Agile jammer detection and mitigation for multi-carrier phase ranging systems

Abstract

A multicarrier phase ranging system and method is provided. Generally, the method includes performing a handshake between a first transceiver and a second transceiver to negotiate a list of channels and a start time for a multicarrier phase ranging process. The process includes exchanging constant tones (CTs) between the first transceiver and the second transceiver in a first period on a first channel in a first cycle and processing the received CTs in the first transceiver and the second transceiver to measure a phase difference between the received CTs and a reference signal. Interference in the received CTs is checked using software or firmware in one or both of the first transceiver and the second transceiver. If no interference is detected, the first transceiver and the second transceiver switch to another channel and exchange CTs at a next period. If interference is detected, at least one channel is skipped for at least a subsequent period.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 63 / 033,740, filed June 2, 2020, pursuant to Section 119(e) of the U.S. Patent Act, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure generally relates to wireless systems, and more specifically to wireless devices including multi-carrier phase-based ranging systems, and methods for operating the wireless devices to detect and mitigate the effects of interference in such systems. Background Technology

[0004] The use of wireless networks (e.g., Bluetooth (BT), Bluetooth Low Energy (BLE), and various IEEE 802.15.4 protocols) to wirelessly connect devices, security systems, entertainment devices, appliances, and communication or computing devices, including those with radio frequency identification (RFID) tags, has grown exponentially. In many applications, measuring the distance between devices in a wireless network is necessary. For example, proximity-based access tags, such as passive keyless entry systems (PKES), are widely used to unlock, lock, or start vehicles; contactless smart cards are used in cashless payment systems; transponders are used in parking and highway toll collection; and RFID tags are commonly used in electronic passports for personnel tracking or inventory control. Several ranging techniques have been developed to measure the distance between devices in a wireless network using wireless signals. One of the most promising ranging techniques is phase ranging, in which the distance between two wireless devices is measured by determining the phase difference between a constant tone (CT) or continuous wave carrier signal transmitted by the initiating device or party and received by the reflecting device or party, and a reference signal generated by a local oscillator in the reflecting party. Typically, the phase ranging process begins with a handshake between the two devices, through which they agree on ranging parameters (e.g., the channel or frequency to use and the time to begin the ranging process). The initiating party then transmits a CT toward the reflecting party. CTs can be transmitted individually or with packets. Unlike CTs (unmodulated carriers), packets are transmitted using modulated carriers. Packets may include, for example, constant tone spread (CTE) packets used in the angle of arrival (AoA) and angle of departure (AoD) measurements used in direction-finding processes. Upon receiving a signal, the reflecting party locks or synchronizes its local oscillator to the received signal, measures the phase difference between the received signal and the reference signal, and transmits a new CT toward the initiating party. The operating mode has been changed to become the initiator of the receiver, measuring the phase difference between the received signal and the reference signal. The reflector then sends the result back to the initiator. The initiator receives the phase measurement result from the reflector and combines it with its own phase measurement to estimate the distance between the initiator and the reflector, which is proportional to the incremental phase of the received signal and the reflector's reference signal.

[0005] Although phase ranging can theoretically be performed using a single frequency or a narrow frequency range, to resolve half-wavelength ambiguity, the two devices measure the phase shift at two separate carrier frequencies. Furthermore, to mitigate problems caused by multipath fading, practical techniques using phase ranging typically involve transmitting multiple CT signals on multiple carrier frequencies or channels (typically up to 80 channels with a 1 MHz bandwidth). Such a system is called a multi-carrier phase ranging system. In a multi-carrier phase ranging system, the initiator and reflector exchange at least two CT signals at two carrier frequencies or channels f1 and f2, where the spacing between the initiator and reflector is proportional to the incremental phase and the incremental carrier f2-f1. Figure 1A and Figure 1B The image shows a sample of a multi-carrier phase-based ranging solution, in which... Figure 1A It is a message sequence diagram illustrating one cycle of the multi-carrier phase ranging process, and Figure 1B It is shown Figure 1A The time and frequency diagram of the process.

[0006] refer to Figure 1A The initiator (device A) and the reflector (device B) perform a handshake and negotiation operation 102, in which the devices discuss parameters of the ranging process (e.g., the channel or frequency to be used, the duration for which each CT will be transmitted (t)). L The time for starting the ranging process is agreed upon. Next, the first cycle of the multi-carrier phase ranging process 104 begins at epoch or time slot t1, where the initiator (device A, which is also...) is... Figure 1B The box marked A indicates that at the first frequency f1, at a length t L ( Figure 1B (as shown in the image) towards the reflecting direction B ( Figure 1B In box B) send the first CT (by Figure 1A (Indicated by arrow 106). Upon receiving a CT, the reflecting party B locks or synchronizes its local oscillator to the received signal, performs phase measurement, and sends the new CT back to the initiating party A, as shown in the image. Figure 1A Arrow 108 indicates this. During this time period, the initiator (device A) has changed its operating mode to act as a receiver, then receives the CT from the reflector and measures the phase difference between the received signal and the reference signal. Then, in n time slots (t1-t... n For n frequencies or channels (f1-f) n Repeat these steps. Afterward, the initiator and the reflector exchange phase and phase measurement results 110, and estimate the distance between the initiator and the reflector.

[0007] Multi-carrier phase ranging using Bluetooth Low Energy (BLE) and 802.15.4 radio can measure the distance between the initiating and reflecting devices with sub-meter accuracy. However, this has become problematic because the devices need to coexist with interference in the 2.4 GHz Industrial, Scientific, and Medical (ISM) band, which is becoming increasingly congested due to other wireless technologies such as Wi-Fi, regular Bluetooth, Bluetooth LE, ZigBee, and Threading. One way to address this is through conventional frequency adaptation, such as... Figure 2A and Figure 2B As shown in the diagram. Similar to the multi-carrier phase ranging process described above, the frequency-adaptive process begins with the initiator (device A) and the reflector (device B) performing a handshake and negotiation operation 202. Next, a ranging cycle (cycle_i 204) is executed, during which interference 206 exists (in... Figure 2B The middle part is shown as the frequency f i and f i+1 (occurring at point), and exchange phase results 208. At the end of cycle_i 204, after processing and exchanging phase results, the two devices (initiator A and reflector B) decide to interfere with the channel (f i and f i+1 The interfering channel is blacklisted and removed from the list of switching channels to be used in subsequent ranging cycles. This blacklist can be permanent or it can be for a predetermined number of ranging cycles, after which the previously interfering channel can be whitelisted for use in subsequent cycles. Figure 2A As shown, to update the switching channel list for the next cycle, a new handshake and negotiation 210 or higher is required between devices via the link layer (LL) after each ranging cycle. Note that while the frequency adaptive method described above is not entirely satisfactory, the decision to blacklist interfering channels is made after analyzing the entire phase measurement result exchange, thus compromising the results for the entire ranging cycle. Furthermore, because interfering channels are permanently blacklisted or at least blacklisted for multiple ranging cycles, the accuracy of the multi-carrier phase ranging process is limited, thus negating the advantage of using the entire ISM bandwidth.

[0008] Therefore, there is a need for wireless systems or devices that include multi-carrier phase-based ranging systems, as well as methods for operating such wireless systems or devices to detect and mitigate the effects of interference in such systems without substantially affecting the cost, complexity, or performance of the wireless devices. Summary of the Invention

[0009] A multicarrier phase ranging system and a method for operating the system to detect and mitigate interference are provided. Typically, the method includes: performing a handshake between an initiating device (initiator) and a reflecting device (reflector) to negotiate a list of channels and a start time for the multicarrier phase ranging process. The process includes: exchanging constant tone (CT) signals between the initiator and reflector on the channels during a period, and locally processing in-phase and quadrature (IQ) samples of the received CTs in both the initiator and reflector. Interference is checked for in the IQ samples using software or hardware from one or both of the initiator and reflector. If no interference is detected, the initiator and reflector switch to another channel and exchange CTs in the next period. If interference is detected, at least one channel is skipped for at least the next period. In some instances, based on the properties of the detected interference (e.g., the intensity of the interference, the length of the interference packets, the repetition of the interference packets in the time domain, and the bandwidth of the interference signal in the frequency domain), multiple (n) subsequent channels in the list of channels are skipped for the next n periods.

[0010] Typically, the method further includes checking whether the most recent channel on which the CT was exchanged is the last or final channel in the list of channels. If the most recent exchange of the CT was performed on the last or final channel in the list of channels, the cycle is completed, and phase measurement results are exchanged between the initiator and the reflector. Subsequent cycles of the multicarrier phase ranging process are then performed. In one embodiment, subsequent cycles are performed without skipping any channels based on interference detected in the first or previous cycle (cycle_i). Alternatively, the method may include skipping any channel for multiple (n) subsequent cycles based on interference detected in the first or previous cycle, but not permanently skipping the channel, i.e., blacklisting the interfering channel.

[0011] Other features and advantages of embodiments of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. Note that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to those skilled in the art based on the teachings contained herein. Attached Figure Description

[0012] Embodiments of the invention will now be described by way of example only, with reference to the accompanying schematic diagrams, in which corresponding reference numerals indicate corresponding parts. Furthermore, the accompanying drawings, which are incorporated herein and form a part of this specification, illustrate embodiments of the invention and, together with the description, further serve to explain the principles of the invention and enable those skilled in the art(s) to make and use the invention.

[0013] Figure 1A This is a message sequence diagram illustrating the multicarrier phase ranging process performed on n channels;

[0014] Figure 1B It is shown Figure 1A The time and frequency diagram of the phase ranging process;

[0015] Figure 2A This is a three-cycle message sequence diagram illustrating a conventional method for detecting and mitigating interference during multi-carrier phase ranging.

[0016] Figure 2B yes Figure 2A The time and frequency diagram of the phase ranging process;

[0017] Figure 3 It is a time and frequency plot of a single cycle of an agile multicarrier phase ranging process using linear channel switching, during which interference is detected at one or more channels and the affected channel is temporarily skipped without permanently blacklisting it.

[0018] Figure 4 An algorithm is described in which a first wireless transceiver or ranging device or a second wireless transceiver makes a local decision to temporarily skip multiple next constant tone exchanges in multiple next periods.

[0019] Figure 5 It is a message sequence diagram of a single cycle of an agile multicarrier phase ranging process, which shows that the initiating ranging device or the reflecting ranging device makes local decisions at each frequency to exchange constant tone for the next period and / or skip constant tone exchange for multiple subsequent channels.

[0020] Figure 6 This is a flowchart of a method for performing agile multi-carrier phase ranging procedures;

[0021] Figure 7 This is another message sequence diagram of a single cycle of the agile multicarrier phase ranging process, which shows that, depending on the properties of the detected interference, the initiating ranging device or the reflecting ranging device will decide whether to skip constant tone switching for more than one period and / or more than one channel.

[0022] Figure 8 It is a time and frequency diagram showing the agile multi-carrier phase ranging process over three cycles, in which two channels are affected by interference in the first and third cycles;

[0023] Figure 9It is a three-cycle message sequence diagram illustrating the agile multi-carrier phase ranging process, in which at each channel and at each tone exchange, the initiating ranging device or the reflecting ranging device will decide whether to exchange a constant tone or remain idle and skip the tone exchange;

[0024] Figure 10 This is a time and frequency plot of a single cycle of an agile multicarrier phase ranging process using pseudo-random channel switching, during which interference is detected at one or more channels and the affected channels are temporarily skipped;

[0025] Figure 11 It is shown Figure 10 A sequence of messages for one cycle of the agile phase ranging process;

[0026] Figure 12 This is a schematic block diagram illustrating a system comprising multiple multi-frequency transceivers or multi-channel transceivers, for which agile multi-carrier phase ranging is useful; and

[0027] Figure 13 This is a schematic block diagram illustrating an embodiment of an architecture that can be implemented in one or both of a ranging device for executing algorithms and making local decisions to switch constant tones or skip tone switching for subsequent channels(multiple) and / or periods(multiple). Detailed Implementation

[0028] Disclosed are wireless networks or systems including wireless devices with agile multi-carrier phase ranging, and methods for operating such wireless networks or systems to detect and mitigate interference to provide high-accuracy distance measurement (HADM). The wireless devices and agile multi-carrier phase ranging methods disclosed herein are particularly useful, or particularly useful in conjunction with, wireless networks using Bluetooth (BT), Bluetooth Low Energy (BLE), various IEEE 802.15.4, and WiFi protocols, in which it is desirable to measure the distance or gap between a first wireless device and a second wireless device to improve the accuracy of signals transmitted between the devices and / or reduce power consumption. Such devices may include, for example, proximity-based access tags such as passive keyless entry systems (PKES) widely used for unlocking, locking, or starting vehicles; contactless smart cards used in cashless payment systems; transponders used in parking and highway toll collection; and radio frequency identification (RFID) tags commonly used in electronic passports and for personnel tracking or inventory control.

[0029] In the following description, several specific details are set forth for purposes of explanation in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without these specific details. In other instances, well-known structures and techniques have not been shown in detail or illustrated in block diagram form to avoid unnecessarily obscuring the understanding of this specification.

[0030] References to "an embodiment" or "embodiment" in the specification indicate that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. The phrase "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. As used herein, the term "coupling" can include both direct electrical connection of two or more components or elements and indirect connection of two or more components or elements via one or more intermediate components.

[0031] A fast multi-carrier phase ranging process will now be described, wherein interference is detected at one or more channels during a period of the process, and the affected channel is temporarily skipped without permanently blacklisting the interfering channel for all time slots or periods in that period or subsequent periods, thereby maximizing the availability of channels used for phase ranging (especially in the frequently used 2.4 GHz Industrial, Scientific, and Medical (ISM) band). “Period” refers to the time or period during which a communication event occurs. For example, for phase ranging purposes, constant tone (CT) is exchanged between a first wireless device and a second wireless device via a channel. “CT” represents an unmodulated continuous wave carrier signal at the channel frequency. “Subsequently” means occurring later in time or later on the negotiated list of channels, not necessarily immediately following or after an earlier time or channel.

[0032] Typically, this method includes performing a handshake between the initiating wireless device or transceiver (initiator) and the reflecting wireless device (reflector) to negotiate the list of channels and the start time for the multi-carrier phase ranging process. This process includes: [f...] i ) on the period (t) iIn this process, the phase difference (CT) is exchanged between the initiator and the reflector; the phase difference between the received CT and the signal from the local oscillator (LO) in each device is measured; and in-phase and quadrature (IQ) samples of the received CT are processed locally in both the initiator and the reflector. Optionally, the agile multicarrier phase ranging process may also include exchanging packets between the initiator and the reflector before or after exchanging CTs. The exchanged packets may be the same as or similar to the Constant Tone Extended (CTE) packets used in Bluetooth direction finding to find the angle of arrival (AoA) or departure angle (AoD). Interference in the IQ samples is checked using software and / or hardware in one or both of the initiator and the reflector. If no interference is detected, the initiator and the reflector switch to the subsequent channel (f i+1 ), and in the next period (t i+1 The CT is switched in the middle. If interference is detected, the device that detected the interference communicates with another device or notifies another device by signaling, and skips at least one subsequent channel for at least the next period.

[0033] Figure 3 This is a time and frequency diagram illustrating an exemplary embodiment of a single cycle (cycle_i) of agile multi-carrier phase ranging process, where channel f i and f i+1 Affected by interference 300. (Reference) Figure 3 Cycle_i begins at the first period t1, where the initiator (device A, which is also indicated by a box labeled A) operates on the first channel or frequency (f1) for a length t. L Oriented towards the reflector (device B, which is also composed of) Figure 3 The box marked B indicates that the CT is being sent. The reflecting side synchronizes its local oscillator (LO) to the received signal, measures the phase difference between the received CT and the signal from the LO, and sends the CT back to the initiator. During this time, the initiator (device A) has changed its operating mode to act as a receiver, then receives the reflected signal, synchronizes it with its LO, and measures the phase difference between the received CT and the signal from the LO. In-phase and quadrature (IQ) samples of the received CT are locally processed in both the initiator and the reflecting side, and interference is checked. If no interference is detected, the initiator and the reflecting side index or switch to the subsequent channel (f). i ), and from the subsequent period (t i The switching of CTs begins. It will be understood that the channel (t) i ) and period (t) i ) are not necessarily immediately followed by Figure 3 Following the channel (f1) and period (t1) in the text, CT can switch on any number of uninterrupted channels in any number of periods. It will be further understood that, although... Figure 3The frequency of the channel in the diagram is shown to increase linearly (i.e., frequency t...). i Greater than f1, and frequency f i+1 Greater than f i (and so on), but this is not necessarily the case in every embodiment of the agile multicarrier phase ranging process. Instead, the two devices can have pseudolinear, nonlinear, non-random, or pseudo-random channel switching, as explained in more detail below.

[0034] Refer again Figure 3 From period t i During the initial exchange, one or both of the initiator and reflector execute algorithm 302 to detect interference in the CT or exchanged packets, and upon detection of interference, operate to skip multiple subsequent channels for multiple next periods. For example, in the illustrated embodiment, the initiator or reflector will not skip channels in period t. i+1 Located in channel f i+1 A constant tone or group is sent. Afterwards, initiator A and reflector B exchange CTs normally for multiple subsequent periods, checking for interference after each exchange, until the cycle is completed in period (t). n ) in channel f n The switching continues until the point of contact is reached. In the case of pseudo-random channel switching, upon detecting interference, the initiator or reflector decides to skip the upcoming interfering channel in the upcoming period, which may be multiple time slots later.

[0035] Figure 4 This is a flowchart depicting the algorithm by which either the initiating or reflecting ranging device makes local decisions to temporarily skip multiple next constant tone exchanges in multiple next periods. (Reference) Figure 4Upon receiving a CT and, in the case of packets, the initiator or reflector will perform phase measurements and sample and process multiple IQ signals of the received CT (402). The set of these IQ samples has a predetermined standard deviation distribution, and depending on the actual standard deviation of this distribution, the initiator or reflector can determine whether the exchanged CT has been affected by interference (404). Alternatively, for some applications, the initiator or reflector may include more than one antenna, and if the signals from all antennas of a single device exhibit a large amount of noise and / or a large standard deviation, the device can conclude that the CT has been affected by interference. If no interference is detected, the initiator will switch to the next channel and transmit CTs and packets in the next period (406), and continue processing the sampled IQ (402). If interference is detected, the detection device (initiator or reflector) will notify other devices to skip multiple subsequent channels that are likely also interfering channels (408), switch to the next channel in the negotiated channel list, and remain idle for multiple periods starting from the next period (410). After several periods have elapsed, normal operation can resume from processing the sampled IQ (402) to the next unskipped channel. The number of skipped channels and the number of idle periods can depend on the properties of the detected interference and / or the signal path of the CT. For example, single-path and / or multi-path channels will have stable phase (monotone) type characteristics. Therefore, the only deviation will be attributed to noise and / or phase / frequency drift, and the number of skipped channels may be small. However, interference caused by very rapid phase changes (which are proportional to the bandwidth of the interference source) may cause multiple subsequent channels to be skipped.

[0036] Figure 5 It is about the above. Figure 3 and Figure 4 A single-cycle message sequence diagram describing an agile multi-carrier phase ranging process. (Reference) Figure 5 The initiator (device A) and the reflector (device B) perform a handshake and negotiation operation 502, in which the devices discuss parameters of the ranging process (e.g., the channel or frequency to be used, the duration for which each CT will be transmitted (t)). LThe initiator (device A) and the start time of the ranging process are agreed upon. Next, the first cycle of the multi-carrier phase ranging process 504 begins at period t1, where the initiator (device A) sends a first CT (as indicated by arrow 506) towards the reflector B at the first frequency f1. Upon receiving the CT, the reflector B locks or synchronizes its local oscillator to the received signal, performs a phase measurement, and sends the CT back to the initiator A, as indicated by arrow 508. Device A receives the reflected CT and performs a phase measurement. At each frequency, the initiator or reflector executes algorithm 510 to determine whether to exchange the CT or remain idle and skip the exchange for the next period and the next channel. If either device detects interference, it will immediately notify the other side of the presence of interference and will temporarily remain idle and skip the constant tone switching process for the interfering channel. For example, in Figure 5 In the embodiment shown, wherein in channel f i During CT exchange, interference is detected by the reflecting side B (e.g., in...). Figure 3 In the embodiment shown, initiator A and reflector B decide to remain idle and skip targeting channel f. i+1 CT exchange. Then, in the remaining periods until the final period t n Up to this point, for frequency or channel f1 to f n Repeat the previous steps. Then, the initiator and reflector exchange phase measurement results 512 and estimate the distance between the initiator and reflector.

[0037] Figure 6 It is used to execute the above about Figures 3 to 5 A flowchart describing a method for agile multi-carrier phase ranging. (Reference) Figure 6 The method begins with a handshake between the initiator and the reflector to negotiate a list of channels (f1 to f2) for the period (cycle_i) of the multi-carrier phase ranging process. n ) and start time (602). Next, in period (t) i In the channel (f) i The initiator and reflector exchange phase measurements (CTs) (604). In-phase and quadrature (IQ) samples of the received CTs are processed locally in both the initiator and reflector (606), and interference is checked by one or both of the initiator and reflector (608). If no interference is detected, a check is performed to see if the most recently exchanged CT is on the last channel in the list of negotiated channels (610). If the most recently exchanged channel is the last channel, the cycle ends, and the initiator and reflector exchange phase measurements (612). If the most recently exchanged channel is not the last channel, the initiator switches to the subsequent channel or the next channel (f). i+1 ), and in the period (t) i+1The initiator exchanges CT (614) between the initiator and the reflector, and resumes local processing (606) for that cycle.

[0038] If interference is detected, a check is performed to see if the most recently exchanged CT is on the last channel in the list of negotiated channels (616). If the most recently exchanged channel is the last channel, the cycle ends, and the initiator and reflector exchange phase measurement results (612). If the most recently exchanged channel is not the last channel, the device that detected the interference (initiator or reflector) will notify or signal the other device (initiator or reflector) and switch to the subsequent channel or the next channel (f). i+1 ), and in the period (t) i+1 (618) Keep idle at this point. Notification or signaling to another device can be achieved by sending a CT on the next channel not in the channel list, thereby implicitly signaling interference to the device; or by sending a CT of shorter length than expected. Alternatively, where the process includes exchanging packets between the initiator and the reflector, notification or signaling to another device about interference can include: i) not sending packets; ii) sending packets with a specific access address; or iii) sending packets with information or instructions to skip multiple channels. In the next period or subsequent period (t i+2 At point ), the initiator will switch to the subsequent channel or the next channel (f). i+2 ), exchange CT between the initiator and the reflector (620), and then restore local processing for that cycle (606).

[0039] Optionally, after the first cycle or intermediate cycle (cycle_i) has ended and the phase measurement results have been exchanged (612), the method may further include: performing a second handshake or a subsequent handshake (602); and performing a second cycle or a subsequent cycle (cycle_i+1) of the multicarrier phase ranging process without skipping any channels in the channel list based on interference detected in the first cycle or previous cycle (cycle_i). In some embodiments, the method further includes: performing a plurality of (n) subsequent cycles while skipping any channels in the channel list that were skipped in the previous cycle or current cycle (cycle_i) based on detected interference.

[0040] Figure 7 This is another message sequence diagram of a single cycle of an agile multicarrier phase ranging process, illustrating how, depending on the properties of the detected interference, the initiating or reflecting ranging device will decide whether to skip constant tone switching for more than one period and / or more than one channel. (Reference) Figure 7The initiator (device A) and the reflector (device B) perform a handshake and negotiation operation 702, in which the devices discuss parameters of the ranging process (e.g., the channel or frequency to be used, the duration for which each CT will be transmitted (t)). L An agreement was reached on the time for starting the ranging process. Next, the period of the multi-carrier phase ranging process 704 begins at time t. i At the location where the initiator (device A) is at frequency f i A CT is sent towards reflector B (as indicated by arrow 706). Upon receiving the CT, reflector B executes algorithm 708 and detects interference. When in period t... i Located in channel f i When interference is detected, both devices will decide to remain idle and skip the period t. i+1 and t i+2 For channel f i+1 and f i+2 The next two CT exchanges are then performed. Afterward, the initiator and reflector exchange phase measurement results 710 and estimate the distance between the initiator and reflector.

[0041] Figure 8 This is a time and frequency diagram illustrating a three-cycle multi-carrier phase ranging process, where two channels are affected by interference 802 in the first and third cycles. (Reference) Figure 8 Note that channel f i and f i+1 In cycle_i and cycle_i+2, it is affected by disturbance 802. In cycle_i, the reflector executes algorithm 804, and when in period t... i When interference is detected, the initiator will be notified (e.g., by not responding) in the current period on the current channel f. i and the next channel f i+1 The current location is idle. In the next cycle (cycle_i+1), both devices decide to return to normal operation and check channel f again. i and f i+1 Is it idle or interfered with? In this example, as in cycle_i+1, these channels are not interfered with, and the two devices will exchange constant tones. In cycle_i+2, when interference 802 is detected again, the two devices decide to remain idle and skip tone switching again. Figure 8 This demonstrates the ability of an agile multi-carrier phase ranging process to maximize the availability of channels used for phase ranging.

[0042] Figure 9This is a message sequence diagram illustrating the three cycles 902a, 902b, and 902c of the agile multi-carrier phase ranging process. At each channel and each CT exchange, the initiating ranging device or the reflecting ranging device executes algorithm 904 and decides whether to exchange the CT or remain idle and skip the tone exchange. Before each cycle 902a, 902b, and 902c, the initiating device (device A) and the reflecting device (device B) perform a handshake 906 to negotiate the list of channels (f1 to f2) for the ranging cycle. n The initiator (device A) and the reflector (device B) exchange phase measurement results 908 and estimate the distance between the initiator and the reflector after each cycle 902a, 902b, 902c. Optionally, in some embodiments, the handshake includes identifying the channels (f1 to f2) where interference was detected in the previous cycles 902a, 902b, 902c. n The subsequent cycle includes skipping the switching of CTs on the channel where interference was detected in at least one cycle.

[0043] Now refer to Figure 10 and Figure 11 This document describes an embodiment of an agile multicarrier phase ranging process using pseudo-random channel switching. In a pseudo-random channel hopping scenario, when in period t... i Located in channel f i When interference is detected, both devices will decide to remain idle and skip the interference to the adjacent channel f. i+k and f i+k+1 The next two upcoming CT swaps are scheduled k times later in period t. i+k and t i+k+1 This process takes place at a specific location. In short, pseudo-random channel switching refers to a process in which channels exchanging CTs in consecutive periods are not necessarily adjacent to each other or monotonically increasing or decreasing in frequency. For example, in... Figure 10 As can be seen, in the first period (t1) of the cycle (cycle_i) of the agile multi-carrier phase ranging process, at a frequency f i+2 On the channel, CT signals are exchanged between the initiator (A) and the reflector (B). In the subsequent period (t... i At point ), the channel switches or jumps to a lower frequency f. i The channel, and in the next period (t) i+1 At point ), it switches or jumps to a channel with even lower frequency f1. However, in the immediately following period (t) i+2 At point ), the channel switches or jumps to a higher frequency f. i+1 The channel, and in the subsequent period (t) nAt point ), the channel switches or jumps to a frequency f that is even higher. n The channel.

[0044] refer to Figure 10 In the agile multicarrier phase ranging process using pseudo-random channel switching, as in the linear switching embodiment described above, one or both of initiator A and reflector B execute algorithm 1000, and then each CT exchange begins from the first period t1. When in period t... i Located in channel f i When interference 1002 is detected, both devices (i.e., initiator A and reflector B) will decide to remain idle and skip the interference targeting the adjacent channel f. i+1 The upcoming or subsequent CT exchanges, which in the illustrated embodiment are scheduled two periods after period (t) i+2 This will take place at point ). Therefore, in the next immediately following period (t) i+1 At point ), initiator A and reflector B normally exchange CTs on channel f1, which is unaffected by interference 1002. Then, at the previously determined period (t... i+2 At point f, initiator A and / or reflector B remain idle and skip the interference channel f. i+1 The CT scans were then exchanged. Subsequently, initiator A and reflector B exchanged CT scans normally for multiple subsequent periods, checking for interference after each exchange, until the cycle was completed in period (t). n ) in channel f n Until the exchange at that point.

[0045] Figure 11 It is shown Figure 10 A sequence of messages for one cycle of the agile phase ranging process. (Reference) Figure 11 The message sequence begins with the handshake and negotiation operation 1102 performed by the initiator (device A) and the reflector (device B), where the devices specify parameters for the ranging process (e.g., the channel to be used, the length of time each CT will be sent (t)). L The initiator (device A) and the reflector (B) agree on the time to start the ranging process. Additionally, in the pseudo-random channel handover scenario, the initiator A and the reflector B agree on the pseudo-random order of channel handover. Next, the first cycle of the multi-carrier phase ranging process 1104 begins at period t1, where the initiator (device A) selects a time between f1 and f2 based on the agreed-upon pseudo-random order. n The first CT is transmitted between frequencies or channels. In the illustrated embodiment, the switching at time t1 occurs on channel f. i+2The process is as follows. After each exchange, the initiator A and / or the reflector B will execute algorithm 1106 to determine, at the appropriate or associated period, whether to exchange CT or remain idle and skip the exchange for the next channel or the nearest channel in the agreed-upon channel list. Therefore, in the subsequent period t... i In the process, when the reflecting party B detects interference, the initiating party A and the reflecting party B locally decide to skip the next adjacent channel f. i+1 The CT exchange occurs at the appropriate time, but in the next immediately following time t i+1 In the process, the initiator and the reflector exchange CTs on the non-interference channel f1. During period t... i+2 At this point, the initiator and reflector skip the interference channel f as previously decided locally. i+1 The CT scans were then exchanged. Subsequently, initiator A and reflector B exchanged CT scans normally for multiple subsequent periods, checking for interference after each exchange, until the cycle was completed in period (t). n ) in channel f n The exchange continues until the cycle is complete. After the cycle is finished, the initiator and the reflector exchange phase measurement results 1108 and estimate the distance between the initiator and the reflector.

[0046] Similar to the embodiments described above, the agile multicarrier phase ranging process in pseudo-random channel scenarios can and typically be repeated for any number of cycles, each preceded by another handshake and negotiation operation 1102. These subsequent cycles can be performed without skipping any channels based on interference detected in previous cycles, or channels on which interference was detected in previous cycles can be skipped for multiple subsequent cycles without permanently blacklisting previously interfered channels.

[0047] Figure 12 This is a schematic block diagram illustrating the system, demonstrating the usefulness of agile multi-carrier phase ranging procedures. (Reference) Figure 12System 1200 typically includes two or more wireless devices 1202 (e.g., transceivers or transponders), each wireless device 1202 including a transmitter 1204, a receiver 1206, and one or more antennas 1208. Each of the wireless devices 1202 includes Bluetooth Low Energy (BLE) or an 802.15.4 radio capable of operating at multiple frequencies or channels in a band including the 2.4 GHz Industrial, Scientific, and Medical (ISM) band. Each of the wireless devices 1202 includes hardware and software to measure the distance between the initiating device and the reflecting device with sub-meter accuracy by measuring the phase difference in the CT exchanged between the initiating device and the reflecting device. Additionally, at least one of the wireless devices 1202 (the initiating device or the reflecting device) in the ranging pair also includes an architecture for performing algorithms and making local decisions to exchange a constant tone or skip tone exchange for subsequent channels(multiple) and / or periods(multiple).

[0048] Figure 13 This is a schematic block diagram illustrating a portion of a wireless device 1300 (e.g., a transceiver or responder), which includes an antenna 1302, a receiver portion 1304 of the transceiver, and an embodiment 1306 of an architecture or block for performing algorithms and making local decisions to switch constant tone or skip tone switching for subsequent channels(multiple) and / or periods(multiple) of time.

[0049] refer to Figure 13 The receiver section 1304 includes: an RF bandpass filter 1308 for blocking any strong out-of-band signals; a low-noise amplifier (LNA) 1310 for amplifying the received RF signal, including a CT or continuous wave carrier signal for agile multi-carrier phase ranging processes; and a down-conversion RF mixer 1312 coupled to the output of the LNA and a local oscillator (LO) 1314 to convert the RF frequency to a lower intermediate frequency (IF). An active complex filter 1316 and an amplitude limiter 1318 are used to remove any amplitude disturbances 1318 coupled to the analog-to-digital converter ADC 1320 for converting the received signal from analog to digital, and a Gaussian frequency shift keying (GFSK) demodulator 1322 for demodulating the digital signal.

[0050] The architecture or frame 1306 for executing the algorithm typically includes: hardware (e.g., processor 1324) for applying signal processing to the received signal; IQ processing software 1326 (e.g., memory embodied in the processor or firmware coupled to the processor's memory) for applying signal processing to the raw IQ sample; and interference detection software 1328 (e.g., memory embodied in the processor or firmware coupled to the processor's memory) for determining whether the sample has been interfered with.

[0051] Therefore, wireless devices including hardware and / or software supporting agile multi-carrier phase ranging, and methods for operating such wireless devices to detect and mitigate the effects of interference from coexisting devices in a network, have been disclosed. Embodiments of the invention have been described above with the aid of functional and schematic block diagrams illustrating the implementation of specified functions and their relationships. For ease of description, the boundaries of these functional building blocks have been arbitrarily defined herein. Other boundaries may be defined provided that the specified functions and their relationships are properly implemented.

[0052] The foregoing description of specific embodiments will so fully reveal the general nature of the invention that others, by applying knowledge within the scope of the art, can readily modify and / or adapt it to various applications, such as the specific embodiments, without departing from the general concept of the invention, without excessive experimentation. Therefore, based on the teachings and guidance presented herein, such adaptations and modifications are intended to be within the meaning and scope of equivalents of the disclosed embodiments. It should be understood that the wording or terminology herein is for descriptive purposes and not for limitation, and that the terminology or terminology of this specification should be interpreted by those skilled in the art in light of the teachings and guidance.

[0053] It should be understood that the "Detailed Description" section, rather than the "Summary" and "Abstract" sections, is intended to interpret the claims. The "Summary" and "Abstract" sections may set forth one or more exemplary embodiments of the invention as conceived by the inventors(s), but not all exemplary embodiments, and are therefore not intended to limit the invention and the appended claims in any way.

[0054] The breadth and scope of this invention should not be limited by any of the exemplary embodiments described above, but should be defined solely by the appended claims and their equivalents.

Claims

1. A method for ranging between two wireless transceivers, comprising: A handshake is performed between the first and second transceivers to negotiate the list of channels and the start time for the multi-carrier phase ranging process; The period for performing the multi-carrier phase ranging process includes: In the first period on the first channel, constant tone (CT) is exchanged between the first transceiver and the second transceiver. The CT received in the first transceiver and the second transceiver is processed to measure the phase difference between the received CT and the reference signal; Interference in the received CT scan is checked using at least one of the first and second transceivers, and: If no interference is detected, the system switches to the second channel, and during the second period, the CT is exchanged between the first transceiver and the second transceiver; and If interference is detected, then: Instruct the first or second transceiver to skip at least the second channel and remain idle for at least the second period; and Execute multiple (n) subsequent cycles while skipping any channels in the list of channels that were skipped in previous cycles based on detected interference, wherein the number (n) of the subsequent cycles is based on the properties of the detected interference, for which channels in the list of channels are skipped in the subsequent cycles, the properties of the interference including: the intensity of the interference, the length of the interference, the repetition of the interference in the time domain, or the bandwidth of the interference in the frequency domain.

2. The method according to claim 1, further comprising: After checking for interference, it is checked whether the first channel is the last channel in the list of channels, and if the first channel is the last channel, the cycle ends and the measured phase difference is exchanged between the first transceiver and the second transceiver. And another cycle of performing the multicarrier phase ranging process without skipping any channels in the list of channels based on interference detected in the previous cycle.

3. The method according to claim 1, wherein, Notification to the first or second transceiver includes specifying the time length (t) for each CT. L The CT is sent, wherein the time length is shorter than the time length for reaching an agreement in the handshake.

4. The method according to claim 1, wherein, The period for performing the multi-carrier phase ranging process further includes: exchanging packets between the first transceiver and the second transceiver before or after exchanging the CT.

5. The method according to claim 4, wherein, Notifying the first transceiver or the second transceiver includes: not transmitting the packet and at least one of the CT from the first transceiver or the second transceiver that detects interference.

6. The method according to claim 4, wherein, The packets are exchanged after the CT, and the notification to the first or second transceiver that interference has been detected includes sending a packet with a specific access address.

7. The method according to claim 4, wherein, The packets are exchanged after the CT, and the notification to the first transceiver or the second transceiver includes sending a packet with information identifying the interfering channel to be skipped.

8. The method according to claim 1, wherein, Processing the CT in the first transceiver and the second transceiver includes: generating in-phase and quadrature (IQ) samples of the CT received therein in the first transceiver and the second transceiver, and wherein checking for interference in the received CT includes: checking for interference in the IQ samples.

9. The method according to claim 1, wherein, The multi-carrier phase ranging process uses linear channel switching.

10. A method for ranging between two wireless transceivers, comprising: A handshake is performed between the first transceiver and the second transceiver, the handshake including negotiating a list of channels and a start time for the multi-carrier phase ranging process; as well as The period for performing the multi-carrier phase ranging process includes performing the following operations for each channel in the list of channels: During the first period of a plurality of periods, CTs are exchanged between the first transceiver and the second transceiver on the channel; The CT received in the first transceiver and the second transceiver is processed to measure the phase difference between the received CT and the local reference signal; as well as Interference in the received CT scan is checked using at least one of the first and second transceivers, wherein: If no interference is detected, the system switches to another channel in the list of channels, and in the second period, the CT is exchanged between the first transceiver and the second transceiver. as well as If interference is detected, the first transceiver or the second transceiver is notified to skip the other channel in the list of at least the channels and remain idle for another period of at least the plurality of periods.

11. The method of claim 10, further comprising: After the cycle is completed, for each channel in the list of channels, the measured phase difference is exchanged between the first transceiver and the second transceiver; another cycle of the multicarrier phase ranging process is performed without skipping any channels in the list of channels based on interference detected in the previous cycle.

12. The method of claim 10, further comprising: After the cycle is completed, for each channel in the list of channels, the measured phase difference is exchanged between the first transceiver and the second transceiver; another cycle of the multicarrier phase ranging process is performed, skipping the exchange of the CT on any channel in the list of channels on which interference was detected in the previous cycle.

13. The method according to claim 10, wherein, The multi-carrier phase ranging process uses pseudo-random channel switching.

14. A system for determining the distance between two wireless transceivers, comprising: The first and second transceivers each include a processor configured to execute program code in firmware to perform the following operations: Negotiate the list of channels and start time for the multi-carrier phase ranging process; and The multi-carrier phase ranging process is executed in multiple cycles, each cycle including the following operations for each channel in the list of channels: During the first period of a plurality of periods, CTs are exchanged between the first transceiver and the second transceiver on the channel; The phase difference between the received CT and the local reference signal is measured in the first transceiver and the second transceiver; as well as Interference in the received CT scan is checked using at least one of the first and second transceivers, wherein: If no interference is detected, the system switches to another channel in the list of channels, and in the second period, the CT is exchanged between the first transceiver and the second transceiver; and If interference is detected, then: Instruct the first transceiver or the second transceiver to skip at least one of the other channels in the list of channels and remain idle for another of the at least a plurality of periods; and Execute multiple (n) subsequent cycles while skipping any channels in the list of channels that were skipped in previous cycles based on detected interference, wherein the number (n) of the subsequent cycles is based on the properties of the detected interference, for which channels in the list of channels are skipped in the subsequent cycles, the properties of the interference including: the intensity of the interference, the length of the interference, the repetition of the interference in the time domain, or the bandwidth of the interference in the frequency domain.

15. The system according to claim 14, wherein, The processor is also configured to execute program code to generate in-phase and quadrature (IQ) samples of the CT received therein in the first transceiver and the second transceiver, wherein checking for interference in the received CT includes checking for interference in the IQ samples.

16. The system according to claim 14, wherein, The processor is also configured to execute program code to perform the following operations: exchange phase measurement results, determine the distance between the first transceiver and the second transceiver based on the phase measurement results; and in subsequent cycles of the multi-carrier phase ranging process, skip exchanging the CT on any channel in the list of channels on which interference was detected in the previous cycle.

17. The system according to claim 14, wherein, The processor is also configured to execute program code to: exchange phase measurement results, determine the distance between the first transceiver and the second transceiver based on the phase measurement results; and perform subsequent cycles of the multi-carrier phase ranging process without skipping any channels in the list of channels based on interference detected in previous cycles.

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