System and method for time synchronization of sensing measurements outside BSS

Abstract

Systems and methods for Wi-Fi sensing are provided. A networked device configured to operate as a sensing receiver and including at least one processor may operate as a system for performing the Wi-Fi sensing method. The sensing receiver may obtain timing information from a non-associated access point that is not associated with the sensing receiver and operates as a sensing transmitter. The sensing receiver may generate local timing information based on the timing information. The sensing receiver may receive a sensing transmission from the non-associated access point. The sensing receiver may perform a sensing measurement on the sensing transmission, and may associate the sensing measurement with a timestamp based on the local timing information. The sensing receiver may transmit the sensing measurement and the timestamp to the non-associated access point.

Description

Technical Field

[0001] The present disclosure generally relates to systems and methods for Wi-Fi sensing. Specifically, the present disclosure relates to systems and methods for time synchronization of sensing measurements outside of a basic service set (OBSS). Background Art

[0002] A Wi-Fi sensing system may be configured to detect features of interest in a sensing space. A Wi-Fi sensing system may be a network of Wi-Fi enabled devices that are part of an IEEE 802.11 network (sometimes referred to as a basic service set (BSS) or extended service set (ESS)). Features of interest may include motion and movement tracking of objects, presence detection, intrusion detection, gesture recognition, fall detection, breathing rate detection, and other applications. A sensing space may refer to any physical space in which a Wi-Fi sensing system may operate, and may include a residence, a workplace, a shopping mall, a gymnasium or stadium, a garden, or any other physical space. Summary of the invention

[0003] The present disclosure generally relates to systems and methods for Wi-Fi sensing. Specifically, the present disclosure relates to systems and methods for time synchronization of sensing measurements outside of a basic service set (OBSS).

[0004] Systems and methods for Wi-Fi sensing are provided. In an example embodiment, a method for Wi-Fi sensing is described. The method is performed by a networked device configured to operate as a sensing receiver. The networked device operating as a sensing receiver includes at least one processor configured to execute instructions. The method includes obtaining, by the sensing receiver, timing information from an unassociated access point that is not associated with the sensing receiver and operates as a sensing transmitter. In some embodiments, the method further includes: generating, by the sensing receiver, local timing information based on the timing information; and receiving, by the sensing receiver, a sensing transmission from the unassociated access point. In some embodiments, the method further includes: performing, by the sensing receiver, sensing measurements on the sensing transmission; and associating, by the sensing receiver, the sensing measurements with a timestamp based on the local timing information. In some embodiments, the method further includes sending, by the sensing receiver, the sensing measurements and the timestamp to the unassociated access point.

[0005] In some embodiments, the timing information is an access point timing synchronization function (TSF) timer of the non-associated access point.

[0006] In some embodiments, the timing information is stored as local timing information.

[0007] In some embodiments, the local timing information is a timer offset value determined from a difference between the timing information and a sensing receiver TSF timer, and the timestamp is determined by combining the sensing receiver TSF timer value with the timer offset value.

[0008] In some embodiments, the unassociated access point is a first unassociated access point.

[0009] In some embodiments, the method further includes: obtaining, by the sensing receiver, additional timing information from a plurality of additional non-associated access points; and generating, by the sensing receiver, additional local timing information based on the additional timing information.

[0010] In some embodiments, the timing information is received in a beacon frame broadcast by a non-associated access point.

[0011] In some embodiments, receiving the sensing transmission further comprises tuning the sensing receiver to the channel on which the beacon frame was received.

[0012] In some embodiments, the sensing receiver is associated with an associated access point operating on the same channel on which the beacon frame is received from the non-associated access point.

[0013] In some embodiments, the method further comprises sending an idle message to an associated access point.

[0014] In some embodiments, the method further comprises: sending, by the sensing receiver, a probe request; and receiving, by the sensing receiver, a probe response comprising the timing information in response to the probe request.

[0015] In some embodiments, the probe request includes at least one access point identification and the probe response includes at least one response from an access point associated with the at least one access point identification.

[0016] In some embodiments, the probe request includes an access point identification wildcard and the probe response includes at least one response from an access point.

[0017] In some embodiments, local timing information is maintained and incremented at the sensing receiver.

[0018] In some embodiments, the local timing information is incremented at the sensing receiver according to a local clock.

[0019] In some embodiments, prior to receiving a sensing transmission, the sensing receiver initiates a Pre-Association Security Negotiation (PASN) procedure with the sensing transmitter.

[0020] In some embodiments, the sensing receiver sends the sensing measurements in response to receiving a sensing report trigger.

[0021] In some embodiments, the method further comprises resynchronizing the local timing information by receiving second timing information from the non-associated access point.

[0022] In some embodiments, resynchronizing the local timing information is performed after expiration of a resynchronization timer.

[0023] In some embodiments, the time interval of the resynchronization timer is determined based on a measurement of timing drift between the non-associated access point and the sensing receiver.

[0024] Other aspects and advantages of the present disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The foregoing and other objects, aspects, features and advantages of the present disclosure will become more apparent and better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1 is a diagram illustrating an example wireless communication system;

[0027] Figure 2A and Figure 2B is a diagram illustrating example wireless signals transmitted between wireless communication devices;

[0028] Figure 3A and Figure 3B It shows that according to Figure 2A and Figure 2B a graph of an example of a channel response calculated for a wireless signal transmitted between wireless communication devices;

[0029] Figure 4A and Figure 4B is a graph showing example channel responses associated with motion of an object in different spatial regions;

[0030] Figure 4C and Figure 4D It is shown Figure 4A and Figure 4B a graph of an example channel response superimposed on an example channel response associated with no motion in space;

[0031] Figure 5 Describes some architecture of implementations of a system for Wi-Fi sensing according to some embodiments;

[0032] Figure 6 depicts an example representation of a typical Wi-Fi sensing system in accordance with some embodiments;

[0033] Figure 7depicts a process for Pre-Association Security Negotiation (PASN) authentication according to some embodiments;

[0034] Figure 8 depicts an example of a timing synchronization function (TSF) timer out of sync situation according to some embodiments;

[0035] Fig. 9 depicts an example of communications between a station, an associated access point, and an unassociated access point in accordance with some embodiments;

[0036] Fig. 10A and Fig. 10B Depicted are trigger-based measurement examples of a Wi-Fi sensing process according to some embodiments;

[0037] Fig.11 depicts an example of a trigger-based exchange of sensed measurements according to some embodiments;

[0038] Fig.12 depicts the format of a sensing measurement report frame according to some embodiments;

[0039] Fig.13 depicts a SENS NDPA STA information field showing a partial TSF in accordance with some embodiments;

[0040] Fig.14 depicts an example of a SENS NDPA STA Information field with a partial TSF in a Sensing Measurement Exchange in accordance with some embodiments;

[0041] Fig.15 depicts an example of a trigger-based exchange of sensed measurements according to some embodiments;

[0042] Fig.16 depicts an example of full TSF timer synchronization using partial TSF fields according to some embodiments;

[0043] Fig.17 depicts a flow diagram of sending sensing measurements and timestamps by a sensing receiver to a non-associated access point in accordance with some embodiments;

[0044] Fig.18A and Fig.18B depicts a flow diagram of resynchronizing local timing information by receiving second timing information from a non-associated access point in accordance with some embodiments; and

[0045] Fig.19A and Fig.19B Another flow diagram for sending sensing measurements and timestamps by a sensing receiver to a non-associated access point is depicted in accordance with some embodiments. DETAILED DESCRIPTION

[0046] In some aspects described herein, by processing wireless signals (e.g., radio frequency (RF) signals) transmitted through space between wireless communication devices, the wireless sensing system can be used for a variety of wireless sensing applications. Example wireless sensing applications include motion detection, which may include the following: detecting the movement of an object in space, motion tracking, respiration detection, respiration monitoring, presence detection, gesture detection, gesture recognition, human detection (moving and stationary human detection), human tracking, fall detection, speed estimation, intrusion detection, walking detection, step counting, respiration rate detection, apnea estimation, posture change detection, activity recognition, pace classification, gesture decoding, sign language recognition, hand tracking, heart rate estimation, respiration rate estimation, room occupancy detection, human dynamics monitoring, and other types of motion detection applications. Other examples of wireless sensing applications include object recognition, speech recognition, keystroke detection and identification, tampering detection, touch detection, attack detection, user authentication, driver fatigue detection, traffic monitoring, smoke detection, school violence detection, people counting, human recognition, bicycle positioning, personnel queue estimation, Wi-Fi imaging, and other types of wireless sensing applications. For example, the wireless sensing system can operate as a motion detection system to detect the presence and location of motion based on Wi-Fi signals or other types of wireless signals. As described in more detail below, the wireless sensing system can be configured to control measurement rates, wireless connections, and device participation, for example, to improve system operation or achieve other technical advantages. In examples where the wireless sensing system is used for another type of wireless sensing application, the system improvements and technical advantages achieved when the wireless sensing system is used for motion detection are also achieved.

[0047] In some example wireless sensing systems, the wireless signal contains a component (e.g., a synchronization preamble in a Wi-Fi PHY frame, or another type of component) that a wireless device can use to estimate a channel response or other channel information, and the wireless sensing system can detect motion (or another characteristic, depending on the wireless sensing application) by analyzing changes in the channel information collected over time. In some examples, the wireless sensing system can operate similar to a bistatic radar system, where a Wi-Fi access point (AP) plays the role of a receiver and each Wi-Fi device (station (STA), node, or peer) connected to the AP plays the role of a transmitter. The wireless sensing system can trigger the connected device to generate a transmission and generate a channel response measurement at the receiver device. This triggering process can be repeated periodically to obtain a series of time-varying measurements. The wireless sensing algorithm can then receive the generated time series of channel response measurements (e.g., calculated by a Wi-Fi receiver) as input, and through a correlation or filtering process, a determination can then be made (e.g., determining whether there is motion within the environment represented by the channel response, for example, based on changes or patterns in the channel estimate). In an example where the wireless sensing system detects motion, the location of the motion within the environment can also be identified based on the motion detection results among several wireless devices.

[0048] Therefore, the wireless signals received at each wireless communication device in the wireless communication network can be analyzed to determine the channel information of various communication links in the network (between the corresponding wireless communication device pairs). Channel information can represent the physical medium of the wireless signal that applies the transfer function to the space. In some cases, the channel information includes a channel response. The channel response can characterize the physical communication path, representing the combined effects of scattering, fading and power attenuation in the space between the transmitter and the receiver, for example. In some cases, the channel information includes beamforming state information (e.g., feedback matrix, steering matrix, channel state information, etc.) provided by the beamforming system. Beamforming is a signal processing technique, typically used for directional signal transmission or reception in multi-antenna (multiple input / multiple output (MIMO)) radio systems. Beamforming can be achieved by operating the elements in the antenna array in a manner such that signals at some angles experience constructive interference, while other signals experience destructive interference.

[0049] The channel information of each communication link may be analyzed (e.g., by a hub device or another device in a wireless communication network, or a sensing transmitter, sensing receiver, or sensing initiator communicatively coupled to the network) to, for example, detect whether motion has occurred in the space, determine the relative position of the detected motion, or both. In some aspects, such as when no motion is detected in the space, the channel information of each communication link may be analyzed to detect whether an object is present.

[0050] In some cases, the wireless sensing system can control the node measurement rate. For example, the Wi-Fi motion system can configure a variable measurement rate (e.g., channel estimation / environmental measurement / sampling rate) based on the criteria given by the current wireless sensing application (e.g., motion detection). In some embodiments, for example, when there is no motion or no motion is detected for a period of time, the wireless sensing system can reduce the rate of measuring the environment, so that the trigger frequency of the connected device is reduced or the frequency of sensing transmission or sensing measurement is reduced. In some embodiments, when there is motion, for example, the wireless sensing system can increase the trigger rate or the sensing transmission rate or the sensing measurement rate to produce a time series of measurements with finer time resolution. Controlling the variable sensing measurement rate can achieve energy saving (via device triggering), reduce processing (reduce the data to be associated or filtered), and improve the resolution during a specified time period.

[0051] In some cases, the wireless sensing system can perform band steering or client steering for nodes throughout the wireless network, for example, in a Wi-Fi multi-AP or extended service set (ESS) topology, multiple coordinated wireless APs each provide a basic service set (BSS), which can occupy different frequency bands and allow devices to move transparently from one participating AP to another participating AP (e.g., a mesh). For example, in a home mesh network, Wi-Fi devices can connect to any AP, but typically select an AP with good signal strength. The coverage areas of mesh APs typically overlap, typically placing each device within the communication range or within more than one AP. If the AP supports multiple frequency bands (e.g., 2.4GHz and 5GHz), the wireless sensing system can keep the device connected to the same physical AP, but instruct the device to use different frequency bands to obtain more diverse information to help improve the accuracy or results of wireless sensing algorithms (e.g., motion detection algorithms). In some embodiments, the wireless sensing system can change a device from connecting to one mesh AP to connecting to another mesh AP. For example, such device steering may be performed during wireless sensing (eg, motion detection) based on criteria detected in a particular area to improve detection coverage or better locate motion within an area.

[0052] In some cases, beamforming can be performed between wireless communication devices based on some knowledge of the communication channel (e.g., through feedback properties generated by the receiver), which can be used to generate one or more steering properties (e.g., steering matrices) that the transmitter device applies to shape the transmitted beam / signal in one or more specific directions. Thus, changes in the steering or feedback properties used in the beamforming process indicate changes in the space accessed by the wireless communication system that may be caused by moving objects. For example, motion can be detected by significant changes in the communication channel over a period of time, such as indicated by the channel response or the steering or feedback properties, or any combination thereof.

[0053] In some embodiments, for example, a steering matrix may be generated at a transmitter device (beamformer) based on a feedback matrix provided by a receiver device (beamformer) based on channel sounding. Since the steering and feedback matrices are related to the propagation characteristics of the channel, these matrices change as the object moves within the channel. Changes in channel characteristics are reflected accordingly in these matrices, and by analyzing these matrices, motion can be detected and different characteristics of the detected motion can be determined. In some embodiments, a spatial map may be generated based on one or more beamforming matrices. A spatial map may indicate the approximate direction of an object in space relative to a wireless communication device. In some cases, a number of beamforming matrices (e.g., feedback matrices or steering matrices) may be generated to represent multiple directions in which an object may be positioned relative to a wireless communication device. The many beamforming matrices may be used to generate a spatial map. A spatial map may be used to detect the presence of motion in space or to detect the location of a detected motion.

[0054] In some cases, the motion detection system can control the variable device measurement rate during the motion detection process. For example, a feedback control system for a multi-node wireless motion detection system can adaptively change the sampling rate based on environmental conditions. In some cases, this control can improve the operation of the motion detection system or provide other technical advantages. For example, the measurement rate can be controlled in a way that optimizes or otherwise improves air time usage and detection capabilities, which is suitable for a variety of different environments and different motion detection applications. The measurement rate can be controlled in a way that reduces redundant measurement data to be processed, thereby reducing processor load / power requirements. In some cases, the measurement rate is controlled in an adaptive manner, for example, the adaptive samples can be controlled individually for each participating device. The adaptive sampling rate can be used in conjunction with a tuning control loop to adapt to different use cases or device characteristics.

[0055] In some cases, the wireless sensing system may allow a device to dynamically indicate and communicate its wireless sensing capabilities or willingness to wireless sensing to the wireless sensing system. For example, sometimes a device may not want to be periodically interrupted or triggered to send wireless signals that allow the AP to generate channel measurements. For example, if the device is sleeping, frequently waking up the device to send or receive wireless sensing signals may consume resources (e.g., causing the phone battery to discharge faster). These and other events may make the device willing or unwilling to participate in wireless sensing system operations. In some cases, a mobile phone running on battery may not want to participate, but when the phone is plugged into a charger, it may be willing to participate. Therefore, if the phone is not plugged in, the phone can indicate to the wireless sensing system that it is excluded from participation; and if the phone is plugged in, the phone can indicate to the wireless sensing system that it is included in the wireless sensing system operation. In some cases, if the device is under load (e.g., the device is streaming audio or video) or busy performing a primary function, the device may not want to participate; and when the load of the same device is reduced and participation does not interfere with the primary function, the device can indicate to the wireless sensing system that the device is willing to participate.

[0056] An example wireless sensing system is described below in the context of motion detection (detecting motion of an object in space, motion tracking, respiration detection, respiration monitoring, presence detection, gesture detection, gesture recognition, human detection (moving and stationary human detection), human tracking, fall detection, speed estimation, intrusion detection, walking detection, step counting, respiration rate detection, apnea estimation, posture change detection, activity recognition, pace classification, gesture decoding, sign language recognition, hand tracking, heart rate estimation, respiration rate estimation, room occupancy detection, human dynamics monitoring, and other types of motion detection applications). However, in examples where the wireless sensing system is used for another type of wireless sensing application, the operations, system improvements, and technical advantages achieved when the wireless sensing system is used as a motion detection system are equally applicable.

[0057] In various embodiments of the present disclosure, non-limiting definitions of one or more terms that will be used in this document are provided below.

[0058] The term "measurement campaign" may refer to a series of one or more sensing transmissions in both directions between a sensing receiver and a sensing transmitter, which allows a series of one or more sensing measurements to be calculated.

[0059] A wireless access point (WAP), or simply an access point (AP), is a networking device in a WLAN network that enables other networking devices in the WLAN network to connect to a wired network. In an example, an AP creates a wireless local area network.

[0060] A station (STA) is any device connected to a WLAN network and containing an 802.11 compatible MAC and PHY interface connected to a wireless medium. A STA can be a laptop, desktop computer, smartphone, or smart appliance. A STA can be fixed, mobile, or portable. A STA that does not act as an AP can be referred to as a non-AP STA.

[0061] The term "transmission opportunity (TXOP)" may refer to a negotiated time interval during which a particular quality of service (QoS) station (e.g., a STA, an AP, or a STA or AP, such as a sensing initiator, a sensing responder, a sensing transmitter, or a sensing receiver) may be entitled to initiate frame exchanges onto the wireless medium. As part of a service or session negotiation, a QoS access category (AC) for a transmission opportunity may be requested.

[0062] The term "Quality of Service (QoS) Access Category (AC)" may refer to an identifier of a frame that classifies the transmission priority required for the frame. In an example, four QoS access categories are defined, namely AC_VI: Video, AC_VO: Voice, AC_BE: Best Effort, and AC_BK: Background. In addition, each QoS access category may have a different TXOP defined for it.

[0063] The term "Short Interframe Space (SIFS)" may refer to a period of time during which a processing element (e.g., a microprocessor, dedicated hardware, or any such element) within a device of a Wi-Fi sensing system is able to process data presented to the processing element in a frame. In an example, the short interframe space may be 10 μs.

[0064] The term "PHY layer protocol data unit (PPDU)" may refer to a data unit including a preamble and a data field. The preamble field may contain transmission vector format information, and the data field may contain a payload and a higher layer header.

[0065] The term "Null Data PPDU (NDP)" may refer to a PPDU that does not contain a data field. In an example, a Null Data PPDU may be used for a sensing transmission, where the MAC header of the NDP contains information required by a sensing receiver to perform sensing measurements on the sensing transmission.

[0066] The term "transmission parameters" may refer to a set of IEEE 802.11 PHY transmitter configuration parameters that are defined as part of a transmission vector (TXVECTOR) corresponding to a specific PHY and may be configured for each PHY layer PPDU transmission or each Null Data PPDU (NDP) transmission.

[0067] The term "resource unit (RU)" may refer to an allocation of an Orthogonal Frequency Division Multiplexing (OFDM) channel that may be used to carry a modulated signal. A RU may contain a variable number of carriers, depending on the mode of the modem.

[0068] The term "tone" may refer to an individual subcarrier in an OFDM signal. A tone may be represented in the time domain or the frequency domain. In the time domain, a tone may also be referred to as a symbol. In the frequency domain, a tone may also be referred to as a subcarrier.

[0069] The term "time domain pulse" may refer to a complex number representing the amplitude and phase of discretized energy in the time domain. When the frequency domain channel state information value of each tone is obtained from a baseband receiver, the time domain pulse may be obtained by performing IFFT on the channel state information value.

[0070] The term "sensing target" may refer to the target of a sensing activity. A sensing target is not static and may change at any time. In an example, a sensing target may require sensing measurements of a specific type, a specific format, or a specific precision, resolution, or accuracy for use by a sensing algorithm.

[0071] The term "sensing space" may refer to any physical space in which a Wi-Fi sensing system may operate.

[0072] The term "wireless local area network (WLAN) sensing session" or "Wi-Fi sensing session" may refer to a period of time during which objects in a physical space may be detected, detected, and / or characterized. In an example, during a WLAN sensing session, several devices participate, thereby contributing to the generation of sensing measurements. A WLAN sensing session may be referred to as a "measurement activity."

[0073] The term "non-sensing message" may refer to a message that is not primarily related to sensing. In an example, the non-sensing message may include data, management, and control messages.

[0074] The term "sensing measurement" may refer to a measurement of a wireless channel between a transmitter device (eg, a sensing transmitter) and a receiver device (eg, a sensing receiver) derived from a sensing transmission. In an example, a sensing measurement may also be referred to as a channel response measurement.

[0075] The term "sensing algorithm" may refer to a computational algorithm that implements a sensing goal. The sensing algorithm may be executed on any device in a Wi-Fi sensing system.

[0076] Wireless Network Management (WNM) can provide information about network conditions and can also provide a means to obtain and exchange WLAN sensing information.

[0077] A sensing receiver is a station (STA) that receives a sensing transmission (e.g., a PPDU or any other transmission, including a data transmission that can be opportunistically used as a sensing transmission) sent by a sensing transmitter and performs sensing measurements as part of the WLAN sensing process. An AP is an example of a sensing receiver. In some examples, a STA may also be a sensing receiver.

[0078] A sensing transmitter is a station (STA) that sends a sensing transmission (e.g., PPDU or any other transmission) for sensing measurements (e.g., channel state information) during WLAN sensing. In an example, a STA is an example of a sensing transmitter. In some examples, such as when a STA acts as a sensing receiver, an AP may be a sensing transmitter for Wi-Fi sensing purposes.

[0079] The sensing initiator is a station (STA) that initiates the WLAN sensing process. The role of the sensing initiator can be assumed by a sensing receiver, a sensing transmitter, or a separate device (eg, a remote processing device) that contains a sensing algorithm.

[0080] A sensing responder is a station (STA) that participates in a WLAN sensing process initiated by a sensing initiator. The role of a sensing responder may be assumed by a sensing receiver or a sensing transmitter. In an example, multiple sensing responders may participate in a Wi-Fi sensing session.

[0081] A proxy sensing (SBP) initiator is defined as a non-AP STA that acts as a sensing initiator that sends an SBP request frame. In an example, proxy sensing (SBP) enables a non-AP STA to obtain sensing measurements of a channel between an AP and one or more non-AP STAs or between an AP's receiving antenna and a transmitting antenna. By performing the SBP process, a non-AP STA can obtain sensing measurements required to detect and track environmental changes. A proxy sensing (SBP) responder is an AP that receives an SBP request frame or is the intended recipient of an SBP request frame.

[0082] The term "sensing transmission" may refer to any transmission from a sensing transmitter to a sensing receiver that may be used to make a sensing measurement. In an example, the sensing transmission may also be referred to as a wireless sensing signal or a wireless signal.

[0083] The term "sensing trigger message" may refer to a message sent from a sensing initiator to a sensing transmitter to initiate or trigger one or more sensing transmissions.

[0084] The term "sensing response message" may refer to a message contained within a sensing transmission from a sensing transmitter to a sensing receiver. The sensing receiver may use the sensing transmission containing the sensing response message to perform sensing measurements.

[0085] The term "sensing response notification" may refer to a message contained within a sensing transmission from a sensing transmitter to a sensing receiver that notifies that a sensing response NDP will follow within a short interframe space (SIFS). An example of a sensing response notification is an NDP notification or an NDPA. In an example, a sensing response NDP may be sent using a requested transmission configuration.

[0086] The term "sensing response NDP" may refer to a response sent by a sensing transmitter and used for sensing measurements at a sensing receiver. In an example, a sensing response NDP may be used when the requested transmission configuration is incompatible with the transmission parameters required for successful reception of a non-sensing message. The sensing response NDP may be notified by a sensing response notification. In an example, the sensing response NDP may be implemented with an empty data PPDU. In some examples, the sensing response NDP may be implemented with a frame that does not contain any data.

[0087] A "transmission channel" may refer to a tunable channel over which a sensing receiver performs sensing measurements and / or over which a sensing transmitter performs sensing transmissions.

[0088] The term "feature of interest" may refer to an item or item state that is actively detected and / or identified by a sensing algorithm.

[0089] The term “clear to send (CTS)” may refer to a function that may be used to let an AP know that a STA is ready (or clear without channel conflicts) to send or receive data.

[0090] The term "timing synchronization function (TSF) timer" may refer to a timer that may be used as a local timer in a Wi-Fi sensing system. The TSF timer may be based on a 1 MHz clock and may tick in microseconds. In an example, the TSF timer is represented by a 64-bit register [63:0] that increments every microsecond.

[0091] The term "OBSS STA" may refer to a STA that is in a non-associated state with an AP.

[0092] The term "OBSS AP" may refer to an AP that is in a non-associated state with a STA.

[0093] The term "timestamp" may refer to a value associated with a sensing measurement that indicates a time reference of the sensing measurement. In an example, a sensing algorithm may use the timestamp to calculate a sensing result.

[0094] The term "OBSS STA TSF timer" may refer to a local TSF timer (according to the IEEE 802.11 standard) maintained by a STA, which is incremented in time units (TUs) based on a STA voltage controlled oscillator (VCO).

[0095] The term "OBSS AP TSF timer" may refer to a local TSF timer (according to the IEEE 802.11 standard) maintained by the AP, which is incremented by TU based on the AP VCO.

[0096] The term "OBSS STA-AP TSF timer" may refer to a local version of a TSF timer maintained and incremented at a STA, which is periodically resynchronized with the OBSS AP TSF timer.

[0097] The term "timer offset" may refer to the TU difference between the OBSS AP TSF timer and the OBSS STA TSF timer at a certain point in time.

[0098] The term "adjusted OBSS STA TSF timer" may refer to a timer having a value equal to a combination of the OBSS STA TSF timer and a timer offset.

[0099] The term "resynchronization timer" may refer to a timer associated with an OBSS STA and an OBSS AP, representing the amount of time before the OBSS STA-AP TSF timer should be considered out of synchronization with the OBSS AP TSF timer.

[0100] The term "synchronization flag" may refer to a bit flag indicating whether the OBSS STA-AP TSF timer is synchronized with the OBSS AP TSF timer.

[0101] The term "Wi-Fi sensing session" may refer to a period of time during which an object in a sensing space may be detected, detected, and / or characterized. In an example, during a Wi-Fi sensing session, several devices participate, thereby contributing to the generation of sensing measurements. A Wi-Fi sensing session may also be referred to as a WLAN sensing session or simply a sensing session.

[0102] In order to read the description of various embodiments below, the following description of the various parts of this specification and their corresponding contents may be helpful:

[0103] Section A describes wireless communication systems, wireless transmissions, and sensing measurements that can be used to practice the embodiments described herein.

[0104] Section B describes systems and methods that may be used in a Wi-Fi sensing system configured to send sensing transmissions and make sensing measurements.

[0105] Section C describes embodiments of systems and methods for time synchronization of sensing measurements outside the basic service set (OBSS).

[0106] A. Wireless communication systems, wireless transmission and sensing measurements

[0107] Figure 1 A wireless communication system 100 is shown. The wireless communication system 100 includes three wireless communication devices: a first wireless communication device 102A, a second wireless communication device 102B, and a third wireless communication device 102C. The wireless communication system 100 may include additional wireless communication devices and other components (e.g., additional wireless communication devices, one or more network servers, network routers, network switches, cables or other communication links, etc.).

[0108] The wireless communication devices 102A, 102B, 102C may operate in a wireless network, for example, in accordance with a wireless network standard or another type of wireless communication protocol. For example, a wireless network may be configured to operate as a wireless local area network (WLAN), a personal area network (PAN), a metropolitan area network (MAN), or another type of wireless network. Examples of WLANs include networks configured to operate in accordance with one or more of the 802.11 series of standards developed by the IEEE (e.g., Wi-Fi networks). Examples of PANs include networks configured to operate in accordance with short-range communication standards (e.g., A network that operates with near field communication (NFC), ZigBee), millimeter wave communication, etc.

[0109] In some embodiments, the wireless communication devices 102A, 102B, 102C may be configured to communicate in a cellular network, for example, according to a cellular network standard. Examples of cellular networks include networks configured according to the following standards: 2G standards, such as Global System for Mobile (GSM) and Enhanced Data Rates for GSM Evolution (EDGE) or EGPRS; 3G standards, such as Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), Universal Mobile Telecommunications System (UMTS), and Time Division Synchronous Code Division Multiple Access (TD-SCDMA); 4G standards, such as Long Term Evolution (LTE) and Advanced LTE (LTE-A); 5G standards, etc.

[0110] exist Figure 1In the example shown, the wireless communication devices 102A, 102B, 102C may be or may include standard wireless network components. For example, the wireless communication devices 102A, 102B, 102C may be commercially available Wi-Fi APs or another type of wireless access point (WAP) that performs one or more operations as described herein, which are embedded as instructions (e.g., software or firmware) on the modem of the WAP. In some cases, the wireless communication devices 102A, 102B, 102C may be nodes of a wireless mesh network, such as commercially available mesh network systems (e.g., Plume Wi-Fi, Google Wi-Fi, Qualcomm Wi-FiSoN, etc.). In some cases, another type of standard or conventional Wi-Fi transmitter device may be used. In some cases, one or more of the wireless communication devices 102A, 102B, 102C may be implemented as a WAP in a mesh network, while other wireless communication devices 102A, 102B, 102C may be implemented as leaf devices (e.g., mobile devices, smart devices, etc.) that access the mesh network through one of the WAPs. In some cases, one or more of the wireless communication devices 102A, 102B, 102C are mobile devices (e.g., smart phones, smart watches, tablet computers, laptop computers, etc.), wireless-enabled devices (e.g., smart thermostats, Wi-Fi-enabled cameras, smart TVs), or another type of device that communicates in a wireless network.

[0111] The wireless communication devices 102A, 102B, 102C may be implemented without Wi-Fi components; for example, other types of standard or non-standard wireless communications may be used for motion detection. In some cases, the wireless communication devices 102A, 102B, 102C may be a dedicated motion detection system, or may be part of a dedicated motion detection system. For example, a dedicated motion detection system may include a hub device and one or more beacon devices (as remote sensor devices), and the wireless communication devices 102A, 102B, 102C may be the hub device or the beacon device in the motion detection system.

[0112] like Figure 1 As shown, the wireless communication device 102C includes a modem 112, a processor 114, a memory 116, and a power supply unit 118; any of the wireless communication devices 102A, 102B, and 102C in the wireless communication system 100 may include the same, additional, or different components, and these components may be configured as follows Figure 1In some embodiments, the modem 112, processor 114, memory 116, and power supply unit 118 of the wireless communication device are housed together in a common housing or other assembly. In some embodiments, one or more components of the wireless communication device may be housed separately, for example, in separate housings or other assemblies.

[0113] The modem 112 may communicate (receive, send, or both) wireless signals. For example, the modem 112 may be configured to communicate RF signals formatted according to a wireless communication standard (e.g., Wi-Fi or Bluetooth). The modem 112 may be implemented as Figure 1 The example wireless network modem 112 shown may be implemented in another way, for example, with other types of components or subsystems. In some embodiments, the modem 112 includes a radio subsystem and a baseband subsystem. In some cases, the baseband subsystem and the radio subsystem may be implemented on a common chip or chipset, or may be implemented in a card or another type of assembly device. The baseband subsystem may be coupled to the radio subsystem, for example, by leads, pins, wires, or other types of connections.

[0114] In some cases, the radio subsystem in modem 112 may include one or more antennas and RF circuits. The RF circuit may include, for example, a circuit for filtering, amplifying or otherwise adjusting an analog signal, a circuit for up-converting a baseband signal to an RF signal, a circuit for down-converting an RF signal to a baseband signal, etc. Such circuits may include, for example, filters, amplifiers, mixers, local oscillators, etc. The radio subsystem may be configured to transmit a radio frequency wireless signal on a wireless communication channel. As an example, the radio subsystem may include a radio chip, an RF front end, and one or more antennas. The radio subsystem may include additional or different components. In some embodiments, the radio subsystem may be or may include a radio electronic device (e.g., an RF front end, a radio chip, or similar components) from a conventional modem, such as a radio electronic device from a Wi-Fi modem, a micro base station modem, etc. In some embodiments, the antenna includes multiple antennas.

[0115] In some cases, the baseband subsystem in modem 112 may include, for example, a digital electronic device configured to process digital baseband data. As an example, the baseband subsystem may include a baseband chip. The baseband subsystem may include additional or different components. In some cases, the baseband subsystem may include a digital signal processor (DSP) device or another type of processor device. In some cases, the baseband system includes digital processing logic to operate a radio subsystem, transmit wireless network services through the radio subsystem, detect motion based on motion detection signals received through the radio subsystem, or perform other types of processes. For example, the baseband subsystem may include one or more chips, chipsets, or other types of devices that are configured to encode signals and pass the encoded signals to the radio subsystem for transmission, or (for example, by decoding the signals according to a wireless communication standard, by processing the signals according to a motion detection process, or otherwise) identify and analyze the data encoded in the signals from the radio subsystem.

[0116] In some cases, the radio subsystem in modem 112 receives a baseband signal from a baseband subsystem, up-converts the baseband signal to an RF signal, and wirelessly transmits the RF signal (e.g., via an antenna). In some cases, the radio subsystem in modem 112 receives an RF signal wirelessly (e.g., via an antenna), down-converts the RF to a baseband signal, and transmits the baseband signal to the baseband subsystem. The signals exchanged between the radio subsystem and the baseband subsystem may be digital or analog signals. In some examples, the baseband subsystem includes a conversion circuit (e.g., a digital-to-analog converter, an analog-to-digital converter) and exchanges analog signals with the radio subsystem. In some examples, the radio subsystem includes a conversion circuit (e.g., a digital-to-analog converter, an analog-to-digital converter) and exchanges digital signals with the baseband subsystem.

[0117] In some cases, the baseband subsystem of modem 112 can transmit wireless network services (e.g., data packets) in a wireless communication network through the radio subsystem on one or more network traffic channels. The baseband subsystem of modem 112 can also send or receive (or both) signals (e.g., motion detection signals or motion detection signals) through the radio subsystem on a dedicated wireless communication channel. In some cases, the baseband subsystem generates a motion detection signal for transmission, for example, to detect a space for movement. In some cases, the baseband subsystem processes a received motion detection signal (a signal based on a motion detection signal sent through the space), for example, to detect the movement of an object in the space.

[0118] Processor 114 can execute instructions, for example, to generate output data based on data input. Instructions can include programs, codes, scripts or other types of data stored in memory. In addition or alternatively, instructions can be encoded as pre-programmed or reprogrammable logic circuits, logic gates or other types of hardware or firmware components. Processor 114 can be or include a general-purpose microprocessor, as a special coprocessor or another type of data processing device. In some cases, processor 114 performs high-level operations of wireless communication device 102C. For example, processor 114 can be configured to execute or interpret software, scripts, programs, functions, executable files or other instructions stored in memory 116. In some embodiments, processor 114 can be included in modem 112.

[0119] The memory 116 may include computer-readable storage media, such as volatile memory devices, non-volatile memory devices, or both. The memory 116 may include one or more read-only memory devices, random access memory devices, buffer memory devices, or a combination of these and other types of memory devices. In some cases, one or more components of the memory may be integrated or otherwise associated with another component of the wireless communication device 102C. The memory 116 may store instructions that are executable by the processor 114. For example, the instructions may include, for example, Fig.17 , Fig.18A , Fig.18B , Fig.19A and Fig.19B One or more operations of the example process described in the instructions for time aligning signals using an interference buffer and a motion detection buffer.

[0120] The power supply unit 118 provides power to other components of the wireless communication device 102C. For example, the other components may operate based on the power provided by the power supply unit 118 through a voltage bus or other connection. In some embodiments, the power supply unit 118 includes a battery or battery system, such as a rechargeable battery. In some embodiments, the power supply unit 118 includes an adapter (e.g., an alternating current (AC) adapter) that receives an external power signal (from an external source) and converts the external power signal to an internal power signal regulated for the components of the wireless communication device 102C. The power supply unit 118 may include other components or operate in another manner.

[0121] exist Figure 1In the example shown, wireless communication devices 102A, 102B transmit wireless signals (e.g., according to a wireless network standard, a motion detection protocol, or in other ways). For example, wireless communication devices 102A, 102B may broadcast wireless motion detection signals (e.g., reference signals, beacon signals, status signals, etc.), or may transmit wireless signals addressed to other devices (e.g., user equipment, client devices, servers, etc.), and other devices (not shown) and wireless communication device 102C may receive the wireless signals transmitted by wireless communication devices 102A, 102B. In some cases, the wireless signals transmitted by wireless communication devices 102A, 102B may be repeated periodically, for example, according to a wireless communication standard or in other ways.

[0122] In the illustrated example, the wireless communication device 102C processes the wireless signals from the wireless communication devices 102A, 102B to detect the motion of an object in the space accessed by the wireless signals, to determine the location of the detected motion, or both. For example, the wireless communication device 102C may perform the following steps with respect to Fig.17 , Fig.18A , Fig.18B , Fig.19A and Fig.19B One or more operations of the described example process or another type of process for detecting motion or determining the location of detected motion. The space accessed by the wireless signal can be an indoor or outdoor space, which can include, for example, one or more fully or partially enclosed areas, an open area without fences, etc. The space can be or can include the interior of a room, multiple rooms, a building, etc. In some cases, the wireless communication system 100 can be modified, for example, so that the wireless communication device 102C can send a wireless signal, and the wireless communication devices 102A, 102B can process the wireless signal from the wireless communication device 102C to detect motion or determine the location of the detected motion.

[0123] The wireless signal used for motion detection may include, for example, a beacon signal (e.g., a Bluetooth beacon, a Wi-Fi beacon, other wireless beacon signals), another standard signal generated for other purposes according to a wireless network standard, or a non-standard signal generated for motion detection or other purposes (e.g., a random signal, a reference signal, etc.). In an example, motion detection may be performed by analyzing one or more training fields carried by the wireless signal or by analyzing other data carried by the signal. In some examples, data will be added for the explicit purpose of motion detection, or the data used will nominally be used for another purpose and used again or repurposed for motion detection. In some examples, the wireless signal propagates through an object (e.g., a wall) before or after interacting with a mobile object, which may allow the movement of the mobile object to be detected without an optical line of sight between the mobile object and the transmitting or receiving hardware. Based on the received signal, the wireless communication device 102C may generate motion detection data. In some cases, the wireless communication device 102C may transmit the motion detection data to another device or system, such as a security system, which may include a control center for monitoring movement within a space such as a room, a building, an outdoor area, etc.

[0124] In some embodiments, the wireless communication devices 102A, 102B may be modified to send a motion detection signal (which may include, for example, a reference signal, a beacon signal, or another signal for detecting motion space) on a wireless communication channel (e.g., a frequency channel or a coding channel) that is separate from the wireless network traffic signal. For example, the wireless communication device 102C may know the modulation applied to the payload of the motion detection signal and the type of data or data structure in the payload, which may reduce the amount of processing performed by the wireless communication device 102C for motion sensing. The header may include additional information, such as an indication of whether another device in the communication system 100 has detected motion, an indication of the modulation type, an identification of the device sending the signal, etc.

[0125] exist Figure 1In the example shown, the wireless communication system 100 is a wireless mesh network having a wireless communication link between each wireless communication device 102. In the example shown, the wireless communication link between the wireless communication device 102C and the wireless communication device 102A can be used to detect the motion detection field 110A, the wireless communication link between the wireless communication device 102C and the wireless communication device 102B can be used to detect the motion detection field 110B, and the wireless communication link between the wireless communication device 102A and the wireless communication device 102B can be used to detect the motion detection field 110C. In some cases, each wireless communication device 102 detects motion in the motion detection field 110 accessed by the device by processing a received signal that is based on a wireless signal sent by the wireless communication device 102 through the motion detection field 110. For example, when Figure 1 As the person 106 is shown moving in the motion detection field 110A and the motion detection field 110C, the wireless communication devices 102 may detect motion based on the signals they receive, which are based on the wireless signals transmitted through the corresponding motion detection field 110. For example, the wireless communication device 102A may detect the motion of the person 106 in the motion detection fields 110A, 110C, the wireless communication device 102B may detect the motion of the person 106 in the motion detection field 110C, and the wireless communication device 102C may detect the motion of the person 106 in the motion detection field 110A.

[0126] In some cases, motion detection field 110 may include, for example, air, a solid material, a liquid, or another medium through which wireless electromagnetic signals may propagate. Figure 1 In the example shown, motion detection field 110A provides a wireless communication channel between wireless communication device 102A and wireless communication device 102C, motion detection field 110B provides a wireless communication channel between wireless communication device 102B and wireless communication device 102C, and motion detection field 110C provides a wireless communication channel between wireless communication device 102A and wireless communication device 102B. In some aspects of operation, wireless signals sent on a wireless communication channel (separate or shared with a wireless communication channel used for network traffic) are used to detect movement of an object in space. The object can be any type of stationary or movable object, and can be animate or inanimate. For example, the object can be a person (e.g., Figure 1The motion information from the wireless communication device may be analyzed to determine the location of the detected motion. For example, as further described below, one of the wireless communication devices 102 (or another device communicatively coupled to the wireless communication device 102) may determine that the detected motion is near a particular wireless communication device.

[0127] Figure 2A and Figure 2B is a diagram showing example wireless signals transmitted between wireless communication devices 204A, 204B, 204C. The wireless communication devices 204A, 204B, 204C may be, for example Figure 1 The wireless communication devices 102A, 102B, 102C shown, or other types of wireless communication devices. The wireless communication devices 204A, 204B, 204C send wireless signals through the space 200. The space 200 can be completely or partially closed or open at one or more boundaries. In an example, the space 200 can be a sensing space. The space 200 can be or can include the interior of a room, multiple rooms, a building, an indoor area, an outdoor area, etc. In the example shown, the first wall 202A, the second wall 202B, and the third wall 202C at least partially enclose the space 200.

[0128] exist Figure 2A and Figure 2B In the example shown, the wireless communication device 204A may be configured to repeatedly (e.g., periodically, intermittently, at scheduled, unscheduled, or random intervals, etc.) transmit wireless signals. The wireless communication devices 204B and 204C may be configured to receive signals based on the signals transmitted by the wireless communication device 204A. The wireless communication devices 204B and 204C may each have a modem (e.g., Figure 1 A modem 112 is shown, which is configured to process received signals to detect movement of objects in the space 200.

[0129] As shown in the figure, the object Figure 2A is in the first position 214A, and the object is in Figure 2B has moved to the second position 214B. Figure 2A and Figure 2B In the figure, the moving object in the space 200 is represented as a person, but the moving object may be another type of object. For example, the moving object may be an animal, an inorganic object (e.g., a system, a device, a device, or a component), an object that defines all or part of the boundaries of the space 200 (e.g., a wall, a door, a window, etc.), or another type of object.

[0130] like Figure 2A and Figure 2B 2 , multiple example paths of a wireless signal transmitted from the wireless communication device 204A are shown by dashed lines. Along a first signal path 216, a wireless signal is transmitted from the wireless communication device 204A and reflects from the first wall 202A toward the wireless communication device 204B. Along a second signal path 218, a wireless signal is transmitted from the wireless communication device 204A and reflects from the second wall 202B and the first wall 202A toward the wireless communication device 204C. Along a third signal path 220, a wireless signal is transmitted from the wireless communication device 204A and reflects from the second wall 202B toward the wireless communication device 204C. Along a fourth signal path 222, a wireless signal is transmitted from the wireless communication device 204A and reflects from the third wall 202C toward the wireless communication device 204B.

[0131] exist Figure 2A In FIG. 2 , along the fifth signal path 224A, the wireless signal is transmitted from the wireless communication device 204A and is reflected from the object at the first location 214A toward the wireless communication device 204C. Figure 2A and Figure 2B During the period between , the surface of the object moves from a first position 214A in the space 200 to a second position 214B (eg, a distance from the first position 214A). Figure 2B In the sixth signal path 224B, the wireless signal is transmitted from the wireless communication device 204A and reflected from the object at the second position 214B toward the wireless communication device 204C. As the object moves from the first position 214A to the second position 214B, Figure 2B The depicted sixth signal path 224B is Figure 2A The depicted fifth signal path 224A is long. In some examples, signal paths may be added, deleted, or otherwise modified due to movement of objects in space.

[0132] Figure 2A and Figure 2B The example wireless signals shown may experience attenuation, frequency shift, phase shift or other effects through their respective paths, and may have a portion that propagates in another direction, such as through first wall 202A, second wall 202B, and third wall 202C. In some examples, the wireless signals are radio frequency (RF) signals. The wireless signals may include other types of signals.

[0133] exist Figure 2A and Figure 2B In the example shown, the wireless communication device 204A can repeatedly send wireless signals. Specifically, Figure 2A shows a wireless signal transmitted from the wireless communication device 204A at a first time, and Figure 2BThe same wireless signal is shown as being sent from the wireless communication device 204A at a later second time. The transmitted signal may be continuously, periodically, randomly, intermittently, etc., or a combination thereof. The transmitted signal may have several frequency components in a frequency bandwidth. The transmitted signal may be sent from the wireless communication device 204A in an omnidirectional manner, a directional manner, or in other ways. In the example shown, the wireless signal passes through a plurality of corresponding paths in the space 200, and the signal along each path may be attenuated due to path loss, scattering, reflection, etc., and may have a phase or frequency offset.

[0134] like Figure 2A and Figure 2B As shown, the signals from the first to sixth paths 216, 218, 220, 222, 224A and 224B are combined at the wireless communication device 204C and the wireless communication device 204B to form a received signal. Due to the influence of multiple paths in the space 200 on the transmitted signal, the space 200 can be represented as a transfer function (e.g., a filter), in which the transmitted signal is input and the received signal is output. When an object moves in the space 200, the attenuation or phase shift affecting the signal in the signal path may change, and therefore, the transfer function of the space 200 may change. Assuming that the same wireless signal is transmitted from the wireless communication device 204A, if the transfer function of the space 200 changes, the output of the transfer function (the received signal) will also change. The change in the received signal can be used to detect the movement of the object.

[0135] Mathematically, the transmitted signal f(t) sent from the first wireless communication device 204A can be described according to equation (1):

[0136]

[0137] where ω n represents the frequency of the nth frequency component of the transmitted signal, c n represents the complex coefficient of the nth frequency component, and t represents time. In the case where f(t) is transmitted from the first wireless communication device 204A, the output signal r from the path k can be described according to equation (2): k (t):

[0138]

[0139] where α n,k represents the attenuation factor (or channel response; e.g. due to scattering, reflection, and path loss) of the nth frequency component along k, and φ n,krepresents the phase of the signal along the nth frequency component of k. Then, the signal R received at the wireless communication device can be described as all the output signals r from all the paths leading to the wireless communication device k The sum of (t) is shown in equation (3):

[0140] R=∑ k r k (t)…(3)

[0141] Substituting equation (2) into equation (3) yields the following equation (4):

[0142]

[0143] Then, R at the wireless communication device can be analyzed. For example, R at the wireless communication device can be transformed into the frequency domain using a fast Fourier transform (FFT) or another type of algorithm. The transformed signal can represent R as a series of n complex values, each of which corresponds to each corresponding frequency component (at n frequencies ω n For frequency ω n The frequency component under the complex value H n It can be expressed in equation (5) as follows:

[0144]

[0145] Given ω n H n Instructions in ω n The relative amplitude and phase shift of the received signal under the condition of H. n Due to the space α n,k The motion detection system may reduce or isolate such effects to improve the accuracy and quality of the motion detection capability. In some embodiments, the overall channel response may be expressed in equation (6) as follows:

[0146]

[0147] In some cases, the spatial channel response h can be determined, for example, based on the mathematical theory of the estimate c" For example, we can use candidate h c" To modify the reference signal R e$ , then the maximum likelihood method can be used to select the signal that matches the received signal (R cvd ) The best matching candidate channel. In some cases, according to R e$ With candidate h c"The convolution of the received signal is estimated Then change h c" The channel coefficients are minimized This can be shown mathematically in equation (7) as follows:

[0148]

[0149] The optimization criterion is shown in equation (8):

[0150]

[0151] The minimization or optimization process can utilize adaptive filtering techniques such as least mean square (LMS), recursive least squares (RLS), batch least squares (BLS), etc. The channel response can be a finite impulse response (FIR) filter, an infinite impulse response (IIR) filter, etc. As shown in the above formula, the received signal can be regarded as the convolution of the reference signal and the channel response. The convolution operation means that the channel coefficients have a certain degree of correlation with each delayed copy of the reference signal. Therefore, the convolution operation shown in the above formula indicates that the received signal appears at different delay points, and each delayed copy is weighted by the channel coefficient.

[0152] Figure 3A and Figure 3B It shows that according to Figure 2A and Figure 2B Graphs of examples of channel responses 360, 370 calculated for wireless signals transmitted between wireless communication devices 204A, 204B, 204C. Figure 3A and Figure 3B Also shown is a frequency domain representation 350 of the initial wireless signal sent by the wireless communication device 204A. In the example shown, Figure 3A The channel response 360 ​​in represents the signal received by the wireless communication device 204B when there is no motion in the space 200, and Figure 3B The channel response 370 in φ represents the channel response after the object has moved in the space 200. Figure 2B The signal received by the wireless communication device 204B in.

[0153] exist Figure 3A and Figure 3BIn the example shown, for purposes of illustration, wireless communication device 204A transmits a signal having a flat frequency distribution (the amplitude of each frequency component f3, f1, and f4 is the same) as shown in frequency domain representation 350. Due to the interaction of the signal with space 200 (and objects therein), the signal received at wireless communication device 204B based on the signal transmitted from wireless communication device 204A is different from the transmitted signal. In this example, where the transmitted signal has a flat frequency distribution, the received signal represents the channel response of space 200. Figure 3A and Figure 3B As shown, the channel responses 360, 370 are different from the frequency domain representation 350 of the transmitted signal. When motion occurs in the space 200, the channel response will also change. For example, Figure 3B As shown, the channel response 370 associated with the motion of the object in the space 200 is different from the channel response 360 ​​associated with the absence of motion within the space 200.

[0154] In addition, when the object moves within space 200, the channel response may be different from channel response 370. In some cases, space 200 may be divided into different regions, and the channel responses associated with each region may share one or more characteristics (e.g., shape), as described below. Thus, the movement of the object within different regions may be distinguished, and the location of the detected movement may be determined based on analysis of the channel response.

[0155] Figure 4A and Figure 4B 401, 403 are diagrams showing example channel responses 401, 403 associated with the motion of an object 406 in different regions 408, 412 of a space 400. In the example shown, the space 400 is a building, and the space 400 is divided into a plurality of different regions, namely a first region 408, a second region 410, a third region 412, a fourth region 414, and a fifth region 416. In some cases, the space 400 may contain additional or fewer regions. Figure 4A and Figure 4B As shown, the areas within space 400 can be defined by walls between rooms. Additionally, the areas can be defined by ceilings between floors of a building. For example, space 400 can include additional floors with additional rooms. Additionally, in some cases, multiple areas of space can be or include several floors in a multi-story building, several rooms in a building, or several rooms on a particular floor of a building. Figure 4A In the example shown, the object located in the first area 408 is represented as a person 406, but the moving object may be another type of object, such as an animal or an inorganic object.

[0156] In the illustrated example, wireless communication device 402A is located in fourth region 414 of space 400, wireless communication device 402B is located in second region 410 of space 400, and wireless communication device 402C is located in fifth region 416 of space 400. Wireless communication devices 402 may be used with Figure 1 The wireless communication device 402 may be configured to transmit and receive wireless signals and detect whether motion has occurred in the space 400 based on the received signals. As an example, the wireless communication device 402 may periodically or repeatedly transmit motion detection signals through the space 400 and receive signals based on the motion detection signals. The wireless communication device 402 may analyze the received signals, for example, by analyzing a channel response associated with the space 400 based on the received signals, to detect whether an object has moved in the space 400. Additionally, in some embodiments, the wireless communication device 402 may analyze the received signals to identify the location of the detected motion within the space 400. For example, the wireless communication device 402 may analyze characteristics of the channel response to determine whether the channel response shares characteristics that are the same or similar to channel responses known to be associated with the first to fifth regions 408, 410, 412, 414, 416 of the space 400.

[0157] In the illustrated example, one (or more) wireless communication devices 402 repeatedly transmit a motion detection signal (e.g., a reference signal) through space 400. In some cases, the motion detection signal may have a flat frequency distribution, where the amplitudes of f3, f1, and f4 are the same or nearly the same. For example, the motion detection signal may have a frequency distribution similar to Figure 3A and Figure 3B The frequency domain shown represents a similar frequency response 350. In some cases, the motion detection signal may have a different frequency distribution. Due to the interaction of the reference signal with the space 400 (and the objects therein), the signal received at the other wireless communication device 402 based on the motion detection signal sent from the other wireless communication device 402 is different from the transmitted reference signal.

[0158] Based on the received signals, wireless communication device 402 can determine a channel response for space 400. When motion occurs in different regions within space, different characteristics can be seen in the channel response. For example, while the channel response may be slightly different for motion within the same region of space 400, the channel responses associated with motion in different regions can generally share the same shape or other characteristics. For example, Figure 4A The channel response 401 of represents an example channel response associated with the motion of the object 406 in the first region 408 of the space 400, while Figure 4BThe channel response 403 of 401 represents an example channel response associated with the motion of the object 406 in the third region 412 of the space 400. The channel responses 401, 403 are associated with signals received by the same wireless communication device 402 in the space 400.

[0159] Figure 4C and Figure 4D It is shown Figure 4A and Figure 4B Graphs of channel responses 401, 403 are superimposed on a channel response 460 associated with no motion occurring in space 400. When motion occurs in space 400, a change in the channel response will occur relative to the channel response 460 associated with no motion, and thus, the motion of an object in space 400 can be detected by analyzing the change in the channel response. Additionally, the relative position of the detected motion within space 400 can be identified. For example, the shape of the channel response associated with the motion can be compared with reference information (e.g., using a trained artificial intelligence (AI) model) to classify the motion as having occurred within a different region of space 400.

[0160] When there is no motion in the space 400 (e.g., when the object 406 is not present), the wireless communication device 402 can calculate a channel response 460 associated with no motion. The channel response may vary slightly due to a variety of factors; however, multiple channel responses 460 associated with different time periods can share one or more characteristics. In the example shown, the channel response 460 associated with no motion has a decreasing frequency distribution (the amplitude of each f3, f1, and f4 is smaller than the previous one). In some cases, the distribution of the channel response 460 may be different (e.g., based on different room layouts or placements of the wireless communication device 402).

[0161] When motion occurs in space 400, the channel response changes. For example, Figure 4C and Figure 4D In the example shown, the channel response 401 associated with the motion of the object 406 in the first area 408 is different from the channel response 460 associated with no motion, and the channel response 403 associated with the motion of the object 406 in the third area 412 is different from the channel response 460 associated with no motion. The channel response 401 has a concave parabolic frequency distribution (the amplitude of the middle frequency component f1 is smaller than the external frequency components f1 and f3), while the channel response 403 has a convex asymptotic frequency distribution (the amplitude of the middle frequency component f2 is larger than the external frequency components f3 and f4). In some cases, the distributions of the channel responses 401, 403 may be different (e.g., based on different room layouts or placements of the wireless communication device 402).

[0162] Analyzing the channel response can be considered similar to analyzing a digital filter. The channel response can be formed by reflections of objects in space and by reflections generated by moving or stationary people. When a reflector (e.g., a person) moves, it changes the channel response. This can be converted into a change in the equivalent taps of the digital filter, which can be considered to have poles and zeros (poles amplify the frequency components of the channel response and appear as peaks or high points in the response, while zeros attenuate the frequency components of the channel response and appear as troughs, low points, or nulls in the response). The changing digital filter can be characterized by the position of its peaks and troughs, and the channel response can be similarly characterized by its peaks and troughs. For example, in some embodiments, motion can be detected by analyzing the nulls and peaks in the frequency components of the channel response (e.g., by marking their positions on the frequency axis and their amplitudes).

[0163] In some embodiments, motion can be detected using time series aggregation. Time series aggregation can be performed by observing the characteristics of the channel response over a moving window and aggregating the windowed results using statistical measurements (e.g., mean, variance, principal component, etc.). During an instance of motion, due to the continuous change of the scattering scene, the characteristic digital filter features will be displaced in position and flipped between certain values. That is, the equivalent digital filter exhibits a range of values ​​for its peak and null values ​​(due to motion). By looking at this range of values, a unique distribution (in an example, a distribution may also be referred to as a signature) can be identified for different regions in space.

[0164] In some embodiments, an AI model can be used to process data. AI models can be of various types, such as linear regression models, logistic regression models, linear discriminant analysis models, decision tree models, naive Bayes models, K nearest neighbor models, learning vector quantization models, support vector machines, bagging and random forest models, and deep neural networks. In general, all AI models are designed to learn functions that provide the most accurate correlation between input values ​​and output values, and are trained using known relevant historical input and output sets. In examples, artificial intelligence can also be referred to as machine learning.

[0165] In some embodiments, the distribution of channel responses associated with motion in different regions of space 400 may be learned. For example, machine learning may be used to classify channel response characteristics based on the motion of objects in different regions of space. In some cases, a user associated with wireless communication device 402 (e.g., an owner or other occupant of space 400) may assist in the learning process. For example, referring to Figure 4A and Figure 4BIn the example shown, the user can move in each of the first through fifth regions 408, 410, 412, 414, 416 during the learning phase and can indicate (e.g., via a user interface on a mobile computing device) that he / she is moving in one of the particular regions in the space 400. For example, when the user moves through the first region 408 (e.g., as shown in FIG. Figure 4A ), a user may indicate on a mobile computing device that he / she is in a first area 408 (and the area may be named "bedroom," "living room," "kitchen," or another type of room of a building, as appropriate). As the user moves through the area, a channel response may be obtained and the channel response may be "tagged" with the location (area) indicated by the user. The user may repeat the same process for other areas of space 400. The term "tagged" as used herein may refer to marking and identifying a channel response with a location indicated by the user or any other information.

[0166] The marked channel responses can then be processed (e.g., by machine learning software) to identify unique characteristics of the channel responses associated with motion in different regions. Once identified, the identified unique characteristics can be used to determine the location of the detected motion of the newly calculated channel response. For example, the marked channel responses can be used to train the AI ​​model, and once trained, the newly calculated channel response can be input to the AI ​​model, and the AI ​​model can output the location of the detected motion. For example, in some cases, the mean, range, and absolute value are input to the AI ​​model. In some cases, the amplitude and phase of the complex channel response itself can also be input. These values ​​allow the AI ​​model to design any front-end filter to obtain the features most relevant to accurately predicting motion in different spatial regions. In some embodiments, the AI ​​model is trained by performing stochastic gradient descent. For example, the most active channel response changes during a particular region can be monitored during training, and specific channel changes can be reweighted (by training and adjusting the weights in the first layer to be associated with these shapes, trends, etc.). Weighted channel changes can be used to create metrics that are activated when a user is present in a particular area.

[0167] For extracted features, such as channel response nulls and peaks, a time series (of nulls / peaks) can be created using aggregation within a moving window to get a snapshot of a few features in the past and present, and use the aggregated values ​​as input to the network. Thus, the network, while adjusting its weights, will try to aggregate the values ​​in a specific area to cluster them, which can be done by creating a decision surface based on a logistic classifier. The decision surface divides different clusters, and subsequent layers can form categories based on a single cluster or a combination of clusters.

[0168] In some embodiments, the AI ​​model includes two or more layers of reasoning. The first layer acts as a logical classifier, which can divide the values ​​in different sets into separate clusters, while the second layer combines some of these clusters together to create categories for different regions. In addition, subsequent layers can help expand different regions to clusters of more than two categories. For example, a fully connected AI model may include an input layer corresponding to the number of tracked features, an intermediate layer corresponding to the number of valid clusters (by iterating between selections), and a final layer corresponding to different regions. In the case where the complete channel response information is input to the AI ​​model, the first layer can act as a shape filter that can be associated with a specific shape. Therefore, the first layer can lock a specific shape, the second layer can generate a measure of the changes that occur in these shapes, and the third and subsequent layers can create a combination of these changes and map them to different regions in space. The outputs of different layers can then be combined by a fusion layer.

[0169] B. Wi-Fi Sensing System Example Methods and Apparatus

[0170] Section B describes systems and methods that may be used in a wireless sensing system configured to send sensing transmissions and make sensing measurements.

[0171] Figure 5 Some architectural implementations of an implementation of a system 500 for Wi-Fi sensing in accordance with some embodiments are depicted.

[0172] The system 500 may include a plurality of networked devices. In an embodiment, the plurality of networked devices may include a plurality of sensing receivers 502-(1-M), a plurality of sensing transmitters 504-(1-N), and a remote processing device 506. In an example, the plurality of sensing receivers 502-(1-M) and the plurality of sensing transmitters 504-(1-N) may belong to more than one basic service set (BSS). In addition, the system 500 may include a network 560 that enables communication between system components to exchange information. The system 500 may be an example or instance of the wireless communication system 100, and the network 560 may be an example or instance of a wireless network or a cellular network, for details of which refer to Figure 1 and its accompanying description. In some embodiments, one or more of the plurality of sensing transmitters 504-(1-N) may not be associated with one or more of the plurality of sensing receivers 502-(1-M) (i.e., may be non-associated). In an example, the plurality of sensing receivers 502-(1-M) may include at least a first sensing receiver 502-1 and a second sensing receiver 502-2. Similarly, the plurality of sensing transmitters 504-(1-N) may include at least a first sensing transmitter 504-1 and a second sensing transmitter 504-2.

[0173] For ease of explanation and understanding, the description provided below is made with reference to the first sensing receiver 502-1 and the first sensing transmitter 504-1, however, the description is also applicable to the remaining sensing receivers 502-(2-M) and the remaining sensing transmitters 504-(2-N).

[0174] According to an embodiment, the first sensing receiver 502-1 may be configured to receive a sensing transmission from the sensing transmitter 504-1 and perform one or more measurements applicable to Wi-Fi sensing (e.g., channel representation information (CRI), such as channel state information (CSI) or time domain channel representation information (TD-CRI)). These measurements may be referred to as sensing measurements. The sensing measurements may be processed to achieve the sensing goals of the system 500, such as detecting motion or gestures. In an embodiment, one or more of the plurality of sensing receivers 502-(1-M) may be an AP. In some embodiments, one or more of the plurality of sensing receivers 502-(1-M) may act as a sensing initiator and / or a sensing responder. In an embodiment, the first sensing receiver 502-1 may be a non-AP station (STA). In some embodiments, the first sensing transmitter 504-1 may be an access point (AP). In an example, the first sensing receiver 502-1 may be an outside BSS (OBSS) STA (i.e., a STA that is not associated with an OBSS AP such as the sensing transmitter 504-1 and is therefore not time synchronized with the OBSS AP).

[0175] According to an embodiment, the first sensing receiver 502-1 may be provided by, for example, Figure 1 In some embodiments, the first sensing receiver 502-1 may be implemented by, for example, the wireless communication device 102 shown in FIG. Figure 2A and Figure 2B In addition, the first sensing receiver 502-1 may be implemented by, for example, the wireless communication device 204 shown in FIG. Figure 4A and Figure 4B4-M). In an embodiment, one or more of the plurality of sensing receivers 502-(1-M) may coordinate and control the communication between the plurality of sensing transmitters 504-(1-N). According to an embodiment, one or more of the plurality of sensing receivers 502-(1-M) may be enabled to control a sensing measurement session including one or more sensing measurement instances to ensure that the required sensing transmission is performed at the required time and that the one or more sensing measurements are accurately determined. In some embodiments, one or more of the plurality of sensing receivers 502-(1-M) may process sensing measurements to achieve the sensing objectives of the system 500. In an embodiment, one or more of the plurality of sensing receivers 502-(1-M) may be STAs. In an embodiment, one or more of the plurality of sensing receivers 502-(1-M) may be APs. In some embodiments, the first sensing receiver 502-1 may be any computing device, such as a desktop computer, a laptop computer, a tablet computer, a mobile device, a personal digital assistant (PDA), or any other computing device. In some embodiments, the first sensing receiver 502-1 may process sensing measurements to achieve the sensing results of the system 500. In some embodiments, the first sensing receiver 502 - 1 may be configured to send the sensing measurements to the sensing transmitter 504 - 1 , and the sensing transmitter 504 - 1 may be configured to process the sensing measurements to achieve a sensing result of the system 500 .

[0176] Reference again Figure 5 In some embodiments, the first sensing transmitter 504-1 may be configured to transmit one or more sensing transmissions to one or more of the plurality of sensing receivers 502-(1-M), based on which one or more sensing measurements (e.g., channel state information) may be performed for Wi-Fi sensing. In an embodiment, the first sensing transmitter 504-1 may be an AP. In some embodiments, the first sensing transmitter 504-1 may be a STA, for example, where the first sensing receiver 502-1 is an AP. In an example, the first sensing transmitter 504-1 may be an OBSS AP (i.e., an AP that is not associated with an OBSS STA, such as the sensing receiver 502-1, and is therefore not time synchronized with the OBSS STA).

[0177] According to an embodiment, the first sensing transmitter 504-1 may be provided by, for example, Figure 1 In some embodiments, the first sensing transmitter 504-1 may be implemented by a device such as the wireless communication device 102 shown in FIG. Figure 2A and 2B In addition, the first sensing transmitter 504-1 may be implemented by, for example, the wireless communication device 204 shown in FIG. Figure 4A and4B In some embodiments, the first sensing receiver 502-1 may be implemented by a device such as the wireless communication device 402 shown in FIG. 4 . In some embodiments, the first sensing transmitter 504-1 may be any computing device, such as a desktop computer, a laptop computer, a tablet computer, a mobile device, a PDA, or any other computing device. In some embodiments, the communication between the first sensing receiver 502-1 and the first sensing transmitter 504-1 may occur via a station management entity (SME) and a MAC layer management entity (MLME) protocol.

[0178] In some embodiments, the remote processing device 506 may be configured to receive sensing measurements from one or more of the plurality of sensing receivers 502-(1-M) and process the sensing measurements. In an example, the remote processing device 506 may process and analyze the sensing measurements to identify one or more features of interest. According to some embodiments, the remote processing device 506 may include / execute a sensing algorithm. In an embodiment, the remote processing device 506 may be a STA. In some embodiments, the remote processing device 506 may be an AP. According to embodiments, the remote processing device 506 may be, for example, Figure 1 In some embodiments, the remote processing device 506 may be implemented by, for example, the wireless communication device 102 shown in FIG. Figure 2A and Figure 2B The remote processing device 506 may be implemented by a device such as the wireless communication device 204 shown in FIG. Figure 4A and Figure 4B The remote processing device 506 may be implemented by a device such as the wireless communication device 402 shown in FIG. In some embodiments, the remote processing device 506 may be any computing device, such as a desktop computer, a laptop computer, a tablet computer, a mobile device, a personal digital assistant (PDA), or any other computing device. In an embodiment, the remote processing device 506 may act as a sensing initiator, where the sensing algorithm determines the Wi-Fi sensing session and the sensing measurements required to complete the measurement activity. In an example, the remote processing device 506 may transmit the sensing measurement parameters and / or transmission parameters required to initiate the Wi-Fi sensing session to one or more of the plurality of sensing receivers 502-(1-M) and / or one or more of the plurality of sensing transmitters 504-(1-N) to coordinate and control the sensing transmissions used to perform the sensing measurements.

[0179] refer to Figure 5 In more detail, the first sensing receiver 502-1 (which is an example of one or more of the plurality of sensing receivers 502-(1-M)) may include a processor 508-1 and a memory 510-1. For example, the processor 508-1 and the memory 510-1 of the first sensing receiver 502-1 may be respectively as follows: Figure 1The processor 114 and memory 116 shown. In an embodiment, the first sensing receiver 502-1 may further include a transmitting antenna 512-1, a receiving antenna 514-1, and a sensing agent 516-1. In some embodiments, the antenna may be used to send and receive signals in a half-duplex format. When the antenna is transmitting, it may be referred to as a transmitting antenna 512-1, and when the antenna is receiving, it may be referred to as a receiving antenna 514-1. It should be understood by those of ordinary skill in the art that the same antenna may be a transmitting antenna 512-1 in some cases and a receiving antenna 514-1 in other cases. In the case of an antenna array, for example, in a beamforming environment, one or more antenna elements may be used to send or receive signals. In some examples, a group of antenna elements for sending a composite signal may be referred to as a transmitting antenna 512-1, and a group of antenna elements for receiving a composite signal may be referred to as a receiving antenna 514-1. In some examples, each antenna is equipped with its own transmit and receive paths, which may be alternately switched to connect to the antenna depending on whether the antenna is operated as a transmitting antenna 512-1 or as a receiving antenna 514-1.

[0180] In an embodiment, the sensing agent 516-1 may be responsible for causing the sensing receiver 502-1 to receive the sensing transmission and the associated sensing measurement parameters and / or transmission parameters to calculate the sensing measurement. In an example, the sensing agent 516-1 may be responsible for processing the sensing measurement to complete the sensing target. In some embodiments, receiving the sensing transmission and optionally receiving the associated sensing measurement parameters and / or transmission parameters and calculating the sensing measurement may be performed by the sensing agent 516-1 running in the medium access control (MAC) layer of the sensing receiver 502-1, and processing the sensing measurement to complete the sensing target may be performed by an algorithm running in the application layer of the sensing receiver 502-1, for example, by the sensing algorithm 518-1. In an example, the sensing algorithm 518-1 running in the application layer of the sensing receiver 502-1 may be referred to as a Wi-Fi sensing agent, a sensing application, or a sensing algorithm. In an example, the sensing algorithm 518-1 may include and / or execute the sensing agent 516-1. According to some embodiments, the sensing agent 516-1 may include and / or execute the sensing algorithm 518-1. In some embodiments, the sensing agent 516-1 running in the MAC layer of the sensing receiver 502-1 and the sensing algorithm 518-1 running in the application layer of the sensing receiver 502-1 can be run separately on the processor 508-1. In an embodiment, the sensing agent 516-1 can pass one or more of the sensing measurement parameters, transmission parameters or physical layer parameters (e.g., channel representation information, examples of which are CSI and TD-CRI) between the MAC layer of the sensing receiver 502-1 and the application layer of the sensing receiver 502-1. In an example, the sensing agent 516-1 in the MAC layer or the sensing algorithm 518-1 in the application layer can operate on the physical layer parameters, for example, to detect one or more features of interest. In an example, the sensing algorithm 518-1 can form services or features that can be presented to an end user. According to an embodiment, the communication between the MAC layer of the sensing receiver 502-1 and other layers or components (including the application layer) of the sensing receiver 502-1 can occur based on communication interfaces such as MLME interfaces and data interfaces. In an example, for the purpose of Wi-Fi sensing, the sensing agent 516-1 can be configured to determine the number and timing of sensing transmissions and sensing measurements. In some embodiments, the sensing agent 516-1 can be configured to send the sensing measurements to the plurality of sensing transmitters 504-(1-N) and / or the remote processing device 506 for further processing. In an embodiment, the sensing agent 516-1 can be configured to cause at least one of the transmit antennas 512-1 to send a message to one or more of the plurality of sensing transmitters 504-(1-N) or to the remote processing device 506.In addition, the sensing agent 516-1 can be configured to receive messages from at least one of the plurality of sensing transmitters 504-(1-N) or from the remote processing device 506 via at least one of the receiving antennas 514-1. In an example, the sensing agent 516-1 can be configured to make sensing measurements based on sensing transmissions received from one or more of the plurality of sensing transmitters 504-(1-N).

[0181] In an example, the sensing receiver 502-1 may include a timestamp generation block 524-1. In an embodiment, the timestamp generation block 524-1 may be coupled to the processor 508-1 and the memory 510-1. In some embodiments, the timestamp generation block 524-1 may include routines, programs, objects, components, data structures, etc. that may perform specific tasks or implement specific abstract data types, as well as other units. The timestamp generation block 524-1 may also be implemented as a signal processor, a state machine, a logic circuit, and / or any other device or component that manipulates a signal based on an operating instruction.

[0182] In some embodiments, timestamp generation block 524-1 can be implemented with hardware, instructions executed by a processing unit, or a combination thereof. A processing unit may include a computer, a processor, a state machine, a logic array, or any other suitable device capable of processing instructions. A processing unit may be a general-purpose processor that executes instructions to enable a general-purpose processor to perform a desired task, or a processing unit may be dedicated to performing a desired function. In some embodiments, timestamp generation block 524-1 may be a machine-readable instruction that performs any desired function when executed by a processor / processing unit. Machine-readable instructions may be stored in an electronic storage device, a hard disk, an optical disk, or other machine-readable storage medium or a non-temporary medium. In an embodiment, machine-readable instructions may also be downloaded to a storage medium via a network connection. In an example, machine-readable instructions may be stored in memory 510-1.

[0183] Reference again Figure 5 , the first sensing receiver 502-1 may include a TSF timer 523-1 (also referred to as an OBSSSTA TSF timer). In an embodiment, the TSF timer 523-1 may be a local timer / clock in the first sensing receiver 502-1. In an example, the TSF timer 523-1 may be based on a 1 MHz clock and may tick in time units (TUs), where 1TU is equal to 1.024 microseconds. In an example, the TSF timer 523-1 may be represented by an 8-octet (64-bit) register [63:0] that increments every microsecond.

[0184] According to an embodiment, the first sensing receiver 502-1 may further include a sensing transmitter information storage device 521-1 and a sensing measurement storage device 520-1. In an embodiment, the sensing transmitter information storage device 521-1 may store information related to multiple sensing transmitters 504-(1-N). In an example, the sensing transmitter information storage device 521-1 may store information related to a TSF timer, and the TSF timer is associated with one or more of one or more of the multiple sensing transmitters 504-(1-N). The first sensing receiver 502-1 may further include a resynchronization timer 526-(1-N) associated with one or more of the multiple sensing transmitters 504-(1-N). In an example, the sensing transmitter information storage device 521-1 may store local timing information. In some examples, the sensing transmitter information storage device 521-1 may store a timer offset value. In an embodiment, the sensing measurement storage device 520-1 can store sensing measurements calculated by the first sensing receiver 502-1 based on sensing transmissions received from one or more of the multiple sensing transmitters 504-(1-N). The information stored in the sensing transmitter information storage device 521-1 and the sensing measurement storage device 520-1 can be updated periodically or dynamically as needed. In some embodiments, the sensing receiver 502-1 can include a sensing measurement parameter storage device 522-1. In an embodiment, the sensing measurement parameter storage device 522-1 can store sensing measurement parameters and / or transmission parameters applicable to one or more sensing measurement establishments. In an embodiment, the sensing measurement parameter storage device 522-1 can store sensing measurement parameters and / or transmission parameters applicable to one or more sensing measurement sessions. In an embodiment, the sensing measurement parameter storage device 522-1 can store sensing measurement parameters and / or transmission parameters applicable to one or more sensing measurement instances. In an example, the sensing measurement parameters and / or transmission parameters stored in the sensing measurement parameter storage device 522-1 can be updated periodically or dynamically as needed. In an embodiment, the sensing transmitter information storage device 521-(1-N) can store information of one or more of the plurality of sensing transmitters 504-(1-N) from which the sensing receiver 502-1 receives sensing transmissions. The information stored in the sensing transmitter information storage device 521-(1-N) can be updated periodically or dynamically as needed. In an embodiment, the sensing transmitter information storage device 521-(1-N) can include any type or form of storage device, such as a database or file system coupled to the memory 510-1. In some embodiments, the sensing measurement storage device 520-1 and / or the sensing measurement parameter storage device 522-1 can include any type or form of storage device, such as a database or file system coupled to the memory 510-1.

[0185] Reference again Figure 5 , the first sensing transmitter 504-1 may include a processor 528-1 and a memory 530-1. For example, the processor 528-1 and the memory 530-1 of the first sensing transmitter 504-1 may be respectively as follows Figure 1 The processor 114 and memory 116 shown. In an embodiment, the first sensing transmitter 504-1 may further include a transmitting antenna 532-1, a receiving antenna 534-1, and a sensing agent 536-1. In an embodiment, the sensing agent 536-1 may be a block that passes physical layer parameters from the MAC of the first sensing transmitter 504-1 to the application layer program. The sensing agent 536-1 may be configured to enable at least one of the transmitting antennas 532-1 and at least one of the receiving antennas 534-1 to exchange messages with one or more of the multiple sensing receivers 502-(1-M).

[0186] In an embodiment, the sensing agent 536-1 may be responsible for causing the sensing transmitter 504-1 to send a sensing transmission, and in an example, receiving associated sensing measurements from one or more of the multiple sensing receivers 502-(1-M). In an example, the sensing agent 536-1 may be responsible for processing the sensing measurements to complete the sensing target. In some embodiments, the sensing agent 536-1 may run in the medium access control (MAC) layer of the sensing transmitter 504-1, and processing the sensing measurements to complete the sensing target may be performed by the sensing algorithm 538-1, which may run in the application layer of the sensing transmitter 504-1 in an example. In an example, the sensing algorithm 538-1 running in the application layer of the sensing transmitter 504-1 may be referred to as a Wi-Fi sensing agent, a sensing application, or a sensing algorithm. In an example, the sensing algorithm 538-1 may include and / or execute the sensing agent 536-1. According to some embodiments, the sensing agent 536-1 may include and / or execute the sensing algorithm 538-1. In some embodiments, the sensing agent 536-1 can run in the MAC layer of the sensing transmitter 504-1, and the sensing algorithm 538-1 can run in the application layer of the sensing transmitter 504-1. In some embodiments, the sensing agent 536-1 and the sensing algorithm 538-1 of the sensing transmitter 504-1 can be run separately on the processor 528-1. In an embodiment, the sensing agent 536-1 can pass sensing measurement parameters, transmission parameters, or physical layer parameters between the MAC layer of the sensing transmitter 504-1 and the application layer of the sensing transmitter 504-1. In an example, the sensing agent 536-1 in the MAC layer or the sensing algorithm 538-1 in the application layer can control the physical layer parameters, such as the physical layer parameters for generating one or more sensing transmissions. In an example, the sensing algorithm 538-1 can form a service or feature, which can be presented to an end user. According to the embodiment, the communication between the MAC layer of the sensing transmitter 504-1 and other layers or components (including the application layer) of the sensing transmitter 504-1 can occur based on communication interfaces such as MLME interfaces and data interfaces. In the example, for the purpose of Wi-Fi sensing, the sensing agent 536-1 can be configured to determine the number and timing of sensing transmissions. In some embodiments, the sensing agent 536-1 can be configured to cause the sensing transmitter 504-1 to send the sensing transmission to one or more of the multiple sensing receivers 502-(1-M). In the embodiment, the sensing agent 536-1 can be configured to cause at least one of the transmitting antennas 532-1 to send a message to one or more of the multiple sensing receivers 502-(1-M) or to the remote processing device 506.Furthermore, the sensing agent 536 - 1 may be configured to receive messages from one or more of the plurality of sensing receivers 502 -( 1 -M) or from the remote processing device 506 via at least one of the receiving antennas 534 - 1 .

[0187] In some embodiments, the antenna can be used to transmit and receive in a half-duplex format. When the antenna transmits, it can be referred to as a transmit antenna 512-1 / 532-1, and when the antenna receives, it can be referred to as a receive antenna 514-1 / 534-1. It should be understood by those of ordinary skill in the art that the same antenna can be a transmit antenna 512-1 / 532-1 in some cases and a receive antenna 514-1 / 534-1 in other cases. In the case of an antenna array, for example, in a beamforming environment, one or more antenna elements can be used to transmit or receive signals. In some examples, a group of antenna elements for transmitting a composite signal can be referred to as a transmit antenna 512-1 / 532-1, and a group of antenna elements for receiving a composite signal can be referred to as a receive antenna 514-1 / 534-1. In some examples, each antenna is equipped with its own transmit and receive paths, which can be switched alternately to connect to the antenna depending on whether the antenna is operated as a transmit antenna 512-1 / 532-1 or as a receive antenna 514-1 / 534-1.

[0188] Reference again Figure 5, the first sensing transmitter 504-1 may include a TSF timer 543-1. In an embodiment, the TSF timer 543-1 (also referred to as the OBSS AP TSF timer) may be a local timer / clock in the first sensing transmitter 504-1. In an example, the TSF timer 543-1 may be based on a 1MHz clock and may tick in units of TU, ​​where 1TU is equal to 1.024 microseconds. In an example, the TSF timer 543-1 may be represented by an 8-octet (64-bit) register [63:0] that increments per microsecond. In an embodiment, the first sensing transmitter 504-1 may include a plurality of resynchronization timers 546-(1-M) corresponding to a plurality of sensing receivers 502-(1-M). In an example, the first resynchronization timer 546-1 may correspond to the first sensing receiver 502-1, the second resynchronization timer 546-2 may correspond to the second sensing receiver 502-2, and so on. According to an embodiment, the first sensing transmitter 504-1 may further include a sensing receiver information storage device 541-(1-M). In an embodiment, the sensing receiver information storage device 541-(1-M) may store information of one or more of the plurality of sensing receivers 502-(1-M) to which the sensing receiver information storage device sends sensing transmissions. The information stored in the sensing receiver information storage device 541-(1-M) may be updated periodically or dynamically as needed. In an embodiment, the sensing receiver information storage device 541-(1-M) may include any type or form of storage device, such as a database or file system coupled to the memory 530-1.

[0189] In some embodiments, the sensing transmitter 504-1 may include a sensing measurement parameter storage device 542-1. In an embodiment, the sensing measurement parameter storage device 542-1 may store sensing measurement parameters and / or transmission parameters applicable to one or more sensing measurement sessions. In an embodiment, the sensing measurement parameter storage device 542-1 may store sensing measurement parameters and / or transmission parameters applicable to one or more sensing measurement establishments. In an embodiment, the sensing measurement parameter storage device 542-1 may store sensing measurement parameters and / or transmission parameters applicable to one or more sensing measurement instances. In an example, the sensing measurement parameters and / or transmission parameters stored in the sensing measurement parameter storage device 542-1 may be updated periodically or dynamically as needed. In an embodiment, the sensing measurement storage device 540-1 and the sensing measurement parameter storage device 542-1 may include any type or form of storage device, such as a database or file system coupled to the memory 530-1.

[0190] Reference again Figure 5, the remote processing device 506 may include a processor 548 and a memory 550. For example, the processor 548 and the memory 550 of the remote processing device 506 may be respectively Figure 1 The processor 114 and memory 116 shown. In an embodiment, the remote processing device 506 may further include a transmitting antenna 552, a receiving antenna 554, a sensing agent 556, and a sensing algorithm 558. In some embodiments, the antenna can be used to send and receive signals in a half-duplex format. When the antenna is transmitting, it can be referred to as a transmitting antenna 552, and when the antenna is receiving, it can be referred to as a receiving antenna 554. It should be understood by those of ordinary skill in the art that the same antenna can be a transmitting antenna 552 in some cases and a receiving antenna 554 in other cases. In the case of an antenna array, for example, in a beamforming environment, one or more antenna elements can be used to send or receive signals. In some examples, a group of antenna elements for sending a composite signal can be referred to as a transmitting antenna 552, and a group of antenna elements for receiving a composite signal can be referred to as a receiving antenna 554. In some examples, each antenna is equipped with its own transmit and receive paths, which can be switched alternately to connect to the antenna depending on whether the antenna is operated as a transmitting antenna 552 or as a receiving antenna 554.

[0191] In an embodiment, the sensing agent 556 may be responsible for determining sensing measurement parameters and / or transmission parameters for establishing one or more sensing measurements. In an example, the sensing agent 556 may receive sensing measurement parameters and / or transmission parameters for establishing one or more sensing measurements from the sensing algorithm 558. In an example, the sensing agent 556 may receive sensing measurements from one or more of the multiple sensing receivers 502-(1-M), and may process the sensing measurements to complete the sensing target. In an example, the sensing agent 556 may receive channel representation information (e.g., CSI or TD-CRI) from one or more of the multiple sensing receivers 502-(1-M), and may process the channel representation information to complete the sensing target. In an embodiment, the sensing agent 556 may receive sensing measurements or channel representation information, and may provide the received sensing measurements or channel representation information to the sensing algorithm 558, and the sensing algorithm 558 may receive sensing measurements or channel representation information from the sensing agent 556, and may process the information to complete the sensing target.

[0192] In some embodiments, receiving sensing measurements may be performed by an algorithm running in a medium access control (MAC) layer of the remote processing device 506, and processing the sensing measurements to complete the sensing objectives may be performed by an algorithm running in an application layer of the remote processing device 506. In an example, the algorithm running in the application layer of the remote processing device 506 may be referred to as a Wi-Fi sensing agent, a sensing application, or a sensing algorithm. In some embodiments, the algorithm running in the MAC layer of the remote processing device 506 and the algorithm running in the application layer of the remote processing device 506 may run separately on the processor 548. In an embodiment, the sensing agent 556 may pass physical layer parameters (e.g., channel representation information, examples of which are CSI and TD-CRI) from the MAC layer of the remote processing device 506 to the application layer of the remote processing device 506, and the physical layer parameters may be used to detect one or more features of interest. In an example, the application layer may operate on the physical layer parameters and form services or features that may be presented to an end user. According to an embodiment, the communication between the MAC layer of the remote processing device 506 and other layers or components of the remote processing device 506 can be based on communication interfaces such as MLME interfaces and data interfaces. According to some embodiments, the sensing agent 556 can include / execute a sensing algorithm 558. In an embodiment, the sensing agent 556 can use the sensing algorithm 558 to process and analyze sensing measurements and identify one or more features of interest. In addition, for the purpose of Wi-Fi sensing, the sensing agent 556 can be configured to determine the number and timing of sensing transmissions and sensing measurements. In some embodiments, the sensing agent 556 can be configured to cause one or more of the multiple sensing transmitters 504-(1-N) to send sensing measurements to one or more of the multiple sensing transmitters 502-(1-M).

[0193] Returning to reference 5, according to one or more embodiments, the Wi-Fi sensing system 500 can participate in a sensing session. In an example, a sensing session is a protocol between a sensing initiator and a sensing responder to participate in a WLAN sensing process (also referred to as a Wi-Fi sensing process). In an example, sensing measurement parameters associated with a sensing session can be determined by a sensing initiator and can be exchanged between the sensing initiator and the sensing responder. In an example, the sensing initiator can be a sensing transmitter 504-1, and the sensing responder can be a sensing receiver 502-1. In an example, the sensing initiator can be a sensing receiver 502-1, and the sensing responder can be a sensing transmitter 504-1. In an example, the sensing initiator can be a remote processing device 506, and the sensing transmitter 504-1 and the sensing receiver 502-1 are both sensing responders. In an example, the sensing transmitter 504-1 can participate in multiple sensing sessions as a sensing initiator or as a sensing responder. In an example, the sensing receiver 502-1 can participate in multiple sensing sessions as a sensing initiator or as a sensing responder. In an example, the remote processing device can participate in multiple sensing sessions as a sensing initiator.

[0194] According to one or more embodiments, communications in network 560 may be managed by one or more of the 802.11 family of standards developed by IEEE. Some example IEEE standards may include IEEE 802.11-2020, IEEE 802.11ax-2021, IEEE 802.11me, IEEE 802.11az, and IEEE 802.11be. IEEE 802.11-2020 and IEEE 802.11ax-2021 are fully ratified standards, while IEEE 802.11me reflects ongoing maintenance updates to the IEEE 802.11-2020 standard, and IEEE 802.11be defines the next generation standard. IEEE 802.11az is an extension of the IEEE 802.11-2020 and IEEE 802.11ax-2021 standards, adding new functionality. In some embodiments, communications may be managed by other standards (other or additional IEEE standards or other types of standards). In some embodiments, the system 500 does not require that the portion of the network 560 managed by one or more of the 802.11 family of standards be implemented by an instance of any type of network, including a wireless network or a cellular network. In addition, IEEE 802.11ax includes OFDMA, which allows the sensing receiver 502 to simultaneously send data to all participating devices, such as multiple sensing transmitters 504-(1-N), using a single transmission opportunity (TXOP), and vice versa. The efficiency of OFDMA depends on how the sensing receiver 502 schedules channel resources (interchangeably referred to as RUs) and configures transmission parameters between multiple sensing transmitters 504-(1-N). According to an embodiment, the system 500 can be a system that supports OFDMA.

[0195] C. System and Method for Time Synchronization of Sensing Measurements Outside of a BSS

[0196] The present disclosure generally relates to systems and methods for Wi-Fi sensing. Specifically, the present disclosure relates to systems and methods for time synchronization of sensing measurements outside of a basic service set (OBSS).

[0197] A Wi-Fi sensing system may be configured to detect features of interest in a sensing space. A Wi-Fi sensing system may be a network of Wi-Fi enabled devices that are part of an IEEE 802.11 network (sometimes referred to as a basic service set (BSS) or extended service set (ESS)). Features of interest may include motion and movement tracking of objects, presence detection, intrusion detection, gesture recognition, fall detection, breathing rate detection, and other applications. A sensing space may refer to any physical space in which a Wi-Fi sensing system may operate, and may include a residence, a workplace, a shopping mall, a gymnasium or stadium, a garden, or any other physical space.

[0198] A typical Wi-Fi sensing system includes a sensing transmitter (which can be a station (STA) or an access point (AP)) and a sensing receiver (if the sensing transmitter is a STA, it is an AP, and if the sensing transmitter is an AP, it is a STA). Figure 6 An example representation 600 of a typical Wi-Fi sensing system according to some embodiments is depicted in FIG. Figure 6 As described, the Wi-Fi sensing system includes a sensing receiver 602 and a sensing transmitter 604. The sensing receiver 602 may be an example of the sensing receiver 502-1. The sensing transmitter 604 may be an example of the sensing transmitter 504-1. In addition, the sensing transmission 606 is performed from the sensing transmitter 604 to the sensing receiver 602, such as Figure 6 The sensing receiver 602 may perform sensing measurements on the sensing transmission 606 .

[0199] IEEE 802.11 specifies a timing synchronization function (TSF) for achieving timing synchronization between various devices. In the example, the TSF synchronizes the TSF timers of all STAs in the same BSS. The STA maintains a local TSF timer, which is synchronized with the AP TSF timer of the AP to which the STA is associated. Figure 5 , the sensing receiver 502-(1-M) maintains a corresponding local TSF timer 523-(1-M), and the local TSF timer is incremented according to the oscillator (e.g., a local crystal oscillator or a voltage-controlled oscillator) of the sensing receiver 502-(1-M).

[0200] According to an embodiment, Pre-Association Security Negotiation (PASN) can be a Robust Security Network (RSN) Association Authentication Protocol in scenarios that rely on the presence of a Pairwise Master Key Security Association (PMKSA) for authentication and key management (AKM). PASN is introduced in IEEE 802.11az and allows for pre-association encryption exchanges between STAs and APs.

[0201] Figure 7Depicted is a process 700 for PASN authentication according to some embodiments. Figure 7 It is from draft P802.11az_D4.1 Figure 12-5 A reappearance of 5a. Figure 7 , STA 702 may be the supplicant and AP 704 may be the authenticator. In an embodiment, AP 704 may indicate that the AP is capable of performing PASN authentication by including a PASN AKM as part of an RSN element (RSNE) included in beacon frames and probe response frames.

[0202] At step 706 of process 700, AP 704 may send a beacon (RSNE (PASN AKM, Base AKM), [RSNXE]). At step 708 of process 700, STA 702 may send an 802.11 authentication (1, PASN, RSNE (Base AKM, PMKID [0..n]), [RSNXE], S-Ephemeral Pub, PASN Parameters, Base AKM Data-1) to AP 704. At step 710 of process 700, AP 704 may send 802.11 authentication ((2, PASN, RSNE (BaseAKM, PMKID [0..n]), [RSNXE], A-Ephemeral Pub, PASN Parameters, Base AKM Data-2, MIC) to STA 702. At step 712 of process 700, STA 702 may send 802.11 authentication (3, Base AKM Data-3, MIC) to AP 704.

[0203] In an implementation scheme, three PASN frames may be constructed, namely a first PASN frame, a second PASN frame, and a third PASN frame. The first PASN frame may be sent from a STA to an AP. If the STA initiates PASN authentication, the STA may first select authentication parameters and then may write an RSNE. The STA may send the first PASN frame to the AP. After receiving the first PASN frame, the AP may start constructing a second PASN frame, and when completed, the AP may send the second PASN frame to the STA. After receiving the second PASN frame, the STA may start constructing a third PASN frame, and when completed, the STA may send the third PASN frame to the AP and then install a time key derived using the MLME-SETKEYS.request primitive. The AP may install a time key derived using the MLME-SETKEYS.request primitive. Currently, the PASN process may be used for ranging of non-associated STAs (as described in draft P802.11az_D4.1).

[0204] According to an embodiment, an out-of-BSS (OBSS) scenario may refer to a scenario in which an AP (also referred to as an OBSS AP, which is an example of a sensing transmitter 504-1) and a STA (also referred to as an OBSS STA, which is an example of a sensing receiver 502-1) are not associated with each other. In an example, in an OBSS scenario, a TSF timer of the OBSS AP (543-1) and a TSF timer of the OBSS STA (523-1) may not be time-aligned. Therefore, the OBSS AP 504-1 and the OBSS STA 502-1 may not be time-synchronized.

[0205] In an embodiment, if the sensing initiator is a sensing transmitter (i.e., an AP, such as sensing transmitter 504-1), the sensing transmitter may send a sensing transmission to a sensing receiver (i.e., a STA, such as sensing receiver 502-1), and sensing receiver 502-1 may perform a sensing measurement on the sensing transmission. In some examples, it may be necessary for sensing receiver 502-1 to associate a timestamp with the sensing measurement and then report the timestamped sensing measurement back to sensing transmitter 504-1. In a scenario where sensing receiver 502-1 is an OBSS STA and sensing transmitter 504-1 is an OBSS AP, the local clock of the sensing receiver (also referred to as an OBSS STA TSF timer, which is an example of TSF timer 523-1) may not be synchronized with the local clock of the sensing transmitter (also referred to as an OBSS AP TSF timer, which is an example of TSF timer 543-1). In addition, if there are more than one OBSS STA (e.g., sensing receiver 502-(1-M)) located in different BSSs, there may be more than one OBSS STA sensing receiver TSF timer (e.g., 523-(1-M)) that is not synchronized with the OBSS AP TSF timer 543-1 of the sensing transmitter 504-1.

[0206] Figure 8 An example 800 of a TSF timer out-of-sync situation according to some embodiments is depicted. The sensing receiver 502-1 as an OBSS STA Figure 8 802, and the sensing transmitter 504-1 as an OBSS AP is in Figure 8 It is depicted as 804. Figure 8 Described in Figure 8 The TSF timer 543-1 of OBSS AP 804 (sensing transmitter 504-1) and the TSF timer 543-1 of 806 are depicted as Fig. 9808 depicted as a non-associated OBSS STA 802 (sensing receiver 502-1) is not synchronized. In addition, when the OBSS STA 802 (sensing receiver 502-1) is required to receive a sensing transmission from the OBSS AP 804 (sensing transmitter 504-1), in some cases, the OBSS STA 802 (sensing receiver 502-1) may change channels to receive the sensing transmission. Since the OBSS STA 802 (sensing receiver 502-1) and the OBSS AP 804 (sensing transmitter 504-1) may not be synchronized, there may be certain errors in the timing of the channel change, the reception of the sensing transmission, and the channel change back (to the original channel). Therefore, a robust time synchronization mechanism between the OBSS STA (sensing receiver 502-1) and the OBSS AP (sensing transmitter 504-1) is required.

[0207] The present disclosure describes a solution for an OBSS STA (which is an example of a sensing receiver 502-1), where the OBSS STA is not associated with an OBSS AP (which is an example of a sensing transmitter 504-1), and therefore is not time synchronized with the OBSS AP, to create and maintain a local version of the OBSS AP's clock / timer (e.g., the TSF timer 543-1 of the sensing transmitter 504-1). The local version of the TSF timer 543-1 of the sensing transmitter 504-1 may be stored by the sensing receiver 502-1 in a sensing transmitter information storage device 521-1, which may be configured to store information related to the sensing transmitter 504-1. The local version of the TSF timer 543-1 may be referred to as the OBSS STA-AP TSF timer of the sensing transmitter 504-1. Maintaining the OBSS STA-AP TSF timer of the sensing transmitter 504-1 as the OBSS AP enables the sensing receiver 502-1 as the OBSS STA to participate as the sensing receiver 502-1 in a sensing session with the OBSS AP as the sensing transmitter 504-1. In the example, the OBSS STA (sensing receiver 502-1) performs sensing measurements on sensing transmissions from the OBSS AP (sensing transmitter 504-1) and applies a timestamp to the sensing measurements based on the OBSS STA-AP TSF timer of the sensing transmitter 504-1 instead of the TSF timer 523-1 of the OBSS STA as the sensing receiver 502-1. Therefore, the sensing measurements calculated by the OBSS STA (sensing receiver 502-1) have an accurate time reference relative to the OBSS AP (sensing transmitter 504-1).

[0208] For ease of explanation and understanding, the description provided below is made with reference to the first sensing receiver 502-1 and the first sensing transmitter 504-1, however, the description is also applicable to the remaining sensing receivers 502-(2-M) and the remaining sensing transmitters 504-(2-N).

[0209] According to the embodiment, the first sensing receiver 502-1 (which is an OBSS STA) can obtain timing information from an unassociated access point (sensing transmitter 504-1) that is not associated with the first sensing receiver 502-1 and acts as a sensing transmitter. In the example, the timing information can be an access point TSF timer of the unassociated access point, that is, the TSF timer 543-1 of the sensing transmitter 504-1. In addition, the timing information can be received in a beacon frame broadcast by the sensing transmitter 504-1. In the example, the sensing transmitter 504-1 can be referred to as an OBSS AP. In addition, the timing information can be a TSF timer 538-1 (also referred to as an OBSSAP TSF timer).

[0210] In some embodiments, the sensing agent 516-1 or the sensing algorithm 518-1 may determine a timer offset value based on a difference between the TSF timer 538-1 of the sensing transmitter 504-1 and the TSF timer 523-1 of the sensing receiver 502-1. The TSF timer 532-1 may also be referred to as the OBSS STA TSF timer of the first sensing receiver 502-1. In addition, the timestamp generation block 524-1 of the sensing receiver 502-1 may be configured to determine a timestamp by combining the TSF timer 523-1 with the timer offset value.

[0211] In an embodiment, the sensing agent 516-1 or the sensing algorithm 518-1 can generate local timing information based on the timing information. In an example, the local timing information can be a local version of the OBSS AP TSF timer 543-1. In some examples, the local timing information can be a timer offset value determined based on the difference between the timing information and the TSF timer 523-1. In an example, the timing information can be stored as local timing information. In an example, the local timing information associated with the TSF timer 543-1 of the sensing transmitter 504-1 can be stored in the sensing transmitter information storage device 521-1.

[0212] According to an embodiment, the first sensing transmitter 504-1 may broadcast a beacon frame, for example, once every 100ms. The format of the beacon frame is described in Section 9.3.3.2 of the draft P802.11REVmd_D5.0 - "Beacon frame format". In an example, the first information field of the beacon frame may be a timestamp field. The timestamp field may represent the TSF timer 543-1 of the sensing transmitter 504-1. In an embodiment, the first sensing receiver 502-1 may receive a beacon frame notified to the first sensing transmitter 504-1.

[0213] In some embodiments, the first sensing receiver 502-1 may obtain additional timing information (e.g., TSF timer 543-(2-N)) from multiple additional non-associated access points (e.g., from one or more of the remaining sensing transmitters 504-(2-N)) and generate additional local timing information based on the additional timing information. In an example, the sensing receiver may store the additional local timing information corresponding to the sensing transmitter 504-(2-N) in the sensing transmitter information storage device 521-(2-N). According to an embodiment, one or more of the remaining sensing transmitters 504-(2-N) may broadcast a beacon frame. In an embodiment, the first sensing receiver 502-1 may receive one or more beacon frames notified to one or more of the remaining sensing transmitters 504-(2-N). In an example, one or more beacon frames of one or more of the remaining sensing transmitters 504-(2-N) may include a full TSF timer 543-(2-N) (64 bits), which reflects the TSF timer of one or more of the remaining sensing transmitters 504-(2-N). In an embodiment, the first sensing receiver 502-1 may store the local timing information (corresponding to the TSF timer 543-(2-N)) received in one or more beacon frames of one or more remaining sensing transmitters 504-(2-N) in the sensing transmitter information storage device 521-(2-N). In some embodiments, the first sensing receiver 502-1 may calculate the timer offset value of one or more remaining sensing transmitters 504-(2-N) and store it in the sensing transmitter information storage device 521-(2-N).

[0214] In an example, the first sensing receiver 502-1 may store identifiers of one or more of the plurality of sensing transmitters 504-(1-N). An example of an identifier of the sensing transmitter 504-1 is a service set identifier or (SSID). In an embodiment, the first sensing receiver 502-1 may send a probe request. In an example, the probe request may include at least one identifier of one or more of the plurality of sensing transmitters 504-(1-N). In addition, the first sensing receiver 502-1 may receive a probe response. In an example, the probe response may include at least one response from one or more of the plurality of sensing transmitters 504-(1-N) associated with at least one identifier. In an example, the probe response from the sensing transmitter 504-1 may include a TSF timer 543-1 of the sensing transmitter 504-1, wherein the probe response is a transmitter from the sensing transmitter 504-1 to the sensing receiver 502-1 in response to receiving a probe request including an identifier of the sensing transmitter 504-1 from the sensing receiver 502-1.

[0215] In some examples, the probe request may contain an access point identification wildcard (eg, a service set identifier (SSID) wildcard), in which case any sensing transmitter 504-(1-N) may respond with a probe response.

[0216] In an embodiment, the first sensing receiver 502-1 may store the local timing information received in the probe response associated with the TSF timer 543-(1-N) of one or more of the plurality of sensing transmitters 504-(1-N) in the sensing transmitter information storage 521-(1-N). In some embodiments, the first sensing receiver 502-1 may calculate the timer offset value of one or more of the plurality of sensing transmitters 504-(1-N) and store it in the sensing transmitter information storage 521-(1-N).

[0217] According to an embodiment, the first sensing receiver 502-1 completes the process of initial synchronization with the first sensing transmitter 504-1 by generating and storing local timing information associated with the first sensing transmitter 504-1 (i.e., a local version of the TSF timer 543-1 (OBSS STA-AP TSF timer)) or by calculating a timer offset value for the first sensing transmitter 504-1. According to an embodiment, the first sensing receiver 502-1 may increment the local timing information based on a local clock (e.g., a crystal oscillator or a voltage-controlled oscillator (VCO)). In an example, the first sensing receiver 502-1 may increment the TSF timer 523-1 and the local timing information associated with one or more of the plurality of sensing transmitters 504-(1-N) based on its VCO.

[0218] In an embodiment, the first sensing receiver 502-1 may set a synchronization flag associated with the first sensing transmitter 504-1 to indicate that the first sensing receiver 502-1 has valid local timing information or a valid timer offset value associated with the first sensing transmitter 504-1. In an example, when the first sensing receiver 502-1 sends a first SENS-CTS to a self frame, the first sensing transmitter 504-1 may set a synchronization flag associated with the first sensing receiver 502-1, the synchronization flag indicating in an example that the first sensing receiver 502-1 has valid local timing information or a valid timer offset value associated with the first sensing transmitter 504-1. In some examples, when the first sensing receiver 502-1 sends a first sensing measurement report with an associated timestamp, the first sensing transmitter 504-1 may set a synchronization flag associated with the first sensing receiver 502-1, the synchronization flag indicating in an example that the first sensing receiver 502-1 has valid local timing information or a valid timer offset value associated with the first sensing transmitter 504-1. In an example, after setting the synchronization flag associated with the first sensing receiver 502-1, the sensing transmitter 504-1 may start a resynchronization timer 546-1 associated with the first sensing receiver 502-1. In an example, the resynchronization timer 546-1 associated with the first sensing receiver 502-1 may indicate to the first sensing transmitter 504-1 when a resynchronization task of the first sensing receiver 502-1 is required. The resynchronization task of the first sensing receiver 502-1 may involve sending a portion or all of the TSF timer 543-1 to the sensing receiver 502-1.

[0219] According to an embodiment, after completing the process of initial synchronization with the first sensing transmitter 504-1, the first sensing receiver 502-1 can start a resynchronization timer 526-1 associated with the local timing information or timer offset of the first sensing transmitter 504-1. In an example, the resynchronization timer 526-1 associated with the local timing information or timer offset of the first sensing transmitter 504-1 can indicate to the first sensing receiver 502-1 when the resynchronization task of the first sensing transmitter 504-1 should run. The resynchronization task is a process of updating the local timing information of the sensing transmitter 504-1 with information associated with the TSF timer 543-1 of the sensing transmitter 504-1.

[0220] According to an embodiment, after completing the process of initial synchronization with the first sensing transmitter 504-1, and considering the scenario that the first sensing receiver 502-1 is not associated with any other sensing transmitter 502-(2-N), the first sensing receiver 502-1 can tune the first sensing receiver 502-1 to the channel where the beacon frame is received from the sensing transmitter 502-1 for further communication from the first sensing transmitter 504-1 (e.g., pre-association security negotiation (PASN) or sensing measurement exchange). The sensing receiver 502-1 can use local timing information associated with the sensing transmitter 504-1 to determine when to power on the receiver circuit of the sensing receiver 502-1 and receive transmissions from the sensing transmitter 504-1, for example, to minimize unnecessary time spent on powering up the receiver circuit, which may, for example, consume battery power.

[0221] In some scenarios, the first sensing receiver 502-1 may be associated with a second sensing transmitter 504-2, which operates on the same channel on which the beacon frame is received from the first sensing transmitter 504-1. In an example, the sensing transmitter 504-2 may be any device other than the first sensing transmitter 504-1 (i.e., a sensing transmitter among the remaining sensing transmitters 504-(2-N), examples of which are the second sensing transmitter 504-2 or the third sensing transmitter 504-3, etc.). In addition, in some scenarios, the first sensing receiver 502-1 may be associated with one of the plurality of sensing transmitters 504-(1-N), which operates on a channel different from the channel on which the beacon frame is received from the first sensing transmitter 504-1.

[0222] Fig. 9 An example 900 of communication on the same channel between an example STA 910 as a sensing receiver 502-1, an associated access point 908 (sensing transmitter 504-2) of a BSS 904, and an unassociated access point 906 (sensing transmitter 504-1) of the BSS 902 is depicted in accordance with some embodiments. In the example, the STA 910 and the unassociated access point 906 may be located in different BSSs, and the STA 910 and the associated access point 908 may be located in the same BSS. In the example, the STA 910 may be a first sensing receiver 502-1, the unassociated access point may be a first sensing transmitter 504-1, and the associated access point may be a second sensing transmitter 504-2. The STA 910 may be referred to hereinafter as an OBSS STA, the unassociated access point 906 may be referred to hereinafter as OBSS AP1, and the associated access point 908 may be referred to hereinafter as BSS AP2. Fig. 9As described in , there are two BSSs, namely, a first BSS 902 and a second BSS 904. The first BSS 902 includes an OBSS AP1 906, and the second BSS 904 includes a BSS AP2 908 and an OBSS STA 910. In addition, the OBSS AP1 906 and the OBSS STA 910 may participate in a sensing measurement exchange 912 (also referred to as an OBSS sensing measurement exchange). And, a communication link 914 (also referred to as an associated communication channel) may be established between the BSS AP2 908 and the OBSS STA 910. In an embodiment, the communication between the OBSS AP1 906 and the OBSS STA 910 and the communication between the BSS AP2 908 and the OBSS STA 910 may occur on a frequency channel "f1", and there may be a coverage overlap area 916 between the OBSS AP1 906 and the OBSS STA 910. In an example, the channel of BSS AP2908 is the same as the channel of the beacon frame of OBSS AP1 906. According to an embodiment, OBSS STA 910 may receive the beacon frame of OBSS AP1 906 on the same channel (e.g., "f1") as the beacon frame of BSS AP2908, and may remain tuned to the channel for further communication (e.g., PASN or sensing measurement exchange) from OBSS AP1 906. In some embodiments, communication between OBSS AP1 906 and OBSS STA 910 may occur on the frequency channel "f1", and communication between BSS AP2908 and OBSS STA 910 may occur on a different frequency channel (e.g., "f2"). In an example, the channel of BSS AP2908 may be different from the channel of the beacon frame of OBSS AP1 906.

[0223] According to an embodiment, in order for the OBSS STA 910 to receive the beacon frame of the OBSS AP1 906 on the channel of the OBSS AP1 906 and remain tuned to the channel of the OBSS AP1 906 for further communication (e.g., PASN or sensing measurement exchange), the OBSS STA 910 may periodically move to an idle state. In an example, the OBSS STA 910 may indicate to the BSS AP2 908 that the OBSS STA is entering a sleep mode, and the BSS AP2 908 may temporarily initiate buffering of communication data for the OBSS STA 910 from the BSS AP2 908. In addition, in an example, when the OBSS STA 910 tunes back to the communication channel associated with the BSS AP2 908, the OBSS STA 910 may buffer communication data for transmission to the BSS AP2 908.

[0224] In an example, a mechanism that enables the OBSS STA 910 to periodically move to an idle state may be provided at the application layer. In addition, in an example, a mechanism that enables the OBSS STA 910 to periodically move to an idle state may be provided at the MAC layer. In an example, the associated station management entity (SME) of BSS AP2 908 may send the mechanism to the OBSS STA 910 in advance, such as at the time of association. In an example, the OBSS STA 910 may periodically move to an idle state using the same or similar mechanism already specified in the IEEE 802.11 standard to provide the same or similar functionality. In an embodiment, when OBSS AP1 906 is in an idle state, the OBSS STA 910 may scan for a beacon frame of OBSS AP1 906 and then tune to a channel of the beacon frame of OBSS AP1 906.

[0225] For ease of explanation and understanding, the description provided is in the context of the first sensing transmitter 504-1 and the first sensing receiver 502-1, however, without loss of generality, the first sensing receiver 502-1 may interact with the remaining sensing transmitters 504-(2-N) (e.g., with the second sensing transmitter 504-2, the third sensing transmitter 504-3, etc.). In an example, the first sensing transmitter 504-1 may interact with the remaining sensing receivers 502-(2-M) (e.g., with the second sensing receiver 502-2, the third sensing receiver 502-3, etc.). According to some embodiments, one or more channels of the plurality of sensing receivers 502-(1-M) may be different from the channel of the beacon frame of the OBSS AP1 906. In an example, the remaining sensing receivers 502-(2-M) may also interact with the first sensing transmitter 504-1.

[0226] Return to reference Figure 5, in an embodiment, the first sensing receiver 502-1 may send an idle message to an associated access point, which may be a second sensing transmitter 504-2. In addition, the first sensing receiver 502-1 may tune the first sensing receiver 502-1 to a channel, for example, from which a beacon frame is received from the first non-associated access point 504-1. In an embodiment, the first sensing receiver 502-1 may receive a sensing transmission from the first sensing transmitter 504-1. In addition, the first sensing receiver 502-1 may perform sensing measurements on the sensing transmission. In an embodiment, the first sensing receiver 502-1 may associate the sensing measurement with a timestamp (which is the same timestamp generated by the timestamp generation block 524-1) based on local timing information associated with the sensing transmitter 504-1, which may be retrieved, for example, from the sensing transmitter information storage device 521-(1-N). Then, the first sensing receiver 502-1 may send the sensing measurement and the timestamp to the first sensing transmitter 504-1. In an embodiment, the first sensing receiver 502-1 may send the sensing measurements in response to receiving a sensing report trigger from the first sensing transmitter 504-1.

[0227] In an example, when the resynchronization timer 526-1 associated with the first sensing transmitter 504-1 expires, the sensing agent 516-1 or the sensing algorithm 518-1 can clear the synchronization flag associated with the first sensing transmitter 504-1. In some embodiments, after the resynchronization timer 526-1 associated with the first sensing transmitter 504-1 expires, or when the synchronization flag associated with the first sensing transmitter 504-1 is cleared, the first sensing receiver 502-1 can resynchronize the local timing information associated with the sensing transmitter 504-1. In a manner similar to that described above, the first sensing receiver 502-1 can obtain the second timing information from the first sensing transmitter 504-1. In an example, the time interval of the resynchronization timer 526-1 can be determined based on the measurement of the timing drift between the TSF timer 523-1 of the first sensing receiver 502-1 and the TSF timer 543-1 of the first sensing transmitter 504-1.

[0228] According to an embodiment, prior to receiving the sensing transmission, the first sensing receiver 502-1 may initiate a PASN procedure with the first sensing transmitter 504-1. In an example, this establishes the security keys required for the first sensing receiver 502-1 to receive and decode messages in the sensing measurement exchange and for the first sensing receiver 502-1 to encode and send messages in the sensing measurement exchange. The PASN procedure is explained in Section 12.12 of the draft P802.11az_D4.1. In an embodiment, the first sensing transmitter 504-1 may indicate that the first sensing transmitter is capable of performing PASN authentication by including an indication in a beacon frame or a probe response (which are the same beacon frames and probe responses from which the first sensing receiver 502-1 obtains the TSF timer 543-1 of the sensing transmitter 504-1).

[0229] In some embodiments, if there is no subsequent sensing measurement exchange, a beacon frame or a probe response may be sent without a PASN process. In an example, the beacon frame or the probe response may be part of a PASN process, and the PASN process may complete authentication and negotiate security keys, which allows the first sensing receiver 502-1 to decode the NDPA frame from the first sensing transmitter 504-1. In an example, after the first sensing receiver 502-1 obtains the TSF timer 543-1 from the beacon frame or the probe response from the sensing transmitter 504-1, the first sensing receiver 502-1 may initiate and complete the PASN process. Once the PASN process is completed, the first sensing receiver 502-1 and the first sensing transmitter 504-1 may participate in the sensing measurement exchange.

[0230] Fig. 10A and Fig. 10B Depicted is a trigger-based measurement example 1000 of a Wi-Fi sensing process in accordance with some embodiments. Fig. 10A and Fig. 10B It is on the draft P802.11bf_D0.01 Figure 6 -28a reappearance. Fig. 10A and Fig. 10B, the sensing receiver 1002 and the sensing transmitter 1004 may perform a sensing measurement exchange. At step 1006 of process 1000, in some embodiments, the SME of the sensing receiver 1002 may send a MLME-SENSMSMTSETUP.request primitive to the MLME of the sensing receiver 1002. At step 1008 of process 1000, in some embodiments, the MLME of the sensing receiver 1002 may send a SENS measurement setup request frame to the MLME of the sensing transmitter 1004. At step 1010 of process 1000, in some embodiments, the MLME of the sensing transmitter 1004 may send a MLME-SENSMSTSETUP.indication primitive to the SME of the sensing transmitter 1004. At step 1012 of process 1000, in some embodiments, the SME of the sensing transmitter 1004 may send a MLME-SENSMSTSETUP.response primitive to the MLME of the sensing transmitter 1004. At step 1014 of process 1000, in some embodiments, the MLME of the sensing transmitter 1004 may send a SENS measurement setup response frame to the MLME of the sensing receiver 1002. At step 1016 of process 1000, in some embodiments, the MLME of the sensing receiver 1002 may send a MLME-SENSMSTSETUP.confirm primitive to the SME of the sensing receiver 1002. At step 1018 of process 1000, in some embodiments, the SME of the sensing receiver 1002 may send a MLME-SENSTBMSMTRQ.request primitive to the MLME of the sensing receiver 1002. At step 1020 of process 1000, in some embodiments, the MLME of the sensing receiver 1002 may send a SENS poll frame to the MLME of the sensing transmitter 1004. At step 1022 of process 1000, in some embodiments, the MLME of the sensing transmitter 1004 may send a SENS CTS-to-self to the MLME of the sensing transmitter 1004. At step 1024 of process 1000, in some embodiments, the MLME of the sensing receiver 1002 may send a SENS NDPA frame to the MLME of the sensing transmitter 1004. At step 1026 of process 1000, in some embodiments, the MLME of the sensing receiver 1002 may send a SENSNDP to the MLME of the sensing transmitter 1004. At step 1028 of process 1000, in some embodiments, the MLME of the sensing transmitter 1004 may send a MLME-SENSTBREPORT.indication primitive to the SME of the sensing transmitter 1004.At step 1030 of process 1000, in some embodiments, the SME of the sensing transmitter 1004 may send a MLME-SENSTBREPORTRQ.request primitive to the MLME of the sensing transmitter 1004. At step 1032 of process 1000, in some embodiments, the MLME of the sensing receiver 1002 may send a SENS report trigger frame to the MLME of the sensing transmitter 1004. At step 1034 of process 1000, in some embodiments, the MLME of the sensing transmitter 1004 may send a sensing measurement report frame to the MLME of the sensing receiver 1002. At step 1036 of process 1000, in some embodiments, the MLME of the sensing receiver 1002 may send a MLME-SENSTBMSMTRQ.confirm primitive to the SME of the sensing receiver 1002. At step 1038 of process 1000, in some embodiments, the MLME of the sensing transmitter 1004 may send a MLME-SENSTBREPORTRQ.confirm primitive to the SME of the sensing transmitter 1004. Fig. 10A and Fig. 10B In , the sensing measurement exchanges are numbered 1 to 6.

[0231] Examples of time synchronization of sensing measurements outside the BSS are described in detail below.

[0232] Fig.11 An example 1100 of a trigger-based OBSS sensing measurement exchange according to some embodiments is depicted. In an example, an OBSS STA may be a sensing receiver (e.g., a first sensing receiver 502-1), and an OBSS AP may be a sensing transmitter (e.g., a first sensing transmitter 504-1). In an example, the OBSS STA may perform sensing measurements on sensing transmissions from the OBSS AP. In addition, the OBSS STA may timestamp the sensing measurements with local timing information associated with the OBSS AP (also referred to as a local version of the OBSS APTSF timer (OBSS STA-AP TSF timer)) or with an adjusted OBSS STA TSF timer. The OBSS STA may then send a sensing measurement report including the sensing measurements and the timestamp to the OBSS AP.

[0233] In an example, a new trigger frame type is defined, which may be called as Fig.11The SENS polling shown. In an example, the SENS polling can enable the OBSS AP to determine which OBSS STAs will participate in the OBSS sensing measurement exchange. In an example, the SENS polling trigger frame can reuse aspects of the ranging trigger frame (polling). In an example, the SENS polling trigger frame is defined by a new trigger type subfield value, which can use one of the reserved trigger type subfield values ​​(i.e., a new trigger type subfield value is defined). In an example, any trigger type subfield value that has not been used for trigger frame variants can be used. In an example, the trigger type subfield value of the SENS polling trigger frame is type 9, as shown in Table 1 below.

[0234] Table 1: New Trigger Type Subfield of Common Information Field (Trigger Frame)

[0235]

[0236]

[0237] In an example, in a SENS-poll trigger frame, the OBSS AP may include a ranging session identifier (RSID) assigned to address each OBSS STA that the OBSS AP may need to participate in a sensing session. In an example, the OBSS AP may address one or more OBSS STAs that have successfully completed the PASN procedure. In an example, the OBSS AP may assign a resource unit (RU) allocation to each addressed OBSS STA in the SENS-poll trigger frame.

[0238] In an example, an OBSS STA may have an availability window for receiving a SENS poll trigger frame from an OBSS AP. In an example, an RSID may be assigned to an OBSS STA, and if the OBSS STA chooses to participate in a sensing measurement exchange, the OBSS STA may respond to the SENS poll trigger frame. In an example, in response to the SENS poll trigger frame, the OBSS STA may respond to the OBSS AP with a CTS to self frame. In an example, in the sensing measurement exchange polling phase, the response from the OBSS STA to the OBSS AP may be referred to as a SENS CTS to self frame. In an example, the OBSS STA may send a SENS CTS to self frame in the RU allocation provided to the OBSS STA by the OBSS AP in the SENS poll trigger frame. In an example, the OBSS STA may report its MAC address to the OBSS AP (e.g., as described in the ranging polling phase in the draft P802.11az_D4.1). In an example, the OBSS AP may create an RSID-MAC element that may be used to identify the OBSS STA.

[0239] In addition, in an example, the OBSS AP may send a SENS NDPA frame to inform the OBSS STA that a SENS NDP will follow, and the OBSS STA may perform sensing measurements on the SENS NDP. In an example, the SENS NDPA frame may be unicast or broadcast. In an example, the OBSS AP may send a SENS NDP frame to all OBSS STAs that respond to the SENS polling trigger frame. In addition, the OBSS STA may perform sensing measurements on the SENS NDP. In an example, the SENS NDPA frame and / or the SENS NDP frame may be sent in the same channel as the SENS polling trigger frame. In an example, the SENS NDPA frame and / or the SENS NDP frame may be sent in a different channel, which may have been selected by the OBSS AP and the OBSS STA, for example, during the polling phase. In an example, the SENS NDP may have the same or similar structure as the ranging NDP. The OBSS STA may perform sensing measurements on the SENS NDP, and may associate a timestamp with the sensing measurement, wherein the timestamp is based on the OBSS STA-APTSF timer or the adjusted OBSS STA TSF timer. In an example, an OBSS AP may send more than one SENS NDPA / SENS NDP frame combination to an OBSS STA. The OBSS STA may make a sensing measurement for each SENS NDP it receives and associate a timestamp with each sensing measurement.

[0240] In an example, an OBSS AP may send a sensing report trigger frame to an OBSS STA. In response to receiving the sensing report trigger frame, the OBSS STA may send a sensing measurement report frame to the OBSS AP, wherein the sensing measurement report frame includes one or more sensing measurements and their associated timestamps. In an example, the timestamp included in the sensing measurement may be 64 bits or 8 octets long. The sensing measurement report frame may be defined as a management frame or a data frame. In an example, the sensing measurement report frame may be transmitted from the OBSS STA to the OBSS AP using any valid data transmission TXOP. In an example, the sensing measurement report frame may include a truncated timestamp less than 64 bits. In an example, one or more of the least significant bits (LSBs) of the 64-bit timestamp may be truncated. In some examples, one or more of the most significant bits (MSBs) of the 64-bit timestamp may be truncated. In an example, the timestamp may include 8 LSBs, 16 LSBs, 24 LSBs, 32 LSBs, 40 LSBs, 48 ​​LSBs, or 56 LSBs. In Fig.11In the present invention, the sensing measurement report can be defined similarly to the I2R LMR feedback (eg, OBSS STA to OBSS AP location measurement report feedback, as described in draft P802.11az_D4.1).

[0241] Fig.12 A format 1200 of a sensing measurement report frame is depicted according to some embodiments. Fig.12 It is draft P802.11az_D4.1 Figure 9-9 An Immediate Measurement subfield may be defined which may be similar to the Immediate I2R Feedback subfield and which indicates that the sensing measurement results from the current sensing measurement exchange may be reported immediately by setting it to 1 (according to the current sensing measurement) or delayed by setting it to 0 (according to the previous sensing measurement) (as described in draft P802.11az_D4.1).

[0242] Reference Fig.11 In an example, the time offset between the OBSS AP TSF timer (eg, TSF timer 543-1) and the OBSS STATSF timer (eg, TSF timer 523-1) is Fig.11 , which is shown as a Δ clock. Both the OBSS AP TSF timer and the OBSS STA TSF timer may increment per system timing unit (abbreviated as TU), however, the clock at the OBSS AP and the clock at the OBSS STA may have different clock drifts (within an allowable tolerance), so that the TU used for the OBSS AP TSF timer and the TU used for the OBSS STA TSF timer may be slightly different, thereby causing a drift between the OBSS APTSF timer and the OBSS STA TSF timer. In an example, when the OBSS STA receives a beacon frame or a probe response containing a complete OBSS AP TSF timer from the OBSS AP, the OBSS STA may set its local timing information (a local version of the OBSSAP TSF timer (OBSS STA-AP TSF timer)) to the received OBSS AP TSF timer, or may calculate a timer offset value as the difference between the OBSS AP TSF timer and the OBSS STA TSF timer. In an example, the received OBSS AP TSF timer 543-1 may contain a complete 8-octet TSF value.

[0243] In the example, it is assumed that when a beacon frame (or a probe response) is broadcast, T0 is the OBSS AP TSF timer, and when a beacon frame (or a probe response) is received at the OBSS STA from the OBSS AP, T0' is the OBSS STA TSF timer. In the example, the timer offset (T offset ) may be defined as the difference between the OBSS AP TSF timer received in a beacon frame or a probe response and the OBSS STA TSF timer when the OBSS STA receives the beacon frame or the probe response. In the example, let T flight represents the flight time, i.e., the transmission time from the OBSS AP to the OBSS STA, and let T proc Indicates the OBSS STA processing time, that is, the time between the time when the OBSS STA receives the signal and the time when the OBSS STA processes the signal of a frame. The timer offset (T offset ) can be expressed mathematically as:

[0244] Time offset = T0′-T0 = Δ clock + T flight +T proc …(8)

[0245] In an example, the sensing measurements may be time stamped with an adjusted OBSS STA TSF timer calculated as follows:

[0246] Adjusted OBSS STA TSF timer = OBSS STA TSF timer - time offset (9)

[0247] In an example, the timer offset value may be stored at the OBSS STA. In an example, the size of the timer offset may vary up to 64 bits (which is the size of the TSF timer 543-1). In an example, the timer offset may be stored as an 8-bit value, a 16-bit value, a 24-bit value, a 32-bit value, a 40-bit value, a 48-bit value, or a 56-bit value.

[0248] In an example, local timing information (a local version of the OBSS AP TSF timer (OBSS STA-AP TSF timer)) can be stored at the OBSS STA. In an example, Tables 2 and 3 provided below show two methods of representing the OBSS STA-AP TSF timer in 64 bits. Table 2 divides the lower two octets into three parts, namely, bits 0 to 5, bits 6 to 21, and bits 22 to 31. The partial TSF using bits 6 to 21 (symbolized as [21:6]) is standardized in IEEE 802.11 as a partial TSF field. For ease of representation, the local timing information (also referred to as the OBSS STA-AP TSF timer) is abbreviated as OSA-TSF in Tables 2 and 3.

[0249] Table 2: Initial OBSS STA-AP TSF timer via beacon frame

[0250]

[0251] Table 3: Initial OBSS STA-AP TSF timer via beacon frame

[0252]

[0253] In an example, the sensing measurements may be time stamped with local timing information (also referred to as an OBSS STA-AP TSF timer). The OBSS STA-AP TSF timer may be incremented in the same manner as the OBSS STA TSF timer (523-1) is incremented.

[0254] In an embodiment, more than one OBSS STA may maintain an OBSS STA-AP TSF timer or timer offset, and may timestamp corresponding sensing measurements of the more than one OBSS STA with the local timing information (OBSS STA-AP TSF timer) or the adjusted OBSS STA TSF timer (which is a combination of the timer offset value and the TSF timer 523-1) of the more than one OBSS STA. In an example, the OBSS STA-AP TSF timer or the adjusted OBSS STA TSF timer maintained by all OBSS STAs may be the same within a certain tolerance, which allows the OBSS AP to combine sensing measurements from multiple OBSS STAs. In an example, after the OBSS STA-AP TSF timer is initially synchronized with the OBSS AP TSF timer through a beacon frame (or a probe response), or after the timer offset value is initially calculated, the OBSS STA-AP TSF timer or the adjusted OBSS STA TSF timer may have a time drift due to differences between the OBSS AP oscillator and the OBSS STA oscillator. In an example, this may make the timestamp associated with the sensing measurement inaccurate. In an example, the time drift of the STA oscillator may be about + / -100 parts per million (ppm), or + / -100 ppm, and the time drift of the AP oscillator may also be about + / -100 ppm. In an example, due to the time drift, the OBS STA-AP TSF timer may need to be periodically resynchronized with the OBSS AP TSF timer. In some examples, the timer offset value needs to be recalculated.

[0255] In an example, resynchronization of the OBSS STA-AP TSF timer with the OBSS AP TSF timer may be achieved using a SENS NDPA frame containing a Partial TSF subfield in the STA Information field. In an example, the Partial TSF is a 16-bit field that appears after the AID11 field in the SENS NDPA frame. Fig.13 An example 1300 showing the SENS NDPA STA information field of a partial TSF is depicted in FIG.

[0256] In an example, a STA information field with the AID11 subfield set equal to 2044 is present in a SENS NDPA frame carrying a partial TSF subfield. In an example, the partial TSF subfield contains 16 bits of the OBSS AP TSF timer 543-1. In an example, the partial TSF carries bits [21:6] of the OBSS AP TSF timer 543-1. The other 16-bit range of the OBSS AP TSF timer can be carried in the SENS NDPA. In an example, if there is no time drift between the AP oscillator and the STA oscillator, the partial TSF should be equal to the same bit range of the local timing information (i.e., the OBSS STA-AP TSF timer), but as previously described, both the OBSS AP oscillator and the OBSS STA oscillator may drift relative to each other. In an example, when the OBSS AP determines that a resynchronization task for one or more OBSS STAs should be run, the OBSS AP can send a SENS NDPA with a STA information field, wherein the STA information field contains a partial TSF subfield. In an example, when the OBSS AP determines that a resynchronization task for one or more OBSS STAs should be run, the OBSS AP may send a SENS NDPA with a partial TSF subfield containing 16 bits of a full OBSS AP TSF timer. In an example, a bit window of the partial TSF field of the OBSS AP TSF timer sent in the SENS NDPA may be preconfigured. In an example, the length of the bit window of the partial TSF field of the OBSSAP TSF timer sent in the SENS NDPA may be greater than 16 bits. In some examples, the bit window of the partial TSF field of the OBSSAP TSF timer sent in the SENS NDPA may extract different portions of the 64 bits of the OBSS AP TSF timer. In an example, the partial TSF field may represent a windowed version of the OBSS AP TSF timer.

[0257] In an example, a windowed version of the OBSS AP TSF timer sent in the partial TSF field may overwrite an equivalent portion of the OBSS STA-AP TSF timer (e.g., partial TSF[21:6] overwrites OBSS STA-AP TSF timer[21:6]), thereby resynchronizing local timing information. In an example, the windowed bit range of the OBSS AP TSF timer captured in the partial TSF may be used to determine the maximum accuracy of time synchronization between the OBSS STA-AP TSF timer and the OBSS AP TSF timer and the minimum resynchronization time.

[0258] In an example, when the partial TSF field includes bits [21:6], the partial TSF field is used to update the timer offset at the OBSS STA. In an example, the timer offset may be updated based on equation (10) provided below.

[0259] Time offset (recalculated) = time offset + F adjusted OBSS STA TSF timer [21:6] - partial TSF [21:6] M ... (10)

[0260] In an example, if a resynchronization timer (e.g., a resynchronization timer 546-1 associated with an OBSS STA, which in the example is the sensing receiver 502-1) reaches a certain value (if the resynchronization timer 546-1 for the OBSS STA counts up from zero) or reaches zero (if the resynchronization timer 546-1 for the OBSS STA counts down from a certain value), the OBSS AP may determine that a resynchronization task of the OBSS STA should be run. In an example, if the resynchronization timer 526-1 for the OBSS AP in the OBSS STA expires, the OBSS STA does not send any sensing measurement report frames to the OBSS AP until the OBSS STA is able to resynchronize the OBSS STA-AP TSF timer or recalculate the timer offset value, for example, until the OBSS STA receives a SENS NDPA from the OBSS AP, wherein the SENS NDPA includes a partial TSF field.

[0261] In an example, when a resynchronization timer for an OBSS AP in an OBSS STA expires, the OBSS STA may clear a synchronization flag of the OBSS AP. In an example, when the synchronization flag is not set, that is, when the synchronization flag is cleared, the OBSS STA may not send any sensing measurement report frame to the OBSS AP. In an example, when the OBSS STA resynchronizes the OBSSSTA-AP TSF timer or recalculates the timer offset value (for example, when the OBSS STA receives a SENS NDPA from the OBSS AP, where the SENS NDPA includes a partial TSF field), the OBSS STA may set the synchronization flag of the OBSS AP.

[0262] In an example, when the resynchronization timer for the OBSS AP in the OBSS STA is running (indicating that the OBSS STA is synchronized with the OBSS AP), or when the synchronization flag of the OBSS AP is set, any scheduled event related to the OBSS AP (e.g., channel change) uses the local timing information of the OBSS AP (i.e., the OBSS STA-AP TSF timer or the adjusted OBSS STA TSF timer of the OBSS AP) as a time reference. As described above, a portion of the OBSS AP TSF timer at T1 may be sent from the OBSS AP to the OBSS STA in a SENS NDPA frame using a partial TSF. In an example, 16 bits [21:6] of the OBSS AP TSF timer at T1 may be sent to the OBSS STA in a SENS NDPA frame with a partial TSF field. This Fig.14 Shown in. Fig.14 Depicted is an example 1400 of a SENS NDPA STA Information field with a partial TSF in a Sensing Measurement Exchange in accordance with some embodiments.

[0263] In an example, the maximum time period between resynchronization events is calculated by the OBSS AP based on the OBSS STA TSF timer drift, which may be bounded by the desired accuracy of the OBSS STA's clock reference. In an example, the OBSS AP and OBSS STA clock references (and therefore TSF timer values) may drift by approximately + / - 100 ppm. In an example, the OBSS STA may calculate the maximum time period between resynchronization events by calculating the timer offset (T offset ) to measure TSF timer drift (TSF drift ), the two different beacon frames are, for example, at T0 and T1 (generating T offset 0 and T offset 1) This is Fig.15 Shown in. Fig.15 An example 1500 of trigger-based OBSS sensing measurement exchange according to some embodiments is depicted. In the example, the TSF timer drift (TSF drift ) can be determined as follows:

[0264] T0'-T0=T offset 0…(11)

[0265] T1'-T1=T offset 1…(12)

[0266] TSF drift =T offset 1-T offset 0…(13)

[0267] In the example, the drift rate can be calculated as follows:

[0268]

[0269] In the example, when TSF drift When a specified threshold is exceeded, the synchronization time may expire.

[0270] In an example, the OBSS AP may include a partial TSF field in each SENS NDPA frame. In an example, the OBSS STA may determine when to apply the partial TSF field received from the OBSS AP in the SENS NDPA frame to the OBSS STA-AP TSF timer for the OBSS AP, or recalculate the timer offset value of the OBSS AP, for example, depending on the TSF drift , such as calculated above, or depending on the expiration of a resynchronization timer of the OBSS AP.

[0271] In an example, the window applied to the TSF timer to derive the partial TSF may be adjusted to allow for a higher or lower precision in updating the OBSS STA-AP TSF timer or timer offset value, as shown in Table 4 provided below. The higher the precision, the more frequently the resynchronization algorithm may need to be run. The resynchronization algorithm may be dynamically adjusted based on, for example, a measure of channel occupancy of the system 500.

[0272] Table 4: Different positions of some TSF (16 bits)

[0273]

[0274]

[0275] Reference again Fig.14 , the partial TSF of NDPA is 16 bits [21:6], therefore, the wraparound time can be about 4.19s, and the time unit is 2 Z μs=64 μs, and the precision of (T1'-T1)[21:6] is also about 64 μs. In an example, the resolution of the OBSS STA-AP TSF timer or the timer offset value may not be greater than the resolution of the partial TSF field. For example, if the partial TSF field includes bits [21:6] of the OBSS AP TSF timer, the resolution of the OBSS STA-AP TSF timer or the timer offset value may not exceed 64 μs.

[0276] The time period t for resynchronization of the OBSS STA-AP TSF timer or timer offset value (given a maximum clock drift x) may be defined as follows:

[0277] x*t<=64μs…(15)

[0278] t<=64μs / x…(16)

[0279] In the example, the maximum x is about + / -100 μs / s, so the resynchronization period is defined as:

[0280] t<=64μs / (100μs / s)=0.64s…(17)

[0281] The resynchronization period x should be less than 0.64s, which is determined by the bit position of the partial TSF of the SENS NPDA frame. The partial TSF is an optional element / field of the SENS NDPA, so if the OBSS AP addresses the OBSS STA in a separate STA information field, the OBSS STA can still use SENS NDPA without the partial TSF field in the sensing measurement exchange.

[0282] In some examples, the SENS NDPA partial TSF can be used to resynchronize the full OBSS STA-AP TSF timer. Fig.16 Shown in. Fig.16 Depicted is an example 1600 of full TSF timer synchronization using partial TSF fields in accordance with some embodiments.

[0283] In an example, for the first four SENS NDPA frames, the position of the partial TSF of the SENS NDPA can be configured from the upper 16 bits [63:48] to the lower 16 bits [15:0]. In an example, the first four NDPA frames can be used to resynchronize the full OBSS STA-AP TSF timer by replacing each 16-bit segment of the OBSS STA-AP TSF timer with 16 bits in the partial TSF of each of the four subsequent SENS NDPA frames. According to the beacon frame, the OBSS STA-AP TSF timer can be as shown in Table 5 provided below. For ease of representation, the OBSS STA-AP TSF timer is abbreviated as OSA-TSF in Table 5.

[0284] Table 5: Initial OBSS STA-AP TSF timer via beacon frame

[0285]

[0286] After the first SENS NDPA frame with partial TSF[63:48], the most significant 16 bits of the OBSS STA-AP TSF timer may be resynchronized as shown in Table 6 provided below. For ease of presentation, the OBSS STA-AP TSF timer is abbreviated as OSA-TSF in Table 6.

[0287] Table 6: OBSS STA-AP TSF timer after the first SENS NDPA frame

[0288]

[0289] After the second SENS NDPA frame with partial TSF[47:32], the next most significant 16 bits[47:32] of the OBSS STA-AP TSF timer are resynchronized as shown in Table 7 below. For ease of presentation, the OBSS STA-AP TSF timer is abbreviated as OSA-TSF in Table 7.

[0290] Table 7: OBSS STA-AP TSF timer after the second SENS NDPA frame

[0291]

[0292] After the third SENS NDPA frame with partial TSF[31:16], the next most significant 16 bits[31:16] of the OBSS STA-AP TSF timer are resynchronized as shown in Table 8 below.

[0293] Table 8: Time offset of the third SENS NDPA frame

[0294]

[0295] After the fourth SENS NDPA frame with partial TSF[15:0], the LSB[15:0] of the OBSS STA-AP TSF timer is resynchronized as shown in Table 9 below.

[0296] Table 9: Time offset of the fourth SENS NDPA frame

[0297]

[0298] After resynchronizing using the first four SENS NDPA frames with partial TSF described above, the OBSS STA can perform sensing measurements on the NDP that arrives after the fourth SENS NDPA, because the OBSS STA-AP TSF timer is fully resynchronized at this time. In the example, sensing measurements can be performed on the NDP after the fifth SENS NDPA frame with an updated OBSS STA-AP TSF timer.

[0299] Fig.17 A flow diagram 1700 is depicted of sending sensing measurements and timestamps by a sensing receiver to a non-associated access point in accordance with some embodiments.

[0300] In a brief overview of an embodiment of flowchart 1700, at step 1702, a networked device operating as a sensing receiver (e.g., first sensing receiver 502-1) may obtain timing information from an unassociated access point (e.g., first sensing transmitter 504-1) that is not associated with the sensing receiver and operates as a sensing transmitter. At step 1704, the networked device operating as a sensing receiver may generate local timing information based on the timing information. At step 1706, the networked device operating as a sensing receiver may receive a sensing transmission from the unassociated access point. At step 1708, the networked device operating as a sensing receiver may perform sensing measurements on the sensing transmission. At step 1710, the networked device operating as a sensing receiver may associate the sensing measurements with a timestamp based on the local timing information. At step 1712, the networked device operating as a sensing receiver may send the sensing measurements and the timestamp to the unassociated access point.

[0301] Step 1702 includes obtaining, by the sensing receiver, timing information from an unassociated access point that is not associated with the sensing receiver and operates as a sensing transmitter. In an example, the unassociated access point may be a first unassociated access point. According to an embodiment, the networked device operating as a first sensing receiver 502-1 may be configured to obtain timing information from the first sensing transmitter 504-1. In an example, the timing information may be an access point TSF timer (e.g., TSF timer 538-1) of the first sensing transmitter 504-1. In addition, in an example, the timing information may be stored as local timing information.

[0302] Step 1704 includes generating local timing information by the sensing receiver according to the timing information. According to the embodiment, the networked device operating as the first sensing receiver 502-1 can be configured to generate local timing information according to the timing information. In an example, the local timing information can be a timer offset value determined according to the difference between the timing information and the sensing receiver TSF timer (e.g., TSF timer 520-1), and the timestamp is determined by combining the sensing receiver TSF timer value with the timer offset value. In some embodiments, the first sensing receiver 502-1 can obtain additional timing information from multiple additional non-associated access points (e.g., one or more of the remaining sensing transmitters 504-(2-N), examples of which are the second sensing transmitter 504-2, the second sensing transmitter 504-3, etc.). In addition, the first sensing receiver 502-1 can generate additional local timing information according to the additional timing information. In an example, the local timing information is maintained and incremented at the first sensing receiver 502-1. In some examples, the local timing information is incremented according to the local clock at the first sensing receiver 502-1.

[0303] Step 1706 includes receiving, by the sensing receiver, a sensing transmission from the non-associated access point. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to receive the sensing transmission from the first sensing transmitter 504-1. In an embodiment, before receiving the sensing transmission, the first sensing receiver 502-1 may initiate a PASN process with the first sensing transmitter 504-1.

[0304] Step 1708 includes performing, by the sensing receiver, sensing measurements on the sensing transmission. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to perform sensing measurements on the sensing transmission.

[0305] Step 1710 includes associating, by the sensing receiver, the sensing measurements with a timestamp based on the local timing information.According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to associate the sensing measurements with a timestamp based on the local timing information.

[0306] Step 1712 includes sending, by the sensing receiver, the sensing measurements and the timestamp to the non-associated access point. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to send the sensing measurements and the timestamp to the first sensing transmitter 504-1.

[0307] Fig.18A and Fig.18B Depicted is a flow diagram 1800 of resynchronizing local timing information by receiving second timing information from a non-associated access point in accordance with some embodiments.

[0308] In a brief overview of an embodiment of flowchart 1800, at step 1802, a networked device operating as a sensing receiver (e.g., first sensing receiver 502-1) may receive timing information from an unassociated access point (e.g., first sensing transmitter 504-1) that is not associated with the sensing receiver and operates as a sensing transmitter, wherein the timing information is received in a beacon frame broadcast by the unassociated access point. At step 1804, the networked device operating as a sensing receiver may generate local timing information from the timing information by the sensing receiver. At step 1806, the networked device operating as a sensing receiver may send an idle message to the associated access point. At step 1808, the networked device operating as a sensing receiver may tune the sensing receiver to the channel where the beacon frame was received. At step 1810, the networked device operating as a sensing receiver may receive a sensing transmission from the unassociated access point. At step 1812, the networked device operating as a sensing receiver may perform sensing measurements on the sensing transmission. At step 1814, the networked device operating as a sensing receiver may associate the sensing measurements with a timestamp based on the local timing information. At step 1816, the networked device operating as a sensing receiver may receive a sensing report trigger from the non-associated access point. At step 1818, the networked device operating as a sensing receiver may send a sensing measurement and a timestamp to the non-associated access point in response to the sensing report trigger. At step 1820, the networked device operating as a sensing receiver may resynchronize the local timing information by receiving second timing information from the non-associated access point.

[0309] Step 1802 includes receiving timing information by a sensing receiver from an unassociated access point that is not associated with the sensing receiver and operates as a sensing transmitter, wherein the timing information is received in a beacon frame broadcast by the unassociated access point. In an example, the unassociated access point may be a first unassociated access point. According to an embodiment, a networked device operating as a first sensing receiver 502-1 may be configured to receive timing information from a first sensing transmitter 504-1, wherein the timing information is received in a beacon frame broadcast by the first sensing transmitter 504-1. In an example, the timing information may be an access point TSF timer (e.g., TSF timer 538-1) of the first sensing transmitter 504-1. In addition, in an example, the timing information may be stored as local timing information. In some embodiments, the first sensing receiver 502-1 may be associated with an associated access point that operates on the same channel on which a beacon frame is received from an unassociated access point (e.g., the first sensing transmitter 504-1). In an example, the associated access point may be any device other than the first sensing transmitter 504-1 (ie, a sensing transmitter among the remaining sensing transmitters 504-(2-N), examples of which are the second sensing transmitter 504-2 or the third sensing transmitter 504-3, etc.).

[0310] Step 1804 includes generating local timing information according to the timing information by the sensing receiver. According to the embodiment, the networked device operating as the first sensing receiver 502-1 can be configured to generate local timing information according to the timing information. In some embodiments, the first sensing receiver 502-1 can obtain additional timing information from multiple additional non-associated access points (e.g., one or more of the remaining sensing transmitters 504-(2-N), examples of which are the second sensing transmitter 504-2, the second sensing transmitter 504-3, etc.). In addition, the first sensing receiver 502-1 can generate additional local timing information according to the additional timing information. In the example, the local timing information is maintained and incremented at the first sensing receiver 502-1. In some examples, the local timing information is incremented according to the local clock at the first sensing receiver 502-1.

[0311] Step 1806 includes sending an idle message to the associated access point. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to send an idle message to the first sensing transmitter 504-1.

[0312] Step 1808 includes tuning the sensing receiver to the channel on which the beacon frame was received. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to tune the sensing receiver to the channel on which the beacon frame was received.

[0313] Step 1810 includes receiving, by a sensing receiver, a sensing transmission from a non-associated access point. According to an embodiment, the networked device operating as a first sensing receiver 502-1 may be configured to receive a sensing transmission from a first sensing transmitter 504-1. In an embodiment, before receiving the sensing transmission, the first sensing receiver 502-1 may initiate a PASN procedure with the first sensing transmitter 504-1.

[0314] Step 1812 includes performing, by the sensing receiver, sensing measurements on the sensing transmission. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to perform sensing measurements on the sensing transmission.

[0315] Step 1814 includes associating, by the sensing receiver, the sensing measurements with a timestamp based on the local timing information.According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to associate the sensing measurements with a timestamp based on the local timing information.

[0316] Step 1816 includes receiving a sensing report trigger from a non-associated access point. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to receive a sensing report trigger from a non-associated access point.

[0317] Step 1818 includes sending, by the sensing receiver, the sensing measurements and timestamp to the non-associated access point in response to the sensing report trigger.According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to send the sensing measurements and timestamp to the first sensing transmitter 504-1 in response to the sensing report trigger.

[0318] Step 1820 includes resynchronizing the local timing information by receiving the second timing information from the non-associated access point. According to an embodiment, the networked device operating as the first sensing receiver 502-1 can be configured to resynchronize the local timing information by receiving another timing information (i.e., the second timing information) from the first sensing transmitter 504-1. In an example, resynchronizing the local timing information can be performed after the resynchronization timer expires. In an example, the time interval of the resynchronization timer is determined based on the measurement of the timing drift between the first sensing transmitter 504-1 and the first sensing receiver 502-1.

[0319] Fig.19A and Fig.19B Another flow diagram 1900 is depicted for sending sensing measurements and timestamps by a sensing receiver to a non-associated access point in accordance with some embodiments.

[0320] In a brief overview of an embodiment of flowchart 1900, at step 1902, a networked device operating as a sensing receiver (e.g., first sensing receiver 502-1) may send a probe request to an unassociated access point (e.g., first sensing transmitter 504-1) that is not associated with the sensing receiver and operates as a sensing transmitter. At step 1904, in response to the probe request, the networked device operating as a sensing receiver may receive a probe response from the unassociated access point, wherein the probe response contains timing information. At step 1906, the networked device operating as a sensing receiver may generate local timing information based on the timing information. At step 1908, the networked device operating as a sensing receiver may receive a sensing transmission from the unassociated access point. At step 1910, the networked device operating as a sensing receiver may perform sensing measurements on the sensing transmission. At step 1912, the networked device operating as a sensing receiver may associate the sensing measurements with a timestamp based on the local timing information. At step 1914, the networked device operating as a sensing receiver may send the sensing measurements and the timestamp to the unassociated access point.

[0321] Step 1902 includes sending, by the sensing receiver, a probe request to an unassociated access point that is not associated with the sensing receiver and operates as a sensing transmitter. In an example, the unassociated access point may be a first unassociated access point. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to send a probe request to the first sensing transmitter 504-1.

[0322] Step 1904 includes receiving, by a sensing receiver and in response to a probe request, a probe response from a non-associated access point, wherein the probe response includes timing information. According to an embodiment, a networked device operating as a first sensing receiver 502-1 may be configured to receive a probe response from a first sensing transmitter 504-1 in response to a probe request, wherein the probe response includes timing information. In an example, the timing information may be an access point TSF timer (e.g., TSF timer 538-1) of the first sensing transmitter 504-1. In addition, in an example, the timing information may be stored as local timing information. In an example, the probe request may include at least one access point identifier, and the probe response may include at least one response from an access point associated with the at least one access point identifier. In some examples, the probe request includes an access point identifier wildcard, and the probe response includes at least one response from an access point.

[0323] Step 1906 includes generating local timing information according to the timing information by the sensing receiver. According to the embodiment, the networked device operating as the first sensing receiver 502-1 can be configured to generate local timing information according to the timing information. In some embodiments, the first sensing receiver 502-1 can obtain additional timing information from multiple additional non-associated access points (e.g., one or more of the remaining sensing transmitters 504-(2-N), examples of which are the second sensing transmitter 504-2, the second sensing transmitter 504-3, etc.). In addition, the first sensing receiver 502-1 can generate additional local timing information according to the additional timing information. In the example, the local timing information is maintained and incremented at the first sensing receiver 502-1. In some examples, the local timing information is incremented according to the local clock at the first sensing receiver 502-1.

[0324] Step 1908 includes receiving, by the sensing receiver, a sensing transmission from the non-associated access point. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to receive the sensing transmission from the first sensing transmitter 504-1. In an embodiment, before receiving the sensing transmission, the first sensing receiver 502-1 may initiate a PASN process with the first sensing transmitter 504-1.

[0325] Step 1910 includes performing, by the sensing receiver, sensing measurements on the sensing transmission. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to perform sensing measurements on the sensing transmission.

[0326] Step 1912 includes associating, by the sensing receiver, the sensing measurements with a timestamp based on the local timing information.According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to associate the sensing measurements with a timestamp based on the local timing information.

[0327] Step 1914 includes sending, by the sensing receiver, the sensing measurements and the timestamp to the non-associated access point. According to an embodiment, the networked device operating as the first sensing receiver 502-1 may be configured to send the sensing measurements and the timestamp to the first sensing transmitter 504-1.

[0328] Additional embodiments according to the present invention include at least the following.

[0329] Embodiment 1 is a method for Wi-Fi sensing performed by a networked device, the networked device being configured to operate as a sensing receiver and comprising at least one processor configured to execute instructions. The method comprises: obtaining, by the sensing receiver, timing information from an unassociated access point that is not associated with the sensing receiver and operates as a sensing transmitter; generating, by the sensing receiver, local timing information based on the timing information; receiving, by the sensing receiver, a sensing transmission from the unassociated access point; performing, by the sensing receiver, a sensing measurement on the sensing transmission; associating, by the sensing receiver, the sensing measurement with a timestamp based on the local timing information; and sending, by the sensing receiver, the sensing measurement and the timestamp to the unassociated access point.

[0330] Embodiment 2 is a method according to embodiment 1, wherein the timing information is an access point TSF timer of the non-associated access point.

[0331] Embodiment 3 is a method according to embodiment 2, wherein the timing information is stored as the local timing information.

[0332] Embodiment 4 is a method according to embodiment 2 or 3, wherein the local timing information is a timer offset value determined based on the difference between the timing information and a sensing receiver TSF timer, and the timestamp is determined by combining the sensing receiver TSF timer value with the timer offset value.

[0333] Embodiment 5 is a method according to any one of embodiments 1 to 4, wherein the non-associated access point is a first non-associated access point, and the method further includes: obtaining additional timing information from multiple additional non-associated access points by the sensing receiver; and generating additional local timing information based on the additional timing information by the sensing receiver.

[0334] Embodiment 6 is the method of any one of embodiments 1 to 5, wherein the timing information is received in a beacon frame broadcast by the non-associated access point.

[0335] Embodiment 7 is the method of embodiment 6, wherein receiving the sensing transmission further comprises tuning the sensing receiver to a channel on which the beacon frame was received.

[0336] Embodiment 8 is the method of embodiment 6 or 7, wherein the sensing receiver is associated with an associated access point operating on the same channel on which the beacon frame is received from the non-associated access point.

[0337] Embodiment 9 is a method according to embodiment 7 or 8, wherein the method further comprises sending an idle message to the associated access point.

[0338] Embodiment 10 is a method according to any one of embodiments 1 to 9, wherein the method further comprises: sending a probe request by the sensing receiver; and receiving a probe response including the timing information by the sensing receiver in response to the probe request.

[0339] Embodiment 11 is a method according to embodiment 10, wherein the probe request includes at least one access point identification, and the probe response includes at least one response from an access point associated with the at least one access point identification.

[0340] Embodiment 12 is a method according to embodiment 10 or 11, wherein the probe request includes an access point identification wildcard and the probe response includes at least one response from an access point.

[0341] Embodiment 13 is the method of any one of embodiments 3 to 12, wherein the local timing information is maintained and incremented at the sensing receiver.

[0342] Embodiment 14 is the method of embodiment 13, wherein the local timing information is incremented at the sensing receiver according to a local clock.

[0343] Embodiment 15 is the method of any one of embodiments 1 to 14, wherein prior to receiving the sensing transmission, the sensing receiver initiates a PASN procedure with the sensing transmitter.

[0344] Embodiment 16 is the method of any one of embodiments 1 to 15, wherein the sensing receiver sends the sensing measurements in response to receiving a sensing report trigger.

[0345] Embodiment 17 is the method of any one of embodiments 1 to 16, further comprising resynchronizing the local timing information by receiving second timing information from the non-associated access point.

[0346] Embodiment 18 is a method according to embodiment 17, wherein resynchronizing the local timing information is performed after expiration of a resynchronization timer.

[0347] Embodiment 19 is a method according to embodiment 17 or 18, wherein a time interval of the resynchronization timer is determined based on a measurement of a timing drift between the non-associated access point and the sensing receiver.

[0348] Embodiment 20 is the method of any one of embodiments 1 to 19, further comprising resynchronizing the local timing information by receiving a portion of second timing information from the non-associated access point.

[0349] Embodiment 21 is a system for Wi-Fi sensing, the system comprising: a networked device, which is configured to operate as a sensing receiver and includes at least one processor, the at least one processor being configured to execute instructions to perform the following operations: obtaining timing information by the sensing receiver from an unassociated access point that is not associated with the sensing receiver and operates as a sensing transmitter; generating local timing information by the sensing receiver based on the timing information; receiving a sensing transmission from the unassociated access point by the sensing receiver; performing sensing measurements on the sensing transmission by the sensing receiver; associating the sensing measurements with a timestamp by the sensing receiver based on the local timing information; and sending the sensing measurements and the timestamp by the sensing receiver to the unassociated access point.

[0350] Embodiment 22 is the system of embodiment 21, wherein the timing information is an access point TSF timer of the non-associated access point.

[0351] Embodiment 23 is a system according to embodiment 22, wherein the timing information is stored as the local timing information.

[0352] Embodiment 24 is a system according to embodiment 22 or 23, wherein the local timing information is a timer offset value determined based on the difference between the timing information and a sensing receiver TSF timer, and the timestamp is determined by combining the sensing receiver TSF timer value with the timer offset value.

[0353] Embodiment 25 is a system according to any one of embodiments 21 to 24, wherein the non-associated access point is a first non-associated access point, and the system further includes: obtaining additional timing information from multiple additional non-associated access points by the sensing receiver; and generating additional local timing information based on the additional timing information by the sensing receiver.

[0354] Embodiment 26 is the system of any one of embodiments 21 to 25, wherein the timing information is received in a beacon frame broadcast by the non-associated access point.

[0355] Embodiment 27 is the system of embodiment 26, wherein receiving the sensing transmission further comprises tuning the sensing receiver to a channel on which the beacon frame was received.

[0356] Embodiment 28 is the system of embodiment 26 or 27, wherein the sensing receiver is associated with an associated access point operating on the same channel on which the beacon frame is received from the non-associated access point.

[0357] Embodiment 29 is the system of embodiment 27 or 28, wherein the system further comprises sending an idle message to the associated access point.

[0358] Embodiment 30 is a system according to any one of embodiments 21 to 29, wherein the instructions are further configured for: sending a probe request by the sensing receiver; and receiving a probe response containing the timing information by the sensing receiver in response to the probe request.

[0359] Embodiment 31 is a system according to embodiment 30, wherein the probe request includes at least one access point identification, and the probe response includes at least one response from an access point associated with the at least one access point identification.

[0360] Embodiment 32 is a system according to embodiment 30 or 31, wherein the probe request includes an access point identification wildcard and the probe response includes at least one response from an access point.

[0361] Embodiment 33 is the system of any one of embodiments 23 to 32, wherein the local timing information is maintained and incremented at the sensing receiver.

[0362] Embodiment 34 is the system of embodiment 33, wherein the local timing information is incremented at the sensing receiver according to a local clock.

[0363] Embodiment 35 is the system of any one of embodiments 21 to 34, wherein the sensing receiver initiates a PASN procedure with the sensing transmitter prior to receiving the sensing transmission.

[0364] Embodiment 36 is the system of any one of Embodiments 21 to 35, wherein the sensing receiver sends the sensing measurements in response to receiving a sensing report trigger.

[0365] Embodiment 37 is the system of any one of embodiments 21 to 36, further comprising resynchronizing the local timing information by receiving second timing information from the non-associated access point.

[0366] Embodiment 38 is a system according to any one of embodiments 27 to 37, wherein resynchronizing the local timing information is performed after expiration of a resynchronization timer.

[0367] Embodiment 39 is the system of any one of embodiments 27 to 38, wherein a time interval of the resynchronization timer is determined based on a measurement of a timing drift between the non-associated access point and the sensing receiver.

[0368] Embodiment 40 is the system of any one of embodiments 21 to 39, further comprising resynchronizing the local timing information by receiving a portion of second timing information from the non-associated access point.

[0369] Although various embodiments of the methods and systems have been described, these embodiments are illustrative and in no way limit the scope of the described methods or systems. Persons skilled in the relevant art may make changes in the form and details of the described methods and systems without departing from the broadest scope of the described methods and systems. Therefore, the scope of the methods and systems described herein should not be limited by any illustrative embodiments, but should be defined in accordance with the appended claims and their equivalents.

Claims

1. A method for Wi-Fi sensing performed by a networked device, the networked device being configured to operate as a sensing receiver and comprising at least one processor configured to execute instructions, the method include: obtaining, by the sensing receiver, timing information from an unassociated access point that is not associated with the sensing receiver and operates as a sensing transmitter; generating, by the sensing receiver, local timing information based on the timing information; receiving, by the sensing receiver, a sensing transmission from the non-associated access point; performing, by the sensing receiver, a sensing measurement on the sensing transmission; associating, by the sensing receiver, the sensing measurements with a timestamp based on the local timing information; as well as The sensing measurements and the timestamp are sent by the sensing receiver to the non-associated access point.

2. The method of claim 1, wherein the timing information is an access point TSF timer of the non-associated access point. The method of claim 2 , wherein the timing information is stored as the local timing information.

4. The method of claim 2, wherein the local timing information is a timer offset value determined according to a difference between the timing information and a sensing receiver TSF timer, and the timestamp is determined by combining the sensing receiver TSF timer value with the timer offset value.

5. The method of claim 1, wherein the unassociated access point is a first unassociated access point, the method further comprising: include: obtaining, by the sensing receiver, additional timing information from a plurality of additional non-associated access points; as well as Additional local timing information is generated by the sensing receiver based on the additional timing information.

6. The method of claim 1, wherein the timing information is received in a beacon frame broadcast by the non-associated access point.

7. The method of claim 6, wherein receiving the sensing transmission further comprises tuning the sensing receiver to a channel on which the beacon frame was received.

8. The method of claim 6, wherein the sensing receiver is associated with an associated access point operating on a same channel on which the beacon frame is received from the non-associated access point.

9. The method according to claim 7, further comprising: include: An idle message is sent to the associated access point.

10. The method according to claim 1, further comprising: include: sending a detection request by the sensing receiver; as well as In response to the probe request, a probe response including the timing information is received by the sensing receiver.

11. The method of claim 10, wherein the probe request comprises at least one access point identification, and the probe response comprises at least one response from an access point associated with the at least one access point identification.

12. The method of claim 10, wherein the probe request includes an access point identification wildcard and the probe response includes at least one response from an access point.

13. The method of claim 3, wherein the local timing information is maintained and incremented at the sensing receiver. The method of claim 13 , wherein local timing information is incremented at the sensing receiver according to a local clock.

15. The method of claim 1, wherein prior to receiving the sensing transmission, the sensing receiver initiates a PASN procedure with the sensing transmitter.

16. The method of claim 1, wherein the sensing receiver sends the sensing measurements in response to receiving a sensing report trigger.

17. The method of claim 1, further comprising resynchronizing the local timing information by receiving second timing information from the non-associated access point.

18. The method of claim 17, wherein resynchronizing the local timing information is performed after expiration of a resynchronization timer.

19. The method of claim 17, wherein a time interval of the resynchronization timer is determined based on a measurement of a timing drift between the non-associated access point and the sensing receiver.

20. The method of claim 1, further comprising resynchronizing the local timing information by receiving a portion of second timing information from the non-associated access point.

21. A system for Wi-Fi sensing, wherein include: A networked device configured to operate as a sensing receiver and comprising at least one processor configured to execute instructions to: obtaining, by the sensing receiver, timing information from an unassociated access point that is not associated with the sensing receiver and operates as a sensing transmitter; generating, by the sensing receiver, local timing information based on the timing information; receiving, by the sensing receiver, a sensing transmission from the non-associated access point; performing, by the sensing receiver, a sensing measurement on the sensing transmission; associating, by the sensing receiver, the sensing measurements with a timestamp based on the local timing information; as well as The sensing measurements and the timestamp are sent by the sensing receiver to the non-associated access point.

22. The system of claim 21, wherein the timing information is an access point TSF timer of the non-associated access point.

23. The system of claim 22, wherein the timing information is stored as the local timing information.

24. The system of claim 22, wherein the local timing information is a timer offset value determined based on a difference between the timing information and a sensing receiver TSF timer, and the timestamp is determined by combining the sensing receiver TSF timer value with the timer offset value.

25. The system of claim 21, wherein the unassociated access point is a first unassociated access point, the system further comprising: include: obtaining, by the sensing receiver, additional timing information from a plurality of additional non-associated access points; as well as Additional local timing information is generated by the sensing receiver based on the additional timing information.

26. The system of claim 21, wherein the timing information is received in a beacon frame broadcast by the non-associated access point.

27. The system of claim 26, wherein receiving the sensing transmission further comprises tuning the sensing receiver to a channel on which the beacon frame was received.

28. The system of claim 26, wherein the sensing receiver is associated with an associated access point operating on a same channel on which the beacon frame is received from the non-associated access point.

29. The system according to claim 27, further comprising: include: An idle message is sent to the associated access point.

30. The system of claim 21, wherein the instructions are further configured to: sending, by the sensing receiver, a probe request; and In response to the probe request, a probe response including the timing information is received by the sensing receiver.

31. The system of claim 30, wherein the probe request comprises at least one access point identification, and the probe response comprises at least one response from an access point associated with the at least one access point identification.

32. The system of claim 30, wherein the probe request includes an access point identification wildcard and the probe response includes at least one response from an access point.

33. The system of claim 23, wherein the local timing information is maintained and incremented at the sensing receiver.

34. The system of claim 33, wherein local timing information is incremented at the sensing receiver according to a local clock.

35. The system of claim 21, wherein the sensing receiver initiates a PASN procedure with the sensing transmitter prior to receiving the sensing transmission.

36. The system of claim 21, wherein the sensing receiver sends the sensing measurements in response to receiving a sensing report trigger.

37. The system of claim 21, further comprising resynchronizing the local timing information by receiving second timing information from the non-associated access point.

38. The system of claim 27, wherein resynchronizing the local timing information is performed after expiration of a resynchronization timer.

39. The system of claim 27, wherein a time interval of the resynchronization timer is determined based on a measurement of a timing drift between the non-associated access point and the sensing receiver.

40. The system of claim 21, further comprising resynchronizing the local timing information by receiving a portion of second timing information from the non-associated access point.

Images