Access points and station

Abstract

A first access point is configured to communicate with at least one associated first station and configured to coordinate transmissions at least with a second access point that is part of a common coordination cluster with the first access point and that is configured to communicate with at least one associated second station. The first access point comprises circuitry configured to transmit a channel request to the at least one associated first station and / or the second access point on a first set of one or more first channels, listen to channel responses from the at least one first station and / or the second access point, and transmit data to the at least one first station on at least the primary first channel if a channel response has been received from the at least one first station on at least the primary first channel.

Description

ACCESS POINTS AND STATIONBACKGROUNDFIELD OF THE DISCLOSURE

[0001] The present disclosure relates to first and second access points and to a first station, in particular for use in coordinated transmission in a cooperation cluster comprising two or more access points having at least partly overlapping bandwidths.DESCRIPTION OF RELATED ART

[0002] Neighboring access points (APs) may have fully or partially overlapping bandwidths.When this is the case and no cooperation is in place, the two APs compete against each other and can block at least part of each other’s transmission bandwidths. AP cooperationcan improve this behavior, however the transmission requirements of the stations (STAs) in different BSSs change dynamically and may not be known a priori outside of their basic service set (BSS). Typically, AP cooperation schemes assume a negotiation phase at the beginning of each obtained transmit opportunity (TXOP), in which the current transmit requirements are exchanged.

[0003] The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor(s), to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.SUMMARY

[0004] It is an object to set up and enable coordinated transmission in a coordination cluster more efficiently and with less overhead.

[0005] According to an aspect there is provided a first access point configured to communicate with at least one associated first station and configured to coordinate transmissions at least with a second access point that is part of a common coordination cluster with the first access point and that is configured to communicate with at least one associated second station, the first access point comprising circuitry configured to: transmit a channel request to the at least one associated first station and / or the second access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the first set of first channels at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channels, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request;listen to channel responses from the at least one first station and / or the second access point; and transmit data to the at least one first station on at least the primary first channel if a channel response has been received from the at least one first station on at least the primary first channel.

[0006] According to a further aspect there is provided a second access point configured to communicate with at least one associated second station and configured to coordinate transmissions at least with a first access point that is part of a common coordination cluster with the second access point and that is configured to communicate with at least one associated first station, the second access point comprising circuitry configured to: listen to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the first set of first channels at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channels, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request; transmit a channel response on at least a primary second channel of a second set of second channels operated by the second access point and / or a second subset of channels as indicated within the channel response information if detected as idle; and establish a frame exchange with the at least one second station on at least the primary second channel if the primary second channel has been indicated in the first subset and a channel response has been transmitted to the first access point on at least the primary second channel.

[0007] According to a further aspect there is provided a first station configured to communicate with an associated first access point that is configured to coordinate transmissions in a common coordination cluster at least with a second access point that is configured tocommunicate with at least one associated second station, the first station comprising circuitry configured to: listen to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request; transmit a channel response to the first access point on at least the primary first channel if the primary first channel has been indicated in the first subset and if the primary first channel is idle; and listen to data transmitted by the first access point on at least the primary first channel if a channel response has been transmitted to the first access point on at least the primary first channel.

[0008] According to still further aspects a computer program comprising program means for causing a computer to carry out the steps of the method disclosed herein, when said computer program is carried out on a computer, as well as a non -transitory computer-readable recording medium that stores therein a computer program product, which, when executed by a processor, causes the method disclosed herein to be performed are provided.

[0009] Embodiments are defined in the dependent claims. It shall be understood that the disclosed methods, the disclosed computer program and the disclosed computer-readable recording medium have similar and / or identical further embodiments as the claimed access points and stations and as defined in the dependent claims and / or disclosed herein.

[0010] One of the aspects of the disclosure is to provide a coordinated transmission scheme enabling coordinated transmission by two or more APs within a coordination cluster, which can be performed without an additional negotiation phase at the start of an obtained TXOP if the primary channels inside the at least partly overlapping operating bandwidths occupy different positions. AP cooperation can thus be performed without excessive additional overhead of setting up the transmission parameters.

[0011] In the context of the present disclosure, a coordination cluster is understood as a group of APs, which can exchange communication parameters in order to enable a coordinated transmission. An example of the APs within the cluster is as follows: Whenever an AP within a coordination cluster obtains a transmit opportunity to exchange data with one or more non-AP STAs associated with itself, it may coordinate the use of time / frequency and / or spatial resources with one or more APs within the cooperation cluster according to exchanged communication parameters.

[0012] Further, in the context of the present disclosure, the expression "channels operated by a certain STA (AP or non_AP STA)" includes or shall be understood as "channels in the operating bandwidth of the respective STA (AP or non_AP STA)".

[0013] The foregoing 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.BRIEF DESCRIPTION OF THE DRAWING

[0014] A more complete appreciation of the disclosure and many of the attendant advantages thereof 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, wherein:Fig. 1 shows a diagram illustrating the relation between primary and secondary channels in 160 MHz bandwidth as currently specified in the standard.Fig. 2 shows a diagram of the legacy behavior of two neighboring APs.Fig. 3 shows a diagram of the behavior of two neighboring APs according to Extremely High Throughput (EHT).Fig. 4 shows diagrams of two examples of the operating channels of two neighboring APs.Fig. 5 shows a diagram of an embodiment of a communication scheme according to the present disclosure using a TXOP over shared channel for the fully overlapped case as shown in Fig. 4A.Fig. 6 shows an example of the format of the channel request.Fig. 7 shows two examples of the format of the channel response.Fig. 8 shows a diagram of an embodiment of a communication scheme according to the present disclosure using a TXOP over shared channel for the partially overlapped channel case shown in Fig. 4B.Fig. 9 shows an example of used channels for a partially overlapped channel case.Fig. 10 shows an example of an underutilized spectrum with static allocation.Fig. 11 shows an example of dynamic indication.Fig. 12 shows a diagram of an embodiment of a communication scheme according to the present disclosure using a TXOP over multiple channels with delayed start.Fig. 13 shows a diagram of an embodiment of a communication scheme according to the present disclosure using a response in case of busy primary second channel.Fig. 14 shows a flow chart of an embodiment of a first communication method according to the present disclosure.Fig. 15 shows a flow chart of an embodiment of a second communication method according to the present disclosure.Fig. 16 shows a flow chart of an embodiment of a third communication method according to the present disclosure.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, Fig. 1 shows a diagram illustrating the relation between primary and secondary channels in 160 MHz bandwidth as currently specified in the baseline IEEE 802.11 standard. To operate over wide bandwidths with manageable complexity, the bandwidths are considered logically split in 20 MHz chunks and the concepts of primary and secondary channels are introduced.

[0016] All the STAs associated with an AP need to listen to at least the primary 20 channel, indicated as P20 in Fig. 1. If the STAs can operate over larger bandwidths, then these will operate hierarchically over the primary 40 MHz channel (P40) or primary 80 MHz channel (P80) or primary 160 MHz (not shown). The primary 40 MHz channel P40 is the 40 MHz channel that includes the primary 20 MHz channel P20 and is further constrained on the busy / idle state before the transmission time. The other channels of the bandwidth are called secondary channels, which may be 20 MHz channels (S20) or secondary 40 MHz channels (S40) or a secondary 80 MHz channel (S80).

[0017] When two neighboring APs are operating over overlapping bandwidths, then these APs will at least partly block each other’s transmissions as depicted in Fig. 2 showing a diagram of the legacy behavior of two neighboring APs AP1 and AP2. In this example, AP1 can operate over 80 MHz and AP2 can operate over 20 MHz. With legacy behavior, if AP2 is actively transmitting over its channel, AP1 can at most use its primary 20 MHz channel P20, while the secondary 20 MHz channels S20 are blocked as the primary 40 MHz channel is blocked.

[0018] Fig. 3 shows a diagram of an exemplary behavior of two neighboring APs AP1 and AP2 according to Extremely High Throughput (EHT). EHT has defined a puncturing operation to improve channel utilization in such scenarios. This allows AP1 and the stations associated with it to puncture the secondary 20 MHz channel (the first S20 channel of AP1) over which AP2 transmits and effectively use 60 MHz of bandwidth. The puncturing operation defined so far is, however, static and does not consider any cooperation between the APs. Furthermore, only a fixed number of puncturing patterns have been defined. Therefore, if the scheme were to be used by APs which operate over large bandwidths, without cooperation it may have limited benefits.

[0019] For the following explanations of various embodiments of the APs and STAs according to the present disclosure, several APs shall be considered as part of a cooperation cluster, which is a set of APs that may coordinate their transmission to some extent, e.g., to exchange control, management or scheduling between themselves. One AP, further referred to as AP1, has traffic for at least one STA (further referred to as STA1) associated to itself and gains a TXOP to transmit this traffic.

[0020] A first aim is that AP1 enables the start of a parallel transmission over a subset of its operating channels, for one or more APs within the cooperation cluster, during the time of its TXOP. If none of the other APs in the cooperation cluster are ready to transmit or have idle channels, AP1 may use the whole set of idle operating channels for the data exchange with the associated STA, for which it obtained the TXOP. If any of the APs in the cooperation cluster has data to transmit and has at least its primary P20 channel idle, a data exchange can happen simultaneously with the one from AP1 under conditions indicated by the AP1 and / or the previously performed coordination negotiation.

[0021] Another aim is that the delay in the start of the data exchange to STA1 is similar to the one in case when no shared TXOP is performed, as long as at least the primary P20 channel of STA1 is idle and AP1 correctly determines that this condition is true.

[0022] General assumptions are that AP1 operates over a first set of first channelscomprised of one primary first channel and one or more secondary first channels andthat AP2 operates over a second set of second channels ® comprised one primary second channels P(2)and one or more secondary second channels S® . The first set and the second set of channels overlap at least partially and at least the primary channelsand P(2)of the two APs are different. Fig. 4 shows diagrams of two examples of the operating channels of AP1 and AP2, for which the schemes defined herein are applicable, wherein according to Fig. 4A the first second sets of channels fully overlap and according to Fig. 4B the first second sets of channels partially overlap. In Fig. 4 the channels are represented with the smallest size, i.e. , 20 MHz, however larger bandwidths, e.g. 40 MHz or 80 MHz, are possible as well.

[0023] The schemes disclosed herein make most sense if the primary channel of any of the basic service sets (BSSs) is in the set of operating channels of the other BSS. Otherwise, the two BSSs could perform well simultaneously with at most sacrificing some part of their channels. Channel access would not be affected by the parallel operation of the two.

[0024] It shall be noted that to keep the description clear, only two APs are considered in the cooperation cluster (AP1 and AP2). More than two APs in the coordination cluster may be used as well, which will be briefly discussed below.

[0025] Several modifications are proposed to the known scheme. With respect to the TXOP request message, the transmitted bandwidth as well as requested channels and messages from the associated STAs and the cooperation APs may be revised with respect to the current specification. AP1 should choose the channels over which it should receive a response such that it can simultaneously obtain information of whether the one or more STAs for which the TXOP was obtained have idle channels and can receive the intended transmission and obtain information of whether one or more APs in the coordination clusters has queued data and idle channels on which to transmit. The response to the TXOP request may be made such that the spectrum is effectively used and protected. The coordination information may be defined and negotiated. The transmission schemes should support the operation. Thus, support for dynamic puncturing may be defined so that AP1 is able to puncture some channels based on the TXOP request configuration and / orcoordination configuration. AP2 should also be able to determine the position of the channels which it shall not use based on their relative location within the bandwidth of AP1.

[0026] More specifically, an embodiment of the proposed communication scheme may be as follows. AP1 sends a TXOP request frame (herein also referred to as “channel request” and depicted as skRTS (“some kind of ready to send (RTS)”)) to the STA for which the TXOP was obtained and to one or more APs in the cooperation clusters such that:• The TXOP request frame is sent over a set of operating channels inside the first set of channels, which are idle and are chosen such that they include the set of operating channels of the intended STAs and one or more channels corresponding to channels within ®;• the set of channels over which the STA responds includes the primary first channel of the setat AP1 , but excludes the primary second P(2)of the setof AP2; and• the set of channels over which AP2 can respond in case it has traffic for downlink (DL) includes P(2)but potentially excludes P(1).

[0027] Excluding from the response of AP2 is not fully necessary but highly recommended. In case of static allocations for STA1 and AP2, the response of AP2 can also includeas the AP1 can detect that there is activity from AP2, by determining activity over P(2)= S3(1). However, in this case, there should not be an overlap in the set of channels over which STA1 and AP2 respond and will operate in the follow-up TXOP, besides the P(1). Furthermore, a false detection of activity in the primary channel from associated STAs can lead to transmissions from AP1 to STA1 which cannot be decoded by STA1 and thus make an inefficient medium utilization.

[0028] Fig. 5 shows a diagram of an embodiment of a communication scheme according to the present disclosure using a TXOP over shared channel for the fully overlapped case as shown in Fig. 4A. In Fig. 5 the following notations have been used: skRTS means some kind of RTS, which represents a channel request and may be implemented as TXOP request frame. P(2)= S3(1)is used as an example. skCTS means some kind of clear to send(CTS), which represents a channel response and may be implemented as TXOP response frame, e.g., as CTS or an extension of CTS. EoTX means end of transmission, which represents a transmission end indication and may be implemented as CF-END frame on all used channels or a TXOP return, sent when channel availability allows.

[0029] ch bitmap (channel bitmap) is an optional field indicating the busy / idle status of the channels indicated within the skRTS. If it is not present, AP1 does a static allocation of the channels on which STA1 can respond. There are two important cases in which “ch bitmap” brings a clear advantage: i) when the AP2 cannot use the overlapped channels and ii) when a large overlap between the set of overlapping channels exists and AP1 may do a dynamic selection of the channels to be used by STA1 and AP2.

[0030] The operation depicted in Fig. 5 is as follows: The skRTS 10 is sent over the bandwidth which includes the largest number of available channels inin order to reserve the medium for the duration of the TXOP. The skRTS 10 indicates the channels over which STA1 and, potentially APs in the cooperation cluster, can respond.

[0031] is idle, STA1 responds, e.g., by sending a skCTS 11 , to the AP within short interframe space (SIFS) on the set of channels that were indicated within the skRTS, in the user field corresponding to STA1 , if these were determined to be idle. If the optional use of ch bitmap 12 is allowed, STA1 may indicate the busy / idle status of all channels on which the skRTS 10 was sent and are within the operating bandwidth of STA1.

[0032] If P(2)is idle, AP2 sends an skCTS 13 on at least the set of channels that AP1 has indicated for potential AP2 response, under the condition that these are idle. It is similar to the standard CTS response to an Mll-RTS, with the following exceptions; i) the standard does not define AP-AP interactions and ii) AP2 may not respond on P(1), which is a requirement in standard operation. AP2 may send a response over a larger bandwidth than the one indicated by AP1 if its operating bandwidth is only partially overlapping, e.g., as shown in Fig. 4B, and the channels are idle. This is further elaborated below.

[0033] If AP1 receives a response from STA1 and AP2 on their respective primary channels, AP1 can start a data transmission 14 within SIFS from the reception of the skCTS 11 , 13 on at least and optionally on a set of secondary channels. The set of secondary channels contains: i) the set of channels indicated in the user field of skRTS, corresponding to STA1 , over which an skCTS was received, and ii) the set of channels indicated in the channel bitmap field of the skCTS as being available and idle (if present). A data transmission can start within SIFS from AP2 to STA2 on at least P(2)and the idle secondary channels on which skCTS was transmitted.

[0034] If AP1 receives a response 11 from STA1but does not receive an skCTS 13 from AP2 on P(2)= S3(1), AP1 may start, if STA1 has indicated further idle secondary channels in the channel bitmap field 12, a transmission over all the channels indicated as available and idle in the channel bitmap, which will be further elaborated below. The DL PPDll 14 from AP1 indicates the used channels in the preamble. If STA1 indicated idle channels in the ch bitmap 12, it should also be ready to receive over these channels. The additional channels are protected by the initial skRTS.

[0035] The response 13 from AP2 should be over the largest possible bandwidth that AP2 intends to use, such as to protect the TXOP in BSS2.

[0036] The data exchanges between AP1 and STA1 (data transmission 14) and between AP2 and STA2 (data transmission 15), respectively, should be done such that there is no interference in the adjacent channels. To achieve this, transmission schemes such as puncturing and coordinated OFDMA can be used. The latter is more spectrally efficient but is more complex to implement, particularly due to synchronization requirements.

[0037] Fig. 6 shows an example of the format of the channel request (skRTS). The skRTS can be implemented similarly as an Mll-RTS, containing one or more (preferably all) of the following fields:• TA: transmitter address, identifying the transmitter of the packet;• RA: receiver address, identifying the receiver of the packet;• Common Field: indicating at least the bandwidth over which the skRTS is sent; and• User field: indicating the resource units over which the users identified in the user field should respond with a skCTS.

[0038] In setting up the skRTS, the following aspects may be considered: The TA could be set to an identifier of the cooperation AP cluster, rather than an individual address of AP1. A reason for this is that the CTS response should contain this field. Consequently, also the CTS from AP2 should contain it. On the other hand, the CTS from AP2 acts as a CTS-to-self so it should contain a transmitter identifier field in the form of a TA, which is also understood in its own BSS. Thus, by defining a TA, which is understood by the STAs, associated with each of the two APs (and is previously announced as such), a unified CTS frame format can be kept, which makes the processing easy.

[0039] Further, the receiver address (RA) should be kept as broadcast address. The user fields indicate, for STA1 , an identifier of STA1 , and the primary P20 channel plus the additional channels on which STA1 should respond: at least P(1), plus optionally a set of secondary channels (except for P(2)=Additionally, it should be indicated if the channel bitmap should be included in the response or not.

[0040] An identifier of AP2 or an identifier of a coordination cluster plus the channels on which AP2 can respond (at least P(2)= S3(1)) should be included, to enable AP2 to start obtain the channel and start a data transmission in case AP2 has queued data.

[0041] With respect to a regular MU-RTS, the following elements are new:• Contrary to a regular RTS or MU-RTS, it allows a STA to respond on a secondary channel only. This should however happen under several conditions: If the STA is an AP STA and has established some coordination with AP1 ; or if the channel corresponding to the primary P20 channel of AP1 is within the set of operating channels of the respective STA and the STA can decode the data units on this channel and use it to align the subsequent response.• Different definition of the TA field• Addressing an AP as part of the Mll-RTS• The skRTS is transmitted, in addition to the channels in the operating bandwidth of the non-AP STA, over one or more channels over which AP2 operates, including the primary channel of this AP2 (in currently defined transmission schemes, if there is a chance that two APs simultaneously transmit, the initial TXOP request frame would to be punctured from the beginning, based on statically defined patterns)• Currently, the indicated Rll on which a STA can respond to an AP is a primary Px channel, with x corresponding to the STA bandwidth (p20, P40, ...). In implementations, the definition may be changed from a specific primary channel to a channel bitmap with 20 MHz resolution or an additional field indicating one or more channels to be punctured in the response.

[0042] Two formats for the implementation of skCTS can be used as depicted in Fig. 7 showing two examples of the format of the channel response. Fig. 7A shows essentially the legacy format, however with a different meaning of the RA field. Fig. 7B contains a control field, which can include the “channel bitmap” in case of an associated non-AP STA or the “transmit indication” in case of an AP inside an agreed cooperation cluster.

[0043] With respect to a regular CTS, the following elements are new:• Definition of the RA field: For the AP2, the CTS response (or skCTS) acts as a CTS to self. The current standard rules imply that, if the first frame sent within a TXOP is a CTS, then the RA field should contain the identifier of the AP, which in this case needs to be the identifier of AP2. At the same time the CTS response of STA1 needs to contain the identifier of the AP, which has sent the RTS, i.e., AP1. Thus, by defining a common TA for both APs (as part of a coordination phase which could be performed beforehand) the problem can be solved. An implementation, using the regular CTS format is depicted in Fig. 7A.• Additional optional contents of an skCTS (as compared to a regular CTS), are in a CTRL field included in the skCTS format depicted in Fig. 7B. It includes “ch bitmap”, particularly in the case it is sent by a STA associated with AP1 , and “TXJnd”, which may contain additional information on the queued traffic, for whichAP2 would use the shared TXOP. Among this information, TID or duration or urgency could be used for scheduling purposes. An example of how to use the TXJnd field is given below.

[0044] The format of the skCTS may be the same for all responding STAs (i.e., both STA1 and AP2). In case AP1 or any of the STA1 or AP2 can use both, then it should be indicated which of the two formats should be used in the channel response. The format of the PPDll carrying this frame should have legacy format.

[0045] When sending the skCTS, AP2 should ensure that the transmission start of the skCTS is within a predefined interval from the reception of the skRTS. It should further perform carrier frequency offset and symbol clock error pre-correction such that the symbols received at AP1 from STA1 and AP2 are aligned, and the offsets are within predefined bounds.

[0046] Since the data transmission is on non-overlapping channels, the TXOP can be seen as organized in two independent sub-TXOPs. Therefore, a transmission end indication, referred to as EoTX 16, 17 (see Fig. 5) herein, can be seen as an optional tool. However, depending on the channel width and the amount of time that AP2 ends up effectively using the selected channel configuration, it can be beneficial to introduce mechanisms that enable AP2 to indicate to AP1 the end of the transmission on the respective “shared” channels.

[0047] In an embodiment, at the beginning of any PPDll, AP1 may add an indication, indicating to AP2 that the latter can send a control message within SIFS (which could be sent simultaneously with an Ack from STA1). For this, AP1 ensures that a PPDll from AP2 can be aligned with a response from STA1 and indicates transmission requirements for the two PPDUs. AP2 after finishing the data exchange with STA2 listen to P(2)in order to decode this indication.

[0048] In another embodiment, AP1 indicates an interval for which it “lends” the respective channels to AP2. At the end of this interval, if channel conditions allow, AP2 sends the EoTXover at least P(1)and P(2)indicating that it has finished the data exchange or if it has more data in queue and requests more shared channel time.

[0049] AP2 may indicates channel(s) are free, e.g., in an EoTX implemented as a CF-End type frame, or STAs in BSS2 sees the channel free and contend. This may lead to interference from STAs in the BSS of AP2 which may send RTS over channels that are overlapped with AP1 and currently in use. To circumvent this problem, AP2 can additionally commit to protecting = P^2e.g., not to respond to CTS on the respective channels and / or indicate within the EoTX that no RTS should be sent on the particular channels until the end of the TXOP.

[0050] With the proposed approach, AP2 can also start a TXOP over a larger bandwidth than the one indicated by AP1 , in case the further channels are idle and the intended receive STAs support the operation. The conditions is, however, that the channels over which skCTS is transmitted excludeand any other set of secondary channels indicated for STA1 transmission.

[0051] The advantage of such a scheme is that one of the APs can start a transmission without having to contend for the particular TXOP and, at the same time, AP1 does not need to sacrifice too many of its own resources, except for the secondary channel corresponding to the primary channel of AP2 since there already exist a number of secondary non overlapping channels that AP2 can access, if free. The reason why the operation is possible is that an skCTS, when transmitted by AP2, is similar to a CTS2self in format and functionality.

[0052] Fig. 8 shows a diagram of an embodiment of a communication scheme according to the present disclosure using a TXOP over shared channel for the partially overlapped channel case shown in Fig. 4B. The current standard allows a TXOP to be started by a CTS2self so the operation in Fig. 8 is similar to what is currently allowed, with the only exception being that there was no contention for the frame.

[0053] Fig. 9 shows an example of used channels for a partially overlapped channel case, in particular details of the channels that are used by the skRTS and skCTS for an example in which AP1 has an operating BW of 80 MHz and AP2 has an operating BW of 160 MHz.

[0054] In an embodiment, AP1 indicates that AP2 is allowed to respond over all S^ , if idle but may be required to restrict channel for the further data transmission as indicated by AP1 in a subsequent PPDll. This may be particularly useful if there exists a large overlap between the operating channels of the two APs, e.g., | > 4 . Such a scheme canutilize the spectrum more effectively than one in which the secondary channels for STA1 are indicated statically within the skRTS, because some of the indicated channels lying inbusy for STA1 but not for AP2, or vice versa so they would end up not being used even though they could be.

[0055] Fig. 10 shows an example of an underutilized spectrum with static allocation. STA1 is requested to respond over P40 of AP1 , AP2 can respond over S40 of AP1. S20 within P40 of AP1 is however busy so that STA1 cannot use it. This channel is idle at AP2, but this is not allowed to respond over it due to the static allocation, thus it remains unoccupied. Therefore, a scheme in which the secondary channels are indicated statically would be mostly appropriate for legacy STAs or STAs that are capability limited.

[0056] Fig. 11 shows an example of a dynamic indication. The operation is depicted in Fig. 12 showing a diagram of an embodiment of a communication scheme according to the present disclosure using a TXOP over multiple channel with delayed start.

[0057] STA1 indicates the idle channels via the “ch bitmap” field 12. AP2 indicates the idle channels in S^h ^ch by transmitting the skCTS 13. AP1 based on the traffic it needs to transmit may choose one or more additional secondary channels for the transmission to STA1 , for example S20 of P40 of AP1 in the example depicted in Fig. 11.

[0058] Decoding the preamble of the transmitted PPDll from AP1 to STA1 (essentially the SIG fields) to determine the Rll allocation of the respective PPDll and then transmit such thatit does not perturb the respective channels may lead to long inactivity interval between the CTS and the start of the AP2 data transmission. Therefore, in the embodiment shown in Fig. 12, AP2 performs first energy detection (indicated as channel sensing CS 18) in all the channels for an interval that covers the transmission start from AP1. Based on this, it determines the channels which AP1 has chosen to use. AP2 will consequently choose the remaining available channels out of the channels on which it has transmitted skCTS.

[0059] Fig. 13 shows a diagram of an embodiment of a communication scheme according to the present disclosure using a response in case of busy primary second channel.

[0060] If P(2)= is busy, then AP2 should not start a data transmission directly, regardless of the state of the other channels over which it can transmit. If any ofe ® are idle and AP2 has traffic to transmit, AP2 may send an skCTS 13 to AP1 , which indicates the need to transmit over the respective channels. This may prompt AP1 to reattempt TXOP sharing at a later time during the TXOP, e.g., when it finished the data transmission 14 to STA1 or when it requests Acks19 from STAI .

[0061] If AP1 does not receive a response from AP2 on P(2)= S3(1)the follow-up transmission 14 can be on more channels than STA1 was requested to respond on. The channels can be selected as channels in the operating bandwidth of STA1, and on which an skRTS was previously sent. It is preferable that STA1 is capable of sending the ch bitmap indication to ensure that the respective channels are indeed idle at STAI . Thus, the data transmission will be over all channels indicated by STA1, if a channel bitmap field 12 was included or on all channels on which STA1 operates and AP1 sent an skRTS 11. If a response is received on a channelbut not on P(2)= S3(1)TXOP sharing may reattempted. If no response is received on any ofthen AP1 may terminate the TXOP with, e.g.,CF-End after a successful data transmission to STAI . The use of “Txjnd” is optional. A regular CTS sent onbut not on P(2)can be used as an indication thatAP2 has queued traffic to transmit and AP1 should try to assist if possible.

[0062] As part of the coordination the following information may be exchanged for the proposed schemes to work: APs should exchange information about their operating bandwidths, positions of the primary channels, as well as puncturing patterns that can be potentially used. Depending on this information, the primary channels can be switched such that a more efficient spectrum utilization can be achieved. The common transmitter address should be established for the cooperation cluster. Scheduling intervals, in which the coordination schemes can occur, should be exchanged.

[0063] The operation in case of more than two APs in a cooperation cluster may be as follows. The primary P20 channels of all APs should be different. The APs, which have not obtained the initial TXOP can only respond over the primary Px channel as negotiated as part of the coordination scheme. AP1 may allow all APs in the cooperation cluster to respond or down-select, based on traffic information exchanged within the scheduling interval setup and the current traffic requirements for the STA t intends to serve. Depending on the response and optionally further information within the “TXJnd” field, AP1 can select only one or less APs than the total number of APs in the cooperation cluster. The APs, which have not obtained the initial TXOP, should first detect the channels used by AP1 , before starting a potential data transmission to their own STAs.

[0064] 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 the spirit or essential characteristics thereof. Accordingly, the disclosure of the present disclosure is intended to be illustrative, but not limiting of the scope of the disclosure, as well as other claims. The disclosure, including any readily discernible variants of the teachings herein, defines, in part, the scope of the foregoing claim terminology such that no inventive subject matter is dedicated to the public.

[0065] Fig. 14 shows a flow chart of an embodiment of a first communication method 100 according to the present disclosure, which may be carried out by a first access point that configured to communicate with at least one associated first station and configured to coordinate transmissions at least with a second access point that is part of a commoncoordination cluster with the first access point and that is configured to communicate with at least one associated second station.

[0066] In a first step 101 , a channel request is transmitted to the at least one associated first station and / or the second access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point. The first set of first channels is at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channel. The channel request includes channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request.

[0067] In a second step 102, the first access point listens to channel responses from the at least one first station and / or the second access point. In a third step 103, data are transmitted to the at least one first station on at least the primary first channel if a channel response has been received from the at least one first station on at least the primary first channel.

[0068] Fig. 15 shows a flow chart of an embodiment of a second communication method 200 according to the present disclosure, which may be carried out by a second access point that is configured to communicate with at least one associated second station and configured to coordinate transmissions at least with a first access point that is part of a common coordination cluster with the second access point and that is configured to communicate with at least one associated first station. In a first step 201 , the second access point listens to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point. In a second step 202, a channel response is transmitted on at least a primary second channel of a second set of second channels operated by the second access point and / or a second subset of channels as indicated within the channel response information if detected as idle. In a third step 203, a frame exchange is established with the at least one second station on at least the primary second channel if the primarysecond channel has been indicated in the first subset and a channel response has been transmitted to the first access point on at least the primary second channel.

[0069] Fig. 16 shows a flow chart of an embodiment of a third communication method 300 according to the present disclosure, which may be carried out by a first station that is configured to communicate with an associated first access point that is configured to coordinate transmissions in a common coordination cluster at least with a second access point that is configured to communicate with at least one associated second station. In a first step 301 , the second access point listens to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point. In a second step 302, a channel response is transmitted to the first access point on at least the primary first channel if the primary first channel has been indicated in the first subset and if the primary first channel is idle. In a third step 303, the second access point listens to data transmitted by the first access point on at least the primary first channel if a channel response has been transmitted to the first access point on at least the primary first channel.

[0070] In summary, according to the present disclosure embodiments of a coordinated transmission scheme are presented, which can be performed without an additional negotiation phase at the start of an obtained TXOP, under the assumption that the primary channels inside the overlapping operating bandwidths occupy different positions. AP cooperation can thus be performed more efficiently without excessive additional overhead of setting up the transmission parameters.

[0071] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may 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.

[0072] In so far as embodiments of the disclosure have been described as being implemented, at least in part, by software-controlled data processing apparatus, it will be appreciated thata non-transitory machine-readable medium carrying such software, such as an optical disk, a magnetic disk, semiconductor memory or the like, is also considered to represent an embodiment of the present disclosure. Further, such a software may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0073] The elements of the disclosed devices, apparatus and systems may be implemented by corresponding hardware and / or software elements, for instance appropriated circuits. A circuit is a structural assemblage of electronic components including conventional circuit elements, integrated circuits including application specific integrated circuits, standard integrated circuits, application specific standard products, and field programmable gate arrays. Further a circuit includes central processing units, graphics processing units, and microprocessors which are programmed or configured according to software code. A circuit does not include pure software, although a circuit includes the above-described hardware executing software.

[0074] It follows a list of further embodiments of the disclosed subject matter:1 . First access point configured to communicate with at least one associated first station and configured to coordinate transmissions at least with a second access point that is part of a common coordination cluster with the first access point and that is configured to communicate with at least one associated second station, the first access point comprising circuitry configured to: transmit a channel request to the at least one associated first station and / or the second access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the first set of first channels at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channels, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request;listen to channel responses from the at least one first station and / or the second access point; and transmit data to the at least one first station on at least the primary first channel if a channel response has been received from the at least one first station on at least the primary first channel.2. First access point according to embodiment 1 , wherein the circuitry is configured to indicate in the first subset of first channels the primary first channel of the first access point and to indicate in the second subset of first channels a primary second channel of the set of second channels operated by the second access point.3. First access point according to embodiment 2, wherein the first channels included in the first subset are different from the primary second channel and optionally from the secondary second channels corresponding to the channels included in the second subset of first channels, and / or wherein the one or more first channels included in the second subset are different from the primary first channel and optionally from one or more of the secondary first channels included in the first subset.4. First access point according to any preceding embodiment, wherein the circuitry is configured to transmit data to the at least one first station on the primary first channel and one or more secondary first channels included in the first subset on which a channel response has been received from the at least one first station and / or on one or more first channels which have been indicated in the channel response by the at least one first station as idle and / or one or more first channels operated by the first station, which correspond to second channels on which a channel response from the second access point has not been received or has not been correctly decoded.5. First access point according to any preceding embodiment, wherein the circuitry is configured to not transmit data to the at least one first station on at least the first channel corresponding to the primary second channel if a channel response has been received by the first access point from the second access point on that channeland / or on one or more first channels corresponding to secondary second channels on which the first access point has received a channel response from the second access point.6. First access point according to any preceding embodiment, wherein the circuitry is configured to transmit a new channel request after receipt of a channel response from the second access point on one or more secondary second channels but not on the primary second channel.7. First access point according to any preceding embodiment, wherein the circuitry is configured to include an indication into the channel request of a time interval from which the second access point can use the first channels and optionally expects an indication at the end of this period regarding whether there is a need for more transmission time or not.8. First access point according to any preceding embodiment, wherein the circuitry is configured to transmit, at the end of a transmission of data to the at least one first station, a transmission end indication to the second access point on the primary second channel or on the primary first channel and the primary second channel once the primary second channel and the primary first channel are idle for a predefined time interval, the transmission end indication indicating that the coordinated transmission has ended.9. First access point according to any preceding embodiment, wherein the circuitry is configured to obtain and / or negotiate, for all access points within the common coordination cluster, information on the primary channels of the respective set of channels operated by the respective access point and information on one or more of: operating bandwidths, supported puncturing patterns, common transmitter address of the coordination cluster, and scheduling intervals in which the coordinated transmission may occur10. First access point according to any preceding embodiment, wherein the circuitry is configured to set the transmitter address of the channel request to a common transmitter address of the coordination cluster.11. First access point according to any preceding embodiment, wherein the first and second subsets of channels are chosen such that the resulting channels on which the transmission to the first station and the second station, respectively, are performed over a set of channels corresponding to supported puncturing patterns.12. First access point according to any preceding embodiment, wherein the circuitry is configured to transmit the data unit containing the channel request in scheduling intervals, negotiated with the access points within the coordination cluster.13. First access point according to any preceding embodiment, wherein the circuitry is configured to additionally include an indication of one or more first channels whose status shall be reported by the first station into the channel response information.14. Second access point configured to communicate with at least one associated second station and configured to coordinate transmissions at least with a first access point that is part of a common coordination cluster with the second access point and that is configured to communicate with at least one associated first station, the second access point comprising circuitry configured to: listen to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the first set of first channels at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channels, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels on which the second access point may respond to the channel request;transmit a channel response on at least a primary second channel of a second set of second channels operated by the second access point and / or a second subset of channels as indicated within the channel response information if detected as idle; and establish a frame exchange with the at least one second station on at least the primary second channel if the primary second channel has been indicated in the first subset and a channel response has been transmitted to the first access point on at least the primary second channel.15. Second access point according to embodiment 14, wherein the circuitry is configured to transmit a channel response to the first access point and transmit data to the at least one second station on the primary second channel and one or more secondary second channels of the second set of second channels operated by the second access point, which have been indicated in the second subset indicated by the channel response information and which are idle.16. Second access point according to any one of embodiments 14 to 15, wherein the circuitry is configured not to transmit a channel response to the first access point and / or not to transmit data to the at least one second station on the primary first channel of the first set of first channels operated by the first access point.17. Second access point according to any one of embodiments 14 to 16, wherein the circuitry is configured to transmit, at the end of a transmission of data to the at least one second station or at the end of a time interval indicated in the channel request once the primary second channel and the primary first channel are idle for a predefined time interval, a transmission end indication to the first access point on the primary second channel and / or on the primary first channel and the primary second channel, the transmission end indication indicating if the second access point has finished data transmission or has more data to transmit to the at least one second station.18. Second access point according to embodiment 16 or 17, wherein the circuitry is configured to transmit a channel response and transmit data to the at least one second station on one or more further secondary second channels that have not been indicated in the second subset indicated by the channel response informationand that are part of the operating bandwidth of the second station with which an intended data exchange shall be subsequently performed and that are idle for the second access point.19. Second access point according to any one of embodiments 14 to 18, wherein the circuitry is configured to perform channel sensing before transmitting data to the at least one second station to detect at the intended start of the transmission from the first access point on which channels the first access point is transmitting data to the at least one first station and to determine which channels indicated in the second subset of first channels to use for subsequent data transmission.20. Second access point according to any one of embodiments 14 to 19, wherein the circuitry is configured to transmit a channel response to the first access point, instead of on the primary second channel, on one or more secondary second channels of the second set of second channels operated by the second access point, which have been indicated in the second subset indicated by the channel response information and which are idle, if the primary second channel is busy.21. Second access point according to any one of embodiments 14 to 20, wherein the circuitry is configured to transmit the channel response in data units with a common transmitter address of the coordination cluster.22. Second access point according to any one of embodiments 14 to 21 , wherein the circuitry is configured to listen to control information on both the primary first channel and the primary second channel.23. Second access point according to any one of embodiments 14 to 22, wherein the circuitry is configured to compensate for carrier frequency offsets and symbol clock offsets with respect to the data unit containing the channel request and to ensure that the start time of the transmission of the channel response is within a predefined time interval from the reception of the data unit containing the channel request from the first access point.24. Second access point according to any one of embodiments 14 to 23, wherein the circuitry is configured to determine the bandwidth and channel information of the first access point; determine the positions of the primary first channel and the secondary first channels relative to the determined bandwidth information; and determine the relation between the first channels and the second channels.25. First station configured to communicate with an associated first access point that is configured to coordinate transmissions in a common coordination cluster at least with a second access point that is configured to communicate with at least one associated second station, the first station comprising circuitry configured to: listen to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels on which the second access point may respond to the channel request; transmit a channel response to the first access point on at least the primary first channel if the primary first channel has been indicated in the first subset and if the primary first channel is idle; and listen to data transmitted by the first access point on at least the primary first channel if a channel response has been transmitted to the first access point on at least the primary first channel.26. First station according to embodiment 25, wherein the circuitry is configured to respond on a first set of channels which excludes the primary second channel or the second subset of channels.27. First station according to embodiment 25 or 26, wherein the circuitry is configured to transmit a busy indication of a set of channels within its operating bandwidth, which are part of the first channel subset.28. First station according to embodiment 25, 25 or 27, wherein the circuitry is configured, if it receives a data unit containing a channel request indication, a transmitter address corresponding to a coordination cluster and an indication indicating the first station as an intended recipient of the data unit, to transmit to the first access point one or more data units as indicated within the channel response indication.29. First communication method of a first access point configured to communicate with at least one associated first station and configured to coordinate transmissions at least with a second access point that is part of a common coordination cluster with the first access point and that is configured to communicate with at least one associated second station, the first communication method comprising: transmitting a channel request to the at least one associated first station and / or the second access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the first set of first channels at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channels, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request; listening to channel responses from the at least one first station and / or the second access point; and transmitting data to the at least one first station on at least the primary first channel if a channel response has been received from the at least one first station on at least the primary first channel.30. Second communication method of a second access point configured to communicate with at least one associated second station and configured to coordinate transmissions at least with a first access point that is part of a common coordination cluster with the second access point and that is configured to communicate with at least one associated first station, the second communication method comprising:listening to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the first set of first channels at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channels, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request; transmitting a channel response on at least a primary second channel of a second set of second channels operated by the second access point and / or a second subset of channels as indicated within the channel response information if detected as idle; and establishing a frame exchange with the at least one second station on at least the primary second channel if the primary second channel has been indicated in the first subset and a channel response has been transmitted to the first access point on at least the primary second channel.31. Third communication method of a first station configured to communicate with an associated first access point that is configured to coordinate transmissions in a common coordination cluster at least with a second access point that is configured to communicate with at least one associated second station, the third communication method comprising: listening to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request; transmitting a channel response to the first access point on at least the primary first channel if the primary first channel has been indicated in the first subset and if the primary first channel is idle; andlistening to data transmitted by the first access point on at least the primary first channel if a channel response has been transmitted to the first access point on at least the primary first channel.32. A non-transitory computer-readable recording medium that stores therein a computer program product, which, when executed by a processor, causes the method according to embodiment 29, 30 or 31 to be performed.33. A computer program comprising program code means for causing a computer to perform the steps of said method according to embodiment 29, 30 or 31 , when said computer pro-gram is carried out on a computer.

Claims

CLAIMS1 . First access point configured to communicate with at least one associated first station and configured to coordinate transmissions at least with a second access point that is part of a common coordination cluster with the first access point and that is configured to communicate with at least one associated second station, the first access point comprising circuitry configured to: transmit a channel request to the at least one associated first station and / or the second access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the first set of first channels at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channels, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request; listen to channel responses from the at least one first station and / or the second access point; and transmit data to the at least one first station on at least the primary first channel if a channel response has been received from the at least one first station on at least the primary first channel.

2. First access point according to claim 1 , wherein the circuitry is configured to indicate in the first subset of first channels the primary first channel of the first access point and to indicate in the second subset of first channels a primary second channel of the set of second channels operated by the second access point.

3. First access point according to claim 2, wherein the first channels included in the first subset are different from the primary second channel and optionally from the secondary second channels corresponding to the channels included in the second subset of first channels, and / orwherein the one or more first channels included in the second subset are different from the primary first channel and optionally from one or more of the secondary first channels included in the first subset.

4. First access point according to claim 1 , wherein the circuitry is configured to transmit data to the at least one first station on the primary first channel and one or more secondary first channels included in the first subset on which a channel response has been received from the at least one first station and / or on one or more first channels which have been indicated in the channel response by the at least one first station as idle and / or one or more first channels operated by the first station, which correspond to second channels on which a channel response from the second access point has not been received or has not been correctly decoded.

5. First access point according to claim 1 , wherein the circuitry is configured to not transmit data to the at least one first station on at least the first channel corresponding to the primary second channel if a channel response has been received by the first access point from the second access point on that channel and / or on one or more first channels corresponding to secondary second channels on which the first access point has received a channel response from the second access point.

6. First access point according to claim 1 , wherein the circuitry is configured to include an indication into the channel request of a time interval from which the second access point can use the first channels and optionally expects an indication at the end of this period regarding whether there is a need for more transmission time or not.

7. First access point according to claim 1 , wherein the circuitry is configured to obtain and / or negotiate, for all access points within the common coordination cluster, information on the primary channels of the respective set of channels operated by the respective access point and information on one or more of: operating bandwidths,supported puncturing patterns, common transmitter address of the coordination cluster, and scheduling intervals in which the coordinated transmission may occur8. First access point according to claim 1 , wherein the circuitry is configured to set the transmitter address of the channel request to a common transmitter address of the coordination cluster, and / or to additionally include an indication of one or more first channels whose status shall be reported by the first station into the channel response information.

9. First access point according to claim 1 , wherein the first and second subsets of channels are chosen such that the resulting channels on which the transmission to the first station and the second station, respectively, are performed over a set of channels corresponding to supported puncturing patterns.

10. Second access point configured to communicate with at least one associated second station and configured to coordinate transmissions at least with a first access point that is part of a common coordination cluster with the second access point and that is configured to communicate with at least one associated first station, the second access point comprising circuitry configured to: listen to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the first set of first channels at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channels, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels on which the second access point may respond to the channel request; transmit a channel response on at least a primary second channel of a second set of second channels operated by the second access point and / or a second subset of channels as indicated within the channel response information if detected as idle; andestablish a frame exchange with the at least one second station on at least the primary second channel if the primary second channel has been indicated in the first subset and a channel response has been transmitted to the first access point on at least the primary second channel.

11. Second access point according to claim 10, wherein the circuitry is configured to transmit a channel response to the first access point and transmit data to the at least one second station on the primary second channel and one or more secondary second channels of the second set of second channels operated by the second access point, which have been indicated in the second subset indicated by the channel response information and which are idle, and / or not to transmit a channel response to the first access point and / or not to transmit data to the at least one second station on the primary first channel of the first set of first channels operated by the first access point.

12. Second access point according to claim 10, wherein the circuitry is configured to transmit, at the end of a transmission of data to the at least one second station or at the end of a time interval indicated in the channel request once the primary second channel and the primary first channel are idle for a predefined time interval, a transmission end indication to the first access point on the primary second channel and / or on the primary first channel and the primary second channel, the transmission end indication indicating if the second access point has finished data transmission or has more data to transmit to the at least one second station.

13. Second access point according to claim 11 or 12, wherein the circuitry is configured to transmit a channel response and transmit data to the at least one second station on one or more further secondary second channels that have not been indicated in the second subset indicated by the channel response information and that are part of the operating bandwidth of the second station with which an intended data exchange shall be subsequently performed and that are idle for the second access point.

14. Second access point according to claim 10, wherein the circuitry is configured to perform channel sensing before transmitting data to the at least one second station to detect at the intended start of the transmission from the first access point on which channels the first access point is transmitting data to the at least one first station and to determine which channels indicated in the second subset of first channels to use for subsequent data transmission, and / or transmit a channel response to the first access point, instead of on the primary second channel, on one or more secondary second channels of the second set of second channels operated by the second access point, which have been indicated in the second subset indicated by the channel response information and which are idle, if the primary second channel is busy, and / or compensate for carrier frequency offsets and symbol clock offsets with respect to the data unit containing the channel request and to ensure that the start time of the transmission of the channel response is within a predefined time interval from the reception of the data unit containing the channel request from the first access point.

15. Second access point according to claim 10, wherein the circuitry is configured to determine the bandwidth and channel information of the first access point; determine the positions of the primary first channel and the secondary first channels relative to the determined bandwidth information; and determine the relation between the first channels and the second channels.

16. First station configured to communicate with an associated first access point that is configured to coordinate transmissions in a common coordination cluster at least with a second access point that is configured to communicate with at least one associated second station, the first station comprising circuitry configured to: listen to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of oneor more first channels on which the second access point may respond to the channel request; transmit a channel response to the first access point on at least the primary first channel if the primary first channel has been indicated in the first subset and if the primary first channel is idle; and listen to data transmitted by the first access point on at least the primary first channel if a channel response has been transmitted to the first access point on at least the primary first channel.

17. First communication method of a first access point configured to communicate with at least one associated first station and configured to coordinate transmissions at least with a second access point that is part of a common coordination cluster with the first access point and that is configured to communicate with at least one associated second station, the first communication method comprising: transmitting a channel request to the at least one associated first station and / or the second access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the first set of first channels at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channels, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request; listening to channel responses from the at least one first station and / or the second access point; and transmitting data to the at least one first station on at least the primary first channel if a channel response has been received from the at least one first station on at least the primary first channel.

18. Second communication method of a second access point configured to communicate with at least one associated second station and configured to coordinate transmissions at least with a first access point that is part of a common coordination cluster withthe second access point and that is configured to communicate with at least one associated first station, the second communication method comprising: listening to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the first set of first channels at least partly overlapping with a second set of second channels operated by the second access point including a primary second channel and one or more secondary second channels, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request; transmitting a channel response on at least a primary second channel of a second set of second channels operated by the second access point and / or a second subset of channels as indicated within the channel response information if detected as idle; and establishing a frame exchange with the at least one second station on at least the primary second channel if the primary second channel has been indicated in the first subset and a channel response has been transmitted to the first access point on at least the primary second channel.

19. Third communication method of a first station configured to communicate with an associated first access point that is configured to coordinate transmissions in a common coordination cluster at least with a second access point that is configured to communicate with at least one associated second station, the third communication method comprising: listening to a channel request from the first access point on a first set of one or more first channels including a primary first channel and one or more secondary first channels operated by the first access point, the channel request including channel response information including an indication of a first subset of one or more first channels on which the at least one first station may respond to the channel request and a second subset of one or more first channels which the second access point may use during the transmit opportunity or on which the second access point may respond to the channel request;transmitting a channel response to the first access point on at least the primary first channel if the primary first channel has been indicated in the first subset and if the primary first channel is idle; and listening to data transmitted by the first access point on at least the primary first channel if a channel response has been transmitted to the first access point on at least the primary first channel.

20. A non-transitory computer-readable recording medium that stores therein a computer program product, which, when executed by a processor, causes the method according to claim 17, 18 or 19 to be performed.

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