MLD and communication method

Abstract

To improve the efficiency of transmission in a multi-link.SOLUTION: A multi-link device (MLD) is an MLD including a plurality of affiliated STAs corresponding to a plurality of links, and includes a reception circuit configured to receive, on a first link, a reference signal transmitted from another MLD, and a transmission circuit configured to transmit, to the other MLD on a second link different from the first link, beamforming feedback information regarding the first link, the beamforming feedback information being generated based on the reference signal.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present disclosure relates to a communication device and a communication method. [Background technology]

[0002] The IEEE Task Group (TG) be is currently developing the technical specifications for 802.11be (hereinafter referred to as "11be") as the successor standard to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, 802.11ax (hereinafter referred to as "11ax").

[0003] In 11be, for example, compared to 11ax, an increase in the maximum number of spatial streams (also called the number of spatial streams (SS) or spatial multiplexing number) in downlink (DL) multi-user multiple-input multiple output (MU-MIMO) is being discussed. Increasing the maximum number of spatial streams can improve spectrum efficiency. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] IEEE 802.11-19 / 0828r4, feedback-overhead-analysis-for-16-spatial-stream-mimo, May, 2019 [Non-patent document 2] IEEE P802.11ax D6.0, November 2019 [Non-patent document 3] IEEE Std 802.11, 2016 [Non-patent document 4] IEEE 802.11-19 / 0823r2, Multi-Link Operation: Design Discussion Summary of the Invention

[0005] However, there is room for further consideration regarding transmission processing in multi-link.

[0006] Non-limiting embodiments of the present disclosure contribute to providing a communication device and a communication method that improve the efficiency of transmission in multi-links.

[0007] A communication device according to one embodiment of the present disclosure includes a control circuit that controls transmission of first information based on second information regarding transmission of the first information over multiple links, and a transmitting circuit that transmits the first information in accordance with the control.

[0008] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0009] According to an embodiment of the present disclosure, it is possible to improve the efficiency of transmission in multi-links.

[0010] Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features. [Brief explanation of the drawings]

[0011] [Figure 1] Sequence diagram showing an example of beamforming using null data packet (NDP) sounding and explicit feedback [Figure 2]An example of the High Efficiency (HE) Compressed Beamforming / Channel Quality Indicator (CQI) frame action field format. [Figure 3] A sequence diagram showing an example of staggered sounding [Figure 4] A diagram showing an example of a multi-link operation system [Figure 5] A diagram showing an example of the operation of Simultaneous Tx and Rx (STR) access point (AP) multi-link device (MLD) [Figure 6] Figure showing an example of Non-STR AP MLD operation [Figure 7] FIG. 1 is a block diagram showing a configuration example of a part of an AP MLD according to a first embodiment; [Figure 8] FIG. 1 is a block diagram showing a partial configuration example of a Non-AP MLD according to a first embodiment; [Figure 9] FIG. 1 is a block diagram showing an example of the configuration of an AP MLD according to a first embodiment; [Figure 10] FIG. 1 is a block diagram showing a configuration example of a Non-AP MLD according to a first embodiment; [Figure 11] FIG. 1 is a sequence diagram illustrating an example of operation of the wireless communication system according to the first embodiment. [Figure 12] An example of a Link ID bitmap [Figure 13] An example of a Link ID bitmap [Figure 14] FIG. 10 is a sequence diagram illustrating an example of a feedback information transmission operation. [Figure 15] FIG. 10 is a sequence diagram illustrating an example of a feedback information transmission operation. [Figure 16] FIG. 10 is a sequence diagram illustrating an example of a feedback information transmission operation. [Figure 17] FIG. 10 is a sequence diagram illustrating an example of a feedback information transmission operation. [Figure 18]FIG. 10 is a diagram showing an example of a field that notifies the start and end points of a spatial stream. [Figure 19] FIG. 10 is a diagram showing an example of a field for notifying the start and end points of a channel index. [Figure 20] A diagram showing an example of a field for notifying the type of feedback information. [Figure 21] FIG. 10 is a diagram illustrating an example of a feedback request signal. [Figure 22] A diagram showing an example of setting up a feedback request signal [Figure 23] An example of a trigger frame [Figure 24] An example of a trigger frame [Figure 25] FIG. 10 is a sequence diagram illustrating an example of operation of a wireless communication system according to a second embodiment. [Figure 26] An example of an NDP Announcement (NDPA) [Figure 27] FIG. 10 is a diagram showing an example of feedback information. [Figure 28] A diagram showing an example of HE MIMO Control [Figure 29] FIG. 10 is a sequence diagram illustrating an example of operation of a wireless communication system according to another embodiment. [Figure 30] FIG. 10 is a sequence diagram illustrating an example of operation of a wireless communication system according to another embodiment. [Figure 31] FIG. 10 is a diagram showing an example of a field for notifying a combination of a frequency band and a channel identifier. [Figure 32] FIG. 1 shows an example of frequency bands and channel identifiers. [Figure 33] FIG. 1 is a diagram showing an example of a combination of a frequency band and a frequency offset. [Figure 34] FIG. 1 shows an example of a frequency band and a frequency offset. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings.

[0013] In the 802.11 standard, for example, when space-time block coding (also called Space-Time Block Coding (STBC)) is not performed, one modulation symbol stream is generated from one bit stream, and when space-time block coding is performed, two or more modulation symbol streams are generated from one bit stream. For example, a spatially multiplexed bit stream is called a "spatial stream," and a spatially multiplexed modulation symbol stream is called a "space-time stream (or "Space-time stream (STS)"). For example, when space-time block coding is not performed, the number of space-time streams is equal to the number of spatial streams.

[0014] In the following description, an example in which space-time block coding is not performed will be described. In other words, in the following description, spatial streams and space-time streams will not be distinguished from each other, and the term "spatial stream" will be used to mean a spatial channel used for spatial multiplexing. However, the spatial stream in the following description may be interpreted as a space-time stream when space-time block coding is performed.

[0015] [Beamforming] Downstream MU-MIMO uses beamforming technology, which can improve communication quality in the downlink.

[0016] In beamforming of DL MU-MIMO, for example, weighting (also called "steering," "spatial mapping," or "transmit precoding") is performed to control amplitude and phase in order to impart orthogonality to signals addressed to each user. A matrix representing this weighting (hereinafter referred to as a "steering matrix") can be derived based on information about propagation paths (also called "channels") estimated by beamforming (see, for example, Non-Patent Document 1).

[0017] 11ax supports a method using null data packet (NDP) sounding and explicit feedback as an example of a beamforming technique (see, for example, Non-Patent Document 2). Fig. 1 is a sequence diagram showing an example of beamforming using NDP sounding and explicit feedback.

[0018] In Fig. 1, an access point (AP, also called a "base station") transmits, for example, an NDP announcement (NDPA) to each terminal (also called a "STA (Station)"). By transmitting the NDPA, the AP notifies the STA of the transmission of the NDP.

[0019] The AP sends the NDPA followed by the NDP to the STA.

[0020] After receiving the NDP, the STA estimates the channel based on a signal (eg, a non-legacy long training field (non-legacy LTF)) included in the NDP.

[0021] Note that, for example, when a steering matrix is ​​added to a non-Legacy LTF, the STA may estimate a channel including the steering matrix (e.g., also referred to as an "effective channel") regardless of whether the received signal is NDP or non-NDP. In the following description, regardless of whether it is a channel or an effective channel, it is simply referred to as a propagation path response (also referred to as "propagation path characteristics," "channel response," "channel estimation matrix," or "channel matrix"). The STA determines feedback information to transmit to the AP in response to the NDP, for example, based on the channel estimation value.

[0022] For example, the STA transmits compressed feedback information to the AP using a method called "compressed beamforming." The AP receives and processes the feedback information transmitted from the STA, and determines resource allocation information and transmission parameters for the destination STA or for each STA based on the received feedback information (also called "scheduling"). The AP may also derive a steering matrix based on the feedback information to perform DL transmission (e.g., MU-MIMO) to the STA.

[0023] Fig. 2 shows an example of the structure of feedback information transmitted from a STA to an AP. Fig. 2 also shows an example of the structure of a Compressed Beamforming / CQI frame Action field format. Fig. 2 also shows an example of the structure when the feedback type is MU (Multi-User), which will be described later.

[0024] The feedback information is classified into, for example, a "HE compressed Beamforming Report," a "HE MU Exclusive Beamforming Report," and a "HE Channel Quality Information (CQI) Report." The HE Compressed Beamforming Report may include, for example, the reception quality for each spatial stream (for example, the average Signal-to-Noise Ratio (SNR)) and a feedback matrix in which the amount of information is compressed by a specified method. The HE MU Exclusive Beamforming Report may include, for example, a difference value obtained by subtracting the average reception quality (for example, the average SNR) of each spatial stream from the reception quality (for example, the SNR) for each subcarrier. The HE CQI Report may include, for example, the average reception quality (for example, the average SNR) of spatial streams in units of 26-tone resource units (RUs).

[0025] The STA may determine feedback information to be transmitted to the AP in response to the NDP based on, for example, the feedback type indicated in the "Feedback Type And Ng subfield" included in the NDPA. For example, when the feedback type is SU (Single User), the STA may feed back an HE compressed Beamforming Report. When the feedback type is MU (e.g., FIG. 2), the STA may feed back an HE compressed Beamforming Report and an HE MU Exclusive Beamforming Report. When the feedback type is CQI, the STA may feed back an HE CQI Report.

[0026] Furthermore, as an example of another beamforming technique, 802.11n supports "Staggered Sounding" (see, for example, Non-Patent Document 3).

[0027] FIG. 3 is a sequence diagram showing an example of the operation of staggered sounding.

[0028] Staggered sounding is a beamforming technique for single-user MIMO (SU-MIMO). For example, an AP transmits a signal (e.g., an SU Physical layer convergence procedure Protocol Data Unit (PPDU)) including a data portion (e.g., also referred to as a data field) to a STA. The STA determines whether to transmit feedback information, for example, based on channel state information (CSI) / Steering Request included in the medium access control (MAC) layer of the signal transmitted from the AP. For example, when instructed to transmit feedback information (if feedback information transmission: yes), the STA feeds back a channel estimate obtained based on a signal (e.g., non-legacy LTF) included in the signal transmitted from the AP. For example, the STA may add the channel estimate (in other words, feedback information) to a response signal (e.g., an Acknowledgement (ACK) or Block ACK (BA)) based on the feedback method instructed by the CSI / Steering Request, and transmit the response signal to the AP.

[0029] [Multi-link operation] In 11be, multi-link operation (hereinafter referred to as "multi-link") is discussed, in which a multi-link device (MLD) in which multiple APs or STAs are connected to one MAC Service Access Point (SAP) transmits and receives (e.g., transmits and receives simultaneously) using multiple links (see, for example, non-patent document 4).

[0030] In multi-link, for example, a MAC Service Data Unit (MSDU) having a single Traffic Identifier (TID) is transmitted (for example, simultaneously) on multiple links to improve throughput and latency.

[0031] Fig. 4 is a diagram showing an example of a multi-link system. In the example shown in Fig. 4, multi-linking is performed using two links, link 1 and link 2, between AP1 and AP2 and STA1 and STA2.

[0032] In multilink, an MLD that includes an AP is called an "AP MLD," and an MLD that includes STAs that are not APs is called a "non-AP MLD." Note that the links used in multilink may be multiple links within the same band, or multiple links in different bands.

[0033] In addition, in multi-link, AP MLD / non-AP MLD that can transmit and receive (e.g., transmit and receive simultaneously) on multiple links is called "Simultaneous Tx and Rx (STR) AP MLD / STR non-AP MLD." On the other hand, AP MLD / non-AP MLD that cannot transmit and receive on multiple links is called "Non-STR AP MLD / Non-STR non-AP MLD."

[0034] Fig. 5 is a diagram showing an example of the operation of STR AP MLD, and Fig. 6 is a diagram showing an example of the operation of Non-STR AP MLD. In Fig. 5, STR AP MLD is capable of transmitting data to a STA over link 2 while receiving an ACK signal (Ack) from the STA over link 1, for example. On the other hand, in Fig. 6, Non-STR AP MLD may perform scheduling so that the timing of data transmission and the timing of receiving an ACK signal do not overlap when data transmission is performed at different times for each link, for example, because simultaneous transmission and reception over multiple links is not permitted (or to be avoided).

[0035] Multilink has been described above.

[0036] However, the method of transmitting feedback information from a STA to an AP in multilink (e.g., multilink feedback) has not been fully studied. For example, the amount of feedback information transmitted from a STA to an AP may increase in proportion to the maximum number of spatial streams. Therefore, in 11be, which can increase the maximum number of spatial streams, a method of improving the efficiency of transmission in multilink (e.g., the frequency utilization efficiency of multilink feedback) is expected.

[0037] In one embodiment of the present disclosure, a method for improving frequency utilization efficiency in multi-link feedback is described.

[0038] [Wireless communication system configuration] A wireless communication system according to an embodiment of the present disclosure includes at least one AP MLD and one non-AP MLD.

[0039] For example, an AP MLD (e.g., also called a "downlink wireless transmitting device" in DL communication) transmits control information to a non-AP MLD (e.g., also called a "downlink wireless receiving device" in DL communication). The non-AP MLD transmits feedback information to the AP MLD (e.g., Uplink (UL) SU transmission or UL MU transmission) using, for example, one or more links designated by the control information from among multiple links.

[0040] In the following, for convenience, an AP MLD may be referred to as an "AP" and a Non-AP MLD may be referred to as an "STA," for example, as a non-limiting example that the devices included in the wireless communication system are MLDs.

[0041] An MLD (e.g., AP MLD or Non-AP MLD) may be, for example, a device having one or more STAs (e.g., STAs affiliated to the MLD). An MLD may also be, for example, a device having one MAC SAP containing one MAC data service for a logical link control (e.g., LLC).

[0042] Furthermore, the MLD may be configured logically or physically. For example, the MLD may be a single physical device having the logical functions of an STA or AP corresponding to each of a plurality of links as shown in Fig. 4. Alternatively, the MLD may be configured by individual physical devices (STAs or APs) corresponding to each of a plurality of links as shown in Fig. 4.

[0043] An MLD may have one STA. For example, the MAC addresses (e.g., wireless medium (WM) MAC) of the STAs (e.g., affiliated STAs) included in the MLD may be the same or different.

[0044] Also, the AP MLD may be, for example, an MLD that includes an AP (in other words, an MLD in which the affiliated STA is an AP), and the non-AP MLD may be, for example, an MLD that includes an STA (in other words, an MLD in which the affiliated STA is a non-AP STA).

[0045] As an example, the following describes a method in which a STA performs multilink feedback transmission based on control information transmitted by an AP in NDP sounding in 11ax.

[0046] FIG. 7 is a block diagram showing a partial configuration example of AP100 according to an embodiment of the present disclosure. In the AP100 shown in FIG. 7 (for example, corresponding to a communication device), a control unit (for example, corresponding to a control circuit) controls the reception of multi-link transmission by another communication device (for example, STA200) based on control information regarding multi-link transmission. A reception unit (for example, a reception circuit) receives multi-link transmission by another communication device in accordance with the control of reception.

[0047] FIG. 8 is a block diagram showing a partial configuration example of STA200 according to an embodiment of the present disclosure. In the STA200 shown in FIG. 8 (for example, corresponding to a communication device), a control unit (for example, corresponding to a control circuit) controls multi-link transmission based on control information regarding multi-link transmission. A transmission unit (for example, corresponding to a transmission circuit) performs multi-link transmission in accordance with the control of multi-link transmission.

[0048] (Embodiment 1) <Configuration Example of AP100> FIG. 9 is a block diagram showing a configuration example of AP100 (for example, a downlink wireless transmission device or an AP MLD). The AP100 shown in FIG. 9 may include, for example, wireless reception units 101-1, 101-2, a reception signal decoding unit 102, a feedback information reconstruction unit 103, a multi-link scheduling unit 104, a data generation unit 105, a Preamble generation unit 106, and wireless transmission units 107-1, 107-2.

[0049] Note that, for example, the reception signal decoding unit 102, the feedback information reconstruction unit 103, the multi-link scheduling unit 104, the data generation unit 105, and the Preamble generation unit 106 may be included in the control unit shown in FIG. 7, and the wireless reception units 101-1, 101-2 may be included in the reception unit shown in FIG. 7.

[0050] Also, for example, wireless receiving unit 101-1 and wireless transmitting unit 107-1 are components of an AP (for example, AP1 shown in Figure 4) that communicates using link 1, and wireless receiving unit 101-2 and wireless transmitting unit 107-2 are components of an AP (for example, AP2 shown in Figure 4) that communicates using link 2.

[0051] Also, while FIG. 9 shows an example of the configuration of the AP 100 having two links, the number of links is not limited to two and may be three or more.

[0052] The radio receiving units 101-1 and 101-2 of each link receive signals transmitted from STA 200 (for example, a downlink radio receiving device or a non-AP MLD) via an antenna, and perform radio receiving processing such as down-conversion and A / D (Analog-to-Digital) conversion on the received signals. The radio receiving units 101-1 and 101-2 divide the received signals after radio receiving processing into a preamble part (also called a "preamble signal") and a data part (also called a "data signal"), and output them to the received signal decoding unit 102.

[0053] The received signal decoding unit 102 may perform demodulation processing such as Fourier transform (e.g., Fast Fourier Transform (FFT)) on the preamble signal and data signal input from the radio receiving units 101-1 and 101-2 for each link, and extract control signals included in the preamble signal and data signal. The control signals may include, for example, frequency bandwidth, Modulation and Channel Coding Scheme (MCS), or encoding method.

[0054] Furthermore, the received signal decoding unit 102 may, for example, use a control signal acquired from the preamble signal and a channel estimation signal to channel equalize, demodulate, and decode the data signal after FFT, and perform error detection such as a Cyclic Redundancy Check (CRC). For example, if there is no error in the data signal (in other words, a decoding error), the received signal decoding unit 102 outputs the decoded data signal to the feedback information reconstruction unit 103 and the multilink scheduling unit 104. On the other hand, for example, if there is an error in the data signal, the received signal decoding unit 102 does not need to output the decoded data signal.

[0055] The feedback information reconstructing unit 103 reconstructs the feedback information input from the received signal decoding unit 102 for each link or for each type of feedback information, for example, based on a data signal input from the received signal decoding unit 102 (for example, control information related to a distribution method of the feedback information). The feedback information reconstructing unit 103 may output the reconstructed feedback information to a processing unit (not shown). Note that the "distribution method" may be abbreviated to "distribution" and may be interchangeably read as other terms such as "allocation (method)" or "mapping (method)" for multiple links.

[0056] The multi-link scheduling unit 104 performs, for example, multi-link scheduling.

[0057] For example, the multilink scheduling unit 104 may determine whether to request the STA 200 to transmit multilink feedback based on a data signal input from the received signal decoding unit 102 (e.g., information regarding the status of each link of the STA 200 (e.g., Network Allocation Vector (NAV) status information)).

[0058] For example, when requesting multilink feedback transmission from STA 200, multilink scheduling section 104 determines the scheduling of multilink feedback transmission based on the data signal input from received signal decoding section 102. Examples of scheduling for multilink feedback transmission include scheduling related to the transmission of control information related to links used for multilink feedback, scheduling related to links used for transmitting feedback information in STA 200, and scheduling related to distribution of feedback information to each link in STA 200. Multilink scheduling section 104 outputs the control information related to scheduling to, for example, at least one of data generation section 105 and preamble generation section 106.

[0059] The data generation unit 105 generates a data sequence to be transmitted to the STA 200 on each link, for example, based on scheduling information input from the multilink scheduling unit 104. The data generation unit 105 may, for example, encode the generated data sequence, allocate the encoded data sequence to a frequency band of a channel (for example, a channel acquired by carrier sensing), and perform modulation and inverse Fourier transform (for example, IFFT: Inverse Fast Fourier Transform) processing to generate a data signal. The data generation unit 105 outputs the generated data signal to the radio transmission units 107-1 and 107-2 of each link.

[0060] The preamble generation unit 106 generates a preamble signal based on the scheduling information input from the multilink scheduling unit 104. The preamble signal may include, for example, a reference signal. For example, the preamble generation unit 106 performs modulation and IFFT processing on the preamble signal, and outputs the preamble signal to the radio transmission units 107-1 and 107-2 of each link.

[0061] The wireless transmission units 107-1 and 107-2 of each link generate a wireless frame (which may be referred to as a "packet signal" for example) including the data signal input from the data generation unit 105 and the Preamble signal input from the Preamble generation unit 106. The wireless transmission units 107-1 and 107-2 perform wireless transmission processing such as D / A conversion and up-conversion to the carrier frequency on the generated wireless frame, and transmit the signal after the wireless transmission processing to the STA200 via the antenna.

[0062] <Configuration example of STA200> FIG. 10 is a block diagram showing a configuration example of the STA200 (for example, a downlink wireless reception device or a Non-AP MLD). The STA200 shown in FIG. 10 may include, for example, wireless reception units 201-1 and 201-2, Preamble demodulation units 202-1 and 202-2, data decoding units 203-1 and 203-2, a multi-link control unit 204, a transmission signal generation unit 205, and wireless transmission units 206-1 and 206-2.

[0063] Note that, for example, the Preamble demodulation units 202-1 and 202-2, the data decoding units 203-1 and 203-2, the multi-link control unit 204, and the transmission signal generation unit 205 may be included in the control unit shown in FIG. 8, and the wireless transmission units 206-1 and 206-2 may be included in the transmission unit shown in FIG. 8.

[0064] Also, for example, the wireless reception unit 201-1, the Preamble demodulation unit 202-1, the data decoding unit 203-1, and the wireless transmission unit 206-1 are components of a STA (for example, the STA1 shown in FIG. 4) that communicates using Link 1, and the wireless reception unit 201-2, the Preamble demodulation unit 202-2, the data decoding unit 203-2, and the wireless transmission unit 206-2 are components of a STA (for example, the STA2 shown in FIG. 4) that communicates using Link 2.

[0065] Also, FIG. 10 shows a configuration example of the STA200 having two links, but the number of links is not limited to two and may be three or more.

[0066] Radio receiving units 201-1 and 201-2 of each link receive signals transmitted from AP 100 via antennas and perform radio receiving processing such as down-conversion and A / D conversion on the received signals. Radio receiving units 201-1 and 201-2 extract preamble signals from the signals after radio receiving processing and output them to preamble demodulation units 202-1 and 202-2. Radio receiving units 201-1 and 201-2 also extract data signals from the signals after radio receiving processing and output them to data decoding units 203-1 and 203-2.

[0067] The preamble demodulators 202-1 and 202-2 of each link perform demodulation processing such as FFT on the preamble signals input from the radio receivers 201-1 and 201-2, and extract, for example, a control signal used for demodulating and decoding a data signal from the demodulated preamble signals. The preamble demodulators 202-1 and 202-2 may also perform channel estimation based on a reference signal included in the preamble signals. The preamble demodulators 202-1 and 202-2 output the extracted control signal and channel estimation information (for example, a channel estimation matrix) to the data decoders 203-1 and 203-2.

[0068] Data decoders 203-1 and 203-2 perform processing such as FFT processing, channel equalization, or demodulation on the data portion input from radio receivers 201-1 and 201-2 based on, for example, the control signal and channel estimation information input from preamble demodulators 202-1 and 202-2, and extract demodulated data addressed to STA 200. Data decoders 203-1 and 203-2 also decode the extracted demodulated data based on the control information signal input from preamble demodulators 202-1 and 202-2, and perform error detection such as CRC. For example, if there is no error in the data signal, data decoders 203-1 and 203-2 output the decoded data to multi-link controller 204. On the other hand, for example, if there is an error in the data signal, data decoders 203-1 and 203-2 may not output the decoded data.

[0069] Multilink control section 204 may determine the links to be used for multilink feedback or the method of distributing the feedback information to each link, based on control information related to multilink feedback included in the decoded data input from data decoding sections 203-1 and 203-2, for example. Multilink control section 204 outputs control information including information related to the determined links or information related to the method of distributing the feedback information to transmission signal generation section 205.

[0070] The transmission signal generation unit 205 generates a data sequence including feedback information based on the control information input from the multilink control unit 204. The transmission signal generation unit 205 allocates the generated data sequence to frequency resources for each link, performs modulation and IFFT processing, and generates a data signal (for example, a transmission signal). The transmission signal generation unit 205 also adds a preamble to the data signal for each link to generate a radio frame (for example, a packet signal), and outputs the radio frame to the radio transmission units 206-1 and 206-2 of each link. Note that the "packet signal" may be abbreviated to "packet".

[0071] The wireless transmitting units 206-1 and 206-2 of each link perform wireless transmission processing such as D / A conversion and up-conversion to a carrier frequency on the wireless frame input from the transmission signal generating unit 205, and transmit the signal after wireless transmission processing to the AP 100 via an antenna.

[0072] [Example of AP100 and STA200 operation] Next, an example of the operation of the AP 100 and the STA 200 according to this embodiment will be described.

[0073] FIG. 11 is a sequence diagram showing an example of the operation of the wireless communication system regarding multilink feedback transmission.

[0074] 11, an example of an operation relating to the transmission of feedback information between AP 100 having two links (e.g., link 1 and link 2) and STA 200 having two links (e.g., link 1 and link 2) will be described. Note that the number of links used to transmit feedback information may be "1" or more, and in the case of multi-link feedback, it is not limited to "2" but may be "3" or more.

[0075] 11, AP 100 may, for example, transmit an NDPA including control information related to multilink feedback transmission to STA 200 on each link (e.g., link 1 and link 2) (S101-1, S101-2). STA 200 may, for example, perform reception processing of the NDPA received on each link and acquire (or receive) the control information related to multilink feedback (S102-1, S102-2). Furthermore, by transmitting the NDPA, STA 200 may be notified that an NDP will be transmitted after the NDPA (e.g., following the NDPA).

[0076] For example, the AP 100 may transmit an NDP to the STA 200 (S103-1, S103-2). The STA 200 may perform reception processing of the NDP based on, for example, control information acquired from the NDPA (S104-1, S104-2). For example, the STA 200 may perform channel estimation based on a reference signal (for example, an LTF) included in the preamble portion of the received NDP.

[0077] In FIG. 11, as an example, STA 200 may perform channel estimation for link 1 using a reference signal (eg, LTF) included in the preamble portion of the NDP transmitted on link 1.

[0078] STA200 may generate, for example, feedback information (S105-1, S105-2). For example, STA200 may generate one or more pieces of feedback information among an HE compressed Beamforming Report, an HE MU Exclusive Beamforming Report, and an HE CQI Report based on a channel estimation value obtained by channel estimation and a feedback type indicated in the control information of NDPA.

[0079] STA200 may determine a link to be used for transmitting feedback information (e.g., multi-link feedback transmission) based on, for example, control information included in the NDPA, and transmit the feedback information to AP100 on the determined link (S106-1, S106-2). In FIG. 11, as an example, STA200 may transmit feedback information regarding link 1 to AP100 using link 1 and link 2.

[0080] For example, the AP 100 may receive feedback information transmitted on each link from the STA 200 (S107-1, S107-2). The AP 100 may reconstruct the feedback information distributed to each link based on, for example, control information related to multi-link feedback included in the NDPA or control information included in the feedback information.

[0081] The AP 100 may transmit an ACK signal to the STA 200 on each link according to the result of the reception processing of the feedback information (S108-1, S108-2), for example.

[0082] Although Fig. 11 has described a case where the NDPA and NDP are transmitted over both link 1 and link 2, the present invention is not limited to this and the NDPA and NDP may be transmitted over at least one of a plurality of links. Furthermore, Fig. 11 has described a case where feedback information regarding link 1 is generated, but the present invention is not limited to this and the feedback information may be generated over at least one of a plurality of links. Furthermore, Fig. 11 has described a case where feedback information is transmitted over both link 1 and link 2, but the present invention is not limited to this and the feedback information may be transmitted over at least one of a plurality of links.

[0083] An example of the operation of a wireless communication system regarding multilink feedback transmission has been described above.

[0084] Next, examples of the control method for multilink feedback transmission (control method 1 and control method 2) will be described.

[0085] [Control method 1] In control method 1, the control information related to the multilink feedback transmission may include, for example, identification information of links available for the multilink transmission (e.g., referred to as "link identifiers" or "Link IDs"). STA 200 may determine, for example, a link from the multilinks to be used for transmitting the feedback information based on the notified identification information.

[0086] For example, the Link ID may be a bitmap (e.g., referred to as a "Link ID bitmap") in which one bit corresponds to each link. For example, a link with Link ID bitmap=1 may be set as a link used for feedback transmission, and a link with Link ID bitmap=0 may be set as a link not used for feedback transmission. Note that the Link ID is not limited to information in bitmap format, and may be information in other formats.

[0087] The Link ID may be set (eg, notified) to the STA 200 by the AP 100 when the STA 200 connects to the AP 100, for example.

[0088] The field length of the Link ID bitmap may be, for example, a fixed length or a variable length.

[0089] For example, as shown in Fig. 12, the field length of the Link ID bitmap may be set to a predetermined (e.g., standard-defined) maximum number of links. In other words, the amount of information in the Link ID bitmap may be based on the predetermined number of links. In this case, the field length of the Link ID bitmap is fixed.

[0090] 13, the field length of the Link ID bitmap may be set to the maximum number of links of the AP 100. In other words, the amount of information in the Link ID bitmap may be based on the number of links set in the AP 100. In this case, the field length of the Link ID bitmap is variable. For example, when the STA 200 connects to the AP 100, the STA 200 may be notified of the maximum number of links based on the capability information of the AP 100 along with the Link ID.

[0091] For example, when the field length of the Link ID bitmap is set to the maximum number of links of AP100, the Link ID bitmap is notified with a shorter field length than when the field length of the Link ID bitmap is set to the maximum number of links specified by the standard, thereby reducing signaling overhead.

[0092] Also, for example, after receiving control information including a Link ID bitmap, STA200 may determine the link to which feedback information transmission is assigned in multi-link transmission (in other words, distribution of feedback information) based on the Link ID bitmap and a specified rule.

[0093] For example, the specified rule may be based on the number of spatial streams included in the feedback information (e.g., the number of spatial streams for which reception quality is measured (or estimated)) and the bandwidth of each link used to transmit the feedback information. As an example, let the number of spatial streams included in the feedback information be N, the number of links used for multilink feedback notified by the Link ID bitmap be two (e.g., Link 1 and Link 2), the bandwidth of Link 1 be BW1, and the bandwidth of Link 2 be BW2. In this example, the STA 200 may transmit feedback information of (N*BW1) / ((BW1+BW2)) for Link 1, and may transmit feedback information of (N*BW2) / ((BW1+BW2)) for Link 2.

[0094] Furthermore, for example, the specified rule may be based on the type (or category) of feedback information. For example, when the number of links to be used for multilink feedback notified to STA 200 by the Link ID bitmap is two (for example, link 1 and link 2), STA 200 may transmit the average SNR for each spatial stream included in the HE MU Compressed Beamforming Report via link 1, and may transmit the feedback matrix included in the HE MU Compressed Beamforming Report via link 2.

[0095] The type of feedback information to be transmitted on each link may be determined based on, for example, the frequency band of the link. For example, feedback information with a larger amount of information may be associated with a link in a higher frequency band among multiple links.

[0096] Alternatively, for example, feedback information with a higher priority (or importance) may be associated with a link in a higher frequency band among a plurality of links.

[0097] In this way, the AP 100 notifies the STA 200 of the Link ID bitmap, allowing the STA 200 to perform multilink feedback transmission.

[0098] Next, examples 1 to 4 of notification of Link ID bitmap and transmission of feedback information in control method 1 will be described.

[0099] <Example 1> In example 1, STA 200 may determine to use a link different from the link on which control information (eg, NDPA and NDP) is received for transmitting feedback information in a multi-link transmission.

[0100] FIG. 14 is a sequence diagram illustrating an example of an operation related to transmission of control information and feedback information in Example 1. In FIG.

[0101] 14, for example, AP 100 transmits NDPA and NDP to STA 200 via link 1. For example, in the Link ID bitmap included in the NDPA, link 1 may be set as a link not used for feedback transmission (Link ID bitmap=0), and link 2 may be set as a link used for feedback transmission (Link ID bitmap=1) (for example, represented as Link ID bitmap=<0001>).

[0102] In FIG. 14, for example, after receiving the NDPA and NDP, STA200 may transmit feedback information (feedback(Link1)) regarding link 1 on link 2, which is different from link 1 on which the Link ID bitmap was received, based on the Link ID bitmap (=

[0001] ) included in the NDPA of link 1.

[0103] In addition, STA200 may transmit feedback information by obtaining carrier sense (in other words, when the channel state of link 2 is idle) on link 2 (in other words, a link not used for transmitting NDPA and NDP). For example, STA200 may transmit feedback information after a Distributed Coordination Function (DCF) Inter-Frame Space (DIFS) and a backoff time have elapsed.

[0104] Example 1 enables, for example, multi-link feedback in which each of a plurality of links is used for different purposes. As an example, a channel in the 2.4 GHz band may be used as link 1 to transmit control information, and a channel in the 5 GHz band may be used as link 2 for high-speed data communication. By using the links differently in this way, it is possible to improve frequency utilization efficiency in the multi-link.

[0105] <Example 2> In Example 2, the STA 200 may synchronize the transmission timing of feedback information between links in a multi-link transmission. For example, feedback information may be transmitted simultaneously on multiple links.

[0106] FIG. 15 is a sequence diagram showing an example of an operation related to transmission of control information (for example, NDPA and NDP) and feedback information in Example 2. In FIG.

[0107] In FIG. 15, for example, the AP 100 transmits the NDPA and NDP to the STA 200 via link 1 and link 2.

[0108] For example, in the Link ID bitmap included in the NDPA of Link 1, Link 1 may be set to a link used for feedback transmission (Link ID bitmap=1), and Link 2 may be set to a link used for feedback transmission (Link ID bitmap=1) (e.g., represented as Link ID bitmap = <0011>). Also, for example, in the Link ID bitmap included in the NDPA of Link 2, Link 1 may be set to a link not used for feedback transmission (Link ID bitmap=0), and Link 2 may be set to a link used for feedback transmission (Link ID bitmap=1) (e.g., represented as Link ID bitmap = <0001>).

[0109] 15, for example, after receiving the NDPA and NDP, STA200 may transmit feedback information regarding link 1 (feedback(Link1)) on each of link 1 and link 2, and may transmit feedback information regarding link 2 (feedback(Link2)) on link 2, based on the Link ID bitmap included in the NDPA of each link. In other words, STA200 may transmit feedback information on link 1 and link 2 simultaneously.

[0110] 15, STA 200 receives NDPA and NDP on link 1 and link 2, respectively, and therefore may transmit feedback information after a Short Inter-Frame Space (SIFS) of the NDP. In other words, STA 200 may transmit feedback information without obtaining carrier sense on each link.

[0111] According to Example 2, feedback information may be distributed to multiple links, for example, based on the communication capacity of the links. As an example, in multi-link feedback, if the communication capacity of link 2 is greater than that of link 1, STA 200 may transmit a portion of the feedback information of link 1 over link 2. Such transmission of feedback information can improve frequency utilization efficiency in multi-link and reduce feedback overhead.

[0112] <Example 3> In Example 3, STA 200 may vary the timing of transmitting feedback information between links in a multi-link transmission.

[0113] FIG. 16 is a sequence diagram illustrating an example of an operation related to transmission of control information (for example, NDPA and NDP) and feedback information in Example 3. In FIG.

[0114] 16, for example, AP 100 transmits an NDPA and an NDP to STA 200 via link 1. For example, in the Link ID bitmap included in the NDPA of link 1, link 1 may be set as the link used for feedback transmission (Link ID bitmap=1), and link 2 may be set as the link used for feedback transmission (Link ID bitmap=1) (for example, represented as Link ID bitmap=<0011>).

[0115] In FIG. 16, for example, after receiving the NDPA and NDP, STA200 may transmit feedback information regarding link 1 (feedback(Link1)) on each of link 1 and link 2 based on the Link ID bitmap (=[1, 1]) included in the NDPA of link 1.

[0116] 16, STA 200 receives the NDPA and NDP on link 1, and therefore may transmit feedback information on link 1 SIFS after receiving the NDP. On the other hand, STA 200 may obtain carrier sense on link 2 (in other words, a link not used for transmitting the NDPA and NDP) (in other words, when the channel state of link 2 is idle) and transmit feedback information. Therefore, as shown in FIG. 16, for example, STA 200 may transmit feedback information on multiple links (e.g., link 1 and link 2) at different timings.

[0117] In this case, as shown in FIG. 16, the timing at which STA 200 receives an ACK signal from AP 100 on link 1 may overlap with the timing at which feedback information is transmitted on link 2, so STA 200 may use STR non-AP MLD.

[0118] 16, since the feedback transmission on link 2 is delayed compared to link 1, for example, link 1 may be used to transmit high-priority feedback information and link 2 may be used to transmit low-priority feedback information, thereby improving the frequency utilization efficiency in multi-link feedback and reducing the feedback overhead.

[0119] <Example 4> In Example 4, the STA 200 may allocate feedback information for each of multiple links to one link in a multi-link transmission (or may aggregate and transmit the information).

[0120] FIG. 17 is a sequence diagram illustrating an example of an operation related to transmission of control information and feedback information in Example 4. In FIG.

[0121] 17, for example, AP 100 transmits an NDPA and an NDP to STA 200 via link 1 and link 2. For example, in the Link ID bitmap included in each NDPA of link 1 and link 2, link 1 may be set to a link used for feedback transmission (Link ID bitmap=1), and link 2 may be set to a link not used for feedback transmission (Link ID bitmap=0) (for example, represented as Link ID bitmap=<0010>).

[0122] 17, for example, after receiving the NDPA and NDP, the STA 200 may transmit feedback information regarding link 1 (feedback(Link1)) and feedback information regarding link 2 (feedback(Link2)) on link 1 based on the Link ID bitmap (=

[0010] ) of each of link 1 and link 2. In other words, the STA 200 may aggregate the feedback information regarding each of link 1 and link 2 on link 1 and transmit it.

[0123] For example, if the STA 200 has a common Association ID (AID) for each link, the STA 200 may aggregate feedback information for multiple links using an Aggregation MAC Service Data Unit (A-MSDU).

[0124] Also, for example, while STA200 is transmitting feedback information, AP100 may transmit packets to other STA200 on a link (link 2 in Figure 17) that has become available due to STA200 aggregating the feedback information into one link.

[0125] According to Example 4, for example, by aggregating feedback information into one link, frequency resources of other links can be released. Also, since the AP 100 can transmit packets to other STAs using the released frequency resources, for example, frequency utilization efficiency can be improved. Furthermore, by aggregating feedback information into one link, for example, preamble overhead can be reduced.

[0126] In Example 4, we have described a case where feedback information is aggregated to one link among multiple links, but this is not limited to this, and feedback information of multiple links may be assigned to some of the multiple links (e.g., two or more links).

[0127] Above, examples 1 to 4 of notification of Link ID bitmap and transmission of feedback information in control method 1 have been described.

[0128] In control method 1, AP 100 notifies, for example, control information related to multilink transmission (for example, Link ID bitmap) to STA 200. Then, STA 200 controls multilink transmission (for example, determines a link to transmit feedback information) based on, for example, the notified control information (for example, Link ID bitmap).

[0129] This control can improve the efficiency of transmission in multi-links, for example. For example, the STA 200 can determine the link to transmit the feedback information based on the state or characteristics of each link.

[0130] [Control method 2] In control method 2, the control information regarding multilink feedback transmission may include, for example, information regarding distribution of feedback information for multiple links in multilink transmission. STA 200 may determine distribution of feedback information among links in multilink transmission based on, for example, the notified information regarding distribution of feedback information.

[0131] For example, the distribution method of the feedback information may be based on parameters such as spatial stream, channel index (or frequency band), or type of feedback information.

[0132] <Case 1> For example, the AP 100 and the STA 200 may determine the distribution of feedback information based on spatial streams.

[0133] In this case, the control information regarding the multilink feedback transmission may include, for example, information regarding the spatial streams included in the feedback information transmitted on each link. For example, as shown in Fig. 18, the AP 100 may notify the STA 200 of the index of the start point (e.g., Feedback SS start index) and the index of the end point (e.g., Feedback SS end index) of the spatial stream included in the feedback information transmitted on each link.

[0134] For example, in 11be, since a maximum of 16 spatial streams are supported, the Feedback SS start index and the Feedback SS end index may each be set to a 4-bit field. Note that the maximum number of supported spatial streams is not limited to 16, and the number of bits of control information related to multilink feedback transmission may be set according to the number of supported spatial streams.

[0135] <Case 2> For example, the AP 100 and the STA 200 may determine the distribution of feedback information based on a channel index (frequency band).

[0136] In this case, the control information regarding the multilink feedback transmission may include, for example, information regarding the frequency band (e.g., channel) included in the feedback information transmitted on each link. For example, as shown in Fig. 19, the AP 100 may notify the STA 200 of the index of the start point (e.g., channel start index) and the index of the end point (e.g., channel end index) of the channel (e.g., channel in 20 MHz units) included in the feedback information transmitted on each link.

[0137] As an example, channel indexes may be assigned in ascending order starting from the lowest 20 MHz. Furthermore, for example, in 11be, since a maximum of 320 MHz (20 MHz * 16) is supported, the channel start index and the channel end index may each be set to a 4-bit field. Note that the supported frequency band is not limited to a maximum of 320 MHz, and the number of bits of control information related to multilink feedback transmission may be set according to the supported frequency band. Furthermore, channel indexes are not limited to being assigned in ascending order starting from the lowest channel, but may also be assigned in descending order or according to other rules.

[0138] <Case 3> For example, the AP 100 and the STA 200 may determine the distribution of feedback information based on the type of feedback information.

[0139] In this case, the control information regarding the multilink feedback transmission may include, for example, information regarding the type of feedback information transmitted in each link. For example, as shown in Fig. 20, the AP 100 may notify the STA 200 of information indicating the type of feedback information transmitted in each link (for example, Feedback info type bit).

[0140] The above describes an example of a method for distributing feedback information.

[0141] In control method 2, AP 100 notifies, for example, control information related to multilink transmission (for example, information related to distribution of feedback information) to STA 200. Then, STA 200 controls multilink transmission (for example, determines distribution of feedback information) based on, for example, the notified information related to distribution of feedback information.

[0142] This process can improve the efficiency of multi-link transmission, for example, by allowing the STA 200 to appropriately distribute feedback information among multiple links based on the status of each link.

[0143] The distribution of feedback information is not limited to the above-mentioned parameters, but may be based on other parameters corresponding to the state of each link, for example.

[0144] Next, examples of the method of distributing feedback information in control method 2 (method 2-1 and method 2-2) will be described.

[0145] [Method 2-1] In method 2-1, for example, the AP 100 may determine a distribution method for feedback information for each link. In other words, the STA 200 may receive control information related to the distribution of feedback information from the AP 100, and determine the distribution of feedback information among links in multi-link transmission to the AP 100 based on the received control information.

[0146] The AP 100 may include control information relating to distribution of feedback information as shown in Fig. 21 in the user information of a feedback request signal and notify the STA 200. Examples of the feedback request signal include an NDPA or a Trigger frame.

[0147] 21 may be information notifying the identifiers of the links used for feedback transmission. For example, if the number of links used for transmitting feedback information is two, the Feedback transmit link ID bitmap may be represented by two bits, where '10' indicates link 1, '01' indicates link 2, and '11' indicates link 1 and link 2.

[0148] 21 may be, for example, information notifying the identifier of a link included in the feedback information (for example, a link whose reception quality is measured (or estimated)). For example, if the number of links used to transmit the feedback information is two, the Feedback info link ID bitmap may be represented by two bits, where '10' indicates link 1, '01' indicates link 2, and '11' indicates link 1 and link 2.

[0149] Furthermore, the "Feedback SS start index" and "Feedback SS end index" shown in Fig. 21 may be, for example, information related to distribution of feedback information. Note that Fig. 21 shows a distribution method based on spatial streams (e.g., Fig. 18), but the information related to distribution of feedback information is not limited to this and may be a distribution method based on the above-mentioned channel index (e.g., Fig. 19) or type of feedback information (e.g., Fig. 20).

[0150] As an example, when transmitting multi-link feedback as shown in FIG. 15, AP100 may include control information regarding multi-link feedback as shown in FIG. 22 in the NDPA of each link (link 1 and link 2 in the example of FIG. 15) and notify STA200.

[0151] For example, in FIG. 22, AP100 may notify STA200 in the user information for link 1 that it will use link 1 (e.g., Feedback transmit link ID bitmap=10) to transmit feedback information regarding spatial stream indexes 1 to 4 of link 1 (e.g., Feedback info Link ID bitmap=10, Feedback SS start index=1, and Feedback SS end index=4).

[0152] Also, for example, in FIG. 22, AP100 may notify STA200 in the user information for link 2 that it will use link 2 (e.g., Feedback transmit link ID bitmap=01) to transmit feedback information regarding spatial stream indexes 5 to 8 of link 1 and feedback information regarding link 2 (e.g., Feedback info Link ID bitmap=11, Feedback SS start index=5, and Feedback SS end index=8).

[0153] STA200 may distribute the feedback information and transmit the feedback based on, for example, control information included in the user information received on each of link 1 and link 2.

[0154] Furthermore, the AP 100 may reconstruct, for example, based on a distribution method of the feedback information, the feedback information transmitted from the STA 200. For example, in Fig. 22, the AP 100 may reconstruct the feedback information of spatial streams 1 to 8 of Link 1 based on feedback information regarding spatial stream indexes 1 to 4 of Link 1 received through Link 1 and feedback information regarding spatial stream indexes 5 to 8 of Link 1 received through Link 2.

[0155] According to method 2-1, for example, the AP 100 can control the distribution of feedback information to each link based on usage information (for example, NAV status information) for each link of the STA 200, thereby improving frequency utilization efficiency.

[0156] Next, examples 1 and 2 of notification of control information and transmission of feedback information in method 2-1 will be described.

[0157] <Example 1> In Example 1, the AP 100 may transmit, for example, control information related to feedback information for each link to the STA 200 by including it in a Trigger frame.

[0158] For example, when the AP 100 controls (in other words, requests) multilink feedback for multiple STAs 200, the AP 100 may include control information related to the feedback information in the User Info field of the Trigger frame.

[0159] For example, as shown in FIG. 23, control information regarding feedback information may be included in User Info of a Beamforming Report Poll (BFRP) in a Trigger frame.

[0160] Alternatively, for example, as shown in FIG. 24, the control information regarding the feedback information may be included in, for example, Trigger dependent user info of a Trigger frame (for example, BFRP).

[0161] Next, an example of operation in Example 1 in which the AP 100 notifies a plurality of STAs 200 of multilink feedback will be described.

[0162] FIG. 25 is a sequence diagram showing an example of an operation when the AP 100 controls multi-link feedback for a plurality of STAs 200. In FIG.

[0163] 25, an example of operation will be described for an AP 100 (e.g., AP) having two links (e.g., link 1 and link 2) and two STAs 200 (e.g., STA1 and STA2) having two links. Note that, as mentioned above, the number of links used in multi-link feedback may be "2" or more.

[0164] In FIG. 25, the AP transmits an NDPA and an NDP to each STA via at least one of link 1 and link 2 (for example, S201-1, S201-2, S204-1, and S204-2).

[0165] STA1 and STA2, for example, perform reception processing of the NDP on link 1 and link 2, respectively, and acquire control information for receiving the NDP (for example, S202-1, S202-2, S203-1, and S203-2).

[0166] STA1 and STA2 also perform, for example, NDP reception processing (e.g., S205-1, S205-2, S206-1, and S206-2). STA1 and STA2 also generate, for example, channel estimation values ​​and feedback information (e.g., HE compressed Beamforming Report and HE MU Exclusive Beamforming Report) notified by control information acquired from the NDPA (e.g., S207-1, S207-2, S208-1, and S208-2).

[0167] The AP transmits a BFRP (e.g., a Trigger frame) to, for example, STA1 and STA2 (e.g., S209-1 and S209-2). The BFRP may include, for example, control information related to multilink feedback transmission. The BFRP may also include, for example, frequency resource allocation information for performing frequency multiplexing (also called, for example, Orthogonal Frequency-Division Multiple Access (OFDMA)) in each link.

[0168] STA1 and STA2 perform BFRP reception processing and acquire control information and frequency resource allocation information related to multilink feedback transmission (for example, S210-1, S210-2, S211-1, and S211-2).

[0169] STA1 and STA2 may transmit feedback information to the AP based on, for example, control information notified by BFRP (e.g., S212-1, S212-2, S213-1, and S213-2). For example, STA1 and STA2 may transmit feedback information to the AP by UL OFDMA using the allocated frequency resources. Also, for example, STA1 and STA2 may distribute feedback information to Link 1 and Link 2 according to control information regarding multilink feedback. In the example shown in FIG. 25, STA1 distributes feedback information corresponding to Link 1 to Link 1 and Link 2 before transmitting it. Also, in the example shown in FIG. 25, STA2 distributes feedback information corresponding to Link 2 to Link 1 and Link 2 before transmitting it.

[0170] The AP may, for example, perform reception processing of feedback information transmitted from each of STA1 and STA2 (for example, S214-1 and S214-2). The AP may, for example, reconstruct the feedback information of each STA received over multiple links based on the control information notified to each STA.

[0171] Furthermore, the AP transmits ACK signals to STA1 and STA2 on each link based on, for example, the results of the reception processing of the feedback information (for example, S215-1 and S215-2).

[0172] Thus, according to Example 1, for example, the AP 100 can simultaneously notify control information related to multilink feedback to multiple STAs 200. Also, for example, when control information is included in Trigger dependent User Info of BFRP, it is not necessary to add signaling related to multilink feedback to User Info of a Trigger frame different from BFRP, and therefore feedback overhead can be reduced.

[0173] <Example 2> In Example 2, the AP 100 may transmit, for example, control information for feedback information for each link to the STA 200 by including it in the NDPA.

[0174] For example, when AP 100 controls (in other words, requests) multilink feedback for a single STA 200, AP 100 may include control information regarding feedback information in STA Info of NDPA as shown in FIG.

[0175] According to Example 2, the AP 100 can notify, for example, a single STA 200 of control information regarding multilink feedback without a trigger frame (eg, BFRP).

[0176] The AP 100 may include control information related to multilink feedback addressed to multiple STAs in the NDPA. In this case, the AP 100 may notify each STA 200 of the timing to transmit feedback information by BFRP, for example.

[0177] [Method 2-2] In method 2-2, for example, the STA 200 may determine a distribution method of feedback information for each link. In other words, the STA 200 may determine, for example, distribution of feedback information to multiple links and transmit control information related to the distribution of the determined feedback information to the AP 100.

[0178] The STA 200 may, for example, include control information related to the distribution of feedback information as shown in FIG. 27 in the feedback information and notify the AP 100 of the same. In FIG. 27, for example, "Feedback Info link ID bitmap" may be information notifying an identifier of a link included in the feedback information (for example, a link whose reception quality is measured (or estimated)). Furthermore, the "Feedback SS start index" and "Feedback SS end index" shown in FIG. 27 may be information related to the distribution of feedback information. Note that while FIG. 27 shows a distribution method based on spatial streams, the information related to the distribution of feedback information is not limited to this, and may also be a distribution method based on the above-mentioned channel index (for example, FIG. 19) or type of feedback information (for example, FIG. 20).

[0179] For example, as shown in Fig. 28, the control information regarding distribution of feedback information may be included in the HE MIMO Control field of the Compressed Beamforming / CQI frame Action field format. Note that the control information regarding distribution of feedback information is not limited to the HE MIMO Control field and may be notified to AP 100 in another field.

[0180] 15, STA 200 may notify AP 100 that the feedback information for link 1 includes feedback information regarding spatial stream indexes 1 to 4 of link 1. Also, STA 200 may notify AP 100 that the feedback information for link 2 includes feedback information regarding spatial stream indexes 5 to 8 of link 1 and feedback information regarding link 2, for example.

[0181] For example, when feedback information for multiple links is transmitted over one link, such as link 2 shown in FIG. 15, feedback information parameters common to multiple links (e.g., information different from the control information related to multi-link feedback such as "Nc" and "Nr" in FIG. 28) may be notified in one HE MIMO Control field, or a different HE MIMO Control field may be set for each link, and different feedback information parameters may be applied to each link.

[0182] Method 2-2 allows, for example, STA 200 to autonomously control the distribution method of feedback information for each link based on the usage status of each link of STA 200, thereby improving frequency utilization efficiency.

[0183] In the method of distributing feedback information described in Control Method 2, the feedback information may be distributed to each link based on, for example, a subcarrier index or a frequency resource unit index.

[0184] In addition, in control method 2, an example has been described in which BFRP is used as the type of trigger frame when control information related to the transmission of feedback information is notified to STA200 by a trigger frame, but control information related to multilink feedback may also be notified to STA200 by a trigger frame type other than BFRP.

[0185] Control method 1 and control method 2 have been described above.

[0186] Note that control method 1 (notification of Link ID) and control method 2 (notification of feedback information distribution method) may be applied in combination or individually. For example, when control method 1 and control method 2 are combined, the distribution of feedback information set by control method 2 may be applied to multiple links used for feedback transmission set by control method 1. Also, for example, when control method 1 is not applied and control method 2 is applied, the distribution of feedback information set by control method 2 may be applied to multiple links set in STA 200.

[0187] The embodiments of the present disclosure have been described above.

[0188] (Other embodiments) (1) In the above-described control method 1 and control method 2, the STA 200 transmits feedback information including information (e.g., reception quality) acquired from an NDP (e.g., a reference signal included in the NDP) via multiple links. However, the feedback information may be acquired (or generated or estimated) based on a signal other than the NDP. For example, the STA 200 may transmit feedback information acquired from a reference signal included in a packet other than the NDP (e.g., referred to as a "non-NDP PPDU") via multiple links, such as "Staggered Sounding" described in Non-Patent Document 3.

[0189] FIG. 29 is a sequence diagram showing an example of an operation when the AP 100 instructs the STA 200 to perform multilink transmission of feedback information acquired from a non-NDP PPDU.

[0190] 29, an example of the feedback information transmission operation of an AP 100 (e.g., AP) having two links and two STAs 200 (e.g., STA1 and STA2) will be described. Note that the number of links used in multi-link feedback may be "2" or more. Also, the number of STAs that transmit feedback information obtained from a non-NDP PPDU via multi-link transmission is not limited to two, and may be three or more.

[0191] 29, the AP transmits an NDPA including control information related to feedback transmission to, for example, STA1 and STA2 via link 1 and link 2 (S301). STA1 and STA2 perform reception processing of the NDPA via, for example, link 1 and link 2, respectively, and acquire the control information related to feedback transmission (S302).

[0192] The AP transmits, for example, an NDP on link 1 and link 2 (S303). STA1 and STA2 perform reception processing of the NDP based on, for example, control information acquired from the NDPA (S304), and generate channel estimation values ​​and feedback information corresponding to link 1 and link 2, respectively (S305).

[0193] The AP transmits, for example, a Trigger frame (S306). For example, the AP may use the Trigger frame of the BFRP to notify STA1 and STA2 of control information (e.g., bandwidth, transmit power, assigned RU, MCS, or assigned spatial streams) and transmission timing for transmitting feedback information to UL MUs on each link.

[0194] STA1 and STA2 perform, for example, a process of receiving a trigger frame (S307). For example, by receiving the trigger frame, STA1 and STA2 obtain control information for transmitting feedback information by UL MU-MIMO, and transmit the feedback information (for example, a UL MU-MIMO signal) to the AP by UL MU-MIMO on link 1 and link 2, respectively, at the transmission timing indicated by the trigger frame (S308).

[0195] The AP receives the UL MU-MIMO signals transmitted from STA1 and STA2 and obtains feedback information (S309). The AP may, for example, perform scheduling for DL ​​MU-MIMO transmission based on the feedback information and generate steering matrices for each link. The AP may also, for example, perform null control on the steering matrices to reduce interference between the STAs.

[0196] For example, the AP adds steering matrices to DL MU-MIMO signals (for example, a reference signal included in a preamble portion and a data portion (DL MU PPDU)) for STA1 and STA2 and transmits the signals (S310). In addition, the AP may store the generated steering matrices in a buffer, for example.

[0197] STA1 and STA2 perform, for example, reception processing of DL MU-MIMO signals (e.g., DL MU PPDUs) (S311). For example, STA1 and STA2 may perform channel estimation using reference signals included in the preamble sections of the DL MU-MIMO signals to extract signals addressed to the STAs. Furthermore, STA1 and STA2 may measure the reception quality of the reference signals addressed to the STAs (e.g., desired signals) and reference signals addressed to other STAs spatially multiplexed in the same RU as the STAs (e.g., inter-user interference signals) from the reference signals included in the preamble sections of the DL MU-MIMO signals (in other words, non-NDP PPDUs).

[0198] The reception quality may include, for example, the error determination result of the desired signal, the signal to interference plus noise ratio (SINR) of the desired signal, the power value of the inter-user interference signal, the desired signal to undesired signal ratio (DUR) between the desired signal and the inter-user interference signal, the change in desired signal power from the previous MU-MIMO signal, the change in inter-user interference signal power, the change in desired signal power between the desired signal power of NDP sounding and the MU-MIMO signal, or the change in inter-user interference signal power.

[0199] STA1 and STA2 may, for example, perform reception quality judgment based on a threshold for the desired signal and the inter-user interference signal, and determine (or judge) the spatial stream for transmitting the feedback information (S312). Note that when the desired signal and the inter-user interference signal include multiple spatial streams, STA1 and STA2 may, for example, perform reception quality judgment for each spatial stream.

[0200] STA1 and STA2 transmit, for example, a response signal (e.g., Block ACK) to the DL MU-MIMO signal (S313). Furthermore, when there is feedback information to transmit based on the reception quality determination of the desired signal and the inter-user interference signal, each STA may transmit a signal (e.g., Trigger request) requesting transmission of a Trigger frame that prompts transmission of the feedback information, in the response signal.

[0201] For example, when the AP receives response signals including a Trigger request from STA1 and STA2, the AP schedules multilink feedback and transmits control information related to the multilink feedback to each STA by including it in a Trigger frame of BFRP (S314).

[0202] STA1 and STA2, for example, perform a receiving process of a BFRP Trigger frame and acquire control information related to multilink feedback transmission (S315). STA1 and STA2, for example, perform multilink feedback to the AP at the timing instructed by the BFRP (S316). For example, in the example shown in FIG. 29, STA1 uses link 1 to transmit feedback information related to link 1 and link 2 to the AP. Also, in the example shown in FIG. 29, STA2 uses link 2 to transmit feedback information related to link 1 and link 2 to the AP.

[0203] The AP receives, for example, feedback information transmitted from the STAs (S317). The AP may reconstruct the feedback information transmitted over multiple links, for example, based on control information related to multilink feedback included in the BFRP or control information included in the feedback information. The AP may also identify, for example, based on the control information included in the feedback information, which spatial stream the feedback information is addressed to. The AP may update the steering matrix stored in the buffer, for example, based on newly acquired feedback information, and store the updated steering matrix in the buffer again. The AP may also change the scheduling of DL MU-MIMO transmission (for example, RU allocation or user allocation) based on the feedback information transmitted from STA1 and STA2. The AP may also transmit an ACK signal on each link, for example, according to the result of receiving and processing the feedback information (S318).

[0204] Note that, in FIG. 29, an example is described in which each STA transmits feedback information obtained from DL MU-MIMO signals (in other words, non-NDP PPDUs) addressed to two STAs via multilink transmission, but this is not limited to this. For example, feedback information obtained from a DL SU signal addressed to a single STA may be transmitted via multilink transmission, as in staggered sounding.

[0205] (2) For example, the AP 100 may cooperate with a plurality of APs (for example, referred to as "multi-AP") and instruct the STA 200 to perform multi-link transmission of feedback information to each AP.

[0206] FIG. 30 is a sequence diagram of an example of operation when the AP 100 notifies (or instructs) the STA 200 to perform multi-link transmission of feedback information related to multiple APs.

[0207] In Figure 30, as an example, an example of the operation of transmitting feedback information in two APs 100 (e.g., AP1 and AP2) having two links (e.g., link 1 and link 2) and one STA 200 (e.g., STA1) will be described.

[0208] The number of links used in multi-link feedback may be two or more. The number of APs cooperating as multi-AP is not limited to two, but may be three or more. The number of STAs notifying multi-link transmission of feedback information related to multi-AP is not limited to one, but may be two or more.

[0209] 30, AP1, which controls multi-AP transmission, transmits a Multi-AP Trigger to AP2, which transmits in cooperation with AP1 (S401). By transmitting the Multi-AP Trigger, control information related to the cooperative transmission of NDPA and NDP (for example, information indicating whether to notify multilink feedback, transmission timing, transmission power information, etc.) may be notified from AP1 to AP2.

[0210] For example, at the timing notified by a Multi-AP Trigger from AP1 to AP2, AP1 and AP2 simultaneously transmit an NDPA and an NDP containing control information regarding multilink feedback (called "Joint sounding") (e.g., S402 and S404).

[0211] STA1, for example, performs reception processing of the NDPA on each of link 1 and link 2, and acquires control information related to multi-link transmission of feedback information (S402). STA1 also performs reception processing of the NDP on each of link 1 and link 2, for example (S405), and generates a channel estimation value and feedback information for each AP (S406). STA1 also determines the link to be used for transmitting the feedback information, for example, based on the control information included in the NDPA, and transmits the feedback information to each AP (S407). In the example shown in FIG. 30, STA1 transmits feedback information for link 1 and link 2 of AP1 on link 1, and transmits feedback information for link 1 and link 2 of AP2 on link 2.

[0212] AP1 and AP2 receive feedback information, for example, on link 1 or link 2 (S408), and transmit an ACK signal to STA1 according to the result of the reception processing of the feedback information (S409). AP1 and AP2 may transmit the ACK signal, for example, on the link on which the feedback information was received.

[0213] (3) In control method 1 (notification of Link ID), the AP 100 may notify the STA 200 of the link to be used for feedback transmission, for example, by a method other than transmission of the Link ID.

[0214] As an example, the link used for feedback transmission may be notified to STA 200 based on a combination of a frequency band (eg, Bandwidth (BW) or Channel BW) and a channel identifier (eg, Channel ID).

[0215] For example, the AP 100 may notify the STA 200 of a frequency band in the BW field and may notify the STA 200 of a channel identifier in the Channel ID field, as shown in Fig. 31. For example, the frequency band (e.g., 2.4 GHz, 5 GHz, or 6 GHz) used by the STA 200 may be notified in the BW field, as shown in Fig. 32. Furthermore, for example, as shown in Fig. 32, the Channel ID field may notify channel IDs assigned in ascending order to available channel numbers (ch) for each frequency band (e.g., 2.4 GHz, 5 GHz, or 6 GHz in Fig. 32) notified in the BW field.

[0216] The STA 200 may determine a link (e.g., a channel) to be used for feedback transmission, based on, for example, a combination of a frequency band and a channel ID notified by the AP 100. For example, in Fig. 32, when the frequency band is BW=01 (5 GHz) and the channel ID=0001, the STA 200 may determine 40ch, which corresponds to the combination of BW=01 and the channel ID=0001, as the link to be used for feedback transmission.

[0217] The values ​​or bit numbers of the frequency bands and channel IDs shown in FIG. 32 are merely examples, and other values ​​or bit numbers may be used.

[0218] As another example, the link to be used for feedback transmission may be notified to STA200 based on a combination of a frequency band (e.g., BW) and a frequency offset value (e.g., channel offset) for one of the multiple links (e.g., link 1).

[0219] For example, as shown in FIG. 33, AP100 may notify STA200 of the frequency band in the BW field, and may notify STA200 of the coefficient for the offset value based on the frequency difference between the center frequency of link 1 and the center frequency of other links in the channel offset field.

[0220] 34, for example, a frequency difference between adjacent channels (e.g., ΔChannel frequency) is determined for each frequency band notified to the STA 200. For example, in the 2.4 GHz band, if the difference in center frequency between link 1 and link 2 is 40 MHz, the frequency offset value is expressed as 40 MHz = 5 MHz * 8, which is the product of the frequency difference ΔChannel frequency between the channels and a coefficient. Therefore, the AP 100 may notify the STA 200 of, for example, BW = 00 (2.4 GHz) and channel offset = 1000 (e.g., 8).

[0221] 34 are merely examples, and other values ​​or bit numbers may be used. Furthermore, the control information notified from AP 100 to STA 200 is not limited to the coefficients described above, and may be any information or parameter indicating the frequency difference between the center frequency of link 1 and the center frequency of other links.

[0222] (4) Information transmitted via multilink is not limited to feedback information.

[0223] For example, the STA 200 may transmit a response signal (eg, ACK, BA) or a link adaptation signal over multiple links.

[0224] (5) In the above embodiment, a configuration example based on the 11ax frame format has been described as an example. However, the format to which an embodiment of the present disclosure is applied is not limited to the 11ax format.

[0225] (6) In the above embodiment, the operation in DL communication has been described. However, an embodiment of the present disclosure is not limited to DL communication and may be applied to, for example, UL communication or sidelink.

[0226] (7) The present disclosure can be realized by software, hardware, or software linked to hardware. Each functional block used in the description of the above embodiments may be realized, in part or in whole, as an LSI, which is an integrated circuit, and each process described in the above embodiments may be controlled, in part or in whole, by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may be called an IC, system LSI, super LSI, or ultra LSI.

[0227] The integrated circuit method is not limited to LSI, but may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0228] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology can be used to integrate functional blocks. The application of biotechnology is also a possibility.

[0229] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a wireless transceiver and processing / control circuitry. The wireless transceiver may include a receiver and a transmitter, or both functions. The wireless transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0230] Communications equipment is not limited to portable or mobile equipment, but also includes non-portable or fixed equipment, devices, and systems of any kind, such as smart home devices (such as appliances, lighting equipment, smart meters or metering devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0231] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0232] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0233] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0234] A communication device according to an embodiment of the present disclosure includes a control circuit that controls multi-link transmission based on control information related to the multi-link transmission, and a transmission circuit that performs the multi-link transmission in accordance with the control of the multi-link transmission.

[0235] In one embodiment of the present disclosure, the control information includes identification information of links that can be used for the multi-link transmission, and the control circuit determines, based on the identification information, a link from the multi-links to be used for transmitting the feedback information.

[0236] In one embodiment of the present disclosure, the amount of information in the identification information is based on either a predefined number of links or the number of links set in the access point.

[0237] In one embodiment of the present disclosure, the control circuit determines a link to which transmission of the feedback information is assigned in the multi-link transmission based on a predefined rule.

[0238] In one embodiment of the present disclosure, the rule is based on the number of spatial streams included in the feedback information and the bandwidth of each link used to transmit the feedback information.

[0239] In one embodiment of the present disclosure, the rule is based on the type of the feedback information.

[0240] In one embodiment of the present disclosure, the control circuit determines to use a link different from the link on which the control information is received to transmit feedback information in the multi-link transmission.

[0241] In one embodiment of the present disclosure, the control circuit synchronizes the transmission timing of feedback information between links in the multi-link transmission.

[0242] In one embodiment of the present disclosure, the control circuit varies the timing of transmitting feedback information between links in the multi-link transmission.

[0243] In one embodiment of the present disclosure, the control circuit allocates feedback information for each of a plurality of links to some of the links in the multi-link transmission.

[0244] In one embodiment of the present disclosure, the control information includes information regarding distribution of feedback information to multiple links in the multi-link transmission, and the control circuit determines distribution of the feedback information among links in the multi-link transmission based on the information regarding the distribution.

[0245] In one embodiment of the present disclosure, the control information includes information regarding the spatial streams included in the feedback information transmitted on each link.

[0246] In one embodiment of the present disclosure, the control information includes information about a frequency band included in feedback information transmitted on each link.

[0247] In one embodiment of the present disclosure, the control information includes information regarding the type of feedback information to be transmitted on each link.

[0248] In one embodiment of the present disclosure, the method further includes a receiving circuit for receiving the control information from an access point, wherein the control circuit determines, based on the control information, a distribution of feedback information among links in the multi-link transmission to the access point.

[0249] In one embodiment of the present disclosure, the control information is included in a Trigger frame.

[0250] In one embodiment of the present disclosure, the control information is included in a Trigger dependent user info field.

[0251] In one embodiment of the present disclosure, the control information is included in a null data packet announcement (NDPA).

[0252] In one embodiment of the present disclosure, the transmitting circuit transmits information regarding distribution of feedback information among links in the multi-link transmission to the access point via the feedback information.

[0253] A communication device according to one embodiment of the present disclosure includes a control circuit that controls reception of the multi-link transmission by the other communication device based on control information related to the multi-link transmission, and a receiving circuit that receives the multi-link transmission by the other communication device in accordance with the control of the reception.

[0254] In a communication method according to an embodiment of the present disclosure, a communication device controls multi-link transmission based on control information related to the multi-link transmission, and performs the multi-link transmission according to the control of the multi-link transmission.

[0255] In a communication method according to one embodiment of the present disclosure, a communication device controls reception of the multi-link transmission by the other communication device based on control information related to the multi-link transmission, and receives the multi-link transmission by the other communication device in accordance with the control of the reception.

[0256] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2020-143901, filed on August 27, 2020, are incorporated herein by reference in their entirety. [Industrial Applicability]

[0257] One embodiment of the present disclosure is useful in wireless communication systems. [Explanation of symbols]

[0258] 100 AP 101-1, 101-2, 201-1, 201-2 Radio receiving unit 102 Received signal decoding unit 103 Feedback information reconstruction unit 104 Multi-link scheduling unit 105 Data Generation Unit 106 Preamble generation section 107-1, 107-2, 206-1, 206-2 Radio transmitter 200 STA 202-1, 202-2 Preamble demodulation section 203-1, 203-2 Data decoding section 204 Multi-link control unit 205 Transmission signal generation unit

Claims

1. A multi-link device (MLD) having a plurality of affiliated STAs corresponding to a plurality of links, a receiving circuit for receiving a reference signal transmitted from another MLD on a first link; a transmission circuit that transmits beamforming feedback information for the first link, generated based on the reference signal, to the other MLD via a second link different from the first link; MLD equipped with.

2. the receiving circuit receives control information relating to transmission of the feedback information over the second link; the transmission circuit transmits the feedback information based on the control information. The MLD according to claim 1.

3. the control information includes identification information of two or more links usable for multi-link transmission of the feedback information; the transmitting circuit transmits the feedback information based on the identification information. The MLD according to claim 2.

4. The identification information includes a Link ID bitmap consisting of a plurality of bits, each of which indicates whether a corresponding link is used for feedback transmission. The MLD according to claim 3.

5. The reference signal is included in the preamble of a Null Data Packet (NDP). The MLD according to claim 1.

6. the control information is included in a frame requesting transmission of the feedback information; the transmitting circuit transmits the feedback information after receiving the frame. The MLD according to claim 2.

7. The frame is a trigger frame or a Null Data Packet Announcement (NDPA) frame. The MLD according to claim 6.

8. 1. A communication method for a multi-link device (MLD) having a plurality of affiliated STAs corresponding to a plurality of links, comprising: receiving a reference signal transmitted from another MLD on a first link; transmitting beamforming feedback information for the first link, which is generated based on the reference signal, to the other MLD over a second link different from the first link; Communication method.

9. receiving control information on the second link relating to transmission of the feedback information; transmitting the feedback information based on the control information; The communication method according to claim 8.

10. the control information includes identification information of two or more links usable for multi-link transmission of the feedback information; transmitting the feedback information based on the identification information; The communication method according to claim 9.

11. The identification information includes a Link ID bitmap consisting of a plurality of bits, each of which indicates whether a corresponding link is used for feedback transmission. The communication method according to claim 10.

12. The reference signal is included in the preamble of a Null Data Packet (NDP). The communication method according to claim 8.

13. the control information is included in a frame requesting transmission of the feedback information; transmitting the feedback information after receiving the frame; The communication method according to claim 9.

14. The frame is a trigger frame or a Null Data Packet Announcement (NDPA) frame. The communication method according to claim 13.

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