Access Point, Station, and Corresponding Method

Abstract

the first access point, comprising: a circuit configured to perform a sounding process with one or more first stations associated with the first access point and configured to communicate with the first access point over respective channels; calculate a resource unit allocation and a beamforming configuration to be used for subsequent communication with each first station; and transmit a training data unit including signaling information related to the calculated resource unit allocation and the calculated beamforming configuration, the training data unit being transmitted together with the beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration.

Description

Technical Field

[0001] The present disclosure relates to different access points, stations, and corresponding methods.

Background Art

[0002] Low-latency or real-time applications have strict requirements for rapid or periodic channel access. For example, in a Basic Service Set (BSS) (hereinafter also referred to as a cell) of a single wireless LAN where one or more Stations (STAs) are associated with a single Access Point (AP) that provides communication services to the one or more Stations, these requirements are relatively easy to achieve. However, this is not the case when a station exists within the scope of multiple Overlapping BSSs (OBSSs) managed by different access points such that one or more other stations are associated with their respective other BSSs (plural possible). One or more of other stations (also referred to as overlapping Stations (oSTAs)) associated with another access point that provides communication services to another BSS are within the scope of the access point that provides communication services to the one or more stations.

[0003] Spatial Reuse (SR) technology is defined in the upcoming 802.11ax amendment to the IEEE 802.11 standard. Thereby, as long as it is guaranteed that interference at the access point is below the allowable level, the oSTAs of the overlapping BSSs can transmit during the time period scheduled by the access point.

[0004] The description of the background art presented herein is for schematically showing the background of the present disclosure. Each aspect of the description that is not suitable as prior art at the time of filing, and the research of the inventor(s) currently shown within the scope described in this background art, is not admitted as prior art to this technology, whether explicitly or implicitly.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, there may be a need for an improved data storage method and an improved privacy protection data storage system that particularly analyze the travel behavior of one or more users of a transportation service as Mobility as a Service (MaaS).

Means for Solving the Problems

[0007] It is an object to provide an access point that enables improved downlink spatial reuse. A further object is to provide a corresponding method, and a corresponding computer program and a non-transitory computer-readable recording medium for implementing the method.

[0008] According to one aspect, a first access point executes sounding processing using one or more first stations that are associated with the first access point and configured to communicate with the first access point via respective channels, calculates resource unit allocation and beamforming configuration to be used for subsequent communication with each of the first stations, and is a training data unit including signaling information related to the calculated resource unit allocation and the calculated beamforming configuration, and is configured to transmit the training data unit transmitted together with a beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration. A first access point is provided that includes a circuit.

[0009] According to a further aspect, a response data unit transmitted by one or more first stations that are a second access point, associated with the first access point, and configured to communicate with the first access point via respective channels, listens to the response data unit transmitted by the one or more first stations in a downlink sounding process executed by the first access point using the one or more first stations, estimates the respective channels using the received response data unit, a training data unit transmitted by the first access point, includes signaling information related to a resource unit allocation and a beamforming configuration calculated by the first access point for subsequent communication with each first station, listens to the training data unit transmitted together with the beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration, and based on the signaling information included in the received training data unit, calculates a resource unit allocation and a beamforming configuration for subsequent communication with one or more second stations associated with the second access point. A second access point is provided that comprises a circuit configured as such.

[0010] According to a further aspect, there is provided a second station comprising a circuit configured to listen for training data transmitted by a first access point to which one or more first stations are associated for communicating with the first access point via respective channels, the training data unit including signaling information related to a resource unit allocation and a beamforming configuration calculated by the first access point for subsequent communication with each of the first stations, and beamforming configurations derived from the calculated resource unit allocation and the calculated beamforming configuration, estimate channel and / or interference information based on the received training data unit, and transmit the estimated channel and / or interference information to a second access point to which the second station is associated for communicating via the channel.

[0011] According to another further aspect, there is provided a corresponding method, a computer program including a program which, when executed on a computer, causes the computer to execute the steps of the method disclosed herein, and a non-transitory computer-readable recording medium storing a computer program product which, when executed by a processor, causes the method disclosed herein to be executed.

[0012] Embodiments are defined in the independent claims. It should be understood that the disclosed stations, the disclosed methods, the disclosed computer programs and the disclosed computer-readable recording media have further embodiments similar and / or identical to those defined in the claimed access points and defined in and / or disclosed herein.

[0013] One of the aspects of the present disclosure enables spatial reuse by beamforming with minimal cooperation between access points. This is particularly suitable for scenarios where an access point cannot or does not intend to perform interference cancellation, but can assist other access points in obtaining information necessary for spatial reuse by beamforming. The method includes introducing a new training data unit, and based on the new training data unit, a cascaded sounding protocol can be devised. Also, appropriate control message flows and examples applicable to an 802.11 multi-access point scenario are presented.

[0014] The above paragraph is provided as a general introduction and is not intended to limit the following claims. The described embodiments will be best understood by reference to the following detailed description in conjunction with the accompanying drawings, along with further advantages.

[0015] A more complete understanding of the present disclosure, and many of its attendant advantages, will be readily obtained by reading the following detailed description in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0016]

Figure 1

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Embodiments for Carrying Out the Invention

[0017] The object of the present disclosure is that an access point (also referred to as oAP or second AP in this specification) within a certain overlapping BSS (oBSS) learns about necessary channel state information and shared resource allocation, and further designs appropriate beamforming techniques for stations (also referred to as oSTA or second stations in this specification) within the oBSS without adjustment by a master device (e.g., a master access point). In a wireless LAN scenario, it is to enable spatial reuse by opportunistic beamforming. The involvement of the AP that permits access of other stations to its spectrum during downlink transmission is minimal, and includes the oAP sharing the information necessary to calculate the opportunity for spatial reuse (however, no decision is made about the shared spectrum).

[0018] FIG. 1 is a schematic diagram of an exemplary embodiment of a communication system according to the present disclosure. One AP having a plurality of antennas performs OFDMA transmission to stations (also referred to as first stations in this specification) STA1 to STA_N. Here, one or more of the resource units use the downlink (DL) multi-user (MU) MIMO mode. The downlink MU-MIMO beamforming method employed by AP1 does not consider at all the minimization of interference to STAs outside its BSS. On the other hand, an AP outside the BSS may be able to utilize the spectrum already being used by appropriately applying beamforming technology by AP1. In FIG. 1, arrow 10 indicates a useful DL signal using the first resource unit RU1. Also, arrow 11 indicates a useful DL signal using the second resource unit RU2. Arrow 12 indicates interference using the first resource unit RU1. Arrow 13 indicates interference using the second resource unit RU2.

[0019] Accordingly, AP1 is selfish, that is, there is no interference nulling for oSTAs, but beamforming is applied only to its own stations STA1 to STA_N, and it is assumed that the sounding process is executed only by its own stations. Also, it is assumed that oAPi knows the channel for STA1 and has the interference nulling ability, and oSTA reports to the associated oAPs of those counterparts.

[0020] Note that hereinafter, the present disclosure will be mainly described with reference to a general case of MU-OFDMA. However, specific cases of non-OFDMA or single user (SU) transmission can be handled in the same way. For example, this can be implemented assuming that one resource unit occupies the entire bandwidth of the channel being used for transmission.

[0021] The stations and access points used in the present disclosure can be realized by appropriate hardware and / or software. For example, the above devices can include circuits configured to execute their respective operations. This circuit can be interpreted as a programmed processor or computer, or as a dedicated hardware element created to execute some operations such as each unit or part. For example, the disclosed device can be realized by a processing unit (for example, for executing signal processing), a communication unit (for example, for transmitting and receiving signals), and a control unit (for example, for controlling the processing unit and / or the communication unit and / or for controlling the overall operation).

[0022] Currently, there are mainly two methods that enable spatial reuse. One method considers a transmission power control-based method in which different APs notify whether spatial reuse is acceptable and under which parameters it is acceptable. Based on these methods, the oAP can reuse spatial resources when it can adapt the transmission parameters to comply with the interference conditions indicated by the AP. In this case, adjustment from the AP side is not required. However, the method defined in this context only considers power control and does not consider beamforming spatial reuse.

[0023] Another approach that enables spatial reuse through more advanced beamforming is to define a cooperation scheme in which the AP sharing the resources also adjusts the activities of the oAP using the resources. However, in order to nullify the interference to STAs outside the BSS, the AP loses the freedom to provide communication services to its own traffic. Further, by participating in cooperative beamforming sounding, overhead is formed for the AP and associated STAs. Most of the overhead is due to the fact that the oSTAs whose interference is to be nullified need to be known in advance at the AP and it is necessary to collect this channel state information. Such overhead may lack rationality, for example, when the AP cannot or does not intend to perform spatial reuse by beamforming. However, just because the AP is not actively nullifying interference to known oSTAs does not mean that other BSSs that can perform more aggressive interference-nullifying beamforming cannot reuse the spatial resources.

[0024] Contrary to existing methods, the present disclosure focuses on developing a method that does not consider adjustments from the master AP. The idea of the present disclosure is as follows. For each scenario assumption, since AP1 is not involved in the cooperative beamforming method, it has little incentive to spend time resources on cooperative training. Therefore, AP1 performs sounding for STAs belonging to its own BSS without sharing resources for STAs in other oBSSs. On the other hand, this enables the oAP to collect indications showing whether channel state information (CSI), resource unit allocation, beamforming information, and / or spatial reuse is permitted, and under what conditions spatial reuse is permitted. For this purpose, AP1 constructs a physical protocol data unit (PPDU) to be transmitted after performing sounding using STAs associated with itself, such that the oSTA can measure the interference experienced by the newly calculated beamforming vectors or these functions. The PPDU is transmitted so that the oSTA and the oAP can obtain information regarding channel estimation values and spatial reuse opportunities, i.e., from AP1, and is hereinafter referred to as a training data unit. Based on specific control information extracted from the packet transmitted by AP1 and the channel estimation from the STA during sounding, the oAP determines whether there are resources that can be shared in the spatial or spectral domain. If so, the oAP requests a series of measurement results from the oSTA and designs a beamforming vector towards a specific oSTA with respect to the interference constraints for STAs 1 to STA_N. The oSTA and the oAP should be able to continue decoding the training data unit even when it is transmitted by an AP with which they are not associated. To enable this, the addressing of the training data unit can be a broadcast address or the identifier of the oSTA or oBSS based on some prior exchange of information between the AP and the corresponding oAP.

[0025] Figure 2 is a schematic diagram showing an embodiment of the method according to the present disclosure using explicit sounding. This embodiment particularly shows the training flow assuming explicit sounding at AP1.

[0026] The first part 20 of the sounding process from AP1 to STA1 to STA_N associated with the AP1 is, in this embodiment, a normal DL sounding process. The downlink sounding process 20 is executed so that AP1 can calculate resource unit allocation and beamforming configuration used for subsequent communication with each of the stations STA1 to STA_N.

[0027] In this embodiment, the downlink sounding process 20 includes a null data packet (NDP) announcement 21 including information regarding necessary training, that is, STA participation, resource unit (RU) and bandwidth (BW) information, and the type of requested feedback. After the null data packet (NDP) announcement 21, one or more (particularly, a series of) NDP packets 22 follow. Preferably, if the purpose of the one or more NDP packets is for STA to estimate the channel from AP1 for all the streams to be transmitted, the NDP packet 22 includes only the PHY layer preamble (synchronization, estimation, and control fields) and does not include a data field. Then, AP1 requests feedback information (that is, a response) from STA1 to STA_N by transmitting, for example, a beamforming report (BFRP) trigger frame 23. The beamforming report (BFRP) trigger frame 23 includes the STA that needs to respond and the resource unit related thereto. Then, the requested STA responds by transmitting a response 24 (that is, feedback), for example, by transmitting a trigger-based (TB) response PPDU respectively.

[0028] From the perspective of AP1 and STA1~STA_N, the previous processing has followed the same steps as the normal DL sounding phase. However, based on the exchange of this frame (especially the transmission of response 24), oAP1 can estimate the channel within the resource unit allocated for the response. To enable a more accurate estimation in the oAP, as a proposal, the definition of response 24, especially the trigger-based PPDU, is improved as follows. The estimation sequence (e.g., E-STF (Estimation Short Training Field) and E-LTF (Estimation Long Training Field)) is transmitted in an orthogonal manner through all subcarriers of the channel including the STA-specific resource unit. On the other hand, the data part is transmitted only through the STA-specific resource unit.

[0029] After the sounding process 20, AP1 transmits the training data unit 25. Thereby, the oSTA can estimate the channel or measure the interference to the channel that may occur after the AP1 applies the newly calculated beamforming vector. The training data unit 25 includes signaling information regarding the calculated resource unit allocation and beamforming configuration. In a preferred embodiment, the training data unit 25 can be a packet such as an NDP without a data field, for example, a PPDU. This may include several fields including an L-P field, a signaling field, and a training field.

[0030] L-P indicates a legacy preamble including legacy synchronization, followed by a legacy estimation sequence.

[0031] U+E refers to the signaling field. This signaling field holds control information that characterizes and decodes the packet, and includes a Universal SIG field (U-SIG) that indicates information independent of the standard version, and a version-dependent signaling field (E-SIG) that depends on the current standard version adopted for communication, such as EHT (Extremely High Throughput) communication. The use of the EHT signaling field is exemplary. Training data units can also be embedded in VHT (Very High Throughput) type PPDUs, in which case only the version-dependent signaling field exists. The SIG field can include information necessary to correctly decode the packet. In one embodiment, the SIG field may include information regarding resource unit allocation, spatial-time stream, and beam mapping. oAP1 can use this information to determine which STA is allocated to which resource unit and whether the channel estimation available at the specific resource unit corresponding to the specific STA used is accurate.

[0032] The transmission beamforming parameters to be used, i.e., the identifier of the STA to which the beamforming parameters are applied, the beamforming configuration, and optionally, the resource unit allocation can be mapped to a session index. In another embodiment, the session index may further be included in the SIG field. The session index indicates the beamforming configuration used by AP1. Based on this information, the oSTA can determine whether it needs to take some countermeasures, e.g., perform an update or report measurement values. Based on the session index, the oAP can request a measurement report and determine whether it has accurate channel information. Based on the session index and together with the set of corresponding channel measurement values, the oAP can determine whether spatial reuse may be possible for a particular session and can inform the oSTAs participating in the particular session of the opportunity for spatial reuse.

[0033] E-STF and E-LTF are synchronization and estimation sequences, respectively, and as shown in FIG. 2, for example, they can be transmitted using a VHT or EHT modulation format on specific resources indicated within the SIG field. These fields are calculated after the sounding phase and are transmitted together with the beamforming weighting matrix used during the next data transmission between AP1 and STA1~STA_N. Let these beamforming weighting matrices be denoted as Q. Since the operation of applying the beamforming matrix corresponds to multiplication for each frequency bin, the sequences after beamforming are shown as Q STF and Q LTF in FIG. 2. The Q matrix can be the beamforming weighting matrix used in the next transmission stage of AP1 regarding the MU-MIMO configuration after training or this function. More precisely, in transmission, the matrix Q is defined based on the resource units used. However, for example, a Q matrix defined with lower granularity on the channel bandwidth rather than at the granularity of resource units or a Q matrix considering some robustness margin for interference protection can also be used. By modulating the STF and LTF fields using the most recently calculated beamforming weighting matrix, the channel or interference level after beamforming is estimated at oSTA.

[0034] To transmit the training data unit 25, preferably, information regarding the beamforming configuration calculated in the preceding sounding process 20 is used. For example, the training data unit 25 can be transmitted such that a set of estimation sequences included in the signaling information is modulated by the beamforming weights calculated after sounding based on the sounding information obtained in the sounding process 20.

[0035] The transmission of the training data unit 25 can be announced by the NDP announcement 21. Thereby, the oAP is made to understand that it is necessary to estimate the channels of STA1 to STA_N and prepare for determining the possibility of SR transmission. Further, thereby, during the sounding period including the transmission of the training data unit, the channel is made busy. In one embodiment, the training data unit is transmitted after the SIFS (Short Interframe Space) time after the feedback trigger-based PPDU. However, it is also possible to transmit the training data unit within a separate Transmit Opportunity.

[0036] After estimating the channel of the STA based on the response 24 (e.g., trigger-based PPDU) and confirming that the resource unit for which the estimated value is calculated is the same as or approximates the one to be used during the subsequent MU-MIMO transmission from AP1 based on the training data unit 25, the oAP1 collects measurement reports from a specific set of oSTAs. To do this, the oAP1 can transmit the trigger frame 26. In response to the trigger frame 26, the oSTA transmits a trigger-based PPDU 27 including a report on, for example, the requested resource unit and the interference level, respectively. Finally, the oAP1 transmits an SR confirmation response (Ack) 28. The SR confirmation response (Ack) 28 causes the oSTA to participate in the next shared Transmit Opportunity (TXOP). Also, the SR confirmation response (Ack) 28 can indicate a resource unit allocation and a session index. This resource unit allocation corresponds to only a given session index. When different session indexes are informed to AP1, the above-described operations are repeated. The session index preferably corresponds to the same group and is used for subsequent data transmission from AP1 to STA having the same beamforming configuration as the one currently in use.

[0037] If multiple MIMO configurations for one or more sets of stations are calculated as part of the training, the proposed training data unit 25' can be designed to include information regarding these configurations. This is shown in FIG. 3. FIG. 3 is a schematic diagram showing another embodiment of the method according to the present disclosure using explicit sounding. In this embodiment of the training data unit 25', after the legacy and SIG fields, a synchronization and estimation sequence, for example, an EHT modulated STF and LTF are transmitted, followed by a frame including a set of possible configurations. Thereafter, for example, in packet extension, one or more beamforming configurations can modulate an additional LTF field to cause the oSTA to measure the channel and / or interference level from AP1 to the oSTA. Packet extension refers to the addition of some additional padding or in this case, an estimation sequence after the data part of a normal PPDU. The presence of these fields needs to be indicated in the preamble of the packet. The Q matrix applied in this case is defined for each resource unit and corresponds at least to the first configuration used for data transmission.

[0038] In the embodiments shown in FIGS. 2 and 3, the training data unit 25 is a PPDU that is transmitted together with the beamforming weights calculated during the same sounding period, i.e., during the DL sounding process 20. According to the embodiment shown in FIG. 2, the training data unit (i.e., the training PPDU) does not carry a MAC frame and consists only of a PHY preamble. According to the embodiment shown in FIG. 3, the training data unit is a PPDU that carries MAC data, but the content of the data is control information regarding resource unit allocation, STA identifier, and beamforming configuration. There are several cases where it may be useful to include control information in the training data unit. As a first case, the training PPDU may be transmitted in the form of a single-user PPDU. In this case, it is impossible to include control information for all stations. As a second case, multiple MIMO configurations may be calculated during sounding and it may not be possible to carry them in the preamble of the packet. In the latter case, the training data unit is a PPDU that includes a PHY preamble, a frame including control information, and an additional estimation sequence corresponding to the beamforming configuration shown in the frame.

[0039] The ideas described above with respect to FIGS. 2 and 3 can also be applied to the case of implicit sounding between the AP and STAs 1 to STAs_N. FIG. 4 shows a schematic diagram showing an embodiment of the method according to the present disclosure using implicit sounding. The advantage of implicit training is that in this case, the oAP can calculate the channels from STAs 1 to STAs_N over the entire bandwidth or the entire range of resource units for which the AP1 will determine the last resource unit and the beamforming allocation. By comparison, in the embodiments shown in FIGS. 2 and 3, the oAP can correctly estimate only the channels on the specific resource unit allocation to which the station responds to the feedback request.

[0040] In the embodiment shown in FIG. 4, training (i.e., downlink sounding process 40) starts particularly from a response request 41 to STAs STA1 to STAN by transmitting a trigger frame. The trigger frame indicates parameters based on which a second STA transmits a subsequent response 42. These parameters are channel and bandwidth information, the number of orthogonal synchronization and estimation sequences used by each STA, an identifier indicating which synchronization and estimation sequences each STA should use, and one or more of the transmission output requirements that the STA follows in transmitting the response 42. Using the latter, it is possible to surely and correctly distinguish between the channel effect and the transmission effect. In response to the request, particularly within the Short Interframe Space (SIFS) of the trigger frame, the response 42 is transmitted by all STAs addressed to the trigger frame using the parameters requested by AP1, particularly by transmitting a response data unit. Different from the response 24, the response 42 may generally consist of a PHY preamble, synchronization and estimation sequences including legacy synchronization, estimation and signaling and specific signaling of the standard. Thereby, the latter synchronization and estimation sequences are transmitted in an orthogonal manner. In the case of the method shown in FIG. 4, since AP1 directly estimates the channels from STAs STA1 to N from the estimation sequences, it is not necessary to include a data frame in the trigger-based PPDU 42 for estimation (however, it may be included for purposes other than those described in this specification). In contrast, in the methods of FIGS. 2 and 3, STAs STA1 to STA_N estimate the channels and feedback the estimation results to the access point. Therefore, the response 24 includes channel feedback information in the data field. Then, a training data unit 43 is transmitted. This training data unit 43 is the same as or identical to the content of the training data unit 25 described above with reference to FIG. 2. After this, the same steps as those described above with reference to FIGS. 2 and 3 with reference to elements 26 to 28 follow.

[0041] Referring to FIGS. 2 to 4, in the above-described embodiment, although AP1 needs to transmit a specific PPDU (training data unit) after sounding processing, this processing implies that it has little or no value for the stations within its BSS, that is, the stations associated with AP1. FIG. 5 is a schematic diagram showing another embodiment of the method according to the present disclosure. In this embodiment, such overhead is avoided, and the training data unit is not transmitted after sounding processing, but is transmitted during normal data transmission.

[0042] In this embodiment, the oAP acquires channel information from a multi-user (MU) PPDU (training data unit 53) transmitted by AP1 during normal data transmission 50. FIG. 5 particularly shows the processing necessary to collect CSI and measurement reports. On the other hand, FIG. 6 shows the operation with the beamforming weighting matrix obtained together with the newly collected CSI.

[0043] As shown in Fig. 5, after the sounding phase (not shown in Fig. 5) and during the transmit phase 50 (also referred to as Transmit Opportunity TXOP1), AP1 attempts MU-DL transmission by transmitting a MU-RTS (Ready To Send) trigger frame 51 to the stations belonging to the MU group provided with the communication service. After receiving the MU-RTS frame 51 respectively, within the same predetermined time period, they respond with a CTS (Clear To Send) frame 52. In the case of STA1 to STA_N, this is a normal MU-DL operation. On the other hand, the oSTA can estimate the interference and / or channel for each resource unit allocation and MU session configuration based on the Q E-STF and Q E-LTF in the MU-PPDU 53. The stations STA1 to STA_N respond with a response 54. The preamble part of the response 54 is the same or similar to the response 24 or 42. These packets only differ in functionality (the former carries the acknowledgement response information for the data unit transmitted from the AP, while the latter contains the channel feedback information). However, for the purposes described in this specification, generally only the preamble information is used by the oSTA and oAP, so the content of the data in the responses 54, 24, and 42 is not important.

[0044] Under the current standard operation, the MU-PPDU is currently targeted at a specific STA indicated in the preamble by an allocation identifier. On the other hand, an oSTA that is not the intended receiver usually discards the packet. Therefore, in order to enable the above-described operation, it is proposed to redefine the MU-RTS trigger 51 to indicate the start of MU-MIMO transmission suitable for spatial reuse for the oSTA. Based on the indication in the MU-RTS frame 51 and the indication from the oAP, the oSTA measures the CSI required by their corresponding oAP. After Transmit Opportunity TXOP1 indicating the MU operation, the oAPs compete for the channel with each other. The winning oAP among them transmits the trigger frame 26 to the corresponding oSTA associated with the oAP in the resource unit for which a measurement report is requested.

[0045] Thus, according to the embodiment shown in FIG. 5, the oSTA starts measuring the channel on the preamble of the subsequent MU frame based on the MU-RTS trigger frame 51. The display of the session index (indicating one or more of the beamforming configuration used by AP1, the function of the beamforming configuration, the identifier of the intended first station, and / or the resource unit allocation. In one embodiment, it indicates the group ID and the beamforming configuration) is useful for indicating to the oSTA whether measurement values for a specific session and configuration are being requested.

[0046] In the case of the trigger-based PPDU (training data unit 53), the oAP estimates or updates the channel of each resource unit. If the previous channel estimate value of the resource unit is available, the calculated channel is averaged using this available information based on the previous training phase. It is necessary to indicate the transmission output (TxPower) of each STA to enable the distinction between the channel effect and the transmission effect. This can be easily included in the preamble of the training data unit 53. The Transmit Opportunity TxOP2 following the Transmit Opportunity TxOP1 includes steps 26 to 28 shown in FIGS. 2 to 4.

[0047] The opportunistic beamforming operation (shown as Transmit Opportunity TxOP3) based on the newly calculated null beamforming weight matrix is schematically shown in FIG. 6. The MU operation between AP1 and STAs 1 to N follows normal processing. That is, the MU operation between AP1 and STAs 1 to N starts from the RTS trigger frame 60 from AP1 that requests a station addressed to respond with a trigger-based CTS 61. The oAP that obtained channel access within Transmit Opportunity TxOP2 (shown in FIG. 5) to collect measurement reports and calculate the beamforming matrix using nulling constraints also responds to the RTS frame. From the perspective of oAP1, this is the CTS 62 for itself intended to inform the STA and oSTA of the medium reservation. The operation described in FIG. 6 is the same regardless of how the training was performed, i.e., whether it was by explicit training shown in FIGS. 2 and 3, implicit training shown in FIG. 4, or training embedded in the Transmission Opportunity of the MU of AP1 shown in FIG. 5.

[0048] The response 64 to the spatial reuse PPDU by beamforming, i.e., the physical protocol data unit 63 (PPDU) for normal data transmission, is transmitted so that the preamble part is beamformed using a beamforming matrix and no interference occurs to STA1~STA_N due to the transmission of the PPDU 63. The beamforming weighting matrix QN1 can be the same matrix as that used during normal transmission or a coarser matrix. Here, "coarser" means that it is optionally designed by smoothing some frequencies so as to cover the entire channel where the actual resource units of transmission between the oAP and the oSTA are selected. Finally, the stations STA1~STA_N transmit an acknowledgment response 65 to the AP1. The acknowledgment response 65 indicates that the MAC data unit has been correctly received from the AP1 or that retransmission is necessary. The acknowledgment response from the oSTA to the oAP will be transmitted as a station ACK (not shown in FIG. 6) within a different time unit period.

[0049] The beamforming session index can be included in the RTS trigger. This enables the second access point to determine whether it has the latest communication parameters for a specific beamforming scenario, i.e., whether it is possible to provide communication services to the oSTA without causing interference.

[0050] FIG. 7 is a diagram showing a flowchart of an embodiment of the operation of the second access point oAP1. In a first step S10, oAP1 performs channel estimation of the channel from the STA. The estimation is performed based on the UL transmission of the STA, and more specifically, based on the response frames 24, 42 (see FIGS. 2 to 4). In a second step S11, oAP1 calculates resource unit allocation for the STA based on the SIG field of the training data unit transmitted after the training phase. Subsequently, in step S12, oAP1 calculates a set of resource units that may be available from i) a set of allocated resource units for which channel estimation values are obtained, ii) a set of allocated resource units for which channel estimation values are estimated, and iii) a set of unallocated resource units. For the resource units of set i), beamforming using interference constraints is preferably used. For the resource units of set ii), robust null forming for the STA is preferably employed. On the other hand, for the resource units of iii), these can be used without necessarily using beamforming. Robust null forming refers to a beamforming design in which the interference cancellation condition is satisfied even when there are errors within a certain range. In a fourth step S13, a trigger frame including a measurement report request is transmitted. In a fifth step S14, a null beamforming weight, that is, a beamforming weight that satisfies the interference constraint at the station, is calculated based on the measurement report received from the associated station and the channel estimation value.

[0051] Therefore, oAP1 determines whether spatial reuse is permitted, calculates a beamforming weight vector so as not to cause interference, and the second access point can transmit data to the second station during the Transmission Opportunity of the first access point for which spatial reuse is determined to be permitted. Therefore, oAP1 can form nulls. The session index indicates the beamforming configuration calculated by AP1 and is used in data transmission. oAP1 requests a measurement report from oSTA for that specific beamforming configuration indicated by the session index using the session index. oAP1 further determines whether the beamforming configuration is one for which null beamforming weights have been calculated using the session index transmitted included in the PPDU during data transmission. Based on the session index, oAP1 can determine whether it is possible to spatially reuse the Transmission Opportunity of the data of AP1 characterized by the indicated beamforming configuration.

[0052] FIG. 8 is a schematic diagram of the state transition of the second station oSTA. If oSTA has received an indication from oAP in an exchange of previous messages including, for example, the schedule of the expected sounding time and information regarding the channel or session index for which interference is to be measured (step S20), oSTA will wait to receive a training data unit during the indicated period including a certain time tolerance. oSTA waits to receive a legacy preamble and, if received correctly, proceeds to decode the U+E SIG (step S21).

[0053] If the SIG information can be correctly decoded, the session index, format, and the number of LTFs are calculated, and further, channel estimation for each frequency / sub-carrier is advanced (step S22). If a training data unit is expected, the legacy preamble is decoded, but the U+E SIG is not decoded. Then, only output measurement at the preamble is performed (step S23).

[0054] If the training schedule is not received or defined, after the preamble of the training data unit is detected, the oSTA decodes the U+E SIG field (step S24) relying only on the information in the U+E SIG field, determines whether the received packet is a training data unit, and calculates the session index (step S25). The oAP further proceeds to measure the channel on the LTF sequence after beamforming (step S26). If the U+E SIG cannot be decoded, the training data unit is discarded (step S27).

[0055] The measurement report prepared in step S28 or S29 and transmitted from the oAPo to the STA in response to the trigger frame 26 should include, for the indicated resource unit, preferably, a series of channel norms and channel phases in a compressed form, or the measured signal output. If no measurement is performed in the resource unit, a default value will be indicated.

[0056] The request for the measurement report transmitted by oAP with the trigger frame 26 shall include information regarding a resource unit identified by oAP as sharable (i.e., a resource unit that oAP can control such that the interference to the STA is below the necessary limit), and the type of measurement, e.g., signal strength or channel norm, and phase feedback for a specific resource unit. Before this request, information including the timestamp of the next sounding round that is the target, transmitted by oAP, together with the corresponding session index, is placed. This information can be obtained by oAP from the control information broadcast by AP1 and will be embedded in the frame transmitted to oSTA at a stage prior to the flow presented in this disclosure.

[0057] FIG. 9 is a diagram showing a flowchart of an embodiment of the operation of the first access point AP1. In a first step S30, AP1 executes sounding processing using one or more first stations, and calculates resource unit allocation and beamforming configuration to be used for subsequent communication with each first station. In a second step S31, a training data unit including signaling information regarding the calculated resource unit allocation and the calculated beamforming configuration is transmitted. Here, the training data unit is transmitted together with a beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration. Therefore, the training data unit can be transmitted together with the calculated beamforming configuration, or a beamforming configuration calculated based on the calculated beamforming configuration (and / or the calculated resource unit allocation). More precisely, the latter refers to the extension of the beamforming weight to the frequency subcarriers corresponding to the entire channel or frequency block to which a specific resource unit belongs, or the smoothing of the frequency or the application of the beamforming weight corresponding to the calculated configuration adapted to the statistical channel knowledge. The advantage of the latter is that it shows an acceptable indication of the interference level that oSTA will receive from AP1 and has a slow time change. In a third step S32, a physical protocol data unit is transmitted to one or more first stations. The physical protocol data unit includes a session index, a training sequence, and data transmitted to each first station.

[0058] FIG. 10 is a diagram showing an example of a training data unit for null formation training. The necessary control signaling to be included in the U + E SIG field is bandwidth and channel, resource allocation, session index (identifying the MU and BF configuration so that the measured values are averaged or updated whenever the configuration is used), and the number and format of LTFs.

[0059] Note that the session index applies to all sounding processes disclosed in this specification and is a combination of possible information regarding the resource unit allocation user ID and the updated beamforming. Any other oSTA or oAP may perform any operation based on this.

[0060] Signaling of the session index is difficult. This is because if the AP is operating for a long time and the resource unit allocation and beamforming configuration are frequently changed, the session index may be insufficient when these session numbers are limited. Therefore, one embodiment of the forgetting mechanism can be applied as described below.

[0061] Assuming that the session index set contains N indices (0 to N-1), the standard or AP1 can define a window length W<N-1 that indicates the current, that is, the window of consecutive indices considered to be in use. Any oAP observes the session index transmitted in the PPDU by AP1. The arbitrary oAP maintains a set S that holds W consecutive session indices. When the oAP observes a session index T that is not part of the current set, the oAP sets a new set given by the following formula.

[0062]

Equation

[0063]

Equation

[0064] Initially, the set S is undefined. That is, the oAP waits for the first session index by AP1 and sets the set according to the above formula. For each element of the set, the oAP records which stations can receive the communication service and are trained according to the above-described process. Any session index that has fallen out of the current set S is determined to be untrained, and while AP1 is performing transmission, the oSTA requires training or retraining according to the above-described process before the communication service is simultaneously provided by the oAP.

[0065] The present embodiment is illustrated by two examples: When N = 8, W = 4, and T = 5, the result is S = [2…5]. When N = 8, W = 4, and T = 2, the result is S = [0…2,7].

[0066] The present disclosure realizes beamforming spatial reuse with minimal cooperation between access points. One master AP adjusts the method and does not need to collect information about stations from other BSSs that require null formation. For example, to make the disclosed solution backward compatible, it can be designed to involve EHT stations using some versions of cooperative beamforming (by signaling and channel acquisition methods) in the spatial reuse method, bringing the advantage that a natural association with the spatial reuse and sounding concepts is realized.

[0067] Therefore, the above discussion discloses and describes merely exemplary embodiments of the present disclosure. As will be understood by those skilled in the art, the present disclosure may be embodied in other specific forms without departing from its intended or essential characteristics. Therefore, the disclosure of the present disclosure is to be regarded as illustrative rather than limiting the scope of the present disclosure and other claims. To ensure that the subject matter of the invention does not become generic, the present disclosure defines, in part, the terms of the scope of the above patent claims, including any readily distinguishable variations of the teachings herein.

[0068] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may perform the functions of several items recited in the claims. The mere fact that several means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used advantageously.

[0069] Although embodiments of the present disclosure have been described as being implemented at least in part by a software-controlled data processing apparatus, it will be understood that non-transitory machine-readable media carrying such software, such as, for example, optical disks, magnetic disks, semiconductor memories, etc., also represent an embodiment of the present disclosure. Further, such software may be distributed in other forms, such as via the Internet or other wired or wireless communication systems.

[0070] The elements of the disclosed devices, apparatuses, and systems can be implemented by corresponding hardware and / or software elements, such as by respective appropriate circuits or circuit portions. A circuit is a structural assembly of electronic components including conventional circuit elements, application specific integrated circuits, integrated circuits including standard integrated circuits, application specific standard products, and field programmable gate arrays. Further, a circuit includes a central processing unit, a graphics processing unit, and a microprocessor programmed or configured according to software code. A circuit does not include pure software, but includes the above-described hardware-executed software. A circuit or circuit portion can be implemented by a single device or unit or a plurality of devices or units, or a chip set(s), or a processor(s).

[0071] A list of further embodiments of the disclosed subject matter is as follows. (1) A first access point, Execute sounding processing using one or more first stations associated with the first access point and configured to communicate with the first access point via respective channels, calculate resource unit allocation and beamforming configuration used for subsequent communication with each first station, Transmit a training data unit including signaling information related to the calculated resource unit allocation and the calculated beamforming configuration, the training data unit being transmitted together with a beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration Configured as circuit Comprising The first access point. (2) The first access point according to any one of the preceding embodiments, The signaling information includes an identifier indicating that the destination of the training data unit is one or more second access points and / or second stations that are associated with a second access point and not associated with the first access point, or a broadcast group The first access point. (3) The first access point according to any one of the preceding embodiments, The signaling information includes information regarding one or more of resource unit allocation, beamforming configuration, channel estimation sequence number, type of channel estimation sequence, display of training packets, and indication of whether spatial reuse is permitted during data transmission based on the beamforming or session index parameter indicated by the signaling information The first access point. (4) The first access point according to any one of the preceding embodiments, The training data unit includes a beamforming configuration, an identifier of a desired first station, the resource unit allocation used by the first access point, and a session index indicating one or more of one or more transmission parameters. A first access point. (5) The first access point according to any one of the preceding embodiments, The training data unit includes a MAC frame that transmits information regarding one or more MIMO configurations and resource unit allocations for one or more sets of first stations that are associated with the first access point and configured to communicate with the first access point via respective channels. A first access point. (6) The first access point according to any one of the preceding embodiments, The circuit transmits a Null Data Packet Announcement (NDPA), transmits one or more Null Data Packets (NDPs), requests feedback from one or more first stations regarding each resource unit, and by receiving feedback data units transmitted by the one or more first stations is configured to perform the downlink sounding process. A first access point. (7) The first access point according to Embodiment 6, The circuit is configured to use the respective resource units to transmit the requested feedback, and to receive the feedback data unit transmitted by the one or more first stations using the channel bandwidth indicated in the null data packet announcement to transmit an estimated sequence. The first access point. (8) The first access point according to Embodiment 6 or 7, In the null data packet announcement, the circuit is configured to indicate one or more of the start of a sounding period suitable for spatial reuse for transmission, the bandwidth information used for subsequent sounding, and the transmission of the training data unit. The first access point. (9) The first access point according to Embodiment 6, 7 or 8, The circuit is configured to transmit the training data unit during a time period after receiving the feedback data unit, or within the period of the downlink sounding process, or in the last section of the period of the downlink sounding process. The first access point. (10) The first access point according to any one of the preceding embodiments, The circuit is a trigger for requesting a response from one or more first stations, the trigger including one or more of information regarding resource allocation for each of the first stations, the number of training sequences, the number of streams per resource unit, an identifier indicating which orthogonal sequences are used by each of the first stations, the transmission output requirement for each of the first stations, and information as to whether spatial reuse is permitted for future transmissions, and receiving a response data unit transmitted by the one or more first stations based on the parameters included in the trigger. by which configured to execute the downlink sounding process a first access point. (11) A first access point according to any one of the preceding embodiments, wherein the circuit is configured to transmit the training data unit including signaling information as part of data communication with one or more first stations a first access point. (12) A first access point according to any one of the preceding embodiments, wherein the circuit after executing the downlink sounding process, transmits an RTS (Ready To Send) trigger indicating the start of MIMO transmission suitable for spatial reuse, which is an RTS (Ready To Send) trigger, to one or more first stations, and receives a CTS (Clear To Send) response from one or more first stations to which the RTS trigger has been transmitted and is configured to a first access point. (13) A first access point according to Embodiment 12, wherein the RTS trigger includes a session index indicating the one or more first stations receiving a communication service in a subsequent PPDU a first access point. (14) A first access point according to Embodiment 4, wherein the circuit is configured to transmit, to the one or more first stations after executing the downlink sounding process, a physical protocol data unit including a session index, a training sequence, and data to be transmitted to each of the respective first stations a first access point. (15) A first access point according to any one of the preceding embodiments, The training data unit includes a synchronization and / or estimation sequence First access point. (16) A first access point according to any one of the preceding embodiments, The circuit is configured to transmit the training data unit including signaling information as part of data communication with one or more first stations First access point. (17) A first access point according to any one of the preceding embodiments, The beamforming session index is included in the RTS trigger First access point. (18) A first access point according to any one of the preceding embodiments, The training data includes the information regarding the beamforming configuration within a universal signaling field or a signaling field independent of the standard version First access point. (19) A first access point according to any one of the preceding embodiments, The circuit is configured to predict the channel of neighboring resource units for the estimated resource unit and form a beamforming vector that nulls the interference within the resource unit with a stricter tolerance than the estimated resource unit First access point. (20) A second access point, A response data unit transmitted by one or more first stations configured to be associated with the first access point and communicate with the first access point via respective channels, the response data unit being listened for by the first access point from the one or more first stations in a sounding process performed by the one or more first stations Estimate each of the channels using the received response data unit, Listen to a training data unit transmitted by the first access point, the training data unit including signaling information related to a resource unit allocation and a beamforming configuration calculated by the first access point for subsequent communication with each first station, and transmitted together with a beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration, Calculate a resource unit allocation and a beamforming configuration for subsequent communication with one or more second stations associated with the second access point based on the signaling information included in the received training data unit, configured to be circuit comprising a second access point. (21) The second access point according to Embodiment 20, wherein the circuit determines whether spatial reuse is permitted, calculates a beamforming weight vector so as not to cause interference, and transmits data to the second station during the Transmission Opportunity of the first access point when it is determined that spatial reuse is permitted for the second access point, configured to be a second access point. (22) The second access point according to Embodiments 20 to 21, wherein the circuit is configured to estimate each of the channels using the estimation and signaling information included in the received response data unit, a second access point. (23) The second access point according to Embodiments 20 to 22, wherein the circuit Request feedback from one or more second stations regarding resource units and / or interference levels, and / or request channel feedback information regarding one or more resource units, Receive a feedback data unit transmitted by the one or more second stations, the feedback data unit including the requested feedback and is further configured to a second access point. (24) A second access point according to Embodiment 23, The circuit is configured to request feedback by transmitting a trigger including information regarding one or more of the resource units that may be available for subsequent communication, the resource units for which feedback is requested, and the format of the requested feedback a second access point. (25) A second access point according to Embodiments 20 to 24, The circuit is a confirmation response used for subsequent communication with the second access point, and the circuit is configured to transmit the confirmation response indicating one or more of the session index, the second station for which use of the spatial reuse resource is permitted, the resource allocation, the beamforming configuration, and the confirmation response behavior to the one or more second stations a second access point. (26) A second access point according to Embodiments 20 to 25, The circuit is Listening for a RTS (Ready To Send) trigger transmitted by the first access point to one or more first stations, wherein the RTS trigger indicates the start of MIMO transmission suitable for a shared resource, and preferably, the session index indicates a beamforming configuration used by the first access point or a function of the beamforming configuration, listening for the RTS (Ready To Send) trigger, Estimating the channel from the one or more first stations during uplink transmission to the first access point, or responding with a Clear To Send (CTS) before data transmission to one or more second stations STA configured as A second access point. (27) The circuit is configured to communicate with one or more second stations using respective beamforming configurations that do not cause interference to the one or more first stations for which the resource unit allocation and beamforming configuration have been calculated A second access point. (28) A second access point according to any one of Embodiments 20 to 27, The circuit is further configured to request measurements in the frame exchange that occurs before the sounding process A second access point. (29) A second access point according to Embodiment 28, The circuit is further configured to request measurements and prepare reports, in particular, by transmitting a frame indicating that the set of second stations has been requested to listen for sounding from a set of first access points using specific sounding information, in particular, sounding from a set of first access points and / or sounding within a certain time period and / or sounding from a first access point using a known beamforming session index A second access point. (30) A second station, A training data unit transmitted by a first access point to which one or more first stations are associated for communicating with the first access point via respective channels, the training data unit including signaling information related to resource unit allocation and beamforming configuration calculated by the first access point for subsequent communication with each of the first stations, listening to the training data transmitted together with the beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration, estimating channel and / or interference information based on the received training data unit, transmitting the estimated channel and / or interference information to a second access point to which the second station is associated for communicating via the channel configured to circuit comprising A second station. (31) The second station according to Embodiment 30, wherein the circuit monitors a channel for a training data unit transmitted with an indication that sounding is for transmission suitable for future spatial reuse, and is further configured to report the estimated channel and interference information for a session index requested by the second access point or for a session index with interference below a predetermined threshold, the session index indicating a beamforming configuration used by the first access point or a function of the beamforming configuration A second station. (32) The second station according to Embodiments 30 to 31, The circuit is further configured to calculate beamforming related information used to estimate the channel or interference information based on the signaling information included in the received training data unit. Second station. (33) A second station according to Embodiments 30 to 32, The circuit is further configured to transmit a feedback data unit including feedback regarding each resource unit and / or interference level and / or channel feedback information regarding one or more resource units as the estimated channel and / or interference information. Second station. (34) A second station according to Embodiment 33, The circuit is configured to transmit the feedback data unit together with an orthogonal training sequence over a bandwidth greater than the bandwidth over which a subsequent data portion is transmitted. Second station. (35) A second station according to Embodiments 30 to 34, The circuit is In particular, listen to the sounding period of an access point different from the associated one based on a request from a second access point or based on training suitable for spatial reuse, In particular, estimate channel or interference information based on the training data unit, Monitor the channel for the packet transmitted with a display suitable for spatial reuse, Report the channel and interference level for the requested beamforming session index or for a beamforming session index where interference is below a predetermined threshold. and is further configured as Second station. (36) A second station according to Embodiments 30 to 35, The circuit is further configured to calculate beamforming related information, in particular, the number of estimation sequences for stream mapping and / or the type of antenna, based on the SIG field of the training data unit so as to enable correct estimation of the channel and / or interference level. Second station. (37) A second station according to Embodiments 30 to 36, The circuit is further configured to transmit a PPDU using orthogonal training sequences over a bandwidth larger than the bandwidth for transmitting the subsequent data portion. Second station. (38) A method used by a first access point, performing sounding processing using one or more first stations configured to communicate with the first access point via respective channels and associated with the first access point, calculating resource unit allocation and beamforming configuration for subsequent communication with each first station, transmitting a training data unit including signaling information related to the calculated resource unit allocation and the calculated beamforming configuration, the training data unit being transmitted together with a beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration. A method used by a first access point. (39) A method used by a second access point, listening for a response data unit transmitted by one or more first stations configured to communicate with the first access point via respective channels and associated with the first access point, the response data unit being transmitted by the one or more first stations in the sounding processing performed by the first access point using the one or more first stations, Estimate each of the channels using the received response data unit, Listen to a training data unit transmitted by the first access point, which includes signaling information related to a resource unit allocation and a beamforming configuration calculated by the first access point for subsequent communication with each first station, and is transmitted together with a beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration, Based on the signaling information included in the received training data unit, calculate a resource unit allocation and a beamforming configuration for subsequent communication with one or more second stations associated with the second access point, A method used by a second access point. (40) A method used by a second station, Listen to training data transmitted by a first access point to which one or more first stations are associated for communicating with the first access point via respective channels, the training data including signaling information related to a resource unit allocation and a beamforming configuration calculated by the first access point for subsequent communication with each first station, and being transmitted together with a beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration, Estimate channel and / or interference information based on the received training data unit, Transmit the estimated channel and / or interference information to a second access point to which the second station is associated for communicating via the channel, A method used by a second station. A non-transitory computer-readable recording medium storing a computer program product which, when executed by a processor, causes the method according to Embodiment 38, 39 or 40 to be executed. A computer program having program code means which, when executed on a computer, causes the computer to execute the steps of the method according to Embodiment 38, 39 or 40.

Claims

1. A first access point, executing sounding processing using one or more first stations associated with the first access point and configured to communicate with the first access point via respective channels, and calculating resource unit allocation and beamforming configuration for subsequent communication with each first station, transmitting a training data unit including signaling information related to the calculated resource unit allocation and the calculated beamforming configuration, the training data unit being transmitted together with a beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration configured to comprise a circuit, wherein the signaling information includes an identifier indicating that the transmission destination of the training data unit is one or more second access points and / or second stations associated with a second access point and not associated with the first access point, or a broadcast group, or the signaling information includes information regarding one or more of resource unit allocation, beamforming configuration, channel estimation sequence number, type of channel estimation sequence, indication of training packet, and indication of whether spatial reuse is permitted during data transmission according to the beamforming or session index parameter indicated in the signaling information the first access point.

2. The first access point according to claim 1, wherein the training data unit includes a beamforming configuration, an identifier of a desired first station, the resource unit allocation used by the first access point, and a session index indicating one or more of one or more transmission parameters, and / or the training data unit includes a MAC frame transmitting information regarding one or more MIMO configurations and resource unit allocations for one or more sets of first stations associated with the first access point and configured to communicate with the first access point via respective channels the first access point.

3. The first access point according to claim 1, wherein the circuit transmits a Null Data Packet Announcement (NDPA), transmits one or more Null Data Packets (NDPs), requests feedback from one or more first stations regarding each resource unit, and by receiving feedback data units transmitted by the one or more first stations is configured to perform downlink sounding processing the first access point.

4. The first access point according to claim 1, wherein the circuit is a trigger that requests a response from one or more first stations, and transmits a trigger including one or more of information regarding resource allocation for each of the first stations, the number of training sequences, the number of streams per resource unit, an identifier as to which orthogonal sequence is used by each of the first stations, the transmission output requirement for each of the first stations, and information as to whether spatial reuse is permitted for future transmissions, receives response data units transmitted by the one or more first stations based on the parameters included in the trigger whereby is configured to perform the downlink sounding processing the first access point.

5. A second access point, which is a response data unit transmitted by one or more first stations that are associated with the first access point and configured to communicate with the first access point via respective channels, listens to the response data unit transmitted by the one or more first stations in the sounding processing performed by the first access point using the one or more first stations, estimates the respective channels using the received response data unit A training data unit transmitted by the first access point, including signaling information related to a resource unit allocation and a beamforming configuration calculated by the first access point for subsequent communication with each first station, listening to the training data unit transmitted together with a beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration, Based on the signaling information included in the received training data unit, calculating a resource unit allocation and a beamforming configuration for subsequent communication with one or more second stations associated with the second access point configured as circuit comprising a second access point.

6. The second access point according to claim 5, wherein the circuit is determining whether spatial reuse is permitted, calculating a beamforming weight vector so as not to cause interference, transmitting data to the second station during the Transmission Opportunity of the first access point when it is determined that spatial reuse is permitted for the second access point configured as a second access point.

7. The second access point according to claim 5, wherein the circuit is In particular, by transmitting a trigger including information regarding one or more of a resource unit that may be used for subsequent communication, a resource unit for which feedback is requested, and the form of the requested feedback, requesting feedback from one or more second stations regarding the resource unit and / or the interference level, and / or requesting channel feedback information regarding one or more resource units, receiving a feedback data unit transmitted by the one or more second stations, the feedback data unit including the requested feedback further configured to a second access point.

8. The second access point according to claim 5, wherein The circuit is configured to communicate with one or more second stations using respective beamforming configurations that do not cause interference to the one or more first stations for which the resource unit allocation and beamforming configuration have been calculated. A second access point. **Claim 9** A second access point, A response data unit transmitted by one or more first stations associated with a first access point and configured to communicate with the first access point via respective channels, listening to the response data unit transmitted by the one or more first stations in the sounding process executed by the first access point using the one or more first stations, Estimating the respective channels using the received response data unit, A training data unit transmitted by the first access point, including signaling information related to the resource unit allocation and beamforming configuration calculated by the first access point for subsequent communication with each first station, listening to the training data unit transmitted together with the beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration, Based on the signaling information included in the received training data unit, calculating a resource unit allocation and a beamforming configuration for subsequent communication with one or more second stations associated with the second access point configured to comprising a circuit, The circuit is such that the resource unit allocation and the beamforming configuration are calculated without causing interference to the one or more first stations configured to communicate with one or more second stations using respective beamforming configurations A second access point. **Claim 10** A method used by a second access point, A response data unit transmitted by one or more first stations associated with a first access point and configured to communicate with the first access point via respective channels, listening for the response data unit transmitted by the one or more first stations in a sounding process executed by the first access point using the one or more first stations, estimating the respective channels using the received response data unit, A training data unit transmitted by the first access point, including signaling information related to a resource unit allocation and a beamforming configuration calculated by the first access point for subsequent communication with each first station, listening for the training data unit transmitted together with the beamforming configuration derived from the calculated resource unit allocation and the calculated beamforming configuration, calculating a resource unit allocation and a beamforming configuration for subsequent communication with one or more second stations associated with a second access point based on the signaling information included in the received training data unit, A method used by a second access point.

11. A non-transitory computer-readable recording medium storing a computer program product that, when executed by a processor, causes the method according to claim 10 to be executed.

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