DE102021113566A1 - Agile interference detection and mitigation for multicarrier phase distance measurement systems - Google Patents

Abstract

A multicarrier phase ranging system and method are provided. In general, the method includes performing a handshake between first and second transceivers to negotiate a list of channels and a start time for a multicarrier phase ranging process. The method comprises, in a first cycle, exchanging a continuous tone (CT) between the first and second transceivers in a first epoch on a first channel and processing the CT received in the first and second transceivers by a phase difference between the received CT and to measure a reference signal. The received CT is checked for interference using software or hardware in either or both of the first and second transceivers. If no interference is detected, the first and second transceivers switch to a different channel and exchange the CT in the next epoch. If an interference is detected, at least one channel is skipped for at least one subsequent epoch.

Description

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This application claims the benefit of priority under 35 USC 119 (e) over U.S. Patent Application No. 63 / 033,740 , filed June 2, 2020, which is incorporated herein by reference in its entirety.

TECHNICAL AREA

This disclosure relates generally to wireless systems, and more particularly to wireless devices that include multicarrier phase-based ranging systems and methods of operating them to detect and mitigate the effects of interference in such systems.

BACKGROUND

The use of wireless networking such as Bluetooth (BT), Bluetooth Low Energy (BLE), and various IEEE 802.15.4 protocols to wirelessly connect devices, including radio frequency identification (RFID), security systems, entertainment devices, home appliances and communication or computing devices, has grown exponentially. In many applications it is necessary to measure a distance or distance between devices on a wireless network. For example, proximity-based access identifiers such as Passive Keyless Entry Systems (PKES) are used extensively to unlock, lock or start a vehicle, contactless smart cards are used in cashless payment systems, transponders are used when collecting parking and Highway tolls are used and RFID tags are commonly used in electronic passports and for personal location or inventory control. Numerous distance measurement techniques have been developed that use wireless signals to measure a distance or distance between devices on a wireless network. One of the most promising of these distance measurement techniques is phase distance measurement, in which the distance between two wireless devices is determined by determining a phase difference between a continuous tone (CT) or continuous wave carrier signal transmitted by an initiating device or initiator and a reflective one Device or a reflector is received, and a reference signal generated by a local oscillator in the reflector is measured. Generally, the phase ranging process begins with the two devices handshaking in which they agree on ranging parameters such as a channel or frequency to use and a time to start the ranging process. Then the initiator sends a CT to the reflector. The CT is sent either alone or together with a packet. In contrast to the CT, which is an unmodulated carrier, the packet is sent using a modulated carrier. For example, the package may include a constant tone extension (CTE) package that is used for direction finding processes at Angle of Arrival (AoA) and Angle of Departure (AoD). When the signal is received, the reflector locks or synchronizes a local oscillator to the received signal, measures a phase difference between the received signal and the reference signal, and transmits a new CT to the initiator. The initiator, which has changed the operating mode to become the receiver, measures the phase difference between the received signal and the reference signal. Later the reflector transmits the results back to the initiator. The initiator receives the phase measurement results from the reflector and combines the results with its own phase measurements to estimate a distance between the initiator and reflector that is proportional to a delta phase of the received signal and the reflector reference signal.

Although the phase distance measurement can theoretically be performed using a single frequency or a narrow range of frequencies, two devices measure the phase shift on two separate carrier frequencies to resolve the half-wavelength ambiguity. Furthermore, current technologies that use phase ranging to mitigate problems caused by multipath fading typically involve sending multiple CT signals over multiple carrier frequencies or channels, typically up to 80 channels with a bandwidth of 1 MHz. Such a system is called a multicarrier phase ranging system. In multi-carrier phase distance measurement systems, the initiator and the reflector exchange at least two CT signals on two carrier frequencies or channels ƒ ₁ and ƒ ₂ , with a distance between the initiator and the reflector being proportional to the delta phase and the delta carrier ƒ ₂ - ƒ ₁ . An example of a phase-based multicarrier distance measurement is in 1A and 1B illustrates where 1A Figure 13 is a message sequence diagram depicting one cycle of a multicarrier phase ranging process illustrates, and 1B Figure 3 is a timing and frequency diagram illustrating the process of 1A illustrated.

Regarding 1A the initiator, device A, and the reflector, device B, conduct a handshaking and negotiation process 102 by which the devices agree on parameters of the ranging process, such as the channels or frequencies to be used, a time duration (t _L ) for which each CT is transmitted, and a point in time to start the ranging process. Next, a first cycle of the multicarrier phase ranging process begins 104 in the case of an epoch or a time slot t ₁ so that the initiator, device A (also by blocks with the designation A in 1B indicated), a first CT with a first frequency ƒ ₁ (by the arrow 106 in 1A shown) with a length of t _L (in 1B shown) in the direction of reflector B (blocks B in 1B) transmits. Upon receiving the CT, the reflector B locks or synchronizes a local oscillator to the received signal, performs a phase measurement and transmits a new CT back to the initiator A, as shown by the arrow 108 in 1A specified. During this time the initiator (device A) has switched operating mode to act as a receiver and then receives the CT of the reflector and measures the phase difference between the received signal and the reference signal. These steps are then repeated for n frequencies or channels (ƒ ₁ -ƒ _n ) in n time slots (t ₁ -t _n ). Then the initiator and the reflector exchange the phase measurement results 110 and estimate a distance between the initiator and the reflector.

Multi-carrier phase range measurement using Bluetooth Low Energy (BLE) and 802.15.4 radios can measure the distance between an initiating device and a reflective device with sub-meter accuracy, but this has become problematic as the devices with interference in the 2nd , 4 GHz ISM band (Industrial, Scientific and Medical Band) must coexist, as this band is more heavily used by other wireless technologies such as Wi-Fi, Bluetooth Classic, Bluetooth LE, ZigBee and Thread. One approach to counter this problem is a classic frequency adaptation, which is described in 2A and 2 B is illustrated. As with the multicarrier phase ranging process described above, using frequency adjustment, the process begins with the initiator, device A, and the reflector, device B, handshaking and negotiating 202 carry out. Next, a ranging cycle (cycle_i 204) is performed during which there is interference 206 (in 2 B as shown occurring on frequencies ƒ _i and ƒ _{i + 1} ) and phase results are exchanged 208. At the end of cycle_i 204, after the phase results have been processed and exchanged, the two devices, initiator A and reflector B, decide the interfering channels (ƒ _i and ƒ _{i + 1} ) to be blacklisted and excluded from a switching channel list that is to be used for subsequent distance measuring cycles. This blacklisting can be permanent or apply for a predetermined number of several distance measuring cycles, after which the previously interfering channels can be placed on a white list for use in subsequent cycles. As in 2A must be shown in order to update the switching channel list for the next cycles, after each distance measuring cycle a new handshaking and a new negotiation 210 between the devices through a Link Layer (LL) or a higher layer negotiation. It should be noted that the above approach of frequency adjustment is not entirely satisfactory, since the decision to blacklist the (disturbed) channels subject to interference is made after analyzing the entire phase measurement result exchange and thus the results of the entire distance measurement cycle undermines. Since the interfering channels are blacklisted permanently or at least for several rangefinding cycles, the accuracy of the multicarrier phase rangefinder process is limited, excluding the benefits of using the entire ISM bandwidth.

Accordingly, there is a need for wireless systems or devices that include multicarrier phase-based ranging systems and methods of operating them to detect and mitigate the effects of interference in such systems without significantly adversely affecting the cost, complexity, or performance of the wireless device.

SHORT VERSION

A multicarrier phase ranging system and method of operating the same to detect and mitigate interference are provided. In general, the method includes performing a handshake between an initiating device (initiator) and a reflective device (reflector) to negotiate a list of channels and a start time for a multicarrier phase ranging process. The process comprises the exchange of a continuous tone (CT) between the initiator and the reflector in an epoch on a channel and the local processing in the initiator and the reflector of in-phase and quadrature samples (IQ samples) of the CT received there . The IQ samples are generated using software or Checked hardware in either the initiator or the reflector or both for interference. If no interference is detected, the initiator and the reflector switch to another channel and exchange the CT in the next epoch. If an interference is detected, at least the next channel is skipped for at least the next epoch. In some cases, a number (n) of subsequent channels in the list of channels for the next n epochs are skipped based on a property of the detected interference, such as strength of the interference, length of the interference packet, repetition of the interference packet in the time domain and bandwidth of the Interference signal in the frequency domain.

In general, the method further includes a test to determine whether the channel on which the CT was last swapped is a last or final channel in the list of channels. If the last exchange of the CT took place via the last or final channel in the list of channels, the cycle is completed and the phase measurement results are exchanged between initiator and reflector. A subsequent cycle of the multicarrier phase ranging process is performed. In one embodiment, the subsequent cycle is performed without skipping channels based on an interference detected in the first or previous cycle (cycle_i). Alternatively, the method may include skipping channels based on interference detected in a first or previous cycle for a number (n) of subsequent cycles, but not permanently skipping channels; H. Blacklisting the disturbed channels.

Further 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. It should be noted that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Other embodiments will be apparent to those skilled in the relevant art based on the teachings contained herein.

Figure list

• 1A ist ein Nachrichtensequenzdiagramm, das einen Mehrträger-Phasenentfernungsmessprozess über n Kanäle veranschaulicht;
• 1B ist ein Zeit- und Frequenzdiagramm, das den Phasenentfernungsmessprozess von 1A veranschaulicht;
• 2A ist ein Nachrichtensequenzdiagramm, das drei Zyklen eines herkömmlichen Ansatzes zur Erkennung und Abschwächung von Interferenz in einem Mehrträger-Phasenentfernungsmessprozess veranschaulicht;
• 2B ist ein Zeit- und Frequenzdiagramm des Phasenentfernungsmessprozesses von 2A;
• 3 ist ein Zeit- und Frequenzdiagramm, das einen einzelnen Zyklus eines agilen Mehrträger-Phasenentfernungsmessprozesses unter Verwendung linearer Kanalumschaltung veranschaulicht, bei dem eine Interferenz auf einem oder mehreren Kanälen während des Zyklus erkannt wird und die betroffenen Kanäle vorübergehend übersprungen werden, ohne dass die Kanäle dauerhaft auf eine schwarze Liste gesetzt werden;
• 4 stellt einen Algorithmus dar, mit dem ein erster drahtloser Sendeempfänger oder eine erste Entfernungsmessvorrichtung oder ein zweiter drahtloser Sendeempfänger eine lokale Entscheidung zum vorübergehenden Überspringen einer Anzahl nächster Dauerton-Austausch(e) in einer Anzahl nächster Epoche(n) trifft;
• 5 ist ein Nachrichtensequenzdiagramm eines einzelnen Zyklus des agilen Mehrträger-Phasenentfernungsmessprozesses, das veranschaulicht, wo eine Initiator- oder eine Reflektor-Entfernungsmessvorrichtung bei jeder Frequenz eine lokale Entscheidung trifft, um entweder den Dauerton für eine nächste Epoche auszutauschen und/oder den Austausch des Dauertons für eine Anzahl von nachfolgenden Kanälen zu überspringen;
• 6 ist ein Fließschema für ein Verfahren zur Durchführung des agilen Mehrträger-Phasenentfernungsmessprozesses;
• 7 ist ein weiteres Nachrichtensequenzdiagramm eines einzelnen Zyklus des agilen Mehrträger-Phasenentfernungsmessprozesses, das veranschaulicht, wo die Initiator- oder die Reflektor-Entfernungsmessvorrichtung in Abhängigkeit von Eigenschaften einer erkannten Interferenz entscheidet, ob Dauertonaustausche für mehr als eine Epoche und/oder mehr als einen Kanal übersprungen werden;
• 8 ist ein Zeit- und Frequenzdiagramm, das drei Zyklen eines agilen Mehrträger-Phasenentfernungsmessprozesses veranschaulicht, bei dem in einem ersten und dritten Zyklus zwei Kanäle von Interferenz betroffen sind;
• 9 ist ein Nachrichtensequenzdiagramm, das die drei Zyklen eines agilen Mehrträger-Phasenentfernungsmessprozesses veranschaulicht, bei dem die Initiator- oder Reflektor-Entfernungsmessvorrichtung bei jedem Tonaustausch auf jedem Kanal entscheidet, entweder einen Dauerton auszutauschen oder inaktiv zu bleiben und den Tonaustausch zu überspringen;
• 10 ist ein Zeit- und Frequenzdiagramm, das einen einzelnen Zyklus eines agilen Mehrträger-Phasenentfernungsmessprozesses unter Verwendung pseudozufälliger Kanalumschaltung veranschaulicht, bei dem eine Interferenz auf einem oder mehreren Kanälen während des Zyklus erkannt wird und die betroffenen Kanäle vorübergehend übersprungen werden;
• 11 ist ein Nachrichtensequenzdiagramm, das einen Zyklus des agilen Phasenentfernungsmessprozesses von 10 veranschaulicht;
• 12 ist ein schematisches Blockdiagramm, das ein System veranschaulicht, das eine Anzahl von Mehrfrequenz- oder Mehrkanal-Sendeempfängern umfasst, für die der agile Mehrträger-Phasenentfernungsmessprozess nützlich ist; und
• 13 ist ein schematisches Blockdiagramm, das eine Ausführungsform einer Architektur veranschaulicht, die in einem oder beiden Entfernungsmessvorrichtungen implementiert werden kann, um einen Algorithmus auszuführen und eine lokale Entscheidung zu treffen, um entweder den Dauerton auszutauschen oder den Tonaustausch für den/die nachfolgenden Kanal/Kanäle und/oder Epoche(n) zu überspringen.

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

• 1A Figure 13 is a message sequence diagram illustrating a multicarrier phase ranging process over n channels;
• 1B FIG. 14 is a timing and frequency diagram illustrating the phase distance measurement process of FIG 1A illustrates;
• 2A Figure 13 is a message sequence diagram illustrating three cycles of a conventional approach to interference detection and mitigation in a multicarrier phase ranging process;
• 2 B FIG. 13 is a timing and frequency diagram of the phase distance measurement process of FIG 2A ;
• 3 Figure 13 is a timing and frequency diagram illustrating a single cycle of an agile multicarrier phase ranging process using linear channel switching in which interference on one or more channels is detected during the cycle and the affected channels are temporarily skipped without the channels permanently up blacklisted;
• 4th represents an algorithm with which a first wireless transceiver or a first distance measuring device or a second wireless transceiver makes a local decision to temporarily skip a number of next continuous tone exchanges (e) in a number of next epoch (n);
• 5 Figure 13 is a message sequence diagram of a single cycle of the agile multicarrier phase ranging process, illustrating where an initiator or reflector ranging device makes a local decision at each frequency to either exchange the continuous tone for a next epoch and / or exchange the continuous tone for a Skip number of subsequent channels;
• 6th Figure 13 is a flow chart for a method of performing the agile multicarrier phase ranging process;
• 7th Figure 4 is another message sequence diagram of a single cycle of the agile multicarrier phase rangefinder process, illustrating where the initiator or reflector rangefinder detected depending on characteristics of one Interference decides whether permanent tone exchanges for more than one epoch and / or more than one channel are skipped;
• 8th Figure 13 is a timing and frequency diagram illustrating three cycles of an agile multicarrier phase ranging process in which two channels are affected by interference in a first and third cycle;
• 9 Figure 13 is a message sequence diagram illustrating the three cycles of an agile multicarrier phase rangefinder process in which the initiator or reflector rangefinder decides, at each tone swap on each channel, to either swap a continuous tone or remain inactive and skip the tone swap;
• 10 Figure 13 is a timing and frequency diagram illustrating a single cycle of an agile multicarrier phase ranging process using pseudo-random channel switching in which interference on one or more channels is detected during the cycle and the affected channels are temporarily skipped;
• 11th FIG. 13 is a message sequence diagram depicting one cycle of the agile phase distance measurement process of FIG 10 illustrates;
• 12th Figure 3 is a schematic block diagram illustrating a system including a number of multi-frequency or multi-channel transceivers for which the agile multi-carrier phase ranging process is useful; and
• 13th Figure 13 is a schematic block diagram illustrating an embodiment of an architecture that can be implemented in one or both of the ranging devices to execute an algorithm and make a local decision to either swap the continuous tone or the tone swap for the subsequent channel (s) and / or skip epoch (s).

DETAILED DESCRIPTION

A wireless network or system comprising a wireless multi-carrier phase range measurement device and methods of operating the same to detect and mitigate interference to provide high accuracy distance measurements (HADM) are disclosed. The wireless device and agile multicarrier phase ranging methods of the present disclosure are particularly useful in or with wireless networks that use Bluetooth (BT), Bluetooth Low Energy (BLE), various IEEE 802.15.4, and WiFi protocols in which it It is desirable to measure a distance or a distance between a first and a second wireless device in order to either improve the accuracy of signals transmitted between the devices and / or to reduce power consumption. Such devices can include, for example, proximity-based access identifiers such as passive keyless entry systems (PKES) that are widely used to unlock, lock or start a vehicle, contactless smart cards that are used in cashless payment systems, transponders that are used when collecting parking and motorway tolls, and include RFID identifiers commonly used in electronic passports and for personal location or inventory control.

In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without these specific details. In other instances, known structures and techniques are not shown in detail or are shown in block diagram form in order to avoid unnecessarily obscuring the understanding of this description.

If “an embodiment” is mentioned in the description, this means that a certain feature, a certain structure or a certain characteristic, which is or which is described in connection with the embodiment, is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in different places in the description need not necessarily all refer to the same embodiment. The term “couple” as used herein can encompass both the direct electrical connection of two or more components or elements and the indirect connection via one or more intermediate components.

An agile multicarrier phase ranging process will now be described in which interference is detected on one or more channels during a cycle of the process and the affected channels are temporarily skipped without the disturbed channels either for all time slots or epochs in the cycle or in subsequent ones Cycles are permanently blacklisted, thereby maximizing the availability of channels for phase distance measurement, especially in the heavily used 2, 4 GHz band for industry, science and medicine (ISM band). An epoch is a time at which or during which a communication event occurs. For example, an exchange of a continuous tone (CT) over a channel between a first and a second wireless device for the purpose of phase distance measurement. CT is understood to mean that it is an unmodulated continuous wave carrier signal at the channel frequency. By "subsequently" it is meant that it occurs at a later time or on a negotiated list of channels, and not necessarily immediately after or following the earlier time or channel.

In general, the method includes performing a handshake between an initiating wireless device or transceiver (initiator) and a reflective wireless device (reflector) to negotiate a list of channels and a start time for a multicarrier phase ranging process. The method includes exchanging a CT between the initiator and the reflector in an epoch (t _i ) on a channel (ƒ _i ), measuring a phase difference between the received CT and a signal from a local oscillator (LO) in each device and the local processing of in-phase and quadrature (IQ) samples of the CT received there. Optionally, the agile multicarrier phase ranging process may further include exchanging a packet between the initiator and the reflector either before or after exchanging the CT. The exchanged packet can be the same as or similar to a CTE packet (Constant Tone Extension Packet) that is used in Bluetooth direction finding to determine an angle of incidence (AoA) or radiation angle (AoD). The IQ samples are checked for interference using software and / or hardware in either the initiator or the reflector or both. If no interference is detected, the initiator and the reflector switch to a subsequent channel (ƒ _{i + 1} ) and exchange the CT in the next epoch (t _{i + 1} ). If an interference is detected, the device that detected the interference communicates with or signals the other device, and at least one subsequent channel is skipped for at least the next epoch.

3 Figure 13 is a timing and frequency diagram illustrating an exemplary embodiment of a single cycle (Cycle_i) of an agile multicarrier phase ranging process in which channels ƒ _i and ƒ _{i + 1 are} affected by interference 300 are affected. Regarding 3 the cycle_i begins at the first epoch t ₁ with the fact that the initiator, device A (indicated by the blocks with the designation A), _{sends a CT with a length of t L} on a first channel or a first frequency (ƒ ₁ ) to the Reflector, device B (in 3 indicated by the blocks labeled B), transmits. The reflector synchronizes a local oscillator (LO) to the received signal, measures a phase difference between the received CT and a signal from the LO and transmits the CT back to the initiator. The initiator (device A), which has switched operating mode during this time to act as a receiver, then receives the reflected signal, synchronizes it to the LO therein and measures a phase difference between the received CT and a signal from the LO. In-phase and quadrature (IQ) samples of the received CT are processed locally in the initiator and reflector and checked for interference. If no interference is detected, the initiator and the reflector index or switch to a subsequent channel (ƒ _i ) and exchange the CT starting with a subsequent epoch (t _i ). It goes without saying that in 3 neither the channel (ƒ _i ) nor the epoch (t _i ) necessarily immediately follow the channel (ƒ ₁ ) and the epoch (t ₁ ), rather the CT can be on any number of channels that do not experience interference in any number be exchanged by epochs. It is also understood that although the frequencies of the channels in 3 are shown as linearly increasing, i.e. the frequency ƒ _i is greater than ƒ _i and the frequency ƒ _{i + 1} is greater than ƒ _i and so on, but this does not necessarily have to be the case in every embodiment of the agile multi-carrier phase distance measurement process. Rather, the two devices can have a pseudo-linear, non-linear, non-random or pseudo-random channel switching, as will be explained in more detail below.

With renewed reference to 3 In the exchange that _{begins in epoch t i} , either the initiator or the reflector or both lead an algorithm 302 to detect interference in either the CT or in the packet, if exchanged, and, upon detection of the interference, operate to skip a number of subsequent channels for a number of next epochs. For example, in the embodiment shown, neither the initiator nor the reflector sends the epoch ƒ _{i + 1} a continuous tone or a packet in the channel ƒ _{i +. 1} Thereafter, initiator A and reflector B exchange CTs normally for a number of subsequent epochs, with interference being checked after each exchange until the cycle is concluded with an exchange on channel ƒ _n at epoch (t _n ). In the case of a pseudo-random channel switch, the initiator or the reflector decides upon detection of the interference to skip the coming disturbed channel in the coming epoch, which can be several time slots later.

4th Figure 13 is a flow chart illustrating an algorithm by which an initiator range finder or a reflector range finder makes a local decision to temporarily skip a number of next continuous tone exchanges (s) in a number of next epoch (n). Regarding 4th after receiving the CT and the packet, if one is included, the initiator or the reflector carries out the phase measurement and samples and processes several IQ signals of the received CT (402). The collection of these IQ samples should have a distribution with a given standard deviation, and depending on the actual standard deviation of the distribution, either the initiator or the reflector can determine whether or not the exchanged CT is affected by interference (404). Additionally, in some applications the initiator or reflector may include more than one antenna, and if the signals from all antennas of a single device have large amounts of noise and / or large standard deviations, then the device may conclude that the CT is interference is affected. If no interference is detected, the initiator switches to the next channel and sends the CT and the packet at the next epoch ( 406 ) and continues processing the sampled IQs (402). If interference is detected, the detecting device (either the initiator or the reflector) informs the other device to skip (408) a number of subsequent channels, which are also likely to be disturbed channels, and switch to the next channel on the negotiated list of channels and remain inactive for a number of epochs beginning with the next epoch (410). Normal operation can resume with the next channel not skipped, starting with processing the sampled IQs ( 402 ) after the number of epochs has passed. The number of skipped channels and the number of inactive epochs can depend on the properties of the detected interference and / or a signal path of the CT. For example, single-use and / or multi-way channels will have a stable phase (monotone) feature. So the only deviation from this will be due to noise and / or phase / frequency drift, and the number of channels skipped may be small. However, interference caused by a very rapid phase change proportional to the bandwidth of the interferer can lead to the skipping of several subsequent channels.

5 FIG. 12 is a message sequence diagram of a single cycle of the multicarrier agile phase ranging process described above with reference to FIG 3 and 4th has been described. Regarding 5 the initiator, device A, and the reflector, device B, conduct a handshaking and negotiation process 502 by which the devices agree on parameters of the ranging process, such as the channels or frequencies to be used, a time duration (t _L ) for which each CT is transmitted, and a point in time to start the ranging process. Next, a first cycle of the multicarrier phase ranging process begins 504 at epoch t ₁ , with the initiator, device A, performing a first CT on a first frequency ƒ ₁ (as indicated by arrow 506 displayed) to the reflector B. Upon receiving the CT, the reflector B locks or synchronizes a local oscillator to the received signal, performs a phase measurement and transmits the CT back to the initiator A, as shown by the arrow 508 specified. Device A receives the reflected CT and takes a phase measurement. The initiator or reflector runs an algorithm on each frequency 510 to decide for the next epoch and the next channel whether the CT should be exchanged or whether it should remain inactive and the exchange should be skipped. When either device detects the interference, it immediately informs the other side of the presence of the interference and remains temporarily inactive, skipping the continuous tone swapping process for that disturbed channel. For example, in the in 5 embodiment shown, in which an interference was detected by the reflector B during the exchange of the CT on the channel ƒ _i , as in the case of FIG 3 embodiment shown, the initiator A and the reflector B to remain inactive and to skip _{the CT exchange for the channel ƒ i + 1.} The previous steps are then repeated for the frequencies or channels ƒ _i to ƒ _n in the remaining epochs up to the last epoch t _n. Then the initiator and reflector exchange phase measurement results 512 and estimate a distance between the initiator and the reflector.

6th FIG. 13 is a flow chart of a method for performing the agile multicarrier phase ranging process described above in relation to FIG 3 until 5 has been described. Regarding 6th the method begins with the execution of a handshake between the initiator and the reflector, _{negotiating a list of channels (ƒ 1} to ƒ _n ) and a start time for a cycle (cycle_i) of a multicarrier phase distance measurement process ( 602 ). Next, in an epoch (t _i ) on a channel (ƒ _i ) a CT is exchanged between the initiator and the reflector ( 604 ). The in-phase and quadrature sampling values (IQ sampling values) of the CT received in the initiator and the reflector are processed locally there ( 606 ) and checked for interference either by the initiator or by the reflector or by both ( 608 ). If no interference is detected, a check is made to see if the last exchanged CT was on the last channel of the negotiated list of channels ( 610 ). If the channel that was last exchanged was the last channel, the cycle is ended and the initiator and reflector exchange phase measurement results ( 612 ). If the channel that was last exchanged was not the last channel, the initiator switches to a subsequent or next channel (ƒ _{i + 1} ) and exchanges the CT between initiator and reflector at epoch (t _{i + 1) (} 614 ) and does the local processing ( 606 ) for the cycle again.

If an interference is detected, a check is carried out to determine whether the last CT exchanged was on the last channel of the negotiated list of channels ( 616 ). If the channel that was last exchanged was the last channel, the cycle is ended and the initiator and reflector exchange phase measurement results ( 612 ). If the channel that was last exchanged was not the last channel, the device (initiator or reflector) that detects the interference informs or signals the other device (initiator or reflector) and switches to one subsequent or next channel (ƒ _{i + 1} ) and remains inactive at epoch (t _{i + 1} ) (618). The information or signaling to the other device can either take place in that no CT is sent on the next channel in the list of channels, which implicitly signals the interference to the device, or a CT with a shorter length than expected is sent . Alternatively, if the process includes exchanging a packet between the initiator and the reflector, informing or signaling the other device of the interference may include: i) not transmitting a packet; ii) sending a packet with a specific access address; or iii) sending a packet containing information or instructions to skip a number of channels. At the next or subsequent epoch (t _{i + 2} ) the initiator switches to a subsequent or next channel (f _{i + 2} ), exchanges the CT between the initiator and reflector ( 620 ) and then takes on local processing ( 606 ) for the cycle again.

Optionally, after the first or intermediate cycle (cycle_i) has ended and phase measurement results have been exchanged ( 612 ), as well as performing a second or subsequent handshake ( 602 ) and performing a second or subsequent cycle (Cycle_i + 1) of the multicarrier phase ranging process without skipping channels in the list of channels based on interference detected in the first or previous cycle (Cycle_i). In some embodiments, the method further comprises performing a number (n) of subsequent cycles, skipping any channels in the list of channels that were skipped in the previous or current cycle (cycle_i) based on detected interference.

7th Figure 3 is another message sequence diagram of another embodiment of a single cycle of the agile multicarrier phase ranging process, illustrating where the initiator or reflector ranging device decides, depending on characteristics of a detected interference, whether permanent tone exchanges for more than one epoch and / or more than one Channel can be skipped. Regarding 7th the initiator, device A, and the reflector, device B, conduct a handshaking and negotiation process 702 by which the devices agree on parameters of the ranging process, such as the channels or frequencies to be used, a time duration (t _L ) for which each CT is transmitted, and a point in time to start the ranging process. Next becomes one cycle of the multicarrier phase range measurement process 704 at epoch t _i at the initiator, device A, when transmitting a CT on a frequency ƒ _i (as indicated by the arrow 706 indicated) on the reflector B. When receiving the CT, the reflector B carries out an algorithm 708 and detects interference. Upon detection of an interference on channel ƒ _i at epoch t _i , the two devices decide to remain inactive and the next two CT exchanges for channels ƒ _{i + 1} and ƒ _{i + 2} at epochs t _{i + 1} and t Skip _{i + 2.} Then the initiator and reflector swap phase measurement results 710 and estimate a distance between the initiator and the reflector.

8th Figure 13 is a timing and frequency diagram illustrating three cycles of an agile multicarrier phase ranging process in which two channels of interference in a first and third cycle 802 are affected. Regarding 8th it should be noted that the channels ƒ _i and ƒ _{i + 1} in the cycle_i and cycle_i + 2 from interference 802 are affected. The reflector executes the algorithm in cycle_i 804 and informs the initiator when the interference is detected in epoch t _i (e.g. by not reacting) that it _{should be inactive on the current channels ƒ i} and the next ƒ _{i + 1} in the current cycle. In the next cycle, cycle_i + 1, the two devices decide to return to normal operation and check again whether channels ƒ _i and ƒ _{i + 1 are} free or faulty. In this example, as in cycle_i + 1, these channels are not disturbed, the two devices exchange the continuous tones. In cycle_i + 2, again when the interference is detected 802 , the two devices decide to remain inactive and skip the sound swap again. 8th illustrates the ability of the agile multi-carrier Phase distance measurement process to maximize the availability of phase distance measurement channels.

9 is a message sequence diagram showing three cycles 902a , 902b , 902c illustrates an agile multicarrier phase rangefinder process in which the initiator or reflector rangefinder applies an algorithm to each CT exchange on each channel 904 performs and decides to either swap a CT or stay inactive and skip the sound swap. Before each cycle 902a , 902b , 902c the initiator (device A) and the reflector (device B) perform a handshake 906 by negotiating a list of channels (ƒ ₁ to ƒ _n ) and a start time for the distance measuring cycle. After every cycle 902a , 902b , 902c the initiator (device A) and the reflector (device B) exchange the phase measurement results 908 and estimate the distance between initiator and reflector. Optionally, in some embodiments, the handshake includes the identification of channels (ƒ ₁ to ƒ _n ) in which in a previous cycle 902a , 902b , 902c interference has been detected and performing a subsequent cycle includes skipping exchanging the CT on channels where interference has been detected for at least one cycle.

One embodiment of an agile multicarrier phase ranging process that uses pseudo-random channel switching will now be described with reference to FIG 10 and 11th described. In the pseudo-random channel hopping scenario, when an interference is detected on channel ƒ _i at epoch t _i , the two devices decide to remain inactive and to skip the next two upcoming CT exchanges for the adjacent channels ƒ _{i + k} and ƒ _{i + k + 1} , the k epochs are planned later for the epochs t _{i + k} and t _{i + k + 1} . In short, pseudo-random channel switching refers to a process in which the channels over which the CT is exchanged in successive epochs are not necessarily adjacent or monotonically increasing or decreasing in frequency. For example, in 10 to see that in a first epoch (t ₁ ) in a cycle (cycle_i) of an agile multi-carrier phase distance measurement process, CT signals are exchanged _{between an initiator (A) and a reflector (B) via a channel with a frequency of ƒ i + 2} will. In a subsequent epoch (t _i ) the channel switches or jumps to a channel with a lower frequency ƒ _i , and in a next epoch (t _{i + 1} ) to a channel with an even lower frequency ƒ ₁ . In an immediately following epoch (t _{i + 2} ), however, the channel switches or jumps to a channel with a higher frequency of ƒ _{i + 1} , and in a subsequent epoch (t _n ) the channel switches or jumps to an even higher frequency from ƒ _n .

Regarding 10 In an agile multicarrier phase ranging process using pseudo-random channel switching, as in the linear switching embodiments described above, either initiator A or reflector B or both leads an algorithm 1000 after every CT exchange that begins _{at a first epoch t 1.} When an interference is detected 1002 on the channel ƒ _i at epoch t _i , the two devices, that is, the initiator A and the reflector B, decide to remain inactive and _{to skip an upcoming or subsequent CT exchange for the adjacent channel ƒ i + 1} , which is the case in the embodiment shown is planned two epochs later at epoch (t _{i + 2} ). In the next, immediately following epoch (t _{i + 1} ), the initiator A and the reflector B swap CTs for the channel ƒ ₁ , which is not subject to interference, normally from 1002. At epoch (t _{i + 2} ), how remains previously decided that initiator A and / or reflector B are inactive and skip a CT exchange for the disturbed channel ƒ _{i + 1} . Thereafter, initiator A and reflector B exchange CTs normally for a number of subsequent epochs, with interference being checked after each exchange until the cycle is concluded with an exchange on channel ƒ _n at epoch (t _n ).

11th FIG. 13 is a message sequence diagram depicting one cycle of the agile phase distance measurement process of FIG 10 illustrated. Regarding 11th the message sequence begins with the initiator, device A, and the reflector, device B, handshaking and negotiating 1102 in which the devices agree on parameters of the ranging process, such as the channels to be used, a length of time (t _L ) for which each CT is transmitted, and a time to start the ranging process. Furthermore, in the scenario of the pseudo-random channel switching, the initiator A and the reflector B agree on a pseudo-random sequence for the channel switching. Next, a first cycle of the multicarrier phase ranging process begins 1104 at epoch t ₁ , wherein the initiator, device A, transmits a first CT on a frequency or channel between ƒ ₁ and ƒ _n selected based on the agreed pseudo-random sequence. In the embodiment shown, the exchange takes place at epoch t ₁ on channel ƒ _{i + 2} . After each exchange, the initiator A and / or the reflector B run an algorithm 1106 in order to decide for the next or closest adjacent channel in the agreed list of channels, either to exchange the CT at the appropriate or associated epoch or to remain inactive and skip the exchange. So if in a subsequent epoch t _i the reflector B detects an interference, the initiator A and the reflector B decide locally, the CT exchange on the next Adjacent channel ƒ _{i + 1} to be skipped in the corresponding epoch, but in the next, immediately following epoch t _{i + 1} , the initiator and the reflector exchange the CT on the undisturbed channel ƒ ₁ . At epoch t _{i + 2} , the initiator and the reflector skip the CT exchange on the disturbed channel ƒ _{i + 1} , as previously decided locally. Thereafter, initiator A and reflector B exchange CTs normally for a number of subsequent epochs, with interference being checked after each exchange until the cycle is concluded with an exchange on channel ƒ _n at epoch (t _n ). After completion of the cycle, the initiator and the reflector exchange the phase measurement results 1108 and estimate the distance between initiator and reflector.

As with the embodiments described above, in the pseudo-random channel scenario, the agile multicarrier phase ranging process can and is generally repeated for any number of cycles, with another handshaking and negotiation process for each cycle 1102 precedes. These subsequent cycles can be performed without channels being skipped based on interference detected in a previous cycle, or channels detected in the previous cycle can be skipped for a number of subsequent cycles without the previously disturbed channels are permanently blacklisted.

12th Figure 4 is a schematic block diagram illustrating a system for which the agile multicarrier phase ranging process is useful. Regarding 12th includes the system 1200 generally two or more wireless devices 1202 , such as transceivers or transponders, each one transmitter 1204 , a recipient 1206 and one or more antennas 1208 include. Any of the wireless devices 1202 includes a Bluetooth Low Energy (BLE) or 802.15.4 radio capable of listening on multiple frequencies or channels in bands including the 2.4 GHz Industrial, Scientific and Medical (ISM) band work. Any of the wireless devices 1202 includes hardware and software to measure a distance between an initiating device and a reflective device with sub-meter accuracy by measuring phase differences in a CT exchanged between the initiating and reflective devices. Also includes at least one of the wireless devices 1202 in a distance measuring pair, either the initiating or the reflecting device, further an architecture to execute an algorithm and to make a local decision to either exchange the continuous tone or to assign the tone exchange for the subsequent channel (s) and / or epoch (s) skip.

13th Figure 3 is a schematic block diagram showing a portion of a wireless device 1300 such as a transceiver or transponder, including an antenna 1302 , a receiver section 1304 of the transceiver and an embodiment of an architecture or block 1306 to run an algorithm and make a local decision to either swap the continuous tone or skip the tone swap for the subsequent channel (s) and / or epoch (s).

Regarding 13th comprises the receiver section 1304 an RF band pass filter 1308 To block out strong out-of-band signals, use a low-noise amplifier (LNA) 1310 to amplify the received RF signals including a CT or CW carrier signal used for the agile multicarrier phase ranging process and a downconverting RF mixer 1312 connected to an output of the LNA and a local oscillator (LO) 1314 is coupled to convert the RF frequency to the lower intermediate frequency (IF). An active complex filter 1316 and an amplitude limiter for eliminating amplitude interference 1318 are equipped with an analog-to-digital converter (ADC) 1320 for converting the received signals from analog to digital and a Gaussian Frequency Shift Keying (GFSK) demodulator 1322 coupled for demodulating the digital signal.

The architecture or the block 1306 to execute the algorithm generally includes hardware such as a processor 1324 to apply signal processing to the received signal, IQ processing software 1326 such as firmware embodied in or coupled to memory in the processor to apply signal processing to the raw IQ samples and interference detection software 1328 such as firmware embodied in or coupled to memory in the processor to decide whether or not the samples are perturbed.

Thus, wireless devices having hardware and / or software to enable agile multicarrier phase ranging and methods of operating the same to detect and mitigate interference effects from coexisting devices in the network have been disclosed. Embodiments of the present invention have been described above using functional and schematic block diagrams that illustrate the implementation of specific functions and their relationships. The limits these function blocks have been specified here to simplify the description. Other limits can be defined as long as the specified functions and their relationships are properly performed.

The foregoing description of the specific embodiments thus fully discloses the general nature of the invention so that others, using a knowledge within the art, can readily modify and / or adapt such specific embodiments for various applications, without undue experimentation and without departing from the general concept of FIG deviate from the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology used herein is for the purpose of description and not of limitation, so that the terminology or phraseology of the present specification will be interpreted by those skilled in the art in light of the teachings and instructions.

It is understood that the “Detailed Description” section and not the “Abstract” and “Summary” sections should be used to interpret the claims. The “Abstract” and “Summary” sections may set forth one or more, but not all, exemplary embodiments of the present invention as contemplated by the inventor (s) and are therefore not intended in any way to set forth the present invention and the appended claims restrict.

The breadth and scope of the present invention should not be limited by any of the exemplary embodiments described above, but should be defined only in accordance with the following claims and their equivalents.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 63/033740 [0001]

Claims (20)

A method of measuring the distance between two wireless transceivers that includes: Performing a handshake between a first transceiver and a second transceiver negotiating a list of channels and a start time for a multicarrier phase ranging process; Perform a cycle of the multicarrier phase ranging method that includes: Exchanging, in a first epoch on a first channel, a constant tone (CT) between the first and second transceivers; Processing the CT received in the first and second transceivers to measure a phase difference between the received CT and a reference signal; Checking for interference in the CT received with at least one of the first transceiver and the second transceiver, and: if no interference is detected, switching to a second channel and, in a second epoch, exchanging the CT between the first and the second transceiver; and if interference is detected, informing the first transceiver or the second transceiver, Skip at least the second channel and remain inactive for at least a second epoch. Procedure according to Claim 1 , further including, after checking for interference, checking that the first channel is a last channel in the list of channels, and if the first channel is the last channel, terminating the cycle and exchanging between the first and second transceivers , of results of the measured phase difference and performing another cycle of the multicarrier phase ranging process without skipping channels in the list of channels based on interference detected in a previous cycle. Procedure according to Claim 1 , further including performing a number (n) of subsequent cycles, skipping any channels in the list of channels that were skipped in a previous cycle based on detected interference. Procedure according to Claim 3 , wherein the number (n) of subsequent cycles that channels in the list of channels are skipped based on interference is based on a property of the interference detected. Procedure according to Claim 4 wherein the property of the interference can include a strength of the interference, a length of the interference packet, a repetition of the interference packet in the time domain and a bandwidth of the interference signal in the frequency domain. Procedure according to Claim 1 wherein informing the first transceiver or the second transceiver includes sending a CT of a shorter than expected length. Procedure according to Claim 1 wherein performing the cycle of the multicarrier phase ranging process further includes exchanging a packet between the first and second transceivers before or after exchanging the CT. Procedure according to Claim 7 wherein informing the first transceiver or the second transceiver includes not transmitting at least one of the packet and the CT from the first transceiver or the second transceiver that detects interference. Procedure according to Claim 7 wherein the packet is exchanged after the CT and wherein informing the first transceiver or the second transceiver that an interference has been detected includes sending a packet with a specific access address. Procedure according to Claim 7 wherein the packet is exchanged after the CT and wherein informing the first transceiver or the second transceiver includes sending a packet with information identifying disturbed channels to be skipped. Procedure according to Claim 1 , wherein the local processing of the CT in the first and second transceivers includes generating in-phase and quadrature (IQ) samples of the CT received there, and wherein checking for interference in the received CT is checking for interference in the Includes IQ samples. Procedure according to Claim 1 , where the multicarrier phase ranging process uses linear channel switching. A method of measuring the distance between two wireless transceivers, comprising: performing a handshake between a first transceiver and a second transceiver, wherein the handshaking is negotiating a list of channels and a Includes start time for a multicarrier phase ranging process; and performing a cycle of the multicarrier phase ranging process, the cycle comprising, for each channel in the list of channels: exchanging a CT between the first transceiver and the second transceiver over the channel during a first epoch of a plurality of epochs; Processing the CT received in the first transceiver and the second transceiver to measure a phase difference between the received CT and a local reference signal; and checking for interference in the CT received with at least one of the first transceiver and the second transceiver, wherein: if interference is not detected, switching to another channel in the list of channels and exchanging the CT between the first transceiver and the second transceiver in a second epoch; and if interference is detected, informing the first transceiver or the second transceiver, skipping at least one other channel in the list of channels, and remaining inactive for at least one more epoch in the plurality of epochs. Procedure according to Claim 13 , further including, upon completion of the cycle, exchanging results of the measured phase difference for each channel in the list of channels between the first and second transceivers and performing another cycle of the multicarrier phase ranging process without any channels in the list of channels skipped based on an interference detected in a previous cycle. Procedure according to Claim 13 , further including, upon completion of the cycle, exchanging results of the measured phase difference for each channel in the list of channels between the first and second transceivers and performing another cycle of the multicarrier phase ranging process, exchanging the CT on each channel is skipped in the list of channels on which interference was detected in a previous cycle. Procedure according to Claim 13 , wherein the multicarrier phase ranging process uses pseudo-random channel switching. A system for determining a distance between two wireless transceivers that includes: a first transceiver and a second transceiver, each including a processor configured to execute program code in firmware to: negotiate a list of channels and a start time for a multicarrier phase ranging process; and perform a number of cycles of the multicarrier phase ranging process, each cycle comprising, for each channel in the list of channels: Exchanging a CT between the first transceiver and the second transceiver over the channel during a first epoch of a plurality of epochs; Measuring, in the first transceiver and the second transceiver, a phase difference between the received CT and a local reference signal; and Checking for interference in the CT received with at least one of the first transceiver and the second transceiver, wherein: if no interference is detected, switching to another channel in the list of channels and exchanging the CT between the first transceiver and the second transceiver in a second epoch; and if interference is detected, informing the first transceiver or the second transceiver, Skipping at least one other channel in the list of channels and remaining inactive for at least one further epoch in the multitude of epochs. System according to Claim 17 wherein the processor is further configured to execute program code to generate in-phase and quadrature (IQ) samples of the received CT in the first and second transceivers, and wherein checking for interference in the received CT is checking for interference in the IQ samples. System according to Claim 17 , wherein the processor is further configured to Execute program code to exchange phase measurement results from which the distance between the first and second transceivers is determined and to execute subsequent cycles of the multicarrier phase distance measurement process, the swapping of the CT on any channel in the list of channels on that in a previous Cycle interference is detected, it is skipped. System according to Claim 17 , wherein the processor is further configured to execute program code to exchange phase measurement results from which the distance between the first and second transceivers is determined and to execute subsequent cycles of the multicarrier phase distance measurement process without including channels in the list of channels based on skipped in a previous cycle of detected interference.

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