Methods and devices for controlling OBSS-driven operations at associated stations, and frame classification

Abstract

When a Multi-AP coordination is setup, the APs involved in the MAP group send a controlling frame to their associated STAs to disable a NPCA mechanism or to provide them with a list of non-OBSS APs. As a consequence, the STAs remain available on their primary channel during a MAP coordination period, although some received MAP frames come from APs different from their own BSS. The STAs can participate to intra-BSS communications when their BSS is offered a transmission opportunity during the MAP cooperation. Furthermore, a frame classification allowing the stations to discriminate between intra-BSS frames, MAP frames and inter-BSS frames allow them not to automatically set their basic NAV in case of MAP coordination, but set their basic NAV for the specific serving periods not allocated to their BSS during the MAP cooperation.

Description

[0001] METHODS AND DEVICES FOR CONTROLLING OBSS-DRIVEN OPERATIONS AT ASSOCIATED STATIONS, AND FRAME CLASSIFICATION

[0002] FIELD OF THE INVENTION

[0003] The present invention generally relates to wireless communications and more specifically to wireless communications in case of coexistence between OBSS interference and Multi-AP (MAP) coordination.

[0004] BACKGROUND OF THE INVENTION

[0005] Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the 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.

[0006] In dense multiple AP networks, co-channel interference becomes a problem.

[0007] Overlapping Basic Service Set (OBSS) interference refers to interference resulting from transmissions of another BSS.

[0008] The stations usually adopt a specific behaviour (“OBSS behaviour” or “OBSS-driven behaviour”) in case OBSS interference is detected, in order to avoid useless collisions on the communication channel. An OBSS behaviour is made of a set of actions (“OBSS actions” or “OBSS-driven actions”) the station can take when OBSS interference is detected.

[0009] A conventional OBSS behaviour requires that a station receiving a frame that is not addressed to it, which is the case for inter-BSS (OBSS) frame emitted by another BSS, defers its access to the medium by setting its basic Network Allocation Vector NAV for a duration specified in the received frame. During this period of time, the station can adopt an OBSS-driven action such as entering a Power Save (PS) mode.

[0010] As BSSs sharing the same channel compete one to each other, methods for AP coordination appear useful to improve the utilization of the limited radio resources.

[0011] The IEEE (Institute of Electrical and Electronics Engineers - RTM) 802.11 be draft standard Task Group addresses a so-called Multi-Access Point (Multi-AP or MAP) technology which aims at providing some collaboration between neighbouring access points (APs) managing separate BSSs in order to have a more efficient utilization of time, frequency and spatial resources available. This is particularly important when the neighbouring APs operate over the same selected communication channel (or channel sufficient close to communicate which each other) in which interference may occur. In that case, the BSSs are referred to as overlapping BSSs or OBSSs. The MAP mechanisms, now addressed by the 802.1 1 bn Task group, allow two or more neighbouring APs to share resources in terms of frequency and / or time and, in this way, they cooperate together to enhance the performance of the network by smartly managing the OBSS interference.

[0012] For example, the MAP coordination can use the Triggered TXOP sharing procedure (section 35.2.1 .2 of the draft IEEE P802.11 be(RTM) / D5.0 standard), so that a sharing AP, i.e., an AP owning a TXOP, allocate a portion of the obtained TXOP to one or several shared APs for their own BSS communications. This allows to minimize the competition between neighbour BSSs to gain the medium and so the potential collision as each BSS can use the medium more regularly. The MAP coordination finally aims at improving the overall usage of the medium resources. Besides the Triggered TXOP Sharing procedure (or “TXS”) defined in section 35.2.1 .2 of the draft IEEE P802.1 1 be(RTM) / D6.0 standard that allows a temporal sharing, other sharing procedures such as MU (Multi User) operations defined in sections 26.5 and 35.5 of IEEE802.11 be are also envisioned in the MAP context to share the frequency resource through the set of APs.

[0013] Besides MAP coordination, 802.1 1 bn also introduced the Non-Primary Channel Access (NPCA) or Secondary Channel Access (SCA) as a new OBSS behaviour for the stations to improve OBSS interference management. The NPCA mechanism allows the stations (AP and non-AP) of a BSS to move from their common primary channel to a predefined secondary channel for channel access, when they detect OBSS interference on the primary channel. Once on the secondary channel used for NPCA, the stations can communicate together during the duration of the TXOP of the OBSS interference (“OBSS TXOP”). The stations of the BSS go back to the primary channel no later than the end of the OBSS TXOP.

[0014] Both MAP and NPCA mechanisms seem very promising.

[0015] However, the MAP mechanism raises coexistence issues with OBSS behaviours, such as the NPCA and PS mechanisms, the stations can use in case of OBSS interference.

[0016] For instance, if an AP BSS gets a transmission timeslot from a sharing AP through the MAP cooperation while some of its associated stations enter the PS mode or switch to another channel for NPCA, due to the MAP frame, it is no longer possible for the AP to communicate with those stations. The stations have missed the communication opportunity offered by the sharing AP to their BSS.

[0017] SUMMARY OF INVENTION

[0018] It is a broad objective of the present invention to overcome some of the foregoing concerns.

[0019] The inventors have noticed that a better classification of the MAP frames to be opposed to the intra-BSS and inter-BSS (or OBSS) frames could be helpful for the stations to adopt appropriate behaviours, in particular to take part of intra-BSS communication within a communication opportunity offered by a sharing AP through the MAP mechanism. They also have noticed that a better control on the OBSS behaviours the stations adopt in case of OBSS interference could allow the APs to keep their associated stations be involved in a communication opportunity offered by a sharing AP through the MAP mechanism.

[0020] In this context, first embodiments of the disclosure include a communication method in a wireless network, comprising at an access point (AP) managing a Basic Service Set (BSS): sending to at least one station of the BSS, a frame including a parameter to control a behaviour of the station in case the station detects Overlapping-BSS (OBSS) interference.

[0021] Correlatively, the first embodiments also provide a communication method in a wireless network, comprising at a station belonging to a Basic Service Set (BSS) managed by an access point (AP): receiving from the AP, a frame including a parameter to control a behaviour of the station in case the station detects Overlapping-BSS (OBSS) interference.

[0022] “Behaviour of the station” means actions the station takes, i.e., use of a mechanism driven by the OBSS.

[0023] By acting on the OBSS-driven mechanisms at the station level (e.g., enabling them, disabling them, pausing them, resuming them, and so on), the AP can keep its associated stations in awake state on the primary channel of the BSS in order to be available for intra-BSS communications within a timeslot offered by another BSS (OBSS). Network efficiency is therefore improved.

[0024] Optional features are defined below with reference to methods, while they can be transposed into device features.

[0025] In some embodiments, the parameter controls whether the station uses an OBSS- driven mechanism or not in case the station detects OBSS interference.

[0026] For instance, the parameter may define an activation or deactivation (enabling or disabling) of the OBSS-driven mechanism at the station. A control of the OBSS-driven operations at BSS level can therefore be obtained.

[0027] In other embodiments, the parameter includes a list of APs based on which the station triggers an OBSS-driven mechanism. A more homogeneous use of the OBSS-driven operations throughout the BSS is obtained, since the shared list allows the stations and the AP to have the same view with respect to OBSS and MAP coordination.

[0028] In particular embodiments, the list of APs includes a list of APs belonging to a Multi- AP (MAP) Group with which the AP has set up collaboration for medium sharing. A non-OBSS AP list is therefore transmitted to the stations. The list allows them to directly identify the APs for which detected activity may not trigger OBSS-driven operations in order to remain available for intra-BSS communication during the MAP cooperation.

[0029] In variants, the list of APs includes a list of APs in the vicinity of the AP, i.e., APs that are considered as OBSS APs for the stations of the BSS. An OBSS AP list is therefore transmitted to the stations. The list allows them to directly identify the APs for which detected activity may trigger OBSS-driven operations in order to remain available for intra-BSS communication during the MAP cooperation.

[0030] In some embodiments, the list of APs excludes any AP belonging to a Multi-AP (MAP) Group with which the AP has set up collaboration for medium sharing. This is to have the exact list of which APs have to be considered as OBSS APs because they are not likely to provide any transmission opportunity to another BSS through MAP coordination.

[0031] In some embodiments, the given OBSS-driven mechanism includes a Power Save mode, a switch to another communication channel, such as a Non-Primary Channel Access mechanism.

[0032] In some embodiments, the frame is sent responsive to a change in a Multi-AP (MAP) coordination scheme. A general approach based on MAP status is therefore implemented.

[0033] In specific embodiments, the change includes a setup of a MAP agreement involving the AP or a partial or full teardown of a MAP agreement involving the AP. For instance, a setup of a MAP agreement may disable an OBSS-driven mechanism while or a partial or full teardown of a MAP agreement may enable the OBSS-driven mechanism.

[0034] In some embodiments, the frame is sent responsive to determining that the number of other (i.e. , OBSS) APs in the vicinity of the AP and / or an amount of data to be exchanged within the BSS are lower than respective thresholds. A control of the OBSS-driven mechanism at the stations that is adjusted to network activity can therefore be obtained.

[0035] In some embodiments, the parameter is included in one from an Operating Mode Notification frame (especially adapted to enable or disable a station OBSS-driven mechanism), a Beacon frame, a Probe Response frame and a Channel Usage element having a Usage mode set to a Multi-AP coordination value, meaning the element is dedicated to signal information about the MAP coordination.

[0036] Furthermore, second embodiments of the disclosure include a communication method in a wireless network, comprising at station belonging to a first Basic Service Set (BSS) managed by a first access point (AP): performing a frame classification of a received frame as an intra-BSS frame or a Multi-AP (MAP) frame or an inter-BSS frame, in which a non-intra-BSS frame is classified as a MAP frame if the received frame signals medium sharing between APs belonging to a MAP Group to which the first AP belongs, or classified as inter-BSS frame otherwise.

[0037] For example, the received frame has a receiving address (RA) not set to an address of the station.

[0038] The station may be the first AP itself or a non-AP STA associated to the first AP.

[0039] A non-intra-BSS frame is a frame that is not classified as an intra-BSS, i.e., a frame sent by another station of the first BSS or in the same multiple BSSID set or wildcard.

[0040] The proposed three-level classification of the frame allows the stations to better behave, in a simpler way, as frames from another BSS are received. Optional features are defined below with reference to the method, while they can be transposed into device features.

[0041] In some embodiments, responsive to classifying the received frame as an inter-BSS frame, the station sets a basic NAV with duration information indicated by the received frame.

[0042] In some embodiments, responsive to classifying the received frame as an intra-BSS frame, the station sets an intra-BSS NAV (different from the basic NAV) with duration information indicated by the received frame. In particular, after sending a clear-to-send response solicited by a Multi-User (MU) Request-to-Send (RTS) Trigger frame from the first AP, the station ignores the intra-BSS NAV either until an end of a time allocation signaled in the MU-RTS Trigger frame or until the allocated time is returned to an owner of a Transmission Opportunity (TXOP) defined by the MU-RTS Trigger frame, whichever happened earlier. The MU-RTS Trigger frame may be an MU-RTS TXS (TXOP Sharing) Trigger frame.

[0043] In some embodiments, responsive to classifying the received frame as a MAP frame, the station sets a MAP NAV (different from the basic and intra-BSS NAV) with duration information indicated by the received frame. Using a dedicated NAV for MAP frame eases the handling of the station’s behaviour in case of MAP frame.

[0044] In alternative embodiments, responsive to classifying the received frame as a MAP frame, the station sets its intra-BSS NAV with duration information indicated by the received frame. This ensures the station is available for communications triggered by its associated AP within a shared resource offered by a sharing AP through MAP cooperation.

[0045] Also, with respect to the AP, responsive to classifying the received frame as a MAP frame, the station, operating as the first AP, sets its basic NAV with duration information indicated by the received frame and ignores the basic NAV to respond to any MAP frame from another AP allocating the medium to the first BSS. This particularly applies to those APs which have only one NAV (the basic one).

[0046] In some embodiments, responsive to classifying the received frame as a MAP frame, the station replies to the MAP frame by sending an acknowledgment frame indicating a duration equal to the sum of the duration of a serving period triggered by the MAP frame and the duration of a subsequent MAP frame to offer a subsequent serving period. This is for the stations out of the range of the sharing AP to remain available to join any subsequent serving period for their BSS during the MAP coordination.

[0047] In some embodiments, if the received frame is a MAP frame allocating a serving period to another BSS than the first BSS and serving period truncation is allowed for the serving period, the station sets an intra-BSS NAV and waits for a communication from the first AP during a duration of the serving period. To be able to wait for communication from its AP, the station either does not apply OBSS-driven operations such as NPCA or has capabilities (such as the EMLSR feature) to still listen on the medium of the first AP, while performing OBSS-driven operations. By remaining on the medium of the first AP, the station will not miss any potential TXOP return indication and so the start of a possible serving period for its BSS. In specific embodiments, the station exchanges with the first AP station’s capabilities to support listening of serving period truncation while applying OBSS-driven operations when a received frame is a MAP frame allocating a serving period to another BSS than the first BSS. By applying the OBSS-driven operations despite the MAP coordination, the station can still exchange frames while remaining available for switching to subsequent serving period allocated to its BSS. This improves network efficiency.

[0048] In some embodiments, the received frame is a MAP frame allocating a serving period to the first BSS for a serving duration, and the first AP sends, to a sharing AP transmitting the MAP frame, an indication of anticipated end of the service period to give the medium back to the sharing AP before an end of the serving duration. Anticipated return of the TXOP to the sharing AP is therefore made available.

[0049] In embodiments, the received frame may be a MAP frame allocating a serving period to the first BSS for a serving duration, and the station, operating as the first AP, may also receive, from a sharing AP transmitting the MAP frame, an indication that truncation (i.e., anticipated end) of the serving period is allowed for the first AP.

[0050] In some embodiments, the received frame is classified as a MAP frame using signalling information, the signalling information comprising at least one of: a Trigger Type subfield of a Common Info field of a trigger frame set to a MAP type; a bit or field defined in the Common Info field set to a MAP type; a Triggered TXOP Sharing Mode subfield of a Common Info field of a trigger frame set to a MAP type; a Special User Info field that includes a bit or field set to a MAP type; a field in a User Info field of a trigger frame set to an association identifier (AID) defined during setting a MAP agreement and dedicated to a BSS different from the BSS sending the frame; both RA and TA fields set to MAC addresses of two different APs;

[0051] DA and / or SA fields set to MAC addresses of AP(s) of a MAP group;

[0052] BSSID field set to a value dedicated to identify a MAP group; a Public Action field value of a Public Action frame set to a MAP type; or a field in an element of a BSS Coexistence Management frame set to a MAP type.

[0053] In some embodiments, the received frame is classified as a MAP frame when the received frame has a group identifier (GROUPJD) field of receive vector (RXVECTOR) parameters set to a specific value signalling a MAP frame.

[0054] In some embodiments, the APs of the MAP group are included in a multi-BSS configuration of the first AP.

[0055] In some embodiments, the first AP exchanges frame with other APs to set up the MAP group, wherein the exchanged frames include one or more Public Action frames. Correlatively, the invention also provides a wireless communication device comprising at least one microprocessor configured for carrying out any method as described above.

[0056] 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 method as described above.

[0057] At least parts 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, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein 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.

[0058] Since the present invention can be implemented in software, the present invention can be embodied as computer readable code for provision to a programmable apparatus on any suitable carrier medium. A tangible carrier medium may comprise a storage medium such as a hard disk drive, a magnetic tape device or a solid state memory device and the like. A transient carrier medium may include a signal such as an electrical signal, an electronic signal, an optical signal, an acoustic signal, a magnetic signal or an electromagnetic signal, e.g., a microwave or RF signal.

[0059] BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Embodiments of the invention will now be described, by way of example only, and with reference to the following drawings in which:

[0061] Figure 1 illustrates an exemplary network environment in which embodiments of the present disclosure can be implemented;

[0062] Figure 2 illustrates an exemplary Multi-AP coordination in the MAP system of Figure 1 , according to embodiments;

[0063] Figure 3 illustrates, using an exemplary timeline, a so-called non-primary channel access (NPCA) mechanism applied by a BSS detecting OBSS interference;

[0064] Figure 4 illustrates, using a flowchart, general steps of a communication method for frame classification in a wireless communication system, according to embodiments;

[0065] Figure 5 illustrates, using a flowchart, a communication method for frame classification in a wireless communication system, according to some embodiments;

[0066] Figure 6 illustrates, using a flowchart, a communication method for frame classification in a wireless communication system according to other embodiments;

[0067] Figure 7 illustrates, using a flowchart, general steps of a communication method at an AP to control OBSS-driven operations at its associated STAs, according to embodiments; Figure 8 illustrates, using a flowchart, general steps of a corresponding communication method at the stations associated to the AP, according to embodiments;

[0068] Figures 9a and 9b illustrate, using flowcharts, communication methods at an initiating AP and an initiated AP respectively to disable an OBSS-driven mechanism at their associated stations when the initiating AP sets up a MAP agreement with the initiated AP, according to embodiments;

[0069] Figures 10a and 10b illustrate, using flowcharts, communication methods at the initiating AP and an initiated AP respectively to enable an OBSS-driven mechanism at their associated stations when a current MAP agreement is torn down, according to embodiments;

[0070] Figures 11a and 11 b illustrate, using flowcharts, communication methods at an initiating AP and an initiated AP respectively to provide a list of APs to their associated stations to control an OBSS-driven mechanism when the initiating AP sets up a MAP agreement with the initiated AP, according to embodiments;

[0071] Figures 12a and 12b illustrate, using flowcharts, communication methods at the initiating AP and an initiated AP respectively to provide an updated list of APs to their associated stations to control an OBSS-driven mechanism when a current MAP agreement is torn down, according to embodiments;

[0072] Figure 13 illustrates a MAP coordination in a MAP system when implementing the frame classification of Figures 4 to 6 or the controlling method of Figures 7 to 12, according to embodiments;

[0073] Figure 14a shows a schematic representation a communication device in accordance with embodiments of the present invention; and

[0074] Figure 14b shows a schematic representation of a wireless communication device in accordance with embodiments of the present invention.

[0075] DETAILLED DESCRIPTION OF EMBODIMENTS

[0076] When a Multi-AP coordination is setup, the APs involved in the MAP group send a controlling frame to their associated STAs to disable a NPCA mechanism or to provide them with a list of non-OBSS APs. As a consequence, the STAs remain available on their primary channel during a MAP coordination period, although some received MAP frames come from APs different from their own BSS. The STAs can participate to intra-BSS communications when their BSS is offered a transmission opportunity during the MAP cooperation. Furthermore, a frame classification allowing the stations to discriminate between intra-BSS frames, MAP frames and inter-BSS frames allow them not to automatically set their basic NAV in case of MAP coordination, but set their basic NAV for the specific serving periods not allocated to their BSS during the MAP cooperation.

[0077] The techniques described herein may be used for various broadband wireless communication systems, including communication systems that are based on an orthogonal multiplexing scheme. Examples of such communication systems include Spatial Division Multiple Access (SDMA) system, Time Division Multiple Access (TDMA) system, Orthogonal Frequency Division Multiple Access (OFDMA) system, and Single-Carrier Frequency Division Multiple Access (SC-FDMA) system. An SDMA system may utilize sufficiently different directions to simultaneously transmit data belonging to multiple user terminals, i.e., wireless devices or stations. A TDMA system may 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 different user terminal. An OFDMA system utilizes orthogonal frequency division multiplexing (OFDM), which is a modulation technique that partitions the overall system bandwidth into multiple orthogonal sub-carriers or resource units. These sub-carriers may also be called tones, bins, etc. With OFDM, each sub-carrier may be independently modulated with data. An SC-FDMA system may utilize interleaved FDMA (IFDMA) to transmit on sub-carriers that are distributed across the system bandwidth, localized FDMA (LFDMA) to transmit on a block of adjacent sub-carriers, or enhanced FDMA (EFDMA) to transmit on multiple blocks of adjacent sub-carriers.

[0078] The teachings herein may be incorporated into (e.g., implemented within or performed by) a variety of apparatuses (e.g., stations). In some aspects, a wireless device or station implemented in accordance with the teachings herein may comprise an access point (so- called AP) or not (so-called non-AP STA (station)). STA includes both AP and non-AP STA.

[0079] An AP may comprise, be implemented as, or known as a Node B, Radio Network Controller (“RNC”), evolved Node B (eNB), 5G Next generation base station (gNB), Base Station Controller (“BSC”), Base Transceiver Station (“BTS”), Base Station (“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, Basic Service Set (“BSS”), Extended Service Set (“ESS”), Radio Base Station (“RBS”), or some other terminology.

[0080] A non-AP station may comprise, be implemented as, or known as a subscriber station, a subscriber unit, a mobile station (MS), a remote station, a remote terminal, a user terminal (UT), a user agent, a user device, user equipment (UE), a user station, or some other terminology. In some implementations, a non-AP STA may comprise a cellular telephone, a cordless telephone, a Session Initiation Protocol (“SIP”) phone, a wireless local loop (“WLL”) station, a personal digital assistant (“PDA”), a handheld device having wireless connection capability, or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone or smart phone), a computer (e.g., a laptop), a tablet, a portable communication device, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music or video device, or a satellite radio), a global positioning system (GPS) device, or any other suitable device that is configured to communicate via a wireless or wired medium. In some aspects, the non-AP station may be a wireless node. Such wireless node may provide, for example, 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. An AP manages a set of STAs (registered to it or associated with it) that together organize their accesses to the wireless medium for communication purposes. The STAs (including the AP to which they register) form a service set, here below referred to as basic service set, BSS (although other terminology can be used). A same physical STA acting as an access point may manage two or more BSSs (and thus corresponding WLANs): each BSS is thus uniquely identified by a specific basic service set identification, BSSID and managed by a separate virtual AP implemented in the physical AP. Each STA is identified within a BSS thanks to an identifier, AID, assigned to it by the AP upon registration.

[0081] The 802.11 family of standards define various media access control (MAC) mechanisms to drive access to the wireless medium.

[0082] For example, each BSS defines a main elementary channel of the wireless medium (known as a primary channel, usually a 20 MHz channel or a multiple of 20 MHz channel) on which the stations (including the AP) perform EDCA (or the like) contention using generally legacy EDCA parameters (defined in an EDCA Parameter Set provided by the AP). To increase bandwidth for the forthcoming transmission, the stations can simultaneously contend for additional 20 MHz channels, known as secondary channels. The communication or “operating” channel thus granted for transmission comprises the primary channel and optionally secondary channels.

[0083] According to the 802.11 standard family, the primary channel is the common channel of operation for all stations that are members of the BSS. Usually, in a 20 MHz, 40 MHz, 80 MHz, 160 MHz, 80+80 MHz, 320 MHz BSS, the primary channel is a primary 20 MHz channel. Correspondingly, a non-primary channel is any 20 MHz channel other than the primary 20 MHz channel. A secondary channel is a channel associated with a primary channel used to create an operating channel wider than the primary channel alone. In a 40 MHz, 80 MHz, 160 MHz, 80+80 MHz or 320 MHz BSS, each secondary channel is a secondary 20 MHz channel.

[0084] However, the notions of primary and secondary channels have been extended to channels having more than 20 MHz width. For example, the primary 40 MHz (resp. 80 MHz, 160 MHz) channel is the 40 MHz channel (resp. 80 MHz, 160 MHz) in a 80 MHz, 160 MHz, 80+80 MHz or 320 MHz BSS, formed by the primary channel (20 MHz) and one or more adjacent and aggregated secondary channels (20 MHz each), that is used to transmit 40 MHz (resp. 80 MHz, 160 MHz) physical layer (PHY) protocol data units (PPDUs). Similarly, a secondary X MHz channel (X = 20, 40, 80 or 160) is defined in a 2X (or more) MHz BSS as the X MHz channel adjacent to the primary X MHz channel that together form a primary 2X MHz channel (or the entire 2X MHz operating channel).

[0085] The primary channel is used for signalling and backwards compatibility while the secondary channels are only used to extend throughput when sending data at full speed.

[0086] This channel access based on the primary channel is known as the Primary Channel

[0087] Access or “PCA”. Efficient medium usage within one operating channel having an operation bandwidth (up to 320MHz in the latest 802.11 be D6.0 standard; however may be wider in future amendments) has evolved along the evolution of the IEEE 802.1 1 standards.

[0088] For example, dynamic bandwidth signalling feature was introduced in the IEEE 802.11 ac amendment, preamble puncturing feature was introduced in the IEEE 802.11 ax -2021 standard approved on February 9, 2021 and further evolved in the IEEE 802.11 be amendments.

[0089] For example, in order to address the issue of increasing bandwidth and decreasing latency requirements that are demanded for wireless communications systems in high-density environments, multi-user (MU) schemes have been developed to allow a single access point (AP) managing a Basic Service Set (BSS) to schedule MU transmissions, i.e., multiple simultaneous transmissions to non-AP stations (so-called MU Downlink or DL transmissions) or from non-AP stations (so-called MU Uplink or UL transmissions) triggered by the AP using a Trigger frame. The Trigger Frame allocates resource units to the non-AP stations of the same BSS, using Association I Dentifiers (Al Ds) assigned to them upon registration to the AP and / or using reserved AIDs designating a group of non-AP stations. The TF also defines the start of the MU UL transmission by the non-AP stations as well as the length thereof. After a non-AP station makes an MU UL transmission, it performs EDCA contention on the medium using temporarily a different (from the legacy ones) set of EDCA parameters, known as MU EDCA parameters (defined in a Multi-User (MU) EDCA Parameter Set provided by the AP).

[0090] The current discussions in the task group 802.11 be, as illustrated by draft IEEE P802.11 be / D6.0, introduce the Multi-Link Operation (MLO) when it comes to MAC layer operation. The MLO allows multi-link devices to establish or setup multiple links and operate them simultaneously. A Multi-Link Device (MLD) is a logical entity and has more than one affiliated STA (STA) and has a single MAC service access point (SAP) to logical link control (LLC), which includes one MAC data service. Multiple affiliated non-AP STAs of a non-AP MLD can then setup communication links with multiple affiliated APs of an AP MLD, hence forming a multi-link channel. A communication link or “link” thus corresponds to a given channel (e.g., 20 MHz, 40 MHz, and so on) in a given frequency band (e.g., 2.4 GHz, 5 GHz, 6 GHz) between an AP affiliated with the AP MLD and a non-AP STA affiliated with the non-AP MLD.

[0091] The description below mostly concentrates on a single link for ease of explanation. However, similar considerations can be made with respect to each link forming a multiple link set for MLD devices. Therefore, the term STA or “station” may refer to one affiliated STA of a non- AP MLD (non-AP STAs of a non-AP MLD), and AP may refer to one affiliated AP of an AP MLD.

[0092] Figure 1 illustrates an exemplary network environment in which embodiments of the present disclosure can be implemented.

[0093] The illustrated wireless network environment comprises a Multi-AP (MAP) system 100 formed by a group of neighbouring wireless networks that operate over a common communication channel or wireless medium. The common communication channel may correspond to a part (e.g., 20 MHz) or all of their operating channel (e.g., 20 MHz, 40 MHz, 80 MHz, 160 MHz or 320 MHz).

[0094] A first wireless network (or Basic Service Set) BSS1 comprises an access point (AP) 110 and three non-AP stations (STAs) 111 , 1 12 and 113 associated with the AP 110 (i.e., registered to it). A second wireless network BSS2 comprises an AP 120 and three associated non-AP STAs 121 , 122 and 123. A third wireless network BSS2 comprises 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 any of the non-AP stations. Of course, another number of wireless networks and any number of non-AP stations per wireless network can be contemplated. In the present disclosure, APs 110, 120 and 130 are also referred to, respectively, as AP1 , AP2 and AP3. A device may act as an AP of one wireless network and at the same time may belong to another wireless network as an associated STA.

[0095] All or part of the APs may be affiliated APs to the same AP MLD. They also can be separate devices. Any AP broadcasts management frames, such as beacon frames, to share parameters to be used for the functioning of its BSS.

[0096] The stations (AP and non-AP) of each BSS exchange data frames over the communication channel 100, under the management of their AP, using the primary channel of the BSS and optional secondary channels aggregated to the primary channel.

[0097] In the context of the invention, the APs can also communicate one with each other, either using the communication channel of their BSS that is common to the other BSSs or using separate communication links (such as a separate wireless network or channel, an Ethernet backhaul connecting all the APs, direct links, and so on).

[0098] Each non-AP STA 1x1-1x3 registers to the AP 1x0 of one wireless network BSSx during an association procedure. During the association procedure over the primary channel, the AP assigns a specific Association I Dentifier (AID) to the requesting station. For example, the AID is a 16-bit value uniquely identifying the station.

[0099] The stations (including the AP) compete one against another over their primary channel using EDCA (Enhanced Distributed Channel Access) contention to access the communication channel in order to be granted a transmission opportunity (TXOP) over an operating channel made of the primary channel and a secondary channel to increase bandwidth.

[0100] The TXOP may then be used to transmit (single-user, SU) data frames or to implement multi-user (MU) transmissions.

[0101] In the MU scheme, a single station, usually the AP of the wireless network BSSx, is allowed to schedule a MU transmission, i.e., multiple simultaneous transmissions to or from its associated stations. One implementation of such a MU scheme has been for example adopted in IEEE 802.11 ax amendment standard, known as the Multi-User Uplink and Downlink OFDMA (MU UL and DL OFDMA) procedures. In the MU scheme, resources, known as resource units, are defined over the 20 MHz channel or channels used, as subparts of a 20 MHz channel, as a 20 MHz channel or as a multiple of 20 MHz channels. A refined MU scheme is the Triggered TXOP Sharing (TXS) procedure which is a TDMA-like procedure. The Triggered TXS procedure allows an AP to allocate a portion of an obtained TXOP to one of its associated non-AP STA for the latter to transmit its own data, not necessarily to the AP itself (as Uplink data). This time sharing is triggered based on the so-called MU-RTS Trigger frame enhanced with a new Triggered TXOP Sharing Mode subfield (trigger frame now called MU-RTS TXS Trigger frame). This subfield informs whether the MU-RTS Trigger frame is used as before without TXOP sharing (Triggered TXOP Sharing Mode is set to 0) or with TXOP sharing (Triggered TXOP Sharing Mode is set to 1 or 2). In that latter, the TXOP Sharing is either limited to Uplink Traffic when the Triggered TXOP Sharing Mode is set to 1 or dedicated to Uplink and / or direct link traffic when the Triggered TXOP Sharing Mode is set to 2. With the Triggered TXS procedure, an AP is now able to allocate frequency resource units (e.g., Basic Trigger Frame) or temporal resource units to its associated non-AP stations.

[0102] More generally, the resources may include space, frequency and time resources and may be obtained according to different multiplexing schemes. Examples of those schemes include Spatial Division Multiple Access (SDMA) system, Time Division Multiple Access (TDMA) system, Orthogonal Frequency Division Multiple Access (OFDMA) system, and Single-Carrier Frequency Division Multiple Access (SC-FDMA) system.

[0103] In the IEEE 802.1 1 wireless local area networking standards, the MAP system 100 may correspond to an extended service set (ESS) and each of the wireless networks to a basic service set (BSS).

[0104] Although the description of embodiments of the invention is given in the context of IEEE 802.11 , the embodiments are not limited thereto and they may apply to other types of wireless networks and protocols.

[0105] The MAP technology allows some collaboration between neighbouring APs in order to have a more efficient utilization of time, frequency and spatial resources available. In particular, two or more neighbouring APs can share transmission resources (such as 20MHz or more resource units).

[0106] Figure 2 illustrates an exemplary Multi-AP coordination in the MAP system 100 of Figure 1.

[0107] In BSSs prior to the 802.1 1 ax-2021 standard, a station classifies a received frame that has a receiving address (RA) not set to an address of the station (in other words, not addressed to the station) as an inter-BSS frame. Basically, responsive to classifying the received frame as an inter-BSS frame (i.e., OBSS frame), the station sets a basic NAV with duration information indicated by the received frame, usually the Duration field of the PPDU or the TXOP_DURATION of the RX_VECTOR parameters which is provided to the MAC layer by the PHY layer upon reception of the frame. The basic NAV is set to prevent the station from competing for medium access for the duration set into the NAV. Indeed, the medium is considered as busy as long as the basic NAV counter is non-zero. Generally, the station updates its basic NAV with each new received frame that is not addressed to it (RA field value is not equal to the MAC address of the station) and whose duration is greater than the current basic NAV value.

[0108] In the 802.1 l ax-compliant BSSs, the trigger frames have their RA field set to broadcast so that the stations associated with the transmitted AP are likely to consider those trigger frames as OBSS frames, hence to set their basic NAV which is prejudicial to MU transmissions.

[0109] The 802.11 ax-compliant stations (High-Efficiency / HE stations) have been enhanced to perform frame classification of any received frame as an intra-BSS frame or as an inter-BSS frame, wherein an intra-BSS frame is a frame sent by another station of the same BSS or BSSs in the same multiple BSSID set or wildcard. Next, responsive to classifying the received frame as an intra-BSS frame, the station sets an intra-BSS NAV (different from the basic NAV) with duration information indicated by the received frame. Therefore, the inter-BSS frames in the meaning of 802.11 ax are those issued by another BSS (OBSS) to which the receiving station is not associated.

[0110] The intra-BSS NAV is therefore controlled according to the rules defined for the intra- BSS frame while the basic NAV is controlled according to the rules defined for the inter-BSS frames or frames which are not classified.

[0111] As a result, since the 802.11 ax-2021 standard, upon reception of a Trigger frame allocating an RU to a station, the station does not consider the intra-BSS NAV in determining whether to respond to the Trigger frame sent by the AP with which the station is associated. However, the station still considers the basic NAV in determining whether to respond to a Trigger frame sent by the AP with which the station is associated.

[0112] Details on the Intra-BSS and Inter-BSS classification are provided in section 26.2.2 of the 802.11 REVme / D6.0 standard of June 2024 (similar to 802.11 ax -2021 standard with respect to these details).

[0113] Some rules are based on the BSS Color of the received frame to classify the frame. When the BSS Color feature is not disabled and the BSS_COLOR from RXVECTOR parameters is not equal to 0 and is not the BSS Color of the BSS of which the station is a member (in other words, the BSS Color of the received frame corresponds to an AP to which the station is not associated), the received frame is classified as an inter-BSS frame. Otherwise, the received frame is classified as an intra-BSS frame.

[0114] Other rules dedicated to VHT frames are based on the PARTI AL_AID of the RXVECTOR parameters (i.e., a subpart of the AID obtained by the station during the association procedure with the AP) to classify the frame. When the PARTI AL_AID is not equal to bits 39:47 of the BSSID of the BSS to which the station is associated and the GROUPJD of the RXVECTOR parameters is 0, the received frame is classified as an inter-BSS frame. Otherwise (PARTIAL_AID matches BSSID[39:47]), the frame is classified as an intra-BSS frame. Other rules are based on the TA and RA fields or at least on the RA (when control frame has no TA like for instance a CTS) to classify the received frame. When the received frame does not have a BSSID field but has both an RA field and TA field, neither value of which is equal to the BSSID of the BSS to which the station is associated (or any of the other BSSs in the same multiple BSSID set or co-hosted BSSID set to which its BSS belongs), the received frame is classified as an inter-BSS frame. Otherwise (the received frame carries a BSSID or a TA or a RA field value equal to the BSSID of a BSS to which the station is associated - or the like), the frame is classified as an intra-BSS frame.

[0115] Back to Figure 2, the exemplary MAP coordination starts with AP2 sending a MAP (coordination) request 260 to its surrounding APs. The MAP request 260 can be broadcast to the APs in the coverage of AP2 or multi-cast to AP1 and AP3 previously discovered by AP2 for example.

[0116] The MAP request 260 may include the configuration of the MAP coordination that AP2 intends to setup, for example all or part of the following: the type of request (Setup request, teardown request), the duration of the MAP agreement, the operating channel / band, the coordination’s type (C-TDMA, C-OFDMA, C-TWT...), the MAP group ID which identifies the group of cooperating APs, the BSS Color of the MAP group, the set of discovered APs - hence forming the MAP group, the initiating AP’s BSSID, the initiating AP’s BSS Color, the AP ID which could be used as an identifier of the initiating AP in the MAP coordination, the primary channel, the secondary channel, for example for non-primary channel access (NPCA) as described below.

[0117] Next, when surrounding APs receive the MAP request 260, they can decide whether they want to participate in the MAP coordination proposed by the initiating AP (AP2 in the Figure) or not. The surrounding APs, also referred to as “initiated APs” (AP1 and AP3 in the scenario) send a MAP (coordination) response 261 to the initiating AP to accept or reject the MAP coordination. The absence of response is considered as a rejection of the MAP coordination.

[0118] The MAP response 261 may include the information of the initiated AP, for example all or part of the following: the status of the response (ACCEPT or REJECT) the initiated AP’s BSSID, the initiated AP’s ID which could be used as an identifier of the initiated AP in the MAP coordination, the initiated AP’s BSS Color, the primary channel, the secondary channel, for example for NPCA.

[0119] The initiated APs may preferably select their primary channel identical to the one of the initiating AP (indicated in the MAP request 260) to be able to receive the Beacon frames from the initiating AP and the Beacon frame from the other APs of the MAP group which are in coverage of each other. The initiating and initiated APs may preferably select their secondary channel out of the operating band used for the MAP coordination so as to perform any OBSS-driven operations (such as the NPCA described below) onto channels that do not interfere with the MAP operations.

[0120] Upon reception of the MAP response 261 , the initiating AP (AP2 in the scenario) may consider that a MAP coordination agreement is settled between the initiating AP and the initiated APs for which the initiating AP received an acceptance. The initiating AP can then determine the set of AP(s) forming the MAP Coordination Group or “MAP group”, based on the MAP responses and / or the absence of response from the surrounding AP(s).

[0121] The initiating AP may send a subsequent frame - such as a MAP Confirmation frame 262 - to the set of AP(s) having accepted the MAP coordination setup to inform them of the identity of the set of AP(s) belonging to the MAP group. This allows that all APs of the MAP group share the same view. This frame 262 may include one element per AP of the set of AP(s), each element including the information related to the AP, such as all or part of the following:

[0122] - the AP BSSID, the AP ID which could be used as an identifier of the initiating AP in the MAP coordination, the AP BSS Color, the primary channel, the secondary channel, for example for NPCA.

[0123] If the MAP agreement is limited to only two APs, the MAP Confirmation frame 262 could be skipped. An AP may setup several one-to-one MAP agreements at the same time and then share the medium with the APs of the different MAP agreements in the same TXOP.

[0124] After the MAP coordination agreement has been made, each station competes with each other to access the medium.

[0125] In the scenario, AP2 does not detect any communication activity within its range. As a consequence, AP2 performs a backoff countdown after CCA sensing period 201 and initiates a transmission when it gains access to the medium (backoff counter to 0). AP2 becomes the TXOP owner or TXOP holder of TXOP 290.

[0126] AP2 can then send a MAP schedule frame 200 to the set of APs (MAP Group) having formerly setup the MAP coordination agreement (AP1 and AP3) to initiate TXOP sharing with the APs of the MAP group. AP2 is said to be the “sharing AP” while AP1 and AP3 are said to be the “shared APs”. It can be noted that the sharing AP may be any initiated AP (involved in the MAP group) and not only the initiating AP.

[0127] MAP schedule frame 200 may be a trigger frame derived from a MU-RTS Trigger frame or MU-RTS TXS Trigger frame, wherein one or more User Info fields allocate resource units of TXOP 290 to one or more shared APs to whom the sharing AP intends to share time or frequency (including itself). More generally, frame 200 informs which APs will be served during the current TXOP, optionally with information on the timing at which each shared AP will be served.

[0128] MAP schedule frame 200 is identified as a MAP using any signalling information.

[0129] As examples: the Trigger Type subfield of the Common Info field (present in a trigger frame - TF) may be set to a MAP type, e.g., through any of the reserved values 9-15. Note that any of the following fields can optionally be used in combination with the Trigger Type subfield to define a subtype of the MAP-type frame (e.g., to distinguish between e.g., a MAP Basic TF, a MAP BSRP TF, a MAP NFRP TF, a MAP MU-RTS TF, a MAP Ranging TF, and so on), should the subtypes not been defined through different values of the Trigger Type subfield: one or more of bits B20, B21 , B56-B62 of the Common Info field, or a Trigger Dependent Common Info field within the Common Info field, or a Trigger Type Extension field after a Trigger Dependent Common Info field in the Common Info field; a new MAP bit (or field) may be defined in the Common Info field, e.g. at bit 63, that can be set to a MAP type (and more generally to different values for different MAP subtypes in case it is a multi-bit field); the Triggered TXOP Sharing Mode subfield of the Common Info field (present in a trigger frame) may be set to a MAP type, e.g., through any reserved value such as value 3; a Special User Info field may be added that includes a MAP bit / field set to a MAP type. The Special User Info field may further include a Trigger Type Extension field defining a subtype of the MAP-type frame; the presence of an AID field (in any User Info field in the trigger frame) set to an AID defined during setting a MAP agreement and dedicated to a BSS (or AP) different from the BSS sending the frame (here different from BSS2); both RA and TA fields are set to MAC addresses of two different APs (hence TA and RA are different while being AP’s MAC addresses);

[0130] DA and / or SA fields are set to the MAC addresses of AP(s) of the MAP group; BSSID field is set to a value dedicated to identify the MAP group; the Public Action field value of a Public Action frame may be set to a MAP type, e.g. through any reserved value such as 54; a field in a new element (compared to the 802.1 1 REVme / D6.0 standard) of the 20 / 40 BSS Coexistence Management frame (i.e., a Public Action frame with Public Action field value set to 0) may be set to a MAP type. Furthermore, the new element may be dedicated to MAP information.

[0131] The use of a Public Action frame may be beneficial. Indeed, the Public Action Frame is defined to allow inter-BSS and AP-to-unassociated-STA communications, intra-BSS communication and GAS as provided in section 9.6.7 of the 802.11 REVme / D6.0 standard. Such a Public Action frame may be used for frames 260, 261 and 262.

[0132] For instance, the MAP Request frame 260 may be identified by Public Action field value set to 54 (or any other reserved value of the Table 9-471 - Public Action field values), the MAP Response frame 261 may be identified by Public Action field value set to 55 and the MAP Confirmation frame 262 may be identified by Public Action field value set to 56.

[0133] In variants still based on Public Action frames, these frames 260, 261 , 262 may reuse the 20 / 40 BSS Coexistence Management frame (Public Action frame with Public Action field value set to 0) with one or more new element(s) dedicated to MAP in which a category field may indicate whether the frame is a MAP Request or MAP Response or MAP Confirmation frame. More generally, a type field in the new element may indicate whether the frame is a MAP frame or not.

[0134] Upon reception to frame 200, addressed AP1 and AP3 respond with a MAP acknowledgement frame 210 back to AP2. MAP acknowledgement frame 210 may be a CTS frame. In embodiments, MAP acknowledgement frame 210 is sent by each addressed (shared) APs in a non-HT duplicate through the whole band covered by MAP schedule frame 200 or each AP may send its MAP acknowledgement frame 210 in the sub-band (resource unit) allocated to it.

[0135] In the proposed scenario, the TXOP holder (AP2) is first to use the medium for its own BSS during period 220. The maximum duration of this period may be included in the MAP schedule frame. During this period, AP2 uses the medium and performs triggered communications (DL or UL or P2P).

[0136] At the end of period 220, the TXOP holder (AP2) operates as a sharing AP by sending a TXOP coordination frame 230 to AP1 and AP3. This frame is used to give the medium from the sharing AP to one shared AP (e.g. in case of TDMA-like sharing) or more shared APs (in case of frequency sharing as well). Upon reception of TXOP coordination frame 230, all APs of the MAP group, or all shared APs or all APs listed in frame 230 (e.g., addressed AP1 and AP3) respond with a MAP acknowledgement frame 240 back to AP2. The more responding AP, the enlarged the protection area.

[0137] Like MAP schedule frame 200, TXOP coordination frame 230 may be a trigger frame derived from a MU-RTS Trigger frame and more especially from a MU-RTS TXS trigger frame that allows the sharing of the medium in time in a TDMA manner.

[0138] After acknowledgment 240 giving the medium to AP1 for a maximum duration indicated in frame 230, AP1 uses the medium for its own BSS during period 221 . After period 221 , TXOP coordination frame 250 and corresponding MAP acknowledgement frame 260 can give the medium to AP3 for a maximum duration indicated in frame 250 in which AP3 uses the medium for its own BSS during period 222.

[0139] As depicted in the Figure, all stations of BSS1 and BSS3 that are in AP2’s coverage receive MAP schedule frame 200 that is from another BSS. Therefore, it is classified as inter-BSS frame because the frame is considered as OBSS interference. The stations then set their basic NAV upon reception of the frame. Consequently, they are not authorized to transmit data to their AP using their primary channel, during TXOP 290.

[0140] In addition, the stations may then adopt a specific OBSS behaviour during TXOP 290, by using a mechanism that is triggered by the detected OBSS interference. Such mechanism and any action or operation taken by a station as a result of the detected OBSS interference is referred below to as OBSS-driven mechanism or OBSS-driven action or OBSS-driven operation.

[0141] One known OBSS behaviour is for any station experiencing OBSS interference to enter a Power Save (PS) mode, in order to save energy. The PS mode is therefore a first exemplary OBSS-driven mechanism.

[0142] Another OBSS behaviour allows the station experiencing OBSS interference to switch to another channel to continue intra-BSS communications. As introduced by the 802.11 bn standard (D6.0), the Non-Primary Channel Access (NPCA) or Secondary Channel Access (SCA) mechanism allows the station experiencing OBSS interference to move from its primary channel to a predefined secondary channel (known as “anchor channel”) for channel access. Once on the secondary channel for NPCA, the station can perform intra-BSS communications during the duration of TXOP 290 of the OBSS interference (“OBSS TXOP”). The station goes back to its primary channel no later than the end of the OBSS TXOP 290. The NPCA or any NPCA-like mechanism involving a switch of channel is a second exemplary OBSS-driven mechanism.

[0143] Figure 3 illustrates, using an exemplary timeline, the non-primary channel access mechanism, applied by BSS1 (AP1 and STA1 1) detecting OBSS interference from BSS2.

[0144] Today's Wi-Fi, including versions up to 1 1 be (Wi-Fi 7), generally does not allow for the use of the secondary channel while the primary channel is busy. In standard 802.11 practice, transmissions typically utilize 20 / 40 / 80 / 160 / 320 MHz channels, with one dedicated 20 MHz channel functioning as the primary channel. Regardless of whether secondary channels are idle or busy, these channels remain inaccessible if the primary channel is occupied.

[0145] In the example, the BSS operating band, which may be announced by AP1 1 10 includes two subchannels, which are 80 MHz channel 1 and 40 MHz channel 2, and where each subchannel includes multiple 20 MHz channels and has one backoff 20 MHz channel, i.e., one channel to perform medium / channel access.

[0146] The first 80MHz channel 1 is composed of a set S1 of four 20MHz channels, including primary channel P1. Primary channel P1 is the primary channel on which the primary channel access or PCA scheme is performed. The second 40MHz channel 2 is composed of a set S2 of two 20MHz channels, including anchor channel P2. The anchor channel P2 is the secondary channel on which the secondary channel access SCA or NPCA scheme is performed. Set S2 is a subset of set S1 .

[0147] Usually, AP and STAs perform backoff procedure in the primary backoff 20 MHz channel P1 only. By using the NPCA mechanism, a STA can enable one or more backoff procedures in the anchor channel P2.

[0148] On the 80MHz channel 1 , while STA11 and AP1 perform backoff procedures, AP2 (which is an OBSS from BSS1 perspective) starts an OBSS TXOP 290. As the primary 20 MHz channel becomes busy due to the OBSS transmission, AP1 and STA1 1 switch from the primary channel P1 to the anchor channel P2. Channel switch operation 321 a / b may take different time depending on the STAs’ ability (including hardware configuration).

[0149] NPCA operations 322a / 322b start after both AP1 and STA11 have completely switched to the anchor channel P2. On the anchor channel, the STAs (STA11 and / or AP1) perform NPCA operation (322a / 322b) as follows. The STAs perform CCA for PPDU detection and decrement their backoff counter(s). A STA may transmit an initial control frame (ICF) after one of its backoff counters becomes 0 to confirm that the STA has successfully switched to the anchor channel. The initial control frame may be an RTS frame or MU-RTS frame or any other control frame. An addressee STA may respond with an initial control response (ICR) frame after it received the ICF. This is to confirm the addressee STA has also successfully switched to the anchor channel. The ICR frame may be a CTS frame or any other control frame.

[0150] The STA transmits a data frame after receiving the ICR frame, e.g. a mere ACK frame. The other STA may respond with an acknowledgement (ACK) frame after receiving the data frame. The frame exchanges in the secondary 40MHz channel S2 are done within OBSS TXOP 290 that uses the primary channel.

[0151] No later than the end of OBSS TXOP 290, the STAs switch back to their primary channel P1 and operating band S1. The switching back is referenced 323a / 323b in the Figure. The STAs can initiate new transmissions through the complete operating band S1 in a conventional manner.

[0152] The NPCA mechanism is not fully efficient in hidden nodes situations. Indeed, one of the challenges for NPCA is the detection of an OBSS frame or activity on the primary channel. As all the station in a BSS are not located at the exact same position, the OBSS detection can differ from station to station. As a result, some stations may move onto the secondary channel based on their local OBSS interference detection while other stations of the same BSS may stay on the primary channel as they are unable to detect the OBSS interference.

[0153] A refinement of the NPCA mechanism allows the AP to share a list of its OBSS APs to its associated stations. The list references all neighbouring APs within the detection range of the AP. Next, any station of the BSS that detects an OBSS frame on its primary channel is authorized to switch to the anchor channel only if the detected OBSS frame matches the OBSS of one of the inputs of the OBSS AP list provided by the AP. As a result, the stations detecting the OBSS interference activate the NPCA mechanism only if the AP also switches to the anchor channel upon detecting the same trigger. Hence, they can communicate with each other in an efficient way on the set S2 of channels.

[0154] Back to Figure 2, STA11 and STA31 detect OBSS interference, set their basic NAV to defer their access to the medium during the entire TXOP 290, and then may apply an OBSS- driven action such as the PS mode or the NPCA scheme. That means STA11 and STA13 are no longer available for intra-BSS communications during TXOP 290 although the MAP mechanism offers them some transmission opportunities (transmission period 221 for STA1 1 and BSS1 , transmission period 222 for STA31 and BSS3). This situation (illustrated with large crosses in the Figure) is very detrimental to network efficiency.

[0155] It is apparent from this situation that a better classification of frames received by the stations would be helpful for them to adopt and use appropriate behaviours. Also, it is apparent that a better control on the use by the stations of the OBSS-driven mechanisms would be helpful to the AP to keep its associated stations involved in communications in case of OBSS interference, should the interference include MAP coordination. This would improve intra-BSS communication.

[0156] In this context, when a station associated to an AP receives a frame having a receiving address (RA) not set to an address of the station, the station may perform a frame classification of the received frame as an intra-BSS frame or a Multi-AP (MAP) frame or an inter- BSS frame. In particular, a non-intra-BSS frame - i.e. , a frame sent by another station of the first BSS or in the same multiple BSSID set or wildcard - is classified as a MAP frame if the received frame signals medium sharing between APs belonging to a MAP Group to which the AP belongs, or classified as inter-BSS frame otherwise. Therefore, an additional class (MAP frame) is proposed to ease the management of the stations’ behaviours by themselves. In particular, they are now able to discriminate between MAP frames and OBSS frames, hence able to avoid using an OBSS-driven mechanism in case a MAP coordination involving their AP is on-going.

[0157] Figure 4 illustrates, using a flowchart, general steps of a communication method for frame classification in a wireless communication system such as MAP system 100 of Figure 1. The method 400 is implemented at any station of a BSS, preferably - but not necessarily - at a non-AP station.

[0158] The method 400 starts at step 401 by the reception of a frame by the station. As any frame directly addressed to the station (i.e., with a RA field set to the MAC address of the station) is directly processed by the station, the description below concentrates on received frames not directly addressed to the station.

[0159] This step may correspond to the reception of MAP schedule frame 200 (Figure 2) by any station (AP1 , STA1 1 , AP3, STA31).

[0160] Upon reception of the frame, the station determines at step 402 a classification of the received frame amongst the known intra-BSS and inter-BSS categories, as well as the MAP category. Classification rules can be defined.

[0161] For example, some rules may be based on the BSS Color of the received frame to classify the frame. When the BSS Color feature is not disabled and the BSS_COLOR from RXVECTOR parameters is not equal to 0 and is not the BSS Color of a MAP Group or of a BSS of a MAP Group that includes the BSS of which the station is a member (in other words, the BSS Color of the received frame corresponds to a BSS which has no MAP cooperation with the BSS of the station), the received frame is classified as an inter-BSS frame. Otherwise, if the BSS_COLOR from RXVECTOR parameters is not equal to 0 and is the BSS Color of such a MAP Group or of a BSS of such a MAP Group but is not the BSS Color of the BSS of which the station is a member (in other words, the BSS Color of the received frame corresponds to an AP of the MAP group, to which the station is not associated), the received frame is classified as a MAP frame. Otherwise, the received frame is classified as an intra-BSS frame. More generally, a BSS Color dedicated to a MAP Group can be used.

[0162] Other rules (in addition or in variant) dedicated to VHT frames (hence to VHT or later STAs) may be based on the PARTIAL_AID of the RXVECTOR parameters to classify the frame. When the PARTIAL_AID is not equal to bits 39:47 of the BSSID of a MAP Group (e.g. the MAP Group ID shared in the MAP Request frame 260 or the BSSID of the initiating AP or of one of the initiated APs) or of a BSS of a MAP Group that includes the BSS to which the station is associated and the GROUPJD of the RXVECTOR parameters is 0, the received frame is classified as an inter-BSS PPDU. Otherwise, if the PARTIAL_AID is equal to bits 39:47 of the BSSID of such a MAP Group or of a BSS of such a MAP Group but not equal to bits 39:47 of the BSSID of the BSS to which the station is associated and the GROUPJD of the RXVECTOR parameters is 0, the received frame is classified as an MAP frame. Otherwise (PARTIAL_AID matches BSSID[39:47] of the BSSID of the BSS), the frame is classified as an intra-BSS frame. More generally, a BSSID dedicated (or any MAP Group identifier) to a MAP Group can be used.

[0163] Other rules (in addition or in variant) dedicated to VHT frames (hence to VHT or later STAs) may be based on the GROUPJD of the RXVECTOR parameters to classify the frame. The conventional use of the GROUPJD of the RX_VECTOR parameters is the following one: GROUPJD in RX_VECTOR is used for MU UL except value 0 and 63 used for SU PPDU as defined in Table 22-1— TXVECTOR and RXVECTOR parameters in section 22.2.2 TXVECTOR and RXVECTOR parameters of the 802.11 REVme / D6.0 standard). In embodiments, the value of the GROUPJD could be set to a specific value to signal a MAP frame, for instance value 1. Alternatively, a value between 0 and 63 can be reused, for instance when the frame is an UHR PPDU. In variants, a value for the GROUPJD may be negotiated beforehand and then be shared in the MAP Request frame 260 or in an enhanced version of a frame dedicated of the management of a Group ID, such as the Group ID Management frame following the format described in section 9.6.22.3 of the 802.11 REVme / D6.0 standard to perform Group ID management operation (described in section 11.39). More generally, a received frame may be classified as a MAP frame when the received frame has a group identifier (GROUPJD) field of receive vector (RXVECTOR) parameters set to a specific value signalling a MAP frame.

[0164] Other rules (in addition or in variant) may be based on the TA and RA fields or at least on the RA (when control frame has no TA like for instance a CTS) to classify the received frame. When the received frame does not have a BSSID field but has both an RA field and TA field, neither value of which is equal to the BSSID of a MAP Group or of a BSS of a MAP Group that includes the BSS to which the station is associated (or any of the other BSSs in the same multiple BSSID set or co-hosted BSSID set to which its BSS belongs), the received frame is classified as an inter-BSS PPDU. Otherwise, if the received frame does not have a BSSID field but has both an RA field and TA field, a value of which is equal to the BSSID of such a MAP Group or of a BSS of such a MAP Group but neither value of which is equal to the BSSID of the BSS to which the station is associated (or any of the other BSSs in the same multiple BSSID set or co-hosted BSSID set to which its BSS belongs), the received frame is classified as a MAP frame. Otherwise (the received frame carries a BSSID or a TA or a RA field value equal to the BSSID of a BSS to which the station is associated - or the like), the frame is classified as an intra- BSS frame.

[0165] Other rules (in addition or in variant) may be based on the conventional classification between intra-BSS frames and inter-BSS frames (as defined in section 26.2.2 of the 802.11 REVme / D6.0 standard) augmented with a determination of a MAP signalling within the frame. With these rules, a non-intra-BSS frame (i.e., a frame usually classified as an inter-BSS frame) is further examined to determine whether it includes such a MAP signalling (in which case it is classified as a MAP frame) or not (in which case it is classified as an inter-BSS frame).

[0166] The MAP signalling may be assessed by the station based on any signalling information as mentioned above: follows: the Trigger Type subfield of the Common Info field set to a MAP type; a new MAP bit (or field) in the Common Info field set to a MAP type; the Triggered TXOP Sharing Mode subfield of the Common Info field set to a MAP type; a Special User Info field including a MAP bit / field set to a MAP type; the presence of an AID field in any User Info field set to an AID dedicated to a BSS (or AP) different from the BSS sending the frame; both RA and TA fields being set to MAC addresses of two different APs.

[0167] Some above rules may require that the stations, in particular non-AP STAs, have knowledge of some information regarding the MAP group, e.g. BSS Color / BSSID / Group identifier dedicated to the MAP group, or the like. Such information is obtained by the APs participating in the MAP cooperation (thanks to frames 260, 261 or 262). It can be shared by the APs to their associated non-AP STAs through Beacon frames or Probe Response frames or new frames dedicated to that purpose. The frame may include a MAP information element including all required information as mentioned above or include an enhanced version of the Neighbor Report element or Reduced Neighbor Report element as defined in sections 9.4.2.35 and 9.4.2.169 of the 802.11 REVme / D6.0 standard. In embodiments, the information about the MAP group may be gathered in an element corresponding to a new AP in the Neighbor Report or Reduced Neighbor Report elements with an additional information to differentiate from a “normal” AP (e.g., one bit or one field or one flag). The set of APs of the MAP group or the MAP group itself (considering the MAP group owns its BSSID, BSS color) could be included in the Multi-BSS configuration of each AP belonging to the MAP group. In particular embodiments where the MAP frame can be classified as an intra-BSS frame to simplify its handling, in response to the MAP agreement, each AP (initiating and initiated) could include the other APs of the MAP group as new BSSs of the multiple BSSID. In variants, the information about the MAP group may be carried in a Channel Usage element (defined in section 9.4.2.84 of the standard) with a new usage mode targeting MAP usage.

[0168] The first rules above implicitly determine whether or not the BSS of the station is involved in the MAP coordination (e.g., through the presence of an appropriate BSS Color or BSSID for the MAP Group).

[0169] The other rules based on the MAP signalling do not make this distinction when classifying the frame. In this case, once classification 402 has been made, the station refines the classification of the frame to check whether, although the frame is classified as a MAP frame, the station has no chance to be involved in a MAP coordination, in which case the frame should be operated as an inter-BSS frame - hence classified as an inter-BSS frame.

[0170] In particular, the station re-classifies the frame as an inter-BSS frame if its BSS is not involved in the MAP operation either its associated AP / BSS is not in the set of APs / BSSs of the MAP group identified in the frame or its associated AP / BSS is not listed in the set of APs / BSSs which will be served during TXOP 290. In that case, although the frame has been identified as a MAP frame, the behaviour of the station is the same as for an inter-BSS frame.

[0171] In the scenario of Figure 2, AP1 and AP3 classify MAP schedule frame 200 as a MAP frame at step 402, e.g., because both APs are addressed by the frame (for example through a User Info filed) or because the transmitter of the frame is an AP of the set of APs involved in the MAP agreement setting up through the message exchange 260 / 261. Similarly, STA11 and STA31 classify MAP schedule frame 200 as a MAP frame at step 402.

[0172] Next, based on the classification, the station performs, at step 404, actions to organize its channel access. For instance, it performs intra-BSS-driven actions or operations in case of an intra-BSS frame; inter-BSS-driven (or OBSS-driven) actions or operations in case of an inter-BSS frame; MAP-driven actions or operations in case of a MAP frame.

[0173] For example, the station could set its NAVs according to the frame classification.

[0174] In a conventional manner, responsive to classifying the received frame as an inter- BSS frame, the station may set a basic NAV with duration information indicated by the received frame. Furthermore, it may switch to another channel (for instance according to the NPCA mechanism described above) or enter the Power Save mode.

[0175] Also, responsive to classifying the received frame as an intra-BSS frame, the station may set an intra-BSS NAV (different from the basic NAV) with duration information indicated by the received frame, and wait for further communication from its AP (either a trigger frame or a downlink transmission or a control frame).

[0176] In embodiments, responsive to classifying the received frame as a MAP frame, the station sets a MAP NAV (different from the basic and intra-BSS NAV) with duration information indicated by the received frame. This third NAV is dedicated to MAP operations. The station may then wait for further MAP frames or communication from its AP. The MAP classification therefore allows the station to remain active, without performing OBSS-driven actions such as switching to a second channel or entering the PS mode.

[0177] If a frame classified as intra-BSS or MAP is addressed to the station, the latter can answer to it.

[0178] In the scenario of Figure 2, AP1 and AP3 set their MAP NAV and respond to MAP schedule frame 200 with a MAP acknowledgement 210 which is normally forbidden if the basic NAV is not equal to 0. In other words, the AP does not consider the MAP NAV in determining whether to respond to a Trigger Frame (such as MAP schedule frame 200) sent by another AP, or another AP of the set of APs having MAP coordination agreement.

[0179] The MAP NAV can be used as follows: after an acknowledgment solicited by a MAP (Trigger) frame from a sharing AP has been sent - typically an acknowledgment by the AP to which the STA is associated -, the STA ignores the MAP NAV either until the end of the time allocation signalled in the MAP (Trigger) frame or until the allocated time is returned to the TXOP holder, whichever happened earlier.

[0180] In alternative embodiments to the MAP NAV - e.g., because the station does not manage a MAP NAV -, the station may rely on the existing NAVs.

[0181] For example, the station (in particular the AP) receiving a MAP frame may set its basic NAV but does not consider the basic NAV in determining whether to respond to a MAP (Trigger) Frame (such as MAP schedule frame 200) sent by another AP, or another AP of the set of APs having MAP coordination agreement. In other words, responsive to classifying the received frame as a MAP frame, the station, operating as the first AP, sets its basic NAV with duration information indicated by the received frame and ignores the basic NAV to respond to any MAP frame from another AP allocating the medium to the first BSS.

[0182] As far as a non-AP station (STA1 1 or STA31) is concerned, the station may set its intra-BSS NAV with duration information indicated by the received frame and wait for communication from its AP or further MAP frames involving its BSS. Alternatively, it can set its basic NAV while refraining to apply OBSS-driven operations, such as a switch to another channel or an entering into the PS mode. However, in this alternative, the non-AP station may further ignore the basic NAV for the reception of any future MAP frame (or T rigger Frame from their AP) that follows a first MAP frame has been received, until an end of a MAP TXOP defined by the first MAP frame.

[0183] Whatever the embodiments elected, the MAP acknowledgement 210 may be a CTS frame as already mentioned above. The stations that have detected MAP schedule frame 200 are able to classify the CTS frame 210 as a MAP frame, because it is a response to MAP schedule frame 200.

[0184] The stations unaware of MAP schedule frame 200 (because out of the range of the sharing AP - AP2) process CTS frame 210 in a conventional way. The RA of the CTS frame 210 is set to the BSSID (or AP MAC address) of the next serving BSS. If the station receiving the CTS frame 210 is concerned by the next serving period 220 (BSSID in the RA matches the BSSID of its BSS), the station sets its intra-BSS NAV to the duration indicated in the CTS frame (if larger than the current value of the basic NAV). If not concerned by the next serving period 220, the station sets its basic NAV to the duration indicated in the CTS frame.

[0185] However, these stations may belong to a shared BSS (e.g., BSS1 or BSS3) that may be served with a subsequent shared period 221 or 222. In order for these stations to remain available to join the subsequent serving period 221 / 222 for their BSS, the duration indicated in the CTS frame may be set to the sum of the duration of serving period 220 defined by the MAP frame 200 and the duration of a subsequent MAP frame 230 to offer a subsequent serving period 221 , while not exceeding the end of TXOP 290. This also applies for the MAP frames 230 / 250 and corresponding acknowledgment frames 240 / 260.

[0186] For the shared AP to be able to calculate the duration to indicate in the CTS frame 210 / 240 / 260, the duration of the next serving period may be indicated in the MAP frames 200 / 230 / 250.

[0187] This scenario ensures that the non-AP stations detecting the initial MAP Schedule frame 200 directly sets their intra-BSS NAV (or MAP NAV in other embodiments) to the duration of the MAP cooperation (TXOP 290). Those stations remain available along the entire TXOP 290 for transmissions triggered by their respective AP.

[0188] Also, the non-AP stations not detecting the initial MAP Schedule frame 200 sets at each new MAP frame 200 / 230 / 240:

[0189] - their intra-BSS NAV to the duration of the next serving period 220 / 221 / 222 plus next MAP frame upon receiving the responding CTS which signals the next serving period is for their BSS, or

[0190] - their basic NAV to the duration of the next serving period 220 / 221 / 222 plus next

[0191] MAP frame upon receiving the responding CTS which signals the next serving period is not for their BSS.

[0192] Those stations also remain available along the entire TXOP 290 for transmissions triggered by their respective AP, while they can also apply OBSS-driven actions (NPCA, PS mode) when a serving period is not allocated to their BSS because their basic NAV is set for at least the duration of the serving period.

[0193] Figure 5 illustrates, using a flowchart, a communication method for frame classification in a wireless communication system according to some embodiments. Compared to Figure 4, this flowchart provides more details on step 402. The method 500 is implemented at any station of a BSS, preferably - but not necessarily - at a non-AP station. After receiving (401) a frame not addressed to the station, the classification starts with determining (502) whether the received frame is an intra-BSS frame or not. The criteria described above apply. Basically, it is checked whether the received frame signals a BSS Color, BSSID or MAC address related to the BSS to which the station belongs.

[0194] In the affirmative, the TXOP is considered as an intra-BSS one at step 503 and the station performs intra-BSS-driven operations, such as setting or updating its intra-BSS NAV and waits for a communication from its AP (step 510). Indeed, the AP to which the station is associated can send a trigger frame which requests the station to further send uplink data to the AP. In that case, the Trigger Frame includes a resource allocation for the station indicating on which frequency and at which time the station should communicate.

[0195] In the negative, the classification continues with determining (504) whether the received frame is a MAP frame or not. The criteria described above apply (rules based on BSS Color, BSSID or MAC address, or MAP signalling, and so on.).

[0196] In the affirmative of test 504, the TXOP is considered as a MAP one at step 505 and the station performs MAP-driven operations, such as setting or updating its intra-BSS NAV or MAP NAV (depending on the embodiments) and waits for a communication from its AP (step 510).

[0197] In a variant shown by dotted test 506, the station may further check whether the next serving period (i.e., a timeslot) triggered by the received frame is allocated to serve its BSS. In the affirmative, the next serving period is for its BSS and the station goes to step 510. Otherwise, the next serving period is for another BSS and the station goes to step 520 to apply OBSS-driven operations.

[0198] In embodiments, the station checks whether the current time (of the received frame) matches the time allocated to serve its BSS in the resource allocation (such as for example in initial MAP schedule frame 200).

[0199] In other embodiments, the station may wait for a subsequent frame (for example an immediate response to the received frame, such as the MAP acknowledgement 210 / 240 / 260) and determines whether the subsequent frame meets the intra-BSS criteria (e.g., includes TA or RA or BSSID field value of the BSS of which the station is associated, in which case the subsequent frame is classified as an intra-BSS. Otherwise, the subsequent frame is classified as an inter-BSS. The corresponding NAV (basic NAV if step 520 and intra-BSS NAV or MAP NAV of step 510) is set globally for the duration of the next serving period (plus the duration of the next MAP frame).

[0200] In yet other embodiments, the station may rely on the first frame occurring in the concerned serving period (220 / 221 / 222) to determine whether the serving period in an intra-BSS period (e.g., a trigger frame from its AP) or an inter-BSS or OBSS period (a frame from another AP). In that case, the classification is delayed to the reception of that first frame. The reception of the MAP schedule frame 200 could be set as an intra-BSS and test 506 allows the classification of the serving period itself. In the negative of test 504, the TXOP is considered as an inter-BSS (or OBSS) one at step 507 and the station performs OBSS-driven operations, such as switching to another channel, activating NPCA or entering the PS mode (step 520).

[0201] Figure 6 illustrates, using a flowchart, a communication method 600 for frame classification in a wireless communication system according to some embodiments. The same references as in Figure 5 correspond to the same steps.

[0202] The difference occurs when the received frame is classified as a MAP frame (505), in order to consider the case where the serving period is early ended, e.g. truncated by a TXOP return indication. A TXOP return indication may be used by a shared AP to give back the medium to the sharing AP in case the shared AP and its associated stations have no more data to exchange within the service period or for any other reason. In other words, at a shared AP, when the received frame is a MAP frame allocating a serving period to the corresponding shared BSS for a serving duration, the shared AP may send, to the sharing AP having sent the MAP frame, an indication of anticipated end of the service period to give the medium back to the sharing AP before an end of the serving duration.

[0203] Exemplary TXOP return indication includes a CF-end frame, a QoS frame with a CAS Control subfield and a RDG subfield set to 0 in the HT control field defined in section 9.2.4.6 of the standard.

[0204] Thanks to the TXOP return indication, the sharing AP may start to serve another BSS before the expected timing. A risk is that a non-AP station belonging to this other BSS misses the beginning of the next serving period allocated to this other BSS.

[0205] If the serving period truncation is authorized, a TXOP return indication may occur during the serving periods allocated to other BSSs if the other BSSs have no more data to exchange during their allocated serving period. The serving period truncation changes the scheduling initially defined.

[0206] To keep track of this change in the scheduling, when the MAP serving period is not for its own BSS (negative at test 506), the station has to be able to receive any TXOP return indication from the shared AP benefiting from the MAP serving period (or any further MAP frame following a TXOP return indication). That is why the station, when the serving period truncation is authorized (see output ‘yes’ with double-line arrow from test 608), goes to step 510 to e.g., disable the OBSS-driven operations in order to be sure not to miss any MAP serving period dedicated to its BSS. If the MAP serving period is for its own BSS, the process also goes to step 510 as in Figure 5. The authorization may be included in the MAP agreement or in a MAP frame such as the one starting the MAP TXOP 290 (for instance MAP schedule frame 200).

[0207] In some embodiments where the station is capable of operating in one channel while listening another channel, for instance by using the EMLSR (Enhanced Multilink Single-Radio) feature, the station can still apply OBSS-driven operations and still receive the TXOP return indication at the same time. However, the capability to listen the serving period truncation while applying OBSS- driven operations at the same time may not be supported by all stations. The support of this capability may be exchanged by each station with its associated AP through the Capability Information field or the Extended Capabilities field or in a new element ID dedicated to MAP capability or more generally in a frame controlling the MAP. More generally, the stations of a BSS could share their capability to support the serving period truncation with their AP and in case of serving period truncation, the shared AP which will be served in the serving period starting ahead of the expected schedule, can decide to only schedule the stations with this capability. An AP can control the service period truncation for instance according to the ratio of stations in its BSS supporting these dual operations (listening TXOP return indication while applying OBSS-driven operations at the same time).

[0208] Therefore, in those embodiments, when the serving period truncation is authorized (see output ‘yes’ with single-line arrow from test 608), the station tests at step 609 whether it is capable to listen TXOP return indication while applying OBSS-driven operations. In the affirmative, the station goes to step 520 to apply an OBSS-driven operation. Otherwise (in the negative), the station goes to step 510.

[0209] The support of the service period truncation allows to adjust the scheduling on-the- fly according to the actual needs of the BSSs by dynamically reallocating time to other BSSs with more needs. On the other hands, the service period truncation requires the stations to get the TXOP return indication and so either to support dual operations or disable OBSS-driven operation.

[0210] If the service period truncation is not authorized at test 608, the process goes to step 520 as in Figure 5 for a MAP serving period not for its own BSS. It can be noted that if the serving period truncation is not authorized (output ‘no’ at test 608), the shared BSS can ensure that its serving period is ended at the expected time. For example, the shared BSS may use padding to keep the medium busy and avoid the TXOP to be lost.

[0211] The above (Figures 4 to 7) shows that a better classification of frames received by the stations is helpful for them to adopt and use appropriate behaviours (intra-BSS-driven operations or MAP-driven operations or OBSS-driven operations).

[0212] A better control on the use by the stations of the OBSS-driven mechanisms can also be helpful to the AP to keep its associated stations involved in communications in case of OBSS interference. This is now explained.

[0213] Below, it is proposed that the AP of a BSS sends to its associated stations, a frame including a parameter to control a behaviour of the stations in case the station detects Overlapping-BSS (OBSS) interference, i.e., to control their OBSS-driven behaviours.

[0214] Figure 7 illustrates, using a flowchart, general steps of a communication method 700 at an AP to control OBSS features - i.e., OBSS-driven operations - at its associated STAs. To be recalled that the OBSS-driven operations regard any action a station can take or apply upon detecting OBSS interference. Examples already provided above include a switch to another channel, the NPCA feature, an entering into the PS mode

[0215] This method 700 is particularly advantageous when the MAP frame is not considered as a new category of classification by the stations, hence it is still considered as an inter-BSS frame. The method thus proposed to refrain the stations to switch to another channel or to go into PS mode even if they set their basic NAV. Of course, the method can also be applied when the MAP classification of Figures 4-6 is used.

[0216] At step 701 , the AP detects an event to trigger a control of the OBSS-driven operations at the stations.

[0217] A first exemplary triggering event relates to a change in a Multi-AP (MAP) coordination scheme to which the AP belongs. For example, the change may include a setup of a MAP agreement involving the AP or include a partial or full teardown of a MAP agreement involving the AP. In other words, a status of a MAP coordination for the AP is determined.

[0218] The AP may determine whether a MAP coordination is setup and active, or is torn down. For instance, an AP may determine the status of a MAP coordination agreement based on frame exchanges between initiating and initiated APs (e.g., frames 260, 261). The MAP coordination may also be updated (hence changed) within a MAP agreement setup. For example, the MAP could be enabled / disabled for a TXOP for example through an information element included in a Control frame such as a Beacon frame or a Probe Response frame or through the detection of a MAP frame at the beginning of a TXOP or through a dedicated TWT agreement.

[0219] Based on the MAP status determined at step 701 , the AP sends at step 702 a controlling frame to the stations of its BSS for controlling the OBSS-driven operations.

[0220] A second exemplary triggering event relates to OBSS-driven operation needs. As an example, the AP may evaluate whether there is a need for its associated stations to use NPCA (in order to perform communications) or not.

[0221] In particular, the AP may determine the number of other (i.e., OBSS) APs in the vicinity of the AP and / or an amount of data to be exchanged within its BSS, which number and / or amount are compared to respective thresholds. If it or they are lower than the thresholds, there is no need for NPCA, hence it can be disabled. On the other hand, if it or they are higher than the thresholds, there may be a need for the stations to use NPCA, hence it can be enabled.

[0222] To be more precise, the AP may determine that NPCA is not useful when there is no other APs in its vicinity, or when there is no or a low quantity of data (DL and / or UL traffic) to transmit throughout its BSS. In that case, in view to save power usage in the stations, the AP may decide to disable the NPCA feature.

[0223] On the other hand, when the number of OBSSs is high and the primary channel of the AP is regularly busy by the OBSSs, the AP may decide to enable the NPCA feature at its stations.

[0224] The AP may also enable NPCA at its stations when low latency traffic or a lot of traffic is to be transmitted throughout its BSS, in order to maximize the chance to gain the medium. The AP may also determine the NPCA need based on the MAP status as explained above.

[0225] Based on the need determined at step 701 , the AP sends at step 702 a controlling frame to the stations of its BSS for controlling the OBSS-driven operations.

[0226] The controlling frame includes a parameter that controls whether the stations use an OBSS-driven mechanism or not in case they detect OBSS interference. The parameter may define an activation or deactivation (enabling or disabling) of an OBSS-driven mechanism at the stations. It may also define a pausing or a resuming of an OBSS-driven mechanism.

[0227] The controlling frame may be a frame to enable OBSS-driven operations such as the NPCA feature when the AP determines that the MAP coordination is disabled or when the AP determines that low latency traffic or a great amount of traffic is to be transmitted.

[0228] The controlling frame may be a frame to disable OBSS-driven operations such as the NPCA feature when the AP determines that the MAP coordination is enabled or when the AP determines that no low latency traffic or few traffic is to be transmitted.

[0229] The controlling frame may be a Control frame in the meaning of the 802.11 REVme / D6.0 standard. In embodiments, it is an Operating Mode (OM) Notification frame dedicated to NPCA or to any OBSS-driven feature / mechanism, that means the OM Notification frame may include a NPCA (or more generally MAP) Control field setting the activation / deactivation state of the NPCA feature (or any OBSS-driven feature).

[0230] In variants, the controlling frame may be a frame including a list of APs, either the OBSS APs for which the NPCA feature (or any OBSS-driven feature) can be applied by a station detecting OBSS interference from any of these OBSS APs, or the non-OBSS or MAP APs of the MAP group for which the NPCA feature (or any OBSS-driven feature) is not applied by a station detecting MAP activity from any of these MAP APs.

[0231] The controlling frame from an AP to its associated STAs may be a Beacon frame or a Probe Response frame to convey the list of APs. Preferably, the list of APs is included in a Channel Usage element (as defined in section 9.4.2.84 of the standard) with a new usage mode targeting MAP usage. Any new frame dedicated to MAP purpose and having this Channel Usage element can be used instead of a Beacon frame or a Probe Response frame.

[0232] In a variant focusing on the NPCA mechanism described above with reference to Figure 3, the AP sharing the list of its OBSS APs to its associated stations may update this existing OBSS AP list by removing the set of AP(s) of the MAP group determined at step 904 from the OBSS AP list.

[0233] Figure 8 illustrates, using a flowchart, general steps of a corresponding communication method 800 at the stations associated to the AP of Figure 7.

[0234] At step 801 , the station receives the controlling frame, i.e., it receives from its associated AP, a frame including a parameter to control a behaviour of the station in case the station detects Overlapping-BSS (OBSS) interference. Responsive to the controlling frame, the station applies the OBSS-driven operation control indicated in the frame: enabling, disabling, pausing, resuming, or the like of OBSS-driven operations.

[0235] Of course, some OBSS-driven operations may be enabled while other OBSS-driven operations may be disabled, upon receiving the controlling frame.

[0236] Figures 9a and 9b illustrate, using flowcharts, communication methods at the initiating AP and an initiated AP respectively, according to embodiments. The communication method intends to disable NPCA (or any other OBSS-driven mechanism) when the initiating AP sets up a MAP agreement with the initiated AP.

[0237] Method 900 starts at optional step 901 where the initiating AP discovers its surrounding APs.

[0238] At step 902, the initiating AP sends a MAP coordination request to the surrounding AP(s) so as to setup a MAP coordination. This above discovery step aims at obtaining knowledge of the surrounding APs to send them the MAP request. The discovery step may thus be optional for instance when the MAP request is broadcast.

[0239] The MAP request may be frame 260 of Figure 2, which is broadcast to the APs in the coverage of AP2 or multi-cast to AP1 and AP3 previously discovered by AP2. An exemplary content of this frame has been provided above with reference to Figure 2.

[0240] Next, at step 903, the initiating AP receives MAP coordination responses from the surrounding AP(s), for instance frames 261 of Figure 2. The responses indicate whether the initiated APs accept or reject the MAP coordination agreement. An exemplary content of the response frame has been provided above with reference to Figure 2.

[0241] Next, based on the received MAP responses, the initiating AP determines at step 904 the set of AP(s) accepting the MAP coordination. This will form the MAP group. To be recalled that any AP not responding to the MAP request is considered to reject the MAP coordination setup. Hence, it will be considered as an OBSS.

[0242] As mentioned above (Figure 2), the initiating AP may send a MAP Confirmation frame.

[0243] Next, at step 905, the initiating AP sends to its associated stations a controlling frame disabling the NPCA feature at the stations, or more generally disabling an OBSS-driven feature. Preferably, the controlling frame is an OM Notification frame as mentioned above. As explained above with reference to Figure 8, when the BSS’s stations receive this controlling frame from their associated AP, they disable the NPCA feature until receiving another command frame that enable anew the feature.

[0244] Method 910 starts at step 911 when the initiated AP receives the MAP coordination request sent by an initiating AP at step 902.

[0245] In response, at step 912, the initiated AP decides whether it wants to participate in the MAP coordination proposed by the initiating AP and, in the affirmative, sends a MAP coordination response to the initiating AP, received by the latter at step 903. Next, at step 913, the initiated AP determines the set of AP(s) involved in the MAP coordination based on the MAP coordination responses or absence of response from the surrounding AP(s) or based on subsequent information frame from one of the AP of the set of AP(s) having accepted the MAP coordination setup. This subsequent information frame may include the identity of the set of AP(s) belonging to the MAP group. For example, this frame may include one element per AP as described above (Figure 2) for the MAP Confirmation frame.

[0246] Next, at step 914, the initiated AP sends to its associated stations a controlling frame disabling the NPCA feature at the stations, or more generally disabling an OBSS-driven feature. This step is similar to step 905 but at the initiated AP side.

[0247] Figures 10a and 10b illustrate, using flowcharts, communication methods at the initiating AP and an initiated AP respectively, according to embodiments. The communication method intends to enable NPCA (or any other OBSS-driven mechanism) when the current MAP agreement is torn down, partially or entirely.

[0248] Method 1000 starts at step 1001 when the initiating AP sends a MAP coordination request to surrounding AP(s) so as to tear down a current MAP coordination, either entirely or partially.

[0249] The MAP coordination request for teardown may include all or part of the following: the MAP group identifier to identify the MAP agreement to teardown e.g., if the initiating AP has setup several MAP agreements, the AP ID or IDs for which the MAP agreement is torn down. An AP ID wild card may be used to indicate that the teardown is for the entire MAP group, the duration before the tear down is effective, a reason of the teardown (e.g., link disable, fairness issue, and so on).

[0250] Next, at step 1002, the initiating AP receives MAP coordination responses from the set of AP(s) or, in variants, for only the APs that are torn down (as specified in the MAP Coordination request).

[0251] The teardown is effective from the reception of the MAP coordination response or after the duration indicated in the MAP coordination request (or preconfigured) elapses. In case of absence of MAP coordination response from an initiated AP, the teardown is effective for that initiated AP after the duration indicated in the MAP coordination request (or preconfigured) elapses.

[0252] Next, at step 1003, the initiating AP sends to its associated stations a controlling frame enabling the NPCA feature at the stations, or more generally enabling an OBSS-driven feature. Step 1003 is similar to step 905, except that the OBSS-driven feature is enabled rather than disabled. As explained above with reference to Figure 8, when the BSS’s stations receive this controlling frame from their associated AP, they enable the NPCA feature until receiving another command frame that disable anew the feature.

[0253] Although, the OBSS-driven feature is globally enabled at BSS level (by the AP through the controlling frame), some stations may disable locally the feature. Method 1010 starts at step 1011 when the initiated AP receives the MAP coordination request send by an initiating AP at step 1001 to tear down a MAP coordination.

[0254] At optional step 1012, the initiated AP may send a MAP coordination response to the initiating AP, to acknowledge the request.

[0255] In embodiments, the initiated AP considers whether the teardown impacts it, e.g., by determining whether the MAP coordination request includes an AP ID that matches the identity of the initiated AP or the identity of a MAP group in which the initiated AP is involved. In the affirmative, the initiated AP sends the MAP coordination response. Otherwise, the MAP coordination request is ignored and no response is sent.

[0256] In other embodiments, the initiated AP systematically responds to a MAP coordination request.

[0257] The teardown is effective from the sending of the MAP coordination response or after the duration indicated in the MAP coordination request (or preconfigured) elapses. In case no MAP coordination response is sent, the teardown is effective after the duration indicated in the MAP coordination request (or preconfigured) elapses.

[0258] Next, at step 1012, the initiated AP sends to its associated stations a controlling frame enabling the NPCA feature at the stations, or more generally enabling an OBSS-driven feature. This step is similar to step 1003 but at the initiated AP side.

[0259] Figures 11a, 11 b, 12a, 12b are variants to Figures 9a, 9b, 10a, 10b wherein, instead of disabling and enabling an OBSS-driven mechanism such as the NPCA, the APs control the OBSS-driven mechanism at their associated stations by providing a list of APs based on which the stations trigger an OBSS-driven mechanism.

[0260] The transmitted list of APs may include a list of APs belonging to a MAP Group with which the transmitting AP has set up collaboration for medium sharing. A non-OBSS or MAP AP list is therefore built and sent. The associated stations do not intend to execute the OBSS-driven mechanism when a frame is received from an AP of the list, because the frame is a MAP frame. Conversely, they may execute the OBSS-driven mechanism when the frame is received from an AP outside the list.

[0261] In variants, the transmitted list of APs includes a list of APs in the vicinity of the transmitting AP, i.e., the APs that are considered as OBSS APs for the stations of the BSS. An OBSS AP list is therefore built and sent. To take into account any on-going MAP cooperation, the list of APs may exclude any AP belonging to a MAP Group with which the transmitting AP has set up collaboration for medium sharing. As a result, the stations receiving the OBSS AP list do not consider anymore the APs of the MAP group as OBSS APs. The associated stations do intend to execute the OBSS-driven mechanism when a frame is received from an AP of the OBSS AP list, because the frame is an OBSS frame. Conversely, they may avoid executing the OBSS-driven mechanism when the frame is received from an AP outside the OBSS AP list.

[0262] The same references throughout the Figures correspond to similar steps. The method 1100 of Figure 11a corresponds to the method 900 of Figure 9a wherein step 905 is replaced by step 1105.

[0263] Once the initiating AP known its surrounding APs (hence OBSS APs) and those participating in the AP cooperation (MAP Group) after step 904, the initiating AP can build the OBSS AP list by keeping the list of surrounding APs to which those of the MAP group are removed. In variants, the initiating AP only builds the non-OBSS or MAP AP list based on the MAP group.

[0264] Still at step 1105, the initiating AP sends the controlling frame including the list of AP(s) to its associated stations. Preferably, the controlling frame is a Beacon frame or Probe Response frame or an Action frame (an existing one enhanced to carry the AP(s) list or a new one defined with a new Category value - see Table 9-81 in section 9.4.1.11) as described in section 9.6 of the 802.11 REVme / D6.0 standard or a OM Notification frame as mentioned above or a new frame, having a dedicated Channel Usage element can be used to convey any type of list of APs. In a variant mentioned above, the AP may also update the existing OBSS AP list exchanged in the context of the NPCA mechanism, by removing the APs of the MAP group therefrom before sharing.

[0265] As explained above with reference to Figure 8, when the BSS’s stations receive this list of APs from their associated AP, they are able to determine whether a frame received from another AP is a MAP frame or an OBSS frame, depending on whether the other AP belongs to the list or not. Accordingly, the stations are able to enable or disable the NPCA feature (or any OBSS-driven mechanism) to favour intra-BSS communications in case of MAP cooperation.

[0266] The method 1110 of Figure 11 b corresponds to the method 910 of Figure 9b wherein step 914 is replaced by step 1114.

[0267] The initiated AP may determine its surrounding APs (in the same way as the initiating AP does at step 901). Once the initiated AP known its surrounding APs (hence OBSS APs) and those participating in the AP cooperation (MAP Group) after step 913, the initiated AP, at step 1114, builds the list of APs (either OBSS AP list or non-OBSS AP list) and sends the controlling frame including that list of AP(s) to its associated stations.

[0268] The BSS’s stations receiving this list of APs act accordingly, as explained above.

[0269] The method 1200 of Figure 12a corresponds to the method 1000 of Figure 10a wherein step 1003 is replaced by step 1203. In practice, the stations have received a list of APs from their associated AP (through method 1100 or 1110).

[0270] In the present method 1200, once the teardown is set through steps 1001 and 1002 is effective, the initiating AP, at step 1203, updates the current list of APs (either OBSS AP list or non-OBSS AP list) based on the APs that have been torn down: such APs are removed from the non-OBSS AP list, or are added to the OBSS AP list. For example, when the initiating AP has no longer an active MAP agreement, the non-OBSS AP list is empty (or the OBSS AP list lists all surrounding APs). Still at step 1203, the initiating AP sends the controlling frame including the updated list of AP(s) to its associated stations.

[0271] The BSS’s stations receiving this list of APs act accordingly, as explained above.

[0272] The method 1210 of Figure 12b corresponds to the method 1010 of Figure 10b wherein step 1013 is replaced by step 1213.

[0273] Step 1213 is similar to step 1203, however at the initiated AP side.

[0274] Figure 13 illustrates a resulting MAP coordination in the MAP system 100 of Figure 1. The same scenario as Figure 2 is provided. Hence, the same references correspond to the same features (frames, serving periods, TXOP).

[0275] The exchange of MAP request 260, MAP responses 261 and MAP Confirmation frame 262 to set up a MAP coordination between APs is conducted as in Figure 2.

[0276] After the MAP coordination agreement has been made, each AP may perform the method of any of Figures 9 to 12 to send a controlling frame (respectively, frame 1371 from AP1 , frame 1372 from AP2, frame 1373 from AP3) to its associated stations to control the OBSS-driven mechanisms. For example, as mentioned above, the controlling frame may disable the OBSS- driven mechanism such as the NPCA or provide a list of APs (either OBSS AP list or non-OBSS AP list) for the associated stations to locally adjust their OBSS-driven behaviour upon determining whether a received frame is from an AP belonging to the same MAP group as their associated AP or not. One advantage of the list of APs is to limit the restriction of the OBSS-driven mechanism usage only to the APs involved in the MAP group.

[0277] For example, from this point, the OBSS-driven mechanism (e.g., the NPCA feature) is disabled for the stations associated to the APs involved in the MAP coordination agreement setup with the frame exchange 260 / 261 / 262.

[0278] Next, as in Figure 2, each station competes with each other to access the medium. In the scenario, AP2 wins the access to send MAP schedule frame 200, reserving TXOP 290.

[0279] As the OBSS-driven mechanism is disabled, the stations of BSS1 and BSS3 remain available to communicate with their AP during the serving period (221 and 222) allocated to their BSS.

[0280] In the case where the MAP frames are still considered as inter-BSS (no frame classification as proposed above - Figures 4-6), those stations should not consider their basic NAV to decide whether to answer to a Trigger frame from their AP if the trigger frame from their AP follows a TXOP coordination sequence (230 / 240 or 250 / 260) by which the sharing AP subleases the medium to their AP. For instance, the TXOP coordination frame could be a MU- RTS TXS addressed to the AP for which the next timeslot will be allocated. Then, during the serving period 221 (resp. 222), AP1 (resp. AP3) and its associated stations can communicate. At the end of the serving period, the sharing AP, AP2, retrieves the medium and can sublease or share the medium to another AP through another TXOP coordination sequence (e.g., 250 / 260 for AP3). In the case where the frame classification above is implemented, the stations, in particular those of BSS1 and BSS3, can detect MAP activity. Therefore, they do not set their basic NAV, in order to remain available should the MAP coordination offer some transmission opportunities to their BSS.

[0281] In embodiments relying on the MAP NAV described above, the stations of BSS1 and BSS3 detecting MAP schedule frame 200 set their MAP NAV (not shown) to the TXOP duration.

[0282] Upon reception of MAP schedule frame 200, addressed AP1 and AP3 respond with MAP acknowledgement frame 210 (e.g., a CTS) back to AP2.

[0283] For each BSS not served with the next serving period (here period 220 for BSS2), the MAP acknowledgement frame 210 from the AP of the BSS allows its associated stations to set their basic NAV for at least the duration of the next serving period. This is shown under reference 1380. In embodiments, MAP acknowledgement frame 210 provides a duration encompassing the serving period 220 and the next MAP frame 230, allowing the associated stations to set their basic NAV up to the end of the next MAP frame 230. By setting their basic NAV, the stations can perform OBSS-driven operations (e.g., NPCA) during the serving periods of other BSSs.

[0284] When the next serving period 221 is triggered by MAP frame 230, addressed AP1 and AP3 respond with MAP acknowledgement frame 240 (e.g., a CTS) back to AP2.

[0285] The stations of BSS1 (e.g., STA11) are concerned by the next serving period 221 . Consequently, they do not set their basic NAV, but set their intra-BSS NAV (not shown) for the duration of serving period 221 (optionally plus the duration of next MAP frame 250) and wait for communication from AP1 . On the other hand, the stations of BSS3 are not concerned by the next serving period 221 . Hence, they set their basic NAV for the same duration and can perform OBSS- driven operations (e.g., NPCA).

[0286] The same occurs for the next serving period 222, triggered by MAP frame 250, by interchanging the roles of BSS1 and BSS3.

[0287] Figure 14a schematically illustrates a communication device 1400 configured to implement at least one embodiment of the present invention, for instance any station (AP or non-AP) shown in Figure 1.

[0288] The communication device 1400 may preferably be a device such as a microcomputer, a workstation or a light portable device. The communication device 800 comprises a communication bus 1413 to which there are preferably connected: a central processing unit 1401 , such as a processor, denoted CPU; a memory 1403 for storing an executable code of methods or steps of the methods according to embodiments of the invention as well as the registers adapted to record variables and parameters necessary for implementing the methods; and at least one communication interface 1402 connected to a wireless communication network, for example a communication network according to one of the IEEE 802.1 1 family of standards or Wi-Fi alliance protocols, via transmitting and receiving antennas 1404. Preferably the communication bus provides communication and interoperability between the various elements included in the communication device 1400 or connected to it. The representation of the bus is not limiting and in particular the central processing unit is operable to communicate instructions to any element of the communication device 1400 directly or by means of another element of the communication device 1400.

[0289] The executable code may be stored in a memory that may either be read only, a hard disk or on a removable digital medium such as for example a disk. According to an optional variant, the executable code of the programs can be received by means of the communication network, via the interface 1402, in order to be stored in the memory of the communication device 1400 before being executed.

[0290] In an embodiment, the device is a programmable apparatus which uses software to implement embodiments of the invention. However, alternatively, embodiments of the present invention may be implemented, totally or in partially, in hardware (for example, in the form of an Application Specific Integrated Circuit or ASIC).

[0291] Figure 14b is a block diagram schematically illustrating the architecture of the communication device 1400, adapted to carry out, at least partially, the invention. As illustrated, device 1400 comprises a physical (PHY) layer block 1423, a MAC layer block 1422, and an application layer block 1421.

[0292] The PHY layer block 1423 (here an 802.1 1 standardized PHY layer) has the task of formatting, modulating on or demodulating from any 20MHz channel or the common communication channel, and thus sending or receiving frames over the wireless radio medium used, such as 802.11 frames, for instance MAC data and management frames based on a 20MHz width to interact with legacy 802.11 stations (non-AP, AP, non-AP MLD, AP MLD), as well as of MAC data frames of OFDMA type having smaller width than 20MHz legacy (typically 2 or 5 MHz) to / from that radio medium.

[0293] The MAC layer block or controller 1422 preferably comprises a MAC 802.11 layer 1424 implementing conventional 802.1 1 MAC operations, and additional block 1425 for carrying out, at least partially, the invention. The MAC layer block 1422 may optionally be implemented in software, which software is loaded into RAM 1403 and executed by CPU 1401. The MAC 802.11 layer 1424 may implement an Upper-MAC stack along with a series of Lower-MAC modules.

[0294] Preferably, the additional block 1425, referred to as MAP / OBSS interference managing module which has different operations to implement parts of the invention, depending on the role played by the communication device 1400. As the same device can play different roles over time, the additional block 1425 is preferably designed to selectively perform the different operations relative to MAP and OBSS features.

[0295] MAC 802.1 1 layer 1424 and MAP / OBSS managing module 1425 interact one with each other in order to process accurately communications over the medium, e.g., over single- user or OFDMA RUs addressed to multiple stations according to embodiments of the invention. In particular, they implement all or part of the methods described above. On top of the Figure, application layer block 1421 runs an application that generates and receives data packets, for example data packets such as a video stream. Application layer block 1421 represents all the stack layers above MAC layer according to ISO standardization.

[0296] Although the present invention has been described hereinabove with reference to specific embodiments, the present invention is not limited to the specific embodiments, and modifications will be apparent to a skilled person in the art which lie within the scope of the present invention.

[0297] Many further modifications and variations will suggest themselves to those versed in the art upon referring to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the invention, that being determined solely by the appended claims. In particular the different features from different embodiments may be interchanged, where appropriate.

[0298] In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used.

Claims

CLAIMS1. A communication method in a wireless network, comprising at an access point (AP) managing a Basic Service Set (BSS): sending to at least one station of the BSS, a frame including a parameter to control a behaviour of the station in case the station detects Overlapping-BSS (OBSS) interference.

2. The method of Claim 1 , wherein the frame is sent responsive to a change in a Multi- AP (MAP) coordination scheme.

3. The method of Claim 2, wherein the change includes a setup of a MAP agreement involving the AP or a partial or full teardown of a MAP agreement involving the AP.

4. The method of Claim 3, wherein a setup of a MAP agreement disables an OBSS- driven mechanism while or a partial or full teardown of a MAP agreement enables the OBSS- driven mechanism.

5. The method of Claim 1 , wherein the frame is sent responsive to determining that the number of other APs in the vicinity of the AP and / or an amount of data to be exchanged within the BSS are lower than respective thresholds.

6. A communication method in a wireless network, comprising at a station belonging to a Basic Service Set (BSS) managed by an access point (AP): receiving from the AP, a frame including a parameter to control a behaviour of the station in case the station detects Overlapping-BSS (OBSS) interference.

7. The method of Claim 1 or 6, wherein the parameter controls whether the station uses an OBSS-driven mechanism or not in case the station detects OBSS interference.

8. The method of Claim 7, wherein the parameter defines an activation or deactivation of the OBSS-driven mechanism at the station.

9. The method of Claim 7, wherein the parameter includes a list of APs based on which the station triggers an OBSS-driven mechanism.

10. The method of Claim 9, wherein the list of APs includes a list of APs belonging to a Multi-AP (MAP) Group with which the AP has set up collaboration for medium sharing.

11. The method of Claim 9, wherein the list of APs includes a list of APs in the vicinity of the AP.

12. The method of Claim 11 , wherein the list of APs excludes any AP belonging to a Multi-AP (MAP) Group with which the AP has set up collaboration for medium sharing.

13. The method of Claim 7, wherein the given OBSS-driven mechanism includes a Power Save mode, a switch to another communication channel, such as a Non-Primary Channel Access mechanism.

14. The method of Claim 1 or 6, wherein the parameter is included in one from an Operating Mode Notification frame, a Beacon frame, a Probe Response frame and a Channel Usage element having a Usage mode set to a Multi-AP coordination value.

15. A communication method in a wireless network, comprising at station belonging to a first Basic Service Set (BSS) managed by a first access point (AP): performing a frame classification of a received frame as an intra-BSS frame or a Multi-AP (MAP) frame or an inter-BSS frame, in which a non-intra-BSS frame is classified as a MAP frame if the received frame signals medium sharing between APs belonging to a MAP Group to which the first AP belongs, or classified as inter-BSS frame otherwise.

16. The method of Claim 15, wherein responsive to classifying the received frame: as an inter-BSS frame, the station sets a basic NAV with duration information indicated by the received frame, as an intra-BSS frame, the station sets an intra-BSS NAV with duration information indicated by the received frame, as a MAP frame, the station sets a MAP NAV with duration information indicated by the received frame.

17. The method of Claim 16, wherein responsive to classifying the received frame as a MAP frame, the station sets its intra-BSS NAV with duration information indicated by the received frame.

18. The method of Claim 16, wherein responsive to classifying the received frame as a MAP frame, the station, operating as the first AP, sets its basic NAV with duration information indicated by the received frame and ignores the basic NAV to respond to any MAP frame from another AP allocating the medium to the first BSS.

19. The method of Claim 16, wherein responsive to classifying the received frame as a MAP frame, the station replies to the MAP frame by sending an acknowledgment frame indicating a duration equal to the sum of the duration of a serving period triggered by the MAP frame and the duration of a subsequent MAP frame to offer a subsequent serving period.

20. The method of Claim 16, wherein if the received frame is a MAP frame allocating a serving period to another BSS than the first BSS and serving period truncation is allowed for the serving period, the station sets an intra-BSS NAV and waits for a communication from the first AP during a duration of the serving period.

21. The method of Claim 20, wherein the station exchanges with the first AP station’s capabilities to support listening of serving period truncation while applying OBSS-drivenoperations to apply when a received frame is a MAP frame allocating a serving period to another BSS than the first BSS.

22. The method of Claim 15, wherein the received frame is a MAP frame allocating a serving period to the first BSS for a serving duration, and the first AP sends, to a sharing AP transmitting the MAP frame, an indication of anticipated end of the service period to give the medium back to the sharing AP before an end of the serving duration.

23. The method of Claim 15, wherein the received frame is a MAP frame allocating a serving period to the first BSS for a serving duration, and the station, operating as the first AP, receives, from a sharing AP transmitting the MAP frame, an indication that truncation of the serving period is allowed for the first AP.

24. The method of Claim 15, wherein the received frame has a receiving address (RA) not set to an address of the station.

25. The method of Claim 15, wherein the received frame is classified as a MAP frame using signalling information, the signalling information comprising at least one of: a Trigger Type subfield of a Common Info field of a trigger frame set to a MAP type; a bit or field defined in the Common Info field set to a MAP type; a Triggered TXOP Sharing Mode subfield of a Common Info field of a trigger frame set to a MAP type; a Special User Info field that includes a bit or field set to a MAP type; a field in a User Info field of a trigger frame set to an association identifier (AID) defined during setting a MAP agreement and dedicated to a BSS different from the BSS sending the frame; both RA and TA fields set to MAC addresses of two different APs;DA and / or SA fields set to MAC addresses of AP(s) of a MAP group;BSSID field set to a value dedicated to identify a MAP group; a Public Action field value of a Public Action frame set to a MAP type; or a field in an element of a BSS Coexistence Management frame set to a MAP type.

26. The method of Claim 15, wherein the received frame is classified as a MAP frame when the received frame has a group identifier (GROUPJD) field of receive vector (RXVECTOR) parameters set to a specific value signalling a MAP frame.

27. The method of Claim 15, wherein the APs of the MAP group are included in a multi- BSS configuration of the first AP.

28. The method of Claim 15, wherein the first AP exchanges frame with other APs to set up the MAP group, wherein the exchanged frames include one or more Public Action frames.

29. A wireless communication device comprising at least one microprocessor configured for carrying out the method of Claim 1 , 6 or 15.

30. 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 the method of Claim 1 , 6 or 15.

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