SYSTEM AND METHOD FOR DYNAMIC TIME DOMAIN CHANNEL REPRESENTATION - Patent application

Abstract

A system and method for dynamic channel representation are described. First, a sensing receiver receives a sensed transmission. Then, the sensing receiver generates sensed measurements based on the sensed transmission. Thereafter, the sensing receiver generates channel representation information of a propagation channel between the sensing receiver and the sensing transmitter based on the sensed measurements. Then, the sensing receiver obtains a sensed imprint that represents a steady-state propagation channel between the sensing receiver and the sensing transmitter. Furthermore, the sensing receiver compares the channel representation information with the sensed imprint and identifies a difference between the channel representation information and the sensed imprint. The sensing receiver may further send the channel representation information to a sensing algorithm manager.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to systems and methods for Wi-Fi sensing, and more particularly to configuring a Wi-Fi system and method for generating a dynamic time domain channel representation for Wi-Fi sensing. [Background technology]

[0002] Motion detection systems are used, for example, to detect the movement of objects within a room or an outdoor area. In some exemplary motion detection systems, infrared or optical sensors are used to detect the movement of objects within the field of view of the sensor. Motion detection systems are used in security systems, automatic control systems, and other types of systems. Wi-Fi sensing systems are a recent addition to motion detection systems.

[0003] The Wi-Fi sensing system may be a network of Wi-Fi enabled devices that may be part of an IEEE 802.11 network. For example, the Wi-Fi sensing system may include a sensing receiver and a sensing transmitter. In one example, the Wi-Fi sensing system may be configured to detect features of interest within a sensing space. The sensing space may refer to any physical space in which the Wi-Fi sensing system may operate, such as a residence, a workplace, a shopping mall, a sports hall or sports stadium, a garden, or any other physical space. The features of interest may include object motion and motion tracking, presence detection, intrusion detection, gesture recognition, fall detection, respiration rate detection, and other applications. The motion or movement may be determined within the sensing space by a Wi-Fi sensing algorithm based on the transmission path between the sensing receiver and the sensing transmitter.

[0004] In a Wi-Fi sensing system, information representing the propagation channel (i.e., channel representation information) may need to be transmitted over the air from one device to another (e.g., from a sensing receiver to a sensing transmitter). The representation of the propagation channel between devices is currently captured in channel state information (CSI). Typically, CSI is a set of complex values ​​in the frequency domain that represent the amplitude attenuation and phase rotation of each tone of a multi-tone orthogonal frequency division multiplexing (OFDM) signal. In one example, for a 20 MHz propagation channel bandwidth, 52 CSI complex pairs are used to represent the propagation channel. In another example, for a 40 MHz propagation channel bandwidth, 104 CSI complex pairs are used to represent the propagation channel. As the propagation bandwidth increases, the number of CSI complex pairs used to represent the propagation channel also increases. Thus, transmitting channel information from one device to another may require passing a significant amount of information, resulting in the consumption of channel capacity that would otherwise be used for data transfer. Also, the wider the channel bandwidth, the more complex values ​​need to be transmitted, and therefore the greater the channel utilization caused by transmitting CSI over the air. Furthermore, CSI needs to be passed from the physical (PHY) layer to the media access control (MAC) layer. Currently, there is no standardized way to transmit CSI from the PHY layer to the MAC layer, and Wi-Fi sensing algorithms rely on a proprietary interface. Summary of the Invention

[0005] FIELD OF THE DISCLOSURE The present disclosure relates generally to systems and methods for Wi-Fi sensing, and more particularly to configuring a Wi-Fi system and method for generating a dynamic time domain channel representation for Wi-Fi sensing.

[0006] A system and method for Wi-Fi detection is provided. In one embodiment, a method for Wi-Fi detection is provided that is implemented by a detection receiver including a transmit antenna, a receive antenna, and at least one processor configured to execute instructions. The method includes transmitting a detection trigger message via the transmit antenna, receiving a detection transmission from a detection transmitter via the receive antenna, obtaining, by the at least one processor, channel representation information based on the detection transmission, identifying, by the at least one processor, that a difference between the channel representation information and a detection imprint exceeds a threshold, where the detection imprint includes two or more previously measured channel representation information, and sending the channel representation information to a detection algorithm manager in response to identifying that the difference exceeds a threshold.

[0007] In another embodiment, a method for Wi-Fi detection implemented by a device including a transmit antenna, a receive antenna, and at least one processor configured to execute instructions is provided, the method including receiving a threshold value from a detection initiator via the receive antenna, receiving a detection transmit announce message and a detection transmit null data PPDU (NDP) via the receive antenna from a detection transmitter, obtaining, by the at least one processor, channel representation information based on the detection transmit NDP, receiving a measurement poll message from the detection initiator via the receive antenna, identifying, by the at least one processor, that a difference between the channel representation information and a detection imprint exceeds a threshold value, where the detection imprint includes two or more previously measured channel representation information, and sending, by the at least one processor, the channel representation information to the detection initiator via the transmit antenna in response to identifying that the difference exceeds the threshold value.

[0008] In another embodiment, a method for Wi-Fi sensing implemented by a device including a transmitting antenna, a receiving antenna, and at least one processor configured to execute instructions is provided, the method including receiving a sensing imprint from a sensing receiver via the receiving antenna, transmitting a sensing transmission to the sensing receiver via the transmitting antenna, transmitting a measurement polling message to the sensing receiver via the transmitting antenna, receiving channel representation information based on the sensing transmission via the receiving antenna, identifying, by the at least one processor, that a difference between the channel representation information and the sensing imprint exceeds a threshold, where the sensing imprint includes two or more previously measured channel representation information, and sending the channel representation information to a sensing algorithm manager in response to identifying that the difference exceeds the threshold.

[0009] In another embodiment, a system for Wi-Fi detection is provided that includes a detection receiver including a transmit antenna, a receive antenna, and at least one processor configured to execute instructions. The instructions may include transmitting a detection trigger message via the transmit antenna, receiving a detection transmission from the detection transmitter via the receive antenna, obtaining channel representation information based on the detection transmission, identifying a difference between the channel representation information and a detection imprint that exceeds a threshold, where the detection imprint includes two or more previously measured channel representation information, and sending the channel representation information to a detection algorithm manager in response to identifying the difference that exceeds the threshold.

[0010] In another embodiment, a system for Wi-Fi detection is provided that includes a device including a transmit antenna, a receive antenna, and at least one processor configured to execute instructions, which may include: receiving a threshold value from a detection initiator via the receive antenna, receiving a detection transmit announce message and a detection transmit null data PPDU (NDP) from a detection transmitter via the receive antenna, obtaining channel representation information based on the detection transmit NDP, receiving a measurement poll message from the detection initiator via the receive antenna, identifying that a difference between the channel representation information and a detection imprint exceeds a threshold value, where the detection imprint includes two or more previously measured channel representation information, and sending the channel representation information to the detection initiator via the transmit antenna in response to identifying that the difference exceeds a threshold value.

[0011] In another embodiment, a system for Wi-Fi sensing is provided that includes a device including a transmitting antenna, a receiving antenna, and at least one processor configured to execute instructions, which may include receiving a sensing imprint from a sensing receiver via the receiving antenna, transmitting a sensing transmission to the sensing receiver via the transmitting antenna, transmitting a measurement polling message to the sensing receiver via the transmitting antenna, receiving channel representation information based on the sensing transmission via the receiving antenna, identifying that a difference between the channel representation information and the sensing imprint exceeds a threshold, where the sensing imprint includes two or more previously measured channel representation information, and in response to identifying that the difference exceeds a threshold, sending the channel representation information to a sensing algorithm manager.

[0012] In an exemplary embodiment, a method configured for Wi-Fi detection is described. The method is implemented by a detection receiver including a transmit antenna, a receive antenna, and a processor configured to execute instructions. The method includes receiving a detection transmission via the receive antenna, generating, by at least one processor, a detection measurement based on the detection transmission, generating, by at least one processor, a full time domain channel representation (TD-CRI) of a propagation channel between the detection receiver and the detection transmitter based on the detection measurement, obtaining, by at least one processor, a detection imprint representing a steady-state propagation channel between the detection receiver and the detection transmitter, comparing, by at least one processor, the full TD-CRI and the detection imprint, identifying, by at least one processor, a filtered TD-CRI according to a difference between the full TD-CRI and the detection imprint, and sending the filtered TD-CRI to a detection algorithm manager.

[0013] In some implementations, identifying the filtered TD-CRI includes determining a first time-domain pulse of the full TD-CRI that is different from a second time-domain pulse of the detection imprint, and designating the first time-domain pulse as the filtered TD-CRI.

[0014] In some implementations, the method further includes obtaining, by the detection algorithm manager, a detection imprint, and generating, by the detection algorithm manager, a reconstructed TD-CRI by replacing a corresponding time-domain pulse of the detection imprint with a first time-domain pulse of the filtered TD-CRI.

[0015] In some implementations, the method further includes transmitting to the detection algorithm manager a location bitmap indicating a location within the full TD-CRI of the first time-domain pulse.

[0016] In some implementations, the method further includes storing a difference between the first time-domain pulse of the full TD-CRI and the second time-domain pulse of the detection imprint as an imprint delta defining the filtered TD-CRI.

[0017] In some implementations, the difference stored as the imprint delta requires fewer bits than the first time-domain pulse.

[0018] In some implementations, storing the difference between the first time-domain pulse of the full TD-CRI and the second time-domain pulse of the detection imprint includes storing only the difference that exceeds a measurement imprint delta threshold.

[0019] In some implementations, the method further includes obtaining, by the detection algorithm manager, a detection imprint and generating a reconstructed TD-CRI by adding, by the detection algorithm manager, the difference stored in the imprint delta to a corresponding time domain pulse of the detection imprint.

[0020] In some implementations, the method further includes sending, to the detection algorithm manager, a location bitmap indicating the imprint delta locations corresponding to the TD-CRI locations.

[0021] In some implementations, the comparison of the full TD-CRI with the sensing imprint is performed in response to a request from the sensing algorithm manager for high-fidelity TD-CRI reconstruction.

[0022] In some implementations, the method further includes sending the sensing imprint indicator to a sensing algorithm manager.

[0023] In some implementations, the method further includes performing a sensing imprint update determination and updating the sensing imprint in response to the sensing imprint update determination.

[0024] In some implementations, making a sensed imprint update determination includes obtaining a previous imprint delta selected according to a steady-state imprint delta period, comparing the previous imprint delta with a current imprint delta, identifying a changed time-domain pulse in the previous imprint delta and a corresponding time-domain pulse in the current imprint delta, and determining that the corresponding time-domain pulse remains above a steady-state imprint delta threshold.

[0025] In some implementations, making the sensed imprint update determination includes obtaining a previous imprint delta selected according to an imprint delta derivative period, comparing the previous imprint delta with a current imprint delta, identifying a time domain pulse that has changed between the previous imprint delta and the current imprint delta, and determining that the corresponding time domain pulse has fallen below an imprint delta derivative threshold.

[0026] In some implementations, making the sensing imprint update determination includes determining that an imprint validity timer has expired.

[0027] In another exemplary embodiment, a method configured for Wi-Fi sensing is described. The method is implemented by a device including a receiving antenna and a processor configured to execute instructions. The method includes receiving a filtered TD-CRI via the receiving antenna, acquiring a sensing imprint by at least one processor, generating a reconstructed TD-CRI from the filtered TD-CRI and the sensing imprint by a sensing algorithm manager, transforming the reconstructed TD-CRI into a reconstructed frequency domain channel representation, and detecting a feature of interest in a sensing space by the sensing algorithm manager according to the reconstructed frequency domain channel representation.

[0028] In some embodiments, receiving the filtered TD-CRI includes receiving a plurality of time-domain pulses, and generating the reconstructed TD-CRI includes replacing a corresponding time-domain pulse of the sensing imprint with the plurality of time-domain pulses.

[0029] In some embodiments, the method further includes receiving a location bitmap indicating a location of the corresponding time-domain pulse within the sensing imprint.

[0030] In some embodiments, receiving the filtered TD-CRI includes receiving an imprint delta that stores a time-domain pulse difference, and generating the reconstructed TD-CRI includes adding the time-domain pulse difference to a corresponding time-domain pulse of the detection imprint.

[0031] In some embodiments, the method further includes receiving a location bitmap indicating a location of the corresponding time-domain pulse within the sensing imprint.

[0032] In some embodiments, the method further comprises receiving a sensing imprint indicator, and wherein obtaining the sensing imprint is performed according to the sensing imprint indicator.

[0033] In some embodiments, the method further includes performing a sensing imprint update determination and updating the sensing imprint in response to the sensing imprint update determination.

[0034] In some embodiments, making a sensed imprint update determination includes obtaining a previous imprint delta selected according to a steady-state imprint delta period, comparing the previous imprint delta with the current imprint delta, identifying a changed time domain pulse of the previous imprint delta and a corresponding time domain pulse of the current imprint delta, and determining that the corresponding time domain pulse remains above the steady-state imprint delta threshold.

[0035] In some embodiments, making a sensed imprint update determination includes obtaining a previous imprint delta selected according to an imprint delta derivative period, comparing the previous imprint delta with a current imprint delta, identifying a time domain pulse that has changed between the previous imprint delta and the current imprint delta, and determining that the corresponding time domain pulse is below an imprint delta derivative threshold.

[0036] In some embodiments, making the sensing imprint update determination includes determining that an imprint validity timer has expired.

[0037] 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 disclosure. [Brief description of the drawings]

[0038] The above and other objects, aspects, features, and advantages of the present disclosure will become more apparent and be better understood by referring to the following description taken in conjunction with the accompanying drawings.

[0039] [Figure 1] FIG. 1 illustrates an example wireless communication system. [Figure 2A-2B] FIG. 2 illustrates exemplary wireless signals communicated between wireless communication devices. [Figure 3A-3B] 4 is a plot illustrating an example of a channel response calculated from a wireless signal communicated between the wireless communication devices in FIGS. 2A and 2B. [Figure 4A-4B] 1A-1C illustrate example channel responses associated with the movement of objects in distinct regions of space. [Fig. 4C-4D] 4C is a plot of the example channel response of FIGS. 4A and 4B superimposed on an example channel response in the absence of spatial motion. [Diagram 5]1 depicts an implementation of part of an architecture of a system for Wi-Fi detection according to some embodiments. [Figure 6] 1 illustrates a representation of a receiver chain of a sensing receiver, according to some embodiments. [Figure 7] 1 illustrates an example of phasor subtraction, according to some embodiments. [Figure 8] 1 illustrates an example of phase rotation, amplitude scaling, and amplitude difference after phase rotation, according to some embodiments. [Figure 9] 1 depicts an illustrative diagram of filtered time domain channel representation information (TD-CRI) in accordance with some embodiments. [Figure 10] 1 depicts an example of a set of modified time-domain pulses in full TD-CRI according to some embodiments. [Figure 11] 13 depicts another example of a set of modified time-domain pulses in full TD-CRI according to some embodiments. [Figure 12] 1 illustrates a management frame carrying a sensing transmission according to some embodiments. [Figure 13] 1 illustrates a management frame carrying a Channel Representation Information (CRI) transmission message, according to some embodiments. [Figure 14] 1 illustrates a sequence diagram for communication between a detection receiver, a detection transmitter, and a detection algorithm manager, according to some embodiments, where the detection receiver is a detection initiator. [Figure 15] 1 illustrates a sequence diagram for communication between a detection receiver, a detection sender, and a detection algorithm manager, according to some embodiments, where the detection sender is a detection initiator. [Figure 16] 1 illustrates a sequence diagram for communication between a detection receiver and a detection sender including a detection algorithm manager, where the detection sender is a detection initiator, according to some embodiments. [Figure 17A-17B] 13 depicts a flowchart for sending a filtered TD-CRI to a detection algorithm manager according to some embodiments. [Figure 18] 1 depicts a flowchart for detecting features of interest in a sensing space, according to some embodiments. [Figure 19A-19B] 13 depicts a flowchart for sending a location bitmap indicating locations within a full TD-CRI to a detection algorithm manager according to some embodiments. [Figure 20] 1 depicts a flowchart for making a sensing imprint update decision based on a steady-state imprint delta threshold according to some embodiments. [Figure 21] 13 depicts a flowchart for making a sensing imprint update decision based on an imprint delta derivative threshold according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The Wi-Fi sensing system may measure the environment by transmitting signals to sensing transmitters and analyzing responses received from the sensing transmitters. The Wi-Fi sensing system may perform repeated measurements to analyze the environment and its changes. The Wi-Fi sensing system may benefit from having a Medium Access Control (MAC) layer entity that may work in conjunction with existing communication components and may be used to coordinate airtime resource usage between multiple devices based on a defined protocol.

[0041] One of the relevant standardization goals of a Wi-Fi sensing system is to reduce additional overhead on existing Wi-Fi networks so that overlaying Wi-Fi sensing functionality on 802.11 networks does not impair the communication capabilities of the network. One aspect of sensing in a Wi-Fi sensing system is the solicitation of sensing transmissions from sensing transmitters. Improvements to the MAC layer that allow solicitation of sensing transmissions from sensing transmitters with properties optimized to enable Wi-Fi sensing agents to detect presence, location, and motion can significantly impact existing system performance. In particular, the uplink scheduler of the sensing transmitters may be affected by requests or solicitations of sensing transmitter transmissions optimized for sensing (or sensing transmissions). There are existing mechanisms to request or solicit sensing transmitters to transmit sensing transmissions. However, such mechanisms were designed for different purposes. As a result, these mechanisms are not efficient, do not provide flexibility in control, and are not universally consistent between different vendors' implementations. Additionally, a channel sounding protocol may be considered to support Wi-Fi sensing. However, channel sounding protocols are currently inflexible, making such functionality in support of Wi-Fi detection impossible.

[0042] Wi-Fi system protocols are designed around data transfer mechanisms as opposed to detection requirements, and as a result, Wi-Fi detection aspects are often not exploited within typical Wi-Fi systems.

[0043] In some aspects of what is described herein, the wireless sensing system may be used for various wireless sensing applications by processing wireless signals (e.g., radio frequency signals) communicated through the air between wireless communication devices. Exemplary wireless sensing applications include motion detection, which may include detection of object movement in space, motion tracking, respiration detection, respiration monitoring, presence detection, gesture detection, gesture recognition, human detection (moving human detection 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, gait rate 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 recognition, tamper detection, touch detection, attack detection, user authentication, driver fatigue detection, traffic monitoring, smoking detection, school violence detection, human counting, human recognition, bike localization, human cue estimation, Wi-Fi imaging, and other types of wireless sensing applications. For example, the wireless sensing system may 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 may be configured to control measurement rates, wireless connections, and device participation, for example, to improve system operation or achieve other technical advantages. The system improvements and technical advantages achieved when the wireless sensing system is used for motion detection are also achieved in examples where the wireless sensing system is used for another type of wireless sensing application.

[0044] In some example wireless sensing systems, the wireless signal includes components (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 collected channel information over a period of time. In some examples, the wireless sensing system can operate like a bi-stationary radar system, where a Wi-Fi access point (AP) acts as a receiver, and each Wi-Fi device (station, node, or peer) connected to the AP acts as a transmitter. The wireless sensing system can trigger the connected devices to generate transmissions and generate channel response measurements at the receiver devices. This triggering process can be repeated periodically to obtain a series of time-varying measurements. The wireless sensing algorithm can then receive as input a time series of generated channel response measurements (e.g., calculated by the Wi-Fi receiver), and through correlation or filtering, make a decision (e.g., determine whether there is motion or no motion in the environment represented by the channel response based on changes or patterns in the channel estimate). Wireless sensing algorithms may contain the intelligence necessary to extract desired features from channel response measurements and may vary based on the desired sensing application.

[0045] In an example where a wireless sensing system detects motion, it may also be possible to identify the location of the motion within the environment based on motion detection results among multiple wireless devices.

[0046] Thus, wireless signals received at each of the wireless communication devices in a wireless communication network may be analyzed to determine channel information for various communication links (between respective pairs of wireless communication devices) in the network. The channel information may represent a physical medium that applies a transfer function to the wireless signals traversing the space. In some cases, the channel information includes a channel response. The channel response may characterize a physical communication path, e.g., representing the combined effects of scattering, fading, and power attenuation in the space between a transmitter and a receiver. In some cases, the channel information includes beamforming state information (e.g., feedback matrix, steering matrix, channel state information (CSI), etc.) provided by a beamforming system. Beamforming is a signal processing technique often used in multi-antenna (multiple-input / multiple-output (MIMO)) wireless systems for directional signal transmission or reception. Beamforming may be achieved by operating elements in an antenna array such that signals at certain angles experience constructive interference and other signals experience destructive interference.

[0047] The channel information for each of the communication links may be analyzed (e.g., by a hub device or other device in the wireless communication network, or by a sensing transmitter communicatively coupled to the network) to, for example, detect whether motion has occurred in the space, to determine a relative location of the detected motion, or both. In some aspects, the channel information for each of the communication links may be analyzed to detect whether an object is present or absent, for example, if no motion is detected in the space. According to some aspects, the channel information may be offloaded to an external device. The external device may process the channel information to detect whether an object is present or absent. In one example, the channel information may be transmitted over the air from one device to another. Furthermore, the channel utilization caused by the transmission of the channel information over the air may vary based on the width of the channel bandwidth.

[0048] In some cases, the wireless sensing system may perform band steering or client steering of nodes across a wireless network, for example, in a Wi-Fi multi-AP or extended service set (ESS) topology, multiple cooperating wireless access points (APs) each occupy a different frequency band and provide a basic service set (BSS) that may enable devices to transparently move from one participating AP to another participating AP (e.g., mesh). For example, in a home mesh network, a Wi-Fi device may connect to any of the APs, but typically selects the one with good signal strength. The coverage footprints of mesh APs are generally overlapping, often placing each device within range or more than one AP. If an AP supports multi-band (e.g., 2.4 GHz and 5 GHz), the wireless sensing system may instruct the device to remain connected to the same physical AP, but to use different frequency bands to obtain more diverse information to help improve the accuracy or results of the wireless sensing algorithm (e.g., motion detection algorithm). In some implementations, the wireless sensing system may change the device from being connected to one mesh AP to being connected to another mesh AP. Such device steering can be performed, for example, during wireless sensing (e.g., motion detection) based on criteria detected in a particular area to improve detection coverage or to better localize motion within the area.

[0049] In some cases, the wireless sensing system may enable devices to dynamically indicate and communicate their wireless sensing capabilities or willingness to the wireless sensing system. For example, a device may not want to be periodically interrupted or triggered to communicate wireless signals that may enable an AP to generate channel measurements. For example, if a device is asleep, waking the device frequently to transmit or receive wireless sensing signals may consume resources (e.g., draining a cell phone battery faster). These and other events may cause a device to be willing or unwilling to participate in the operation of the wireless sensing system. In some cases, a cell phone running on its battery may not want to participate, but may be willing to participate when the cell phone is plugged into a charger. Thus, if the cell phone is not plugged in, it may indicate to the wireless sensing system to exclude the cell phone from participating, whereas if the cell phone is plugged in, it may indicate to the wireless sensing system to include the cell phone in the operation of the wireless sensing system. In some cases, if a device is under load (e.g., a device streaming audio or video) or is in the middle of performing a primary function, the device may not want to join; if the load on that same device is reduced and joining would not interfere with the primary function, the device can indicate to the wireless detection system that it is willing to join.

[0050] An exemplary wireless sensing system is described below in the context of motion detection (detection of object movement in space, motion tracking, respiration detection, respiration monitoring, presence detection, gesture detection, gesture recognition, human detection (moving human detection 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, gait rate 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, the operation, system improvements, and technical advantages achieved when the wireless sensing system is operating as a motion detection system are also applicable in instances where the wireless sensing system is used for another type of wireless sensing application.

[0051] As disclosed in the embodiments herein, a wireless local area network (WLAN) detection procedure enables a station (STA) to perform WLAN detection. The WLAN detection may include a WLAN detection session. In examples, the WLAN detection procedure, the WLAN detection, and the WLAN detection session may be referred to as a wireless detection procedure, a wireless detection, a wireless detection session, a Wi-Fi detection procedure, a Wi-Fi detection, and a Wi-Fi detection session, or a detection procedure, a detection, and a detection session.

[0052] WLAN sensing is a service that allows a STA to obtain sensing measurements of a channel between two or more STAs and / or a channel between a receive antenna and a transmit antenna of a STA or an access point (AP). A WLAN sensing procedure may consist of one or more of sensing session setup, sensing measurement setup, sensing measurement case, sensing measurement setup termination, and sensing session termination.

[0053] In the examples disclosed herein, sensing session setup and sensing measurement setup may be referred to as sensing configuration and may be accomplished by a sensing configuration message and may be confirmed by a sensing configuration response message. A sensing measurement instance may be an individual sensing measurement and may be derived from a sensing transmission. For example, a sensing configuration message may be referred to as a sensing measurement setup request and a sensing configuration response message may be referred to as a sensing measurement setup response.

[0054] A WLAN sensing procedure may include multiple sensing measurement instances, eg, the multiple sensing measurement instances may be referred to as a measurement campaign.

[0055] IEEE P802.11-REVmd / D5.0 considers an STA to be a physical (PHY) and medium access controller (MAC) entity capable of supporting features defined by the standard. A device that includes a STA may be referred to as a Wi-Fi device. A Wi-Fi device that manages a basic service set (BSS) (as defined by IEEE P802.11-REVmd / D5.0) may be referred to as an AP STA. A Wi-Fi device that is a client node in a BSS may be referred to as a non-AP STA. In some examples, an AP STA may be referred to as an AP and a non-AP STA may be referred to as a STA.

[0056] In various embodiments of the present disclosure, non-limiting definitions of one or more terms used herein are provided below.

[0057] The term "steady-state propagation channel" may refer to the channel between a sensing receiver and a sensing transmitter, which is defined and affected only by the physical sensing space and does not take into account any perturbations due to transient objects or motion.

[0058] The term "measurement campaign" may refer to a series of sensing transmissions in both directions between a sensing receiver (commonly known as a Wi-Fi device, wireless access point, Wi-Fi access point, access point, Wi-Fi station, station, sensing initiator, sensing responder, or sensing receiver) and a sensing transmitter (commonly known as a Wi-Fi device, wireless access point, Wi-Fi access point, access point, Wi-Fi station, station, sensing initiator, sensing responder, or sensing transmitter).

[0059] The term "sensing initiator" may refer to a STA or AP that initiates a Wi-Fi sensing procedure. A STA acting as a sensing initiator may participate in a sensing measurement instance as a sensing receiver, a sensing transmitter, both a sensing transmitter and a sensing receiver, or neither a sensing transmitter nor a sensing receiver, or as a separate device that includes a sensing algorithm (e.g., a sensing algorithm manager). In some examples, a sensing initiator may be a device that initiates a WLAN sensing session. In one example, a sensing initiator may include a Wi-Fi sensing agent that executes a sensing algorithm. In one example, a sensing initiator may be considered to control a WLAN sensing procedure or a measurement campaign.

[0060] The term "sensing responder" may refer to a STA or AP that participates in a WLAN sensing procedure initiated by a sensing initiator. A STA acting as a sensing responder may participate in a sensing measurement instance as a sensing receiver, a sensing transmitter, or both a sensing receiver and a sensing transmitter.

[0061] The term "sensing transmitter" may refer to a STA or AP that transmits a PPY layer protocol data unit (PPDU), which is a sensing transmission used to sense measurements in a WLAN sensing session.

[0062] The term "sensing receiver" may refer to a STA or AP that receives the PPDU sent by a sensing transmitter in a WLAN sensing procedure and performs sensing measurements.

[0063] For example, a sensing transmitter may be referred to as a remote device and a sensing receiver may be referred to as a sensing device. In other examples, a sensing initiator may be a function of a sensing device or a remote device, and a sensing responder may be a function of a sensing device or a remote device.

[0064] The term "wireless local area network (WLAN) sensing session" may refer to a period of time during which objects in a physical space may be probed, detected, and / or characterized. In one example, during a WLAN sensing session, multiple devices participate and thereby contribute to the generation of sensing measurements. A WLAN sensing session may be controlled by a sensing initiator.

[0065] The term "PHY layer protocol data unit (PPDU)" may refer to a data unit that includes a preamble and a data field. The preamble field may include transmission vector format information, and the data field may include a payload and an upper layer header.

[0066] The term "Channel State Information (CSI)" can describe how a wireless signal propagates from a transmitter to a receiver along multiple paths. CSI is typically a matrix of complex values ​​that represents the amplitude attenuation and phase shift of a signal, providing an estimate of the communication channel.

[0067] The term "sensing space" may refer to any physical space in which a Wi-Fi sensing system may operate.

[0068] The term "sensing initiation message" may refer to a message sent from a sensing initiator (which may be a sensing receiver) to a sensing transmitter to initiate one or more sensing transmissions that may be used to perform sensing measurements. A sensing initiation message may also be known as a sensing trigger message in some examples.

[0069] The term "sensing transmission" may refer to any transmission from a sensing transmitter to a sensing receiver that may be used to perform sensing measurements. In one example, a sensing transmission may be referred to as a wireless sensing signal or a wireless signal. For example, a PPDU used for sensing measurements may be referred to as a sensing transmission.

[0070] 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 that may be used to perform sensing measurements. In an example, the sensing trigger message may include a requested transmission configuration, a requested timing configuration, and / or a steering matrix configuration. In an example, the term sensing trigger message may be referred to as a sensing sounding trigger message or a sensing sounding trigger frame.

[0071] The term "detection transmission announcement" may refer to a message sent from a detection transmitter to a detection receiver announcing that a detection transmission NDP follows in a short interframe space (SIFS). The detection transmission NDP may be transmitted using transmission parameters defined along with the detection transmission announcement.

[0072] The term "detection transmission NDP" may refer to an NDP (Null Data PPDU) transmission sent by a detection transmitter and used for detection measurements at a detection receiver. The transmission may follow a detection transmission announcement and be sent using the transmission parameters defined in a detection response announcement.

[0073] The term "sensing measurement" may refer to a measurement of the conditions of the propagation channel between a sensing transmitter and a sensing receiver.

[0074] The term "Channel Representation Information (CRI)" may refer to a collection of sensed measurements that together represent the condition of the propagation channel between two devices. Examples of CRI are CSI and full TD-CRI.

[0075] The term "sensing measurement poll" may refer to a message sent from a sensing initiator or, for example, from a sensing transmitter to a sensing receiver to request the transmission of channel representation information determined by the sensing receiver.

[0076] The term "transmit parameters" may refer to a set of IEEE 802.11 PHY transmitter configuration parameters that are defined as part of a transmit vector (TXVECTOR) corresponding to a particular PHY and are configurable for each PHY layer protocol data unit (PPDU) transmission.

[0077] The term "full time-domain channel representation information (full TD-CRI)" may refer to a series of complex pairs of time-domain pulses created by performing an inverse fast Fourier transform (IFFT) on CSI values, e.g., CSI computed by a baseband receiver.

[0078] The term "filtered time-domain channel representation information (filtered TD-CRI)" may refer to a reduced series of complex pairs of time-domain pulses created by applying an algorithm to the full TD-CRI. The algorithm may select some time-domain pulses and reject others. The filtered TD-CRI includes information relating the selected time-domain pulses to the corresponding time-domain pulses in the full TD-CRI.

[0079] The term "Channel Response Information (CRI) transmission message" may refer to a message sent by a sensing receiver that has performed sensing measurements on a sensing transmission, and the sensing receiver sends the CRI to a sensing initiator or a sensing algorithm manager.

[0080] The term "reconstructed CSI (R-CSI)" may refer to a representation of the original CSI values ​​measured by a baseband receiver, where the R-CSI is calculated by taking the original CSI values ​​(frequency domain), performing an IFFT to transform them to the time domain, selecting a number of time-domain pulses, zeroing or nulling the time-domain tones that do not contain the selected time-domain pulses, and performing an FFT. The resulting frequency-domain complex value is the R-CSI.

[0081] The term "time-domain pulse" may refer to a complex number that represents the amplitude and phase of discretized energy in the time domain. Once the CSI values ​​are obtained for each tone from the baseband receiver, the time-domain pulse is obtained by performing an IFFT on the CSI values.

[0082] 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 be referred to as a symbol. In the frequency domain, a tone may be referred to as a subcarrier.

[0083] The term "feature of interest" may refer to an item or condition of an item that is positively detected and / or identified by a detection algorithm.

[0084] The term "sensing imprint" may refer to a steady-state or semi-stationary representation of the propagation channel between a sensing receiver and a sensing transmitter in a sensing space, computed by the sensing receiver, in the form of a time-domain channel impulse response.

[0085] The term "delivered transmit configuration" may refer to the transmit parameters applied by the sensing transmitter to the sensing transmitter.

[0086] The term "requested transmit configuration" may refer to the requested transmit parameters of a sensing transmitter to be used when sending a sensing transmission.

[0087] The term “imprint delta” may refer to a complex-valued, single-dimensional matrix that represents the difference between the time-domain channel impulse response generated by transforming the CSI measurements to the time domain using an IFFT and the stored detection imprint.

[0088] The term "measurement imprint delta threshold" may refer to the minimum difference between a TD-CRI value and a corresponding detection imprint value at which a detection receiver or detection algorithm manager considers there to be a change in the propagation channel propagation characteristics.

[0089] The term "measurement imprint delta count" may refer to the number of times a measurement imprint delta threshold is exceeded before a sensing receiver or sensing algorithm manager considers there to be a change in the propagation channel propagation characteristics.

[0090] The term “imprint delta derivative period” may refer to the period of time that the imprint delta derivative must remain below the imprint delta derivative threshold before the detection receiver or detection algorithm manager determines that a new detection imprint needs to be calculated.

[0091] The term "imprint delta derivative" may refer to the rate of change of the imprint delta across one or more tones and across one or more frames.

[0092] The term "imprint delta derivative threshold" may refer to a maximum value of the rate imprint delta derivative at which the sensing receiver or sensing algorithm manager considers there to be ongoing movement or motion in the sensing space. If the imprint delta derivative falls below the imprint delta derivative threshold, the sensing receiver or sensing algorithm manager may determine that a new sensing imprint needs to be calculated.

[0093] The term "imprint validity timer" for a sensing imprint may indicate when the validity period of that sensing imprint expires. In an example, when the imprint validity timer of a given sensing imprint expires, the sensing imprint is recalculated. In one example, the duration of the imprint validity timer may be configured by the sensing algorithm manager.

[0094] The term "steady state imprint delta threshold" may refer to the maximum difference between a TD-CRI value and a corresponding detection imprint value at which the detection receiver or detection algorithm manager considers the TD-CRI has not returned to its steady state (i.e., the stored detection imprint).

[0095] The term "steady-state imprint delta period" may refer to the period during which the imprint delta should be below the steady-state imprint delta threshold if the detection receiver or detection algorithm manager considers the TD-CRI to have returned to its steady state.

[0096] The term "imprint validity period" may refer to the maximum period of validity of a sensing imprint.

[0097] The term "sensing imprint average count" may refer to multiple sensing measurements that may be averaged to generate a sensing imprint.

[0098] In reading the following description of the various embodiments, the following description of the sections of this specification and their respective contents may be useful.

[0099] Section A describes wireless communication systems, wireless transmissions, and sensing measurements that may be useful in practicing the embodiments described herein.

[0100] Section B describes embodiments of systems and methods for Wi-Fi sensing. In particular, Section B describes Wi-Fi systems and methods for generating a dynamic time-domain channel representation for Wi-Fi sensing.

[0101] A. Wireless Communication Systems, Wireless Transmission, and Sensing Measurements 1 illustrates a wireless communication system 100. 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 example 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.).

[0102] The wireless communication devices 102A, 102B, 102C can operate in a wireless network, for example, according to a wireless network standard or another type of wireless communication protocol. For example, the wireless network can 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 according to one or more of the 802.11 family of standards developed by the IEEE (e.g., Wi-Fi networks), etc. Examples of PANs include networks that operate according to short-range communication standards (e.g., BLUETOOTH, Near Field Communications (NFC), ZigBee), millimeter wave communication, and others.

[0103] In some implementations, the wireless communication devices 102A, 102B, 102C may be configured to communicate within a cellular network, for example, according to a cellular network standard. Examples of cellular networks include networks configured according to 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), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), 4G standards such as Long-Term Evolution (LTE) and LTE-Advanced (LTE-A), 5G standards, and others.

[0104] In the example shown in FIG. 1, 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 access points or another type of wireless access point (WAP) that implements one or more operations described herein embedded as instructions (e.g., software or firmware) on the WAP's modem. In some cases, the wireless communication devices 102A, 102B, 102C may be nodes of a wireless mesh network, such as, for example, a commercially available mesh network system (e.g., Plume Wi-Fi, Google Wi-Fi, Qualcomm Wi-Fi SoN, 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 the mesh network, while other wireless communication devices 102A, 102B, 102C are 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 is a mobile device (e.g., a smartphone, a smart watch, a tablet, a laptop computer, etc.), a wireless-enabled device (e.g., a smart thermostat, a Wi-Fi enabled camera, a smart TV), or another type of device that communicates in a wireless network.

[0105] The wireless communication devices 102A, 102B, 102C may be implemented without a Wi-Fi component, e.g., 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 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 either a hub device or a beacon device in the motion detection system.

[0106] 1, the wireless communication device 102C includes a modem 112, a processor 114, a memory 116, and a power unit 118, and any of the wireless communication devices 102A, 102B, 102C in the wireless communication system 100 may include the same, additional, or different components, and the components may be configured to operate as shown in FIG. 1 or in another manner. In some implementations, the modem 112, the processor 114, the memory 116, and the power unit 118 of the wireless communication device are housed together in a common housing or other assembly. In some implementations, one or more of the components of the wireless communication device may be housed separately, for example, in a separate housing or other assembly.

[0107] The modem 112 can communicate (receive, transmit, or both) wireless signals. For example, the modem 112 can be configured to communicate radio frequency (RF) signals formatted according to a wireless communication standard (e.g., Wi-Fi or Bluetooth). The modem 112 can be implemented as the example wireless network modem 112 shown in FIG. 1 or can be implemented otherwise, e.g., with other types of components or subsystems. In some implementations, the modem 112 includes a radio subsystem and a baseband subsystem. In some cases, the baseband subsystem and the radio subsystem can be implemented on a common chip or chipset, or they can be implemented in a card or another type of assembled device. The baseband subsystem can be coupled to the radio subsystem, e.g., by leads, pins, wires, or other types of connections.

[0108] In some cases, the radio subsystem in the modem 112 can include one or more antennas and radio frequency circuitry. The radio frequency circuitry can include, for example, circuitry for filtering, amplifying, or otherwise conditioning analog signals, circuitry for upconverting baseband signals to RF signals, circuitry for downconverting RF signals to baseband signals, etc. Such circuitry can include, for example, filters, amplifiers, mixers, local oscillators, etc. The radio subsystem can be configured to transmit radio frequency wireless signals over a wireless communication channel. As an example, the radio subsystem can include a radio chip, an RF front end, and one or more antennas. The radio subsystem can include additional or different components. In some implementations, the radio subsystem can be or include radio electronics (e.g., RF front end, radio chip, or similar components) from a conventional modem, e.g., a Wi-Fi modem, a pico base station modem, etc. In some implementations, the antenna includes multiple antennas.

[0109] In some cases, the baseband subsystem in the modem 112 may include digital electronics configured to process, for example, 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 for operating the radio subsystem, communicating wireless network traffic via the radio subsystem, detecting motion based on motion detection signals received via the radio subsystem, or performing other types of processing. For example, the baseband subsystem may include one or more chips, chipsets, or other types of devices configured to encode signals, deliver the encoded signals to the radio subsystem for transmission, or identify and analyze encoded data in signals from the radio subsystem (e.g., by decoding the signals according to a wireless communication standard, by processing the signals according to a motion detection process, or otherwise).

[0110] In some cases, the radio subsystem in modem 112 receives baseband signals from the baseband subsystem, upconverts the baseband signals in frequency (radio frequency (RF) signals, and transmits the radio frequency signals wirelessly (e.g., through an antenna). In some cases, the radio subsystem in modem 112 receives radio frequency signals wirelessly (e.g., through an antenna), downconverts the radio frequency signals to baseband signals, and sends the baseband signals to the baseband subsystem. Signals exchanged between the radio subsystem and the baseband subsystem may be digital signals or analog signals. In some examples, the baseband subsystem includes conversion circuitry (e.g., digital-to-analog converters, analog-to-digital converters) and exchanges analog signals with the radio subsystem. In some examples, the radio subsystem includes conversion circuitry (e.g., digital-to-analog converters, analog-to-digital converters) and exchanges digital signals with the baseband subsystem.

[0111] In some cases, the baseband subsystem of the modem 112 can communicate wireless network traffic (e.g., data packets) in a wireless communication network through the radio subsystem over one or more network traffic channels. The baseband subsystem of the modem 112 can also transmit or receive (or both) signals (e.g., motion search signals or motion detection signals) through the radio subsystem over a dedicated wireless communication channel. In some cases, the baseband subsystem generates a motion search signal for transmission, for example, to search a space for motion. In some cases, the baseband subsystem processes a received motion detection signal (a signal based on the motion search signal transmitted through the space), for example, to detect the motion of an object in the space.

[0112] The processor 114 may execute instructions, for example, to generate output data based on data input. The instructions may include programs, codes, scripts, or other types of data stored in memory. Additionally or alternatively, the instructions may be encoded as preprogrammed or reprogrammable logic circuits, logic gates, or other types of hardware or firmware components. The processor 114 may be or include a general-purpose microprocessor, as a dedicated coprocessor or another type of data processing device. In some cases, the processor 114 performs high-level operations of the wireless communication device 102C. For example, the processor 114 may be configured to execute or interpret software, scripts, programs, functions, executable files, or other instructions stored in the memory 116. In some implementations, the processor 114 may be included in the modem 112.

[0113] The memory 116 may include a computer-readable storage medium, such as a volatile memory device, a non-volatile memory device, 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 with or otherwise associated with another component of the wireless communication device 102C. The memory 116 may store instructions executable by the processor 114. For example, the instructions may include instructions for time aligning signals using an interference buffer and a motion detection buffer through one or more of the operations of an example process such as those described in any of Figures 17A, 17B, 18, 19A, 19B, 20, and 21.

[0114] 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 power provided by the power supply unit 118 through a voltage bus or other connection. In some implementations, the power supply unit 118 includes a battery or battery system, e.g., a rechargeable battery. In some implementations, the power supply unit 118 includes an adapter (e.g., an AC adapter) that receives an external power signal (from an external source) and converts the external power signal into an internal power signal conditioned for the components of the wireless communication device 102C. The power supply unit 118 may include other components or operate in another manner.

[0115] 1, the wireless communication devices 102A, 102B transmit wireless signals (e.g., in accordance with a wireless network standard, a motion detection protocol, or other method). For example, the wireless communication devices 102A, 102B may broadcast wireless motion detection signals (e.g., reference signals, beacon signals, status signals, etc.) or may send wireless signals addressed to other devices (e.g., user equipment, client devices, servers, etc.), and other devices (not shown) as well as the wireless communication device 102C may receive the wireless signals transmitted by the wireless communication devices 102A, 102B. In some cases, the wireless signals transmitted by the wireless communication devices 102A, 102B are repeated periodically, e.g., in accordance with a wireless communication standard or otherwise.

[0116] In the illustrated example, the wireless communication device 102C processes wireless signals from the wireless communication devices 102A, 102B to detect motion of objects in a space accessed by the wireless signals, determine a location of the detected motion, or both. For example, the wireless communication device 102C may perform one or more of the exemplary processes described below with respect to any of FIG. 17A, FIG. 17B, FIG. 18, FIG. 19A, FIG. 19B, FIG. 20, and FIG. 21, or another type of processing to determine a location of the detected motion. The space accessed by the wireless signals may be, for example, an indoor or outdoor space that may include one or more fully or partially enclosed areas, open areas without enclosures, etc. The space may be or may include an interior of a room, multiple rooms, a building, etc. In some cases, the wireless communication system 100 may be modified such that, for example, the wireless communication device 102C can transmit wireless signals and the wireless communication devices 102A, 102B can process wireless signals from the wireless communication device 102C to detect motion or determine a location of the detected motion.

[0117] The wireless signals used for motion detection may include, for example, beacon signals (e.g., Bluetooth beacons, Wi-Fi beacons, other wireless beacon signals), other standard signals generated for other purposes according to a wireless network standard, or non-standard signals (e.g., random signals, reference signals, etc.) generated for motion detection or other purposes. In examples, motion detection may be performed by analyzing one or more training fields carried by the wireless signals, or by analyzing other data carried by the signals. In some examples, data is added or used for the explicit purpose of motion detection, or data that is nominally for another purpose is reused or used for motion detection. In some examples, the wireless signals propagate through objects (e.g., walls) before or after interacting with a moving object, thereby allowing the movement of the moving object to be detected even without an optical line of sight between the moving object and the transmitting or receiving hardware. Based on the received signals, the wireless communication device 102C may generate motion detection data. In some cases, the wireless communication device 102C may communicate 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.

[0118] In some implementations, the wireless communication devices 102A, 102B may be modified to transmit a motion probing signal (which may include, for example, a reference signal, a beacon signal, or another signal used to probe the space for motion) on a wireless communication channel (e.g., a frequency channel or a coded channel) separate from the wireless network traffic signals. For example, the modulation applied to the payload of the motion probing signal and the type of data or data structure within the payload may be known by the wireless communication device 102C, thereby reducing the amount of processing the wireless communication device 102C performs for motion detection. The header may include additional information, such as, for example, an indication of whether motion has been detected by another device in the communication system 100, an indication of the modulation type, an identification of the device transmitting the signal, etc.

[0119] 1, the wireless communication system 100 is a wireless mesh network having wireless communication links between each of the wireless communication devices 102. In the illustrated example, the wireless communication link between the wireless communication device 102C and the wireless communication device 102A can be used to probe 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 probe 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 probe the motion detection field 110C. In some cases, each wireless communication device 102 detects motion within the motion detection field 110 accessed by that device by processing a received signal based on a wireless signal transmitted by the wireless communication device 102 via the motion detection field 110. 1 moves in motion detection field 110A and motion detection field 110C, the wireless communication devices 102 can detect the motion based on signals they receive that are based on wireless signals transmitted through the respective motion detection fields 110. For example, wireless communication device 102A can detect the motion of person 106 in motion detection fields 110A, 110C, wireless communication device 102B can detect the motion of person 106 in motion detection field 110C, and wireless communication device 102C can detect the motion of person 106 in motion detection field 110A.

[0120] In some cases, the motion detection field 110 may include, for example, air, solid material, liquid, or another medium through which wireless electromagnetic signals may propagate. In the example shown in FIG. 1, the motion detection field 110A provides a wireless communication channel between the wireless communication device 102A and the wireless communication device 102C, the motion detection field 110B provides a wireless communication channel between the wireless communication device 102B and the wireless communication device 102C, and the motion detection field 110C provides a wireless communication channel between the wireless communication device 102A and the wireless communication device 102B. In some aspects of operation, wireless signals transmitted on a wireless communication channel (either separate from or shared with the wireless communication channel for network traffic) are used to detect the movement of objects in space. The objects may be any type of stationary or movable object, animate or inanimate. For example, the object may be a human (e.g., person 106 shown in FIG. 1), an animal, an inanimate object, or another device, apparatus, or assembly), an object that defines all or a portion of a boundary of a space (e.g., a wall, a door, a window, etc.), or another type of object. In some implementations, the motion information from the wireless communication devices may be analyzed to determine a location of the detected motion. For example, as described further 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 in the vicinity of a particular wireless communication device.

[0121] 2A and 2B are diagrams illustrating example wireless signals communicated between wireless communication devices 204A, 204B, 204C. The wireless communication devices 204A, 204B, 204C may be, for example, wireless communication devices 102A, 102B, 102C shown in FIG. 1, or other types of wireless communication devices. The wireless communication devices 204A, 204B, 204C transmit wireless signals through a space 200. The space 200 may be fully or partially enclosed with one or more boundaries, or may be open. The space 200 may be within or may include a room, multiple rooms, a building, an indoor area, an outdoor area, etc. A first wall 202A, a second wall 202B, and a third wall 202C at least partially surround the space 200 in the illustrated example.

[0122] 2A and 2B, the wireless communication device 204A is operable to transmit a wireless signal repeatedly (e.g., periodically, intermittently, at scheduled, unscheduled, or random intervals, etc.). The wireless communication devices 204B, 204C are operable to receive a signal based on the signal transmitted by the wireless communication device 204A. The wireless communication devices 204B, 204C each have a modem (e.g., modem 112 shown in FIG. 1) configured to process the received signal to detect movement of an object in the space 200.

[0123] As shown, the object is at a first position 214A in Figure 2A, and the object has moved to a second position 214B in Figure 2B. In Figures 2A and 2B, the moving object in the space 200 is depicted as a human, but the moving object may be another type of object. For example, the moving object may be an animal, an inanimate object (e.g., a system, device, apparatus, or assembly), an object that defines all or part of the boundary of the space 200 (e.g., a wall, a door, a window, etc.), or another type of object.

[0124] 2A and 2B, multiple example paths of a wireless signal transmitted from a wireless communication device 204A are illustrated with dashed lines. Along a first signal path 216, the wireless signal is transmitted from the wireless communication device 204A and reflected from a first wall 202A toward the wireless communication device 204B. Along a second signal path 218, the wireless signal is transmitted from the wireless communication device 204A and reflected from a second wall 202B and the first wall 202A toward the wireless communication device 204C. Along a third signal path 220, the wireless signal is transmitted from the wireless communication device 204A and reflected from the second wall 202B toward the wireless communication device 204C. Along a fourth signal path 222, the wireless signal is transmitted from the wireless communication device 204A and reflected from a third wall 202C toward the wireless communication device 204B.

[0125] In FIG. 2A, along the fifth signal path 224A, the wireless signal is transmitted from the wireless communication device 204A and is reflected from an object at the first position 214A toward the wireless communication device 204C. Between FIG. 2A and FIG. 2B, the surface of the object moves from the first position 214A in the space 200 to the second position 214B (e.g., a distance away from the first position 214A). In FIG. 2B, along the sixth signal path 224B, the wireless signal is transmitted from the wireless communication device 204A and is reflected from an object at the second position 214B toward the wireless communication device 204C. The sixth signal path 224B depicted in FIG. 2B is longer than the fifth signal path 224A depicted in FIG. 2A due to the movement of the object from the first position 214A to the second position 214B. In some examples, the signal paths can be added, removed, or otherwise modified due to the movement of the object in the space.

[0126] 2A and 2B may be subject to attenuation, frequency shift, phase shift, or other effects along their respective paths, and may have portions that propagate in different directions through the first, second, and third walls 202A, 202B, and 202C, for example. In some examples, the wireless signals are radio frequency (RF) signals. The wireless signals may include other types of signals.

[0127] In the example shown in Figures 2A and 2B, the wireless communication device 204A may repeatedly transmit a wireless signal. In particular, Figure 2A shows a wireless signal being transmitted from the wireless communication device 204A at a first time, and Figure 2B shows the same wireless signal being transmitted from the wireless communication device 204A at a second, later time. The transmit signal may be transmitted continuously, periodically, at random or intermittent times, etc., or combinations thereof. The transmit signal may have multiple frequency components within a frequency bandwidth. The transmit signal may be transmitted from the wireless communication device 204A omnidirectionally, directional, or otherwise. In the illustrated example, the wireless signal traverses multiple respective paths in the space 200, and the signal along each path may be attenuated due to path loss, scattering, reflections, etc., and may have a phase or frequency offset.

[0128] As shown in FIG. 2A and FIG. 2B, signals from the first through sixth paths 216, 218, 220, 222, 224A, and 224B combine at the wireless communication device 204C and the wireless communication device 204B to form a received signal. Due to the effect of multiple paths in the space 200 on the transmitted signal, the space 200 may be represented as a transfer function (e.g., a filter) where the transmitted signal is input and the received signal is output. When an object moves in the space 200, the attenuation or phase offset affecting the signals in the signal paths may change, and thus the transfer function of the space 200 may change. Assuming the same wireless signal is transmitted from the wireless communication device 204A, if the transfer function of the space 200 changes, the output of that transfer function (the received signal) will also change. The change in the received signal can be used to detect the movement of the object.

[0129] Mathematically, the transmit signal f(t) transmitted from the first wireless communication device 204A may be described according to equation (1).

number

[0130] In the formula, ω n represents the frequency of the nth frequency component of the transmitted signal, and c n where f(t) is the complex coefficient of the n-th frequency component, and t is time. If the transmitted signal f(t) is transmitted from the first wireless communication device 204A, the output signal r from path k is k (t) can be written according to equation (2).

number

[0131] In the formula, α n、k represents the attenuation coefficient (or channel response, e.g., due to scattering, reflection, and path loss) for the nth frequency component along path k, and φ n、krepresents the phase of the signal for the nth frequency component along path k. The signal R received at the wireless communication device is then multiplied by the total output signals r from all paths to the wireless communication device, as shown in equation (3). k (t) can be written as the sum of

number

[0132] By substituting equation (2) into equation (3), we obtain the following equation (4).

number

[0133] The received signal R at the wireless communication device may then be analyzed. The received signal R at the wireless communication device may be transformed into the frequency domain, for example, using a Fast Fourier Transform (FFT) or another type of algorithm. The transformed signal may represent the received signal R as a series of n complex values, one complex value for each frequency component (n frequencies ω n ) corresponds to each of the frequencies ω n For the frequency components of n can be expressed in equation (5) as follows:

number

[0134] For a given frequency component ω n Complex value H for n is the frequency component ω n , and the relative magnitude and phase offset of the received signal at n , k Since changes, the complex value H nchanges. Thus, a detected change in the channel response can indicate the movement of an object in the communication channel. In some cases, noise, interference, or other phenomena can affect the channel response detected by the receiver, and the motion detection system can reduce or isolate such effects to improve the accuracy and quality of the motion detection capability. In some implementations, the overall channel response can be expressed in equation (6) as follows:

number

[0135] In some cases, the spatial channel response h ch can be determined, for example, based on a mathematical theory of estimation. For example, the reference signal R ef is the candidate channel response (h ch ), and then the maximum likelihood approach can be applied to the received signal (R cvd ) can be used to select the candidate channel that best matches the estimated received signal

number

number

number

[0136] Using the optimization criterion

number

[0137] Minimizing or optimizing the processing can utilize adaptive filtering techniques such as least mean squares (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 equation, the received signal can be considered as a convolution of a reference signal and a channel response. The convolution operation means that the channel coefficients have some correlation with each of the delayed replicas of the reference signal. Thus, the convolution operation shown in the above equation indicates that the received signal appears at different delay points, and each delayed replica is weighted by a channel coefficient.

[0138] 3A-3B are plots illustrating example channel responses 360, 370 calculated from wireless signals communicated between wireless communication devices 204A, 204B, 204C of FIGS. 2A-2B. FIGS. 3A-3B also show a frequency domain representation 350 of an initial wireless signal transmitted by wireless communication device 204A. In the illustrated example, channel response 360 ​​in FIG. 3A represents a signal received by wireless communication device 204B when there is no motion in space 200, and channel response 370 in FIG. 3B represents a signal received by wireless communication device 204B in FIG. 2B after an object has moved in space 200.

[0139] In the example shown in FIGS. 3A-3B, for illustrative purposes, the wireless communication device 204A transmits a signal having a flat frequency profile (the magnitude of each frequency component f1, f2, and f3 is the same), as shown in the frequency domain representation 350. Due to the interaction of the signal with the space 200 (and objects therein), the signal received at the wireless communication device 204B based on the signal sent from the wireless communication device 204A appears different from the transmitted signal. In this example, where the transmitted signal has a flat frequency profile, the received signal represents the channel response of the space 200. As shown in FIGS. 3A-3B, the channel responses 360, 370 are different from the frequency domain representation 350 of the transmitted signal. When motion occurs in the space 200, variations in the channel response also occur. For example, as shown in FIG. 3B, the channel response 370 associated with the motion of objects in the space 200 is different from the channel response 360 ​​associated with no motion in the space 200.

[0140] Furthermore, as an object moves within the space 200, the channel response may vary from the channel response 370. In some cases, the space 200 may be divided into distinct regions, and the channel responses associated with each region may share one or more characteristics (e.g., shape), as described below. Thus, the motion of objects within different distinct regions may be distinguished, and the location of the detected motion may be determined based on an analysis of the channel responses.

[0141] 4A-4B are diagrams illustrating example channel responses 401, 403 associated with the movement of an object 406 in distinct regions of a space 400, a first region 408 and a third region 412. In the illustrated example, the space 400 is a building, and the space 400 is divided into multiple distinct regions, namely, a first region 408, a second region 410, a third region 412, a fourth region 414, and a fifth region 416. The space 400 may include additional or fewer regions in some cases. As shown in FIGS. 4A-4B, the regions in the space 400 may be defined by walls between rooms. In addition, the regions may be defined by ceilings between floors of a building. For example, the space 400 may include additional floors having additional rooms. In addition, in some cases, the multiple regions of the space may be or include multiple floors in a high-rise building, multiple rooms in a building, or multiple rooms on a particular floor of a building. In the example shown in FIG. 4A, the object located in the first area 408 is represented as a person 106, although the moving object may be another type of object, such as an animal or an inanimate object.

[0142] In the illustrated example, the wireless communication device 402A is located in a fourth region 414 of the space 400, the wireless communication device 402B is located in a second region 410 of the space 400, and the wireless communication device 402C is located in a fifth region 416 of the space 400. The wireless communication device 402 may operate in the same or similar manner as the wireless communication device 102 of FIG. 1. For example, 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 a motion probing signal through the space 400 and receive a signal based on the motion probing signal. The wireless communication device 402 may analyze the received signals to detect whether an object has moved in the space 400, such as by analyzing a channel response associated with the space 400 based on the received signals. Additionally, in some implementations, the wireless communication device 402 may analyze the received signals to identify a location of the detected motion in the space 400. For example, the wireless communication device 402 may analyze characteristics of the channel response to determine whether the channel response shares the same or similar characteristics as channel responses known to be associated with the first region 408 through the fifth region 416 of the space 400.

[0143] In the illustrated example, one (or more) of the wireless communication devices 402 repeatedly transmits a motion search signal (e.g., a reference signal) through the space 400. The motion search signal may have a flat frequency profile in some cases, with magnitudes of each frequency component f1, f2, and f3. For example, the motion search signal may have a frequency response similar to the frequency domain representation 350 shown in FIGS. 3A-3B. The motion search signal may have a different frequency profile in some cases. Due to the interaction of the reference signal with the space 400 (and objects therein), a signal received at another wireless communication device 402 based on a motion search signal transmitted from the other wireless communication device 402 differs from the transmitted reference signal.

[0144] Based on the received signals, the wireless communication device 402 can determine a channel response for the space 400. When motion occurs in distinct regions in the space, distinct characteristics may be seen in the channel response. For example, the channel response may be slightly different for motion in the same region of the space 400, but the channel responses associated with motion in distinct regions may generally share the same shape or other characteristics. For example, the channel response 401 in FIG. 4A represents an exemplary channel response associated with motion of an object 406 in a first region 408 of the space 400, and the channel response 403 in FIG. 4B represents an exemplary channel response associated with motion of an object 406 in a 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.

[0145] 4C-4D are plots showing the channel responses 401, 403 of FIGS. 4A-4B superimposed on a channel response 460 associated with no motion occurring in the space 400. In the illustrated example, the wireless communication device 402 transmits a motion probing signal having a flat frequency profile as shown in the frequency domain representation 450. When motion occurs in the space 400, a variation in the channel response occurs relative to the channel response 460 associated with no motion, and thus, by analyzing the variation in the channel response, motion of an object in the space 400 can be detected. In addition, the relative location of the detected motion in the space 400 can be identified. For example, the shape of the channel response associated with the motion can be compared to reference information (e.g., using a trained AI model) to classify the motion as occurring in a distinct region of the space 400.

[0146] When there is no motion in the space 400 (e.g., no object 406 is present), the wireless communication device 402 may calculate a channel response 460 associated with no motion. Although multiple factors may cause slight variations in the channel response, multiple channel responses 460 associated with different time periods may share one or more characteristics. In the example shown, the motionless channel response 460 has a decreasing frequency profile (the magnitude of each frequency component f1, f2, and f3 is smaller than the previous one). The profile of the channel response 460 may differ in some cases (e.g., based on different room layouts or placements of the wireless communication device 402).

[0147] When motion occurs in the space 400, variations in the channel response occur. For example, in the example shown in Figures 4C-4D, the channel response 401 associated with the motion of the object 406 in the first region 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 region 412 is different from the channel response 460 associated with no motion. The channel response 401 has a concave parabolic frequency profile (the magnitude of the mid-frequency component f2 is smaller than the outer frequency components f1 and f3), and the channel response 403 has a convex asymptotic frequency profile (the magnitude of the mid-frequency component f2 is larger than the outer frequency components f1 and f3). The profiles of the channel responses 401, 403 may differ in some cases (e.g., based on different room layouts or placement of the wireless communication device 402).

[0148] Analyzing a channel response can be considered to be similar to analyzing a digital filter. In other words, the channel response is formed through the reflection of objects in space and the reflections created by a moving or stationary human. When a reflector (e.g., a human) moves, the channel response changes. This can be translated into a change in the equivalent taps of a digital filter that 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 location of its peaks and troughs, and the channel response can be characterized by its peaks and troughs as well. For example, in some implementations, the nulls and peaks in the frequency components of the channel response can be analyzed (e.g., by marking their location on the frequency axis and their magnitude) to detect motion.

[0149] In some implementations, time series aggregation can be used to detect motion. Time series aggregation can be performed by observing the characteristics of the channel response over a moving window and aggregating the windowed results by using statistical measures (e.g., mean, variance, principal components, etc.). During the motion case, the characteristic digital filter features are displaced in terms of location and flip-flop between some values ​​due to the continuous changes of the scattering scene. That is, the equivalent digital filter shows a range of values ​​for its peaks and nulls (due to motion). By looking at this range of values, a unique profile (in some instances the profile is also referred to as a signature) can be identified for distinct regions in the space.

[0150] In some implementations, artificial intelligence (AI) models can be used to process the 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 aim to learn a function that provides the most accurate correlation between input and output values ​​and is trained using a past set of inputs and outputs that are known to be correlated. For example, artificial intelligence is sometimes referred to as machine learning.

[0151] In some implementations, a profile of channel response associated with movement in distinct regions of the space 400 may be learned. For example, machine learning may be used to categorize channel response characteristics with movement of objects in distinct regions of the space. In some cases, a user associated with the wireless communication device 402 (e.g., an owner or other occupant of the space 400) may assist in the learning process. For example, with reference to the example shown in FIGS. 4A-4B, a user may move through each of the first through fifth regions 408, 410, 412, 414, 416 during the learning phase and may indicate (e.g., via a user interface on a mobile computing device) that they are moving in one of the particular regions in the space 400. For example, while the user is moving through the first region 408 (e.g., as shown in FIG. 4A), the user may indicate on the mobile computing device that they are in the first region 408 (and may label the region as a "bedroom," "living room," "kitchen," or another type of room in the building, as appropriate). The channel response may be obtained as the user moves through the region, and the channel response may be "tagged" with the user's indicated location (region). The user may repeat the same process for other regions of the space 400. The term "tagged" as used herein may refer to marking and identifying the channel response with the user's indicated location or any other information.

[0152] The tagged channel response can then be processed (e.g., by machine learning software) to identify unique characteristics of the channel response associated with motion in the distinct regions. Once the unique characteristics are identified, the identified unique characteristics can be used to determine the location of the detected motion for the newly calculated channel response. For example, an AI model can be trained using the tagged channel response, and once trained, the newly calculated channel response can be input into the AI ​​model, which can output the location of the detected motion. For example, in some cases, the mean, range, and absolute values ​​are input into the AI ​​model. In some cases, the magnitude and phase of the complex channel response itself can also be input. These values ​​allow the AI ​​model to design any front-end filters to pick up the features most relevant to making accurate predictions regarding motion in the distinct regions of space. In some implementations, the AI ​​model is trained by performing stochastic gradient descent. For example, channel response variations that are most active during a particular zone can be monitored during training, and certain channel variations can be weighted heavily (by training and adapting weights in the first layer to correlate with their shape, trend, etc.). The weighted channel variation can be used to create a metric that activates when a user is within a particular region.

[0153] For extracted features such as channel response nulls and peaks, a time series (of nulls / peaks) can be created using aggregation in a moving window, taking snapshots of some features in the past and present, and using the aggregated values ​​as input to the network. Thus, the network may try to aggregate values ​​in a particular region to cluster them while adapting its weights, which can be done by creating a decision surface based on a logistic classifier. The decision surface divides the different clusters, and subsequent layers can form categories based on a single cluster or a combination of clusters.

[0154] In some implementations, the AI ​​model includes two or more layers of inference. The first layer acts as a logistic classifier that can divide values ​​of different cardinality into separate clusters, and the second layer combines some of these clusters together to create categories for separate regions. Further, subsequent layers can facilitate the extension of the separate regions across two or more categories of clusters. For example, a fully connected input layer model may include an AI corresponding to the number of tracked features, an intermediate layer corresponding to the number of valid clusters (through iterations between selections), and a final layer corresponding to the different regions. If complete channel response information is input to the AI ​​model, the first layer may act as a shape filter that can correlate specific shapes. Thus, the first layer may lock onto specific shapes, the second layer may generate a measure of the variations occurring in those shapes, and the third and subsequent layers may create combinations of those variations and map them to different regions in space. The outputs of the different layers may then be combined through a fusion layer.

[0155] B. SYSTEMS AND METHODS FOR DYNAMIC TIME DOMAIN CHANNEL REPRESENTATION FIELD OF THE DISCLOSURE The present disclosure relates generally to systems and methods for Wi-Fi sensing, and more particularly to configuring a Wi-Fi system and method for generating a dynamic time domain channel representation for Wi-Fi sensing.

[0156] The disclosed system and method exploits the physics of the relationship between the time domain and the frequency domain (Fourier relationship). In a propagation channel impulse response between two devices (such as a sensing receiver and a sensing transmitter), reflections in the physical environment may be represented in the time domain by changes in only a few time domain pulses, especially when the reflections are caused by objects that are not very close to one device or another. However, in the frequency domain, the effects of these reflections are reflected across all channel state information (CSI) values ​​of the propagation channel bandwidth.

[0157] FIG. 5 illustrates a portion of the architecture of an implementation of a system 500 for Wi-Fi detection, according to some embodiments.

[0158] The system 500 (alternatively referred to as Wi-Fi sensing system 500) may include multiple sensing receivers 502-(1-K), multiple sensing transmitters 504-(1-M), a sensing algorithm manager 506, and a network 560 that enables communication between system components for information exchange. 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 cellular network connection, details of which are provided with reference to FIG. 1 and the accompanying description. The following description is described with reference to the sensing receiver 502-1 and the sensing transmitter 504-1 for purposes of simplicity and should not be construed as limiting.

[0159] According to some embodiments, the sensing receiver 502-1 may be configured to receive sensing transmissions and perform one or more sensing measurements useful for Wi-Fi sensing. These measurements may be known as sensing measurements. The sensing measurements may be processed to achieve the sensing goal of the system 500. In one embodiment, the sensing receiver 502-1 may be an access point (AP). In some embodiments, the sensing receiver 502-1 may be a station (STA), for example, in a mesh network scenario. According to one implementation, the sensing receiver 502-1 may be implemented by a device such as the wireless communication device 102 shown in FIG. 1. In some implementations, the sensing receiver 502-1 may be implemented by a device such as the wireless communication device 204 shown in FIG. 2A and FIG. 2B. The sensing receiver 502-1 may be implemented by a device such as the wireless communication device 402 shown in FIG. 4A and FIG. 4B. In one implementation, the sensing receiver 502-1 may coordinate and control communication between multiple sensing transmitters 504-(1-M). According to one implementation, the sensing receiver 502-1 may be enabled to control the measurement campaign to ensure that necessary sensing transmissions occur at the necessary times and to ensure that sensing measurements are accurately determined. In some embodiments, the sensing receiver 502-1 may process the sensing measurements to achieve the sensing goals of the system 500. In some embodiments, the sensing receiver 502-1 may be configured to transmit the sensing measurements to the sensing algorithm manager 506, which may be configured to process the sensing measurements to achieve the sensing goals of the system 500.

[0160] According to one implementation, the sensing receiver 502-1 may initiate a WLAN sensing session, and the multiple sensing transmitters 504-(1-M) may join the WLAN session initiated by the sensing receiver 502-1. In some implementations, the multiple sensing transmitters 504-(1-M) may transmit PPDUs used to sense measurements in the WLAN sensing session. In one implementation, the sensing receiver 502-1 may receive PPDUs in the WLAN sensing session and process the PPDUs into sensing measurements.

[0161] Referring again to FIG. 5, in some embodiments, the detection transmitter 504-1 may be configured to send a detection transmission to the detection receiver 502-1 based on which one or more detection measurements may be performed for Wi-Fi detection. In one embodiment, the detection transmitter 504-1 may be a STA. In some embodiments, the detection transmitter 504-1 may be an AP for Wi-Fi detection, for example, in a scenario in which the detection receiver 502-1 serves as a STA. According to one implementation, the detection transmitter 504-1 may be implemented by a device such as the wireless communication device 102 shown in FIG. 1. In some implementations, the detection transmitter 504-1 may be implemented by a device such as the wireless communication device 204 shown in FIG. 2A and FIG. 2B. Furthermore, the detection transmitter 504-1 may be implemented by a device such as the wireless communication device 402 shown in FIG. 4A and FIG. 4B. In some implementations, communication between the sensing receiver 502-1 and the sensing transmitter 504-1 may occur via Station Management Entity (SME) and MAC Layer Management Entity (MLME) protocols.

[0162] According to some embodiments, the detection algorithm manager 506 may be configured to receive detection measurements from the detection receiver 502-1 and process the detection measurements to achieve the detection goal of the system 500. In one example, the detection algorithm manager 506 may process and analyze the detection measurements to achieve the detection goal of detecting motion and / or movement. According to some implementations, the detection algorithm manager 506 may include / execute a detection algorithm. The detection algorithm may be a computational algorithm that achieves the detection goal. In one example, the detection algorithm may utilize channel representation information (CRI) to achieve the detection goal of detecting movement and / or movement. In one embodiment, the detection algorithm manager 506 may be implemented in a STA. In some embodiments, the detection algorithm manager 506 may be implemented in an AP. According to one implementation, the detection algorithm manager 506 may be implemented by a device such as the wireless communication device 102 shown in FIG. 1. In some implementations, the detection algorithm manager 506 may be implemented by a device such as the wireless communication device 204 shown in FIG. 2A and FIG. 2B. Further, the detection algorithm manager 506 may be implemented by a device such as the wireless communication device 402 shown in FIG. 4A and FIG. 4B. In some embodiments, the detection algorithm manager 506 may be any computing device such as a desktop computer, a laptop, a tablet computer, a mobile device, a personal digital assistant (PDA), or any other computing device. In an embodiment, the detection algorithm manager 506 may act as a detection initiator where the detection algorithm determines the measurement campaign and the detection measurements required to satisfy the measurement campaign. The detection algorithm manager 506 may communicate the detection measurements required to satisfy the measurement campaign to the detection receiver 502-1 to coordinate and control communication between the multiple detection transmitters 504-(1-M).Although the detection algorithm manager 506 is described as being a separate device, in some implementations, the detection algorithm manager 506 may be implemented within the detection transmitter 504-1.

[0163] 5, in more detail, the sensing receiver 502-1 may include a processor 508-1 and a memory 510-1. For example, as shown in FIG. 1, the processor 508-1 and memory 510-1 of the sensing receiver 502-1 may be the processor 114 and the memory 116, respectively. In one embodiment, the 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 both transmit and receive signals in a half-duplex format. When an antenna is transmitting, it may be referred to as a transmitting antenna 512-1, and when an antenna is receiving, it may be referred to as a receiving antenna 514-1. It will be understood by those skilled 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, one or more antenna elements may be used to transmit or receive a signal, for example, in a beamforming environment. In some examples, a group of antenna elements used to transmit a composite signal may be referred to as a transmit antenna 512-1, and a group of antenna elements used to receive a composite signal may be referred to as a receive antenna 514-1. In some examples, each antenna has its own transmit and receive paths, which may be alternately switched to connect to the antenna depending on whether the antenna is operating as a transmit antenna 512-1 or a receive antenna 514-1.

[0164] In one implementation, the sensing agent 516-1 may be responsible for receiving the sensing transmission and associated transmission parameters and calculating the sensing measurements for the purpose of Wi-Fi sensing. In some implementations, receiving the sensing transmission and associated transmission parameters and calculating the sensing measurements may be performed by an algorithm running at a medium access control (MAC) layer of the sensing receiver 502-1. In one implementation, the sensing agent 516-1 may be configured to cause at least one transmit antenna of the transmit antennas 512-1 to transmit a message to the sensing transmitter 504-1. In one example, the sensing agent 516-1 may be configured to receive a message from the sensing transmitter 504-1 via at least one receive antenna of the receive antennas 514-1. In one example, the sensing agent 516-1 may be configured to perform sensing measurements based on the sensing transmissions received from the sensing transmitter 504-1.

[0165] In some embodiments, the detector receiver 502-1 may include a detector imprint storage 518-1, a channel representation information storage 520-1, and an imprint delta storage 522-1. The detector imprint storage 518-1 may store information related to one or more detector imprints. The channel representation information storage 520-1 may store information related to a detector measurement value representing a state of a channel between the detector receiver 502-1 and each of the multiple detector transmitters 504-(1-M). In one example, the channel representation information storage 520 may store one or more of channel state information (CSI), a full TD-CRI, and a filtered TD-CRI. The imprint delta storage 522-1 may store information related to a difference between the full TD-CRI and the detector imprint as an imprint delta. The information about one or more sensed imprints stored in the sensed imprint storage device 518-1, the information about sensed measurements stored in the channel representation information storage device 520-1, and the information about imprint deltas stored in the imprint delta storage device 522-1 may be updated periodically or dynamically as needed. In one implementation, the sensed imprint storage device 518-1, the channel representation information storage device 520-1, and the imprint delta storage device 522-1 may include any type or form of storage device, such as a database or file system, or coupled to the memory 510-1.

[0166] Referring again to FIG. 5, the 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 sensing transmitter 504-1 may be the processor 114 and the memory 116, respectively, as shown in FIG. 1. In one embodiment, the sensing transmitter 504-1 may further include a transmit antenna 532-1, a receive antenna 534-1, and a sensing agent 536-1. In one implementation, the sensing agent 536-1 may be a block that passes physical and MAC layer parameters from the MAC of the sensing transmitter 504-1 to an application layer program. The sensing agent 536-1 may be configured to cause at least one transmit antenna of the transmit antennas 532-1 and at least one receive antenna of the receive antennas 534-1 to exchange messages with the sensing receiver 502-1. In some embodiments, the antennas may be used to both transmit and receive in a half-duplex format. When an antenna is transmitting, it may be referred to as a transmitting antenna 532-1, and when an antenna is receiving, it may be referred to as a receiving antenna 534-1. It will be understood by those skilled in the art that the same antenna may be a transmitting antenna 532-1 in some cases and a receiving antenna 534-1 in other cases. In the case of an antenna array, one or more antenna elements may be used to transmit or receive signals, for example, in a beamforming environment. In some examples, a group of antenna elements used to transmit a composite signal may be referred to as a transmitting antenna 532-1, and a group of antenna elements used to receive a composite signal may be referred to as a receiving antenna 534-1. In some examples, each antenna has its own transmit and receive paths, which may be alternately switched to connect to the antenna depending on whether the antenna is operating as a transmitting antenna 532-1 or a receiving antenna 534-1.

[0167] According to one or more implementations, communications in network 560 may be governed by one or more of the 802.11 family of standards developed by the IEEE. Some example IEEE standards may include IEEE 802.11ax, IEEE 802.11md, and IEEE 802.11-REVmd / D5.0. IEEE 802.11ax and IEEE 802.11md are part of the IEEE 802.11-2016 WLAN standard. IEEE 802.11md is a new release of the standard that includes previous amendments. Additionally, IEEE 802.11ax is an addition to the IEEE 802.11-2016 standard. In some implementations, communications may be governed by other standards (other or additional IEEE standards or other types of standards). In some embodiments, portions of network 560 that do not require system 500 to be governed by one or more of the 802.11 family of standards may be implemented by instances of any type of network, including wireless networks or cellular networks.

[0168] Referring again to FIG. 5, in one implementation, the detection receiver 502-1 may initiate a measurement campaign. According to an exemplary implementation, the detection receiver 502-1 may initiate a measurement campaign via one or more detection initiation messages. In one implementation, the detection agent 516-1 may be configured to generate the detection initiation message. In one example, the detection initiation message may include a requested transmission configuration. Other examples of information / data included in the detection initiation message not discussed herein are contemplated herein. In one implementation, the detection agent 516-1 may transmit a detection initiation message to the detection transmitter 504-1 via the transmit antenna 512-1.

[0169] According to one implementation, the detection transmitter 504-1 may receive a detection initiation message from the detection receiver 502-1 via the receive antenna 534-1. In one implementation, the detection agent 536-1 may apply the requested transmission configuration included in the detection initiation message. The detection agent 536-1 may then transmit a detection transmission to the detection receiver 502-1 according to the requested transmission configuration in response to the detection initiation message. In one implementation, the detection agent 536-1 may be configured to transmit the detection transmission to the detection receiver 502-1 via the transmit antenna 532-1.

[0170] In one implementation, the sensing receiver 502-1 may receive a sensing transmission from the sensing transmitter 504-1 transmitted in response to the sensing initiation message. The sensing receiver 502-1 may be configured to receive the sensing transmission from the sensing transmitter 504-1 via the receiving antenna 514-1. According to one implementation, the sensing agent 516-1 may be configured to process the sensing transmission to determine one or more sensing imprints. In one example, the one or more sensing imprints may be a steady-state or baseline representation of a time-domain impulse response of a propagation channel between the sensing transmitter 504-1 and the sensing receiver 502-1. In an aspect, the sensing receiver 502-1 and the sensing transmitter 504-1 may be in a steady state, and objects between the sensing receiver 502-1 and the sensing transmitter 504-1 may be in a semi-stationary state. For example, objects such as furniture or fixtures in a room may not move much and thus are in a semi-static state. Thus, the propagation channel between the sensing transmitter 504-1 and the sensing receiver 502-1 may be in a semi-static or stationary state (ie, the propagation channel may be devoid of any movement or motion).In the following, a method for determining the sensing imprint will be described.

[0171] According to one implementation, the baseband receiver of the detecting receiver 502-1 may be configured to calculate the CSI based on the detected transmission. In some implementations, the detecting receiver 502-1 may calculate the contribution to the CSI by the receiver chain. In one example, the receiver chain of the detecting receiver 502-1 may include analog and digital elements. For example, the receiver chain may include analog and digital components where the received signal may move from a reference point to a point where the received signal may be read, i.e., by the detecting agent 516-1 of the detecting receiver 502-1. A representation 600 of the receiver chain of the detecting receiver 502-1 is illustrated in FIG. 6. As depicted in FIG. 6, in-phase (I) and quadrature (Q) modulated symbols arrive at the front end of the receiver where synchronization including frequency and timing recovery is performed. Furthermore, the time domain guard period (cyclic prefix) is removed, and the receiver performs a fast Fourier transform (FFT) on the received signal (e.g., I and Q modulation symbols). The guard tones and DC tones are then removed. The CSI is then generated prior to data demapping, deinterleaving (using a deinterleaver), depuncturing, decoding (using a Viterbi decoder), and finally descrambling (using a descrambler). As a result of the descrambling, data bits are generated. The generated CSI is provided to the detection agent 516-1.

[0172] According to one implementation, upon receiving the CSI, the sensing agent 516-1 may determine a sensing imprint of the propagation channel in the format of a full time domain channel representation information (TD-CRI). The sensing agent 516-1 may perform an inverse fast Fourier transform (IFFT) on the CSI to determine the sensing imprint. This results in a time domain representation of the CSI. The sensing imprint may include complex values ​​for each time domain tone. In one example, the sensing imprint may include as many full TD-CRI values ​​as there are CSI values. The number of CSI values ​​may be scaled with the propagation channel bandwidth. In one implementation, the number of CSI values, and therefore the number of full TD-CRI values ​​in the sensing imprint, may be represented by Equation (1) provided below.

number

[0173] In one implementation, the sensing agent 516-1 may store the sensing imprint in the sensing imprint storage device 518-1. In one example, the sensing agent 516-1 may store the sensing imprint as a baseline at the time of the propagation channel. In some implementations, the sensing transmitter 504-1 may send one or more sensing transmissions to the sensing receiver 502-1 with different delivered transmission configurations. In such implementations, the sensing receiver 502-1 may determine and store a sensing imprint of the propagation channel associated with each delivered transmission configuration.

[0174] According to one implementation, the sensing imprint may be measured by the sensing receiver 502-1 based on one or more sensing transmissions. In one example, the measurements may be made in one or both directions of the propagation channel, i.e., one or more sensing transmissions may be sent in one direction and the sensing imprint may be measured and stored for that transmission direction. In some examples, another one or more sensing transmissions may be sent in the opposite direction and the sensing imprint may be measured and stored for that transmission direction. In one implementation, the sensing imprint may be measured and stored in the time domain. In one example, the sensing imprint may be measured multiple times with multiple sensing transmissions and these measurements may be averaged to generate the sensing imprint.

[0175] According to one implementation, the sensing imprint stored in the sensing imprint storage device 518-1 may be updated periodically or dynamically as needed. In one example, if there is a change in the semi-static nature of one or more propagation channels between the sensing receiver 502-1 and the sensing transmitter 504-1, the sensing imprint may need to be recalculated or updated. For example, if one or both of the sensing receiver 502-1 and the sensing transmitter 504-1 move, or if a semi-static object (e.g., a piece of furniture) between the sensing receiver 502-1 and the sensing transmitter 504-1 moves, there may be a change in the semi-static nature of the propagation channel. In some examples, the sensing imprint may also need to be updated in cases where the sensing receiver 502-1 detects that an object moves into the sensing space that affects the propagation channel, remains there for a period of time, and remains stationary. In one implementation, the baseband receiver may send a notification to the sensing receiver 502-1 that the sensing imprint associated with one or more propagation channels needs to be updated.

[0176] In some implementations, an automatic gain control (AGC) in the baseband receiver (e.g., block "Front End Sync" in FIG. 6) may precondition the I and Q samples before digitization. The AGC is a dynamic process and its gain may change over time depending on conditions in the propagation channel. In some examples, a measure of the change in the AGC gain, or a signal from the AGC indicating that the gain has changed significantly, may inform the detection receiver 502-1 that it needs to update the detection imprint associated with one or more propagation channels.

[0177] Although the sensing receiver 502-1 is described as determining and storing a sensing imprint representing a semi-static or steady-state propagation channel between the sensing receiver 502-1 and the sensing transmitter 504-1, in some implementations, the sensing receiver 502-1 may determine and store a sensing imprint representing a semi-static or steady-state propagation channel between the sensing receiver 502-1 and the sensing transmitter 504-(2-M). The sensing receiver 502-1 may also store an identifier (ID) associated with each sensing transmitter to uniquely identify each sensing transmitter and the corresponding sensing imprint. Examples of the sensing transmitter ID may include a MAC ID, an association ID, or any distinct identifier. Furthermore, the sensing receiver 502-1 may store multiple sensing imprints for each sensing transmitter 504-(1-M), and in one example, each sensing imprint may be distinguished by a transmitted transmission configuration or another distinct identifier. An exemplary data structure for detecting imprints stored in detection receiver 502-1 is shown in Table 1 provided below. [Table 1]

[0178] In one example, the imprint creation time of a sensing imprint may refer to the time when the sensing imprint is recorded / determined and stored in the sensing receiver 502-1. For example, the imprint creation time may be the value of a system clock or counter that may be used to determine the validity deadline of the sensing imprint.

[0179] According to some implementations, the detection receiver 502-1 may send a copy of the stored detection imprint representing a semi-static or steady-state propagation channel between the detection receiver 502-1 and the multiple detection transmitters 504-(1-M) to the detection algorithm manager 506. In one implementation, each of the multiple detection receivers 502-(2-K) may also be configured to determine a detection imprint and send a copy of the detection imprint to the detection algorithm manager 506. Thus, the detection algorithm manager 506 may store copies of the detection imprint for multiple detection receiver and detection transmitter pairs, and optionally for multiple delivered transmission configurations per detection receiver detection transmitter pair. In one example, the detection algorithm manager 506 may store copies of the detection imprint locally in a data storage device. An exemplary data structure for detecting imprints stored by the detection algorithm manager 506 is shown in Table 2 provided below. [Table 2-1] [Table 2-2] [Table 2-3]

[0180] Referring back to FIG. 5, according to one or more implementations, for purposes of Wi-Fi detection, the detection receiver 502-1 may initiate a measurement campaign (or Wi-Fi detection session). The measurement campaign may involve an exchange of transmissions between the detection receiver 502-1 and the detection transmitter 504-1. In one example, control of these transmissions may be by the MAC layer of the IEEE 802.11 stack. According to an exemplary implementation, the detection receiver 502-1 may initiate the measurement campaign via one or more detection initiation messages. In one implementation, the detection agent 516-1 may be configured to generate the detection initiation messages. According to one implementation, the detection agent 516-1 may transmit the detection initiation messages to the detection transmitter 504-1 via the transmit antenna 512-1.

[0181] According to one implementation, the detection transmitter 504-1 may receive a detection initiation message from the detection receiver 502-1 via the receive antenna 534-1. In one implementation, the detection agent 536-1 may apply the requested transmission configuration included in the detection initiation message. The detection agent 536-1 may then transmit a detection transmission to the detection receiver 502-1 in response to the detection initiation message and according to the requested transmission configuration. In one example, the detection transmission may include the delivered transmission configuration. In one implementation, the detection agent 536-1 may be configured to transmit a detection transmission to the detection receiver 502-1 via the transmit antenna 532-1.

[0182] In one implementation, the sensing receiver 502-1 may receive a sensing transmission from the sensing transmitter 504-1 transmitted in response to the sensing initiation message. The sensing receiver 502-1 may be configured to receive the sensing transmission from the sensing transmitter 504-1 via the receiving antenna 514-1. According to one implementation, the sensing agent 516-1 may be configured to generate sensing measurements based on the sensing transmission. The sensing agent 516-1 may then generate a full TD-CRI of the propagation channel between the sensing receiver 502-1 and the sensing transmitter 504-1 based on the sensing measurements. In one implementation, upon receiving the sensing transmission, the baseband receiver of the sensing receiver 502-1 may calculate the CSI and pass the CSI from the PHY to the MAC layer. The MAC layer may then convert the CSI to the full TD-CRI using an IFFT.

[0183] In one example, the detection algorithm manager 506 may send a request for high fidelity TD-CRI reconstruction to the detection receiver 502-1. Here, high fidelity TD-CRI reconstruction means that the resulting TD-CRI reconstruction does not show any loss of fidelity of the propagation channel during measurement. In one example, this high fidelity TD-CRI reconstruction may be referred to as lossless, which means that it does not lose the fidelity of the propagation channel. According to one implementation, the detection agent 516-1 may select a time domain compression technique as needed. For example, the detection agent 516-1 may use a lossy or lossless time domain compression technique depending on the detection application requirements and use cases. In one example, the lossy time domain compression may require less calculations compared to the lossless time domain compression because there is no need to perform subtraction between the full TD-CRI and the detection imprint. Therefore, it may be preferable for the detection algorithm manager 506 to request the use of a lossy time domain compression technique when a loss of fidelity is acceptable.

[0184] According to one implementation, the sensing agent 516-1 may obtain a sensing imprint representing a steady-state propagation channel between the sensing receiver 502-1 and the sensing transmitter 504-1. In one implementation, the sensing agent 516-1 may obtain a sensing imprint representing a steady-state propagation channel between the sensing receiver 502-1 and the sensing transmitter 504-1 by retrieving the sensing imprint from the sensing imprint storage device 518-1. In one example, the obtained sensing imprint may be a previously recorded sensing imprint measured on one or more sensing transmissions from the sensing transmitter 504-1 using the same transmitted transmission configuration.

[0185] Upon obtaining the detection imprint, the detection agent 516-1 may compare the full TD-CRI to the detection imprint. According to one implementation, the detection agent 516-1 may compare the full TD-CRI to the detection imprint in response to a request from the detection algorithm manager 506. In one implementation, the detection algorithm manager 506 may indicate to the detection receiver 502-1 the required fidelity of the detection measurement based on, for example, the detection application requirements and use case.

[0186] In some implementations, there may be situations where either lossless or lossy time domain compression techniques are preferred over the other. In one example, if the detection goal of the detection algorithm manager 506 is to detect motion anywhere in the surrounding area, the lossy time domain compression technique may be sufficient to provide the necessary information. In some examples, if the detection goal of the detection algorithm manager 506 is to detect fine-grained motion features, such as the direction of motion or the ability to track where the motion is occurring in the propagation channel, the detection algorithm manager 506 may request a lossless update of the propagation channel so that all available information can be applied to the detection. According to some examples, the decision regarding the reconstruction technique may be influenced by the range of the object from the detection receiver 502-1 or the detection transmitter 504-1. If the detection goal of the detection algorithm manager 506 is to detect motion when the disturbance (or motion) is close to the detection receiver 502-1 or the detection transmitter 504-1, the lossy time domain compression technique may be sufficient to detect the disturbance. However, if the detection algorithm manager 506 requires an expanded area of ​​coverage where it is sensitive to slight interference occurring on the periphery of the propagation channel, then lossy time domain compression techniques may be required to detect the interference.

[0187] According to one implementation, based on the comparison of the full TD-CRI and the detection imprint, the detection agent 516-1 may identify a filtered TD-CRI according to the difference between the full TD-CRI and the detection imprint. In one implementation, the detection agent 516-1 may determine a set of time-domain pulses of the full TD-CRI that are different from the corresponding time-domain pulses of the detection imprint, and designate the set of time-domain pulses of the full TD-CRI as the filtered TD-CRI. According to one implementation, the detection agent 516-1 may only identify those differences between the time-domain pulses of the full TD-CRI and the time-domain pulses of the detection imprint that exceed a measurement imprint delta threshold. In one implementation, the measurement imprint delta threshold may be equal to or greater than a threshold at which the time-domain pulses of the full TD-CRI are considered to be different from the time-domain pulses of the detection imprint. In one example, the measurement imprint delta threshold may be defined in terms of an amplitude threshold or a phase threshold, or a combination of both an amplitude threshold and a phase threshold.

[0188] According to one implementation, the sensing agent 516-1 may determine the difference between the full TD-CRI and the sensing imprint based on calculating the difference between the full TD-CRI and the sensing imprint for each time-domain pulse by phase subtraction. In one example, the difference between each time-domain pulse of the full TD-CRI and the sensing imprint may be expressed in terms of an amplitude difference or a phase difference, or a combination of both amplitude and phase differences. In some examples, the difference between each time-domain pulse of the full TD-CRI and the sensing imprint may be expressed as a phase and amplitude transformation (i.e., phase rotation and amplitude scaling). In some examples, the difference between each time-domain pulse of the full TD-CRI and the sensing imprint may be expressed as a combination of expressions such as amplitude difference and phase rotation.

[0189] FIG. 7 illustrates an example 700 of phasor subtraction according to some embodiments. In FIG. 7, Re is the real axis and Im is the imaginary axis. In the example of FIG. 7, phasor 2 is subtracted from phasor 1. As described in FIG. 7, the amplitude and phase of phasor 1 are represented by R1 and α, respectively, and the amplitude and phase of phasor 2 are represented by R2 and β, respectively. Furthermore, the amplitude and phase of the difference between phasor 1 and phasor 2 are represented by R3 and γ. FIG. 8 illustrates an example 800 of phase rotation, amplitude scaling, and amplitude difference after phase rotation. In FIG. 8, Re is the real axis and Im is the imaginary axis. As described in FIG. 8, the phase difference between phasor 1 and phasor 2 is θ, and the scaling factor between the amplitudes of phasor 1 and phasor 2 is a.

[0190] 5, according to one implementation, the sensing agent 516-1 may store a set of time domain pulses of the full TD-CRI constituting the filtered TD-CRI in the imprint delta storage 522-1 as an imprint delta defining the filtered TD-CRI as a difference between the set of time domain pulses of the full TD-CRI and the corresponding time domain pulses of the sensing imprint. In one implementation, the imprint delta values ​​constituting the filtered TD-CRI may be represented by a numeric format having fewer bits than may be required to represent the complete time domain pulses of the filtered TD-CRI. According to an example, there may be no loss of precision since the range of values ​​being represented is reduced by the difference operation.

[0191] In one implementation, once the imprint delta is obtained, the sensing agent 516-1 may evaluate the imprint delta for each time-domain pulse of the full TD-CRI individually. According to one implementation, the sensing agent 516-1 may compare each time-domain pulse difference (i.e., the difference between the time-domain pulse of the full TD-CRI and the time-domain pulse of the sensing imprint) with a measurement imprint delta threshold for amplitude or phase, or both amplitude and phase. Based on the comparison result, the sensing agent 516-1 may determine that the time-domain pulse of the full TD-CRI has changed. In one example, the sensing agent 516-1 may determine that the time-domain pulse of the full TD-CRI has changed when the measurement imprint delta threshold is exceeded only once. According to one implementation, the measurement imprint delta threshold must be exceeded for a measurement imprint delta count for a subsequent measurement before the time-domain pulse of the full TD-CRI is considered to be different from the time-domain pulse of the sensing imprint. In one example, the measurement imprint delta count may refer to the number of times a measurement imprint delta threshold is exceeded before a time domain pulse of the full TD-CRI is considered different from a time domain pulse of the sensed imprint.

[0192] In one implementation, the measurement imprint delta threshold and the measurement imprint delta count may be configured by sensing receiver 502-1. In some implementations, the measurement imprint delta threshold and the measurement imprint delta count may be configured by sensing algorithm manager 506. According to one implementation, the sensing algorithm manager 506 may send one or more measurement imprint delta thresholds and one or more corresponding measurement imprint delta counts to the sensing receiver 502-1. According to one embodiment, upon initial association of the sensing receiver 502-1 with the sensing algorithm manager 506, the sensing algorithm manager 506 may inform the sensing receiver 502-1 of one or more measurement imprint delta thresholds and one or more corresponding measurement imprint delta counts for use in future Wi-Fi sensing sessions. In one example, one or more measurement imprint delta thresholds may be associated with a particular sensing imprint. For example, the measurement imprint delta threshold may be associated with a sensing imprint for an uplink path between the sensing transmitter 504-1 and the sensing receiver 502-1 in a particular channel bandwidth and for a particular delivered transmission configuration.

[0193] According to one implementation, the detection receiver 502-1 may send the filtered TD-CRI to the detection algorithm manager 506 as a representation of the reflection of the propagation channel between the detection receiver 502-1 and the detection transmitter 504-1 for Wi-Fi detection. In one implementation, the detection agent 516-1 may send the filtered TD-CRI to the detection algorithm manager 506 via a CRI transmission message. In an example implementation, the detection agent 516-1 may send a CRI transmission message including the filtered TD-CRI to the detection algorithm manager 506 via the transmit antenna 512-1. In one example, the filtered TD-CRI may include a time domain pulse of the full TD-CRI to the detection algorithm manager 506 that is determined to have changed from the detection imprint (a time domain pulse of the full TD-CRI that differs from the detection imprint may be sent to the detection algorithm manager 506). In some examples, the filtered TD-CRI may include an imprint delta value representing the time-domain pulse of the full TD-CRI determined to be modified from the detection imprint (the imprint delta of the modified time-domain pulse of the full TD-CRI may be transmitted to the detection algorithm manager 506).

[0194] According to one implementation, the detection agent 516-1 may indicate to the detection algorithm, manager 506, the location of a time-domain pulse within the filtered TD-CRI that represents a reflection in the propagation channel (i.e., a time-domain pulse or a time-domain tone represented by the imprint delta).

[0195] In one implementation, the detection agent 516-1 may send a detection imprint indicator to the detection algorithm manager 506 along with the filtered TD-CRI. In one example, the detection imprint indicator may refer to a version number or a unique identifier of the detection imprint used by the detection receiver 502-1 to calculate the filtered TD-CRI. The unique identifier may be generated based on a combination of identifiers of the detection receiver 502-1, the detection transmitter 504-1, and any of the delivered transmission configurations so that the detection algorithm manager 506 can determine which of multiple possibly stored sensing imprints to use. In some implementations, the detection agent 516-1 may generate and send a cryptographic hash of the detection imprint used by the detection receiver 502-1 to calculate the filtered TD-CRI along with the filtered TD-CRI so that the detection algorithm manager 506 can determine which sensing imprint to use. In one implementation, the detection agent 516-1 may generate the cryptographic hash using a SHA-256 algorithm.

[0196] In one implementation, to avoid using a longer data field than necessary, e.g., a MAC PDU to send the filtered TD-CRI from the detection receiver 502-1 to the detection algorithm manager 506, the filtered TD-CRI time domain pulse or imprint delta value may be placed consecutively in the data message without gaps or nulls between them. However, there may have been gaps between the actual updated or selected full TD-CRI time domain pulses, and therefore the original location of the selected full TD-CRI time domain pulse must be signaled from the detection receiver 502-1 to the detection algorithm manager 506. In one example, the updated or selected full TD-CRI time domain pulse may point to a time domain pulse of the full TD-CRI that is different from the detection imprint.

[0197] According to one implementation, the sensing agent 516-1 may send a location bitmap to the sensing algorithm manager 506 indicating the location of the first time-domain pulse in the full TD-CRI. In one example, the first time-domain pulse may be a series of time-domain pulses from within the full TD-CRI that are altered compared to the sensing imprint and processed by the sensing algorithm manager 506 to determine a current sensing measurement. Thus, each time-domain pulse must be identified to allow a reconstructed full TD-CRI to be generated in the sensing algorithm manager 506 and the sensing measurement to be recreated.

[0198] FIG. 9 illustrates an illustrative diagram 900 of a filtered TD-CRI according to some embodiments. An example of a time domain pulse in the sensing imprint is shown using a solid arrow (represented as “902”), and an example change to the sensing imprint in three time domain pulses is shown using dashed arrows (represented as “904”). For clarity, in the example of FIG. 9, a set of selected full TD-CRI time domain values ​​that are different from the sensing imprint are in a window represented as “906”. In one example, the propagation channel between the sensing receiver 502-1 and the sensing transmitter 504-1 may be 20 MHz in bandwidth and may be represented by 52 complex time domain pulses in the full TD-CRI.

[0199] According to one implementation, the sensing agent 516-1 may create a bitmap of length necessary to represent all time domain pulses carrying data. In one example, the bitmap may be 52 bits long. In another example, the bitmap may be 104 bits long. In one example, the sensing agent 516-1 may populate the bitmap with "1"s where a time domain pulse is selected and present, and "0"s where a time domain pulse is not selected and not present. In one example, the most significant bit (MSB) of the bitmap refers to the first time domain tone and the least significant bit (LSB) of the bitmap refers to the last time domain tone.

[0200] Referring to the example of FIG. 9, a 52-bit long bitmap (or a 52-bit bitfield) is created as follows.

number

[0201] In one implementation, the three updated time domain pulses (magnitude and phase) are transferred sequentially. In one example, the updated time domain pulses may be transferred as values ​​replacing the corresponding values ​​in the sensing imprint. In some examples, the imprint delta may be transferred to be applied as a change to the corresponding values ​​in the sensing imprint. The type of update transferred may be signaled by an additional bit in the bit field. In one example, the value of the additional MSB may represent the type of update transferred. According to one implementation, to take advantage of the possibility of low information content in the bit field, the sensing agent 516-1 may use a lossless data compression algorithm to reduce the number of bits transferred. An example of a lossless data compression algorithm is run-length encoding.

[0202] In one example, the bitmap may be equal to the number of tones in the FFT including guard tones and DC tones, i.e., 64 bits in an example of a 20 MHz propagation channel bandwidth, and 128 bits in an example of a 40 MHz propagation channel bandwidth. In this example, the first number of MSBs is "0", which corresponds to the guard tones, and the second number of LSBs is also "0", which corresponds to the DC tone and the guard tones. According to one implementation, it may be assumed that the MSB of the bitmap maps to the first symbol of the FFT. Based on that assumption, the time domain pulse or imprint delta value may be input according to the bitmap.

[0203] According to some implementations, for each time domain pulse in the filtered TD-CRI, the sensing agent 516-1 may send three values ​​instead of two values, and one of the three values ​​may represent the position of the time domain pulse or the imprint delta value in the full TD-CRI. In one example, the number of bits used to represent the additional value (i.e., the third value) or the size of the additional value may vary depending on the bandwidth of the propagation channel and the number of time domain pulses in the TD-CRI. For example, if the propagation channel bandwidth is 20 MHz and a 64-point FFT is required, the additional value may be 6 bits long. If the propagation channel bandwidth is 40 MHz and a 128-point FFT is required, the additional value may be 7 bits long. In one example, the additional value may precede the value of the time domain pulse or the imprint delta value. In some examples, the additional value may follow the value of the time domain pulse or the imprint delta value.

[0204] In one example, the type of filtered TD-CRI value that is transferred (i.e., that which replaces the corresponding time-domain pulse value in the sensing imprint or that which reflects a change to the corresponding value in the sensing imprint) is signaled by a dedicated type of update field that is transferred along with the value itself.

[0205] FIG. 10 illustrates an example of a set 1000 of modified time-domain pulses in a full TD-CRI (selected time-domain pulses) and FIG. 11 illustrates another example of a set 1100 of modified time-domain pulses in a full TD-CRI (imprint delta), according to some embodiments. In one example, it may be assumed that there is no guard tone or DC tone before the start of the time-domain representation. In both depictions, parameters representing the location of the modified time-domain pulses in the TD-CRI are transferred along with the modified time-domain pulses.

[0206] According to one implementation, the detection algorithm manager 506 may receive the filtered TD-CRI from the detection receiver 502-1. In one example, the filtered TD-CRI may include multiple time domain pulses. In one implementation, the detection algorithm manager 506 may receive a detection imprint indicator along with the filtered TD-CRI. In one example, the detection imprint indicator may refer to a version number or a unique identifier of the detection imprint used by the detection receiver 502-1 to calculate the filtered TD-CRI. In one implementation, the detection algorithm manager 506 may receive a location bitmap indicating the location of the corresponding time domain pulse within the detection imprint. In some implementations, the detection algorithm manager 506 may receive a cryptographic hash of the detection imprint used by the detection receiver 502-1 to calculate the filtered TD-CRI along with the filtered TD-CRI, thereby enabling the detection algorithm manager 506 to determine which detection imprint to use.

[0207] According to one implementation, upon receiving the filtered TD-CRI and the detection imprint indicator and / or the cryptographic hash, the detection algorithm manager 506 may retrieve the detection imprint (or a copy of the detection imprint) from the data storage device according to the detection imprint indicator and / or the cryptographic hash. In one implementation, the detection algorithm manager 506 may generate a reconstructed TD-CRI from the filtered TD-CRI and the detection imprint. According to one implementation, the detection algorithm manager 506 may generate the reconstructed TD-CRI by replacing the corresponding time domain pulse of the detection imprint with the multiple time domain pulses received in the filtered TD-CRI. The detection algorithm manager 506 may then perform an FFT on the resulting time domain signal to obtain a nearly accurate frequency domain CSI. The detection algorithm manager 506 may then detect features of interest in the detection space according to the reconstructed frequency domain channel representation.

[0208] In some implementations, the filtered TD-CRI may include an imprint delta that stores the time-domain pulse difference. Upon receiving the filtered TD-CRI, the detection algorithm manager 506 may generate a reconstructed TD-CRI by adding the time-domain pulse difference to the corresponding time-domain pulse of the detection imprint. In one example, the detection algorithm manager 506 may add the imprint delta to the corresponding time-domain pulse in the detection imprint using phasor addition. The operation of phase addition is opposite to the operation of phase subtraction shown in FIG. 9 and FIG. 10. In one example, if the numerical representation of the imprint delta is modified to reduce the number of bits to transmit, the imprint delta is first cast to the numerical format and resolution of the corresponding time-domain pulse in the stored copy of the detection imprint, thereby allowing the phasor addition to proceed without numerical errors. The detection algorithm manager 506 may then perform an FFT on the resulting time-domain signal to obtain a nearly accurate frequency-domain CSI. The detection algorithm manager 506 may then detect features of interest in the detection space according to the reconstructed frequency-domain channel representation.

[0209] In instances where the detection imprint used to determine the filtered TD-CRI cannot be identified by the detection algorithm manager 506, either by the detection imprint indicator or the cryptographic hash, the time domain pulse or the imprint delta value may be discarded. In some implementations, the detection algorithm manager 506 may send a message to the detection receiver 502-1 to invalidate the stored detection imprint. In some implementations, if the detection imprint used to determine the filtered TD-CRI cannot be identified by the detection algorithm manager 506, either by the detection imprint indicator or the cryptographic hash, and a time domain pulse (rather than an imprint delta value) is sent, the detection algorithm manager 506 may utilize a lossy time domain compression technique instead of a lossless time domain compression technique.

[0210] According to one implementation, the detection imprint used by the detection algorithm manager 506 to calculate the reconstructed TD-CRI or the detection imprint used by the detection receiver 502-1 to calculate the filtered TD-CRI may need to be recalculated or updated in a scenario, for example, where the detection receiver 502-1 detects a moving object in the propagation channel between the detection receiver 502-1 and the detection transmitter 504-1, resulting in an imprint delta between the full TD-CRI and the detection imprint, and then the object that caused this imprint delta stops moving but remains in the detection space. In such a scenario, the baseline detection imprint formed before the object entered the detection space is no longer valid. The imprint delta may change minimally from detection measurement to detection measurement when the object is no longer moving, and therefore there is a repeated transmission of the same or similar information from the detection receiver 502-1 to the detection algorithm manager 506. In such a scenario, a new detection imprint may be determined. In one example, the update of the detection imprint may lead to the creation of a new detection imprint.

[0211] In some implementations, the detection receiver 502-1 or the detection algorithm manager 506 may determine that a new detection imprint is needed based on one or more of the three scenarios provided below: Scenario 1, Scenario 2, and Scenario 3. Other example situations not discussed herein are contemplated herein.

[0212] Scenario 1 In an exemplary implementation, the detection receiver 502-1 or the detection algorithm manager 506 may detect whether a time domain pulse in the full TD-CRI that initially differs from a corresponding time domain pulse in the detection imprint returns to within the steady state imprint delta threshold of the full TD-CRI value in the detection imprint within the steady state imprint delta period. If the detection receiver 502-1 or the detection algorithm manager 506 detects that the changed time domain pulse of the full TD-CRI does not return to within the steady state imprint delta threshold of the detection imprint within the steady state imprint delta period, the detection receiver 502-1 or the detection algorithm manager 506 may determine that the stored detection imprint is no longer valid and should be updated. Thus, the detection receiver 502-1 or the detection algorithm manager 506 may determine that a new detection imprint is needed.

[0213] Scenario 2 In an exemplary implementation, the detection receiver 502-1 or the detection algorithm manager 506 may determine that a new detection imprint is needed when the detection receiver 502-1 or the detection algorithm manager 506 detects that the rate of change of the magnitude and / or phase of the time domain pulse indicative of the imprint delta from the time domain pulse of the detection imprint (i.e., the modified time domain pulse) falls below an imprint delta derivative threshold of an imprint delta derivative term. In one example, the detection receiver 502-1 or the detection algorithm manager 506 may determine that a new detection imprint is needed when the detection receiver 502-1 or the detection algorithm manager 506 determines that the difference between subsequent imprint delta measurements falls below an imprint delta derivative threshold of an imprint delta derivative term. In one example, the imprint delta derivative term may be set to a value to avoid a situation where a moving object is detected and then remains static for a short period of time (i.e., the rate of change of the magnitude and phase of the time domain pulse indicative of the imprint delta from the time domain pulse becomes zero) but then moves again. In such a situation, if the imprint delta derivative period is too short, the sensed imprint may be recalculated if the object is stationary for a short period of time, which is undesirable.

[0214] Scenario 3 In an example implementation, when the detection receiver 502-1 or the detection algorithm manager 506 detects that an imprint validity timer associated with a detection imprint has expired, the detection receiver 502-1 or the detection algorithm manager 506 may determine that a new detection imprint is needed. In one example, the detection imprint may become invalid after an imprint validity period. In one example, the detection algorithm manager 506 may configure the imprint validity period and determine when the imprint validity period expires.

[0215] In one implementation, the detection algorithm manager 506 may configure a steady-state imprint delta threshold, a steady-state imprint delta term, an imprint delta derivative threshold, and an imprint delta derivative term. The detection algorithm manager 506 may send one or more steady-state imprint delta thresholds. In one example, one or more steady-state imprint delta thresholds may be associated with a particular detection imprint. For example, one or more steady-state imprint delta thresholds may be associated with a detection imprint of an uplink path between the detection transmitter 504-1 and the detection receiver 502-1 for a particular delivered transmission configuration.

[0216] In an example implementation, the sensing algorithm manager 506 may configure an imprint delta derivative threshold below which the rate of change of the imprint delta between sensing measurements may be deemed negligible. In one example, the sensing algorithm manager 506 may configure an imprint delta derivative period during which the rate of change of the imprint delta between sensing measurements remains below the threshold.

[0217] According to one implementation, when a new sensing imprint is needed, the sensing receiver 502-1 may generate a new sensing imprint based on sensing transmissions that occur normally and are not specifically requested for the purpose of generating a new sensing imprint. In an example where the sensing imprint includes multiple delivered transmission configuration versions, the sensing receiver 502-1 may update only the version of the sensing imprint that corresponds to the delivered transmission configuration being used. In some examples, the sensing receiver 502-1 may determine that the complete sensing imprint between the sensing receiver 502-1 and the sensing transmitter 504-1 (i.e., for all delivered transmission configurations) is updated. In such a scenario, the sensing receiver 502-1 may request a sensing transmission having the required requested transmission configuration.

[0218] In one implementation, when the sensing receiver 502-1 determines that a new sensing imprint is needed, for example based on scenario 2, the new sensing imprint may be determined to be the channel impulse response at the point where the rate of change of the imprint delta of the time domain pulse falls below the imprint delta derivative threshold for the required imprint delta derivative period. In some examples, the new sensing imprint may be an average of the sensing imprint average count channel impulse response after the rate of change of the imprint delta falls below the imprint delta derivative threshold. In one implementation, the sensing algorithm 506 may configure a sensing imprint average count of the sensing measurements made on the sensing transmissions from the sensing transmitters 504-1 that share a common delivered transmission configuration that are averaged to reduce noise (e.g., measurement noise). The resulting average full TD-CRI may be the sensing imprint of the sensing transmitter 504-1 that generated the delivered transmission configuration and the sensed transmission on which the sensing measurement was made.

[0219] In some implementations, the detection algorithm manager 506 may determine that a new detection imprint is needed and may send a request to the detection receiver 502-1 to create a new detection imprint and send the new detection imprint to the detection algorithm manager 506. In one example, the detection algorithm manager 506 may inform the detection receiver 502-1 that the next X transmissions it receives are detection transmissions, and the detection receiver 502-1 may take detection measurements on each of the detection transmissions and combine these detection measurements together to create a detection imprint. In some implementations, the detection receiver 502-1 may determine that a new detection imprint is needed and may send an announce message regarding the determination to the detection algorithm manager 506. In one example, such a determination may be made when the detection receiver 502-1 detects that an imprint validity timer associated with the detection imprint has expired. In one implementation, once the imprint validity period has expired, the detection receiver 502-1 may process the detection measurements to determine a new detection imprint. In some implementations, the sensing transmitter 504-1 may be required to construct a new series of sensing transmissions to continue the measurement campaign.

[0220] According to one implementation, if it is determined that the sensing receiver 502-1 or the sensing transmitter 504-1 has moved (e.g., based on detection of a complete change in the imprint delta, or due to detection of a power interruption event, or due to a change in the MAC address of the sensing receiver 502-1 or the sensing transmitter 504-1), the sensing algorithm manager 506 may create one or more new sensing imprints for the propagation channel that includes the reconfigured sensing receiver 502-1 or the sensing transmitter 504-1. Additionally, in a situation where a new sensing transmitter is added to the system 500, the sensing algorithm manager 506 may create one or more new sensing imprints for the propagation channel that includes the new sensing transmitter.

[0221] In some implementations, when the detection imprint for a given delivered transmission configuration and a given set of detection transmitters needs to be updated or recalculated, the detection receiver 502-1 may send time domain pulses of all tones to the detection algorithm manager 506. The time domain pulses may include an average of several time domain pulses over several detection transmissions. In one example, when the detection receiver 502-1 calculates a new detection imprint, the detection receiver 502-1 may determine the time domain tones of the updated detection imprint that differ from the time domain tones of the existing detection imprint, and may send only the time domain pulses whose difference is greater than a measurement imprint delta threshold, along with an indication of the location of the time domain pulse within the detection imprint.

[0222] Some embodiments of the present disclosure as described above define detection message types for Wi-Fi detection: detection configuration message, detection configuration response message, delta-CRI message, and detection imprint transmission message.

[0223] In one example, the detection configuration message and the detection configuration response message are carried within a new extension to management frames of the type described in IEEE 802.11. Figure 12 illustrates one example of components of a management frame 1200 carrying a detection transmission. In one example, the system 500 may require an acknowledgement frame and the management frame carrying the detection message may be implemented as an action frame, in another example, the system 500 may not require an acknowledgement frame and the management frame carrying the detection message may be implemented as an Action No Ack frame.

[0224] In one implementation, the information content of all detection message types may be conveyed in a format as shown in Figure 12. In some examples, the transmit configuration, timing configuration, steering matrix configuration, and TD-CRI configuration described in Figure 12 are implemented as IEEE 802.11 elements. In some examples, the TD-CRI components are part of the transmit components.

[0225] In one or more embodiments, according to some embodiments, detection message types may be identified by a message type field, and each detection message type may carry other identified elements. Examples of detection message types and TD-CRI components are shown in Table 3. Details of the TD-CRI components are also shown in Table 4. [Table 3] [Table 4-1] [Table 4-2] [Table 4-3] [Table 4-4] [Table 4-5] [Table 4-6]

[0226] In one example, the data provided in Table 4 may be encoded into elements for inclusion in detection messages between the detection receiver 502-1, the detection transmitter 504-1, and the detection algorithm manager 506. In a measurement campaign that includes multiple detection receivers and multiple detection transmitters, these parameters may be defined for all detection receiver-detection transmitter pairs. In one example, when these parameters are sent from the detection algorithm manager 506 or the detection transmitter 504-1 including the detection algorithm manager 506 to the detection receiver 502-1, these parameters configure the detection receiver 502-1 to process the detection transmission and calculate the detection measurements. In some examples, when these parameters are sent from the detection receiver 502-1 to the detection algorithm manager 506 or the detection transmitter 504-1 including the detection algorithm manager 506, these parameters report the configuration used by the detection receiver 502-1.

[0227] According to some implementations, when the sensing receiver 502-1 has calculated sensing measurements (e.g., in the form of filtered TD-CRI) and created channel representation information, the sensing receiver 502-1 may need to communicate the channel representation information to the sensing algorithm manager 506 or to the sensing transmitter 504-1 that includes the sensing algorithm manager 506. In one example, the sensing measurements may be processed as described to form the channel representation information in the form of a sensing imprint and then an imprint delta.

[0228] In one implementation, a version of the detection imprint is required by the detection algorithm manager 506 to provide a baseline for the filtered TD-CRI. In one example, the detection imprint may be transferred by a management frame, and in one example, a message type may be defined to represent the detection imprint transmission message.

[0229] In one example, the filtered TD-CRI may be forwarded by a management frame. In one example, a message type may be defined to represent a delta CRI message.

[0230] 13 illustrates an example of components of a management frame 1300 carrying a CRI transmission message, according to some embodiments. In one example, the system 500 may require an acknowledgement frame and the management frame carrying the CRI transmission message may be implemented as an Action frame, and in another example, the system 500 may not require an acknowledgement frame and the management frame carrying the CRI transmission message may be implemented as an Action No Ack frame. An example of the CRI transmission message and TD-CRI components are shown in Table 5. Further details of the delta CRI message elements are shown in Table 6. [Table 5-1] [Table 5-2] [Table 6-1] [Table 6-2]

[0231] Table 6 shows an example of a delta CRI message element that transports the TD-CRI using bit fields to represent active (included / selected) time domain pulses while taking into account the DC tone and guard tones. Other examples of data representations are described above and in the examples the delta CRI message elements may be adjusted to reflect those data schemes.

[0232] Table 7 shows an example of a detection imprint transmit message element for transferring a detection imprint from a detection receiver 502-1 to a detection algorithm manager 506 or a detection transmitter 504-1 that includes a detection algorithm manager 506. An example format of data storage for a detection imprint of a single detection receiver (i.e., detection receiver 502-1) is set forth in Table 1. In one example, the data structure set forth in Table 7 may be transferred via a detection imprint transmit message element or may be compressed prior to transmission using any available lossless compression technique. In one example, the data describing the detection imprint is accompanied by a header that describes the format of the data and the device and configuration with which the data is associated. [Table 7-1] [Table 7-2]

[0233] In one implementation, if the detection algorithm manager 506 is implemented on a separate device (i.e., not implemented within the detection transmitter 504-1), management frames may not be necessary and the detection imprint and TD-CRI may be encapsulated in a standard IEEE 802.11 data frame and forwarded to the detection algorithm manager 506. In one example, the data structures described in Tables 6 and 7 may be used to format the detection imprint and TD CRI data. In one example, a unique header or descriptor may be added to the data structure that allows the detection algorithm manager 506 to detect that the data structure is in the form of a detection imprint transmit message element or a delta CRI message element. In one example, the data may be forwarded in the format shown in FIG. 13, and the detection algorithm manager 506 may be configured to interpret message type values ​​representing the detection imprint transmit message element and the delta CRI message element.

[0234] 14 illustrates a sequence diagram 1400 for communication between a detection receiver 502-1, a detection transmitter 504-1, and a detection algorithm manager 506, where the detection receiver 502-1 is the detection initiator, according to some embodiments. FIG 14 illustrates an example of a network (e.g., an 802.11 network) in which the detection algorithm manager 506 is a separate device.

[0235] As shown in FIG. 14, in step 1402, the detection algorithm manager 506 may send a detection configuration message to the detection receiver 502-1. In one example, the detection configuration message may include TD-CRI configuration parameters. In step 1404, the detection receiver 502-1 may send an acknowledgement using a detection configuration response message in response to the detection configuration message and configure the detection agent 516-1 with the TD-CRI configuration parameters for use in generating the filtered TD-CRI. In step 1406, the detection receiver 502-1 may send a detection start message to the detection transmitter 504-1 initiating a detection session and requesting a detection transmission. In step 1408, the detection transmitter 504-1 may send a detection transmission to the detection receiver 502-1 in response to the detection start message. Upon receiving the detection transmission, the detection receiver 502-1 may perform channel state measurements on the received detection transmission and generate channel representation information using the TD-CRI configuration parameters. In one example, the detection receiver 502-1 may generate a filtered TD-CRI. In step 1410, the detection receiver 502-1 may send a CRI transmission message including the channel condition measurement (i.e., the filtered TD-CRI) over the air to the detection algorithm manager 506 for further processing.

[0236] 15 illustrates a sequence diagram 1500 for communication between a detection receiver 502-1, a detection transmitter 504-1, and a detection algorithm manager 506, where the detection transmitter 504-1 is the detection initiator, according to some embodiments. FIG 15 illustrates an example of a network (e.g., an 802.11 network) in which the detection algorithm manager 506 is a separate device.

[0237] As shown in FIG. 15, in step 1502, the detection algorithm manager 506 may send a detection configuration message to the detection receiver 502-1. In one example, the detection configuration message may include TD-CRI configuration parameters. In step 1504, the detection receiver 502-1 may send an acknowledgement using a detection configuration response message in response to the detection configuration message and configure the detection agent 516-1 with the TD-CRI configuration parameters for use in generating the filtered TD-CRI. In step 1506, the detection transmitter 504-1 may initiate a detection session and send a detection transmission NDP to the detection receiver 502-1 after a detection transmission announce message. As described in step 1508, the detection transmission NDP follows the detection transmission announce message after one SIFS. In one example, the duration of the SIFS is 10 μs. The detection receiver 502-1 may perform channel state measurements on the detection transmission NDP and generate channel representation information based on the TD-CRI configuration parameters. In one example, the detection receiver 502-1 may generate a filtered TD-CRI. In step 1510, the detection receiver 502-1 may send a CRI transmission message including the channel condition measurement (i.e., the filtered TD-CRI) over the air to the detection algorithm manager 506 for further processing.

[0238] 16 illustrates a sequence diagram 1600 for communication between a detection receiver 502-1 and a detection sender 504-1 that includes a detection algorithm manager 506, where the detection sender 504-1 is a detection initiator, according to some embodiments. FIG. 16 illustrates an example of a network (e.g., an 802.11 network) in which the detection sender 504-1 includes the detection algorithm manager 506.

[0239] As shown in FIG. 16, in step 1602, the sensing transmitter 504-1 may initiate a sensing session and send a sensing transmission NDP to the sensing receiver 502-1 after a sensing transmission announce message. In one example, the sensing transmission announce message may include TD-CRI configuration parameters. As described in step 1604, the sensing transmission NDP follows the sensing transmission announce message after one SIFS. In one example, the duration of the SIFS is 10 μs. In one implementation, the sensing receiver 502-1 may perform a channel condition measurement on the sensing transmission NDP and generate channel representation information based on the TD-CRI configuration parameters. In one example, the sensing receiver 502-1 may generate a filtered TD-CRI. In one implementation, the sensing receiver 502-1 may store the channel condition measurement in a temporary storage device, such as the channel representation information storage device 520-1. In one example, the sensing receiver 502-1 may hold the channel condition measurement until it receives a sensing measurement polling message. In step 1606, the detection transmitter 504-1 may send a detection measurement polling message to the detection receiver 502-1, which may trigger the detection receiver 502-1 to send the already formatted channel condition measurement (i.e., the filtered TD-CRI) and forward the channel condition measurement to the detection transmitter 504-1. In another example, in step 1606, the detection transmitter 504-1 may send a detection measurement polling message to the detection receiver 502-1, which may trigger the detection receiver 502-1 to format the channel condition measurement (i.e., create the filtered TD-CRI) and forward the channel condition measurement to the detection transmitter 504-1. In step 1608, the detection receiver 502-1 may send a CRI transmission message over the air, which includes the channel condition measurement (i.e., the filtered TD-CRI), to the detection transmitter 504-1. In one implementation, the detection algorithm manager 506 may further process the channel condition measurement. In some implementations, the sensing transmitter 504-1 may include TD-CRI configuration parameters in a sensing measurement polling message.According to some implementations, the sensing transmitter 504-1 may use multiple sensing measurement polling messages to request channel representation information in multiple formats.

[0240] According to one implementation, when the sensing transmission is performed between the sensing transmitter 504-1 and the sensing receiver 502-1, which are fixed in space (i.e., not movable), the motion in the sensing space typically changes the characteristics of some, but not all, of the time-domain pulses of the channel impulse response. Furthermore, when the motion occurs in the sensing space and is not very close to the sensing receiver 502-1 or the sensing transmitter 504-1, the constituent time-domain pulses of the channel impulse response are highly decorated (there is very low cross-pulse correlation). This means that each time-domain pulse is affected independently of all other pulses. As a result, the impulse response of the entire channel can be conveyed to the sensing algorithm manager 506 by identifying only the changes (phase and amplitude) of a subset of the time-domain pulses affected by the motion or movement. Thus, by sending the filtered TD-CRI instead of all of the frequency-domain CSI values ​​provided by the baseband receiver, the amount of information transmitted from the sensing receiver 502-1 to the sensing algorithm manager 506 is significantly reduced. Thus, minimizing the amount of information transmitted between the detection receiver 502-1 and the detection algorithm manager 506 minimizes the overhead that the system 500 places on the Wi-Fi network. Also, in scenarios where CSI may be passed from the MAC layer to higher layers, minimizing the amount of information passed reduces traffic on the data bus, conserving microprocessor and memory activity, and therefore reducing power usage of the system 500.

[0241] According to one aspect of the present disclosure, if the detection receiver 502-1 sends a filtered TD-CRI including only time-domain pulses affected by changes in the impulse response of the propagation channel, significantly fewer values ​​compared to the CSI values ​​may be sent from the detection receiver 502-1 to the detection algorithm manager 506. As a result, the amount of information conveyed from the detection receiver 502-1 to the detection algorithm manager 506 may be significantly reduced. Furthermore, when the detection algorithm manager 506 receives the filtered TD-CRI including time-domain pulses affected by changes in the propagation channel impulse response together with an indication of the location of the time-domain pulses in the time-domain representation from the detection receiver 502-1, the detection algorithm manager 506 may reconstruct the time-domain representation by combining the time-domain pulses of the filtered TD-CRI with those of the identified detection imprints in the correct locations to form a reconstructed filtered TD-CRI, and performing an FFT on the reconstructed filtered TD-CRI. As a result, a nearly accurate frequency-domain CSI is obtained (i.e., the R-CSI is nearly identical to the CSI). Thus, according to aspects of the present disclosure, a nearly lossless channel representation is achieved while still significantly reducing the amount of data transmitted compared to transmitting the CSI itself.

[0242] 17A and 17B depict a flowchart 1700 for sending a filtered TD-CRI to a detection algorithm manager 506 according to some embodiments. In a brief overview of the implementation of the flowchart 1700, in step 1702, a detection transmission is received. In step 1704, a detection measurement is generated based on the detection transmission. In step 1706, a full TD-CRI of a propagation channel between the detection receiver 502-1 and the detection transmitter 504-1 is generated based on the detection measurement. In step 1708, a detection imprint is obtained that represents a steady-state propagation channel between the detection receiver 502-1 and the detection transmitter 504-1. In step 1710, the full TD-CRI is compared with the detection imprint. In step 1712, a filtered TD-CRI is identified according to a difference between the full TD-CRI and the detection imprint. In step 1714, the filtered TD-CRI is sent to the detection algorithm manager 506.

[0243] Step 1702 includes receiving a detection transmission. In one implementation, the detection receiver 502-1 may receive the detection transmission from the detection transmitter 504-1.

[0244] Step 1704 includes generating a detection measurement based on the detection transmission. In one implementation, the detection receiver 502-1 may generate the detection measurement based on the detection transmission.

[0245] Step 1706 includes generating a full TD-CRI of the propagation channel between the detecting receiver 502-1 and the detecting transmitter 504-1 based on the detection measurements. In one implementation, the detecting receiver 502-1 may generate a full TD-CRI of the propagation channel between the detecting receiver 502-1 and the detecting transmitter 504-1 based on the detection measurements.

[0246] Step 1708 includes obtaining a detection imprint representing a steady-state propagation channel between the detection receiver 502-1 and the detection transmitter 504-1. In one implementation, the detection receiver 502-1 may obtain a detection imprint representing a steady-state propagation channel between the detection receiver 502-1 and the detection transmitter 504-1. In one example, the detection receiver 502-1 may obtain the detection imprint by obtaining the detection imprint from the detection imprint storage device 518-1.

[0247] Step 1710 includes comparing the full TD-CRI to the detection imprint. In one implementation, the detection receiver 502-1 may compare the full TD-CRI to the detection imprint.

[0248] Step 1712 includes identifying the filtered TD-CRI according to the difference between the full TD-CRI and the detection imprint. In one implementation, the detection receiver 502-1 may identify the filtered TD-CRI according to the difference between the full TD-CRI and the detection imprint. In one example, the detection receiver 502-1 may identify the filtered TD-CRI based on determining a first time domain pulse of the full TD-CRI that is different from a second time domain pulse of the detection imprint and designating the first time domain pulse as the filtered TD-CRI. In one example, the detection receiver 502-1 may store the difference between the first time domain pulse of the full TD-CRI and the second time domain pulse of the detection imprint as an imprint delta that defines the filtered TD-CRI. The difference stored as the imprint delta requires fewer bits than the first time domain pulse. In one example, the detection receiver 502-1 may store only the difference that exceeds a measurement imprint delta threshold.

[0249] Step 1714 includes sending the filtered TD-CRI to the detection algorithm manager 506. In one implementation, the detection receiver 502-1 may send the filtered TD-CRI to the detection algorithm manager 506. In some implementations, the detection receiver 502-1 may send a detection imprint indicator to the detection algorithm device 506.

[0250] FIG. 18 illustrates a flowchart 1800 for detecting features of interest in a detection space according to some embodiments. In a brief overview of an implementation of the flowchart 1800, in step 1802, a filtered TD-CRI is received. In step 1804, a detection imprint is obtained. In step 1806, a reconstructed TD-CRI is generated from the filtered TD-CRI and the detection imprint. In step 1808, the reconstructed TD-CRI is transformed into a reconstructed frequency domain channel representation. In step 1810, features of interest are detected in the detection space according to the reconstructed frequency domain channel representation.

[0251] Step 1802 includes receiving a filtered TD-CRI. In one implementation, the detection algorithm device 506 may receive the filtered TD-CRI from the detection receiver 502-1. In one example, the filtered TD-CRI may include a plurality of time domain pulses. In some implementations, the detection algorithm device 506 may receive an imprint delta that stores a time domain pulse difference. In one example, the detection algorithm device 506 may receive a location bitmap that indicates a location of a corresponding time domain pulse in a detection imprint. In one example, the detection algorithm device 506 may receive a detection imprint indicator.

[0252] Step 1804 includes obtaining the detection imprint. In one implementation, the detection algorithm device 506 may obtain the detection imprint. In one example, the detection algorithm device 506 may obtain the detection imprint according to the detection imprint indicator.

[0253] Step 1806 includes generating a reconstructed TD-CRI from the filtered TD-CRI and the sensing imprint. In one implementation, the sensing algorithm device 506 may generate the reconstructed TD-CRI from the filtered TD-CRI and the sensing imprint. In one example, the sensing algorithm device 506 may generate the reconstructed TD-CRI by replacing a corresponding time domain pulse of the sensing imprint with a plurality of time domain pulses. In one example, the sensing algorithm device 506 may generate the reconstructed TD-CRI by adding a time domain pulse difference to a corresponding time domain pulse of the sensing imprint.

[0254] Step 1808 includes converting the reconstructed TD-CRI into a reconstructed frequency domain channel representation. In one implementation, the detection algorithm device 506 may convert the reconstructed TD-CRI into a reconstructed frequency domain channel representation.

[0255] Step 1810 includes detecting features of interest in the detection space according to the reconstructed frequency domain channel representation. In one implementation, the detection algorithm device 506 may detect features of interest in the detection space according to the reconstructed frequency domain channel representation.

[0256] 19A and 19B depict a flowchart 1900 for transmitting a location bitmap indicating a location in the full TD-CRI of a first time-domain pulse to the detection algorithm manager 506 according to some embodiments. In a brief overview of an implementation of the flowchart 1900, in step 1902, a detection transmission is received. In step 1904, a detection measurement is generated based on the detection transmission. In step 1906, a full TD-CRI of a propagation channel between the detection receiver 502-1 and the detection transmitter 504-1 is generated based on the detection measurement. In step 1908, a request for a high fidelity TD-CRI reconstruction is received from the detection algorithm manager 506. In step 1910, a detection imprint is obtained that represents a steady-state propagation channel between the detection receiver 502-1 and the detection transmitter 504-1. In step 1912, the full TD-CRI is compared to the detection imprint to determine a first time-domain pulse of the full TD-CRI that is different from the second time-domain pulse of the detection imprint. In step 1914 , a location bitmap indicating the location within the full TD-CRI of the first time-domain pulse is sent to the detection algorithm manager 506 .

[0257] Step 1902 includes receiving a detection transmission. In one implementation, the detection receiver 502-1 may receive the detection transmission from the detection transmitter 504-1.

[0258] Step 1904 includes generating a detection measurement based on the detection transmission. In one implementation, the detection receiver 502-1 may generate the detection measurement based on the detection transmission.

[0259] Step 1906 includes generating a full TD-CRI of the propagation channel between the detecting receiver 502-1 and the detecting transmitter 504-1 based on the detection measurements. In one implementation, the detecting receiver 502-1 may generate a full TD-CRI of the propagation channel between the detecting receiver 502-1 and the detecting transmitter 504-1 based on the detection measurements.

[0260] Step 1908 includes receiving a request for high fidelity TD-CRI reconfiguration from the detection algorithm manager 506. In one implementation, the detection receiver 502-1 may receive the request for high fidelity TD-CRI reconfiguration from the detection algorithm manager 506.

[0261] Step 1910 includes obtaining a detection imprint representing a steady-state propagation channel between the detection receiver 502-1 and the detection transmitter 504-1. In one implementation, the detection receiver 502-1 may obtain a detection imprint representing a steady-state propagation channel between the detection receiver 502-1 and the detection transmitter 504-1. In one example, the detection receiver 502-1 may obtain the detection imprint by obtaining the detection imprint from the detection imprint storage device 518-1.

[0262] Step 1912 includes comparing the full TD-CRI to the detection imprint to determine a first time-domain pulse of the full TD-CRI that is different from the second time-domain pulse of the detection imprint. In one implementation, the detection receiver 502-1 may compare the full TD-CRI to the detection imprint to determine a first time-domain pulse of the full TD-CRI that is different from the second time-domain pulse of the detection imprint.

[0263] Step 1914 includes transmitting a location bitmap indicating a location within the full TD-CRI of the first time-domain pulse to the detection algorithm manager 506. In one implementation, the detection receiver 502-1 may transmit a location bitmap indicating a location within the full TD-CRI of the first time-domain pulse to the detection algorithm manager 506.

[0264] FIG. 20 depicts a flowchart 2000 for making a sensing imprint update decision based on a steady-state imprint delta threshold according to some embodiments. In a brief overview of one implementation of the flowchart 2000, in step 2002, a previous imprint delta selected according to a steady-state imprint delta period is obtained. In step 2004, the previous imprint delta is compared with the current imprint delta. In step 2006, a changed time domain pulse in the previous imprint delta and a corresponding time domain pulse in the current imprint delta are identified. In step 2008, it is determined that the corresponding time domain pulse remains above the steady-state imprint delta threshold. In step 2010, upon determining that the corresponding time domain pulse remains above the steady-state imprint delta threshold, a sensing imprint update decision is made.

[0265] Step 2002 includes acquiring a previous imprint delta selected according to a steady-state imprint delta period. In one implementation, the detection receiver 502-1 may acquire a previous imprint delta selected according to a steady-state imprint delta period. In some implementations, the detection algorithm manager 506 may acquire a previous imprint delta selected according to a steady-state imprint delta period.

[0266] Step 2004 includes comparing the previous imprint delta with the current imprint delta. In one implementation, the detection receiver 502-1 may compare the previous imprint delta with the current imprint delta. In some implementations, the detection algorithm manager 506 may compare the previous imprint delta with the current imprint delta.

[0267] Step 2006 includes identifying the modified time domain pulse in the previous imprint delta and the corresponding time domain pulse in the current imprint delta. In one implementation, the detection receiver 502-1 may identify the modified time domain pulse in the previous imprint delta and the corresponding time domain pulse in the current imprint delta. In some implementations, the detection algorithm manager 506 may identify the modified time domain pulse in the previous imprint delta and the corresponding time domain pulse in the current imprint delta.

[0268] Step 2008 includes determining that the corresponding time domain pulse remains above the steady-state imprint delta threshold. In one implementation, the detection receiver 502-1 may determine that the corresponding time domain pulse remains above the steady-state imprint delta threshold. In some implementations, the detection algorithm manager 506 may determine that the corresponding time domain pulse remains above the steady-state imprint delta threshold.

[0269] Step 2010 includes making a detection imprint update decision upon determining that the corresponding time domain pulse remains above the steady-state imprint delta threshold. In one implementation, the detection receiver 502-1 may make the detection imprint update decision upon determining that the corresponding time domain pulse remains above the steady-state imprint delta threshold. In some implementations, the detection algorithm manager 506 may make the detection imprint update decision upon determining that the corresponding time domain pulse remains above the steady-state imprint delta threshold.

[0270] FIG. 21 illustrates a flowchart 2100 for a sensed imprint update decision based on an imprint delta derivative threshold, according to some embodiments. In a brief overview of an implementation of the flowchart 2100, in step 2102, a previous imprint delta selected according to an imprint delta derivative period is obtained. In step 2104, the previous imprint delta is compared with the current imprint delta. In step 2106, a changed time domain pulse between the previous imprint delta and the current imprint delta is identified. In step 2108, it is determined that the corresponding time domain pulse is below the imprint delta derivative threshold. In step 2110, a sensed imprint update decision is made upon determining that the corresponding time domain pulse is below the imprint delta derivative threshold.

[0271] Step 2102 includes acquiring a previous imprint delta selected according to the imprint delta derivative term. In one implementation, the detection receiver 502-1 may then acquire the previous imprint delta selected according to the imprint delta derivative term. In some implementations, the detection algorithm manager 506 may acquire the previous imprint delta selected according to the imprint delta derivative term.

[0272] Step 2104 includes comparing the previous imprint delta with the current imprint delta. In one implementation, the detection receiver 502-1 may compare the previous imprint delta with the current imprint delta. In some implementations, the detection algorithm manager 506 may compare the previous imprint delta with the current imprint delta.

[0273] Step 2106 includes identifying a modified time domain pulse between the previous imprint delta and the current imprint delta. In one implementation, the detection receiver 502-1 may identify a modified time domain pulse between the previous imprint delta and the current imprint delta. In some implementations, the detection algorithm manager 506 may identify a modified time domain pulse between the previous imprint delta and the current imprint delta.

[0274] Step 2108 includes determining that the corresponding time domain pulse is below the imprint delta derivative threshold. In one implementation, the detection receiver 502-1 may determine that the corresponding time domain pulse is below the imprint delta derivative threshold. In some implementations, the detection algorithm manager 506 may determine that the corresponding time domain pulse is below the imprint delta derivative threshold.

[0275] Step 2110 includes making a detection imprint update decision when the corresponding time domain pulse is determined to be below the imprint delta derivative threshold. In one implementation, the detection receiver 502-1 may make the detection imprint update decision when the corresponding time domain pulse is determined to be below the imprint delta derivative threshold. In some implementations, the detection algorithm manager 506 may make the detection imprint update decision when the corresponding time domain pulse is determined to be below the imprint delta derivative threshold.

[0276] In a further embodiment,

[0277] Embodiment 1 is a method for Wi-Fi detection implemented by a detection receiver including a transmitting antenna, a receiving antenna, and at least one processor configured to execute instructions, the method including: receiving a detection transmission via the receiving antenna; generating, by the at least one processor, a detection measurement based on the detection transmission; generating, by the at least one processor, a full time-domain channel representation (TD-CRI) of a propagation channel between the detection receiver and the detection transmitter based on the detection measurement; obtaining, by the at least one processor, a detection imprint representing a steady-state propagation channel between the detection receiver and the detection transmitter; comparing, by the at least one processor, the detection imprint and the full TD-CRI; identifying, by the at least one processor, a filtered TD-CRI according to a difference between the full TD-CRI and the detection imprint; and sending the filtered TD-CRI to a detection algorithm manager.

[0278] Embodiment 2 is a method according to embodiment 1, wherein identifying the filtered TD-CRI includes determining a first time-domain pulse of the full TD-CRI that is different from a second time-domain pulse of the detection imprint, and designating the first time-domain pulse as the filtered TD-CRI.

[0279] Example 3 is a method according to example 1 or 2, further comprising: acquiring a detection imprint by a detection algorithm manager; and generating a reconstructed TD-CRI by replacing a corresponding time domain pulse of the detection imprint with a first time domain pulse of the filtered TD-CRI by the detection algorithm manager.

[0280] Example 4 is the method of example 2 or 3, further comprising sending a location bitmap indicating a location within the full TD-CRI of the first time-domain pulse to the detection algorithm manager.

[0281] Embodiment 5 is a method according to any one of embodiments 1 to 4, further comprising storing a difference between the first time-domain pulse of the full TD-CRI and the second time-domain pulse of the detection imprint as an imprint delta defining the filtered TD-CRI.

[0282] Example 6 is the method of example 5, wherein the difference stored as the imprint delta requires fewer bits than the first time-domain pulse.

[0283] Example 7 is a method according to any one of Examples 5 to 6, wherein storing the difference between the first time-domain pulse of the full TD-CRI and the second time-domain pulse of the detection imprint includes storing only differences that exceed a measurement imprint delta threshold.

[0284] Example 8 is the method of example 7, further comprising: obtaining a detection imprint by a detection algorithm manager; and generating a reconstructed TD-CRI by adding, by the detection algorithm manager, the difference stored in the imprint delta to a corresponding time domain pulse of the detection imprint.

[0285] Example 9 is the method of example 7 or 8, further comprising sending a location bitmap to the detection algorithm manager indicating an imprint delta location corresponding to the TD-CRI location.

[0286] Embodiment 10 is a method according to any one of embodiments 1 to 9, wherein the comparison of the full TD-CRI with the detection imprint is performed in response to a request from a detection algorithm manager for high-fidelity TD-CRI reconstruction.

[0287] An eleventh embodiment is the method according to any one of the first to tenth embodiments, further comprising sending a detection imprint indicator to a detection algorithm manager.

[0288] A twelfth embodiment is the method according to any one of the first to eleventh embodiments, further comprising: performing a sensing imprint update determination; and updating the sensing imprint in response to the sensing imprint update determination.

[0289] Example 13 is a method according to Example 12, in which making a detection imprint update determination includes obtaining a previous imprint delta selected according to a steady-state imprint delta period, comparing the previous imprint delta with a current imprint delta, identifying a changed time domain pulse in the previous imprint delta and a corresponding time domain pulse in the current imprint delta, and determining that the corresponding time domain pulse remains above a steady-state imprint delta threshold.

[0290] Example 14 is the method according to example 12 or 13, wherein making the sensed imprint update decision includes obtaining a previous imprint delta selected according to an imprint delta derivative period, comparing the previous imprint delta with a current imprint delta, identifying a time domain pulse that has changed between the previous imprint delta and the current imprint delta, and determining that the corresponding time domain pulse is below an imprint delta derivative threshold.

[0291] A fifteenth embodiment is the method according to any one of the twelfth to fourteenth embodiments, wherein making the sensing imprint update determination includes determining that an imprint validity timer has expired.

[0292] Embodiment 16 is a method for Wi-Fi detection implemented by a device including a receive antenna and at least one processor configured to execute instructions, the method including receiving a filtered TD-CRI via the receive antenna, obtaining a detection imprint by the at least one processor, generating a reconstructed TD-CRI from the filtered TD-CRI and the detection imprint by a detection algorithm manager, converting the reconstructed TD-CRI to a reconstructed frequency domain channel representation, and detecting features of interest in a detection space according to the reconstructed frequency domain channel representation by the detection algorithm manager.

[0293] Embodiment 17 is a method according to embodiment 16, wherein receiving the filtered TD-CRI includes receiving a plurality of time-domain pulses, and generating a reconstructed TD-CRI includes replacing a corresponding time-domain pulse of the detection imprint with the plurality of time-domain pulses.

[0294] Example 18 is the method of example 17, further comprising receiving a location bitmap indicating locations of corresponding time-domain pulses within the sensing imprint.

[0295] Embodiment 19 is a method according to any one of embodiments 16 to 18, wherein receiving the filtered TD-CRI includes receiving an imprint delta that stores a time-domain pulse difference, and generating a reconstructed TD-CRI includes adding the time-domain pulse difference to a corresponding time-domain pulse of the detection imprint.

[0296] Example 20 is the method of example 19, further comprising receiving a location bitmap indicating locations of corresponding time-domain pulses within the sensing imprint.

[0297] Example 21 is the method according to any one of Examples 16 to 20, further comprising receiving a sensing imprint indicator, wherein obtaining the sensing imprint is performed according to the sensing imprint indicator.

[0298] A twenty-second embodiment is the method according to any one of the sixteenth to twenty-first embodiments, further comprising: performing a sensing imprint update decision; and updating the sensing imprint in response to the sensing imprint update decision.

[0299] Example 23 is a method according to example 22, wherein making a detection imprint update determination includes obtaining a previous imprint delta selected according to a steady-state imprint delta period, comparing the previous imprint delta with a current imprint delta, identifying a changed time domain pulse in the previous imprint delta and a corresponding time domain pulse in the current imprint delta, and determining that the corresponding time domain pulse remains above a steady-state imprint delta threshold.

[0300] Example 24 is a method according to embodiment 22 or 23, wherein making a sensed imprint update decision includes obtaining a previous imprint delta selected according to an imprint delta derivative period, comparing the previous imprint delta with a current imprint delta, identifying a time domain pulse that has changed between the previous imprint delta and the current imprint delta, and determining that the corresponding time domain pulse is below an imprint delta derivative threshold.

[0301] Example 25 is the method according to any one of Examples 22 to 24, wherein making the sensing imprint update determination includes determining that an imprint validity timer has expired.

[0302] Embodiment 26 is a method for Wi-Fi detection implemented by a detection receiver including a transmitting antenna, a receiving antenna, and at least one processor configured to execute instructions, the method including: transmitting a detection trigger message via the transmitting antenna; receiving a detection transmission from a detection transmitter via the receiving antenna; obtaining, by the at least one processor, channel representation information based on the detection transmission; identifying, by the at least one processor, that a difference between the channel representation information and a detection imprint exceeds a threshold, where the detection imprint includes two or more previously measured channel representation information; and sending the channel representation information to a detection algorithm manager in response to identifying that the difference exceeds the threshold.

[0303] Example 27 is the method of example 26, wherein the sensing imprint represents a steady-state propagation channel between the sensing transmitter and the sensing receiver.

[0304]

[0046] Embodiment 28 is a method according to embodiment 26 or 27, wherein the channel representation information includes one or more of channel state information (CSI), full time domain channel representation information (TD-CRI), and filtered TD-CRI.

[0305] Embodiment 29 is the method according to any one of embodiments 26 to 28, wherein the threshold value includes one or more of an amplitude threshold value or a phase threshold value, or a combination of both an amplitude threshold value and a phase threshold value.

[0306]

[0081] An embodiment 30 is the method according to any one of embodiments 26 to 29, in which the detection transmission includes a detection transmission null data PPDU (NDP).

[0307] Embodiment 31 is a method according to any one of embodiments 26 to 30, further comprising updating, by at least one processor, the detection imprint in response to changes in the semi-static nature of one or more propagation channels between the detection receiver and the detection transmitter.

[0308] Embodiment 32 is a method for Wi-Fi detection implemented by a device including a transmitting antenna, a receiving antenna, and at least one processor configured to execute instructions, the method including: receiving a threshold value from a detection initiator via the receiving antenna; receiving a detection transmit announce message and a detection transmit null data PPDU (NDP) from a detection transmitter via the receiving antenna; obtaining, by the at least one processor, channel representation information based on the detection transmit NDP; receiving a measurement poll message from the detection initiator via the receiving antenna; identifying, by the at least one processor, that a difference between the channel representation information and a detection imprint exceeds a threshold value, where the detection imprint includes two or more previously measured channel representation information; and sending, by the at least one processor, the channel representation information to the detection initiator via the transmitting antenna in response to identifying that the difference exceeds the threshold value.

[0309] Embodiment 33 is a method for Wi-Fi detection implemented by a device including a transmitting antenna, a receiving antenna, and at least one processor configured to execute instructions, comprising: receiving a detection imprint from a detection receiver via the receiving antenna; transmitting a detection transmission to the detection receiver via the transmitting antenna; transmitting a measurement polling message via the transmitting antenna; receiving channel representation information based on the detection transmission via the receiving antenna; identifying, by the at least one processor, that a difference between the channel representation information and the detection imprint exceeds a threshold, where the detection imprint includes two or more previously measured channel representation information; and sending the channel representation information to a detection algorithm manager in response to identifying that the difference exceeds the threshold.

[0310] Embodiment 34 is a Wi-Fi detection system including a detection receiver including a transmitting antenna, a receiving antenna, and at least one processor, the processor being configured to execute instructions for transmitting a detection trigger message via the transmitting antenna, instructions for receiving a detection transmission from the detection transmitter via the receiving antenna, instructions for obtaining channel representation information based on the detection transmission, instructions for identifying that a difference between the channel representation information and a detection imprint exceeds a threshold, where the detection imprint includes two or more previously measured channel representation information, and instructions for sending the channel representation information to a detection algorithm manager in response to identifying that the difference exceeds the threshold.

[0311] Example 35 is the system of example 34, wherein the sensing imprint represents a steady-state propagation channel between the sensing transmitter and the sensing receiver.

[0312] Embodiment 36 is a system described in embodiment 34 or 35, wherein the channel representation information includes one or more of channel state information (CSI), full time domain channel representation information (TD-CRI), and filtered TD-CRI.

[0313] A thirty-seventh embodiment is the system according to any one of the thirty-fourth to thirty-sixth embodiments, wherein the threshold value includes one or more of an amplitude threshold value or a phase threshold value, or a combination of both an amplitude threshold value and a phase threshold value.

[0314] A thirty-eighth embodiment is the system according to any one of the thirty-fourth to thirty-seventh embodiments, in which the detection transmission includes a detection transmission null data PPDU (NDP).

[0315] Embodiment 39 is a system described in any one of embodiments 34 to 38, wherein at least one processor is further configured to update the detection imprint in response to changes in the semi-static nature of one or more propagation channels between the detection receiver and the detection transmitter.

[0316] Embodiment 40 is a Wi-Fi detection system including a device including a transmitting antenna, a receiving antenna, and at least one processor, the processor being configured to execute instructions for receiving a threshold value from a detection initiator via the receiving antenna, instructions for receiving a detection transmit announce message and a detection transmit null data PPDU (NDP) from a detection transmitter via the receiving antenna, instructions for obtaining channel representation information based on the detection transmit NDP, instructions for receiving a measurement poll message from the detection initiator via the receiving antenna, instructions for identifying that a difference between the channel representation information and a detection imprint exceeds a threshold value, the detection imprint including two or more previously measured channel representation information, and instructions for sending the channel representation information to the detection initiator via the transmitting antenna in response to identifying that the difference exceeds the threshold value.

[0317] Embodiment 41 is a Wi-Fi sensing system including a device including a transmitting antenna, a receiving antenna, and at least one processor, the processor being configured to execute instructions for receiving a sensing imprint from a sensing receiver via the receiving antenna, instructions for transmitting a sensing transmission to the sensing receiver via the transmitting antenna, instructions for transmitting a measurement polling message via the transmitting antenna, instructions for receiving channel representation information based on the sensing transmission via the receiving antenna, instructions for identifying that a difference between the channel representation information and the sensing imprint exceeds a threshold, the sensing imprint including two or more previously measured channel representation information, and instructions for sending the channel representation information to a sensing algorithm manager in response to identifying that the difference exceeds the threshold.

[0318] 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. Those skilled in the art may make changes in form and detail of the described methods and systems without departing from the broadest scope of the described methods and systems. Thus, the scope of the methods and systems described herein should not be limited by any of the illustrative embodiments, but should be defined according to the appended claims and their equivalents.

Claims

1. 1. A method for Wi-Fi detection performed by a detection transmitter, the method including a transmit antenna, a receive antenna, and at least one processor configured to execute instructions, and acting on behalf of a detection initiator, the method comprising: receiving, via the receiving antenna and from the sensing initiator, a threshold value associated with movement within a sensing space; transmitting a sensing transmission via the transmitting antenna to the sensing receiver, the sensing receiver being different from the sensing initiator; receiving a first sensing measurement report from the sensing receiver via the receive antenna and subsequent to transmitting the sensing transmission; transmitting a second sensing measurement report to the sensing initiator via the transmitting antenna of the sensing transmitter; Including, the first sensed measurement report includes channel representation information obtained by the sensed receiver based on the sensed transmission; the first detection measurement report is transmitted by the detection receiver in response to the detection receiver identifying that a difference between the channel representation information and the detection imprint exceeds the threshold; The method, wherein the sensing imprint represents channel representation information previously obtained at the sensing receiver, and the second sensing measurement report includes the first sensing measurement report.

2. The method of claim 1 , wherein the sensing imprint represents a propagation channel between the sensing transmitter and the sensing receiver.

3. The method of claim 1 , wherein the channel representation information comprises one or more of channel state information (CSI), full time domain channel representation information (TD-CRI), and filtered TD-CRI.

4. The method of claim 1 , wherein the threshold comprises one or more of an amplitude threshold or a phase threshold, or a combination of both an amplitude threshold and a phase threshold.

5. The method of claim 1 , wherein the sensing transmission comprises a sensing transmission Null Data PPDU (NDP).

6. The method of claim 1 , wherein the first sensed measurement report includes the channel representation information.

7. The method of claim 1 , wherein the previously acquired channel representation information is associated with a lack of motion in a sensing space.

8. The method of claim 1 , wherein the sensing receiver updates the sensing imprint in response to changes in semi-static properties of one or more propagation channels between the sensing receiver and the sensing transmitter.

9. The method of claim 1 , further comprising transmitting the threshold value to the sensing receiver via the transmit antenna.

10. 1. A system for Wi-Fi detection, comprising: a sensing transmitter acting in place of the sensing initiator; the sensing transmitter includes a transmitting antenna, a receiving antenna, and at least one processor; The at least one processor instructions to receive, via the receive antenna and from the sensing initiator, a threshold value associated with movement within a sensing volume; instructions to transmit a sensing transmission via the transmitting antenna to the sensing receiver, which is different from the sensing initiator; instructions for receiving a first sensing measurement report from the sensing receiver via the receive antenna and subsequent to transmitting the sensing transmission; instructions for transmitting a second sensing measurement report to the sensing initiator via the transmitting antenna of the sensing transmitter; configured to run the first sensed measurement report includes channel representation information obtained by the sensed receiver based on the sensed transmission; the first detection measurement report is transmitted by the detection receiver in response to the detection receiver identifying that a difference between the channel representation information and the detection imprint exceeds the threshold; The system, wherein the sensing imprint represents channel representation information previously obtained at the sensing receiver, and the second sensing measurement report includes the first sensing measurement report.

11. The system of claim 10 , wherein the sensing imprint represents a propagation channel between the sensing transmitter and the sensing receiver.

12. The system of claim 10 , wherein the channel representation information comprises one or more of channel state information (CSI), full time domain channel representation information (TD-CRI), and filtered TD-CRI.

13. The system of claim 10 , wherein the threshold comprises one or more of an amplitude threshold or a phase threshold, or a combination of both an amplitude threshold and a phase threshold.

14. The system of claim 10 , wherein the sensing transmission comprises a sensing transmission Null Data PPDU (NDP).

15. The system of claim 10 , wherein the first sensed measurement report includes the channel representation information.

16. The system of claim 10 , wherein the previously acquired channel representation information is associated with a lack of motion in a sensing space.

17. The system of claim 10 , wherein the sensing receiver updates the sensing imprint in response to changes in semi-static properties of one or more propagation channels between the sensing receiver and the sensing transmitter.

18. The system of claim 10 , wherein the processor is further configured to execute instructions to transmit the threshold value to the sensing receiver via the transmit antenna.

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