COMMUNICATION APPARATUS AND METHOD FOR SUBCARRIER SELECTIVE FEEDBACK - Patent application

Abstract

A communication device and a communication method for subcarrier selective feedback are provided. One exemplary embodiment provides a first communication device, the first communication device comprising: a receiver that, in operation, receives a PPDU; a circuit that, in operation, measures channel information of a channel based on the PPDU, the channel to be measured being divided into two or more segments, each of the two or more segments including one or more subcarriers, the circuit selecting a subset of one or more subcarriers to be reported for a corresponding segment; and a transmitter that, in operation, transmits a report frame to a second communication device, the report frame conveying channel information feedback based on the channel information of the selected subcarriers.

Description

[Technical field]

[0001] The present embodiments relate generally to communication devices, and more particularly to a method and apparatus for subcarrier selective feedback. [Background technology]

[0002] In the standardization of next-generation wireless local area networks (WLANs), a new technology that enables wireless sensing using IEEE 802.11 technology was discussed in the 802.11 Working Group and named 802.11bf WLAN SENS (hereafter referred to as 11bf).

[0003] In explicit feedback beamforming, channel sounding and corresponding feedback are used to assist the beamformer in determining the steering matrix Q to be used for the beamformed transmission. Three types of channel sounding feedback are defined in IEEE 802.11: channel state information (CSI) matrix feedback (as described in 11n, the beamformer receives the quantized MIMO channel matrix Heff from the beamformee), uncompressed beamforming feedback matrix (as described in 11n, the beamforming feedback matrix V detected by the beamformee is transmitted to the beamformer), and compressed beamforming feedback matrix (as described in 11n, 11ac, and 11ax, the beamforming feedback matrix V detected by the beamformee is compressed in the form of angles (ψ (psi) and Φ (phi)) and transmitted to the beamformer).

[0004] In 802.11bf, it is agreed that CSI (i.e., the channel measured during the training symbols of the received PPDU) is a type of sensing measurement result for sub-7 GHz WLAN sensing. To enable sub-7 GHz WLAN sensing, a RXVECTOR parameter CSI_ESTIMATE is defined, which contains the channel measured during the training symbols of the received PPDU. The format of CSI_ESTIMATE may be the same as that used in the Measurement Report field in the Sensing Measurement Report frame. A Sensing Measurement Report frame is also defined, which allows the sensing receiver to report the sensing measurements. This frame contains at least a Measurement Report Control field that contains the information necessary to interpret the Measurement Report field, or a Measurement Report field that conveys the CSI measurements obtained by the sensing receiver.

[0005] As can be seen from Table 100 in FIG. 1A (i.e., showing Table 9-56-CSI Report Field (20 MHz) in Non-Patent Document 1), the CSI report format used to convey CSI feedback in 802.11n is such that the CSI matrix for each reported subcarrier requires (3+2*Nb*Nc*Nr) bits. The 3 bits / carrier is the carrier matrix amplitude (or the per-subcarrier scaling ratio M H (k)), where there is one I and one Q value per subcarrier. Table 102 in FIG. 1B shows the meaning and range of values ​​of each CSI field parameter, in particular, Nb refers to the number of bits used to quantize I and Q as determined by the coefficient size field of the MIMO control field, Nc refers to the number of columns of the CSI matrix, Nr refers to the number of rows of the CSI matrix, and Ng refers to the subcarrier grouping parameter.

[0006] The size of the CSI feedback can be reduced by using subcarrier grouping. Grouping is a method to reduce the size of the CSI Report field by reporting a single value for each group of Ng adjacent subcarriers. When using grouping, the size of the CSI Report field is Nr*8+Ns*(3+2*Nb*Nc*Nr) bits, where the number of transmitted subcarriers Ns is a function of Ng and the bandwidth. The subcarrier index scidx(i) (i=0,...,Ns-1) is a subset of the subcarrier indexes identified by the 802.11ax bandwidth (BW) and grouping subfields defined in table 200 of FIG. 2 (i.e., Table 9-91e of 3GPP TS 2011-01066), starting with scidx(0) and ending with scidx(Ns-1), in the given order. This implicitly defines Ns. For full bandwidth feedback, the subcarrier indices scidx(i), for i=0,...,Ns-1, are the entire superset shown in table 200, in the order given. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] IEEE P802.11-2020 [Non-Patent Document 2] 'Tracking vital signs during sleep leveraging off-the-shelf WiFi,' (J. Liu, Y. Wang, Y. Chen, J. Yang, X. Chen, and J. Cheng, 2015) [Non-Patent Document 3] 'Continuous user verification via respiratory biometrics' (Liu, J., Chen, Y., Dong, Y., Wang, Y., Zhao, T. and Yao, YD, 2020) [Non-Patent Document 4] 'PhaseBeat: Exploiting CSI Phase Data for Vital Sign Monitoring with Commodity WiFi Devices,' (Xuyu Wang, Chao Yang, and Shiwen Mao. 2017) [Non-Patent Document 5] 'Light Weight Passive Human Motion Detection with WiFi', (Xu Wang, Linghua Zhang. 2021) [Non-Patent Document 6] 802.11ax-2021 specification Summary of the Invention [Problem to be solved by the invention]

[0008] 802.11ax and 802.11be (baseline for sub-7GHz 11bf) only support Ng=4 and 16, and the reported subcarrier index is fixed by the standard. Assuming 11bf adopts the same Ng value, if a high value is chosen, the CSI feedback will omit many subcarriers, and if a low value is chosen, the CSI feedback overhead will be large.

[0009] Therefore, what is needed is a communication apparatus and method that can solve the problems set forth above. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and appended claims, taken in conjunction with the accompanying drawings and this Background section of this disclosure. [Means for solving the problem]

[0010] Non-limiting and illustrative embodiments facilitate providing a communications apparatus and method for reduced-order CSI feedback.

[0011] According to one aspect of the present disclosure, there is provided a first communications device comprising: a receiver that, in operation, receives a physical layer protocol data unit (PPDU); circuitry that, in operation, measures channel information of a channel based on the PPDU, where the channel to be measured is divided into two or more segments, each of the two or more segments including one or more subcarriers, and the circuitry selects a subset of the one or more subcarriers to be reported for a corresponding segment; and a transmitter that, in operation, transmits a report frame to a second communications device, conveying channel information feedback based on the channel information of the selected subcarriers.

[0012] According to another aspect of the present disclosure, there is provided a second communications device comprising: a transmitter that, in operation, transmits a PPDU used by the first communications device to measure channel information of a channel, where the channel to be measured is divided into two or more segments, each of the two or more segments including one or more subcarriers, and where a subset of subcarriers to be reported for a corresponding segment is selected based on a grouping parameter Ng; and a receiver that, in operation, receives a reporting frame from the first communications device, where the reporting frame conveys channel information feedback based on channel information of the selected subcarriers.

[0013] According to another aspect of the present disclosure, there is provided a communication method, comprising: receiving a physical layer protocol data unit (PPDU); measuring channel information of a channel based on the PPDU, where the measured channel is divided into two or more segments, each of the two or more segments including one or more subcarriers; selecting a subset of one or more subcarriers to be reported for a corresponding segment; and transmitting a report frame carrying channel information feedback based on the channel information of the selected subcarriers.

[0014] It should be noted that the general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof. Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. These benefits and / or advantages may be obtained individually through the various embodiments and features of the specification and drawings, and it is not necessary for all of these features to be present in order to obtain one or more of such benefits and / or advantages. [Brief description of the drawings]

[0015] The accompanying drawings, together with the following detailed description, are incorporated in and form a part of this specification, and serve to illustrate various embodiments and to explain various principles and advantages according to the present embodiments. Throughout the different drawings, like reference numbers indicate identical or functionally similar elements. [Figure 1A] 1 shows a table for 20 MHz CSI reporting fields, according to an example. [Figure 1B] 1 shows a table for CSI field parameters, according to an example. [Diagram 2] 1 shows a table describing subcarrier indexes of a compressed beamforming feedback matrix, according to an example. [Diagram 3]1 shows an example diagram of an Extremely High Throughput (EHT) null data packet announcement (NDPA) frame. [Figure 4] 1 shows an example table illustrating how the Ng value is signaled in the STA Info field of an EHT NDPA frame. [Diagram 5] 1 shows an example graph illustrating the CSI time series pattern and subcarrier distribution for a vital signs sensing application (from Non-Patent Document 2). [Figure 6A] 1 shows an exemplary graph illustrating CSI measurements across subcarriers, corresponding scores across subcarriers, and respiration analysis based on selected subcarriers (from Non-Patent Document 3). [Figure 6B] 1 shows an exemplary graph illustrating CSI measurements across subcarriers, corresponding scores across subcarriers, and respiration analysis based on selected subcarriers (from Non-Patent Document 3). [Figure 6C] 1 shows an exemplary graph illustrating CSI measurements across subcarriers, corresponding scores across subcarriers, and respiration analysis based on selected subcarriers (from Non-Patent Document 3). [Figure 7A] 1 shows an example graph for vital signs sensing, depicting the CSI phase difference pattern after data calibration, the mean absolute deviation of each subcarrier, and heart rate estimation based on fast Fourier transform (FFT) (from Non-Patent Document 4). [Figure 7B] 1 shows an example graph for vital signs sensing, depicting the CSI phase difference pattern after data calibration, the mean absolute deviation of each subcarrier, and heart rate estimation based on fast Fourier transform (FFT) (from Non-Patent Document 4). [Figure 7C]1 shows an example graph for vital signs sensing, depicting the CSI phase difference pattern after data calibration, the mean absolute deviation of each subcarrier, and heart rate estimation based on fast Fourier transform (FFT) (from Non-Patent Document 4). [Figure 8] 1 shows an exemplary graph describing clusters of phase differences for human motion detection (from Non-Patent Document 5). [Figure 9] 1 illustrates an exemplary diagram of a subcarrier report, according to one example. [Figure 10] 1 shows an exemplary table describing subcarrier indexes for CSI, amplitude, and phase matrices, according to one example. [Figure 11] 1 shows an exemplary diagram of subcarrier selective feedback according to an example. [Figure 12A] 1 illustrates an exemplary flow chart of an initiator station (STA) procedure and a responder STA procedure according to one example. [Figure 12B] 1 illustrates an exemplary flow chart of an initiator station (STA) procedure and a responder STA procedure according to one example. [Figure 13] 13 shows an exemplary diagram of subcarrier selection and sensing according to embodiment E1. [Figure 14] An exemplary diagram of a sensing NDPA frame according to embodiment E1 is shown. [Figure 15A] 1 shows an example table illustrating various values ​​of the resource unit (RU) size field and the Ng_exponent field according to embodiment E1. [Figure 15B] 1 shows an example table illustrating various values ​​of the resource unit (RU) size field and the Ng_exponent field according to embodiment E1. [Figure 16] 1 shows an exemplary diagram of a Sensing Measurement Report frame according to embodiment E1. [Figure 17] 13 shows an example table describing Sensing Measurement Report fields of CSI according to embodiment E1. [Figure 18] 13 shows an exemplary table describing values ​​of scidx_mth_segment(k) when the segment size is 242 tones or 484 tones according to embodiment E1. [Figure 19] 13 shows an exemplary table describing values ​​of scidx_mth_segment(k) when the segment size is 996 tones or 2*996 tones according to embodiment E1. [Figure 20A] An exemplary diagram of a sensing NDPA frame based on a bandwidth of 160 MHz and an exemplary diagram of reported subcarriers according to embodiment E1 are shown. [Figure 20B] An exemplary diagram of a sensing NDPA frame based on a bandwidth of 160 MHz and an exemplary diagram of reported subcarriers according to embodiment E1 are shown. [Figure 21A] 1 shows an example diagram of a sensing NDPA frame and an example diagram of reported subcarriers based on a bandwidth of 320 MHz according to embodiment E1. [Figure 21B] 1 shows an example diagram of a sensing NDPA frame and an example diagram of reported subcarriers based on a bandwidth of 320 MHz according to embodiment E1. [Figure 22] 1 shows an exemplary diagram of a Sensing Session Setup Request frame according to embodiment E1. [Diagram 23] 13 shows an exemplary diagram of a sensing measurement setup request frame according to embodiment E1. [Figure 24] FIG. 13 shows an exemplary diagram of a respiration estimation sensing application setup according to embodiment E1. [Diagram 25] FIG. 13 shows an exemplary diagram of a coarse-grained CSI feedback sensing procedure according to embodiment E1. [Figure 26] FIG. 13 shows an exemplary diagram of CSI amplitude curves of selected subcarriers for a respiration estimation sensing application according to embodiment E1. [Figure 27A] FIG. 13 shows an example diagram of fine-grained CSI feedback collection for population detection and subcarrier identification for respiration estimation according to embodiment E1. [Figure 27B] FIG. 13 shows an example diagram of fine-grained CSI feedback collection over sub-channels including sub-carriers of interest for respiration estimation, according to embodiment E1. [Figure 28] 13 shows an exemplary flowchart of a respiration estimation sensing process according to embodiment E1. [Figure 29A] 13 shows an exemplary diagram of a sensing NDPA frame and a sensing measurement report frame according to embodiment E2. [Figure 29B] 13 shows an exemplary diagram of a sensing NDPA frame and a sensing measurement report frame according to embodiment E2. [Figure 30A] 13 shows an example diagram of the Partial BW Info subfield when bit B0 is set to '0' and when it is set to '1' according to embodiment E3. [Figure 30B] 13 shows an example diagram of the Partial BW Info subfield when bit B0 is set to '0' and when it is set to '1' according to embodiment E3. [Diagram 31] 13 shows a table describing additional settings of the BW, Partial BW Info subfield in sensing NDPA frames in addition to settings already allowed in EHT NDPA frames according to embodiment E3. [Diagram 32] An exemplary diagram of a sensing NDPA frame according to embodiment E3 is shown. [Diagram 33]13 shows an example diagram of a Sensing Measurement Report field and a corresponding feedback process according to embodiment E3. [Diagram 34] 13 shows another example diagram of a Sensing Measurement Report field and corresponding feedback process according to embodiment E3. [Diagram 35] An exemplary diagram of a sensing NDPA frame according to embodiment E4 is shown. [Diagram 36] An exemplary diagram of a sensing NDPA frame and corresponding feedback process according to embodiment E4 is shown. [Figure 37] An exemplary diagram of subcarriers according to embodiment E5 is shown. [Figure 38] 13 shows an exemplary table illustrating reported subcarriers for feedback on a 996-tone RU (80 MHz) for two values ​​of subcarrier_offset (2, 8) according to embodiment E5. [Figure 39A] An exemplary diagram of a sensing NDPA frame and a sensing measurement report frame according to embodiment E5 is shown. [Figure 39B] An exemplary diagram of a sensing NDPA frame and a sensing measurement report frame according to embodiment E5 is shown. [Figure 40A] 13 shows another exemplary diagram of a sensing NDPA frame and a sensing measurement report frame according to embodiment E5. [Figure 40B] 13 shows another exemplary diagram of a sensing NDPA frame and a sensing measurement report frame according to embodiment E5. [Diagram 41] An exemplary diagram of beamforming feedback according to embodiment E6 is shown. [Figure 42A] An exemplary diagram of a sensing NDPA frame and an EHT compressed beamforming or channel quality information (CQI) frame according to embodiment E6 is shown. [Figure 42B] An exemplary diagram of a sensing NDPA frame and an EHT compressed beamforming or channel quality information (CQI) frame according to embodiment E6 is shown. [Figure 43A] An exemplary diagram of a sensing NDPA frame and a sensing measurement report frame according to embodiment E7 is shown. [Figure 43B] An exemplary diagram of a sensing NDPA frame and a sensing measurement report frame according to embodiment E7 is shown. [Diagram 44] 13 shows an exemplary table illustrating an exemplary encoding of the subcarrier selection condition field (2 bits) according to embodiment E7. [Diagram 45] An exemplary diagram of a sensing NDPA frame and corresponding encoding of the Ng index field according to embodiment E7-1 is shown. [Figure 46] 13 shows an example table describing Sensing Measurement Report fields for CSI feedback according to embodiment E7-1. [Figure 47] 13 shows an example diagram of a Sensing Measurement Report field and corresponding feedback process according to embodiment E7-1. [Figure 48] 1 shows a schematic diagram of an apparatus suitable for sensing and communication in accordance with various embodiments. [Figure 49] 1 shows a schematic diagram of a sensing device according to various embodiments. [Figure 50] 1 shows a flow diagram illustrating a method for subcarrier selective feedback according to various embodiments. [Figure 51] 1 shows a partially boxed schematic diagram of a STA that may be implemented for subcarrier selective feedback in accordance with various embodiments.

[0016] Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The following detailed description is merely exemplary in nature and is not intended to limit the embodiments or the application and uses of the embodiments. Furthermore, there is no intention to be bound by the theories presented in the preceding Background or Detailed Description sections. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the Background section of this disclosure.

[0018] In an EHT non-TB sounding sequence where the STA Info field of the EHT NDP Announcement frame requests single user (SU) feedback, the subcarrier grouping, Ng, codebook size, and number of columns Nc used to generate the SU feedback are determined by the EHT beamformee, regardless of the parameters indicated by the EHT beamformer. However, in the case of multi-user (MU) feedback, the subcarrier grouping, Ng, codebook size, and number of columns Nc used to generate the MU feedback are determined by the EHT beamformer and indicated in the EHT NDP Announcement frame. For example, referring to the EHT NDPA frame 300 of FIG. 3, the grouping parameter Ng can be indicated in the feedback type and Ng subfield 306 of the STA Info field 302. Examples of values ​​and corresponding descriptions that may be indicated in the feedback type and Ng subfield 306 are shown in table 400 of FIG. 4.

[0019] Furthermore, the EHT NDPA frame 300 may include a partial BW Info subfield 304 in the STA Info field 302, which may further include a resolution subfield 308 and a feedback bitmap subfield 310. For a BW of 320 MHz, a value of 0 in the resolution subfield 308 indicates 20 MHz and a value of 1 indicates a resolution of 40 MHz. The feedback bitmap subfield 310 indicates each resolution bandwidth for which the beamformer is requesting feedback. Each bit in the feedback bitmap subfield 310 is set to 1 if feedback is requested for the corresponding bandwidth, and 0 otherwise. This is used to select the resource unit / multi-resource unit (RU / MRU) for which feedback is requested.

[0020] In mainstream 802.11, a sounding procedure is used by the beamformer to gather channel information for the purpose of making an accurate estimation of the transmit beamforming, and it can be argued that the feedback of channel information (e.g., compressed beamforming feedback) is not required for each subcarrier in the channel bandwidth, hence the use of large Ng values ​​(4 and 16) in the new 802.11 amendments (802.11ax, 802.11be). The channel information of the non-reported subcarriers can be estimated by the beamformer using techniques such as interpolation. However, for sounding used for sensing applications, the feedback of the channel information may be more sensitive to the subcarrier frequency. As an example, one common sensing application is human vital sign detection using the CSI of WLAN signals. The CSI is represented as a complex number and can be decomposed into amplitude and phase components. The importance of subcarrier selection in sensing applications such as vital sign detection is well known in the literature. For example, Non-Patent Document 2 shows that due to frequency diversity, the amplitudes of different subcarriers have different sensitivities to inhalation and exhalation due to breathing. Diagram 500 of FIG. 5 shows an example of the time evolution of CSI amplitude of 30 subcarriers extracted from a laptop in a Wi-Fi network when a person is sleeping. It can be seen that CSI from small subcarrier index is more affected by micro-motion due to breathing, while CSI from high subcarrier index (i.e., 15 to 30) is less affected. Also, the variance of CSI amplitude in a moving time window can be used to quantify the sensitivity of subcarriers to micro-motion. Diagram 502 of FIG. 5 shows the variance of 30 subcarriers. It can be seen that subcarriers with lower index have larger variance and are more sensitive to micro-motion. A threshold-based method can be used to select subcarriers with large variance of CSI amplitude in the time window for respiration rate estimation. In this disclosure, such subcarriers may be referred to as "subcarriers of interest."

[0021] Non-Patent Document 3 further shows that even within a group of high sensitivity subcarriers, the CSI of different subcarriers has different sensitivity to subtle respiratory motion because each subcarrier experiences unique multipath and shadowing effects. The more sensitive the subcarrier is to respiratory motion, the more comprehensive characteristics of respiratory motion can be captured by CSI. As an example, diagram 600 in FIG. 6A shows respiratory signals extracted from three subcarriers (i.e., subcarriers #4, #6, and #14). It is observed that the signal of subcarrier #4 has a larger periodicity and a larger amplitude of fluctuation than the other two subcarriers, which corresponds to the top score shown in diagram 602 in FIG. 6B. The measurement period is important to ensure a sufficient sampling rate. Furthermore, as seen in diagram 604 in FIG. 6C, the selected high sensitivity subcarriers may then be used to derive a respiratory analysis based on inhalation and exhalation detection (such as respiratory rate).

[0022] Non-Patent Document 4 provides another example of respiration rate and heart rate estimation using CSI of WLAN signal. Diagram 700 of FIG. 7A shows the CSI phase difference sequence pattern after data calibration. It can be seen that the adjacent subcarriers of subcarrier 20 have higher sensitivity to respiration signal. And the mean absolute deviation of CSI phase difference data of subcarrier 19 is the largest, as shown in diagram 702 of FIG. 7B. As shown in diagram 704 of FIG. 7C, a fast fourier transform (FFT) based method is applied to a selected subcarrier (e.g., subcarrier 19) to estimate the heart rate. After finding the peak of the FFT, an inverse FFT is performed using three bins including the peak bin and its two adjacent bins to obtain a complex time domain signal.

[0023] Non-Patent Document 5 provides an example of human motion sensing using WLAN CSI and shows that for a multi-input multi-output (MIMO) WiFi system, there is always a variation among different subcarriers when a person moves, since signals undergo different attenuation across frequency bands. Diagram 800 in FIG. 8 shows an example of this phenomenon. For clarity, only 13 representative subcarriers are considered. From FIG. 8, the authors find that the response of some subcarriers to human motion is similar, such as the five subcarriers plotted with solid lines (see reference number 802). In their work, the authors call these subcarriers patterns. The authors also find that different patterns respond diversely to the environment, as shown by the dashed line (see reference number 804), solid line (see reference number 802), and dotted line (see reference number 806), respectively. A motion-sensitive pattern is less stable in a static environment, so if an oversensitive subcarrier is selected, the slight fluctuations caused by human motion are more likely to be buried in noise. Therefore, the oversensitive subcarriers are discarded, and from the remaining subcarriers, subcarrier clusters with high similarity are selected for motion detection. Therefore, Non-Patent Document 5 emphasizes that the subcarriers of interest can be extended to a group of subcarriers of interest.

[0024] As discussed above and shown in FIG. 2, 11ax and 11be (baseline for sub-7GHz 11bf) only support Ng=4 and Ng=16, and the index of the reported subcarrier is fixed by the standard. Assuming that 11bf adopts the same Ng value, if a high value is selected, the CSI feedback may miss many subcarriers of interest, and if a low value is selected, the overhead of the CSI feedback is large. For example, referring to diagram 900 in FIG. 9, the unlabeled lines represent the subcarriers selected for feedback based on the indicated Ng value, and it can be seen that if a high Ng value is used and if the index of the subcarrier of interest is not among the indexes listed in the 802.11 specification for the indicated Ng value, the subcarriers of interest 902, 904, 906, and 908 may be missed and not reported. Therefore, it is desired to propose a more flexible subcarrier selection / reporting scheme and related signaling while keeping the overhead of the CSI feedback low.

[0025] For CSI feedback reporting, a more dynamic range of Ng can be standardized, which is different from the value used for compressed beamforming feedback matrix reporting. For example, using 3 bits for Ng, 8 different values ​​of Ng can be signaled. An exemplary set of subcarriers reported in a 320 MHz channel is shown in table 1000 of FIG. 10. It will be understood that subcarrier indexes for other applicable channel widths other than 320 MHz can be derived similarly, and larger values ​​of Ng are only applicable to wider channels (e.g., 320 MHz). Therefore, the finest Ng value can be selected based on table 1000 so that all subcarriers of interest are included in the CSI measurement report. However, in this case, the feedback size will increase, especially if the index of the subcarrier of interest is not divisible by 2, which means that an Ng value of 1 needs to be selected.

[0026] Referring to diagram 1100 of FIG. 11, during an initial sounding session 1106, the initiator STA 1102 may perform one or more rounds of channel sounding to collect one or more sets of channel information feedback and use these to select subcarriers of interest as described above. Subcarriers of interest are defined as a subset of subcarriers (out of the set of all subcarriers in the channel bandwidth) for which channel information feedback is considered to be of special interest to the initiator STA and / or to an application that utilizes the channel information. The channel information feedback may be channel state information (CSI) feedback or compressed / uncompressed beamforming feedback. During a subsequent sounding session 1108, the initiator STA 1102 may indicate the subcarrier indexes for which channel information feedback is requested. Thus, the responder / receiver 1104 includes only channel information feedback for the indicated subcarriers in the measurement report. This may be referred to as subcarrier selective feedback. Thus, channel information feedback may be included in the measurement report frame 1110 (sent from the responder 1104 to the initiator 1102) only for the indicated subcarrier indexes.

[0027] 12A shows an example flowchart 1200 of the procedure of the initiator STA. The process starts at step 1202. At step 1204, channel sounding is performed over the entire channel, and subcarrier selection is performed based on channel information feedback received from the responder STA. At step 1206, channel sounding is performed over the entire channel or a subset of the channel, and a channel sounding announcement requests channel information feedback from the responder STA for the selected subcarriers. At step 1208, the initiator STA receives channel information feedback for the selected subcarriers from the responder STA. The process ends at step 1210.

[0028] 12B shows an example flow chart 1212 of the procedure of the responder STA. The process starts at step 1214. At step 1216, a channel sounding announcement is received from the initiator STA requesting channel information feedback for selected subcarriers. At step 1218, channel measurements are performed over the entire channel or a subset of the channel, and channel information feedback for the selected subcarriers is prepared. At step 1220, the responder STA transmits the prepared channel information feedback for the selected subcarriers to the initiator STA. The process ends at step 1222.

[0029] In embodiment E1, referring to the sensing measurement diagram 1300 of FIG. 13 during an initial phase (e.g., subcarrier selection phase 1306), the initiator 1302 may perform one or more rounds of sounding (e.g., using a non-trigger-based (TB) sounding sequence) and collect one or more rounds of complete CSI feedback (e.g., for all subcarriers using Ng=1), and then the initiator 1302 may apply an application-specific scheme to select subcarriers of interest, as described above. Other methods may also be used to select subcarriers of interest, for example, for respiration analysis, the respiration energy ratio (RER) is a common parameter for selecting subcarriers of interest. The respiration energy ratio (RER) is defined as the ratio of the amount of energy in the respiration frequency band to the total energy of the spectrum. Empirically, the RER can be calculated using a fast Fourier transform (FFT). To improve the estimation accuracy, subcarriers with low RER or variance greater than a certain percentile are discarded. RER can also be expressed as breathing-to-noise ratio (BNR), which is defined as the ratio of breathing energy to total energy. Depending on the sensing application, the location (location in frequency) of the subcarriers of interest and the distance between two nearest subcarriers of interest may be different in different segments of the sensed channel. Some segments may be populated with many subcarriers of interest, while other segments may be populated with relatively few or none at all. In order to collect CSI feedback from as many subcarriers of interest as possible while keeping the overhead of CSI feedback low, during later phases (e.g., sensing phase 1308), the initiator STA 1302 implicitly indicates the subcarrier indexes for which CSI feedback is requested by specifying different Ng values ​​for different segments of the channel.A segment of a channel may be a resource unit (RU) or multi-RU (MRU), or may be a subchannel (e.g., 20 MHz / 40 MHz). For example, a 160 MHz channel may be divided into 8 segments, each of which is a 242-tone RU, or into 4 segments, each of which is a 40 MHz subchannel. The responder / receiver STA 1304 then includes CSI feedback in the Sensing Measurement Report frame 1310 only for subcarriers selected based on the Ng values ​​of the different segments. Also, the subcarriers of interest may vary over time, and the initiator STA 1302 may need to periodically perform full CSI feedback and re-perform subcarrier selection. Although not shown in FIG. 13, different phases may be negotiated as different measurement setups, each identified by a different measurement setup ID. In addition, the sensing NDP in FIG. 13 may also be referred to as an I2R NDP, and although not shown in the figure, the responder STA 1304 may transmit an R2I NDP within SIFS from the end of reception of the I2R NDP, and finally, may transmit a Sensing Measurement Report frame conveying CSI feedback measured based on the I2R NDP.

[0030] In this disclosure, we propose that even for non-TB sounding sequences, a sensing initiator is allowed to request partial-bandwidth CSI feedback from a single sensing responder STA. Note, however, that this is not allowed for HE / EHT STAs in the case of compressed beamforming feedback according to the IEEE 802.11 specification.

[0031] In embodiment E1, the initiator may indicate different Ng values ​​for different segments in the sensing NDPA, e.g., sensing NDPA frame 1400 of FIG. 14. The Ng values ​​for the segments are indicated as a list of Ng_index values ​​in the Ng List subfield 1408 in the Ng Parameters field 1404 in the STA Info List field 1402 of the sensing NDPA frame 1400. The RU Size subfield 1406 in the Ng Parameters field 1404 indicates the size of the segments into which the RU / MRUs signaled in the Partial BW Info field 1410 are evenly divided for the purpose of Ng differentiated CSI feedback. An exemplary encoding of the RU Size field 1406 is shown in table 1500 of FIG. 15A. Using different Ng values ​​for different segments of the channel during sounding feedback is known as Ng differentiated CSI feedback. For practical purposes, the minimum segment is sometimes limited to 242 tone RU (=20 MHz).

[0032] The size of the Ng List subfield 1408 depends on the number of segments into which the RU / MRU indicated in the Partial BW Info subfield 1410 is divided, and the Ng value of each segment is indicated by a corresponding Ng_exponent subfield in the Ng List subfield 1408, e.g., each Ng_exponent subfield uses 3 bits. The Ng_exponent subfield is included in the Ng List subfield only for channel segments for which feedback is indicated to be requested in the Partial BW Info field 1410. In other words, for channel segments for which feedback is not requested according to the Partial BW Info field, the Ng_exponent subfield is not included in the Ng List subfield. Here, it is assumed that the Partial BW Info field has the same format and encoding as the Partial BW Info field of the EHT NDPA frame 300 of FIG. 3. In sensing NDPA, the Partial BW Info field may also be referred to as the Feedback BW Info field to better reflect its usage in sensing. When Ng differentiated CSI feedback is not applied (e.g., in the initial subcarrier selection phase), a single Ng value may be applied to the entire feedback RU / subchannel, the RU Size subfield 1406 indicates an RU / MRU size equal to or larger than the entire feedback RU / MRU size, and the Ng List subfield 1408 includes a single Ng_exponent subfield 1412 indicating a single Ng value.For example, if the feedback MU / MRU indicated in the Partial BW Info field 1410 is 484+242MRU and a single Ng value is applied, the Ng Parameters field 1404 includes a single Ng_exponent subfield 1412 (e.g., =4) and the RU Size subfield 1406 indicates (5 or 996 tone RU). Alternatively, the Ng Parameters subfield 1404 may be replaced with a single subfield indicating an Ng value for the case where Ng differentiated CSI feedback is not applied. In this case, a separate field (e.g., using one bit) may indicate whether Ng differentiated CSI feedback is not applied. The Ng List subfield 1408 indicates an Ng value for each segment for which feedback is requested. Examples of Ng values ​​to be shown are shown in the exemplary Ng List subfield 1414, and an example encoding of the Ng_exponent field 1412 is shown in table 1502 of FIG. 15B.

[0033] In embodiment E1, for each channel segment, the responder STA may include CSI feedback for the indicated subcarriers (according to the Ng value per segment) in a measurement report, such as the Sensing Measurement Report frame 1600 of FIG. 16. The encoding and meaning of the Ng Parameters subfield 1604 of the Sensing Measurement Report frame 1600 is the same as that of the Sensing NDPA (e.g., the Sensing NDPA frame 1400). The Ng value of the segment is indicated as a list of Ng_index values ​​in the Ng List subfield 1608 in the Ng Parameters field 1604 in the Sensing Control field 1602 of the Sensing Measurement Report frame 1600. The RU Size subfield 1606 of the Ng Parameters field 1604 indicates the size of segments into which the RU / MRU signaled in the Partial BW Info field 1610 is equally divided for the purpose of Ng differentiated CSI feedback. The size of the Ng List subfield 1608 depends on the number of segments into which the RU / MRU indicated in the Partial BW Info subfield 1610 is divided, and is indicated by the Ng value of each segment indicated by a corresponding Ng_exponent subfield in the Ng List subfield 1604, e.g., each Ng_exponent field using 3 bits.

[0034] Furthermore, the size of the Sensing Measurement Report field (e.g., Sensing Measurement Report field 1612 of Sensing Measurement Report frame 1600) is shown in table 1700 of FIG. 17. The index of subcarrier k in the mth segment (e.g., scidx_mth_segment(k)) for various values ​​of the Ng parameter and various operating channel bandwidths is defined in table 1800 of FIG. 18 for a segment size of 242 tones or 484 tones, and in table 1900 of FIG. 19 for a segment size of 996 tones or 2*996 tones. The values ​​of scidx_mth_segment(k) defined in tables 1800 and 1900 indicate the exact subcarrier index corresponding to the subcarrier k reported for the mth segment. Ns_m is the number of subcarriers for which a CSI matrix is ​​reported in the mth segment and is a function of the grouping parameter Ng for that segment. For each group of Ng adjacent subcarriers, only a single CSI matrix is ​​reported. The total number of reported subcarriers is

number

[0035] Referring to table 1800, subcarrier indexes of various channel bandwidths for various values ​​of Ng are listed when the segment size is 242 tones or 484 tones. [x,y,z] represents a sequence of indexes, where x, y, and z represent the RU start index (e.g., the lowest index number in the RU), the step, and the RU end index (e.g., the highest index number in the RU). The grouping parameter Ng shown in the table indicates an arithmetic progression in Ng units. When the segment size is 242 tones, the 242-tone RU index corresponds to the segment index, i.e., the first segment is the same as the 242-tone RU with 242-tone RU index 1, and so on. When the segment size is 484 tones, the first segment is composed of two 242-tone RUs with 242-tone RU indexes 1 and 2, and so on. Selected combinations of 242-tone RU index and Ng are shown in table 1800, and other combinations are omitted. For a 242-tone RU, the subcarrier index is calculated using: When Ng=1, all data and pilot subcarriers as described in the applicable 802.11 specification (e.g., 802.11ax (HE) or 802.11be (EHT)) are included, e.g., for a 160 MHz EHT PPDU, the first 242 tones RU=[-1012:-771] and the second 242 tones RU=[-765:-524]. When Ng=x (>1), among the subcarriers with Ng=1, subcarrier indices are selected such that the lowest index is always included (e.g., -1012), and starting from the lowest index, subcarriers are selected at a distance of the Ng value (e.g., x). Null subcarriers as described in the specification (e.g., ±254, ±255, ±256, ±257, ±258) are excluded. When the segment size is 484 tones, the subcarrier index is based on two consecutive 242-tone RUs listed in table 1800, for example, the primary 40 MHz segment is based on 242-tone RU indexes 1 and 2, etc.Table 1800 is based on the EHT tone plan and assumes that the EHT sounding NDP is used for sensing measurements. When the HE tone plan and HE sounding PPDU are used and the Partial BW Info subfield of the sensing NDPA frame and the sensing measurement report frame indicate the start RU index and the end RU index, the subcarrier index for Ng values ​​other than 4 and 16 is expressed similarly to Table 9-91c-1 (subcarrier indexes scidx(0) and scidx(Ns-1) when Ng=4) and Table 9-91d- (subcarrier indexes scidx(0) and scidx(Ns-1) when Ng=16) in the non-patent document. When all bits in the Partial BW Info subfield corresponding to an 80 MHz subblock are set to 1 and the RU Size subfield in the Ng parameters subfield indicates a 242-tone RU, each 80 MHz subblock can be divided into four 242-tone segments, and a tone plan based on the 242-tone RU (e.g., as shown in table 1800) is used to select subcarriers with different values ​​of Ng within each 242-tone segment.

[0036] Referring to table 1900, subcarrier indexes for various channel bandwidths for various values ​​of Ng when the segment size is 996 tones or 2*996 tones are listed. The grouping parameter Ng shown in the table indicates an arithmetic progression in Ng units. Here, only the subcarrier indexes reported for selected Ng values ​​are listed, but the subcarrier indexes for other values ​​of Ng can be derived similarly. Table 1900 is based on the EHT tone plan, assuming that an EHT sounding NDP is used for sensing measurements and that the RU Size subfield of the Ng parameters subfield indicates 996 tone RUs or more. When the segment size is 2*996 tones, the subcarrier index is based on two consecutive 996 tone RUs listed in Table 4B, for example, the primary 160 MHz segment is based on 996 tone RU indexes 1 and 2, and the secondary 160 MHz segment is based on 996 tone RU indexes 3 and 4. A segment size of 996 tones or greater may only be used when all bits in the Partial BW Info subfield corresponding to an 80 MHz subblock are set to 1. When all bits in the Partial BW Info subfield corresponding to an 80 MHz subblock are not set to 1, a segment size of 242 tones or 484 tones shall be used, with the subcarrier index based on the associated 242-tone RU listed in Table 1800.

[0037] The CSI matrix (for subcarrier k) may have the following structure:

[0038] For each reported subcarrier k, include { 3-bit carrier matrix magnitude (MH(k)) For each of the Nr rows of each CSI matrix, in the order (1,...,Nr) { CSI matrix Heff It contains Nc complex coefficients of H eff Each element of contains the real part of the element (Nb bits) and the imaginary part of the element (Nb bits), in that order. } } where the total size in bits of the CSI feedback (excluding the SNR / RSSI fields) = Ns × (3 + 2 × Nb × Nc × M), where the total number of subcarriers being reported

number

[0039] 20A and 20B show an example diagram of a sensing NDPA frame 2000 and an example diagram of corresponding reported subcarriers 2016 based on a sensing bandwidth of 160 MHz according to embodiment E1. The feedback RU / MRU size is indicated by the Partial BW Info field 2002 as "011111111", or 2*996 tone RU. For Ng parameters, the RU size is indicated by the RU Size subfield 2006 of the Ng Parameters field 2004 as 3 (i.e., 242 tones), e.g., the 2*996 tone RU is divided into 8 segments, each segment being a 242 tone (subcarrier) RU. In this case, the subcarrier index is given by the first 8 RU indexes of table 1800, e.g., 242 tone RU indexes 1 to 8, which correspond to the 160 MHz row. Thus, eight different Ng values ​​(2, 16, 16, 16, 16, 16, 1, 4) are shown for each of the eight 242-tone RUs. In this example, the penultimate RU 2022 (Ng_exponent value is indicated as "0" in the Ng List subfield 2012, so Ng value = 2^0 = 1), the first RU 2018 (Ng_exponent value is indicated as "1" in the Ng List subfield 2008, so Ng value = 2^1 = 2), and the last RU 2024 (Ng_exponent value is indicated as "2" in the Ng List subfield 2014, so Ng value = 2^2 = 4) are of particular interest (in descending order) to the sensing application, so smaller Ng values ​​are indicated for these RUs, while the second through sixth RUs are not of particular interest (and therefore larger Ng values ​​are indicated for these RUs, e.g., Ng value is indicated as 4 in the Ng List subfield 2010 for the second RU 2020, so Ng value = 2^4 = 16).Assuming that 3 bits are used to signal the RU size and Ng_exponent in the sensing NDPA frame 2000 and the number of segments reported is 8 (or 160 MHz / 20), the overhead of Ng signaling may be the number of extra bits required to signal the Ng value, which is calculated as 3+(3*8)=27 bits. Furthermore, the total number of subcarriers reported (Ns)=122+18×5+244+64=520, which, in the form of omitted subcarriers, is a saving of 1988-520=1468 (compared to the case where all subcarriers are reported, i.e., assuming Ng=1 for an RU of 2*996 tones). Assuming Nb=8, Nc=3, Nr=3, this advantageously leads to an overhead reduction of (1468×(3+2×8×3×3)-27) bits=26,971 octets.

[0040] 21A and 21B show an example diagram of a sensing NDPA frame 2100 and an example diagram of corresponding reported subcarriers 2114 based on a sensing bandwidth of 320 MHz according to embodiment E1. The feedback RU / MRU size is indicated by the partial BW information field 2102 as "111001111", or a 3*996 tone MRU with the second 996 tone RU punctured. For the Ng parameters, the RU size is indicated by the RU Size subfield 2106 of the Ng Parameters field 2104 as 5 (i.e., 996 tones), e.g., the 3*996 tone feedback MRU is divided into three segments, each segment being a 996 tone (subcarrier) RU. In this case, the subcarrier index is indicated in the first, third, and fourth 996 tone RU index of table 1900, corresponding to 320 MHz. Thus, three different Ng values ​​(2, 1, 4) are shown for each of the three 996-tone RUs. For example, the Ng_exponent value for the penultimate RU 2118 is indicated as "0" in the Ng list subfield 2110, resulting in an Ng value of 2^0=1, the Ng_exponent value for the first RU 2116 is indicated as "1" in the Ng list subfield 2108, resulting in an Ng value of 2^1=2, and the Ng_exponent value for the last RU 2120 is indicated as "2" in the Ng list subfield 2112, resulting in an Ng value of 2^2=4. Assuming that 3 bits are used to signal the RU size and Ng_exponent in the sensing NDPA frame 2000 and the number of segments reported is 3 (or 3*996 / 996), the overhead of Ng signaling would be the number of extra bits required to signal the Ng value, calculated as 3+(3*3)=12 bits. Furthermore, the total number of reported subcarriers (Ns)=122+244+64=430, resulting in a savings of 2982-430=2552 in the omitted carrier form (assuming Ng=1 for a 3*996 tone MRU).Assuming Nb = 8, Nc = 3, and Nr = 3, this results in an overhead reduction of (2552 x (3 + 2 x 8 x 3 x 3) - 12) bits = 46,891.5 octets, which is advantageous.

[0041] As an alternative to the sensing NDPA frame, the initiator STA may also indicate the Ng parameters during the sensing session setup itself (in a Sensing Session Setup Request frame) if the Ng parameters are expected to be fixed throughout the sensing session. For example, the Sensing Session Setup Request frame 2200 of FIG. 22 may indicate the Ng parameters in the Ng List subfield 2204 of the Ng Parameters field 2202 in a manner similar to that shown for the Sensing Measurement Report frame 1600. Alternatively, the initiator STA may also indicate the Ng parameters during the sensing measurement setup (in a Sensing Measurement Setup Request frame) if the Ng parameters are expected to be fixed throughout the sensing measurement instance. For example, the sensing measurement setup request frame 2300 of FIG. 23 may indicate the Ng parameters in the Ng list subfield 2304 of the Ng parameters field 2302 in a manner similar to that shown for the sensing measurement report frame 1600 .

[0042] An exemplary respiration estimation WLAN sensing application that uses a model-based algorithm (e.g., based on a Fresnel zone model) to detect and estimate a person's respiration rate is shown in diagram 2400 of Figure 24. The Fresnel zone 2406 is one of a series of elliptical regions of space in the space between and around a wireless transmitter 2402 and a wireless receiver 2404. The Fresnel reflection model in an indoor environment can be used to estimate a person's respiration rate using a WLAN sensing system.

[0043] The curve of CSI amplitude across subcarriers may be suitable for use in human presence detection due to its high sensitivity to environmental changes. The Signal Tendency Index (STI) of the CSI amplitude data can provide a quantitative comparison of the similarity of the shape of the CSI amplitude curve between an empty room and a room with one or more people present. A low STI score indicates that the room is empty, while a high STI score indicates that the room has one or more people. Since this module needs to be running all the time, only coarse-grained CSI feedback (e.g., using Ng=16 as shown in Figure 25) across the entire channel (e.g., 160 MHz as shown in Figure 25) can be used.

[0044] Once the presence of people is detected, medium-grained CSI feedback across the channels (e.g., using Ng=4, or Ng=2, as shown in diagram 2700 of the CSI feedback sensing procedure in FIG. 27A) is collected, and techniques such as power spectral density (PSD) are used to analyze the time series of CSI amplitudes in the frequency domain to determine how many people are present in the room, and the subcarriers most sensitive to the breathing rate of each of the five people are selected. Since different people have different natural breathing rates, the index of the subcarrier most sensitive to each person's breathing rate may vary greatly. For example, referring to CSI amplitude curves 2600 and 2602 in FIG. 26, the subcarriers in the first 242-tone RU (i.e., the first 20 MHz subchannel) may be most sensitive to individuals with low breathing rates (e.g., as shown in CSI amplitude curve 2600 for an individual with a low breathing rate of 8 bpm), and the subcarriers in the last 242-tone RU (i.e., the eighth 20 MHz subchannel) may be most sensitive to individuals with high breathing rates (e.g., as shown in CSI amplitude curve 2602 for an individual with a high breathing rate of 18 bpm).

[0045] Finally, fine-grained CSI feedback is performed at least for the channel segments where the subcarriers of interest are located (e.g., using Ng=1, or Ng=2, as shown in the diagram 2702 of the fine-grained CSI feedback sensing procedure of FIG. 27B). Meanwhile, only coarse-grained CSI feedback is required for the remaining channel segments, or those channel segments can be omitted completely in the CSI feedback (e.g., using Ng=16, as shown in the diagram 2702 of the fine-grained CSI feedback sensing procedure). To estimate the respiration rate, a technique such as peak detection is used on the CSI amplitude curve. Each peak and valley in the CSI amplitude curve of the selected subcarrier corresponds to the start of inspiration and expiration, respectively. By measuring the distance between two peaks (or two valleys), the respiration rate can be calculated.

[0046] FIG. 28 shows an example flowchart 2800 of a respiration estimation sensing process according to embodiment E1. The process starts at step 2802. At step 2804, coarse-grained CSI feedback (e.g., Ng=16) is performed over the entire channel. At step 2806, human presence detection is performed using the coarse-grained CSI feedback (e.g., using STI comparison). At step 2808, it is determined whether a human presence is detected based on the coarse-grained CSI feedback. If it is determined that no human presence is present, the process returns to step 2804. Otherwise, the process proceeds to step 2810, where fine-grained CSI feedback (e.g., Ng=2) is collected over the entire channel, the number of people is identified, and the optimal subcarrier for respiration estimation is identified for each detected person. At step 2812, fine-grained CSI feedback (e.g., Ng=2) is collected over the subchannels including the subcarriers of interest. Step 2812 can be repeated multiple times to obtain fine-grained CSI feedback over a period of time with a sufficiently high sampling rate (e.g., 20 times per second for several minutes). In step 2814, respiration estimation (in units of breaths per minute or bpm) is performed using the CSI feedback of the subcarriers of interest. The process then ends in step 2816.

[0047] While the above are examples of how subcarrier selective feedback can be used to obtain fine-grained CSI feedback for sensing applications while keeping feedback overhead low, it will be appreciated that subcarrier selective feedback can be applied in a similar manner to other sensing applications, similar to beamforming feedback in communications applications.

[0048] In embodiment E2, the initiator STA may indicate different Ng values ​​for different segments by including multiple STA Info fields with the AID11 field set to the same STA 1 AID, with each STA Info field specifying a different segment of the channel and the same or different Ng value for that segment. HE / EHT currently indicates that an HE / EHT NDP announcement frame must not include multiple STA Info fields with the same value in the AID11 subfield. However, this rule may be relaxed in future 802.11 amendments (e.g., 11bf). For example, the sensing NDPA frame 2900 of FIG. 29A may be utilized for the example described with respect to FIGS. 20A and 20B, where the STA Info list field 2902 includes multiple STA Info fields with each AID11 field 2904 set to the same AID of STA 1, and each STA Info field specifies a different segment of the channel in each Partial BW Info field 2906 and the same or different Ng values ​​in each Ng field 2908 for the corresponding segments.

[0049] Furthermore, the responder / receiver may generate multiple sensing measurement reports, each report carrying CSI feedback for one segment, a Partial BW Info field indicating the channel segment, and an Ng field 2914 indicating the Ng value used for that segment. Multiple measurement report fields may be aggregated into a Sensing Measurement Report frame (e.g., Sensing Measurement Report frame 2910 of FIG. 29B), or multiple sensing measurement report frames (each carrying one sensing measurement report field) may be aggregated into a single A-MDPU. Advantageously, such signaling achieves Ng differentiated CSI feedback.

[0050] In embodiment E3, the Partial BW Info subfield (in the Sensing NDPA frame and the Sensing Measurement Report frame) can be configured with full flexibility to indicate any combination of RU / MRUs in the operating bandwidth (not limited to the values ​​currently defined in the EHT specification, since the EHT specification only allows certain values ​​of the Partial BW Info field). For example, referring to the Partial BW Info field 3000 of FIG. 30A when bit B0 3002 is set to "0", each of the following 8 bits set to "1" indicates whether to request CSI feedback from each of the 242 tone RUs in the 160 MHz channel. If the operating bandwidth is narrower than 160 MHz (e.g., 80 MHz), only the first 4 bits (e.g., bits B1-B4 of the Partial BW Info field 3000) can be set to 1, and the remaining bits are reserved. The bitmap can also be extended by another 8 bits to cover up to 320 MHz with a granularity of 242 tones. Bits B9-B17 of the Partial BW Info field 3000 can indicate whether CSI feedback is requested for each of the 242 tone RUs. With further reference to the Partial BW Info field 3004 of FIG. 30B, when bit B0 3008 is set to "1", each of the following 8 bits are set to "1" to indicate whether CSI feedback is requested from each of the 484 tone RUs in the 320 MHz channel.

[0051] FIG. 31 shows a table 3100 describing additional settings of the BW, Partial BW Info subfields of the sensing NDPA frame (assuming a 9-bit field) in addition to the settings already allowed in the EHT NDPA frame according to embodiment E3. Referring to the Partial BW Info subfield values ​​(B0 B1 B2 B3 B4 B5 B6 B7 B8) in binary format as shown in table 3100, for each bandwidth of the sensing NDPA, only the Partial BW Info subfield values ​​specific to that bandwidth (i.e., not already listed for a narrower bandwidth) are listed in the table. The proposed Partial BW Info values ​​allow full flexibility in terms of selecting any combination of subchannels for feedback from within the operating channel bandwidth. As an example, if the Partial BW Info field is set to 010001000 and the bandwidth of the operating channel is 160 MHz, the initiator STA is requesting feedback only for the first and fifth 242-tone RUs.

[0052] FIG. 32 shows an example diagram of a sensing NDPA frame 3200 according to embodiment E3. In this case, the Partial BW Info field can flexibly signal any combination of subchannels (or segments) for which feedback is requested, with the size of the segments indicated by B0 in the Partial BW Info field (0 for 242-tone RU, 1 for 484-tone RU). Only the Ng_exponent is explicitly signaled in the sensing NDPA frame 3200 (e.g., Ng List subfield 3202) and the corresponding Sensing Measurement Report frame, with one Ng_exponent subfield for each segment for which feedback is requested. The number of segments and the corresponding number of Ng_exponent subfields are inferred from the Partial BW Info field 3204. Referring to the example of Ng differentiated CSI feedback based on the Partial BW Info and Ng List subfields 3300 of the sensing NDPA frame or Sensing Measurement Report frame of FIG. 33 with a sensing bandwidth of 160 MHz and the corresponding feedback process 3312, the feedback segment is indicated by the Partial BW Info field 3302 as “010001001” or three 242-tone RUs.Thus, three different Ng values ​​(2, 1, 4) are indicated, for example, for the first, fifth, and eighth 242-tone RUs, where, for example, the Ng_index of the first RU is indicated in subfield 3306 of the Ng list field 3304 of the first RU 3314 as "1" such that the Ng value is 2^1=2, the Ng_index of the fifth RU is indicated in subfield 3308 of the Ng list field 3304 of the fifth RU 3316 as "0" such that the Ng value is 2^0=1, and the Ng_index of the eighth RU is indicated in subfield 3310 of the Ng list field 3304 of the eighth RU 3318 as "2" such that the Ng value is 2^2=4. Advantageously, Ng differentiated CSI feedback signaling is simple.

[0053] Referring to another example of Ng differentiated CSI feedback based on the Partial BW Info and Ng List subfields 3400 of the Sensing NDPA frame or Sensing Measurement Report frame and corresponding feedback process 3408 of FIG. 34, where the subcarriers of interest are restricted to a single 242-tone RU segment and the sensing NDPA bandwidth is 160 MHz, the feedback size is indicated as "000001000" or one 242-tone RU by the Partial BW Info field 3402. Thus, for the fifth 242-tone RU, a single Ng value (4) is indicated, e.g., the Ng_index of the fifth RU is indicated as "2" in the subfield 3406 of the Ng List field 3304 of the fifth RU 3310, resulting in an Ng value of 2^2=4. Here, we assume that Ng=4 is the smallest possible Ng value (defined in the 11bf specification). In such a case, the responder may also report the average CSI value of a group of subcarriers (e.g., a group of 4 for Ng=4) to capture the channel information of the omitted subcarriers as well. The request for such an averaging operation of CSI values ​​of a group of subcarriers may also be signaled by the initiator, for example, in a sensing NDPA frame.

[0054] In embodiment E4, when the HE NDP is used as a measurement PPDU, such as a sensing NDP, the Partial BW Info subfield in the corresponding sensing NDPA frame and sensing measurement report frame is based on the HE format (e.g., indicating RU start index, RU end index). Figure 35 shows an example diagram of a sensing NDPA frame 3500 according to embodiment E4. The RU Start Index subfield 3504 and the RU End Index subfield 3506 of the Partial BW Info field 3502 indicate the first 26-tone RU and the last 26-tone RU for which the initiator STA is requesting feedback, respectively. The following Ng parameter signaling (e.g., Ng parameters field 3508) can be used in both the sensing NDPA and sensing measurement report frames. A Default Ng field 3510 may indicate an Ng value (using the same encoding as the Ng_exponent subfield) to be applied to all feedback RUs / MRUs except those covered by the subchannels indicated in an Ng Bitmap subfield 3512. The encoding of the Ng Bitmap subfield 3512 may be the same as that of the Partial BW Info field 3204 described in embodiment E3, except that each of the 8 bits except B0 set to 1 indicates the presence of an Ng_exponent subfield in the corresponding Ng List subfield 3514, which conveys an Ng value different from the default Ng value for each of the 242-tone / 484-tone RUs in the 160 / 320 MHz channel.The Ng List subfield 3514 indicates the Ng values ​​(as a list of Ng_exponent values) for the subchannels indicated by the Ng Bitmap subfield 3512. Although not shown in the figure, the NDPA frame 3500 may also include a STA Information List with the AID11 field set to 2047, in which case the Partial BW Info field of the STA Information List is replaced with a Disallowed Subchannel Bitmap, with the lowest numbered bit of the Disallowed Subchannel Bitmap subfield corresponding to the 20 MHz subchannel that is within the BSS bandwidth and has the lowest frequency among the set of all 20 MHz subchannels within the BSS bandwidth. Each successive bit of the bitmap corresponds to the next higher frequency 20 MHz subchannel. The bit in the bitmap is set to 1 to indicate that no energy is present in the HE sounding NDP associated with this NDP announcement frame for the corresponding 20 MHz subchannel, and the corresponding bit in the Ng Bitmap subfield of all other STA information lists is set to 0 to indicate that the Ng_exponent subfield is not present for this subchannel. For each disallowed 20 MHz subchannel, the 242-tone RU that is closest in frequency to the 20 MHz subchannel is disallowed. The STA addressed in the NDP announcement frame does not include tones (subcarriers) from the disallowed 242-tone RU when determining the average SNR of the space-time stream and when generating the requested sounding feedback. If the 20 MHz subchannel and its corresponding 242-tone RU are not disallowed, the corresponding bit in the bitmap of the disallowed subchannel is set to 0.

[0055] See an example of Ng differentiated CSI feedback based on the sensing NDPA frame 3600 and corresponding feedback process 3622 of FIG. 36, where the sensing bandwidth is 160 MHz. The feedback RUs are indicated by the Partial BW Info field 3602 as the 10th 26-tone RU (indicated by a value of “9” in the RU Start Index subfield 3606 of the Partial BW Info field 3602) to the 65th 26-tone RU (indicated by a value of “64” in the RU End Index subfield 3608 of the Partial BW Info field 3602), or the 2nd to 7th 242-tone RUs. The default Ng indicated in the default Ng subfield is “4”, which means that the default Ng value is 2^4=16. This Ng value applies to the 3rd, 4th, and 5th 242-tone RUs 3626. B0 of the Ng Bitmap field 3612 is set to 0 to indicate a granularity of 20 MHz, and B2, B6, and B7 are set to 1 to indicate that non-default Ng values ​​are indicated in the Ng List subfields 3616, 3618, and 3620 corresponding to the sixth 242-tone RU 3628, the second 242-tone RU 3624, and the seventh 242-tone RU 3630, respectively.

[0056] In this example, the sixth 242-tone RU 3628, the second 242-tone RU 3624, and the seventh 242-tone RU 3630 are of special interest (in descending order) for sensing applications and therefore have small values ​​of Ng, while the third through fifth 242-tone RUs 3626 are not of special interest (and therefore have large values ​​of Ng). The subcarrier index is based on Table 9-122 of Non-Patent Document 6 (subcarrier indexes scidx(0) and scidx(Ns-1) for Ng=4) corresponding to the 160 MHz column.

[0057] In embodiment E5, the initiator may indicate, along with the grouping parameter Ng, a "subcarrier_offset" that is the difference between the index of the defined subcarrier (e.g., as defined in the Ng value specification) and the subcarrier of interest. An example of this difference is shown in diagram 3700 of FIG. 37 as subcarrier offset 3704 between the defined subcarrier 3702 and the subcarrier of interest 3706. For z=0 to Ns-1, scidx_new(i)=scidx(i)+subcarrier_offset (referred to herein as equation E5-1), where scidx() returns a predefined subcarrier index (e.g., baseline, or as defined in table 1800 of FIG. 18 and table 1900 of FIG. 19) for a particular Ng value, and Ns is the total number of subcarriers being reported. The value of subcarrier_offset shall be less than the value of Ng. If Equation E5-1 returns a subcarrier index that is not within the valid index range (e.g., greater than the DC tone or the maximum index of that RU / MRU), scidx_new(i) returns the previous valid subcarrier index. This method may be used when the subcarriers of interest are uniformly distributed and follow the same pattern across the channel, e.g., at the same distance from the defined subcarrier index. An example table 3800 showing reported subcarriers for feedback on a 996 tone RU (80 MHz) for two values ​​of subcarrier_offset (2, 8) is shown in FIG. 38. The entry in Scidx_new() for subcarrier_offset=8 and Ng=4 is empty because the offset value (8) is greater than the Ng value.

[0058] 39A and 39B, the subcarrier_offset may be indicated in a subcarrier_offset field 3902 of a sensing NDPA frame 3900 and a subcarrier_offset field 3906 of a sensing measurement report frame 3904. An advantageous effect is that some flexibility in subcarrier selection may be achieved with minimal signaling overhead.

[0059] Alternatively, referring to Figures 40A and 40B, instead of indicating a subcarrier_offset value, a list of reported subcarrier indices is indicated in the Subcarrier_List field 4002 (including the Subcarrier_Index_From_First_To_Last subfield) of the Sensing NDPA frame 4000 and in the Subcarrier_List field 4006 (including the Subcarrier_Index_From_First_To_Last subfield) of the Sensing Measurement Report frame 4004 to explicitly indicate the subcarriers to be reported (i.e., the subcarriers for which CSI feedback is requested / provided). Each of the Subcarrier_Index_From_First_To_Last subfields may be 12 bits long and encoded as two's complement numbers (e.g., -2047, 2047). Furthermore, a feedback matrix may be included (e.g., in the Sensing Measurement Report field 4008) only for the subcarrier indices included in the Subcarrier_List field 4006.

[0060] In embodiment E6, Ng differentiated feedback can also be applied to beamforming feedback, in which case it can be referred to as Ng differentiated beamforming (BF) feedback. For example, referring to diagram 4100 of FIG. 41, the beamformer STA 4102 indicates (e.g., in HE / EHT NDPA frame 4106) different Ng values ​​for different segments of the channel for which feedback is requested. In response, the beamformee STA 4104 includes (e.g., in HE / EHT compressed beamforming feedback frame 4108) a compressed beamforming feedback matrix for the reported subcarriers that is selected based on the different Ng values ​​for different segments of the channel for which feedback is requested. Embodiment E6 is specific to communication (i.e., non-sensing) use cases, and although an example is shown in FIG. 41 for an HE / EHT STA, Ng differentiated beamforming may be applied to any existing 802.11 based communication system (11ac / 11ax / 11be / 11lad / 11ay, etc.) that uses channel sounding for transmit beamforming and / or MIMO, including future 802.11 amendments. 42A and 42B, and again considering the example of a HE / EHT STA, the HE / EHT NDPA frame 4200 and the HE / EHT compressed beamforming / CQI frame 4204 can be modified to convey Ng parameters subfields (e.g., Ng parameters subfield 4202 of the HE / EHT NDPA frame 4200 and Ng parameters subfield 4206 of the HE / EHT compressed beamforming / CQI frame 4204) having the same encoding as described in embodiment E1. Additionally, a compressed beamforming feedback matrix may be included in the EHT compressed beamforming report field 4208 of the HE / EHT compressed beamforming / CQI frame 4204 for a subcarrier index selected using the Ng value for each channel segment.

[0061] In embodiment E7, instead of directly indicating the subcarrier index, the initiator can indicate a condition for selecting the reported subcarriers (e.g., subcarriers whose CSI / phase / amplitude value difference from the previous measurement is greater than or equal to a threshold, and other similar values). For example, the selection condition can be indicated in a 2-bit subcarrier selection condition field 4302 of the sensing NDPA frame 4300 of FIG. 43A based on various values ​​and corresponding meanings as shown in table 4400 of FIG. 44. For example, if the subcarrier selection condition field 4302 indicates a value of 0, all subcarriers are selected based on the grouping parameter Ng. If the subcarrier selection condition field 4302 indicates a value of 1, subcarriers having I and Q values ​​whose difference from the previous measurement is greater than a threshold (e.g., the threshold value indicated in the subcarrier selection threshold field 4304 of the sensing NDPA frame 4300) are selected. If the subcarrier selection condition field 4302 indicates a value of 2, then subcarriers having amplitude values ​​whose difference from the previous measurement value exceeds a threshold (e.g., the threshold indicated in the subcarrier selection threshold field 4304 of the sensing NDPA frame 4300) are selected. Furthermore, if the subcarrier selection condition field 4302 indicates a value of 3, then subcarriers having phase values ​​whose difference from the previous measurement value exceeds a threshold (e.g., the threshold indicated in the subcarrier selection threshold field 4304 of the sensing NDPA frame 4300) are selected.The responder may then perform subcarrier selection based on the indicated condition and include only the selected subcarriers in the sensing measurement report, e.g., as a list of subcarrier indices in the subcarrier_list field 4308 of the Sensing Measurement Report frame 4306 of FIG. 43B. Alternatively, instead of a list of subcarrier indices, any of the signaling described above for embodiments E1-E5 may be used by the responder to provide feedback of the selected subcarriers. The responder may also indicate the top 10 or top n subcarriers that match the indicated condition (e.g., high variance). The value of "n" may also be indicated by the initiator. Instead of providing CSI feedback, the responder may also feed back only the result, such as a simple indication, e.g., variance above a threshold for half of the subcarriers. Also, even with Ng differentiated feedback, it is possible to provide subcarrier selection conditions and subcarrier selection thresholds so that different Ng values ​​are applied to different segments of the channel, and the responder STA performs further selection of subcarriers from among the subcarriers selected based on the Ng values ​​of the segments based on the provided subcarrier selection conditions and subcarrier selection thresholds.

[0062] In embodiment E7-1, a dynamic grouping of subcarriers is proposed for CSI feedback, where the DC subcarrier is not included, the edge subcarriers are always included, and the distance is 2 for a given fixed Ng value, provided that the subcarrier index is selected to correspond to the index defined in the specification for the selected Ng value. jAdditional signaling (differentiated subcarrier index=j) is included in the sensing measurement report such that j indicates the distance between two adjacent reported subcarriers. With reference to the sensing NDPA frame 4500 of FIG. 45, a Default Ng field 4502 can be configured to indicate an Ng value applied in a segment with dynamic grouping. The Ng value determines the number of subcarriers reported in that segment. A value of Ng_exponent (e.g., value 7 shown in table 4506) is reserved to indicate that dynamic grouping is applied to the channel segment. The value of Ng_exponent for each segment is indicated in a corresponding field of the Ng_exponent field 4504. Table 4600 of FIG. 46 illustrates Sensing Measurement Report fields for CSI feedback according to embodiment E7-1. The same signaling is also used to indicate dynamic grouping in the Sensing Measurement Report frame. For example, when indicating dynamic grouping for the mth segment (by setting the Ng_exponent field to 7), a Differentiated Subcarrier Index field is included for every two adjacent reported subcarriers in the mth segment, e.g., scidx_mth_Segment(0)-scidx_mth_Segment(1) for the first and second reported subcarriers, and the size of the field is 3 bits. The indicated Differentiated Subcarrier Index is only present for the dynamically grouped mth segment, and the distance between the subcarrier indexes, scidx_mth_Segment(0)-scidx_mth_Segment(1), is 2. j For example, if the differentiated subcarrier index of scidx_mth_Segment(0)-scidx_mth_Segment(1) indicates 3, the difference between the subcarrier indexes of the first reported subcarrier and the second reported subcarrier in the mth segment is 8 (2 3 ).

[0063] FIG. 47 illustrates an example diagram 4700 of the Partial BW Info and Ng Parameters fields in a sensing NDPA frame or Sensing Measurement Report frame for a sensing bandwidth of 320 MHz, and an example diagram 4716 of the corresponding subcarriers on which feedback is reported, according to embodiment E7-1. The feedback RU / MRU size is indicated by the Partial BW Info field 4702 as "111001111" or three 996-tone RUs (first, third, and fourth). In the Ng parameters field 4704, the Default Ng field indicates a value of "2", indicating that Ng=4 for segments with dynamic grouping. The RU size field 4708 indicates a value of "5" (996 tones). For example, a 3*996 feedback MRU is divided into three segments, with each segment being a 996 tone (subcarrier) RU. Ng values ​​(2, 4) are indicated for the first and fourth 996 tone RUs 4718 and 4722 (e.g., indicated in Ng List subfields 4710 and 4714 for the first and fourth 996 tone RUs 4718 and 4722, respectively), while dynamic grouping is indicated as an Ng value of "7" in Ng List subfield 4712 for the third 996 tone RU 4720.Dynamic grouping can be seen in the third 996-tone RU 4720, where the number of subcarriers reported is determined using a default Ng=4, and the value of the differentiated subcarrier index varies between “2” (i.e., difference between subcarrier indexes of differentiated subcarrier index 4724=4), “0” (i.e., difference between subcarrier indexes of differentiated subcarrier indexes 4726 and 4730=1), “5” (i.e., difference between subcarrier indexes of differentiated subcarrier index 4728=32), and “4” (i.e., difference between subcarrier indexes of differentiated subcarrier index 4732=16).

[0064] Thus, subcarrier selective channel information feedback and related signaling can be utilized as described in various embodiments. For example, as shown in embodiments E1, E2, E3, and E4, a single feedback can be sent for a group of Ng subcarriers, where the value of Ng can be different for different segments of the channel. The index of the subcarrier for which the feedback is sent can be implicitly signaled as an offset or explicitly signaled, as shown in embodiment E5. Furthermore, default and non-default Ng values ​​can be shown as shown in embodiment E4, conditions for selecting subcarriers can be shown as shown in embodiment E7, and dynamic grouping of subcarriers for feedback can be shown as in embodiment E7-1.

[0065] FIG. 48 shows a schematic diagram of an apparatus 4800 suitable for sensing and communication according to various embodiments. The apparatus 4800 can be configured to perform communication utilizing subcarrier selective feedback and can include a subcarrier selection module 4802 configured to perform functions required for such communication. The subcarrier selection module 4802 can be configured to measure channel information feedback of a channel based on a PPDU, the measured channel being divided into two or more segments, each of the two or more segments including one or more subcarriers, and select a subset of one or more subcarriers to be reported for the corresponding segment based on a grouping parameter Ng. The subcarrier selection module 4802 can have its own built-in memory that can be used to store PPDU formats and related information for performing subcarrier selection, for example, the subcarrier selection can be performed by the apparatus 4800 without instructions from or involvement of other communication devices.

[0066] FIG. 49 shows a schematic diagram of a sensing device 4900 (shown within dotted line portion 4914) according to various embodiments. The sensing device 4900 may be configured to communicate with another communication device for sensing measurements and may include a sensing module 4902 configured to perform functions necessary for such sensing measurements, including utilizing subcarrier selective feedback. The sensing module 4902 may further include a subcarrier selection module 4904 configured to perform functions necessary for subcarrier selective feedback. The subcarrier selection module 4904 may be configured to measure channel information feedback of a channel based on a PPDU, the channel to be measured being divided into two or more segments, each of the two or more segments including one or more subcarriers, and select a subset of one or more subcarriers to be reported for a corresponding segment based on a grouping parameter Ng. The subcarrier selection module 4904 may have its own built-in memory that may be used to store PPDU formats and related information for performing subcarrier selection, such that subcarrier selection may be performed by the device 4900, for example, without instructions from or involvement of another communication device. The sensing device 4900 can further interact with a WLAN sensing application module 4906 via a WLAN sensing API. The WLAN sensing application module 4906 can further interact with a WLAN sensing application module 4908 for performing functions related to vital signs detection, and a WLAN sensing application module 4910 for performing functions related to motion detection. The sensing device 4900 can also simultaneously function as a communication device and interact with one or more WLAN data applications 4912.

[0067] FIG. 50 shows a flow diagram 5000 illustrating a method of communication according to various embodiments. In step 5002, a PPDU is received. In step 5004, channel information of a channel based on the PPDU is measured, the measured channel being divided into two or more segments, each of the two or more segments including one or more subcarriers. In step 5006, a subset of one or more subcarriers to be reported for a corresponding segment is selected. In step 5008, a report frame is transmitted, the report frame conveying channel information feedback based on the channel information of the selected subcarriers.

[0068] 51 shows a schematic, partially boxed diagram of a communication device 5100 that may be implemented for subcarrier selective feedback according to embodiments E1 to E7.1. The communication device 5100 may be implemented as a STA or an AP according to various embodiments.

[0069] The various functions and operations of the communication device 5100 are arranged in layers according to a hierarchical model, where lower layers report to and receive instructions from higher layers according to IEEE specifications. For the sake of brevity, the details of the hierarchical model are not described in this disclosure.

[0070] As shown in FIG. 51, the communication device 5100 may include a circuit 5114, at least one wireless transmitter 5102, at least one wireless receiver 5104, and multiple antennas 5112 (for simplicity, only one antenna is depicted in FIG. 51 for illustrative purposes). The circuit may include at least one controller 5106, which is used to perform the tasks it is designed to perform with the assistance of software and hardware, including controlling communications with one or more other devices in a wireless network. The at least one controller 5106 may control at least one transmit signal generator 5108 for generating frames to be transmitted to one or more other STAs or APs via the at least one wireless transmitter 5102, and at least one receive signal processor 5110 for processing frames received from one or more other STAs or APs via the at least one wireless receiver 5104. At least one transmit signal generator 5108 and at least one receive signal processor 5110 may be independent modules of the communication device 5100 that communicate with at least one controller 5106 for the above-mentioned functions. Alternatively, at least one transmit signal generator 5108 and at least one receive signal processor 5110 may be included in at least one controller 5106. It will be understood by those skilled in the art that the arrangement of these functional modules is flexible and may vary according to actual needs and / or requirements. The data processing device, storage device, and other related control devices may be provided on a suitable circuit board and / or chipset.

[0071] In various embodiments, in operation, the at least one wireless transmitter 5102, the at least one wireless receiver 5104, and the at least one antenna 5112 may be controlled by at least one controller 5106. Further, while only one wireless transmitter 5102 is shown, it will be understood that there may be multiple such transmitters.

[0072] In various embodiments, in operation, the at least one wireless receiver 5104 together with the at least one receive signal processor 5110 form a receiver for the communications device 5100. In operation, the receiver for the communications device 5100 provides the functionality necessary for subcarrier selective feedback. Although only one wireless receiver 5104 is shown, it will be understood that there may be multiple such receivers.

[0073] The communication device 5100, in operation, provides functionality necessary for subcarrier selective feedback. For example, the communication device 5100 can be a first communication device. The receiver 5104, in operation, can receive a PPDU. The circuit 5114, in operation, can measure channel information of a channel based on the PPDU, where the measured channel is divided into two or more segments, each of the two or more segments including one or more subcarriers, and select a subset of one or more subcarriers to be reported for a corresponding segment. The transmitter 5102, in operation, can transmit a report frame to a second communication device conveying channel information feedback based on the channel information of the selected subcarriers.

[0074] The channel information feedback may be one of CSI feedback, uncompressed beamforming feedback, or compressed beamforming feedback. The transmitter 5102 may be further configured to transmit one or more different report frames, where the channel information feedback for different segments is included in one or more different report frames or in different fields or information elements in the same report frame. The circuit 5114 may be further configured to select a subset of subcarriers, where the selected subset of subcarriers is implicitly indicated in the report frame by a known subcarrier offset value. The circuit 5114 may be further configured to select a subset of subcarriers, where the selected subset of subcarriers is explicitly indicated in the report frame by an index of the selected subset of subcarriers.

[0075] The subcarriers reported for each segment may be based on the grouping parameter Ng. The reporting frame may indicate the size of each segment and the value of the grouping parameter Ng for each segment, and may include a feedback matrix of subcarriers selected based on the grouping parameter Ng. The circuit 5114 may be further configured to select one or more segments, and a different grouping parameter Ng is indicated in the reporting frame for the selected segments, and a default grouping parameter Ng is applied for the remaining segments. The receiver 5104 may be further configured to receive a frame prior to reception of the PPDU, and the size of each segment and the value of the grouping parameter Ng used for each segment are indicated in the frame.

[0076] The circuit 5114 may be further configured to select the subset of subcarriers based on a selection condition, the selection condition being a change in I and Q values, a change in amplitude value, or a change in phase value of each subcarrier compared to a threshold. The selection condition may be specified in a frame received prior to reception of the PPDU. The location of the selected subcarriers may be indicated in a reporting frame, the indication being based on a difference between the indexes of two adjacent selected subcarriers.

[0077] Furthermore, the communication device 5100 can be a second communication device. The transmitter 5102, in operation, can transmit a PPDU used by the first communication device to measure channel information of a channel, the measured channel being divided into two or more segments, each of the two or more segments including one or more subcarriers, and a subset of subcarriers to be reported for a corresponding segment is selected based on a grouping parameter Ng. The receiver 5104, in operation, can receive a report frame from the first communication device, the report frame conveying channel information feedback based on the channel information of the selected subcarriers.

[0078] The transmitter 5102 may be further configured to transmit a frame prior to the transmission of the PPDU, where the size of each segment and the value of the grouping parameter Ng used for each segment are indicated in the frame. The transmitter 5102 may be further configured to transmit a frame prior to the transmission of the PPDU, where the condition used by the first communication device to select a subset of subcarriers is indicated in the frame. The frame may be a Null Data PPDU Announcement (NDPA) frame, where the NDPA frame carries a plurality of STA Info fields addressed to the first communication device, where the value of the grouping parameter Ng for each segment is indicated in a respective STA Info field of the plurality of STA Info fields.

[0079] The present disclosure can be implemented by software, hardware, or software cooperating with hardware. Each functional block used in the description of each embodiment above can be implemented in part or in whole by an LSI such as an integrated circuit, and each process described in each embodiment can be controlled in part or in whole by the same LSI or a combination of LSIs. The LSI can be formed as multiple chips individually, or a single chip can be formed to include some or all of the functional blocks. The LSI can include a data input / output unit coupled to it. Depending on the degree of integration, the LSI can also be called an IC, a system LSI, a super LSI, or an ultra LSI. However, the technology for implementing the integrated circuit is not limited to the LSI, and can be implemented by using a dedicated circuit, a general-purpose processor, or a dedicated processor. Furthermore, an FPGA (Field Programmable Gate Array) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connections and settings of the circuit cells arranged inside the LSI, can also be used. The present disclosure can be implemented as digital processing or analog processing. If a future integrated circuit technology replaces LSI as a result of advances in semiconductor technology or other derivative technologies, the future integrated circuit technology can be used to integrate the functional blocks. Biotechnology can also be applied.

[0080] The present disclosure may be implemented by any type of apparatus, device, or system having communication capabilities, referred to as a communications device.

[0081] Some non-limiting examples of such communications devices include phones (e.g., mobile phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices), game consoles, e-book readers, telehealth / telemedicine devices, vehicles that provide communications capabilities (e.g., cars, airplanes, ships), and various combinations of these.

[0082] Communications devices are not limited to being portable or portable, but can also include any type of apparatus, device, or system that is non-portable or stationary, such as smart home devices (e.g., appliances, lights, smart meters, control panels), vending machines, and any other "things" in the network of the "Internet of Things" (IoT).

[0083] Communications may include, for example, exchanging data through cellular systems, wireless LAN systems, satellite systems, and various combinations thereof.

[0084] A communications device may include devices such as a controller or sensors coupled to the communications device to perform the communications functions described in this disclosure. For example, a communications device may include a controller or sensors that generate control or data signals used by the communications device to perform the communications functions of the communications device.

[0085] The communications devices may further include infrastructure facilities, such as base stations, access points, and any other apparatus, devices, or systems that communicate with or control apparatus such as the apparatus in the non-limiting examples above.

[0086] A non-limiting example of a station may be a station included in a first plurality of stations belonging to a multi-link station logical entity (i.e., MLD, etc.), where the stations of the first plurality of stations, as part of the first plurality of stations belonging to the multi-link station logical entity, share a common Medium Access Control (MAC) data service interface to higher layers, where the common MAC data service interface is associated with a common MAC address or traffic identifier (TID).

[0087] Thus, it can be seen that the present embodiments provide a communication apparatus and method for subcarrier selective feedback.

[0088] In the above detailed description of the embodiments of the present invention, exemplary embodiments have been presented, but it should be understood that a vast number of variations exist. Furthermore, it should be understood that the exemplary embodiments are examples and are not intended to limit the scope, applicability, operation, or configuration of the present disclosure in any way. Rather, the above detailed description provides those skilled in the art with a convenient guide for implementing the exemplary embodiments. It should be understood that various changes can be made in the function and organization of the steps and methods of operation described in the exemplary embodiments, and in the modules and structures of the devices described in the exemplary embodiments, without departing from the scope of the subject matter described in the appended claims.

Claims

1. a receiver for receiving a sensing Null Data Physical Protocol Data Unit (NDP) announcement frame and a sensing NDP from a second communication device; a circuit for performing channel state information (CSI) measurements; a transmitter configured to transmit to the second communication device a report frame including the CSI measured for subcarriers indicated by a value of a subcarrier grouping parameter (Ng) selected from a set of values ​​including a first value and a second value; Including, the first value of Ng is applicable to both a channel having a narrow bandwidth and a channel having a bandwidth wider than the narrow bandwidth; the second value of Ng is not applicable to the channel having the narrow bandwidth and is applicable to the channel having the wide bandwidth. A first communication device.

2. the circuit selects subcarriers for measuring the CSI based on a combination of the Ng and bandwidth information notified by the second communication device. The first communication device according to claim 1 .

3. If an empty segment of the channel is included in the subcarrier of interest, the report frame does not include CSI corresponding to the empty segment. The first communication device according to claim 1 .

4. the circuit selects the free segment based on partial BW information notified by the second communication device; The first communication device according to claim 3 .

5. the partial BW information is indicated by a bitmap field notified by the second communication device; The first communication device according to claim 4 .

6. 1. A communication method for a first communication device, comprising: receiving a sensing Null Data Physical Protocol Data Unit (NDP) announcement frame and a sensing NDP from a second communication device; performing channel state information (CSI) measurements; transmitting a report frame to the second communication device, the report frame including the CSI measured for subcarriers indicated by a value of a subcarrier grouping parameter (Ng) selected from a set of values ​​including a first value and a second value; the first value of Ng is applicable to both a channel having a narrow bandwidth and a channel having a bandwidth wider than the narrow bandwidth; the second value of Ng is not applicable to the channel having the narrow bandwidth and is applicable to the channel having the wide bandwidth. Communication method.

7. The subcarriers for measuring the CSI are set based on a combination of the Ng and bandwidth information notified by the second communication device. The communication method according to claim 6.

8. If an empty segment of the channel is included in the subcarrier of interest, the report frame does not include CSI corresponding to the empty segment. The communication method according to claim 6.

9. the free segment is selected based on partial BW information notified by the second communication device; The communication method according to claim 8.

10. the partial BW information is indicated by a bitmap field notified by the second communication device; The communication method according to claim 9.

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