Patent Application
20230269657
This is the first application filed for the present disclosure.
The present disclosure pertains to the field of wireless communications, and in particular to techniques for transmitting measurement feedback in Wi-Fi sensing.
The use of Wi-Fi radio frequency (RF) signals for the identification and recognition of human activities and other applications is a well-publicized topic.
One particular sensing method relies on the use of Wi-Fi channel state information (CSI) capabilities to monitor changes to the CSI sequence (which can include characteristics such as amplitude and phase, among others). Wi-Fi CSI was first introduced in IEEE 802.11n in the context of multiple-in multiple-out (MIMO).
CSI represents how an electrical signal propagates from the transmitter to the receiver, and combined effects including scattering, fading, and power decay with respect to a distance travelled by the signal. A CSI training sequence is a known sequence designed to measure the channel effect between the transmitter and the receiver. Changes to the CSI sequence can then be processed in order to identify certain events, for example human gestures or human identity, which may be reflected in the changes to the CSI sequence.
CSI can further be reflective of a wireless signal's propagation characteristics for the link from the transmitter to the receiver at certain carrier frequencies. CSI measurements include information when wireless signals transmit through surrounding objects and humans in time, frequency and spatial domains, and can be used for various wireless sensing applications. For example, amplitude variations in CSI in the time domain may show different patterns for different humans, activities or gestures; phase shifts in CSI in the spatial and frequency domains (such as transmit/receive antennas and carrier frequencies) can be related to signal transmission delay and direction which can be used for human localization and tracking; and phase shifts in CSI in the time domain may demonstrate different dominant frequency components which can be used to estimate breathing rate. However some of these evaluations may be limited.
Accordingly, there is a need for new methods and devices to better harness the use of CSI in providing feedback information, that are not subject to one or more limitations of the prior art.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present disclosure. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present disclosure.
An object of embodiments of the present disclosure is to provide methods and devices for transmitting measurements feedback in Wi-Fi sensing.
An aspect of the disclosure provides for a method of providing a sensing initiator station with measurement feedback. The method includes broadcasting, by the sensing initiator station, a sensing announcement frame. The method further includes broadcasting, by the sensing initiator station, a sensing sequence frame, the sensing sequence frame containing a reference sequence. The method further includes transmitting, by the sensing initiator station, a feedback request frame, the feedback request frame including station information indicating resources allocated for each participating station. The method further includes receiving, from a responder station, a feedback frame to the sensing initiator, the feedback frame including an indicator corresponding to data contained in the feedback frame.
In some embodiments the method further includes receiving, from the responder station, at least one of an indication to participate, and an indication to not participate. In some embodiments the at least one of the indication to participate and the indication to not participate is sent one of before the broadcasting of the sensing sequence frame, and after the broadcasting of the sensing sequence frame. In some embodiments the sensing initiator station is one of an access point station, and a non-access point station. In some embodiments the sensing announcement frame includes at least one station ID for at least one station. In some embodiments the reference sequence is used by a participating station to estimate at least one of channel state information (CSI) channel state information (CSI), angle of arrival (AoA), angle of departure (AoD), time of flight (ToF), time of arrival (ToA), and time of departure (ToD). In some embodiments the feedback request frame is a trigger frame. In some embodiments the feedback frame is an action frame. In some embodiments the feedback frame includes at least one of sensing measurements feedback, an indication that no measurements are reported, an indication to participate, and an indication to not participate. In some embodiments the sensing announcement frame is a null data packet announcement (NDPA) frame.
An advantage of embodiments can be that they may provide a feedback frame protocol for sending sensing measurements information from a responder station back to an initiator station. Further, the frame format presented herein may be used to start the sensing procedure in the downlink (DL) and the uplink (UL) directions. According to some embodiments, the frame format for the feedback frame disclosed herein is based on action frames, which can allow for easier integration into existing architectures. Moreover, some embodiments of the present disclosure define feedback types which may provide greater usability.
Another aspect of the disclosure provides for a device. The device includes a processor, and non-transitory computer readable memory having stored thereon machine readable instructions which when executed by the processor configure the device to execute the methods disclosed herein. For example, upon execution by the processor, the instructions configure the device to broadcast a sensing announcement frame and broadcast a sensing sequence frame, the sensing sequence frame containing a reference sequence. Upon execution by the processor, the instructions can further configure the device to transmit a feedback request frame, the feedback request frame including station information indicating resources allocated for each participating station. Upon execution by the processor, the instructions can further configure the device to receive a feedback frame from a responder station, the feedback frame including an indicator corresponding to data contained in the feedback frame.
Embodiments have been described above in conjunctions with aspects of the present disclosure upon which they can be implemented. Those skilled in the art will appreciate that embodiments may be implemented in conjunction with the aspect with which they are described, but may also be implemented with other embodiments of that aspect. When embodiments are mutually exclusive, or are otherwise incompatible with each other, it will be apparent to those skilled in the art. Some embodiments may be described in relation to one aspect, but may also be applicable to other aspects, as will be apparent to those of skill in the art.
Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in combination with the appended drawings, in which:
It will be noted that throughout the appended drawings, like features are identified by like reference numerals.
Embodiments of the present disclosure describe techniques for transmitting measurement feedback in Wi-Fi sensing. A sensing session begins with a sensing initiator station (which may be an access point station or a non-access point station) broadcasting a sensing announcement frame. The sensing announcement frame may be similar to a null data packet (NDP) announcement (NDPA), as defined in the 802.11 standard. The sensing announcement may include, among other information, the respective station ID of stations invited to participate in the sensing session. As the sensing announcement is a broadcast message, it is received by all stations associated with the particular sensing initiator station. The sensing announcement is followed by a sensing sequence frame containing a reference sequence (which may be similar to an NDP). The sensing sequence is used by a participating station in order to estimate the channel state information (CSI). A feedback request frame is then transmitted by the sensing initiator station. The feedback request frame is a trigger frame which includes the station information which indicate resources allocated for each participating station for their respective transmission. Then the one or more participating stations respond by sending a feedback frame to the sensing initiator station. The feedback frame may be an action frame.
As may be appreciated by a person skilled in the art, CSI may reflect wireless signal propagation characteristics associated with a link between a transmitter and a receiver at, for example, certain carrier frequencies. CSI measurements may include information in time, frequency, and spatial domains. CSI measurements may be used for various wireless sensing applications.
As used herein, an initiator shall be taken to be similar in meaning to a sensing initiator or a sensing initiator station, and a responder shall be taken to be similar in meaning to a sensing responder or a sensing responder station.
In some embodiments the sensing announcement frame includes at least one station ID for at least one station which is being asked for participation in the sensing session or sensing feedback session.
In some embodiments the method 100 further includes sending, by the responder station to the initiator station, at least one of an indication to participate and an indication to not participate. The provision of a participating or non-participating indicator may allow the initiator station to be informed of the willingness of a responder station to participate in a pending sensing session. Each responder station may elect to send an indication to participate, or not participate to the initiator station. The indications to participate or not participate may be action frames of the same sensing category. However, these indications may be configured in a variety of different formats as would be readily understood by a worker skilled in the art.
The call flow 200 may be a downlink (DL) procedure. As may be appreciated by a person skilled in the art, a DL procedure may refer to embodiments in which one or more sensing frames (for example, sensing sequence frame 208) may be carried in a sensing physical protocol data unit (PPDU) and transmitted by the sensing initiator 202 toward the sensing responders 204a and 204b. Accordingly, the DL direction may refer to the direction toward the sensing responders 204a and 204b from the sensing initiator 202.
Similarly, an uplink (UL) procedure may refer to embodiments in which one or more sensing frames may be carried in a sensing PPDU and transmitted by the one or more sensing responders (204a and 204b) toward the sensing initiator 202. The UL direction may refer to the direction toward the sensing initiator 202 from the sensing responders 204a and 204b.
In some embodiments at least one of the indications to participate and the indication to not participate is sent before the broadcasting of the sensing sequence frame 208. This timing of the transmission of the indication may allow for a sensing initiator 202 to identify early on which responder stations are willing participate in the sensing session, thereby potentially allowing the sensing initiator to transmit the sensing sequencing frame 208 and feedback request frame 210 only to the responder stations that have indicated participation.
In the embodiment illustrated in
In some embodiments the at least one of the indication to participate and the indication to not participate is sent after the broadcasting of the sensing sequence frame 208. This provision of the sensing sequence frame 208 prior to the transmission of the indication, can provide the responder stations with knowledge of the sensing sequence frame 208 prior to electing whether they wish to participate or not participate in the sensing session.
As with
In some embodiments the feedback type of the sensed measurements includes channel state information (CSI). In some embodiments, the type of feedback provided by a sensing responder depends on the measured values. For example, if the measured values are significantly different (e.g. the difference exceeds a pre-defined threshold value) from the previously measured values, the sensing responder feeds back the newly measured values to the sensing initiator in a “Sensing Measurement Feedback” action field. However, if the measured values are within a pre-defined threshold value, the sensing responder sends to the sensing initiator an indication that no new values are to be reported in a “No Measurements Are Reported” action field.
In some embodiments the feedback type of the sensed measurements includes angle of arrival (AoA) and/or angle of departure (AoD). AoA and AoD may be estimated using spatial diversity (e.g phase difference between different sensors, for example, multiple antennas) via CSI measurement for the location (e.g. direction) associated with the sensing responder. AoA and AoD measurement result formats have been defined in the 802.11 standard, which include: AoA/AoD Azimuth (in 360°/2048 resolution); AoA/AoD Azimuth Accuracy; AoA/AoD Elevation (in 180°/1024 resolution); and AoA/AoD Elevation Accuracy. In a sensing measurement information element (IE), the information related to AoA and AoD may be included, wherein the measured angle information that is being fed back to the sensing initiator is a real number.
In some embodiments the feedback type of the sensed measurements includes time of flight (ToF). ToF is a parameter that may be used to estimate the position of an object by measuring the distance to an object through considering the phase shift between subcarriers as a function of ToF in order to reformulate the steering matrix of a transmission. In this way, both antennas and subcarriers may be treated as sensors. In a sensing measurement IE, the information related to ToF on the subcarriers may be included, in which the measured time information that is being fed back to the sensing initiator is a real number.
In some embodiments the feedback type of the sensed measurements includes time of arrival (ToA) and/or time of departure (ToD). ToA and ToD are other possible sensing measurements if timestamp is considered. In a sensing measurement IE, the information related to ToA and ToD on the subcarriers may be included, in which the measured time information to be fed back is real number.
In some embodiments the sensing initiator station may be an access point station. In other embodiments the sensing initiator may be a non-access point station. The sensing initiator may initiate the sensing procedure and determine which devices (for example, one or more sensing responders) may be requested to send one or more of sensing frames and sensing feedback. The one or more sensing responders may be a Wi-Fi station capable of performing sensing actions as described herein.
In some embodiments the reference sequence associated with a sensing sequence frame is used by a participating station in order to estimate channel state information (CSI). The reference sequence may be alternately or additionally be used by one or more participating stations to estimate one or more of angle of arrival (AoA), angle of departure (AoD), time of flight (ToF), time of arrival (ToA) and time of departure (ToD).
In some embodiments the feedback request frame is a trigger frame. For example, a feedback request frame may be used to exclude non-participating responder stations.
In some embodiments the feedback frame is an action frame. An action frame is defined in the 802.11 standard, and is depicted in
In some embodiments the feedback frame includes several types of feedback in order to indicate the type of feedback the sensing responder is transmitting to the sensing initiator. Various feedback types are shown in TABLE 1 below with an associated order number, which as an example may be defined by an eight bit sequence:
Having particular regard to TABLE 1, “Sensing Measurements Feedback” can be used to indicate that measurements are included in the frame. “No Measurements Are Reported” can be used to indicate that the sensing responder is not reporting any measurements at the particular time. No measurements may be result of the sensing responder not able to perform the required measurements or that changes in the measurements relative to the previously provided measurements are insignificant (e.g. do not exceed a predefined threshold) and may be ignored. “Participate/No Participate” can be used at the sensing session setup in order to indicate whether ability of the sensing responder will participate or not participate in the sensing session. For example, the determination of participating or not participating may be determined based on the abilities of the sensing responder or status of the sensing responder. “Sensing Measurements Feedback” may be further defined by a “Measurement Type” subfield, which may be used to indicate the type of measurements that are being transmitted or fed back by the sensing responder to the sensing initiator.
In some embodiments the sensing announcement frame is a null data packet announcement (NDPA) frame. As may be appreciated by a person skilled in the art, in the mainstream 802.11 (e.g., 11 ac, 11ax, 11be), the NDPA sounding dialog token field may follow the MAC header field (e.g. in the NDPA frame). The sounding dialog token field may include, for example, eight bits. The first two bits of the sounding dialog token field may be used to indicate the NDPA version, while the remaining six bits may be used to indicate the session of the NDPA. For example, the first two bits, may be used to indicate very high throughput (VHT) NDPA, high efficiency (HE) NDPA (11ax NDPA), ranging NDPA (11az NDPA), and extremely high throughput (EHT) NDPA (11be NDPA). Accordingly, the first two bits of the sounding dialog token field is already consumed and may no longer be used for any other indication.
As shown, the device includes a processor 810, memory 820, non-transitory mass storage 830, I/O interface 840, network interface 850, and a transceiver 860, all of which are communicatively coupled via bi-directional bus 870. According to certain embodiments, any or all of the depicted elements may be utilized, or only a subset of the elements. Further, the device 800 may contain multiple instances of certain elements, such as multiple processors, memories, or transceivers. Also, elements of the hardware device may be directly coupled to other elements without the bi-directional bus.
The memory 820 may include any type of non-transitory or non-transient memory such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), any combination of such, or the like. The mass storage element 830 may include any type of non-transitory storage device, such as a solid state drive, hard disk drive, a magnetic disk drive, an optical disk drive, USB drive, or any computer program product configured to store data and machine executable program code. According to certain embodiments, the memory 820 or mass storage 830 may have recorded thereon statements and instructions executable by the processor 810 for performing any of the aforementioned method steps described above.
It will be appreciated that, although specific embodiments of the technology have been described herein for purposes of illustration, various modifications may be made without departing from the scope of the technology. The specification and drawings are, accordingly, to be regarded simply as an illustration of the disclosure as defined by the appended claims, and are contemplated to cover any and all modifications, variations, combinations or equivalents that fall within the scope of the present disclosure. In particular, it is within the scope of the technology to provide a computer program product or program element, or a program storage or memory device such as a magnetic or optical wire, tape or disc, or the like, for storing signals readable by a machine, for controlling the operation of a computer according to the method of the technology and/or to structure some or all of its components in accordance with the system of the technology.
Acts associated with the methods described herein can be implemented as coded instructions in a computer program product. In other words, the computer program product is a computer-readable medium upon which software code is recorded to execute the methods when the computer program product is loaded into memory and executed on the microprocessor of the wireless communication device.
Acts associated with the methods described herein can be implemented as coded instructions in plural computer program products. For example, a first portion of the method may be performed using one computing device, and a second portion of the method may be performed using another computing device, server, or the like. In this case, each computer program product is a computer-readable medium upon which software code is recorded to execute appropriate portions of the method when a computer program product is loaded into memory and executed on the microprocessor of a computing device.
Further, each step of the methods may be executed on any computing device, such as a personal computer, server, PDA, or the like and pursuant to one or more, or a part of one or more, program elements, modules or objects generated from any programming language, such as C++, Java, or the like. In addition, each step, or a file or object or the like implementing each said step, may be executed by special purpose hardware or a circuit module designed for that purpose.
Although the present disclosure has been described with reference to specific features and embodiments thereof, it is evident that various modifications and combinations can be made thereto without departing from the disclosure. The specification and drawings are, accordingly, to be regarded simply as an illustration of the disclosure as defined by the appended claims, and are contemplated to cover any and all modifications, variations, combinations or equivalents that fall within the scope of the present disclosure.
