Multistatic radar measurements

Abstract

The present disclosure provides systems, methods, and apparatus for multistatic radar communications, including computer programs encoded on computer storage media. In some implementations, a transmitting device may transmit a radar warning frame, followed by a codeword and one or more radar pulses, to a receiving device. These radar pulses are transmitted in several directions using beamforming. Timing information indicates a timing offset or delay between one or more codewords in a codeword sequence and the start of the radar pulse. The receiving device may detect an echo of one or more codewords in the codeword sequence and at least one of the radar pulses and determine the time when the corresponding pulse was transmitted by the transmitting device. The receiving device may compare the timing of the echo with the timing of the transmitted pulse to determine the relative distance of the object that generated the echo.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communications, and more particularly to multistatic radar measurements in wireless communication systems.

[0002] Related technical description

[0003] Radar is a ranging technology that can be used to determine the distance of an object relative to a given location. A radar system operates by transmitting and receiving electromagnetic pulses. Some of these pulses reflect from objects or surfaces along the transmission path, producing "echoes." The radar system can determine the distance to an object or surface based on the round-trip time between transmitting the pulse and receiving the echo of that pulse. In a monostatic radar system, the antenna used to transmit the pulse (the "transmitting antenna") is co-located with the antenna used to receive the echo (the "receiving antenna"). For example, the transmitting antenna and the receiving antenna are typically arranged on the same device. This allows for simple synchronization between the timing of the transmitted pulses and the timing of the received echoes, as the same device (or system) clock can be used for both.

[0004] In a multistatic radar system, the transmitting antenna is located at a considerable distance from the receiving antenna. The spatial diversity provided by the multistatic system provides high accuracy in target location and allows simultaneous observation of different aspects of the target. However, to achieve the necessary separation between the transmitting and receiving antennas, many multistatic radar systems are implemented using multiple devices without wired communication between them. For example, the transmitting antenna may be located on a transmitting device, while the receiving antenna may be located on one or more spatially diverse receiving devices (with shared or partially shared coverage areas). The transmitting device can transmit pulses in various directions, and the receiving device can detect the resulting echoes. The transmitting and receiving devices use separate clocks for timing pulse transmission and echo detection. Accordingly, a mechanism is required to synchronize the transmission of pulses by the transmitting device with the reception of echoes by the receiving device, and to exchange radar measurement information between the transmitting and receiving devices.

[0005] Overview

[0006] The systems, methods, and devices of the present disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

[0007] One innovative aspect of the subject matter described in this disclosure can be implemented as a wireless communication method. The method can be performed by a wireless communication device and can include: receiving a radar warning frame that carries timing information indicating a timing relationship between a codeword sequence and one or more pulses; detecting a codeword in the codeword sequence; determining a first time when the codeword was detected; detecting an echo of a pulse in the one or more pulses; determining a second time when the echo was detected; and determining a distance from an object to the wireless communication device based at least in part on the first time, the second time, and the timing information.

[0008] In some implementations, the radar warning frame may be a Clear to Send (CTS)-to-Self frame with a control trailer carrying the timing information. In some implementations, each codeword in the codeword sequence may include a corresponding Golay sequence. In some implementations, detecting the codeword may include tuning multiple antennas of the wireless communication device in the direction of the transmitting device. In some implementations, the one or more pulses may include a pulse sequence, and the timing information may indicate the duration of each of the one or more pulses and a delay between the detected codeword and the start of the pulse sequence. In some implementations, detecting the echo may include positioning multiple antennas of the wireless communication device in multiple directions.

[0009] In some implementations, the method may further include: calculating a time at which the pulse was transmitted based on the first time, the second time, and the timing information; and estimating a distance range associated with the object based at least in part on the second time and the calculated time. In some implementations, determining the distance to the object may include: determining an angle of arrival of the echo at the wireless communication device; and calculating the distance to the object based at least in part on the angle of arrival and the estimated distance range. In some implementations, the method may further include: transmitting feedback to the transmitting device in response to detecting the echo, wherein the feedback indicates the estimated distance range. In some other implementations, the method may further include: transmitting feedback to the transmitting device in response to detecting the echo, wherein the feedback indicates the second time.

[0010] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a wireless communication device. In some implementations, the wireless communication device may include at least one modem, at least one processor communicatively coupled to the at least one modem, and at least one memory communicatively coupled to the at least one processor and storing processor-readable code. In some implementations, execution of the processor-readable code by the at least one processor may cause the wireless communication device to perform operations including: receiving a radar warning frame carrying timing information indicating a timing relationship between a codeword sequence and one or more pulses; detecting a codeword in the codeword sequence; determining a first time at which the codeword was detected; detecting an echo of a pulse in the one or more pulses; determining a second time at which the echo was detected; and determining a distance from an object to the wireless communication device based at least in part on the first time, the second time, and the timing information.

[0011] Another innovative aspect of the subject matter described in the present disclosure can be implemented as a wireless communication method. The method can be performed by a wireless communication device and can include: transmitting a first radar warning frame to a first recipient device, the first radar warning frame carrying timing information indicating a timing relationship between a codeword sequence and one or more pulses; transmitting a first codeword of the codeword sequence in a direction of the first recipient device using beamforming; transmitting the one or more pulses in multiple directions using beamforming; receiving feedback from the first recipient device in response to transmitting the one or more pulses; and determining a distance of an object from the wireless communication device based at least in part on the feedback received from the first recipient device.

[0012] In some implementations, each codeword in the codeword sequence may include a corresponding Golay sequence. In some implementations, the first radar warning frame may be a CTS-to-Self frame having a control trailer carrying the timing information. In some implementations, the CTS-to-Self frame may be transmitted in the direction of the first receiving device using beamforming. In some implementations, the codeword sequence and the one or more pulses may be transmitted in a PPDU that includes a PHY preamble and a header.

[0013] In some implementations, determining the distance to the object may include: determining, based on the feedback, a time at which an echo of a first pulse of the one or more pulses was detected by a first receiving device; determining a departure angle of the first pulse at the wireless communication device; and calculating the distance to the object based at least in part on the departure angle, the time at which the echo was detected by the first receiving device, and the time at which the first pulse was transmitted by the wireless communication device. In some implementations, the one or more pulses may include a pulse sequence, and the timing information may indicate a duration of each of the one or more pulses and a delay between transmitting the codeword sequence and the start of the pulse sequence.

[0014] In some implementations, the method may further include: transmitting a second radar warning frame carrying the timing information to a second recipient device; transmitting a second codeword in the codeword sequence in a direction of the second recipient device using beamforming; and receiving feedback from the second recipient device in response to transmitting the one or more pulses. In some implementations, the feedback received from the first recipient device may indicate a first distance range associated with the object, and the feedback received from the second recipient device may indicate a second distance range associated with the object.

[0015] In some implementations, determining the distance to the object may include: determining a time when an echo of a first pulse in the one or more pulses is detected by the first receiving device based on feedback received from the first receiving device; and determining a time when an echo of a second pulse in the one or more pulses is detected by the second receiving device based on feedback received from the second receiving device, wherein the distance to the object is determined based on the time when the echo of the first pulse is detected by the first receiving device and the time when the echo of the second pulse is detected by the second receiving device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. It should be noted that the relative dimensions of the following drawings may not be drawn to scale.

[0018] Figure 1 A schematic diagram of an example wireless communication network is shown.

[0019] Figure 2A Example protocol data units (PDUs) that may be used for communication between an access point (AP) and several stations (STAs) are shown.

[0020] Figure 2B Shown Figure 2A Example fields in the PDU.

[0021] Figure 3 Another example PDU that may be used for communication between an AP and each of a number of STAs is shown.

[0022] Figure 4 Example physical layer convergence protocol (PLCP) protocol data units (PPDUs) that may be used for communication between an AP and several STAs are shown.

[0023] Figure 5 A block diagram of an example wireless communication device is shown.

[0024] Figure 6AA block diagram of an example access point (AP) is shown.

[0025] Figure 6B A block diagram of an example station (STA) is shown.

[0026] Figure 7 An example bistatic radar system is shown in accordance with some implementations.

[0027] Figure 8 An example multistatic radar system is shown according to some implementations.

[0028] Figure 9 Shown is a timing diagram illustrating example communications between a radar transmitter and multiple radar receivers according to some implementations.

[0029] Figure 10A A flow chart illustrating an example process for supporting wireless communications for multistatic radar measurements according to some implementations is shown.

[0030] Figure 10B A flow chart illustrating an example process for supporting wireless communications for multistatic radar measurements according to some implementations is shown.

[0031] Figure 10C A flow chart illustrating an example process for supporting wireless communications for multistatic radar measurements according to some implementations is shown.

[0032] Figure 11A A flow chart illustrating an example process for supporting wireless communications for multistatic radar measurements according to some implementations is shown.

[0033] Figure 11B A flow chart illustrating an example process for supporting wireless communications for multistatic radar measurements according to some implementations is shown.

[0034] Figure 11C A flow chart illustrating an example process for supporting wireless communications for multistatic radar measurements according to some implementations is shown.

[0035] Figure 11D A flow chart illustrating an example process for supporting wireless communications for multistatic radar measurements according to some implementations is shown.

[0036] Figure 12 A block diagram of an example radar receiver is shown, according to some implementations.

[0037] Figure 13 A block diagram of an example radar transmitter is shown, according to some implementations.

[0038] Like reference numbers and designations in the various drawings indicate like elements.

[0039] Detailed description

[0040] The following description is directed to certain implementations for the purpose of describing the innovative aspects of the present disclosure. However, one of ordinary skill in the art will readily recognize that the teachings herein can be applied in many different ways. The described implementations can be implemented in a manner that is capable of being implemented in accordance with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, the IEEE 802.15 standard, the Bluetooth Special Interest Group (SIG), or any other standard defined by the Bluetooth Special Interest Group (SIG). The described implementations may be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals in accordance with one or more of the Long Term Evolution (LTE), 3G, 4G, or 5G (New Radio (NR)) standards promulgated by the Third Generation Partnership Project (3GPP). The described implementations may be implemented in any device, system, or network capable of transmitting and receiving RF signals in accordance with one or more of the following technologies or techniques: code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), single-user (SU) multiple-input multiple-output (MIMO), and multi-user (MU) MIMO. The described implementations may also be implemented using other wireless communication protocols or RF signals suitable for use in one or more of a wireless personal area network (WPAN), a wireless local area network (WLAN), a wireless wide area network (WWAN), or an Internet of Things (IoT) network.

[0041] Various implementations generally involve synchronizing spatially diverse transmitting and receiving devices in a multistatic radar system. Some implementations specifically involve using signaling techniques and packet formats compliant with the IEEE 802.11 family of standards to perform multistatic radar measurements by one or more wireless communication devices. A WLAN can be formed by one or more access points (APs) that provide a shared wireless communication medium for use by multiple client devices, also known as stations (STAs). The fundamental building block of a WLAN compliant with the IEEE 802.11 family of standards is a basic service set (BSS) managed by the AP. Each BSS is identified by a basic service set identifier (BSSID) announced by the AP. Wireless communication devices (such as APs and STAs) communicate by transmitting and receiving electromagnetic signals in the RF spectrum. The electromagnetic signals transmitted by the transmitting device may reflect from objects and surfaces along the transmission path before reaching a remote receiving device. Accordingly, signaling techniques used in wireless communication, such as beamforming, are well-suited for multistatic radar.

[0042] In some implementations, a transmitting device (also referred to as a "radar transmitter") may transmit a radar alert frame, followed by a radar frame, to a receiving device (also referred to as a "radar receiver"). A radar frame may include a codeword sequence (also referred to as a "synchronization sequence") and one or more radar pulses. As used herein, the term "radar pulse" may refer to any wireless signal that can be used to detect objects along its transmission path based on radar technology. Radar pulses may be transmitted in multiple directions using beamforming to detect objects near the radar system. Beamforming focuses the energy of each radar pulse in a narrow direction to compensate for path loss and achieve greater range. A radar warning frame may alert the receiving device to an upcoming radar frame. In some implementations, the radar warning frame may carry timing information that can be used to synchronize the receiving device's receive (RX) clock with the transmitting device's transmit (TX) clock. For example, the timing information may indicate a timing offset or delay between one or more codewords in the codeword sequence and the start of the radar pulse. The receiving device may detect the echo of one or more codewords in the codeword sequence and at least one of these radar pulses and determine the time when the corresponding pulse was transmitted by the transmitting device. The receiving device can compare the timing of the echo with the timing of the transmitted pulse to determine the relative distance of the target object that generated the echo.

[0043] Specific implementations of the subject matter described in this disclosure can be implemented to achieve one or more of the following potential advantages. By leveraging wireless communication technologies defined by the IEEE 802.11 family of standards, aspects of the present disclosure can enable multistatic radar to be implemented within existing wireless communication systems and networks. For example, an AP (or STA) can perform the functions of a radar transmitter, while one or more STAs (or APs) can perform the functions of each radar receiver. Specifically, the radar transmitter can use beamforming techniques to transmit highly directional radar pulses, which can generate corresponding echoes when interacting with objects in the environment. The radar transmitter can use a packet format that complies with the IEEE 802.11 family of standards to convey timing and synchronization information about the radar pulses to each radar receiver. Each radar receiver can also use this packet format to provide feedback to the radar transmitter regarding the echoes. Furthermore, the multistatic radar implementation of the present disclosure adheres to the link access rules defined by the existing IEEE 802.11 standard, thereby enabling radar functionality in frequency bands commonly used for wireless communications. Accordingly, aspects of the present disclosure can enable multistatic radar functionality anywhere a WLAN is or could be deployed.

[0044] Figure 1A block diagram of an example wireless communication network 100 is shown. According to some aspects, the wireless communication network 100 may be an example of a wireless local area network (WLAN), such as a Wi-Fi network (and will be referred to as WLAN 100 hereinafter). For example, the WLAN 100 may be a network that implements at least one of the IEEE 802.11 family of standards, such as those defined by the IEEE 802.11-2016 specification or its amendments, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be. The WLAN 100 may include numerous wireless communication devices, such as an access point (AP) 102 and a plurality of stations (STAs) 104. Although only one AP 102 is shown, the WLAN network 100 may also include multiple APs 102.

[0045] Each STA 104 may also be referred to as a mobile station (MS), a mobile device, a mobile handset, a wireless handset, an access terminal (AT), a user equipment (UE), a subscriber station (SS), or a subscriber unit, among other possibilities. STA 104 may represent a variety of devices, such as a mobile phone, a personal digital assistant (PDA), other handheld devices, a netbook, a netbook computer, a tablet computer, a laptop device, a display device (e.g., a TV, a computer monitor, a navigation system, etc.), a music or other audio or stereo device, a remote control device ("remote control"), a printer, a kitchen or other home appliance, a key fob (e.g., for a passive keyless entry and start (PKES) system), and other possibilities.

[0046] A single AP 102 and the associated set of STAs 104 may be referred to as a basic service set (BSS), which is managed by the respective AP 102 . Figure 1Additionally shown is an example coverage area 106 of the AP 102, which may represent a basic service area (BSA) of the WLAN 100. A BSS may be identified to users by a service set identifier (SSID) and may be identified to other devices by a basic service set identifier (BSSID), which may be the media access control (MAC) address of the AP 102. The AP 102 periodically broadcasts a beacon frame ("beacon") including the BSSID to enable any STA 104 within wireless range of the AP 102 to "associate" or reassociate with the AP 102 to establish or maintain a corresponding communication link 108 (hereinafter also referred to as a "Wi-Fi link") with the AP 102. For example, the beacon may include an identification of a primary channel used by the corresponding AP 102 and a timing synchronization function for establishing or maintaining timing synchronization with the AP 102. The AP 102 may provide various STAs 104 in the WLAN with access to external networks via corresponding communication links 108 .

[0047] To establish a communication link 108 with the AP 102, each STA 104 is configured to perform passive or active scanning operations ("scans") on frequency channels in one or more frequency bands (eg, 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz bands). To perform a passive scan, a STA 104 listens for beacons transmitted by a corresponding AP 102 at periodic time intervals, referred to as target beacon transmission times (TBTTs), measured in time units (TUs), where one TU may be equal to 1024 microseconds (μs). To perform an active scan, a STA 104 generates probe requests and sequentially transmits these probe requests on each channel to be scanned, and listens for probe responses from the AP 102. Each STA 104 may be configured to identify or select an AP 102 with which to associate based on scan information obtained through passive or active scanning, and to perform authentication and association operations to establish a communication link 108 with the selected AP 102. The AP 102 assigns an association identifier (AID) to the STA 104 at the end of the association operation, and the AP 102 uses the AID to track the STA 104.

[0048] As wireless networks become increasingly common, a STA 104 may have the opportunity to select one of many B14s within range of the STA or multiple APs 102 that together form an extended service set (ESS) (including multiple connected B14s). Extended network stations associated with a WLAN 100 may be connected to a wired or wireless distribution system that allows multiple APs 102 to be connected in such an ESS. In this way, a STA 104 may be covered by more than one AP 102 and may associate with different APs 102 at different times for different transmissions. Additionally, after associating with an AP 102, the STA 104 may be configured to periodically scan its surroundings to find a more suitable AP 102 to associate with. For example, a STA 104 that is moving relative to its associated AP 102 may perform a "roaming" scan to find another AP 102 with more desirable network characteristics, such as a greater received signal strength indicator (RSSI) or reduced traffic load.

[0049] In some cases, STAs 104 may form a network without an AP 102 or other equipment other than the STAs 104 themselves. One example of such a network is an ad hoc network (or wireless ad hoc network). An ad hoc network may alternatively be referred to as a mesh network or a peer-to-peer (P2P) network. In some cases, an ad hoc network may be implemented within a larger wireless network, such as WLAN 100. In such an implementation, while STAs 104 may be able to communicate with each other via AP 102 using communication link 108, STAs 104 may also communicate directly with each other via direct wireless link 110. In addition, two STAs 104 may communicate via direct communication link 110 regardless of whether they are associated with and served by the same AP 102. In such an ad hoc system, one or more STAs 104 may assume the role played by AP 102 in a BSS. Such STAs 104 may be referred to as group owners (GOs) and may coordinate transmissions within the ad hoc network. Examples of direct wireless link 110 include a Wi-Fi Direct connection, a connection established by using a Wi-Fi Tunneled Direct Link Setup (TDLS) link, and other P2P group connections.

[0050] The AP 102 and the STA 104 may function and communicate in accordance with the IEEE 802.11 family of standards (such as those defined by the IEEE 802.11-2016 specification or its amendments, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be) (via corresponding communication links 108). These standards define WLAN radio and baseband protocols for the PHY and media access control (MAC) layers. The AP 102 and the STA 104 transmit and receive wireless communications (hereinafter also referred to as "Wi-Fi communications") to and from each other in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs). The AP 102 and STA 104 in the WLAN 100 can transmit PPDUs on an unlicensed spectrum, which can be a portion of the spectrum that includes frequency bands traditionally used by Wi-Fi technology, such as the 2.4 GHz band, the 5 GHz band, the 60 GHz band, the 3.6 GHz band, and the 900 MHz band. Some implementations of the AP 102 and STA 104 described herein can also communicate in other frequency bands, such as the 6 GHz band, that can support both licensed and unlicensed communications. The AP 102 and STA 104 can also be configured to communicate in other frequency bands, such as shared licensed bands, where multiple operators may have licenses to operate in one or more of the same or overlapping frequency bands.

[0051] Each frequency band can include multiple sub-bands or frequency channels. For example, PPDUs compliant with IEEE 802.11n, 802.11ac, and 802.11ax standard revisions can be transmitted in the 2.4 GHz and 5 GHz frequency bands, where each frequency band is divided into multiple 20 MHz channels. Thus, these PPDUs are transmitted on physical channels with a minimum bandwidth of 20 MHz, but larger channels can be formed through channel bonding. For example, a PPDU can be transmitted on a physical channel with a bandwidth of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding multiple 20 MHz channels together.

[0052] Each PPDU is a composite structure that includes a PHY preamble and a payload in the form of a PLCP service data unit (PSDU). The information provided in the preamble can be used by the receiving device to decode subsequent data in the PSDU. In instances where the PPDU is transmitted over a bonded channel, the preamble field can be replicated and transmitted in each of the multiple component channels. The PHY preamble may include both a legacy portion (or "legacy preamble") and a non-legacy portion (or "non-legacy preamble"). The legacy preamble can be used for packet detection, automatic gain control, and channel estimation, among other purposes. The legacy preamble can also generally be used to maintain compatibility with legacy devices. The format, decoding, and information provided therein of the non-legacy portion of the preamble are based on the specific IEEE 802.11 protocol to be used to transmit the payload.

[0053] Figure 2A An example protocol data unit (PDU) 200 is shown that can be used for communication between an AP and several STAs. For example, the PDU 200 can be configured as a PPDU. As shown, the PDU 200 includes a PHY preamble 202 and a PHY payload 204. For example, the PHY preamble 202 may include a legacy portion, which itself includes a legacy short training field (L-STF) 206, a legacy long training field (L-LTF) 208, and a legacy signaling field (L-SIG) 210. The PHY preamble 202 may also include a non-legacy portion (not shown). The L-STF 206 generally enables a receiving device to perform automatic gain control (AGC) and coarse timing and frequency estimation. The L-LTF 208 generally enables a receiving device to perform fine timing and frequency estimation, and also to estimate the wireless channel. The L-SIG 210 generally enables a receiving device to determine the duration of the PDU and use the determined duration to avoid transmitting over the PDU. For example, the L-STF 206, L-LTF 208, and L-SIG 210 may be modulated according to a binary phase shift keying (BPSK) modulation scheme. The payload 204 may be modulated according to a BPSK modulation scheme, a quadrature BPSK (Q-BPSK) modulation scheme, a quadrature amplitude modulation (QAM) modulation scheme, or another appropriate modulation scheme. The payload 204 may generally carry higher layer data (e.g., in the form of a media access control (MAC) protocol data unit (MPDU) or an aggregated MPDU (A-MPDU)).

[0054] Figure 2B Show Figure 2A2. Example L-SIG field 210 in a PDU of FIG. L-SIG 210 includes a data rate field 212, reserved (R) bits 214, a length field 216, parity (P) bits 218, and a tail field 220. Data rate field 212 indicates the data rate (note that the data rate indicated in data rate field 212 may not be the actual data rate of the data carried in payload 204). Length field 216 indicates the packet length, for example, in bytes. Parity bits 218 are used to detect bit errors. Tail field 220 includes tail bits, which are used by a receiving device to terminate the operation of a decoder (e.g., a Viterbi decoder). The receiving device uses the data rate and length indicated in data rate field 212 and length field 216 to determine the packet duration, for example, in microseconds (μs).

[0055] Figure 3 Another example PDU 300 that can be used for communication between an AP and several STAs is shown. For example, PDU 300 can be configured as a PPDU. As shown, PDU 300 includes a PHY preamble 301, a PHY header 306, a data field 308, and a beamforming training field (TRN) 310. PHY preamble 301 may include a short training field (STF) 302 and a channel estimation field (CE) 304. STF 302 generally enables a receiving device to detect PDU 300 and perform automatic gain control (AGC) and coarse timing and frequency estimation. CE field 304 can be used by the receiving device to perform channel estimation. PHY header 306 includes information associated with data field 308, including, for example, modulation and coding scheme (MCS), length, or checksum. Data field 308 may include payload data and padding (if any).

[0056] In high-frequency (such as 60 GHz or millimeter wave (mmWave)) wireless communication systems (such as IEEE 802.11ad or 802.11ay amendments that comply with the IEEE 802.11 standard), communications can be beamformed using phased array antennas at the transmitter and receiver. Beamforming generally refers to a technique by which a transmitting device and a receiving device adjust the transmit or receive antenna settings to achieve a desired link budget for subsequent communications. A procedure for adapting the transmit and receive antennas (referred to as beamforming training) can be initially performed to establish a link between the transmitting device and the receiving device, and can also be performed periodically to maintain a quality link using optimized transmit and receive beams.

[0057] The TRN field 310 may be used for beamforming training. More specifically, the TRN field 310 may be used by the receiving device to tune or configure its antenna for directional beamforming. For example, based on the TRN field 310, the receiving device may determine which antenna sectors (of a phased array antenna) should be used to transmit and receive the corresponding beam. The TRN field 310 may include an AGC subfield 312 and one or more TRN subfields 314. The AGC subfield 312 enables the receiving device to readjust its AGC settings to receive the TRN subfield 314. The TRN subfield 314 may include a Golay sequence, which may be used to determine the antenna weight vector (AWV) to be applied to the transmit antenna or receive antenna for beamforming. For example, the AWV may describe the amplitude or phase to be applied to each transmit or receive antenna. The number of TRN subfields 314 may vary depending on whether the TRN field 310 is used for transmit AWV training or receive AWV training.

[0058] Figure 4 An example PPDU 400 is shown that can be used for communication between an AP 102 and several STAs 104. As described above, each PPDU 400 includes a PHY preamble 402 and a PSDU 404. Each PSDU 404 can carry one or more MAC protocol data units (MPDUs). For example, each PSDU 404 can carry an aggregated MPDU (A-MPDU) 408, which includes an aggregation of multiple A-MPDU subframes 406. Each A-MPDU subframe 406 can include a MAC delimiter 410 and a MAC header 412, preceding an accompanying MPDU 414, which includes the data portion ("payload" or "frame body") of the A-MPDU subframe 406. The MPDU 414 can carry one or more MAC service data unit (MSDU) subframes 416. For example, the MPDU 414 can carry an aggregated MSDU (A-MSDU) 418, which includes multiple MSDU subframes 416. Each MSDU subframe 416 includes a corresponding MSDU 420 followed by a subframe header 422 .

[0059] Referring back to the A-MPDU subframe 406, the MAC header 412 may include several fields containing information defining or indicating characteristics or attributes of the data encapsulated within the frame body 414. The MAC header 412 also includes several fields indicating the address of the data encapsulated within the frame body 414. For example, the MAC header 412 may include a combination of a source address, a transmitter address, a receiver address, or a destination address. The MAC header 412 may include a frame control field containing control information. The frame control field specifies the frame type, such as a data frame, a control frame, or a management frame. The MAC header 412 may further include a duration field indicating the duration from the end of the PPDU until the end of the acknowledgement (ACK) (e.g., a block ACK (BA) in the case of an A-MPDU) for the last PPDU to be transmitted by the wireless communication device. The duration field is used to reserve the wireless medium for the indicated duration, thereby establishing a NAV. Each A-MPDU subframe 406 may also include a frame check sequence (FCS) field 424 for error detection. For example, the FCS field 416 may include a cyclic redundancy check (CRC).

[0060] As described above, the AP 102 and the STAs 104 may support multi-user (MU) communications; that is, concurrent transmissions from one device to each of multiple devices (e.g., multiple simultaneous downlink (DL) communications from the AP 102 to the corresponding STAs 104), or concurrent transmissions from multiple devices to a single device (e.g., multiple simultaneous uplink (UL) transmissions from the corresponding STAs 104 to the AP 102). To support MU transmissions, the AP 102 and the STAs 104 may utilize multi-user multiple-input multiple-output (MU-MIMO) and multi-user orthogonal frequency-division multiple access (MU-OFDMA) techniques.

[0061] In the MU-OFDMA scheme, the available spectrum of a wireless channel can be divided into multiple resource units (RUs), each of which includes a number of different frequency subcarriers ("tones"). Different RUs can be allocated or assigned to different STAs 104 by the AP 102 at a specific time. The size and distribution of the RUs can be referred to as RU allocation. In some implementations, RUs can be allocated in 2 MHz intervals, and thus, the smallest RU can include 26 tones including 24 data tones and 2 pilot tones. Therefore, in a 20 MHz channel, up to 9 RUs (such as 2 MHz, 26 tone RUs) can be allocated (because some tones are reserved for other purposes). Similarly, in a 160 MHz channel, up to 74 RUs can be allocated. Larger 52 tone, 106 tone, 242 tone, 484 tone, and 996 tone RUs can also be allocated. Adjacent RUs may be separated by a null subcarrier, such as a DC subcarrier, for example, to reduce interference between adjacent RUs, reduce receiver DC offset, and avoid transmit center frequency leakage.

[0062] For UL MU transmissions, the AP 102 may transmit a trigger frame to initiate and synchronize UL MU-OFDMA or UL MU-MIMO transmissions from multiple STAs 104 to the AP 102. Such a trigger frame may thereby enable multiple STAs 104 to send UL traffic concurrently in time to the AP 102. The trigger frame may address one or more STAs 104 by corresponding association identifiers (AIDs) and may assign one or more RUs to each AID (and thus each STA 104) that may be used to transmit UL traffic to the AP 102. The AP may also specify one or more random access (RA) RUs that unscheduled STAs 104 may contend for.

[0063] Figure 5 1 shows a block diagram of an example wireless communication device 500. In some implementations, the wireless communication device 500 may be a STA (such as the one described above with reference to FIG. Figure 1 In some implementations, the wireless communication device 500 may be an example of a device for an AP (such as one of the STAs 104 described above). Figure 1 The wireless communication device 500 is an example of a device in the described AP 102. The wireless communication device 500 is capable of transmitting (or outputting for transmission) and receiving wireless communications (e.g., in the form of wireless packets). For example, the wireless communication device can be configured to transmit and receive packets in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs) and media access control (MAC) protocol data units (MPDUs) that comply with the IEEE 802.11 standard (such as the standard defined by the IEEE 802.11-2016 specification or its amendments, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be).

[0064] The wireless communication device 500 may be or may include a chip, system on chip (SoC), chipset, package, or device that includes one or more modems 502 (e.g., Wi-Fi (IEEE 802.11 compliant) modems). In some implementations, the one or more modems 502 (collectively, “modems 502”) additionally include a WWAN modem (e.g., a 3GPP 4G LTE or 5G compatible modem). In some implementations, the wireless communication device 500 also includes one or more radios 504 (collectively, “radios 504”). In some implementations, the wireless communication device 506 further includes one or more processors, processing blocks, or processing elements 506 (collectively, “processors 506”) and one or more memory blocks or elements 508 (collectively, “memory 508”).

[0065] The modem 502 may include an intelligent hardware block or device (e.g., such as an application specific integrated circuit (ASIC)). The modem 502 is generally configured to implement the PHY layer. For example, the modem 502 is configured to modulate packets and output the modulated packets to the radio 504 for transmission on the wireless medium. Similarly, the modem 502 is configured to obtain modulated packets received by the radio 504 and demodulate these packets to provide demodulated packets. In addition to the modulator and demodulator, the modem 502 may further include digital signal processing (DSP) circuitry, automatic gain control (AGC), an encoder, a decoder, a multiplexer, and a demultiplexer. For example, when in transmit mode, data obtained from the processor 506 is provided to an encoder, which encodes the data to provide coded bits. The coded bits are then mapped to points in the modulation constellation (using the selected MCS) to provide modulated symbols. The modulated symbols may then be mapped to a number (N SS ) spatial streams or several (N STS ) space-time streams. The modulated symbols in the corresponding spatial streams or space-time streams may then be multiplexed, transformed via an inverse fast Fourier transform (IFFT) block, and then provided to the DSP circuitry for Tx windowing and filtering. The digital signal may then be provided to a digital-to-analog converter (DAC). The resulting analog signal may then be provided to an upconverter and ultimately to the radio 504. In implementations involving beamforming, the modulated symbols in the corresponding spatial streams may be precoded via a steering matrix before being provided to the IFFT block.

[0066] When in receive mode, a digital signal received from radio 504 is provided to a DSP circuitry configured to acquire the received signal, for example, by detecting the presence of a signal and estimating initial timing and frequency offset. The DSP circuitry is further configured to digitally condition the digital signal, for example, using channel (narrowband) filtering, analog impairment conditioning (such as correcting I / Q imbalance), and applying digital gain to ultimately acquire a narrowband signal. The output of the DSP circuitry can then be fed to an AGC, which is configured to use information extracted from the digital signal (e.g., in one or more received training fields) to determine an appropriate gain. The output of the DSP circuitry is also coupled to a demodulator, which is configured to extract modulated symbols from the signal and, for example, calculate a log-likelihood ratio (LLR) for each bit position of each subcarrier in each spatial stream. The demodulator is coupled to a decoder, which can be configured to process the LLRs to provide decoded bits. The decoded bits from all spatial streams are then fed to a demultiplexer for demultiplexing. The demultiplexed bits may then be descrambled and provided to the MAC layer (processor 506) for processing, evaluation, or interpretation.

[0067] The radio 504 generally includes at least one radio frequency (RF) transmitter (or "transmitter chain") and at least one RF receiver (or "receiver chain"), which can be combined into one or more transceivers. For example, the RF transmitter and receiver may include various DSP circuitry, including at least one power amplifier (PA) and at least one low noise amplifier (LNA), respectively. The RF transmitter and receiver may, in turn, be coupled to one or more antennas. For example, in some implementations, the wireless communication device 500 may include or be coupled to multiple transmit antennas (each with a corresponding transmit chain) and multiple receive antennas (each with a corresponding receive chain). The symbols output from the modem 502 are provided to the radio 504, which then transmits the symbols via the coupled antennas. Similarly, the symbols received via the antennas are acquired by the radio 504, which then provides the symbols to the modem 502.

[0068] The processor 506 may comprise an intelligent hardware block or device designed to perform the functions described herein, such as, for example, a processing core, a processing block, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD) (such as a field-programmable gate array (FPGA)), discrete gate or transistor logic, discrete hardware components, or any combination thereof. The processor 506 processes information received via the radio 504 and the modem 502, and processes information to be output by the modem 502 and the radio 504 for transmission over the wireless medium. For example, the processor 506 may implement the control plane and MAC layer, which are configured to perform various operations related to the generation and transmission of MPDUs, frames, or packets. The MAC layer is configured to perform or facilitate frame encoding and decoding, spatial multiplexing, space-time block coding (STBC), beamforming, and OFDMA resource allocation, among other operations or techniques. In some implementations, the processor 506 may generally control the modem 502 to cause the modem to perform the various operations described above.

[0069] The memory 504 may include tangible storage media such as random access memory (RAM) or read-only memory (ROM), or a combination thereof. The memory 504 may also store non-transitory processor or computer-executable software (SW) code containing instructions that, when executed by the processor 506, cause the processor to perform various operations for wireless communication described herein, including the generation, transmission, reception, and interpretation of MPDUs, frames, or packets. For example, the various functions of the various components disclosed herein or the various blocks or steps of the methods, operations, processes, or algorithms disclosed herein may be implemented as one or more modules of one or more computer programs.

[0070] Figure 6A 6 shows a block diagram of an example AP 602. For example, the AP 602 may be a reference Figure 1 An example implementation of the AP 102 is described. The AP 602 includes a wireless communication device (WCD) 610. For example, the wireless communication device 610 may be a reference Figure 51. An example implementation of the wireless communication device 500 is described. AP 602 also includes multiple antennas 620 coupled to the wireless communication device 610 for transmitting and receiving wireless communications. In some implementations, AP 602 additionally includes an application processor 630 coupled to the wireless communication device 610, and a memory 640 coupled to the application processor 630. AP 602 further includes at least one external network interface 650 that enables AP 602 to communicate with a core network or backhaul network to gain access to an external network, including the Internet. For example, external network interface 650 may include one or both of a wired (e.g., Ethernet) network interface and a wireless network interface (such as a WWAN interface). Components of the aforementioned components may communicate with other components of these components directly or indirectly over at least one bus. AP 602 further includes a housing that encloses the wireless communication device 610, the application processor 630, the memory 640, and at least portions of the antennas 620 and the external network interface 650.

[0071] Figure 6B 604. For example, STA 604 may be a reference Figure 1 104. The STA 604 includes a wireless communication device 615. For example, the wireless communication device 615 may be a reference Figure 5 1. Example implementation of the wireless communication device 500 described. STA 604 also includes one or more antennas 625 coupled to the wireless communication device 615 for transmitting and receiving wireless communications. STA 604 additionally includes an application processor 635 coupled to the wireless communication device 615, and a memory 645 coupled to the application processor 635. In some implementations, STA 604 further includes a user interface (UI) 655 (such as a touch screen or keyboard) and a display 665, which can be integrated with the UI 655 to form a touch screen display. In some implementations, STA 604 can further include one or more sensors 675 (such as one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, or altitude sensors, for example). Components of the aforementioned components can communicate directly or indirectly with other components of these components over at least one bus. STA 604 further includes a housing that encloses the wireless communication device 615, the application processor 635, the memory 645, and at least portions of the antennas 625, the UI 655, and the display 665.

[0072] As described above, signaling techniques used in wireless communications (such as beamforming) are well-suited for multistatic radar. In a multistatic radar system, the transmitting antenna is located at a considerable distance from the receiving antenna. The spatial diversity provided by the multistatic system provides high accuracy in target location and allows simultaneous observation of different aspects of the target. However, to achieve the necessary separation between the transmitting and receiving antennas, many multistatic radar systems are implemented using multiple devices without wired communication between them. For example, the transmitting antenna can be placed on the transmitting device, while the receiving antenna can be placed on one or more spatially diverse receiving devices (which have shared or partially shared coverage areas). The transmitting device can transmit pulses in various directions, and the receiving device can detect the resulting echoes. The transmitting and receiving devices use separate clocks for timing pulse transmission and echo detection.

[0073] In some implementations, a transmitting device may transmit a radar warning frame, followed by a radar frame, to one or more receiving devices. A radar frame may include a codeword sequence and one or more radar pulses. As used herein, the term "radar pulse" may refer to any wireless signal that can be used to detect objects along its transmission path based on radar technology. A radar warning frame may alert each receiving device of an upcoming radar frame. Radar pulses may be transmitted in multiple directions using beamforming to detect target objects near the radar system. Beamforming focuses the energy of each radar pulse in a narrow direction to compensate for path loss and achieve greater range. In some implementations, a radar warning frame may carry timing information that can be used to synchronize the receive (RX) clock of each receiving device with the transmit (TX) clock of the transmitting device. For example, the timing information may indicate a timing offset or delay between one or more codewords in the codeword sequence and the start of the radar pulse. Each receiving device may detect the echo of one or more codewords in the codeword sequence and at least one of the radar pulses and determine the time when the corresponding pulse was transmitted by the transmitting device. Each receiving device can compare the timing of the echo with the timing of the transmitted pulse to determine the relative distance of the target object that generated the echo.

[0074] Figure 7 An example bistatic radar system 700 is shown according to some implementations. The bistatic radar system 700 includes a radar transmitter (RTX) 710 and a radar receiver (RRX) 720. The radar transmitter 710 and the radar receiver 720 are spatially separated by a baseline (L). In some implementations, the radar transmitter 710 may be Figure 1 AP 102 or Figure 6A An example of an AP 602 and a radar receiver 720 may be Figure 1 STA 104 or Figure 6BAn example of STA 604.

[0075] Radar transmitter 710 is configured to transmit radar pulses 712 in several directions. Each of these pulses 712 may be a beamformed RF signal having a specific width and directionality. Objects or surfaces along the path of any of these pulses 712 may reflect or scatter the pulse 712. The reflected pulse may be referred to as an "echo" of the pulse from which it originated. Figure 7 In the example of FIG, target object 701 is located along the path of one of radar pulses 712. Radar pulse 712(i) incident on target object 701 is reflected as echo 722. Figure 7 As shown in FIG, echo 722 is reflected in the direction of radar receiver 720. In some implementations, radar receiver 720 may determine the direction of radar receiver 720 based at least in part on a baseline distance L between radar transmitter 710 and radar receiver 720, an angle of arrival (θ R ) and the flight time (τ) of the incident pulse 712 (i) transmitted from the radar transmitter 710 to the radar receiver 720 to determine the distance (R R ). More specifically, the distance R R It can be calculated according to formula 1.

[0076]

[0077] where R T +R R represents the combined distance from target object 701 to each of radar transmitter 710 and radar receiver 720. Figure 7 As shown in T +R R The range 702 (in the shape of an ellipse) around the radar transmitter 710 and the radar receiver 720 where the target object 701 may be located is defined. More specifically, it can be calculated according to Equation 2 as a function of the baseline (L), the flight time of the reflected pulse (τ), and the propagation speed of the radar pulse (c p ) to calculate R T +R R .

[0078] R T +R R =c p τ+L (2)

[0079] Refer to Equations 1 and 2, baseline L and propagation velocity c prepresents a fixed or preconfigured value inherent to radar system 700. The angle of arrival θ may be determined based on the time difference of arrival (TDOA) of echo 722 between different receiving antennas of radar receiver 720 or based on the antenna sector (corresponding to a preset beam of a phased array antenna) used by radar receiver 720 to receive echo 722. R However, in order to calculate the time of flight τ, the radar receiver 720 must have knowledge of the time at which the incident pulse 712(i) is transmitted at the receiver's location. More specifically, the time of flight (T) of the incident pulse can be calculated according to Equation 3. 脉冲 ) and the echo receiving time (T 回波 ) to calculate the flight time τ.

[0080] τ=T 回波 -T 脉冲 (3)

[0081] Because the radar transmitter 710 and the radar receiver 720 are implemented in (or correspond to) separate wireless communication devices, the radar transmitter 710 may need to communicate the transmission timing T of the incident pulse to the radar receiver 720. 脉冲 However, because radar transmitter 710 transmits pulses 712 in several directions, radar transmitter 710 may not know which of these pulses 712 is incident on target object 701. Accordingly, radar transmitter 710 may need to communicate the timing of each of these pulses 712 to radar receiver 720, and radar receiver 720 may need to determine which of these pulses 712 resulted in echo 722. Aspects of the present disclosure recognize that a packet format according to the IEEE 802.11 standard may be well suited for communicating such timing information (T 脉冲 ).

[0082] In some implementations, radar transmitter 710 may transmit a radar warning frame followed by a codeword sequence to radar receiver 720 prior to transmitting radar pulse 712. The radar warning frame may warn radar receiver 720 of the upcoming radar pulse 712. In some aspects, the radar warning frame may include timing information that may be used to synchronize a receiver (RX) clock of radar receiver 720 with a transmit (TX) clock of radar transmitter 710. For example, the timing information may indicate a timing offset or delay between one or more codewords in the codeword sequence and the start of transmission of radar pulse 712. Thus, upon detecting one or more codewords in the codeword sequence and a subsequent echo 722, radar receiver 720 may determine the time at which incident pulse 712(i) was transmitted by radar transmitter 710. Radar receiver 720 may determine the timing T of the echo. 回波 The timing of the transmitted pulse T脉冲 Compare to determine the distance R of the target object 701 R (such as described with respect to Equations 1-3).

[0083] In some implementations, the radar transmitter 710 may also determine its relative distance R to the target object 701. T For example, in some aspects, radar receiver 720 may feed back timing information to radar transmitter 710. The timing information may include the timing T of the echo. 回波 , the timing of the transmitted pulse T 脉冲 , or time of flight τ. Radar transmitter 710 may then determine the time of flight based at least in part on the angle of departure θ of incident pulse 712(i). T To calculate the distance R T For example, the radar transmitter 710 can T Substitute the arrival angle θ into Equation 1 R To calculate the distance R T Radar transmitter 710 may determine the departure angle θ based on the antenna sector (corresponding to a predetermined beam of the phased array antenna) used by radar transmitter 710 to transmit incident pulse 712(i). T .

[0084] Figure 8 An example multistatic radar system 800 is shown according to some implementations. The multistatic radar system 800 includes a radar transmitter RTX and a plurality of spatially diverse radar receivers RRX1 and RRX2. Figure 8 In the example shown in FIG, two radar receivers RRX1 and RRX2 are shown, but in actual implementation, the multistatic radar system 800 may include any number of radar receivers. The radar transmitter RTX is spatially separated from the radar receivers RRX1 and RRX2 by baseline distances L1 and L2, respectively. In some implementations, the radar transmitter RTX may be Figure 1 AP 102 or Figure 6A An example of an AP 602, and each of radar receivers RRX1 and RRX2 may be Figure 1 STA 104 or Figure 6B An example of STA 604.

[0085] In some implementations, radar transmitter RTX may transmit radar warning (RA) frames 812 and 814 to radar receivers RRX1 and RRX2, respectively. For example, first radar warning frame 812 may be transmitted in the direction of first radar receiver RRX1 using beamforming, and second radar warning frame 814 may be transmitted in the direction of second radar receiver RRX2 using beamforming. In some implementations, each of radar warning frames 812 and 814 may be a Clear to Send (CTS-to-Self) frame as defined, for example, by the IEEE 802.11ay revision of the 802.11 standard. Radar warning frames 812 and 814 may warn respective radar receivers RRX1 and RRX2 of the upcoming radar frame 810. In some aspects, radar warning frames 812 and 814 may carry timing information that may be used to synchronize the RX clocks in radar receivers RRX1 and RRX2, respectively, with the TX clock of radar transmitter RTX. In some other aspects, radar warning frames 812 and 814 may indicate pulse separations or durations between successive pulses P1 - P4 .

[0086] In some implementations, radar frame 810 may include a codeword sequence (not shown for simplicity) followed by a radar pulse sequence P1-P4. Figure 9 As described in more detail, the codeword sequence can be used by radar receivers RRX1 and RRX2 to calculate the relative start time of the pulse sequence P1-P4. For example, the timing information included in the first radar warning frame 812 can indicate a timing offset or delay between one or more codewords in the codeword sequence and the start of the pulse sequence. After detecting one or more codewords in the codeword sequence, the first radar receiver RRX1 can determine the start time of the pulse sequence relative to its own internal clock based on the timing information provided in the first radar warning frame 812. Similarly, the timing information included in the second radar warning frame 814 can indicate a timing offset or delay between one or more portions of the codeword sequence and the start of the pulse sequence. After detecting one or more codewords in the codeword sequence, the second radar receiver RRX2 can determine the start time of the pulse sequence relative to its own internal clock based on the timing information provided in the second radar warning frame 814.

[0087] Each of the pulses P1-P4 may be a beamformed RF signal having a specific width and directionality. Figure 8 In the example of FIG, four radar pulses P1-P4 are shown, but in actual implementations, radar frame 810 may include any number of radar pulses. An object or surface along the trajectory of any of pulses P1-P4 may reflect or scatter the pulse, thereby generating an echo. Figure 8 In the example shown in FIG, a target object 801 is located along the path of two radar pulses P2 and P3. The pulses P2 and P3 incident on the target object 801 are reflected as echoes P2 and P3, respectively.E and P3 E .like Figure 8 As shown in the figure, the first echo P2 E is reflected in the direction of the first radar receiver RRX1, and the second echo P3 E is reflected in the direction of the second radar receiver RRX2. In some implementations, radar receivers RRX1 and RRX2 can detect echo P2 based on the change of channel impulse response (CIR). E and P3 E For example, each of radar receivers RRX1 and RRX2 may detect an incoming echo when the CIR measured by that radar receiver reaches a peak or exceeds a threshold energy level.

[0088] In some implementations, each of radar receivers RRX1 and RRX2 may calculate a corresponding distance (R R For example, each of radar receivers RRX1 and RRX2 may calculate a corresponding echo (P2) based at least in part on the timing information included in radar warning frames 812 and 814 and the codeword sequence of radar frame 810. E or P3 E ) of the flight time (τ). As described above, each of radar receivers RRX1 and RRX2 can use the timing information and the codeword sequence to determine the relative start time of the pulse sequence. In some aspects, radar receivers RRX1 and RRX2 can determine which of pulses P1-P4 caused the detected echo P2 based on the start time of the pulse sequence and the pulse duration. E and P3 E For example, the first radar receiver RRX1 may be connected to the first echo P2 due to the second pulse P2 in the pulse sequence. E P2 is determined by the temporal proximity of E is the reflection of P2. Similarly, the second radar receiver RRX2 can be detected by the third pulse P3 in the pulse sequence and the second echo P3 E P3 is determined by the temporal proximity of E is a reflection of P3. In some other aspects, pulses P1-P4 may be encoded with information (such as a unique Golay sequence) that can be used by the receiving devices RRX1 and RRX2 to identify the destination.

[0089] In the marked result echo P2 E and P3 EAfter the incident pulses P2 and P3 are received, the radar receivers RRX1 and RRX2 can respectively determine the time when the incident pulses P2 and P3 are transmitted by the radar transmitter RTX. For example, the communication from the radar transmitter RTX to the radar receivers RRX1 and RRX2 respectively experiences a propagation speed (c) based on the wireless signal between the devices. p ) and the propagation delays of distances L1 and L2. Since the propagation speed and distance are known or fixed quantities, each of radar receivers RRX1 and RRX2 can also know its corresponding propagation delay. Accordingly, each of radar receivers RRX1 and RRX2 can be dependent on the timing (T) of the transmitted pulse at the radar transmitter relative to the radar receiver according to Equation 4. 脉冲，RX ) and propagation delay to calculate the timing of the transmitted pulse (T 脉冲，TX ).

[0090] T 脉冲，TX =T 脉冲，RX - Propagation delay (4)

[0091] T 脉冲，TX Substitute T in Equation 3 into Equation 4 脉冲 ,get:

[0092] τ=T 回波 -T 脉冲，RX + Propagation Delay (5)

[0093] Referring to Equation 5, each of radar receivers RRX1 and RRX2 can calculate the flight time τ based on the following: the time T when the echo is detected 回波 , corresponding to the time T at which the pulse is transmitted relative to the radar receiver 脉冲，RX (as determined based on the timing information included in the radar warning frame 812 or 814 and the codeword sequence in the radar frame 810), and the propagation delay between the radar receiver and the radar transmitter RTX. In some implementations, each of the radar receivers RRX1 and RRX2 can use its calculated flight time τ to determine the relative distance (R ) to the target object 801 (according to Equations 1 and 2). R ).

[0094] In some implementations, the radar transmitter RTX may determine its relative distance (R T ). For example, in some aspects, one or more of the radar receivers RRX1 and RRX2 may feed back timing information to the radar transmitter RTX. The timing information may include the timing T of the echo. 回波 , the timing of the transmitted pulse T 脉冲，RX or T 脉冲，TX , or time of flight τ. In some aspects, radar transmitter RTX may be based on a departure angle θ with respect to one or more incident pulses.T To calculate the distance R T (such as about Figure 7 described).

[0095] In some other aspects, radar transmitter RTX may calculate the range of target object 801 based on the intersection of timing information received from radar receivers RRX1 and RRX2. Figure 8 As shown in FIG, the time-of-flight information (τ1) received from the first radar receiver RRX1 indicates a distance range 802 around the radar transmitter RTX and the first radar receiver RRX1, in which the target object 801 may be located. Similarly, the time-of-flight information (τ2) received from the second radar receiver RRX2 indicates a distance range 804 around the radar transmitter RTX and the second radar receiver RRX2, in which the target object 801 may be located. Accordingly, the radar transmitter RTX can determine a more accurate position or distance of the target object 801 based on the intersection of the distance range 802 and the distance range 804 (such as the intersection of the ellipses 802 and 804).

[0096] Figure 9 A timing diagram 900 illustrating example communications between a radar transmitter RTX and multiple radar receivers RRX1 and RRX2 according to some implementations is shown. In some implementations, the radar transmitter RTX and the radar receivers RRX1 and RRX2 may belong to a multistatic radar system such as Figure 8 Thus, the radar transmitter RTX and the radar receivers RRX1 and RRX2 may be respectively Figure 8 Example of a radar transmitter RTX and radar receivers RRX1 and RRX2.

[0097] At time t0, radar transmitter RTX transmits a radar warning frame 910 to a first radar receiver RRX1. In some implementations, radar warning frame 910 may be a CTS-to-Self frame in accordance with the IEEE 802.11ay revision of the IEEE 802.11 standard. For example, the receiver address (RA) field of the CTS-to-Self frame may include the address of radar transmitter RTX and may be used to indicate to the first radar receiver RRX1 the address to which feedback will be reported. Radar warning frame 910 may be transmitted in the direction of the first radar receiver RRX1 using beamforming and may warn the first radar receiver RRX1 of an upcoming radar frame 930. In some aspects, the CTS-to-Self frame may include a control trailer carrying an association identifier (AID) value associated with one or more radar receivers, including the first radar receiver RRX1.

[0098] In some implementations, the control trailer of radar warning frame 910 may further carry timing information associated with radar frame 930. In some aspects, the timing information may identify one or more unique codewords CW1 or CW2 in radar frame 930. In some other aspects, the timing information may further indicate the timing offset ΔT1 or ΔT2 between codewords CW1 or CW2, respectively, and the start of the pulse sequence (at time t8). Still further, in some aspects, the timing information may indicate the pulse spacing between successive radar pulses P1-Pn of radar frame 930.

[0099] First radar receiver RRX1 receives radar warning frame 910 at time t1 after propagation delay 901. Upon receiving radar warning frame 910, first radar receiver RRX1 may store the timing offset information and pulse spacing information included therein. First radar receiver RRX1 may proceed to listen for an upcoming radar frame 930 to be transmitted by radar transmitter RTX. For example, first radar receiver RRX1 may tune multiple receive antennas in the direction of radar transmitter RTX. More specifically, first radar receiver RRX1 may configure its receive antennas to receive beamformed signals from radar transmitter RTX. In some implementations, first radar receiver RRX1 may continue to listen for radar frame 930 until it detects one or more of codewords CW1 or CW2 of radar frame 930.

[0100] At time t2, radar transmitter RTX transmits a radar warning frame 920 to a second radar receiver RRX2. In some implementations, radar warning frame 920 may be a CTS-to-Self frame. For example, the RA field of the CTS-to-Self frame may include the address of radar transmitter RTX and may be used to indicate to the second radar receiver RRX2 the address to which feedback will be reported. Radar warning frame 920 may be transmitted in the direction of the second radar receiver RRX2 using beamforming and may warn the second radar receiver RRX2 of the upcoming radar frame 930. In some aspects, the CTS-to-Self frame may include a control trailer carrying AID values ​​associated with one or more radar receivers, including the second radar receiver RRX2.

[0101] In some implementations, the control trailer of radar warning frame 920 may further carry timing information associated with radar frame 930. In some aspects, the timing information may identify one or more of the codewords CW1 or CW2 in radar frame 930. In some other aspects, the timing information may further indicate a timing offset or delay ΔT1 or ΔT2, respectively, between codewords CW1 or CW2, and the start of the pulse sequence (at time t8). Still further, in some aspects, the timing information may indicate a pulse spacing between successive radar pulses P1-Pn of radar frame 930.

[0102] Second radar receiver RRX2 receives radar warning frame 920 at time t3 after propagation delay 902. Upon receiving radar warning frame 920, second radar receiver RRX2 may store the timing offset information and pulse spacing information included therein. Second radar receiver RRX2 may further listen for an upcoming radar frame 930 to be transmitted by radar transmitter RTX. For example, second radar receiver RRX2 may tune its multiple receive antennas in the direction of radar transmitter RTX. More specifically, second radar receiver RRX2 may configure its receive antennas to receive beamformed signals from radar transmitter RTX. In some implementations, second radar receiver RRX2 may continue to listen for radar frame 930 until it detects one or more of codewords CW1 or CW2 of radar frame 930.

[0103] Radar transmitter RTX from time t4 to t 11 The radar frame 930 is transmitted. In some implementations, the radar frame 930 may be a new type of PPDU based at least in part on a packet structure defined by an existing IEEE 802.11 standard (such as Figure 3 For example, radar frame 930 may include a preamble, a header, a codeword sequence, and one or more radar pulses P1-Pn. Figure 3 , the preamble and header of radar frame 930 may be an example of PHY preamble 301 and PHY header 306 of PDU 300, respectively. However, TRN field 310 (or TRN subfield 314) of PDU 300 may be repurposed as the codeword sequence and radar pulse sequence of radar frame 930. In some aspects, radar frame 930 may include payload data (such as Figure 3 In some other aspects, the radar frame 930 may not include any payload data. The codeword sequence may include one or more unique codewords CW1 and CW2. Figure 9 Two codewords CW1 and CW2 are shown in the example of FIG, but in actual implementation, radar frame 930 may include any number of codewords.

[0104] In some implementations, each codeword may represent a corresponding Golay sequence. Complementary Golay sequences are often used for channel estimation due to their autocorrelation properties. For example, existing versions of the IEEE 802.11 standard provide for generating beamforming training fields (such as Figure 3In some aspects, the Golay sequence can be transferred to the codeword sequence of radar frame 930. For example, different Golay sequences can be assigned or otherwise associated with different "colors" that may be known to radar receivers RRX1 and RRX2. Accordingly, each of the codewords CW1 and CW2 can represent a Golay sequence of a different color.

[0105] In some implementations, radar transmitter RTX may use beamforming to transmit portions of radar frame 930 in different directions. Figure 9 In the example of , neither the first radar receiver RRX1 nor the second radar receiver RRX2 receives the preamble or header of the radar frame 930. However, starting at time t5, at least one of the codewords CW1 or CW2 in the codeword sequence may be transmitted (using beamforming) in the direction of each of the receivers RRX1 and RRX2. More specifically, Figure 9 In the example of , the first codeword CW1 is transmitted in the direction of the first radar receiver RRX1 and the second codeword CW2 is transmitted in the direction of the second radar receiver RRX2. In some implementations, the pulses P1-Pn may be Figure 8 Thus, beamforming can be used to transmit each of the pulses P1-Pn in a different direction (such as Figure 8 ).

[0106] The first radar receiver RRX1 receives the first codeword CW1 at time t6. Upon receiving the first codeword CW1, the first radar receiver RRX1 may determine the relative start of the pulse sequence (t6+ΔT1) based on the timing offset ΔT1 associated with the first codeword CW1. In addition, the first radar receiver RRX1 may begin tuning (or positioning) its receive antenna to various directions to detect echoes of the radar pulses P1–Pn. For example, the first radar receiver RRX1 may reconfigure its receive antenna to detect echoes from objects that may be located anywhere in the vicinity of the first radar receiver RRX1. Figure 9 In the example shown in FIG, the first radar receiver RRX1 detects an echo at time t9. The first radar receiver RRX1 can further determine that the received echo is a reflection of the second pulse P2 based on the relative start of the pulse sequence (t6+ΔT1) and the pulse interval. The first radar receiver RRX1 can then determine the time of flight τ1 of the second pulse P2 (such as by using Equation 5).

[0107] In some implementations, the first radar receiver RRX1 may calculate a relative distance to the target object (such as with respect to a time of flight τ1 of the second pulse P2) at least in part. Figure 7 and Figure 8In some other implementations, the first radar receiver RRX1 may transmit feedback to the radar transmitter RTX based on the detected echo. For example, the feedback may indicate the timing of the echo, the timing of the second pulse P2 (relative to the first radar receiver RRX1 or the radar transmitter RTX), or the flight time τ1 associated with the second pulse. In such implementations, the radar transmitter RTX may use the feedback from the first radar receiver RRX1 to calculate its relative distance to the target object (such as the time of flight of the second pulse P2). Figure 7 and Figure 8 described).

[0108] The second radar receiver RRX2 receives the second codeword CW2 at time t7. Upon receiving the second codeword CW2, the second radar receiver RRX2 can determine the relative start of the pulse sequence (t7+ΔT2) based on the timing offset ΔT2 associated with the second codeword CW2. Similar to the first radar receiver RRX1, the second radar receiver RRX2 can begin to tune (or position) its receive antenna in various directions to detect the echoes of the radar pulses P1–Pn. Figure 9 In the example of FIG, the second radar receiver RRX2 is at time t 10 Detecting the echo. The second radar receiver RRX2 can further determine that the received echo is a reflection of the third pulse P3 based on the relative start of the pulse sequence (t7+ΔT2) and the pulse interval. The second radar receiver RRX2 can then determine the flight time τ2 of the third pulse P3 (such as by using Equation 5).

[0109] In some implementations, the second radar receiver RRX2 may further calculate a relative distance to the target object (such as with respect to Figure 7 and Figure 8 As described above). In some other implementations, the second radar receiver RRX2 may transmit feedback to the radar transmitter RTX based on the detected echo. For example, the feedback may indicate the timing of the echo, the timing of the third pulse P3 (relative to the second radar receiver RRX2 or the radar transmitter RTX), or the flight time τ2 associated with the third pulse. In such implementations, the radar transmitter RTX may use the feedback from the second radar receiver RRX2 to calculate its relative distance to the target object (such as the time of flight of the third pulse P3). Figure 7 and Figure 8 described).

[0110] Figure 10A A flow chart illustrating an example process 1000 for wireless communication supporting multistatic radar measurements according to some implementations is shown. In some implementations, the process 1000 may be performed by a radar receiver (such as a Figure 1 、 Figure 6A 、 Figure 7 and Figure 8 The communication may be performed by a wireless communication device operating in or within the radar receiver (e.g., STA 104, STA 604, radar receiver 720, or any of radar receivers RRX1 or RRX2).

[0111] In some implementations, process 1000 begins at block 1001 by receiving a radar warning frame that carries timing information indicating a timing relationship between a codeword sequence and one or more pulses. The radar warning frame may be received from a transmitting device. In some implementations, the one or more pulses may include a pulse sequence, and the timing information may indicate the duration of each of the one or more pulses and the delay between a detected codeword and the start of the pulse sequence. In some implementations, the radar warning frame may be a CTS-to-Self frame with a control trailer that carries the timing information.

[0112] At block 1002, process 1000 proceeds to detecting a codeword in the codeword sequence. In some implementations, detecting the codeword may include tuning multiple antennas of a wireless communication device in the direction of the transmitting device. In some implementations, each codeword in the codeword sequence may include a corresponding Golay sequence. At block 1003, process 1000 proceeds to determining a first time the codeword was detected.

[0113] At block 1004, process 1000 proceeds to detecting an echo of a pulse in the one or more pulses. In some implementations, detecting the echo may include positioning multiple antennas of the wireless communication device in multiple directions. At block 1005, process 1000 proceeds to determining a second time at which the echo is detected.

[0114] At block 1006, process 1000 proceeds to determine a distance between the object and the wireless communication device based at least in part on the first time, the second time, and the timing information. In some implementations, process 1000 may further proceed by transmitting feedback to a transmitting device in response to detecting the echo, wherein the feedback indicates the second time.

[0115] Figure 10B A flow chart illustrating an example process 1010 for wireless communication supporting multistatic radar measurements according to some implementations is shown. In some implementations, the process 1010 may be performed by a radar receiver (such as a Figure 1 、 Figure 6A 、 Figure 7 and Figure 8 The communication may be performed by a wireless communication device operating in or within the radar receiver (e.g., STA 104, STA 604, radar receiver 720, or any of radar receivers RRX1 or RRX2).

[0116] Refer to for example Figure 10A Process 1010 may begin in block 1011 after determining the second time in block 1005. In block 1011, process 1010 begins by calculating the time at which the pulse was transmitted based on the first time, the second time, and the timing information. In block 1012, process 1010 proceeds to estimating a distance range associated with the object based at least in part on the second time and the calculated time. In some implementations, process 1010 may further proceed to transmitting feedback to the transmitting device in response to detecting the echo in block 1013, wherein the feedback indicates the estimated distance range.

[0117] Figure 10C A flow chart illustrating an example process 1020 for wireless communication supporting multistatic radar measurements according to some implementations is shown. In some implementations, the process 1020 may be performed by a radar receiver (such as a Figure 1 、 Figure 6A 、 Figure 7 and Figure 8 The communication may be performed by a wireless communication device operating in or within the radar receiver (e.g., STA 104, STA 604, radar receiver 720, or any of radar receivers RRX1 or RRX2).

[0118] Refer to for example Figure 10A , process 1020 may be a more detailed implementation of the distance determination operation described in block 1006 of process 1000. In some implementations, process 1020 may be a more detailed implementation of the distance determination operation described in block 1006 of process 1000. Figure 10A Process 1020 may begin after process 1010. For example, process 1020 may begin in block 1021 after estimating the distance range in block 1012 of process 1010. In block 1021, process 1020 begins by determining the angle of arrival of the echo at the wireless communication device. In block 1022, process 1020 proceeds to calculate the distance to the object based at least in part on the angle of arrival and the estimated distance range.

[0119] Figure 11A A flow chart illustrating an example process 1100 for wireless communication supporting multistatic radar measurements according to some implementations is shown. In some implementations, the process 1100 may be performed by a radar transmitter such as a Figure 1 、 Figure 6A 、 Figure 7 and Figure 8 The communication may be performed by a wireless communication device operating on or within the radar transmitter (AP 102, AP 104, radar transmitter 710, or radar transmitter RTX).

[0120] In some implementations, process 1100 begins by transmitting a first radar warning frame to a first recipient device in block 1101, the first radar warning frame carrying timing information indicating a timing relationship between a codeword sequence and one or more pulses. In some implementations, the one or more pulses may include a pulse sequence, and the timing information may indicate a duration of each of the one or more pulses and a delay between transmitting the codeword sequence and the start of the pulse sequence. In some implementations, the first radar warning frame may be a CTS-to-Self frame with a control trailer carrying the timing information. In some implementations, the CTS-to-Self frame may be transmitted in the direction of the first recipient device using beamforming.

[0121] In block 1102, process 1100 proceeds to transmitting a first codeword in the sequence of codewords in a direction of a first receiving device using beamforming. In block 1103, process 1100 proceeds to transmitting the one or more pulses in multiple directions using beamforming. In some implementations, the sequence of codewords and the one or more pulses may be transmitted in a PPDU that includes a PHY preamble and a header. In block 1104, process 1100 proceeds to receiving feedback from the first receiving device in response to transmitting the one or more pulses. In block 1105, process 1100 proceeds to determining a distance of an object from the wireless communication device based at least in part on the feedback received from the first receiving device.

[0122] Figure 11B A flow chart illustrating an example process 1110 for wireless communication supporting multistatic radar measurements according to some implementations is shown. In some implementations, the process 1110 may be performed by a radar transmitter such as a Figure 1 、 Figure 6A 、 Figure 7 and Figure 8 The communication may be performed by a wireless communication device operating on or within the radar transmitter (AP 102, AP 104, radar transmitter 710, or radar transmitter RTX).

[0123] Refer to for example Figure 11AProcess 1110 may be a more detailed implementation of the distance determination operations described in block 1105 of process 1100. For example, process 1110 may begin in block 1111 after receiving feedback from the first receiving device in block 1104. In block 1111, process 1110 begins by determining, based on the feedback, a time at which an echo of a first pulse of the one or more pulses was detected by the first receiving device. In block 1112, process 1110 proceeds to determine a departure angle of the first pulse at the wireless communication device. In block 1113, process 1110 proceeds to calculate the distance to the object based, at least in part, on the departure angle, the time at which the echo was detected by the first receiving device, and the time at which the first pulse was transmitted by the wireless communication device.

[0124] Figure 11C A flow chart illustrating an example process 1120 for supporting wireless communications for multistatic radar measurements according to some implementations is shown. In some implementations, the process 1120 may be performed by a radar transmitter such as a Figure 1 、 Figure 6A 、 Figure 7 and Figure 8 The communication may be performed by a wireless communication device operating on or within the radar transmitter (AP 102, AP 104, radar transmitter 710, or radar transmitter RTX).

[0125] In some implementations, process 1120 is performed at Figure 11A Process 1120 may begin after process 1100. For example, process 1120 may begin in block 1121 after determining the distance to the object in block 1105. In block 1121, process 1120 begins by transmitting a second radar frame carrying the timing information to a second receiving device. In block 1122, process 1120 proceeds to transmitting a second codeword in the sequence of codewords in the direction of the second receiving device using beamforming. In block 1123, process 1120 proceeds to receiving feedback from the second receiving device in response to transmitting the one or more pulses.

[0126] Figure 11D A flow chart illustrating an example process 1130 for wireless communication supporting multistatic radar measurements according to some implementations is shown. In some implementations, the process 1130 may be performed by a radar transmitter such as a Figure 1 、 Figure 6A 、 Figure 7 and Figure 8 The communication may be performed by a wireless communication device operating on or within the radar transmitter (AP 102, AP 104, radar transmitter 710, or radar transmitter RTX).

[0127] Refer to for example Figure 11A, process 1130 may be a more detailed implementation of the distance determination operation described in block 1105 of process 1100. In some implementations, process 1130 may be a more detailed implementation of the distance determination operation described in block 1105 of process 1100. Figure 11C For example, process 1130 may begin in block 1131 after receiving feedback from the second receiving device in block 1123 of process 1120. In block 1131, process 1130 begins by determining, based on the feedback received from the first receiving device, a time at which an echo of a first pulse of the one or more pulses is detected by the first receiving device. In block 1132, process 1130 proceeds to determining, based on the feedback received from the second receiving device, a time at which an echo of a second pulse of the one or more pulses is detected by the second receiving device, wherein the distance to the object is determined based on the time at which the echo of the first pulse is detected by the first receiving device and the time at which the echo of the second pulse is detected by the second receiving device.

[0128] Figure 12 FIG2 shows a block diagram of an example radar receiver 1200 according to some implementations. In some implementations, the radar receiver 1200 may be configured to perform the above-mentioned Figure 10A –10C. Radar receiver 1200 may be an example implementation of wireless communication device 500. For example, radar receiver 1200 may be a chip, SoC, chipset, package, or device that includes at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0129] Radar receiver 1200 includes a receiving component 1210, a communication manager 1220, and a transmitting component 1230. Communication manager 1220 further includes a codeword detection component 1222, an echo detection component 1224, and a distance determination component 1226. Portions of one or more of components 1222-1226 may be implemented at least in part in hardware or firmware. In some implementations, at least some of components 1222, 1224, or 1226 are implemented at least in part as software stored in a memory (such as memory 508). For example, portions of one or more of components 1222, 1224, and 1226 may be implemented as non-transitory instructions (or "code") that are executable by a processor (such as processor 506) to perform the functions or operations of the corresponding component.

[0130] Receive component 1210 is configured to receive an RX signal from a radar transmitter. In some implementations, receive component 1210 may receive timing information indicating a timing relationship between a codeword sequence and one or more pulses. For example, receive component 1210 may receive timing information from a radar transmitter. Communications manager 1220 is configured to manage radar communications with the radar transmitter. In some implementations, codeword detection component 1222 may detect a codeword in the codeword sequence and determine a first time at which the codeword was detected; echo detection component 1224 may detect an echo of a pulse in the one or more pulses and determine a second time at which the echo was detected; and distance determination component 1226 may determine a distance from an object to the wireless communication device based at least in part on the first time, the second time, and the timing information. Transmit component 1230 is configured to transmit a TX signal to the radar transmitter. In some implementations, transmit component 1230 may transmit feedback to the radar transmitter based on the detected echo.

[0131] Figure 13 FIG2 shows a block diagram of an example radar transmitter 1300 according to some implementations. In some implementations, the radar transmitter 1300 can be configured to perform the above-mentioned Figure 11A -Any of the processes 1100-1130 described in 11D. The radar transmitter 1300 may be Figure 5 For example, the radar transmitter 1300 may be a chip, SoC, chipset, package, or device that includes at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0132] Radar transmitter 1300 includes a transmission component 1310, a communication manager 1320, and a reception component 1330. Communication manager 1320 further includes a distance determination component 1322. Portions of distance determination component 1322 may be implemented at least in part in hardware or firmware. In some implementations, distance determination component 1322 may be implemented at least in part as software stored in a memory (such as memory 508). For example, portions of distance determination component 1322 may be implemented as non-transitory instructions (or "code") that are executable by a processor (such as processor 506) to implement the functionality or operation of the corresponding component.

[0133] Transmitting component 1310 is configured to transmit a TX signal to one or more radar receivers. In some implementations, transmitting component 1310 may transmit a radar warning frame to a first radar receiver, the radar warning frame carrying timing information indicating a timing relationship between a codeword sequence and one or more pulses. Transmitting component 1310 may further utilize beamforming to transmit a first codeword from the codeword sequence in the direction of the first radar receiver. Transmitting component 1310 may further utilize beamforming to transmit the one or more pulses in multiple directions. Receiving component 1330 is configured to transmit a TX signal from one or more radar receivers. In some implementations, receiving component 1330 may receive feedback from the first radar receiver in response to transmitting the one or more pulses. Communication manager 1320 is configured to manage radar communications with a receiving device. In some implementations, distance determination component 1322 may determine the distance of an object from radar transmitter 1300 based at least in part on the feedback received from the first radar receiver.

[0134] As used herein, a phrase referring to "at least one of" or "one or more of" a list of items refers to any combination of those items, including individual members. For example, "at least one of a, b, or c" is intended to encompass the following possibilities: only a, only b, only c, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a, b, and c.

[0135] The various illustrative components, logic, logic blocks, modules, circuits, operations, and algorithmic processes described in conjunction with the implementations disclosed herein may be implemented as electronic hardware, firmware, software, or a combination of hardware, firmware, or software, including the structures disclosed in this specification and their structural equivalents. This interchangeability of hardware, firmware, and software has been generally described in terms of their functionality and illustrated in the various illustrative components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware, firmware, or software depends on the specific application and the design constraints imposed on the overall system.

[0136] Various modifications to the implementations described in this disclosure may be apparent to those skilled in the art, and the general principles defined herein may be applied to other implementations without departing from the spirit or scope of the disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but should be accorded the widest scope consistent with this disclosure, the principles, and the novel features disclosed herein.

[0137] In addition, various features described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented in multiple implementations separately or in any suitable subcombination. Thus, although features may be described above as functioning in a particular combination and even initially claimed as such, one or more features from a claimed combination may in some cases be omitted from that combination, and a claimed combination may be directed to a subcombination, or variations of a subcombination.

[0138] Similarly, although the operations are depicted in a particular order in the accompanying drawings, this should not be understood as requiring such operations to be performed in the particular order shown or in a sequential order, or to perform all of the illustrated operations in order to achieve the desired result. In addition, the accompanying drawings may schematically depict one or more example processes in the form of a flow chart or flow diagram. However, other operations not depicted may be incorporated into the schematically illustrated example processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In some environments, multitasking and parallel processing may be advantageous. In addition, the separation of the various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0139] Implementation examples are described in the following numbered clauses:

[0140] 1. A method for wireless communication performed by a wireless communication device, comprising:

[0141] receiving a radar warning frame carrying timing information indicating a timing relationship between a codeword sequence and one or more pulses;

[0142] detecting a codeword in the codeword sequence;

[0143] determining a first time the codeword was detected;

[0144] detecting an echo of a pulse from the one or more pulses;

[0145] determining a second time at which the echo is detected; and

[0146] A distance of an object from the wireless communication device is determined based at least in part on the first time, the second time, and the timing information.

[0147] 2. The method of clause 1, wherein detecting the codeword comprises:

[0148] The multiple antennas of the wireless communication device are tuned in the direction of the transmitting device.

[0149] 3. The method of clause 1 or 2, wherein detecting the echo comprises:

[0150] The plurality of antennas of the wireless communication device are tuned in a plurality of directions.

[0151] 4. The method of clauses 1-3, wherein the one or more pulses comprise a pulse train, and the timing information indicates a duration of each of the one or more pulses and a delay between the detected codeword and the start of the pulse train.

[0152] 5. The method according to any one of clauses 1 to 4, further comprising:

[0153] Feedback is transmitted to the transmitting device in response to detecting the echo, the feedback indicating the second time.

[0154] 6. The method according to any one of clauses 1 to 5, further comprising:

[0155] calculating a time at which the pulse is transmitted based on the first time, the second time, and the timing information; and

[0156] A distance range associated with the object is estimated based at least in part on the second time and the calculated time.

[0157] 7. The method according to any one of clauses 1 to 6, further comprising:

[0158] Feedback is transmitted to the transmitting device in response to detecting the echo, the feedback indicating the estimated distance range.

[0159] 8. The method of any one of clauses 1-7, wherein determining the distance of the object further comprises:

[0160] determining an angle of arrival of the echo at the wireless communication device; and

[0161] The distance to the object is calculated based at least in part on the angle of arrival and the estimated distance range.

[0162] 9. A method as recited in any one of clauses 1-8, wherein each codeword in the sequence of codewords comprises a corresponding Golay sequence.

[0163] 10. The method of any of clauses 1-9, wherein the radar warning frame is a clear-to-send (CTS-to-self) frame with a control trailer carrying the timing information.

[0164] 11. A wireless communication device comprising:

[0165] at least one modem;

[0166] at least one processor communicatively coupled to the at least one modem; and

[0167] At least one memory communicatively coupled to the at least one processor and storing processor-readable code that, when executed by the at least one processor in conjunction with the at least one modem, is configured to perform the method as recited in any one or more of clauses 1-10.

[0168] 12. A method for wireless communication performed by a wireless communication device, comprising:

[0169] transmitting a first radar warning frame to a first recipient device, the first radar warning frame carrying timing information indicating a timing relationship between a codeword sequence and one or more pulses;

[0170] transmitting a first codeword in the sequence of codewords in the direction of the first receiving device using beamforming;

[0171] transmitting the one or more pulses in multiple directions using beamforming;

[0172] receiving feedback from the first recipient device in response to transmitting the one or more pulses; and

[0173] A distance of an object from the wireless communication device is determined based at least in part on the feedback received from the first recipient device.

[0174] 13. The method of clause 12, wherein determining the distance of the object comprises:

[0175] determining, based on the feedback, a time at which an echo of a first pulse of the one or more pulses is detected by the first recipient device;

[0176] determining an angle of departure of the first pulse at the wireless communication device; and

[0177] The distance to the object is calculated based at least in part on the departure angle, the time when the echo was detected by the first recipient device, and the time when the first pulse was transmitted by the wireless communication device.

[0178] 14. The method of clause 12 or 13, wherein the one or more pulses comprise a pulse sequence, and the timing information indicates a duration of each of the one or more pulses and a delay between transmitting the codeword sequence and the start of the pulse sequence.

[0179] 15. The method of any one of clauses 12 or 14, further comprising:

[0180] transmitting a second radar warning frame carrying the timing information to a second receiving device;

[0181] transmitting a second codeword in the sequence of codewords in the direction of the second receiving device using beamforming; and

[0182] Feedback is received from the second recipient device in response to transmitting the one or more pulses.

[0183] 16. The method of any of clauses 12, 14, or 15, wherein determining the distance of the object comprises:

[0184] determining, based on feedback received from the first recipient device, a time at which an echo of a first pulse of the one or more pulses is detected by the first recipient device; and

[0185] The time at which the echo of the second pulse of the one or more pulses is detected by the second receiving device is determined based on feedback received from the second receiving device, and the distance to the object is determined based on the time at which the echo of the first pulse is detected by the first receiving device and the time at which the echo of the second pulse is detected by the second receiving device.

[0186] 17. The method of clauses 12 or 14-16, wherein the feedback received from the first recipient device indicates a first distance range associated with the object, and the feedback received from the second recipient device indicates a second distance range associated with the object.

[0187] 18. A method as recited in any one of clauses 12-17, wherein each codeword in the sequence of codewords comprises a corresponding Golay sequence.

[0188] 19. The method of any of clauses 12-18, wherein the first radar warning frame is a clear-to-send (CTS-to-self) frame with a control trailer carrying the timing information.

[0189] 20. The method of any of clauses 12-19, wherein the CTS-to-Self frame is transmitted in the direction of the first recipient device using beamforming.

[0190] 21. The method of any of clauses 12-20, wherein the sequence of codewords and the one or more pulses are transmitted in a physical layer (PHY) convergence protocol (PLCP) protocol data unit (PPDU) including a PHY preamble and a header.

[0191] 22. A wireless communication device comprising:

[0192] at least one modem;

[0193] at least one processor communicatively coupled to the at least one modem; and

[0194] At least one memory communicatively coupled to the at least one processor and storing processor-readable code that, when executed by the at least one processor in conjunction with the at least one modem, is configured to perform the method as recited in any one or more of clauses 12-21.

Claims

1. A method for wireless communication performable at a first wireless communication device, comprising: receiving a radar warning frame from a second wireless communication device, the radar warning frame carrying timing information indicating a timing relationship between a codeword sequence and one or more pulses; receiving, at a first time, a codeword in the sequence of codewords from the second wireless communication device; receiving an echo of a pulse of the one or more pulses at a second time; as well as A distance between an object and the first wireless communication device is determined based on the first time, the second time, and the timing information.

2. The method of claim 1 , wherein receiving the codeword comprises: The plurality of antennas of the first wireless communication device are tuned in the direction of the second wireless communication device.

3. The method of claim 1 , wherein receiving the echo comprises: The plurality of antennas of the first wireless communication device are tuned in a plurality of directions.

4. The method of claim 1, wherein the one or more pulses comprise a pulse train, and the timing information indicates a duration of each of the one or more pulses and a delay between the codeword and a start of the pulse train.

5. The method of claim 1, further comprising: Feedback is transmitted to the second wireless communication device in response to detecting the echo, the feedback indicating the second time.

6. The method of claim 1, further comprising: calculating a time at which the pulse is transmitted based on the first time, the second time, and the timing information; as well as A distance range associated with the object is estimated based on the second time and the calculated time.

7. The method of claim 6, further comprising: Feedback is transmitted to the second wireless communication device in response to detecting the echo, the feedback indicating the estimated distance range.

8. The method of claim 6, wherein determining the distance of the object further comprises: determining an angle of arrival of the echo at the first wireless communication device; as well as The distance to the object is calculated based on the angle of arrival and the estimated distance range.

9. The method of claim 1, wherein each codeword in the sequence of codewords comprises a corresponding Golay sequence.

10. The method of claim 1, wherein the radar warning frame is a Clear to Send (CTS)-to-Self (QTS-to-Self) frame having a control trailer carrying the timing information.

11. A first wireless communication device, comprising: at least one memory; as well as at least one processor communicatively coupled to the at least one memory, The at least one processor is operable to cause the first wireless communication device to: receiving a radar warning frame from a second wireless communication device, the radar warning frame carrying timing information indicating a timing relationship between a codeword sequence and one or more pulses; receiving, at a first time, a codeword in the sequence of codewords from the second wireless communication device; receiving an echo of a pulse of the one or more pulses at a second time; as well as A distance between an object and the first wireless communication device is determined based on the first time, the second time, and the timing information.

12. The first wireless communication device of claim 11 , wherein receiving the codeword further comprises: The plurality of antennas of the first wireless communication device are tuned in the direction of the second wireless communication device.

13. The first wireless communication device of claim 11 , wherein receiving the echo further comprises: The plurality of antennas of the first wireless communication device are tuned in a plurality of directions.

14. The first wireless communication device of claim 11, wherein the one or more pulses comprise a pulse train, and the timing information indicates a duration of each of the one or more pulses and a delay between the codeword and a start of the pulse train.

15. The first wireless communication device of claim 11 , wherein the at least one processor is further operable to cause the first wireless communication device to: Feedback is transmitted to the second wireless communication device in response to detecting the echo, the feedback indicating the second time.

16. The first wireless communication device of claim 11 , wherein the at least one processor is further operable to cause the first wireless communication device to: calculating a time at which the pulse is transmitted based on the first time, the second time, and the timing information; and A distance range associated with the object is estimated based on the second time and the calculated time.

17. The first wireless communication device of claim 16, wherein the at least one processor is further operable to cause the first wireless communication device to: Feedback is transmitted to the second wireless communication device in response to detecting the echo, the feedback indicating the estimated distance range.

18. The wireless communication device of claim 16, wherein determining the distance of the object further comprises: determining an angle of arrival of the echo at the first wireless communication device; as well as The distance to the object is calculated based on the angle of arrival and the estimated distance range.

19. The first wireless communication device of claim 11, wherein each codeword in the sequence of codewords comprises a corresponding Golay sequence.

20. The first wireless communication device of claim 11, wherein the radar warning frame is a Clear to Send (CTS)-to-Self (QTS-to-Self) frame having a control trailer carrying the timing information.

21. A method for wireless communication performable at a wireless communication device, comprising: transmitting a first radar warning frame to a first recipient device, the first radar warning frame carrying timing information indicating a timing relationship between a codeword sequence and one or more pulses; transmitting a first codeword in the sequence of codewords in a direction of the first receiving device using beamforming; transmitting the one or more pulses in multiple directions using beamforming; receiving feedback from the first recipient device in response to transmitting the one or more pulses; as well as A distance of an object from the wireless communication device is determined based on the feedback received from the first recipient device.

22. The method of claim 21 , wherein determining the distance of the object further comprises: determining, based on the feedback, a time at which an echo of a first pulse of the one or more pulses is detected by the first recipient device; determining a departure angle of the first pulse at the wireless communication device; as well as The distance to the object is calculated based on the departure angle, the time when the echo is detected by the first receiver device, and the time when the first pulse is transmitted by the wireless communication device.

23. The method of claim 21, wherein the one or more pulses comprise a pulse sequence, and the timing information indicates a duration of each of the one or more pulses and a delay between transmitting the codeword sequence and the start of the pulse sequence.

24. The method of claim 21, further comprising: transmitting a second radar warning frame carrying the timing information to a second receiving device; transmitting a second codeword in the sequence of codewords in the direction of the second receiving device using beamforming; as well as Feedback is received from the second recipient device in response to transmitting the one or more pulses.

25. The method of claim 24, wherein determining the distance of the object further comprises: determining, based on the feedback received from the first recipient device, a time at which an echo of a first pulse of the one or more pulses is detected by the first recipient device; as well as The time at which the echo of the second pulse of the one or more pulses is detected by the second receiving device is determined based on the feedback received from the second receiving device, and the distance of the object is determined based on the time at which the echo of the first pulse is detected by the first receiving device and the time at which the echo of the second pulse is detected by the second receiving device.

26. The method of claim 25, wherein the feedback received from the first recipient device indicates a first distance range associated with the object, and the feedback received from the second recipient device indicates a second distance range associated with the object.

27. The method of claim 21, wherein each codeword in the sequence of codewords comprises a corresponding Golay sequence.

28. The method of claim 21, wherein the first radar warning frame is a Clear to Send (CTS)-to-Self (QTS-to-Self) frame having a control trailer carrying the timing information.

29. The method of claim 28, wherein the CTS-to-Self frame is transmitted in the direction of the first receiving device using beamforming.

30. The method of claim 21, wherein the codeword sequence and the one or more pulses are transmitted in a Physical Layer (PHY Convergence Protocol) (PLCP) Protocol Data Unit (PPDU) including a PHY preamble and a header.

31. A wireless communication device comprising: at least one memory; already at least one processor communicatively coupled to the at least one memory, the at least one processor operable to cause the wireless communication device to: transmitting a first radar warning frame to a first recipient device, the first radar warning frame carrying timing information indicating a timing relationship between a codeword sequence and one or more pulses; transmitting a first codeword in the sequence of codewords in a direction of the first receiving device using beamforming; transmitting the one or more pulses in multiple directions using beamforming; receiving feedback from the first recipient device in response to transmitting the one or more pulses; as well as A distance of an object from the wireless communication device is determined based on the feedback received from the first recipient device.

32. The wireless communication device of claim 31 , wherein determining the distance of the object comprises: determining, based on the feedback, a time at which an echo of a first pulse of the one or more pulses is detected by the first recipient device; determining a departure angle of the first pulse at the wireless communication device; as well as The distance to the object is calculated based on the departure angle, the time when the echo is detected by the first receiver device, and the time when the first pulse is transmitted by the wireless communication device.

33. The wireless communication device of claim 31, wherein the one or more pulses comprise a sequence of pulses, and the timing information indicates a duration of each of the one or more pulses and a delay between transmitting the sequence of codewords and a start of the sequence of pulses.

34. The wireless communication device of claim 31 , wherein the at least one processor is further operable to cause the wireless communication device to: transmitting a second radar warning frame carrying the timing information to a second receiving device; transmitting a second codeword in the sequence of codewords in the direction of the second receiving device using beamforming; and Feedback is received from the second recipient device in response to transmitting the one or more pulses.

35. The wireless communication device of claim 31 , wherein determining the distance of the object further comprises: determining, based on the feedback received from the first recipient device, a time at which an echo of a first pulse of the one or more pulses is detected by the first recipient device; as well as The time at which the echo of the second pulse of the one or more pulses is detected by the second receiving device is determined based on the feedback received from the second receiving device, and the distance of the object is determined based on the time at which the echo of the first pulse is detected by the first receiving device and the time at which the echo of the second pulse is detected by the second receiving device.

36. The wireless communication device of claim 35, wherein the feedback received from the first recipient device indicates a first distance range associated with the object, and the feedback received from the second recipient device indicates a second distance range associated with the object.

37. The wireless communication device of claim 31, wherein each codeword in the sequence of codewords comprises a corresponding Golay sequence.

38. The wireless communication device of claim 31, wherein the first radar warning frame is a Clear to Send (CTS)-to-Self (QTS-to-Self) frame having a control trailer carrying the timing information.

39. The wireless communication device of claim 38, wherein the CTS-to-Self frame is transmitted in the direction of the first receiving device using beamforming.

40. The wireless communication device of claim 31, wherein the codeword sequence and the one or more pulses are transmitted in a Physical Layer (PHY Convergence Protocol) (PLCP) Protocol Data Unit (PPDU) including a PHY preamble and a header.

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