Support for calibration of round trip time error

Abstract

Certain aspects of the present disclosure provide a method for wireless communication at a first wireless node, the method generally comprising: generating a first frame associated with a timestamp; outputting the first frame for transmission to a second wireless node as part of a ranging procedure; and outputting, for transmission, signaling including information on a transmit impulse response of the first frame.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application No. 17 / 951,850, filed on September 23, 2022, which is assigned to the assignee of the present application and is hereby expressly incorporated by reference in its entirety, as if fully set forth below and for all applicable purposes. Background Art Technical Field

[0003] Aspects of the present disclosure relate to wireless communications, and more particularly to techniques for calibrating errors in round trip time (RTT) measurements.

[0004] Related technologies

[0005] Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, and single carrier FDMA (SC-FDMA) networks.

[0006] In order to address the problem of increased bandwidth requirements required for wireless communication systems, different schemes are being developed to allow multiple user terminals to communicate with a single access point by sharing channel resources while achieving high data throughput. Multiple-input multiple-output (MIMO) technology represents one such approach that has emerged as a popular technology for communication systems. MIMO technology has been adopted in several wireless communication standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards. IEEE 802.11 represents a set of wireless local area network (WLAN) air interface standards developed by the IEEE 802.11 committee for short-range communications, such as tens of meters to hundreds of meters.

[0007] 802.11 has standardized procedures for measuring the RTT between two devices (eg, stations) to achieve ranging and positioning. Aspects of the present disclosure provide mechanisms that can help enhance RTT measurements and increase the accuracy of such ranging and positioning procedures. Summary of the invention

[0008] One aspect provides a method for wireless communication at a first wireless device. The method includes: generating a first frame associated with a timestamp; outputting the first frame for transmission to a second wireless node as part of a ranging procedure; and outputting signaling including information about a transmit impulse response of the first frame for transmission.

[0009] Another aspect provides a method for wireless communication (and ranging procedure) at a second wireless node. The method includes: obtaining a first frame for estimating a timestamp as part of a ranging procedure; obtaining information about a transmit impulse response of the first frame; adjusting a receive timestamp of the first frame based on the information about the transmit impulse response of the first frame; and outputting a frame having a value determined based on the adjusted receive timestamp as part of a ranging procedure.

[0010] Other aspects provide: an apparatus operable to, configured to, or otherwise adapted to perform any one or more of the foregoing methods and / or those described elsewhere herein; a non-transitory computer-readable medium comprising instructions that, when executed by a processor of the apparatus, cause the apparatus to perform the foregoing methods and those described elsewhere herein; a computer program product embodied on a computer-readable storage medium, the computer-readable storage medium comprising code for performing the foregoing methods and those described elsewhere herein; and / or an apparatus comprising components for performing the foregoing methods and those described elsewhere herein. By way of example, an apparatus may include a processing system, a device having a processing system, or a processing system cooperating through one or more networks.

[0011] For purposes of illustration, the following description and drawings set forth certain features. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings depict certain features of the various aspects described herein and should not be considered to limit the scope of the disclosure.

[0013] Figure 1 An example wireless communication network is depicted.

[0014] Figure 2 An example disaggregated base station architecture is depicted.

[0015] Figure 3 An example round trip time (RTT) procedure is depicted.

[0016] Figure 4 Examples of RTT with different transmit filtering are depicted.

[0017] Figure 5 Another example of RTT with different transmit filtering is depicted.

[0018] Figure 6 Depicted are example RTT errors caused by filtering differences at the sender and receiver.

[0019] Figure 7 An example of RTT calibration is depicted.

[0020] Figure 8 is an example call flow diagram for calibrating RTT error in accordance with aspects of the present disclosure.

[0021] Fig. 9 A method for wireless communication is described.

[0022] Fig.10 A method for wireless communication is described.

[0023] Fig.11 Aspects of an example communications device are depicted. DETAILED DESCRIPTION

[0024] Aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for calibrating errors in round trip time (RTT).

[0025] RTT (Round Trip Time) measurements have been widely used in various wireless systems such as Wi-Fi, 5G NR, and Ultra Wideband (UWB) for ranging procedures. A ranging procedure typically involves two stations: an initiator (initiating a ranging procedure) and a responder. A location session may be established for a ranging procedure, which may involve one or more bursts of packets, based on which one or more RTT measurements are obtained, which may be used to determine a distance (d = .5·RTT·c).

[0026] Unfortunately, errors in RTT measurements can degrade the position accuracy of the ranging procedure. The accuracy can be particularly evident when the ranging procedure involves equipment from different vendors. Although each vendor calibrates its own equipment, vendor-to-vendor testing still shows significant RTT errors that can result in decimeter or even meter errors in ranging accuracy. One reason for some of these errors may be the use of different transmit (Tx) filtering, which can result in errors in the receive timestamps measured at the initiator and responder.

[0027] Various aspects of the present invention can help reduce RTT error by reporting the TX filter response in the ranging frame to facilitate the device receiving the ranging frame to estimate the RTT error. The estimated RTT error can be used to adjust the receive timestamp, which can result in more accurate RTT measurement and increased position accuracy of the ranging procedure.

[0028] The techniques described herein can be applied to ranging procedures performed in various different types of wireless networks such as Wi-Fi, 5G NR, and UWB. The improved accuracy using the techniques proposed herein can help achieve certain design goals, such as centimeter-level ranging accuracy.

[0029] The various aspects of the present disclosure are described more fully below with reference to the accompanying drawings. However, the present disclosure can be implemented in many different forms and should not be interpreted as being limited to any specific structure or function presented throughout the present disclosure. On the contrary, these aspects are provided so that the present disclosure will be thorough and complete, and the scope of the present disclosure will be fully conveyed to those skilled in the art. Based on the teachings of this article, it should be understood by those skilled in the art that the scope of the present disclosure is intended to cover any aspect of the disclosure disclosed herein, whether it is independently implemented or implemented in combination with any other aspect of the present disclosure. For example, any number of aspects stated herein can be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such a device or method that is practiced using other structures, functionality, or structure and functionality in addition to the various aspects of the disclosure stated herein or different from the various aspects of the disclosure stated herein. It should be understood that any aspect of the disclosure disclosed herein can be implemented by one or more elements of the claim.

[0030] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.

[0031] Although specific aspects are described herein, numerous variations and arrangements of these aspects fall within the scope of the present disclosure. Although some benefits and advantages of preferred aspects are mentioned, the scope of protection of the present disclosure is not intended to be limited by specific benefits, uses or objects. More specifically, various aspects of the present disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks and transmission protocols, some of which are illustrated by way of example in the drawings and the following description of the preferred aspects. The specific embodiments and drawings are merely illustrative of the present disclosure and are not limiting. The scope of the present disclosure is defined by the appended claims and their equivalents.

[0032] The techniques described herein can be used in various broadband wireless communication systems, including communication systems based on orthogonal multiplexing schemes. Examples of such communication systems include space division multiple access (SDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and the like. SDMA systems can make full use of different directions to simultaneously send data belonging to multiple user terminals. TDMA systems can allow multiple user terminals to share the same frequency channel by dividing the transmitted signal into different time slots, each of which is assigned to a different user terminal. OFDMA systems utilize orthogonal frequency division multiplexing (OFDM), which is a modulation technique that divides the entire system bandwidth into multiple orthogonal subcarriers. These subcarriers may also be referred to as tones, bins, and the like. With OFDM, each subcarrier can be independently modulated using data. An SC-FDMA system may utilize interleaved FDMA (IFDMA) to transmit on subcarriers distributed across the system bandwidth, centralized FDMA (LFDMA) to transmit on adjacent subcarrier blocks, or enhanced FDMA (EFDMA) to transmit on multiple adjacent subcarrier blocks. In general, modulation symbols are transmitted in the frequency domain using OFDM and in the time domain using SC-FDMA.

[0033] The teachings herein may be incorporated into (eg, implemented within or performed by) various wired or wireless devices (eg, nodes). In some aspects, a wireless node implemented in accordance with the teachings herein may comprise an access point or an access terminal.

[0034] An access point ("AP") may include, be implemented as, or be referred to as a Node B, a radio network controller ("RNC"), an evolved Node B (eNB), a base station controller ("BSC"), a base transceiver station ("BTS"), a base station ("BS"), a transceiver function ("TF"), a radio router, a radio transceiver, a basic service set ("BSS"), an extended service set ("ESS"), a radio base station ("RBS"), or some other terminology.

[0035] An access terminal ("AT") may include, be implemented as, or be referred to as a subscriber station, a subscriber unit, a mobile station (MS), a remote station, a remote terminal, a user terminal (UT), a user agent, a user device, a user equipment (UE), a user station, or some other term. In some implementations, an access terminal may include a cellular phone, a cordless phone, a session initiation protocol ("SIP") phone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a handheld device with wireless connection capability, a station ("STA"), or some other suitable processing device connected to a wireless modem. Therefore, one or more aspects taught herein may be incorporated into a phone (such as a cellular phone or a smart phone), a computer (such as a laptop), a tablet device, a portable communication device, a portable computing device (such as a personal data assistant), an entertainment device (such as a music or video device, or a satellite radio), a global positioning system (GPS) device, or any other suitable device configured to communicate via a wireless medium or a wired medium. In some aspects, the node is a wireless node. For example, such a wireless node may provide connectivity for or to a network (such as a wide area network such as the Internet or a cellular network) via a wired or wireless communication link.

[0036] Example Wireless Communication System

[0037] Figure 1 is a diagram illustrating an example wireless communication system 100 in accordance with certain aspects of the present disclosure. System 100 may be a multiple-input multiple-output (MIMO) / multi-link operation (MLO) system 100. Figure 1 As shown, access point (AP) 110 includes an association manager 112 that may be configured to take one or more actions described herein. Wireless station (STA) 120a includes an association manager 122 that may be configured to take one or more actions described herein.

[0038] For simplicity, Figure 1Only one AP 110 is shown in the figure. An AP is typically a fixed station that communicates with wireless STAs, and may also be referred to as a base station (BS) or some other term. A wireless STA may be fixed or mobile, and may also be referred to as a mobile STA, a wireless device, or some other term. The AP 110 may communicate with one or more wireless STAs 120 on a downlink (DL) and / or uplink (UL) at any given moment. The DL (i.e., forward link) is a communication link from the AP 110 to the wireless STA 120, and the UL (i.e., reverse link) is a communication link from the wireless STA 120 to the AP 110. The wireless STA 120 may also communicate peer-to-peer with another wireless STA 120, for example, via a direct link (such as a tunneled direct link setup (TDLS)). The system controller 130 may communicate with the access point and provide coordination and control for the access point.

[0039] Although portions of the following disclosure will describe wireless STAs 120 that are capable of communicating via spatial division multiple access (SDMA), for certain aspects, the wireless STAs 120 may also include some wireless STAs 120 that do not support SDMA. Therefore, for such aspects, the AP 110 may be configured to communicate with both SDMA and non-SDMA wireless STAs 120. This approach may facilitate allowing older versions of wireless STAs 120 ("legacy" stations) to remain deployed in an enterprise, thereby extending their useful life, while allowing newer SDMA wireless STAs 120 to be introduced where deemed appropriate.

[0040] The system 100 uses multiple transmit antennas and multiple receive antennas to transmit data on the DL and UL. ap The set of K selected wireless stations 120 collectively represents multiple output for DL ​​transmission and multiple input for UL transmission. For pure SDMA, if the data symbol streams of the K wireless STAs are not multiplexed in code, frequency, or time in some way, then N is expected. ap > K > 1. K can be greater than N if the data symbol streams can be multiplexed using TDMA techniques, different code channels using CDMA, non-intersecting subband sets using OFDM, etc. ap Each selected wireless STA sends user-specific data to the access point and / or receives user-specific data from the access point. Generally speaking, each selected wireless STA may be equipped with one or more antennas (ie, N sta > 1). The K selected wireless STAs may have the same or different numbers of antennas.

[0041] The system 100 may be a time division duplex (TDD) system or a frequency division duplex (FDD) system. For a TDD system, DL and UL share the same frequency band. For an FDD system, DL and UL use different frequency bands. The system 100 may also transmit using a single carrier or multiple carriers. Each wireless STA may be equipped with a single antenna or multiple antennas. If the wireless STA 120 shares the same frequency channel by dividing the transmission / reception into different time slots, the system 100 may also be a TDMA system, with each time slot being assigned to a different wireless STA 120. The system 100 may also be a carrier sense multiple access (CSMA) with a collision avoidance (CA) system, in which the STA 120 performs carrier sense to access the medium and attempts to avoid collisions by starting to transmit only after the transmission channel is idle.

[0042] Figure 2 A block diagram illustrating an AP 110 and two wireless STAs 120m and 120x in a MIMO / MLO system, such as system 100, in accordance with certain aspects of the present disclosure.

[0043] AP 110 is equipped with N ap The wireless STA 120m is equipped with N antennas 224a to 224t. sta,m antennas 252ma to 252mu, and the wireless STA 120x is equipped with N sta,x The AP 110 is a transmitting entity for DL ​​and a receiving entity for UL. Each wireless STA 120 is a transmitting entity for UL and a receiving entity for DL. As used herein, a "transmitting entity" is an independently operated device or equipment capable of transmitting data via a wireless channel, and a "receiving entity" is an independently operated device or equipment capable of receiving data via a wireless channel. The term communication generally refers to transmission, reception, or both. In the following description, the subscript "DL" indicates downlink, the subscript "UL" indicates uplink, and N UL Wireless STAs are selected for simultaneous transmission on the uplink, N DL Wireless STAs are selected for simultaneous transmission on the downlink, N UL May or may not be equal to N DL , and N UL and N DL It may be a static value, or can change for each scheduling interval.Beam steering or some other spatial processing technique may be used at the access points and wireless stations.

[0044] On the UL, at each wireless STA 120 selected for UL transmission, a transmit (TX) data processor 288 receives traffic data from a data source 286 and control data from a controller 280. The TX data processor 288 processes (e.g., encodes, interleaves, and modulates) the traffic data for the wireless station based on a coding and modulation scheme associated with a rate selected for the wireless STA and provides a data symbol stream. The TX spatial processor 290 performs spatial processing on the data symbol stream and transmits the data symbol stream to the N STA. sta,m The antennas provide N sta,m Each transceiver (TMTR) 254 receives and processes (eg, converts to analog, amplifies, filters, and upconverts) a corresponding transmit symbol stream to generate an uplink signal. sta,m The transceivers 254 provide N sta,m UL signal for N sta,m The antennas 252 transmit to the AP 110.

[0045] Scheduling N UL Each of these wireless STAs performs spatial processing on its data symbol stream and sends its set of transmit symbol streams to AP 110 on the UL.

[0046] At AP 110, N ap The antennas 224a to 224ap transmit from all N UL Each antenna 224 provides a received signal to a corresponding transceiver (RCVR) 222. Each transceiver 222 performs processing complementary to that performed by transceiver 254 and provides a received symbol stream. The receive (RX) spatial processor 240 processes the N ap N of transceivers 222 ap The receiver performs spatial processing on the received symbol streams and provides N UL Receiver spatial processing is performed based on channel correlation matrix inversion (CCMI), minimum mean square error (MMSE), soft interference cancellation (SIC), or some other technique. Each recovered UL data symbol stream is an estimate of the data symbol stream sent by the corresponding wireless station. The RX data processor 242 processes (e.g., demodulates, deinterleaves, and decodes) the stream according to the rate used for each recovered uplink data symbol stream to obtain decoded data. The decoded data for each wireless STA can be provided to the data sink 244 for storage and / or to the controller 230 for further processing.

[0047] On the DL, at AP 110, TX data processor 210 receives N data packets scheduled for downlink transmission from data source 208. DL The TX data processor 210 processes (e.g., encodes, interleaves, and modulates) the traffic data of each wireless station based on the rate selected for each wireless station. The TX data processor 210 processes (e.g., encodes, interleaves, and modulates) the traffic data of each wireless station based on the rate selected for each wireless station. DL The wireless stations provide N DL TX spatial processor 220 performs N DL The DL data symbol streams are spatially processed (such as precoding or beamforming as described in the present disclosure) and are N ap The antennas provide N ap Each transceiver 222 receives and processes a corresponding transmit symbol stream to generate a DL signal. ap The transceiver 222 provides N ap DL signals for N ap The antennas 224 transmit to the wireless STAs.

[0048] At each wireless STA 120, N sta,m The antenna 252 receives N signals from the access point 110. ap Each transceiver 254 processes the received signal from an associated antenna 252 and provides a received symbol stream. The RX spatial processor 260 processes the received signal from the N sta,m N of transceivers 254 sta,m The RX data processor 270 performs receiver spatial processing on the received symbol streams and provides a recovered DL data symbol stream for the wireless station. The receiver spatial processing is performed based on CCMI, MMSE, or some other technique. The RX data processor 270 processes (e.g., demodulates, deinterleaves, and decodes) the recovered DL data symbol stream to obtain decoded data for the wireless station.

[0049] At each wireless STA 120, the channel estimator 278 estimates the DL channel response and provides a DL channel estimate, which may include a channel gain estimate, an SNR estimate, a noise variance, etc. Similarly, the channel estimator 228 estimates the UL channel response and provides a UL channel estimate. The controller 280 of each wireless STA is generally based on the wireless station's downlink channel response matrix H dn,m The controller 230 derives the spatial filter matrix for the wireless station based on the effective UL channel response matrix H up,effTo derive the spatial filter matrix for the AP. The controller 280 of each wireless STA may transmit feedback information (e.g., downlink and / or uplink eigenvectors, eigenvalues, SNR estimates, etc.) to the AP. Controllers 230 and 280 also control the operation of various processing units at AP 110 and wireless STA 120, respectively.

[0050] Although simultaneous uplink and downlink transmissions are described herein, it should be understood that a single downlink and uplink transmission between devices may also be performed. In addition, although AP-scheduled transmissions are described, STAs may also transmit unscheduled transmissions. In addition, although MIMO processing by the AP and STAs is described, the system 100 may also support single-antenna devices that do not use any spatial processing.

[0051] Aspects related to calibrating RTT error

[0052] Aspects of the present invention provide mechanisms that can help increase ranging accuracy by identifying the root cause of many RTT errors, estimating the RTT error, and compensating for the RTT by adjusting the receive timestamp.

[0053] Many RTT errors may be caused by using different filters and different RTT algorithms at the initiator station and the responder station. Since it is generally difficult to enforce filter responses and / or RTT algorithms in standard specifications (standards), aspects of the present disclosure propose mechanisms that may lead to changes in the standard to support reporting of TX filter responses for ranging frames, so as to facilitate the device receiving the ranging frame to estimate the RTT error.

[0054] RTT devices are usually calibrated so that the RTT error is zero when both the initiator and responder are similar devices (e.g., from the same vendor) and both devices use the same RTT algorithm and the same filtering. If the devices use different filtering and / or different RTT algorithms, this may cause RTT errors.

[0055] Figure 3 A timing diagram of an example RTT protocol is depicted. As illustrated, a first station (e.g., a responding station) transmits a fine time measurement (FTM) frame and records a departure time (t1). The FTM frame is received at a second station (e.g., an initiating station), which records the receipt time (t2). The second station may acknowledge receipt of the FTM frame by transmitting an acknowledgment (ACK) frame and recording the departure time (t3). The ACK frame is received at the first station, which records the receipt time (t4).

[0056] The timestamps t1 and t4 may be reported back to the second (initiating) station where the position will actually be calculated. The timestamps t1 and t4 may be included in subsequent FTM frames. Once the initiating station receives t1 and t4 from the responding station, the initiating station may calculate its position as follows:

[0057] RTT = (t4 - t1) - (t3 - t2).

[0058] This RTT value can then be used to calculate the distance as follows:

[0059] d=0.5·RTT·c,

[0060] Where c is the propagation speed (ie, the speed of light). The device calibrates its reported T1..T4 times to ensure that the RTT is correct.

[0061] As described above, executing the RTT procedure with devices using different Tx filtering may result in RTT errors, for example, depending on the RTT algorithm used. In some cases, a threshold is used to determine the timestamp, such as a First Arrival Correction (FAC) threshold.

[0062] like Figure 4 As illustrated in , a device using different Tx filtering but the same FAC threshold (as indicated by the dots) may not see a difference in RTT even if the device sends different responses. In the illustrated example, STA1 and STA2 use different Tx filtering, resulting in a first transmit pulse response 402 from STA1 and a second transmit pulse response 404 from STA2, but use the same FAC threshold.

[0063] like Figure 5 As illustrated in , devices using different Tx filtering and different FAC thresholds (as indicated by dots) may see differences in RTT. In the illustrated example, STA1 and STA2 use different Tx filtering and different FAC thresholds, resulting in a first transmit pulse response 502 from STA1 and a second transmit pulse response 504 from STA2. In this case, the time point may be too late because: 1) STA2 may use a different FAC threshold; and STA2 may use different filtering.

[0064] Figure 6A graph 600 depicts an example of RTT error caused by filtering differences. In the figure, the different impulse responses are flat within one dB in 20 MHz, but the first curve 602 has a narrower Tx finite impulse response (TxFIR) than the second curve 604. If both STAs use the same FAC threshold (e.g., with an amplitude of 0.3), there is no timing error. If one STA uses a FAC threshold of 0.3 and the other STA uses a FAC threshold of 0.6, there may be an error of 8ns, which may result in an error of about 2.4m in ranging accuracy.

[0065] If one STA uses a threshold of 0.3 and the other STA uses a threshold of 1 (e.g., no peak estimation), there may be an error of 16ns (corresponding to 4.8m). For higher bandwidth modes, the error is proportionally smaller. For 160MHz, the worst case error is 8 times smaller (so about 0.6m instead of 4.8m). Figure 6 The example error shown in may be larger than the RTT noise error, which is less than 1 m at high SNR in a wired channel.

[0066] Other factors may contribute to RTT errors. For example, differences in filtering may also include different propagation delays. For example, this may be due to different ADC or DAC delays. In this specification, it is generally assumed that propagation delays are included in the transmit and receive pulse responses htx and hrx.

[0067] The impact of different propagation delays can be demonstrated by considering an example where STA1 and STA2 are identical except that STA2 has an additional TX delay of D2. If both STA1 and STA2 are calibrated using replicas of themselves, there may be no RTT error. This is because STA2 adds D2 to both its T1 and T3 times (so T3-T2 > D2), and STA1 sees an additional delay of D2 in T4, which was not present in T4 when STA2 did not have the additional TX delay. In this case there is no RTT error because the D2 term cancels when calculating RTT = (T4-T1)-(T3-T2).

[0068] If STA1 is calibrated using STA2, which is calibrated using its own replica, different results are obtained. The calibration adds D2 to T1 from STA1 (or subtracts D2 from T4) so ​​that there is no RTT error between STA1 and STA2. When STA1 does RTT to its own replica, there will be an RTT error of D2. This example illustrates the importance of using the same equipment when doing RTT calibration without a mechanism to estimate and compensate for errors.

[0069] Figure 7 An example of RTT calibration is illustrated. The figure shows a TX pulse response 702 from a responder 702, an RX pulse response 704 from an initiator, a TX pulse response 706 from an initiator, and an RX pulse response 708 from a responder. Calibration may be performed to ensure that (T4-T1)-(T3-T2)=RTT. For example, for simplicity, assuming RTT=0, T1 will need to be equal to T2 and T3 will need to be equal to T4. It is permissible to have equal deviations in {T1, T4} and different equal deviations in {T2, T3} because such deviations are eliminated in the RTT calculation. For example, the deviation may be the difference between the TX response time and the RX response time.

[0070] How different filtering and RTT algorithms can cause RTT errors can be demonstrated by assuming an example where both STA1 and STA2 are perfectly calibrated to a device that is a replica of STA1 and STA2. In this case, STA1 can be calibrated such that:

[0071] T1 = T2 = RTT1 (conv (htx1, hrx1)); and

[0072] T4=T3=RTT1(conv(htx1,hrx1)).

[0073] Similarly, STA2 can be calibrated such that:

[0074] T1 = T2 = RTT2 (conv (htx2, hrx2)); and

[0075] T4=T3=RTT2(conv(htx2,hrx2)),

[0076] Where RTT1() is the RTT algorithm of STA1, and RTT2() is the RTT algorithm of STA2. In order to have zero error when STA1 is used as the responder and STA2 is used as the initiator, the T1, T2 and T4, T3 values ​​must match, except that T1, T4 can have a constant deviation D relative to T2, T3:

[0077] T1 = RTT1 (conv (htx1, hrx1)) = T2 = RTT2 (conv (htx1, hrx2)) + D; and

[0078] T4=RTT1(conv(htx2,hrx1))=T3=RTT2(conv(htx2,hrx2))+D.

[0079] Note that in this example, the actual RTT is assumed to be zero because (T4-T1)-(T3-T2) decreases to 0 when T1=T2 and T4=T3, in order to focus entirely on the calibration error.

[0080] The above examples generally show that RTT error involves two conditions:

[0081] RTT1(conv(htx1,hrx1))=RTT2(conv(htx1,hrx2))+D; and

[0082] RTT1(conv(htx2,hrx1))=RTT2(conv(htx2,hrx2))+D.

[0083] This can be illustrated by considering some examples. As a first example, if the TX filtering is the same but the RX filtering is different, then the 2 requirements are reduced to 1 requirement:

[0084] RTT1(conv(htx1,hrx1))=RTT2(conv(htx1,hrx2))+D.

[0085] This is true because RTT2() differs from RTT1() by some constant offset that depends on the difference in RX filtering. Therefore, there is no RTT error in this case. As a second example, the RX filtering can be the same, but the TX filtering is different, such that:

[0086] RTT1(conv(htx1,hrx1))=RTT2(conv(htx1,hrx1))+D; and

[0087] RTT1(conv(htx2,hrx1))=RTT2(conv(htx2,hrx1))+D.

[0088] This is only true if RTT1 == RTT2, so both devices need to use the same RTT algorithm (e.g., the same FAC threshold for both devices). The third example assumes that both TX and RX filtering are different. In this case, there may always be some RTT error even if both devices use the same RTT algorithm.

[0089] Different devices may be used to perform RTT calibration. In this case, using the same RTT algorithm and the same filtering, the RTT devices may be calibrated such that the RTT error is zero when both the initiator and responder are similar devices. If the devices used for calibration have different filtering (including different propagation delays) and / or different RTT algorithms, this will cause RTT errors for other devices. An illustrative example assumes that STA1 and STA2, which have different TX and RX filters, are calibrated such that:

[0090] T1 = T2 = RTT2 (conv (htx1, hrx2)); and

[0091] T3=T4=RTT1(conv(htx2,hrx1)).

[0092] To get zero error, when some third device is used as an initiator that calibrates using a replica of itself:

[0093] T1 = RTT2 (conv (htx1, hrx2)) = T2 = RTT3 (conv (htx3, hrx3)) + D; and

[0094]

[0095] This may be true for certain cases where the difference in filtering happens to be cancelled out by the difference in the RTT algorithm. In most cases there will be a significant RTT error. This again illustrates the importance of performing the calibration with the same equipment.

[0096] Due to the problems described above regarding RTT error, using current RTT methods results in a golden test device (e.g., a standardized test device that can generally be used to calibrate any other device). For example, if STA1 happens to have the same TX filtering as the test device, and STA2 has the same RX filtering as the test device and the same RTT algorithm as the test device, the test device will not show an RTT error to both STA1 and STA2, even though there may be a significant RTT error between STA1 and STA2.

[0097] Generally speaking, the test equipment will show STA1 and STA2 a certain RTT error, which depends on the differences in TX / RX filtering and RTT algorithms, which cannot be used to predict the RTT error between STA1 and STA2. However, with some additional measurements, it is possible to make a golden test equipment. In addition to the RTT error, such test equipment may also need to measure the TX response from 2 STAs. In this case, only the oversampled peak samples may be sufficient. If both STAs know the TX response from the other STA, they can estimate the RTT calibration term that eliminates the RTT deviation between them.

[0098] Aspects of the present disclosure may help address RTT deviations by providing TX filtering to participating stations. For example, each STA may signal its oversampled TX pulse response peak htx. In some cases, only samples within some range, such as + / -100ns around the peak may be required. In some cases, the initiator may estimate the difference T2d between the T2 timing of conv(htx1, hrx2) to conv(htx2, hrx2). The latter may be used by calibration for STA2. The responder may estimate the difference T4d between the T4 timing of conv(htx2, hrx1) to conv(htx1, hrx1). The latter is used by calibration for STA1. T2d and T4d may be signaled in the FTM message, or they may be used to correct T2 and T4. This procedure may remove RTT deviations without having to know the RTT algorithm of each device. Each device may know its own RX filter response and RTT algorithm, so it only needs to know the TX response from another device to estimate the RTT error. This method may assume that each device is perfectly calibrated using its own replica. If this condition is not true, then a test device may be used to account for residual RTT deviation.

[0099] In some cases, a golden test device can be used to provide an accurate estimate of the overall TX impulse response of the device. This ensures that all responses are estimated in the same way. Each device can signal its TX impulse response for each RTT measurement. However, it should be noted that depending on which mode is used, a device may have multiple TX responses (e.g., 20-in-20 and 20-in-160 modes may result in different TX responses). In some cases, a golden test device can be used to provide an estimate of the residual RTT error of the device after applying TX response deviation compensation. In some cases, the residual RTT error may be caused, for example, by a device having a certain fixed deviation in its T4-T1 or T3-T2 measurements.

[0100] A residual RTT error may be reported for each RTT measurement to compensate for this bias, or it may be used by a device to compensate its T4-T1 or T3-T2 measurements.

[0101] It may be desirable to estimate the overall TX impulse response without affecting any RX filtering and without affecting the effect of using an IFFT with rectangular windowing. To estimate the TX response, the frequency domain channel estimate estimated by some reference receiver can be divided by the known RX frequency response to eliminate RX filtering. The impulse response h can be estimated from the frequency domain channel H by performing the following operation:

[0102] h = Fs'*inv(Fs*Fs')*H(subcarrier_ind); and

[0103] Fs=F(subcarrier_ind,time_ind),

[0104] Where F is the N-point FFT matrix, where N is large enough to get a high oversampling rate in h. For example, for a 20MHz mode, N=1024 gives 16x oversampling. Large oversampling can make it easier for the STA to perform further interpolation to calculate the RTT correction term with a resolution of <<1ns. The impulse response can also be estimated from:

[0105] subcarrier_ind: the index of the subcarrier used in the OFDM channel symbol; and

[0106] time_ind: The index in the time domain that includes the peak, e.g. samples in the range 0..800ns.

[0107] There may also be alternative methods of estimating h using MMSE or SVD.

[0108] The start time of the impulse response is usually insignificant for the RTT deviation because it is ignored in the T2d / T4d calculation. For example, if htx1 starts 50ns earlier, the corrected T2 is 50ns less, but T4 is 50ns greater, so that these 50ns are eliminated when calculating RTT = (T4-T1)-(T3-T2).

[0109] In this specification, it can be assumed that the calibration offset is independent of the fact that the device is an initiator or a responder. This usually means that the device applies the same offset to T1 and T3 (TX offset) and T2 and T4 (RX offset). If this is not the case, there may be additional RTT errors.

[0110] In one example, STA1 and STA2 may be assumed to be identical except for an additional receiver delay of D in STA2. If STA2 applies a CAL offset of D on both T1 and T3, there is no RTT error to STA1 nor to any other STA with a different receiver delay. If STA2 is the initiator, T4-T1 from STA1 is greater than D due to the additional delay, and T3-T2 is greater than D due to the STA2 CAL, so there is no RTT error.

[0111] If STA2 applies a CAL offset of 2D to T1 but does not apply anything to T3, there is an RTT error for other STAs with receiver delays different from D. If STA2 is the initiator, T4-T1 from STA1 is larger than D due to the additional delay, but T3-T2 is unchanged: there is an RTT error = D. If STA2 is the responder, T4-T1 from STA2 is smaller than D-2D, but T3-T2 is unchanged: and there is an RTT error = -D. If STA2 performs RTT on its own replica, then T4-T1 is smaller than D-2D, and T3-T2 is larger than D: in this case, RTT error = 0.

[0112] As described herein, differences in filtering and RTT algorithms result in RTT deviations between different devices. Eliminating RTT errors between different devices may require knowledge of the TX pulse response of the other device. In some cases, the calculation of the correction term may be based on the difference in the TX response of both the initiator and the responder. Alternatively, these corrections may all be calculated at one device, but in addition to the TX response of the two devices, the device also needs to know the RTT algorithm used by the different devices. RTT calibration should be performed using the same device.

[0113] As mentioned above, unless the above TX response correction is done, there may not be a golden test device. The golden test device would be a good way to get the TX response from the device under test plus any residual RTT error.

[0114] Implementing the techniques described herein may involve potential changes in the standards to address the deviation issue. For example, the changes may need to accommodate the transmission of the TX response plus the residual RTT error from the test device in the FTM message or capability field.

[0115] In some cases, this information may be signaled in each FTM message as a TX response, and the RTT algorithm may vary depending on the packet bandwidth SNR and potentially other factors.

[0116] The enhancement of the ranging procedure proposed in this paper can be found in Figure 8 800 to understand the call flow diagram.

[0117] As illustrated, the responder may send an FTM frame for the initiator to measure the timestamp from it. For each such ranging frame used to estimate the timestamp, the transmitter of the ranging frame may signal information about the TX pulse response of the ranging frame. Based on this information, the initiator may adjust its Rx timestamp (t2).

[0118] Similarly, the initiator may send an ACK frame for the responder to measure the timestamp from it. For each such ranging frame used to estimate the timestamp, the initiator may signal information about the TX pulse response of the ranging frame. Based on this information, the responder may adjust its Rx timestamp (t4). As illustrated, the responder may provide an indication of t4 and t1 to the initiator. The initiator may use the values ​​of t4 and t1 received from the responder together with t2 and t3 recorded at the initiator to calculate the RTT.

[0119] In some cases, the content of the Tx IR information may be a number of samples around the peak of the impulse response. The sampling rate may be specified or signaled as part of the ranging procedure. The sampling is preferably complex in-phase and quadrature sampling. An alternative Tx IR information would use a sampled frequency response.

[0120] The signaling can be done in an "immediate" manner for the current ranging frame or in a "delayed" manner for the previous ranging frame. Figure 8 As illustrated in , the signaling may be included in the ranging frame itself (e.g., if the ranging frame is an FTM frame or an ACK frame with a data payload), or in an LMR (Location Measurement Report) frame (e.g., if the ranging frame is a ranging NDP frame without a data payload).

[0121] It is usually relatively difficult to change the ACK frame content, so another option is for the sender of the ACK frame to transmit another frame. For example, another frame may be sent at the end of the sounding sequence to report the TX pulse response of the ACK frame together with the token information for each of the ACK frames transmitted in the sounding sequence. This also means that the receiver of the ACK frame may not know the TX pulse response of the ACK frame until the end of the sounding sequence, and therefore cannot correct the error in the RX timestamp of the ACK frame until the end of the sounding sequence. Therefore, for each of the ACK frames received in the sounding sequence, the receiver of the ACK frame needs to transmit another frame to report the residual in the RX timestamp of the ACK frame.

[0122] The residual in the RX timestamp of each ranging frame may also be reported to facilitate the test equipment to report calibration results. This reporting may be done in the ranging frame itself, in the LMR frame, or in a separate frame.

[0123] Example Operation of the First Wireless Node

[0124] Fig. 9 An example of a method 900 for wireless communication at a first wireless node is shown. In some examples, the first wireless node is a station, such as Figure 1 and Figure 2 STA 120. In some examples, the first wireless node is an AP device, such as Figure 1 and Figure 2 AP 110.

[0125] Method 900 begins at step 905, where a first frame associated with a timestamp is generated. In some cases, the operation of this step refers to the Fig.11 The described circuit for generating and / or code for generating, or can be executed by the circuit and / or the code.

[0126] Method 900 then proceeds to step 910, where the first frame is output to be sent to the second wireless node as part of a ranging procedure. In some cases, the operation of this step refers to the same as in reference Fig.11 The described circuit for outputting and / or code for outputting, or can be executed by the circuit and / or the code.

[0127] Method 900 then proceeds to step 915, where signaling including information about the transmit impulse response of the first frame is output for transmission. In some cases, the operation of this step refers to the operation described in reference to Fig.11 The described circuit for outputting and / or code for outputting, or can be executed by the circuit and / or the code.

[0128] In some aspects, this information is signaled via the first frame.

[0129] In some aspects, the first frame comprises: an FTM frame; an ACK frame; or an LMR frame.

[0130] In some aspects, outputting signaling for transmission including information about a transmit impulse response of a first frame includes, after outputting the first frame for transmission, outputting the information for transmission via a second frame.

[0131] In some aspects, the first frame comprises an acknowledgement frame output for transmission as part of a sounding sequence; and the second frame is output for transmission after the sounding sequence.

[0132] In some aspects, the second frame includes information regarding a transmit impulse response of a plurality of acknowledgment frames as part of a sounding sequence.

[0133] In some aspects, the method 900 further includes obtaining signaling indicating a reception timestamp of each of the confirmation frames as received at the second wireless node as part of a ranging procedure. In some cases, the operation of this step refers to as described in reference to Fig.11 The described circuit for obtaining and / or the code for obtaining, or can be executed by the circuit and / or the code.

[0134] In some aspects, method 900 further includes: after probing the sequence, obtaining an indication of a residual in each of the received timestamps. In some cases, the operation of this step refers to the operation of Fig.11 The described circuit for obtaining and / or the code for obtaining, or can be executed by the circuit and / or the code.

[0135] In some aspects, method 900 further includes: adjusting the received timestamp based on the indication of the residual. In some cases, the operation of this step refers to the operation of Fig.11 The circuit for adjustment and / or the code for adjustment may be executed by the circuit and / or the code.

[0136] In some aspects, method 900 further includes: calculating RTT based on the adjusted receive timestamp as part of a ranging procedure. In some cases, the operation of this step refers to the Fig.11 The described circuits for computing and / or codes for computing, or can be executed by the circuits and / or the codes.

[0137] In some aspects, method 900 further includes: outputting a frame having a value determined based on the calculated RTT. In some cases, the operation of this step refers to the operation of Fig.11 The described circuit for outputting and / or code for outputting, or can be executed by the circuit and / or the code.

[0138] In some aspects, the method 900 further includes: obtaining a second frame associated with the timestamp from the second wireless node. In some cases, the operation of this step refers to the Fig.11 The described circuit for obtaining and / or the code for obtaining, or can be executed by the circuit and / or the code.

[0139] In some aspects, the method 900 further includes: obtaining information about the transmit impulse response of the second frame. In some cases, the operation of this step refers to the operation of Fig.11 The described circuit for obtaining and / or the code for obtaining, or can be executed by the circuit and / or the code.

[0140] In some aspects, method 900 further includes adjusting the estimated receive timestamp of the second frame based on information about the transmit impulse response of the second frame. In some cases, the operation of this step refers to as described in reference Fig.11 The circuit for adjustment and / or the code for adjustment may be executed by the circuit and / or the code.

[0141] In some aspects, the method 900 further includes: outputting a signaling of third information about the residual in the estimated received timestamp for transmission. In some cases, the operation of this step refers to the Fig.11 The described circuit for outputting and / or code for outputting, or can be executed by the circuit and / or the code.

[0142] In some aspects, information about the residual in the estimated received timestamp is signaled via: a first frame; or a LMR frame.

[0143] In one aspect, method 900 or any aspect related thereto may be performed by an apparatus such as Fig.11 The method 900 is performed by a communication device 1100 that includes various components that are operable, configured, or adapted to perform the method 900. The communication device 1100 is described in more detail below.

[0144] Please note that Fig. 9 This is merely one example of a method, and other methods including fewer, additional, or alternative steps may also be consistent with the present disclosure.

[0145] Example Operation of the Second Wireless Node

[0146] Fig.10 An example of a method 1000 for wireless communication at a second wireless node is shown. In some aspects, the second wireless node is a station, such as Figure 1 and Figure 2 In some aspects, the second wireless node is an AP device, such as Figure 1 and Figure 2 AP 110.

[0147] Method 1000 begins at step 1005, where a first frame for estimating a timestamp is obtained as part of a ranging procedure. In some cases, the operation of this step refers to the Fig.11 The described circuit for obtaining and / or the code for obtaining, or can be executed by the circuit and / or the code.

[0148] Method 1000 then proceeds to step 1010, where information about the transmit impulse response of the first frame is obtained. In some cases, the operation of this step refers to the operation described in reference to Fig.11The described circuit for obtaining and / or the code for obtaining, or can be executed by the circuit and / or the code.

[0149] Method 1000 then proceeds to step 1015, where the receive timestamp of the first frame is adjusted based on the information about the transmit impulse response of the first frame. In some cases, the operation of this step refers to the operation described in reference to Fig.11 The circuit for adjustment and / or the code for adjustment may be executed by the circuit and / or the code.

[0150] Method 1000 then proceeds to step 1020, where a frame having a value determined based on the adjusted receive timestamp is output as part of a ranging procedure. In some cases, the operation of this step refers to the operation described in reference to Fig.11 The described circuit for outputting and / or code for outputting, or can be executed by the circuit and / or the code.

[0151] In some aspects, the information is obtained via the first frame.

[0152] In some aspects, the first frame comprises: an FTM frame; an ACK frame; or an LMR frame.

[0153] In some aspects, obtaining information about a transmit impulse response of a first frame includes obtaining the information via a second frame after obtaining the first frame.

[0154] In some aspects, the first frame comprises an acknowledgement frame obtained as part of a sounding sequence; and the second frame is obtained after the sounding sequence.

[0155] In some aspects, the second frame includes information regarding a transmit impulse response of a plurality of acknowledgment frames as part of a sounding sequence.

[0156] In some aspects, the method 1000 further includes: outputting signaling indicating a reception timestamp of each of the confirmation frames as received at the second wireless node for transmission as part of the ranging procedure. In some cases, the operation of this step refers to as described in reference to Fig.11 The described circuit for outputting and / or code for outputting, or can be executed by the circuit and / or the code.

[0157] In some aspects, the method 1000 further includes: after the sounding sequence, outputting an indication of the residual in each of the received timestamps. In some cases, the operation of this step refers to the operation of Fig.11 The described circuit for outputting and / or code for outputting, or can be executed by the circuit and / or the code.

[0158] In some aspects, the method 1000 further includes: outputting a second frame for estimating the timestamp for transmission as part of a ranging procedure. In some cases, the operation of this step refers to the operation of Fig.11 The described circuit for outputting and / or code for outputting, or can be executed by the circuit and / or the code.

[0159] In some aspects, method 1000 further includes outputting information about the transmit impulse response of the second frame. In some cases, the operation of this step refers to the operation of Fig.11 The described circuit for outputting and / or code for outputting, or can be executed by the circuit and / or the code.

[0160] In some aspects, the method 1000 further includes: outputting signaling of information about the residual in the received timestamp for transmission. In some cases, the operation of this step refers to the Fig.11 The described circuit for outputting and / or code for outputting, or can be executed by the circuit and / or the code.

[0161] In some aspects, outputting signaling of information about residuals in received timestamps for transmission includes outputting information about residuals in received timestamps via: a second frame used to estimate timestamps as part of a ranging procedure; or an LMR frame.

[0162] In one aspect, method 1000 or any aspect related thereto may be performed by an apparatus such as Fig.11 The method 1000 is performed by a communication device 1100 that includes various components that are operable, configured, or adapted to perform the method 1000. The communication device 1100 is described in more detail below.

[0163] Please note that Fig.10 This is merely one example of a method, and other methods including fewer, additional, or alternative steps may also be consistent with the present disclosure.

[0164] Example Communication Device

[0165] Fig.11 Depicted are aspects of an example communications device 1100. In some aspects, communications device 1100 is a station, such as described above with respect to Figure 1 and Figure 2 In some aspects, the communication device 1100 is an AP, such as the STA 120 described above. Figure 1 and Figure 2 Describe the AP 110.

[0166] The communication device 1100 includes a processing system 1105 coupled to a transceiver 1175 (e.g., a transmitter and / or a receiver). The transceiver 1175 is configured to transmit and receive signals for the communication device 1100, such as various signals as described herein, via an antenna 1180. The transceiver 1175 may be a reference Figure 2 Examples of various aspects of the transceiver 222 and / or the transceiver 254 are described. The processing system 1105 may be configured to perform processing functions for the communication device 1100, including processing signals received and / or to be transmitted by the communication device 1100.

[0167] The processing system 1105 includes one or more processors 1110. In various aspects, the one or more processors 1110 may represent Figure 2 120 RX data processor 270, TX data processor 288, TX spatial processor 290 or controller 280. In various aspects, one or more processors 1110 may represent Figure 2 One or more of the RX data processor 242, TX data processor 210, TX spatial processor 220, or controller 230 of the AP 110 illustrated in FIG. The one or more processors 1110 are coupled to the computer-readable medium / memory 1140 via a bus 1170. In certain aspects, the computer-readable medium / memory 1140 is configured to store instructions (e.g., computer-executable code) that, when executed by the one or more processors 1110, cause the one or more processors 1110 to perform: Fig. 9 The method 900 described herein or any aspect related thereto; and / or Fig.10 The described method 1000 or any aspect related thereto. Note that reference to a processor performing a function of the communication device 1100 may include one or more processors 1110 performing that function of the communication device 1100 .

[0168] In the depicted example, the computer-readable medium / memory 1140 stores code (e.g., executable instructions), such as code for generating 1145, code for outputting 1150, code for obtaining 1155, code for adjusting 1160, and code for calculating 1165. Processing of the code for generating 1145, code for outputting 1150, code for obtaining 1155, code for adjusting 1160, and code for calculating 1165 may cause the communication device 1100 to perform: Fig. 9 The method 900 described herein or any aspect related thereto; and / or Fig.10 The described method 1000 or any aspect related thereto.

[0169] The one or more processors 1110 include circuits configured to implement (e.g., execute) code stored in the computer-readable medium / memory 1140, including circuits such as: circuits for generating 1115, circuits for outputting 1120, circuits for obtaining 1125, circuits for adjusting 1130, and circuits for calculating 1135. Processing using the circuits for generating 1115, the circuits for outputting 1120, the circuits for obtaining 1125, the circuits for adjusting 1130, and the circuits for calculating 1135 may cause the communication device 1100 to perform: Fig. 9 The method 900 described herein or any aspect related thereto; and / or Fig.10 The described method 1000 or any aspect related thereto.

[0170] The various components of the communication device 1100 may provide means for performing the following: Fig. 9 The method 900 described herein or any aspect related thereto; and / or Fig.10 The method 1000 described herein or any aspect related thereto. For example, in some cases, a component for sending, transmitting, or outputting for sending may include Figure 2 The transmitter unit 254 or antenna 252 of the STA 120 illustrated in FIG. 1 , and / or Fig.11 The transceiver 1175 and antenna 1180 of the communication device 1100 in FIG. In some cases, components for sending, transmitting, or outputting for sending may include Figure 2 The transmitter unit 222 or antenna 224 of the AP 110 illustrated in FIG. 1 , and / or Fig.11 The transceiver 1175 and antenna 1180 of the communication device 1100 in some aspects may include Figure 2 The receiver unit 254 or antenna 252 of the STA 120 illustrated in FIG. 1 , and / or Fig.11 The transceiver 1175 and antenna 1180 of the communication device 1100 in some aspects may include Figure 2 The receiver unit 222 or antenna 224 of the AP 110 illustrated in FIG. 1 , and / or Fig.11 The transceiver 1175 and antenna 1180 of the communication device 1100 in FIG. In some aspects, the means for generating, the means for calculating, the means for adjusting, and / or the means for estimating may include Figure 2 One or more processors among the processors illustrated in .

[0171] Sample Clauses

[0172] Specific implementation examples are described in the following numbered clauses:

[0173] Item 1: A method for wireless communication at a first wireless node, the method comprising: generating a first frame associated with a timestamp; outputting the first frame for transmission to a second wireless node as part of a ranging procedure; and outputting signaling for transmission including information about a transmit pulse response of the first frame.

[0174] Clause 2: The method of clause 1, wherein the information is signaled via the first frame.

[0175] Clause 3: The method of clause 2, wherein the first frame comprises: an FTM frame; an ACK frame; or an LMR frame.

[0176] Clause 4: A method according to any one of clauses 1 to 3, wherein outputting signaling including information about the transmit impulse response of the first frame for transmission comprises: after outputting the first frame for transmission, outputting the information for transmission via a second frame.

[0177] Clause 5: The method of clause 4, wherein: the first frame comprises an acknowledgement frame output for transmission as part of a sounding sequence; and the second frame is output for transmission after the sounding sequence.

[0178] Clause 6: The method of clause 5, wherein the second frame includes information regarding a transmit impulse response of a plurality of acknowledgement frames as part of the sounding sequence.

[0179] Clause 7: The method according to clause 6 further includes: obtaining signaling indicating a reception timestamp of each of the confirmation frames as received at the second wireless node as part of the ranging procedure; obtaining an indication of a residual in each of the reception timestamps after the detection sequence; adjusting the reception timestamp based on the indication of the residual; calculating RTT based on the adjusted reception timestamp as part of the ranging procedure; and outputting a frame having a value determined based on the calculated RTT.

[0180] Clause 8: According to the method described in any one of clauses 1 to 7, the method also includes: obtaining a second frame associated with a timestamp from the second wireless node; obtaining information about a transmit pulse response of the second frame; and adjusting the estimated receive timestamp of the second frame based on the information about the transmit pulse response of the second frame.

[0181] Clause 9: The method of clause 8, further comprising: outputting signaling of third information regarding the residual in the estimated reception timestamp for transmission.

[0182] Clause 10: The method of clause 9, wherein the information about the residual in the estimated reception timestamp is signaled via: the first frame; or a LMR frame.

[0183] Clause 11: A method for wireless communication at a second wireless node, the method comprising: obtaining a first frame for estimating a timestamp as part of a ranging procedure; obtaining information about a transmit pulse response of the first frame; adjusting a receive timestamp of the first frame based on the information about the transmit pulse response of the first frame; and outputting a frame having a value determined based on the adjusted receive timestamp as part of the ranging procedure.

[0184] Clause 12: The method of clause 11, wherein the information is obtained via the first frame.

[0185] Clause 13: The method of clause 12, wherein the first frame comprises: an FTM frame; an ACK frame; or an LMR frame.

[0186] Clause 14: The method of any one of clauses 11 to 13, wherein obtaining information about a transmit impulse response of the first frame comprises obtaining the information via a second frame after obtaining the first frame.

[0187] Clause 15: The method of clause 14, wherein: the first frame comprises an acknowledgement frame obtained as part of a sounding sequence; and the second frame is obtained after the sounding sequence.

[0188] Clause 16: The method of clause 15, wherein the second frame comprises information regarding a transmit impulse response of a plurality of acknowledgement frames as part of the sounding sequence.

[0189] Clause 17: The method according to clause 16 further comprising: outputting signaling indicating a reception timestamp of each of the confirmation frames as received at the second wireless node for sending as part of the ranging procedure; and outputting an indication of a residual in each of the reception timestamps after the detection sequence.

[0190] Clause 18: A method as described in any of clauses 11 to 17, the method further comprising: outputting a second frame for estimating a timestamp for transmission as part of the ranging procedure; and outputting information about a transmit impulse response of the second frame.

[0191] Clause 19: A method according to any of clauses 11 to 18, further comprising: outputting signalling of information about the residual in the received timestamp for transmission.

[0192] Clause 20: A method according to clause 19, wherein outputting signaling of information about the residual in the received timestamp for sending includes: outputting the information about the residual in the received timestamp via: a second frame for estimating timestamps as part of a ranging procedure; or an LMR frame.

[0193] Clause 21: An apparatus, the apparatus comprising: a memory including executable instructions; and a processor configured to execute the executable instructions and cause the apparatus to perform the method according to any one of clauses 1 to 20.

[0194] Clause 22: An apparatus comprising means for performing the method according to any one of clauses 1 to 20.

[0195] Clause 23: A non-transitory computer readable medium comprising executable instructions which, when executed by a processor of an apparatus, cause the apparatus to perform the method of any one of clauses 1 to 20.

[0196] Clause 24: A computer program product embodied on a computer readable storage medium, the computer readable storage medium comprising code for performing the method according to any one of clauses 1 to 20.

[0197] Clause 25: A wireless node comprising: at least one transceiver; a memory comprising instructions; and one or more processors configured to execute the instructions and cause the wireless node to perform a method according to any one of clauses 1 to 10, wherein the at least one transceiver is configured to send a first frame.

[0198] Clause 26: A wireless node comprising: at least one transceiver; a memory comprising instructions; and one or more processors configured to execute the instructions and cause the wireless node to perform a method according to any one of clauses 11 to 20, wherein the at least one transceiver is configured to receive a first frame.

[0199] Additional considerations

[0200] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein are not limited to the scope, applicability or aspects set forth in the claims. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. For example, without departing from the scope of the present disclosure, the functions and arrangements of the elements discussed may be changed. Various examples may omit, replace or add various procedures or components as appropriate. For example, the described methods may be performed in an order different from the order described, and various actions may be added, omitted or combined. In addition, the features described for some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such devices or methods practiced using other structures, functionality or structures and functionality that are supplementary or alternative to the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of the present invention.

[0201] The various illustrative logical blocks, modules, and circuits described in conjunction with the present disclosure may be implemented or performed using a general purpose processor, a digital signal processor (DSP), an ASIC, a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic components, discrete hardware components, or any combination thereof, designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, a system on a chip (SoC), or any other such configuration.

[0202] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items (including single members). For example, "at least one of a, b, or c" is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other ordering of a, b, and c).

[0203] As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, searching (e.g., searching in a table, a database, or another data structure), ascertaining, and the like. Additionally, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Additionally, "determining" may include resolving, selecting, choosing, establishing, and the like.

[0204] The method disclosed herein includes one or more actions for implementing the method. The method actions are interchangeable with each other without departing from the scope of the claims. In other words, unless a specific order of actions is specified, the order and / or use of specific actions may be modified without departing from the scope of the claims. In addition, the various operations of the method described above may be performed by any appropriate component capable of performing the corresponding function. The component may include various hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs) or processors.

[0205] The following claims are not intended to be limited to the various aspects shown herein, but should be given the full scope consistent with the language of the claims. Within the claims, unless otherwise specified, reference to an element in the singular form is not intended to mean "one and only one", but "one or more". Unless otherwise specified, the term "some" refers to one or more. Any claim element is not interpreted according to the provisions of 35 U.S.C. § 112 (f) unless the element is explicitly stated using the phrase "parts for...". All structural and functional equivalents of the elements of the various aspects described throughout the present disclosure that are known or will be known later to a person of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims.

Claims

1. A device, comprising: a memory including processor-executable instructions; and one or more processors configured to execute the processor-executable instructions and cause the apparatus to: generating a first frame associated with a timestamp; outputting the first frame for transmission to a wireless node as part of a ranging procedure; and Signaling including information about a transmit impulse response of the first frame is output for transmission. 2 . The apparatus of claim 1 , wherein the information is signaled via the first frame.

3. The apparatus of claim 2, wherein the first frame comprises: Fine Time Measurement (FTM) frame; Acknowledgement (ACK) frame; or Location Measurement Report (LMR) frame.

4. The apparatus of claim 1 , wherein outputting signaling including information about the transmit impulse response of the first frame for transmission comprises: After the first frame is output for transmission, the information is output via a second frame for transmission.

5. The device according to claim 4, wherein: The first frame includes an acknowledgement frame output for transmission as part of a sounding sequence; and The second frame is output for transmission after the sounding sequence.

6. The apparatus of claim 5, wherein the second frame includes information about a transmit impulse response of a plurality of acknowledgement frames as part of the sounding sequence.

7. The apparatus of claim 6, wherein the one or more processors are configured to execute the processor-executable instructions and cause the apparatus to: obtaining signaling indicating a reception timestamp of each of the acknowledgment frames as received at the wireless node as part of the ranging procedure; obtaining, after the sounding sequence, an indication of a residual in each of the received timestamps; adjusting the reception timestamp based on the indication of the residual; as well as calculating a round trip time (RTT) based on the adjusted receive timestamp as part of the ranging procedure; as well as A frame having a value determined based on the calculated RTT is output.

8. The apparatus of claim 1, wherein the one or more processors are configured to execute the processor-executable instructions and cause the apparatus to: obtaining a second frame from the wireless node; estimating a reception timestamp based on the second frame; obtaining information about a transmit impulse response of the second frame; as well as The estimated receive timestamp is adjusted based on the information about the transmit impulse response of the second frame.

9. The apparatus of claim 8, wherein the one or more processors are configured to execute the processor-executable instructions and cause the apparatus to output signaling of third information regarding the residual in the estimated received timestamp for transmission.

10. The apparatus of claim 9, wherein the information about the residual in the estimated received timestamp is signaled via: the first frame; or Location Measurement Report (LMR) frame.

11. A device, comprising: a memory including processor-executable instructions; and one or more processors configured to execute the processor-executable instructions and cause the apparatus to: Obtaining a first frame from a wireless node as part of a ranging procedure; estimating a timestamp based on the first frame; obtaining information about a transmit impulse response of the first frame; adjusting an estimated timestamp of the first frame based on the information about the transmit impulse response of the first frame; as well as A frame having a value determined based on the adjusted estimated timestamp is output as part of the ranging procedure. The apparatus of claim 11 , wherein the information is obtained via the first frame.

13. The apparatus of claim 12, wherein the first frame comprises: Fine Time Measurement (FTM) frame; Acknowledgement (ACK) frame; or Location Measurement Report (LMR) frame.

14. The device according to claim 11, wherein: Obtaining information about the transmit impulse response of the first frame includes: obtaining the information via a second frame after obtaining the first frame; The first frame comprises an acknowledgment frame obtained as part of a sounding sequence; and The second frame is acquired after the sounding sequence.

15. The apparatus of claim 14, wherein the second frame includes information about a transmit impulse response of a plurality of acknowledgement frames as part of the sounding sequence.

16. The apparatus of claim 15, wherein the one or more processors are configured to execute the processor-executable instructions and cause the apparatus to: outputting signaling indicating a reception timestamp of each of the acknowledgement frames as received at the apparatus for transmission as part of the ranging procedure; and Following the sounding sequence, an indication of a residual in each of the received timestamps is output.

17. The apparatus of claim 11, wherein the one or more processors are configured to execute the processor-executable instructions and cause the apparatus to: outputting a second frame for estimating a timestamp for transmission as part of the ranging procedure; and Information on the transmit impulse response of the second frame is output.

18. The apparatus of claim 11, wherein the one or more processors are configured to execute the processor-executable instructions and cause the apparatus to: output signaling of information about the residual in the estimated timestamp for transmission via: A second frame used to estimate the timestamp as part of a ranging procedure; or Location Measurement Report (LMR) frame.

19. The apparatus of claim 11, further comprising at least one transceiver, wherein the at least one transceiver is configured to receive the first frame, and the apparatus is configured to operate as a wireless station.

20. A wireless node, comprising: at least one transceiver; a memory including processor-executable instructions; and one or more processors configured to execute the processor-executable instructions and cause the wireless node to: generating a first frame associated with a timestamp; transmitting, via the at least one transceiver, the first frame to another wireless node as part of a ranging procedure; as well as Signaling including information about a transmit impulse response of the first frame is transmitted via the at least one transceiver.

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