Method and device for optimized multi-AP coordination

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 have been 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 problem of increased bandwidth and decreased latency requirements for wireless communication systems in dense environments, multi-user (MU) procedures have been developed to allow 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 of that BSS, in a wireless network. For example, one such MU procedure has been 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] Due to the MU feature, non-AP stations have 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 main fundamental channel of the wireless medium (usually a 20 MHz channel or a multiple of 20 MHz, known as the primary channel) over which stations (including the AP) conduct EDCA contention. 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 has gained 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). As an 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 association identifier (AID) of the non-AP station (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 an MU Uplink (UL) transmission when it gains access to the wireless medium. During an 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 of the same BSS using a 16-bit association identifier (AID) that was assigned to the non-AP stations of the same BSS when they registered with the AP, and / or using 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 the 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 especially important when neighboring APs operate on the same selected communication channel (or channels close enough to each other to communicate).

[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 cooperation 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 cooperation. Such an AP that participates in multi-AP cooperation and uses the shared resources is called a shared or coordinated AP. The corresponding BSS is known as a coordinated BSS.

[0011] A coordinator AP typically transmits a sharing announcement frame that defines which resources are assigned to which coordinated AP. A trigger frame may be used. A coordinated AP may schedule MU downlink (DL) and / or uplink (UL) transmissions for its associated non-AP stations within the constraints (usually in terms of frequency and time) of its assigned resources. Multi-AP cooperation is preferably dynamic, meaning that different APs of the same multi-AP group may 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. In order 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 with 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 out of range of the coordinator AP and therefore may not receive the shared announcement frame. As a result, these non-AP stations cannot switch their primary channel to the correct channel and cannot participate in the MU transmissions initiated by their local AP (where 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 the information mandatory for non-AP stations of its BSS, such as the primary channel and the bandwidth of the shared resource, and 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 made by different companies. In fact, the coordinated APs need to 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 for the equipment, but 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 a priori (e.g., during association) with associated non-AP stations in order for these non-AP stations to efficiently decode switch frames with a TA equal to the MAC address of the coordinator AP. Thus, the coordinator AP needs to 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 performing 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, in a wireless device, receiving, from a coordinator device to which a transmission opportunity (TXOP) has been granted, an announcement frame announcing a sharing of resources of the granted TXOP, the announcement frame comprising a short start 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 steps:

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

[0020] The wireless devices involved in this method, i.e. the coordinated device managing a group of wireless devices (e.g. a BSS or a 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 the re-announcement frame simply 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, which happens for example when the coordinated device is assigned shared resources declared at the very end of the announce frame. Thus, the various coordinated devices involved in the multi-AP procedure can form exactly the same 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 frame with a transmission opportunity (TXOP) announced for a resource sharing of the given 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 start 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 steps:

[0023] Thus, the coordinator device effectively drives a re-announcement of the 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) are inevitably 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-mentioned methods.

[0026] Optional features of embodiments of the invention are defined in the appended claims. Some of these features are described below with reference to methods, but they can 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 where the entire MAC payload is kept intact (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 is left intact, allowing the coordinated device to add signaling as needed.

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

[0030] In some embodiments, transmitting the re-announcement frame is further in response to determining that a re-announcement 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 a re-announcement is 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-announcement frame has a null or no sender address (TA) field in its MAC header. For example, the re-announcement frame may simply be a duplicate of the received announce frame, where the sender address (TA) field in the MAC header is nulled.

[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 a 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 for 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 non-AP stations 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 it, which may be made for 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 further 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 which, 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 some of the methods according to the 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] Since the present invention may be implemented in software, the present invention may be embodied as computer readable code for provision to a programmable apparatus on any suitable carrier medium. 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, audio, magnetic, or electromagnetic signals, e.g., microwave or RF signals. [Brief description of the drawings]

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

[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. With 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 not (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"), transmit / receive 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. Thus, one or more aspects taught herein may be incorporated into a phone (e.g., a mobile phone or a 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 example 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] The 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. The second wireless network BSS2 includes an AP 120 and three associated non-AP STAs 121, 122, and 123. The third wireless network BSS2 includes an AP 130 and three associated non-AP STAs 131, 132, and 133. In the following, BSSx represents any of the wireless networks, while 1x1, 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 anticipated. In this disclosure, the APs 110, 120, and 130 are also referred to as AP1, AP2, and AP3, respectively. A device may operate as an AP of one wireless network and simultaneously belong as an associated STA to another wireless network.

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

[0054] Direct communication (also known as Direct Link (DiL)) between non-AP STAs 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 situation of direct communication, which corresponds to a recent growing trend, is the existence of peer-to-peer (P2P) transmission between non-AP stations having the same primary channel, for example, between STA112 and STA113 as shown in the figure. Technologies that support P2P transmission between non-AP STAs that are not associated with the same BSS or associated with any BSS include, for example, WiFi-Miracast (RTM) and wireless display scenarios in addition to WiFi-Direct. Other technologies that support 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-compressed video 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 given a transmission opportunity (TXOP). A TXOP 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 of 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 on 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 supports 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, 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 BSSx, more specifically, trigger-based (TB) multi-user (MU) transmissions, including MU uplink (UL) transmissions to the APs of BSSx, 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 transmission opportunity TXOP 200. The TF is a control frame, for example in the legacy non-HT format of IEEE 802.11. The TF is transmitted by APx on a primary 20 MHz channel 250 if it 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 the reserved communication channel during the transmission opportunity (TXOP).

[0062] TF210 has the structure shown in Figure 3. This is a MAC header 310, including a standardized "Frame Control" field 311, a standardized "Duration" field 312 that defines the duration of the transmission opportunity (e.g., TXOP 200), a "RA" field that is set to the broadcast MAC address for BSSx 313, and a "TA" field that is set to the MAC address of the AP sending the trigger frame 314; MAC payload 320, 3 is a MAC frame 300 (representing Medium Access Control) consisting 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. Basically, 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 Fig. 3, each "User Info" field 340 corresponds to one RU. The order of the "User Info" fields 340 used in the TF 300 can be arbitrary, since 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 of variable length and whose content depends on the "Trigger Type" subfield 320. There are other fields that are not 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 present 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 presents the RUs (RU1 201 and RU3-RU8 203-208) to the non-AP stations for uplink (UL) transmission 221, and also presents DiL transmission capability 222 within a triggered MU transmission by allocating a resource unit (here RU2 202) for this purpose. Previously, the administrator, person in charge, or "group owner" of the P2P group may have notified the AP that the P2P group intends to have a new opportunity for a DiL transmission.

[0072] The DiL transmission proposed by the AP may be signaled in the associated “User Info” field 340 (i.e., the field corresponding to the proposed RU) by using an 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 the direct link communication). This may be assumed when the AP allows a P2P session (such as the DLS protocol when in a BSS) or is aware of a P2P protocol (outside a BSS and discovered by a beacon or discovery frame of the cooperation procedure) and provides an identifier for the session. Preferably, the DiL session identifier is bound to the 12-bit AID format, and it is up to the AP to assign a value different from the one assigned to the AID that identifies an individual non-AP station.

[0074] Alternatively, the "AID12" subfield 341 may carry the AID of a non-AP station of the P2P group, e.g., 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), since this type of address is widely known and shared among 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 the TF 210, non-AP stations start their MU transmissions (for UL or DiL transmissions) one SIFS after that TF. They start transmitting data frames in the High-Efficiency (HE) format introduced in 802.11ax.

[0076] High-Efficiency (HE) frames are introduced in 802.11ax. As shown in Figure 4, these frames start 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 only decodable 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 transmissions to one or more stations, specifically MU (multi-user) downlink (DL) transmissions 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, respectively the HE SU PPDU frame, the HE MU PPDU frame and the HE TB PPDU frame. These HE frames are used as examples in describing embodiments of the invention. However, other formats are of course possible. For example, the Extremely-High-Throughput (EHT) frame introduced in 802.11be may also be used.

[0078] Figure 4a shows the format of the HE SU PPDU. It includes an HE preamble consisting of a legacy preamble (L-STF, L-LTF, L-SIG with RL-SIG), HE-SIG-A (HE SIGNAL A), HE-STF (HE Short Training Field) and 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 (jointly 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 indicating a set of transmission parameters of the PPDU, such as bandwidth (BW), modulation and coding scheme (MCS), number of data streams, coding type, etc. The following field 401a is modulated on 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) and an additional field 401, HE-SIG-B (HE SIGNAL B), which is used to tell the non-AP station in which resource unit it will find its data (i.e., the allocation of RUs to the non-AP station). This is so that DL transmissions can be started directly without a prior triggering frame announcing the allocation of RUs. Thus, HE-SIG-B 401 defines how the RUs forming the DL MU transmissions are assigned to the non-AP station in order for the non-AP station to efficiently receive its 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 on the channel bandwidth, while data is modulated only on the relevant 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 (i.e., from one non-AP station) transmission in response to a trigger frame. The HE-Trig frame has a format very close to the HE SU PPDU, except that the duration of the HE-STF field is 8 μs. Notably, 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 in an entire 20 MHz channel or in entire 20 MHz channels, and based on the HE TB PPDU format when the transmission occurs in 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 field 400c (which constitutes the preamble 230) must be exactly the same and radiated simultaneously on each 20 MHz band of the communication channel used. This includes the preamble of a DiL transmission made by a non-AP station to a destination DiL non-AP station.

[0083] When a station uses scheduled and / or random RUs to transmit data to the AP, the AP responds with a multi-user acknowledgement to acknowledge the data received on each RU. The acknowledgement frame 240 may follow the NON_HT PPDU format (241) for block acknowledgment, or the HE MU PPDU format (242) when transmitted on an OFDMA RU 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 technology is emerging where APs 110, 120, 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 the multi-AP communication, i.e., to avoid interference.

[0086] The sharing of the multi-AP 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., number of bytes), and / or any other suitable units depending on the type of resource as defined above. For example, RUs organized in frequency as shown in FIG. 2 may be shared, which means that a first AP may offer one or more RUs to other APs. In this respect, "shared resources", "shared frequency band", "shared channel" and "shared resource unit" are synonymous and designate those resources offered by a coordinator AP to other APs through the 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 outside the scope of the present invention. As an example, APs willing to cooperate may proactively issue management frames, such as beacons or dedicated broadcast frames, to advertise their multi-AP coordination capabilities to other APs. The coordination group is also referred to as an AP candidate set for multi-AP sharing.

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

[0089] The trigger frame 210 has a non-HT replicated format and is replicated on each 20 MHz channel that forms a 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. For this purpose, 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 transmission are allocated to a wireless network (BSS2 in the example) managed by another AP (AP2). From the perspective of the coordinator AP, the other AP (AP2) is considered as just a device, e.g., a station, that is not associated with the coordinator AP (AP1), i.e., is not typically assigned an AID by the coordinator AP. The other AP is called the coordinated or "shared" AP and manages the shared resources allocated by the coordinator 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 such allocated resource unit occupies a frequency band consisting of a channel that is a multiple 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 20MHz channel on which the stations of this network will compete. The shared frequency band may or may not include the primary 20MHz of the coordinated BSS (here BSS2). If the shared frequency band does not include the primary 20MHz channel of BSS2, AP2 and non-AP stations of BSS2 will need to temporarily switch their primary 20MHz channels (until the end of resource sharing) to communicate together in this shared band efficiently.

[0096] The "new" (and temporary) primary 20 MHz channel for the coordinated BSS (BSS2) may be defined in the TF 210 by the coordinator AP (AP1) (using an 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) assigned 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 so acquired to other APs outside BSS2, such as AP3, in which case AP2 becomes the coordinator AP for AP3. As an 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 resource of the cooperative transmission, the coordinated device can transmit data frames using the single-user (SU) format, since the shared frequency band consists of one or more entire 20 MHz channels, but may also transmit data using the multi-user (MU) format or a mixture of them. The SU format used may be the HE SU PPDU format (Fig. 4a) according to the IEEE 802.11ax standard, and the MU format used may be the HE MU PPDU (Fig. 4b) according to the IEEE 802.11ax standard (alternatively, the EHT MU PPDU format according to the IEEE 802.11be standard is also conceivable). In the case of the MU format, the frame (preamble) has an HE-SIG-B field that 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 the reception of the data field of the frame). This helps non-AP stations to accurately identify whether they should process the frame (whether the frame comes 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 way, 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 stations 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 that forms a shared frequency band (if not subleased), the preamble 500 transmitted by the Coordinating AP on the 20 MHz channel (preamble to the 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 included 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] Also, the MU downlink frame (550 - with preamble 540) may be carried within a shared frequency band authorized by AP1, in 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 take less time than those in the coordinator BSS (BSS1) - see hatched area. In that case, 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 (eg, 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 original 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: in fact, 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 know that a 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), since a temporary switch of stations of the coordinated BSS (BSS2) is required to receive further communications from the coordinated AP (specifically the trigger frame 510). However, non-AP stations of 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 (the coordinated 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., to a frame announcing resource sharing) to transmit a re-announcement 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 the station can clearly distinguish between the announce frame and the re-announcement frame. This is important to ensure that the station's operation meets the sequence time (e.g., MU transmission starts SIFS after the re-announcement 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 part 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 after receiving the initial / announcing TF 210 (only SIFS is guaranteed).

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

[0117] The coordinator AP may send an announce frame (first TF) including a re-announce field indicating whether at least one coordinated AP involved in the resource sharing needs to re-announce the resource sharing. The coordinator AP subsequently receives re-announcement frames from one or more coordinated APs, each repeating the MAC payload of the transmitted announce frame or a large final data portion thereof.

[0118] Although the above description of multi-AP technology focuses on coordinator APs and coordinated APs, the present invention is directed to 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 FIG. 2), sharing of resources can be in the interest of P2P groups that can organize themselves to perform DiL transmissions within a shared resource, in which case the coordinated equipment is a P2P device (not an AP), e.g., an 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 a group of stations communicating in a direct link (introduced with reference to FIG. 2). In such short-range and dynamic network configurations, one station device may be elected as a group owner and act as a 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 equal 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 is called a "coordinator device." Correspondingly, any entity that manages such other groups or other BSSs is called a "coordinating device," which may, for example, correspond 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 communication device 600 configured to carry out at least one embodiment of the present invention, such as any of the (AP or non-AP) stations illustrated in Figure 1. The communication device 600 may be either 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 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 a communication bus 613 connected thereto.

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

[0126] The executable code may be stored in a memory that may be either read-only, 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 the communication network, via the interface 602, to be stored in the memory of the communication 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 generally 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 medium used via the wireless radio medium, such as, for example, 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 having 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 for performing 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, which is loaded into RAM 603 and executed by CPU 601.

[0131] An additional block 625, preferably 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. Since 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 exhaustive, 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 communications device acting as a coordinated device may include receiving an announce (trigger) frame from a coordinator device, determining whether a re-announcement frame needs to be sent, preparing the re-announcement 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-announcement (trigger) frame.

[0134] For example, and not exhaustive, operations for a communication device operating as a station in a coordinated group / BSS may include receiving a re-announcement frame from the coordinated device, obtaining an indication from the received announce frame or the re-announcement frame (if no announce frame was received) to ensure that it switches 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, such as 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 invention according to a different aspect considers that one or more coordinated devices emit a control frame duplicating the information of the initial trigger frame (so-called "announce frame" emitted by the coordinator device) before transmitting their HE PPDU in the acquired shared RU, so that all stations in the vicinity of the coordinated device (especially stations outside the transmission range of the coordinator) can receive such information before the use of the shared RU is started. Since the initial trigger frame signals multi-AP based resource sharing, all stations receiving the trigger frame or a copy thereof will be aware of such sharing and can therefore switch their primary channel if necessary. Since the resource allocation information forming the majority of the initial TF received by the coordinated device is directly copied in the new control frame (so-called "re-announce frame"), an accurate, fast and easy duplication can be achieved by the coordinated device for each 20 MHz channel in a synchronous manner.

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

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

[0140] The TF 710 is followed by a re-announcement frame 720 that one or more coordinated devices (AP2) transmit after the SIFS of the announcement 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 all of the corresponding 20 MHz channels that match the capabilities of the coordinated device in terms of bandwidth operation). Optionally, the re-announcement frame 720 may be transmitted on fewer channels, provided that it is emitted on at least the coordinated device's primary channel and the channels of the shared frequency band assigned to the coordinated device (so that all of the stations of 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 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 start fields) of the TF 710, where 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 the same re-announcement frame 710 in parallel, preferably on the same 20 MHz channel, in a non-HT duplicated format, in this way 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 to the appropriate channel (indicated in frames 710, 720 or known locally through predefined rules) of the primary channel.

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

[0146] Furthermore, in an embodiment that seeks to reduce interference between adjacent 20 MHz channels, the preambles 500, 520, 540 are radiated over the entire 20 MHz band, while the associated data 520, 540, 560 is transmitted in 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 the 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 a particular embodiment, 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 stations, in which case the re-announcement frame is also sent in response to determining from a received announcement frame 710 that the shared resources assigned 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-announcement frame 720 and, optionally, which coordinated devices have to do so.

[0152] For example, the coordinator device may know that all of the stations of the triggered BSS or group are within transmission range. In that case, all stations receive the announce frame 710 directly and do not 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 the time / frequency TXOP with at least one of the non-originating APs (all located in the same physical AP device).

[0153] In this context, the initial announcement frame 710 may include a re-announce field indicating 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. This 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-announcement field may allow the coordinator AP to decide between no re-announcement (field set to 0) and re-announcement by the switching coordinated AP (field set to 1), or between re-announcement by all of the coordinated APs without a primary channel switching issue (field set to 0) and re-announcement by the switching coordinated AP (field set to 1), or even to decide between the three options (so that the re-announcement 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 is considered 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 ​​(8, 9, etc.) 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 number 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 or bits 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 in the Common Info subfield 330 may be used. Such signaling is common to all of the coordinated equipment. This preferably applies when all devices (except for devices in the coordinator BSS) that have an assigned shared RU are considered as coordinated equipment.

[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, as well as any bit or bits in the Trigger Dependent Common Info field 335. Such signaling at the Common Info field 720 level is also backward compatible with the existing 802.11ax TF format.

[0164] According to the invention, the re-announcement 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-announcement frame 720), the re-announcement 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-announcement frame 720 is expected) or the re-announcement frame 720 (in which case MU transmission starts SIFS later). Therefore, a short start portion is made different between the two frames 710, 720.

[0165] In a first embodiment where the short start portion consists of the 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 new trigger frame variant (with 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 as is. 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 value 0 or NULL) or no TA field in its MAC header. This may 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 in the coordinated device is very simple and quick (only a SIFS period is guaranteed to generate the frame): it is just a copy of the received announce frame 710, where the sender address (TA) field of the MAC header is emptied or removed. This may be used together with the first embodiment described above, where one or more start fields of 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, therefore 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 preferable (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 assigned 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 will radiate after the period of UL Length 332 and release the frequency band to the coordinator equipment. This ensures that the final period of TXOP is not used in 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 any NAVs of nearby stations occupying the medium and operating in 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 given 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 (called 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 in its own BSS, and allocates one or more resource units to other BSSs and / or P2P groups using appropriate indications (e.g., BSSID or DiL session identifier or MAC address in the corresponding AID12 subfield 341).

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

[0174] As mentioned above, the decision of the coordinator AP may be included in a dedicated re-announcement field, for example, in 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 need to emit the re-announcement frame 720, or that only the coordinated device that switches the primary channel needs to do so, or may indicate individually each coordinated device that needs to do so (e.g., using bit B39 343 for each shared RU).

[0175] The selection of RUs to assign (share) to the coordinated devices may be done 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 BSS of the coordinator AP such that the primary channel of the direct link station is not the same as the primary channel of the coordinator AP) and / or the primary channels used by the coordinated BSS (e.g., the coordinator BSS and the coordinated BSS may appear to have non-same primary channels). In either case, the primary channels of the coordinated devices 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 as described above in step 802 by the PHY of the coordinator AP to trigger various stations (some non-AP stations in 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 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, for example to allow some devices that had difficulty or problems receiving the initial announce frame 710 to be reached regardless of the BSS or group to which they belong.

[0180] The coordinator AP then participates in MU communication (230, 221, 241) via the resource units maintained for its BSS in step 804. 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 take place in parallel in the shared frequency band that does not include the coordinator 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 take place within that other BSS (between a non-AP STA 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 a 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 another BSS or P2P group (e.g., whether the AID12 subfield contains a BSSID, a P2P session identifier, or a MAC address).

[0187] Other means for analysis of the received TF are also possible: for example, the device may have previously determined that its associated AP or group owner has informed other APs (potential coordinator devices) of its AP cooperation capabilities through a list of advertised capabilities 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 the 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 the test 902 is positive, then in step 903, the coordinated device retrieves the re-announcement field (if any) from the received TF 710 in order to determine (test 904) whether the coordinated device needs to emit a re-announcement frame 720.

[0190] If the 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 part thereof, in addition to providing a MAC header with, for example, an empty TA field, and transmits the re-announce frame 720 SIFS after the first TF 710. This transmission is done in parallel by all of the triggered coordinated devices in the duplicate 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 the 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, and only the physical (PHY) layer is configured with the MU operating over the allocated shared resource unit or units.

[0193] On the other hand, if the device's original primary channel is not included in the shared resources allocated to itself 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, then 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 coordinator 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 been assigned shared resources, which may be done by parsing the User Info field 340 of the RU to find the identifiers (e.g., MAC address, DiL session identifier, BSSID) corresponding to their BSS or P2P group.

[0199] If the device is not associated with 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-announcement frame 720 (at least from their local AP or the group owner). For these out-of-range devices, the process starts directly at step 908 (dashed arrow on the right side of the figure). Due to the unique signaling in the TF 720, these devices can determine that the frame they received is a re-announcement frame and not an initial TF 710.

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

[0203] Thus, the present invention allows out-of-range stations to eventually become aware of the resource sharing and temporarily switch their primary channel to actually participate in the MU transmission. 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 (not 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. each of the various coordinated devices sequentially gets a time slot for its BSS and the communication operates in single user mode).

[0205] Also, as shown in Figure 3, the format of the trigger frame 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 assigned 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 correctly 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 the 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 the 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 Fig. 7 and, avoiding 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 for the entire UL Length 332 defined in TF 710. In other words, the coordinated device starts a multi-user downlink transmission over the assigned 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. This is to align communications between BSSs (here BSS1 and BSS2), specifically aligning preambles, which reduces co-channel interference.

[0213] The DL MU PPDU (1000, 1010) is used to trigger the uplink RUs 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 assigned shared resources.

[0214] For example, part of the DL data frame includes 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 assign RUs to these STAs). The resulting UL RU 1030 provides an opportunity for the triggered non-AP stations of BSS2 to emit UL data and / or acknowledgements for the 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, meaning that the same non-AP STA is addressed in both DL and UL.

[0216] To avoid 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, for each of multiple non-AP stations. Thus, the DL broadcast RU can trigger several distinct 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 the duration must be SIFS + TF720 + 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 that, the UL Length field 332 of the TF 710 is set to 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 TF710). DiL2 From STA DiL1 A second DiL transmission (to

[0219] Although the present invention has been described with reference to specific embodiments, it is understood that the present invention is not limited to those embodiments, and modifications that fall within the scope of the present 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 replaced with 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, comprising: receiving a first trigger frame from another AP that has been granted a transmission opportunity (TXOP), the first trigger frame indicating a sharing of time resources in the TXOP, the first trigger frame including time resource allocation information; transmitting a second trigger frame generated based on the time resource allocation information; and 13. A communication method comprising:

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

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

4. the communication device performs time division multiple access (TDMA) with a non-AP station of a basic service set managed by the communication device using the assigned time resource; The communication method according to claim 1 .

5. the first trigger 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 second trigger frame includes information of the second portion of the first trigger frame.

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

7. A communication device that functions as an access point (AP) in a wireless network, A receiver that receives a first trigger frame from another AP that has been granted a transmission opportunity (TXOP), the first trigger frame being a trigger frame indicating sharing of time resources in the TXOP, the first trigger frame including time resource allocation information; a transmitter that transmits a second trigger frame generated based on the time resource allocation information; A communication device comprising:

8. The communication device according to claim 7 , wherein the communication device transmits the second trigger frame to a non-AP station of a basic service set managed by the communication device.

9. the communication device performs multi-user downlink transmission with non-AP stations of a basic service set managed by the communication device using the allocated time resources; The communication device according to claim 7.

10. the communication device performs time division multiple access (TDMA) with a non-AP station of a basic service set managed by the communication device using the assigned time resource; The communication device according to claim 7.

11. the first trigger frame includes a first portion and a second portion indicating a sharing of time resources in the TXOP; The communication device of claim 7 , wherein the second trigger frame includes information of the second portion of the first trigger frame.

12. The communications device of claim 11 , wherein the second portion is a MAC payload of the first trigger frame.

13. A computer included in a communication device that functions as an access point (AP) in a wireless network, receiving a first trigger frame from another AP that has been granted a transmission opportunity (TXOP), the first trigger frame indicating a sharing of time resources in the TXOP, the first trigger frame including time resource allocation information; transmitting a second trigger frame generated based on the time resource allocation information; and A program for executing the above.

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