Access point, station and corresponding methods

Abstract

The first access point includes circuitry configured to perform a sounding procedure with respect to one or more first stations associated with the first access point and configured to communicate with the first access point over respective channels to determine resource unit allocations and beamforming configurations for use in subsequent communications with the respective first stations; and transmit a training data unit containing signaling information related to the determined resource unit allocations and related to the determined beamforming configurations, wherein the training data unit is transmitted with a beamforming configuration derived from the determined resource unit allocations and the determined beamforming configurations.

Description

TECHNICAL FIELD

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

[0002] Low latency or real-time applications have stringent requirements on fast or periodic channel access. For example, in a WLAN Basic Service Set (BSS; also referred to as cell in the following) one or more stations (STAs) are associated with an access point (AP) serving the one or more STAs, these requirements are relatively easy to fulfill.

[0003] However, this is not the case when a STA is located in the range of multiple overlapping BSSs (OBSSs) managed by different APs and one or more other STAs are associated with respective other BSSs. One or more other STAs (also referred to as overlapping STAs (oSTAs)) associated with another AP serving another BSS are also in the range of the AP serving the one or more STAs.

[0004] Spatial reuse (SR) techniques are defined in the upcoming 802.1 lax amendment of the IEEE 802.11 standard. This enables oSTAs from overlapping BSSs to transmit in time intervals scheduled by the AP as long as the interference at the AP can be guaranteed to be below a tolerable level.

[0005] The purpose of the background description provided herein is to generally present the context of the disclosure. The work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that can not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. SUMMARY

[0006] It is an object to provide an access point capable of enhancing downlink spatial reuse. It is a further object to provide a corresponding method for implementing the method as well as a corresponding computer program and a non-transitory computer-readable recording medium.

[0007] According to one aspect, a first access point is provided, comprising circuitry configured to:

[0008] - perform a sounding procedure with one or more first stations associated with the first access point and configured to communicate with the first access point over a respective channel, to determine a resource unit allocation and a beamforming configuration for use in subsequent communication with the respective first stations; and

[0009] - transmitting a training data unit containing signaling information related to the determined resource unit allocation and signaling information related to the determined beamforming configuration, wherein the training data unit is transmitted using a beamforming configuration derived from the determined resource unit allocation and the determined beamforming configuration.

[0010] According to another aspect, there is provided a second access point comprising circuitry configured to:

[0011] - listen for response data units transmitted by one or more first stations, the one or more first stations being associated with the first access point and being configured to communicate with the first access point over respective channels, the response data units being transmitted by the one or more first stations in a sounding procedure performed by the first access point with respect to the one or more first stations;

[0012] - estimate the respective channels using the received response data units;

[0013] - listen for a training data unit transmitted by the first access point, the training data unit containing signaling information related to a resource unit allocation and a beamforming configuration determined by the first access point for use in subsequent communication with respective first stations, wherein the training data unit is transmitted using a beamforming configuration derived from the determined resource unit allocation and the determined beamforming configuration;

[0014] - determine, based on the signaling information contained in the received training data unit, a resource unit allocation and a beamforming configuration for use in subsequent communication with one or more second stations, the one or more second stations being associated with the second access point.

[0015] According to another aspect, there is provided a second station comprising circuitry configured to:

[0016] - listen for a training data unit transmitted by a first access point, the first access point being associated with one or more first stations to communicate with the first access point over respective channels, the training data unit containing signaling information related to a resource unit allocation and a beamforming configuration determined by the first access point for use in subsequent communication with respective first stations, wherein the training data unit is transmitted using a beamforming configuration derived from the determined resource unit allocation and the determined beamforming configuration;

[0017] - estimate channel and / or interference information based on the received training data unit;

[0018] - transmit the estimated channel and / or interference information to a second access point, the second access point to be associated with the second station to communicate over the channels.

[0019] According to further aspects respective methods, there is provided a computer program comprising program means for causing a computer to carry out the steps of the methods disclosed herein when said computer program is carried out on a computer; and a non-transitory computer-readable recording medium storing the computer program product which, when executed by a processor, causes the execution of the methods disclosed herein.

[0020] Embodiments are defined in dependent claims. It is to be understood that the disclosed station, the disclosed method, the disclosed computer program and the disclosed computer-readable recording medium have similar and / or identical further embodiments as the claimed access point and as disclosed herein, as dependent claims and / or as disclosed herein.

[0021] One aspect of the invention is to enable beamforming based spatial reuse with minimal coordination between access points. This is particularly applicable to the case where an access point cannot or does not want to perform interference cancellation, but can help other access points to obtain the information needed for beamforming based spatial reuse. The method comprises introducing a new training data unit on the basis of which a cascaded sounding protocol can be designed. Furthermore, appropriate control message flows and examples suitable for 802.11 multi-AP scenarios are provided.

[0022] The above summary is provided as a general overview of the subject matter of the application and is not intended to be limiting with respect to the scope of the claims. The described embodiments and further advantages can be better understood with reference to the following detailed description together with the appended drawings, in which: BRIEF DESCRIPTION OF DRAWINGS

[0023] The present invention, together with further advantages, can best be understood by reference to the following detailed description taken in connection with the accompanying drawings, in which:

[0024] Figure 1 A diagram showing an exemplary embodiment of a communication system according to the invention is shown.

[0025] Figure 2 A diagram illustrating one embodiment of a method using explicit sounding according to the invention is shown.

[0026] Figure 3 A diagram illustrating another embodiment of a method using explicit sounding according to the invention is shown.

[0027] Figure 4 A diagram illustrating one embodiment of a method using implicit sounding according to the invention is shown.

[0028] Figure 5 A diagram illustrating an embodiment of a method according to the invention, which transmits a training data unit during regular data transmission, is shown.

[0029] Figure 6 A diagram illustrating an embodiment of a spatial multiplexing method performed by a second access point to exploit opportunistic beamforming according to the present application is shown.

[0030] Figure 7 A flowchart illustrating an embodiment of a second access point operation is shown.

[0031] Figure 8 A diagram illustrating a state flow of a second station is shown.

[0032] Figure 9 A flowchart illustrating an embodiment of a first access point operation is shown.

[0033] Figure 10 A diagram illustrating an example of a training data unit used for nulling training is shown. DETAILED DESCRIPTION

[0034] It is the object of the present application to enable spatial multiplexing based on opportunistic beamforming in a WLAN scenario where an AP within the oBSS (also referred to as oAP or second AP herein) is aware of the required channel state information and shares resource allocation and further designs suitable beamforming techniques for the stations (also referred to as oSTAs or second stations herein) in its oBSS without coordination of a master device like a master AP. The involvement of the AP (allowing other STAs to access the spectrum of the AP during downlink transmission) is minimal and includes the information required by the sharing oAP to determine spatial multiplexing opportunities but does not require decision making on the shared spectrum.

[0035] Figure 1 A diagram illustrating an exemplary embodiment of a communication system according to the present application is shown. An AP with multiple antennas performs OFDMA transmission to stations STA1 to STA_N (also referred to as first stations herein) in which one or more resource units use a downlink (DL) multi-user (MU) MIMO mode. The DL MU MIMO beamforming scheme employed by AP1 does not consider any interference minimization to STAs outside its BSS. On the other hand, an AP outside the BSS can potentially exploit the spectrum already used by AP1 by appropriate use of beamforming techniques. In Figure 1 In the figure, arrow 10 represents a wanted DL signal using a first resource unit RU1, arrow 11 represents a wanted DL signal using a second resource unit RU2, arrow 12 represents interference using the first resource unit RU1, and arrow 13 represents interference using the second resource unit RU2.

[0036] Therefore, assume that AP1 is selfish, i.e. does not interfere with oSTAs, but applies beamforming only to its own STAs (STA1 to STA_N) and performs the sounding procedure only for its own STAs. Furthermore, assume that oAPi knows the channel of STA1 and has interference cancellation capabilities and that oSTAs are reporting to their associated respective oAP.

[0037] It should be noted that the present application is mainly explained with reference to the general case of MU OFDMA. However, special cases of non-OFDMA or single user (SU) transmission can be treated similarly. For example, this can be achieved by assuming that one RU occupies the whole bandwidth of the channel used for transmission.

[0038] The stations and access points used according to the present application can be implemented using appropriate hardware and / or software. For example, the devices can comprise circuitry configured to perform the respective operations. Circuitry can be understood as a programmed processor or computer, or as a dedicated hardware element, e.g. individual units or parts, made for the performance of certain operations. For example, the disclosed devices can be implemented using processing units (e.g. for performing signal processing), communication units (e.g. for transmitting and / or receiving signals) and control units (e.g. for controlling the processing and / or communication units and / or for controlling the overall operation).

[0039] There are currently two main approaches to enable spatial reuse. One approach considers schemes based on transmission power control, in which different APs advertise their parameters if spatial reuse is acceptable. Based on these schemes, an oAP can reuse spatial resources if it can adjust the transmission parameters according to the interference conditions indicated by the APs. In this case, no coordination on the AP side is required. However, the schemes defined in this document only consider power control and not beamforming assisted spatial reuse.

[0040] Another approach that allows for more advanced beamforming based spatial reuse is to define a coordination scheme in which the APs sharing the resources also coordinate the activities of the oAPs using their resources. However, in order to cancel the interference to STAs outside the BSS, the AP loses the freedom that would otherwise be used to serve its own traffic. Furthermore, participating in cooperative beamforming sounding incurs overhead for the AP and the related STAs. A large part of the overhead is due to the fact that the oSTAs to be cancelled have to be known in advance at the AP and channel state information of these oSTAs should be collected. This overhead can be unreasonable, for example, when the AP is not able or willing to perform beamforming based spatial reuse. However, the fact that one AP does not actively interfere with known oSTAs does not mean that spatial resources cannot be reused by other BSSs that are able to perform more aggressive interference cancellation beamforming.

[0041] The present invention focuses on developing a method that is contrary to the existing methods, which do not take into account coordination from the master AP. The idea of the present invention is as follows. Since AP1 does not participate in the coordinated beamforming scheme according to the scenario assumption, it also has no incentive to spend time resources on coordination training. Therefore, AP1 is performing sounding for STAs belonging to its own BSS without sharing the STA resources within other OBSs. However, AP1 allows oAPs to collect channel state information (CSI), RU allocation, beamforming information, and / or an indication of whether spatial multiplexing is feasible and under what conditions. To this end, AP1 constructs a physical protocol data unit (PPDU) that is transmitted after performing sounding with respect to its own associated STAs, thereby enabling oSTAs to measure the interference experienced by the newly computed beamforming vectors or functions thereof. The PPDU, which is further referred to as a training data unit, is transmitted in order to enable oSTAs and oAPs to train, i.e., to obtain information about the estimate of the channel and spatial multiplexing opportunities from AP1. Based on the specific control information extracted from the data packet transmitted by AP1, and the estimate of the channel from the STAs during the sounding, oAPs determine whether there are resources that can be shared in the spatial or spectral domain. If this is the case, oAPs will request a series of measurements from oSTAs and design beamforming vectors for specific oSTAs that take into account the interference constraints to STAs1 to STA_N. oSTAs and oAPs should be able to continue decoding the training data unit even if it is transmitted by an AP that has no association. To achieve this, the addressing of the training data unit can be either a broadcast address or an identifier of the oSTAs or oBSS, which is based on some previous exchange of information between the AP and the corresponding oAP.

[0042] Figure 2 The figure shows an embodiment of a method according to the present invention using explicit sounding. The embodiment shows in particular the training procedure under the assumption of explicit sounding by AP1.

[0043] The first part 20 of the sounding procedure from AP1 to STAs1 to STA_N is related to AP1 and is, in the present embodiment, a regular DL sounding procedure. The downlink sounding procedure 20 is performed to enable AP1 to determine resource unit allocation and beamforming configuration for use in subsequent communication with the respective stations among STAs1 to STA_N.

[0044] In this embodiment, the downlink sounding procedure 20 comprises a Null Data Packet (NDP) announcement 21 containing information about the required training, i.e. STA involvement, Resource Unit (RU) and Bandwidth (BW) information and the requested feedback type. This is followed by one or more (in particular, a series of) NDP data packets 22, which preferably contain only the PHY layer preamble (synchronization, estimation and control fields) and no data field, since the one or more NDP data packets are intended to allow the STAs to estimate the channel from the API for all the streams to be transmitted. Subsequently, the API requests feedback information (i.e. a response) from the STAs 1 to N, for example by transmitting a Beamforming Report (BFRP) Trigger frame 23, in which the API contains the STAs that should respond and with which RUs are responded.

[0045] From the point of view of the API and the STAs 1 to N, the procedure so far follows the same steps as a regular DL sounding phase. However, based on this exchange of frames (in particular the transmission of the responses 24), the API is able to estimate the channel within the RUs allocated for the responses. In order to have a more accurate estimation at the oAP, one suggestion is to enhance the definition of the responses 24, in particular the TB PPDUs, as follows. The estimation sequence (e.g. the Estimation Short Training Field (E-STF) and the Estimation Long Training Field (E-LTF)) is transmitted in an orthogonal way through all the subcarriers containing the channel of the RU specific to the STA, while the data part is transmitted only through the RU specific to the STA.

[0046] After the sounding procedure 20, the API sends a training data unit 25 to allow the oSTAs to estimate the channel or to measure the interference on the channel, since these channels will experience interference after the new computed beamforming vectors are applied by the API. The training data unit 25 contains signaling information about the determined resource unit allocation and beamforming configuration. In a preferred embodiment, the training data unit 25 can be a NDP-like packet, e.g. a PPDU, without data field. It can include several fields, including the L-P field, the signal field and the training field.

[0047] L-P stands for legacy preamble containing a legacy synchronization followed by a legacy estimation sequence.

[0048] U + E refers to the signaling field, containing control information for describing and decoding the data packet, and including a generic SIG field (U-SIG) representing standard version independent information and a version dependent signaling field (E-SIG) depending on the current standard version used in the communication, for example an Extremely High Throughput (EHT) communication. The use of EHT signaling field is exemplary. The training data unit can also be embedded in a (Very High Throughput) VHT type PPDU, in which case only the version dependent signaling field is present. In the SIG field, information can be contained that is required for the correct decoding of the data packet. In embodiments, the SIG field can contain information on the RU allocation and the spatial stream and beam mapping, which oAP1 can use to determine in which RUs which STAs are to be allocated and whether the available channel estimates and the specific RUs to be used corresponding to a specific STA are accurate.

[0049] The transmit beamforming parameters used, i.e. the identifiers of the STAs for which the beamforming parameters apply, the beamforming configuration and optionally the RU allocation, can be mapped to a session index, which in another embodiment can further be included in the SIG field. The session index indicates the beamforming configuration used by oAP1. From this information, oSTAs can determine whether measures need to be taken, for example performing an update or reporting measurements. From the session index, oAPs can request measurement reports to determine whether oAPs have accurate channel information. From the session index and the corresponding set of channel measurements, oAPs can decide whether a specific session can / is allowed to spatially multiplex and announce spatial multiplexing opportunities to oSTAs that can participate in the session.

[0050] E-STF and E-LTF are synchronization and estimation sequences, respectively, which can be transmitted in VHT or EHT modulation format, as shown in Figure 2 , on the specific resources indicated in the SIG field. These fields are transmitted together with the beamforming weight matrices determined after the probing phase and will be used during the next data transfer between oAP1 and oSTA1 to oSTA_N. These beamforming weight matrices are denoted by Q. Since the operation applying the beamforming matrices corresponds to a mathematical multiplication per frequency bin, the beamforming sequences are described in Figure 2 as Q STF and Q LTF. The Q matrix can be the beamforming weight matrix to be used in the next transmission phase of oAP1 for training the MUMIMO configuration or a function thereof. More precisely, in the transmission, the matrix Q is defined based on the RUs to be used. However, it is also possible to use a Q matrix defined coarser, for example based on the channel bandwidth instead of the RU granularity, or considering some robustness margin for interference protection. The STF and LTF fields are modulated using the beamforming weight matrices calculated recently, enabling oSTAs to estimate the beamformed channel or interference level.

[0051] For transmitting the training data unit 25, the information about the beamforming configuration determined in the previous sounding procedure 20 is preferably used. For example, the transmission of the training data unit 25 can be performed such that the set of estimated sequences included in the signaling information is modulated by beamforming weights calculated after the sounding based on the sounding information obtained in the sounding procedure 20.

[0052] The transmission of the training data unit 25 can be announced by the NDP announcement 21. This enables the oAPs to understand that they should also be prepared to estimate the channel of the STAs 1 to N and determine the possibility of SR transmission. Furthermore, this allows to keep the channel busy during the sounding, which includes the transmission of the training data unit. In one embodiment, the training data unit is sent after a short interframe space (SIFS) time after the feedback TB PPDU. However, it can also be transmitted within a separate transmission opportunity.

[0053] After estimating the channel of the STAs based on the response 24 (e.g. TB PPDU) and checking whether the estimated RUs are the same or close to the RUs that will be used during the subsequent MU MIMO transmission from the API based on the training data unit 25, the oAPI collects the measurement reports from a specific set of STAs. For this, it can send a trigger frame 26, in response to which the oSTAs transmit a response, e.g. by transmitting one TB PPDU 27 each, which contains the requested RU and interference level report. Finally, the oAPI sends an SR Ack 28, which allows the oSTAs to participate in the next shared transmission opportunity (TXOP), which can indicate the RU allocation and the session index. The RU allocation is only valid for the given session index. Once the API announces a different session index, the operations described before can be repeated. The session index is preferably used in the subsequent data transmission from the API to the STAs corresponding to the same group and the same beamforming configuration as the one currently used.

[0054] If multiple MIMO configurations of one or more groups of STAs are determined as part of the training, the proposed training data unit 25' can be designed to contain information about these configurations. This is the case, for example, if the oAP determines that the channel conditions of the STAs are not good enough for a single MIMO configuration, but that a combination of multiple MIMO configurations would be more efficient. In this case, the oAP can transmit the training data unit 25' containing the information about the multiple MIMO configurations to the STAs. The STAs can then estimate the channel based on the multiple MIMO configurations and report the results to the oAP. The oAP can then determine the best combination of MIMO configurations and transmit the SR to the STAs. Figure 3An illustration of another embodiment of the method using explicit sounding according to the present application is illustrated in FIG. 3. In this embodiment of the training data unit 25', after the legacy and SIG fields, a synchronization and estimation sequence is transmitted, for example, an EHT modulated STF and LTF, followed by a frame containing the possible set of configurations. Thereafter, one or more beamforming configurations can modulate additional LTF fields, for example, within a packet extension, allowing the oSTA to measure the channel and / or interference level from the API to the oSTA. The packet extension refers to the fact that some extra padding is appended after the data portion of the regular PPDU, or in this case, the estimation sequence. The presence of these fields must be signaled in the preamble of the packet. The Q matrix applied in this case is defined according to the RU, at least corresponding to the first configuration used for data transmission.

[0055] In Figure 2 and Figure 3 , the training data unit 25 is a PPDU transmitted using the computed beamforming weights during the same sounding interval, i.e., during the DL sounding procedure 20. According to the embodiment shown in Figure 2 , the training data unit (or training PPDU) does not carry a MAC frame, but only includes a PHY preamble. According to the embodiment shown in Figure 3 , the training data unit is a PPDU that carries a MAC data, however, the content of the data is control information regarding the RU allocation, the STA identifier and the beamforming configuration. In some cases, it can be useful to include control information in the training data unit. One is when the training PPDU is transmitted in a single user PPDU format, in which case it is not possible to include control information for all STAs. The second case is when multiple MIMO configurations are computed in the sounding procedure, but these configurations cannot be signaled in the preamble of the packet. In the latter case, the training data unit is a PPDU that contains a PHY preamble, a frame containing control information and additional estimation sequences corresponding to the beamforming configurations indicated within the frame.

[0056] The idea described above with respect to Figure 2 and Figure 3 can also be used for implicit sounding between the AP and STAl to STA_N. Figure 4 An illustration of one embodiment of the method using implicit sounding according to the present application is shown in FIG. 4. The advantage of implicit training is that, in this case, the oAP can determine the channel over the full bandwidth or full RU range from STAl to STA_N, from which the API will decide the final RU and beamforming allocation. In comparison, in Figure 2 and Figure 3 , the oAP can only correctly estimate the channel on the specific RU allocation for which the STAs respond to the request.

[0057] In Figure 4In the embodiment shown, the training, i.e. the downlink sounding procedure 40, starts with a request 41 for responses from STA1 to STA_N, in particular by sending a trigger frame. The trigger frame indicates on which parameters the second STAs shall transmit the subsequent responses 42. Among these parameters are included one or more of: channel and bandwidth information, number of orthogonal synchronization and estimation sequences to be used by each STA, identifiers of the synchronization and estimation sequences to be used by each STA, and transmission power requirements to be respected by the STAs when transmitting the responses 42. The latter is used to ensure the correct differentiation of the channels and the transmissions. In response to the request, in particular within a short interframe space (SIFS) of the trigger frame, the responses 42 are sent by all the STAs addressed in the trigger frame and use the parameters requested by the API, in particular by sending response data units. Unlike the responses 24, the responses 42 can consist entirely of PHY preambles, including legacy synchronization, estimation and signaling and standard specific signaling, synchronization and estimation sequences, where the latter are transmitted in an orthogonal way. Since in the embodiment shown the API estimates the channels of the STA1 to STA_N directly from the estimation sequences, no data frames need to be included in the TB PPDU 42 at the time of the estimation (possibly included for purposes other than the applications described herein). In contrast, in the embodiments shown in Figure 4 and Figure 2 , the STA1 to STA_N estimate the channels and feed back the estimation results to the API. Therefore, the responses 24 contain channel feedback information within the data field. Subsequently, a training data unit 43 is sent, similar or identical to the content of the training data unit 25 described above with reference to Figure 3 and Figure 2 , followed by the same steps shown in Figure 2 and Figure 3 , with reference to items 26 to 28.

[0058] The embodiment described above with reference to Figures 2 to 4 implies that the API needs to send a specific PPDU (training data unit) after the sounding procedure, but for the stations within its BSS, i.e. the stations related to the API, the value of the PPDU is low or null. Figure 5 Another embodiment of the method according to the present application is shown, which avoids this overhead and does not transmit a training data unit after the sounding procedure, but during the regular data transmission.

[0059] In this embodiment, the oAP acquires the channel information from a multi-user (MU) PPDU (training data unit 53) sent by the API during the regular data transmission 50. Figure 5 The procedure required to collect the CSI and the measurement report is described in particular, while the operation of the beamforming weight matrix obtained using the newly collected CSI is shown in Figure 6 .

[0060] like Figure 5 As shown, during the detection phase ( Figure 5 Following (not described in the text) and during transmission phase 50 (also known as transmission opportunity TXOP1), AP1 attempts a MU DL transmission by sending a MU-Ready Transmission (RTS) trigger frame 51 to the STAs that are part of the MU group to be served. Upon receiving the MU-RTS frame 51, each frame responds with a Clear Transmission (CTS) frame 52 within the same predetermined time interval. For STA1 to STA_N, this is the normal MU DL operation. However, based on the QE-STF and QE-LTF within the MU PPDU 53, the oSTA can estimate the interference and / or channel for each RU allocation and MU session configuration. Stations STA1 to STA_N respond with response 54. The preamble portion of 54 is the same as or similar to response 24 or 42; these packets differ only functionally (the former sends acknowledgment information to the data unit sent from the AP, while the latter contains channel feedback information). However, for the purposes described herein, the data content of 54, 24, and 42 is not important, as oSTAs and oAPs typically only use the preamble information.

[0061] Under current standard operation, MU PPDUs are currently used for a specific STA indicated by the allocation identifier in the preamble, and oSTAs that are not intended to receive the data packet typically discard it. Therefore, to achieve the above operation, it is recommended to redefine MU RTS trigger 51 to indicate to the oSTA the start of an SR-qualified MU MIMO transmission. Based on the indication of MU RTS frame 51 and the indication of oAP, the oSTA measures CSI according to the request of its corresponding oAP. After transmitting the opportunity TXOP1 indicating MU operation, the oAP contends for the channel. The winner transmits trigger frame 26 to the corresponding oSTA associated with it on the RU requesting the measurement report.

[0062] Therefore, according to Figure 5 In the illustrated embodiment, based on MU RTS trigger frame 51, the oSTA begins measuring the channel on the preamble of subsequent MU frames. The indication of the session index (indicating one or more beamforming configurations, the functionality of the beamforming configuration, the identifier of the expected first station, and / or the resource element allocation used by AP1; in the embodiment indicating the group ID and beamforming configuration) helps to indicate to the oSTA whether they have been requested to measure a specific session and configuration.

[0063] With the trigger-based PPDU (training data unit 53), the oAP is estimating or updating the channel on each RU. If previous RU channel estimates are available, the channel is determined using the available information averaged from previous training phases. The transmit power (TxPower) of each STA should be indicated in order to distinguish between channel effects and transmit effects. This can easily be included in the preamble of the training data unit 53. The transmit opportunity TxOP2 follows the transmit opportunity TxOP1, including Figures 2 to 4 steps 26 to 28 shown in

[0064] The opportunity beamforming operation based on the newly calculated counteracted beamforming weight matrix (denoted as transmit opportunity TxOP3) as shown in Figure 6 The MU operation between the AP1 and the STA1 to STA_N follows the usual procedure, i.e. starting with an RTS trigger frame 60 from the AP1, the addressed STAs respond with a CTS 61 based on the trigger. The oAP, which has gained channel access within the transmit opportunity TxOP2 (as shown in Figure 5 ) collects the measurement reports and calculates the beamforming matrix with counteracted constraints, the oAP also responds with an RTS frame. From the oAP1, this is a CTS to self 62, intended to inform the STAs and oSTAs about the medium reservation. Irrespective of how the training has been conducted, that is, irrespective of whether it has been an explicit training as shown in Figure 6 Figure 6 the operation is the same. Figure 4 Figure 5 or an implicit training as shown in, or training embedded in the AP1 MU transmit opportunity as shown in

[0065] Figure 6 The SR PPDU based on BF, i.e. the response 64 to the physical protocol data unit 63 (PPDU) for the regular data transmission, is transmitted such that the preamble part is beamformed with the beamforming matrix such that the transmission of the PPDU 63 does not cause interference to the STA1 to STA_N. The beamforming weight matrix QN1 can be the same matrix used during the regular transmission or it can be a coarser version of the matrix. Coarse means thus that it is designed to cover the whole channel from which the actual RUs for the transmission between the oAP and the oSTAs are selected, a smoothing in frequency can be chosen. Finally, the stations STA1 to STA_N transmit an acknowledgement 65 to the AP1 indicating the correct reception of the MAC data unit from the AP1 or the need for a retransmission. The acknowledgement from the oSTAs to the oAP will be transmitted in different time unit intervals as the acknowledgement of the STAs (not shown in

[0066] ​​Beamforming session indexes can be included in RTS triggers. This allows the second access point to determine whether the beamforming session index has the latest communication parameters for a specific beamforming scenario, i.e., whether it can serve the oSTA without causing interference.

[0067] Figure 7 A flowchart of an operational embodiment of the second access point oAP1 is shown. In the first step S10, oAP1 performs channel estimation on the channel from the STA. The estimation is based on the UL transmission of the STA, and more specifically, on response frames 24 and 42 (see...). Figures 2 to 4 In the second step S11, oAP1 determines the RU allocation for the STA based on the SIG field of the training data unit sent after the training phase. Subsequently, in step S12, oAP1 determines a set of RUs that can potentially be used: i) a set of allocated RUs with obtained channel estimates, ii) a set of allocated RUs with inferred channel estimates, and iii) a set of free RUs. For RUs from set i), beamforming with interference constraints is preferably used; for RUs from set ii), robust cancellation for the STA is preferably used; and for RUs from set iii), these cancellations can be used without beamforming. Robust cancellation refers to a beamforming design that maintains interference cancellation conditions unchanged even when errors are within a certain range. In the fourth step S13, a trigger frame containing a measurement report request is transmitted. In the fifth step S14, based on the measurement reports and channel estimates received from the relevant stations, the cancellation beamforming weights, i.e., beamforming weights (which prioritize interference constraints at the STA), are calculated.

[0068] Therefore, oAP1 can determine whether spatial multiplexing is feasible and calculate the beamforming weight vector to ensure no interference occurs, then transmit data to the second station during the transmission opportunity of the first access point, for which spatial multiplexing has been determined. oAP1 can thus create cancellation. The session index indicates the beamforming configuration determined by AP1 and used in data transmission. oAP1 uses the session index to request a measurement report from oSTA for the specific beamforming configuration indicated in the session index. oAP1 also uses the session index transmitted within the PPDU during data transmission to determine whether the beamforming configuration determines a configuration that cancels beamforming weights for it. Based on the session index, oAP1 can determine whether it can spatially multiplex AP1's data transmission opportunities, characterized by the beamforming configuration shown.

[0069] Figure 8A diagram showing the flow of states of the second station oSTA. If the oSTA receives an indication from the oAP in the previous message exchange containing a schedule of expected sounding times and channel information, it shall measure the interference or session index (step S20), it will wait to receive the training data unit within the specified time interval with a certain time tolerance. The oSTA waits to receive the legacy preamble and, if received correctly, proceeds to decode the U+E SIG (step S21).

[0070] If the oSTA is able to decode the SIG information correctly, it will proceed to determine the session index, the format and number of LTFs and further perform channel estimation per frequency / subcarrier (step S22). If the training data unit is required, the legacy preamble is decoded but the U+E SIG is not decoded. Then, only the preamble is power measured (step S23).

[0071] If the training plan is not received or not defined, upon detecting the preamble of the training data unit, the oSTA decodes the U+E SIG field (step S24) relying only on the information in the U+E SIG field to determine whether the received data packet is a training data unit and to determine the session index (step S25). The oAP further performs channel measurement on the beamformed LTF sequence (step S26). If the U+E SIG is not decoded, the training data unit is discarded (step S27).

[0072] The measurement report is prepared and transmitted from the oAP to the oSTA in response to the trigger frame 26 in step S28 or S29, which shall contain a series of channel specifications and channel phases (preferably in compressed form) or measured signal power for the indicated RUs. If no measurement is performed in the RU, a default value is shown.

[0073] The measurement report request transmitted by the oAP in the trigger frame 26 shall contain information about the RUs that the oAP identifies as potentially shared (i.e. RUs where the oAP can control the interference to STAs below a required limit) and the type of measurement, e.g. signal strength or channel specification and phase feedback for a specific RU. Prior to the request, the oAP can transmit information including the timestamp of the next round of interest sounding and the corresponding session index. This information can be obtained by the oAP from the control information broadcast by the AP1 and will be embedded in the frame transmitted to the oSTA, which occurs prior to the flow presented in the present disclosure.

[0074] Figure 9The flowchart shows an operational example of the first access point AP1. In the first step S30, AP1 performs a detection process with respect to one or more first stations to determine resource unit allocation and beamforming configuration for use in subsequent communication with the corresponding first stations. In the second step S31, a training data unit containing signaling information regarding the determined resource unit allocation and the determined beamforming configuration is transmitted, wherein the training data unit is transmitted using a beamforming configuration derived from the determined resource unit allocation and the determined beamforming configuration. Thus, the training data unit can be transmitted using the determined beamforming configuration or a beamforming configuration determined based on the determined beamforming configuration (and / or determined resource unit allocation). More precisely, the latter refers to extending the beamforming weights to the frequency subcarriers corresponding to the entire channel or frequency block to which a particular RU belongs, or smoothing over frequency, or applying beamforming weights corresponding to the determined configuration, but adapting to statistical channel knowledge. The advantage of the latter is that it changes slowly over time, while demonstrating an acceptable indication of the interference level that an oSTA will experience from AP1. In the third step S32, a physical protocol data unit is transmitted to the one or more first stations, the physical protocol data unit including a session index, a training sequence, and data to be transmitted to the corresponding first stations.

[0075] Figure 10 The figure shows an example of a training data unit for cancellation training. The required control signals to be included in the U+E SIG field include: bandwidth and channel, resource allocation, session index (identifying the MU and BF configuration so that measurements can be averaged or updated when using the configuration), and the number and format of LTFs.

[0076] It should be noted that the session index applies to all detection processes disclosed herein and is a combination of RU allocation user ID and updated beamforming information. Any other oSTA or oAP can perform any operation based on this.

[0077] Signaling the session index is challenging because when the AP runs for a long time and often changes the RU allocation and beamforming configuration, it may exhaust the session index since these session numbers come from a finite set. Thus, an implementation of a forgetting mechanism can be applied, as described below.

[0078] Assume that the session index set contains N indices from 0 to N - 1, and the standard or AP1 can define a representation of a window of consecutive indices that are in use, considered to be the current window length W < N - 1. That is, any oAP will observe the session index transmitted by AP1 in the PPDU. It maintains a set 5 that contains W consecutive session indices. Once an oAP observes a session index T that does not belong to the current set, the oAP establishes a new set, which is given by the following equation:

[0079] S = [mod(T-W+1, N)...T]

[0080] In this equation, T can be less than mod(T-W+1, N), in which case the window extends from mod(T-W+1, 7V) to T via N-1. This can also be expressed by the definition of specific cases, as follows:

[0081]

[0082] Initially, set S is undefined; that is, oAP waits for the first session index of AP1 and establishes its set according to the equation above. For each element of the set, oAP should note which STAs can provide services and have been trained according to the procedure described above. Any session index outside the current set S is considered untrained and needs to be trained or retrained according to the procedure above before oAP can provide services to oSTAs.

[0083] Two examples illustrate this implementation:

[0084] Given N=8, W=4, and T=5, the result is 5=[2…5].

[0085] N=8, W=4, T=2 results in 5=[0…2,7]

[0086] The present invention has the following advantages: beamforming for assisted spatial multiplexing with minimal cooperation between APs; avoids the need for a master AP to coordinate the scheme and collect information about STAs from other BSSs that need to be offset; the disclosed solution can be designed to be backward compatible, for example, allowing EHT STAs with certain versions of the coordination BF to still participate in the spatial multiplexing scheme (due to signaling and channel acquisition methods); and naturally maps to spatial multiplexing and probe concepts.

[0087] Therefore, the foregoing discussion has only disclosed and described exemplary embodiments of this disclosure. Those skilled in the art will understand that the invention may be embodied in other specific forms without departing from its spirit or essential characteristics. Thus, the disclosure of this invention is intended to be illustrative, but not to limit the scope of the disclosure and the other claims. This invention, including any readily identifiable variations taught herein, partially defines the scope of the foregoing claims, such that no inventive subject matter is specifically directed to the public.

[0088] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plural. A single element or other unit can perform the function of several items listed in the claims. The fact that certain measures are listed only in mutually different dependent claims does not indicate that a combination of these measures cannot be advantageous.

[0089] With regard to the description of embodiments of the invention as being implemented at least in part by a data processing device controlled by software, it should be recognized that non-transient machine-readable media carrying such software, such as optical discs, magnetic disks, semiconductor memories, etc., are also considered to represent an embodiment of the invention. Furthermore, such software may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0090] The components of the disclosed devices, apparatuses, and systems can be implemented using appropriate hardware and / or software components, such as suitable circuits or cascades. A circuit is a structural collection of electronic components including conventional circuit elements, integrated circuits (including application-specific integrated circuits), standard integrated circuits, application-specific standard products, and field-programmable gate arrays. Furthermore, a circuit includes a central processing unit, graphics processing unit, and microprocessor programmed or configured according to software code. A circuit does not include pure software, although it includes the aforementioned hardware to execute software.

[0091] The following is a list of further embodiments of the disclosed subject matter:

[0092] 1. A first access point, including circuitry, configured as follows:

[0093] - A probe process is performed relative to one or more first stations, which are associated with and configured to communicate with the first access point via appropriate channels, to determine resource element allocation and beamforming configurations for use in subsequent communications with the respective first stations; and

[0094] - Transmit training data units containing signaling information related to the determined resource unit allocation and the determined beamforming configuration, wherein the training data units are transmitted using beamforming configurations derived from the determined resource unit allocation and the determined beamforming configuration.

[0095] 2. The first access point as defined in any of the foregoing embodiments, wherein the signaling information includes an identifier indicating that the destination of the training data unit is one or more second stations associated with the second access point and / or unassociated with the first access point or propagation group.

[0096] 3. The first access point as defined in any of the foregoing embodiments, wherein the signaling information includes one or more of the following: resource unit allocation, beamforming configuration, number of channel estimation sequences, type of channel estimation sequences, indication of training packets, and indication of whether spatial multiplexing is permitted during data transmission using beamforming or session index parameters indicated in the signaling information.

[0097] 4. The first access point as defined in any of the foregoing embodiments, wherein the training data unit includes a session index indicating one or more of the following: beamforming configuration, identifier of the intended first station, resource unit allocation used by the first access point, and one or more transmission parameters.

[0098] 5. The first access point as defined in any of the foregoing embodiments, wherein the training data unit includes a MAC frame carrying information about one or more MIMO configurations of a group or more first stations and resource unit allocations, the group or more first stations being associated with the first access point and configured to communicate with the first access point through a corresponding channel.

[0099] 6. The first access point as defined in any of the foregoing embodiments,

[0100] The circuit is configured to perform the downlink probing process via the following:

[0101] - Announcement of empty data packet transmission;

[0102] - Transmit one or more empty data packets;

[0103] - Request feedback from one or more first stations regarding the corresponding resource units; intranasal cavity

[0104] - Receive feedback data units transmitted by one or more first stations.

[0105] 7. The first access point defined in Example 6,

[0106] The circuit is configured to receive feedback data units transmitted by one or more first stations, which use corresponding resource units to transmit requested feedback and use empty data packet announcements to indicate the channel bandwidth used to transmit the estimated sequence.

[0107] 8. The first access point defined in Embodiment 6 or 7,

[0108] The circuit is configured to indicate in the empty data packet announcement one or more of the following: the start of the probe interval for qualified transmission of spatial multiplexing, the bandwidth information to be used in subsequent probes, and the transmission of training data units.

[0109] 9. The first access point defined in Embodiments 6, 7, or 8,

[0110] The circuit is configured to transmit training data units during a period after receiving feedback data units, during an interval of downlink probing, or during the last segment of an interval of downlink probing.

[0111] 10. The first access point as defined in any of the foregoing embodiments,

[0112] The circuit is configured to perform the downlink probing process via the following:

[0113] - A transmission trigger requests a response from one or more first stations, the trigger containing information about resource allocation for the respective first station, the number of training sequences, the number of streams per resource unit, identifiers of orthogonal sequences to be used by the respective first station, one or more of the respective first station's transmission power requirements, and whether spatial multiplexing is permitted in future transmissions; and

[0114] - Receive response data units transmitted by one or more first stations based on parameters contained in the trigger.

[0115] 11. The first access point defined in any of the above embodiments,

[0116] The circuit is configured to transmit training data units containing signaling information as part of data communication with one or more first stations.

[0117] 12. The first access point defined in any of the above embodiments, wherein the circuit is configured as follows:

[0118] - After performing the downlink probe procedure, a transmission-ready RTS is sent to trigger one or more first stations. The RTS trigger indicates the start of spatially multiplexed qualified MIMO transmission; and

[0119] - Receive the cleared CTS response from the first station that has sent one or more RTS triggers.

[0120] 13. The first access point defined in Example 12,

[0121] The RTS trigger contains a session index, which refers to one or more first stations served in a subsequent PPDU.

[0122] 14. The first access point defined in Example 4,

[0123] The circuit is configured to transmit a physical protocol data unit to one or more first stations after executing a downlink probing procedure. The physical protocol data unit includes a session index, a training sequence, and data to be transmitted to the corresponding first station.

[0124] 15. The first access point as defined in any of the foregoing embodiments,

[0125] The training data unit contains synchronization and / or estimated sequences.

[0126] 16. The first access point as defined in any of the foregoing embodiments,

[0127] The circuit is configured to transmit training data units containing signaling information as part of data communication with one or more first stations.

[0128] 17. The first access point as defined in any of the foregoing embodiments,

[0129] The beamforming session index is included in the RTS trigger.

[0130] 18. The first access point as defined in any of the foregoing embodiments,

[0131] The training data contains information about beamforming configurations within general signaling fields or standard version independent signaling fields.

[0132] 19. The first access point as defined in any of the foregoing embodiments,

[0133] The circuit is configured to predict the channel from adjacent resource cells to the estimated resource cells and create beamforming vectors that invalidate interference within these resource cells, resulting in a larger error magnitude compared to the estimated resource cells.

[0134] 20. A second access point, including circuitry, configured to:

[0135] - Listen to response data units transmitted by one or more first stations, which are associated with and configured to communicate with the first access point via appropriate channels, the response data units being transmitted by one or more first stations during a probe performed by the first access point relative to the one or more first stations;

[0136] - Estimate the corresponding channel using the received response data unit;

[0137] - Listen to training data units transmitted by the first access point, the training data units containing signaling information related to resource unit allocation and beamforming configuration determined by the first access point for use in subsequent communications with the corresponding first station, wherein the training data units are transmitted using beamforming configurations derived from the determined resource unit allocation and determined beamforming configurations.

[0138] - Based on the signaling information contained in the received training data units, determine the resource unit allocation and beamforming configuration for use in subsequent communications with one or more second stations associated with a second access point.

[0139] 21. The second access point defined in Example 20,

[0140] The circuit is configured as follows:

[0141] - Determine if spatial multiplexing is feasible and calculate the beamforming weight vector to ensure no interference occurs.

[0142] - Data is transmitted to the second station during a transmission opportunity at the first access point, for which the second access point has determined that spatial multiplexing is possible.

[0143] 22. A second access point as defined in any of embodiments 20 to 21, wherein the circuitry is configured to estimate the respective channels using the estimated and signaling information contained in the received response data units.

[0144] 23. The second access point defined in any of embodiments 20 to 22,

[0145] The circuit is further configured as follows:

[0146] - Request feedback from one or more second stations regarding resource elements and / or interference levels and / or request channel feedback information regarding one or more resource elements; and

[0147] - Receive feedback data units transmitted by one or more second stations, the received feedback data units containing the requested feedback.

[0148] 24. The second access point defined in Example 23,

[0149] The circuit is configured to request feedback via a transmission trigger, which includes information about one or more resource units available for subsequent communication, the resource unit requesting feedback, and the format of the requested feedback.

[0150] 25. The second access point defined in any of embodiments 20 to 24,

[0151] The circuit is configured to transmit acknowledgments to one or more second stations for subsequent communication with the second access point. These acknowledgments indicate acknowledgments of one or more session indices, second stations authorized to use spatial multiplexing resources, resource allocation, beamforming configuration, and acknowledgment behavior.

[0152] 26. The second access point defined in any of embodiments 20 to 25,

[0153] The circuit is configured as follows:

[0154] - Listen to a ready-to-transmit RTS trigger transmitted from a first access point to one or more first stations, the RTS trigger indicating the start of a shared resource qualified MIMO transmission and preferably indicating a session index of the beamforming configuration or beamforming configuration functionality used by the first access point; and - estimate the channel from one or more first stations to the first access point during uplink transmission, or transmit explicitly, CTS acknowledge, and then transmit data to one or more second stations STA.

[0155] 27. The second access point defined in any of embodiments 20 to 26,

[0156] The circuit is configured to communicate with one or more second stations using a corresponding beamforming configuration that does not interfere with the resource unit allocation and beamforming configuration of one or more first stations that have been determined.

[0157] 28. The second access point defined in any of embodiments 20 to 27,

[0158] The circuit is further configured to request measurements during frame exchanges that occur prior to the probe procedure.

[0159] 29. The second access point defined in Example 28,

[0160] The circuit is also configured to request measurements by transmitting a frame to a set of second stations, the frame indicating that it is requested to listen for specific probe information, particularly probes from a set of first access points and / or probes within a certain time interval, and / or probes from first access points using a known beamforming session index, and to prepare a report.

[0161] 30. The second station includes a circuit, which is configured as follows:

[0162] - Listen to training data units transmitted by a first access point, which is associated with one or more first stations to communicate with the first access point via a corresponding channel. The training data units contain signaling information related to resource unit allocation and beamforming configuration determined by the first access point for use in subsequent communications with the corresponding first station, wherein the training data units are transmitted using beamforming configurations derived from the determined resource unit allocation and determined beamforming configuration.

[0163] - Estimate channel and / or interference information based on the received training data units;

[0164] - The estimated channel and / or interference information is transmitted to a second access point, which will be associated with a second station to communicate via the channel.

[0165] 31. The second station as defined in Example 30,

[0166] The circuit is further configured as follows:

[0167] - Monitor the channel used to transmit training data units and indications, which are probes for qualified transmission in future space multiplexing; and

[0168] - Report the estimated channel and interference information requested by the second access point for the session index, or the estimated channel and interference information for the session index where the interference is below a predetermined threshold, the session index indicating the beamforming configuration or a function of the beamforming configuration used by the first access point.

[0169] 32. The second station defined in any of the embodiments 30 to 31,

[0170] The circuit is further configured to determine beamforming-related information based on signaling information contained in the received training data unit for estimating channel or interference information.

[0171] 33. The second station as defined in any of Examples 30 to 32,

[0172] The circuit is further configured to transmit feedback data units as estimated channel and / or interference information, the feedback data units containing feedback on the corresponding resource unit and / or interference level, and / or channel feedback information on one or more resource units.

[0173] 34. The second station as defined in Example 33,

[0174] The circuit is configured to transmit feedback data units with orthogonal training sequences on a bandwidth greater than the bandwidth of the data transmission portion below.

[0175] 35. The second station as defined in any of the embodiments 30 to 34,

[0176] The circuit is further configured as follows:

[0177] - Listen for probe intervals that differ from those associated with the access point, particularly based on requests from a second access point or on qualified training based on spatial multiplexing.

[0178] - Estimate channel or interference information, especially based on training data units.

[0179] - Monitor packets transmitted in the monitoring channel that have spatial multiplexing qualification indicators, and

[0180] - Report the channel and interference level of the requested beamforming session index or beamforming session index that is below a predetermined threshold.

[0181] 36. The second station defined in any of the embodiments 30 to 35,

[0182] The circuit is further configured to determine beamforming-related information based on the SIG field of the training data unit, particularly the type of multiple estimation sequences and / or antenna-to-stream mappings, to allow for accurate estimation of channel and / or interference levels.

[0183] 37. The second station as defined in any of Examples 30 to 36,

[0184] The circuit is also configured to transmit PPDUs with orthogonal training sequences on a bandwidth greater than the bandwidth of the portion of the circuit that transmits subsequent data.

[0185] 38. The methods used by the first access point include:

[0186] - A detection process is performed relative to one or more first stations, which are associated with and configured to communicate with the first access point via appropriate channels to determine resource element allocation and beamforming configurations for use in subsequent communications with the respective first stations; and

[0187] - Transmit training data units containing signaling information related to the determined resource unit allocation and signaling information related to the determined beamforming configuration, wherein the training data units are transmitted using a beamforming configuration derived from the determined resource unit allocation and the determined beamforming configuration.

[0188] 39. The methods used by the second access point, including

[0189] - Listen to response data units transmitted by one or more first stations, which are associated with and configured to communicate with the first access point via appropriate channels. The response data units are transmitted by one or more first stations during a probe performed by the first access point relative to the one or more first stations.

[0190] - Estimate the corresponding channel using the received response data unit;

[0191] - Listen to training data units transmitted by the first access point, the training data units containing signaling information related to resource unit allocation and beamforming configuration determined by the first access point for use in subsequent communications with the corresponding first station, wherein the training data units are transmitted using beamforming configurations derived from the determined resource unit allocation and determined beamforming configurations.

[0192] - Based on the signaling information contained in the received training data units, determine the resource unit allocation and beamforming configuration for use in subsequent communications with one or more second stations associated with a second access point.

[0193] 40. The methods used in the second station include

[0194] - Listen to training data units transmitted by a first access point, one or more first stations associated with the first access point to communicate with the first access point via a corresponding channel, the training data units containing signaling information related to resource unit allocations and beamforming configurations determined by the first access point for use in subsequent communications with the corresponding first station, wherein the training data units are transmitted using beamforming configurations derived from the determined resource unit allocations and determined beamforming configurations;

[0195] - Estimate channel and / or interference information based on the received training data units;

[0196] - The estimated channel and / or interference information is transmitted to the second access point, which is associated with the second access point to communicate via the channel.

[0197] 41. A non-transient 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 performed.

[0198] 42. A computer program, including program code means, which, when executed on a computer, causes the computer to perform the steps described in the method according to embodiments 38, 39 or 40.

Claims

1. A first access point, including circuitry, said circuitry being configured to: - The detection process is performed only relative to one or more first stations, which are associated with and configured to communicate with the first access point via appropriate channels to determine resource element allocation and beamforming configurations for use in subsequent communications with the respective first stations; and - Training data units that transmit signaling information related to the determined resource unit allocation and signaling information related to the determined beamforming configuration, wherein, The training data units are transmitted using a beamforming configuration derived from the determined resource unit allocation and the determined beamforming configuration.

2. The first access point according to claim 1, in, The signaling information includes an identifier indicating that the destination of the training data unit is one or more second access points and / or a second station, the second station being associated with the second access point and not associated with the first access point or propagation group, or The signaling information includes one or more of the following: the resource unit allocation, the beamforming configuration, the number of channel estimation sequences, the type of channel estimation sequences, the indication of training packets, and the indication of whether spatial multiplexing is allowed during data transmission using the beamforming or session index parameters indicated in the signaling information.

3. The first access point according to claim 1, in, The training data unit includes a session index indicating one or more of the following: the beamforming configuration, the identifier of the intended first station, the resource unit allocation used by the first access point, and one or more transmission parameters, and / or wherein the training data unit includes a MAC frame carrying information about one or more MIMO configurations and resource unit allocations for one or more groups of first stations associated with and configured to communicate with the first access point via a corresponding channel.

4. The first access point according to claim 1, -in, The circuit is configured to perform a downlink probing process by: transmitting empty data packet announcements; - Transmit one or more empty data packets; - Request feedback from the one or more first stations regarding the corresponding resource units; and - Receive feedback data units transmitted by the one or more first stations.

5. The first access point according to claim 4, in, The circuit is configured to receive the feedback data unit transmitted by the one or more first stations, the one or more first stations using the corresponding resource unit to transmit the requested feedback, and using the channel bandwidth indicated in the empty data packet announcement for transmitting the estimated sequence, and / or The circuitry is configured to indicate in the empty data packet announcement: the start of a probe interval for spatial multiplexing qualified transmission, bandwidth information to be used in subsequent probes, and one or more of the transmissions of the training data units, and / or The circuit is configured to transmit the training data unit during a period of time after receiving the feedback data unit, or during an interval of the downlink probing process, or at the end of an interval of the downlink probing process.

6. The first access point according to claim 1, in, The circuit is configured to perform a downlink probing process via the following: - A transmission trigger requests a response from the one or more first stations, the trigger containing information about one or more of the following: resource allocation for the respective first station, the number of training sequences, the number of streams per resource unit, identifiers of orthogonal sequences to be used by the respective first station, transmission power requirements of the respective first station, and whether spatial multiplexing is permitted in future transmissions. and - Receive response data units transmitted by the one or more first stations based on parameters contained in the trigger.

7. The first access point according to claim 1, in, The circuit is configured to transmit the training data unit containing the signaling information as part of data communication with the one or more first stations, or, after performing a downlink probing process, to transmit a physical protocol data unit to the one or more first stations, the physical protocol data unit including a session index, a training sequence, and data to be transmitted to the corresponding first station.

8. A second access point, including circuitry, said circuitry being configured to: - Listen to response data units transmitted by one or more first stations, which are associated with and configured to communicate with the first access point via appropriate channels, the response data units being transmitted by the one or more first stations during a probe performed by the first access point only relative to the one or more first stations; - Estimate the corresponding channel using the received response data unit; - Listen to training data units transmitted by the first access point, the training data units containing signaling information related to resource unit allocation and beamforming configuration determined by the first access point for use in subsequent communications with the corresponding first station, wherein the training data units are transmitted using beamforming configurations derived from the determined resource unit allocation and determined beamforming configurations. - Based on the signaling information contained in the received training data units, determine the resource unit allocation and beamforming configuration for use in subsequent communications with one or more second stations associated with the second access point.

9. The second access point according to claim 8, in, The circuit is configured as follows: - Determine if spatial multiplexing is feasible, and calculate the beamforming weight vector to avoid interference. - During a transmission opportunity at the first access point, data is transmitted to the second station, for which the second access point has determined that spatial multiplexing is feasible.

10. The second access point according to claim 8, in, The circuit is further configured as follows: Request feedback from the one or more second stations regarding resource units and / or interference levels, and / or request channel feedback information regarding one or more resource units, particularly by means of a transmission trigger, the trigger including information about one or more resource units that can be used for subsequent communication, the resource unit for which feedback is requested, and the format of the requested feedback; and Receive feedback data units transmitted by the one or more second stations, wherein the received feedback data units contain the requested feedback.

11. The second access point according to claim 8, in, The circuit is configured to transmit an acknowledgment to the one or more second stations for subsequent communication with the second access point, the acknowledgment indicating one or more session indices, a second station permitted to use spatial multiplexing resources, resource allocation, beamforming configuration, and acknowledgment behavior.

12. The second access point according to claim 8, in, The circuit is configured to communicate with one or more second stations using a corresponding beamforming configuration that does not interfere with one or more first stations whose resource unit allocation and beamforming configuration have been determined.

13. The second station includes a circuit, which is configured as follows: - Listening to training data units transmitted by a first access point, one or more first stations associated with the first access point to communicate with the first access point via corresponding channels, the training data units containing signaling information determined by the first access point related to resource unit allocation and beamforming configurations for use in subsequent communications by the first access point only with the one or more first stations, wherein... The training data unit is transmitted using a beamforming configuration derived from the determined resource unit allocation and the determined beamforming configuration. - Estimate channel and / or interference information based on the received training data units; - The estimated channel and / or interference information is transmitted to a second access point, which is associated with the second access point to communicate via the channel.

14. The second station according to claim 13, in, The circuit is further configured as follows: - Monitor the channel used to transmit the training data units and indications, the indications being a probe for qualified transmission in future space multiplexing; and - Report the estimated channel and interference information requested by the second access point for a session index, or the estimated channel and interference information for a session index where the interference is below a predetermined threshold, wherein the session index indicates a beamforming configuration or a function of a beamforming configuration used by the first access point.

15. The second station according to claim 13, in, The circuit is further configured to determine beamforming-related information based on the signaling information contained in the received training data unit, for the purpose of estimating channel or interference information.

16. The second station according to claim 13, in, The circuit is further configured to transmit feedback data units as estimated channel and / or interference information, the feedback data units containing feedback about the corresponding resource unit and / or interference level, and / or channel feedback information about one or more resource units.

17. The method used by the first access point includes: - The detection process is performed only relative to one or more first stations, which are associated with and configured to communicate with the first access point via appropriate channels to determine resource element allocation and beamforming configurations for use in subsequent communications with the respective first stations; and - Transmit training data units containing signaling information related to the determined resource unit allocation and signaling information related to the determined beamforming configuration, wherein the training data units are transmitted using a beamforming configuration derived from the determined resource unit allocation and the determined beamforming configuration.

18. A method used by a second access point, including: - Listen to response data units transmitted by one or more first stations, which are associated with and configured to communicate with the first access point via appropriate channels, the response data units being transmitted by the one or more first stations during a probe performed by the first access point only relative to the one or more first stations; - Estimate the corresponding channel using the received response data unit; - Listen to training data units transmitted by the first access point, the training data units containing signaling information related to resource unit allocation and beamforming configuration determined by the first access point for use in subsequent communications with the corresponding first station, wherein the training data units are transmitted using beamforming configurations derived from the determined resource unit allocation and determined beamforming configurations. - Based on the signaling information contained in the received training data units, determine the resource unit allocation and beamforming configuration for use in subsequent communications with one or more second stations associated with the second access point.

19. The methods used by the second station, including - Listening to training data units transmitted by a first access point, one or more first stations associated with the first access point to communicate with the first access point via corresponding channels, the training data units containing signaling information determined by the first access point for resource unit allocation and beamforming configuration used only by the first access point in subsequent communications with the one or more first stations, wherein... The training data unit is transmitted using a beamforming configuration derived from the determined resource unit allocation and the determined beamforming configuration. - Estimate channel and / or interference information based on the received training data units; - The estimated channel and / or interference information is transmitted to a second access point, which is associated with the second access point to communicate via the channel.

20. A non-transient computer-readable recording medium storing a computer program product, which, when executed by a processor, causes to perform the method according to claim 17, 18 or 19.

Images