Method and apparatus for optimized multi-AP cooperation

Abstract

To provide a more efficient communication method and device for performing a multi-AP operation with stations outside the range of a coordinator access point (AP).SOLUTION: In 802.11be multi-AP coordination, a collaborated apparatus that has acquired a shared resource announced by a collaborator AP re-announces the shared resource for stations outside the transmission range of the collaborator AP. Assuming that a short time is available, a re-announcement frame repeats in binary most of an initial announcement by the collaborator AP, in particular substantially the whole of its MAC payload. To facilitate identification of the re-announcement, the latter contains an empty transmitter address (TA) field in its header or does not contain a TA field. This additionally allows any AP to act as a coordinator AP.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates generally to wireless communications. [Background technology]

[0002] Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting a large number of users by sharing available network resources. Examples of such multiple-access networks include code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, and single-carrier FDMA (SC-FDMA) networks.

[0003] To address the increasing bandwidth and decreasing latency requirements for wireless communication systems in high-density environments, multi-user (MU) procedures have been developed to enable a single access point (AP) managing a basic service set (BSS) to schedule MU transmissions, i.e., multiple parallel transmissions to and from non-AP stations in that BSS, in a wireless network. For example, one such MU procedure was adopted by the Institute of Electrical and Electronics Engineers (IEEE) in the June 2018 draft version 3.0 (D3.0) of the IEEE 802.11ax standard.

[0004] The MU feature allows non-AP stations the opportunity to gain access to the wireless medium via two access procedures: the MU procedure and the conventional Enhanced Distributed Channel Access-EDCA (single user) procedure.

[0005] Each BSS defines a primary channel (usually a 20 MHz channel or a multiple of 20 MHz) of the wireless medium over which stations (including APs) conduct EDCA contention, known as the primary channel. To increase the bandwidth for upcoming transmissions, stations can contend in parallel for additional 20 MHz channels, known as secondary channels. Thus, a given communication channel for transmission includes the primary channel and, optionally, the secondary channel.

[0006] The 802.11ax standard allows an AP to perform MU downlink (DL) transmissions when it obtains access to the wireless medium for a transmission opportunity (TXOP). During a MU DL transmission on a given communication channel, the AP performs multiple simultaneous elementary transmissions to various non-AP stations on so-called resource units (RUs). For example, resource units divide the communication channel of a wireless network in the frequency domain, for example, based on orthogonal frequency division multiple access (OFDMA) technology. The allocation of RUs to non-AP stations is signaled at the beginning of the MU downlink frame by providing the non-AP station's association identifier (AID) (obtained individually by each station during the association procedure with the AP) for each RU defined in the transmission opportunity.

[0007] The 802.11ax standard also allows an AP to trigger a MU uplink (UL) transmission when it gains access to the wireless medium. During a MU UL transmission, various non-AP stations can transmit data to the AP in parallel on resource units that form a communication channel. To control MU UL transmissions by non-AP stations, the AP transmits a control frame known as a trigger frame (TF) in advance. The trigger frame allocates resource units to non-AP stations in the same BSS using a 16-bit association identifier (AID) assigned to the non-AP station when it registers with the AP and / or a reserved AID that specifies a group of non-AP stations. The TF also defines the start and length of MU UL transmissions by non-AP stations.

[0008] Recently, the IEEE 802.11be draft standard task group has been working on so-called multi-AP technology. The latter aims to provide a degree of coordination between neighboring access points (APs managing separate BSSs) for more efficient utilization of available time, frequency, and space resources. This is particularly important when neighboring APs operate on the same selected communication channel (or channels close enough to communicate with each other).

[0009] Using such techniques, two or more neighboring APs can share resources in terms of frequency and / or time, and avoid interfering with each other in the call process.

[0010] An AP that initiates and manages multi-AP collaboration by sharing the resources of its given TXOP is called a sharing or coordinator AP. An AP candidate set is maintained that registers candidate APs that have requested to be part of the set and want to participate in the collaboration. Such an AP that participates in multi-AP collaboration and uses the shared resources is called a shared or coordinated AP. The corresponding BSS is known as a coordinated BSS.

[0011] The coordinator AP typically transmits a sharing announcement frame that defines which resources are allocated to which coordinated APs. A trigger frame may be used. The coordinated AP can schedule MU downlink (DL) and / or uplink (UL) transmissions for its associated non-AP stations within the constraints (typically in terms of frequency and time) of its assigned resources. Multi-AP cooperation is preferably dynamic, meaning that different APs in the same multi-AP group can act as coordinator APs to seize the wireless medium and share resources.

[0012] With the multi-AP procedure, the resources shared with the coordinated AP may not include the primary channel of the coordinated BSS. For the coordinated AP to effectively schedule MU DL or UL transmissions within the shared resources, all of the stations in the coordinated BSS are required to temporarily switch from their native primary channel to another channel of the shared resources over which the coordinated AP communicates to manage the MU transmissions until the end of the shared TXOP. However, some non-AP stations in the shared BSS may be outside the range of the coordinating AP and therefore may not receive the shared announcement frame. As a result, these non-AP stations are unable to switch their primary channel to the correct channel and are unable to participate in MU transmissions initiated by their local AP (with which they registered) within the shared resources.

[0013] The IEEE 802.11-20 / 0277r1 contribution to the 802.11be standard discloses that a coordinating AP may need to indicate a temporary channel switch to associated non-AP stations in order to operate properly during a shared opportunity. These coordinating APs transmit identical switch frames in parallel. The latter must include only information essential for non-AP stations in that BSS, such as the primary channel and bandwidth of the shared resource, and must set the MAC address of the coordinating AP in the TA field of the MAC header.

[0014] The first problem with this procedure is the difficulty of coordinating APs to locally create identical switching frames, especially when they rely on hardware manufactured by different companies. In fact, the coordinated APs must organize the same basic information in the switching frame in the same order. However, the order of some information, such as the User Info field (which defines the corresponding assignments to RUs and stations), is not mandatory and only depends on the AP implementation.

[0015] A second problem with known multi-AP procedures is the need for the coordinated AP to share the MAC address of the coordinator AP in advance (e.g., during association) with associated non-AP stations in order for these non-AP stations to efficiently decode switchover frames with a TA equal to the MAC address of the coordinator AP. Therefore, the coordinator AP must be known by all stations, which means that the coordinator AP must be fixed.

[0016] It would be desirable to design a more efficient mechanism for multi-AP operation with out-of-range stations. Summary of the Invention

[0017] It is a general object of the present invention to address some of the above concerns.

[0018] In this context, the present invention relates to a method of communication in a wireless network, comprising: receiving, from a coordinator device to which a transmission opportunity (TXOP) has been granted, a frame announcing a sharing of resources of the granted TXOP, the frame comprising a short opening portion and a large data portion; transmitting a re-announcement frame repeating the large data portion of the received announce frame; The present invention provides a communication method having the following features.

[0019] This resource sharing can benefit any wireless device outside the coordinator device's BSS, for example, other APs.

[0020] The wireless devices participating in this method, i.e., the coordinated device managing a group of wireless devices (e.g., a BSS or direct link group), form a re-announcement frame by binary duplicating or copying a data portion of the same length as one of the received announce frames. This makes the process of forming a re-announcement frame simple and independent of implementation variations from device to device. This is important because the coordinated device may have very little time (e.g., SIFS) to generate the re-announcement frame, as may occur, for example, when the coordinated device is assigned shared resources declared at the very end of the announce frame. Thus, various coordinated devices participating in the multi-AP procedure can form exactly identical re-announcement frames in a very short time before transmitting them in parallel.

[0021] Furthermore, by repeating the large data portion, the coordinated device allows out-of-range devices (e.g., access points (APs) from the coordinator device's perspective) to eventually become aware of the multi-AP resource sharing, so they can temporarily switch primary channels if necessary.

[0022] The present invention also provides a communication method in a wireless network, comprising: transmitting a transmission opportunity (TXOP) granted frame announcing a resource sharing of the granted TXOP and including a re-announcement field indicating whether at least one coordinated device involved in the resource sharing needs to re-announce the resource sharing, the frame including a short opening portion and a large data portion; receiving a re-announcement frame from one or more of the coordinated devices, the re-announcement frame repeating the large data portion of the transmitted announcing frame; The present invention provides a communication method having the following features.

[0023] Thus, the coordinator device effectively drives re-announcement of resource sharing, for example, when it recognizes that some devices involved in the resource sharing (i.e., devices to which the shared resource will be assigned) will inevitably be outside the range of the initial announcement frame.

[0024] Furthermore, by receiving the re-announcement frame from the coordinated device, the coordinator device verifies that the coordinated device is operating in a proper manner.

[0025] Correspondingly, the present invention also provides a wireless communication device having at least one microprocessor configured to perform the steps of any of the above-described methods.

[0026] Optional features of embodiments of the invention are defined in the accompanying claims. Some of these features are described below with reference to methods, but they can also be transferred to apparatus features.

[0027] In some embodiments, the large data portion is the MAC payload of the announce frame. In that case, a re-announce frame is generated in which the entire MAC payload is kept intact (a binary copy) and only the (short) MAC header differs. This is the shortest and most secure way to generate a re-announce frame.

[0028] In another embodiment, the re-announce frame has a different MAC header and one or more start fields in the MAC payload than the announce frame, while the remainder of the MAC payload remains the same, allowing the coordinating device to add signaling as needed.

[0029] In some embodiments of the coordinated device, transmitting the re-announce frame is further responsive to determining from the received announce frame that the shared resources allocated to the wireless device do not include the wireless device's primary channel. In other words, the coordinated device retransmits the large data portion or MAC payload only if it needs to switch its primary channel.

[0030] In some embodiments, transmitting the re-announce frame is further in response to determining that the re-announce field of the received announce frame indicates that the wireless device needs to announce resource sharing, in such a manner that the coordinator device can efficiently operate, possibly on a per-coordinated device basis, when re-announcements are required.

[0031] According to a particular feature, the re-announcement field indicates that the wireless device that needs to switch its primary channel needs to re-announce its resource sharing.

[0032] In some embodiments, the wireless device is a management device that manages a group of wireless devices, such as an AP that manages a BSS or a group owner that manages a peer-to-peer (P2P) group that implements direct link transmission.

[0033] In some embodiments, the re-announce frame has an empty or no sender address (TA) field in its MAC header. For example, the re-announce frame may simply be a duplicate of the received announce frame, where the sender address (TA) field in the MAC header is empty.

[0034] This approach is advantageous in that it avoids having a fixed coordinator device that needs to be known by each and every station. Instead, the empty TA field allows any AP to dynamically act as the coordinator for multi-AP sharing (contrary to known techniques where the MAC address of the coordinator AP is signaled in the TA field).

[0035] Furthermore, the empty TA field is an unambiguous indication to the wireless device that the frame is a re-announcement frame, and the wireless device can act accordingly (e.g., parse the MAC payload to determine if a primary channel switch is required, or initiate a MU UL or DL ​​transmission after a SIFS).

[0036] In some embodiments, the wireless device is an access point (AP) and transmits a trigger frame on a shared resource assigned to the AP to trigger a multi-user uplink transmission with a non-AP station of its basic service set on the assigned shared resource.

[0037] In some embodiments, the wireless device is an access point (AP) and further initiates a multi-user downlink transmission with non-AP stations of its basic service set on the assigned shared resources. For example, the multi-user downlink transmission can include an indication of a subsequent multi-user uplink transmission opportunity on the assigned shared resources.

[0038] In some embodiments, the wireless device further transmits a frame announcing the sharing of a portion of the shared resources assigned to the wireless device, which may be for the benefit of other APs outside its own BSS, e.g., APs outside the transmission range of the coordinator device.

[0039] In some embodiments for a coordinator device, a re-announce field indicates that a coordinated device that needs to switch primary channels needs to re-announce resource sharing.

[0040] In some embodiments, the re-announcement field is provided at the shared resource (e.g., RU) level (e.g., User Info field level of the trigger frame) for the purpose of the coordinator device selectively choosing which coordinated devices need to send the re-announcement frame.

[0041] In another embodiment, the coordinator device also transmits re-announcement frames in parallel to one or more coordinated devices.

[0042] Another aspect of the invention relates to a non-transitory computer readable medium storing a program that, when executed by a microprocessor or computer system in a wireless device, causes the wireless device to perform any of the methods defined above.

[0043] At least a portion of the methods according to the present invention may be computer-implemented. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all of which may be generally referred to as a "circuit," "module," or "system." Furthermore, the present invention may take the form of a computer program product embodied in any tangible medium of expression having computer-usable program code embodied in the medium.

[0044] Because the present invention may be implemented in software, it may be embodied as computer-readable code on any suitable carrier medium for provision to a programmable apparatus. Tangible carrier media may include storage media such as hard disk drives, magnetic tape devices, or solid-state memory devices. Transient carrier media may include signals such as electrical, electronic, optical, acoustic, magnetic, or electromagnetic signals, e.g., microwave or RF signals. [Brief explanation of the drawings]

[0045] Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings: [Figure 1] FIG. 1 illustrates an exemplary network environment in which embodiments of the present disclosure may be implemented. [Figure 2] FIG. 1 illustrates trigger-based (TB) multi-user (MU) transmission. [Figure 3] FIG. 2 is a diagram illustrating the structure of a trigger frame. [Figure 4a] A diagram showing the format of the HE SU PPDU. [Figure 4b] A diagram showing the format of an HE MU PPDU. [Figure 4c] A diagram showing the format of the HE TB PPDU. [Figure 5]A diagram showing a transmission sequence implementing multi-AP technology to achieve cooperative OFDMA resource sharing. [Figure 6a] 1 shows a schematic representation of a communication device according to an embodiment of the present invention; [Figure 6b] 1 shows a schematic representation of a wireless communication device according to an embodiment of the present invention; [Figure 7] FIG. 10 illustrates another multi-AP based transmission sequence implementing an embodiment of the present invention. [Figure 8] FIG. 1 is a flowchart illustrating the general steps in a coordinator device according to an embodiment of the present invention. [Figure 9] FIG. 1 is a flowchart illustrating the general steps in a non-coordinator device according to an embodiment of the present invention. [Figure 10] FIG. 10 illustrates an alternative multi-AP based transmission sequence implementing an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0046] The techniques described herein may be used for various broadband wireless communication systems, including communication systems based on orthogonal multiplexing procedures. Such communication systems include, for example, spatial division multiple access (SDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems. SDMA systems may utilize sufficiently different directions to transmit data belonging to multiple user terminals, i.e., wireless devices or stations, in parallel. TDMA systems allow multiple user terminals to share the same frequency channel by dividing the transmission signal into different time slots or resource units, each time slot being assigned to a different user terminal. OFDMA systems utilize orthogonal frequency division multiplexing (OFDM), a modulation technique that divides the overall system bandwidth into multiple orthogonal subcarriers or resource units. These subcarriers may also be referred to as tones, bins, etc. Using OFDM, each subcarrier may be individually modulated with data. An SC-FDMA system may utilize Interleaved FDMA (IFDMA) for transmission on subcarriers that are distributed across the system bandwidth, Localized FDMA (LFDMA) for transmission on blocks of adjacent subcarriers, or Enhanced FDMA (EFDMA) for transmission on multiple blocks of adjacent subcarriers.

[0047] The teachings herein may be incorporated into (e.g., implemented within or performed by) a variety of devices (e.g., stations). In some aspects, wireless devices or stations implemented in accordance with the teachings herein may include access points (so-called APs) or other devices (so-called non-AP stations or STAs).

[0048] An AP may include or be implemented as what is known as a Node B, Radio Network Controller ("RNC"), Evolved Node B (eNB), 5G Next Generation Base Station (gNB), Base Station Controller ("BSC"), Base Transceiver Station ("BTS"), Base Station ("BS"), Transceiver Function ("TF"), Wireless Router, Wireless Transceiver, Basic Service Set ("BSS"), Enhanced Service Set ("ESS"), Radio Base Station ("RBS"), or some other terminology.

[0049] A non-AP station may include or be implemented as a subscriber unit, mobile station (MS), remote station, remote terminal, user terminal (UT), user agent, user device, user equipment (UE), user station, or some other terminology. In some embodiments, a STA may include a mobile phone, a cordless phone, a Session Initiation Protocol ("SIP") phone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a handheld device with wireless connectivity capabilities, or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a mobile phone or smartphone), a computer (laptop), a tablet, a portable communication device, a portable computing device (e.g., a personal digital assistant), an entertainment device (e.g., a music or video device, satellite radio), a global positioning system (GPS) device, or any other suitable device configured to communicate via a wireless or wired medium. In some aspects, a non-AP station may be a wireless node. Such a wireless node may, for example, provide connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link.

[0050] FIG. 1 illustrates an exemplary network environment in which embodiments of the present disclosure may be implemented.

[0051] The illustrated wireless network environment includes a multi-AP system 100 formed by a group of adjacent wireless networks operating over a communication channel or wireless medium. The common communication channel may correspond to a portion (e.g., 20 MHz) or all of an operating channel (e.g., 20 MHz, 40 MHz, 80 MHz, or 160 MHz).

[0052] A first wireless network BSS1 includes an access point (AP) 110 and three non-AP stations (STAs) 111, 112, and 113 associated with (i.e., registered with) the AP. A second wireless network BSS2 includes an AP 120 and three associated non-AP STAs 121, 122, and 123. A third wireless network BSS2 includes an AP 130 and three associated non-AP STAs 131, 132, and 133. Hereinafter, BSSx represents any of the wireless networks, while BSS1, 1x2, and 1x3 represent any of the non-AP stations. Of course, any number of wireless networks and any number of non-AP stations per wireless network may be contemplated. In this disclosure, APs 110, 120, and 130 are also referred to as AP1, AP2, and AP3, respectively. A device may operate as an AP in one wireless network and simultaneously belong as an associated STA to another wireless network.

[0053] Stations (AP and non-AP) of each wireless network exchange data frames under the control of the AP over communication channels 100. A primary channel, typically a 20 MHz channel, is defined for each wireless network over which management frames are exchanged. Other 20 MHz channels in the communication channels, if any, are known as secondary channels.

[0054] Direct communication between non-AP STAs (also known as direct link (DiL)) can also be implemented without using an access point (known as ad-hoc mode). For example, the WiFi-Direct standard allows devices to communicate directly over the 802.11 wireless medium without the need for any APs. An example of a direct communication scenario, which corresponds to a recent trend, is peer-to-peer (P2P) transmission between non-AP stations having the same primary channel, e.g., between STA 112 and STA 113 as shown in the figure. Technologies supporting P2P transmission between non-AP STAs not associated with the same BSS or any BSS include, for example, WiFi-Miracast (RTM) and wireless display scenarios in addition to WiFi-Direct. Other technologies supporting P2P transmission within a BSS include Direct Link Setup (DLS) and Tunneled Direct Link Setup (TDLS). Even if the P2P flows are not numerous, the amount of data per flow tends to be significant, typically low-compression video ranging from 1080p60 to 8K UHD resolution.

[0055] Each non-AP STA 1x1-1x3 registers with AP 1x0 of one wireless network BSSx during an association procedure. During the association procedure on the primary channel, the AP assigns a unique association identifier (AID) to the requesting station. For example, the AID is a 16-bit value that uniquely identifies the station.

[0056] Stations (including APs) compete with each other using EDCA (Enhanced Distributed Channel Access) contention to access communication channels (including a primary channel and optionally a secondary channel for increased bandwidth) to be granted a transmission opportunity (TXOP). TXOPs can be used to transmit (single-user (SU)) data frames or to implement multi-user (MU) transmissions. In the MU procedure, a single station, typically an AP of a wireless network BSSx, can schedule MU transmissions, i.e., multiple simultaneous transmissions to or from other stations in the wireless network. One implementation of such a MU procedure is adopted, for example, in the IEEE 802.11ax amendment known as the Multi-User Uplink and Downlink OFDMA (MU UL and DL OFDMA) procedure. In the MU procedure, resources are defined in terms of one or more 20 MHz channels to be used, known as resource units.

[0057] More generally, resources include spatial, frequency, and time resources and may be obtained according to various multiplexing procedures, including, for example, spatial division multiple access (SDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single-user frequency division multiple access (SC-FDMA) systems.

[0058] In the IEEE 802.11 wireless local area network standard, the multi-AP system 100 may support an extended service set (ESS), and each of the wireless networks may support a basic service set (BSS).

[0059] Although a description of embodiments of the present invention is provided in the context of IEEE 802.11, the embodiments are not so limited and may be applied to other types of wireless networks and protocols.

[0060] FIG. 2 illustrates the MU procedure in any of the wireless network BSSs x, and more specifically, trigger-based (TB) multi-user (MU) transmissions, including MU uplink (UL) transmissions to the APs of BSSs x, as well as MU transmissions between non-AP STAs, i.e., direct link (DiL) transmissions.

[0061] The illustrated MU transmission is triggered by a trigger frame (TF) 210 that reserves a communication channel for a transmit opportunity (TXOP) 200. The TF is a control frame, e.g., in the IEEE 802.11 legacy non-HT format. The TF is transmitted by APx on a primary 20 MHz channel 250 when the primary channel is detected as idle, and is repeated (duplicated) on one or more other (secondary) idle 20 MHz channels 251 that form the communication channel, if present. Due to the duplication of the control frame 210, all nearby legacy stations (non-HT or 802.11ac stations) that receive the TF on the primary channel (which may be a secondary channel for the BSSx under consideration) are expected to set their NAV to the value specified in the header of the TF. This can prevent these legacy stations from accessing any of the reserved communication channels during the transmit opportunity (TXOP).

[0062] TF210 has the structure shown in Figure 3. This is a MAC header 310 containing a standardized "Frame Control" field 311, a standardized "Duration" field 312 that defines the duration of the transmit opportunity (e.g., TXOP 200), an "RA" field set to the broadcast MAC address for BSSx 313, and a "TA" field set to the MAC address of the AP sending the trigger frame 314; MAC payload 320, A MAC frame 300 (representing medium access control) is composed of:

[0063] The MAC payload 320 is "Common Info" field 330, one or more "User Info" fields 340; and Padding and FCS fields Includes.

[0064] The "Common Info" field 330 includes a "Trigger Type" subfield 331 that identifies the type of trigger frame. For the time being, eight values ​​(0 to 7) are defined. For example, a basic TF is signaled by a value of 0 in the "Trigger Type" subfield.

[0065] The "Common Info" field 330 also includes a "UL Length" field 332 that specifies the duration of the desired UL transmission (preamble 230 plus UL data 221), and a 2-bit "UL BW" field 333 that specifies the bandwidth of the considered communication channel, e.g., BW=0 to define a 20 MHz bandwidth, BW=1 for a 40 MHz bandwidth, BW=2 for an 80 MHz bandwidth, BW=3 for an 80+80 MHz or 160 MHz bandwidth. It is terminated by a reserved B63 bit 334 and a Trigger Dependent Common Info subfield 335 that is of variable length and whose content depends on the "Trigger Type" subfield 320.

[0066] As shown in Figure 2, a basic communication channel, here a resource unit RU, is defined over the communication channel used. Essentially, each resource unit is assigned to a different non-AP station in the MU procedure.

[0067] Resource units RU1 201 to RU8 208 (more generally RUx) are formed by a group of subcarriers, preferably contiguous, contained in a communication channel. This means that the frequency bandwidth of the communication channel is equal to or greater than the frequency bandwidth of the resource unit. RUs can be allocated for scheduled access (the AP decides which RUs non-AP stations will use) or random access (non-AP stations compete for access to the RUs).

[0068] RUs are defined by the AP in the TF 210. Returning to Figure 3, each "User Info" field 340 corresponds to one RU. The order of the "User Info" fields 340 used within the TF 300 can be arbitrary, as these fields are sufficient to define the RUs and their access procedures.

[0069] The "User Info" field 340 includes an "AID12" subfield 341, an "RU Allocation" subfield 342, and is terminated by a reserved B39 bit 343 and a "Trigger Dependent User Info" subfield 344, which is variable in length and whose content depends on the "Trigger Type" subfield 320. There are other fields that will not be described here for the sake of brevity.

[0070] The "AID12" subfield 341 is set to the AID of the non-AP station to which the RU defined in the "RU Allocation" subfield 342 is assigned upon scheduled access, or is set to AID=0 or 2045 to indicate a corresponding RU for random access to associated and non-associated non-AP stations, respectively. The 802.11ax standard (e.g., Table 9-31g of version D4.1 of the standard) defines the values ​​to be used in the "RU Allocation" subfield 342 to specify a particular RU within the communication channel signaled in the "UL BW" field 333.

[0071] 2, the TF 210 offers RUs (RU1 201 and RU3-RU8 203-208) to non-AP stations for uplink (UL) transmission 221, and also offers DiL transmission capability 222 within a triggered MU transmission by allocating a resource unit (here, RU2 202) for this purpose. An administrator, person in charge, or "group owner" of the P2P group may have previously notified the AP that the P2P group intends to have a new opportunity for DiL transmission.

[0072] The DiL transmission offered by the AP may be signaled in the associated "User Info" field 340 (i.e., the field corresponding to the offered RU) by using the appropriate value in the "AID12" subfield 341.

[0073] In one implementation, the "AID12" subfield 341 may carry a DiL session identifier corresponding to a direct link session (directly identifiable by the source and destination stations involved in direct link communication). This may be assumed when the AP allows P2P sessions (such as the DLS protocol when within a BSS) or recognizes a P2P protocol (outside a BSS and discovered via a beacon or discovery frame in a cooperation procedure) and provides an identifier for the session. Preferably, the DiL session identifier is constrained to the 12-bit AID format, and it is up to the AP to assign a value different from that assigned to the AID that identifies individual non-AP stations.

[0074] Alternatively, the "AID12" subfield 341 may carry the AID of a non-AP station of the P2P group, for example, of the group owner of the P2P group. Also, since a non-AP 802.11ax station of the P2P group may not know its AID, a MAC address may be used instead of a station identifier (AID), as this type of address is widely known and shared, among other things, between APs and stations. In a variant, two AIDs or two MAC addresses (if any) of the non-AP stations involved in the DiL session may be indicated in the User Info field (e.g., using the AID12 subfield 341 and / or the Trigger Dependent User Info section 344).

[0075] Returning to Figure 2, upon receiving TF 210, non-AP stations begin MU transmission (for UL or DiL transmission) one SIFS after that TF. They begin transmitting data frames in the High-Efficiency (HE) format introduced in 802.11ax.

[0076] High-Efficiency (HE) frames were introduced in 802.11ax. As shown in Figure 4, these frames begin with the same preamble 230 (L-STF, L-LTF, and L-SIG) that can be read by any station (for backward compatibility), followed by auxiliary preamble and data fields. The HE field of the preamble is decodable only by 802.11ax (and forward-compatible) devices and is included in various types of HE frames, such as the HE Single User (SU) PPDU, which is used for single-user transmissions; the HE MU PPDU, which is used for multi-user (MU) downlink (DL) transmissions to one or more stations, specifically from an AP to a non-AP station; and the HE trigger-based (TB) PPDU (HE_Trig), which is used for uplink (UL) transmissions from a non-AP station to an AP in response to a trigger frame.

[0077] Figures 4a, 4b, and 4c illustrate the formats of these various frames: the HE SU PPDU frame, the HE MU PPDU frame, and the HE TB PPDU frame, respectively. These HE frames are used as examples in describing embodiments of the present invention. However, it should be understood that other formats are also possible. For example, the Extremely-High-Throughput (EHT) frame introduced in 802.11be may also be used.

[0078] Figure 4a shows the format of an HE SU PPDU. It includes an HE preamble consisting of a legacy preamble (L-SIG with L-STF, L-LTF, and RL-SIG), an HE-SIG-A (HE SIGNAL A), an HE-STF (HE Short Training Field), and an HE-LTF (HE Long Training Field), and ends with a Data field and a Packet Extension (PE) field. The legacy preamble and HE-SIG-A (collectively referred to as field 400a) are replicated on each 20 MHz channel used in the communication channel. The HE-SIG-A field includes multiple subfields that indicate a set of transmission parameters for the PPDU, such as bandwidth (BW), modulation and coding scheme (MCS), number of data streams, coding type, etc. The following field 401a is modulated over the channel bandwidth.

[0079] Figure 4b shows the format of the HE MU PPDU. It contains the same fields as the HE SU PPDU (Figure 4a), plus an additional field 401, HE-SIG-B (HE SIGNAL B), which is used to inform non-AP stations in which resource units they can find their data (i.e., the allocation of RUs to the non-AP stations). This allows DL transmissions to be initiated directly, without a prior triggering frame announcing the RU allocation. In this way, HE-SIG-B 401 defines how RUs forming DL MU transmissions are assigned to non-AP stations so that they can efficiently receive their data from the AP. Again, for field 401b, field 400b is replicated on each 20 MHz channel while the HE-STF and HE-LTF are modulated over the channel bandwidth, while data is modulated only on the associated RUs.

[0080] Figure 4c shows the format of the HE TB PPDU (HE-Trig). This is the format used for the data frames (preamble 230 and data 221) of Figure 2. Each HE-Trig PPDU carries a single transmission (i.e., from one non-AP station) in response to a trigger frame. The HE-Trig frame has a format very similar to the HE SU PPDU, except that the duration of the HE-STF field is 8 μs. In particular, it does not include an HE-SIG-B field, since the allocation of RUs to non-AP stations is already defined by the TF 210. Again, field 400c is duplicated on each 20 MHz channel, while the HE-STF and HE-LTF for field 401c are modulated across the channel bandwidth, while data is modulated only in the associated RU.

[0081] DiL transmission is based on the HE SU PPDU format when DiL occurs over an entire 20 MHz channel or over multiple 20 MHz channels, and is based on the HE TB PPDU format when the transmission occurs over a portion of a 20 MHz channel.

[0082] Conventional MU transmissions mandate that the preamble 230 be identical for all transmissions. More precisely, for 802.11ax, the pre-HE modulated fields 400c (which constitute the preamble 230) must be exactly identical and emitted simultaneously on each 20 MHz band of the communication channel being used. This includes the preamble for DiL transmissions made by non-AP stations to targeted DiL non-AP stations.

[0083] When a station uses scheduled and / or random RUs to transmit data to the AP, the AP responds with a multi-user acknowledge frame 240 to acknowledge the data received on each RU. The acknowledge frame 240 may follow the NON_HT PPDU format (241) for block acknowledgment or the HE MU PPDU format (242) when transmitted over OFDMA RUs for RU-based acknowledgment.

[0084] For a DiL transmission, the destination DiL non-AP station may be expected to emit an acknowledge frame 260 on the same RU as the RU used for the DiL transmission 222. The acknowledge frame 260 may follow the SU format (FIG. 4a).

[0085] Multi-AP technologies are emerging in which APs 110, 120, and 130 cooperate to share a common communication channel depending on which of them is granted access to that channel. The APs exchange messages with each other to coordinate multi-AP communication, i.e., to avoid interference.

[0086] Multi-AP sharing of a common communication channel is resource-based. The amount of shared resources may be measured in time units, frequency bandwidth, number of streams, amount of data or traffic (e.g., bytes), and / or any other suitable units depending on the resource type as defined above. For example, RUs organized in a frequency band as shown in FIG. 2 may be shared, meaning that a first AP may offer one or more RUs to other APs. In this regard, the terms "shared resource," "shared frequency band," "shared channel," and "shared resource unit" are synonymous and refer to those resources offered by a coordinator AP to other APs through multi-AP technology.

[0087] To coordinate multi-AP communication, APs may be part of an inter-AP coordination group, where the formation of an inter-AP coordination group is beyond the scope of the present invention. By way of example, willing APs may proactively issue management frames, such as beacons or dedicated broadcast frames, to advertise their multi-AP coordination capabilities to other APs. A coordination group is also referred to as an AP candidate set for multi-AP sharing.

[0088] Figure 5 shows a transmission sequence for implementing the multi-AP technique for achieving coordinated OFDMA resource sharing. This is based on 802.11ax frames. However, other frames may also be used.

[0089] The trigger frame 210 has a non-HT replication format and is replicated in each 20 MHz channel that forms the communication channel (eg, 40 MHz for illustrative purposes).

[0090] A trigger frame 210 transmitted from a coordinator or "sharing" AP (AP1 for illustrative purposes) is configured to trigger MU transmissions for a wireless network (BSS2, managed by AP2 for illustrative purposes), i.e., to initiate multi-AP cooperation to share a portion of its TXOP with other BSSs. To this end, the trigger frame 210 allocates one or more resource units of the reserved communication channel (here a single resource unit (RU5) having a width of 20 MHz) to the other wireless network. In this respect, the trigger frame 210 acts as a frame announcing the sharing of the resources of the granted TXOP.

[0091] In the illustrated example sequence, the TF 210 transmitted by AP1 is sent to a non-AP STA (STA 11 , S.T.A. 12 , S.T.A. 13 , S.T.A. 14) in its primary 20 MHz channel. Thus, conventional MU UL transmissions 221 occur in the primary 20 MHz channel of that BSS, and non-AP STAs (STA 11 , S.T.A. 12 , S.T.A. 13 , S.T.A. 14 ) emit UL frames according to the HE TB PPDU format (FIG. 4c), in which all of the pre-HE modulated fields 400c (forming the preamble 230) are emitted by these stations only in the primary 20 MHz channel.

[0092] In addition to the conventional MU UL RU, one or more resource units for MU transmissions are allocated to a wireless network (BSS2 in the example) managed by another AP (AP2). From the perspective of the coordinating AP, the other AP (AP2) is viewed as a simple device, e.g., a station, that is not associated with the coordinating AP (AP1), i.e., that is not typically assigned an AID by the coordinating AP. The other AP is called the coordinated or "shared" AP and manages the shared resources allocated by the coordinating AP to its own BSS.

[0093] The allocation of resource units to the coordinated AP (AP2) is signaled by AP1 in the TF 210. Because there is no AID known by AP1 for AP2, a dedicated identifier may be used to populate the "AID12" subfield 341 of the corresponding "User Info" field 340. For example, the MAC address of the coordinated AP or the BSSID of the coordinated BSS may be used to signal that resource units are allocated to the coordinated AP / BSS (AP2 / BSS2).

[0094] Each of these allocated resource units occupies a frequency band consisting of channels that are multiples of 20 MHz (e.g., 20, 40, 60, 80 MHz, etc.). In other words, the multi-AP technology preferably subleases 20 MHz channels. The shared frequency band may be contiguous or perforated, and may or may not be adjacent to the primary channel of BSS1.

[0095] As mentioned above, each wireless network BSSx defines its own primary 20 MHz channel on which stations of this network will contend. The shared frequency band may or may not include the primary 20 MHz channel of the coordinated BSS (here, BSS2). If the shared frequency band does not include the primary 20 MHz channel of BSS2, AP2 and non-AP stations of BSS2 will need to temporarily switch their primary 20 MHz channels (until the end of resource sharing) to efficiently communicate together in this shared band.

[0096] The "new" (and temporary) primary 20 MHz channel for the coordinated BSS (BSS2) may be defined by the coordinator AP (AP1) in TF 210 (using the appropriate flag) or by rules known by all stations in the coordinated BSS.

[0097] The coordinated AP (AP2) uses the MU transmission resource unit (RU5 in the example) allocated to its own BSS (BSS2) to manage data exchange within its own BSS, particularly between non-AP stations in BSS2 and AP2.

[0098] Recursively, AP2 may sublease one or more 20 MHz channels of the shared resource unit thus obtained to other APs outside BSS2, such as AP3, in which case AP2 becomes the coordinator AP for AP3. For example, when the BSSID AP of a physical AP is transmitted to the coordinated device (AP2), it may allocate a portion of the shared frequency band to that BSSID that is not transmitted.

[0099] When managing data exchange within the shared resources of a cooperative transmission, the coordinated device can transmit data frames using a single-user (SU) format because the shared frequency band consists of one or more entire 20 MHz channels. However, it may also transmit data using a multi-user (MU) format, or a combination of both. The SU format used may be the HE SU PPDU format (Figure 4a) according to the IEEE 802.11ax standard, and the MU format used may be the HE MU PPDU (Figure 4b) according to the IEEE 802.11ax standard (alternatively, the EHT MU PPDU format according to the IEEE 802.11be standard is also possible). In the MU format, the frame (preamble) contains additional information (such as the identifier of the sender, i.e., the coordinated AP) that can be used by the receiver of the frame to quickly determine the sender of the PPDU (i.e., even before receiving the data field of the frame). This helps non-AP stations accurately identify whether they should process the frame (i.e., whether the frame came from a local AP).

[0100] For example, the MU procedure described with reference to FIG. 2 may be performed within a shared resource unit (RU5 in the example).

[0101] In this manner, the coordinated AP (AP2) issues a trigger frame 510 (in SU or MU format) to trigger a (second) MU UL transmission from a non-AP station in a second BSS (BSS2) via the allocated shared resource unit of the (first) MU transmission triggered by the coordinator AP (AP1). The coordinated AP (triggered by AP1 through the TF 210) becomes the triggering AP for the non-AP station in BSS2. The TF 510 defines its own Duration 312 (within the TXOP limit defined by the Duration 312 of the TF 210) and its own UL Length 332 for the MU UL transmission 530 of the non-AP station in BSS2.

[0102] Since the Coordinating AP (AP) is the only transmitter in the 20 MHz channel that forms the shared frequency band (if not subleased), the preamble 500 transmitted by the Coordinating AP on the 20 MHz channel (preamble to TF 510) does not overlap with the preamble 230 transmitted (simultaneously) by the STAs of BSS1 on other 20 MHz channels.

[0103] Subsequently, the non-AP station of BSS2 receives TF 510 transmitted by AP2 and determines from TF 510 whether it has been assigned an RU within the shared frequency band (RU5 in this example). Note that the RU defined in TF 510 is contained within and may be part of the shared RU defined in TF 210. The non-AP station of BSS2 may emit a triggered UL frame 530 (with preamble 520).

[0104] Additionally, the MU downlink frame (550—together with the preamble 540) may be carried within a shared frequency band authorized by AP1, within which AP2 may transmit AMPDUs for multiple non-AP stations of its BSS (BSS2).

[0105] The PHY preambles 500-520-540 have the same frequency bandwidth as the associated data 510-530-550, ie, for example, 20 MHz wide.

[0106] As shown in Figure 5, MU transmissions in the coordinated BSS (BSS2) may be shorter than those in the coordinator BSS (BSS1)—see the hatched area—and the coordinated AP (AP2) may transmit padding signals to maintain power in the shared frequency band across the entire TXOP.

[0107] At the end of the MU transmission on the shared frequency band, the stations in the coordinated BSS (BSS2) switch back to their original primary 20 MHz channel (if they had temporarily switched).

[0108] One critical requirement for this coordinated multi-AP procedure to function efficiently is the perfect reception of the trigger frame by all actors, including the coordinated AP and associated non-AP stations.

[0109] However, some non-AP stations in the coordinated BSS (e.g., stations managed by AP2 in BSS2) may be outside the transmission range of the coordinator AP (AP1) and therefore may not be able to receive the initial TF 210.

[0110] This is not an issue for non-AP stations in a BSS that has been assigned a shared frequency band that encompasses the primary 20 MHz channel. Indeed, in that case, the coordinated AP (AP2) will emit TF500 in the primary channel of the coordinated BSS (BSS2), and non-AP stations in this BSS that are out of range will be able to receive it and recognize that an MU sequence is coming.

[0111] However, this is difficult if the assigned shared frequency band does not encompass the primary 20 MHz channel of the coordinated AP (AP2). This is because a temporary switch of stations in the coordinated BSS (BSS2) is required to receive further communications (specifically, trigger frame 510) from the coordinated AP. However, non-AP stations in this BSS that are out of range cannot recognize such a switch without receiving the initial TF 210. As a result, they cannot participate in the coordinated TXOP, and in particular, cannot receive the TF 500 transmitted by their local AP (coordinating AP (AP2)) on the switched primary 20 MHz channel.

[0112] We propose an extended multi-AP procedure that addresses this concern, which is easily implemented in coordinated APs and provides flexible multi-AP sharing.

[0113] The enhanced procedure provides for the coordinated AP (or more generally, the coordinated device) and in response to the TF 210 (i.e., the frame announcing resource sharing) to transmit a re-announce frame that repeats the MAC payload of the received announce frame or repeats a large final data portion (e.g., the MAC header plus one or more start fields in the MAC payload) following a short initial portion of the announce frame. The short initial portion is made different so that stations can clearly distinguish between announce and re-announce frames. This is important for station operation to meet the sequence time (e.g., MU transmission begins SIFS after the re-announce frame).

[0114] The re-announcement ensures that all stations in the coordinated BSS (i.e., including out-of-range stations) become aware of the resource sharing defined in the MAC payload (which came from the initial / announcing TF 210).

[0115] Furthermore, simply repeating a copy of the MAC payload or a large portion of it (i.e., the common and fixed payload) keeps the processing complexity at the Coordinating AP very low, which is also well suited to the fact that the Coordinating AP has a very short time (only SIFS is guaranteed) after receiving the initial / announcing TF 210.

[0116] In this manner, a non-AP station in the coordinated BSS receives a re-announcement frame from a coordinated AP (AP2) separate from the coordinator AP (AP1) announcing its sharing of the resources of a given transmit opportunity (TXOP) to the coordinator equipment, and then switches its primary channel to the working channel of the shared resources in response to receiving the re-announcement frame, thereby (temporarily) becoming the primary channel for the coordinated BSS.

[0117] The coordinator AP may send an announce frame (initial TF) that includes a re-announce field indicating whether at least one coordinated AP involved in the resource sharing needs to re-announce the resource sharing. Subsequently, the coordinator AP receives re-announce frames from one or more coordinated APs that repeat the MAC payload of the announced frame or its large final data portion.

[0118] Although the above description of multi-AP technology focuses on coordinator APs and coordinated APs, the present invention contemplates any kind of device acting as a coordinator entity and a coordinated entity.

[0119] Similar to the allocation of RUs to DiL transmissions (see 222 in Figure 2), resource sharing can benefit P2P groups that can organize themselves to perform DiL transmissions within the shared resource, in which case the coordinated equipment is the P2P device (not the AP), e.g., the owner or administrator of the P2P group.

[0120] Similarly, any device (not only APs) can acquire a TXOP and decide to share it using the proposed mechanism. Therefore, the coordinator device can be different from the AP.

[0121] In other words, in addition to the coordinated BSS, other communication groups may be considered, such as the group of stations communicating in the direct link (introduced with reference to FIG. 2). In such short-range and dynamic network configurations, one station device may be elected as the group owner and act as the central hub for all P2P communications. As a result, the multi-AP (sharing) procedure may be applied to the direct link, where the device elected as the group owner for a given P2P group has a role equivalent to that of the coordinated AP, referred to above, for a given BSS.

[0122] Therefore, in the following description, an entity (e.g., a coordinator AP or a coordinator P2P station) that triggers a multi-AP-based coordination procedure to offer shared resources to other groups or BSSs will be referred to as a "coordinator device." Correspondingly, any entity that manages such other groups or other BSSs will be referred to as a "coordinated device," which may correspond, for example, to a coordinated AP in the context of other BSSs or to a group owner station in the context of a P2P group.

[0123] Figure 6a illustrates a schematic diagram of a communications device 600 configured to implement at least one embodiment of the present invention, such as any of the stations (AP or non-AP) shown in Figure 1. The communications device 600 may be a coordinator device, a coordinated device, or simply a station managed by a coordinator device or a coordinated device.

[0124] The communication device 600 may preferably be a device such as a microcomputer, a workstation, or a lightweight portable device. a central processing unit 601, such as a processor, designated as CPU; A memory 603 for storing executable code of a method or steps of the method according to an embodiment of the present invention, and registers adapted to record variables and parameters necessary for carrying out the method; and at least one communication interface 602 connected via a transmitting and receiving antenna 604 to a wireless communication network, for example a communication network according to one of the standards of the IEEE 802.11 family; and preferably includes a communication bus 613 connected thereto.

[0125] Preferably, a communication bus provides communication and interoperability between the various elements included in or connected to the communication device 600. The representation of a bus is not limiting, in particular a central processing unit may communicate instructions with any element of the communication device 600 directly or by using other elements of the communication device 600.

[0126] The executable code may be stored in a memory that may be either read-only, a hard disk, or a removable digital medium, such as a disk. According to an optional variant, the executable code of the program may be received by means of a communications network, via the interface 602, so as to be stored in the memory of the communications device 600 before being executed.

[0127] In an embodiment, the device is a programmable apparatus that uses software to implement embodiments of the invention, however, embodiments of the invention may alternatively be implemented in whole or in part in hardware (e.g., in the form of an application specific integrated circuit (ASIC)).

[0128] 6b is a block diagram that schematically illustrates the structure of a communications device 600 adapted, at least in part, to carry out the present invention. As shown, the device 600 comprises a physical (PHY) layer block 623, a MAC layer block 622, and an application layer block 621.

[0129] The PHY layer block 623 (here the PHY layer of the 802.11 standard) has the task of formatting, modulating or demodulating in any 20 MHz channel or common communication channel, and transmitting or receiving 802.11 frames to / from the wireless radio medium used, such as medium access trigger frames TF for reserving transmission slots, MAC data and management frames for interworking with legacy 802.11 stations, and OFDMA type MAC data frames with a width smaller than the 20 MHz legacy (usually 2 or 5 MHz).

[0130] The MAC layer block or controller 622 preferably includes a MAC 802.11 layer 624 that performs conventional 802.11ax MAC operations, and additional blocks 625 for at least partially performing the present invention. The MAC layer block 622 may optionally be implemented in software that is loaded into RAM 603 and executed by CPU 601.

[0131] Preferably, an additional block 625, called a Multi-AP Announcement Management Module, has different operations for carrying out parts of the present invention depending on the role played by the communication device 600. Because the same device can take on different roles over time, the additional block 625 is preferably designed to selectively perform different operations.

[0132] For example, and not exhaustively, operations for a communication device acting as a coordinator device may include selecting a coordinated device (AP or non-AP P2P station), generating an initial trigger frame announcing resource sharing and including, for example, an indication of RU allocations for stations in the same group and other groups and an indication of which coordinated device re-announcement frames need to be transmitted.

[0133] For example, and not exhaustive, operations for a communication device acting as a coordinated device may include receiving an announce (trigger) frame from a coordinator device, determining whether a re-announce frame needs to be sent, preparing the re-announce frame, if necessary, by reusing the MAC payload of the announce frame or a large data portion thereof, and configuring the PHY layer 623 to emit the re-announce (trigger) frame.

[0134] For example, and not exhaustively, operations for a communication device operating as a station in a coordinated group / BSS may include receiving a re-announce frame from the coordinated device, obtaining an indication from the received announce frame or the re-announce frame (if no announce frame was received) to ensure switching its primary channel, and performing a conventional frame exchange for PSP (DiL) or MU transmission.

[0135] The MAC 802.11 layer 624 and the multi-AP announcement management module 625 interact with each other to properly handle communications over OFDMA RUs addressed to multiple stations according to an embodiment of the present invention.

[0136] At the top of the diagram, an application layer block 621 runs applications that generate and receive data packets, for example video streams, etc. The application layer block 621 represents all of the stack layers above the MAC layer according to the ISO standard.

[0137] An embodiment of the present invention in a different aspect considers that one or more coordinated devices emit a control frame duplicating information from the initial trigger frame (the so-called "announce frame" emitted by the coordinator device) before transmitting their HE PPDUs in the acquired shared RU, so that all stations in the vicinity of the coordinated device (especially stations outside the coordinator's transmission range) can receive such information before starting to use the shared RU. Because the initial trigger frame signals multi-AP-based resource sharing, all stations receiving the trigger frame or a copy thereof become aware of such sharing and can therefore switch their primary channel if necessary. Because the resource allocation information that forms the majority of the initial TF received by the coordinated device is directly duplicated in the new control frame (the so-called "reannounce frame"), accurate, fast, and easy duplication can be achieved by the coordinated device for each 20 MHz channel in a synchronous manner.

[0138] The concept of the present invention is shown in Figure 7, which illustrates a transmission sequence similar to Figure 5 with an implementation of the present invention. Figure 8 is a flowchart illustrating the general steps of a communication device acting as a coordinator device, in accordance with an embodiment of the present invention, particularly during the sequence of Figure 7. Figure 9 is another flowchart showing the general steps of a non-coordinator communication device (i.e., a device acting as a coordinated device or simply as a station), in accordance with an embodiment of the present invention, particularly during the sequence of Figure 7.

[0139] As is already apparent from Figure 7, an initial trigger frame 710 is emitted over the communication channel to announce resource sharing based on multi-AP technology. This announcement frame is conceptually equivalent to TF 210 described above, but may optionally include additional indications, as further described below, to signal when re-announcement by the coordinated device is required.

[0140] The TF 710 is followed by a re-announce frame 720 that one or more coordinated devices (AP2) transmit SIFS after the announce frame 710. It is preferably emitted by the coordinated device in non-HT duplicate mode over the same 20 MHz channel as the TF 710 (or over any of a number of corresponding 20 MHz channels that match the capabilities of the coordinated device in terms of bandwidth operation). Optionally, the re-announce frame 720 may be transmitted over fewer channels, provided that it is emitted over at least the coordinated device's primary channel and channels of the shared frequency band assigned to the coordinated device (so that all stations in the same BSS receive the frame).

[0141] The re-announcement frame 720 may be named "Trigger Frame To Self" because it is directed to the BSS set (or group set) of the coordinated device that emits the frame.

[0142] According to the present invention, the re-announce frame 720 contains the same resource allocation data content as the TF 710, and in particular may be a binary repeat or copy of the entire MAC payload (or most of it except for one or more initiation fields) of the TF 710, in which all resource allocations (including resource sharing) are defined. This allows all stations included as coordinated devices in the same group / BSS to receive the resource allocations, even if they are outside the transmission range of AP1 and did not receive the initial announce frame 710.

[0143] Advantageously, when coordinated devices are involved in multi-AP resource sharing initiated by a coordinator device, they transmit identical re-announce frames 710 in parallel, preferably on the same 20 MHz channel, in a non-HT duplicated format, so that all stations in their BSS or group become aware of the resource sharing.

[0144] If the assigned shared frequency band requires it, the station switches from the primary channel to the appropriate channel (indicated in frames 710, 720 or known locally through predetermined rules).

[0145] The MU transmission 221, 510 may then begin SIFS after the reannounce frame 720 (including its preambles 230 and 500). Such MU transmissions are described above with reference to Figure 5. For example, the coordinated AP may also transmit a trigger frame on its (or its BSS's) assigned shared resources to trigger multi-user uplink transmissions on the assigned shared resources with non-AP stations in its own basic service set.

[0146] Furthermore, in embodiments seeking to reduce interference between adjacent 20 MHz channels, the preambles 500, 520, 540 are radiated across the entire 20 MHz band, while the associated data 520, 540, 560 is transmitted across a narrower band. For example, at one (or both) boundaries of a 20 MHz channel (consisting of 246 tones), an empty 26-tone RU may be defined (e.g., with AID=2046 in the corresponding User Info field 340). The empty RU is shown in the figure under reference numeral 599 and is the RU closest to AP1's primary channel.

[0147] As described above, the announcing TF 710 allocates resources, e.g., one or more RUs (here, RU5 defining the shared frequency band), to BSS2, e.g., by setting the BSSID of AP2 in the corresponding "AID12" subfield 341.

[0148] In an embodiment, the re-announcement process by the coordinated device (AP2) is systematic for the coordinated device (AP2) to receive the announcement frame 710. In that case, the TF 710 may be similar to the TF 210 described above.

[0149] This may apply to direct link RU communication: the mere determination that an RU is a direct link RU is sufficient to determine that a re-announcement is required. Similarly, this may apply to coordinated APs: the mere use of the coordinated AP's MAC address or BSSID (or a value derived therefrom) for RU allocation is sufficient to determine that a re-announcement is required.

[0150] In certain embodiments, only a coordinated device that needs to temporarily switch its primary channel (for reasons discussed above) will proceed with a resource sharing re-announcement for its peer station (which needs to switch), in which case the re-announcement frame is sent in response to determining from a received announce frame 710 that the shared resources allocated to the coordinated device do not include the coordinated device's primary channel (in which case a temporary switch is required).

[0151] In another embodiment, the coordinator device (AP1) may decide when the coordinated devices need to transmit the re-announce frame 720 and, optionally, which coordinated devices should do so.

[0152] For example, the coordinator device may know that all of the stations in the triggered BSS or group are within transmission range. In that case, all stations receive the announce frame 710 directly and there is no need to transmit the re-announce frame 720. The corresponding transmission time plus SIFS is omitted. Such a situation typically occurs when the coordinator AP is an AP of at least one originating BSSID that shares a portion of its time / frequency TXOP with at least one of the non-originating APs (all located within the same physical AP device).

[0153] In this context, the initial announcement frame 710 may include a re-announce field that indicates whether at least one coordinated device involved in the resource sharing needs to re-announce the resource sharing. Only the coordinated devices need to read the re-announce field of a received announcement frame to determine whether they need to re-announce the resource sharing.

[0154] In certain embodiments, all coordinated devices may be required to emit a re-announcement frame, which may be useful when the coordinator device performs a punctured TF due to the detection of some occupied channels that cannot be used during the communication TXOP reserved by the TF.

[0155] In certain embodiments, only a coordinated device that needs to temporarily switch its primary channel (for reasons discussed above) is required to re-announce resource sharing for other stations (that also need to switch), in which case the re-announce field indicates that the coordinated device that needs to switch its primary channel needs to re-announce resource sharing.

[0156] For example, the re-announce field may allow the coordinating AP to decide between no re-announcement (field set to 0) and re-announcement by the switching Coordinating AP (field set to 1), or between re-announcement by all of the Coordinating APs without primary channel switching issues (field set to 0) and re-announcement by the switching Coordinating AP (field set to 1), or even to decide between three options (thus the re-announce field consists of at least two bits).

[0157] Of course, any other conditions may be taken into account to select the subset of coordinated devices that will emit the re-announcement frame. For example, a subset of coordinated devices that are considered to be spatially far from the coordinator device may be selected. The spatial distance may be obtained by measuring low power signals (compared to a threshold). Such an example aims to extend the protection area by including stations in the vicinity of those devices.

[0158] More generally, a coordinator device may selectively choose which coordinated devices need to send re-announcement frames (e.g., depending on strategy rules and / or historical data), in which case the re-announcement fields are preferably provided at the resource level (e.g., at the User Info field level in the trigger frame).

[0159] In some embodiments, the re-announcement field is implemented in the Trigger Type subfield 331 of frame 710. The subfield 331 may be set to a value indicating that the collaboration trigger frame requests a re-announcement by the coordinated device. For example, one or more reserved values ​​(e.g., 8, 9) may be used.

[0160] In a variant, a specific subfield (e.g., a single bit serving as a re-announcement field) may be used as a signaling element for the re-announcement request. Such a subfield may be named "TF required", or "TF Duplication Required", or "TF-to-self Required", or any other suitable name.

[0161] In one implementation, bit 39 of the 802.11ax User Info field 340 (reference numeral 343 in FIG. 3) is used for this purpose. Alternatively, one or more bits in the Trigger Dependent User Info subfield 344 can be used. Advantageously, such RU-level bit(s) allow the coordinator AP to selectively choose which coordinated devices need to re-announce resource sharing. Also, the use of RU-level subfields is backward compatible with the existing 802.11ax TF format.

[0162] In another implementation, bits within the Common Info subfield 330 may be used. Such signaling is common to all of the coordinated devices. This preferably applies when all devices (except devices in the coordinator BSS) with assigned shared RUs are considered coordinated devices.

[0163] As an example, the "CS Required" bit (reference number 336 in FIG. 3) may be used, since it has no meaning in trigger frames for multi-AP technology. In a variant, the reserved bit B63 (reference number 334) may be used, or any bit or bits in the Trigger Dependent Common Info field 335 may be used. Such signaling at the Common Info field 720 level is also backward compatible with the existing 802.11ax TF format.

[0164] According to the present invention, the re-announce frame TF-to-self 720 has substantially identical payload content as the initial announcement frame TF 710. Due to the timing of the sequence (MU transmission starts SIFS after the re-announce frame 720), the re-announce frame 720 and the initial announcement frame 710 are different, and out-of-range stations need to know whether they are currently receiving the announcement frame 710 (in which case the re-announce frame 720 is expected) or the re-announce frame 720 (in which case the MU transmission starts SIFS later). Therefore, a short opening portion is made different between the two frames 710, 720.

[0165] In first embodiments where the short start portion consists of a MAC header and one (or two) or more start fields of the MAC payload, the Trigger Type subfield 331 in the Common Info field 330 may be used to identify the TF-to-self frame as a variable for the new trigger frame (using a reserved type value). Thus, stations only need to read this subfield 331 to clearly distinguish TF 710 from TF 720. In these embodiments, the remainder of the MAC payload (which defines the RU allocation, including resource sharing) may be kept unchanged. Optionally, the next field, the UL Length subfield 332, may be adjusted.

[0166] In a second embodiment, the re-announce frame 720 has an empty sender address (TA) field (with a value of 0 or NULL) or no TA field in its MAC header. This can be used advantageously if the entire MAC header is binary copied in the re-announce frame 720. In that case, the generation of the re-announce frame at the coordinated device is very simple and quick (only a SIFS period is guaranteed to generate the frame): it is simply a copy of the received announce frame 710, where the sender address (TA) field in the MAC header is emptied or removed. This may be used in conjunction with the first embodiment described above, in which one or more start fields in the MAC header are modified.

[0167] These embodiments allow any station to dynamically act as a coordinator device, since there is no need to identify the coordinator device in the frame. Thus, the sharing procedure proposed by the present invention is fully flexible.

[0168] Note that for consistency between the durations set in the re-announcement frame 720 and the initial announcement frame 710, it is desirable (but not required) for the re-announcement frame 720 to indicate a lower duration timer (in the Duration field 312) that again reserves the same airtime as the initial announcement frame 710. For consistency, the Duration field 312 specified in the initial announcement frame TF 710 encompasses the duration of the re-announcement frame 720 sent in response thereto, plus the SIFS and RU length (MU transmission time).

[0169] However, in some embodiments, the shared frequency band may be allocated to the cooperative group for a period corresponding to the "UL Length" subfield 332 indicated in TF 710. In that case, none of the stations in the coordinated group radiates after the UL Length 332 period, releasing the frequency band to the coordinator equipment. This leaves the final period of the TXOP unused on the shared frequency band: co-channel interference with AP1's BSS (primary 20 MHz channel) is avoided; furthermore, the BA frame 241 may be replicated by AP1 over the released frequency band to reset the NAVs of any nearby stations occupying the medium and operating on that 20 MHz channel.

[0170] 8 and 9, operation of various devices according to embodiments of the present invention will be described.

[0171] It is assumed that all devices (especially APs and P2P group owners) have an AP Candidate Set that lists other BSSs or P2P groups that would like to be granted new resources for data transmission (through multi-AP sharing). Based on such a Set and incoming resource requests from other APs and other P2P group owners, a coordinator device accessing the medium can decide to share resources.

[0172] 8, in step 801, a coordinator device (referred to as a coordinator AP) prepares a trigger frame 710 to trigger multi-user (MU) transmission for a coordination procedure. The TF 710 allocates some resource units to non-AP stations of its own BSS, and allocates one or more resource units to other BSSs and / or P2P groups using appropriate indications (e.g., BSSIDs or DiL session identifiers or MAC addresses in the corresponding AID12 subfields 341).

[0173] Also during the same step 801, the coordinator AP determines whether a coordinated device needs to send a re-announce frame 702 and, if applicable, which coordinated device should do so.

[0174] As mentioned above, the coordinator AP's decision may be included in dedicated re-announcement fields, such as the Trigger Type subfield 331 (different values ​​correspond to different re-announcement procedures), the B39 bit 343, one or more bits in the Trigger Dependent User Info subfield 344, one or more bits in the Common Info subfield 330 such as the "CS Required" bit 336 or bit B63 334, and one or more bits in the Trigger Dependent Common Info field 335. The coordinator AP may, for example, indicate that all coordinated devices should emit the re-announcement frame 720, or that only coordinated devices that switch primary channels should do so, or may indicate individually each coordinated device that should do so (e.g., using bit B39 343 for each shared RU).

[0175] The selection of RUs to allocate (share) to the coordinated devices may be made by the coordinator device taking into account whether the coordinated devices need to switch their primary channels. Preferably, the coordinator device tries to reduce the number of coordinated devices (and associated stations) that need to switch primary channels.

[0176] The coordinator device may be aware of the primary channels used by individual stations (e.g., a direct link session may appear to occur outside the coordinator AP's BSS, such that the direct link station's primary channel is not the same as the coordinator AP's primary channel) and / or the primary channels used by the coordinated BSS (e.g., the coordinator BSS and coordinated BSS may appear to have non-identical primary channels). In either case, the coordinated devices' primary channels are contained within the channel bandwidth operated by the coordinator AP (otherwise, they would not receive the initial announcement TF 710). As an example, a BQR trigger frame (standing for Bandwidth Query Report) may be used by the coordinator AP to trigger the most suitable channel for each of the coordinated devices / BSSs / P2P groups.

[0177] The initial announcement TF 710 thus prepared is transmitted by the PHY of the coordinator AP as described above in step 802 to trigger various stations (non-AP stations that are part of its own BSS, as well as other APs in other BSSs and / or coordinated devices such as P2P group owner stations) in each of the 20 MHz bands that are detected as free and form the common communication channel.

[0178] The initial announce TF 710 causes some coordinated devices to transmit re-announce frames 720. As a result, in step 803a, the coordinator AP expects to receive such control frames 720 (SIFS after the TF 710) from the triggered coordinated devices.

[0179] Optionally, the coordinator AP may send a re-announce frame 720 in parallel to one or more coordinated devices, step 803b, to allow, for example, some devices that had difficulty or problems receiving the initial announce frame 710 to reach those devices regardless of the BSS or group to which they belong.

[0180] Next, in step 804, the coordinator AP participates in MU communications (230, 221, 241) over the resource units maintained for its BSS. If the RU is an uplink RU, the coordinator AP receives data frames from non-AP STAs in its BSS.

[0181] Note that other transmissions occur in parallel in the shared frequency band that does not include the coordinating AP. For each shared DiL RU, the destination non-AP STA (for direct link communication) receives data frames from the P2P group owner via this RU. For each shared RU assigned to another BSS, MU transmissions occur within that other BSS (between non-AP STAs in that other BSS and the coordinated AP in that same BSS).

[0182] 9, in step 901, any non-coordinator device that is within the transmission range of the coordinator AP and whose primary channel carries any copy of the initial announce TF 710 receives the initial announce TF 710. The non-coordinator device may be a non-AP STA of any BSS, an AP of the BSS, or a STA in a P2P group.

[0183] Note that conventional trigger frames are processed in a conventional (e.g., 802.11ax) manner that is not shown in the flowchart.

[0184] The device may identify the received frame as a resource sharing announcement frame 710 using the information therein.

[0185] For example, the TF 710 may include a dedicated Trigger Type subfield 331 that identifies the announcement frame, thereby directing each receiving device to analyze the User Info element therein to determine whether it is involved in the subsequent MU transmission.

[0186] Alternatively, the device may parse each of the User Info elements of TF 710 to determine whether the resource is shared with other BSSs or P2P groups (e.g., whether the AID12 subfield contains a BSSID, a P2P session identifier, or a MAC address).

[0187] Other means for analyzing the received TF are also possible. For example, the device may have previously determined that its associated AP or group owner has notified other APs (potential coordinator devices) of its AP cooperation capabilities through a list of capabilities advertised in management frames (e.g., beacons or probe responses) transmitted by the AP or group owner.

[0188] In step 902, a non-coordinating device determines whether it acts as a coordinated device. Essentially, it does so when it is the AP of the BSS to which shared resources are assigned or the group owner of the P2P group. In fact, the presence of a BSSID or MAC address in the AID12 subfield of the User Info element (or any list of coordinated devices in that frame) is sufficient to determine that it is a coordinated device.

[0189] If test 902 is positive, then in step 903 the coordinated device retrieves the re-announce field (if any) from the received TF 710 in order to determine (test 904) whether the coordinated device needs to emit a re-announce frame 720.

[0190] If test 904 is positive, the coordinated device generates a re-announce frame 720 as described above, specifically by binary copying the MAC payload or a large data portion thereof, in addition to providing a MAC header with, for example, an empty TA field. The re-announce frame 720 is then transmitted SIFS after the first TF 710. This transmission is performed in parallel by all of the triggered coordinated devices in duplication mode. This is step 905.

[0191] The next step is step 906, where the device configures itself with the correct primary channel.

[0192] As indicated above, if a device's original primary channel is included in the shared resources allocated to itself and its BSS or P2P group, the device does not need to change its primary channel. Only the physical (PHY) layer is configured to perform MU operation over the allocated shared resource unit or units.

[0193] On the other hand, if a device's original primary channel is not included in the shared resources allocated to it and its BSS or P2P group, the device must temporarily switch its primary channel at the physical layer. If the allocated shared resources are larger than a single 20 MHz channel, only one 20 MHz channel will be the primary channel, and the other channels will be secondary channels.

[0194] If test 904 is negative, processing proceeds directly to step 906 for preparing the PHY layer.

[0195] Returning to test 902, if the result is negative, the device is not a coordinated device.

[0196] At test 907, the device determines whether it is associated with a TXOP 200.

[0197] For a non-AP station of the coordinating AP, this means that it has an RU assigned to it (the AID12 subfield of the User Info field contains its own AID).

[0198] For other devices that do not belong to the BSS of the coordinator AP, they need to determine whether their BSS or P2P group has shared resources allocated to it, which may be done by parsing the User Info field 340 of the RU to find the identifier (e.g., MAC address, DiL session identifier, BSSID) corresponding to their BSS or P2P group.

[0199] If the device is not interested in the TF 710, the process ends. Otherwise, the device waits to receive a re-announce TF 720 (step 908) (sent in parallel by the triggered coordinated device, possibly including its own local AP).

[0200] Following step 908, the device prepares its PHY for the correct primary channel (step 906 above), specifically switching its own primary channel if necessary.

[0201] Note that devices outside the transmission range of the coordinator AP do not receive the TF 710 (step 901). However, according to the present invention, devices involved in the TXOP 200 will eventually receive the re-announce frame 720 (at least from their local AP or the group owner). For these out-of-range devices, processing starts directly at step 908 (dashed arrow on the right side of the figure). Due to the specific signaling in the TF 720, these devices can determine that the received frame is a re-announce frame and not an initial TF 710.

[0202] Once the devices' PHYs are ready (before the SIFS following the re-announce TF 720), they participate in MU transmissions (starting SIFS after the TF 720) in their individually assigned RUs (step 909). At the end of the TXOP 200, devices that had switched primary channels switch back to their primary channels.

[0203] In this way, the present invention allows out-of-range stations to eventually become aware of resource sharing and temporarily switch primary channels to actually participate in MU transmissions. The present invention has low impact on the network (only the transmission time of the re-announce TF 720 plus SIFS) because, thanks to the almost entirely binary copy of the MAC payload, various coordinated devices can rapidly generate identical re-announce frames and transmit them in parallel (rather than sequentially).

[0204] Although the above description is based on frequency division, the proposed mechanism based on sequential announcement frames TF710 and re-announcement frames TF720 may also be applied using time division sharing (i.e., the various coordinated devices each get a time slot for their BSS sequentially and the communication operates in single user mode).

[0205] 3, the trigger frame format also includes an MCS subfield in the User Info field 340 corresponding to each RU. The MCS subfield indicates the modulation and coding scheme to be used. The coordinator device may specify a different MCS in the User Info field 340 of the shared resources allocated to the coordinated device (when preparing the frame in step 801). Based on this indication, the coordinated device may transmit a re-announcement frame 720 with a different MCS.

[0206] For example, a larger MCS may be indicated to reduce the impact of overhead due to the re-announcement frame 720. The value of MCS is preferably the same for all coordinated devices (so that the re-announcement frames transmitted by them are properly aligned with each other).

[0207] FIG. 10 illustrates another transmission sequence according to an embodiment of the present invention.

[0208] In this scenario, the APs are providing communication channels across three 20 MHz channels. AP1 acts as a coordinator AP, which means that TF 710 is an announcement frame sharing resources (here RU5 and RU6) with other BSSs or P2P groups. In this example, RU5 is assigned to BSS2 managed by AP2, while RU6 is assigned to STA DiL1 It is assigned to a P2P group managed by

[0209] AP2 and STA DiL1 receives announce frame 710 and, as the coordinated device, emits (in parallel) an identical re-announce frame 720 by repeating substantially all of the MAC payload (after a SIFS). In the figure, the coordinator device (AP1) is also transmitting a re-announce frame 720 in parallel.

[0210] Upon receiving the re-announce frame 720, all non-AP stations in BSS2 and the P2P group (including those outside the transmission range of AP1) become aware of the resource sharing and can temporarily switch their primary channel if necessary. They are ready to perform data transmission during the TXOP.

[0211] In this scenario, the transmission sequence within BSS2 is modified compared to Figure 7, and instead of having a preamble 500 and associated data 510, the coordinated AP2 starts communication in the shared RU with a DL transmission (DL MU PPDU - preamble 1000 and data RU 1010) lasting the entire UL Length 332 defined in TF 710. In other words, the coordinated device starts a multi-user downlink transmission over the allocated shared resources with non-AP stations of its own basic service set.

[0212] UL communication (UL PPDU-preamble 1020 and UL data 1030) may occur SIFS after DL communication in order to align communications between BSSs (here, BSS1 and BSS2), specifically aligning preambles, thereby reducing co-channel interference.

[0213] The DL MU PPDU (1000, 1010) is used to trigger the uplink RU so that the UL transmission occurs correctly without the emission of a trigger frame. In other words, the multi-user downlink transmission contains an indication of a subsequent multi-user uplink transmission opportunity on the allocated shared resources.

[0214] For example, some of the DL data frames include a TRS Control subfield (according to 802.11ax, the TRS Control subfield in the MAC header is used to initiate OFDMA transmission in the uplink direction, identify non-AP STAs participating in the UL MU transmission, and allocate RUs to these STAs). The resulting UL RU 1030 provides an opportunity for non-AP stations of the triggered BSS2 to emit UL data and / or acknowledgements for received DL data 1010.

[0215] Typically, the TRS subfield in the MAC header of a data frame is used to trigger a response (UL transmission) from the same non-AP station that received the DL data frame, which means that the same non-AP STA is addressed in both DL and UL.

[0216] To circumvent that limitation, the coordinated AP2 may consider using at least one DL RU in broadcast mode to transmit multiple MAC data frames, each with a separate TRS subfield, to each of multiple non-AP stations. Thus, the DL broadcast RU can trigger several different UR RUs during the next UL transmission (with signaled duration 1099).

[0217] Note that the DL plus UL communication sequence must fit within the original Duration 312 specified in the announcement frame TF710, and must be within the SIFS + TF720 duration + SIFS + UL Length 332 + SIFS + Duration 1099. <TF710のDuration312である。

[0218] In parallel, the shared RU6 is used for DiL transmission. Preferably, the DiL transmission is aligned with the MU transmission in BSS1 and BSS2. To achieve this, the UL Length field 332 of the TF 710 is set to (STA DiL1 From STA DiL2It is used to define the duration of a DiL transmission (to the STA) and may continue after a SIFS until the end of the TXOP (defined by Duration 312 in TF 710). DiL2 From STA DiL1 A second DiL transmission (to

[0219] Although the present invention has been described with reference to particular embodiments, it is not limited to those embodiments, and modifications within the scope of the invention will be apparent to those skilled in the art.

[0220] In particular, the different HE frame formats described in the different embodiments may be substituted for EHT frame formats where appropriate.

[0221] Many further modifications and variations will occur to those skilled in the art upon reference to the above described embodiments, which are given by way of example only and are not intended to limit the scope of the invention, which is determined solely by the claims. In particular, different features from different embodiments may be interchanged where appropriate.

[0222] 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. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage. [Explanation of symbols]

[0223] 110, 120, 130: AP, 112, 113, 121, 131: STA, 200: TXOP, 210: Control frame

Claims

1. A communication method in a wireless network, in a communication device functioning as an access point (AP), receiving a first communication frame from another AP indicating that the other AP will share time resources in a transmission opportunity (TXOP) with the communication device; determining whether to switch a primary channel of the communication device in response to receiving the first communication frame; When determining to switch the primary channel of the communication device, transmitting a second communication frame to prompt the non-AP station to switch the primary channel; After transmitting the second communication frame, transmitting a third communication frame to the non-AP station, the third communication frame triggering data transmission from the non-AP station according to a time resource allocation shared by the other AP to the communication device; A communication method comprising:

2. The communication method according to claim 1 , wherein the communication device transmits a second trigger frame as the third communication frame to the non-AP station of a basic service set managed by the communication device.

3. the communication device performs multi-user downlink transmission to the non-AP stations in a basic service set managed by the communication device using the time resources allocated by the other APs. The communication method according to claim 1 .

4. the communication device performs time division multiple access (TDMA) with the non-AP stations in a basic service set managed by the communication device using the time resources allocated by the other APs; The communication method according to claim 1 .

5. the first communication frame includes a first portion and a second portion indicating a sharing of time resources in the TXOP; The communication method of claim 1 , wherein the third communication frame includes information of the second portion of the first communication frame.

6. The communication method of claim 5 , wherein the second portion is a MAC payload of the first communication frame.

7. The communication method described in claim 1, wherein the communication device determines to switch the primary channel of the communication device when the frequency resources allocated to the communication device by the other AP do not include the primary channel of the communication device.

8. A communication device that functions as an access point (AP) in a wireless network, a receiver for receiving a first communication frame from another AP indicating that the other AP will share a time resource in a transmission opportunity (TXOP) with the communication device; a determination unit that determines whether to switch a primary channel of the communication device in response to receiving the first communication frame; a transmitter that transmits a second communication frame to a non-AP station when it is determined that the primary channel of the communication device should be switched, to prompt the non-AP station to switch the primary channel; a transmitter that, after transmitting the second communication frame, transmits a third communication frame to the non-AP station, the third communication frame triggering data transmission from the non-AP station according to a time resource allocation shared by the other AP to the communication device; A communication device comprising:

9. The communication device according to claim 8 , wherein the communication device transmits a second trigger frame as the third communication frame to the non-AP station of a basic service set managed by the communication device.

10. the communication device performs multi-user downlink transmission to the non-AP stations in a basic service set managed by the communication device using the time resources allocated by the other APs. The communication device according to claim 8.

11. the communication device performs time division multiple access (TDMA) with the non-AP stations in a basic service set managed by the communication device using the time resources allocated by the other APs; The communication device according to claim 8.

12. the first communication frame includes a first portion and a second portion indicating a sharing of time resources in the TXOP; The communication device of claim 8 , wherein the third communication frame includes information of the second portion of the first communication frame.

13. The communication device of claim 12 , wherein the second portion is a MAC payload of the first communication frame.

14. A communication device as described in Claim 8, wherein the judgment unit determines to switch the primary channel of the communication device when the frequency resources allocated to the communication device by the other AP do not include the primary channel of the communication device.

15. A computer included in a communication device that functions as an access point (AP) in a wireless network, receiving a first communication frame from another AP indicating that the other AP will share time resources in a transmission opportunity (TXOP) with the communication device; determining whether to switch a primary channel of the communication device in response to receiving the first communication frame; When determining to switch the primary channel of the communication device, transmitting a second communication frame to prompt the non-AP station to switch the primary channel; After transmitting the second communication frame, transmitting a third communication frame to the non-AP station, the third communication frame triggering data transmission from the non-AP station according to a time resource allocation shared by the other AP to the communication device; A program to execute.

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