Distancing system and method using channel sounding

Abstract

A system and method for determining the distance between a first device (e.g., an object device) and a second device (e.g., a remote device) based on phase characteristics determined with respect to transmission from a first device to a second device, and optionally, return transmission from the second device to the first device.

Description

[Technical Field]

[0001] This disclosure relates to a system and method for determining the distance between a remote device and an object such as a vehicle. [Background technology]

[0002] Real-time location and positioning of objects is becoming increasingly prevalent across a wide range of applications. Real-time location systems (RTLS) are trusted and used to track objects such as portable and remote devices in many fields, including automotive, storage, retail, secure access for authentication, and secure access for authorization.

[0003] A conventional RTLS in the automotive sector includes a transmitter located within the vehicle that can communicate with a remote device via radio frequency (RF). Often, the signal strength of the communication between the transmitter and the remote device is used as a basis for determining the location of the remote device relative to the transmitter or vehicle. For example, a low signal strength may indicate that the remote device is farther away from the vehicle than a high signal strength indicates. Generally, the greater the distance between the remote device and the vehicle, the weaker the communication strength. Communication between the transmitter and the remote device can be intercepted (sniffed) by sensors placed on the object. The signal strength of such intercepted communication can be used as a basis for determining the distance between the remote device and each sensor. The distance to each of these sensors allows for the determination of the remote device's location relative to the object.

[0004] Environmental and external interference can significantly impact the accuracy of determining location and distance based on communications. For example, the environment can produce reflections that negatively affect sensor measurements. RF interference can similarly negatively impact the ability to accurately determine the location of a remote device relative to an object based on the nature of the communications, such as the signal strength of the communications. [Overview of the project]

[0005] In general, one innovative aspect of the subject matter described herein can be embodied in a system for determining the distance between a remote device and an object. The system may include a first device, which includes a first antenna system positioned at a fixed location relative to the object and configured to receive and / or transmit a first tone signal from the remote device. A control system may be configured to determine first and second phase characteristics of the first tone signal at first and second frequencies. The first and second phase characteristics may indicate a first phase rotation of the first tone signal between the first device and the remote device. The first control system may be operable to determine a first distance between the first device and the remote based on the first phase rotation of the first tone signal.

[0006] The system may include a second device positioned at a fixed location relative to an object. The second device may include a second antenna system configured to monitor a first tone signal between the first device and a remote device. The control system may be configured to determine a second phase rotation of the first tone signal monitored by the second device. Based on the first and second phase rotations, the control system may be configured to determine a second device clock offset between the second device and the remote device.

[0007] The embodiments described above and other embodiments may each optionally include one or more of the following features, either individually or in combination. In particular, one embodiment includes all combinations of the following features.

[0008] In some embodiments, the control system may be configured to determine the relative clock offset between the first device and the second device based on the second device clock offset.

[0009] In some embodiments, the control system may be configured to determine a third phase rotation between the first and second devices without using clock ambiguity based on relative clock offsets and ambiguous phase rotation between the first and second devices determined based on a monitored first tone signal.

[0010] In some embodiments, the second device may be configured to receive a second tone signal from a remote device and / or transmit a second tone signal to the remote device. The first device may be configured to monitor the second tone signal between the second device and the remote device, and the control system may be configured to determine a third phase rotation of the second tone signal between the second device and the remote device. The control system may be configured to determine a fourth phase rotation between the remote device and the first device based on (1) the second tone signal monitored by the first device and (2) the second device clock offset between the second device and the remote device.

[0011] In some embodiments, the first frequency and the second frequency are different.

[0012] In some embodiments, the control system is provided in the first device, in which case the first device can operate as an initiator.

[0013] In some embodiments, the remote device may be capable of functioning as a reflector.

[0014] In some embodiments, the control system may be provided as a first control system and a second control system, which are separately located within the first device and the second device, respectively.

[0015] In some embodiments, the remote device may be able to operate as an initiator, and the first device may be able to operate as a reflector.

[0016] In some embodiments, the control system is operable to determine a third phase characteristic of the first tone signal at a third frequency, the third phase characteristic indicating a first phase rotation of the first tone signal between the first device and the remote device.

[0017] In some embodiments, the first frequency, the second frequency, and the third frequency may be different from each other.

[0018] In some embodiments, the first tone signal is an initiator tone signal, in which case the first phase characteristic and the second phase characteristic may be determined by the remote device with respect to the reception of the initiator tone signal from the first device.

[0019] In some embodiments, the first tone signal is a reflector tone signal, in which case the first phase measurement and the second phase characteristic may be determined by the first device with respect to the reception of the reflector tone signal from the remote device.

[0020] In some embodiments, the first phase characteristic of the reflector tone signal indicates a bidirectional phase rotation between the initiator tone signal and the reflector tone signal at the first frequency, while the second phase characteristic of the reflector tone signal may indicate a bidirectional phase rotation between the initiator tone signal and the reflector tone signal at the second frequency.

[0021] In some embodiments, the control system may be operable to determine a first distance based on (1) a difference between the first phase characteristic and the second phase characteristic, and (2) a difference between the first frequency and the second frequency.

[0022] In some embodiments, the control system may be configured to compensate for the movement of the remote device with respect to the first device.

[0023] In some embodiments, the control system may be configured to reduce the influence of an estimated velocity vector from at least one of the first phase rotation and the second phase rotation.

[0024] In some embodiments, the control system may be configured to compensate for multi-phase effects in the environment.

[0025] In some embodiments, the control system may be configured to generate a K-space mapping of the phase rotation and identify multi-path artifacts based on the K-space mapping.

[0026] In some embodiments, the remote device may operate as a reflector and the first device may operate as an initiator.

[0027] In some embodiments, the second device may be configured to receive a second tone signal from the first device and / or transmit a second tone signal to the first device.

[0028] In some embodiments, the control system may be configured to determine a third phase characteristic based on the second tone signal.

[0029] In some embodiments, the control system may be configured to repeatedly update a second device clock offset based on the second tone signal.

[0030] Generally, one innovative aspect of the subject matter described herein may be embodied in a method for determining the position of a remote device relative to a first device. The method can include transmitting an initiator signal between the remote device and the first device according to a first frequency and transmitting an initiator signal between the remote device and the first device according to a second frequency.

[0031] The method can include determining a first phase characteristic of the initiator signal at the first frequency and a second phase characteristic of the initiator at the second frequency, and the first characteristic and the second characteristic can indicate a first phase rotation of the initiator signal between the first device and the remote device.

[0032] The method may include, in the second device, monitoring the initiator signal between the remote device and the first device, and determining the second phase rotation of the initiator signal monitored by the second device.

[0033] The method may include determining a second device clock offset between the second device and the remote device based on a first phase rotation and a second phase rotation, and determining the position of the remote device based on at least the first phase rotation.

[0034] The embodiments described above and other embodiments may each optionally include one or more of the following features, either individually or in combination. In particular, one embodiment includes all combinations of the following features.

[0035] In some embodiments, the method may include determining the relative clock offset between the first device and the second device based on the second device clock offset.

[0036] In some embodiments, the method may include determining a third phase rotation between a first device and a second device without using clock ambiguity based on relative clock offset and ambiguous phase rotation between the first device and the second device determined based on a monitored first tone signal.

[0037] In some embodiments, the method may include, with respect to a second device, receiving a second tone signal from a remote device and / or transmitting a second tone signal to the remote device, and, with respect to a first device, monitoring the second tone signal between the second device and the remote device. The method may also include determining a third phase rotation of the second tone signal between the second device and the remote device, and determining a fourth phase rotation between the remote device and the first device based on (1) the second tone signal monitored by the first device and (2) a second device clock offset between the second device and the remote device.

[0038] Before describing embodiments of the present invention in detail, it should be understood that the present invention is not limited to the operational details, configuration details, and arrangement of components described in the following description or illustrated in the drawings. The present invention can be carried out in various other embodiments and can be practiced or performed in alternative ways not expressly disclosed herein. It should also be understood that the language and terminology used herein are for illustrative purposes only and not limiting. The use of “includes” and “equips” and similar words means that the items and their equivalents listed thereafter, as well as additional items and their equivalents, are included. Furthermore, enumerations may be used in the description of various embodiments. Unless expressly stated otherwise, the use of enumerations should not be construed as limiting the present invention to a particular order or number of components. Nor should the use of enumerations be construed as excluding any additional steps or components that may be combined with or incorporated into the enumerated steps or components from the scope of the present invention. [Brief explanation of the drawing]

[0039] [Figure 1] Figure 1 shows a system according to one embodiment of the present disclosure. [Figure 2] Figure 2 shows a system according to one embodiment. [Figure 3]Figure 3 shows the devices of the system in one embodiment. [Figure 4] Figure 4 shows a portion of the devices in one embodiment of the system. [Figure 5] Figure 5 shows a system according to one embodiment. [Figure 6] Figure 6 shows a system according to one embodiment. [Figure 7] Figure 7 shows the devices of a system according to one embodiment. [Figure 8] Figure 8 shows communication according to one embodiment. [Figure 9] Figure 9 shows communication according to one embodiment. [Figure 10] Figure 10 shows phase wrapping of communication according to one embodiment. [Figure 11] Figure 11 shows a sniffing arrangement according to one embodiment. [Figure 12] Figure 12 shows a method for determining phase rotation according to one embodiment. [Figure 13] Figure 13 shows a method for determining phase rotation according to one embodiment. [Figure 14] Figure 14 shows a method of phase reconstruction according to one embodiment. [Figure 15] Figure 15 shows a method for determining phase characteristics according to one embodiment. [Figure 16] Figure 16 shows the timing between two devices during transmit and receive channel sounding communication according to one embodiment. [Figure 17] Figure 17 shows a sniffing arrangement with a moving remote device according to one embodiment. [Figure 18] Figure 18 shows a method for compensating a moving remote device according to one embodiment. [Figure 19] Figure 19 shows a method for compensating for multipath artifacts according to one embodiment. [Modes for carrying out the invention]

[0040] In one embodiment, a system and method are provided for determining the distance between a first device (e.g., an object device) and a second device (e.g., a remote device) based on phase characteristics determined with respect to a transmission from a first device to a second device and, optionally, a return transmission from the second device to the first device. The transmission is performed from the first device and can accommodate various frequencies.

[0041] A system according to one aspect of this disclosure may conform to wireless or communication specifications (e.g., Bluetooth specifications) to more effectively achieve industry acceptance. A passive channel sounding procedure with sniffing may be provided to allow increasing the system sampling rate at a multiplier proportional to the number of reflectors (e.g., object-based devices or anchors) in the system. Simultaneous phase measurements from multiple displacement reflectors allow the system to incorporate active motion compensation to more accurately locate remote devices. By not requiring the reflector radios to have coherent phase-locked loop elements, system 100 may be less complex and less expensive than conventional systems that require multiple coherent radios.

[0042] In system 100 equipped with a sniffing reflector, additional functions, use cases, and applications may be enabled. For example, in the case of a stationary vehicle, an application could include building a Ground Moving Target Indicator (GMTI) that could be used to confirm that an approaching person is in the same location as a remote device, based on simultaneously sniffed phase differences. Another example is using this system inside a car to detect the movement of a child or dog and indicate their presence to take action, such as issuing a warning to a mobile device or rolling down a window. In yet another example, in the case of a moving vehicle, the system could assist with remote parking.

[0043] (I. Overview of the Location Information System) A system and method are provided for determining the position of a remote device relative to an object based on phase-based distance. The system and method can determine the position of a remote device based on the phase-based distance of a first communication between a first object device (e.g., a sensor, also called an anchor) and a remote device, and the phase-based distance of the first communication monitored by a second object device (e.g., a sensor, also called an anchor). A clock difference between the first and second devices is determined, and this clock difference can form the basis for determining the phase-based distance of the first communication monitored by the second object device. The clock difference may be determined iteratively. The phase-based distance can be based on the signal characteristics of the communication determined with respect to the first communication, such as a determined phase rotation of the first communication between the remote device and the first object device, or a determined phase rotation of the first communication between the remote device and the second object device.

[0044] In one embodiment, the position of the remote device may be determined based on the phase-based distance of the second communication between the second object device and the remote device, and the phase-based distance of the second communication monitored by the first object device.

[0045] In one embodiment, the object is mobile, and its environment may change depending on the object's location. For example, if the object is a vehicle, it may be stored overnight in an enclosed garage with a movable partition, then driven to an outdoor parking lot where it is parked, and there may be one or more other vehicles nearby. The environmental configuration of these locations may differ in important respects with respect to RF or radio communication, and the environmental configuration may change over time, even when the object is not moving relative to the environment. Such environmental changes, and other possible additional factors, may affect the clock difference between the first and second devices with respect to radio communication. An additional example of a system that adapts to environmental conditions is described in U.S. Patent 10869161, “System and Method for Determining Real-Time Location,” published to Smith on December 15, 2020.

[0046] In one embodiment, a locator may be provided to determine the location information of a remote device relative to an object based on the signal characteristics of communication with the remote device. It should be understood that this disclosure is not limited to determining location information based on a single signal characteristic of communication, and that one or more additional signal characteristics of communication may be used by the locator as a basis for determining location information.

[0047] As shown in Figure 4, the locator may include a core function 312 that can operate in conjunction with one or more parameters 314 to determine location information based on one or more inputs 316, such as at least one signal characteristic of wireless communication, and to generate one or more outputs 318 indicating the location of the remote device 20 relative to an object 10. Values ​​for one or more parameters may be selected to generate location information of the remote device relative to an object with a certain degree of confidence in a given environment. For example, the locator may be configured to determine the location of the remote device relative to an object with a confidence of 90% or more in an outdoor parking lot where no vehicles are nearby or within 4 inches. In one embodiment, the selection of values ​​for one or more parameters may be based on empirical analysis, which includes obtaining truth data about the actual location of the remote device relative to an object, along with at least one sample of at least one signal characteristic for each actual location. As discussed herein, the system may include multiple object devices positioned at different locations on an object, thereby allowing for the acquisition of multiple signal characteristics of wireless communication with respect to different locations on the object. Multiple signal characteristics may correlate with truth data regarding the actual location of a remote device relative to an object, and one or more parameters combined with the core position function may be trained or selected to generate position information that approximates the truth data within a certain confidence range.

[0048] A system according to one embodiment is shown in the illustrated embodiments of Figures 1, 2, and 5, and is shown as 100 overall. System 100 may include one or more system components outlined herein. The system components may be a remote device 20, a sensor 40, or an object device 50, or a user 60 or an electronic system component, which may be a component including one or more of these devices. As discussed herein, the basic components of the object device 50 are configured to work in conjunction with any one or more of these devices. In this sense, in one embodiment, there may be several aspects or features common to the remote device 20, the sensor 40, and the object device 50. Features described in relation to the object device 50 shown in Figure 3 may be incorporated into the remote device 20 or the sensor 40, or both. In one embodiment, the object device 50 may form an equipment component placed on an object 10 such as a vehicle or a building. The object device 50 may be communicatively coupled to one or more systems of object 10 in order to control the operation of object 10, transmit information to one or more systems of object 10, receive information from one or more systems of object 10, or a combination thereof. For example, object 10 may include an object controller 12 configured to control the operation of object 10. Object 10 may include one or more wired or wireless communication networks that enable communication between the object controller 12 and the object device 50. The communication network that enables communication between the object device 50 and the object controller 12 is indicated by 150 in the embodiment shown in Figure 2 and is provided as a CAN bus. However, it should be understood that the communication network is not limited thereto. The communication network can be any type of network, including wired or wireless networks, or a combination of two or more types of networks.

[0049] In the embodiment shown in Figure 3, the object device 50 may include a control system or controller 58 configured to control the operation of the object device 50 according to one or more functions and algorithms described herein, or embodiments thereof. System components such as the remote device 20 and / or the sensor 40 may similarly include the controller 58.

[0050] The controller 58 may include electrical circuits and components for performing the functions and algorithms described herein. Generally speaking, the controller 58 may include one or more microcontrollers, microprocessors, and / or other programmable electronic devices programmed to perform the functions described herein. The controller 58 may additionally or alternatively include other electronic components programmed to perform the functions described herein, or supporting the microcontrollers, microprocessors, and / or other electronic devices. Other electronic components may include, but are not limited to, one or more field-programmable gate arrays, systems on chips, volatile or non-volatile memory, discrete circuits, integrated circuits, application-specific integrated circuits (ASICs), and / or other hardware, software, or firmware. Such components may be physically configured in any suitable way, such as being mounted on one or more circuit boards or arranged in any other manner, to combine into a single unit or distributed across multiple units. Such components may be physically distributed at different locations within the object device 50 or at common locations within the object device 50. When physically distributed, components can communicate using any suitable serial or parallel communication protocol, including but not limited to CAN, LIN, Vehicle Area Network (VAN), FireWire, I2C, RS-232, RS-485, and Universal Serial Bus (USB).

[0051] As described herein, the terms locator, module, model, and generator refer to components of the controller 58. For example, a model or locator in one embodiment is described as having one or more core functions and one or more parameters that affect the outputs of one or more core functions. A model or locator can be stored in the memory of the controller 58, and can also form part of the controller configuration such that the model is part of the controller 58 configured to receive and transform one or more inputs and output one or more outputs. Similarly, a module or generator is part of the controller 58 configured to receive inputs described in relation to the module or generator and to provide outputs corresponding to algorithms associated with the module or generator.

[0052] The controller 58 of the object device 50 in the embodiment shown in Figure 3 may include, among other electronic hardware, one or more processors 51 that run one or more applications 57 (including software and / or firmware), one or more memory units 52 (e.g., RAM and / or ROM), and one or more communication interfaces 53. The object device 50 may or may not have an operating system 56 that controls access to lower-level devices / electronic devices via the communication interface 53. The object device 50 may or may not have a hardware-based encryption unit 55. If they are not present, encryption functions may be performed in software. The object device 50 may or may not have a secure memory unit 54 (e.g., a secure element or hardware security module (HSM)) (or may or may not have access to one). In the illustrated embodiment, optional components and communication paths are shown by dotted lines.

[0053] The controller 58 in the embodiment shown in Figure 3 does not depend on the presence of a secure memory unit 54 in any component. Optionally, if a secure memory unit 54 is not present, data that might be stored in the secure memory unit 54 (e.g., confidential and / or private keys) can be encrypted during hibernation. By utilizing both software-based and hardware-based mitigation measures, access to such data can be substantially prevented, and compromises of entire system components can be substantially prevented or detected, or both. Examples of such mitigation features include the implementation of physical obstacles and shields, the disabling of JTAG and other ports, strengthening software interfaces to eliminate attack vectors, the use of trusted execution environments (hardware, software, or both), and the detection of root access or compromise of the operating system.

[0054] For the purposes of disclosure, security is generally understood to mean confidentiality (encryption), authentication, and integrity verification. However, this disclosure is not limited to these, and the term “secure” may be a subset of these aspects or may include additional aspects related to data security.

[0055] The communication interface 53 can be any type of communication link, including any type of communication link described herein, including wired or wireless. The communication interface 53 can enable external communication, internal communication, or both. For example, the communication interface 53 can be coupled to or incorporate the antenna array 30. The antenna array 30 may include one or more antennas configured to enable wireless communication, including Bluetooth Low Energy (BTLE) communication.

[0056] In another example, the communication interface 53 may provide a wireless communication link with another system component in the form of a remote device 20, such as wireless communication compliant with the Wi-Fi standard. In yet another example, the communication interface 53 may be configured to communicate with the vehicle's object controller 12 (e.g., a vehicle component) via a wired link, such as a CAN-based wired network, enabling communication between multiple devices. In one embodiment, the communication interface 53 may include a display and / or input interface for transmitting information to and / or receiving information from the user 60.

[0057] In one embodiment, the object device 50 may be configured to communicate with another object device 50 or one or more auxiliary devices other than the user. The auxiliary devices may be configured differently from the object device 50. For example, the auxiliary device may not include a processor 51 and instead include at least one direct connection and / or communication interface for sending and receiving information with or receiving information from the object device 50, or both. For example, the auxiliary device may be a solenoid that accepts input from the object device 50, or the auxiliary device may be a sensor (e.g., a proximity sensor) that provides analog and / or digital feedback to the object device 50.

[0058] The system 100 in the illustrated embodiment can be configured to determine location information in real time with respect to the remote device 20. In the embodiments shown in Figures 1, 2, and 5, the user 60 may carry the remote device 20 (e.g., a smartphone). The system 100 can enable real-time positioning of the remote device 20 relative to the object 10 (e.g., a vehicle) with sufficient accuracy to determine whether the user 60 is in a position to access the object 10 or to be granted permission to issue an object command.

[0059] For example, in an embodiment where object 10 is a vehicle, the system 100 may be able to determine whether the remote device 20 is outside the vehicle but very close, such as within 5 feet, 3 feet, or 2 feet of the driver's side door 15. This determination can form the basis for determining whether the system 100 needs to unlock the vehicle. On the other hand, if the system 100 determines that the remote device 20 is outside the vehicle and not very close to the driver's side door (e.g., outside the range of 2 feet, 3 feet, or 5 feet), the system 100 may decide to lock the driver's side door. As another example, if the system 100 determines that the remote device 20 is very close to the driver's seat and not close to the passenger seat or rear seat, the system 100 may decide to allow the vehicle to move. Conversely, if the system 100 determines that the remote device 20 is outside very close to the driver's seat, the system 100 may decide to immobilize the vehicle or keep the vehicle immobilized.

[0060] Object 10 may include a plurality of object devices 50 or variations thereof, such as an object device 50 including a sensor 40 coupled to an antenna array 30, according to one or more embodiments described herein.

[0061] The microlocation of the remote device 20 can be determined in various ways, including by information obtained from a global positioning system, one or more signal characteristics of communications from the remote device 20, and one or more sensors (e.g., proximity sensors, limit switches, or vision sensors), or a combination thereof. An example of the microlocation technology that system 100 can constitute is described in Nonprovisional Patent Application No. 15 / 488136, filed April 17, 2017, entitled “System and Method for Establishing Real-Time Position,” by Raymond Michael Stitt et al., the disclosure of which is incorporated herein by reference in whole.

[0062] In one embodiment, as illustrated in Figures 1 to 5, the object device 50 (e.g., a system control module (SCM)) and a plurality of sensors 40 (coupled to an antenna array 30 as shown in Figure 3) can be positioned on or in a fixed location relative to the object 10. Examples of use cases for the object 10 include the vehicle specified in the above example, or a building whose access is controlled by the object device 50.

[0063] The remote device 20 can communicate wirelessly with the object device 50 via a communication link 140. Multiple sensors 40 may be configured to monitor (e.g., sniff) the communication on the communication link 140 between the remote device 20 and the object device 50 and determine one or more signal characteristics of the communication, such as phase characteristics, signal strength, time of arrival, time of flight, or angle of arrival, or a combination thereof. The determined signal characteristics may be communicated to the object device 50 via a separate communication link 130 from the communication link between the remote device 20 and the object device 50, or communicated after analysis. Additionally or alternatively, the remote device 20 may establish a direct communication link with one or more sensors 40 and determine one or more signal characteristics based on this direct communication link.

[0064] One or more sensors 40 can be placed at various locations on the object 10, such as the locations described herein, including, for example, one or more sensors 40 in the door panel and one or more other sensors in the B-pillar.

[0065] The object device 50 and one or more sensors 40 may be powered via a power bus 120. The power bus 120 can be daisy-chained from one device to the next, as shown in the embodiment illustrated in Figure 6. Alternatively, the power bus 120 may be provided in the form of a star connection, where power is supplied from one location to multiple locations via separate connections. The power supply and associated architecture are not limited to one type. For example, power may be distributed in both daisy-chain and star connection configurations. The power bus 120 may be coupled to a power supply 110 to facilitate the distribution of power to devices in the system 100.

[0066] The system 100 in the illustrated embodiment can be configured to determine location information in real time with respect to the remote device 20. In the embodiment shown in Figure 5, the user may carry the remote device 20 (e.g., a smartphone). The system 100 can enable real-time positioning of the remote device 20 relative to the object 10 (e.g., a vehicle) with sufficient accuracy to determine whether the user is in a position to access the object 10 or to be authorized to issue an object 10 command.

[0067] In the embodiment shown in Figure 6, the communication link 130 is distributed from one device to another, with a terminator 132 at each end. The communication link 130 between devices may be a shared link, a separate link for each device, or a combination thereof. For example, the communication link 130 may be shared by two or more devices as shown, or additionally or alternatively, the communication link 130 may be established individually from one device to another. Devices can communicate via multiple separate communication links 130, and can also be configured to relay communication from one communication link 130 to another.

[0068] The remote device 20 can communicate wirelessly with the object device 50 via a communication link 140, such as a BLE communication link or an ultra-wideband (UWB) communication link. Multiple sensors 40 may be configured to monitor (sniff) communications on the communication link 140 between the remote device 20 and the object device 50, as shown by the virtual line 142. The monitored communications or transmissions may correspond to tone exchanges (unidirectional or bidirectional) between the object device 50 and the remote device 20. Based on the monitored communications, the sensors 40 may determine one or more signal characteristics of the communications described herein, including the phase characteristics of the communications. Additional or alternative signal characteristics may include signal strength, time of arrival, time of flight, angle of arrival, or a combination thereof. The determined signal characteristics may be communicated to the object device 50 via a communication link 130 separate from the communication link 140 between the remote device 20 and the object device 50, or may be communicated after analysis.

[0069] Additionally or alternatively, as described herein, the remote device 20 may establish a direct communication link with one or more sensors 40, and one or more signal characteristics may be determined based on this direct communication link. For example, as described herein, the remote device 20 and the sensors 40 may perform tone exchange as a basis for determining the distance between the sensors 40 and the remote device 20. The direct communication link may be established according to the BLE protocol. However, the disclosure is not limited thereto, and the direct communication link may be any type of link, including ultra-wideband (UWB).

[0070] It should be understood that an object 10, such as a vehicle, may contain more or fewer sensors 40(AF) than those shown in the embodiments illustrated in Figures 1 and 2. Depending on the embodiment, some sensors 40 may be integrated into the vehicle.

[0071] As described herein, one or more signal characteristics, such as phase characteristics, signal strength, time of arrival, time of flight, and angle of arrival, may be analyzed in aspect of object 10 to determine positional information of the remote device 20 relative to object 10, or object device 50, or a combination thereof. For example, the phase rotation of tone transmission and optional retransmission, or a phase characteristic indicating phase rotation, may form the basis for determining the distance between object device 50 or sensor 40 and the remote device 20. Further examples of signal characteristics include the time of arrival difference or angle of arrival, or both, in object device 50 and sensor 40, which may be processed to determine the relative position of the remote device 20. Since the positions of one or more antenna arrays 30 relative to object device 50 are known, the relative position of the remote device 20 can be translated into an absolute position relative to antenna arrays 30 and object device 50.

[0072] Additional or alternative types of signal characteristics may be acquired to facilitate position determination according to one or more algorithms, including distance functions, trilateration functions, triangulation functions, edge measurement functions, polydextrinsic functions, fingerprinting functions, difference functions, time-of-flight functions, time-of-arrival functions, time-of-arrival difference functions, departure angle functions, geometric functions, or any combination thereof.

[0073] (II. Overview of System Devices) In the illustrated embodiment shown in Figure 7, one aspect of the object device 50 is shown in further detail. The structures and configurations described in relation to Figure 7 can be incorporated into the sensor 40 or the object device 50. However, for the purposes of disclosure, the structures and configurations are described in relation to the object device 50.

[0074] The object device 50 in the embodiment shown in Figure 7 includes several components, one or more of which may be provided in commercial embodiments. In some examples, the object device 50 can be described as an anchor placed on the object 10.

[0075] The object device 50 may include an RF circuit 204 that is operable to control the transmission and reception of HF signals. The RF circuit 204 may be operably coupled to an antenna array 30 including one or more antennas. An example configuration of the antenna array 30 is described in Nonprovisional Patent Application No. 18 / 096666, filed on 13 January 2023, entitled “System and Method for Communications,” the disclosure of which is incorporated herein by reference in whole.

[0076] The RF circuit 204 may be configured to supply high-frequency signals to or receive high-frequency signals from the antenna array 30 via the filter circuit 206 and the HF switch 208. The filter circuit 206 can adjust the signal output from the RF circuit 204 to drive the antenna array 30. Conversely, the filter circuit 206 can adjust the signal received from the antenna array 30 for processing by the RF circuit 204. The HF switch 208 can selectively indicate the input and output of HF signals, including HF supplied to the antenna array 30 and HF received from the antenna array 30.

[0077] In one embodiment, the RF circuit 204 may be configured to transmit and receive signals via the high-frequency interface of the communication link 130. In one embodiment, by transmitting and receiving HF signals, the object device 50 may be able to communicate over a physical medium in accordance with the same or similar communication protocol as the communication protocol used by the antenna array 30 of the RF circuit 204. For example, the object device 50 may transmit and receive communications over a physical medium defined by the high-frequency interface corresponding to BTLE communication, and may also transmit and receive communications over the antenna array 30 corresponding to BTLE communication.

[0078] The HF switch 208 can selectively send the output from the RF circuit 204 to the high-frequency interface of the communication link 130, and selectively send the input from the high-frequency interface of the communication link 130 to the RF circuit 204. In one embodiment, the HF interface may be a single-ended configuration, such as a coaxial conductor arrangement. Alternatively, the HF interface may be differential and optionally include adjustment circuits 214, 216 (e.g., baluns and / or impedance transformers) that convert between the single-ended output from the HF switch 208 and the differential output of the high-frequency interface of the communication link 130.

[0079] In one embodiment, the high-frequency switch 208 and the adjustment circuits 214, 216 may be omitted, and as a result, the communication link 130 is provided via a serial interface or another type of communication interface, as described herein.

[0080] In the illustrated embodiment, the object device 50 is configured to send and receive communications via a separate high-frequency interface provided by a separate communication link 130. In other words, the two communication links 130 in the illustrated embodiment are isolated from each other, and communications received on one communication link 130 are not essentially transmitted or acknowledged on the other communication link 130. As described herein, the object device 50 can be configured to relay communications from one of the communication links 130 to the other of the communication links 130. For example, communications received via one high-frequency interface may be directed to an RF circuit 204 and relayed through the RF circuit 204 to the other high-frequency interface. The HF switch 208 may be in transition from one state to another to enable such relaying of communications. However, it should be understood that in one or more embodiments described herein, communications transmitted via one of the communication links 130 may essentially be passed to the other of the communication links 130.

[0081] The object device 50 includes a main controller 51, which may be configured to direct the operation of the RF circuit 204 as described herein. In one embodiment, the main controller 51 can control tone exchange via the antenna array 30 to enable the determination of a unidirectional or bidirectional distance to the remote device 20. Additionally or alternatively, the object device 50 may be involved in tone exchange and sniff communication taking place between another object device (e.g., a sensor 40) and the remote device 20. In one embodiment, the sensor 40 may be involved in tone exchange and configured to monitor or sniff communication taking place between the object device 50 and the remote device 20.

[0082] The main controller 51 can further instruct the transmission and reception of communications via the HF interface of one or more communication links 130. For example, the main controller 51 can instruct the transmission and reception of BTLE communications via the HF interface of communication link 130. The information transmitted via the high-frequency interface of communication link 130 may relate to one or more signal characteristics acquired with respect to communications received and / or transmitted via the antenna array 30. For example, the information transmitted via communication link 130 may indicate a phase rotation determined with respect to communications received and / or transmitted via the antenna array 30.

[0083] Additionally, or alternatively, the main controller 51 may utilize the high-frequency interface of the communication link 130 for the purpose of determining time synchronization or time offset. As described herein, the phase characteristics of tone exchange are at least in part based on the time reference of the device. Furthermore, with respect to electromagnetic waves, time is convertible to distance (and conversely, distance is convertible to time), and determining the reference time of the sensor 40 can easily improve the accuracy in determining the phase characteristics and distance between the remote device 20 and the object device 50.

[0084] The object device 50 may include a clock 202 that operates the oscillator of the sensor 40 and generates one or more timing signals for the operation of an embodiment of the object device 50, including the main controller 51 and the RF circuit 204. In one embodiment, the clock 202 may be configured to generate timing signals that can be used as a reference for the main controller 51 and / or the RF circuit 204 to transmit a tone-changed signal (e.g., an initiator signal). As described herein, the tone-changed signal may include transmissions at multiple frequencies and phase rotations with respect to such transmissions, which can form the basis for determining the distance between the object device 50 and the remote device 20.

[0085] In one embodiment, the object device 50 includes first and second transceivers 210, 212, respectively, coupled to the serial interface of the communication link 130. The transceivers 210, 212 may be CAN transceivers, but are not limited to such transceivers. The transceivers 210, 212 enable any type of serial or non-serial communication via the communication link 130, including but not limited to RS-485, LIN, Vehicle Area Network (VAN), FireWire, I2C, RS-232, RS-485, Universal Serial Bus (USB), etc.

[0086] The first transceiver 210 and the second transceiver 212 can enable communication between devices (e.g., an object device 50 and a sensor 40). For example, the object device 50 can send connection parameters for the communication link 140 to the sensor 40 via the serial interface of the communication link 130, thereby enabling the sensor 40 to monitor communication between the object device 50 and the remote device 20. The sensor 40 can receive such communication via the first transceiver 210 and relay that communication to another device (e.g., another sensor 40) via the second transceiver 212.

[0087] Optionally, the object device 50 may have a communication link 130 comprising a serial interface without a high-frequency interface, or a high-frequency interface without a serial interface. The communications described herein relating to one interface, rather than the other, may be transmitted via the interface provided by the communication link 130. For example, the communication link 130 may include a high-frequency interface without a serial interface, and the communications described relating to a serial interface may be transmitted via the high-frequency interface. The high-frequency interface and / or serial interface may be wired or wireless.

[0088] The communication interface of the main controller 51 can enable any type of communication link, including any type of communication link described herein, including wired or wireless. The communication interface can enable external communication, internal communication, or both. For example, the communication interface can be coupled to the RF circuit 204 and enable communication between the antenna array 30 and one or more HF interfaces of the communication link 130.

[0089] As another example, the communication interface of the main controller 51 can enable wireless communication links with other system components in the form of a remote device 20, such as wireless communication compliant with the Wi-Fi standard or UWB, or any combination thereof. As yet another example, the communication interface of the main controller 51 may include a display and / or input interface for transmitting information to and / or receiving information from the user.

[0090] (III. Phase-based ranging) In the embodiment shown in Figure 9, tone exchange using multiple frequencies f_0, f_1, f_2, and f_3 is demonstrated, where the object device 50 is the initiator, i.e., device A, and the remote device 20 is the reflector, i.e., device B. Note that device A and / or device B may be different devices within system 100. For example, device A may be sensor 40 and device B may be remote device 20. In another example, device A may be object device 50 and device B may be sensor 40. When different frequencies are used for tone exchange, a type of channel sounding for the ranging approach is utilized.

[0091] In Figure 8, tone exchange may include device A transmitting a frequency-dependent initiator signal, device B receiving the initiator signal, device B transmitting a reflector signal based on the same frequency-dependent initiator signal, and device A receiving the reflector signal. Based on the phase characteristics of the initiator and / or reflector signals measured by device B or device A, respectively, the phase rotation of the initiator and / or reflector signals can be determined, and the distance between devices A and B can be determined.

[0092] A single tone exchange depending on frequency f_0 is shown in more detail in Figure 9 and is described in conjunction with one or more phase characteristics and associated characteristics of the tone exchange. In this example, frequency f_0 is specified as 2.4 GHz. However, the frequency may vary. At the frequency in this example, the wavelength of the signal is approximately 12.5 cm. The distance can be determined by knowing the total phase rotation of the initiator signal and reflector signal in the round trip. For example, if the total phase of a bidirectional exchange (φ_AB + φ_BA, i.e., φ_2W) is measured to be 90 degrees (1 / 4 of a full rotation), the bidirectional distance is determined by 12.5 cm * 1 / 4 + 12.5 cm * N, where N is the number of wraps (rewinds) or full rotations of the initiator signal and reflector signal.

[0093] When tone exchange is performed at a second frequency f_1 that is different from f_0, the measured phase will be different, and the wavelength will also be different due to the change in frequency. By combining the measured phase difference with the known frequency difference (f_1-f_0), it becomes possible to determine the number of wraps or complete rotations N of the initiator and reflector signals.

[0094] In the embodiment shown in Figure 9, an initial phase offset exists with respect to the timing signal. The phase offsets of device A and device B in bidirectional exchange cancel each other out when determining the bidirectional phase rotation.

[0095] In the illustrated embodiment, the initiator (device A) transmits and receives with a relative phase offset φa, and the reflector (device B) transmits and receives with a relative phase offset φb. φa is the intrinsic phase offset of the initiator, and φb is the intrinsic phase offset of the reflector. When φa and φb are 0 or the same, the unidirectional phase rotation measured at B from A is φ1W = φ1AB, and when φa and φb are 0 or the same, the unidirectional phase rotation measured at B from A is φ1W = φ1BA. However, when φa and φb are not the same, the phases measured at B and A will be different due to these offsets. This is because, when going from A to B, φa causes the transmission delay of A, and φb causes the measurement delay of B. That is, φ1ABmeasured = φ1AB + φa - φb. When moving from B to A, φb causes a transmission delay in B and φa causes a measurement delay in A, so φ1BAmeasured = φ1BA + φb - φa. Summing these together, the bidirectional rotation can be determined as follows:

number

[0096] We can see that φa and φb cancel each other out. Switching to Euler notation, the phase offset cancels out when the exponents are combined, yielding the same result. Thus, bidirectional rotation can be determined as follows:

number

[0097] The notation for determining unidirectional and bidirectional rotations may differ depending on the document parameters and the method used to conceptualize the phase. For example, the phase can be described with respect to the IQ domain, in which case I+QJ=X+Yj=Φ=cos(φ)+jsin(φ)=e -jφ Here, Φ (uppercase PHI) is the complex representation of the phase in radians, i.e., φ (lowercase RHI). The value of Φ_1AB_measured is sometimes called the reflector phase correction term (PCT) or PCT_B, and the value of Φ_1BA_measured is sometimes called PCT_A. Bidirectional rotation Φ2W = Φ1_AB_ measured · Φ1_BA_ measured.

[0098] Because the wavelength of high-frequency transmission may be short relative to the target distance being measured, the transmission may either wrap or complete a full phase rotation. Therefore, the total phase rotation, which is embodied as a total distance, cannot be directly measured from the phase of the input stage of RF circuit 204. For example, if the carrier frequency is 2.4 GHz, the phase rotation is unwound by 2π in a range of d of 12 cm. While the phase measurement at the input stage of RF circuit 204 indicates a phase within the range of 0 to 2π, the phase measurement does not necessarily directly indicate the number of phase rotation wraps.

[0099] To measure longer distances without ambiguity, two different frequencies (f0, f1) can be used at two different time points (i0, i1) to calculate two different phase rotations. Two different phase rotations can be used to measure distance. Phase-based distance determination is described in combination with two different frequencies. However, it should be understood that phase measurements at multiple frequencies (including three or more frequencies) can be used to improve the accuracy of distance determination.

[0100] As shown in Figure 8, when using two or more different frequencies (f_0, f_1) as the basis for determining distance, the initiator can perform two tone exchanges to measure the bidirectional phase rotation (φ_2w) at the two frequencies (f_0, f_1). In this example, φ_2w(f_0, d) = φ_1AB(f_0, d) + φ_1BA(f_0, d), where the phase characteristic φ_1AB(f_0, d) is measured by the initiator and the phase characteristic φ_1BA(f_0, d) is measured by the reflector. Also, φ_2w(f_1, d) = φ_1AB(f_1, d) + φ_1BA(f_1, d), where the phase characteristic φ_1AB(f_1, d) is measured by the initiator and the phase characteristic φ_1BA(f_1, d) is measured by the reflector. The difference between the two-way phase measurements, φ_2w(f_0, d) - φ_2w(f_0, d), is related to the difference in frequency and distance as follows:

number

[0101] Based on the difference in bidirectional phase measurements, the distance and time delay can be determined as follows:

number

number

[0102] Note that, given the relationship between bidirectional phase rotation, frequency, and distance, if the frequency changes while the distance remains constant, the bidirectional phase rotation (φ_2w) will unwind to zero. As a result, for multiple frequencies within a bandwidth (e.g., 2.4GHz to 2.48GHz), the bidirectional phase rotation may unwind to 0 degrees zero or more times, depending on the distance. The lap distances and multiple frequencies of round-trip, i.e., bidirectional phase rotations are shown in the illustrated embodiment in Figure 10. In Figure 10, it can be seen that for a distance of 20m, signals from 2.4GHz to 2.48GHz lap in 1MHz frequency steps. The slope of the bidirectional phase rotation may also depend on the distance. In one embodiment, the distance can be determined at least partially based on the slope and / or frequency at which the bidirectional phase rotations lap.

[0103] This disclosure is not limited to determining bidirectional phase rotation. Unidirectional phase rotation (φ_1w) can be conceptualized in a similar manner, and the distance and time delay are determined as follows:

number

number

[0104] However, it should be noted that obtaining an accurate unidirectional ranging delta between the transmit and receive phases may require the initiator and receiver to be time-synchronized. In the case of bidirectional ranging, the difference in the time references of the two devices may cancel each other out, so a lack of synchronization may not be necessary.

[0105] (IV. Sniffing / Monitoring and Phase-Based Ranging) As described herein, channel sounding can directly calculate the distance between device A and device B (e.g., a set of radios and a remote device) by measuring the quadrature signals (i.e., I-modulation and Q-modulation) between device A and device B. System 100 (e.g., a passive access system) can be configured to determine the distance between device A and device B primarily by analysis based on the phase of its modulation on the Bluetooth channel. This configuration allows one object-based device (e.g., object device 50 or sensor 40) to communicate with the remote device 20 at a time. This configuration may substantially limit the speed at which system 100 can operate in each ranging procedure between one object-based device and the remote device 20, in the absence of a sniffing or monitoring configuration. Each radio of each object-based device can perform communication with the remote device 20 in sequence, and as described herein, a vehicle, i.e., object 10, may include five to seven or more radios (e.g., object devices 50 and sensor 40). Employing such a turn-by-turn method for communication between the object device and the remote device 20 may increase the time it takes for the system 100 to determine its position and perform actions such as unlocking a door.

[0106] By providing temporal consistency between object-based devices, one object device or sensor can monitor tone exchanges between another object device or sensor and the remote device 20, making it possible to determine the distance without directly exchanging tones with the remote device 20. However, the underlying communication standard for tone exchange (e.g., the BTLE standard) may not support temporal consistency.

[0107] In one embodiment, all object devices 50 and sensors 40 (e.g., all radios) of system 100 can measure the distance to the remote device 20 when only one of the devices (e.g., one radio) is communicating directly with the remote device 20. In a further embodiment, these radios may not need to be compatible with one another.

[0108] In one embodiment, system 100 provides selective access to object 10 (such as a vehicle). In this case, each radio in system 100 is configured to communicate directly with a remote device 20, of which one can be selected, and transmits quadrature-modulated radio frequency energy across a series of radio frequency channels. This allows the radios (operating as active reflectors) and the remote device 20 (operating as initiators) to receive phase information from each other, and the other radios (operating as passive sniffing reflectors) to sniff the channel sounding procedure. By combining the sniffed phase measurements with the local oscillator (LO) difference between the initiator and the reflectors, system 100 can recover the output, which is the phase difference between the initiator and the active reflectors and sniffing reflectors, from the measured phase information of the reflectors.

[0109] In one embodiment, a method is provided for performing motion compensation to reduce the influence of the movement of the remote device 20 on the measured phase information measured by the active reflector and sniffing reflector of system 100. Each radio can measure phase information indicating the distance to the remote device 20. The motion compensation method may include comparing the nonlinear shift of the phase difference between the reflectors to determine and / or remove the velocity component in the measured data and improve the estimation of the distance measurement accuracy.

[0110] In one embodiment, a method is provided for performing multipath mitigation to reduce the potential influence of a complex environment on the phase information measured by the reflector of system 100. System 100 can be configured to perform the step of synthesizing sparse two-dimensional apertures based on simultaneous phase information measured by an active reflector and a sniffing reflector. System 100 can also be configured to perform the step of reconstructing the synthesized aperture image inside and around object 10 and removing multipath-induced artifacts to more accurately position the remote device 20.

[0111] Figure 11 shows a typical part of system 100, consisting of a remote device 20 and first and second object-based devices (e.g., object device 50 or sensor 40) arranged to communicate with the remote device 20. For illustrative purposes, the object-based devices are designated as anchors A and B, and each of these devices can act as a reflector in phase distance analysis (e.g., channel sounding distance determination).

[0112] For each anchor A and B, the distance can be determined as a function of the phase measurement of the communication. As shown in the figure, θIA and θIB correspond to the phase measurements of anchor A and anchor B, respectively. Based on these measurements, θAB between anchor A and anchor B can be determined, and the clock offset of θAB can also be determined. θIA may correspond to the unidirectional phase rotation φ1ABmesured described herein.

[0113] A method for determining the baseline θAB is shown in Figure 12 and is generally designated as 1000. Method 1000 involves performing a phase ranging procedure between the remote device 20 and anchor A, in which θIA can be determined and a zero clock offset reference can be established. Step 1010. Method 1000 can then begin acquiring a baseline value (e.g., a baseline clock offset between anchor B and the remote device 20). Method 1000 may be performed at startup, such as when the system 100 is powered on.

[0114] Method 1000 may also include a phase-distancing procedure performed by anchor B. Step 1012. Specifically, anchor B can monitor the phase-distancing procedure between the remote device 20 and anchor A (e.g., sniffing θ1A at anchor B). Based on the known θIA and the sniffed θIA determined at anchor B by monitoring the phase-distancing procedure between the remote device 20 and anchor A, θAB including clock ambiguity may be determined. Step 1014.

[0115] The clock offset between anchor B (i.e., the sniffer) and remote device 20 (i.e., the initiator) can be determined by aligning the known θIA (determined as a phase distance procedure between anchor A and remote device 20) with the sniffed θIA (determined by anchor B with respect to the phase distance procedure between anchor A and remote device 20). The rotation required to align these two may correspond to the relative clock offset between the sniffing device (anchor B) and the initiator (remote device 20). Step 1016.

[0116] When sniffing θIA at anchor B, no direct information about θAB exists. However, the relative clock offset between anchor A and anchor B can be derived by channel sounding 1A and sniffing the transmissions of remote device 20 and anchor A (e.g., sniffing the transmissions of I and A). In step 1016, the relative clock offset of anchor B with respect to anchor A can be generated by comparing the known offset of the channel sounding procedure between remote device 20 and anchor B with the derived clock offset between anchor B and remote device 20.

[0117] Method 1000 may include receiving the clock offset between anchor B and remote device 20. Step 1018. Method 1000 may also include combining the active clock offset with the relative offset between anchor B and remote device 20 to generate a clock offset between anchor B and anchor A. Step 1020.

[0118] (1) Based on the clock offset determined between anchor B and anchor A in step 1020 and (2) θAB determined by anchor B by sniffing the channel sounding procedure between the remote device 20 and anchor A in step 1014, a clock-unambiguous θAB distance between anchor A and anchor B can be determined by channel reconstruction. Many channel reconstruction methods have been considered, but one embodiment, namely step 3014 in Figure 14, is described below. Step 1022.

[0119] A method for determining θAB from the sniffing procedure and the baseline is shown in Figure 13 and is generally specified as 2000. Thus, the baseline of θAB determined by method 1000 can be repeatedly updated to take into account environmental changes, the movement of the remote device 20, and fading changes.

[0120] Method 2000 includes anchor B (1) sniffing θIA for a phase distance measurement procedure between anchor A and remote device 20, and (2) determining θAB based on an active distance measurement procedure between anchor B and remote device 20. Step 2010.

[0121] Method 2000 includes receiving the clock offset of θIB. Step 2012.

[0122] Method 2000 includes determining the relative rotation of θAB with respect to the previous baseline determination of θAB determined in Method 1000, and determining the BA clock offset with respect to the current procedure. Step 2014.

[0123] Method 2000 may include determining θIA by combining the BA clock offset with the θAB and IB offsets. Step 2016.

[0124] A method for actively determining θAB between anchor A and anchor B is shown in Figure 15 and is generally designated as 6000. Method 6000 includes assigning the roles of initiator and reflector to the devices of anchor A and anchor B, respectively. Step 6010. A phase measurement procedure may be performed between the anchor A device and the anchor B device. Step 6012. A phase reconstruction is performed based on the phase distance measurement procedure in step 6012, and θAB between anchor A and anchor B can be determined. Step 6014. This θAB can be used as a baseline for future distance measurement procedures and methods, including a method that includes sniffing a distance measurement procedure between the other of anchor A or anchor B and the remote device 20 in either anchor A or anchor B.

[0125] Passive sniffing by the method described herein can be implemented in various ways. In one embodiment, the RF circuit 204 of the object device 50 or sensor 40 may be based on a Bluetooth radio, for example, a Bluetooth Low Energy 5.3 compliant radio that supports multiple simultaneous secure connections. The RF circuit 204 in this configuration can be configured to sniff broadcasts from both the initiator (e.g., remote device 20) and the reflector (e.g., anchor A). Power-on / power-off / mode change transitions of the radio can be ordered in hardware. The timing of all or some signals is reprogrammable, and high / low times of individual signals can be used in both the receive and transmit sequences. Thus, the transmit control entry can be translated into a receive block control line at the appropriate timing, and the "transmit" mode can be commanded in place of the receive.

[0126] This hardware adjustment to RF circuit 204 may introduce one or more limitations, but there are various workarounds.

[0127] 1. The controller does not need to drive some receive-related hardware control signals in transmit mode. This problem can be overcome by manually switching the control signals using override registers that are available at the appropriate time during the transition.

[0128] 2. There may be no override or control mechanism to provide the correct reflector access address. To synchronize the sniffing anchor to the active anchor oscillator during the sniffing procedure, the firmware can instead collect the T_FM tone of each mode 0 broadcast from the active anchor and calculate the subsequent CFO value. This approach may have the added advantage of being more accurate than hardware CFO estimation. The lack of access address control may limit the hardware's utilization of timing information in mode 1 and mode 3 steps.

[0129] There are also several firmware implementation changes that may be provided for RF circuit 204.

[0130] • TQI calculation of sniffed tone / phase does not need to be implemented.

[0131] The data processing of the sniffing method described herein will be further explained according to the following definitions and formulas.

[0132] Let's begin with definitions of what standard PCT and sniffing PCT measure.

number

[0133] It is worth noting that the relationship between LO phase difference can be considered as follows.

number

[0134] The propagation channel between the initiator and the reflector is symmetric, that is, (θ Channel(init→refl) ==θ Channel(refl→init) Assuming that ), the following equation is derived.

number

[0135] This quantity 2θ Channel(init→refl) This may be useful in determining distance. After dividing by 2, this quantity can represent the phase of a unidirectional channel for each tone, with a phase ambiguity of ±π. θ Channel(init→refl) The ambiguity in Δθ is that the opposite ambiguity of minus plus π can appear in each tone. LO(init→refl) This may be related.

[0136] The quantity Δθ ​​derived from the active initiator and reflector. LO(init→refl)and the sniffed PCT, θ sniffer(init→refl) and θ sniffer(refl→init) are given, the phase information of the target in θ Channel(init→refl) can be elucidated.

Number

[0137] Simplifying this gives the following.

Number

[0138] Based on this simplification, by observing the phases of the tones of the initiator and the reflector and combining the observation results with the information obtained from the active ranging device, the difference for each channel between θ sniffer(init→refl) and θ sniffer(refl→init) can be noted.

[0139] In the round-robin ranging procedure, the "sniffer" anchor is the active anchor, and when calculating θ Channel(refl→sniffer) θ Channel(init→sniffer) can be directly measured. Assuming the environment does not change, the θ Channel(refl→sniffer) of a specific active anchor is likely not to change, and θ Channel(init→sniffer) can be calculated in subsequent sniffing ranging procedures.

[0140] In one aspect, using the information regarding the PLL states at both the active anchor and the sniffing anchor, the system 100 can determine and compensate for the relative phase for each frequency. The measurement and compensation of the CFO are accurate and precise enough to reduce θ Channel(init→sniffer) to a constant within a fairly small error term range over the procedure. This can make θ Channel(init→sniffer) interchangeable with θ LO(refl→init) As a result, θ Channel(init→sniffer) can be obtained from the active initiator and reflector θ LO(refl→init)It can be calculated directly by subtracting terms.

number

[0141] The phase reconstruction method is shown in Figure 14 and is generally specified in 3000. This method may include acquiring an initiator PCT and a reflector PCT. Step 3008. These PCTs may correspond to the unidirectional PCTs described herein, which involve clock ambiguity.

[0142] Method 3000 may include utilizing a reflector PCT and combining it with an initiator PCT to determine the clock-related phase components. Step 3010. The clock components over time can be unwrapped to determine the residual frequency offset. Step 3012. Method 3000 may include identifying the midpoint of the unwrapped clock result to determine the clock offset, combining the clock offset with the initiator PCT, and combining the utilization offset with the reflector PCT. Steps 3014, 3016.

[0143] The initiator PCT and reflector PCT may be averaged. Step 3018. The averaging procedure serves to reduce noise in the measurements. While averaging is considered, other noise reduction techniques may be used depending on the embodiment.

[0144] Method 3000 may also include PBR sniffing, which is an input to the above-described system and method for determining the distance to the passive anchor. See, for example, step 1018 in Figure 12. Step 3020.

[0145] Figure 16 provides a visual aid to facilitate understanding the recovery of the local oscillator offset.

[0146] (V. Motion compensation) In one embodiment, the system 100 is configured to include a sniffing reflector for measuring simultaneous phase differences and may further be configured to perform motion compensation to mitigate the detrimental effects of the mobile device's motion on the measured phase data. The method of performing motion compensation can suppress the influence of the remote device 20's motion on the measured phase information measured by the system 100's active reflector and sniffing reflector. Each radio can measure phase information indicating the distance to the remote device 20.

[0147] The sniffed phase difference may include a nonlinear shift as a function of frequency (or Bluetooth channel), and this nonlinear shift may indicate the velocity of a mobile device moving directly toward or away from the sniffing reflector. Motion compensation methods may include comparing the nonlinear shift of the phase difference between reflectors to determine and / or remove the velocity component of the measurement data to improve estimation of ranging accuracy.

[0148] As shown in Figure 17, a portion of the system 100 is illustrated using reflector A, initiator B, and sniffing reflector B for illustrative purposes. Reflector A may correspond to object device 50, initiator B to remote device 20, and sniffing reflector C to sensor 40. Note that the devices associated with reflector A, initiator B, and sniffing reflector B may vary depending on the application and circumstances.

[0149] In Figure 17, the remote device 20 is moving toward reflector A and tangentially toward sniffing reflector B. The phase D1 between reflector A and initiator B may include a "blue shift" effect due to the velocity of initiator B moving toward reflector A. The phase D2 between initiator B and sniffing reflector C may be observed as a linear response because initiator B is moving tangentially toward sniffing reflector C. The sniffed phase difference provides an index of the different velocities observed, and by using multiple sniffing anchors, system 100 can estimate the velocity vector based on the sniffed phase difference.

[0150] A motion compensation method according to one embodiment is shown in Figure 18 and is generally designated as 4000. Method 4000 includes measuring the phase between the active reflector and the initiator. Step 4010. Method 4000 may include sniffing the phase between the active reflector and the initiator for all sniffing reflectors (e.g., multiple sniffing reflectors). Step 4012. System 100 can model the linearity of the phase measurements for each reflector and compare the modeled linearity of the phase measurements for all reflectors. Steps 4014 and 4016.

[0151] Method 4000 may include mapping nonlinearity to known relative positions of the sniffing reflector. Step 4018. An estimate of the velocity vector of the remote device 20, for example, initiator B, may be determined. Step 4020.

[0152] This method may include subtracting the effect of the estimated velocity vector from the phase measurement of each reflector. Step 4022. The distance between the reflector and the mobile device may be determined based on the phase measurement and the subtraction result. Step 4024.

[0153] (VI. Multipath Mitigation) In one embodiment, a method may be provided for performing multipath mitigation to reduce the potential influence of a complex environment on the phase information measured by the reflector of system 100. System 100 may be configured to perform the step of synthesizing sparse two-dimensional apertures based on simultaneous phase information measured by an active reflector and a sniffing reflector. System 100 may be configured to perform the step of reconstructing a synthesized aperture image inside and around an object 10 (e.g., a vehicle). The synthesized image may include two-dimensional information about both actual sources and sources induced by multipath. Algorithms for generating the image include filtered back projection, interferometric imaging, FFT, and CLEAN. Furthermore, system 100 may also be configured to isolate and remove multipath-induced artifacts to more accurately position the remote device 20.

[0154] A method for multipath mitigation according to one embodiment is shown in Figure 19 and is generally designated as 5000. Method 5000 includes measuring the phase between the active reflector and the initiator. Step 5010. Method 5000 may include sniffing the phase between the active reflector and the initiator for all sniffing reflectors (e.g., multiple sniffing reflectors). Step 5012.

[0155] One aspect obtainable by method 5000 may include synthesizing the apertures by calculating a K-space mapping of the phase measurements of all reflectors. This may include performing a transformation of the wireless IQ data (e.g., BLE CS IQ data) to a common coordinate system of all reflectors. Step 5014.

[0156] Method 5000 may include converting a K-space map to a 2D spatial image and identifying multipath artifacts within the 2D image. Steps 5016, 5018.

[0157] In one embodiment, method 5000 may include removing multipath artifacts from a 2D image. Step 5020. In the artifact-free 2D image, the location of a mobile device may be estimated. Step 5022. Method 5000 may also include identifying other features in the 2D image, such as a person or a moving object. Step 5024.

[0158] Terms indicating direction, such as "vertical," "horizontal," "upper," "lower," "upward," "downward," "inward," "outward," and "outward," are used to assist in describing the invention based on the directions of the illustrated embodiments. The use of directional terms should not be construed as limiting the invention to any particular direction.

[0159] The above description describes current embodiments of the present invention. Various modifications and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, and the claims should be interpreted in accordance with the principles of patent law, including the doctrine of equivalents. This disclosure is presented for illustrative purposes only and should not be interpreted as an exhaustive description of all embodiments of the invention, nor should the claims be interpreted as limiting the claims to specific elements illustrated or described in relation to these embodiments. For example, but not limited thereto, individual elements of the described invention may be replaced by alternative elements that provide substantially similar functionality or appropriate operation. This includes, for example, currently known alternative elements, such as those that may now be known to those skilled in the art, and alternative elements that may be developed in the future, such as those that may be recognized as alternatives by those skilled in the art at the time of development. Furthermore, the disclosed embodiments include several features that are described in relation to each other and may collectively provide a set of benefits. The present invention is not limited to embodiments that include all of these features or embodiments that provide all of the benefits described, except as expressly stated in the claims. For example, any reference to a singular claim element using an article such as "a," "an," "the," or "said" should not be interpreted as limiting that element to the singular form. Any reference to a claim element that says "at least one of X, Y, and Z" means that it includes any one of X, Y, or Z individually, and also includes any combination of X, Y, and Z, such as X and Y and Z, X and Y, X and Z, and Y and Z.

Claims

1. A system for determining the distance between a remote device and an object, A first device including a first antenna system positioned in a fixed location relative to an object and configured to receive a first tone signal from a remote device and / or transmit a first tone signal to a remote device, A control system configured to determine the first and second phase characteristics of a first tone signal at a first frequency and a second frequency. The first and second phase characteristics indicate the first phase rotation of the first tone signal between the first device and the remote device. The control system is operable to determine a first distance between a first device and a remote device based on a first phase rotation of a first tone signal. A second device including a second antenna system positioned in a fixed location relative to an object and configured to monitor a first tone signal between the first device and a remote device, and The control system is configured to determine the second phase rotation of the first tone signal, which is monitored by the second device. The control system is configured to determine the second device clock offset between the second device and the remote device based on a first phase rotation and a second phase rotation.

2. The system according to claim 1, wherein the control system is configured to determine the relative clock offset between the first device and the second device based on the second device clock offset.

3. The system according to claim 2, wherein the control system is configured to determine a third phase rotation between a first device and a second device without using clock ambiguity based on relative clock offset and ambiguous phase rotation between a first device and a second device determined based on a monitored first tone signal.

4. The second device is configured to receive a second tone signal from the remote device and / or to transmit a second tone signal to the remote device. The first device is configured to monitor the second tone signal between the second device and the remote device. The control system is configured to determine the third phase rotation of the second tone signal between the second device and the remote device. The system according to claim 2, wherein the control system is configured to determine a fourth phase rotation between the remote device and the first device based on (1) a second tone signal monitored by the first device and (2) a second device clock offset between the second device and the remote device.

5. The system according to any one of claims 1 to 4, wherein the first frequency and the second frequency are different.

6. The system according to any one of claims 1 to 5, wherein the control system is provided in the first device, and the first device is capable of operating as an initiator.

7. The system according to claim 6, wherein the remote device can operate as a reflector.

8. The system according to claim 6, wherein the control system is provided as a first control system and a second control system, which are separately arranged within the first device and the second device.

9. The system according to any one of claims 1 to 8, wherein the remote device can operate as an initiator and the first device can operate as a reflector.

10. The control system is operable to determine the third phase characteristic of the first tone signal at the third frequency. The system according to claim 9, wherein the third phase characteristic indicates a first phase rotation of the first tone signal between the first device and the remote device.

11. The system according to claim 10, wherein the first frequency, the second frequency, and the third frequency are different from each other.

12. The first tone signal is the initiator tone signal. The system according to any one of claims 1 to 11, wherein the first phase characteristic and the second phase characteristic are determined by the remote device with respect to the reception of an initiator tone signal from the first device.

13. The first tone signal is a reflector tone signal. The system according to any one of claims 1 to 12, wherein the first phase measurement and the second phase characteristic are determined by the first device with respect to the reception of a reflector tone signal from a remote device.

14. The first phase characteristic of the reflector tone signal shows the bidirectional phase rotation of the initiator tone signal and the reflector tone signal at the first frequency. The system according to claim 13, wherein the second phase characteristic of the reflector tone signal indicates a bidirectional phase rotation between the initiator tone signal and the reflector tone signal at a second frequency.

15. The system according to claim 14, wherein the control system is operable to determine a first distance based on (1) the difference between a first phase characteristic and a second phase characteristic, and (2) the difference between a first frequency and a second frequency.

16. The system according to any one of claims 1 to 15, wherein the control system is configured to compensate for the movement of the remote device relative to the first device.

17. The system according to claim 16, wherein the control system is configured to reduce the influence of the estimated velocity vector from at least one of the first phase rotation and the second phase rotation.

18. The control system is configured to compensate for multi-phase effects in the environment, according to any one of claims 1 to 17.

19. The system according to any one of claims 1 to 18, wherein the control system is configured to generate a K-space mapping of phase rotations and to identify multipath artifacts based on the K-space mapping.

20. The system according to any one of claims 1 to 19, wherein the remote device can operate as a reflector and the first device can operate as an initiator.

21. The system according to any one of claims 1 to 20, wherein the second device is configured to receive a second tone signal from the first device and / or transmit a second tone signal to the first device.

22. The system according to claim 21, wherein the control system is configured to determine a third phase characteristic based on a second tone signal.

23. The system according to claim 22, wherein the control system is configured to repeatedly update the second device clock offset based on a second tone signal.

24. A method for determining the position of a remote device relative to a first device, Transmitting an initiator signal between the remote device and the first device according to the first frequency. Transmitting an initiator signal between the remote device and the first device according to the second frequency. To determine the first phase characteristic of the initiator signal at the first frequency and the second phase characteristic of the initiator at the second frequency. The first and second characteristics indicate the first phase rotation of the initiator signal between the first device and the remote device. In the second device, the initiator signal between the remote device and the first device is monitored. Determining the second phase rotation of the initiator signal monitored by the second device, Based on the first phase rotation and the second phase rotation, the second device clock offset between the second device and the remote device is determined, and A method comprising determining the position of a remote device based on at least a first phase rotation.

25. The method according to claim 24, comprising determining the relative clock offset between the first device and the second device based on the second device clock offset.

26. The method according to claim 25, comprising determining a third phase rotation between a first device and a second device without using clock ambiguity based on relative clock offset and ambiguous phase rotation between a first device and a second device determined based on a monitored first tone signal.

27. With respect to the second device, it receives a second tone signal from the remote device and / or transmits a second tone signal to the remote device. In the first device, the second tone signal between the second device and the remote device is monitored. To determine the third phase rotation of the second tone signal between the second device and the remote device, and The method according to any one of claims 24 to 26, comprising: (1) a second tone signal monitored by the first device; and (2) determining a fourth phase rotation between the remote device and the first device based on a second device clock offset between the second device and the remote device.

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