Communication device and communication method

Abstract

To overcome or at least reduce the problems in using cooperative beamforming in a WLAN context, in particular to reduce residual interference. In the present invention, two access points AP1, oAP1 are in overlapping basic service sets and perform partially or fully overlapping downlink transmissions towards their associated base stations STA1, oSTA1, while the interference to other base stations involved in the cooperative communication scheme is controlled and suppressed / reduced.

Description

[Technical field]

[0001] The present disclosure relates to communications devices and methods, particularly for use with coordinated beamforming. [Background technology]

[0002] Enhancement of spatial reuse by utilizing beamforming techniques to manage interference and improve spectral efficiency has been discussed in academic circles and is currently being considered in recent draft amendments to the IEEE 802.11 standard P802.11TGbe and beyond. Summary of the Invention [Problem to be solved by the invention]

[0003] So far, different cooperation and beamforming techniques have been proposed, including joint transmission and cooperative beamforming. The latter is easier to implement because the involved access points (APs) handle data transmission independently after an initial cooperation and training phase is set up. However, implementing cooperative beamforming in WLANs has several challenges, including legacy constraints and residual interference issues caused by the format of the transmission packets.

[0004] The "Background" discussion provided herein is intended to generally set forth the context of the present disclosure. To the extent that it is described in this Background section, aspects of the present specification that may not be admitted as prior art at the time of filing and the inventor's work are not admitted, expressly or impliedly, as prior art to the present disclosure.

[0005] The aim is to overcome or at least reduce the problems in using cooperative beamforming in a WLAN context, in particular to reduce residual interference. [Means for solving the problem]

[0006] According to one aspect, the first communication device is a first communication device configured to communicate with one or more third communication devices, transmitting first configuration information including first beamforming configuration information and first time information, where the first time information indicates a duration of intended transmission from the first communication device to one or more third communication devices of one or more data units to which the first configuration information applies and / or a maximum duration of simultaneous transmission of data units by the first communication device and a second communication device configured to communicate with one or more fourth communication devices; listening for receipt of second configuration information from the second communication device, where the second configuration information includes second beamforming configuration information and second time information, the second time information indicating a duration of an intended transmission of one or more data units to which the second configuration information applies to one or more fourth communication devices; and communicating with the one or more third communication devices using the first configuration information and, if received, taking into account the second configuration information using coordinated beamforming. The present invention provides a circuit configured as follows: The communication includes transmitting a first data unit including a preamble and a payload to a third communication device; Beamforming weights are used to transmit both the preamble and the payload of the first data unit that reduces or minimizes interference to a fourth communication device.

[0007] According to a further aspect, the second communication device is a second communication device configured to communicate with one or more fourth communication devices, receiving first configuration information from a first communication device configured to communicate with one or more third communication devices, the first configuration information including first beamforming configuration information and first time information, where the first time information indicates a duration of an intended transmission from the first communication device to the one or more third communication devices of one or more data units to which the first configuration information applies, or a maximum duration of simultaneous transmission of data units by the first communication device and the second communication device; transmitting second configuration information comprising second beamforming configuration information and second time information, the second time information indicating a duration of an intended transmission of one or more data units to which the second configuration information applies to one or more fourth communication devices; Using the second configuration information, communicate with the one or more fourth communication devices using coordinated beamforming and taking into account the first configuration information. The present invention provides a circuit configured as follows: the communication includes transmitting a second data unit including a preamble and a payload to a fourth communication device; beamforming weights are used to transmit both the preamble and the payload of the second data unit that reduces or minimizes interference to a third communication device; The first communication device transmits to the third communication device a first data unit that at least partially overlaps in time with transmission of the second data unit from the second communication device to the fourth communication device.

[0008] According to a further aspect, a third communication device is configured to communicate with the first communication device, the third communication device comprising: receiving first configuration information comprising first beamforming configuration information and first time information, where the first time information indicates a duration of an intended transmission from the first communication device to the third communication device of one or more data units to which the first configuration information applies and / or a maximum duration of simultaneous transmission of data units by the first communication device and a second communication device configured to communicate with one or more fourth communication devices; Communicating with the first communication device The present invention provides a circuit configured as follows: The communication includes receiving a first data unit transmitted from the first communication device, the first data unit including a preamble and a payload; beamforming weights are used to transmit both the preamble and the payload of the first data unit; The received first data unit is decoded using the first configuration information.

[0009] According to a further aspect, there is provided a computer program comprising program means for causing a computer to perform the steps of the methods disclosed herein, when the computer program is executed on a computer, and a non-transitory computer readable recording medium having stored therein a computer program product which, when executed by a processor, causes a computer to perform the methods disclosed herein.

[0010] Embodiments are defined in the dependent claims. It is to be understood that the disclosed communication device, the disclosed communication method, the disclosed computer program and the disclosed computer readable recording medium have further embodiments similar and / or identical to the communication device as defined in the claims and as defined in the dependent claims and / or as disclosed herein.

[0011] One aspect of the present disclosure is to enable two APs (first and second communication devices) with overlapping basic service sets (OBSS) to engage in partially or completely overlapping downlink transmissions towards associated base stations (STAs, third and fourth communication devices) while controlling interference to other base stations involved in the cooperative communication scheme. To solve or mitigate the problem of residual interference caused by legacy constraints and the format of transmission packets, protocol and frame modifications according to embodiments are presented that allow transmissions with interference nullifying beamforming scheme applied preambles while allowing base stations on the medium to correctly obtain required information from the beamformed preamble of the data unit (also called packet).

[0012] The preceding paragraphs have been provided by way of general introduction and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings, in which:

[0013] A more complete understanding of the present disclosure and many of the attendant advantages will be readily obtained as the same becomes better understood by reference to the following detailed description, when considered in connection with the accompanying drawings, in which: [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram illustrating a simple example of a cooperative beamforming scenario. [Figure 2A] A diagram showing a communication scenario involving simultaneous transmission of a PPDU having a preamble and a payload. [Figure 2B] FIG. 1 is a diagram of a communication scenario in which only a portion of the transmissions overlap. [Diagram 3] FIG. 1 is a diagram of an embodiment of a communication scenario according to the present disclosure using coordinated beamforming transmission opportunities. [Figure 4] FIG. 13 is a diagram of another embodiment of a communication scenario in accordance with the present disclosure using joint cooperative beamforming with extended estimation. [Diagram 5] An example of a projection matrix is ​​shown below. [Figure 6] 1 shows a modified pilot sequence for enhanced noise estimation. [Figure 7] 1 illustrates another embodiment of a communication scenario according to the present disclosure using a multi-user sequence of single-user cooperative beamforming (CBF) transmission. [Figure 8] 1 illustrates another embodiment of a communication scenario according to the present disclosure using multi-user sequential CBF transmission without PPDU alignment and null spatial beamforming. [Figure 9]1 illustrates another embodiment of a communication scenario according to the present disclosure, where the network allocation vector (NAV) is busy for a second communication device at the start of a CBF. [Figure 10] 1 illustrates another embodiment of a communication scenario according to the present disclosure, where no preamble mapping occurs while the NAV is busy in the second communication device. [Figure 11] 1 illustrates a communication system including a first communication device, a second communication device, a third communication device, and a fourth communication device according to the present disclosure. [Figure 12] 4 is a flowchart illustrating an embodiment of a first communication method of a first communication device according to the present disclosure. [Figure 13] 4 is a flow chart illustrating an embodiment of a second communication method of a second communication device according to the present disclosure. [Figure 14] 11 is a flow chart illustrating an embodiment of a third communication method for a second communication device according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Referring now to the drawings, where like reference numerals denote the same or corresponding parts throughout the several views, FIG. 1 is a schematic diagram illustrating a simple example of a cooperative beamforming scenario. One access point (AP), AP1 (also referred to herein as a first communication device) and oAP1 (overlapping AP, also referred to herein as a second communication device), each serves one associated base station (STA), STA1 (also referred to herein as a third communication device) served by AP1 and oSTA1 (overlapping base station, also referred to herein as a fourth communication device) served by oAP1. Downlink (DL) transmissions from one AP to each station (i.e., data flows from AP to STA, shown as solid lines) overlap partially or completely in time. To reduce the interference caused to each other STA (shown as dashed lines in FIG. 1), each AP employs a beamforming technique called interference nulling.

[0016] Interference nulling involves determining and using beamforming weights (denoted as BF11 and BF22 in FIG. 1) at the transmitter such that desired transmissions to the intended STAs can be performed with a desired quality of service while interference to a set of protected STAs is minimized or kept below a threshold. These beamforming weights (or corresponding beamforming or shaping matrices) may have been previously determined, for example, in a beamforming training or beamforming sounding phase.

[0017] However, implementing cooperative beamforming in a WLAN context entails several challenges: Respecting the current format of the data units (e.g., the Physical Layer Protocol Data Unit (PPDU) format) and applying beamforming as currently allowed by the standard can lead to significant error rates, depending on how the transmission is performed.

[0018] FIG. 2A illustrates a communication scenario involving simultaneous transmission of a PPDU having a preamble (including a legacy preamble part (LP), a signaling part (SIG), and a short training field and a channel estimation field (STF / CEF)) and a payload.

[0019] The LP part is understood by all IEEE 802.11 compliant devices and is necessary for backward compatibility. The LP part contains a training field to enable packet detection, synchronization, and initial channel estimation, and a signaling field that indicates basic information such as the duration of the PPDU. In standard operation, this field is not beamformed.

[0020] The SIG part contains more comprehensive signaling information that new generations of devices, for example compliant with IEEE 802.11ax or 802.11be, can understand. This includes information about bandwidth, TXOP time, MCS, number of spatial streams, etc. This is important information to allow the stations involved in the communication to decode the next data field of the PPDU, and also for other base stations to know the channel usage. In standard operation, this field is not beamformed.

[0021] The STF and CEF fields allow fine synchronization and channel estimation to properly decode the data field. In standard operation, when beamforming is applied, these fields and the data field (payload part) are beamformed with the same weights.

[0022] As shown in Fig. 2A, when both APs start transmitting simultaneously to the corresponding STAs, a header error rate of about 25% can be observed, despite the interference nullification effect of the applied beamforming technique, which traditionally does not apply to the header (including the LP and SIG parts), but only to the payload and STF / CEF parts. This error rate means that about 25% of PPDUs require retransmission, since any remaining errors in the PPDU header will cause the PPDU to be decoded incorrectly. In this context, a header error refers to the case when the information in the signaling field of the preamble cannot be decoded, and without this information the STA cannot decode the data field, i.e. the PPDU is effectively lost.

[0023] On the other hand, if one of the APs starts transmitting at a later time than the other APs, especially after the preamble of the first transmission (oAP1 in this example) has already been sent, a large packet error rate in the range of 50% can be expected in the payload from the time the delayed overlapping transmission starts, as shown in the illustration of a communication scenario where only part of the transmissions overlap, as shown in Figure 2B.

[0024] The main source of these errors is the PPDU format, which includes at the beginning a header (in the example shown in Figures 2A and 2B, a header including the LP and SIG parts) that must be understood by all STAs listening to the medium. Due to this constraint, this part is not usually transmitted with beamforming applied (as shown in Figures 2A and 2B), except in the very special case of single user transmission (SU) according to IEEE 802.11ax. The difficulty of beamforming the preamble is that the preamble carries the control information necessary for the STAs to correctly decode the packet, such as instructions regarding the length of the PPDU (necessary for all STAs listening to the medium, and especially for legacy STAs to infer the period during which the medium is occupied and should not attempt channel access), the beamforming configuration (e.g. the number of spatial streams to be used, the information contained in the SIG field immediately before the channel estimation sequence), the bandwidth, resource allocation, user ID, etc.

[0025] However, applying interference nulls in the preamble, especially the header, appears to be an efficient way to implement cooperative beamforming and avoid the large overhead for cooperation. For this reason, the present disclosure presents a method that allows at least one of the APs to apply beamforming to the (entire) preamble, including the header, while ensuring that the intended recipients of the PPDUs can decode them correctly and that unintended recipients can determine the necessary information for correct channel access. The technique of applying beamforming to the entire preamble is also referred to herein as preamble mapping (PM).

[0026] In the following description, a cooperative beamforming scenario is considered in which one AP (AP1) communicates with one STA (STA1) at a time while disabling one or more oSTAs (oSTA1). Furthermore, the oAP (oAP1) transmits to one or more oSTAs at a time while disabling one or more STAs, and the transmissions from the AP to the STAs and from the oAP to the oSTAs overlap partially or completely in time. In a real scenario, each AP may communicate with one or more STAs, and there may be more than one AP.

[0027] The present disclosure presents a communications apparatus and method for coordinated beamforming (CBF) transmission that minimizes the probability of error due to preamble interference (particularly header interference) while ensuring that there is a correct distribution of channel occupancy information to unintended STAs, i.e., that the unintended STAs are able to decode the length and / or duration of the upcoming transmission. Additionally, correct control distribution to intended STAs is provided.

[0028] One element of an embodiment of the presented CBF solution is that at least one of the APs transmits, as part of the CBF transmission, one or more PPDUs with spatial mapping, e.g. interference-null beamforming, applied to the entire preamble, the configuration used in each PPDU being implicitly or explicitly announced in a previous DL PPDU from the transmitting AP STA. Depending on the channel occupancy, i.e. whether both APs can start beamformed transmissions at the same time or not, two main cases are distinguished:

[0029] In the first case, both APs can start transmitting at the same time, i.e., channel occupancy allows this. Figure 3 is a diagram of a corresponding embodiment of a communication scenario according to the present disclosure using a coordinated beamforming transmission opportunity (TXOP) with both APs. Both APs apply beamforming to the header.

[0030] Initially, AP1 and oAP1 compete for the medium to start transmission to STA1 and oSTA1, respectively. Assuming that AP1 wins the contention phase, during the TXOP initiation AP1 can announce, for example by a multi-user ready-to-send (MU-RTS) transmission or other suitable announcement, that the transmission in the next TXOP can be performed with cooperative beamforming, as another frame or data unit, or as part of another frame or data unit. Identifiers, for example association identifiers (AIDs), of STAs capable of a cooperative beamforming stage are announced, for example in the multi-user ready-to-send (MU-RTS). If oAP1 has data for at least one oSTA for which a previous cooperative beamforming training or sounding phase has been performed and which the training or sounding phase revealed can serve simultaneously with the announced STA, the AP can respond to the initial announcement, for example MU-RTS, by a corresponding response, for example a clear-to-send (CTS) transmission. STA1 may respond to the initial announcement in a similar manner, for example with another CTS transmission.

[0031] In order to allow two APs to transmit simultaneously to their respective users using coordinated beamforming, some of the information that would otherwise be in the header (also referred to herein as configuration information) is announced at least partially in advance. In the embodiment shown in FIG. 3, second configuration information including the configuration of the preamble of the PPDU transmitted from oAP1 to oSTA1 is announced, for example, in a frame, referred to herein as a coordinated beamforming announcement frame (CBA). This ensures that oSTA1 is able to decode the respective transmission. Similarly, second configuration information including the configuration of the preamble of the PPDU transmitted from AP1 to STA1 is announced, for example, in a frame, referred to herein as a coordinated beamforming response frame (CBR). Information such as, for example, the number of spatial streams on which the coordinated PPDU is transmitted may be included in these frames. Furthermore, information regarding the length of the next beamforming PPDU, or the duration of the downlink transmission, or an indication as to when an acknowledgement is required may be included.

[0032] The length of the beamformed PPDU or the duration of the DL transmission can be transmitted to allow the two APs to organize the UL transmissions, for example for the acknowledgement phase, under the assumption that the UL transmissions are not nulled, i.e., neither the UL transmissions between STA1 and AP1, nor the UL transmissions between oSTA1 and oAP1, nor the UL transmissions and the DL transmissions of other Basic Service Sets (BSSs) are nulled.

[0033] For STAs other than STA1 and oSTA1, information regarding the length of the next PPDU duration may be included in the CBA and CBR, respectively, e.g., as a spoofed length covering the next duration, or simply as signaling information.

[0034] When the channel state information (CSI) on which the beamformer is calculated becomes stale, i.e., when the period between sounding and actual data transmission becomes longer than a certain threshold, the null effect decreases and transmissions become more susceptible to mutual interference.

[0035] The CBA / CBR frame transmission / reception can be preceded by one transmission from AP1 of a frame, for example a CBRi frame. It is beneficial for AP1 to start frame transmission / reception after receiving CTS, because otherwise the following problems may occur: STAs that do not hear CTS can assume that the intended STA has made the channel busy, and are therefore allowed to transmit within the timeout after receiving RTS. Thus, if the inactivity period of AP1 is larger than the respective timeout interval, the STA may mistakenly assume that the TXOP establishment was not successful and start transmitting, resulting in a collision. On the other hand, after responding with CTS, oAP1 may already deliver its NAV and start transmitting towards AP1, informing it of its participation in CBF and the beamforming information to be used. This can be achieved with less overhead than the scheme with CBRi, but at the cost of reduced reliability.

[0036] After transmitting and receiving the first and second configuration information (contained in the CBA and CBR frames in this example), AP1 and oAP1 start transmitting simultaneously to STA1 and oSTA1, respectively, using cooperative beamforming. This causes AP1 to use the first configuration information and take into account the second configuration information if received from oAP1. In this way, PPDUs may be transmitted simultaneously with interference nulls, in which case beamforming weights (or corresponding beamforming or shaping matrices) are used to transmit both the preamble and payload of the PPDU that reduces or minimizes the interference to oSTA1, which oAP1 transmits or intends to transmit. In exactly the same way, oAP1 uses the second configuration information and takes into account the first configuration information using cooperative beamforming.

[0037] The first configuration information thus includes first beamforming configuration information and first time information indicating the duration of intended transmission of one or more data units from AP1 to one or more STA(s) to which the first configuration information applies, and / or the maximum duration of simultaneous transmission of data units by AP1 and oAP1 communicating (or intended to communicate) with one or more oSTA(s).

[0038] Thus, the second configuration information includes second beamforming configuration information and second time information indicating a period of intended transmission of one or more data units from oAP1 to one or more oSTAs to which the second configuration information applies.

[0039] In general, the first beamforming configuration information consists of one or more of the following: the number of spatial streams used by AP1 to transmit the first data unit to STA1; Identification information indicative of one or more STAs with which AP1 intends to communicate during the current transmission opportunity, and / or identification information indicative of a set of one or more STAs and oSTAs that can be simultaneously served by AP1 and oAP1; and The maximum number of degrees of freedom, including spatial dimensions and / or spatial streams and / or space-time streams, that can be used by oAP1 to serve one or more oSTAs simultaneously for transmission from AP1 to STA1.

[0040] The second beamforming configuration information generally consists of one or more of the following: the number of spatial streams used by oAP1 to transmit the second data unit to oSTA1; Identification information indicating one or more oSTAs with which oAP1 intends to communicate during the current transmission opportunity or to perform cooperative beamforming, and / or identification information indicating a set of STA1 and oSTA1 that can be simultaneously served by AP1 and oAP1 as part of a subsequent transmission; and o The maximum number of degrees of freedom that can be used by AP1 to serve one or more STAs (more than 1) simultaneously in transmission from AP1 to oSTA1.

[0041] The first time information typically includes one or more of the following indications: The time when AP1 is expected to send an acknowledgment to STA1, the time at which AP1 is expected to receive an acknowledgment from STA1 in response to transmitting the first data unit; When the acknowledgement request is included in the subsequent first data unit or is sent separately; Subsequent coordinated beamforming transmissions are initiated synchronously or whether and to what extent the transmission of the second data unit is likely to exceed the transmission of the first data unit; the length of the first data unit to be transmitted with the selected beamforming weights in response to the indication by the first beamforming configuration (T_p in FIG. 4); and The duration of the sequence of first data units transmitted with the selected beamforming weights as indicated by the first beamforming configuration and corresponding interframe spatial time, and the interframe spatial time.

[0042] The second time information generally includes one or more indications of the following: The time when oAP1 is expected to send an acknowledgment request to oSTA1, the time at which oAP1 expects to receive an acknowledgment from oSTA1 in response to transmitting the second data unit; An acknowledgment request is included in a subsequent second data unit, or If requested in the first timing information, verifying that subsequent transmissions are performed synchronously with the transmissions from AP1 to STA1; a length of the second data unit to be transmitted together with the beamforming weights indicated by the second beamforming information; and The duration of the sequence of data units transmitted with the beamforming configuration indicated by the second beamforming information, and the interframe spatial time.

[0043] In one embodiment, when initiating a CBF TXOP, AP1 has traffic for one or more STAs. However, it cannot know which or which oSTAs are CBF capable (from a beamforming perspective) need to be served or if the oAP has buffered traffic for them. This is information provided specifically from the oAP together with the confirmation that the oAP will participate in the CBF stage. This information is taken into account by AP1. After confirmation from the oAP together with the identities of the oSTAs, AP1 is able to use interference-null based beamforming.

[0044] Therefore, the second configuration information of the oAP should at least indicate whether it transmits frames (or data units) fully or partially overlapping with frames (or data units) from AP1 using a coordinated beamforming technique. In this case, it must further include which beamforming configuration is used during the fully or partially overlapped transmission (informing about the beamforming configuration means either informing which oSTAs it serves, or informing an indication of the beamforming configuration, or informing a group AID indicating the set of STAs and oSTAs that are served together by the respective APs they are associated with).

[0045] There are two possible points for synchronization: first, requesting a synchronized start of cooperative transmission (which requires that the subsequent PPDUs are transmitted with enhanced estimation and / or pilot sequences) and / or, second, transmitting a frame before the cooperative transmission that is preamble-mapped, after which both AP1 and oAP1 start transmitting within SIFS (or a predefined interval).

[0046] 4 is a diagram of another embodiment of a communication scenario according to the present disclosure using joint cooperative beamforming with enhanced estimation. In this case, the start of PPDU transmission from AP1 and oAP1 is synchronized. Both APs modify the estimation fields (STF / CEF) so that STA1 and oSTA1 can individually determine the channel from their own AP as well as the channel from the interfering AP. For example, STA1 can estimate both the channel from AP1 and the channel from oAP1.

[0047] To achieve this, in one embodiment, the two APs extend the number of LTF sequences on which estimation is performed in order to achieve orthogonalization of the estimation sequences used by the two APs. This extension can correspond to the total number of spatial streams transmitted and received by the two APs during one CBF DL PPDU transmission. More precisely, oAP1 informs oSTA1 of N SS oAP1 AP1 sends N SS AP1 During cooperative DL transmission, both APs must transmit at least N SS oAP1 +N SS AP1 LTF estimation sequences can be used. Furthermore, these estimation sequences are created by expanding an orthogonal P matrix to the desired dimension and selecting the number of rows that correspond to the desired number of spatial streams for each AP. The selection can be made such that the selected rows are mutually distinct.

[0048] In the example shown in Figure 4, oAP1 is the first N SS oAP1 The rows can be selected and the signal can be sent within the CBA, and AP1 can select N different projection matrices as shown in Figure 5. SS AP1Select a set of rows and transmit the signal within the CBR. Upon receiving the CBR, oAP1 updates the number of LTF sequences and both APs start transmitting with the extended estimate. In Figure 5, the index g denotes the LTF index in the transmission order. Similarly, it can be called the time index of the LTF.

[0049] Furthermore, in order to improve the noise estimation, the following modifications can be made to the pilot sequences used within the two PPDUs: In normal transmission, pilot sequences are used not only during data payload transmission but also during the preamble, and their main purpose is to track and correct phase and frequency changes during the PPDU. For this operation, it is sufficient if the values ​​used for the pilots in the preamble part are the same as those used for the pilots transmitted during the data part. Furthermore, in normal transmission, a single-stream pilot is sufficient, since phase tracking of only a single transmitter is performed on this basis.

[0050] In coordinated beamforming transmission, the pilots can still be transmitted in a single stream. However, it may be beneficial to select each of the streams used by an AP to be orthogonal to the streams used by other APs. More specifically, the pilots of the BSS and OBSS transmissions for subcarrier k and LTF symbol g can be set as follows:

[0051]

number

[0052] Here, [ψ LTF AP1 ] k,g is the pilot at subcarrier k and symbol g used during the LTF sequence by AP1, and τ k is the training symbol in subcarrier k, g is the OFDM symbol index, and r gare elements of the mapping matrix R, which is similar to the projection matrix P. In a typical implementation, the R matrix is ​​set to the first row of the P matrix, regardless of the number of streams, etc.

[0053] In the implementation of the modified pilot sequences for enhanced noise estimation shown in FIG. 6, the first AP can select the default first row of the P matrix, and the second AP (e.g., AP1 in FIG. 4) can select the first row of the P matrix (e.g., the third row in the examples of FIG. 5 and FIG. 6) that it uses. If multiple streams are transmitted by any AP, the pilots are equal among these multiple streams, since we are primarily interested in isolating the effects of the oBSS from the effects of the BSS. In general, in other words, each transmitter transmitting at a given time needs a separate orthogonal pilot. Furthermore, within the payload, the pilot sequences remain unchanged between BSSs. More specifically, for the kth subcarrier and gth symbol, the two pilot sequences can be written as follows:

[0054]

number

[0055] Improved noise estimates can be obtained by performing estimations on pilots in the preamble and data parts of the PPDU and performing averaging operations. Thanks to these techniques, sudden noise variations occurring in the payload due to, for example, early termination of an interfering transmission or a sequence of interfering DL PPDUs can be better estimated and provided to the Minimum Mean Square Error (MMSE) generator.

[0056] To ensure correct decoding of PPDUs with new estimated and / or pilot sequences, the STA should be notified by the two corresponding APs. In the implementation example shown in Figure 4, one or more (preferably all) of the following indications should be present in the CBA: Orthogonal estimation sequences and / or orthogonal pilots are used; Which sequence is used, Which pilots will be used? Each of the APs may require the use of orthogonal sequences based on the freshness of the CSI at the respective AP.

[0057] An advantage of the synchronous initiation mode of operation described in Fig. 4 is the possibility to exploit the relaxation regarding the frequency with which sounding needs to be performed and serve multiple sets of STAs during one CBF TXOP with relatively little additional overhead. This is illustrated in Fig. 7, which shows another embodiment of a communication scenario according to the present disclosure using a multi-user sequence of SU-CBF transmissions. According to this embodiment, in the first stage, AP1 transmits towards STA1 with beamforming configuration BF11, nullifying interference to oSTA1, while oAP1 transmits towards oSTA1 with beamforming configuration BF21, nullifying interference to STA1. In the second stage, within the TXOP, AP1 transmits to the second base station STA2 while nullifying interference to oSTA1, while oAP1 continues to transmit towards oSTA1 with a modified beamforming configuration BF22, which nullifies interference to STA2.

[0058] Between the two stages, a new CBA / CBR transmission / reception can be performed to announce new configuration parameters of CBF. The prerequisite for this scheme is that a coordinated training phase has been performed, in which one or more of the beamforming configurations that can be used simultaneously by AP1 and oAP1 have been determined after collecting channel state information from both the STAs targeted in the TXOP and the oSTAs. Thus, for example, after the AID of the STA to be nulled next is first announced from AP1, oAP1 selects one of the oSTAs for which two conditions are met: there is a beamforming configuration that does not cause interference to the selected STA, and there is traffic to be transmitted to the respective oSTA. Based on the length information in the initial CBA / CBR PPDU, it can be inferred when a new CBA / CBR transmission / reception can be performed.

[0059] A modified implementation is to have the CBA frame sent SIFS after the longest PPDU transmission. For synchronous start CBF operation, alignment of DL PPDU ends is not required, but a constraint is assumed to prevent one transmission from being significantly longer than the other.

[0060] In the case of sequential CBF transmission (i.e., transmission using multiple preamble-mapped PPDUs one after the other), it is possible to relax the constraint on the synchronous start of the non-first PPDU in the sequence. However, some design modifications must be considered. In this case, the configuration of the beamformed PPDU preamble can be kept the same for all PPDUs in the sequence, since there is no CBA / CBR transmission / reception in between. Furthermore, duration information can be signaled in the first CBA and replicated in the CBR to signal the end of the simultaneous transmission with beamforming applied to the preamble and the start of the acknowledgement or uplink phase. In order to make such a solution viable for multi-user sequential CBF transmission, while considering the constraint of maintaining the configuration of the preamble transmission format, the design is modified as shown in FIG. 8, which illustrates another embodiment of a communication scenario according to the present disclosure, with multi-user sequential CBF transmission without PPDU alignment and null-space beamforming.

[0061] However, the beamforming matrix used is not necessarily used for payload transmission, but is only intended to control interference to STAs from other BSSs participating in the CBF. More specifically, this can be achieved by applying a beamforming matrix to the preamble that is based only on the nulled spatial components of the channel matrix corresponding to the STAs whose interference should be controlled. For example, to calculate BF02 towards STA1 and STA2, oAP1 can perform a singular value decomposition (SVD) of the channel matrix between oAP1 and STA1 and between oAP1 and STA2, respectively. Based on this decomposition, a beamforming matrix corresponding to the minimum between the number of streams to be used for the subsequent transmission and the dimension of the null space resulting from the SVD is determined. If this number is greater than 1, the singular vector corresponding to the determined null space is used for the transmission of BF02. For payload transmission, BF21 is a multiplication of the null spatial component with a second component that takes into account the best singular vector of the channel towards STA1. Similarly, AP1 applies BF01 in the null space of oSTA1 without fine-tuning to the STA1 or STA2 channel. In this case, the configuration does not change, so it is guaranteed that the two STAs can decode the preamble. In this case, AP1 changing the intended receiver between STA1 and STA2 can be done without informing the two STAs of new parameters in separate PPDUs, since both STAs can decode the header or legacy preamble with the applied beamformer. In the training phase prior to the CBF transmission, it can be guaranteed that the transmission with the null space based matrix can be received by the two STAs with sufficient SNR to allow correct decoding of the preamble information.

[0062] In the following we consider the second case where the channel is busy at the start of the other AP's CBF stage. So far we have considered the behavior when both AP1 and oAP1 detect the channel as idle at the time the other AP starts its cooperative beamforming transmission opportunity. An example implementation for the other case is shown in Figure 9 and Figure 10.

[0063] As in the previous case, assume that AP1 wins the contention and initiates a CBF TXOP. However, since oAP1 has set its NAV to Busy, it cannot respond with a CTS or send a CBA. AP1 can do one of the following:

[0064] A first example is shown in Fig. 9. Fig. 9 illustrates another embodiment of a communication scenario according to the present disclosure, where the network allocation vector (NAV) indicates that the channel is busy for oAP1 at the start of CBF. After the timeout has elapsed and no activity from oAP1 has been detected, AP1 transmits a CBR informing of the configuration of the next PPDU as in the previous case, followed by a PPDU with a beamformed preamble. After the end of the PPDU transmission, AP1 starts a listening period, and oAP1 can start PPDU transmission assuming that the channel has become idle. However, since oAP1 has not yet been informed of the configuration of the CBF PPDU, it starts with a normal PPDU (i.e., no beamforming is applied to the preamble). Based on this, AP1 determines the length of the PPDU and the length of the preamble. AP1 starts a beamforming transmission, and during the preamble, the same beamforming is used as was used during the previous PPDU transmitted from AP1 to STA1.

[0065] Furthermore, the transmission may start after oAP1 has finished transmitting the preamble with an optional safety margin, so that STA1 receiving the transmission from oAP1 to oSTA1 can decode the preamble and determine based on the SIG information that the PPDU is not intended for itself. If STA1 determines based on the SIG information that the PPDU was transmitted as part of a CBF scheme, it discards the packet, resets its PHY, and starts receiving the correct PPDU, i.e., the PPDU from AP1. The determination of whether the PPDU was transmitted as part of a CBF scheme can be based on the following indicators: BSS color (i.e., the BSS color of oAP1 corresponds to the BSS announced by AP1 as the BSS in which the AP participated in each CBF), AID (currently present in the SIG field), or CBF identifier (indicating the index of the CBF allowed during the TXOP).

[0066] Another example is shown in Figure 10. Figure 10 illustrates another embodiment of a communication scenario according to the present disclosure without preamble mapping while NAV is busy at oAP1. In this case, the transmission from AP1 to STA1 is without preamble mapping unless there is a response from oAP1. There is an indication in the preamble that a follow-up PPDU will be transmitted after the listen time. If a CBF PPDU is received from oAP1, the follow-up PPDU from AP1 to STA1 is transmitted with the same beamforming and legacy preamble or header configuration that was used when transmitting the payload of the non-preamble-mapped PPDU. Constraints may be imposed on the length of the PPDU from oAP1 to oSTA1, such as a maximum length. In addition, one of the following conditions may be imposed: i) Only one PPDU is sent from oAP1 to oSTA1. After sending, oAP1 waits for a continue instruction from AP1. Or ii) The length of AP1's transmission does not exceed the length of oAP1's transmission, to ensure correct continuation of transmissions after overlapping transmissions of the two APs.

[0067] A loosely synchronized transmission can cause problems with interference during the guard interval. A potential solution to this is to change the window function that the receiver applies between OFDM symbols. For example, using a window function with a larger transition time between OFDM symbols can improve the resistance to this type of error. For the STA to know how to adapt the window function, the AP should indicate whether the CBF transmission is performed in a synchronous or asynchronous manner and potentially how much deviation with respect to the OFDM symbol boundary is allowed. Based on this information, the STA can adapt the transition time of the window function.

[0068] 11 is a diagram illustrating a communication system according to an aspect of the present disclosure, including a first communication device 10 (AP1) for communicating with one (or more) third communication device(s) 30 (STA1) and a second communication device 20 (oAP1) for communicating with one (or more) fourth communication device(s) 40 (oSTA1). According to the present disclosure, the two APs 10, 20 are in overlapping basic service sets and engage in partially or fully overlapping downlink transmissions towards their respective associated base stations(s) 30, 40. At the same time, interference to other base stations involved in the cooperative communication scheme is controlled and suppressed / reduced.

[0069] In this context, it must be noted that beamforming is generally not applied to all connected oSTAs, but to one or more oSTAs (one or more) that were determined in a previous training phase to be able to nullify interference for them simultaneously with the specific STAs served by the AP. oAP1 indicates in the second configuration information that there is buffered traffic for oSTA, and oAP1 transmits frames in a CBF manner to oSTA during a CBF TXOP requested by AP1 for STA1. Furthermore, it is intended that the preamble is beamformed only with matrices in the null space of the oSTA (one or more), and the payload is beamformed with matrices that are derived from both the null space of the one or more oSTAs (one or more) and the SVD of the specific STA (one or more) that it serves.

[0070] Each of the communication devices 10, 20, 30, 40 comprises a circuit 11, 21, 31, 41 configured to perform certain operations. The circuit may be implemented by a respective processor or computer, i.e. as hardware and / or software, or by dedicated units or components. For example, a respective programmed processor may represent the respective circuit 11, 21, 31, 41.

[0071] FIG. 12 shows a flow chart of an embodiment of a first communication method 100 of a first communication device 10 according to the present disclosure, which may be executed by the circuit 11. In a first step S10, first configuration information is transmitted. The first configuration information comprises first beamforming configuration information and first time information indicating a duration of an intended transmission from the first communication device to one or more third communication devices of one or more data units to which the first configuration information applies and / or a maximum duration of a simultaneous transmission of data units by a second communication device configured to communicate with the first communication device and one or more fourth communication devices. In a second step S11, the first communication device listens to the reception of second configuration information from the second communication device. The second configuration information comprises second beamforming configuration information and second time information indicating a duration of an intended transmission to one or more fourth communication devices of one or more data units to which the second configuration information applies. In a third step S12, the first communication device uses the first configuration information and, if received, takes into account the second configuration information using coordinated beamforming to communicate with one or more third communication devices, including transmitting a first data unit including a preamble and a payload to the third communication device, where beamforming weights that reduce or minimize interference to the fourth communication device are used to transmit both the preamble and the payload of the first data unit, i.e. an interference null is used.

[0072] FIG. 13 shows a flow chart of an embodiment of a second communication method 200 of a first communication device 20 according to the present disclosure, which may be executed by the circuit 21. In a first step S20, first configuration information is received from the first communication device. In a second step S21, the second configuration information is transmitted to one or more fourth communication devices. In a third step S22, the second communication device uses the second configuration information and communicates with one or more fourth communication devices taking into account the first configuration information using coordinated beamforming, the communication including transmitting a second data unit including a preamble and a payload to the fourth communication device, where beamforming weights are used to transmit both the preamble and the payload of the second data unit, which reduces or minimizes interference to a third communication device to which the first communication device transmits the first data unit, which at least partially overlaps in time with the transmission of the second data unit from the second communication device to the fourth communication device.

[0073] 14 shows a flowchart of an embodiment of a third communication method 300 of the first communication device 30 according to the present disclosure, which may be executed by the circuit 31. In a first step S30, first configuration information is received. In a second step S31, the third communication device communicates with the first communication device, the communication including receiving a first data unit transmitted from the first communication device, the first data unit including a preamble and a payload, and beamforming weights are used to transmit both the preamble and the payload of the first data unit. In a third step S32, the received first data unit is decoded using the first configuration information.

[0074] Thus, the foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. As will be understood by those skilled in the art, the present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. Accordingly, the disclosure of the present disclosure, as well as the other claims, are intended to be illustrative rather than limiting on the scope of the present disclosure. The present disclosure defines in part the scope of the preceding claim terms, including readily identifiable variations of the teachings herein, so that the inventive subject matter is not dedicated to the public.

[0075] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0076] To the extent that embodiments of the present disclosure have been described as being implemented, at least in part, by a software-controlled data processing apparatus, it will be understood that non-transitory machine-readable media bearing such software, such as optical disks, magnetic disks, semiconductor memories, etc. Moreover, such software may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0077] The elements of the disclosed devices, apparatus and systems may be implemented by corresponding hardware elements and / or software elements, such as suitable circuits or circuitry. A circuit is a structural collection of electronic components including conventional circuit elements, application specific integrated circuits, standard integrated circuits, application specific standard products, and integrated circuits including field programmable gate arrays. Furthermore, a circuit includes a central processing unit, a graphics processing unit, a microprocessor that is programmed or configured according to software code. A circuit includes the aforementioned hardware that executes software, but does not include pure software. A circuit or circuitry may be implemented by a single device or unit, or by multiple devices or units, or by chipset(s) or processor(s).

[0078] Further embodiments of the disclosed subject matter are listed below.

[0079] (1) a first communication device configured to communicate with one or more third communication devices, transmitting first configuration information including first beamforming configuration information and first time information, where the first time information indicates a duration of intended transmission from the first communication device to one or more third communication devices of one or more data units to which the first configuration information applies and / or a maximum duration of simultaneous transmission of data units by the first communication device and a second communication device configured to communicate with one or more fourth communication devices; listening for receipt of second configuration information from the second communication device, where the second configuration information includes second beamforming configuration information and second time information, the second time information indicating a duration of an intended transmission of one or more data units to which the second configuration information applies to one or more fourth communication devices; and communicating with the one or more third communication devices using the first configuration information and, if received, taking into account the second configuration information using coordinated beamforming. The present invention provides a circuit configured as follows: The communication includes transmitting a first data unit including a preamble and a payload to a third communication device; Beamforming weights are used to transmit both the preamble and the payload of the first data unit that reduces or minimizes interference to a fourth communication device. A first communication device. (2) A first communication device according to embodiment (1), The circuitry is configured to use beamforming weights to transmit the first data unit to the third communication device with an interference null that reduces or minimizes interference to one or more fourth communication devices to which the second communication device transmits or intends to transmit a second data unit that at least partially overlaps in time with transmission of the first data unit from the first communication device to the third communication device. A first communication device. (3) A first communication device according to embodiment (1) or (2), The circuitry is configured to announce that the transmission of the data unit within a current transmission opportunity is feasible with cooperative beamforming. A first communication device. (4) A first communication device according to embodiment (3), the circuitry is configured to transmit the announcement in a data unit or frame prior to or together with the transmission of the first configuration information; The data unit or frame includes identification information of a third communication device for which coordinated beamforming is performed and the second communication device performing coordinated beamforming within the current transmission opportunity. A first communication device. (5) A first communication device according to any one of embodiments (1) to (4), The first beamforming configuration information comprises one or more of the following: a number of spatial streams used by the first communication device to transmit the first data unit to the third communication device; identification information indicative of one or more third communication devices with which the first communication device intends to communicate during the current transmission opportunity and / or a set of one or more third and fourth communication devices that can be simultaneously served by the first and second communication devices; and the maximum number of degrees of freedom, including spatial dimensions and / or spatial streams and / or space-time streams, that can be used by the second communication device to serve the one or more fourth communication devices simultaneously with transmissions from the first communication device to the third communication device; and / or The second beamforming configuration information comprises one or more of the following: a number of spatial streams used by the second communication device to transmit a second data unit to the fourth communication device; Identification information indicative of one or more fourth communication devices with which the second communication device intends to communicate during the current transmission opportunity or with which it will perform cooperative beamforming, and / or a set of the third and fourth communication devices that may be simultaneously served by the first and second communication devices as part of a subsequent transmission; and a maximum number of degrees of freedom that the first communication device can use to provide services to the one or more third communication devices simultaneously with transmissions from the second communication device to the fourth communication device; A first communication device. (6) A first communication device according to any one of embodiments (1) to (5), The first time information comprises an indication of one or more of the following: a time at which the first communication device is expected to transmit an acknowledgment to the third communication device; a time at which the first communication device is expected to receive an acknowledgment from the third communication device in response to transmitting the first data unit; whether and when the acknowledgement request is included in the subsequent first data unit or whether the acknowledgement request is sent separately; Subsequent coordinated beamforming transmissions are initiated synchronously or whether and to what extent transmission of the second data unit may exceed transmission of the first data unit; a length of the first data unit to be transmitted with a beamforming weight selected in response to the indication by the first beamforming configuration; and the duration of a sequence of first data units transmitted with beamforming weights selected in response to the indication of the first beamforming configuration, and / or an interframe spatial time; and / or The second time information comprises an indication of one or more of the following: a time at which the second communication device is expected to transmit an acknowledgment to the fourth communication device; a time at which the second communication device is expected to receive an acknowledgment from the fourth communication device in response to transmitting the second data unit; An acknowledgment request is included in a subsequent second data unit, or confirming, if required by the first time information, that a subsequent transmission is performed in synchronism with the transmission from the first communication device to the third communication device; a length of a second data unit to be transmitted with the beamforming weight indicated by the second beamforming information; A duration of a series of data units transmitted in the beamforming configuration indicated by the second beamforming information, and an interframe spatial time. A first communication device. (7) A first communication device according to any one of embodiments (1) to (6), The circuitry is configured to transmit the first configuration information in a data unit or frame before or after receiving a data unit or frame that includes the second configuration information. A first communication device. (8) A first communication device according to any one of embodiments (1) to (7), The circuitry is configured to synchronize a start of transmission of the first data unit to the third communication device with a start of transmission of a second data unit by the second communication device to the fourth communication device. A first communication device. (9) A first communication device according to embodiment (8), The circuitry is configured to request the second communication device to synchronize a transmission of the second data unit directed to the fourth communication device with a transmission of the first data unit from the first communication device to the third communication device if a time interval between a sounding phase and a communication phase exceeds a predefined threshold. A first communication device. (10) A first communication device according to any one of embodiments (1) to (9), the circuitry is configured to include in a preamble of the first data unit a number of estimation sequences corresponding to a number of spatial streams; The estimated sequence is different from the estimated sequence included in the preamble of a second data unit by the second communication device. A first communication device. (11) A first communication device according to embodiment (10), the circuitry is configured to select an estimate sequence from a projection matrix of a number of orthogonal estimate sequences; The number is greater than or equal to the sum of a number of spatial streams used by the first communication device to transmit the first data unit and a number of spatial streams used by the second communication device to transmit the second data unit. A first communication device. (12) A first communication device according to any one of embodiments (1) to (11), The circuitry is configured to include one or more of the following in the first data unit: a pilot sequence orthogonal to a pilot sequence included in a second data unit by the second communication device; a pilot sequence of all streams in a training field of the first data unit, the pilot sequence being orthogonal to the pilot sequences of all streams in a training field of the second data unit; and a pilot sequence in the data portion of the first data unit that is identical to a pilot sequence included in the second data unit A first communication device. (13) A first communication device according to embodiment (11) or (12), The circuitry is configured to transmit, as part of the first configuration information, an indication that: Whether orthogonal estimation sequences and / or orthogonal pilot sequences are used; Which estimated sequence was selected from the projection matrix, and / or Which pilot sequence is used A first communication device. (14) A first communication device according to any one of embodiments (1) to (13), The circuitry is configured to transmit new first configuration information and / or receive new second configuration information before transmitting the new data unit to another third communication device. A first communication device. (15) A first communication device according to any one of embodiments (1) to (14), The circuitry is configured to transmit a preamble of the first data unit and a payload of the first data unit using different beamforming weights. A first communication device. (16) A first communication device according to embodiment (15), the preamble beamforming weights are configured to reduce or minimize interference to one or more fourth communication devices connected to the second communication device; The payload beamforming weights are configured to reduce or minimize interference to the fourth communication device to which the second communication device transmits the second data unit and / or to improve a communication link with the third communication device to which the first data unit is transmitted. A first communication device. (17) A first communication device according to any one of embodiments (1) to (16), the circuitry determines if the second configuration information is not received from the second communication device; transmitting the first data unit to the third communication device using an interference null; listening for and receiving a third data unit from the second communication device after transmitting the first data unit; deriving third configuration information from the preamble of the third data unit, the third configuration information indicating a duration of the third data unit and optionally its preamble, and transmitting a fourth data unit to the third one of the communication devices using the interference null of the preamble and payload field after the preamble of the third data unit has been completely received. It is configured as follows: A first communication device. (18) A first communication device according to any one of embodiments (1) to (17), The circuit comprises: the second configuration information is not received from the second communication device; transmitting the first data unit to the third communication device using an interference null for the payload only and indicating in a preamble that a subsequent fourth data unit will be transmitted after a listening period; listening for receipt of a third data unit from the second communication device after transmitting the first data unit; deriving third configuration information from a preamble of the third data unit, the third configuration information indicating a duration of the third data unit and its preamble; transmitting a fourth data unit to one of the third communication devices using the same interference null used in transmitting the payload of the first data unit after the preamble of the third data unit has been completely received. It is configured as follows: A first communication device. (19) A first communication device according to any one of embodiments (1) to (18), The circuit comprises: If a third data unit is received, the preamble of the third data unit is completely received and after a time margin has elapsed, the fourth data unit is transmitted with interference nulling applied to both the preamble and the payload field; If the third data unit is not received, the fourth data unit is transmitted to the third communication device within a predefined time interval without applying preamble mapping. It is configured as follows: A first communication device. (20) A first communication device according to any one of embodiments (1) to (19), The circuitry is configured to take into account the second configuration information by determining based on the second configuration information: the second communication device transmits one or more data units that fully or partially overlap with the transmission of one or more data units by the first communication device; to which the second communication device transmits one or more fourth communication devices; and Which groups of third and fourth communication devices can be served simultaneously by said first and second communication devices A first communication device. (twenty one) A first communication device according to any one of embodiments (1) to (20), The circuitry is configured to transmit a configuration request requesting the second communication device to transmit the second configuration information. A first communication device. (twenty two) A first communication device according to any one of embodiments (1) to (21), The circuitry is configured to request a synchronous transmission if a time interval between a sounding phase and a communication phase exceeds a predefined threshold. A first communication device. (twenty three) A first communication device according to any one of embodiments (1) to (22), The circuitry is configured to perform beamforming training to determine beamforming weights to use for transmitting a data unit with an interference null. A first communication device. (twenty four) a second communication device configured to communicate with one or more fourth communication devices, receiving first configuration information from a first communication device configured to communicate with one or more third communication devices, the first configuration information including first beamforming configuration information and first time information, where the first time information indicates a duration of an intended transmission from the first communication device to the one or more third communication devices of one or more data units to which the first configuration information applies, or a maximum duration of simultaneous transmission of data units by the first communication device and the second communication device; transmitting second configuration information comprising second beamforming configuration information and second time information, the second time information indicating a duration of an intended transmission of one or more data units to which the second configuration information applies to one or more fourth communication devices; Using the second configuration information, communicate with the one or more fourth communication devices using coordinated beamforming and taking into account the first configuration information. The present invention provides a circuit configured as follows: the communication includes transmitting a second data unit including a preamble and a payload to a fourth communication device; beamforming weights are used to transmit both the preamble and the payload of the second data unit that reduces or minimizes interference to a third communication device; The first communication device transmits to the third communication device a first data unit that at least partially overlaps in time with a transmission of the second data unit from the second communication device to the fourth communication device. A second communication device. (twenty five) A second communication device according to embodiment (24), the circuit is configured to transmit a third data unit to a fourth communication device using an interference null only on a payload of the third data unit if the second configuration information cannot be transmitted; The third configuration information is included in a preamble of the third data unit, the third configuration information indicating a duration of the third data unit and its preamble. A second communication device. (26) A second communication device according to embodiment (25), The circuitry is configured to transmit the third data unit within a predefined interval after the first data unit transmitted by the first device to the third device. A second communication device. (27) The second communication device according to any one of embodiments (24) to (26), The circuitry is configured to transmit a response to an announcement by the first communication device that transmission of a data unit within a current transmission opportunity is feasible with cooperative beamforming. A second communication device. (28) a third communication device configured to communicate with the first communication device, receiving first configuration information comprising first beamforming configuration information and first time information, where the first time information indicates a duration of an intended transmission from the first communication device to the third communication device of one or more data units to which the first configuration information applies and / or a maximum duration of simultaneous transmission of data units by the first communication device and a second communication device configured to communicate with one or more fourth communication devices; Communicating with the first communication device The present invention provides a circuit configured as follows: The communication includes receiving a first data unit transmitted from the first communication device, the first data unit including a preamble and a payload; beamforming weights are used to transmit both the preamble and the payload of the first data unit; Decoding the received first data unit using the first configuration information. A third communication device. (29) A third communication device according to embodiment (28), The circuitry is configured to receive, as part of the first configuration information, an indication of: orthogonal estimation sequences and / or orthogonal pilot sequences are used in the first data unit; which estimated sequence is used in the first data unit; and / or Which pilot sequence is used in the preamble and / or payload of the first data unit A third communication device. (30) A third communication device according to embodiment (28) or (29), The circuitry is configured to decode the first data unit based on one or more of the following: an expanded set of estimation sequences, the estimation sequences in the preamble of the first data unit being orthogonal to the estimation sequences in the preamble of the second data unit; a pilot sequence in a preamble that is orthogonal to a pilot sequence used in transmitting the second data unit; and a pilot sequence in a preamble of the first data unit that is orthogonal to a pilot sequence used in the payload of the first data unit; The estimation sequence and / or the pilot sequence are indicated as part of the first configuration information. A third communication device. (31) A third communication device according to any one of embodiments (28) to (30), The circuit comprises: estimating a first channel from the first communication device to itself based on a first set of estimation sequences; and estimating residual interference from a second communication device configured to communicate with one or more fourth communication devices using coordinated beamforming to the third communication device based on the second set of estimated sequences. It is configured as follows: A third communication device. (32) A third communication device according to any one of embodiments (28) to (31), The circuitry is configured to discard a third data unit received from the second communication device from an end of the first data unit and before an end of the third data unit, and to receive a fourth data unit transmitted by the first communication device to the third communication device. A third communication device. (33) 1. A first communication method for a first communication device configured to communicate with one or more third communication devices, comprising: transmitting first configuration information including first beamforming configuration information and first time information, where the first time information indicates a duration of intended transmission from the first communication device to one or more third communication devices of one or more data units to which the first configuration information applies and / or a maximum duration of simultaneous transmission of data units by the first communication device and a second communication device configured to communicate with one or more fourth communication devices; listening for receipt of second configuration information from the second communication device, where the second configuration information includes second beamforming configuration information and second time information, the second time information indicating a duration of an intended transmission of one or more data units to which the second configuration information applies to one or more fourth communication devices; communicating with the one or more third communication devices using the first configuration information and, if received, taking into account the second configuration information using coordinated beamforming; The communication includes transmitting a first data unit including a preamble and a payload to a third communication device; Beamforming weights are used to transmit both the preamble and the payload of the first data unit that reduces or minimizes interference to a fourth communication device. The first communication method. (34) A second communication method for a second communication device configured to communicate with one or more fourth communication devices, comprising: receiving first configuration information from a first communication device configured to communicate with one or more third communication devices, the first configuration information including first beamforming configuration information and first time information, where the first time information indicates a duration of an intended transmission from the first communication device to the one or more third communication devices of one or more data units to which the first configuration information applies, or a maximum duration of simultaneous transmission of data units by the first communication device and the second communication device; transmitting second configuration information comprising second beamforming configuration information and second time information, the second time information indicating a duration of an intended transmission of one or more data units to which the second configuration information applies to one or more fourth communication devices; communicating with the one or more fourth communication devices using the second configuration information and taking into account the first configuration information using coordinated beamforming; the communication includes transmitting a second data unit including a preamble and a payload to a fourth communication device; beamforming weights are used to transmit both the preamble and the payload of the second data unit that reduces or minimizes interference to a third communication device; The first communication device transmits to the third communication device a first data unit that at least partially overlaps in time with a transmission of the second data unit from the second communication device to the fourth communication device. The second communication method. (35) A third communication method for a third communication device configured to communicate with the first communication device, comprising: receiving first configuration information comprising first beamforming configuration information and first time information, where the first time information indicates a duration of an intended transmission from the first communication device to the third communication device of one or more data units to which the first configuration information applies and / or a maximum duration of simultaneous transmission of data units by the first communication device and a second communication device configured to communicate with one or more fourth communication devices; communicating with the first communication device; The communication includes receiving a first data unit transmitted from the first communication device, the first data unit including a preamble and a payload; beamforming weights are used to transmit both the preamble and the payload of the first data unit; Decoding the received first data unit using the first configuration information. The third communication method. (36) A computer program product that, when executed by a processor, causes the method according to any one of the preceding embodiments (33), (34) and (35) to be performed. A non-transitory computer-readable recording medium. (37) A computer program comprising program code means for causing a computer to carry out the steps of the method according to embodiment (33), (34) or (35), when said computer program is run on a computer.

Claims

1. a first communication device configured to communicate with one or more third communication devices, transmitting first configuration information comprising first beamforming configuration information and first time information, where the first time information indicates a duration of intended transmission from the first communication device to one or more third communication devices of one or more data units to which the first configuration information applies and / or a maximum duration of simultaneous transmission of data units by the first communication device and a second communication device configured to communicate with one or more fourth communication devices; listening for receipt of second configuration information from the second communication device, where the second configuration information includes second beamforming configuration information and second time information, the second time information indicating a duration of an intended transmission of one or more data units to which the second configuration information applies to one or more fourth communication devices; and communicating with the one or more third communication devices using the first configuration information and, if received, taking into account the second configuration information using coordinated beamforming. The present invention provides a circuit configured as described above. The communication includes transmitting a first data unit including a preamble and a payload to a third communication device; Beamforming weights are used to transmit both the preamble and the payload of the first data unit that reduces or minimizes interference to a fourth communication device. A first communication device.

2. 2. A first communication device according to claim 1, The circuitry is configured to use beamforming weights to transmit the first data unit to the third communication device with an interference null that reduces or minimizes interference to one or more fourth communication devices to which the second communication device transmits or intends to transmit a second data unit that at least partially overlaps in time with transmission of the first data unit from the first communication device to the third communication device. A first communication device.

3. 2. A first communication device according to claim 1, The circuitry is configured to announce that the transmission of the data unit within a current transmission opportunity is feasible with cooperative beamforming. A first communication device.

4. A first communication device according to claim 3, the circuitry is configured to transmit the announcement in a data unit or frame prior to or together with the transmission of the first configuration information; The data unit or frame includes identification information of a third communication device for which coordinated beamforming is performed and the second communication device performing coordinated beamforming within the current transmission opportunity. A first communication device.

5. 2. A first communication device according to claim 1, The first beamforming configuration information comprises one or more of the following: a number of spatial streams used by the first communication device to transmit the first data unit to the third communication device; identification information indicative of one or more third communication devices with which the first communication device intends to communicate during the current transmission opportunity and / or a set of one or more third and fourth communication devices that can be simultaneously served by the first and second communication devices; and the maximum number of degrees of freedom, including spatial dimensions and / or spatial streams and / or space-time streams, that can be used by the second communication device to serve the one or more fourth communication devices simultaneously with a transmission from the first communication device to the third communication device; and / or The second beamforming configuration information comprises one or more of the following: a number of spatial streams used by the second communication device to transmit second data units to the fourth communication device; Identification information indicative of one or more fourth communication devices with which the second communication device intends to communicate during the current transmission opportunity or with which it will perform cooperative beamforming, and / or a set of the third and fourth communication devices that may be simultaneously served by the first and second communication devices as part of a subsequent transmission; and the maximum number of degrees of freedom that the first communication device may use to provide services to the one or more third communication devices simultaneously with transmissions from the second communication device to the fourth communication device; A first communication device.

6. 2. A first communication device according to claim 1, The first time information comprises an indication of one or more of the following: a time when the first communication device is expected to transmit an acknowledgment to the third communication device; a time at which the first communication device is expected to receive an acknowledgment from the third communication device in response to transmitting the first data unit; whether and when the acknowledgement request is included in the subsequent first data unit or whether the acknowledgement request is sent separately; Subsequent coordinated beamforming transmissions are initiated synchronously or whether and to what extent transmission of second data units can exceed transmission of said first data units; a length of the first data unit to be transmitted with beamforming weights selected in response to the indication by the first beamforming configuration; and the duration of a sequence of first data units transmitted with beamforming weights selected in response to the indication of the first beamforming configuration, and / or an interframe spatial time; and / or The second time information comprises an indication of one or more of the following: a time at which the second communication device is expected to transmit an acknowledgment to the fourth communication device; a time at which the second communication device is expected to receive an acknowledgment from the fourth communication device in response to transmitting the second data unit; An acknowledgment request is included in a subsequent second data unit, or confirming, if required by the first time information, that a subsequent transmission is made synchronous with the transmission from the first communication device to the third communication device; a length of the second data unit to be transmitted with the beamforming weight indicated by the second beamforming information; A duration of a series of data units transmitted in the beamforming configuration indicated by the second beamforming information, and an interframe spatial time. A first communication device.

7. 2. A first communication device according to claim 1, The circuitry is configured to transmit the first configuration information in a data unit or frame before or after receiving a data unit or frame that includes the second configuration information. A first communication device.

8. 2. A first communication device according to claim 1, The circuitry is configured to synchronize a start of transmission of the first data unit to the third communication device with a start of transmission of a second data unit by the second communication device to the fourth communication device. A first communication device.

9. 2. A first communication device according to claim 1, the circuitry is configured to include in a preamble of the first data unit a number of estimation sequences corresponding to a number of spatial streams; The estimated sequence is different from the estimated sequence included in the preamble of a second data unit by the second communication device. A first communication device.

10. 10. A first communication device according to claim 9, the circuitry is configured to select an estimate sequence from a projection matrix of a number of orthogonal estimate sequences; The number is greater than or equal to the sum of a number of spatial streams used by the first communication device to transmit the first data unit and a number of spatial streams used by the second communication device to transmit the second data unit. A first communication device.

11. 2. The first communication device according to claim 1, The circuitry is configured to include one or more of the following in the first data unit: a pilot sequence orthogonal to a pilot sequence included in a second data unit by the second communication device; a pilot sequence of all streams in a training field of the first data unit, the pilot sequence being orthogonal to the pilot sequences of all streams in a training field of the second data unit; and a pilot sequence in the data portion of the first data unit that is identical to a pilot sequence included in the second data unit A first communication device.

12. A first communication device according to claim 9 or 11, The circuitry is configured to transmit, as part of the first configuration information, an indication of: Whether orthogonal estimation sequences and / or orthogonal pilot sequences are used; Which estimated sequence was selected from the projection matrix, and / or Which pilot sequence is used A first communication device.

13. 2. The first communication device according to claim 1, The circuitry is configured to transmit a preamble of the first data unit and a payload of the first data unit using different beamforming weights. A first communication device.

14. A first communication device according to claim 13, the preamble beamforming weights are configured to reduce or minimize interference to one or more fourth communication devices connected to the second communication device; Payload beamforming weights are configured to reduce or minimize interference to the fourth communication device to which the second communication device transmits the second data unit and / or to improve a communication link with the third communication device to which the first data unit is transmitted. A first communication device.

15. a second communication device configured to communicate with one or more fourth communication devices, receiving first configuration information from a first communication device configured to communicate with one or more third communication devices, the first configuration information including first beamforming configuration information and first time information, where the first time information indicates a duration of an intended transmission from the first communication device to the one or more third communication devices of one or more data units to which the first configuration information applies, or a maximum duration of simultaneous transmission of data units by the first communication device and the second communication device; transmitting second configuration information comprising second beamforming configuration information and second time information, the second time information indicating a duration of an intended transmission of one or more data units to which the second configuration information applies to one or more fourth communication devices; using the second configuration information to communicate with the one or more fourth communication devices using coordinated beamforming taking into account the first configuration information. The present invention provides a circuit configured as described above. The communication includes transmitting a second data unit including a preamble and a payload to a fourth communication device; beamforming weights are used to transmit both the preamble and the payload of the second data unit that reduces or minimizes interference to a third communication device; The first communication device transmits to the third communication device a first data unit that at least partially overlaps in time with a transmission of the second data unit from the second communication device to the fourth communication device. A second communication device.

16. a third communication device configured to communicate with the first communication device, receiving first configuration information comprising first beamforming configuration information and first time information, where the first time information indicates a duration of an intended transmission from the first communication device to the third communication device of one or more data units to which the first configuration information applies and / or a maximum duration of simultaneous transmission of data units by the first communication device and a second communication device configured to communicate with one or more fourth communication devices; Communicating with the first communication device The present invention provides a circuit configured as described above. The communication includes receiving a first data unit transmitted from the first communication device, the first data unit including a preamble and a payload; beamforming weights are used to transmit both the preamble and the payload of the first data unit; Decoding the received first data unit using the first configuration information. A third communication device.

17. 1. A first communication method for a first communication device configured to communicate with one or more third communication devices, comprising: transmitting first configuration information comprising first beamforming configuration information and first time information, where the first time information indicates a duration of intended transmission from the first communication device to one or more third communication devices of one or more data units to which the first configuration information applies and / or a maximum duration of simultaneous transmission of data units by the first communication device and a second communication device configured to communicate with one or more fourth communication devices; listening for receipt of second configuration information from the second communication device, where the second configuration information includes second beamforming configuration information and second time information, the second time information indicating a duration of an intended transmission of one or more data units to which the second configuration information applies to one or more fourth communication devices; communicating with the one or more third communication devices using the first configuration information and, if received, taking into account the second configuration information using coordinated beamforming; The communication includes transmitting a first data unit including a preamble and a payload to a third communication device; Beamforming weights are used to transmit both the preamble and the payload of the first data unit that reduces or minimizes interference to a fourth communication device. A first communication method.

18. A second communication method for a second communication device configured to communicate with one or more fourth communication devices, comprising: receiving first configuration information from a first communication device configured to communicate with one or more third communication devices, the first configuration information including first beamforming configuration information and first time information, where the first time information indicates a duration of an intended transmission from the first communication device to the one or more third communication devices of one or more data units to which the first configuration information applies, or a maximum duration of simultaneous transmission of data units by the first communication device and the second communication device; transmitting second configuration information comprising second beamforming configuration information and second time information, the second time information indicating a duration of an intended transmission of one or more data units to which the second configuration information applies to one or more fourth communication devices; using the second configuration information to communicate with the one or more fourth communication devices using coordinated beamforming taking into account the first configuration information; The communication includes transmitting a second data unit including a preamble and a payload to a fourth communication device; beamforming weights are used to transmit both the preamble and the payload of the second data unit that reduces or minimizes interference to a third communication device; The first communication device transmits to the third communication device a first data unit that at least partially overlaps in time with a transmission of the second data unit from the second communication device to the fourth communication device. A second communication method.

19. A third communication method for a third communication device configured to communicate with the first communication device, comprising: receiving first configuration information comprising first beamforming configuration information and first time information, where the first time information indicates a duration of an intended transmission from the first communication device to the third communication device of one or more data units to which the first configuration information applies and / or a maximum duration of simultaneous transmission of data units by the first communication device and a second communication device configured to communicate with one or more fourth communication devices; communicating with the first communication device; The communication includes receiving a first data unit transmitted from the first communication device, the first data unit including a preamble and a payload; beamforming weights are used to transmit both the preamble and the payload of the first data unit; Decoding the received first data unit using the first configuration information. A third communication method.

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

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