Systems, devices and methods for exchanging wireless signals

Abstract

Described herein are systems, devices, and methods for establishing a wireless link between two or more wireless devices. In some variations, the wireless system may include a first device configured to transmit a feedback signal. The system may also include a second device including a transducer array, a processor, and a power source. The transducer array may be configured to receive a feedback signal on one or more transducer elements of the transducer array. The power source may include one or more predetermined transmit voltage levels. The processor may be configured to process the feedback signal received by the one or more transducer elements of the transducer array to generate feedback signal data. The processor may be further configured to determine a transducer array configuration based at least in part on the feedback signal data and the one or more predetermined transmit voltage levels. The second device may be configured to exchange one or more wireless signals with the first device using the transducer array configuration.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 477,131, filed December 23, 2022, the contents of which are incorporated herein by reference in their entirety.

[0002] The devices, systems, and methods herein relate to exchanging wireless signals between two or more wireless devices of a wireless system. [Background technology]

[0003] A wireless system may comprise a wireless link between two or more wireless devices of the wireless system. Such a wireless link may be used for one or more of wireless power transmission, wireless data communication, wireless command transfer, wireless signal transfer, combinations thereof, etc. For example, a wireless implantable device may be wirelessly powered by and communicate wirelessly with an external wireless device. The presence of inhomogeneous media in the wireless link, such as different tissue structures within the body, and / or relative motion between the wireless devices may limit the reliability and / or efficiency of the wireless link. Furthermore, practical constraints such as hardware complexity, device size, cost, and power dissipation may pose additional challenges to implementing a reliable and secure wireless link, particularly for a wireless link between an implantable device and an external wireless device (e.g., a handheld device placed on the patient's skin to wirelessly power the implantable device). Therefore, additional devices, systems, and methods may be desirable for establishing a reliable, efficient, and secure wireless link between two or more wireless devices of a wireless system. Summary of the Invention

[0004] Described herein are systems, devices, and methods for exchanging wireless signals between wireless devices of a wireless system. Generally, the systems may be configured to exchange one or more of wireless power, wireless data, and wireless commands between the wireless devices. In some variations, the systems, devices, and methods described herein enable mitigating variations in the wireless link over time (e.g., due to movement and / or rotation of one wireless device relative to another wireless device within the wireless system) to enable reliable, efficient, and fast wireless powering or charging of another wireless device based on wireless power transmitted by another wireless device within the wireless system. In some variations, the systems, devices, and methods described herein may enable mitigation of multipath interference in heterogeneous tissue media for efficient and / or reliable exchange of wireless signals (e.g., power, data, commands) between a wireless implantable device and an external wireless device. In some variations, a system configured to exchange wireless power or data may include a first device configured to transmit a feedback signal and a second device including a transducer array, a processor, and a power source, wherein the transducer array may be configured to receive a feedback signal on one or more transducer elements of the transducer array, the power source may include one or more predetermined transmit voltage levels, the processor may be configured to process the feedback signal received by the one or more transducer elements of the transducer array to generate feedback signal data and to determine a transducer array configuration based at least in part on the feedback signal data and the one or more predetermined transmit voltage levels of the power source, and the second device may be configured to exchange one or more wireless signals with the first device using the transducer array configuration.

[0005] In some variations, the feedback signal data may include one or more of absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute time of arrival, relative time of arrival, frequency, duration, number of cycles, absolute signal-to-noise ratio, and relative signal-to-noise ratio of the feedback signal received by one or more transducer elements of the transducer array. In some variations, the transducer array configuration may include one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to one or more transducer elements of the transducer array to transmit a wireless signal to the first device.

[0006] In some variations, the processor may be further configured to determine a transmit apodization of the transducer elements of the transducer array. In some variations, the processor may be further configured to select a set of transducer elements of the transducer array configuration based on one or more of the transmit apodization of the transducer elements, one or more predetermined transmit voltage levels of the power source, and one or more predetermined target signal strengths at the first device. In some variations, the transmit apodization of the transducer elements may be proportional to the relative signal strengths of feedback signals received by the transducer elements of the transducer array within one or more frequency bands. In some variations, the transmit apodization of two or more transducer elements may be substantially equal.

[0007] In some variations, the second device may further include one or more transmitter circuits configured to apply transmit signals to one or more transducer elements of the transducer array, and the processor may be configured to determine transmitter circuit data corresponding to the one or more transmitter circuits based at least in part on the feedback signal data. In some variations, the transmitter circuit data may include one or more of efficiency, power dissipation, energy dissipation, current dissipation, voltage drop, heat dissipation, temperature, temperature rise, input power, input energy, input current, input voltage, output power, output energy, output current, and output voltage of the one or more transmitter circuits. In some variations, the processor may be further configured to determine transmit apodization of the transducer elements based at least in part on the transmitter circuit data.

[0008] In some variations, the power source may include a plurality of predetermined transmit voltage levels, the processor may be further configured to select one or more predetermined transmit voltage levels based at least in part on the feedback signal data and the plurality of predetermined transmit voltage levels, and the transducer array configuration may further include the selected one or more predetermined transmit voltage levels for exchanging one or more wireless signals with the first device.

[0009] In some variations, the power source may include a first predetermined transmit voltage level and a second predetermined transmit voltage level, and the transducer array configuration may include the first predetermined transmit voltage level for transmitting wireless power and the second predetermined transmit voltage level for transmitting one or more of wireless data and commands to the first device. In some variations, the first predetermined transmit voltage level may be greater than or substantially equal to the second predetermined transmit voltage level.

[0010] In some variations, the first device may include an implantable medical device, and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first device may include an external wireless device, and the second device may include an implantable medical device configured to be located physically separate from the first device. In some variations, the second device may be further configured to transmit a wireless command to the first device, and the first device may be configured to transmit a feedback signal in response to receiving the wireless command. In some variations, the first device may be configured to transmit the feedback signal at one or more predetermined recurrence intervals.

[0011] Also described is a method for exchanging wireless signals in a wireless system. In some variations, the method for exchanging wireless signals in a wireless system may include the steps of transmitting a feedback signal from a first device of the wireless system to a second device of the wireless system, receiving the feedback signal using one or more transducer elements of a transducer array of the second device, processing the received feedback signal using the one or more transducer elements of the transducer array to generate feedback signal data using a processor of the second device, determining, using the processor of the second device, a transducer array configuration of the second device based at least in part on the feedback signal data and one or more predetermined transmit voltage levels of a power source of the second device, and exchanging one or more wireless signals with the first device using the transducer array configuration of the second device.

[0012] In some variations, the feedback signal data may include one or more of absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute time of arrival, relative time of arrival, frequency, duration, number of cycles, absolute signal-to-noise ratio, and relative signal-to-noise ratio of the feedback signal received by one or more transducer elements of the transducer array. In some variations, the transducer array configuration may include one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to one or more transducer elements of the transducer array to transmit a wireless signal to the first device.

[0013] In some variations, the method may include determining, using a processor of the second device, transmit apodization of transducer elements of the transducer array. In some variations, the method may further include using a processor of the second device to select a set of transducer elements of the transducer array configuration based on one or more of the transmit apodization of the transducer elements, one or more predetermined transmit voltage levels of the power source, and one or more predetermined target signal strengths at the first device. In some variations, the transmit apodization of the transducer elements may be proportional to the relative signal strength of feedback signals received by the transducer elements of the transducer array within one or more frequency bands. In some variations, the transmit apodization of two or more transducer elements may be substantially equal.

[0014] In some variations, the method may further include determining, using a processor of the second device, transmitter circuit data corresponding to one or more transmitter circuits of the second device configured to apply transmit signals to one or more transducer elements of the transducer array based at least in part on the feedback signal data. In some variations, the transmitter circuit data may include one or more of efficiency, power dissipation, energy dissipation, current dissipation, voltage drop, heat dissipation, temperature, temperature rise, input power, input energy, input current, input voltage, output power, output energy, output current, and output voltage of the one or more transmitter circuits. In some variations, the method may further include determining transmit apodization of the transducer elements based at least in part on the transmitter circuit data.

[0015] In some variations, the method may further include using a processor of the second device to select one or more predetermined transmit voltage levels of the power source from a plurality of predetermined transmit voltage levels of the power source based at least in part on the feedback signal data, and exchanging one or more wireless signals with the first device using a transducer array configuration including the selected one or more predetermined transmit voltage levels. In some variations, the method may further include transmitting wireless power to the first device using the first predetermined transmit voltage level of the power source, and transmitting one or more of wireless data and commands to the first device using a second predetermined transmit voltage level of the power source. In some variations, the first predetermined transmit voltage level may be greater than or substantially equal to the second predetermined transmit voltage level.

[0016] In some variations, the first device may include an implantable medical device, and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first device may include an external wireless device, and the second device may include an implantable medical device configured to be located physically separate from the first device. In some variations, the method may further include transmitting one or more wireless commands from the second device to the first device, and transmitting one or more feedback signals from the first device to the second device in response to receiving the one or more wireless commands. In some variations, the method may further include transmitting the feedback signals from the first device at one or more predetermined recurrence intervals.

[0017] Also described are systems configured to exchange wireless power or data based on one or more transmitter circuits. In some variations, the system configured to exchange wireless power or data may include a first device configured to transmit feedback signals, a transducer array, a processor, and a second device including one or more transmitter circuits, where the transducer array may be configured to receive feedback signals on one or more transducer elements of the transducer array, the one or more transmitter circuits may be configured to apply transmit signals to the one or more transducer elements of the transducer array, the processor may be configured to process the feedback signals received by the one or more transducer elements of the transducer array to generate feedback signal data, determine transmitter circuit data corresponding to the one or more transmitter circuits based at least in part on the feedback signal data, and determine a transducer array configuration based at least in part on the feedback signal data and the transmitter circuit data, and the second device may be configured to exchange one or more wireless signals with the first device using the transducer array configuration.

[0018] In some variations, the feedback signal data may include one or more of absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute time of arrival, relative time of arrival, frequency, duration, number of cycles, absolute signal-to-noise ratio, and relative signal-to-noise ratio of the feedback signal received by one or more transducer elements of the transducer array. In some variations, the transmitter circuit data may include one or more of efficiency, power dissipation, energy dissipation, current dissipation, voltage drop, heat dissipation, temperature, temperature rise, input power, input energy, input current, input voltage, output power, output energy, output current, and output voltage of the one or more transmitter circuits.

[0019] In some variations, the transducer array configuration may include one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse width modulation, duty cycle, phase, delay time, frequency, and transmit duration applied to one or more transducer elements of the transducer array to transmit wireless signals to the first device. In some variations, the processor may be further configured to determine a transmit apodization of the transducer elements of the transducer array.

[0020] In some variations, the processor may be further configured to select a set of transducer elements of the transducer array configuration based on one or more of the transmit apodization of the transducer elements, the transmitter circuit data, and one or more predetermined target signal strengths at the first device. In some variations, the transducer array configuration may include one or more transmit voltage levels, and the processor is configured to determine the one or more transmit voltage levels based at least in part on the selected set of transducer elements of the transducer array configuration. In some variations, the transmit apodization of the transducer elements may be proportional to the relative signal strength of feedback signals received by the transducer elements of the transducer array within one or more frequency bands. In some variations, the transmit apodization of two or more transducer elements may be substantially equal.

[0021] In some variations, the first device may include an implantable medical device, and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first device may include an external wireless device, and the second device may include an implantable medical device configured to be located physically separate from the first device. In some variations, the second device may be further configured to transmit one or more wireless commands to the first device, and the first device may be configured to transmit one or more feedback signals in response to receiving the one or more wireless commands. In some variations, the first device may be configured to transmit the feedback signals at one or more predetermined recurrence intervals.

[0022] Also described is a method for exchanging wireless signals in a wireless system based on one or more transmitter circuits. In some variations, the method of exchanging wireless signals in a wireless system may include the steps of transmitting a feedback signal from a first device of the wireless system to a second device of the wireless system, receiving the feedback signal using one or more transducer elements of a transducer array of the second device, processing the received feedback signal using the one or more transducer elements of the transducer array to generate feedback signal data using a processor of the second device, determining, using the processor of the second device, transmitter circuit data corresponding to one or more transmitter circuits of the second device configured to apply transmit signals to the one or more transducer elements of the transducer array based at least in part on the feedback signal data, determining, using the processor of the second device, a transducer array configuration of the second device based at least in part on the feedback signal data and the transmitter circuit data, and exchanging one or more wireless signals with the first device using the transducer array configuration of the second device.

[0023] In some variations, the feedback signal data may include one or more of absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute time of arrival, relative time of arrival, frequency, duration, number of cycles, absolute signal-to-noise ratio, and relative signal-to-noise ratio of the feedback signal received by one or more transducer elements of the transducer array. In some variations, the transmitter circuit data may include one or more of efficiency, power dissipation, energy dissipation, current dissipation, voltage drop, heat dissipation, temperature, temperature rise, input power, input energy, input current, input voltage, output power, output energy, output current, and output voltage of the one or more transmitter circuits.

[0024] In some variations, the transducer array configuration may include one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to one or more transducer elements of the transducer array to transmit a wireless signal to the first device.

[0025] In some variations, the method may further include determining, using a processor of the second device, transmit apodization of transducer elements of the transducer array. In some variations, the method may further include using a processor of the second device to select a set of transducer elements of the transducer array configuration based on one or more of the transmit apodization of the transducer elements, the transmitter circuit data, and one or more predetermined target signal strengths at the first device. In some variations, the method may further include using a processor of the second device to determine one or more transmit voltage levels of the transducer array configuration based at least in part on the selected set of transducer elements of the transducer array configuration. In some variations, the transmit apodization of the transducer elements is proportional to the relative signal strength of feedback signals received by the transducer elements of the transducer array within one or more frequency bands. In some variations, the transmit apodization of two or more transducer elements may be substantially equal.

[0026] In some variations, the first device may include an implantable medical device, and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first device may include an external wireless device, and the second device may include an implantable medical device configured to be located physically separate from the first device. In some variations, the method may further include transmitting a wireless command from the second device to the first device, and transmitting a feedback signal from the first device to the second device in response to receiving the wireless command. In some variations, the method may further include transmitting the feedback signal from the first device at one or more predetermined recurrence intervals.

[0027] Also described are systems configured to exchange wireless power or data. In some variations, the system configured to exchange wireless power or data may include a first device including a first transducer, a first processor, and an energy storage device, where the first transducer may be configured to receive a first wireless power signal from a second device, the energy storage device may be configured to charge based on the received first wireless power signal, the first processor may be configured to determine a charging duration corresponding to one or more predetermined conditions, the first device may be configured to transmit a feedback signal based on the charging duration, the second device may include a second transducer and a second processor, the second transducer may be configured to receive the feedback signal, the second processor may be configured to process the feedback signal to generate feedback signal data and determine a transducer configuration based at least in part on the feedback signal data, and the second device may be configured to transmit a second wireless power signal to the first device based on the transducer configuration.

[0028] In some variations, the predetermined condition may include one or more of: an absolute or relative duration corresponding to the received first wireless power signal, an absolute or relative duration corresponding to a voltage generated by the first device in response to the received first wireless power signal, an absolute or relative duration corresponding to a current generated by the first device in response to the received first wireless power signal, an absolute or relative power level corresponding to the received first wireless power signal, an absolute or relative energy level corresponding to the received first wireless power signal, an absolute or relative voltage level generated by the first device in response to the received first wireless power signal, and an absolute or relative current level generated by the first device in response to the received first wireless power signal. In some variations, the first processor may be configured to digitize the charging duration.

[0029] In some variations, the feedback signal may include one or more of a digital representation of the charge duration and an analog representation of the charge duration. In some variations, the feedback signal data may include one or more of a digital representation of the charge duration, an analog representation of the charge duration, absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute arrival time, relative arrival time, frequency, duration, number of cycles, absolute signal-to-noise ratio, and relative signal-to-noise ratio of the feedback signal received by the second transducer.

[0030] In some variations, the feedback signal data may include one or more of a mean, median, mode, variance, standard deviation, minimum, maximum, percentile, histogram, statistical distribution, frequency, and probability of one or more charging durations corresponding to the one or more first wireless power signals received by the first transducer from the second device.

[0031] In some variations, the transducer configuration may include one or more of an absolute or relative duration of the second wireless power signal, one or more absolute or relative power levels of the second wireless power signal, one or more absolute or relative amplitudes of the second wireless power signal, an absolute or relative pulse repetition frequency of the second wireless power signal, and an absolute or relative frequency of the second wireless power signal.

[0032] In some variations, the duration of the second wireless power signal can be configured to be substantially equal to or greater than the charge durations. In some variations, the duration of the second wireless power signal is configured to be substantially equal to or greater than one or more of one or more average charge durations, one or more median charge durations, one or more modes of charge durations, and values ​​corresponding to one or more charge durations, where the one or more charge durations correspond to the one or more first wireless power signals received by the first transducer from the second device.

[0033] In some variations, the second transducer may include one or more transducer arrays, the one or more transducer arrays including one or more transducer elements. In some variations, the transducer configuration may include one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse repetition rate, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to the one or more transducer elements for transmitting the one or more wireless power signals to the first device.

[0034] In some variations, the first device may include an implantable medical device and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first and second wireless power signals may include ultrasonic or acoustic signals.

[0035] Also described is a method of exchanging wireless signals in a wireless system. In some variations, the method of exchanging wireless signals in a wireless system may include receiving a first wireless power signal at a first transducer of a first device of the wireless system from a second device of the wireless system, where the first device may include an energy storage device and a first processor, and the second device may include a second transducer and a second processor, charging the energy storage device based on the received first wireless power signal, determining, using the first processor, a charging duration corresponding to one or more predetermined conditions, transmitting a feedback signal from the first device to the second device based on the charging duration, receiving the feedback signal using the second transducer, processing the feedback signal to generate feedback signal data using the second processor, determining a transducer configuration based at least in part on the feedback signal data using the second processor, and transmitting a second wireless power signal from the second device to the first device based on the transducer configuration.

[0036] In some variations, the predetermined condition may include one or more of an absolute or relative duration corresponding to the received first wireless power signal, an absolute or relative duration corresponding to the voltage generated by the first device in response to the received first wireless power signal, an absolute or relative duration corresponding to the current generated by the first device in response to the received first wireless power signal, an absolute or relative power level corresponding to the received first wireless power signal, an absolute or relative energy level corresponding to the received first wireless power signal, an absolute or relative voltage level generated by the first device in response to the received first wireless power signal, and an absolute or relative current level generated by the first device in response to the received first wireless power signal.

[0037] In some variations, the method may include digitizing the charge duration using the first processor. In some variations, the method may include encoding or modulating the feedback signal with one or more of a digital representation of the charge duration and an analog representation of the charge duration using the first processor.

[0038] In some variations, the feedback signal data may include one or more of: a digital representation of a charging duration, an analog representation of a charging duration, an absolute amplitude or magnitude, a relative amplitude or magnitude, an absolute signal strength, a relative signal strength, a signal energy in one or more frequency bands, apodization, an absolute phase, a relative phase, an absolute delay time, a relative delay time, an absolute arrival time, a relative arrival time, a frequency, a duration, a number of cycles, an absolute signal-to-noise ratio, and a relative signal-to-noise ratio of the feedback signal received by the second transducer. In some variations, the feedback signal data may include one or more of a mean, median, mode, variance, standard deviation, minimum, maximum, percentile, histogram, statistical distribution, frequency, and probability of one or more charging durations corresponding to the one or more first wireless power signals received by the first transducer from the second device.

[0039] In some variations, the transducer configuration may include one or more of an absolute or relative duration of the second wireless power signal, one or more absolute or relative power levels of the second wireless power signal, one or more absolute or relative amplitudes of the second wireless power signal, an absolute or relative pulse repetition frequency of the second wireless power signal, and an absolute or relative frequency of the second wireless power signal.

[0040] In some variations, the duration of the second wireless power signal can be configured to be substantially equal to or greater than the charge durations. In some variations, the duration of the second wireless power signal can be configured to be substantially equal to or greater than one or more of one or more average charge durations, one or more median charge durations, one or more modes of charge durations, and values ​​corresponding to one or more charge durations, where the one or more charge durations correspond to the one or more first wireless power signals received by the first transducer from the second device.

[0041] In some variations, the second transducer may include one or more transducer arrays, the one or more transducer arrays including one or more transducer elements. In some variations, the transducer configuration may include one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse repetition rate, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to the one or more transducer elements for transmitting the one or more wireless power signals to the first device.

[0042] In some variations, the first device may include an implantable medical device and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first and second wireless power signals may include ultrasonic or acoustic signals.

[0043] Also described are devices configured for charging. In some variations, the wireless implantable device may include a transducer configured to receive a wireless power signal, a power supply circuit coupled to the transducer and configured to recover at least a portion of the wireless power signal received by the transducer, an energy storage device coupled to the power supply circuit and configured to charge based on the portion of the wireless power signal recovered by the power supply circuit, and a processor coupled to one or more of the power supply circuit, the energy storage device, and the transducer, wherein the processor may be configured to determine charging parameters corresponding to one or more predetermined conditions and adjust parameters of one or more of the power supply circuit, the energy storage device, and the transducer based at least in part on the charging parameters.

[0044] In some variations, the power supply circuit may include one or more of an AC-DC converter, a reconfigurable AC-DC converter, a rectifier, a reconfigurable rectifier, a DC-DC converter, a reconfigurable DC-DC converter, a linear regulator, a switching regulator, a switched capacitor voltage regulator, a boost converter, a buck converter, a switched capacitor DC-DC converter, a charging circuit, a battery charging circuit, a current source, a voltage source, a constant current (CC) charging circuit, a constant voltage (CV) charging circuit, a trickle charging circuit, a pulse charging circuit, a current limiter circuit, and a voltage limiter circuit. In some variations, the energy storage device may include one or more of a battery, a rechargeable battery, a capacitor, and an inductor.

[0045] In some variations, the charging parameters may include one or more of an absolute or relative duration corresponding to the wireless power signal received by the transducer, an absolute or relative duration of the voltage generated by the transducer in response to the received wireless power signal, an absolute or relative duration of the current generated by the transducer in response to the received wireless power signal, an absolute or relative duration corresponding to the wireless power signal recovered by the power circuit, an absolute or relative duration of the voltage generated by the power circuit in response to the recovered wireless power signal, an absolute or relative duration of the current generated by the power circuit in response to the recovered wireless power signal, an absolute or relative duration corresponding to charging of the energy storage device, and an absolute or relative charge rate of the energy storage device. In some variations, the charging parameters may include an absolute or relative voltage level corresponding to the energy storage device, an absolute or relative current level corresponding to the energy storage device, an absolute or relative power level corresponding to the energy storage device, an absolute or relative energy level corresponding to the energy storage device, an absolute or relative voltage level corresponding to the power supply circuit, an absolute or relative current level corresponding to the power supply circuit, an absolute or relative power level corresponding to the power supply circuit, an absolute or relative voltage level corresponding to the transducer, an absolute or relative current level corresponding to the transducer, and an absolute or relative power level corresponding to the transducer.

[0046] In some variations, the processor may be configured to digitize the charging parameters. In some variations, the power supply circuit parameters adjusted by the processor may include one or more of a charging current level, a charging voltage level, a charging mode, a switching frequency of the AC-DC converter, a switching frequency of the DC-DC converter, a load current of the AC-DC converter, a load current of the DC-DC converter, a configuration of a matching network, and a signal applied to a switch coupled to the power supply circuit. In some variations, the energy storage device parameters adjusted by the processor may include one or more of a capacitor selection, a battery selection, a number of capacitors, a number of batteries, a capacitance value, and a signal applied to a switch coupled to the energy storage device. In some variations, the transducer parameters adjusted by the processor may include one or more of a transducer element selection, an impedance coupled to the transducer, a matching network coupled to the transducer, and a signal applied to a switch coupled to the transducer.

[0047] In some variations, the transducer may include an acoustic transducer and the wireless power signal may include an acoustic power signal. In some variations, the acoustic transducer may include an ultrasonic transducer and the acoustic power signal may include an ultrasonic power signal.

[0048] Also described are methods of charging a wireless device. In some variations, the method of charging a wireless implantable device may include the steps of receiving a wireless power signal using a transducer of the wireless implantable device, recovering at least a portion of the received wireless power signal using a power supply circuit coupled to the transducer, charging an energy storage device coupled to the power supply circuit based on the recovered portion of the received wireless power signal, determining charging parameters corresponding to one or more predetermined conditions using a processor coupled to one or more of the power supply circuit, the energy storage device, and the transducer, and adjusting, using the processor, parameters of one or more of the power supply circuit, the energy storage device, and the transducer based at least in part on the charging parameters.

[0049] In some variations, the power supply circuit may include one or more of an AC-DC converter, a reconfigurable AC-DC converter, a rectifier, a reconfigurable rectifier, a DC-DC converter, a reconfigurable DC-DC converter, a linear regulator, a switching regulator, a switched capacitor voltage regulator, a boost converter, a buck converter, a switched capacitor DC-DC converter, a charging circuit, a battery charging circuit, a current source, a voltage source, a constant current (CC) charging circuit, a constant voltage (CV) charging circuit, a trickle charging circuit, a pulse charging circuit, a current limiter circuit, and a voltage limiter circuit. In some variations, the energy storage device may include one or more of a battery, a rechargeable battery, a capacitor, and an inductor.

[0050] In some variations, the charging parameters may include one or more of an absolute or relative duration corresponding to the wireless power signal received by the transducer, an absolute or relative duration of the voltage generated by the transducer in response to the received wireless power signal, an absolute or relative duration of the current generated by the transducer in response to the received wireless power signal, an absolute or relative duration corresponding to the wireless power signal recovered by the power circuit, an absolute or relative duration of the voltage generated by the power circuit in response to the recovered wireless power signal, an absolute or relative duration of the current generated by the power circuit in response to the recovered wireless power signal, an absolute or relative duration corresponding to charging of the energy storage device, and an absolute or relative charge rate of the energy storage device. In some variations, the charging parameters may include an absolute or relative voltage level corresponding to the energy storage device, an absolute or relative current level corresponding to the energy storage device, an absolute or relative power level corresponding to the energy storage device, an absolute or relative energy level corresponding to the energy storage device, an absolute or relative voltage level corresponding to the power supply circuit, an absolute or relative current level corresponding to the power supply circuit, an absolute or relative power level corresponding to the power supply circuit, an absolute or relative voltage level corresponding to the transducer, an absolute or relative current level corresponding to the transducer, and an absolute or relative power level corresponding to the transducer. In some variations, the processor may be configured to digitize the charging parameters.

[0051] In some variations, the power supply circuit parameters adjusted by the processor may include one or more of a charging current level, a charging voltage level, a charging mode, a switching frequency of the AC-DC converter, a switching frequency of the DC-DC converter, a load current of the AC-DC converter, a load current of the DC-DC converter, a configuration of a matching network, and a signal applied to a switch coupled to the power supply circuit. In some variations, the energy storage device parameters adjusted by the processor may include one or more of a capacitor selection, a battery selection, a number of capacitors, a number of batteries, a capacitance value, and a signal applied to a switch coupled to the energy storage device. In some variations, the transducer parameters adjusted by the processor may include one or more of a transducer element selection, an impedance coupled to the transducer, a matching network coupled to the transducer, and a signal applied to a switch coupled to the transducer.

[0052] In some variations, the transducer may include an acoustic transducer and the wireless power signal may include an acoustic power signal. In some variations, the acoustic transducer may include an ultrasonic transducer and the acoustic power signal may include an ultrasonic power signal. [Brief explanation of the drawings]

[0053] [Figure 1] 1 is a schematic block diagram of an exemplary variation of a wireless system; [Figure 2] 1 is a cross-sectional schematic diagram of an exemplary variation of a wireless system. [Figure 3] 10 is a flowchart of an exemplary variation of a method for exchanging wireless signals with a device based on a feedback signal. [Figure 4] FIG. 10 is a timing diagram of an exemplary variation of a feedback signal and feedback signal data. [Figure 5]10 is a flowchart of an exemplary variation of another method for exchanging wireless signals with a device based on a feedback signal. [Figure 6] FIG. 10 is a timing diagram of an exemplary variation of a received feedback signal whose amplitude has been settled. [Figure 7] 1A-1C are cross-sectional schematic diagrams of exemplary variations in ultrasound beams and transmit signal strength of an ultrasound transducer array. [Figure 8] 10 is a flowchart of an exemplary variation of a method for exchanging wireless signals with a device based on a link scan signal. [Figure 9] 4 is a timing diagram of an exemplary variation of signals used in a method of exchanging wireless signals with a device. [Figure 10] 10 is a flowchart of an exemplary variation of a method for exchanging wireless signals with a device based on a link scan signal and a feedback signal. [Figure 11] 4 is a flowchart of an exemplary variation of a method for decoding a data signal in a wireless system. [Figure 12] 3 is a timing diagram of an exemplary variation of signals used in a method for decoding a data signal in a wireless system. [Figure 13] FIG. 10 is a timing diagram of another exemplary variation of signals used in a method for decoding a data signal in a wireless system. [Figure 14] 4 is a timing diagram of an exemplary variation of signals used in a method for decoding a data signal in a wireless system based on a combined data signal and matched filtering; [Figure 15] 10 is a flowchart of another exemplary variation of a method for decoding a data signal in a wireless system. [Figure 16] 4 is a flowchart of an exemplary variation of a method for decoding a data signal in a wireless system based on a predistorted data signal. [Figure 17]10 is a flowchart of an exemplary variation of a method for decoding a data signal in a wireless system based on a delayed and summed data signal. [Figure 18] 4 is a flowchart of an exemplary variation of a method for calibrating a wireless system. [Figure 19] 1 is a schematic block diagram of an exemplary variation of a wireless system configured for calibration; [Figure 20] 1 is a schematic block diagram of an example variation of a wireless system configured to exchange wireless signals; [Figure 21] 10 is an exemplary variation of a method for exchanging wireless signals with a device based on one or more predetermined transmit voltage levels. [Figure 22] 1 is an exemplary variation of a method for exchanging wireless signals with a device using a transmitter circuit. [Figure 23] 10 is an exemplary variation of a method for exchanging wireless signals with a device based on charging duration. [Figure 24] 1 is an exemplary variation of a method for charging a wireless device. DETAILED DESCRIPTION OF THE INVENTION

[0054] I. System A. Overview Generally, described herein are systems, devices, and methods for establishing a wireless link between two or more wireless devices of a wireless system. Generally, the wireless system may include one or more wireless monitors or wireless implantable devices or implantable medical devices and one or more wireless devices or external wireless devices. The wireless implantable devices may be wirelessly powered or charged by the external wireless device using wireless power transmission. The wireless implantable devices may also wirelessly communicate data and / or commands bidirectionally with the external wireless device.

[0055] 1 is a schematic block diagram of an exemplary variation of a wireless system 100 including a wireless implantable device 110 and a wireless device 114, each of the components of which is described in more detail herein. The wireless device 114 may transmit wireless downlink signals 140 to the wireless implantable device 110, including one or more of power, data, commands, signals, combinations thereof, etc. The wireless device 114 may receive wireless uplink signals 150 from the wireless implantable device 110, including one or more of power, data, commands, signals, combinations thereof, etc. Each of these signals is also described in more detail herein.

[0056] 2 illustrates an exemplary variation of a system including a first device (210) implanted within the heart surrounded by tissue (270) and the rib cage or ribs (272), along with an external second device (214) comprising one or more transducer arrays (220) including one or more transducer elements (222). In some variations, the second device (214) may be positioned on the patient's chest. The second device (214) may be configured to transmit downlink signals (242) to the first device (210), including one or more of an interrogation signal, a power signal, a downlink command, a downlink data signal, etc. The first device (210) may be configured to generate wireless signals (252), including one or more of a feedback signal, an uplink data signal, a reflected signal from the first device (210), a backscattered signal from the first device (210), etc. In some variations, the first device (210) may move relative to the second device (214) along a spatial path (280) or a periodic orbit.

[0057] In some variations, the systems, devices, and methods disclosed herein may include one or more of the systems, devices, and methods described in International Application No. PCT / US2020 / 027468, filed April 9, 2020, International Application No. PCT / US2020 / 041696, filed July 10, 2020, International Application No. PCT / US2021 / 036258, filed June 7, 2021, and International Application No. PCT / US2022 / 035574, filed June 29, 2022, the contents of each of which are incorporated herein by reference in their entirety.

[0058] B. Wireless Monitor In general, a wireless monitor may be configured to perform one or more functions, including, but not limited to, sensing, monitoring, stimulating, delivering therapy, combinations thereof, etc. In some variations, a wireless monitor may receive and / or transmit one or more of wireless power, wireless data, wireless commands, and wireless signals to / from an external wireless device or another wireless monitor. For example, a wireless monitor may be configured to monitor, measure, and / or process one or more physiological parameters of a patient.

[0059] In some variations, a wireless monitor described herein may be configured to perform only a subset of the measurement, processing, data storage, and / or signal transmission steps described herein. In some variations, a wireless monitor may include only a subset of the components or blocks described herein. For example, in some variations, a wireless monitor may include only a transducer, a power circuit, and a processor. As another example, in some variations, a wireless monitor may include one or more transducers, a power circuit, a processor, a sensor, and a memory. In some variations, a wireless monitor may include other components in addition to those described herein (e.g., sensors, stimulation devices, delivery and / or anchoring mechanisms, mechanical parts that enable deployment within a body or organ, or other components).

[0060] In some variations, the wireless monitor may be implanted within the patient's or animal's body. In some variations, the wireless monitor may be coupled to (e.g., attached to) an implantable device or any part of an implantable device as described herein. For example, one or more wireless monitors may be attached to a prosthetic heart valve or stent. As another example, one or more wireless monitors may be attached to one or more of a pulse generator and / or one or more leads of a pacemaker, implantable cardioverter-defibrillator, and / or cardiac resynchronization therapy device. In some variations, the wireless monitor may be implanted in or on one or more of a cardiac structure (e.g., heart valve, heart chamber), a vascular structure (e.g., pulmonary artery, any other blood vessel), a body lumen, body cavity, tissue, organ, etc.

[0061] In some variations, the wireless monitor may include one or more of the components or blocks described herein for the implantable device. In some variations, the implantable device may include one or more of the components or blocks described herein for the wireless monitor. For example, the wireless monitor may include one or more of a transducer, a power supply circuit, an energy storage device, a sensor, a processor, a memory, a wireless transmitter, a wireless receiver, a multiplexer circuit, combinations thereof, etc.

[0062] C. Implantable Devices In general, the implantable devices, wireless implantable devices, or implantable medical devices described herein may be configured to be implanted within a patient's or animal's body. In some variations, the implantable device may be a wireless implantable device. In some variations, the wireless implantable device may receive and / or transmit one or more of wireless power, wireless data, wireless commands, and wireless signals to / from an external wireless device or another wireless implantable device. In some variations, the wireless implantable device may be configured to perform one or more functions including, but not limited to, sensing, monitoring, stimulating, delivering therapy, combinations thereof, etc. In some variations, the wireless implantable device may be a wireless monitor.

[0063] In some variations, the implantable device may include one or more of a prosthetic heart valve, a prosthetic heart valve conduit, a valve leaflet coaptation device, annuloplasty ring, a valve repair device (e.g., clip, pledget), a septal defect occluder, an atrial appendage occluder, a ventricular assist device, a pacemaker (e.g., including a lead, a pulse generator), an implantable cardioverter-defibrillator (e.g., including a lead, a pulse generator), a cardiac resynchronization therapy device (e.g., including a lead, a pulse generator), an implantable cardiac monitor, a stent (e.g., a coronary or peripheral stent, a textile stent, a metallic stent), a stent-graft, a scaffold, an embolic protection device, an embolic coil, an intravascular plug, a vascular patch, a vascular closure device, an atrial shunt, a parachute device for treating heart failure, a loop electrocardiograph, combinations thereof, and the like. For example, the prosthetic heart valve may include one or more of a transcatheter prosthetic valve (THV), a self-expanding THV, a balloon-expandable THV, a surgical cardiac bioprosthetic valve, a mechanical cardiac valve, and the like.

[0064] Generally, the implantable devices described herein may be located in or near (e.g., adjacent, proximal to) any region of the body, including, but not limited to, a heart valve (e.g., aortic valve, mitral valve), a heart chamber (e.g., left ventricle or LV, left atrium or LA, right ventricle or RV, right atrium or RA), a blood vessel (e.g., pulmonary artery, aorta, superficial femoral artery, coronary artery, pulmonary vein, etc.), cardiac tissue (e.g., myocardium or wall, septum), gastrointestinal tract (e.g., stomach, esophagus), bladder, combinations thereof, etc.

[0065] 1, the wireless implantable device 110 may include a transducer 120, a processor 130, and a power circuit 160. The wireless device 114 may include a transducer 120 and a processor 130. Each of these components is described in more detail herein.

[0066] a. Transducer In general, the transducers described herein may be configured to convert between wireless energy modalities and electrical signals. In some variations, a transducer of a device may be configured to exchange one or more of wireless power, wireless signals, wireless data, wireless commands, combinations thereof, etc. with another device and / or with another transducer of the same device. In some variations, the transducer (120) may be configured to receive and / or transmit signals as well as convert those signals to and / or from electrical signals using one or more of mechanical waves (e.g., acoustic, ultrasonic or ultrasound, vibration), magnetic fields (e.g., induction), electric fields (e.g., capacitance), electromagnetic waves (e.g., radio frequency or RF, light), galvanic coupling, surface waves, combinations thereof, etc. The transducer may be included in one or more of a wireless implantable device, a wireless monitor, an external wireless device, etc. (e.g., any of the devices described herein), as described herein.

[0067] In some variations, the transducer (120) may comprise one or more of an ultrasonic transducer, a radio frequency (RF) transducer (e.g., coil, RF antenna), a capacitive transducer, combinations thereof, etc. In some variations, the ultrasonic transducer may include one or more of a piezoelectric device, a capacitive micromachined ultrasonic transducer (CMUT), a piezoelectric micromachined ultrasonic transducer (PMUT), combinations thereof, etc. In some variations, the ultrasonic transducer may convert pressure and / or force into an electrical signal and / or vice versa. In some variations, the transducer (120) may include one or more ultrasonic transducers, which may be of one or more types, including, but not limited to, piston (e.g., rod, plate), cylindrical, ring, spherical (e.g., shell), bending (e.g., bar, diaphragm), bending tension, combinations thereof, etc. In some variations, the piezoelectric device may be made from one or more of lead zirconate titanate (PZT), PMN-PT, barium titanate (BaTiO), polyvinylidene difluoride (PVDF), lithium niobate (LiNbO), any derivatives thereof, etc. In some variations, the radio frequency (RF) transducer may be configured to transmit and / or receive near-field and / or far-field (e.g., far-field) signals. For example, the RF antenna may be configured for far-field transmission and / or reception of power, data, and / or other signals. The RF coil may be configured for near-field (e.g., inductive) transmission and / or reception of power, data, and / or other signals.

[0068] In some variations, the transducer (120) may include one or more ultrasound transducers for one or more of receiving wireless power, transmitting / receiving data to / from another wireless device, and transmitting / receiving signals to / from another wireless device. For example, the ultrasound transducer of the wireless monitor may be designed to operate at a frequency between about 20 kHz and about 20 MHz to receive power from an external wireless device. Operation within such a frequency range may be useful for miniaturizing the ultrasound transducer to millimeter or submillimeter dimensions, which may be advantageous for integrating one or more wireless monitors onto another implantable device (e.g., a transcatheter prosthetic valve, a stent). In some variations, the ultrasound transducer may have an impedance with a real part on the order of about several hundred ohms to several hundred kiloohms (e.g., between about 100 Ω and about 500 kΩ). In some variations, the ultrasound transducer may have an impedance with a real part on the order of several tens of ohms.

[0069] In some variations, the transducer 120 may include a single transducer element (e.g., an ultrasonic piezoelectric device), which may enable miniaturization of the wireless monitor. In some variations, the single transducer element may be configured to receive a power signal (e.g., an ultrasonic power source) transmitted from an external wireless device and convert the signal into electrical power. Additionally or alternatively, the single transducer element may be configured to receive downlink data (e.g., using an ultrasonic signal) and / or other signals from an external wireless device or wireless monitor. In some variations, the single transducer element may be configured to transmit uplink data (e.g., using an ultrasonic signal) and / or other signals to an external wireless device or wireless monitor. In some variations, the single transducer element may include an ultrasonic transducer and may be configured to perform one or more of: receiving ultrasonic power from another device (e.g., an external wireless device), performing bidirectional ultrasonic data communication or signal exchange (e.g., uplink and downlink) with another device (e.g., an external wireless device, a wireless monitor), combinations thereof, etc.

[0070] In some variations, the transducer (120) may include more than one transducer element or one or more arrays of transducer elements. For example, the transducer (120) may include an array of ultrasound transducer elements. As another example, a first transducer element may include an RF coil and may be configured to receive power and communicate data and / or other signals with an external wireless device. A second transducer element may include an ultrasound transducer configured to transmit and / or receive other signals. In some variations, the ultrasound transducer of the external wireless device may include one or more arrays of ultrasound transducer elements and may be configured to generate ultrasound beams for one or more of power transmission, data transfer, and / or exchange of other signals with a wireless monitor.

[0071] In some variations, a transducer (120) including multiple transducer elements may be configured to perform a predetermined set of functions, for example, a first transducer element may be configured to recover wireless power, a second transducer element may be configured to receive data and / or signals, and a third transducer element may be configured to transmit data and / or signals.

[0072] The reduced size of the transducer may allow for miniaturization of the wireless monitor or monitors, which may be useful for attaching the wireless monitor or monitors to another implantable device, such as a cardiac implantable device (e.g., a prosthetic heart valve), and / or may allow for minimally invasive delivery of the wireless monitor or wireless implantable device into the body (e.g., via percutaneous or transcatheter techniques). In some variations, the transducer may be less than about 10 cm 3 It may have a volume of less than 1000 .mu.m.

[0073] In some variations, a transducer (e.g., an ultrasound transducer) of a wireless monitor may be directed or angled toward one or more of a transducer of another wireless monitor, a transducer of an external wireless device, a combination thereof, etc. This may improve the reliability of transmitting / receiving power, data, and / or other signals between the wireless monitor and the external wireless device, or between two wireless monitors.

[0074] In some variations, a wireless monitor may include one or more transducers. In some variations, one or more wireless monitors may share one or more transducers. For example, in some variations, more than one wireless monitor may be connected to a transducer (e.g., an RF coil) by more than one feed or port. For example, a stent device may include an RF coil with two or more feeds or ports to which two or more wireless monitors may be connected. In some variations, two or more wireless monitors may be connected to a single feed or port of a transducer (e.g., two or more wireless monitors may be connected in parallel at a single feed or port of an RF coil).

[0075] b.Power circuit In general, the power supply circuits described herein may be configured to recover, regulate, detect, select, combine, store, and / or supply power or energy, or charge an energy storage device. For example, the power supply circuit may be configured to recover wireless power received by the transducer and convert it into usable energy to power one or more circuit blocks of the wireless monitor. In some variations, the power supply circuit may include one or more energy storage elements (e.g., batteries, capacitors) configured to store the energy received by the transducer. The power supply circuit may be further configured to control (e.g., stabilize, limit) the power supplied to one or more components (e.g., circuit blocks) of the wireless monitor. The combination of the power supply circuit and transducer described herein may be useful for transmitting power, data, and / or signals between an external wireless device and one or more low-power devices (e.g., a wireless monitor) implanted within a patient. In some variations, the power supply circuit (160) may include one or more of a power recovery circuit, a power management circuit, a power detector circuit, a power distribution circuit, combinations thereof, etc.

[0076] In some variations, the power supply circuit (160) may include an AC-DC converter configured to convert an alternating current (AC) voltage into a DC voltage. For example, the power supply circuit (160) may include a rectifier configured to convert the AC voltage at the terminals of the transducer into a DC voltage rail. The rectifier may include one or more of a passive rectifier, an active rectifier, a passive voltage doubler, combinations thereof, etc. In some variations, the power supply circuit (160) may include a DC-DC converter configured to convert a DC voltage rail into another DC voltage rail. For example, the power supply circuit (160) may include a switched capacitor DC-DC converter, a charge pump, combinations thereof, etc. In some variations, the power supply circuit (160) may include a voltage regulator (e.g., a low dropout regulator (LDO) circuit, a voltage clamp circuit) configured to generate a regulated or constant DC voltage rail. In some variations, the power supply circuit (160) may include one or more reference generating circuits, such as a current reference circuit, a bandgap reference circuit, a voltage reference circuit, or a combination thereof.

[0077] In some variations, the power supply circuitry (160) may be configured to recover and / or couple wireless power received by multiple transducer elements disposed on the wireless monitor. For example, such power supply circuitry connected to multiple transducer elements may perform one or more of AC power coupling, DC power coupling, DC voltage coupling, DC current coupling, any combination thereof, etc.

[0078] In some variations, the power supply circuit (160) may include a power detector circuit configured to detect or measure power and / or energy at one or more of its inputs. In some variations, the power detector circuit may be configured to provide one or more supply voltages or powers within the wireless monitor in response to detecting a power source at one or more inputs. In some variations, the power detector circuit may include one or more of a power ORing circuit, a power combining circuit, a power selection circuit, one or more diodes, and one or more switches, as described herein. A power ORing circuit, a power combining circuit, or a power selection circuit generally operates with multiple power sources at its inputs and may generate one or more power sources or voltage supplies at its output. For example, a power combining circuit may combine power from multiple power sources. For example, a power selection circuit may select power from one of the multiple power sources.

[0079] In some variations, the power supply circuit (160) may comprise an energy storage device including one or more of a capacitor, a supercapacitor, a rechargeable or secondary battery, a non-rechargeable or primary battery, combinations thereof, etc. In some variations, the power supply circuit (160) may include a rechargeable battery for energy storage with a capacitor in parallel with the battery, which may sink / source at least a portion of the current during charging / discharging transients of the rechargeable battery.

[0080] In some variations, the power supply circuit (160) may be separate from the energy storage device. In some variations, the power supply circuit (160) may not include any energy storage device, and the wireless monitor may be powered by another device (e.g., an external wireless device, another wireless monitor, etc.) while the wireless monitor is in operation. In some variations, power may be supplied to the wireless monitor until the wireless monitor completes a predetermined set of functions, and the wireless monitor may remain inactive until powered again. A power supply circuit without an energy storage device may allow for a reduction in the size of the power supply circuit and the wireless monitor.

[0081] In some variations, the power supply circuit (160) may include one or more charging circuits for charging one or more energy storage devices (e.g., capacitors, batteries) of a device (e.g., a wireless implantable device). In some variations, the power supply circuit (160) may include a battery charging circuit or battery charger (e.g., a charging current source, a charging voltage source, a constant current or CC charging circuit, a constant voltage or CV charging circuit, combinations thereof, etc.), a capacitor charging circuit, combinations thereof, etc. In some variations, the power supply circuit (160) may include a matching network (e.g., composed solely of capacitors, composed of capacitors, inductors, and / or resistors, etc.) configured to achieve a preferred impedance or power source match for a transducer that may be configured to receive wireless power. This may be advantageous to improve the efficiency of wireless power recovery and enable faster charging of an energy storage device based on the recovered wireless power.

[0082] In some variations, the power supply circuit (160) may be adaptive or adjustable. For example, in some variations, the processor of the wireless device or wireless implantable device may be configured to adjust or adapt parameters of the power supply circuit (e.g., adjust the charging current level, charging voltage level, charging mode such as CC or CV, boost converter or active rectifier switching frequency, boost converter or rectifier load current, matching network, combinations thereof, etc.) based on predetermined conditions, as described herein.

[0083] In some variations, the systems, devices, and methods disclosed herein may include one or more of the systems, devices, and methods described in U.S. Patent No. 9,544,068, filed May 13, 2014; U.S. Patent No. 10,177,606, filed September 30, 2016; U.S. Patent No. 10,014,570, filed December 7, 2016; and International Application No. PCT / US2020 / 041696, filed July 10, 2020, the contents of each of which are incorporated herein by reference in their entirety.

[0084] c. Energy storage devices In general, the energy storage devices described herein may be configured to store energy that may be used to power one or more circuit blocks of a wireless implantable device or monitor. In some variations, the energy storage device may include one or more of a capacitor, a supercapacitor, a rechargeable or secondary battery, a non-rechargeable or primary battery, a combination thereof, or the like.

[0085] In some variations, the energy storage device of the wireless implantable device (110) may comprise a battery (e.g., a rechargeable battery) having a capacity of less than about 100 milliwatt-hours (about 360 joules). In some variations, the energy storage device of the wireless implantable device (110) may comprise a battery (e.g., a rechargeable battery) having a capacity of less than about 10 milliwatt-hours (36 joules). Such batteries may be significantly smaller in size than batteries used in conventional implantable devices such as pacemakers or deep brain stimulators, allowing the wireless implantable device (110) to be miniaturized to dimensions on the order of one centimeter, one millimeter, or even less than one millimeter.

[0086] In some variations, the energy storage device of the wireless implantable device (110) may comprise a capacitor having a capacitance between about 0.1 nanofarads (nF) and about 100 microfarads (μF). Such a capacitor may be on-chip (i.e., contained within an integrated circuit) or off-chip. In some variations, the wireless implantable device (110) may include multiple energy storage devices, each of which may include any type of energy storage device described herein.

[0087] In some variations, the energy storage device may be adaptive or adjustable. For example, in some variations, the processor of the wireless device or wireless implantable device may be configured to adjust or adapt parameters of the energy storage device (e.g., select capacitors configured to charge, adjust the number of storage capacitors, adjust capacitance values, select batteries configured to charge, adjust the number of batteries, control switches connected to a network of capacitors and / or batteries, combinations thereof, etc.) based on predetermined conditions, as described herein.

[0088] d. Sensor In general, the sensors described herein may be configured to sense or measure one or more parameters. In some variations, the sensors may be pressure sensors, flow sensors, transducers (e.g., ultrasound transducers, infrared / light photodiodes, infrared / light LEDs, RF antennas, RF coils), temperature sensors, electrical sensors (e.g., using electrodes to measure impedance, electromyogram or EMG, electrocardiogram or ECG, etc.), magnetic sensors (e.g., RF coils), electromagnetic sensors (e.g., infrared photodiodes, light photodiodes, RF antennas), neural sensors (e.g., for sensing neural action potentials), force sensors (e.g., strain gauges), flow sensors, etc. Or it may include one or more of a velocity sensor (e.g., hot wire anemometer, vortex flow meter), an acceleration sensor (e.g., accelerometer), a chemical sensor (e.g., pH sensor, protein sensor, glucose sensor), an oxygen sensor (e.g., pulse oximetry sensor, myocardial oxygen consumption sensor), an audio sensor (e.g., microphone for detecting heart murmurs, prosthetic valve noises, auscultation), a sensor for sensing other physiological parameters (e.g., sensors for sensing heart rate, respiratory rate, arrhythmia, cardiac wall motion), a stimulator (e.g., for stimulation and / or pacing functions), combinations thereof, and the like.

[0089] In some variations, the one or more pressure sensors (alternatively referred to as pressure transducers) may be used for one or more of monitoring cardiac function and / or heart failure (e.g., measuring pressure in the LV, RV, LA, RA, pulmonary artery, aorta, etc.), monitoring prosthetic valves (e.g., valve pressure gradients to monitor stenosis), monitoring stent devices (e.g., measuring intraluminal pressure), estimating and / or verifying blood flow velocity measurements (e.g., using Bernoulli's equation), combinations thereof, etc. In some variations, the one or more pressure sensors may be of the following types, such as, but not limited to, absolute pressure sensors, gauge pressure sensors, sealed pressure sensors, differential pressure sensors, atmospheric pressure sensors, combinations thereof, etc. In some variations, the one or more pressure sensors may be based on one or more pressure-sensitive techniques, such as, but not limited to, resistive (e.g., piezoresistive, using a strain gauge or membrane to create a pressure-sensitive resistance, etc.), capacitive (e.g., using a diaphragm or membrane to create a pressure-sensitive capacitance, etc.), piezoelectric, optical, resonant (e.g., a pressure-sensitive resonant frequency of a structure, etc.), combinations thereof, etc. In some variations, the pressure sensors may be fabricated using microelectromechanical systems (MEMS) techniques. In some variations, the pressure sensors may include one or more of a stagnation pressure sensor, a static pressure sensor, etc.

[0090] In some variations, the sensor may comprise a stimulator used to stimulate one or more muscles and / or neurons or nerves of cardiac tissue (e.g., HIS bundle, atrioventricular node), heart chamber (e.g., septum, lateral wall of the LV), vascular wall, combinations thereof, etc. For example, one or more stimulators may be used to stimulate the LV wall for pacing and / or cardiac resynchronization. In some variations, the stimulator may include an electrical stimulator (e.g., electrode), an ultrasound stimulator (e.g., ultrasound transducer), a light stimulator (e.g., light LED), an infrared stimulator (e.g., infrared LED), a thermal stimulator (e.g., electrode that generates heat in tissue), combinations thereof, etc.

[0091] In some variations, the sensor may include one or more of a sensing transducer and a sensing circuit, which may include one or more of a signal conditioning circuit, an analog front end (AFE), an amplifier, a front-end amplifier (FEA), an instrumentation amplifier, a filter, an anti-aliasing filter, an analog-to-digital converter (ADC), a comparator, a reference generator, a power supply generator, a digital controller, a bias circuit, a clock circuit, a timer circuit, an oscillator, combinations thereof, etc.

[0092] In some variations, the sensor may be configured to measure a physiological parameter of the patient, which may include one or more of intracardiac pressure, intravascular pressure, blood pressure, blood velocity, blood flow, blood oxygen level, heart rate, respiratory rate, temperature, voltage (e.g., voltage generated by tissue such as ECG, EMG, etc.), current, impedance (e.g., tissue impedance, thoracic impedance, etc.), nerve signals, heart sounds, combinations thereof, etc.

[0093] e. Processor Generally, a processor (e.g., a CPU) described herein may receive, transmit, and / or process data and / or other signals and / or control one or more components of the system (e.g., control one or more circuit blocks of a wireless monitor). The processor may be configured to receive, process, compile, calculate, store, access, read, write, transmit, and / or generate data and / or other signals. Additionally or alternatively, one or more blocks of the processor of the wireless monitor may be configured to control one or more other blocks of the processor and / or one or more components of the wireless monitor (e.g., transducer, power circuit, memory, sensor, wireless transmitter, wireless receiver, etc.). The processor may be included in one or more of the wireless monitor, wireless implantable device, external wireless device, etc., as described herein.

[0094] In some variations, the processor 130 of the wireless device 114 may be configured to process signals (e.g., feedback signals) and take actions (e.g., generate feedback signal data). In some variations, the processor 130 of the wireless device 114 may be configured to process signals (e.g., feedback signals), generate data (e.g., feedback signal data), and determine the wireless device's transducer configuration (e.g., signal strengths and delays applied to elements of a transducer array) to power the wireless implantable device 110, as described in detail herein. For example, the processor may include an amplifier, a phase detector, a frequency detector, a digital signal processor, an analog signal processor, an integrator, an adder circuit, a multiplier circuit, a finite state machine, combinations thereof, etc. to perform such calculations. In some variations, the processor (130) of the wireless device (114) and / or the wireless implantable device (110) may be configured to process one or more wireless signals transmitted over a wireless link (e.g., a link between the wireless implantable device 110 and the wireless device 114) to determine an impulse response of the wireless system.

[0095] In some variations, the processor 130 of the wireless implantable device 110 may be configured to process parameters (e.g., physiological parameters of the patient) measured by the sensors and generate parameter data (e.g., physiological parameter data). In some variations, the processor 130 may be configured to control one or more circuit blocks of the wireless implantable device 110 and / or the wireless device 114. For example, the processor 130 may be configured to control the wireless transmitter of the wireless implantable device 110 to adjust one or more parameters (e.g., transmission frequency) of the wireless transmitter. In some variations, the processor 130 of the wireless implantable device 110 and / or the wireless device 114 may be configured to monitor one or more circuit blocks or components of the wireless implantable device 110 and / or the wireless device 114. In some variations, the processor (130) of the wireless implantable device (110) may be configured to digitize analog signals (eg, signals received by a transducer).

[0096] In some variations, the processor (130) may include data communications circuitry, which may be a data receiver, configured to access or receive data and / or other signals from one or more of a transducer, a sensor (e.g., a pressure sensor), and a storage medium (e.g., a memory, flash drive, memory card). For example, the processor may include one or more of a signal receiver (e.g., to detect interrogation signals), an envelope detector circuit, an amplifier (e.g., a low noise amplifier or LNA), a filter, a frequency detector circuit, a phase detector circuit, a comparator circuit, a decoder circuit, combinations thereof, etc., to receive data and / or signals via a transducer.

[0097] In some variations, the processor (130) may comprise any suitable processing device configured to perform and / or execute a set of instructions or code, and may include one or more data processors, image processors, graphics processing units (GPUs), physics processing units, digital signal processors (DSPs), analog signal processors, mixed signal processors, machine learning processors, deep learning processors, finite state machines (FSMs), compression processors (e.g., data compression to reduce data rates and / or memory requirements), encryption processors (e.g., for secure wireless data transfer and / or power transfer), and / or central processing units (CPUs). The processor may include, for example, a general-purpose processor, a field programmable gate array (FPGA), an application-specific integrated circuit (ASIC), a processor board, etc. The processor may be configured to perform and / or execute application processes and / or other modules, processes, and / or functions associated with the system. The underlying device technology can be provided in a variety of component types (e.g., metal-oxide-semiconductor field-effect transistor (MOSFET) technologies such as complementary metal-oxide-semiconductor (CMOS), bipolar technologies such as emitter-coupled logic (ECL), polymer technologies (e.g., silicon-conjugated polymer and metal-conjugated polymer-metal structures), mixed analog and digital, etc.).

[0098] The systems, devices, and / or methods described herein may be implemented by software (executed on hardware), hardware, or a combination thereof. Hardware modules may include, for example, general-purpose processors (or microprocessors or microcontrollers), field-programmable gate arrays (FPGAs), graphics processing units (GPUs), central processing units (CPUs), and / or application-specific integrated circuits (ASICs). Software modules (executed on hardware) may be expressed in various software languages ​​(e.g., computer code), including C, C++, Java, Python, Ruby, Visual Basic, and / or other object-oriented, procedural, or other programming languages ​​and development tools. Examples of computer code include, but are not limited to, microcode or microinstructions, machine instructions such as those produced by a compiler, code used to create web services, and files containing high-level instructions executed by a computer using an interpreter. Additional examples of computer code include, but are not limited to, control signals, encryption code, and compression code.

[0099] In some variations, the processor (130) of the wireless implantable device (110) may include one or more of an envelope detection circuit, an energy detector circuit, a power detector circuit, a voltage sensor, a time-to-digital converter (TDC) circuit, an integrator circuit, a sampling circuit, an analog-to-digital converter (ADC) circuit, a timer circuit, a clock, a counter, an oscillator, a phase-locked loop (PLL), a frequency-locked loop (FLL), combinations thereof, etc. In some variations, the processor (130) may include an amplifier, a phase detector, a frequency detector, a digital signal processor, an integrator, an adder circuit, a multiplier circuit, a finite state machine, combinations thereof, etc. to perform calculations.

[0100] In some variations, the processor (130) of the wireless implantable device (110) may include data communication circuitry, which may be a data transmitter or a wireless transmitter, and may be configured to generate or transmit data and / or other signals via one or more of a transducer, a storage medium, etc. For example, the processor (130) of the wireless implantable device (110) may include one or more of a signal transmitter, an uplink data transmitter, an oscillator, a power amplifier, a mixer, an impedance matching circuit, a switch, a driver circuit, combinations thereof, etc., to generate or transmit data and / or signals via a transducer. In some variations, a first processor may be included in the wireless monitor or the wireless implantable device, and a second processor may be included in the external wireless device.

[0101] f.Memory In general, the implantable devices, wireless monitors, and / or wireless devices described herein may comprise memory configured to store data and / or information. In some variations, the memory may be of one or more types including, but not limited to, random access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), resistive random access memory (ReRAM or RRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), standard cell-based memory (SCM), shift register, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory (e.g., NOR, NAND), embedded flash, volatile memory, non-volatile memory, one-time programmable (OTP) memory, combinations thereof, etc.

[0102] In some variations, the memory may store instructions and / or data for causing a processor to execute modules, processes, and / or functions associated with the wireless monitor and / or external wireless device (e.g., execute a search algorithm). Some variations described herein may relate to a computer storage product with a non-transitory computer-readable medium (which may also be referred to as a non-transitory processor-readable medium) having instructions or computer code for performing various computer-implemented operations. The computer-readable medium (or processor-readable medium) may be non-transitory in the sense that it may not itself include a transient propagating signal (e.g., a propagating electromagnetic wave that carries information over a transmission medium such as space or a cable). The medium and computer code (which may also be referred to as code or algorithm) may be designed and constructed for a specific purpose or purposes.

[0103] In some variations, the memory may be configured to store sensor data (e.g., physiological parameter data), received data, and / or data generated by the wireless monitor (e.g., data generated by a processor of the wireless monitor, calibration parameters, etc.), and / or data generated by an external wireless device (e.g., a reference feedback signal in a frequency domain representation and / or a time domain representation). In some variations, the memory of the wireless monitor may be configured to store data generated upon processing a signal sensed by a sensor (e.g., blood pressure data sensed by a pressure sensor that may be included in the wireless monitor). In some variations, the memory may be configured to store data temporarily or permanently.

[0104] g. Wireless transmitter In general, a wireless transmitter of a wireless implantable device or monitor may be configured to wirelessly transmit one or more of a wireless signal, wireless data, wireless commands, and wireless power. For example, the wireless transmitter of the wireless implantable device (110) may include one or more of a signal transmitter, an uplink data transmitter, an oscillator, a clock circuit, a power amplifier, a mixer, an impedance matching circuit, a switch, a driver circuit, combinations thereof, etc., to generate and / or wirelessly transmit data and / or signals via the transducer (120) of the wireless implantable device (110).

[0105] h. Radio receiver In general, a wireless receiver of a wireless implantable device or monitor may be configured to wirelessly receive one or more of a wireless signal, wireless data, wireless commands, and wireless power. For example, the wireless receiver of the wireless implantable device 110 may include one or more of a signal receiver, a data recovery circuit, a clock recovery circuit, a clock circuit, a power recovery circuit, an envelope detector, a wake-up receiver circuit, a data demodulator, an amplifier, a mixer, an analog-to-digital converter (ADC), a phase-locked loop (PLL), a frequency-locked loop (FLL), an impedance matching circuit, a switch, a coherent receiver circuit, a non-coherent receiver circuit, a combination thereof, etc., to wirelessly receive data and / or signals via the transducer 120 of the wireless implantable device 110.

[0106] i. Multiplexer circuit In general, the multiplexers or multiplexer circuits described herein may be configured to decouple one or more of the power signals, data signals, and / or other signals received and / or transmitted by the transducers. This may be done to avoid interference between these signals and ensure proper functionality of a wireless device, such as a wireless monitor, a wireless implantable device, and / or an external wireless device. For example, the multiplexer of a wireless monitor may be configured to decouple the power signals from data signals received by the transducers of the wireless monitor from the external wireless device, such that the power signals are provided to a power supply circuit for power recovery and conditioning, and the data signals are provided to a wireless receiver or processor for data recovery.

[0107] In some variations, the multiplexer may include one or more of a transmit / receive switch, a passive device (e.g., a diode, a relay, a MEMS circuit, a circuit breaker, a passive switch), a circulator, frequency selection (e.g., using a filter, an impedance matching network), a direct wired connection, a combination thereof, and the like.

[0108] In some variations, the transmit / receive switch may be driven based on timing control or time division multiplexing so that one or more of the power signal, the data signal, and other signals are received by the wireless monitor at different times. In some variations, the transmit / receive switch may be driven based on amplitude selection so that one or more of the power signal, the data signal, and other signals have different amplitudes. In some variations, the transmit / receive switch may be driven based on frequency selection or frequency division multiplexing so that one or more of the power signal, the data signal, and other signals have different frequencies. In some variations, the transmit / receive switch may be implemented using depletion mode transistors so that it operates even when the wireless monitor may not have power, stored energy, or established voltage rails.

[0109] D. Wireless Devices In general, a wireless device or external wireless device may refer to any device that is physically separate from a wireless implantable device or wireless monitor. In some variations, an external wireless device may include one or more blocks described herein in the context of a wireless implantable device, including, but not limited to, a transducer, a power supply circuit, an energy storage device, a sensor, a processor, a memory, a wireless transmitter, a wireless receiver, a multiplexer circuit, combinations thereof, etc. Variations of these blocks described herein in the context of a wireless implantable device are also applicable here.

[0110] In some variations, the transducer of the external wireless device may include multiple ultrasound transducer elements or an ultrasound array configured to exchange (transmit and / or receive) wireless signals with one or more wireless implantable devices. As another example, in some variations, the transducer of the external wireless device may include one or more RF coils and / or RF antennas. In some variations, the processor of the external wireless device may perform one or more of processing data and / or signals received from one or more wireless monitors, processing data received from one or more other wireless devices, a combination thereof, etc.

[0111] In some variations, the external wireless device may perform one or more functions including, but not limited to, transmitting one or more of wireless power, data, and other signals to one or more wireless implantable devices; receiving one or more of wireless data and other signals from one or more wireless implantable devices; processing the data and / or signals; performing sensing and / or actuation (e.g., measuring blood pressure, heart rate, heart rate variability, ECG, EKG, thoracic impedance, respiratory rate or respiration, patient activity level, heart sounds, temperature, weight, blood glucose, blood oxygen, combinations thereof, etc.); storing data or information in memory; communicating with other external wireless devices (e.g., tablets, phones, computers) via wires and / or using wireless links (e.g., Bluetooth); displaying or providing data or information (e.g., visual display on a screen or monitor, audio signal); generating alerts / notifications (e.g., visual, audio, vibration) to a user (e.g., patient, nurse, doctor), combinations thereof, etc.

[0112] In some variations, the external wireless device may be located in one or more locations, including, but not limited to, outside the body (e.g., wearable device, strap, belt, handheld device, probe connected to measurement equipment, device placed on the skin, device attached to the skin using adhesive, device attached to the skin using other techniques, device that does not touch the patient, laptop, computer, cell phone, smart watch, etc.), permanently implanted within the body (e.g., implanted under the skin, along the outer wall of an organ, under muscle, outside the heart wall, etc.), temporarily (e.g., for a predetermined period of time) implanted within the body (e.g., located on a catheter or probe inserted through a blood vessel, esophagus, or chest wall used during surgery or procedure), combinations thereof, etc. In some variations, the external wireless device may have different shapes or forms, including, but not limited to, planar, conforming to the body or organ, flexible, stretchable, flat, probe-like, etc.

[0113] In some variations, the external wireless device may further include a communications device configured to enable a user and / or medical personnel to control one or more of the devices of the wireless system. The communications device may include a network interface configured to connect the external wireless device to another system (e.g., the Internet, a remote server, a database) via a wired or wireless connection. In some variations, the external wireless device may communicate with other devices (e.g., a mobile phone, a tablet, a computer, a smartwatch, etc.) via one or more wired and / or wireless networks. In some variations, the network interface may include one or more of a radio frequency receiver / transmitter, an optical (e.g., infrared) receiver / transmitter, an acoustic or ultrasonic receiver / transmitter, etc., and may be configured to communicate with one or more devices and / or networks. The network interface may communicate wired and / or wirelessly with one or more of the external wireless device, a network, a database, and a server.

[0114] The network interface may include RF circuitry configured to receive and / or transmit RF signals. The RF circuitry may convert electrical signals to and from electromagnetic signals and communicate with communication networks and other communication devices via these electromagnetic signals. The RF circuitry may include well-known circuits to perform these functions, including, but not limited to, an antenna system, an RF transceiver, one or more amplifiers, a tuner, one or more oscillators, a mixer, a digital signal processor, a CODEC chipset, a subscriber identity module (SIM) card, memory, etc.

[0115] Wireless communication via any device may be performed using any of the following standards: GSM (Global System for Mobile Communications), EDGE (Enhanced Data GSM Environment), HSDPA (high-speed downlink packet access), HSUPA (high-speed uplink packet access), EV-DO (Evolution, Data-Only), HSPA, HSPA+, DC-HSPDA (Dual-Cell HSPA), LTE (long term evolution), NFC (near field communication), W-CDMA (wideband code division multiple access), CDMA (code division multiple access), TDMA (time division multiple access), Bluetooth, WiFi (Wireless Fidelity: Wireless fidelity) (e.g., IEEE802.11a, IEEE802.11b, IEEE802.11g, IEEE802.11n, etc.), voice over Internet Protocol (VoIP), Wi-MAX, email protocols (e.g., Internet message access protocol (IMAP) and / or post office protocol (POP)), instant messaging (e.g., extensible messaging and presence protocol (XMPP), Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions (SIMPLE), Instant Messaging and Presence Service (IMPS)), and / or Short Message Service (SMS), or any other suitable communication protocol. In some variations, devices herein may communicate directly with each other without transmitting data over a network (e.g., via NFC, Bluetooth, WiFi, RFID, etc.).

[0116] The communication device may further comprise a user interface configured to enable a user (e.g., a subject or patient, a partner, a family member, a medical professional, or other predetermined contact) to control the external wireless device. The communication device may enable a user to directly and / or remotely interact with and / or control the external wireless device. For example, the user interface of the external wireless device may include an input device through which the user inputs commands and an output device through which the user receives output (e.g., a blood pressure reading on a display device).

[0117] In some variations, the output device of the user interface may output one or more of information regarding the coupling of the external wireless device to tissue or skin, information regarding the wireless link between the external wireless device and the wireless monitor (e.g., that a reliable link is established), data measured by one or more of the wireless monitor and the external wireless device (e.g., physiological parameter data), combinations thereof, etc. In some variations, the output device of the user interface may include one or more of a display device and an audio device. Data analysis generated by the server may be displayed by an output device (e.g., a display) of the external wireless device. Data used in finding the transducer configuration or in ensuring that the external wireless device is sufficiently coupled to tissue may be received via the network interface and output visually and / or audibly via one or more output devices of the external wireless device. In some variations, the output device may comprise a display device including at least one of a light emitting diode (LED), a liquid crystal display (LCD), an electroluminescent display (ELD), a plasma display panel (PDP), a thin film transistor (TFT), an organic light emitting diode (OLED), an electronic paper / e-ink display, a laser display, and / or a holographic display.

[0118] In some variations, the audio device may audibly output one or more of any data, commands, instructions to a user, alarms, notifications, etc. For example, if the link between the wireless monitor and the external wireless device is disturbed or interrupted, the audio device may output an audible alarm and may require manual adjustment by the user. In some variations, the audio device may comprise at least one of a speaker, a piezoelectric audio device, a magnetostrictive speaker, and / or a digital speaker. In some variations, a user may communicate with other users using the audio device and the communication channel. For example, a user may form an audio communication channel (e.g., a VoIP call) with a remote medical professional.

[0119] In some variations, the user interface may include an input device (e.g., a touchscreen) and an output device (e.g., a display device) and may be configured to receive input data from one or more of the wireless monitor, an external wireless device, a network, a database, and a server. For example, user control of the input device (e.g., a keyboard, a button, a touchscreen) may be received by the user interface and then processed by a processor and memory of the user interface to output a control signal to the wireless monitor. Some variations of the input device may include at least one switch configured to generate a control signal. For example, the input device may include a touch surface for a user to provide input (e.g., a finger touch on the touch surface) corresponding to the control signal. Input devices including a touch surface may be configured to detect contact and movement on the touch surface using any of a number of touch sensitivity technologies, including capacitive, resistive, infrared, optical imaging, dispersive signal, acoustic pulse recognition, and surface acoustic wave technologies. In variations of input devices that include at least one switch, the switch may include, for example, at least one of a button (e.g., hard key, soft key), a touch surface, a keyboard, an analog stick (e.g., a joystick), a directional pad, a mouse, a trackball, a jog dial, a step switch, a rocker switch, a pointer device (e.g., a stylus), a motion sensor, an image sensor, and a microphone. The motion sensor may receive user movement data from an optical sensor and classify user gestures as control signals. The microphone may receive audio data and recognize user speech as a control signal.

[0120] A haptic device may be incorporated into one or more of the input and output devices to provide additional sensory output (e.g., force feedback) to the user. For example, the haptic device may generate a haptic response (e.g., vibration) to confirm a user input to an input device (e.g., a touch surface). As another example, the haptic feedback may indicate that the user input is overridden by an external wireless device.

[0121] a. Subarray A subarray may generally refer to any subset of a plurality of transducer elements of a wireless device. In some variations, a subarray may include one or more of a set of adjacent transducer elements, a set of alternating transducer elements (e.g., one in two elements), a set of “one in n” transducer elements, or any subset of transducer elements of a transducer array. For example, a subarray may include a set of transducer elements selected to efficiently transfer wireless power to a wireless implantable device based on a feedback signal, as described in detail herein. In some variations, a subarray may comprise a single transducer element of an external wireless device. In some variations, a subarray may comprise all transducer elements of an external wireless device.

[0122] In some variations, subarrays may include disjoint sets of transducer elements. For example, an external wireless device may include a linear 1D array with array elements labeled 1, 2, 3, etc., and subarrays may be comprised of element numbers 1 through 8, 9 through 16, 17 through 24, etc. In some variations, subarrays may include overlapping sets of transducer elements. For example, in the example of a linear 1D array, subarrays may be comprised of element numbers 1 through 8, 2 through 9, 3 through 10, etc. In some variations, subarrays may have different sizes. For example, different subarrays of the same external wireless device may include one or more of different numbers of transducer elements (e.g., some subarrays may include four transducer elements and some subarrays may include 16 transducer elements), transducer elements of different sizes, combinations thereof, etc. In some variations, the selection of transducer elements for a given subarray of an external wireless device may be based on feedback signal data, as described in detail herein.

[0123] b. Transducer Configuration A transducer configuration (e.g., a transducer array configuration, a configuration of a transducer array) may generally refer to one or more transducer elements of a wireless device configured to exchange one or more of wireless power, data, commands, and signals with another wireless device. A transducer configuration may also refer to parameters and settings of one or more transducer elements (e.g., one or more transducer elements of a transducer array) configured to transmit signals (e.g., frequency, amplitude, phase, delay time, duration, etc., according to which one or more transducer elements may be configured to transmit signals) and / or receive signals (e.g., phase shift, delay time, gain, etc., according to which the transducer elements may be configured to receive signals). In some variations, a transducer configuration may be selected by a processor of a wireless device (e.g., an external wireless device) based on feedback signals received from another wireless device (e.g., a wireless implantable device).

[0124] In some variations, a transducer configuration configured to transmit wireless signals to a wireless device may be referred to as a transmit transducer configuration (TTC). In some variations, a transducer configuration configured to receive wireless signals from a wireless device may be referred to as a receive transducer configuration (RTC). In some variations, a transducer configuration selected by a processor of a wireless device based on a feedback signal received from another wireless device may be referred to as an optimal transducer configuration (OTC), which may be improved over a default transducer configuration, but may not necessarily be the most optimal transducer configuration. In some variations, a set of transducer elements of a wireless device, along with drive signals for each of those transducer elements, which may be selectively configured to power the wireless implantable device and / or transmit other downlink signals to the wireless implantable device, may be collectively referred to as a sub-array power snapshot. In some variations, a set of transducer elements of a wireless device configured to receive an uplink signal (e.g., data) from a wireless implantable device, along with parameters related to receiving the signal or conditioning the received signal, such as gain, phase shift, delay, filtering, time window for receiving the signal, etc., may be collectively referred to as a sub-array uplink data snapshot.

[0125] c. User prompts User prompts (also referred to as user feedback) may generally refer to one or more instructions, notifications, recommendations, alerts, etc. provided to a user by a wireless device. User prompts may serve several purposes, including, but not limited to, communicating data regarding the state of charge (SoC) and / or depth of discharge (DoD) of the energy storage device of the wireless implantable device and / or the battery of the external wireless device, prompting the user to charge the battery, communicating data regarding data transfer and / or wireless signal exchange between two wireless devices (e.g., data transfer completion rate), prompting the user to manually adjust or reposition the wireless device on the patient's body, combinations thereof, etc. In some variations, the user prompt may include one or more of feedback signal data (e.g., apodization of one or more transducer elements of the transducer array), link scan signal data, transducer array configuration, properties of the first data signal, properties of the second data signal, properties of the combined data signal, properties of the delay and sum data signal, decoded data bits, properties of the predistortion data signal, properties of the test signal, combinations thereof, etc. In some variations, the user prompt may be provided using one or more of visual instructions, audio instructions, vibration, notifications (e.g., alerts by phone, computer, etc., push notification, email, etc.), combinations thereof, etc. Variations of communication devices, user interfaces, input devices, output devices, etc. may be used to provide user prompts as described herein.

[0126] In some variations, the user prompts (e.g., visual instructions) may include one or more of: images, photographs, and stylized representations (e.g., diagrams, cartoons, diagrams) of the patient's chest (e.g., showing one or more of the chest, arms, neck, and head); a current device configuration (e.g., position, angle, tilt, etc.) of the wireless device; a target device configuration (e.g., position, angle, rotation, tilt, etc.) of the wireless device; a map showing the current / target location; instructions displayed in text form (e.g., statements asking the user to move the wireless device toward the patient's left arm, right arm, head, etc.; a number or percentage representing the power received by the wireless device, the battery's SoC and / or DoD, etc.); arrows instructing the user to move, rotate, and / or adjust the wireless device; an LED (e.g., steady, flashing); combinations thereof; and the like. For example, in some variations, the current location of the wireless device as well as the target location may be overlaid on the image of the chest. The user may be instructed to move the wireless device until it reaches the target location.

[0127] In some variations, the audio instructions may include one or more of a voice command (e.g., asking the user to move the wireless device toward the patient's left arm, asking the user to charge the battery of the wireless device, notifying the user of the completion of data transfer between the two wireless devices), a beep, an alarm, a combination thereof, etc.

[0128] d. Network In some variations, the systems, devices, and methods described herein may communicate with other wireless devices over one or more networks, which may be, for example, any type of network (e.g., wired network, wireless network). Communications may be encrypted or unencrypted. A wireless network may refer to any type of digital network that is not connected by any type of cable. Examples of wireless communications in a wireless network include, but are not limited to, cellular, radio, satellite, and microwave communications. However, wireless networks may be connected to wired networks to interface with the Internet, other carriers' voice and data networks, business networks, and personal networks. Wired networks are typically carried over copper twisted pair, coaxial cable, and / or fiber optic cable. There are many different types of wired networks, including wide area networks (WANs), metropolitan area networks (MANs), local area networks (LANs), Internet area networks (IANs), campus area networks (CANs), global area networks (GANs), such as the Internet, and virtual private networks (VPNs). Hereinafter, a network refers to any combination of wireless, wired, public and private data networks interconnected, typically via the Internet, to provide a unified network and information access system.

[0129] Cellular communications may include technologies such as GSM, PCS, CDMA or GPRS, W-CDMA, EDGE or CDMA2000, LTE, WiMAX, and 5G network standards. Some wireless network deployments combine networks from multiple cellular networks or use a combination of cellular, Wi-Fi, and satellite communications. In some variations, the network may be used for remote processing of any data or information used by the wireless system described herein. For example, a processor that may process any data or information related to the wireless system may be located in the same housing as the wireless implantable device and / or the external wireless device, in a separate housing in the same room or building as the wireless implantable device, in a remote location (e.g., different building, city, country) from the wireless implantable device and the external wireless device, any combination thereof, etc. Processing of data or information related to the wireless system may be performed in real time as data (e.g., feedback signal data, physiological data) is received or recorded, or may be performed at a different time.

[0130] E. Radio Signals As used herein, a wireless signal may generally refer to any wireless signal exchanged between two devices, such as a wireless implantable device and an external wireless device. In some variations, the wireless signal may include one or more of a wireless power or power signal, a downlink data signal, a downlink command, an interrogation signal, a feedback signal, a link scan signal, an uplink data signal, an uplink command, a reflected signal, a backscattered signal, etc.

[0131] a. Feedback signal A feedback signal may generally refer to any signal received by a wireless device (e.g., an external wireless device) from another wireless device (e.g., a wireless implantable device). In some variations, a feedback signal may occur in response to another signal (e.g., an interrogation signal). In some variations, a wireless device (e.g., a wireless implantable device) may be configured to transmit one or more feedback signals without being interrogated by another wireless device. For example, a wireless implantable device may be configured to periodically transmit a feedback signal, which in some variations may also be referred to as a beacon signal.

[0132] In some variations, the feedback signal may be generated using one or more of mechanical waves (e.g., ultrasound, acoustic, vibration), magnetic fields (e.g., induction), electric fields (e.g., capacitance), electromagnetic waves (e.g., RF, light), galvanic coupling, surface waves, etc. In some variations, the feedback signal may be generated in the form of a continuous wave (CW) signal or a pulsed wave (PW) signal. In some variations, the feedback signal may be generated using any known digital or analog modulation technique, such as ASK, FSK, PSK, AM, FM, PM, pulse modulation, PAM, PIMD, PPM, PCM, PDM, etc. In some variations, the ultrasonic feedback signal may include a carrier frequency between about 20 kHz and about 20 MHz. In some variations, the ultrasonic feedback signal pulse may include a pulse duration between about 1 μs and about 1 ms.

[0133] In some variations, the feedback signal may include one or more pulses. For example, the wireless implantable device may be configured to transmit a single ultrasonic pulse (e.g., comprising one or more cycles of a carrier frequency) as the feedback signal, or may periodically transmit multiple ultrasonic pulses. Such ultrasonic pulses may be used by the external wireless device for triangulation or localization of the wireless implantable device and / or to estimate link gain between the external wireless device and the wireless implantable device, as described in more detail herein. In some variations, the feedback signal may include multiple cycles of the carrier frequency. For example, the duration of the feedback signal may be greater than about five cycles of the carrier frequency of the feedback signal. In some variations, the feedback signal may include a pulsed signal. In some variations, the pulsed signal may include one or more of a rectangular pulse, a Dirac pulse, a sinusoidal pulse, a triangular pulse, a trapezoidal pulse, a raised cosine pulse, a sinc pulse, a Gaussian pulse, one or more cycles of the carrier frequency of the pulsed signal, combinations thereof, etc. In some variations, the pulsed signal may include sinusoidal cycles of the carrier frequency. In some variations, the pulse signal may include one or more of a two-level square wave, a three-level square wave, a five-level square wave, a multi-level square wave, combinations thereof, etc. In some variations, the feedback signal may be generated by a multi-level pulser circuit (e.g., a three-level pulser) of the first device.

[0134] In some variations, the feedback signal may include data encoded using modulation techniques (e.g., digital modulation). For example, in some variations, the wireless implantable device may encode one or more of the following onto the feedback signal, including, but not limited to, the power or voltage received by one or more transducers of the wireless implantable device (e.g., after digitization of the power or voltage), the voltage of the battery and / or capacitor of the wireless implantable device, the energy state of the wireless implantable device, the energy stored in the power source (e.g., battery, capacitor) of the wireless implantable device, the battery charging current, the DC voltage generated by the power supply circuit of the wireless implantable device, the duration corresponding to the wireless power signal received by the wireless implantable device, the duration corresponding to the charging of the energy storage device of the wireless implantable device, combinations thereof, etc. As another example, in some variations, the wireless implantable device may encode a unique identification (ID) number or code into the feedback signal. In some variations, the feedback signal may encode a delay time. For example, in some variations, the feedback signal may encode a delay time (e.g., after digitization) between receiving an interrogation and / or power signal from an external wireless device and transmitting the feedback signal to the external wireless device.

[0135] In some variations, the feedback signal may include one or more of a reflected signal and a backscattered signal. These signals may occur upon reflection or backscattering of the interrogation signal or any other signal transmitted by the external wireless device from one or more wireless implantable devices and / or one or more tissue structures (such as a rib, a lung, or a boundary between two types of tissue). Reflections from the wireless implantable devices may include one or more reflections from one or more of the housing, coating, or encapsulation of the wireless implantable device, the transducer (e.g., an ultrasound transducer) of the wireless implantable device, a surface (e.g., front, back, side, outer surface, inner surface) of the wireless implantable device, any portion of the wireless implantable device, a combination thereof, etc. In some variations, the reflected signal may include an ultrasound reflected signal generated upon reflection of an ultrasound signal transmitted into tissue by a sub-array of the external wireless device.

[0136] b. Link scan signal A link scan signal may generally refer to any signal transmitted over a wireless link that can be processed to determine properties of the wireless link. The link scan signal may be transmitted by any device in a wireless system. For example, the link scan signal may be transmitted by one or more of a wireless implantable device and an external wireless device. For example, the link scan signal may be an impulse signal transmitted by the wireless implantable device and received by the external wireless device. A processor in the external wireless device may be configured to process the received impulse signal to determine the impulse response of the wireless link or system.

[0137] In some variations, the link scan signal may include similar parameters or properties (e.g., signal modality, type, modulation, etc.) as those described for the feedback signal. In some variations, the link scan signal may be generated using one or more of mechanical waves (e.g., ultrasound, acoustic, vibration), magnetic fields (e.g., induction), electric fields (e.g., capacitance), electromagnetic waves (e.g., RF, light), galvanic coupling, surface waves, etc. In some variations, the link scan signal may include one or more of an impulse signal, a pulsed signal, a feedback signal, a predetermined digital code, and a continuous wave signal. In some variations, the pulsed signal may include one or more of a rectangular pulse, a Dirac pulse, a sinusoidal pulse, a triangular pulse, a trapezoidal pulse, a raised cosine pulse, a sinc pulse, a Gaussian pulse, one or more cycles of a carrier frequency of the pulsed signal, combinations thereof, etc. In some variations, the pulsed signal may include a sinusoidal cycle of a carrier frequency. In some variations, the pulse signal may include one or more of a two-level square wave, a three-level square wave, a five-level square wave, a multi-level square wave, combinations thereof, etc. In some variations, the link scan signal may be generated by a multi-level pulser circuit (e.g., a three-level pulser) of the first device. In some variations, the ultrasonic link scan signal may include a carrier frequency between about 20 kHz and about 20 MHz.

[0138] In some variations, the link scan signal may include data encoded using a modulation technique (e.g., digital modulation). In some variations, the link scan signal may include one or more of a reflected signal and a backscattered signal. For example, the link scan signal may include a reflected signal from a wireless implantable device that corresponds to a signal transmitted into tissue by an external wireless device.

[0139] c. Data signal A data signal may generally refer to any signal transferred over a wireless link for data communication. A data signal may be transmitted by any device in a wireless system. For example, a data signal may be transmitted by one or more of a wireless implantable device and an external wireless device. A data signal may include one or more of an uplink data signal and a downlink data signal. An uplink data signal may refer to a data signal from a wireless implantable device to an external wireless device. A downlink data signal may refer to a data signal from an external wireless device to a wireless implantable device.

[0140] In some variations, the data signal may include similar parameters or properties (e.g., signal modality, type, modulation, etc.) as those described for the feedback signal. In some variations, the data signal may be generated using one or more of mechanical waves (e.g., ultrasound, acoustic, vibration), magnetic fields (e.g., induction), electric fields (e.g., capacitance), electromagnetic waves (e.g., RF, light), galvanic coupling, surface waves, etc. In some variations, the data signal may be generated in the form of a continuous wave (CW) signal or a pulsed wave (PW) signal. In some variations, the data signal may include one or more of digital data and analog data. In some variations, the data signal may be generated using any known digital or analog modulation technique, such as ASK, FSK, PSK, AM, FM, PM, pulse modulation, PAM, PIMD, PPM, PCM, PDM, etc. In some variations, the ultrasound data signal may include a carrier frequency between about 20 kHz and about 20 MHz. In some variations, a data bit of a data signal (e.g., an ultrasound data signal) may include a pulse duration (or bit duration) of between about 1 μs and about 1 ms. In some variations, the data signal may include one or more of a reflected signal and a backscattered signal. For example, the data signal may include a backscattered signal.

[0141] In some variations, the data signal may encode one or more of a physiological parameter (e.g., information about a physiological parameter sensed by the wireless implantable device), a parameter of the wireless device (e.g., a voltage of an energy storage device of the wireless implantable device, a frequency of the wireless device, an ID of the wireless device, etc.), a parameter of the wireless link (e.g., a link gain), data generated by a processor of the wireless device (e.g., feedback signal data), data generated by a user (e.g., a user command), a wireless command or instruction, a combination thereof, etc.

[0142] II. Method Described herein are methods for exchanging wireless signals in a wireless system using any of the systems and devices described herein. In general, a wireless system or device may implement one or more of the methods described herein, or any subset of one or more of the methods described herein, or a combination of a method or subset of methods. One or more of the methods described herein, or steps therein, may be applied to multiple wireless implantable devices and / or wireless monitors.

[0143] Wireless signals exchanged in wireless systems that include heterogeneous media (e.g., ribs, lungs, muscles, etc.) may experience reflections from different objects or structures within the media. These reflections may cause undesirable destructive and / or constructive interference of the wireless signals due to multipath interference. Solutions are provided herein to mitigate and / or account for the effects of multipath interference in order to efficiently and / or reliably transfer wireless signals (e.g., power, data, commands, etc.) in wireless systems.

[0144] In some variations, exchanging wireless signals in a wireless system may be facilitated by transmitting a feedback signal from a first device of the wireless system to a second device of the wireless system. In some variations, a method of exchanging wireless signals in a wireless system may include one or more of the following steps, including but not limited to: transmitting a feedback signal from a first device of the wireless system to a second device of the wireless system for a first duration, receiving the feedback signal for a second duration using one or more transducer elements of a transducer array of the second device, processing the feedback signal received during the second duration using the one or more transducer elements of the transducer array to generate feedback signal data using a processor of the second device, determining a transducer array configuration of the second device based at least in part on the feedback signal data using the processor of the second device, and exchanging one or more wireless signals with the first device using the transducer array configuration of the second device.

[0145] In some variations, a method of exchanging wireless signals in a wireless system may include one or more of the following steps, including but not limited to: transmitting a feedback signal from a first device of the wireless system to a second device of the wireless system; receiving the feedback signal using a first transducer array of the second device; extracting, using a processor of the second device, one or more portions of the received feedback signal that are received by one or more transducer elements of the first transducer array of the second device; processing the extracted one or more portions of the received feedback signal using the processor of the second device to generate feedback signal data; determining a second transducer array configuration of the second device based at least in part on the feedback signal data; and exchanging one or more wireless signals with the first device using the second transducer array configuration of the second device.

[0146] In some variations, exchanging wireless signals in a wireless system may be facilitated by transmitting a link scan signal from a first device of the wireless system to a second device of the wireless system. In some variations, a method of exchanging wireless signals in a wireless system may include one or more of the following steps, including but not limited to: transmitting a link scan signal from a first device of the wireless system to a second device of the wireless system; receiving the link scan signal using a first transducer array of the second device; processing the received link scan signal, which is received by one or more transducer elements of the first transducer array of the second device, using a processor of the second device to generate link scan signal data; determining a second transducer array configuration of the second device based at least in part on the link scan signal data; and exchanging one or more wireless signals with the first device using the second transducer array configuration of the second device.

[0147] In some variations, exchanging wireless signals in a wireless system may be facilitated by transmitting both a link scan signal and a feedback signal from a first device of the wireless system to a second device of the wireless system. In some variations, a method of exchanging wireless signals in a wireless system may include one or more of the following steps, including but not limited to: transmitting a link scan signal and a feedback signal from a first device of the wireless system to a second device of the wireless system; receiving the link scan signal and the feedback signal using a first transducer array of the second device; processing the received link scan signal and the received feedback signal received by one or more transducer elements of the first transducer array of the second device using a processor of the second device to generate feedback signal data; determining a configuration of the second transducer array of the second device based at least in part on the feedback signal data; and exchanging one or more wireless signals with the first device using the configuration of the second transducer array of the second device.

[0148] Also described herein are methods for exchanging wireless signals based on defocusing acoustic beams. Also described herein are closed-loop powering methods for transmitting wireless power from a second device to a first device to target a required voltage and / or power level at the first device.

[0149] Also described herein are methods of wireless data communication between two or more devices of a wireless system. In some variations, the wireless data communication between the two wireless devices may utilize a link scan signal. In some variations, a method of decoding a data signal in a wireless system may include, but is not limited to, the following steps: transmitting a link scan signal and a first data signal from a first device of the wireless system to a second device of the wireless system; receiving the link scan signal and the first data signal using one or more transducer elements of the second device; processing the received link scan signal and the received first data signal using a processor of the second device to generate a second data signal; and decoding the first data signal based at least in part on the second data signal.

[0150] In some variations, wireless data communication between a first device and a second device of a wireless system may utilize selection of one or more transducer elements of the second device. In some variations, a method of decoding a data signal in a wireless system may include, but is not limited to, the following steps: transmitting a link scan signal and a first data signal from a first device of the wireless system to a second device of the wireless system, receiving the link scan signal and the first data signal using one or more transducer elements of the second device, processing one or more of the received link scan signal and the received first data signal using a processor of the second device to select one or more transducer elements of the second device, and decoding the first data signal based at least in part on the selected one or more transducer elements of the second device.

[0151] In some variations, wireless data communications between two wireless devices may utilize predistorted data signals. In some variations, a method of decoding a signal in a wireless system may include, but is not limited to, the following steps: transmitting a link scan signal from a first device of the wireless system to a second device of the wireless system, receiving the link scan signal using one or more transducer elements of the second device, processing the received link scan signal using a processor of the second device to generate link scan signal data, generating a predistorted data signal based on the link scan signal data using a processor of the second device, transmitting the predistorted data signal from the second device to the first device, receiving the predistorted data signal using one or more transducer elements of the first device, and processing the received predistorted data signal using the processor of the first device to generate decoded data.

[0152] Also described herein is a method of calibrating a wireless system. In some variations, the method of calibrating a wireless system may include, but is not limited to, the following steps: transmitting one or more test signals including one or more carrier frequencies from a first device of the wireless system to a second device of the wireless system, receiving the one or more test signals using the second device, processing the one or more received test signals using a processor of the second device to generate test signal data, determining one or more selected carrier frequencies using the processor of the second device based at least in part on the test signal data, transmitting one or more wireless commands from the second device to the first device including information corresponding to the one or more selected carrier frequencies, and storing the information corresponding to the one or more selected carrier frequencies in a memory of the first device.

[0153] In some variations, exchanging wireless signals in a wireless system may be facilitated by one or more predetermined transmit voltage levels. In some variations, a method of exchanging wireless signals in a wireless system may include, but is not limited to, the following steps: transmitting a feedback signal from a first device of the wireless system to a second device of the wireless system, receiving the feedback signal using one or more transducer elements of a transducer array of the second device, processing the received feedback signal using the one or more transducer elements of the transducer array to generate feedback signal data using a processor of the second device, determining, using the processor of the second device, a transducer array configuration of the second device based at least in part on the feedback signal data and one or more predetermined transmit voltage levels of a power source of the second device, and exchanging one or more wireless signals with the first device using the transducer array configuration of the second device.

[0154] In some variations, exchanging wireless signals in a wireless system may be facilitated by one or more transmitter circuits. In some variations, a method of exchanging wireless signals in a wireless system may include, but is not limited to, the following steps: transmitting a feedback signal from a first device of the wireless system to a second device of the wireless system; receiving the feedback signal using one or more transducer elements of a transducer array of the second device; processing the received feedback signal using the one or more transducer elements of the transducer array to generate feedback signal data using a processor of the second device; determining, using the processor of the second device, transmitter circuit data corresponding to one or more transmitter circuits of the second device configured to apply transmit signals to the one or more transducer elements of the transducer array based at least in part on the feedback signal data; determining, using the processor of the second device, a transducer array configuration of the second device based at least in part on the feedback signal data and the transmitter circuit data; and exchanging one or more wireless signals with the first device using the transducer array configuration of the second device.

[0155] A. Exchanging radio signals with wireless devices In some variations, beamforming may be performed in a wireless system to establish a reliable and / or efficient wireless link between two or more wireless devices. In some variations, a wireless signal, such as a feedback signal, propagating wirelessly from a first device in the wireless system may be received by a second device in the wireless system. Such a received signal may be processed by a processor in the second device to determine a transducer configuration of the second device for exchanging wireless signals with the first device. For example, the transducer configuration may include a set of elements of a transducer array of the second device and their corresponding signal strengths and delays or phases for transmitting wireless power to the first device. Determining such a transducer configuration may be difficult in wireless links or systems that experience multipath interference due to reflections of wireless signals propagating from inhomogeneous media and structures onto the wireless link. For example, ultrasound signals propagating within the chest may experience multipath interference due to reflection and / or scattering of ultrasound waves from ribs, lungs, and / or other tissue boundaries. Because conventional ultrasound beamforming techniques may not account for multipath interference, using such techniques to deliver wireless power or energy to a wireless implantable device may result in reduced total power or energy delivery due to potentially destructive interference of ultrasound waves reaching the wireless implantable device from one or more reflectors in the medium. Solutions to overcome such challenges are provided herein.

[0156] a. Radio signal exchange based on feedback signals In some variations, wireless devices in a wireless system may exchange wireless signals based on a feedback signal that propagates from a first device of the wireless system to a second device of the wireless system.

[0157] 3 is a flowchart generally illustrating variations of a method 300 for exchanging wireless signals with a device based on a feedback signal. In some variations, determining a transducer array configuration of the second device based at least in part on feedback signal data (e.g., characterizing a wireless link between the first and second devices) enables focused wireless signals (e.g., ultrasound) to be transmitted by the second device, which may result in a reliable and / or efficient wireless link between the second and first devices. The method (300) may include the steps of transmitting a feedback signal for a first duration from a first device of a wireless system to a second device of the wireless system (302); receiving the feedback signal for a second duration using one or more transducer elements of a transducer array of the second device (304); processing the feedback signal received during the second duration by the one or more transducer elements of the transducer array to generate feedback signal data using a processor of the second device (306); determining a transducer array configuration of the second device based at least in part on the feedback signal data using the processor of the second device (308); and exchanging one or more wireless signals with the first device using the transducer array configuration of the second device (310).

[0158] In some variations, the feedback signal may include one or more analog pulses, hi some variations, processing the feedback signal may include extracting analog features of the feedback signal, such as one or more of amplitude, phase, delay time, arrival time, duration, number of cycles, frequency, power, energy, combinations thereof, etc.

[0159] In some variations, the received feedback signal may be processed on a subset of the transducer elements (e.g., some or all) that receive the feedback signal. In some variations, the transducer elements selected to process the received feedback signal may be predetermined. In some variations, the transducer elements selected to process the received feedback signal may be selected based on one or more properties of the received feedback signal, other signals in the wireless system, properties of the transducer elements, combinations thereof, etc. For example, the transducer elements selected to process the received feedback signal may be selected based on the signal strength of the received feedback signal, the signal-to-noise ratio of the received feedback signal, the energy of the received feedback signal in one or more frequency bands, a predetermined apodization of the transducer elements, a moving average of the feedback signal amplitude, the signal strength of the interferer, the signal strength of the multipath interference, and the multipath time. Apodization may refer to relative amplitude weighting applied to different transducer elements of a transducer array for transmitting and / or receiving wireless signals. For example, a transducer element with an apodization value of 0.7 may be configured to transmit approximately 70% of the signal amplitude, or equivalently, approximately 49% of the power level, relative to another transducer element with an apodization value of 1.0. In some variations, multipath time may refer to the duration over which multipath reflections or multipath interference in a wireless link may dissipate below a predetermined threshold (e.g., a predetermined power level).

[0160] In some variations, the second duration may be longer than the first duration. In some variations, the second duration may be predetermined based on one or more of multipath propagation in the wireless link, multipath time, signal attenuation in the medium, propagation speed of the wireless signal in the medium, calibration of the system by sending a signal through the system and measuring the time required for the multipath echo to dissipate, combinations thereof, etc. In some variations, the second duration may be determined by a processor of the second device based on properties of the received feedback signal (e.g., by measuring the time required for the multipath echo in the received feedback signal to dissipate). In some variations, the second duration of the received feedback signal may be shorter than the first duration of the transmitted feedback signal. For example, the transmitted feedback signal may include a pulse signal having multiple cycles of a carrier frequency, and the second duration of the received feedback signal may include a portion of the pulse signal having one or more cycles that include a settled signal amplitude (e.g., the amplitude at which the multipath echo has dissipated).

[0161] In some variations, the method (300) may include detecting an onset (e.g., rising edge, time of arrival) of a received feedback signal on one or more transducer elements of the transducer array using one or more of envelope detection, predetermined timing, coherent detection (e.g., using blending), comparing the amplitude of the received feedback signal to a threshold level, combinations thereof, etc. In some variations, the onset detection may include using one or more of envelope detection, predetermined timing (e.g., based on a time at which the first device may transmit the feedback signal and a signal propagation delay from the first device to the second device), coherent detection, and comparing the amplitude of the received feedback signal to a threshold level (e.g., a predetermined threshold).

[0162] In some variations, the feedback signal data may include one or more of the following: absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute arrival time, relative arrival time, frequency, duration, number of cycles, absolute signal-to-noise ratio, relative signal-to-noise ratio, combinations thereof, etc. of the feedback signal received by one or more transducer elements of the transducer array within the second duration. For example, in some variations, the arrival time of the received feedback signal on one or more transducer elements may include detecting the absolute timing of a rising edge of the received feedback signal or the timing of a rising edge of the received feedback signal relative to a reference transducer element. In some variations, the reference transducer element may be determined based on one or more of the amplitude, energy, signal-to-noise ratio or signal-to-interference ratio of the received feedback signal, apodization of the transducer element, combinations thereof, etc. For example, the reference transducer element may be the transducer element receiving the strongest amplitude or SNR of the feedback signal.

[0163] In some variations, the transducer array configuration may include one or more of transducer element selection, apodization, signal strength, voltage level, current level, pulse width, pulse width modulation, signal duty cycle, phase, delay time, frequency, transmission duration, combinations thereof, etc. applied to one or more transducer elements of the transducer array to transmit a wireless signal to the first device. In some variations, the transmitted wireless signal may include one or more of power, data, commands, one or more other signals (e.g., pulses), combinations thereof, etc. In some variations, the second device may include one or more pulser circuits to drive one or more transducer elements of the transducer array to transmit the wireless signal. In some variations, the output or transmit signal of the pulser circuit may include one or more signal levels (e.g., a two-level pulser output or square wave, a three-level pulser output, a five-level pulser output, combinations thereof, etc.). In some variations, the multi-level pulser output may include a pulse width or duty cycle that may be modulated (eg, pulse width modulated) to modulate the transmit power.

[0164] In some variations, the transmit duration of the wireless signal transmitted from the second device to the first device may be determined by a processor of the second device based on monitoring feedback signal data (e.g., link efficiency, apodization, phase, and / or delay) corresponding to feedback signals received by transducer elements of a transducer array of the second device. For example, if the feedback signal data does not change significantly over time, the second device may be configured to transmit the wireless signal with an increased transmit duration. In some variations, the increased transmit duration may enable an increase in the duty cycle of the wireless power (e.g., burst duration that the wireless power is on relative to the total repetition interval), thereby enabling faster charging of an energy source (e.g., capacitor, battery) of the first device. In some variations, the processor of the second device may be configured to periodically monitor the feedback signal data over time and dynamically adjust the transmit duration of the wireless signal transmitted from the second device to the first device based on the feedback signal data (e.g., rate of change of apodization or phase corresponding to feedback signals received by the transducer elements).

[0165] In some variations, it may be desirable to use one or more wireless power signals to achieve one or more of efficient and / or fast charging of a first device from a second device and operation or heating below safe intensity levels due to the wireless power signals within the body. In some variations, closed-loop powering may be used to achieve a target power level in the first device (e.g., a wireless implantable device). In some variations, the first device may be configured to transmit or communicate feedback regarding one or more of the power level, voltage level, or current level received or generated by the first device in response to the first wireless power signal received from the second device. However, in some systems where the first device may move relative to the second device over time, or where there may be fluctuations in other links over time, feedback regarding the power, voltage, or current level may not be sufficient to achieve reliable wireless powering or charging of the first device. Solutions to overcome such challenges are provided herein.

[0166] In some variations, the first device receiving the wireless power signal from the second device may be configured to determine or measure a first duration including one or more of a duration corresponding to the wireless power signal received by the first device, a duration corresponding to charging of an energy storage device of the first device (e.g., a duration for which the energy storage device of the first device charges upon receiving the wireless power signal), a combination thereof, etc. In some variations, the first duration may include a duration that may satisfy a predetermined condition. In some variations, the predetermined condition may include checking (e.g., using a processor of the first device) whether one or more of the following, including but not limited to, a wireless power level or energy level received by the first device, a voltage generated by the first device in response to the received wireless power signal (e.g., an output voltage of a rectifier, AC-DC converter circuit, DC-DC converter circuit, charging circuit, power management circuit, etc.), a current generated by the first device in response to the received wireless power signal (e.g., a load current of a rectifier circuit, a current of a clamp circuit, a charging current of an energy storage device of the first device, etc.), combinations thereof, etc., may be above or below a predetermined threshold. In some variations, the first duration may be digitized by the first device (e.g., using a timer circuit, a time-to-digital converter circuit, etc.). In some variations, information regarding the first duration may be transmitted by the first device to the second device in the form of a feedback signal and / or a wireless data signal (e.g., the digitized duration may be transmitted in the form of OOK data bits).In some variations, the second device may be configured to receive (e.g., using one or more transducer elements of a transducer array) and process (e.g., using a processor of the second device) the feedback signal and / or wireless data signal to generate feedback signal data (e.g., the feedback signal data may include information regarding the first duration) and determine the second duration based at least in part on the feedback signal data. In some variations, the second device may be configured to exchange one or more wireless signals with the first device based on the second duration (e.g., transmit a wireless power signal to the first device with a duration equal to the second duration). In some variations, the second duration may be substantially equal to the first duration. In some variations, the second duration may be longer than the first duration. For example, if the duration of the wireless power signal transmitted by the second device and the first duration are substantially equal, it may indicate that the energy storage device of the first device can charge for the entire duration of the wireless power signal and that a longer duration of the wireless power signal may be beneficial in faster charging of the energy storage device of the first device. In some variations, the second device may be configured to adjust (e.g., increase or decrease) the transmission duration of the next one or more wireless signals (e.g., wireless power signal, wireless data signal, etc.) transmitted by the second device to the first device based on the feedback signal data. In some variations, the second device may be configured to dynamically adjust its transmission duration based on feedback from the first device. For example, the feedback from the first device may include a digitized duration of the received power signal received by the first device, during which the output voltage of the rectifier circuit of the first device may be above a predetermined threshold voltage level (e.g., 3 V, 4 V, etc.).This may be advantageous to optimize (or increase) or adjust the duty cycle of the wireless power (which may be calculated as the power signal duration useful for charging the first device divided by the repetition interval of the wireless power signal transmitted by the second device). For example, such an approach may allow maximizing (or increasing) the charging rate of one or more energy storage devices of the first device and / or minimizing (or shortening) the time required to charge one or more energy storage devices of the first device.

[0167] In some variations, a system configured to exchange wireless power or data may include a first device including a first transducer, a first processor, and an energy storage device, wherein the first transducer may be configured to receive a first wireless power signal from a second device, the energy storage device may be configured to charge based on the received first wireless power signal, the first processor may be configured to determine a charging duration corresponding to one or more predetermined conditions, the first device may be configured to transmit a feedback signal based on the charging duration, the second device may include a second transducer and a second processor, the second transducer may be configured to receive the feedback signal, the second processor may be configured to process the feedback signal to generate feedback signal data and determine a transducer configuration based at least in part on the feedback signal data, and the second device may be configured to transmit a second wireless power signal to the first device based on the transducer configuration.

[0168] In some variations, the charging duration may include one or more of a duration for the first wireless power signal, a duration for a signal generated by the first device in response to the first wireless power signal, a duration for charging an energy storage device of the first device, combinations thereof, etc. For example, the charging duration may include a duration during which a voltage level at a capacitor of the first device (e.g., an output capacitor of a rectifier circuit) may exceed a predetermined threshold. For example, the voltage level at the capacitor may rise based on power recovery of the first wireless power signal by the rectifier circuit. In some variations, the voltage level at the capacitor (e.g., in the case of a relatively large capacitance) may exceed the predetermined threshold even after the first wireless power signal dissipates. In some variations, the charging duration may be longer than the duration of the first wireless power signal. In some variations, the charging duration may be shorter than the duration of the first wireless power signal (e.g., if the first device moves significantly during the duration of the first wireless power signal, it may receive a power level that decreases over time, causing the voltage level at the capacitor to drop below a predetermined threshold).

[0169] In some variations, the predetermined condition may include one or more of an absolute or relative duration corresponding to the received first wireless power signal, an absolute or relative duration corresponding to the voltage generated by the first device in response to the received first wireless power signal, an absolute or relative duration corresponding to the current generated by the first device in response to the received first wireless power signal, an absolute or relative power level corresponding to the received first wireless power signal, an absolute or relative energy level corresponding to the received first wireless power signal, an absolute or relative voltage level generated by the first device in response to the received first wireless power signal, and an absolute or relative current level generated by the first device in response to the received first wireless power signal.

[0170] 23 is a flowchart generally illustrating a variation of a method 2300 for exchanging wireless signals with a device based on a charging duration. The method 2300 includes receiving 2302 a first wireless power signal at a first transducer of a first device of the wireless system from a second device of the wireless system, where the first device may include an energy storage device and a first processor, and the second device may include a second transducer and a second processor; charging 2304 the energy storage device based on the received first wireless power signal; determining 2306 a charging duration corresponding to one or more predetermined conditions using the first processor; and receiving 2308 a signal from the first device based on the charging duration. The method may include transmitting a feedback signal from the first device to a second device (2308), receiving the feedback signal using a second transducer (2310), processing the feedback signal to generate feedback signal data using a second processor (2312), determining a transducer configuration based at least in part on the feedback signal data using the second processor (2314), and transmitting a second wireless power signal from the second device to the first device based on the transducer configuration (2316).

[0171] In some variations, the predetermined condition may include one or more of an absolute or relative duration corresponding to the received first wireless power signal, an absolute or relative duration corresponding to the voltage generated by the first device in response to the received first wireless power signal, an absolute or relative duration corresponding to the current generated by the first device in response to the received first wireless power signal, an absolute or relative power level corresponding to the received first wireless power signal, an absolute or relative energy level corresponding to the received first wireless power signal, an absolute or relative voltage level generated by the first device in response to the received first wireless power signal, and an absolute or relative current level generated by the first device in response to the received first wireless power signal.

[0172] In some variations, the method may include digitizing the charging duration using the first processor. For example, in some variations, the first processor may include a timer circuit and an analog-to-digital converter to determine digital bits representing the charging duration. In some variations, the method may include using the first processor to encode or modulate a feedback signal with one or more of a digital representation of the charging duration (e.g., using OOK modulation) and an analog representation of the charging duration. In some variations, feedback from the first device regarding the charging duration may be included as part of one or more of a feedback signal, a data signal, an uplink data signal, a combination thereof, etc.

[0173] In some variations, the feedback signal data may include one or more of: a digital representation of a charging duration, an analog representation of a charging duration, an absolute amplitude or magnitude, a relative amplitude or magnitude, an absolute signal strength, a relative signal strength, a signal energy in one or more frequency bands, apodization, an absolute phase, a relative phase, an absolute delay time, a relative delay time, an absolute arrival time, a relative arrival time, a frequency, a duration, a number of cycles, an absolute signal-to-noise ratio, and a relative signal-to-noise ratio of the feedback signal received by the second transducer. In some variations, the feedback signal data may include one or more of a mean, median, mode, variance, standard deviation, minimum, maximum, percentile, histogram, statistical distribution, frequency, and probability of one or more charging durations corresponding to the one or more first wireless power signals received by the first transducer from the second device.

[0174] In some variations, the transducer configuration may include one or more of: an absolute or relative duration of the second wireless power signal; one or more absolute or relative power levels of the second wireless power signal (e.g., increasing power levels over the duration or over the duration of a burst of the second wireless power signal); one or more absolute or relative amplitudes of the second wireless power signal; an absolute or relative pulse repetition frequency (PRF) or duty cycle of the power supply of the second wireless power signal; and an absolute or relative frequency of the second wireless power signal. For example, the second processor may be configured to adjust or adapt the transmission duration of the second wireless power signal based on feedback regarding the duration of one or more previously transmitted wireless power signals that successfully charged the energy storage device of the first device. In some variations, the second processor may be configured to adapt, adjust, or ramp the transmission power level corresponding to the second wireless power signal over time. For example, if the strength or power level of the first wireless power signal received by the first device decays over time, the second processor may be configured to increase the transmit power level of the second wireless power signal over time so that the first device receives a substantially uniform strength or power level over time (or an strength or power level with relatively little variation over time). For example, in some variations, the PRF of the second wireless power signal may be adjusted to meet intensity limitations (e.g., time-averaged intensity limitations) or heating limitations within the body.

[0175] In some variations, the second processor may be configured to process multiple feedback signals received from the first device (e.g., one or more feedback signals may encode information related to charging durations). In some variations, the second processor may be configured to determine a transmission duration and / or a power level of the second wireless power signal based on the multiple feedback signals received from the first device (e.g., by calculating an average value of charging durations corresponding to the multiple first wireless power signals received by the first device and transmitting a second wireless power signal with a transmission duration that may be substantially equal to the average value). In some variations, the second device may include a memory for storing feedback signal data (e.g., storing charging durations corresponding to the multiple first wireless power signals).

[0176] In some variations, the duration of the second wireless power signal may be configured to be substantially equal to or greater than the charging duration. In some variations, the duration of the second wireless power signal may be configured to be substantially equal to or greater than one or more of one or more mean charging durations, one or more median charging durations, one or more modes of charging durations, and one or more values ​​corresponding to the charging durations, where the one or more charging durations correspond to one or more first wireless power signals received by the first transducer from the second device. For example, in some variations, the duration of the second wireless power signal may be configured to be substantially equal to or greater than the sum of a mean and one or more standard deviations of a distribution of one or more charging durations (e.g., a mean and standard deviation of a Gaussian distribution). Such an approach may be advantageous for wireless links that vary over time and allows for empirical determination of an optimal transmission duration of the second wireless signal based on charging durations corresponding to one or more previous first wireless signals.

[0177] In some variations, the second transducer may include one or more transducer arrays, the one or more transducer arrays including one or more transducer elements. In some variations, the transducer configuration may include one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse repetition rate, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to the one or more transducer elements for transmitting the one or more wireless power signals to the first device.

[0178] In some variations, the first device may include an implantable medical device and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first and second wireless power signals may include ultrasonic or acoustic signals.

[0179] In some variations, the transducer array configuration may include a set of parameters (e.g., phases of transducer elements) based on parameters (e.g., phases) of the feedback signal. For example, a phase applied to one or more transducer elements of the transducer array to transmit a wireless signal to the first device may be based on one or more of the relative phase of a feedback signal received within a second duration at a predetermined frequency and the arrival time of the feedback signal received on the one or more transducer elements. Additionally or alternatively, a delay time applied to one or more transducer elements of the transducer array to transmit a wireless signal to the first device may be based on one or more of the relative phase of a feedback signal received within a second duration at a predetermined frequency and the arrival time of the feedback signal received on the one or more transducer elements. In some variations, the predetermined frequency may include one or more of the carrier frequency of the feedback signal, a harmonic of the carrier frequency, a sub-harmonic of the carrier frequency, yet another frequency within the frequency band of the received feedback signal, combinations thereof, etc. In some variations, the delay time applied to a transducer element may include the sum of a relative arrival time of the feedback signal (e.g., relative to a reference transducer element) rounded to a period of the carrier frequency of the feedback signal and a delay time or phase corresponding to the relative phase of the received feedback signal (e.g., relative to the reference transducer element) received during a second duration at the carrier frequency of the feedback signal. For example, this may facilitate alignment of the rising and / or falling edges of wireless signals (e.g., ultrasonic pressure waves) as well as the steady-state phase of wireless signals received by a transducer element of a first device from a different transducer element of a second device.In some variations, aligning the rising and / or falling edges allows for a shorter bit duration of OOK-modulated downlink data bits transmitted by a second device (e.g., an external device) to a first device (e.g., an implantable medical device), thereby enabling higher data rates and faster data communications. In some variations, the relative phase of the feedback signal received at the predetermined frequency during the second duration may be the relative phase of a portion of the feedback signal whose amplitude has settled (e.g., where multipath reflections have dissipated below a predetermined threshold and whose amplitude is within about 5% of its steady-state value). In some variations, the transmit phase or delay time may be applied using one or more of a number of clock cycles, a delay line, a digitally controlled phase or delay time, an analog phase or delay time, a combination thereof, or the like. In some variations, the transmit phase may be wrapped (e.g., limited to [0, 2π) or [-π, π) radians). In some variations, the transmit phase may be unwrapped.

[0180] In some variations, the processor of the second device may be configured to select one or more transducer elements of the transducer array of the second device for transmitting wireless data or commands to the first device based on one or more of a signal strength of multipath interference, a signal-to-interference ratio (SIR), a signal-to-noise-and-interference ratio (SNIR), combinations thereof, etc. of a feedback signal received by the transducer elements of the transducer array. For example, the processor may be configured to select transducer elements that may have low multipath interference or high SNIR of the feedback signal for transmitting the wireless data or commands to the first device. This may facilitate high-fidelity data or command signals at the first device and / or higher downlink data rates, and may enable reliable detection of the data or commands at the first device. In some variations, the processor of the second device may be configured to select one or more transducer elements of the transducer array of the second device to transmit wireless power to the first device based on one or more of the signal strengths of the feedback signals received by the transducer elements of the transducer array (e.g., link efficiencies corresponding to the received feedback signals). This may provide high link efficiency for power transfer, thereby enabling faster wireless charging of the energy source of the first device.

[0181] In some variations, the received feedback signal may include a duration during which the amplitude settles. In some variations, the first duration of the transmitted feedback signal may be longer than a multipath time of the wireless link (e.g., to allow the amplitude of the received feedback signal to settle once multipath reflections have subsided). In some variations, the first duration of the transmitted feedback signal may be greater than approximately five cycles of the carrier frequency of the feedback signal. In some variations, the feedback signal may include one or more of an impulse signal and a pulse signal. In some variations, the pulse signal may include one or more of a rectangular pulse, a Dirac pulse, a sine pulse, a triangular pulse, a trapezoidal pulse, a raised cosine pulse, a sinc pulse, a Gaussian pulse, one or more cycles of the carrier frequency of the pulse signal, combinations thereof, etc.

[0182] In some variations, processing the feedback signal or determining the transducer array configuration of the second device may include one or more of time-domain analysis, frequency-domain analysis, interpolation analysis, combinations thereof, etc. In some variations, the time-domain analysis may include one or more of cross-correlation and time reversal. For example, a feedback signal (or a portion of the feedback signal with a settling amplitude) received on a transducer element may be cross-correlated with a feedback signal (or a portion of the feedback signal with a settling amplitude) received on another transducer element to determine their relative phase difference or delay time. In some variations, the relative phase difference or delay time may be inverted and applied to the transducer element to transmit a wireless signal to the first device (e.g., to achieve focusing of a power source or continuous wave signal at the transducer of the first device).

[0183] In some variations, the frequency domain analysis may include computing one or more of a Fourier transform, a discrete Fourier transform (DFT), a discrete-time Fourier transform (DTFT), combinations thereof, etc. at one or more predetermined frequencies. In some variations, computing one or more of a Fourier transform, a discrete Fourier transform (DFT), and a discrete-time Fourier transform (DTFT) at one or more predetermined frequencies may include using one or more of a fast Fourier transform (FFT) algorithm, a Goertzel algorithm, combinations thereof, etc. In some variations, applying the Goertzel algorithm to one or more predetermined frequencies may be computationally more efficient compared to determining a Fourier transform or DFT within a wide frequency band. In some variations, the one or more predetermined frequencies may be based on one or more feedback signal frequencies (e.g., carrier frequencies of the feedback signal). In some variations, determining the one or more predetermined frequencies may be based on one or more of a time-domain analysis and a frequency-domain analysis of a feedback signal received by one or more transducer elements of the transducer array within one or more of the first duration, the second duration, and the third duration. For example, the third duration may include one or more cycles of a carrier frequency of the received feedback signal. In some variations, the onset (e.g., rising edge) of a feedback signal pulse received on one or more transducer elements may be detected, and the third duration may be determined based on one or more of an onset time (e.g., timing of the rising edge of the feedback signal pulse) and a predetermined pulse width of the feedback signal. For example, the third duration may start at the onset time or a fixed time offset after the onset time (e.g., one or more cycles of the carrier frequency after the onset time) and end one or more cycles (e.g., five cycles) after the carrier frequency of the received feedback signal.

[0184] In some variations, the interpolation analysis may include interpolating one or more of the feedback signal data and the transducer array configuration from one or more transducer elements to one or more other transducer elements (e.g., adjacent transducer elements). For example, such interpolation analysis may be based on one or more interpolation techniques, such as spline interpolation, linear interpolation, cubic interpolation, combinations thereof, etc. In some variations, predetermined spatial positions of the transducer elements may be used for the interpolation (e.g., calculating transmit phases based on differences in path lengths for feedback signal propagation from a first device to different transducer elements of a second device). In some variations, the interpolation may enable transmitting wireless signals onto one or more transducer elements not configured to receive or process received feedback signals.

[0185] In some variations, determining the transducer array configuration of the second device may include using at least one of the feedback signal data and the predetermined power of the transmitted feedback signal to determine one or more of a link efficiency and a transmit power for transmitting the wireless signal to the first device. For example, the closed-loop powering methods described herein may be used to determine one or more of a link efficiency (e.g., uplink and / or downlink link efficiency) and a transmit power for transmitting the wireless signal from the second device to the first device.

[0186] In some variations, the one or more wireless signals exchanged with the first device may include one or more frequencies that are the same or different compared to the one or more frequencies of the feedback signal. For example, the feedback signal may include a carrier frequency f1, and a frequency-domain analysis of the received feedback signal may be performed to generate feedback signal data at frequency f2 (e.g., magnitude, phase, etc. of the received feedback signal), where f1 may not be equal to or equal to f2. In some variations, the feedback signal data may be generated at frequency f1 and / or frequency f2, and the transducer array configuration (e.g., transmit phase or delay time, apodization, transmit signal strength, transmit signal pulse width, etc.) may be determined at frequency f2 (e.g., by scaling the magnitude and phase at frequency f1 to frequency f2), where f1 may not be equal to f2 (e.g., f2 may be a harmonic of f1, a sub-harmonic of f1, or any frequency relative to f1).

[0187] In some variations, the transducer elements configured to receive the feedback signal and the transducer array configuration used to exchange wireless signals with the first device may include one or more common transducer elements. In some variations, the transducer elements used to receive the feedback signal and the transducer array configuration used to exchange wireless signals with the first device may include different transducer elements. In some variations, interpolation (e.g., based on adjacent transducer elements) may be used to determine the configuration of one or more transducer elements used to exchange wireless signals with the first device if one or more transducer elements were not used to receive or process the feedback signal.

[0188] In some variations, the first device may include an implantable medical device and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first device may include an external wireless device and the second device may include an implantable medical device configured to be located physically separate from the first device.

[0189] In some variations, the method (300) may include transmitting one or more feedback signals from the first device at one or more predetermined repetition intervals. In some variations, the predetermined repetition interval may correspond to a duration during which the wireless link may be quasi-static (e.g., a duration during which link efficiency may vary by less than about 3 dB) or a duration during which the first device may be stationary relative to the first device. In some variations, the first duration of the transmitted feedback signal may be the same or different within different repetition intervals. In some variations, the second duration of the received feedback signal may be the same or different within different repetition intervals. In some variations, the method (300) may include transmitting a wireless command from the second device to the first device and transmitting a feedback signal from the first device to the second device in response to receiving the wireless command. In some variations, the wireless command may include one or more of a wireless signal, a pulse signal, a plurality of pulse signals, a signal in which data bits are encoded (e.g., using on-off keying (OOK) modulation), combinations thereof, etc. In some variations, the transmitted feedback signal may include a reflected or backscattered signal in response to a radio signal transmitted by the second device to the first device. In some variations, the transmitted feedback signal may include one or more of an ultrasonic signal, an acoustic signal, a vibration signal, a radio frequency signal, an electromagnetic signal, a magnetic signal, an electrical signal, an optical signal, a combination thereof, or the like. In some variations, the transmitted feedback signal may be an ultrasonic or acoustic signal having a carrier frequency between about 20 kHz and about 20 MHz. In some variations, the first duration of the transmitted feedback signal may be between about 1 μs and 1 ms (e.g., including a pulsed signal having one or more cycles of the carrier frequency). In some variations, the second duration of the received feedback signal may be between about 1 μs and 100 ms (e.g., 500 μs to capture multipath reflections of the transmitted feedback signal pulse).

[0190] In some variations, the method (300) may include transmitting one or more data signals from the first device to the second device. In some variations, the method (300) may further include selecting one or more transducer elements (e.g., some or all) of a transducer array of the second device for processing the one or more data signals using a processor of the second device. In some variations, selecting one or more transducer elements of the transducer array of the second device may be based on one or more of the following: signal strength of the received feedback signal, signal-to-noise ratio of the received feedback signal, energy of the received feedback signal within one or more frequency bands, apodization of the transducer elements, a moving average of the feedback signal amplitude, signal strength of an interference source, signal strength of multipath interference, multipath time, combinations thereof, etc. In some variations, the method (300) may include transmitting one or more data signals from the second device to the first device.

[0191] 4 illustrates a timing diagram (400) of an exemplary variation of a feedback signal used in a method of exchanging wireless signals with a wireless device. As shown, a transmitted feedback signal (402) from a first device (e.g., a wireless implantable device) may include a first duration (404). During wireless propagation through a medium (e.g., an inhomogeneous tissue structure) between the first and second devices, the transmitted feedback signal (402) may be subject to multipath interference. A feedback signal (406) received by a transducer element during a second duration (408) is also shown. The received feedback signal (406) during the second duration (408) may include multipath reflections (410) due to multipath interference in the wireless link. In some variations, the second duration (408) may be longer than the duration required for the multipath reflections (410) or echoes to dissipate (e.g., the intensity of the multipath reflections dissipates to a particular level, such as 30 dB, below the intensity of the first received feedback signal pulse, or below a predetermined threshold level). The processor of the second device may be configured to process the received feedback signal (406) in the frequency domain. For example, the processor may be configured to calculate one or more of the magnitude (412) and phase (414) of a Fourier transform of the received feedback signal (406) within the second duration (or within a third duration obtained by zero-padding the received feedback signal) using one or more of an FFT algorithm and a Goertzel algorithm at one or more predetermined frequencies. In some variations, the processor may be configured to generate feedback signal data including one or more of a magnitude value Mag0 (416) and a phase value Phase0 (418) of the received feedback signal (406) at one or more predetermined frequencies, such as the carrier frequency of the transmitted feedback signal, shown as f0 in FIG. 4 .As an example, feedback signal data corresponding to received feedback signals of three transducer elements of a transducer array may include a magnitude of [85.8, 61.5, 32.0] in arbitrary units and a phase of [19.3, -89.6, 72.5] in degrees. Based on the feedback signal data, the processor may determine a transducer array configuration including apodization, or transmit a signal strength of [1.00, 0.72, 0.37] in arbitrary units and a phase of [0, -108.9, 53.2] degrees to transmit wireless signals to the first device over the three transducer elements. Apodization may be calculated by normalizing the magnitude to the maximum magnitude. The transmit phase may be calculated as the phase difference relative to a reference transducer element.

[0192] 5 is a flowchart generally illustrating a variation of a method 500 for exchanging wireless signals with a device based on a feedback signal. The method 500 may include the steps of: transmitting a feedback signal from a first device of a wireless system to a second device of the wireless system 502; receiving the feedback signal using a first transducer array of the second device 504; extracting, using a processor of the second device, one or more portions of the received feedback signal received by one or more transducer elements of the first transducer array of the second device 506; processing, using the processor of the second device, the extracted one or more portions of the received feedback signal to generate feedback signal data 508; determining, at least in part, a second transducer array configuration of the second device 510; and exchanging one or more wireless signals with the first device using the second transducer array configuration of the second device 512. As described herein, the feedback signal, transducer array, processor, transducer array configuration, feedback signal data, and wireless signal may be applied to any of the methods described herein. In some variations, the extracted portion or portions of the received feedback signal may have a duration that is shorter than the duration of the received feedback signal.

[0193] FIG. 6 shows a timing diagram (600) of an example variation of a feedback signal used in a method of exchanging wireless signals with a wireless device. As shown, a feedback signal (602) transmitted from a first device (e.g., a wireless implantable device) may experience multipath interference on the wireless link, such that a feedback signal (604) received by a second device (e.g., an external wireless device) may include various amplitude levels. In some variations, extracting one or more portions of the received feedback signal (604) may include finding one or more regions (606) of the received feedback signal waveform in which the amplitude is settled. In some variations, such regions (606) of the received feedback signal may correspond to a duration during which all major reflections of the feedback signal on the wireless link may be in a steady state. In some variations, such regions (606) of the received feedback signal may occur after the last major reflection of the feedback signal is received by the second device. In some variations, the duration of the transmitted feedback signal (602) may be greater than approximately five cycles of the carrier frequency of the feedback signal. This long duration of the feedback signal may allow the amplitude of the received feedback signal to settle, accounting for constructive and / or destructive interference from reflections of the feedback signal within the wireless link. In some variations, the duration of the transmitted feedback signal (602) may be selected based on the intended location of reflectors (e.g., ribs, lungs, tissue boundaries, etc.) within the wireless link relative to the locations of the first and second devices. For example, in some variations, if reflections within the wireless link are expected to settle within approximately 100 microseconds (e.g., settling within 5% or 1% of the signal amplitude), the duration of the feedback signal may be selected to be approximately 100 microseconds or longer.In some variations, the duration of the transmitted feedback signal (602) may be selected based on the multipath time of the link (e.g., the delay time between the arrival time of the direct line-of-sight signal or first reflection and the last reflection of the signal propagating from a first device to a second device in the wireless system). In some variations, extracting the portion of the received feedback signal may include detecting one or more regions of the received feedback signal waveform in which the envelope of the received feedback signal may not vary outside a predetermined percentage range (e.g., outside a ±5% range).

[0194] Optionally, in some variations, the method (500) may include detecting one or more rising and falling edges of the received feedback signal before extracting one or more portions of the received feedback signal. For example, a rising edge of the received feedback signal may be detected, a timing of the occurrence of the rising edge may be determined, and a region of the received feedback signal may be extracted starting from a time that may be a predetermined duration after the timing of the occurrence of the rising edge. Such a predetermined duration may be based on the multipath time of the wireless link or the time required for reflections in the link to settle. In some variations, detecting the rising and / or falling edges of the received feedback signal may be performed by comparing the amplitude envelope and / or energy of the received feedback signal with a predetermined threshold. In some variations, such comparison with a predetermined threshold may be performed in the time domain and / or the frequency domain (e.g., after calculating a Fourier transform or a short-time Fourier transform of the received feedback signal). In some variations, a running window or filter, or a matched filter, may be applied to the received feedback signal to detect the rising and / or falling edges. In some variations, the mean amplitude envelope and / or mean energy of the received feedback signal, averaged over a predetermined time duration, may be compared to a predetermined threshold to detect its rising and / or falling edges. For example, the received feedback signal may be digitized, and a rising edge may be detected by checking the time when a predetermined number of consecutive samples of the amplitude envelope of the received feedback signal exceed a predetermined threshold.

[0195] In some variations, the first transducer array (e.g., ultrasound array) of the second device may include multiple transducer elements (e.g., ultrasound transducer elements). In some variations, extracting one or more portions of the received feedback signal may be performed on feedback signals received by a subset of elements of the first transducer array. For example, transducer elements that may not receive sufficient signal strength of the received feedback signal (e.g., due to signal blockage by ribs) may be omitted from further processing to conserve computational resources. In some variations, extracting one or more portions of the received feedback signal may be performed only on one or more transducer elements of the first transducer array that may receive the highest signal strength or signal-to-noise ratio (SNR) of the feedback signal, or a signal strength or SNR above a predetermined threshold. In some variations, extracting one or more portions of the received feedback signal may be performed only on one or more transducer elements of the first transducer array that may have the highest link gain (or efficiency) with the first device, or a link gain (or efficiency) with the first device above a predetermined threshold. In some variations, extracting one or more portions of the received feedback signal may be performed only on one or more predetermined transducer elements of the first transducer array of the second device.

[0196] In some variations, the method (500) may further include digitizing the feedback signal received by one or more transducer elements of the first transducer array before extracting one or more portions of the received feedback signal. In some variations, the method (500) may further include detecting a rising edge of the received feedback signal using analog signal processing before digitizing the feedback signal received by the one or more transducer elements of the first transducer array. For example, such analog signal processing may include one or more of envelope detection (e.g., using an envelope detector circuit), integration (e.g., using a charge integration-based wait timer circuit), comparison with a predetermined threshold (e.g., using a comparator and reference generator circuit), combinations thereof, etc. In some variations, extracting one or more portions of the received feedback signal is performed using one or more of digital signal processing, analog signal processing, combinations thereof, etc.

[0197] In some variations, the feedback signal data may include one or more of: absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute arrival time, relative arrival time, frequency, duration, number of cycles, absolute signal-to-noise ratio, relative signal-to-noise ratio, combinations thereof, etc. of a feedback signal received by one or more transducer elements of a first transducer array of the second device. In some variations, the relative amplitude, signal strength, phase, and / or delay time of a given transducer element may be relative to another transducer element of the second device. In some variations, determining the configuration of the second transducer array of the second device may include determining one or more of amplitude, signal strength, phase, delay time, frequency, duration, number of cycles, combinations thereof, etc. for transmitting wireless signals through one or more transducer elements of the second transducer array. In some variations, determining one or more of amplitude, signal strength, phase, delay time, frequency, duration, number of cycles, combinations thereof, etc. to transmit the wireless signal through one or more transducer elements of the second transducer array may include performing one or more of cross-correlation, time reversal, frequency domain analysis (e.g., calculating one or more of a Fourier transform, a DFT, a DTFT using one or more of an FFT and a Goertzel algorithm), interpolation analysis (e.g., based on adjacent transducer elements), combinations thereof, etc. In some variations, the time reversal may include inverting a delay time or phase of a received feedback signal received from the first device by one or more transducer elements of the transducer array of the second device to transmit the wireless signal to the first device.In some variations, time reversal may result in focusing of the ultrasound beam on the first device, which may be advantageous for efficient wireless power delivery to the first device (e.g., a wireless implantable device).

[0198] In some variations, the cross-correlation described herein may include calculating a sliding dot product of at least two received feedback signals received by at least two transducer elements of a first transducer array of the second device. In some variations, the cross-correlation may be performed to determine a relative delay time, lag, or phase difference between the at least two received feedback signals. In some variations, the relative delay time, lag, or phase difference between the at least two received feedback signals may be inverted upon transmitting a wireless signal (e.g., power) from the second device to the first device. In some variations, the feedback signals received on one or more transducer elements of the first transducer array may be cross-correlated to a received feedback signal having the highest signal strength or amplitude, SNR, and / or link gain. In some variations, the received, digitized feedback signals may be resampled (e.g., using upsampling, interpolation, extension, etc.) before cross-correlation to change (e.g., increase) the resolution of the relative delay time, lag, and / or phase difference calculated using cross-correlation. In some variations, one or more received feedback signals may be normalized (e.g., by scaling the amplitude of the signal and setting its maximum value to 1) before cross-correlation. In some variations, to reduce the amount of computation, the cross-correlation between two or more received feedback signals may be performed using a maximum lag (or time shift) based on the period of the received feedback signals. For example, the maximum lag of the cross-correlation may be set to one period of the carrier frequency of the feedback signals.

[0199] In some variations, determining one or more of the amplitude and signal strength for transmitting the wireless signal through one or more transducer elements of the second transducer array may include one or more of envelope detection, energy detection within a predetermined frequency band (e.g., a bandwidth centered on the carrier frequency of the transmitted feedback signal), comparison of relative signal strengths received on different transducer elements of the first transducer array, combinations thereof, etc. Signal processing to determine such transmit amplitude or signal strength may be performed on one or more extracted portions of the received feedback signal. Relative transmit signal strengths calculated based on determining the relative amplitudes of settled regions of the received feedback signal may be useful for efficiently powering the first device from the second device.

[0200] In some variations, determining one or more of the amplitude, signal strength, phase, and delay for transmitting the wireless signal through one or more transducer elements of the second transducer array may further include interpolating one or more of the amplitude, signal strength, phase, and delay based on the relative spatial positions of the transducer elements of the first and second transducer arrays. For example, the first transducer array may include alternating transducer elements of a one-dimensional second transducer array including a plurality of equally spaced transducer elements. In this case, one or more of the amplitude, signal strength, phase, and delay determined for the elements of the first transducer array may be interpolated (e.g., using spline interpolation, linear interpolation, etc.) to determine one or more of the amplitude, signal strength, phase, and delay of one or more transducer elements of the second transducer array. In some variations, the phase may be unwrapped before interpolation to obtain a continuous phase signal that is not constrained to a major value of (-π,π) or [0,2π] radians. In some variations, determining the configuration of the second transducer array may also include a closed-loop powering method as described herein.

[0201] In some variations, the first device may include an implantable medical device, and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first transducer array and the second transducer array may include one or more common transducer elements (e.g., the same set of transducer elements). In some variations, the first transducer array may include a subset of the second transducer array. In some variations, the first transducer array and the second transducer array may include separate transducer elements. In some variations, the first transducer array and the second transducer array may each include an acoustic (e.g., ultrasound) transducer array.

[0202] FIG. 7 shows a cross-sectional schematic diagram (700) of variations of the ultrasound beam and transmit signal strength of an ultrasound transducer array. The relative transmit signal strength or apodization of the transducer elements (722) of the transducer array (720) of the second device (714) is shown. Apodization may refer to the relative amplitude weighting applied to different transducer elements of the transducer array. The relative transmit signal strength and corresponding transmit delay (not shown) may be calculated using any of the methods previously described. This transducer configuration of the second transducer array (720) results in an ultrasound beam (742) being focused at the location of the wireless implantable device (710) implanted in thoracic tissue (770), including the rib cage or ribs (772).

[0203] b. Radio signal exchange based on link scan signals In some variations, it may be undesirable to transmit a feedback signal of long duration (e.g., more than about five cycles of the carrier frequency of the feedback signal). For example, it may be desirable to avoid transmitting a feedback signal of long duration from a wireless implantable device due to its limited energy budget (e.g., a small implantable device may not have sufficient stored energy, or it may be advantageous to utilize its stored energy for other operations, such as sensing or stimulation). This may be particularly difficult in wireless systems that experience multipath interference. For example, as described in the example above, in some variations, if the multipath time in the wireless system is about 100 microseconds, a feedback signal duration of about 100 microseconds or longer may be required to allow the amplitude of the received feedback signal to settle. However, a battery-less wireless implantable device may not have enough energy to transmit such a long duration feedback signal. Solutions to overcome this challenge are provided herein.

[0204] In some variations, the method of exchanging wireless signals may be based on a link scan signal, as described herein. Figure 8 is a flowchart generally illustrating a variation of a method (800) of exchanging wireless signals with a device based on a link scan signal. The method (800) may include the steps of: transmitting a link scan signal from a first device of a wireless system to a second device of the wireless system (802); receiving the link scan signal using a first transducer array of the second device (804); processing the received link scan signal, received by one or more transducer elements of the first transducer array of the second device, using a processor of the second device to generate link scan signal data (806); determining a second transducer array configuration of the second device based at least in part on the link scan signal data (808); and exchanging one or more wireless signals with the first device using the second transducer array configuration of the second device (810). As described herein, the link scan signal, transducer array, processor, transducer array configuration, link scan signal data, and wireless signal may be applied to any of the methods described herein.

[0205] In some variations, the link scan signal may include one or more of an impulse signal, a pulse signal, combinations thereof, etc. In some variations, the pulse signal may include one or more cycles of a carrier frequency of the pulse signal. In some variations, the pulse signal may include one or more of a rectangular pulse, a Dirac pulse, a sine pulse, a triangular pulse, a trapezoidal pulse, a raised cosine pulse, a sinc pulse, a Gaussian pulse, one or more cycles of a carrier frequency of the pulse signal, combinations thereof, etc.

[0206] In some variations, processing the received link scan signal received by the transducer elements of the first transducer array may include determining an impulse response of the wireless system. For example, if the transmitted link scan signal includes an impulse signal, the received link scan signal may include an impulse response of the wireless system. In some variations, the impulse response of the wireless system may be determined based on the received link scan signal and the transmitted link scan signal. For example, the impulse response of the wireless system may be determined by a processor of the second device by performing a deconvolution of the received link scan signal with a reference link scan signal (e.g., the transmitted link scan signal). In some variations, a Fourier transform of the received link scan signal may be divided by a Fourier transform of the transmitted link scan signal to determine the impulse response of the wireless system.

[0207] In some variations, processing the received link scan signal may further include performing a convolution of an impulse response of the wireless system corresponding to one or more transducer elements of the first transducer array with one or more template signals. The template signal may be any signal generated and / or received by a processor of the second device. For example, the template signal may include a sine wave or rectangular pulse having one or more cycles of a carrier frequency. In some variations, the template signal may represent or be the same as a transmitted feedback signal of the method (500) of exchanging wireless signals based on a feedback signal. In some variations, the template signal may include one or more of a rectangular pulse, a Dirac pulse, a sine wave pulse, a triangular wave pulse, a trapezoidal wave pulse, a raised cosine pulse, a sinc pulse, a Gaussian pulse, one or more cycles of a carrier frequency of the pulse signal, combinations thereof, etc. In some variations, the duration of the template signal may be greater than approximately five cycles of the carrier frequency of the template signal. In some variations, the same template signal may be used to process link scan signals received by different transducer elements of the first transducer array of the second device. In some variations, different template signals may be used to process link scan signals received by different transducer elements of the first transducer array of the second device. Considerations regarding the duration of the feedback signal discussed herein (e.g., a duration of the feedback signal that is equal to or greater than the multipath time of the wireless link) may also be applicable to the duration of the template signal.

[0208] In some variations, the link scan signal data may include the output signal of the convolution of the template signal and the received link scan signal, or any property of the output signal of the convolution (e.g., amplitude, delay time, phase, frequency, etc.). In some variations, the link scan signal data may include one or more of the absolute amplitude, relative amplitude, absolute signal strength, relative signal strength, apodization, absolute phase, relative phase, absolute delay time, relative delay time, combinations thereof, etc. of the output signal of the convolution. In some variations, the relative amplitude, signal strength, phase, and / or delay time of a given transducer element may be relative to another transducer element of the second device.

[0209] FIG. 9 is a timing diagram (900) of an example variation of a signal used in a method of exchanging wireless signals using a link scan signal. As shown, in some variations, a transmitted link scan signal (902) transmitted by a first device in a wireless system may include a short-duration rectangular pulse that may approximate a Dirac pulse or a Dirac delta function. Such a link scan signal may be advantageous for measuring the impulse response of the wireless system (e.g., to characterize the transfer function of a wireless link in the wireless system) or for measuring an approximate impulse response or a scaled impulse response of the wireless system. Also shown is a conceptual representation of a corresponding received link scan signal (904) received by a transducer element of a first transducer array of a second device in the wireless system. The received link scan signal (904) may include a carrier frequency and bandwidth based on the resonant frequency and bandwidth of one or more of the transducers of the first device and the second device. Additionally, the received link scan signal (904) may include one or more pulse signals due to multipath interference (reflections of the received link scan signal from one or more reflectors or scatterers in the wireless link). Also shown is an example of a template signal (906) including multiple cycles of a carrier frequency. The received link scan signal (904) may be convolved with the template signal (906) by a processor of the second device to generate an output signal (908) of the convolution. In some variations, the output signal (908) of the convolution may emulate the received feedback signal of the method (500) of exchanging wireless signals based on a feedback signal. In some variations, the output signal (908) of the convolution may be further processed using processing steps similar to those applied to the received feedback signal in the method (500) of exchanging wireless signals based on a feedback signal described herein.

[0210] In some variations, determining the configuration of the second transducer array of the second device may include determining one or more of amplitude, signal strength, phase, delay time, combinations thereof, etc. for transmitting wireless signals through one or more transducer elements of the second transducer array. In some variations, determining one or more of amplitude, signal strength, phase, and delay time for transmitting wireless signals through one or more transducer elements of the second transducer array may include performing one or more of cross-correlation, time reversal, combinations thereof, etc. The cross-correlation and time reversal steps described herein may be applicable here as well.

[0211] In some variations, determining one or more of amplitude, signal strength, phase, and delay time for transmitting the wireless signal through one or more transducer elements of the second transducer array may further include interpolating one or more of amplitude, signal strength, phase, and delay time based on relative spatial positions of the transducer elements of the first transducer array and the second transducer array. In some variations, determining the configuration of the second transducer array may include a closed-loop feeding method. The interpolation steps described herein may be applicable here as well.

[0212] In some variations, the first device may include an implantable medical device, and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first transducer array and the second transducer array may include one or more common transducer elements (e.g., the same set of transducer elements). In some variations, the first transducer array may include a subset of the second transducer array. In some variations, the first transducer array and the second transducer array may include separate transducer elements. In some variations, the first transducer array and the second transducer array may each include an acoustic (e.g., ultrasound) transducer array.

[0213] In some variations, the first transducer array (e.g., ultrasound array) of the second device may include multiple transducer elements (e.g., ultrasound transducer elements). In some variations, processing the received link scan signal may be performed on link scan signals received by a subset of elements of the first transducer array. For example, transducer elements that may not receive sufficient signal strength of the received link scan signal (e.g., due to signal blockage by ribs) may be omitted from further processing to conserve computational resources. In some variations, processing the received link scan signal may be performed only on one or more transducer elements of the first transducer array that may receive the highest signal strength or signal-to-noise ratio of the link scan signal, or a signal strength or SNR above a predetermined threshold. In some variations, processing the received link scan signal may be performed only on one or more transducer elements of the first transducer array that may have the highest link gain (or efficiency) with the first device, or a link gain (or efficiency) with the first device that is above a predetermined threshold. In some variations, processing the received link scan signal may be performed only on one or more predetermined transducer elements of the first transducer array of the second device.

[0214] c. Exchange of radio signals based on feedback signals and link scan signals In some variations, the method of exchanging wireless signals may be based on feedback signals and link scan signals, as described herein. Figure 10 is a flowchart generally illustrating a variation of a method (1000) of exchanging wireless signals with a device based on feedback signals and link scan signals. The method (1000) may include the steps of transmitting (1002) a link scan signal and a feedback signal from a first device of a wireless system to a second device of the wireless system; receiving (1004) the link scan signal and the feedback signal using a first transducer array of the second device; processing (1006) the received link scan signal and the received feedback signal received by one or more transducer elements of the first transducer array of the second device using a processor of the second device to generate feedback signal data; determining (1008) a second transducer array configuration of the second device based at least in part on the feedback signal data; and exchanging (1010) one or more wireless signals with the first device using the second transducer array configuration of the second device. As described herein, the feedback signal, link scan signal, transducer array, processor, transducer array configuration, feedback signal data, link scan signal data, and wireless signal are applicable to any of the methods described herein.

[0215] In some variations, processing the received link scan signal and the received feedback signal may include performing a deconvolution of the received link scan signal and the received feedback signal. In some variations, processing the received link scan signal received by the transducer elements of the first transducer array may include determining an impulse response of the wireless system. In some variations, processing the received link scan signal and the received feedback signal may include performing a deconvolution of the received feedback signal with an impulse response of the wireless system or a scaled impulse response of the wireless system. In some variations, the method (1000) may further include extracting, using a processor of the second device, one or more portions of the deconvolution output signal. In some variations, extracting one or more portions of the deconvolution output signal may include finding one or more regions of the deconvolution output signal where the amplitude is settled.

[0216] In some variations, determining the second transducer array configuration of the second device may include determining one or more of amplitude, signal strength, phase, and delay time for transmitting the wireless signal through one or more transducer elements of the second transducer array. In some variations, determining one or more of amplitude, signal strength, phase, and delay time for transmitting the wireless signal through one or more transducer elements of the second transducer array may include performing one or more of cross-correlation and time-reversal. The cross-correlation and time-reversal steps may be applicable here as well.

[0217] In some variations, determining one or more of an amplitude, signal strength, phase, and delay for transmitting the wireless signal through one or more transducer elements of the second transducer array may further include interpolating one or more of the amplitude, signal strength, phase, and delay based on relative spatial positions of the transducer elements of the first transducer array and the second transducer array. Interpolation steps described herein may be applicable here as well. In some variations, determining the second transducer array configuration includes a closed-loop powering method.

[0218] In some variations, the first device may include an implantable medical device, and the second device may include an external wireless device configured to be located physically separate from the first device. In some variations, the first transducer array and the second transducer array may include one or more common transducer elements (e.g., the same set of transducer elements). In some variations, the first transducer array may include a subset of the second transducer array. In some variations, the first transducer array and the second transducer array may include separate transducer elements. In some variations, the first transducer array and the second transducer array may each include an acoustic (e.g., ultrasound) transducer array.

[0219] In some variations, particular transducer elements of the first transducer array may be selected to process their corresponding feedback signals and link scan signals using criteria similar to those described for the method of exchanging wireless signals based on feedback signals (500) and the method of exchanging wireless signals based on link scan signals (800).

[0220] d. Defocus-based wireless signal exchange In some variations, the transducer array configuration of the second device determined using the above method may not be sufficient to exchange wireless signals with the first device if the first device exhibits excessive motion relative to the second device. For example, a wireless implantable device implanted in the heart may move relative to a stationary external wireless device positioned on the patient's chest. In some cases, after transmitting a feedback signal and / or a link scan signal, the wireless implantable device may move to a different position relative to the external wireless device, which then processes the received feedback signal and / or the received link scan signal and transmits power to the wireless implantable device's original position. This may result in insufficient wireless power delivery to the wireless implantable device, thereby significantly limiting its functionality. A solution to overcome this problem is provided herein.

[0221] In some variations, defocusing of a wireless beam (e.g., an ultrasound beam) may be intentionally performed to exchange wireless signals with a moving wireless implantable device. Defocusing of a wireless signal beam may refer to one or more of increasing the spot size of the wireless signal beam at one or more locations in a region (e.g., one or more locations within a body), decreasing the directionality of the wireless signal beam, decreasing the intensity of the wireless signal beam at one or more locations in a region, combinations thereof, etc. For example, defocusing of a wireless signal beam may be performed to achieve a large beam diameter of the wireless signal near the location of the wireless implantable device so that the wireless implantable device can receive a wireless signal of relatively uniform intensity (or achieve relatively low variation in the intensity of the wireless signal) despite movement of the wireless implantable device. In some variations, defocusing of a wireless signal beam may be useful to accommodate the range of motion of a wireless implantable device (e.g., an intracardiac device that may move due to heartbeat or breathing) over a given duration to enable reliable and efficient wireless power (or charging) and wireless data communication between the wireless implantable device and an external device. In some variations, defocusing the radio beam may be desirable to reduce the strength or power of the radio signal within the body to minimize tissue heating and / or to operate at safe strength or power levels within the body.

[0222] In some variations, a method for exchanging wireless signals between a first device of a wireless system and a second device of the wireless system may include the above method based on one or more of a feedback signal and a link scan signal. A transducer array configuration of the second device may be determined, including one or more of a set of transducer elements of the transducer array, signal strength, amplitude, apodization, delay time, phase, combinations thereof, etc. Parameters of the transducer configuration may be determined using techniques such as cross-correlation and / or time reversal as described herein. In some variations, the parameters of the transducer configuration may be further adjusted to defocus the beam.

[0223] In some variations, the aperture and / or apodization of the transducer array may be adjusted to defocus the beam. In some variations, a smaller sub-aperture or sub-array of the transducer array of the second device may be selected (e.g., by turning off other transducer elements of the array) to exchange wireless signals with the first device, since a smaller aperture may correspond to a wider beam diameter. For example, a sub-array (comprising a contiguous set of transducer elements or a discontinuous set of transducer elements) may be selected by selecting transducer elements that receive a feedback signal strength greater than a predetermined threshold. In some variations, a sub-array may be selected by selecting transducer elements whose apodization (determined after processing the received feedback signal and / or the received link scan signal) is greater than a predetermined threshold (e.g., greater than about 0.5). In some variations, a sub-array may be selected by selecting transducer elements adjacent to or near a transducer element with a maximum or minimum delay or phase.

[0224] In some variations, multiple feedback signals and / or link scan signals may be received from the first device corresponding to one or more positions of the first device relative to the second device. Such multiple received feedback signals and / or received link scan signals may be processed by a processor of the second device to generate multiple apodization and / or delay profiles using one or more of cross-correlation, time reversal, combinations thereof, etc. In some variations, the transducer array configuration of the second device for exchanging wireless signals with the first device may include an average of multiple apodization and / or delay profiles. Such an average apodization and / or delay profile may result in a wider beam diameter covering the range of motion of the first device. In some variations, the delay profile selected for exchanging wireless signals with the first device may include a delay profile corresponding to a wireless implantable device location whose apodization profile is closest (or most similar) to the average apodization profile across the multiple wireless implantable device locations.

[0225] In some variations, the phase and / or delay applied to the transducer elements of the transducer array may be adjusted to defocus the beam. In some variations, the curvature of the delay or phase profile across the transducer array of the second device may be adjusted (e.g., increased or decreased) to shift the focal point of the ultrasound beam to a position between the first device and the second device, or beyond the first device to a position further away from the second device. In doing so, a wider beam diameter may be achieved near the position of the first device (thereby covering its range of motion) compared to if the beam were directly focused at one of the positions of the first device. In some variations, one or more of noise (e.g., Gaussian noise, white noise, etc.), fluctuations, perturbations, combinations thereof, etc. may be added (e.g., by a processor of the second device) to one or more of the phases and delays (or relative phases and / or relative delays) (e.g., phases and / or delays comprising the transducer array configuration of the second device) applied to one or more transducer elements of a transducer array of the second device for transmitting signals to the first device to achieve defocusing of the beam (e.g., an acoustic beam near the location of the first device). In some variations, adding noise, fluctuations, and / or perturbations to the transmit phases and / or delays applied to the transducer elements may enable the spot size or beam diameter of the wireless signal to be increased by intentionally creating a small incoherent wireless signal at the target location (e.g., the location of the wireless implantable device or its transducer).

[0226] In some variations, the frequency of the wireless signal transmitted by the transducer array of the second device may be adjusted to defocus the beam. In some variations, a lower frequency may be selected because a lower frequency may result in a wider beam diameter due to a longer wavelength. In some variations, a feedback signal may be received by the second device from the first device at a first frequency, but power may be transmitted by the second device to the first device at a second frequency, which may be lower than the first frequency. In some variations, the same apodization and delay time calculated based on the feedback signal at the first frequency may be utilized to transmit the wireless signal to the first device at the second frequency. Using a lower second frequency to transmit wireless power may result in a wider beam diameter and less tissue loss, thereby enabling reliable power transmission to the first device despite movement of the first device relative to the second device.

[0227] e. Closed loop power supply A closed-loop power supply method is described herein. In some variations, when a wireless system transmits wireless power from a second device to a first device, the closed-loop power supply method may be used to target a power level required for the first device. The absolute signal strength transmitted by the transducer elements of the transducer array of the second device, or the total transmit power of the second device, may be determined based on the closed-loop power supply method.

[0228] In some variations, the power of the feedback signal transmitted by the first device may be known, P TX,fb The power of the feedback signal received by the second device can be expressed as P RX,fb The processor of the second device may calculate the uplink link gain or uplink link efficiency, η アップリンク(i.e., the gain or efficiency of a signal propagating from a first device to a second device). The uplink link efficiency may be given by the following equation:

number

[0229] In some variations, the downlink link efficiency, η ダウンリンク (i.e., the gain or efficiency of the signal propagating from the second device to the first device) is the measured uplink link efficiency, η アップリンク In some variations, based on the reciprocity of the wireless link, the downlink link efficiency may be determined to be equal to or substantially equal to the uplink link efficiency. In some variations, the downlink link efficiency may differ from the uplink link efficiency (e.g., when the link gain includes one or more non-reciprocal gain components). The downlink link efficiency, η ダウンリンク is the target received power level (P) at the first device when wirelessly powering the first device from the second device using the following formula: RX,電力 ), and the transmission power from the second device (P TX,電力 ) may be related.

number

[0230] Assuming the downlink link efficiency is equal to the uplink link efficiency of the reciprocal system, the required transmit power level from the second device may be calculated as follows:

number

[0231] In some variations, to maintain sufficient margin for link variations or anomalies, the total transmit power level of the transducer array of the second device may be selected to be greater than the value calculated using the above equation. Based on the calculated total transmit power level of the transducer array, the absolute transmit signal strengths of the individual transducer elements of the array may be determined based on their relative signal strengths and the impedance of the transducer elements.

[0232] In some variations, the total transmit power level required for the second device may be determined based on feedback from the first device. For example, the first device may be configured to digitize its received voltage or power level and transmit this digitized voltage or power level via one or more feedback signals to the second device, and the second device may adjust (increase or decrease) its transmit power to achieve the voltage or power level required for the first device.

[0233] In some variations, the first device may include an implantable medical device and the second device may include an external wireless device configured to be located physically separate from the first device.

[0234] B. Decoding wireless data signals In some variations, wireless data communications in wireless systems may be affected by multipath interference due to reflections of wireless signals propagating over the wireless link from inhomogeneous media and structures. Multipath interference may corrupt the wireless data signal waveform received by a receiving device in the wireless system. Decoding such wireless data signals using conventional techniques may result in undesirable bit errors. For example, a wireless implantable device implanted within the heart may sense a physiological parameter (e.g., pressure), digitize it, and transmit the digitized physiological parameter data to an external wireless device via an ultrasound uplink data signal. The ultrasound uplink data signal may be subject to multipath interference due to reflections and / or scattering of ultrasound waves from ribs, lungs, and / or other tissue boundaries. This may result in corruption of the uplink data signal waveform received by the external wireless device and bit errors in the decoded physiological parameter data, which may lead to improper or inaccurate management of a patient's disease. Solutions for overcoming such challenges are provided herein.

[0235] In some variations, wireless data communication between two wireless devices may utilize a link scan signal. Figure 11 is a flowchart generally illustrating a variation of a method (1100) for decoding a data signal in a wireless system. The method (1100) may include the steps of transmitting (1102) a link scan signal and a first data signal from a first device in the wireless system to a second device in the wireless system, receiving (1104) the link scan signal and the first data signal using one or more transducer elements of the second device, processing (1106) the received link scan signal and the received first data signal using a processor of the second device to generate a second data signal, and decoding (1108) the first data signal based at least in part on the second data signal. As described herein, the link scan signal, data signals (first data signal, second data signal), transducer elements, and processor are applicable to any of the methods described herein.

[0236] In some variations, the link scan signal may include one or more of a feedback signal, an impulse signal, a pulse signal, a pulse signal representing a single data bit of the first data signal, a pulse signal representing multiple data bits of the first data signal, a header signal, a footer signal, a predetermined digital code, a continuous wave signal, multiple impulse signals, multiple pulse signals, combinations thereof, etc. In some variations, the pulse signal may include one or more of a rectangular pulse, a Dirac pulse, a sine pulse, a triangular pulse, a trapezoidal pulse, a raised cosine pulse, a sinc pulse, a Gaussian pulse, one or more cycles of a carrier frequency of the pulse signal, combinations thereof, etc. In some variations, the link scan signal may include a portion of the first data signal. For example, the link scan signal may include one or more header and / or one or more footer sections of the first data signal. In some variations, there may be a delay time between the link scan signal and the first data signal (e.g., a delay time to capture multipath reflections of the impulse signal, feedback signal, or pulse signal). In some variations, there may be no time gap between the link scan signal and the first data signal (eg, they may be continuous waveforms).

[0237] In some variations, the first data signal may include one or more of an uplink data signal and a downlink data signal, hi some variations, the first data signal may include one or more of on-off keying (OOK) modulation, amplitude shift keying (ASK) modulation, pulse position modulation (PPM), frequency shift keying (FSK) modulation, phase shift keying (PSK) modulation, quadrature amplitude modulation (QAM), combinations thereof, etc.

[0238] In some variations, processing the received link scan signal and / or the received first data signal received by one or more transducer elements and described in any of the methods herein may include one or more of analog signal processing, digital signal processing, signal amplification, low pass filtering (e.g., anti-aliasing filtering), digitization, deconvolution of the received link scan signal or wireless system impulse response with the received data signal, band pass filtering (e.g., to remove out-of-band thermal noise, thereby increasing the SNR), matched filtering (e.g., to detect bits, headers, footers, etc. within the data signal), cross correlation (e.g., determining the relative lag or delay between two data signals in order to delay and sum them), autocorrelation, signal combining (e.g., to increase the SNR of a data signal), delaying and summing two or more data signals (e.g., to increase the SNR), digital demodulation (e.g., OOK demodulation), comparison to a predetermined threshold, combinations thereof, and the like.

[0239] In some variations, the link scan signal and the first data signal received by different transducer elements or channels of the second device may first be individually processed (e.g., using amplification, digitization, low-pass filtering, deconvolution, matched filtering, cross-correlation, combinations thereof, etc.) to generate second data signals corresponding to each of the processed channels. One or more of the second data signals from the different channels may then be combined with each other (e.g., using cross-correlation to determine relative lags, delaying and summing to combine the signals, combinations thereof, etc.), and data may then be decoded from the combined signal (e.g., by applying a matched filter to the combined signal, comparing the envelope of the output to a predetermined threshold, and detecting "1" or "0" bits depending on the result of the comparison). Combining the signals may be to improve the SNR and / or signal-to-interference ratio (SIR) to reduce the number of bit errors or bit error rate in the decoded data. In some variations, instead of performing a signal combining operation on all processed channels, specific channels may be selected for signal combining. In some variations, such channels selected for signal combining may be channels in which the second data signal may have the highest SNR, SIR, SNR above a predetermined threshold, SIR above a predetermined threshold, correction values ​​for header bits of the data stream, combinations thereof, etc.

[0240] In some variations, upon generating a second data signal corresponding to each of the processed channels, instead of combining the signals and then decoding the data, data decoding may be performed on multiple second data signals. In some variations, the final result of the decoded data bit may be determined based on the majority occurrence rate of the bit (e.g., if multiple first decoded bits of a processed channel are “1,” the first decoded bit may be designated as “1”). In some variations, the link scan signal and the received first data signal received from multiple channels may be combined before processing and generating the second data signal. For example, the link scan signal and the received first data signal received from multiple channels or transducer elements of the transducer array of the second device may be delayed or summed based on one or more of a delay calculated using cross-correlation, a delay determined from processing a feedback signal, a delay determined or used in a previous iteration of the method for decoding wireless data signals described herein, a delay determined or used in a previous iteration of the method for exchanging wireless signals described herein, combinations thereof, etc.

[0241] In some variations, the processor of the second device may be configured to detect onsets (e.g., rising edges, time of arrival) of one or more of the received link scan signal and the received first data signal. In some variations, the onset detection may include using one or more of envelope detection, predetermined timing (e.g., based on knowledge of the times when the first device may transmit the link scan signal or the first data signal and the signal propagation delay from the first device to the second device), coherent detection, and comparing the amplitude of the received feedback signal to a threshold level (e.g., a predetermined threshold).

[0242] In some variations, processing the received link scan signal and the first data signal may include selecting one or more durations of one or more of the received link scan signal and the received first data signal, and then further processing based on one or more of a predetermined timing, signal onset detection, detection of one or more of a signal rising edge and a signal falling edge, detection of one or more of a signal header component and a footer component, and multipath time and drift in the frequency of the received first data signal. In some variations, the timing of the rising edge of one or more of the link scan signal (e.g., a feedback signal pulse) and the first data signal may be detected (e.g., using envelope detection and comparing the envelope to a predetermined threshold), and the durations for processing the link scan signal and the first data signal may be selected based on a predetermined fixed time offset before or after the time of the rising edge. The fixed time offset before the timing of the rising edge may be determined based on the difference between the minimum and maximum propagation delays of wireless signals between different transducer elements of the first and second devices. The fixed time offset after the timing of the rising edge may be determined based on one or more of the duration of the link scan signal transmitted by the first device, the duration of the first data signal transmitted by the first device, the duration of the multipath interference (e.g., multipath time), and detection of one or more terminations (e.g., falling edges, footers, etc.) of the link scan signal and the first data signal.

[0243] In some variations, one or more signals processed herein may be zero-padded before further processing (e.g., to match a predetermined number of samples for a digital processing operation such as an FFT calculation). For example, as described herein, signals may be zero-padded before a deconvolution operation and / or a convolution operation. In some variations, one or more signals processed herein may be filtered (e.g., using one or more of a band-pass filter, a low-pass filter, a high-pass filter, an all-pass filter, a notch filter, and a band-reject filter). In some variations, one or more signals processed herein may undergo one or more of a time-domain to frequency-domain transformation (e.g., using an FFT operation) and a frequency-domain to time-domain transformation (e.g., using an inverse FFT operation) to perform processing in one or more of the frequency domain or the time domain. In some variations, one or more signals processed herein may be upsampled, downsampled, or resampled before further processing. For example, the two signals may be upsampled (e.g., one or more interpolation techniques, such as spline interpolation, may be used to increase the sampling frequency of the signals) before cross-correlation to obtain finer time resolution of their relative lag or delay time. In some variations, one or more signals processed herein may be scaled or normalized before further processing. For example, both two signals may be normalized (e.g., over an amplitude range of -1 to +1) before cross-correlation or deconvolution.

[0244] In some variations, processing the received link scan signal may include determining an impulse response or a scaled impulse response of the wireless system. Determining the impulse response may characterize a transfer function of the wireless link, as described herein, that enables accurate data decoding in the presence of multipath interference. In some variations, the received link scan signal itself may represent the impulse response or the scaled impulse response of the wireless system (e.g., where the link scan signal may include an impulse signal). In some variations, the scaled impulse response of the wireless system may include the impulse response of the wireless system scaled by a predetermined factor that may have a value of 1 or a value other than 1.

[0245] In some variations, determining the scaled impulse response of the wireless system (e.g., a transfer function of the wireless system or wireless link) may include deconvolving the scaled received link scan signal (e.g., a feedback signal) with a scaled reference link scan signal (e.g., a reference feedback signal) using one or more of a frequency domain (or Laplace domain) analysis and a time domain analysis.

[0246] In some variations, the scaled signals described herein (e.g., impulse response, received feedback signal, reference feedback signal, received link scan signal, reference link scan signal, received first data signal, second data signal, combined data signal, combinations thereof, etc.) may include signals scaled by one or more of: the amplitude of the signal in the time domain, the amplitude of the signal in frequency, the energy of the signal in one or more frequency bands, the signal-to-noise ratio, the apodization of the corresponding transducer element receiving the signal, a predetermined scaling factor (e.g., a scaling factor of 1 or a value other than 1), a scaling factor for normalization, combinations thereof, etc. In some variations, scaling the signal (e.g., reducing the maximum amplitude of the signal) may be performed before the operation (e.g., multiplication by or convolution with another signal) to avoid saturation of the amplitude of the resulting signal relative to amplitude limits (e.g., the maximum number of bits of an FPGA register). In some variations, scaling the signals by their SNR values ​​before combining them may enable generating a combined signal having a higher SNR compared to a combined signal obtained without pre-scaling the signals.

[0247] In some variations, the scaled reference link scan signal may represent a link scan signal transmitted by the first device (i.e., before the link scan signal propagates through a wireless link). In some variations, the scaled reference link scan signal may include an ideal link scan signal (e.g., an ideal impulse, an ideal rectangular pulse). In some variations, a method of decoding a data signal in a wireless system may include preloading (or storing) a scaled reference link scan signal (e.g., a scaled reference feedback signal) in a memory of the second device using one or more of the frequency domain representation and the time domain representation. For example, this may be possible in a system in which the link scan signal transmitted by the first device is known to the second device in advance (e.g., one or more of the frequency, duration, number of cycles, amplitude, phase, combinations thereof, etc. of the transmitted link scan signal may be known in advance).

[0248] In some variations, a method for decoding a data signal in a wireless system may include generating one or more of a frequency domain representation and a time domain representation of a scaled reference link scan signal (e.g., a scaled reference feedback signal) based on one or more properties of one or more of the received link scan signal and the received first data signal. In some variations, the one or more properties of the received link scan signal and the received first data signal may include one or more of frequency, duration, number of cycles, amplitude, phase, and time of arrival. For example, a processor of the second device may be configured to detect (on one or more transducer elements) a carrier frequency of one or more of the received link scan signal and the received first data signal and generate a pulse signal based on the detected carrier frequency and a predetermined number of cycles. This may be useful in a system in which the carrier frequency used by the first device for signal transmission may not be known a priori to the second device.

[0249] In some variations, the deconvolution may be performed in one or more of the time domain and the Laplace or frequency domain. For example, deconvolving a time-domain signal a(t) with another time-domain signal b(t) in the Laplace or frequency domain may include converting the time-domain signal to a frequency-domain signal (e.g., A(f) and B(f)) and calculating the division A(f) / B(f). For example, the impulse response (IR) of a wireless system may be determined by dividing the FFT of a received feedback signal by the FFT of a reference (or transmitted) feedback signal. In some variations, one or more deconvolution operations described herein may further include one or more of regularization and addition of a noise floor to avoid division by zero (or division by a very small number) or to remove artifacts in the output of the deconvolution.

[0250] In some variations, processing the received link scan signal and the received first data signal may include deconvolving the scaled received first data signal with one or more of the scaled impulse response and the scaled received link scan signal using one or more of a frequency domain analysis and a time domain analysis to generate the second data signal.

[0251] In some variations, processing the received link scan signal (e.g., in an impulse signal, a feedback signal, a pulse signal) and the received first data signal may include deconvolving the scaled received first data signal with the scaled received link scan signal using one or more of frequency domain analysis and time domain analysis to generate a second data signal or a scaled version thereof. For example, the received link scan signal may represent an impulse response or a pulse response of the wireless system. In some variations, the link scan signal may include one or more of an impulse signal, a feedback signal, a pulse signal, a pulse signal representing a single data bit of the first data signal (e.g., a pulse representing a “1” bit of OOK modulation), a pulse signal representing multiple data bits of the first data signal, multiple impulse signals, multiple pulse signals, combinations thereof, etc.

[0252] In some variations, the deconvolution may be performed to achieve one or more of removing multipath interference and aligning the signal in time. In some variations, the second data signal may include one or more of an output signal of the deconvolution (e.g., in the time domain, the frequency domain, or both), an impulse train, a pulse train, a combination thereof, etc.

[0253] FIG. 12 shows timing diagrams of signal variations that may be used in a method 1200 for decoding a data signal in a wireless system. A received link scan signal 1202 is shown, which may include one or more pulses due to multipath interference on the wireless link. A first data signal 1204 received using OOK modulation is also shown, which may be corrupted or have a low signal-to-interference ratio (SIR) or SNR due to multipath interference. Decoding such a received first data signal 1204 using conventional OOK demodulation techniques may be difficult. In some variations, the received first data signal 1204 may be deconvolved using the received link scan signal 1202, which may represent the impulse response of the wireless system. In some variations, the deconvolution may be performed in the time domain and / or the frequency domain. An output signal of the deconvolution, or a second data signal 1206, is also shown in FIG. 12. It should be noted that upon inspection of the received first data signal (1204) and second data signal (1206), deconvolution can help remove or reduce multipath interference or improve the SIR or SNR of the data signals. Performing OOK demodulation on the second data signal (1206) can result in accurate data recovery, as shown by the decoded data (1208) in Figure 12. In some variations, one or more of coherent OOK demodulation techniques (e.g., using mixing), non-coherent OOK demodulation techniques (e.g., using envelope detection), combinations thereof, etc. may be used for decoding.

[0254] FIG. 13 shows a timing diagram of another variation of signals that may be used in a method (1300) for decoding a data signal in a wireless system. A received link scan signal (1302) for a transducer element is shown and may include a received feedback signal pulse (e.g., including one or more cycles of a carrier frequency) and its multipath reflections (1304) due to multipath interference in the wireless link. A received first data signal (1306) for a transducer element based on OOK modulation is also shown and may be corrupted or have a low signal-to-interference ratio (SIR), or SNR, due to multipath interference. It may be difficult to decode such a received first data signal (1306) for a transducer element using conventional OOK demodulation techniques. In some variations, an impulse response (1310) for a transducer element may be determined by deconvolving the received link scan signal (1302) at the transducer element with a reference link scan signal (1308). For example, the reference link scan signal (1308) may include one or more cycles of a carrier frequency representing the link scan signal transmitted by the first device. In some variations, to remove or reduce multipath interference present in the first data signal (1306) received on the transducer element, the first data signal (1306) received on the transducer element may be deconvolved with the transducer element's impulse response (1310) to generate a second data signal (1314) of the transducer element, or an output signal of the deconvolution operation. In some variations, the deconvolution operation described herein may be performed in one or more of the time domain and the frequency domain. In some variations, OOK demodulation may further be performed on the second data signal (1314) in order for the transducer element to accurately decode the first data signal (e.g., using operations similar to those described for the combined data signal of FIG. 14).

[0255] In some variations, a method of decoding a data signal in a wireless system may include filtering one or more of a link scan signal, a first data signal, and a second data signal using one or more of a bandpass filter, a lowpass filter, a highpass filter, an allpass filter, a notch filter, a band-reject filter, combinations thereof, etc. In some variations, the filtering may enable one or more of reducing or eliminating thermal noise, reducing the strength of an interference source, eliminating an interference source, combinations thereof, etc.

[0256] In some variations, a method for combining selected second data signals may be required to improve the resulting SNR or SIR and thus reduce the probability of errors in decoding data bits. In some variations, a method for decoding a data signal in a wireless system may further include selecting two or more of the second data signals to combine into a single data signal based on one or more of a header check, a footer check, the relative strengths of the two or more second data signals, the relative signal-to-noise ratios of the two or more second data signals, the relative strengths of residual interference present in the two or more second data signals, cross-correlation values ​​of the two or more second data signals relative to a reference second data signal, combinations thereof, etc. For example, the selected two or more second data signals may include two or more second data signals with corrected header bits (e.g., upon decoding the header bits and comparing them with predetermined header bits). Screening the second data signals based on the header check may be a computationally efficient way to screen the second data signals before combining to achieve a higher SNR or SIR for accurate bit decoding. In some variations, the second data signals, or corresponding transducer elements of the second device, may be sorted or ranked according to one or more of the relative strength of the second data signals, the relative signal-to-noise ratio of the second data signals, the relative signal-to-interference ratio of the second data signals, the relative strength of residual interference present in the second data signals, a cross-correlation value of the second data signals with respect to a reference second data signal, combinations thereof, etc. For example, second data signals with higher ranks (e.g., higher SNR or SIR) may be used for further processing (e.g., signal combining).In some variations, the reference second data signal may be determined based on one or more of the amplitude, energy, signal-to-noise ratio or signal-to-interference ratio of the second data signal, the amplitude, energy, signal-to-noise ratio or signal-to-interference ratio of the corresponding first data signal, the amplitude, energy, signal-to-noise ratio or signal-to-interference ratio of the corresponding link scan signal, the apodization of corresponding transducer elements that may receive the link scan signal or the first data signal, combinations thereof, etc. For example, the reference second data signal may be the second data signal with the highest SNR or SIR.

[0257] In some variations, processing the received link scan signal and the received first data signal may further include applying a matched filter to one or more of the deconvolution output signal (or the second data signal). For example, a matched filter including sinusoidal pulses having a duration equal to the bit width may be applied to the deconvolution output signal (or the second data signal) to determine a time reference for decoding and / or to designate bits as “1” or “0.” In some variations, a matched filter corresponding to a header and / or footer of the data stream may be applied to the deconvolution output signal to detect the timing and / or presence of the header and / or footer in the data signal. In some variations, the first data signal may include multiple headers, footers, and / or predetermined bits or words at intermediate positions within the bit stream of the first data signal (e.g., to facilitate time synchronization or bit position determination while performing data bit decoding on the second device, which may be particularly useful for decoding long data streams including a large number of data bits).

[0258] In some variations, processing the received link scan signal and the received first data signal may further include combining two or more of the deconvolution output signals (or second data signals) using one or more of cross-correlation, delay and summation, combinations thereof, etc. Such two or more deconvolution output signals may be generated by processing the link scan signal and the first data signal received by two or more transducer elements of a transducer array of the second device. Combining signals from different transducer elements in this manner may improve the SIR or SNR of the combined signal compared to the SIR or SNR of the individual signals, thereby enabling more accurate data recovery or a lower bit error rate (because the number or probability of bit errors may be inversely proportional to the SIR or SNR). In some variations, time gaps resulting from delaying one signal relative to the other may be zero-padded. In some variations, a method of decoding a data signal in a wireless system may include combining two or more second data signals or scaled second data signals using one or more of summation, delay and summation, averaging, delay and averaging, combinations thereof, etc. to generate one or more combined data signals. In some variations, the combined signals may be sorted, ordered, or ranked (e.g., S1, S2, S3, etc.), and different delay and summation combinations may be calculated (e.g., S1+S2, S1+S2+S3, etc.). In some variations, such sorting, ordering, or ranking may be based on a cross-correlation value (or similarity) of the signals relative to a reference signal (e.g., the signal with the highest SNR or SIR).In some variations, the method of decoding data signals in a wireless system may further include selecting a combined data signal (e.g., a delay-and-sum combination of a second data signal) to decode the data bits based on one or more of the amplitude of the combined data signal in the time domain, the amplitude of the combined data signal at a frequency, the energy of the combined data signal in one or more frequency bands, the signal-to-noise ratio of the combined data signal, combinations thereof, etc. In some variations, the method may further include decoding the data bits based at least on the one or more combined data signals using one or more of OOK demodulation, ASK decoding, PPM demodulation, FSK demodulation, PSK demodulation, QAM demodulation, envelope detection, a matched filter, comparing the amplitude of the one or more combined data signals to a predetermined threshold, sampling the amplitude of the one or more combined data signals at a fixed time offset, combinations thereof, etc.

[0259] FIG. 14 is a timing diagram of exemplary variations of signals used in a method of decoding a data signal in a wireless system based on a combined data signal and matched filtering. Similar operations may be performed on one or more second data signals, such as one or more output signals of deconvolution of one or more first data signals with one or more impulse responses, to decode one or more first data signals, as illustrated by FIG. 14. A combined data signal (1402) is shown, which may be the result of delaying and summing two or more second data signals (e.g., the output of deconvolution of an impulse response and a received first data signal). In some variations, the combined data signal (1402) may be convolved (e.g., in the time domain or the frequency domain) by a header matched filter (1404) to generate a header convolution output (1406). In some variations, the header matched filter (1404) may include a reference OOK data signal (e.g., including one or more pulses) corresponding to a predetermined header bit (e.g., 11001) known to be present at the beginning of the first data signal. In some variations, the envelope of the header convolution output (1408) may be determined (e.g., by squaring the header convolution output and applying a low-pass filter or using other envelope detection techniques). The envelope of the header convolution output (1408) may be compared to a header convolution threshold (1410) to determine a header position (1412) including the timing of a first peak in the envelope of the header convolution output (1408) that exceeds the header convolution threshold (1410). In some variations, the combined data signal (1402) may be convolved (e.g., in the time domain or the frequency domain) by a bit-matched filter (1414) to generate a bit-convolved output (1416). In some variations, the bit-matched filter (1414) may include a reference OOK data signal corresponding to a predetermined single “1” bit (e.g., including a single pulse).In some variations, the envelope (1418) of the bit convolution output may be determined (e.g., by squaring the header convolution output and applying a low-pass filter, or using other envelope detection techniques). In some variations, the bit positions (1422) may be determined based on one or more of the header position (1412), the number of header bits, a predetermined bit duration (i.e., the duration, number of cycles of a carrier frequency, or number of clock cycles corresponding to a "1" and / or "0" bit), a combination thereof, etc., as indicated by the arrows in FIG. 14. For example, the position of the first bit may be determined based on the header position (1412), the number of header bits (e.g., 5), and the duration of a single bit, and the positions of the other bits may be determined based on fixed timing offsets corresponding to the duration of a single bit starting from the position of the first bit. In some variations, the value of the envelope (1418) of the bit-convolution output at bit position (1422) may be compared to a bit-convolution threshold (1420) to decode each bit as a "1" (e.g., if the envelope value is greater than the bit-convolution threshold) or a "0" (e.g., if the envelope value is less than the bit-convolution threshold). In some variations, one or more of the header matched filter (1404), bit matched filter (1414), header convolution threshold (1410), and bit convolution threshold (1420) may be predetermined or preloaded (e.g., stored) in a memory of the second device. In some variations, one or more of the header matched filter (1404) and bit matched filter (1414) may be preloaded (e.g., stored) in the time-domain and / or frequency-domain representation. In some variations, one or more of the header matched filter (1404), the bit matched filter (1414), the header convolution threshold (1410), and the bit convolution threshold (1420) may be calculated by a processor of the second device during execution of the method for decoding a data signal (e.g., upon detecting the carrier frequency of one or more of the link scan signal and the first data signal).

[0260] In some variations, a method of decoding a data signal in a wireless system may include decoding data bits corresponding to one or more second data signals (e.g., an output signal of deconvolving a first data signal with an impulse response of the wireless system) using one or more of OOK demodulation, ASK demodulation, PPM demodulation, FSK demodulation, PSK demodulation, QAM demodulation, envelope detection, matched filtering, comparing the amplitude of the one or more second data signals with a predetermined threshold, and sampling the amplitude of the one or more second data signals at a fixed time offset, combinations thereof, etc. In some variations, the method may further include selecting one or more second data signals before decoding the data bits based on a header check, a footer check, a relative strength of the one or more second data signals, a relative signal-to-noise ratio of the one or more second data signals, a relative strength of residual interference present in the one or more second data signals, a cross-correlation value of the one or more second data signals with a reference second data signal, combinations thereof, etc. In some variations, the method may further include determining, among the decoded data bit values ​​corresponding to the two or more second data signals, one or more of a majority occurrence rate (or majority vote) of the bit values, a weighted majority occurrence rate of the bit values, an average bit value, a weighted average bit value, combinations thereof, etc. In some variations, decoding the bits based on the majority occurrence rate may be less computationally intensive compared to combining the second data signals to generate multiple combined signals, selecting the combined signal with the highest SNR, and decoding the bits based on the combined signal with the highest SNR.In some variations, determining the weighted majority occurrence or weighted average bit value may include apodization of the transducer element receiving the corresponding link scan signal or the corresponding first data signal, scaling the bit value by one or more of the amplitude, energy, signal-to-noise ratio, delay time, phase, and multipath time of one or more of the second data signal, the corresponding first data signal, the corresponding link scan signal, combinations thereof, etc. For example, an average of the decoded "1" and "0" bit values ​​across the transducer elements or channels may be calculated for the final assignment of the decoded bit value of "1" or "0" and may be compared to a predetermined threshold (e.g., 0.5).

[0261] In some variations, a method for decoding a data signal in a wireless system may include reporting an error or an indication that it may not be possible to reliably decode a bit. Such an error or indication may be generated based on one or more of a header check, a footer check, a bit error rate, a strength of the link scan signal, a signal-to-noise ratio of the link scan signal, a signal-to-interference ratio of the link scan signal, an energy of the link scan signal in one or more frequency bands, a moving average of the link scan signal amplitude, a strength of a first data signal, a signal-to-noise ratio of the first data signal, a signal-to-interference ratio of the first data signal, an energy of the first data signal in one or more frequency bands, a moving average of the first data signal amplitude, a strength of a second data signal, a signal-to-noise ratio of the second data signal, a signal-to-interference ratio of the second data signal, an energy of the second data signal in one or more frequency bands, a moving average of the second data signal amplitude, a signal strength of an interferer, a signal strength of multipath interference, a multipath time, an apodization of one or more transducer elements, combinations thereof, etc.

[0262] In some variations, one or more link scan signals may be transmitted by the first device before transmitting the one or more first data signals. For example, in some variations, multiple first data signals may be transmitted by the first device after transmitting a link scan signal. In some variations, one or more first data signals may be transmitted by the first device before transmitting the one or more link scan signals. In some variations, one or more link scan signals may be transmitted by the first device both before and after transmitting the one or more first data signals.

[0263] In some variations, a method for decoding a data signal in a wireless system may include transmitting a first link scan signal, then a first data signal, then a second link scan signal from a first device in the wireless system to a second device in the wireless system, and receiving the first link scan signal, the first data signal, and the second link scan signal using one or more transducer elements of the second device. In some variations, the method may further include decoding a first portion of the first data signal (e.g., a first half of the first data signal) using the first link scan signal and decoding a second portion of the first data signal (e.g., a second half of the first data signal) using the second link scan signal based on any of the methods for decoding data signals as described herein. This may be advantageous for transmitting a first data signal that includes a long stream of data bits, and due to changes in multipath interference over time, the first link scan signal may not be sufficient to reliably and accurately decode the complete data stream. In some variations, this may also be advantageous for decoding a first data signal that includes variations or drifts in its carrier frequency (or frequency content) over time (e.g., caused by frequency drift and / or long settling times of oscillator circuitry of a first device that may transmit one or more link scan signals and data signals). For example, the frequency content or carrier frequency of the first link scan signal may be close to the frequency content or carrier frequency of the first portion of the first data signal so as to allow accurate decoding of the first portion of the first data signal using one or more methods of decoding wireless data signals as described herein.

[0264] In some variations, the first device may include an implantable medical device, the second device may include an external wireless device configured to be located physically separate from the first device, and the first data signal may include an uplink data signal. In some variations, the first device may include an external wireless device, the second device may include an implantable medical device configured to be located physically separate from the first device, and the first data signal may include a downlink data signal.

[0265] In some variations, the method for decoding a data signal in a wireless system may further include transmitting one or more of the link scan signal and the first data signal from a first device of the wireless system to a second device of the wireless system at one or more predetermined repetition intervals. In some variations, this enables reliable data transfer between a first device (e.g., a wireless implantable cardiovascular device) and a second device (e.g., an external wireless device) in the presence of relative motion (due to heartbeat and respiration) between the first and second devices. In some variations, the one or more predetermined repetition intervals may be determined based on a rate of relative motion between the first and second devices. In some variations, the predetermined repetition interval may correspond to a duration during which the wireless link may be quasi-static (e.g., a duration during which link efficiency may vary by less than about 3 dB) or a duration during which the first device may be stationary relative to the first device. In some variations, the first device may transmit one link scan signal (e.g., one feedback signal pulse) corresponding to the multiple first data signals (e.g., transmit a link scan signal including a feedback signal pulse before transmitting the multiple first data signals, etc.). In some variations, the first device may transmit multiple link scan signals corresponding to a single first data signal (e.g., transmit a link scan signal including a feedback signal pulse before and after transmitting the first data signal, etc.). In some variations, the method may further include transmitting a wireless command from the second device to the first device, and transmitting a link scan signal and the first data signal from the first device to the second device in response to receiving the wireless command by the first device. In some variations, the wireless command may include one or more of a wireless signal, a pulse signal, multiple pulse signals, a signal in which data bits are encoded (e.g., using OOK modulation), combinations thereof, etc.In some variations, one or more of the one or more transmitted link scan signals and the one or more transmitted first data signals may include reflected or backscattered signals in response to receiving a radio signal transmitted by the second device to the first device.

[0266] In some variations, one or more of the transmitted link scan signal and the first data signal may include one or more of an ultrasonic signal, an acoustic signal, a vibration signal, a radio frequency signal, an electromagnetic signal, a magnetic signal, an electrical signal, an optical signal, combinations thereof, and the like.

[0267] 15 is a flowchart generally illustrating a variation of a method 1500 for decoding a data signal in a wireless system. The method may include the steps of transmitting 1502 a link scan signal and a first data signal from a first device in the wireless system to a second device in the wireless system, receiving 1504 the link scan signal and the first data signal using one or more transducer elements of the second device, processing 1506 one or more of the received link scan signal and the received first data signal to select one or more transducer elements of the second device, and decoding 1508 the first data signal based at least in part on the selected one or more transducer elements of the second device. In some variations, the link scan signal may include one or more of a feedback signal, an impulse signal, a pulse signal, a pulse signal representing a single data bit of the first data signal, a pulse signal representing multiple data bits of the first data signal, a header signal, a footer signal, a predetermined digital code, a continuous wave signal, multiple impulse signals, multiple pulse signals, combinations thereof, etc. In some variations, selecting one or more transducer elements of the second device may be based on one or more of a header check, a footer check, a bit error rate, a relative strength of the link scan signal, a relative signal-to-noise ratio of the link scan signal, a relative signal-to-interference ratio of the link scan signal, the energy of the link scan signal in one or more frequency bands, a moving average of the link scan signal amplitude, a relative strength of the first data signal, a relative signal-to-noise ratio of the first data signal, a relative signal-to-interference ratio of the first data signal, the energy of the first data signal in one or more frequency bands, a moving average of the first data signal amplitude, a signal strength of an interferer, a signal strength of multipath interference, a multipath time, an apodization of one or more transducer elements, combinations thereof, and the like.In some variations, upon selecting one or more transducer elements of the second device, the received link scan signal and the received first data signal received on the selected transducer elements may be processed using one or more operations described herein (e.g., signal combining, matched filtering, data decoding using OOK demodulation, bandpass filtering, combinations thereof, etc.).

[0268] In some variations, the bit duration of the data signal may be selected to allow multipath interference to settle (e.g., the bit duration is longer than the multipath time in the wireless link). In some variations, a high frequency may be used for the data signal (e.g., higher than the frequency of the power signal) to reduce the effects of multipath interference (e.g., because the higher the frequency, the higher the signal attenuation in tissue). In some variations, the first data signal may include pulse position modulation (PPM), and the link scan signal may be used for time synchronization (e.g., to detect the timing of the PPM pulses).

[0269] In some variations, the received first data signals may be combined using one or more of summation, delay and summation, averaging, delay and average, combinations thereof, etc. to generate one or more combined signals. This may be done to improve the SNR or SIR of the combined signal relative to the one or more first data signals. In some variations, the delay for the delay and summation or delay and average may be calculated based on the arrival time of one or more of the received link scan signal and the received first data signal on one or more transducer elements of the second device. In some variations, envelope detection may be performed on one or more of the received link scan signal and the received first data signal, and the envelope may be compared to a predetermined threshold to detect the onset, arrival time, or rising edge of the signal, which may be used to delay the signal before combining and summing the signals.

[0270] 16 shows a flowchart of yet another variation of a method 1600 for decoding a data signal in a wireless system. The method 1600 may include the steps of transmitting a link scan signal from a first device of the wireless system to a second device of the wireless system 1602, receiving the link scan signal using one or more transducer elements of the second device 1604, processing the received link scan signal using a processor of the second device to generate link scan signal data 1606, generating a predistortion data signal based on the link scan signal data using a processor of the second device 1608, transmitting the predistortion data signal from the second device to the first device 1610, receiving the predistortion data signal using one or more transducer elements of the first device 1612, and processing the received predistortion data signal using the processor of the first device to generate decoded data 1614. As described herein, the link scan signals, data signals, link scan signal data, transducer elements, and processors are applicable to any of the methods described herein.

[0271] In some variations, the link scan signal may include an impulse signal, and generating the predistortion data signal may include performing deconvolution of the received link scan signal and a data signal (e.g., an ideal OOK data waveform without any multipath interference). In some variations, the link scan signal data may include an impulse response of a wireless system, and generating the predistortion data signal may include performing deconvolution of the impulse response of the wireless system and the data signal (e.g., an ideal OOK data waveform without any multipath interference). As the predistortion data signal travels from the second device to the first device, it may be convolved with the impulse response of the wireless system. Thus, the received predistortion data signal received by the first device may resemble the original data signal (i.e., an ideal OOK data waveform without any multipath interference), which may mitigate any signal corruption due to multipath interference. In some variations, time reversal may be applied to one or more received link scan signals, and the resulting one or more time-reversed signals may be used to transmit one or more data signals to the first device rather than generating and transmitting a predistorted data signal.

[0272] In some variations, the first device may include an implantable medical device, the second device may include an external wireless device configured to be located physically separate from the first device, and the predistortion data signal may include a downlink data signal. In some variations, the first device may include an external wireless device, the second device may include an implantable medical device configured to be located physically separate from the first device, and the predistortion data signal may include an uplink data signal.

[0273] 17 shows a flowchart of yet another variation of a method 1700 for decoding a data signal in a wireless system. The method 1700 may include the steps of transmitting 1702 a data signal from a first device of the wireless system to a second device of the wireless system, receiving 1704 the data signal using a plurality of transducer elements of the second device, applying 1706 a predetermined delay to one or more received data signals received using the plurality of transducer elements of the second device to generate delayed data signals, summing 1708 two or more delayed data signals using the processor of the second device to generate one or more delayed and summed data signals, and decoding 1710 the data signal using the processor of the second device based at least in part on the one or more delayed and summed data signals. As described herein, the data signal, transducer elements, and processor are applicable to any of the methods described herein.

[0274] In some variations, the method (1700) may further include transmitting a feedback signal from the first device to the second device before transmitting the data signal, receiving the feedback signal using one or more transducer elements of the second device, processing the received feedback signal using a processor of the second device to generate feedback signal data, and calculating a predetermined delay based at least in part on the feedback signal data. In some variations, the method (1700) may further include transmitting a link scan signal from the first device to the second device before transmitting the data signal, receiving the link scan signal using one or more transducer elements of the second device, processing the received link scan signal using a processor of the second device to generate link scan signal data, and calculating a predetermined delay based at least in part on the link scan signal data. As described herein, the feedback signal, link scan signal, data signal, transducer element, processor, feedback signal data, and link scan signal data are applicable to any of the methods described herein.

[0275] In some variations, the first device may include an implantable medical device, the second device may include an external wireless device configured to be located physically separate from the first device, and the data signal may include an uplink data signal. In some variations, the first device may include an external wireless device, the second device may include an implantable medical device configured to be located physically separate from the first device, and the data signal may include a downlink data signal.

[0276] In some variations, the processor of the second device may be configured to select one or more transducer elements of the second device for further processing of one or more of the link scan signal and the first data signal based on one or more properties of one or more of the link scan signal and the first data signal.

[0277] In some variations, upon decoding the data signal, one or more processors of the second device and the first device of the wireless system may be configured to perform one or more of error detection, error correction, a combination thereof, etc. (e.g., using an error correction code or ECC, a cyclic redundancy check or CRC, etc.). In some variations, upon detecting the data signal, one or more processors of the second device and the first device may be configured to generate one or more of an acknowledgement signal (ACK) and a negative acknowledgement signal (NACK). For example, the processor of the second device may be configured to generate an ACK signal upon detecting a zero-bit error in the decoded first data signal (e.g., after performing a cyclic redundancy check) and transmit the ACK signal to the first device using a transducer array configuration of the second device described herein. Variations of the data signal may be applicable to one or more of the ACK signal and the NACK signal, as described herein.

[0278] C. Radio System Calibration In some variations, a wireless implantable device may include a transducer having a resonant frequency and a wireless transmitter including an oscillator circuit having an oscillator frequency. In some variations, the oscillator frequency may vary significantly between different wireless implantable devices due to device-to-device variations (e.g., due to chip-to-chip variations caused by integrated circuit manufacturing process variations). In some devices, the resonant frequency of the transducer of the wireless implantable device may not match the oscillator frequency due to excessive variation, which may result in low output power of any uplink signals transmitted by the wireless implantable device. In these cases, calibration and / or adjustment of the oscillator frequency may be desirable. However, conventional methods of calibrating the oscillator frequency by bench testing the wireless implantable device and / or its components may be time-consuming and / or expensive and may not take into account the performance of the entire wireless system. A solution to alleviate this problem is provided herein.

[0279] 18 is a flowchart generally illustrating a variation of a method 1800 for calibrating a wireless system. The method 1800 may include the steps of transmitting one or more test signals including one or more carrier frequencies from a first device in the wireless system to a second device in the wireless system (1802), receiving the one or more test signals using the second device (1804), processing the one or more received test signals using a processor of the second device to generate test signal data (1806), determining one or more selected carrier frequencies using a processor of the second device based at least in part on the test signal data (1808), transmitting one or more wireless commands from the second device to the first device (1810) including information corresponding to the one or more selected carrier frequencies, and storing the information corresponding to the one or more selected carrier frequencies in a memory of the first device (1812). The test signal may be any signal transmitted from one device in the wireless system to another device in the wireless system to test one or more characteristics of a wireless link between the two devices. For example, the test signal may include a sinusoidal and / or rectangular signal having one or more cycles of the carrier frequency of the test signal or one or more cycles of an oscillator frequency of the first device (e.g., a wireless implantable device). In some variations, the test signal data may include any property of the test signal (e.g., amplitude, signal strength, frequency, phase, etc.) and / or any characteristic of the wireless link (e.g., link efficiency).

[0280] In some variations, the method (1800) may further include transmitting a wireless signal having one or more selected carrier frequencies from the first device to the second device. In some variations, the transmitted wireless signal may include one or more of a feedback signal, a link scan signal, an uplink data signal, a combination thereof, etc.

[0281] In some variations, determining the one or more selected carrier frequencies may include determining one or more carrier frequencies at which a parameter of the received test signal may have a value greater than a predetermined threshold. In some variations, the parameter of the received test signal may include one or more of signal strength, signal amplitude, signal power, signal energy, signal-to-noise ratio, signal-to-interference ratio, link efficiency, link gain, combinations thereof, etc. In some variations, the memory of the first device may include one or more of non-volatile memory, volatile memory, combinations thereof, etc. In some variations, the non-volatile memory may be configured to persistently store information corresponding to the one or more selected carrier frequencies and / or store information corresponding to the one or more selected carrier frequencies until the next calibration operation.

[0282] 19 shows a schematic block diagram of a wireless system (1900) configured for calibration. The system (1900) may include a wireless device (1914) including a transducer (1920) and a processor (1930). The system may further include a wireless implantable device (1910) including the transducer (1920), a wireless transmitter (1960), a wireless receiver (1970), a processor (1930), and a memory (1980). In some variations, the processor (1930) of the wireless implantable device (1910) may be configured to control the wireless transmitter (1960) to transmit one or more test signals (1950) having one or more carrier frequencies via the transducer (1920) of the wireless implantable device (1910). The transducer (1920) of the wireless device (1914) may be configured to receive the one or more test signals (1950). The processor (1930) of the wireless device (1914) may be configured to process the one or more received test signals (1950) to generate test signal data. In some variations, the processor (1930) of the wireless device (1914) may be further configured to determine one or more selected carrier frequencies based at least in part on the test signal data. The processor (1930) of the wireless device (1914) may be further configured to control the transducer (1920) of the wireless device (1914) to transmit one or more wireless commands to the wireless implantable device (1910) via one or more downlink signals (1940), where the one or more wireless commands may include information corresponding to the one or more selected carrier frequencies. The wireless receiver (1970) of the wireless implantable device (1910) may be configured to receive the one or more wireless commands via the transducer (1920). In some variations, the processor (1930) may be configured to store information corresponding to one or more selected carrier frequencies in the memory (1980) of the wireless implantable device (1910).Optionally, in some variations, the processor (1930) may be configured to control the wireless transmitter (1960) to transmit one or more wireless signals at one or more selected carrier frequencies.

[0283] D. Exchange of radio signals based on one or more predetermined transmission voltage levels In some variations, the first device and the second device of the wireless system may be configured to exchange wireless signals based on one or more predetermined transmit voltage levels of the second device. Any of the methods of exchanging wireless signals may be used with any of the methods described herein (e.g., exchanging wireless signals based on feedback signals and / or link scan signals, exchanging wireless signals based on defocus, closed-loop powering, decoding wireless data signals, calibrating a wireless system).

[0284] The closed loop powering method described herein includes a step of controlling the power of the feedback signal (P TX,fb ), the power of the feedback signal received by the second device (P RX,fb ), the target received power level at the first device (P RX,電力 ), and the transmit power level (P TX,電力) is calculated. Furthermore, in some variations, the transmit power level may correspond to a transmit voltage level. For example, the transmit voltage level may be determined based on a required transmit power level and the impedance of one or more transducer elements used to transmit the wireless power or wireless signal. In some variations, the required transmit power level or transmit voltage level may change over time due to changes in link efficiency between the first device and the second device (e.g., due to movement of the first device, such as an intracardiac implantable device, relative to the second device, such as an external wireless device). However, in some cases, configuring the second device to have a variable or adjustable transmit voltage level may not be practical as it may add one or more of hardware complexity, device size, and cost. Furthermore, in some variations, bursts of variable transmit power levels may be required, and it may not be possible to quickly adjust the transmit voltage level within the duration of the burst (e.g., adjusting the transmit voltage level may require charging or discharging a large capacitor, which may require a long time). Instead, in some variations, it may be advantageous to configure the second device to have one or more predetermined or fixed transmit voltage levels. As such, additional devices, systems, and methods may be desirable for reliably exchanging wireless signals between two or more devices in a wireless system based on one or more predetermined transmit voltage level constraints.

[0285] 20 shows a schematic block diagram of an example variation of a wireless system (2000) configured to exchange wireless signals. In some variations, the system (2000) may comprise a first device (2010), such as a wireless implantable device including at least a transducer (2020). In some variations, the system (2000) may further comprise a second device (2014), such as a wireless device including the transducer (2020), a processor (2030), a transmitter circuit (2070), and a power source (2080). In some variations, the power source (2080) may comprise one or more of a power supply or source, a voltage supply or source, a current supply or source, and an energy supply or source. In some variations, the first device (2010) may be configured to transmit a feedback signal (2050), and the transducer (2020) of the second device (2014) may include a transducer array configured to receive the feedback signal on one or more transducer elements of the transducer array. In some variations, the power source (2080) may include one or more predetermined transmit voltage levels. In some variations, the processor (2030) of the second device (2014) may be configured to process the feedback signal (2050) received by one or more transducer elements of the transducer array to generate feedback signal data and determine a transducer array configuration based on the feedback signal data and the one or more predetermined transmit voltage levels of the power source (2080). Further, the second device (2014) may be configured to exchange one or more wireless signals (2040) with the first device (2010) using the transducer array configuration.

[0286] 21 is a flowchart generally illustrating a variation of a method 2100 for exchanging wireless signals with a device based on one or more predetermined transmit voltage levels. The method 2100 may include the steps of: transmitting a feedback signal from a first device of a wireless system to a second device of the wireless system 2102; receiving the feedback signal using one or more transducer elements of a transducer array of the second device 2104; processing the received feedback signal using the one or more transducer elements of the transducer array to generate feedback signal data using a processor of the second device 2106; determining a transducer array configuration of the second device 2108 based at least in part on the feedback signal data and one or more predetermined transmit voltage levels of a power source of the second device; and exchanging one or more wireless signals with the first device 2110 using the transducer array configuration of the second device.

[0287] In some variations, the feedback signal data may include one or more of the absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute arrival time, relative arrival time, frequency, duration, number of cycles, absolute signal-to-noise ratio, relative signal-to-noise ratio, combinations thereof, etc. of the feedback signal received by one or more transducer elements of the transducer array.

[0288] In some variations, the transducer array configuration may include one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse width modulation, duty cycle, phase, delay time, frequency, transmission duration, combinations thereof, and the like applied to one or more transducer elements of the transducer array to transmit a wireless signal to the first device.

[0289] In some variations, the method (2100) may further include using a processor of the second device to determine transmit apodization of transducer elements of the transducer array. In some variations, the transmit apodization of the transducer elements may refer to the relative signal strength of the wireless signals transmitted by the transducer elements relative to one another. In some variations, the signal strength may refer to the signal amplitude, voltage level, current level, pulse width (e.g., pulse width of a multi-level square wave signal), duty cycle (e.g., duty cycle of a multi-level square wave signal), power, energy, efficiency, link efficiency (e.g., uplink link efficiency, downlink link efficiency), combinations thereof, etc. In some variations, the transmitter circuit of the second device may include a three-level pulser circuit that may be configured to apply a three-level square wave to the transducer elements to transmit the wireless signals. For example, in some variations, the three-level square wave may be applied to the transducer elements from +V HV , 0 and -V HV may include a voltage level of V HV ("HV" stands for high voltage) may refer to a predetermined transmit voltage level of the power supply of the second device. In some variations, the pulse width or duty cycle of the three-level square wave signal (e.g., the time it takes for the voltage to exceed +V for the total period of the square wave signal) HV or -V HV The duration may be set to .times. ...

[0290] In some variations, the transmit apodization of a transducer element may be proportional to the receive apodization or relative signal strength of a feedback signal received by the transducer element of the transducer array within one or more frequency bands. For example, the relative signal strength or receive apodization of a feedback signal may refer to one or more of the following: relative time-domain amplitude, power, or energy levels (e.g., based on envelope detection), relative frequency-domain amplitude, power, or energy levels (e.g., based on FFT or Goertzel operations), relative link efficiency (e.g., ratio of received power level to transmitted power level), combinations thereof, etc. for the feedback signal received on different transducer elements of the transducer array of the second device. In some variations, setting the transmit apodization to be proportional to, equal to, or substantially equal to the receive apodization (e.g., in addition to setting the transmit phase or delay described herein) may optimize or increase wireless link efficiency for transmitting a wireless signal (e.g., wireless power or data) from the second device to the first device. In some variations, the transmit apodization of two or more transducer elements may be equal or substantially equal. For example, in some variations, it may be beneficial to transmit to multiple transducer elements of a transducer array of a second device with maximized transmit apodization in order to minimize the number of transducer elements required to achieve a target receive power level at a first device. In some variations, minimizing the required number of transducer elements may minimize power dissipation in associated transmitter circuitry, thereby minimizing heating of the second device (e.g., an external wireless device placed on the patient's skin).

[0291] In some variat...

Claims

1. a first device configured to transmit a feedback signal; a second device including a transducer array, a processor, and a power source; 1. A system configured to exchange wireless power or data, comprising: the transducer array is configured to receive the feedback signal on one or more transducer elements of the transducer array; the power source includes one or more predetermined transmit voltage levels; the processor is configured to process the feedback signal received by one or more transducer elements of the transducer array to generate feedback signal data; and determine a transducer array configuration based at least in part on the feedback signal data and the one or more predetermined transmit voltage levels of the power source; The system, wherein the second device is configured to exchange one or more wireless signals with the first device using the transducer array configuration.

2. 2. The system of claim 1, wherein the feedback signal data includes one or more of absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute time of arrival, relative time of arrival, frequency, duration, number of cycles, absolute signal-to-noise ratio, and relative signal-to-noise ratio of the feedback signal received by one or more transducer elements of the transducer array.

3. 10. The system of claim 1, wherein the transducer array configuration includes one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to one or more transducer elements of the transducer array for transmitting wireless signals to the first device.

4. The system of claim 1 , wherein the processor is further configured to determine a transmit apodization of the transducer elements of the transducer array.

5. 5. The system of claim 4, wherein the processor is further configured to select a set of transducer elements of the transducer array configuration based on one or more of the transmit apodization of the transducer elements, the one or more predetermined transmit voltage levels of the power source, and one or more predetermined target signal strengths at the first device.

6. 5. The system of claim 4, wherein the transmit apodization of the transducer elements is proportional to the relative signal strength of the feedback signals received by the transducer elements of the transducer array within one or more frequency bands.

7. The system of claim 4 , wherein the transmit apodization of two or more transducer elements is substantially equal.

8. 10. The system of claim 1, wherein the second device further includes one or more transmitter circuits configured to apply transmit signals to one or more transducer elements of the transducer array, and the processor is configured to determine transmitter circuit data corresponding to the one or more transmitter circuits based at least in part on the feedback signal data.

9. 9. The system of claim 8, wherein the transmitter circuit data includes one or more of efficiency, power dissipation, energy dissipation, current dissipation, voltage drop, heat dissipation, temperature, temperature rise, input power, input energy, input current, input voltage, output power, output energy, output current, and output voltage of the one or more transmitter circuits.

10. The system of claim 8 , wherein the processor is further configured to determine the transmit apodization of the transducer elements based at least in part on the transmitter circuit data.

11. 2. The system of claim 1, wherein the power source includes a plurality of predetermined transmit voltage levels, the processor is further configured to select one or more predetermined transmit voltage levels based at least in part on the feedback signal data and the plurality of predetermined transmit voltage levels, and the transducer array configuration further includes the selected one or more predetermined transmit voltage levels for exchanging one or more wireless signals with the first device.

12. 2. The system of claim 1, wherein the power source includes a first predetermined transmit voltage level and a second predetermined transmit voltage level, and the transducer array configuration includes the first predetermined transmit voltage level for transmitting wireless power and the second predetermined transmit voltage level for transmitting one or more of wireless data and commands to the first device.

13. 13. The system of claim 12, wherein the first predetermined transmit voltage level is greater than or substantially equal to the second predetermined transmit voltage level.

14. 10. The system of claim 1, wherein the first device comprises an implantable medical device and the second device comprises an external wireless device configured to be located physically separate from the first device.

15. 10. The system of claim 1, wherein the first device comprises an external wireless device and the second device comprises an implantable medical device configured to be located physically separate from the first device.

16. 2. The system of claim 1, wherein the second device is further configured to transmit a wireless command to the first device, and the first device is configured to transmit the feedback signal in response to receiving the wireless command.

17. The system of claim 1 , wherein the first device is configured to transmit the feedback signal at one or more predetermined recurrence intervals.

18. 1. A method for exchanging wireless signals in a wireless system, comprising: transmitting a feedback signal from a first device of the wireless system to a second device of the wireless system; receiving the feedback signal using one or more transducer elements of a transducer array of the second device; processing the feedback signal received using one or more transducer elements of the transducer array to generate feedback signal data using a processor of the second device; using the processor of the second device to determine a transducer array configuration of the second device based at least in part on the feedback signal data and one or more predetermined transmit voltage levels of a power supply of the second device; exchanging one or more wireless signals with the first device using the transducer array configuration of the second device; The method comprising:

19. 20. The method of claim 18, wherein the feedback signal data includes one or more of absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute time of arrival, relative time of arrival, frequency, duration, number of cycles, absolute signal-to-noise ratio, and relative signal-to-noise ratio of the feedback signal received by one or more transducer elements of the transducer array.

20. 20. The method of claim 18, wherein the transducer array configuration includes one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to one or more transducer elements of the transducer array for transmitting wireless signals to the first device.

21. 20. The method of claim 18, further comprising determining, using the processor of the second device, transmit apodization of the transducer elements of the transducer array.

22. 22. The method of claim 21, further comprising using the processor of the second device to select a set of transducer elements of the transducer array configuration based on one or more of the transmit apodization of the transducer elements, the one or more predetermined transmit voltage levels of the power source, and one or more predetermined target signal strengths at the first device.

23. 22. The method of claim 21, wherein the transmit apodization of the transducer elements is proportional to the relative signal strength of the feedback signals received by the transducer elements of the transducer array within one or more frequency bands.

24. 22. The method of claim 21, wherein the transmit apodization of two or more transducer elements is substantially equal.

25. 20. The method of claim 18, further comprising: using the processor of the second device, determining, based at least in part on the feedback signal data, transmitter circuit data corresponding to one or more transmitter circuits of the second device configured to apply transmit signals to one or more transducer elements of the transducer array.

26. 26. The method of claim 25, wherein the transmitter circuit data includes one or more of efficiency, power dissipation, energy dissipation, current dissipation, voltage drop, heat dissipation, temperature, temperature rise, input power, input energy, input current, input voltage, output power, output energy, output current, and output voltage of the one or more transmitter circuits.

27. 26. The method of claim 25, further comprising determining transmit apodization of the transducer elements based at least in part on the transmitter circuit data.

28. 20. The method of claim 18, further comprising: using the processor of the second device to select one or more predetermined transmit voltage levels for the power source from a plurality of predetermined transmit voltage levels for the power source based at least in part on the feedback signal data; and exchanging one or more wireless signals with the first device using the transducer array configuration including the selected one or more predetermined transmit voltage levels.

29. 20. The method of claim 18, further comprising transmitting wireless power to the first device using a first predetermined transmit voltage level of the power source, and transmitting one or more of wireless data and commands to the first device using a second predetermined transmit voltage level of the power source.

30. 30. The method of claim 29, wherein the first predetermined transmit voltage level is greater than or substantially equal to the second predetermined transmit voltage level.

31. 20. The method of claim 18, wherein the first device comprises an implantable medical device and the second device comprises an external wireless device configured to be located physically separate from the first device.

32. 20. The method of claim 18, wherein the first device comprises an external wireless device and the second device comprises an implantable medical device configured to be located physically separate from the first device.

33. 20. The method of claim 18, further comprising: transmitting one or more wireless commands from the second device to the first device; and transmitting one or more feedback signals from the first device to the second device in response to receiving the one or more wireless commands.

34. 20. The method of claim 18, further comprising transmitting the feedback signal from the first device at one or more predetermined repetition intervals.

35. a first device configured to transmit a feedback signal; a second device including a transducer array, a processor, and one or more transmitter circuits; 1. A system configured to exchange wireless power or data, comprising: the transducer array is configured to receive the feedback signal on one or more transducer elements of the transducer array; the one or more transmitter circuits configured to apply a transmit signal to one or more transducer elements of the transducer array; the processor is configured to process the feedback signals received by one or more transducer elements of the transducer array to generate feedback signal data; determine transmitter circuit data corresponding to the one or more transmitter circuits based at least in part on the feedback signal data; and determine a transducer array configuration based at least in part on the feedback signal data and the transmitter circuit data; The system, wherein the second device is configured to exchange one or more wireless signals with the first device using the transducer array configuration.

36. 36. The system of claim 35, wherein the feedback signal data includes one or more of absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute time of arrival, relative time of arrival, frequency, duration, number of cycles, absolute signal-to-noise ratio, and relative signal-to-noise ratio of the feedback signal received by one or more transducer elements of the transducer array.

37. 36. The system of claim 35, wherein the transmitter circuit data includes one or more of efficiency, power dissipation, energy dissipation, current dissipation, voltage drop, heat dissipation, temperature, temperature rise, input power, input energy, input current, input voltage, output power, output energy, output current, and output voltage of the one or more transmitter circuits.

38. 36. The system of claim 35, wherein the transducer array configuration includes one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to one or more transducer elements of the transducer array for transmitting wireless signals to the first device.

39. 36. The system of claim 35, wherein the processor is further configured to determine a transmit apodization of the transducer elements of the transducer array.

40. 40. The system of claim 39, wherein the processor is further configured to select a set of transducer elements of the transducer array configuration based on one or more of the transmit apodization of the transducer elements, the transmitter circuit data, and one or more predetermined target signal strengths at the first device.

41. 41. The system of claim 40, wherein the transducer array configuration includes one or more transmit voltage levels, and the processor is configured to determine the one or more transmit voltage levels based at least in part on a selected set of the transducer elements of the transducer array configuration.

42. 40. The system of claim 39, wherein the transmit apodization of the transducer elements is proportional to the relative signal strength of the feedback signals received by the transducer elements of the transducer array within one or more frequency bands.

43. 40. The system of claim 39, wherein the transmit apodization of two or more transducer elements is substantially equal.

44. 36. The system of claim 35, wherein the first device comprises an implantable medical device and the second device comprises an external wireless device configured to be located physically separate from the first device.

45. 36. The system of claim 35, wherein the first device comprises an external wireless device and the second device comprises an implantable medical device configured to be located physically separate from the first device.

46. 36. The system of claim 35, wherein the second device is further configured to transmit one or more wireless commands to the first device, and the first device is configured to transmit one or more feedback signals in response to receiving the one or more wireless commands.

47. 36. The system of claim 35, wherein the first device is configured to transmit the feedback signal at one or more predetermined recurrence intervals.

48. 1. A method for exchanging wireless signals in a wireless system, comprising: transmitting a feedback signal from a first device of the wireless system to a second device of the wireless system; receiving the feedback signal using one or more transducer elements of a transducer array of the second device; processing the feedback signal received using one or more transducer elements of the transducer array to generate feedback signal data using a processor of the second device; using the processor of the second device, determining, based at least in part on the feedback signal data, transmitter circuit data corresponding to one or more transmitter circuits of the second device configured to apply transmit signals to one or more transducer elements of the transducer array; using the processor of the second device to determine a transducer array configuration of the second device based at least in part on the feedback signal data and the transmitter circuit data; exchanging one or more wireless signals with the first device using the transducer array configuration of the second device; The method comprising:

49. 49. The method of claim 48, wherein the feedback signal data comprises one or more of absolute amplitude or magnitude, relative amplitude or magnitude, absolute signal strength, relative signal strength, signal energy in one or more frequency bands, apodization, absolute phase, relative phase, absolute delay time, relative delay time, absolute time of arrival, relative time of arrival, frequency, duration, number of cycles, absolute signal-to-noise ratio, and relative signal-to-noise ratio of the feedback signal received by one or more transducer elements of the transducer array.

50. 49. The method of claim 48, wherein the transmitter circuit data includes one or more of efficiency, power dissipation, energy dissipation, current dissipation, voltage drop, heat dissipation, temperature, temperature rise, input power, input energy, input current, input voltage, output power, output energy, output current, and output voltage of the one or more transmitter circuits.

51. 49. The method of claim 48, wherein the transducer array configuration includes one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to one or more transducer elements of the transducer array for transmitting wireless signals to the first device.

52. 49. The method of claim 48, further comprising using the processor of the second device to determine transmit apodization of the transducer elements of the transducer array.

53. 53. The method of claim 52, further comprising using the processor of the second device to select a set of transducer elements of the transducer array configuration based on one or more of the transmit apodization of the transducer elements, the transmitter circuit data, and one or more predetermined target signal strengths at the first device.

54. 54. The method of claim 53, further comprising: using the processor of the second device, determining one or more transmit voltage levels for the transducer array configuration based at least in part on a selected set of the transducer elements of the transducer array configuration.

55. 53. The method of claim 52, wherein the transmit apodization of the transducer elements is proportional to the relative signal strength of the feedback signals received by the transducer elements of the transducer array within one or more frequency bands.

56. 53. The method of claim 52, wherein the transmit apodization of two or more transducer elements is substantially equal.

57. 49. The method of claim 48, wherein the first device comprises an implantable medical device and the second device comprises an external wireless device configured to be located physically separate from the first device.

58. 49. The method of claim 48, wherein the first device comprises an external wireless device and the second device comprises an implantable medical device configured to be located physically separate from the first device.

59. 49. The method of claim 48, further comprising: transmitting a wireless command from the second device to the first device; and transmitting the feedback signal from the first device to the second device in response to receiving the wireless command.

60. 49. The method of claim 48, further comprising transmitting the feedback signal from the first device at one or more predetermined repetition intervals.

61. 1. A system configured to exchange wireless power or data, comprising: a first device including a first transducer, a first processor, and an energy storage device; the first transducer is configured to receive a first wireless power signal from a second device; the energy storage device is configured to charge based on the received first wireless power signal; the first processor is configured to determine a charging duration corresponding to one or more predetermined conditions; the first device is configured to transmit a feedback signal based on the charging duration; the second device includes a second transducer and a second processor; the second transducer is configured to receive the feedback signal; the second processor is configured to process the feedback signal to generate feedback signal data and determine a transducer configuration based at least in part on the feedback signal data; The second device is configured to transmit a second wireless power signal to the first device based on the transducer configuration.

62. 62. The system of claim 61 , wherein the predetermined condition includes one or more of: an absolute or relative duration corresponding to the received first wireless power signal; an absolute or relative duration corresponding to a voltage generated by the first device in response to the received first wireless power signal; an absolute or relative duration corresponding to a current generated by the first device in response to the received first wireless power signal; an absolute or relative power level corresponding to the received first wireless power signal; an absolute or relative energy level corresponding to the received first wireless power signal; an absolute or relative voltage level generated by the first device in response to the received first wireless power signal; and an absolute or relative current level generated by the first device in response to the received first wireless power signal.

63. 62. The system of claim 61, wherein the first processor is configured to digitize the charge duration.

64. 62. The system of claim 61, wherein the feedback signal comprises one or more of a digital representation of the charging duration and an analog representation of the charging duration.

65. 62. The system of claim 61 , wherein the feedback signal data includes one or more of a digital representation of the charging duration, an analog representation of the charging duration, an absolute amplitude or magnitude, a relative amplitude or magnitude, an absolute signal strength, a relative signal strength, a signal energy in one or more frequency bands, apodization, an absolute phase, a relative phase, an absolute delay time, a relative delay time, an absolute time of arrival, a relative time of arrival, a frequency, a duration, a number of cycles, an absolute signal-to-noise ratio, and a relative signal-to-noise ratio of the feedback signal received by the second transducer.

66. 62. The system of claim 61 , wherein the feedback signal data comprises one or more of a mean, median, mode, variance, standard deviation, minimum, maximum, percentile, histogram, statistical distribution, frequency, and probability of one or more charging durations corresponding to one or more first wireless power signals received by the first transducer from the second device.

67. 62. The system of claim 61 , wherein the transducer configuration includes one or more of an absolute or relative duration of the second wireless power signal, one or more absolute or relative power levels of the second wireless power signal, one or more absolute or relative amplitudes of the second wireless power signal, an absolute or relative pulse repetition frequency of the second wireless power signal, and an absolute or relative frequency of the second wireless power signal.

68. 62. The system of claim 61, wherein the duration of the second wireless power signal is configured to be substantially equal to or greater than the charging duration.

69. 62. The system of claim 61 , wherein the duration of the second wireless power signal is configured to be substantially equal to or greater than one or more of: one or more average charging durations, one or more median charging durations, one or more modes of charging durations, and one or more values ​​corresponding to charging durations, wherein the one or more charging durations correspond to the one or more first wireless power signals received by the first transducer from the second device.

70. 62. The system of claim 61, wherein the second transducer comprises one or more transducer arrays, the one or more transducer arrays comprising one or more transducer elements.

71. 71. The system of claim 70, wherein the transducer configuration includes one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse repetition rate, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to the one or more transducer elements for transmitting one or more wireless power signals to the first device.

72. 62. The system of claim 61, wherein the first device comprises an implantable medical device and the second device comprises an external wireless device configured to be located physically separate from the first device.

73. 62. The system of claim 61, wherein the first and second wireless power signals comprise ultrasonic or acoustic signals.

74. 1. A method for exchanging wireless signals in a wireless system, comprising: receiving, at a first transducer of a first device of the wireless system, a first wireless power signal from a second device of the wireless system, the first device including an energy storage device and a first processor, and the second device including a second transducer and a second processor; charging the energy storage device based on the received first wireless power signal; determining, using the first processor, a charging duration corresponding to one or more predetermined conditions; transmitting a feedback signal from the first device to the second device based on the charging duration; receiving the feedback signal using the second transducer; processing the feedback signal to generate feedback signal data using the second processor; using the second processor to determine a transducer configuration based at least in part on the feedback signal data; transmitting a second wireless power signal from the second device to the first device based on the transducer configuration; The method comprising:

75. 75. The method of claim 74, wherein the predetermined condition comprises one or more of: an absolute or relative duration corresponding to the received first wireless power signal; an absolute or relative duration corresponding to a voltage generated by the first device in response to the received first wireless power signal; an absolute or relative duration corresponding to a current generated by the first device in response to the received first wireless power signal; an absolute or relative power level corresponding to the received first wireless power signal; an absolute or relative energy level corresponding to the received first wireless power signal; an absolute or relative voltage level generated by the first device in response to the received first wireless power signal; and an absolute or relative current level generated by the first device in response to the received first wireless power signal.

76. 75. The method of claim 74, further comprising digitizing the charge duration using the first processor.

77. 75. The method of claim 74, further comprising using the first processor to encode or modulate the feedback signal with one or more of a digital representation of the charging duration and an analog representation of the charging duration.

78. 75. The method of claim 74, wherein the feedback signal data comprises one or more of a digital representation of the charge duration, an analog representation of the charge duration, an absolute amplitude or magnitude, a relative amplitude or magnitude, an absolute signal strength, a relative signal strength, a signal energy in one or more frequency bands, apodization, an absolute phase, a relative phase, an absolute delay time, a relative delay time, an absolute time of arrival, a relative time of arrival, a frequency, a duration, a number of cycles, an absolute signal-to-noise ratio, and a relative signal-to-noise ratio of the feedback signal received by the second transducer.

79. 75. The method of claim 74, wherein the feedback signal data comprises one or more of a mean, median, mode, variance, standard deviation, minimum, maximum, percentile, histogram, statistical distribution, frequency, and probability of one or more charging durations corresponding to one or more first wireless power signals received by the first transducer from the second device.

80. 75. The method of claim 74, wherein the transducer configuration includes one or more of an absolute or relative duration of the second radio power signal, one or more absolute or relative power levels of the second radio power signal, one or more absolute or relative amplitudes of the second radio power signal, an absolute or relative pulse repetition frequency of the second radio power signal, and an absolute or relative frequency of the second radio power signal.

81. 75. The method of claim 74, wherein the duration of the second wireless power signal is configured to be substantially equal to or greater than the charging duration.

82. 75. The system of claim 74, wherein the duration of the second wireless power signal is configured to be substantially equal to or greater than one or more of: one or more average charging durations, one or more median charging durations, one or more modes of charging durations, and one or more values ​​corresponding to charging durations, wherein the one or more charging durations correspond to the one or more first wireless power signals received by the first transducer from the second device.

83. 75. The method of claim 74, wherein the second transducer comprises one or more transducer arrays, the one or more transducer arrays comprising one or more transducer elements.

84. 84. The method of claim 83, wherein the transducer configuration includes one or more of a selected set of transducer elements, apodization, signal strength, voltage level, current level, pulse width, pulse repetition rate, pulse width modulation, duty cycle, phase, delay time, frequency, and transmission duration applied to the one or more transducer elements for transmitting one or more wireless power signals to the first device.

85. 75. The method of claim 74, wherein the first device comprises an implantable medical device and the second device comprises an external wireless device configured to be located physically separate from the first device.

86. 75. The method of claim 74, wherein the first and second radio frequency power signals comprise ultrasonic or acoustic signals.

87. 1. A wireless implantable device, comprising: a transducer configured to receive a wireless power signal; a power supply circuit coupled to the transducer and configured to recover at least a portion of the wireless power signal received by the transducer; an energy storage device coupled to the power supply circuit and configured to charge based on the portion of the wireless power signal recovered by the power supply circuit; a processor coupled to one or more of the power supply circuit, the energy storage device, and the transducer; Including, the processor is configured to determine charging parameters corresponding to one or more predetermined conditions, and to adjust parameters of one or more of the power supply circuit, the energy storage device, and the transducer based at least in part on the charging parameters.

88. 88. The device of claim 87, wherein the power supply circuit comprises one or more of an AC-DC converter, a reconfigurable AC-DC converter, a rectifier, a reconfigurable rectifier, a DC-DC converter, a reconfigurable DC-DC converter, a linear regulator, a switching regulator, a switched capacitor voltage regulator, a boost converter, a buck converter, a switched capacitor DC-DC converter, a charging circuit, a battery charging circuit, a current source, a voltage source, a constant current (CC) charging circuit, a constant voltage (CV) charging circuit, a trickle charging circuit, a pulse charging circuit, a current limiter circuit, and a voltage limiter circuit.

89. 88. The device of claim 87, wherein the energy storage device comprises one or more of a battery, a rechargeable battery, a capacitor, and an inductor.

90. 88. The device of claim 87, wherein the charging parameters include one or more of an absolute or relative duration corresponding to the wireless power signal received by the transducer, an absolute or relative duration of a voltage generated by the transducer in response to the received wireless power signal, an absolute or relative duration of a current generated by the transducer in response to the received wireless power signal, an absolute or relative duration corresponding to the wireless power signal recovered by the power circuit, an absolute or relative duration of a voltage generated by the power circuit in response to the recovered wireless power signal, an absolute or relative duration of a current generated by the power circuit in response to the recovered wireless power signal, an absolute or relative duration corresponding to the charging of the energy storage device, and an absolute or relative rate of charge of the energy storage device.

91. 88. The device of claim 87, wherein the charging parameters include an absolute or relative voltage level corresponding to the energy storage device, an absolute or relative current level corresponding to the energy storage device, an absolute or relative power level corresponding to the energy storage device, an absolute or relative energy level corresponding to the energy storage device, an absolute or relative voltage level corresponding to the power supply circuit, an absolute or relative current level corresponding to the power supply circuit, an absolute or relative power level corresponding to the power supply circuit, an absolute or relative voltage level corresponding to the transducer, an absolute or relative current level corresponding to the transducer, and an absolute or relative power level corresponding to the transducer.

92. 88. The device of claim 87, wherein the processor is configured to digitize the charging parameter.

93. 88. The device of claim 87, wherein the parameters of the power supply circuit adjusted by the processor include one or more of a charging current level, a charging voltage level, a charging mode, an AC-DC converter switching frequency, a DC-DC converter switching frequency, an AC-DC converter load current, a DC-DC converter load current, a matching network configuration, and a signal applied to a switch coupled to the power supply circuit.

94. 88. The device of claim 87, wherein the parameters of the energy storage device adjusted by the processor include one or more of a capacitor selection, a battery selection, a number of capacitors, a number of batteries, a capacitance value, and a signal applied to a switch coupled to the energy storage device.

95. 88. The device of claim 87, wherein the parameters of the transducer adjusted by the processor include one or more of a transducer element selection, an impedance coupled to the transducer, a matching network coupled to the transducer, and a signal applied to a switch coupled to the transducer.

96. 88. The device of claim 87, wherein the transducer comprises an acoustic transducer and the wireless power signal comprises an acoustic power signal.

97. 97. The device of claim 96, wherein the acoustic transducer comprises an ultrasonic transducer and the acoustic power signal comprises an ultrasonic power signal.

98. 1. A method for charging a wireless implantable device, comprising: receiving a wireless power signal using a transducer of the wireless implantable device; recovering at least a portion of the received wireless power signal using a power circuit coupled to the transducer; charging an energy storage device coupled to the power supply circuit based on the recovered portion of the received wireless power signal; determining charging parameters corresponding to one or more predetermined conditions using a processor coupled to one or more of the power supply circuit, the energy storage device, and the transducer; adjusting, using the processor, parameters of one or more of the power supply circuit, the energy storage device, and the transducer based at least in part on the charging parameters; The method comprising:

99. 100. The method of claim 98, wherein the power supply circuit comprises one or more of an AC-DC converter, a reconfigurable AC-DC converter, a rectifier, a reconfigurable rectifier, a DC-DC converter, a reconfigurable DC-DC converter, a linear regulator, a switching regulator, a switched capacitor voltage regulator, a boost converter, a buck converter, a switched capacitor DC-DC converter, a charging circuit, a battery charging circuit, a current source, a voltage source, a constant current (CC) charging circuit, a constant voltage (CV) charging circuit, a trickle charging circuit, a pulse charging circuit, a current limiter circuit, and a voltage limiter circuit.

100. 99. The method of claim 98, wherein the energy storage device comprises one or more of a battery, a rechargeable battery, a capacitor, and an inductor.

101. 99. The method of claim 98, wherein the charging parameters include one or more of: an absolute or relative duration corresponding to the wireless power signal received by the transducer; an absolute or relative duration of a voltage generated by the transducer in response to the received wireless power signal; an absolute or relative duration of a current generated by the transducer in response to the received wireless power signal; an absolute or relative duration corresponding to the wireless power signal recovered by the power circuit; an absolute or relative duration of a voltage generated by the power circuit in response to the recovered wireless power signal; an absolute or relative duration of a current generated by the power circuit in response to the recovered wireless power signal; an absolute or relative duration corresponding to the charging of the energy storage device; and an absolute or relative rate of charge of the energy storage device.

102. 99. The method of claim 98, wherein the charging parameters include an absolute or relative voltage level corresponding to the energy storage device, an absolute or relative current level corresponding to the energy storage device, an absolute or relative power level corresponding to the energy storage device, an absolute or relative energy level corresponding to the energy storage device, an absolute or relative voltage level corresponding to the power supply circuit, an absolute or relative current level corresponding to the power supply circuit, an absolute or relative power level corresponding to the power supply circuit, an absolute or relative voltage level corresponding to the transducer, an absolute or relative current level corresponding to the transducer, and an absolute or relative power level corresponding to the transducer.

103. 99. The method of claim 98, wherein the processor is configured to digitize the charging parameter.

104. 99. The method of claim 98, wherein the parameters of the power supply circuit adjusted by the processor include one or more of a charging current level, a charging voltage level, a charging mode, an AC-DC converter switching frequency, a DC-DC converter switching frequency, an AC-DC converter load current, a DC-DC converter load current, a matching network configuration, and a signal applied to a switch coupled to the power supply circuit.

105. 99. The method of claim 98, wherein the parameters of the energy storage device adjusted by the processor include one or more of a capacitor selection, a battery selection, a number of capacitors, a number of batteries, a capacitance value, and a signal applied to a switch coupled to the energy storage device.

106. 99. The method of claim 98, wherein the parameters of the transducer adjusted by the processor include one or more of a transducer element selection, an impedance coupled to the transducer, a matching network coupled to the transducer, and a signal applied to a switch coupled to the transducer.

107. 99. The method of claim 98, wherein the transducer comprises an acoustic transducer and the wireless power signal comprises an acoustic power signal.

108. 108. The method of claim 107, wherein the acoustic transducer comprises an ultrasonic transducer and the acoustic power signal comprises an ultrasonic power signal.

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