Methods and devices for TWT coordination and configuration in multi-AP operation

Abstract

APs with OBSS have overlapping wireless coverage areas which can result in co-channel interference. In the invention a first overlapping AP1 can transmit TWT schedule information 560 to a second overl

Description

FIELD OF THE INVENTION The present disclosure generally relates to wireless communications and more specifically to coordination in multi-AP operations with a view of reducing OBSS interferences. The disclosure more particularly regards OBSS TWT schedules in neighbouring BSSs, to protect a TWT schedule in a target BSS. BACKGROUND OF THE INVENTION 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. In dense multiple AP networks, co-channel interference becomes a problem. Overlapping Basic Service Set (OBSS) interference refers to interference resulting from transmissions of another BSS. The stations usually adopt a specific behaviour (“OBSS behaviour” or “OBSS-driven behaviour”) in a case where 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. A conventional OBSS behaviour requires that a station receiving a frame that is not addressed to it - which is the case for an 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. 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. 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 802.11 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. For example, the MAP coordination can use the Triggered TXOP sharing procedure (section 35.2.1.2 of the draft IEEE (RTM) P802.11be / D7.0 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 medium access competition between neighbour BSSs and so the potential collisions to be minimized, 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 P802.11be / D7.0 standard that allows a temporal sharing, other sharing procedures such as MU (Multi User) operations defined in sections 26.5 and 35.5 of IEEE802.11be are also envisioned in the MAP context to share the frequency resource through the set of APs. Contributions to 802.11 bn have been made to reduce OBSS interference in case of Target Wake Time (TWT) scheduling in BSSs. The TWT mechanism, originally defined in the IEEE 802.11 ah, enables a wake time negotiation between an AP and an associated station (STA) to improve power efficiency. With TWT operation, a STA has only to wake up at a pre-scheduled time negotiated with another STA or AP in the network. TWT has been adapted to be included in the IEEE 802.11be / D7.0 standard. An adaptation is known as the Restricted Target Wake Time (R-TWT) which schedules dedicated (and protected) service periods (SPs) for stations (possibly affiliated with a non-AP multi-link device, MLD, as introduced in IEEE 802.11 be / D7.0) to convey their latency sensitive traffic(s) over their BSS. An R-TWT agreement is nothing more than a Broadcast TWT agreement negotiated between an AP and an associated non-AP station of the BSS on a given link. The non-AP station establishes with the AP membership in the Broadcast TWT (or R-TWT) schedule. The R-TWT Service Periods SPs of the R-TWT schedule are advertised in broadcast management frames (e.g., beacons), using R-TWT information about the negotiated R-TWT SPs, typically a Broadcast TWT identifier (bTWT ID). To ensure the efficiency of the TWT mechanism, the overlapping BSSs should cooperate to reduce risks of OBSS interference. Contribution IEEE 802.11-22 / 1530r1 (entitled “Multi AP coordination for nextgeneration Wi-Fi”) has been made where neighbouring APs can share TWT information of their BSS to reduce OBSS interference experienced by the STAs. For R-TWT operation, an AP (“target AP”) of a current BSS may request a neighbour AP’s BSS to quiet transmission in that BSS. If the neighbour AP accepts, it sends a Quiet element (as defined in the IEEE 802.11 h standard) to its associated stations, the Quiet element corresponding to the R-TWT schedule for which the Quieting request was sent by the target AP. SUMMARY OF INVENTION Enhanced MAP coordinated R-TWT SP protections have been proposed, including the setting of an OBSS R-TWT (with OBSS service period (SP)) in a neighbouring BSS(s) when a r-TWT SP is initiated in the current (“target”) BSS. The main concept of the OBSS R-TWT is to set up an OBSS service period (SP) in neighbouring BSS(s) when a r-TWT SP is initiated in the current BSS. This is described in co-pending international application No PCT / EP2024 / 059627. The OBSS R-TWT SPs of the neighbouring BSS(s) and the r-TWT SPs of the current BSS are timely aligned, meaning they overlap in such a way absence of communication in the neighbouring BSS due to the OBSS R-TWT SP benefits to the r-TWT SP of the current BSS. The overlap may be organized over at least the beginning of the SPs; for example, the SPs may start simultaneously, meaning their starting times are fully aligned in time. The efficiency of the OBSS R-TWT is driven by the neighbouring AP through coordinated medium access. In this context, the neighbouring AP can apply some rules during its OBSS R-TWT SPs, including providing any following element to its associated STAs: - an OBSS TWT element that forbids the STAs of the neighbouring BSSs to access the medium during the OBSS R-TWT SPs, - an OBSS TWT element that adjusts the EDCA parameters of the neighbouring BSSs to penalize the medium access mechanism of all STAs of the neighbouring BSSs, - an OBSS TWT element that indicates a temporary operating channel modifications for STAs of the neighbouring BSSs, e.g a channel switch announcement, Dynamic Subchannel Operation (DSO), Non-Primary Channel Access (NPCA). MAP coordinated R-TWT SP protections can further be improved. Embodiments provide a communication method in a wireless network comprising the following steps: exchanging, from a first access point (AP) managing a first Basic Service Set (BSS) to a second AP managing a second BSS - for example the above current AP and neighbouring AP -, information about a Target Wake Time (TWT) schedule provided in the first BSS, and setting, by the second AP, an overlapping BSS (OBSS) TWT schedule in the second BSS which is timely aligned with the TWT schedule in the first BSS (i.e., their service periods SPs are timely aligned; they start substantially at the same time; they may end substantially at the same time), wherein the first AP also exchanges all or part of the following information items for the second AP to configure the OBSS TWT schedule: a Buffer Status Report (BSR) of the first BSS reporting an amount of data to be exchanged within the first BSS, possibly per access category or per TID, a low latency data scheme of the first BSS reporting one or more prioritized TID in the first BSS, a SP splitting scheme of the first TWT SPs reporting a breakdown of a service period (SP) within a Beacon interval of the first BSS, a reciprocal OBSS TWT indication reporting an agreement of the first AP to provide a second OBSS TWT schedule in the first BSS timely aligned with a second TWT schedule in the second BSS. Thanks to these indications, the second (neighbouring) AP is able to tightly adjust the OBSS TWT schedule protecting the TWT schedule in the first AP, to the needs of each BSS, with a view of improving network efficiency. In some embodiments, configuring the OBSS TWT schedule based on all or part of the information items includes adjusting a length of a SP ofthe OBSS TWT schedule. In particular, adjusting a length of a SP ofthe OBSS TWT schedule may include negotiating, with the first AP, a length of a SP for the TWT schedule and the OBSS TWT schedule. In particular, the same length is used to ease time alignment between them. More specifically, all initiated SPs must be synchronized to be efficient. For example, should the second BSS have a substantial amount of data to be exchanged compared to the first BSS, the second AP may reduce the length of the OBSS SPs in order to keep enough opportunities for its BSS to exchange the data. In some embodiments, configuring the OBSS TWT schedule based on all or part of the information items includes adjusting a medium access policy in the second BSS during a SP ofthe OBSS TWT schedule. In particular, adjusting a medium access policy in the second BSS may include applying, by non-AP stations of the second BSS, at least one degraded EDCA parameter. The second AP may instruct its associated non-AP stations to do so. This degrading of EDCA parameters may include forbidding medium access or altering medium access. As an example, a dedicated OBSS EDCA Parameter Set (i.e., different from known EDCA Parameter set and MU EDCA Parameter set) may be used by the non-AP stations ofthe second BSS. As an example, a degraded minimum size of a contention window (ECWmin) may be used by the non-AP stations of the second BSS. As an example, a degraded arbitration interframe space number (AIFSN) may be used by the non-AP stations ofthe second BSS. In some embodiments, the degraded EDCA parameter is advised by the second BSS in a Beacon frame, e.g., through a dedicated OBSS EDCA Parameter Set that is additional to (hence different from) the conventional legacy EDCA Parameter Set and multi-user (MU) EDCA Parameter Set. In some embodiments, the degraded EDCA parameter is conveyed in a frame sent by the second AP to set the OBSS TWT schedule in the second BSS. In some embodiments, configuring the OBSS TWT schedule based on all or part of the information items includes splitting a SP of the OBSS TWT schedule in the second BSS according to the SP splitting scheme provided by the first AP. Such SP splitting advantageously offers a medium access regularly during a short period of time. It is especially useful for low-latency flows that require short medium access time. In some embodiments, configuring the OBSS TWT schedule based on all or part of the information items includes setting a second TWT schedule in the second BSS and setting the OBSS TWT schedule in the second BSS in a case where a second OBSS TWT schedule is set in the first BSS that is timely aligned with the second TWT schedule. The second AP may obtain confirmation from the first AP that the second OBSS TWT schedule has been set. The reciprocity of OBSS TWT schedule settings ensure fairness through the BSSs. The adjusting of the SP length, the adjusting of the medium access policy, the splitting of the SP of the OBSS TWT schedule and the condition set of the OBSS TWT schedule to the setting of the second OBSS TWT schedule by the first AP can be combined all together or partly together. In some embodiments, the information items are included in a TWT element extending the TWT element defined in the IEEE P802.11 be / D7.0 standard. Extending an element means having an enhanced element format, e.g., having additional fields. In some embodiments, the information items are included in a Broadcast TWT Parameter Set field of the extended TWT element. In some embodiments, the information items are included in an additional subfield to the subfields of the Broadcast TWT Parameter Set field as defined in the IEEE P802.11be / D7.0 standard. Alternatively, the information items may be included in an extended (to include additional subfields) version of the Restricted TWT Traffic Info field as defined in the IEEE P802.11 be / D7.0 standard. The second AP may advise its associated non-AP stations - in particular only its associated stations that are interfering with the first BSS - about the OBSS TWT schedule, using an OBSS TWT element conveyed in a beacon frame or in a probe response frame. The first AP may advise the second AP about the TWT schedule in the first BSS, using a beacon frame broadcast in the first BSS (but received by the second AP) or a dedicated unicast frame addressed by the first AP to the second AP. Such a frame can be seen as a MAP coordination frame. Correlatively, the invention also provides a wireless communication device comprising at least one microprocessor configured for carrying out any method as described above. 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. 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. 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. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of example only, and with reference to the following drawings in which: Figure 1 illustrates an exemplary network environment in which embodiments of the present disclosure can be implemented; Figure 2a illustrates, using a flowchart, general steps at an AP of a communication method providing TWT coordination in MAP operation according to embodiments of the invention; Figure 2b illustrates, using a flowchart, general steps at a non-AP station of a communication method according to embodiments of the present disclosure; Figure 3 illustrates a format of a Target Wake Time, TWT, element according to embodiments of the present disclosure; Figure 4 illustrates exemplary formats of an OBSS TWT Info field of the TWT element of Figure 3; Figure 5 illustrates a transmission sequence implementing a TWT coordination for reduced OBSS interference in MAP operation, according to embodiments of the present disclosure; Figure 6a shows a schematic representation a communication device in accordance with embodiments of the present disclosure; and Figure 6b shows a schematic representation of a wireless communication device in accordance with embodiments of the present disclosure; DETAILLED DESCRIPTION OF EMBODIMENTS A target AP provides a neighbourhing AP with information about a TWT schedule in the target BSS, together with additional information such as a Buffer Status Report (BSR) of the target first BSS, a low latency data scheme of the target BSS reporting one or more prioritized TID in the target BSS, a SP splitting scheme of the TWT SPs reporting a breakdown of a service period (SP) within a Beacon interval of the target BSS, a reciprocal OBSS TWT indication reporting an agreement of the target AP to provide a second OBSS TWT schedule in the target BSS timely aligned with a second TWT schedule in the second BSS. The neighbouring AP can then configure an OBSS TWT schedule in its BSS based on the received information, to protect the TWT schedule of the target BSS. The OBSS TWT schedule is timely aligned with the TWT schedule. The neighbouring AP advises its associated stations about the OBSS TWT schedule. 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. 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. 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. 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. The 802.11 family of standards define various media access control (MAC) mechanisms to drive access to the wireless medium. 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). This channel access based on the primary channel is known as the Primary Channel Access or “PCA”. 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. 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. 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. Efficient medium usage within one operating channel having an operation bandwidth (up to 320MHz in the latest 802.11be / D7.0 standard; however may be wider in future amendments) has evolved along the evolution of the IEEE 802.11 standards. For example, dynamic bandwidth signalling feature was introduced in the IEEE 802.11ac amendment, preamble puncturing feature was introduced in the IEEE 802.11ax-2021 standard approved on February 9, 2021 and further evolved in the IEEE 802.11 be amendments. 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 IDentifiers (AlDs) 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). The current discussions in the 802.11 be task group, as illustrated by draft IEEE P802.11be / D7.0, 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. 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. Figure 1 illustrates an exemplary network environment in which embodiments of the present disclosure can be implemented. The illustrated wireless network environment comprises a multi-AP 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 an operating channel (e.g., 20 MHz, 40 MHz, 80 MHz, 160 MHz or 320 MHz). A first wireless network (or Basic Service Set) BSS1 comprises an access point (AP) 110 and three non-AP stations (STAs) 111, 112 and 113 associated with the AP 110 (i.e., registered with 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 networksand 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. 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. The stations (AP and non-AP) of each wireless network exchange data frames over the communication channel 100, under the management of the AP. A primary channel, usually 20 MHz channel, is defined per wireless network on which the management frames are exchanged. The other 20 MHz channels of the communication channel, if any, are known as secondary channels. In the context of the invention, the APs can also communicate one with each other, either using a 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). 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 IDentifier (AID) to the requesting station. For example, the AID is a 16-bit value uniquely identifying the station. The stations (including the AP) compete one against each other over the communication channel (including the primary channel and optionally secondary channels to increase bandwidth) using EDCA (Enhanced Distributed Channel Access) contention to access the communication channel in order to be granted a transmission opportunity (TXOP). The TXOP may then be used to transmit (single-user, SU) data frames or to implement multi-user (MU) transmissions. 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 other stations of the wireless network. 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 are defined over the 20 MHz channel or channels used, known as resource units. 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. In the IEEE 802.11 wireless local area networking standards, the multi-AP system 100 may correspond to an extended service set (ESS) and each of the wireless networks to a basic service set (BSS). 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. To meet low latency requirements in 802.11 be as well as to increase efficiency of the UL MU operation, existing mechanisms have been reused and improved, which are summarized now. The Target Wake Time (TWT) mechanism, originally defined in the IEEE 802.11 ah and 802.11ax standards, has been adapted to be included in the 802.11be / D7.0 standard. An adaptation is known as the Restricted Target Wake Time (R-TWT or r-TWT) which schedules dedicated (and protected) service periods (SPs) for stations (affiliated with a non-AP MLD) to convey their latency sensitive traffic(s) over their BSS. An R-TWT agreement is nothing more than a Broadcast TWT agreement negotiated between an AP and one (or more) associated non-AP station of the BSS of a given link. The non-AP station establishes with the AP membership in a Broadcast TWT (or R-TWT) schedule. The schedule may be defined for some TIDs. The R-TWT Service Periods SPs of the R-TWT schedule are advertised in broadcast management frames (e.g., beacons), using an R-TWT information about the negotiated R-TWT SPs, typically a Broadcast TWT ID (bTWT ID). Non-AP stations in a power saving mode can then wake up at the time of the R-TWT SPs to efficiently communicate during those periods. Mechanisms like TWT or R-TWT are negotiated per link in case of ML operation, that is to say between an initiator affiliated STA of the non-AP MLD and the corresponding affiliated AP of the AP MLD. For a given link, a non-AP station establishes membership in broadcast TWT schedules of the AP, while the AP delivers broadcast TWT parameter sets to the non-AP stations. The non-AP station is said to be the TWT scheduled station, while the AP is said to be the TWT scheduling station. Negotiations to become a member of or to terminate membership in an R-TWT schedule (more generally a broadcast TWT) are performed through an exchange of frames that carry TWT elements (defined in section 9.4.2.198 TWT element of the IEEE P802.11-REVme / D7.0 standard of August 2024), having the Negotiation Type subfield set to 3 (Broadcast TWT). In particular, a non-AP station may request to become a member of a TWT schedule by transmitting a TWT Setup frame to its associated AP, that contains a TWT element for a given R-TWT schedule. The AP then advertises the scheduled broadcast TWT (or R-TWT) using broadcast TWT elements in its management frames, typically in the beacon frames, FILS Discovery frames and broadcast Probe Response frames. The TWT SP of an R-TWT schedule is uniquely identified by the <bTWT ID, MAC address of TWT scheduling AP> tuple, where the TWT scheduling AP is the affiliated AP of concerned link in case of AP MLD. Broadcast TWT ID (bTWT ID) is used to identify an R-TWT schedule, and thus to identify the R-TWT SPs belonging to the same R-TWT schedule. An initiator STA can request its AP to become an R-TWT scheduled STA, by negotiating R-TWT SPs for its low latency traffics using a TWT Setup frame conveying the above-mentioned TWT element. For example, initiator STA (e.g., affiliated STA of a non-AP MLD) may negotiate the wake time, wake interval and the TIDs to be allowed in the R-TWT. The AP (e.g., affiliated AP of the AP MLD on that link) provides a TWT Response frame accepting or refusing the request. In other words, the STA requests membership in an R-TWT schedule. A TWT Setup frame carries a TWT element with the Negotiation Type subfield set to 3 and a TWT Setup Command field set to Request TWT, Suggest TWT, or Demand TWT. A Restricted TWT Parameter set in the TWT element indicates a Broadcast TWT ID (bTWT ID) of the R-TWT schedule that the STA is requesting to join. The AP has possibility to answer (TWT Response frame) with no new R-TWT schedule for the bTWT ID (keep the existing one), or offering an alternative set of parameters to those indicated in TWT Setup frame, or creating a new R-TWT schedule with a new bTWT ID. Once the negotiation and membership are completed, a conventional TWT / R-TWT scheduled STA that is in awake state may enter, thanks to the advertising of the R-TWT SPs (e.g., through beacon frames), the doze state after receiving a Beacon frame with a Restricted TWT element indicating the existence of an R-TWT schedule and switch back to the awake state at the R-TWT start times. The Beacon frame indicates an R-TWT SP during which the TWT scheduling AP intends to send Trigger frames on that link, or DL BUs (Bufferable Units) to the TWT scheduled STAs. At the beginning of each TWT / R-TWT service period, and expecting the TWT scheduled stations are in the awake state, the TWT scheduling AP usually uses OFDMA Multiuser techniques (e.g., MU UL trigger-based transmission, MU DL transmission) to manage the R-TWT SP and possibly offer resource units to all or part of the TWT scheduled stations in the awake state. Still referring to Figure 1 that depicts multiple APs, a Multi-AP (MAP) technology has emerged where APs 110, 120, 130 collaborate to share the common communication channel once one of them is granted access to it. To do so, the APs exchange messages one with each other to coordinate the MAP communications, and thus to avoid interference. MAP sharing of the common communication channel is resource-based. An amount of a shared resource can be measured in time units, frequency band width, number of streams, amount of data or traffic (e.g., number of bytes) and / or any other suitable unit, depending on the type of resources as defined above. In this perspective, “shared resources”, “shared frequency band”, “shared channels” and “shared resource units” are synonyms and designate those resources offered by one of the APs to any other AP through the MAP technology. To coordinate the MAP communications, the APs may be part of an inter-AP coordination group (also referred below to “MAP coordination set of APs”, “MAP group”, “Coordination group” or “AP Candidate Set for MAP sharing”, etc.), the formation of which is out of scope of the present invention. As an example, the APs willing to collaborate may previously issue management frames, like beacons or dedicated broadcasted frames, to advertise the other APs of their MAP coordination capability. The coordination group may contain one or more APs. Embodiments described below provide a more efficient TWT coordination in MAP operation than contribution 11-22-1530 and corresponding publication US 2022 / 408355, to mitigate the interference between neighbouring APs. In these embodiments, (restricted) TWT service periods of a target BSS pertaining to the MAP collaborative set are replicated in time through a new TWT period, called OBSS TWT, in a second (neighbouring) BSS of the set, wherein activities of the OBSS TWT are limited for STAs of the second (neighbouring) BSS. To do so, a second AP managing the second (neighbouring) BSS first receives, from a first AP managing the first target BSS, a MAP coordination frame specifying a TWT schedule provided in the first BSS. The first AP also provides additional information items for the second AP to configure, set or design the OBSS TWT schedule to be set in order to protect the TWT schedule of the first BSS. Such information items include all or part of: a Buffer Status Report (BSR) of the first BSS reporting an amount of data to be exchanged within the first BSS, possibly per access category or per TID, a low latency data scheme of the first BSS reporting one or more prioritized TID in the first BSS, a SP splitting scheme of the first TWT SPs reporting a breakdown of a service period (SP) of the first TWT schedule within a Beacon interval of the first BSS, a reciprocal OBSS TWT indication reporting an agreement of the first AP to provide a second OBSS TWT schedule in the first BSS timely aligned with a second TWT schedule in the second BSS. Next, the second AP, responsive to the receiving, configures the OBSS TWT schedule based on all or part of these information items. For example, as described below, it may adjust or negotiate a length of a SP of the OBSS TWT schedule, adjust a medium access policy in the second BSS during a SP of the OBSS TWT schedule, split a SP of the OBSS TWT schedule in the second BSS according to the SP splitting scheme provided by the first AP. It may also decide to set a second TWT schedule in the second BSS and to set the OBSS TWT schedule in the second BSS only in a case where a second OBSS TWT schedule is set in the first BSS that is timely aligned with the second TWT schedule. For example, the length of the requested OBSS TWT SP may be adapted to the global bandwidth needs of all BSSs, especially when strong medium access rules are applied to the interfering BSSs. Due to the impact in term of throughput for the neighbouring (interfering) BSSs, only short OBSS R-TWT SPs can be setup and reserved only for transmitting low latency flows that require precise and periodic medium accesses. The OBSS TWT schedule has OBSS TWT Service Periods, SPs, that are preferably aligned in time, or at least partially overlap, with first TWT SPs of the TWT schedule in the first target BSS. Note that the overlap may be partial or full over the first TWT SPs. A full overlap may correspond to a second TWT SP aligned with, or encompassing, the first TWT SPs. It should be noted that the use of the OBSS TWT element for defining second (OBSS) TWT SPs relates to a preferred implementation; of course, other types of elements or other fields in the sent frame may be used to define the second TWT SPs. The OBSS TWT SPs and TWT SPs can have substantially the same starting time. The OBSS TWT SPs and TWT SPs can have substantially the same ending time. The second AP can then send, to its associated stations (i.e., of the second BSS), a frame also including the TWT element or an alternative “overlapping BSS” (OBSS) TWT element, defining the OBSS TWT schedule. By handling the OBSS TWT schedule in a synchronous manner with the TWT schedule of the first target BSS, the second (neighbouring) AP can adjust the communication or medium access policy of its own associated stations during the TWT schedule of the first target BSS, hence can adjust risks of interference. A TWT coordination is therefore achieved. As mentioned above, the medium access policy can be finely tuned based on the information items provided by the first AP, in order to balance the transmission needs of each BSS with a view of improving network efficiency. Indeed, if the bandwidth allocated to each of participating APs and its corresponding BSSs is not tracked, spectrum efficiency can drastically decrease. Restrictive communication policy favors very low risks of interference to the detriment of communication efficiency in the second (neighbouring) BSS. On the other hand, too permissive communication policies help having more efficient communication within the BSS, but with the downside of higher risks of interference with the overlapping BSSs. In embodiments, the second AP (through the OBSS TWT element) forbids the STAs of the neighbouring BSS to access the medium during the OBSS R-TWT SPs. In other embodiments, the second AP (through the OBSS TWT element) adjusts the EDCA parameters of the neighbouring BSS to penalize the medium access mechanism of all STAs of the neighbouring BSS. For instance, it triggers the use of a dedicated OBSS EDCA Parameter set, e.g., provided by the neighbouring AP, which set decreased (i.e., degraded) medium access performance. In yet other embodiments, the second AP (through the OBSS TWT element) indicates a temporary operating channel modifications for STAs of the neighbouring BSS, e.g a channel switch announcement, Dynamic Subchannel Operation (DSO), Non-Primary Channel Access (NPCA). Figure 2a illustrates, using a flowchart, general steps of a communication method providing TWT coordination in MAP operation according to embodiments. The communication method takes place at an AP of the MAP coordination set which is a neighbour of a first AP of the MAP coordination set. It is assumed that the first AP, e.g., AP1 of BSS1 in Figure 1, has set up a TWT or R-TWT schedule in its own “first” BSS, which requires TWT coordination with the other BSSs of the MAP coordination set in order to “protect” the TWT schedule. The process of Figure 2a can be performed by any AP neighbouring the first AP. Traditionally, the Broadcast TWT operation allows the first AP to set up a shared TWT session for a group of stations within its BSS, and to periodically specify the TWT parameters set within the beacon frames it broadcasts. The stations of a TWT Broadcast agreement are required to wake up to receive only the beacon frames containing instructions for the TWT Broadcast sessions they belong to. The AP may advertise existing TWT Broadcast agreements so that the stations may ask membership to existing TWT sessions, or send requests to create new ones, as explained above. The first AP, AP1, may decide to share this information about its TWT schedule or schedules to the other (neighbouring) APs of the MAP coordination set. In the description below, the first AP and its corresponding first BSS may also be referred to as “target AP” and “target BSS” respectively. In the same way, the other AP and corresponding BSS may be referred to second or “neighbouring AP” and second or “neighbouring BSS”. Hence, at step 200, the target (first) AP exchanges, with the neighbouring AP, information about the TWT schedule provided in the target (first) BSS. The neighbouring AP of the MAP coordination set can receive a MAP coordination frame including the information about the TWT schedule. The neighbouring AP that receives TWT scheduling information experiences BSS interference with the target BSS. The neighbouring AP may be for example AP2 of BSS2 in Figure 1. The scheduling information may be carried in a TWT element which extends the TWT element defined in the IEEE P802.11 be / D7.0 standard, as shown in Figures 3 and 4. TWT element 300 is identified by Element ID 301 and comprises “Control” field 310 and field 320 for conveying TWT parameter information. “Control” field 310 informs, through Negotiation Type field 311, whether the TWT is a broadcast TWT agreement or an individual TWT agreement. The MSB of the Negotiation Type subfield 311 is the Broadcast field, therefore the TWT element 300 is referred to as Broadcast TWT element when MSB of subfield 311 is 1 (otherwise it is a single Individual TWT element). Other fields are of less importance for present description, unless described below. “TWT Parameter Information” field 320 contains a single ‘Individual TWT Parameter Set’ field if it concerns an individual TWT agreement (not illustrated), or one or more ‘Broadcast TWT Parameter Set’ fields having format 320a if it concerns a Broadcast TWT agreement (when Broadcast field of the “Negotiation Type” subfield is 1). First field in “Broadcast TWT Parameter Set” field 320a is Request Type field 330 comprising: TWT Request subfield 331 set to 1 when issued by the TWT scheduled STA. Otherwise, set to 0 when issued by the TWT scheduling STA (AP); TWT Setup Command subfield 332 to indicate the type of TWT command: Request, Suggest, Demand, Reject when issued by a non-AP STA; or Accept, Alternate, Dictate, Reject when issued by a TWT scheduling AP; Trigger field 333 to indicate whether or not the TWT SP indicated by the TWT element 300 includes triggering frames (the Trigger subfield equals to 1 for trigger-enabled R-TWT). Such a TWT SP is named triggered-enabled TWT SP, and a non-AP station cannot start transmitting data within it without previous triggering by the AP; Broadcast TWT Recommendation field 336 set to 4 to indicate the TWT described in Broadcast TWT element 300 is a restricted TWT (r-TWT). In that case, Broadcast TWT element 300 is also referred to as a restricted TWT element (r-TWT IE), while Broadcast TWT Parameter Set 320a is referred to as Restricted TWT Parameter Set. Other subfields of Request Type field 330 are of less importance: Last Broadcast Parameter Set subfield 334 is set to 0 to indicate that another Broadcast TWT Parameter set follows this set. The Last Broadcast Parameter Set subfield is set to 1 to indicate that this is the last broadcast TWT Parameter set in the broadcast TWT element; Flow Type subfield 335 indicates whether the TWT is announced (the TWT scheduling AP will wait for receiving a frame from TWT scheduled STA to signal its awake state) or not (Flow Type subfield equals to 0 for r-TWT, for “announced” mode, because r-TWT is a trigger-enabled TWT); TWT Wake Interval Exponent subfield 337; and Reserved subfield 338. Other fields in Restricted TWT Parameter Set field 320a are used to define time Parameters for the R-TWT schedule, as follows: Target Wake Time (TWT) field 340 indicates the next time (in microseconds) at which the station participating in the R-TWT schedule should wake up for the next R-TWT SP; Nominal Minimum TWT Wake Duration field 350 indicates the minimum amount of time that the TWT scheduled STA is expected to be awake since the starting time of the TWT SP in order to complete the frame exchanges for the period of TWT Wake Interval. The TWT Wake Interval of the R-TWT SP is the value calculated from the TWT Wake Interval Mantissa 360 and TWT Wake Interval Exponent 337. It is expressed in number of units as defined in Wake Duration Unit subfield 312 of Control field 310, e.g., typically 256 ps. Other fields in Restricted TWT Parameter Set field 320a according to the IEEE P802.11 be / D7.0 standard are used to define parameters specific to the Broadcast and Restricted nature of the R-TWT SP. As to Broadcast TWT Info field 370, it conveys the identifier of the R-TWT schedule, namely the Broadcast TWT ID 373 (bTWT ID), that is used to identify the R-TWT SPs belonging to the same R-TWT schedule. This identifier, which is not 0, hence allows an AP to schedule multiple sets of Broadcast TWT SPs with different sets of TWT parameters; it specifies, through Broadcast TWT Persistence subfield 374, the number of Target Beacon Transmission Times (TBTT) during which the Broadcast TWT SPs corresponding to this Restricted (more generally Broadcast) TWT Parameter set are present; it also signals, through Restricted TWT Schedule Full subfield 372, when set to 1, that the r-TWT scheduling AP is unlikely to accept a request from a STA in the BSS to establish a new membership in the corresponding schedule (identified by bTWT ID 373); finally, it also signals, through Restricted TWT Traffic Info Present field 371, whether Restricted TWT Traffic Info field 380 is present (field 371 to 1) or not. As to Restricted TWT Traffic Info field 380 specific to the restriction of the Broadcast TWT to specific traffics, it is mandatory (hence field 371 is mandatorily set to 1) when the broadcast TWT is related to a LL (low latency) stream (the Traffic Info is related to TIDs). It comprises the following fields: Traffic Info Control field 381 that indicates whether the following fields 382 and 383 are provided (i.e., “valid”). DL TID Bitmap Valid subfield 3811 (respectively UL TID Bitmap Valid subfield 3812) indicates whether the Restricted TWT DL TID Bitmap field 382 (respectively Restricted TWT UL TID Bitmap field 383) has valid information. Subfield 3813 is reserved. Restricted TWT DL TID Bitmap field 382 (respectively Restricted TWT UL TID Bitmap field 383) that identifies TIDs as latency sensitive traffic for DL (respectively UL) directions, i.e., TIDs that are allowed in the R-TWT defined by Restricted TWT element 300. The TIDs may be those defining LL streams. A value of 1 at bit position k in the bitmap indicates that TID k is classified as latency sensitive traffic stream for the concerned transmission direction. Such TWT element (as described up to now) corresponds to the TWT element of the IEEE P802.11be / D7.0 standard. It is enough for the target AP to inform any neighbouring AP about the TWT schedule set in the target BSS. As shown in the Figure, the TWT element is extended with the additional OBSS TWT Info field 390 for the target AP to provide more information items for the neighbouring AP to design (i.e., configure) the OBSS TWT schedule. Figure 4 illustrates an exemplary implementation of the OBSS TWT Info field 390 showing five information items provided in OBSS TWT Info field 390: BSS BSR subfield 392, LL bitmap 393, Nbr Splitted TWT SP subfield 394, Reverse OBSS TWT subfield 395 and OBSS EDCA Parameter Set 396. Alternatively, only a part of them can be provided: any subfield 392 to 395 can be provided alone, or a combination thereof can be provided. Subfield 396 can be omitted when the TWT element 300 is transmitted to another AP (for MAP coordination), whereas subfield 396 can be used by a (neighbouring) AP informing its associated non-AP station about the OBSS TWT schedule (as described below). OBSS TWT info field 390 contains the following information: Info control field 391 allowing to detect the presence or not of one or more of subfields 392 to 396. Each of bits 3911 to 3915 signals the presence or not of respective subfields 392 to 396, BSS BSR subfield 392 reporting an amount of data to be exchanged within the target BSS. Hence, it reports the amount of data (e.g., per access categories (AC)) known by the target AP that are already ready for transmission. It may include data ready for transmission from the target AP itself and, optionally, also for transmission from all associated STAs of the target BSS. The format of the BSS BSR may be similar to the BSR control field as described in section 9.2.4.7.4 of the IEEE P802.11-REVme / D7.0. It is made of the following subfields: ACI Bitmap, Delta TID, ACI High, Scaling Factor, Queue Size High, Queue Size All. Such information from the target AP may be used by the neighboring AP to adjust a length of the service periods of the OBSS TWT schedule, or negotiate the length with the target AP, optionally together with a length of the SPs of the TWT schedule in the target BSS. It may also be used by the neighboring AP to adjust a medium access policy in the target BSS during the SPs of the OBSS TWT schedule, LL bitmap subfield 393 reporting one or more prioritized TID in the first BSS. For example, it is an 8-bit bitmap for the eight TIDs. Each bit indicates whether data traffic of the corresponding TID (equal to bit position in the bitmap) contains low-latency data. It means that the data corresponding to the ‘enabled’ TID (bit set to 1) should be delivered as soon as possible within the target BSS. Such information may be used by the neighboring AP to degrade medium access of its associated STAs (e.g., through degraded EDCA parameters) during the OBSS TWT SP for the corresponding TID associated with an access category, hence favoring transmission within the target BSS for this TID. With this LL bitmap field, OBSS R-TWT is reserved for low-latency flows, especially in high-collided environment. Nbr splitted TWT SPs field 394 indicating a SP splitting scheme of the target TWT SPs which reports a breakdown of the TWT SP within a Beacon interval of the target BSS. For example, it indicates the number of subparts splitting the SPs in each Beacon interval. In embodiments, the SP is divided into equal-length sub-SPs during the Beacon interval. It means that the date of each sub-SPs is equally distributed inside the Beacon interval. In other embodiments, the length of each subpart may be precisely defined (in additional subfields of OBSS TWT Info field 390 - not shown). Splitting a SP advantageously provides frequent medium accesses (opportunities) for low-latency data flows, hence minimizing the medium access time. This information may be used by the neighboring AP to align the sub-SPs within its OBSS TWT schedule to the sub-SPs of the TWT schedule in the target BSS, Reverse OBSS TWT subfield 395 conveying a reciprocal OBSS TWT indication reporting an agreement of the target AP to provide an OBSS TWT schedule in the target BSS timely aligned with a TWT schedule that the neighbouring AP desires to set in its neighbouring BSS. In other words, it indicates that the target AP agrees to create an OBSS TWT schedule in its own BSS (if necessary) should the neighbouring AP requires such compensation. In embodiments, this indication is valid if the TWT Setup Command subfield 332 ofthe TWT element 300 is Request, Suggest or Demand, OBSS EDCA Parameter Set 396 indicating one or more EDCA parameters (usually degraded) to be used during the OBSS TWT SPs. It may include an entire set of parameters. The target AP may suggest some EDCA parameters to the neighbouring AP using subfield 396. However, this subfield may be omitted in the MAP coordination frame from the target AP to the neighbouring AP. More globally, all previous parameters are useful to ensure a global fairness among the APs and corresponding BSSs. If the bandwidth allocated to each of participating APs and its corresponding BSSs is not tracked, spectrum efficiency is drastically decreased. Once the MAP coordination frame including the TWT element 300 for the TWT schedule of target BSS is received by the neighbouring AP, the neighbouring AP performs (optionally) a clock mapping ofthe timing information included in the received TWT information, at step 210. Indeed, in practice, the TWT time fields shared by the target AP are expressed using a time or clock reference that is specific to that target AP (AP1) and known by the target BSS only. The TWT time fields are therefore not linked at all with any time or clock reference used by the neighbouring AP (AP2). For instance, the target AP sending a beacon frame (conveying a TWT element for example) sets the value of the beacon frame’s timestamp to a value of its local Time Synchronization Function (TSF) timer corresponding to the time when the data symbol containing the first bit of the timestamp is transmitted to the PHY plus the target AP’s delays required for the path through its local PHY from the MAC-PHY interface to its interface with the wireless medium (WM). Therefore, at step 210, the neighbouring AP converts timing information of the received TWT schedule in the target BSS that is based on a first clock (or time reference) applicable to the target BSS, into timing information based on a second clock (or time reference) applicable to the neighbouring BSS. When multiple OBSS R-TWT SPs are established among all BSSs, it is very difficult to avoid overlapping SPs. It means that this OBSS R-TWT mechanism should be applied between a low number of BSSs to minimize the impact on the medium access. Main field concerned by such time conversion includes the Target Wake Time (TWT - as field 340). For the neighbouring AP to have knowledge ofthe time shift (or TSF offset) between the two clocks (and then to determine that time shift for time correction / conversion), the target AP may advertise a TSF timestamp in the TWT element 300 it sends to the neighbouring AP within the MAP coordination frame. For example, the TSF timestamp may be provided as an additional subfield (not shown) within Restricted TWT Traffic Info field 380 or within OBSS TWT Info field 390. Alternatively (not represented), the target AP may advertise a time standard by transmitting a Timing Advertisement element in TWT-conveying frames (Time Advertisement element is described in section 9.4.2.59 of IEEE P802.11REVme / D7.0), such as the MAP coordination frame, including the frames exchanges during any negotiation (described below). This element may describe the source of time corresponding to the time standard, and an estimate of the offset between that time standard and the indicated TSF timer (timestamp) provided in the MAP coordination frame. This Time Advertisement element may be included as an additional subfield in TWT element 300 within Restricted TWT Traffic Info field 380 or within OBSS TWT Info field 390. In other embodiments where the two APs are directly connected through a backhaul (e.g., Ethernet backhaul), step 210 can be avoided as there may exist a Cross-AP synchronization by synchronizing the APs via the LAN (Local Area Network) formed by the backhaul. Once the time shift (TSF offset) in between the two BSSs is determined, the time characteristics of an OBSS TWT schedule within the neighbouring BSS (BSS2) to protect the TWT schedule of the target BSS (BSS1) are known, in particular the TWT timing information expressed using the clock reference of the target BSS. As mentioned above, the OBSS TWT schedule aims at defining OBSS TWT SPs that are preferably aligned with, or overlap (either fully or partially over the beginning of), the TWT SPs of the target BSS. With this knowledge, the neighbouring AP verifies, at step 220, whether the OBSS information meets the needs of its BSS, e.g., whether it complies with existing reserved periods of the neighbouring BSS. Indeed, the neighbouring AP may not impose limited communication policies within its BSS during service periods dedicated to intensive communication for its BSS, in particular with respect to low latency data traffic (for R-TWT scheduled in that neighbouring BSS). For example, the second AP checks whether the first TWT SPs (of the TWT scheduled in the target BSS) do not overlap TWT SPs initially scheduled by the neighbouring AP within the neighbouring BSS. To do so, the neighbouring AP determines whether the TWT parameters (starting time point and end time point) obtained from the MAP coordination frame (after conversion if needed) from the target AP do not encompass any period scheduled by the neighbouring AP in its own BSS. Such period may typically be any TWT service period already scheduled in the neighbouring BSS or similar period that favors communication with the neighbouring BSS. In other embodiments, the neighbouring AP may use the timing of the TWT SPs of the TWT scheduled in the target BSS to set up or modify the setting of its own TWT SPs within its neighbouring BSS. In yet other embodiments, the neighbouring AP may use the information items 392 to 396 to negotiate the TWT schedule of the target BSS in order to have an acceptable impact on the communications in the neighbouring BSS. Exemplary negotiations, including a negotiation of the length of the SPs, of the medium access policies (including the OBSS EDCA parameters) are described below. The MAP coordination may be accepted by the neighbouring AP in a case where no interference between scheduled periods is detected. Hence, the neighbouring AP may send (step 230), to the target AP, a positive response in case of no overlapping (positive check); otherwise send a negative response to the target AP. The response may be a TWT Response frame with an Accept (or Refusal) code. In case of refusal, the process stops. In first embodiments, the TWT element 300 is transmitted by the target AP within its own target BSS to announce the TWT schedule. The neighbouring APs can receive the TWT element 300 even if not associated with the target BSS, hence they are aware of the TWT schedule and the additional information items (in the OBSS TWT Info field 390). The target AP, AP1 in the example, regularly informs the stations of its target BSS, BSS1, about the TWT schedule by including such TWT element 300 in Beacon frames it broadcasts in its BSS. In this situation, the MAP coordination frame is a beacon frame broadcast by the first (target) AP within the first (target) BSS. In particular, the TWT schedule information received by the second (neighbouring) AP is defined by the TWT element addressed to stations of the first (target) BSS within the beacon frame. Of course, any type of IEEE802.11 frame may be used to convey the TWT element 300 from target AP AP1 to neighbouring AP AP2. These could be actions frame specific to a MAP scheme which are exchanged in single-user mode between both APs, as shown, for illustrative purposes, by references 560 and 561 in Figure 5. The 802.11 frames may be exchanged over the wireless medium shared between BSS1 and BSS2, or exchanged over another (wireless or wired) medium, such as an Ethernet backhaul built as an off-link or separate network between the two APs. In this scenario (first embodiments), the neighbouring AP may not have to respond to the target AP or to negotiate. Therefore, the neighbouring AP takes the TWT schedule information as it is to design / configure the OBSS TWT schedule in its neighbouring BSS. This is described below. At best, the neighbouring AP merely acknowledges the TWT element 300 received, by sending a TWT Response frame (step 230). In second embodiments, the MAP coordination frame is included in a negotiation process between the target and neighbouring APs to agree on a length of the SPs of the TWT schedule in the target BSS, as well as on a length of the SPs of the OBSS TWT schedule in the neighbouring BSS, and optionally on a medium access policy (e.g., OBSS EDCA parameters). Indeed, the scheduling information of the TWT schedule as provided in the TWT element 300 may not be satisfactory to the neighbouring AP, given activity in its neighbouring BSS. A negotiation phase is conducted between the two APs in which the target AP (AP1) and the neighbouring AP (AP2) agree on a minimum set of parameters related to the TWT schedule, hence to the OBSS TWT schedule (that should be aligned with the TWT schedule). In embodiments where BSS BSR subfield 392 is present, the neighboring AP compares its own BSS BSR with the values provided in BSS BSR subfield 392. This comparison is useful to maintain fairness between the target AP and the neighboring AP. The result may be different for each access category depending on the Queue size of each access category. The length in time of the OBSS TWT SP that the neighbouring AP can afford may be computed based on the total number of the Queue size of each access category contained in the BSS BSR subfield associated with the MCS (Modulation Coding scheme) usually used within the target BSS. The MCS defines the coding rate and the associated throughput. By comparing the total amount of data to be transmitted within the target BSS and the total amount of data to be transmitted within the neighbouring BSS, the neighbouring AP can adjust the desired length of its OBSS TWT SPs. The neighboring AP can then respond (step 230) to the target AP with a proposed alternative TWT schedule, including an updated SP length (e.g., reduced compared to the one in TWT element 300 as defined through Nominal Minimum TWT Wake Duration field 350) The responding frame from the neighboring AP can then include another TWT element 300 specifying the desired characteristics for the TWT schedule in the target BSS. The neighbouring AP may send, to the target AP, a MAP coordination frame containing a TWT element with the TWT Setup Command subfield 332 of the TWT element set to Alternate and with the Nominal Minimum TWT Wake Duration subfield 350 set to the desired value different from the value provided by the target AP. The results of the BSS BSR comparison can also be used to negotiate others TWT parameters with the target AP by providing others values for instance for the Restricted TWT Traffic info subfield 380 (specifying the TIDs that are prioritized during the TWT SP). In other embodiments (in variants or in combination), the neighbouring AP can negotiate the low latency TID, based on LL Bitmap subfield 393. In yet other embodiments (in variants or in combination), the neighbouring AP can negotiate a SP splitting scheme for the TWT schedule in the target BSS, using Nbr Splitted TWT SPs subfield 394. In yet other embodiments (in variants or in combination), the neighbouring AP can request reciprocity of TWT protection by the target AP, based on the indication provided in Reverse OBSS TWT subfield 394. For example, if subfield 394 is set to 1 (the target AP is ready to set an OBSS TWT schedule to protect a TWT schedule in the neighbouring BSS), the neighbouring AP designs, sets or configures a second TWT schedule in the neighbouring BSS and sends a MAP coordination frame to the target AP for the latter to set the corresponding second OBSS TWT schedule in the target BSS. The MAP configuration frame contains a TWT element 300 with the TWT Setup Command subfield 332 of the TWT element set to Accept and all the other subfields of the TWT element 300 defines parameters of the second OBSS TWT schedule to be created in the target BSS of the target AP. When the second OBSS TWT schedule is made (confirmation received from the target AP), the neighbouring AP may make the OBSS TWT schedule effective in the neighbouring BSS. If subfield 394 is set to 0 (the target AP has not declared to be ready to set an OBSS TWT schedule to protect a TWT schedule in the neighbouring BSS), the neighbouring AP may ask the target AP for a second OBSS TWT to be created in the target BSS to ensure the fairness. This may be done by sending a MAP coordination frame including a TWT element 300, with a TWT Setup Command subfield 332 of the TWT element set as Accept or Alternate, and Reverse OBSS TWT subfield 394 set to 1. The other subfields of the TWT element 300 defines parameters of the second OBSS TWT schedule to be created in the target BSS of the target AP. Note that in the MAP coordination frame sent by the neighboring AP, the latter may include its own BSS BSR or other fields of the OBSS TWT info field 390 to help the target AP to configure the requested second OBSS TWT SP. The negotiation between the target AP and the neighbouring AP may concern: - the Target Wake Time (TWT - as field 340); - the TWT Wake interval (defined by fields 337 and 360 in relation with field 312); and - the Minimum TWT Wake duration (as field 350). If several TWT SPs have to be protected, hence to be notified in MAP coordination frames, the MAC addresses of the target and neighbouring APs and the bTWT Identifier 373 of a successful TWT MAP setup between those two APs may be used to uniquely identify a TWT MAP agreement. In yet other embodiments (in variants or in combination), the neighbouring AP can negotiate one or more EDCA parameters for the OBSS TWT schedule, based on the proposal provided in OBSS EDCA Parameter Set subfield 395. Again, the neighbouring AP may send back a MAP coordination (response) frame to the target AP, including a TWT element 300 with the counterproposal. A Request and Accept frames is a minimum set of messages exchanged by the two APs. However, multiple pairs of Suggest / Demand and Alternate / Dictate frames may be exchanged before reaching a final MAP agreement for the TWT schedule in the target BSS (and optionally second TWT schedule in the neighbouring BSS), corresponding to a repetition of steps 200 to 230. The negotiation advantageously allows avoiding scheduling concurrent period of activities (TWT SPs) in the two BSSs, i.e., respective TWT schedule that could overlap. The frames exchanged by the two APs during the negotiation can be identified by each of them, as coming from a device outside its own BSS by merely analyzing the MAC frame header. For example, AP2 may identify the MAC address source of a received frame is AP1 MAC address, which does not belong to BSS2. Optionally or alternatively, a SSID can be randomly generated for the MAP coordination set at the time the set is formed, and such exchanged frame can be identified when the SSID used for address 3 of MAC header is not set to BSS2 nor BSS1 but to the randomly generated SSID for the MAP coordination set. Third embodiments are directed to the specific case of MLDs where multiple links exist. In these embodiments, the MAP coordination frame or frames are exchanged between a third AP co-affiliated, as the target AP, with the (same) first AP MLD and a fourth AP co-affiliated, as the neighbouring AP, with the (same) neighbouring AP MLD. Hence the frame or frames are conveyed on a separate link than the link on which the target and neighbouring APs operate and that creates OBSS interference, i.e., it is forwarded from another affiliated AP of the AP1 MLD. The third AP sends the MAP coordination frame on behalf of the target AP experiencing the OBSS interference, while the fourth AP receiving the MAP coordination frame may then forward it to the neighbouring AP, within the neighbouring AP MLD, for the neighbouring AP to conduct the TWT coordination. The reverse path (fourth AP to third AP) is used for the responding frames from the neighbouring AP. This could be the case for 802.11be / bn devices (multi-link capable) according to coverage in wireless bands. For instance, 2.4GHz offers greater coverage than 6GHz. There could then have OBSS interferences in between a subset of stations of two BSSs of a 6GHz band, while the two corresponding APs of two AP MLDs are out of range of each other. In that case, AP1 operating on the 2.4GHz band for the first AP MLD may inform AP2 operating on the same band for the second AP MLD, about such OBSS interference, i.e., the MAP coordination frame informing of the TWT coordination is conveyed on another link than the 6GHz link experiencing the OBSS interference. In this context, frames 560 and 561 (Figure 5) are exchanged on a distinct link, and contain the link identification where the interferences impact the communications. In case of acceptance of the TWT schedule (either imposed by the target AP or negotiated with it), the neighbouring AP next designs, sets, configures, computes or builds, at step 240, an OBSS TWT schedule for its BSS that is adapted to the TWT schedule of the target BSS, i.e., time aligned with it. To do so, it builds an OBSS TWT element. In fact, the neighboring AP can define a new transmission policy to be applied during the OBSS TWT SP depending on the information contained in the OBSS TWT Info field 390 received from the target AP. Two aspects are dealt with at this step. First aspect regards the timing of the OBSS TWT SPs of the OBSS TWT schedule. As mentioned above, they are preferably time aligned with the TWT SPs scheduled in the target BSS. In embodiments, they have the same starting time, meaning the TWT (field 340) is the same, given the determined time shift (TSF offset). Variants may contemplate having OBSS TWT SPs starting a little before the TWT SPs scheduled in the target BSS. The OBSS TWT SPs may have the same length as the TWT SPs scheduled in the target BSS, meaning for example that the Minimum TWT Wake Duration fields are the same. Variants may define a larger or shorter Minimum TWT Wake duration for the OBSS TWT schedule compared to the TWT schedule of the target BSS. In the case of encompassing, the Minimum TWT Wake duration is larger. In the case of overlapping, the Minimum TWT Wake duration may be larger or shorter. The length of the TWT SPs scheduled in the target BSS may be imposed to the neighbouring AP through the TWT element 300 transmitted by the target AP. Alternatively, the length may have been negotiated between the two APs as described above, in particular based on information items 392 to 396. In embodiments where the SPs of the TWT schedule in the target BSS are split (Nbr Splitted TWT SPs subfield 394 not zero), the corresponding SPs of the OBSS TWT schedule in the neighbouring BSS are split using the same splitting scheme (either predefined or specified in the TWT element 300). Second aspect regards the communication activity the neighbouring AP can allow to the stations of its BSS to ensure TWT coordination, i.e., reduced OBSS interference with the target BSS. It is indeed sought to control communication activity of the stations of the neighbouring BSS during the TWT SPs scheduled in the target BSS. In addition, it is expected that the stations of the neighbouring BSS end their transmissions before the starting of the TWT SPs scheduled in the target BSS. The neighbouring AP can then adjusting a medium access policy in the neighbouring BSS during the OBSS TWT SPs, for example based on information items 392 to 396. In first embodiments regarding the second aspect, the neighbouring AP may forbid the stations of the second BSS to access the medium during the second TWT SPs. For example, the comparison between the BSS BSR in subfield 392 (i.e., of the target AP) and the own BSS BSR of the neighbouring AP may conduct the latter to forbid access to the medium during the OBSS TWT schedule. This is to give high priority to the target BSS. Conversely, if the BSRs are more balanced, the neighbouring AP can allow medium access to its associated stations during the OBSS TWT schedule, as described below. In case of medium access prohibition, the neighbouring AP announces a TWT service period where no station of the second BSS can access the medium. It aims at offering a TWT schedule that stations of the BSS cannot try to join, or if they intend, the AP will always refuse. In other words, the TWT schedule may correspond to an idle TWT schedule in which the stations of the BSS cannot participate. Any signalling frame can be used, such as a Beacon frame, that includes an OBSS TWT element having the same format as TWT element 300 of Figure 3, except that OBSS TWT Info field 390 may be omitted. In other words, a conventional (IEEE P802.11be / D7.0 standard) TWT element may be used. A dedicated bTWT ID (373) different from the one of the TWT schedule for the target BSS is used. More generally, the expression “OBSS TWT element” is used below to designate the TWT element 300 that is sent by the neighbouring AP to its associated stations, in contrast to TWT elements exchanged between the target and neighbouring APs. In embodiments, an additional subfield in Traffic Info Control field 381, namely OBSS TWT subfield 3814, may explicitly indicate that the present TWT element 300 is an OBSS TWT element for an OBSS TWT schedule. In that way, the OBSS TWT element is a restricted TWT element having a Restricted TWT Traffic Info section 380 comprising an OBSS TWT field 3814 that is enabled. Turning now to second embodiments regarding the second aspect (communication activity for the stations during the OBSS TWT SPs), the OBSS TWT element announces a TWT service period where the stations of the neighbouring BSS (BSS2) can access the medium with a less aggressive medium access scheme than the first embodiments (i.e., lower priority). It is proposed that the OBSS TWT element defines a waiting time for the stations of the neighbouring BSS to access the medium that is larger than a waiting time for stations of the target BSS to access the medium during the first TWT SPs. The stations of the neighbouring BSS thus take more time to issue a medium access. So, they perform a CCA (channel sensing) during a larger time that lets stations of the target BSS (BSS1) to have priority to access the medium. Increasing the sensing time may be obtained by degrading EDCA parameters at the stations of the neighbouring AP, e.g., a degraded minimum size of a contention window (ECWmin), a degraded arbitration interframe space number (AIFSN) or a dedicated OBSS EDCA Parameter Set (including degraded EDCA parameters) that is additional to the conventional legacy EDCA Parameter Set and multi-user (MU) EDCA Parameter Set. The degraded parameters (AIFSN, ECWmin or even the entire OBSS EDCA Parameter Set) can be sent to the associated stations within the OBSS TWT element, in particular using subfield 396 described above. In variants, they may be transmitted through an OBSS EDCA Parameter Set field in the Beacon or Probe Response frames. In embodiments, the adjusting of the medium access policy (hence of the degraded parameter or parameters) is made based on the comparison between the BSS BSR of the two BSSs. The more data the target BSS has to transmit compared to the neighbouring BSS, the more degraded (to wait longer sensing time) the EDCA parameters are in the neighbouring BSS. For example, the neighboring AP defines a new set of degraded EDCA parameters to be applied during the OBSS TWT SP that will be broadcast to the STAs associated to the neighboring AP. For instance, if the BSS BSR of the target AP contains a higher amount of data frames to be sent for a dedicated access category (AC) than the BSS BSR of the neighboring BSS, the neighboring AP can decide to degrade the EDCA parameters of the corresponding AC inside its own BSS to prioritize the data frames to be sent for the BSS of the target AP. In specific embodiments, a degraded EDCA parameters includes a degraded ECWmin value. The neighboring AP thus forces its stations to statistically wait for a longer time than in a conventional operating mode. This results in less medium access attempts by its stations, hence in less OBSS interference with the first BSS. In other embodiments, a degraded EDCA parameters includes a degraded AIFSN value. The neighboring AP thus drives its stations to wait for a longer time before starting decrementing their backoff counter to gain access to the medium. This results in giving priority for medium access to stations having a lower AIFSN, basically those of the target BSS, hence resulting in less OBSS interference with the first BSS. Penalizing EDCA parameters such as degrading (increasing) only the AIFSN value of the interfering BSS guarantees that the medium access rules in the neighbouring BSS are not too strong, instead of forbidding medium access. It ensures a fairness for the neighbouring AP, especially when the OBSS TWT SP is not fully used by the target AP and its associated stations. The main advantage of this subfield is that low-latency flows may be specifically prioritized, associated with a short OBSS TWT SP. Due to the impact in term of throughput for the neighboring (interfering) BSS, only short OBSS R-TWT SPs should be setup and reserved only for transmitting low latency flows that require precise and periodic medium accesses. In other embodiments (in variants or in combination), where low latency flows are declared (in LL Bitmap subfield 393), it means that the data corresponding to this TID should be delivered as soon as possible in the target BSS. In that case, the neighboring AP can decide to degrade EDCA parameters to be applied during the OBSS TWT SP for the corresponding TID associated with an access category. In yet other embodiments (in variants or in combination), where the SPs of the TWT schedule in the target BSS are split (Nbr Splitted TWT SPs subfield 394 not zero), the neighbouring AP ensures that the controlled activity in its BSS is performed during the sub-SPs of the TWT SP. In other words, the neighbouring AP configures its SP to be split in an aligned fashion with the sub-SPs of the TWT schedule in the target BSS. OBSS EDCA Parameter Set 396 includes EDCA parameters (up to a whole EDCA parameter set) different from a legacy EDCA Parameter Set and a MU EDCA Parameter Set, to be applied by the stations of the neighbouring BSS to contend for access to the medium during the OBSS TWT SPs. The neighbouring AP can then drive the waiting time of its stations by adjusting the EDCA parameters of the OBSS EDCA Parameter Set. It also means that those stations have to use this specific set of parameters upon each new OBSS TWT SP starting and to switch back to the legacy EDCA Parameter Set upon the OBSS TWT SP ending or upon a dedicated timer elapsing. The presence of the OBSS EDCA Parameter Set field is signaled through a dedicated 1 -bit field (EDCA Param Valid 3915) of Traffic Info Control field 391. OBSS EDCA Parameter Set 396 thus provides information needed by the stations for proper operation of medium access during the OBSS TWT SP embedding this OBSS TWT element. In other words, for an infrastructure BSS such as BSS2, the OBSS EDCA Parameter Set element is used by AP2 to establish policy (by changing default MIB attribute values), to change policies when member stations (STA21, STA22, STA23) perform medium access. Various embodiments of OBSS EDCA Parameter Set 396 are depicted. First embodiments corresponding to format 396a reuse the legacy format for the EDCA Parameter Set element, as follows. The QoS Info and Update EDCA Info fields are reserved (not used). The formats of AC_BE, AC_BK, AC_VI, and AC_VO Parameter Record fields 430 are the conventional ones. ACI / AIFSN subfield 431 typically contains an ACI subfield and AIFSN subfield. The value of the AC index (ACI) references the AC to which all parameters in this record correspond. The AIFSN subfield indicates the number of slots after a SIFS a STA defers before either invoking a backoff or starting a transmission. AIFSN stands for “Arbitration InterFrame Space Number”. ECWmin / ECWmax subfields 432 encode the values of CWmin and CWmax, respectively, in an exponent form. ECW stands for “EDCA Contention Window”. The TXOP Limit field 433 shall not be specified as a TWT SP is considered. Thus, a TXOP Limit field set to 0 (that has a special meaning) can be used. In embodiments seeking to provide less aggressive medium access than pure prohibition, one may envisage using a greater ECWmin than the default one in the BSS. Hence, the OBSS EDCA Parameter Set includes a degraded ECWmin value. In other embodiments still seeking to provide less aggressive medium access, the AIFSN value may be adjusted (basically increased) to delay the backoff decrement by the stations of the neighbouring BSS, hence to delay any medium access. In that case, the OBSS EDCA Parameter Set includes a degraded AIFSN value. Second embodiments corresponding to format 396b reuse the known format of the MU EDCA Parameter Set element. While the conventional MU EDCA Parameter Set element is used by an AP to control the use of EDCA by non-AP 802.11be / HE stations following particular UL MU HE TB PPDU transmissions, it is proposed for the neighouring AP to use it in order to control the use of EDCA by its non-AP stations inside a particular OBSS TWT SP. The element is used as follows. The QoS Info field is reserved (not used). The formats of MU AC_BE, MU AC_BK, MU AC_VI, and MU AC_VO Parameter Record fields 440 are the conventional ones. Each field element 440 contains the same subfields ACI / AIFSN 431 and ECWmin / ECWmax 432, plus a MU EDCA Timer subfield 443. The MU EDCA Timer field shall be set to value 0 as reserved. Subfields ACI / AIFSN 431 and ECWmin / ECWmax 432 are described above and may carry a degraded ECWmin value and / or a degraded AIFSN value. However, in some embodiments, a timer defined by this field 443 may be used to drive the stations of the neighbouring BSS to switch back from the OBSS EDCA Parameter Set to the legacy EDCA Parameter Set. This is to restore the legacy parameters once the OBSS TWT SP protecting a TWT SP scheduled in the target BSS has ended. In these embodiments, the OBSS EDCA Parameter Set includes an OBSS EDCA Timer indicating a duration of time during which the stations of the neighbouring BSS use OBSS EDCA parameters before switching back to legacy EDCA parameters. The MU EDCA Timer field 443 indicates the duration of time, in units of 8 TUs, during which the stations use the OBSS EDCA parameters for the corresponding AC. Each TU may be defined by Wake Duration Unit field 312. In these embodiments, the stations of the neighbouring BSS may implement an independent backoff procedure during the OBSS TWT SP to control medium access based on the parameters of the OBSS EDCA Parameter Set. Third embodiments corresponding to format 396c reuse ACI / AIFSN field 431 alone as forming the OBSS EDCA Parameter Set 396. In that field, only the AIFSN subfield may be significant (ACI subfield is not used) to indicate the number of slots after a SIFS a station defers before either invoking a backoff or starting a transmission. The indicated AIFSN value applies to all ACs during the OBSS TWT SP. In any of these embodiments, the AIFSN value may be used alone to defer invocation of the backoff decrement. In a variant, the AIFSN value may define additional slots that the station adds to the legacy EDCA AIFSN value of each AC category, to defer such invocation. In other words, the degraded AIFSN value (specified in field 431) is to be added to a legacy AIFSN value (e.g., defined in the legacy EDCA Parameter Set) by the stations of the neighbouring BSS to obtain an AIFSN value to be applied when contending for access to the medium during the OBSS TWT SPs. The neighbouring AP has to determine the minimum value of the AIFSN subfield(s) whatever the embodiment. In some embodiments, a minimum value of the AIFSN subfield 431 can be set to 2, in particular when added to the legacy AIFSN value. This value provides a shift in medium access slot countdown in favor of the target BSS (BSS1): each AC queue of the stations in the neighbouring BSS (BSS2) is shifted two slots later compared to the target BSS. In other embodiments, a minimum value of the AIFSN subfield 431 can be set to the maximum AIFSN value used by the stations of the target BSS (BSS1). As an example, a default value for AC_BK may be set to 7. This allows to prioritize all queues from the target BSS (BSS1) compared to the highest priority queue in the neighbouring BSS (BSS2). Of course, larger values can also be envisaged. They can ensure medium access is always granted to the stations of the target BSS. As an example, the Minimum TWT Wake Duration (as in field 350) provided in the MAP coordination frame can be considered for aligning an AIFSN close to this delay. In that case, the waiting time is specified in the MAP coordination frame, and the waiting time is set to a duration of the TWT SPs scheduled in the target BSS or set to the negotiated Minimum TWT Wake Duration. In embodiments, OBSS TWT Info field 390 includes only Info Control field 391 and OBSS EDCA Parameter Set field 396. Info Control field 391 includes only EDCA ParamValid subfield 3915 (in addition to reserved bits). Although the embodiments above provide the OBSS EDCA Parameter Set (396) within the OBSS TWT element 300, variants may contemplate providing such Parameter Set in the beacon frames periodically broadcast by the neighbouring AP. Should different OBSS EDCA Parameter Sets be used for different OBSS TWT schedules of the neighbouring BSS, the OBSS EDCA Parameter Sets may be provided in the beacon frames in association with the bTWT ID of the respective OBSS TWT schedule. In these variants, it turns out that the AP broadcasts various EDCA Parameter sets. Back to Figure 2a, once the OBSS TWT element 300 has been prepared at step 240, the neighbouring AP (AP2) sends, to associated stations of its BSS, a frame including the OBSS TWT element 300 which defines OBSS TWT SPs aligned or overlapping with the TWT SPs scheduled in the target BSS (BSS1), This is step 250 corresponding to the announcement of the OBSS TWT schedule in the neighbouring BSS. In some embodiments, the frame including the OBSS TWT element is a beacon frame broadcast by the neighbouring AP in the neighbouring BSS. Hence all the stations of that BSS can receive the OBSS TWT schedule and then can be limited in their communication activity during the OBSS TWT SPs. These beacon-based embodiments allow the neighbouring AP to periodically specify the TWT parameters set. In alternative embodiments, the frame including the OBSS TWT element is a probe response frame sent by the neighbouring AP in the neighbouring BSS. Although that probe response frame can be broadcast to all stations of the BSS, it can also be addressed to a specific subset thereof. This probe-based approach allows the neighbouring AP to specify more rapidly the OBSS TWT schedule and the OBSS TWT Parameter Set (in advance to the next TBTT) compared to the beacon frame. Hence, decision for the neighbouring AP to use the conventional beacon frame or a probe response frame can be based on the starting time of the next OBSS TWT SP. In particular, a Probe Response frame including the OBSS TWT parameters is preferably emitted if the starting time of the next OBSS TWT SP is scheduled prior to the next TBTT (beacon frame). Although the neighbouring AP can send the OBSS TWT element to all its associated stations, hence limiting the communication activity of all these stations during the OBSS TWT SPs, there are situations where such limitation is excessive. This is the case for instance for those stations that are far enough from the target BSS so they cannot generate OBSS interference with the target BSS. It would be worth having these stations keeping their entire communication activity during the OBSS TWT SPs, although other stations of the same neighbouring BSS are limited in their communication activity. The neighbouring AP may then try to make those interfering stations joining the OBSS TWT schedule. In this respect, the neighbouring AP (AP2) may first obtain information about interfering stations of its BSS (BSS2) that are interfering with the target BSS (BSS1) and free (or not interfering) stations of its BSS that are not interfering with the target BSS. Next, the neighbouring AP may decide to send the OBSS TWT element to the interfering stations only. This may be done using individually-addressed probe response frames or individually-addressed TWT Setup frames with a command value of TWT Grouping (not shown in the Figures) in the TWT Setup Command field 332 and with the TWT Request field 331 equal to 0 (transmitting AP is a TWT scheduling station). As a result, the OBSS TWT element limits communication activity over the medium for the interfering stations only. In above embodiments, the neighbouring AP obtains or negotiates with the target AP, TWT schedule information in order to adjust its (i.e., of its BSS) communication operations during the OBSS TWT SPs on the shared medium to reduce risks of OBSS interference. In other embodiments, the communication activity for the stations of the neighbouring BSS during the OBSS TWT SPs may be off-loaded to a distinct channel from the shared medium / channel In that case, the OBSS TWT element may include a channel (or list of) indication along with the optional OBSS EDCA Parameter Set providing the parameters for the stations to limit their communication activity during the OBSS TWT SPs. In other words, the OBSS TWT element may announce a TWT service period where the stations of the neighbouring BSS (BSS2) can access the medium but over another channel, different from the operating channel initially in use by stations of the neighbouring BSS. Thus, instead of stopping or reducing access to the medium by the stations of the neighbouring BSS according to above embodiments, communications can be maintained while preventing interference with the target BSS during the first TWT SP. The channel initially in use by stations is the “initial operating channel” and the other channel where to switch is the “second channel” or “temporary operating channel”. The initial operating channel is usually the primary channel of the BSSs (channel over which beacon frames are exchanged), but may also be a secondary channel. Therefore, a channel switch is attempted to move the BSS2 to the temporary operating channel. The decision to switch to a new operating channel in an infrastructure BSS is made by the neighbouring AP of the neighbouring BSS. The neighbouring AP may make use of the information in Supported Channels elements and the results of measurements undertaken by the neighbouring AP and other STAs in the neighbouring BSS to assist the selection of the new channel. The Supported Channels information element, according to IEEE802.11 series of standards, describes sub-bands that are supported by a station (it consists of a first channel number, which is the lowest channel in a supported sub-band, followed by the number of channels in the sub-band). Generally, a channel switch is used very rarely by an AP. In complement, the neighbouring AP may make use of the information in Supported Channels elements provided by other APs of the MAP coordination group (such as the target AP). The negotiation of an elected channel among the supported channels may be provided by frame exchanges 560 / 561, wherein each AP (here AP1 or AP2) exchanges information about at least one second channel used for channel switching during an OBSS TWT. For example, the TWT element 300 received from the target AP with channel information for the off-load. The channel information may concern the information in Supported Channels elements advertised by the target AP for its BSS (through its emitted management frames like beacon frames). In a variant or in addition, the channel information may concern the information of interfered channels in results of measurements undertaken by the AP and other STAs in the target AP’s BSS, In a variant or in addition, the channel information may concern the information of negotiated channel (or list of) as a result of channel allocation for OBSS TWT within the MAP set. In response, the neighbouring AP attempts to select a second channel that is supported by all associated STAs of the neighbouring BSS and that is compliant with the received channel information from the target AP. In other words, the neighbouring AP determines if a channel can be accommodated locally compared to a received list of channels. If a channel can be accommodated, it is selected as second (or temporary) channel. The channel is then announced to the neighbouring BSS through a dedicated frame additional to the one conveying the OBSS TWT element, or directly in the OBSS TWT element, during step 250. At least three exemplary mechanisms to announce a channel switch information (CSA, Channel Switch Announcement) can be envisaged: using Channel Switch Announcement frames (or equivalent - as defined in section 9.6.2.6 or section 9.6.7.7 of the IEEE P802.11-REVme / D7.0 standard) until the intended channel switch time. For example, the Channel Switch Mode field indicates any restrictions on transmission until a channel switch. The New Channel Number field identifies the second (temporary) 20 MHz channel where to operate after the switch. The Channel Switch Count field indicates the number of target beacon transmission times (TBTTs) until the AP sending the frame switches to the new (temporary) channel; using Channel Switch Announcement elements (or equivalent - as defined in section 9.4.2.17 of the IEEE P802.11-REVme / D7.0 standard) in Beacon frames or Probe Response frames. For example, the Channel Switch Mode field indicates any restrictions on transmission until a channel switch. The New Channel Number field is set to the number of the channel to which the STA is moving. The Switch Time field indicates the maximum time delta between the TBTT of the last Beacon frame transmitted by the AP in the current channel and the switching date; using a combination of Channel switch information and OBSS TWT schedule. For example, a Target Channel field may be provided as a new subfield in OBSS TWT Info field 390 or in Restricted TWT Traffic Info field 380. The Target Channel field indicates a channel number for second channel operation during OBSS TWT SP, which is interpreted in the context of the BSS operating class. Channel numbers are defined in IEEE P802.11 REVme / D7.0 standard Annex E. Optionally, an Operating Bandwidth field allows indicating an operating bandwidth greater than 20 MHz. Turning now to the stations of the neighbouring BSS (BSS2), Figure 2b illustrates, using a flowchart, general steps, at such a station, of a communication method according to embodiments of the invention. At step 255, a station of BSS2 receives, from its AP (AP2), an OBSS TWT element 300 in a beacon frame or a Probe Response frame. The OBSS TWT element defines an OBSS TWT schedule with OBSS TWT SPs that are aligned or overlapping with TWT SPs (to be protected) scheduled in the target BSS (BSS1). Depending on the embodiments, the OBSS TWT element may include an OBSS EDCA Parameter Set providing the parameters for the station to limit its communication activity during the OBSS TWT SPs. Step 260 consists for the station in waiting the start of the next OBSS TWT SP. In the above first embodiments, the OBSS TWT element 300 indicates that the OBSS TWT schedule is not available for accepting new membership. In that case, the station does not request to establish membership in such OBSS TWT schedule and stays in a doze state (i.e., with no communication activity) during the OBSS TWT SP. In the above second embodiments, the station is authorized to have some transmission activity in the BSS according to restriction or limitation defined in the OBSS TWT element 300 (typically according to the OBSS EDCA Parameter Set). Note that for both cases, the station is expected to stop any transmission activity before an OBSS TWT scheduled SP. In those second embodiments, at step 270, the station applies the parameters of OBSS EDCA Parameter Set 396 advertised by its AP (AP2), if any. As mentioned above, the station may then apply a degraded AIFSN value 431 and / or a degraded ECWmin value 432 and optionally an OBSS EDCA Timer 443, to control the use of EDCA during the OBSS TWT SP. Step 270 thus consists for the station to switch from a legacy EDCA Parameter Set to an OBSS EDCA Parameter Set to contend for access to the medium during one of the OBSS TWT SPs. The switch takes place so that the OBSS EDCA Parameter Set starts to be used when the OBSS TWT SP starts. Step 280 consists for the station in waiting the end of the OBSS TWT SP. At the end of the SP, the legacy EDCA parameters are restored (step 290). To do so, the station switches back (from the OBSS EDCA Parameter Set) to the legacy EDCA Parameter Set. It may be at the end of the OBSS TWT SP, i.e., after an OBSS duration defined by a Minimum TWT Wake Duration field 350 specified in the OBSS TWT element 300. In a variant where the OBSS EDCA Timer 443 is used, it is made when the OBSS EDCA Timer 443 specified in the OBSS TWT element elapses. Next, the station invokes a new (conventional) EDCA backoff procedure. In the embodiments where the communication activity for the stations of the neighbouring BSS is off-loaded to a distinct channel from the shared medium / channel, during the OBSS TWT SPs, an indication of a selected target (second) channel to switch to, and the appropriate timing for the switching, are received by the station from the neighbouring AP, at step 255. Step 260 consists for the station to wait for the start of a next OBSS TWT SP. At step 270, the station (including the neighbouring AP) selects the second channel, and operates the switching. In embodiments applying a restriction or a limitation defined in the OBSS TWT Element 300 (typically according to the OBSS EDCA Parameter Set), the station may conduct backoff procedure for access on the selected channel with provided EDCA parameters (396), or may wait for receiving a frame on this channel (e.g., a Trigger Frame emitted by AP2). Step 280 consists for the station to wait for the end of the OBSS TWT SP. At the end of the SP, the station switches back onto the initial operating channel (step 290). In embodiments, the legacy EDCA parameters are restored. Figure 5 illustrates a transmission sequence implementing a TWT coordination for reduced OBSS interference in MAP operation, according to embodiments of the invention. Although it is described using 802.11 single user frames, it may alternatively use equivalent frames in multi-user operation. The proposed example involves two BSSs in a MAP coordination set, e.g., BSS1 and BSS2 of Figure 1. First, the two APs directly exchange (above step 200) their TWT scheduling information through frames 560 and 561. This may be a negotiation between the two APs. AP1 provides a MAP TWT scheduling, included in MAP coordination frame 560 for example. Once the MAP scheduling negotiation is completed, AP1 and AP2 continue their own operations on their proper BSS. Typically, AP1 sends regular beacon frames 500, at each TBTT1 duration interval. In that example, TBTT1 is shorter than TBTT2 (used by AP2 in its own BSS2). As an alternative or complement to frame exchange 560-561, the MAP TWT scheduling can also be obtained by AP2 directly from beacon frame 500. This is because TWT element 300 is present in such beacon frame for the stations of BSS1. Note that this TWT element may also result from the negotiation 560-561 (if any). Such a TWT element 300 in the beacon frame is usually a broadcast TWT element or a restricted-TWT element (which is a particular broadcast TWT element). In the example of the Figure, beacon frame 500 is sent by AP1 in BSS1 at TO and T4, and indicates the TWT SPs that follow for BSS1: TWT SP 540 and TWT SP 541, each corresponding to timing T1-T2 and T5-T6. TWT SPs 540 and 541 are the period suffering from OBSS interferences with BSS2 and that require protection using a TWT coordination between AP1 and AP2. In BSS2, beacon frame 550 is sent by AP2 at T3. Embodiments of the TWT coordination according to the invention operate as follows. Once the MAP TWT negotiation 560 / 561 is completed, AP2 can determine that first TWT SP 540 (T1-T2) in BSS1 will take place before the next TBTT T3 (i.e., before the beacon frame to be sent). A MAP TWT protection scheme can be provided before T3 by sending Probe Response frame 551 that includes OBSS TWT element 520 informing about the OBSS TWT schedule (and thus SPs) within BSS2. Probe Response frame 551 may be broadcast to reach all stations of BSS2 or may be sent to a specific subset of stations within BSS2, e.g., stations determined as interfering with BSS1. In the example of the Figure, OBSS TWT element 520 announces an OBSS TWT SP 530 (starting time aligned with TWT SP 540) where the stations of BSS2 can access the medium using a degraded medium access scheme, e.g., relying on above-discussed degraded AIFSN value and / or degraded ECWmin value (optionally included in OBSS EDCA Parameter Set 396). As a result, a subset of stations may conduct communication in BSS2 during OBSS TWT SP 530, stations of which the CCA sensing 599 (Minimum TWT Wake Duration 350 as defined in the OBSS TWT element 300) takes more time than for stations of BSS1 in TWT SP 540. This ensures that BSS1 has priority over BSS2 in accessing the medium during scheduled TWT SP 540. In the example, STA22 does not detect any communication activity within its range. As a consequence, it may perform a backoff countdown after CCA sensing period 599 and initiate a transmission if it gains access to the medium. Of course, OBSS TWT element 520 may alternatively announce an OBSS TWT SP where medium access is forbidden to the stations of BSS2. This is for example the case with beacon frame 550 sent by AP2 that includes OBSS TWT element 520 announcing next OBSS TWT SP 531 and specifying medium access is forbidden to the stations of BSS2. In that case, there is no communication at all in BSS2 during OBSS TWT SP 531, hence avoiding any OBSS interference with BSS1 during TWT SP 541. CCA sensing period 599 corresponds to T1-T2’, and could be set so that T2’ can reach T2. For example, Minimum TWT Wake Duration 350 as defined in the OBSS TWT element 300 may be set to Minimum TWT Wake Duration 350 of the TWT SPs within target BSS1, i.e., as defined in the TWT element 300 of the beacon frames 500 transmitted by AP1. This scenario shows that two different communication activity policies are used for OBSS TWT SPs 530 and 531. Of course, one and the same policy (access prohibition or controlled access with waiting time) can be used over multiple OBSS TWT SPs of the same OBSS TWT schedule. Situations may require that AP1 and AP2 update their negotiation 560 / 561 (not shown in the figure). To handle such updates overtime, beacon frames 550 may advise an OBSS TWT Update Counter field to follow the updates, that is associated with an OBSS TWT schedule (e.g., using identifier bTWT ID). OBSS TWT Update counter field may be defined as an unsigned integer initialized to 0 that is incremented each time an update of the OBSS TWT parameters is made. In that case, the stations of BSS2 become aware of any important change in the OBSS TWT schedule and may retrieve the updated parameters from beacon frame 550. The same applies for the embodiments where the communication activity for the stations of the neighbouring BSS is off-loaded to a distinct channel from the shared medium / channel. However, once the channel switch information is received by any station from its AP, it switches to the selected target (second) channel at the appropriate switching time. In embodiments, the switched station may not transmit a frame to its AP on the second channel until it receives a frame on the second channel from the AP. Therefore, AP considers sending first an initial frame when the switching has occurred. Preferably, a trigger frame may be considered to be emitted for triggering stations that have also switched their operating channel. Several mechanisms may be envisaged to apply the channel switch operation, including the BSS Channel switch, but also more recent technologies or protocols such as NonPrimary or Secondary Channel Access (NPCA or SCA) operation, where the primary channel is not operated until sensed as free; Subchannel Selective Transmission (SST) operation (including SST element in Beacon frames); and / or Dynamic Sub-band Operation (DSO). Once the OBSS TWT SP ends, the station switches back to its initial operating channel. Figure 6a schematically illustrates a communication device 600 configured to implement at least one embodiment of the present invention, for instance any of the (AP and non-AP) stations shown in Figure 1. The communication device 600 is either a coordinator device, a coordinated device ora mere station managed by the coordinator or coordinated device of a Multi-AP set. The communication device 600 may preferably be a device such as a microcomputer, a workstation or a light portable device. The communication device 600 comprises a communication bus 613 to which there are preferably connected: a central processing unit 601, such as a processor, denoted CPU; a memory 603 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 602 connected to a wireless communication network, for example a communication network according to one of the IEEE 802.11 family of standards, via transmitting and receiving antennas 604. Preferably the communication bus provides communication and interoperability between the various elements included in the communication device 600 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 600 directly or by means of another element of the communication device 600. 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 602, in order to be stored in the memory of the communication device 600 before being executed. 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). Figure 6b is a block diagram schematically illustrating the architecture of the communication device 600, adapted to carry out, at least partially, the invention. As illustrated, device 600 comprises a physical (PHY) layer block 623, a MAC layer block 622, and an application layer block 621. The PHY layer block 623 (here an 802.11 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 medium access trigger frames TF to reserve a transmission slot, MAC data and management frames based on a 20MHz width to interact with legacy 802.11 stations, as well as of MAC data frames of OFDMAtype having smaller width than 20MHz legacy (typically 2 or 5 MHz) to / from that radio medium. The MAC layer block or controller 622 preferably comprises a MAC 802.11 layer 624 implementing conventional 802.11 be MAC operations, and additional block 625 for carrying out, at least partially, the invention. The MAC layer block 622 may optionally be implemented in software, which software is loaded into RAM 603 and executed by CPU 601. Preferably, the additional block 625, referred to as multi-AP interference managing module which has different operations to implement parts of the invention, depending on the role played by the communication device 600. As the same device can play different roles overtime, the additional block 625 is preferably designed to selectively perform the different operations. For instance, and not exhaustively, operations for the communication device 600 acting as an AP include: exchanging frames for a MAP TWT negotiation 560 / 561, converting timing of received TWT schedule information into timing information of its local clock (TSF); setting up an OBSS TWT element defining OBSS TWT SPs time aligned or overlapping with TWT SPs of a target BSS based on the information - in particular OBSS TWT Info - provided by the target AP; declaring a communication activity policy for OBSS TWT SPs; determining stations of its own BSS that interfere with a target BSS; providing OBSS TWT elements in beacon frames or Probe Response frames. Operations for the communication device 600 acting as a non-AP station in a BSS interfering with a target BSS include receive an OBSS TWT element from its AP; determining the medium access rules / policy; retrieving degraded AIFSN / ECWmin or an OBSS EDCA Parameter Set; switching to the degraded values for an OBSS TWT SP and switching back to legacy EDCA parameters after; performing EDCA contention with the degraded values during the OBSS TWT SP. MAC 802.11 layer 624 and multi-AP interference managing module 625 interact one with the other in orderto process accurately communications over the medium, e.g., over OFDMA RUs addressed to multiple stations according to embodiments of the invention. On top of the Figure, application layer block 621 runs an application that generates and receives data packets, for example data packets such as a video stream. Application layer block 621 represents all the stack layers above MAC layer according to ISO standardization. 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. 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. In the claims, the word “comprising” does not exclude other elements or steps, and 5 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

1. A communication method in a wireless network comprising the following steps: exchanging, from a first access point (AP) managing a first Basic Service Set (BSS) to a second AP managing a second BSS, information about a Target Wake Time (TWT) schedule provided in the first BSS, andsetting, by the second AP, an overlapping BSS (OBSS) TWT schedule in the second BSS which is timely aligned with the TWT schedule in the first BSS,wherein the first AP also exchanges all or part of the following information items for the second AP to configure the OBSS TWT schedule:a Buffer Status Report (BSR) of the first BSS reporting an amount of data to be exchanged within the first BSS,a low latency data scheme of the first BSS reporting one or more prioritized TID in the first BSS,a SP splitting scheme of the first TWT SPs reporting a breakdown of a service period (SP) within a Beacon interval of the first BSS,a reciprocal OBSS TWT indication reporting an agreement of the first AP to provide a second OBSS TWT schedule in the first BSS timely aligned with a second TWT schedule in the second BSS.

2. The method of Claim 1, wherein configuring the OBSS TWT schedule based on all or part of the information items includes adjusting a length of a SP of the OBSS TWT schedule.

3. The method of Claim 2, wherein adjusting a length of a SP of the OBSS TWT schedule includes negotiating, with the first AP, a length of a SP for the TWT schedule and the OBSS TWT schedule.

4. The method of Claim 1, wherein configuring the OBSS TWT schedule based on all or part of the information items includes adjusting a medium access policy in the second BSS during a SP of the OBSS TWT schedule.

5. The method of Claim 4, wherein adjusting a medium access policy in the second BSS includes applying, by non-AP stations of the second BSS, at least one degraded EDCA parameter.

6. The method of Claim 5, wherein an OBSS EDCA Parameter Set is used by the non-AP stations of the second BSS.

7. The method of Claim 5, wherein a degraded minimum size of a contention window (ECWmin) is used by the non-AP stations of the second BSS.

8. The method of Claim 5, wherein a degraded arbitration interframe space number (AIFSN) is used by the non-AP stations of the second BSS.

9. The method of Claim 5, wherein the degraded EDCA parameter is advised by the second BSS in a Beacon frame, e.g., through a dedicated OBSS EDCA Parameter Set that is additional to the conventional legacy EDCA Parameter Set and multi-user (MU) EDCA Parameter Set.

10. The method of Claim 5, wherein the degraded EDCA parameter is conveyed in a frame sent by the second AP to set the OBSS TWT schedule in the second BSS.

11. The method of Claim 1, wherein configuring the OBSS TWT schedule based on all or part of the information items includes splitting a SP of the OBSS TWT schedule in the second BSS according to the SP splitting scheme provided by the first AP.

12. The method of Claim 1, wherein configuring the OBSS TWT schedule based on all or part of the information items includes setting a second TWT schedule in the second BSS and setting the OBSS TWT schedule in the second BSS in a case where a second OBSS TWT schedule is set in the first BSS that is timely aligned with the second TWT schedule.

13. The method of Claim 1, wherein the information items are included in a TWT element extending the TWT element defined in the IEEE P802.11be / D7.0 standard.

14. The method of Claim 13, wherein the information items are included in a Broadcast TWT Parameter Set field of the extended TWT element.

15. The method of Claim 14, wherein the information items are included in an additional subfield to the subfields of the Broadcast TWT Parameter Set field as defined in the IEEE P802.11 be / D7.0 standard.

16. A wireless communication device comprising at least one microprocessor configured for carrying out the method of Claim 1.

17. 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 1.41

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