Communication devices and communication methods

Abstract

A first communication device configured to communicate with one or more third communication devices within its own basic service set includes a circuit configured to transmit a fourth feedback request information to the fourth communication device, which includes a requested feedback format and a requested number of feedback vectors or a range of requested feedback vectors with respect to the feedback that the fourth communication device provides; transmit a fourth training data to at least the fourth communication device; receive a fourth beamforming feedback from the fourth communication device, which includes a number of feedback vectors corresponding to the requested feedback format; calculate a steering matrix for communicating with the one or more third communication devices using beamforming based on the received fourth beamforming feedback; and communicate with the one or more third communication devices using the calculated steering matrix.

Description

[Technical Field]

[0001] This disclosure relates to a communication device and a communication method for communication in a cooperative beamforming scenario. [Background technology]

[0002] To perform beamforming, channel state information must be available on the transmitter side. Feeding back the complete, uncompressed channel coefficients for each subcarrier can result in enormous data volumes. In the compressed feedback scheme adopted by IEEE 802.11, the receiving base station (STA) currently needs to calculate the maximum singularity vector of the downlink channel, compress it, and transmit it to the access point (AP). When beamforming is used for interference mitigation, as in cooperative beamforming, feeding back the maximum singularity vector corresponding to the number of spatial streams used is not a suitable option. In such a method, the access point performing interferometric beamforming is constrained to protect spatial directions that are meaningless to the receiving station. Furthermore, this may prevent the access point from obtaining sufficient information to mitigate interference to base stations involved in simultaneous data exchange within a cooperative beamforming scenario.

[0003] The “Background” section in this specification is provided for the purpose of outlining the context of this disclosure. Within the scope described in this Background section, the currently recognized work of the inventors(s), and any aspects of the specification that may not be recognized as prior art at the time of filing, are not, expressly or implicitly, prior art to this disclosure. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2023 / 009996 Specification [Patent Document 2] U.S. Patent Application Publication No. 2019 / 058514 [Overview of the project] [Problems that the invention aims to solve]

[0005] The objective is to modify known concepts of feedback in cooperative beamforming scenarios to be more suitable for interferometric beamforming methods. A further objective is to provide corresponding communication devices and communication methods, as well as corresponding computer programs and non-temporary computer-readable recording media for storing computer program products for implementing said methods. [Means for solving the problem]

[0006] According to one embodiment, a first communication device is provided, configured to communicate with one or more third communication devices within its own basic service set, and comprising a circuit configured to transmit fourth feedback request information to the fourth communication device, the fourth feedback request information including a requested feedback format and a requested number of feedback vectors or a range of requested feedback vectors with respect to feedback to be fed back by the fourth communication device, transmit fourth training data to at least the fourth communication device, receive fourth beamforming feedback from the fourth communication device including a number of feedback vectors corresponding to the requested feedback format, calculate a steering matrix for communicating with the one or more third communication devices using beamforming based on the received fourth beamforming feedback, and communicate with the one or more third communication devices using the calculated steering matrix.

[0007] In another embodiment, a fourth communication device is provided, configured to communicate with a second communication device in its own basic service set, and comprising a circuit configured to receive fourth feedback request information from a first communication device configured to communicate with one or more third communication devices in another basic service set, the fourth feedback request information, which includes a request feedback format and a number of request feedback vectors or a range of request feedback vectors relating to feedback that the fourth communication device provides back to the first communication device, the fourth training data from the first communication device, the channel information estimated based on the received fourth training data, the feedback vector corresponding to the singular vector of the channel between the first communication device and the fourth communication based on the estimated channel information, and the fourth beamforming feedback including the calculated feedback vector to the first communication device in accordance with the request feedback format.

[0008] In yet another embodiment, a corresponding method, a computer program, and a non-temporary computer-readable recording medium are provided. The computer program, when executed on a computer, includes programming means for causing the computer to perform steps of the method disclosed herein. The non-temporary computer-readable recording medium, when executed by a processor, stores a computer program product that causes the method disclosed herein to perform.

[0009] Embodiments are defined in the dependent claims. It should be understood that the disclosed methods, disclosed computer programs and disclosed computer-readable recording media have similar and / or identical further embodiments to those described in the claims and defined in the dependent claims and / or disclosed herein.

[0010] One aspect of this disclosure is that an access point (first communication device) notifies an overlapping base station (oSTA) (fourth communication device) of an overlapping basic service set (OBSS) of the access point via a feedback request (fourth feedback request information) that it wishes to receive beamforming feedback from the oSTA and specifies the parameters thereof. This request feedback information includes information on the number (or range) of feedback vectors that the access point should protect from interference from transmissions from an overlapping access point (oAP) (second communication device) to the oSTA while transmitting to one or more base stations (third communication devices) within its BSS in a coordinated beamforming scenario. The feedback vectors fed back from the oSTA to the access point as beamforming feedback (fourth beamforming feedback) are used by the access point to construct a beamforming matrix (steering matrix) for communicating with the base station. This ensures that the channel or portion of the channel used for communication between the oAP and oSTA is protected from interference caused by the access point during communication with base stations within its own BSS. Furthermore, to achieve this objective, the feedback provided by the oSTA is more appropriate and efficient than feedback provided according to known concepts.

[0011] The preceding paragraph is provided as a general introduction and does not limit the scope of the following claims. Each embodiment described herein, along with its further advantages, will be best understood by referring to the following detailed description in conjunction with the accompanying drawings.

[0012] Many of the benefits of this disclosure and its associated advantages will be more readily understood by referring to the following detailed description in conjunction with the attached drawings. [Brief explanation of the drawing]

[0013] [Figure 1] A diagram illustrating a collaborative beamforming scenario is shown. [Figure 2] A more detailed diagram of the collaborative beamforming scenario is shown. [Figure 3] Another detailed diagram of the collaborative beamforming scenario is shown. [Figure 4] A diagram of the first embodiment of the communication method according to this disclosure is shown. [Figure 5] A diagram of a second embodiment of the communication method according to this disclosure is shown. [Figure 6] A diagram of a third embodiment of the communication method according to this disclosure is shown. [Figure 7] A diagram of a fourth embodiment of the communication method according to this disclosure is shown. [Figure 8A] A flowchart of one embodiment of the communication method for an access point according to this disclosure is shown. [Figure 8B] A flowchart of one embodiment of the communication method for an access point according to this disclosure is shown. [Figure 9A] A flowchart of a first embodiment of the method for constructing a steering matrix according to this disclosure is shown. [Figure 9B] A flowchart of a second embodiment of the method for constructing a steering matrix according to this disclosure is shown. [Figure 10A] A flowchart of one embodiment of the base station communication method according to this disclosure is shown. [Figure 10B] A flowchart of one embodiment of the base station communication method according to this disclosure is shown. [Figure 11] A schematic diagram of one embodiment of the communication system described herein is shown. [Figure 12] A flowchart of another embodiment of the access point communication method according to this disclosure is shown. [Figure 13] A flowchart of another embodiment of the base station communication method according to this disclosure is shown. [Modes for carrying out the invention]

[0014] Referring to the drawings, similar reference numerals refer to the same or corresponding parts across several figures. Figure 1 shows a coordinated beamforming (CBF) scenario. Two access points, access point AP1 (also referred to herein as the “first communication device”) and access point oAP1 (also referred to herein as the “second communication device”), each having multiple antennas, communicate with one base station, either base station STA1 (also referred to herein as the “third communication device”) or base station oSTA1 (also referred to herein as the “fourth communication device”). The communication between access point AP1 and base station STA1 and the communication between access point oAP1 and base station oSTA1 overlap completely or partially in time. The communication between access point AP1 and base station STA1 is H 1 This is done through the channel indicated by 1, channel H 1 o,1 This causes interference to base station oSTA1. Similarly, communication between access point oAP1 and base station oSTA1 occurs on channel H. o,1 o,1 Performed above, channel H o,1 1. This causes interference to base station STA1. Access point AP1 and base station oSTA1 do not exchange data (i.e., they do not communicate with each other), but they may exchange control messages. The same applies to access point oAP1 and base station STA1.

[0015] The following notation rules are used in this specification. Superscripts (o,1) and (1) indicate values ​​requested or transmitted by access point oAP1 and access point AP1, respectively. Subscripts (o,1) and (1) indicate values ​​received or requested by base station oSTA1 and base station STA1, respectively. Subscripts and superscripts are omitted when clear from the context. N req This indicates the number of feedback vectors that the access point requests from the base station (for example, access point AP1 requests from base station oSTA1) that should be protected from interference.C indicates the number of feedback vectors requested by an access point from a base station that transmits data communication (for example, access point AP1 requests from base station STA1).

[0016] The access point applies beamforming (BF: beamforming) to improve the communication link to its own base station and to protect the communication link from other BSSs to the base station. For example, the signal transmitted from access point oAP1 is x t = Q (o,1) s o,1 o,1 has the form of.

[0017] The applied beamforming matrix Q (o,1) has N (o,1) c columns and N (o,1) r rows. Here, N (o,1) c corresponds to the number of spatial streams of base station oSTA1, and N (o,1) r corresponds to the number of transmit antennas or the number of spatial streams transmitted during the transmission of a training data unit (null data packet) (also referred to as "training data" in this specification). The beamforming matrix Q (o,1) depends not only on the channel H (o,1) o,1 but also on the interference channel H (o,1) 1. In order to make the latter channel information available at access point oAP1, it is necessary to adapt sounding. The peculiarity of cooperative beamforming is that i) even when there is only one base station providing services to access point oAP1, the sounding procedure needs to follow the multi-user case, and ii) in that case, the number of columns of the beamforming matrix Q (o,1) depends only on the number of spatial streams of the base station (base station oSTA1) within each BSS and does not depend on the total number of base stations (base station STA1) to be sounded.

[0018] The feedback schemes currently covered by the IEEE 802.11 standard are left to implementation, but are generally thought to follow the following logic. This is H o,1 o,1 This is presented as an exception.

[0019] [Table 1]

[0020] More precisely, base station oSTA1 is H o,1 o,1 Perform a singular value decomposition (SVD) of the channel, and σ o,1 (o,1),1 ...σ (o,1) (o,1),Nss N corresponding to the maximum singularity shown as (o,1) SS,o,1 V consists of several vectors Gset (o,1) We select a set of V vectors, which are represented as follows. These vectors are further compressed by a series of matrix rotations and sent back to the access point.

[0021] Simply extending this feedback scheme to interference channels means that base station STA1 uses a singular vector in the channel matrix corresponding to the number of streams used in data exchange, i.e., N ss,1 Selecting this option suggests that a feedback vector for access point oAP1 needs to be calculated.

[0022] Transmitting the maximum singular vector corresponding to the number of streams used in data communication has several drawbacks when applied to the channel between access point AP1 and base station oSTA1, and the channel between access point oAP1 and base station STA1, respectively. Firstly, since access point oAP1 and access point AP1 do not exchange data with base station STA1 and base station oSTA1, respectively, these access points do not need to ensure a good quality communication link to base station STA1 and base station oSTA1, respectively. Therefore, beamforming channel Ho,1 1 and H 1 o,1 The maximum singular vector is not effectively used. Furthermore, protecting the singular vectors of these channels is H o,1 o,1 and H 1 1. This could unnecessarily restrict the precoder design of the communication link above. Finally, if the feedback information is limited by a stream number different from the channel rank, it becomes impossible for the access point to reconstruct the zero space of the interfered channel.

[0023] For these reasons, the selection matrix V of the feedback vector used by base stations requiring interference protection. SEL In the case of interference channels in cooperative beamforming, this should be adapted as follows (N I (This indicates the number of vectors being fed back.)

[0024] [Table 2]

[0025] Below, matrix V (o,1),SEL This document describes different embodiments of the method for selecting a vector within 1, the feedback required from the interference-protected base station (i.e., base station STA1 in the case of access point oAP1), the processing steps at access point oAP1, and the impact on the sounding flow. It also describes the corresponding changes to address the improved selection method. Since the characteristics of the interference channel also affect the direct communication channel, the feedback from base station STA1 to access point AP1 must be adapted accordingly. Finally, the required signaling adaptations are described. For clarity, the case from access point oAP1 to base station STA1 is chosen as a simple example.

[0026] Figure 2 shows a more detailed diagram of a co-beamforming scenario that explains the selection criteria for interference and communication channel feedback on a subspace basis. In this figure, channel H (o,1) 1 is the right singular vector direction V (o,1) 1,1 ...V (o,1) 1,N It is represented only by channel H. (o,1) o,1 and H 1 This also applies to point 1. Solid arrows represent channel directions corresponding to large singular values, while dashed lines represent small singular values ​​(possibly below or zero interference thresholds). In communication links, large right-hand singular vectors are important because they guarantee the best SINR (signal-to-interference + noise ratio) level. In interference links, directions corresponding to small singular vectors (preferably zero or below the interference threshold) are more important.

[0027] V (o,1),SEL 1 to N I One first option for selecting the vectors is for the base station STA1 to first select the singular vector corresponding to the smallest singular value below the threshold corresponding to the interference tolerance. The interference tolerance can be selected based on the supported modulation coding scheme (MCS) and can be indicated by the access point. n This indicates the number of vectors selected using this method. Depending on the configuration, N n The dimension is relatively large, and in some cases can be larger than the actual channel dimension. For example, in a configuration where the access point has 8 antennas and the base station STA1 has 2 antennas, the dimension of the zero space is a maximum of 6, while the channel dimension is a maximum of 2. Therefore, it is important to reduce and select the dimensional space to be fed back. In other configurations, for example, when the number of antennas is the same for the access point and the base station STA1, N n The value becomes 0, in which case interference protection may be difficult or impossible.

[0028] Traditionally, the number of vectors to be fed back is selected by the access point requiring the feedback and is related to the number of spatial streams available in the communication between each access point and base station. In the case of cooperative beamforming, several additional conditions come into play.

[0029] In the case of an interfering link, the access point (access point oAP1) is N (o,1) req The number of feedback vectors, expressed as [expression], is requested from base station STA1. To do this, the following conditions must be met: i) As shown in the operating conditions, further N (o,1) iofs The number of safeguardable interference directions is greater than or equal to the maximum number of interference directions indicated by, and further N as indicated by the function. (o,1) ns The maximum applicable zero space dimension is less than or equal to the dimension expressed by [the specified method]. ii)N (o,1) req To ensure sufficient flexibility in the precoder design of access point oAP1, the number of spatial streams available during communication between access point oAP1 and base station oSTA1 is N. (o,1) SS,o,1 It must be the above. (o,1) SS,o,1 This may not be known before training. Therefore, a value corresponding to the maximum number of spatial streams limited by the operating mode, function, or modulation can be used instead. This number can also be used, for example, in a null data packet (NDP) announcement, where access point oAP1 requests feedback from base station oSTA1. (o,1) C, It can correspond to values

[0030] Alternatively, the access point could be, for example, N (o,1) req,min =max(N (o,1) SS,o,1 ,N (o,1) iof ) and N (o,1)req,min =N (o,1) ns etc., only notifies the upper and lower limits of the interval in which the number of feedback vectors should be included. On the other hand, in order to be completely protected from interference, the base station STA1 needs to calculate the number of directions in which the interference level should be controlled by the access point oAP1. This number is further N int. is referred to as.

[0031] Furthermore, N int should correspond to the number of spatial streams received by the base station STA1 from the access point AP1. However, similar to the description in item ii) above, only the upper limit of this value may be known. This upper limit value is the N 1 c,1 (for example, in the null data packet announcement when the announcement has already been sent), or is obtained by internally calculating an estimated value based on the operating mode, function, and / or modulation.

[0032] The influence on the feedback to the access point oAP1 is as follows. The feedback dimensions to the access point oAP1 and the access point AP1 from the base station STA1 are N n,1 (the number of singular vectors of the channel matrix between the access point oAP1 - base station STA1 corresponding to singular values equal to zero or less than the threshold), N (o,1) req and N int,1 depends on. a) N (o,1) req ≧N int,1 and N n is as follows, this is an ideal case, and the number of selection vectors N I,1 fed back by the base station STA1 is equal to N (o,1) req b) N (o,1) req >N n,1 In the case of, the selection corresponds to N n,1 singular vectors of directions less than the interference threshold, N n,1This consists of an indication and padding (if any) up to the required size. An indication may be sent to both access point oAP1 and access point AP1 indicating that the interference conditions may not be met as desired. Alternatively, the minimum N (o,1) req Individual singular vectors can be fed back, but in this case, a corresponding SNR value must exist. c)N (o,1) req,max or N (o,1) req But strictly speaking, N n,1 If the value is smaller, zero space reduction may be performed. There are several ways to do this, including the following examples. c1) For example, sort the singular vectors in descending order, and the last N (o,1) req Methods that do not depend on the communication channel, such as methods for selecting individual values. c2) Alternatively, a correlation-based method in which the base station selects a singular vector that has the best channel direction and the highest correlation. This ensures that the direction that base station STA1 needs to primarily use for communication with access point AP1 is also the direction that is best protected from interference.

[0033] The impact on the feedback to access point AP1 is as follows: a)N n,1 If <1, interference mitigation may not be possible, and such an indication should be sent. b)i)N (o,1) req ≤N int,1 or N (o,1) req,min ≤N int,1 Or ii) N int,1 ≥N n,1 However, if it is strictly greater than 1, interference protection is possible, but the number of streams may be less than the desired number. In this case, feedback from base station STA1 to access point AP1 must indicate that operation with the desired number of spatial streams may not be achievable.

[0034] The behavior and associated feedback in this case further depend on the type of adjustment. For example, if access point oAP1 has channel access rights or has a scheduled service period and opportunistically allows access point AP1, access point AP1 will need to apply interference constraints, but may need to reduce the number of streams used for communication with base station STA1.

[0035] Therefore, as part of sounding feedback, the access point will provide the base station within its BSS with the maximum number of nulling directions allowed by the channel and the N requested by the other access point (i.e., the one controlling the interference). req We need to request a value that represents the minimum between N and N. nd It is called that. Alternatively, the base station is value N nd However, in some cases, it may suffice to indicate whether the number of spatial streams is less than or equal to the number of streams that will be sounded between the access point and base station, or that will be used for downlink communication between the access point and base station within its own BSS.

[0036] In the sequential sounding method, depending on the order in which the access points perform the sounding, some access points may have more information than others. For example, if access point oAP1 performs the sounding after access point AP1, access point oAP1 will already have more information than access point N 1 nd It recognizes this and can adapt the required parameters accordingly (for example, N (o,1) c ). Also, if one of the access points acts as the master access point that coordinates the coordinated beamforming sounding, these parameters are N req -N int This could be decided during an adjustment phase where trade-offs are identified.

[0037] Figure 3 shows another detailed diagram of the cooperative beamforming scenario, illustrating the parameters involved, the conditions regarding feedback, and the relationships between the requested feedback parameters. The number of requested feedback dimensions from access point oAP1 to base station oSTA1 is N. (o,1) c This is the number of effective spatial streams N that should be used for communication between these two base stations. (o,1) SS That concludes the explanation. Number of request feedback directions N from access point AP1 to base station STA1. (1) C (Number of valid streams N) (1) SS A similar relationship exists for (exceeding) channel H. (o,1) Dimension N of zero space of 1 (o,1) n This is further indicated along with the case where the request feedback from access point oAP1 is less than or equal to this value. However, the latter relationship is merely illustrative, and in reality, access point oAP1 cannot know whether this relationship holds or not, requiring further steps to communicate this information as described herein.

[0038] Parameter N (o,1) req , N (o,1) n , N (1) C , and N (o,1) C The interaction between these two factors, and the actions required when the above relationship is satisfied, can be summarized as follows:

[0039] [Table 3]

[0040] Figure 4 shows a first embodiment of the communication method according to this disclosure. According to this embodiment, the sounding flow shown in Figure 4 is N req =N nThis can be used when zero-space reduction is performed based on a method independent of the communication channel. The new value N req (Define the "number of required feedback vectors") or limit value (N) req,min ,N req,max The range of requests for feedback vectors (defined as "the range of requests for feedback vectors") is announced, for example, within the null data packet announcement frames 10,15 that initiate the sounding procedure. (o,1) c (The number of feedback vectors that access point oAP1 requests from base station oSTA1) is matrix H (o,1) o,1 It is necessary to select all singular vectors corresponding to the nucleus so that they can be obtained at access point oAP1. This is V SEL,o,1 In addition to the reconstruction of 1, V SEL,o,1 o,1 This may be relevant when obtaining the final steering matrix using partial channel information in the system.

[0041] Following the null data packet announcement 10, a training data unit (null data packet) 11 is transmitted to base station STA1 and base station oSTA1. As a result, both base stations receive channel H from access point AP1. 1 1 and H 1 o,1The number of training units in the null data packet 11 can be selected so that all transmitting antennas of access point AP1 are sounded, but must not exceed the maximum number of training fields that either of the two base stations (base station STA1 and base station oSTA1) can handle, as indicated in each function field. Therefore, access point AP1 needs to know the functions of base station oSTA1, which are not in its BSS. Alternatively, access point AP1 may send a null data packet corresponding to the maximum number of training fields that base station STA1 can handle, preventing oSTA, which cannot handle the number of training fields required at each sounding stage, from participating in the cooperative beamforming scenario. One option for collecting feedback is to use trigger frames 12, 17 or polling frames (not shown) as shown in Figure 4. Trigger frames 12 and 17 trigger base stations STA1 and oSTA1 to send feedback (BF Fbck) 13 ("third beamforming feedback"), 14 ("fourth beamforming feedback"), 18 ("another third beamforming feedback"), and 19 ("another fourth beamforming feedback") in the format shown in null data packet announcements 10 and 15.

[0042] Generally, each feedback vector corresponds to one or more singular vectors in the channel matrix between access point AP1 and base station oSTA1, and between access point oAP1 and base station STA1. The number of feedback vectors in BF feedback is generally less than or equal to the maximum number of requests or the range of requests.

[0043] In the sequential method shown in Figure 4, sounding at access point oAP1 is performed after the access point sounding and consists of similar steps. Therefore, after the null data packet announcement 15, null data packets 16 are also sent to base stations STA1 and oSTA1, and both base stations each receive channel H from access point oAP1.o,1 1 and H o,1 o,1 We estimate this.

[0044] For the first access point performing the sounding (for example, access point AP1 in Figure 4), the value N was set during the feedback collection phase. nd This value is not available. This value can be requested after sounding, for example, when a transmission opportunity (TXOP) for communication between access point AP1 and base station STA1 is obtained. Generally, base station STA1's N nd This can be configured as follows: i) the number of directions corresponding to power below a threshold in the channel between access point oAP1 and base station STA1, or ii) the number of feedback vectors that access point oAP1 requests from base station STA1, or iii) the minimum value between i) and ii).

[0045] N req <N n In this case, if a correlation criterion is used for dimensionality reduction, each base station will have both channel estimates (for example, in the case of base station STA1, H 1 1 and H o,1 The sounding flow needs to be adapted so that 1) can be obtained. When using a sounding flow as shown in Figure 4, only base station STA1 has enough information to send feedback based on the reduced zero space to access point oAP1. To enable base station oSTA1 to also perform reduction, an additional feedback round from access point AP1 to base station oSTA1 is required, increasing overhead. Figure 5 shows a second embodiment of the communication scheme according to this disclosure in which an adaptive sounding flow for reduced zero space is used.

[0046] According to the sounding scheme shown in Figure 5, firstly, training units 11 and 16 are transmitted so that all participating base stations can estimate the channels from both access points. This is followed by a feedback round. This feedback round consists of two access points, AP1 and oAP1, which request feedback from the STA1 and oSTA1 base stations that participated in the training. After each feedback request (either contained in NDP-A frames 10 and 15 or indicated by the transmission of training units 11 and 16), the designated base station transmits feedback (BF Fbck) 13, 14 and 18 and 19 in the format shown in the NDP-A frames 10 and 15.

[0047] If one of the access points acts as the master access point, all sound configuration information can be transmitted from the master access point (e.g., access point AP1) within a single NDP-A frame (e.g., NDP-A frame 10). In this case, the second NDP-A block 15 (shown by the dashed line) may be omitted.

[0048] In some specific cases, such as when base stations STA1 and oSTA1 each use only one stream for communication with access points AP1 and oAP1, it can be shown that sufficient performance can be obtained by simply applying the feedback vector V that base stations oSTA1 and STA1 each provide as the steering vector for access points AP1 and oAP1, corresponding to one of the null directions. In this case, the feedback from base station STA1 to access point AP1 and from base station oSTA1 to access point oAP1 can be omitted or reduced, thereby further reducing overhead. As reduced feedback, base station oSTA1 may need to transmit an SNR value to ensure it is in the high SNR region. In that case, the steering matrix obtained only from the null direction (singular vectors corresponding to null or less than the threshold singular value) fed back from base station STA1 will perform sufficiently well.

[0049] For oSTA, it is also possible to completely separate the sounding phase. In this case, an advantage is that oSTA does not need to be able to process trigger frames. Figure 6 shows a third embodiment of the communication scheme of the present disclosure in which simple non-trigger-based (non-TB) feedback is performed. In the scheme shown in Figure 6, base station oSTA1 and base station STA1 are required to provide their beamforming feedback information within a predetermined interval (e.g., Short InterFrame Space interval (SIFS)) from the end of NDP. The scheme shown in Figure 6 can also be used when implementing a steering matrix based only on null-direction feedback.

[0050] The communication schemes shown in Figures 4 to 6 suggest that the communication direction is calculated in the zero space of the interference channel based only on partial information (V matrix and SNR value) regarding the direct communication channel. An example of this implementation will be described later. This may not be sufficiently accurate, especially when the SNR is low. Figure 7 shows a fourth embodiment of the communication scheme according to this disclosure, in which an improved sounding flow is applied to overcome this problem and the shortcomings of incomplete CSI information during sequential sounding.

[0051] An essential part of this operation is the transmission of nNDP (null NDP; hereinafter also referred to as "modified third feedback information" and "modified fourth feedback information") 20, 21. These are feedback V that base station oSTA1 and base station STA1 provide, respectively. (SEL) This is a frame transmitted using a steering matrix calculated based on a matrix. The number of training fields in the subsequent nNDP data units (also referred to herein as “modified third training data” and “modified fourth training data”)22,23 is N ns The following is true, and this can be less than the number of transmitting antennas. Therefore, the number of feedback lines shown in nNDP-A frames 20,21 is also N ns The following conditions must be met, resulting in fewer requirements than in the case of normal sounding (for example, as shown in Figures 4 and 5). Also, since interference protection is already applied, the two nNDP22,23 can transmit simultaneously by both access points. However, in this case, the lengths of the two nNDP22,23 must be the same, which means that the number of training fields (e.g., ELTF (HE, EHT LTF, etc., Extended Long Training Field (LTF))) is N 1 ns and N (o,1) nsThis means that it must be less than or equal to the minimum value between these two values. These two values ​​are interchangeable between access points before the sounding phase and are not subject to frequent changes. The number of columns of the feedback (BF Fbck; also referred to herein as the "modified third beamforming feedback" and the "modified fourth beamforming feedback") 25,26 from base station STA1 and base station oSTA1 to access point AP1 and access point oAP1, respectively, can be requested within NDP-A frames 10,15 to initiate coordinated beamforming sounding. In this case, nNDP-A frames 20 (and 21) are merely triggers to initiate and coordinate the transmission of null data packets.

[0052] The blocks shown by dashed lines may be optionally present in this scheme. For example, nNDP-A21 may be omitted if one of the access points acts as the master access point or coordinator in a coordinated beamforming scheme. Another optional case is when an access point that has gained access to the medium may be allowed to initiate this modified training phase. This is particularly important if the initial NDP-A frames 10 and 15 contain the required feedback request information. In the scheme shown in Figure 7, the base station sends NNDP-A21 to each of the access points to which it is associated. nd You do not need to send any information.

[0053] Furthermore, the number of columns in the required feedback matrix can be reduced to the number of spatial streams, as recommended by the non-access point base stations of base station STA1 and base station oSTA1. This is because, in this case, the access point does not need to perform any additional operations within the feedback space.

[0054] Blocks indicated by dashed lines can be omitted depending on the implementation. For example, feedback 14 from base station oSTA1 to access point AP1 and feedback 19 from base station STA1 to access point oAP1 are required in the first two stages, but feedback from each base station itself (i.e., feedback within each access point's BSS) is optional. The advantage of omitting this additional feedback is that the sounding method can be executed without trigger frames 12 and 17, which further reduces training time.

[0055] Figure 8 shows a flowchart of one embodiment of the communication method 100 for access points (access point AP1 and access point oAP1) according to this disclosure. As an example, the steps of the communication method are shown for access point oAP1, but the same steps are generally performed by access point AP1.

[0056] Before initiating the sounding procedure, each access point performing coordinated beamforming must have information about both the base stations in its own BSS and the base stations in the oBSS that it needs to protect from interference. For example, access point oAP1 must have the following information about base station STA1: • Identification information for specifying base station STA1 ·N req The maximum number of spatial streams that base station STA1 can process, used in the calculation. • The bandwidth on which base station STA1 is available and on which sounding should be performed, in whole or in part. • Whether puncturing is possible. In other words, whether base station STA1 can participate in coordinated beamforming and sounding even if part of the channel becomes unavailable during transmission. • Whether a compressed long training field (LTF) is available at base station STA1 (this could be a deciding factor in selecting the format of the training units used in the sounding). • Known as Beamformee STS, this represents the maximum number of spatial streams that can be received within the sounding, which is the basis for determining the LTF (Longest Stream Frequency) in a null data packet (and can be calculated based on this). • Maximum dimension of feedback that a base station can provide to an access point that does not exchange data (or in a coordinated beamforming scenario)

[0057] This information is required in addition to the information the access point has about its own base station, particularly regarding the number of spatial streams, bandwidth, and channels subject to puncturing. Identification information and operating bandwidth are exchanged between the two access points, but the remaining information can be obtained by access point oAP1 directly from access point AP1 or base station STA1. When transmitting null data packets, the maximum number of Long Training Fields (LTFs) must not exceed the maximum number of Beamformee STS notified by both STAs and oSTA.

[0058] In the first step 101, the identification information of base station STA1 is calculated. This can be obtained from access point AP1 through information exchange such as coordinated beamforming settings, or it can be announced by base station STA1 itself. In the second step 102, the functions and communication requirements of base station STA1 are calculated from message exchange with base station STA1 or access point AP1. In the third step 103, the sounding parameters are calculated. This includes the feedback type and format (CBF, SU, MU), and the size Nc of the feedback from base station oSTA1. (o,1) , N (o,1) nd , and N that is fed back from base station STA1 1 reqThis includes. The cooperative beamforming format refers to the format required for the cooperative beamforming scheme. The cooperative beamforming format needs to indicate the number of feedback vectors that base station STA1 provides feedback for, for example, if the number of feedback vectors that base station STA1 provides feedback for corresponds to the zero-space direction or nucleus of the channel matrix between access point oAP1 and base station STA1. Also, if compression of the feedback vectors is used, it needs to include as part of the feedback that base station STA1 provides feedback on which compression parameters can be used (e.g., the number of givens angles, the value of the diagonal exponential used to create the matrix for each givens rotation, and whether the SNR value is averaged across subcarriers). In the fourth step 104, sounding in the interference (and optionally data) direction is initiated by transmitting NDP-A to base station STA1 (and optionally base station oSTA1). In the fifth step 105, a training data unit with a training field based on the calculated function is transmitted. In the sixth step 106, based on the received compression angle, V 1,SEL o,1 (and V 1,SEL Reconstruct (1).

[0059] Next, we distinguish between different cases. In the first case, in step 107, N (o,1) nd Check if it is available. If it is not available, proceed to step 108 to select N from future TXOP or soundings. (o,1) nd Calculate N. Then proceed to step 109. In step 107, N (o,1) nd Step 109 is also performed if it is determined that it is available.

[0060] In step 109, N (o,1) nd <N (o,1) c Check whether this is the case. If yes, in step 110, according to the communication channel conditions, N ss Apply V1,SEL o,1 , V 1,SEL 1, N ss Q1 is calculated based on the following. If No, in step 111, N is calculated according to the interference conditions and communication channel. ss Apply V 1,SEL o,1 , V 1,SEL 1, N ss Q1 is calculated based on this. Adaptation to the communication channel means that the number of spatial streams used can be reduced in response to potential residual interference due to the fact that not all desired directions can be protected by other access points.

[0061] In another case, in step 112, N (o,1) I <N (o,1) req Check whether the answer is yes or no. If yes, perform step 110. If no, perform step 111.

[0062] The steering matrix can be calculated from the feedback vector, for example, as shown in Figures 9A and 9B. Figure 9A shows a flowchart of a first embodiment of the method 200 for constructing the steering matrix according to the present disclosure, based on a second singular value decomposition. In the first step 201, from the beamforming feedback information, V (o,1) o,1 and V (SEL,o,1) Reconstruct 1, N (o,1) nd The second step 202 is performed using the partial CSI of base station oSTA1 to calculate the second singular value decomposition (V (o,1),H o,1 V (SEL,o,1) 1=U t Σ t- V H t ). In the third step 203, the number of effective spatial streams N used for downlink communication between access point oAP1 and base station oSTA1. eSS =min(N (o,1) nd ,N C,o,1) is calculated. In the fourth step 204, the steering matrix is ​​Q=V SEL,o,1 1V t (1:N eSS )Σ 1 / 2 t (1:N eSS ,1:N eSS ) will be constructed as follows.

[0063] Figure 9B shows a flowchart of a second embodiment of the method 300 for constructing a steering matrix according to the present disclosure from zero-space feedback. In the first step 301, V (o,1) o,1 and V (SEL,o,1) Reconstruct 1, N (o,1) nd Calculate N. In the second step 302, eSS =min(N (o,1) nd ,N C,o,1 ) is calculated. In the third step 303, V (o,1) (o,1) Σ (o,1) o,1 The V with the highest correlation is (SEL,o,1) 1 of N eSS A vector is selected.

[0064] When beamforming feedback is based on the kernel of the channel matrix between access point oAP1 and base station STA1, embodiments of the method shown in Figures 9A and 9B are still available. However, access point oAP1 must perform preprocessing to obtain the zero-space matrix from the kernel of the channel matrix. More specifically, from beamforming feedback operation V (SEL,o,1) After reconstructing the matrix, V (SEL,o,1) A group of vectors W that are orthogonal to 1. (SEL,o,1) Find 1. The subsequent steps (i.e., steps 202-204 in Figure 9A and steps 302 and 303 in Figure 9B) are V (SEL,o,1) W instead of 1 (SEL,o,1) This is performed using 1. The two spaces, nuclear space and zero space, are complementary to each other, and the method of obtaining one space from the other is generally known in this field.

[0065] Figure 10 shows a flowchart of one embodiment of the communication method 400 for base stations (base station STA1 and base station oSTA1) according to this disclosure. As an example, the steps of the communication method of base station STA1 for calculating feedback to access point oAP1 are shown, but base station oSTA1 for calculating feedback to access point oAP1 generally performs the same steps. This process can be combined with the estimation of the channel from access point AP1 and the calculation of feedback to be transmitted to access point AP1.

[0066] In the first step 401, the NDP-A transmitted from an access point outside of its own BSS (access point oAP1) is decoded, enabling the establishment of cooperative beamforming. In the second step 402, the cooperative beamforming sounding parameters (feedback format, feedback size N to access point oAP1) are set. (o,1) req ) is calculated. In the third stage 403, H is calculated from the null data packet. (o,1) We estimate 1. In the fourth stage 404, we perform singular value decomposition and determine the vectors and vector number N corresponding to singular values ​​smaller than the defined threshold. (n,1) Calculate.

[0067] Subsequently, different cases are distinguished. In the first case, in step 405, N n It is checked whether <1. If No, in step 406 it is detected that interference protection is not possible. If Yes, in step 407 it is checked whether N req <N n Check if this is the case. If yes, in step 408, shrink the subspace and N I =N req Calculate and compress the number of vectors. If No, in step 409, N I =N n Select and compress individual vectors.

[0068] In the second case, in step 410, N (o,1) nd =min(N (o,1) req ,N (o,1) n Set ) in step 411. Then, in step 411, N (1) C Check if it is available. If yes, then N int to N (1) C If assigned to, this method proceeds to step 412. If No, then in step 413, N int The method estimates N and proceeds to step 412. In step 412, int <N (o,1) nd Check whether this is the case. If No, then in step 414, regardless of the NDP-A request, N (o,1) nd It is necessary to report this. If yes, in step 415, based on the NDP-A request from access point AP1, (o,1) nd I will report this.

[0069] Figure 11 is a schematic diagram showing one embodiment of a communication system according to one aspect of the present disclosure. This communication system includes a first communication device AP1 that communicates with one or more third communication devices STA1, and a second communication device oAP1 that communicates with one or more fourth communication devices oSTA1. According to the present disclosure, the two access points AP1 and oAP1 are located within an overlapping set of basic services and perform partially or fully overlapping downlink transmissions to the associated base station(s) of STA1 and oSTA1, respectively. At the same time, interference to other base stations involved in the cooperative communication scheme is controlled, suppressed, or reduced.

[0070] Each communication device comprises circuits 50, 51, 52, and 53 configured to perform specific operations. These circuits can be implemented as hardware and / or software, i.e., by their respective processors or computers, or by dedicated units or components. For example, each programmed processor can constitute each of the circuits 50, 51, 52, and 53.

[0071] Figure 12 shows a flowchart of another embodiment of the access point communication method 500 according to this disclosure (also referred to as the "first communication method") which can be performed by access point AP1 and access point oAP1. The method when performed by access point AP1 will be described below.

[0072] In the first (optional) step 501, the functionality and communication requirements of base station oSTA1, which is configured to communicate with access point oAP1 in another basic service set, are obtained. In the second step 502, feedback request information is sent to base station oSTA1 (and optionally base station STA1). This feedback request information relates to the feedback to be fed back from base station oSTA1 (and optionally base station STA1) and includes the requested feedback format and the number of requested feedback vectors or the range of requested feedback vectors. In the third step 503, training data is sent to base station oSTA1 (and optionally base station STA1). In the fourth step 504, beamforming feedback, including the number of feedback vectors, is received from base station oSTA1 (and optionally base station STA1). In the fifth step 505, a steering matrix is ​​calculated for communicating with base station STA1 using beamforming, based on the received beamforming feedback. In the sixth step 506, access point AP1 communicates with base station STA1 using the calculated steering matrix.

[0073] Figure 13 is a flowchart showing another embodiment of the base station communication method 600 according to this disclosure, which can be performed by base station STA1 and base station oSTA1. The method when performed by base station oSTA1 is described below.

[0074] In the first step 601, feedback request information is received from access point AP1, which is configured to communicate with base station STA1 in another basic service set. In the second step 602, training data is received from access point AP1 (first communication device). In the third step 603, channel information is estimated based on the received training data. In the fourth step 604, based on the estimated channel information, the feedback vector and the number of feedback vectors corresponding to singular values ​​smaller than the interference threshold are calculated. In the fifth step 605, beamforming feedback including the calculated feedback vector is sent to access point AP1 in request feedback format.

[0075] In summary, this disclosure provides several embodiments relating to an access point (described in terms of an access point oAP1). One or more of these embodiments may be used in the communication devices and communication methods provided by this disclosure. Access point oAP1 can determine the function and identification of base stations within different BSSs (base station STA1) that are eligible to participate in the cooperative beamforming scheme, calculate the sounding parameters of the training unit to transmit to base station STA1, and request the cooperative beamforming feedback format from base station STA1. • Access point oAP1 performs sounding to its BSS base station (base station oSTA1). As part of the feedback, the number of null directions for channels from different BSSs is provided, but participation in the coordinated beamforming scheme (access point AP1) to base station oSTA1 is required. Access point oAP1 requests Vs from base station STA1 for SNR below the threshold, or requests indication of the SNR value corresponding to the feedback Vs. The number of columns in the matrix fed back from base station STA1 is equal to or greater than the number of spatial streams used by access point oAP1 for base station oSTA1, or the maximum number of spatial streams. • The number of columns fed back from base station STA1 is greater than or equal to the number of interference dimensions controllable by access point AP1, and N ns The following is • The number of streams fed back from base station STA1 is equal to or greater than the number of spatial streams used by access point AP1 toward base station STA1, or the maximum number of spatial streams, in the case of cooperation. The number of columns for which feedback is requested in the form of a matrix from base station oSTA1 may be greater than the maximum number of spatial streams that can actually be used in communication in order to ensure sufficient degrees of freedom. The number of columns is limited by the capabilities of the base station oSTA1. For example, this includes the number of spatial streams that can be processed during the sounding procedure, bandwidth information, whether channel puncture can be handled, whether trigger-based sounding can be handled, and the available LTF types (e.g., 2x or 4x). These functions are communicated from base station oSTA1 to access point AP1 directly or indirectly via access point oAP1. The number of columns is indicated in the null data packet announcement frame. This frame contains at least one base station information field relating to a base station outside of access point AP1's BSS. This corresponds to the identifier of base station oSTA1 and is known in both access point AP1's BSS and access point oAP1's BSS. The number of LTFs used during the transmission of training data units (null data packets) must not exceed the maximum number of spatial streams available during the sounding procedure, as notified by the functions of each base station, for both base station STA1 and base station oSTA1. Apply the zero space, and the zero space and V o,1o,1 We perform a second singular value decomposition of and in the final singular value decomposition N nd Find the steering wheel of dimensions ·V SEL,o,1 From 1 to V (o,1) o,1 The direction with the greatest correlation to N nd The vector is fed back to access point AP1 by base station STA1. • Base station STA1 is required to provide feedback to access point AP1 of a beamforming matrix having a number of columns corresponding to the number of receiving antennas actually used by base station STA1. • Subsequent sounding is performed by base station oSTA1 in a space calculated from the vector fed back from base station STA1. This can be done simultaneously with the subsequent sounding performed by access point AP1 on base station STA1 in a space calculated from the vector fed back from base station oSTA1 to access point AP1.

[0076] Generally, each communication device can be implemented by individual devices or circuits that perform its functions, such as processors, processing circuits, computers, or dedicated hardware. Alternatively, a common device or circuit, such as a common processor or computer, may implement the various functions of the device. Or, individual devices or elements may be used together to constitute the circuit.

[0077] Accordingly, the foregoing description merely illustrates and describes exemplary embodiments of the present disclosure. As those skilled in the art will understand, the present disclosure may be implemented in other specific forms without departing from its spirit or essential features. Accordingly, the disclosure is intended to be illustrative and not to limit the scope of the disclosure or the other claims. The present disclosure partially defines the scope of the terms of the above claims, including any readily identifiable modifications of the teachings described herein, and does not attribute any inventive subject matter to the public.

[0078] In a claim, the term “comprising” does not necessarily exclude the presence of other elements or steps, and the indefinite articles “a” or “an” do not exclude the plural. A single element or other device may satisfy the functions of multiple items described in a claim. The mere fact that certain measures are described in different dependent claims does not indicate that a combination of these measures cannot be advantageously utilized.

[0079] To the extent that an embodiment of the disclosure is described as being implemented by a software-controlled data processing device, it should be understood that a non-transient, machine-readable medium, such as an optical disk, magnetic disk, or semiconductor memory, that holds such software is also considered to constitute an embodiment of the disclosure. Furthermore, such software may be distributed in other forms, such as via the Internet or other wired or wireless communication systems.

[0080] The elements of the disclosed devices, apparatus, and systems can be implemented by corresponding hardware and / or software elements, such as appropriate circuits or circuit sections. A circuit is a structural assembly of electronic components, including conventional circuit elements, application-specific integrated circuits (ASICs), standard integrated circuits, application-specific standard products (ASSPs), and field-programmable gate arrays (FPGAs). A circuit also includes a central processing unit (CPU), a graphics processing unit (GPU), and a microprocessor, which are programmed or configured according to software code. The circuit does not contain pure software, but it does contain the hardware that runs the software. The circuit or circuit section can be implemented by a single device or unit, multiple devices or units, chipsets, or processors.

[0081] The following is a list of further embodiments of the disclosed subject matter. (Embodiment 1) A first communication device configured to communicate with one or more third communication devices within its own basic service set, A fourth feedback request information, which includes a requested feedback format and a requested number of feedback vectors or a range of requested feedback vectors with respect to feedback to be provided by the fourth communication device, is transmitted to the fourth communication device, which is configured to communicate with a second communication device in another basic service set. The fourth training data is transmitted to at least the fourth communication device. A fourth beamforming feedback, including the number of feedback vectors corresponding to the requested feedback format, is received from the fourth communication device. Based on the received fourth beamforming feedback, a steering matrix is ​​calculated for communicating with the one or more third communication devices using beamforming. The steering matrix calculated above is used to communicate with the one or more third communication devices. Circuit configured in such a way Equipped with The first communication device. (Embodiment 2) The first communication device described in Embodiment 1, The aforementioned circuit is Third feedback request information, which includes a requested feedback format and a requested number of feedback vectors or a range of requested feedback vectors with respect to the feedback that the third communication device provides, and / or third training data, is transmitted to one or more third communication devices. A third beamforming feedback is received from one or more third communication devices. The system is configured to calculate the steering matrix based on the third and fourth beamforming feedback received from the one or more third and fourth communication devices. The first communication device. (Embodiment 3) The first communication device described in Embodiment 2, The circuit is configured to include in the third feedback request information an indication of the number of singular vectors in the channel matrix between the second and third communication devices, corresponding to the number of requested feedback vectors for the one or more third communication devices to provide feedback, and / or an indication of the number of singular vectors in the channel matrix between the second and third communication devices, corresponding to singular values ​​below a threshold, and / or information regarding whether the number of singular vectors thus calculated exceeds the number of feedback vectors requested by the one or more third communication devices. The first communication device. (Embodiment 4) A first communication device as described in any one of the prior embodiments, The circuit is configured to receive the fourth beamforming feedback from the fourth communication device in response to a trigger transmitted to the fourth communication device or within an interframe spatial time interval from the end of the transmitted training data. The first communication device. (Embodiment 5) A first communication device as described in any one of the prior embodiments, The aforementioned circuit is The number of request feedback vectors included in the fourth feedback request information is The number of directions for which the first communication device can control interference is greater than or equal to the maximum number of directions for which it can control interference, and / or The first communication device is subject to the maximum zero spatial dimension, and / or The number of spatial streams used for communication between the first communication device and the third communication device shall be greater than or equal to the number of spatial streams used for communication between the first communication device and the third communication device, and / or The first communication device has a number of feedback vectors equal to or greater than the number requested by the third communication device, and / or The second communication device has a number of feedback vectors that it requests from the fourth communication device that is equal to or greater than the number of feedback vectors it requests from the fourth communication device. The number of spatial streams used for data communication between the second communication device and the fourth communication device shall be greater than or equal to the number of spatial streams used for data communication between the second communication device and the fourth communication device, and / or As part of the beamforming feedback, the feedback dimension is less than or equal to the maximum feedback dimension that can be fed back to the first communication device. It is configured to calculate The first communication device. (Embodiment 6) A first communication device as described in any one of the prior embodiments, The circuit is configured to transmit the feedback request information as part of a null data packet announcement. The first communication device. (Embodiment 7) A first communication device as described in any one of the prior embodiments, The circuit is configured to send a trigger to one or more third and / or fourth communication devices that are requesting beamforming feedback immediately after the first communication device has transmitted the feedback request information and the training data, or after both the first and second communication devices have successively transmitted their own feedback request information and their own training data. The first communication device. (Embodiment 8) A first communication device as described in any one of the prior embodiments, The aforementioned circuit is The modified third feedback request information is transmitted to one or more third communication devices. The corrected third training data is transmitted to the one or more third communication devices using the calculated steering matrix. The modified third beamforming feedback is received from the one or more third communication devices. Based on the received modified third beamforming feedback, a steering matrix is ​​calculated for communicating with the one or more third communication devices using the modified beamforming. The modified steering matrix is ​​used to communicate with the one or more third communication devices. It is configured to The first communication device. (Embodiment 9) The first communication device described in Embodiment 8, The aforementioned circuit is The third and fourth beamforming matrices are calculated from the third and fourth beamforming feedbacks described above. The first beamforming matrix is ​​obtained by multiplying the third and fourth beamforming matrices calculated above. A second beamforming matrix is ​​obtained by performing singular value decomposition on the first beamforming matrix. The fourth beamforming matrix is ​​given the second beamforming matrix, or the second beamforming matrix is ​​given N ss The steering matrix is ​​calculated by multiplying it by a second beamforming matrix, whose array shape has been modified, corresponding to the largest singular value. It is configured in such a way, N ssThis represents the number of spatial streams used for data communication from the first communication device to the one or more third communication devices. The first communication device. (Embodiment 10) The first communication device described in Embodiment 8, The aforementioned circuit is A fourth beamforming matrix is ​​calculated from the fourth beamforming feedback described above. As the steering matrix, the fourth beamforming matrix calculated above is used by optionally adjusting the power. It is configured to The first communication device. (Embodiment 11) The first communication device described in Embodiment 8, The aforementioned circuit is Based on the third and fourth beamforming feedback, the third and fourth beamforming matrices are calculated. The N corresponding to the vector with the highest correlation to the fourth beamforming matrix. ss Select n columns from the aforementioned third beamforming matrix. It is configured in such a way, N ss This represents the number of spatial streams used for data communication from the first communication device to the one or more third communication devices. The first communication device. (Embodiment 12) A first communication device as described in any one of the prior embodiments, The circuit is configured to transmit the modified fourth training data from the second communication device to the fourth communication device, and at the same time transmit the modified third training data to one or more third communication devices. The training data is transmitted from the second communication device using a steering matrix calculated from the third beamforming feedback, which the second communication device requests from one or more third communication devices. The first communication device. (Embodiment 13) A first communication device as described in any one of the prior embodiments, The aforementioned circuit is The functions and communication requirements of the fourth communication device are as follows: Identification information for specifying the fourth communication device, The maximum number of spatial streams that the fourth communication device can process, used to calculate the number of requested feedback vectors or the range of requested feedback vectors, The bandwidth in which the fourth communication device can be used, within or in part of the bandwidth, where sounding should be performed, Information regarding whether puncture is possible. Information regarding whether the fourth communication device can use compressed LTF (Long Training Field), The maximum number of spatial streams that can be received during the aforementioned sounding, and The maximum support feedback dimension for the fourth beamforming feedback described above. It is configured to obtain one or more of the following. The first communication device. (Embodiment 14) A first communication device as described in any one of the prior embodiments, The aforementioned request feedback format is: An indicator showing whether the feedback vector corresponds to the core or zero space of the channel between the first communication device and the fourth communication device, An indicator showing whether the aforementioned feedback vector is compressed or not, One or more compression parameters when the feedback vector is compressed, and Information regarding whether the average signal-to-noise value is included as part of the fourth beamforming feedback. Includes one or more of the following The first communication device. (Embodiment 15) A first communication device as described in any one of the prior embodiments, The circuit is part of the fourth beamforming feedback, The number of singular vectors in the channel matrix of the channel between the first communication device and the fourth communication device that corresponds to a singular value below a threshold, and which corresponds to the number of request feedback vectors, or which is within the range of the number indicated as part of the fourth feedback request information, or The number of singular vectors in the channel matrix of the channel between the first communication device and the fourth communication device, where the singular vectors correspond to all singular values ​​above a threshold, or to a number corresponding to the number of receiving antennas of the fourth communication device, or to a number corresponding to the maximum support feedback dimension for the fourth beamforming feedback. Configured to receive The first communication device. (Embodiment 16) A first communication device as described in any one of the prior embodiments, The circuit is configured to transmit third and / or fourth training data, which includes a number of training sequences that is less than or equal to the number included in the function of the third and / or fourth communication device. The first communication device. (Embodiment 17) A fourth communication device configured to communicate with a second communication device within its own basic service set, A fourth feedback request information, which includes a request feedback format and a number of request feedback vectors or a range of request feedback vectors, is received from a first communication device configured to communicate with one or more third communication devices in another basic service set, relating to feedback that the fourth communication device provides to the first communication device. The fourth training data is received from the first communication device. Based on the received fourth training data, channel information is estimated. A feedback vector corresponding to the singular vector of the channel between the first communication device and the fourth communication is calculated based on the estimated channel information. The fourth beamforming feedback, including the calculated feedback vector, is transmitted to the first communication device according to the requested feedback format. Circuit configured in such a way Equipped with The fourth communication device. (Embodiment 18) A fourth communication device as described in Embodiment 17, The circuit is configured to calculate the interference threshold based on an indication received from the first communication device, or based on the modulation coding scheme desired by the second communication device, or based on the modulation and coding scheme supported by the fourth communication device. The fourth communication device. (Embodiment 19) A fourth communication device according to any one of embodiments 17 to 18, The circuit is configured to include in the fourth beamforming feedback an indication indicating that the interference conditions may not be met (or cannot be fully met) if the calculated number of feedback vectors is smaller than the required number of feedback vectors or smaller than the range of numbers included in the feedback information. The fourth communication device. (Embodiment 20) A fourth communication device according to any one of embodiments 17 to 19, The circuit is configured to find a subset of feedback vectors to be fed back if the calculated number of feedback vectors is greater than the required number of feedback vectors, or exceeds the range of numbers included in the feedback information. The fourth communication device. (Embodiment 21) A fourth communication device as described in Embodiment 20, The fourth beamforming feedback includes a number of feedback vectors greater than the number of spatial streams available for data communication between the second and fourth communication devices. The fourth communication device. (Embodiment 22) A fourth communication device according to any one of embodiments 17 to 21, The aforementioned circuit is The calculated feedback vectors are arranged in descending order of the corresponding singular values, and the last feedback vector among them is included as a feedback vector in the transmitted fourth beamforming feedback, or The fourth communication device selects the calculated feedback vector that has the highest correlation with the best channel direction used for communication with the second communication device, and includes this feedback vector as a feedback vector in the transmitted fourth beamforming feedback. It is configured to The fourth communication device. (Embodiment 23) A fourth communication device according to any one of embodiments 17 to 22, The aforementioned circuit is The system receives additional fourth feedback request information and / or additional fourth training data from the second communication device. Another fourth beamforming feedback is sent to the second communication device. It is configured to The fourth communication device. (Embodiment 24) A fourth communication device according to any one of embodiments 17 to 23, The circuit, based on the calculated feedback vector, The number of requests or range of requests included in the fourth feedback request information, The number of requests or range of requests included in the feedback request information received from the second communication device, and Estimated number of spatial streams available for data communication between the fourth communication device and the second communication device. Configured to select the number of feedback vectors corresponding to one or more of the following. The fourth communication device. (Embodiment 25) A fourth communication device according to any one of embodiments 17 to 24, The aforementioned circuit is Information regarding whether the calculated number of singular vectors for the channel between the first communication device and the fourth communication device corresponding to a singular value smaller than the threshold or the number of requested feedback vectors included in the fourth feedback request information is smaller than the number of requests or range of requests included in the feedback request information received from the second communication device or an estimate of the number of spatial streams available for data communication between the fourth communication device and the second communication device. Configured to provide feedback to the second communication device. The fourth communication device. (Embodiment 26) A fourth communication device according to any one of embodiments 17 to 25, The circuit is configured to select the feedback vector from the singular vector of the channel matrix between the first communication device and the fourth communication device that corresponds to the singular value smaller than the threshold. The fourth communication device. (Embodiment 27) A fourth communication device according to any one of embodiments 17 to 26, The circuit is configured to select the feedback vector as the singular vector of the channel matrix between the first and fourth communication devices, corresponding to all singular values ​​greater than a threshold, or the number of singular vectors equal to the minimum value between the number of training fields in the training data transmitted by the first communication device and the number of receiving antennas of the fourth communication device. The fourth communication device. (Embodiment 28) A first communication method for a first communication device configured to communicate with one or more third communication devices within its own basic service set, A fourth feedback request information, which includes a requested feedback format and a requested number of feedback vectors or a range of requested feedback vectors with respect to the feedback that the fourth communication device provides, is transmitted to the fourth communication device. The fourth training data is transmitted to at least the fourth communication device. A fourth beamforming feedback, including the number of feedback vectors corresponding to the requested feedback format, is received from the fourth communication device. A steering matrix for communicating with the one or more third communication devices using beamforming is calculated based on the received fourth beamforming feedback. The steering matrix calculated above is used to communicate with the one or more third communication devices. The first method of communication. (Embodiment 29) A fourth communication method for a fourth communication device configured to communicate with a second communication device within its own basic service set, A fourth feedback request information, relating to feedback that the fourth communication device provides back to the first communication device, includes a request feedback format and a number of request feedback vectors or a range of request feedback vectors, which is received from a first communication device configured to communicate with one or more third communication devices in another basic service set. The fourth training data is received from the first communication device. Based on the received fourth training data, channel information is estimated. Based on the estimated channel information, a feedback vector corresponding to the singular vector of the channel between the first communication device and the fourth communication is calculated. The fourth beamforming feedback, including the calculated feedback vector, is transmitted to the first communication device according to the requested feedback format. The fourth method of communication. (Embodiment 30) A non-temporary computer-readable recording medium that stores a computer program product that, when executed by a processor, causes the method described in Embodiment 28 or 29 to be performed. (Embodiment 31) A computer program that, when executed on a computer, includes program code means that causes the computer to perform the steps of the method described in Embodiment 28 or 29.

Claims

1. A first communication device configured to communicate with one or more third communication devices within its own basic service set, A fourth feedback request information, which includes a requested feedback format and a requested number of feedback vectors or a range of requested feedback vectors with respect to feedback to be provided by the fourth communication device, is transmitted to the fourth communication device, which is configured to communicate with a second communication device in another basic service set. The fourth training data is transmitted to at least the fourth communication device. A fourth beamforming feedback, including the number of feedback vectors corresponding to the requested feedback format, is received from the fourth communication device. Based on the received fourth beamforming feedback, a steering matrix is ​​calculated for communicating with the one or more third communication devices using beamforming. The steering matrix calculated above is used to communicate with the one or more third communication devices. Circuit configured in such a way Equipped with The first communication device.

2. A first communication device according to claim 1, The aforementioned circuit is Third feedback request information, which includes a requested feedback format and a requested number of feedback vectors or a range of requested feedback vectors with respect to the feedback that the third communication device provides, and / or third training data, is transmitted to one or more third communication devices. A third beamforming feedback is received from one or more third communication devices. The system is configured to calculate the steering matrix based on the third and fourth beamforming feedback received from the one or more third and fourth communication devices. The first communication device.

3. The first communication device according to claim 2, The circuit is configured to include in the third feedback request information an indication of the number of singular vectors in the channel matrix between the second and third communication devices, corresponding to the number of requested feedback vectors for the one or more third communication devices to provide feedback, and / or an indication of the number of singular vectors in the channel matrix between the second and third communication devices, corresponding to singular values ​​below a threshold, and / or information regarding whether the number of singular vectors thus calculated exceeds the number of feedback vectors requested by the one or more third communication devices. The first communication device.

4. A first communication device according to claim 1, The circuit is configured to receive the fourth beamforming feedback from the fourth communication device in response to a trigger transmitted to the fourth communication device or within an interframe spatial time interval from the end of the transmitted training data. The first communication device.

5. A first communication device according to claim 1, The aforementioned circuit is The number of requested feedback vectors included in the fourth feedback request information is The number of directions for which the first communication device can control interference is greater than or equal to the maximum number of directions for which it can control interference, and / or The first communication device is subject to the maximum zero spatial dimension, and / or The number of spatial streams used for communication between the first communication device and the third communication device shall be greater than or equal to the number of spatial streams used for communication between the first communication device and the third communication device, and / or The first communication device has a number of feedback vectors equal to or greater than the number requested by the third communication device, and / or The second communication device has a number of feedback vectors that is equal to or greater than the number requested by the fourth communication device, The number of spatial streams used for data communication between the second communication device and the fourth communication device shall be greater than or equal to the number of spatial streams used for data communication between the second communication device and the fourth communication device, and / or As part of the beamforming feedback, the feedback dimension is less than or equal to the maximum feedback dimension that can be fed back to the first communication device. It is configured to calculate The first communication device.

6. A first communication device according to claim 1, The circuit is configured to transmit the feedback request information as part of a null data packet announcement. The first communication device.

7. A first communication device according to claim 1, The circuit is configured to send a trigger to one or more third and / or fourth communication devices that are requesting beamforming feedback immediately after the first communication device has transmitted the feedback request information and the training data, or after both the first and second communication devices have successively transmitted their own feedback request information and their own training data. The first communication device.

8. A first communication device according to claim 1, The aforementioned circuit is The modified third feedback request information is transmitted to one or more third communication devices. The corrected third training data is transmitted to the one or more third communication devices using the calculated steering matrix. The modified third beamforming feedback is received from the one or more third communication devices. Based on the received modified third beamforming feedback, a steering matrix is ​​calculated for communicating with the one or more third communication devices using the modified beamforming. The modified steering matrix is ​​used to communicate with the one or more third communication devices. It is configured to The first communication device.

9. A first communication device according to claim 1, The aforementioned circuit is The functions and communication requirements of the fourth communication device are as follows: Identification information for specifying the fourth communication device, The maximum number of spatial streams that the fourth communication device can process, used to calculate the number of requested feedback vectors or the range of requested feedback vectors, A bandwidth in which the fourth communication device can be used, within or in part of said bandwidth, where sounding should be performed. Information regarding whether puncture is possible. Information regarding whether the fourth communication device can use a compressed LTF (Long Training Field), The maximum number of spatial streams that can be received during the aforementioned sounding, and The maximum support feedback dimension for the fourth beamforming feedback described above. It is configured to obtain one or more of the following. The first communication device.

10. A first communication device according to claim 1, The aforementioned request feedback format is: An indicator showing whether the feedback vector corresponds to the core or zero space of the channel between the first communication device and the fourth communication device, An indicator showing whether the aforementioned feedback vector is compressed or not, One or more compression parameters when the feedback vector is compressed, and Information regarding whether the average signal-to-noise value is included as part of the fourth beamforming feedback. Includes one or more of the following The first communication device.

11. A first communication device according to claim 1, The circuit is part of the fourth beamforming feedback, The number of singular vectors in the channel matrix of the channel between the first communication device and the fourth communication device, corresponding to a singular value below a threshold, which corresponds to the number of request feedback vectors, or is within the range of the number indicated as part of the fourth feedback request information, or The number of singular vectors in the channel matrix of the channel between the first communication device and the fourth communication device, where the singular vectors correspond to all singular values ​​exceeding a threshold, or to a number corresponding to the number of receiving antennas of the fourth communication device, or to a number corresponding to the maximum support feedback dimension for the fourth beamforming feedback. Configured to receive The first communication device.

12. A fourth communication device configured to communicate with a second communication device within its own basic service set, A fourth feedback request information, which includes a request feedback format and a number of request feedback vectors or a range of request feedback vectors, is received from a first communication device configured to communicate with one or more third communication devices in another basic service set, relating to feedback that the fourth communication device provides to the first communication device. The fourth training data is received from the first communication device. Based on the received fourth training data, channel information is estimated. A feedback vector corresponding to the singular vector of the channel between the first communication device and the fourth communication is calculated based on the estimated channel information. The fourth beamforming feedback, including the calculated feedback vector, is transmitted to the first communication device according to the requested feedback format. Circuit configured in such a way Equipped with The fourth communication device.

13. A fourth communication device according to claim 12, The circuit is configured to include in the fourth beamforming feedback a corresponding indication, or an indication indicating that the interference conditions may not be met, if the calculated number of feedback vectors is smaller than the required number of feedback vectors, or smaller than the range of numbers included in the feedback information. The fourth communication device.

14. A fourth communication device according to claim 12, The aforementioned circuit is The system receives additional fourth feedback request information and / or additional fourth training data from the second communication device. Another fourth beamforming feedback is transmitted to the second communication device. It is configured to The fourth communication device.

15. A fourth communication device according to claim 12, The circuit, based on the calculated feedback vector, The number of requests or range of requests included in the fourth feedback request information, The feedback request information received from the second communication device includes the number of requests or the range of requests, and Estimated number of spatial streams available for data communication between the fourth communication device and the second communication device. It is configured to select the number of feedback vectors corresponding to one or more of the following. The fourth communication device.

16. A fourth communication device according to claim 12, The aforementioned circuit is Information regarding whether the calculated number of singular vectors for the channel between the first and fourth communication devices corresponding to a singular value smaller than a threshold or the number of requested feedback vectors included in the fourth feedback request information is smaller than the number of requests or range of requests included in the feedback request information received from the second communication device or an estimate of the number of spatial streams available for data communication between the fourth communication device and the second communication device. It is configured to provide feedback to the second communication device. The fourth communication device.

17. A fourth communication device according to claim 12, The aforementioned circuit is From the singular vector of the channel matrix between the first communication device and the fourth communication device, corresponding to the singular value smaller than the threshold, or As the singular vectors of the channel matrix between the first communication device and the fourth communication device, corresponding to all singular values ​​greater than the threshold, or the number of singular vectors equal to the minimum value between the number of training fields in the training data transmitted by the first communication device and the number of receiving antennas of the fourth communication device, The configuration is configured to select the aforementioned feedback vector. The fourth communication device.

18. A first communication method for a first communication device configured to communicate with one or more third communication devices within its own basic service set, A fourth feedback request information, which includes a requested feedback format and a requested number of feedback vectors or a range of requested feedback vectors with respect to the feedback that the fourth communication device provides, is transmitted to the fourth communication device. The fourth training data is transmitted to at least the fourth communication device. A fourth beamforming feedback, including the number of feedback vectors corresponding to the requested feedback format, is received from the fourth communication device. A steering matrix for communicating with the one or more third communication devices using beamforming is calculated based on the received fourth beamforming feedback. The steering matrix calculated above is used to communicate with the one or more third communication devices. The first method of communication.

19. A fourth communication method for a fourth communication device configured to communicate with a second communication device within its own basic service set, A fourth feedback request information, relating to feedback that the fourth communication device provides back to the first communication device, includes a request feedback format and a number of request feedback vectors or a range of request feedback vectors, which is received from a first communication device configured to communicate with one or more third communication devices in another basic service set. The fourth training data is received from the first communication device. Based on the received fourth training data, channel information is estimated. Based on the estimated channel information, a feedback vector corresponding to the singular vector of the channel between the first communication device and the fourth communication is calculated. The fourth beamforming feedback, including the calculated feedback vector, is transmitted to the first communication device according to the requested feedback format. The fourth method of communication.

20. A non-temporary computer-readable recording medium that stores a computer program product, when executed by a processor, causes the method described in claim 18 or 19 to be performed.

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