Method and apparatus for allocating TXS timeslots for multiple operations

Abstract

At an access point (AP) of the wireless network transmits a multi-user - ready to send triggered TXOP sharing trigger frame (MU-RTS TXS TF) for reserving a transmission opportunity (TXOP) on a communi

Description

FIELD OF THE INVENTION The present invention generally relates to wireless communications and more specifically to coordination in multi-AP operations. BACKGROUND OF 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 multipleaccess 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. The IEEE (Institute of Electrical and Electronics Engineers - RTM) 802.11be 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 IEEE 802.11 be draft standard Task Group focuses its activity also on the management of the low-latency data flows that ask prioritized medium accesses to cover its requirements. Several new mechanisms were introduced to handle these constraints, such an new extension for the Multi-User RTS trigger frame called MU-RTS TXS Trigger frame that can initiates triggered TXOP sharing procedure wherein only one scheduled STA can transmit MPDUs addressed to its associated AP or addressed to another STA. But these mechanisms may still be improved. The MAP topic is now addressed in the UHR Study Group, a study group in charge of defining the scope of the successor of the 802.11 be Task Group, namely the 802.11 bn Task group. The scope of the MAP topic is extended to optimized coordination, not only regarding shared transmissions but also regarding alternative mechanisms for OBSS Interference reduction. In other words, MAP coordination becomes one of emerging features for interference management in WLAN networks: multiple APs can cooperate together to enhance the performance of the network by smartly managing the interference due to OBSSs. Recent publications of the UHR group intend to define a TDMA-like procedure called Triggered TXOP Sharing procedure. This triggered TXOP sharing procedure allows an AP to allocate a portion of an obtained TXOP to one of its associated non-AP STA for transmitting its own data. This time sharing is triggered based on the MU-RTS trigger frame formerly defined by 802.11 ax but with a new TXOP sharing mode subfield. This subfield informs if the MU-RTS trigger frame is used according to its previous meaning defined by the 802.11ax (Triggered TXOP Sharing Mode is set to 0) or for the TXOP Sharing procedure (Triggered TXOP Sharing Mode is set to 1 or 2). In that latter, the TXOP Sharing is either limited to Uplink Traffic when the Triggered TXOP Sharing Mode is set to 1 or dedicated to Uplink and / or direct link traffic when the Triggered TXOP Sharing Mode is set to 2. Therefore, with this new mechanism, the AP is now able to allocate to its associated non-AP stations frequency resource unit (e.g. Basic Trigger Frame) or temporal resource unit. As explained above, the previous standard 802.11 ax and 802.11 be have defined several mechanisms to improve the medium access of the stations and as a result decrease the waste of air time by reducing the number of collisions among the stations. However, these mechanisms are limited to the intra-BSS communications. Thereby, one of the key challenges for the next 802.11 bn standard is the multi-AP coordination and the medium access sharing among the STAs associated to its BSS and its neighboring APs. The MU-RTS TXS Trigger frame is a first step to guarantee a timeslot, called in this context a TXS timeslot, for a dedicated STA. But as we explained before a way to effectively allocate resource allocation is required to ensure an efficient usage of the air time (reduction of the collisions) and so it exits a need to define procedure of time-based sharing to avoid concurrent transmissions. A technical goal of this invention is to provide an extension procedure based on the MU-RTS TXS Trigger frame to coordinate QoS data flows with dedicated requirements and Multi-APs transmissions and more especially a procedure that an AP could trigger and allocate resource for multiple types of requirements. SUMMARY OF THE INVENTION It is a broad objective of the present invention to overcome some of the foregoing concerns. The inventors have noticed that the existing triggering procedure can be extended to support multiple modes in the current time allocation. Correlatively, the invention also provides a wireless communication device comprising at least one microprocessor configured for carrying out any method as described above. According to a first aspect of the invention there is provided a method of communication in a wireless network, the method comprising at an access point, AP, of the wireless network the following steps: - transmitting a Multi User - Ready To Send Triggered TXOP Sharing trigger frame, MU-RTS TXS TF, for reserving a transmission opportunity, TXOP, on a communication channel, the MU-RTS TXS TF defining at least one TXS timeslot within the TXOP, the MU-RTS TXS TF comprising a Triggered TXOP Sharing Mode subfield for indicating a type of traffic allowed in the TXS timeslots; - wherein a value of the Triggered TXOP Sharing Mode subfield indicates that a sharing mode is indicated in an Extended Sharing Mode field of the MU-RTS TXS TF. According to embodiments, the Extended Sharing Mode field indicates the type of traffic allowed in all the TXS timeslots defined in the MU-RTS TXS TF. According to embodiments, a different Extended Sharing Mode filed is associated with each TXS timeslot. According to embodiments, the Extended Sharing Mode fields associated with the TXS timeslots are comprised in a common info field of the MU-RTS TXS TF. According to embodiments, the common info field further comprises a subfield indicating that it comprises the Extended Sharing Mode fields. According to embodiments, the common info field further comprises a subfield indicating the number of Extended Sharing Mode fields. According to embodiments, each Extended Sharing Mode field is comprised in a user info field associated with a TXS timeslot in the user info list field of the MU-RTS TXS TF. According to embodiments, at least one of the TXS timeslots is allocated to one or more station outside a BSS handled by the AP. According to embodiments, the sharing modes indicated in an Extended Sharing Mode filed comprise at least one of the following sharing modes: - Time slot allocated to one or more STA associated to the BSS with no data traffic restriction for uplink transmission; - Time slot allocated to one or more STA associated to the BSS used for low-latency traffics for uplink transmission; - Time slot allocated to one or more AP for multi-AP transmissions; - Time slot allocated to one or more STA associated to the BSS used for peer-to-peer traffics; - Time slot allocated to one or more STA used for traffic relay; - Time slot allocated to one or more STA associated to the BSS used for random medium access; - Time slot allocated to one or more STA not associated to the BSS used for random medium access. According to another aspect of the invention there is provided a computer program product for a programmable apparatus, the computer program product comprising a sequence of instructions for implementing a method according to the invention, when loaded into and executed by the programmable apparatus. According to another aspect of the invention there is provided a computer-readable storage medium storing instructions of a computer program for implementing a method according to the invention. According to another aspect of the invention there is provided a computer program which upon execution causes the method of the invention to be performed. According to another aspect of the invention there is provided an access point, AP, device in a wireless network, the AP device comprising a processor configured for: - transmitting a Multi User - Ready To Send Triggered TXOP Sharing trigger frame, MU-RTS TXS TF, for reserving a transmission opportunity, TXOP, on a communication channel, the MU-RTS TXS TF defining at least one TXS timeslot within the TXOP, the MU-RTS TXS TF comprising a Triggered TXOP Sharing Mode subfield for indicating a type of traffic allowed in the TXS timeslots; - wherein a value of the Triggered TXOP Sharing Mode subfield indicates that a sharing mode is indicated in an Extended Sharing Mode field of the MU-RTS TXS TF. 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, non-transitory carrier medium may comprise a storage medium such as a floppy disk, a CD-ROM, 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; Figures 2a, 2b and 2c illustrate examples of frame exchanges occurring in typical triggered procedure defined in 802.11ax and 802.11be standards; Figures 3a, 3b,3c 3d, 3e and 3f illustrate the MU-RTS trigger frame format such as defined by the standards IEEE P802.11REVme / D3.0, April 2023 and its amendment IEEE P802.11be / D3.2, May 2023; Figures 4a and 4b illustrate the MU-RTS TXS trigger frame format such as defined by the standards IEEE P802.11REVme / D3.0, April 2023 and its amendment IEEE P802.11be / D3.2, May 2023; Figure 5 illustrate an example of frame exchanges according to some embodiments of the invention; Figures 6a, 6b, 6c and 6d illustrate the extended MU-RTS TXS trigger frame format according to some embodiments of the invention; Figures 7a and 7b illustrate, using flowcharts, exemplary steps at the soliciting AP MLD (or AP) and one of the solicited STA MLDs (or stations) according to some embodiments of the invention; Figure 8a shows a schematic representation a communication device in accordance with embodiments of the present invention; and Figure 8b shows a schematic representation of a wireless communication device in accordance with embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION 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 SingleCarrier 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 timeslots or resource units, each timeslot 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 station or 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 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 BSS (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, 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 or from non-AP stations of the BSS, in the wireless network. A MU scheme has been adopted in the 802.11ax-2021 standard, published on May 2019. Thanks to the MU feature, a non-AP station has the opportunity to gain access to the wireless medium via two access schemes: the MU scheme and the conventional Enhanced Distributed Channel Access - EDCA (Single User) scheme. Each BSS defines a main elementary channel of the wireless medium (known as a primary channel, usually a 20 MHz channel ora multiple of 20 MHz channel) on which the stations (including the AP) perform EDCA contention using generally legacy EDCA parameters (defined in an EDCA Parameter Set provided by the AP). To increase bandwidth for the forthcoming transmission, the stations can simultaneously contend for additional 20 MHz channels, known as secondary channels. The communication channel thus granted for transmission comprises the primary channel and optionally secondary channels. The 802.11ax standard allows a MU downlink (DL) transmission to be performed by the AP when gaining access to the wireless medium for a transmission opportunity (TXOP). During the MU DL transmission on the granted communication channel, the AP performs multiple simultaneous elementary transmissions, over so-called resource units (RUs), to various non-AP stations. As an example, the resource units split the communication channel of the wireless network in the frequency domain, based for instance on Orthogonal Frequency Division Multiple Access (OFDMA) technique. The assignment of the RUs to the non-AP stations is signaled at the beginning of the MU Downlink frame, by providing an association identifier (AID) of a non-AP station (individually obtained by each station during its association procedure with the AP) for each RU defined in the transmission opportunity. The 802.11ax standard also allows a MU uplink (UL) transmission to be triggered by the AP when gaining access to the wireless medium. During the MU UL transmission, various non-AP stations can simultaneously transmit data to the AP over the resource units forming the communication channel. To control the MU UL transmission by the non-AP stations, the AP previously sends a control frame, known as a Trigger Frame (TF). The Trigger Frame allocates the resource units to the non-AP stations of the same BSS, using 16-bit Association IDentifiers (AIDs) 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 task group 802.11 be, as illustrated by draft IEEE P802.11be / D3.0 of March 2023, 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 medium access control (MAC) service access point (SAP) to logical link control (LLC), which includes one MAC data service. An Access Point MultiLink Device (or AP MLD) then corresponds to a MLD where each STA affiliated with the MLD is an AP, hence referred to as “affiliated AP”. A non-Access Point Multi-Link Device (or non-AP MLD) corresponds to a MLD where each STA affiliated with the MLD is a non-AP STA, referred to as “affiliated non-AP STA”. Depending on the literature, “multilink device”, “ML Device” (MLD), “multilink logical entity”, “ML logical entity” (MLE), “multilink set” and “ML set” are synonyms to designate the same type of ML Device. 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 multilink channel. The links established (or “enabled links”) for MLDs are theoretically independent, meaning that the channel access procedure (to the communication medium) and the communication are performed independently on each link. Hence, different links may have different data rates (e.g. due to different bandwidths, number of antennas, etc.) and may be used to communicate different types of information (each over a specific link). 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 affiliated APs and non-AP STAs operate on their respective channels in accordance with one or more of the IEEE 802.11 standards (a / b / g / n / ac / ad / af / ah / aj / ay / ax / be / bn) or other wireless communication standards. Thanks to the multi-link aggregation, traffic associated with a single MLD can theoretically be transmitted across multiple parallel communication links, thereby increasing network capacity and maximizing utilization of available resources. 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) 110and 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 networks and any number of non-AP stations per wireless network can be contemplated. In the present disclosure, APs 110, 120 and 130 are also referred to, respectively, as AP1, AP2 and AP3. A device may act as an AP of one wireless network and at the same time may belong to another wireless network as an associated STA. 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, 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 another 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 802.11ax 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 802.11be as well as to increase efficiency of the MU operation, existing mechanisms have been reused and improved. Since its initial versions, the IEEE 802.11 has developed or is developing wireless communication technology for improvement in the quality of service (QoS), compatibility of an access point (AP) protocol, security enhancement, radio measurement or radio resource measurement, wireless access in vehicular environment, fast roaming, and the like. With the constant increase of the number of wireless devices, the optimization of the medium access is an important factor to increase the useful bandwidth. Thereby, 802.11 standard has moved from a random-access mechanism called EDCA in which each station contend to get access to the medium and transmit to a trigger based medium access largely controlled by the access point. The triggering procedure were introduced by 11 ax amendment and refined in some part in be amendment. The following figures illustrate the main trigger based medium access procedures. Figures 2a, 2b and 2c illustrate examples of frame exchange occurring in typical triggered procedure defined in 802.11ax and 802.11 be standards. The figure 2a describes a Multi User uplink communication triggered by an AP. The frame exchange starts with a MU-RTS / CTS sequence procedure. This procedure allows an AP to initiate a TXOP and protect the TXOP frame exchange sequences. An AP may transmit an MU-RTS Trigger frame 210 to solicit simultaneous CTS frames 211, 212 transmissions from one or more non-AP STAs as illustrated by the MU-RTS frame 210 sent by one of the APs 110, 120 or 130 in the example of the figure 1. The MU-RTS 210 is a trigger frame of whom the format is further described in reference to the figure 3a. When the stations received a MU-RTS Trigger Frame (Trigger Frame type field 311 set to 3 in figure 3c) from their associated AP with a User Info Field which is addressed to them i.e. with the AID12 subfield equal to the 12LSB of the AID of the station, then the stations send back a CTS to the transmitting AP. Therefore, the STA1 and STA2 send respectively the CTS frame 211 and 212 to the AP. The CTS is sent on the channel indicated by the RU allocation subfield. This procedure allows to protect the subsequent transmission. Indeed, all the stations receiving either the MU-RTS from the AP or one of the CTSs from the stations have set their NAV that prevent the stations to access the medium for the duration included in the MU-RTS and CTS frames. Those durations computed by the AP corresponds to time to transmit the complete sequence i.e. Trigger frame, data and acknowledgement. Then, the AP may send a Trigger Frame to solicit simultaneous immediate response frames from the stations addressed by the trigger frame. Thereby, in the example of the figure 2a, the AP sends the basic trigger frame 213 (Trigger frame type set to 0) including User Info fields with the AID12 corresponding to the STA1 and STA2. Then in response to this trigger frame, the STA1 and the STA2 send their uplink data (214 for STA1 and 215 for STA2) to the AP on the channel allocated by the RU allocation subfield. Then, the AP may acknowledge the reception of the uplink data by sending a Multi-STA Block Ack 216 including the acknowledgement for the STA1 and the STA2. The figure 2b describes an example of an MU-RTS TXS Trigger frame with Triggered TXOP Sharing Mode subfield value equal to 1 soliciting UL PPDU. This procedure allows an AP to initiate a TXOP and then share its TXOP with an associated non-AP station before in its turn sending data to a non-AP station. The procedure may optionally be preceded by the sending of a CTS-to-self (not shown) to protect the TXOP frame exchange sequences. The MU-RTS TXS trigger frame is a trigger frame of whom the format is further described in reference to the figures 4a and 4b. The AP sends a Trigger Frame 220 with the Trigger Frame type field 311 set to the value 3 and the Triggered TXOP Sharing Mode field 316 set to the value 1, it means it is a MU-RTS TXS Trigger frame that solicits Uplink transmission. Upon the reception of this trigger frame, the scheduled station that is addressed by the trigger frame i.e. the AID12 subfield 331 included in the User Info field 330 is set to the 12LSB of the AID of the station and with the address corresponding to the RA field 303, transmits to the AP a CTS response 221 and then starts to transmit to the AP its uplink data 222. At the end of the data transmission, the AP sends a block acknowledgement to the STA1 223 to acknowledge the data received correctly. The station may then start the transmission of a new non-TB PPDU toward the AP 224 which acknowledges the data with a subsequent Block ack sent to the emitting STA 225. After transmitting the block ack of the last data to transmit (the AP finds out it is the last data because the medium is idle), the AP may use the end of its TXOP for its own operation, e.g., to send data 230 to another station at or even before the end of the TXOP Sharing duration allocated to the scheduled station STA1. The figure 2c describes an example of an MU-RTS TXS Trigger frame with Triggered TXOP Sharing Mode subfield value equal to 2 soliciting UL PPDU and / or transmission to another station i.e. direct link transmission. This procedure allows an AP to initiate a TXOP and then share its TXOP with an associated non-AP station before in its turn sending data to a non-AP station. The procedure may optionally be preceded by the sending of a CTS-to-self (not shown) to protect the TXOP frame exchange sequences. Therefore, the AP sends a Trigger Frame 250 with the Trigger Frame type field 311 set to the value 3 and the Triggered TXOP Sharing Mode field 316 set to the value 2, it means it is a MU-RTS TXS Trigger frame that solicits Uplink transmission and / or transmission addressed to another station. Upon the reception of this trigger frame, the scheduled station that is addressed by the trigger frame i.e. the AID12 subfield 331 included in the User Info field 330 is set to the 12LSB of the AID of the station and with the address corresponding to the RA field 303, transmits a CTS response to the AP 221 and then starts to transmit its data to the AP 222. At the end of the data transmission, the AP sends a block acknowledgement to the STA1 223 to acknowledge the data received correctly. Then the station may send data addressed to another station (STA2 in the example of this figure). Upon reception of these data from the STA1, the STA2 responds by an acknowledgement to the STA1 by sending a block ack 252. At the end of the duration allocated to the scheduled stations, the AP may use the end of its TXOP for its own operation e.g. transmission or transmit a new MU-RTS TXS to share again its TXOP with other stations. Figure 3a describes the trigger frame format such as defined by the standards IEEE P802.11REVme / D3.0, April 2023 and its amendment IEEE P802.11be / D3.2, May 2023. A Trigger frame (except MU-RTS trigger frame) allocates resources for and solicits one or more TB PPDU transmissions. An MU-RTS trigger frame allocates resources for one or more PPDUs (non-TB PPDU). The Trigger frame also carries other information required by the responding STA to send an HE TB PPDU. The format for the Trigger frame 300 described by the figure 3a is made up of the following fields: The frame control field 301 indicates mainly the type of the frames. The duration field 302 is generally set to a time in ps. The value allows the receivers to set their network allocation vector (NAV) which is an indication of the duration that a station shall prevent from accessing the medium. The RA field 303 is set to the non-AP address of the station identified by the AID12 subfield 331 of the User Info field 330 if there is only one User Info field 330 in the User Info list 305 otherwise if there are more than one User Info field 330 in the User Info list 305 or one User Info field 330 with the AID12 331 that allocates an RA-RU, the RA field 303 is set to the broadcast address. The TA field 304 is set to the address of the transmitting station if the frame is addressed to stations that belongs to the same BSS or is set to the transmitted BSSID if the frame is addressed to stations that belongs to several BSSs of the multiple BSSID set. The common info field 310 is further described with reference to the figures 3c and 3d for the HE and EHT variant. The user info list field 305 is further described with reference to the figure 3b. The User Info List field 305 contains zero or more User Info fields 330. The padding field 306 is optionally present in a Trigger frame to extend the frame length to give the recipient STAs enough time to prepare a response for transmission a SIPS after the frame is received. The FCS field 307 contains a 32-bit CRC. The EHT variant of the User Info field format is the same except that the EHT variant includes a PS160 subfield (in place of a reserved bit) which is used in complement to RU allocation and UL BW subfields for instance to handle 320MHz bandwidth channel. Figure 3b illustrates a format of the User Info field 330 (HE variant) of the trigger frame format according to the 802.11 standard. The User Info field includes the following subfields: AID12 subfield 331 encoded as described in the following table: AID12 subfield Description 0 User Info field allocates one or more contiguous RA-RUs for associated STAs 1-2007 User Info field is addressed to an associated STA whose AID is equal to the value in the AID12 subfield 2008-2044 Reserved 2045 User Info field allocates one or more contiguous RA-RUs for unassociated STAs 2046 Unallocated RU 2047-4094 Reserved 4095 Start of Padding field The RU Allocation subfield 332 along with the UL BW subfield 325 in the Common Info field 310 identifies the size and the location of the RU. If the AID12 subfield is in the range 1 to 2007, then the RU Allocation subfield indicates the RU allocated to the STA identified by the AID12 subfield. If the AID12 subfield is 0 or 2045, then the RU Allocation subfield indicates the starting RU of one or more contiguous RA-RUs (Random Access - Resource Unit) allocated by the User Info field. If the AID12 subfield is 2046, then the RU Allocation subfield indicates an unallocated RU. The UL FEC Coding Type subfield 333 of the User Info field indicates the code type of the solicited HE TB PPDU. The UL HE-MCS subfield 334 of the User Info field indicates the HE-MCS of the solicited HETB PPDU. The UL DCM subfield 335 of the User Info field indicates DCM of the solicited HE TB PPDU. The subfield 336 corresponds to the RA-RU Information subfield if the AID12 subfield is either 0 or 2045 otherwise this subfield corresponds to the SS (Spatial Stream) Allocation subfield. The Number of RA-RU subfield (not shown bits 26 to 30) indicates the number of contiguous RUs allocated for UORA (Uplink OFDMA Random Access). The value of the Number Of RA-RU subfield is equal to the number of contiguous RA-RUs minus 1. The more RA-RU subfield (not shown bit 31) is set to 1 to indicate that RA-RUs of the type indicated by the AID12 subfield in this User Info field are allocated in subsequent Trigger frames that are sent until the end of the TWT SP in which the Trigger frame carrying this field is sent. The UL Target Receive Power subfield 337 indicates the expected receive signal power, measured at the AP. The Trigger Dependent User Info subfield 339 in the User Info field is optionally present based on the value of the Trigger Type field. Figures 3c and 3d illustrate a format of respectively the HE variant and the EHT variant Common Info field 310 of the trigger frame format according to the 802.11 standard. The Common Info field includes the following subfields: The Trigger Type subfield 311 identifies the Trigger frame variant and its encoding is described with reference to Figure 3e The UL Length subfield 312 of the Common Info field indicates the value of the L-SIG LENGTH field of the solicited TB PPDU. The More TF subfield 313 of the Common Info field indicates whether or not a subsequent Trigger frame is scheduled for transmission. The CS Required subfield of the Common Info field 314 defines specific rules for channel sensing. The UL BW subfield 315 of the HE variant Common Info field indicates the bandwidth in the HE-SIG-A of the HE TB PPDU. The field 316 corresponds to the Triggered TXOP Sharing Mode subfield if the Trigger type 311 indicates an MU-RTS Trigger Frame otherwise the field 316 is the Gl And HE-LTF Type subfield. The Triggered TXOP Sharing Mode subfield encoding is further described with reference to Figure 3f. The AP Tx Power subfield 321 of the Common Info field indicates the AP’s combined transmit power at the transmit antenna connector of all the antennas used to transmit the triggering PPDU in units of dBm / 20 MHz. The UL Spatial Reuse subfield 324 of the Common Info field carries the values to be included in the Spatial Reuse fields in the HE-SIG-A field of the solicited HE TB PPDUs. The Trigger Dependent Common Info subfield 328 in the Common Info field is optionally present based on the value of the Trigger Type field. The common Info filed also includes the MU-MIMO HE-LTF Mode field 317, the Number Of HE / EHT-LTF Symbols field 318, the UL STBC 319c, the LDPC Extra Symbol Segment subfield 320, the Pre-FEC Padding Factor subfield 322, the PE Disambiguity subfield 323. The HE variant also specifically carries the Doppler subfield 325c, the UL HE-SIG-A2 Reserved subfield 326c. And the EHT variant carries HE / EHT P160 subfield 326d. These subfields are of less importance for the present disclosure. We can also note that a bit 327 is still reserved in the HE variant of the common info field. While the EHT variant contains two additional reserved subfields corresponding to 1 bit 325d and EHT Reserved subfield 351 corresponding to 7 bits. In addition, the EHT variant carries a Special User Info Field Flag subfield 350. The Special User Info Field Flag subfield is always set to 0 in an EHT variant Common Info field, indicating that a Special User Info field is included in the Trigger frame that contains the EHT variant Common Info field. Figures 4a and 4b describe the MU-RTS TXS trigger frame format such as defined by the amendment IEEE P802.11be / D3.2, May 2023. The MU-RTS TXS trigger frame 400 has the same settings as a MU-RTS Trigger frame 300 except for the following fields (as illustrated in figures 4a and 4b): The field 316 corresponds to the Triggered TXOP Sharing Mode subfield if the Trigger type 311 indicates an MU-RTS Trigger Frame otherwise the field 316 is the Gl And HE-LTF Type subfield. The Triggered TXOP Sharing Mode subfield encoding is further described with reference to Figure 3f. This field is set to the value 1 to solicit Uplink transmissions. It is set to the value 2 to solicit Uplink transmissions and / or transmission addressed to another station. The subfields UL Length 312, MU-MIMO HE-LTF Mode 317, Number Of HE-LTF Symbols And Midamble Periodicity 318, UL STBC 319c, LDPC Extra Symbol Segment 320, AP Tx Power 321, Pre-FEC Padding Factor 322, PE Disambiguity 323, UL Spatial Reuse 324, and Doppler 325c, UL HE-SIG-A2 326c and Trigger Dependent Common Info 328 in the Common Info field 410 are all reserved. The subfield User info List 405 is composed of only one User Info field that can have 2 formats: the HE variant User Info field includes the following subfields. The subfield AID12 is the same field as the field AID12 331, the subfield RU Allocation is the same field as the field RU Allocation 332, and the subfield Allocation Duration is the time allocated to the solicited non-AP STA. The EHT variant of the User Info field format is the same except that the EHT variant includes a PS160 subfield 437 (in place of a reserved bit) which is used in complement to RU allocation to handle 320MHz bandwidth channel. In summary, an Extended MU-RTS TXS trigger frame allows the AP to schedule a TXS timeslot dedicated to a station of the BSS for transmitting data according to two different sharing modes. These two different sharing modes consist in a first mode allowing only Uplink traffic from the station to the AP, and a second mode allowing Uplink traffic from the station to the AP and / or peer to peer traffic from the station to another station. This existing mechanism may be improved in different ways that may be used separately or freely combined. According to a first improvement, an Extended MU-RTS TXS trigger frame may be used to schedule more than one TXS timeslot at once. Each TXS timeslot may be dedicated to a different station. In some embodiments, a TXS timeslot may be dedicated to stations outside the BSS handled by the AP, like for example, another AP. According to a second improvement additional sharing modes are defined beyond the two existing ones. These additional modes may be used in the prior art mechanism for the scheduling of a single TXS timeslot. They may also apply to all embodiments of the first improvement. Figure 5 describes an example of a procedure initiated with an extended MU-RTS TXS Trigger frame according to embodiments of the invention and sharing a gained TXOP in several TXS timeslots, where each TXS timeslot may be dedicated to a different sharing mode. The amendment IEEE P802.11be specifies a MU-RTS TXS Trigger frame comprising a unique user info field allowing to allocate a unique TXS timeslot. The MU-RTS TXS Trigger frame is a first step to guarantee a timeslot for a dedicated STA. So, this figure illustrates an example of how the MU-RTS TXS Trigger frame can be extended by configuring multiple TXS timeslots, each TXS timeslots possibly initiating different sharing modes. The AP sends a Trigger Frame 500 with the Trigger Frame type field 311 set to the value 3 and the Triggered TXOP Sharing Mode field 316 set to the value 3, it means it is an extended MU-RTS TXS Trigger frame that comprises multiple User Info fields with dedicated sharing modes. The extended MU-RTS TXS trigger frame 500 is a trigger frame of whom the format is further described in reference to the figures 6a- 6d according to different embodiments. Upon the reception of the extended MU-RTS TXS Trigger frame, the solicited AP2 that is addressed by the trigger frame (i.e; the AID12 subfield 331 included in the user info field) transmits to the AP1 a CTS response 510 and then starts to transmit its uplink data frames 511 to the STA21 associated to it (BSS different from the AP1). For this TXS timeslot 501, the Extended Sharing Mode field is set to 2 (multi-AP transmission). In response the STA21 sends a block acknowledgement frame 512 to the AP2. The TXS timeslot ends with the duration allocated in the “Allocation Duration” field 335. For the TXS timeslot 502, the Extended Sharing Mode field is set to 3 initiating a peer-to-peer transmission between the STA12 and the STA13. The solicited STA12 transmits to the AP1 a CTS response 520 and then starts to transmit its uplink data frames 521 to the STA13 associated to the AP1. In another embodiment, the STA13 is a STA that is not associated to the AP1. In response the STA13 sends a block acknowledgement frame 522 to the STA12. The TXS timeslot ends with the duration allocated in the “Allocation Duration” field 335. For the TXS timeslot 503, the Extended Sharing Mode field is set to 1 initiating a uplink low-latency transmission to the AP1. The solicited STA12 transmits to the AP1 a CTS response 530 and then starts to transmit its uplink data frames 531 to the AP1. In response the AP1 sends a block acknowledgement frame 532 to the STA14. The TXS timeslot ends with the duration allocated in the “Allocation Duration” field 335. For the TXS timeslot 504, the Extended Sharing Mode field is set to 0 initiating downlink data transmissions to the STA12 and the STA13. The AP1 sends a Basic trigger frame 540 with the Trigger type” field 310 set to 0 to schedule uplink data transmissions for the STA12 and STA 13. In response the STA 12and STA13 transmit a HE TB PPDU (541,542) to the AP1. In response the AP1 sends a block acknowledgement frame 543 to the STA12. The TXS timeslot ends with the duration allocated in the “Allocation Duration” field 335. The Extended Sharing Mode field allows to define a dedicated sharing mode for each TXS timeslot inside the TXOP gained with the extended MU-RTS TXS trigger frame. Figure 6a describes a first embodiment of the format of the extended MU-RTS TXS Trigger frame. The Triggered TXOP Sharing Mode field 316, illustrated in Figure 6d, is set to the value 3 to identify the extended MU-RTS TXS Trigger frame. Compared to the Figure 3f, the value 3 named as “Reserved” is now set to “Extended MU-RTS TXS trigger frame” meaning that other modes are described in fields 610, 620 and or 651, 661. These new modes are different than described when the Triggered TXOP Sharing Mode subfield value is set to 1 or 2. As several fields described in the Figure 4a for a standard MU-RTS TXS Trigger frame are reserved, these available bits are reused to define additional fields to set up the sharing mode associated to each user info field. The “Number of User Info fields” field 610 is set to the number of TXS timeslots allocated inside the gained TXOP. The Extended Sharing Mode fields 620 defines the sharing mode that is associated with a user info field and therefore to the associated allocated TXS timeslot. The Extented Sharing Mode field is for example a 3-bit field with the allocation illustrated in Figure 6b. The Mode bitmap present field 600 is set to the value 1 if the fields 610 and 620 are present. In this embodiment the User Info List field 305 describes the list of the User Info field providing the information related to each TXS timeslot. It is similar to the User Info field 650 or 660 except that it does not contain the Extended Sharing Mode field 651 in Figure 6b. According to an embodiment, a single Extended Sharing Mode field 620 is present, while a plurality of TXS timeslots are defined in the MU-RTS TXS Trigger frame. In that case, the sharing mode indicated by the Extended Sharing Mode field applies to all the TXS timeslots. Figure 6c describes another embodiment of the format of the extended MU-RTS TXS Trigger frame. The Triggered TXOP Sharing Mode field 316 is set to the value 3 to identify the extended MU-RTS TXS Trigger frame. The Common Info field 310 remains similar as in Figure 6a except that it does not contain the Extended Sharing Mode field 620. The format of the user info field could be an HE variant User info field 650 or an EHT variant user info field 660. The sharing mode associated to each allocated TXS timeslot is defined within the user info field itself. The Extended Sharing Mode field 651, 661 is similar to the Extended Sharing Mode field 620 illustrated in Figure 6b. A Trigger Dependent User info field 652, 662 may be added to set additional information related the sharing mode set in the Extended Sharing Mode field 651, 661. Figures 7a and 7b illustrate, using flowcharts, the main steps of a method for sharing a TXOP reserved by the soliciting AP and one of the solicited STA according to some embodiments of the invention. The AP and the STA may be a regular AP, respectively a regular STA or an affiliated AP of an AP MLD, respectively an affiliated STA of a STA MLD. Figure 7a illustrates steps of a method at the sharing AP station, while Figure 7b illustrates steps of the method at the solicited STA(s) for the management of the data transmission inside the allocated TXS timeslot. At step 700, an AP gains a transmission opportunity TXOP. Then in step 701, the sharing AP may get information from the intended solicited STAs about their resource need. This step is optional. Then, in step 702, the sharing AP prepares the resource allocation for each TXS timeslot. The resource allocation may be computed based on the information obtained in step 701 or blindly with a statistical approach. Then, the sharing AP send an extended MU-RTSTXS trigger frame including the resource allocation for the solicited STAs that are identified through the AID12 field 431. This extended MU-RTS TXS trigger frame is received by the stations connected to the AP, namely the station of its BSS. It may also be received by coordinated APs in the neighborhood of the AP. This receiving station comprises the solicited STA in the step 710 if any. The receiving STA identified the extended MU-RTS TXS trigger frame. Then in step 712, the receiving station identifies a User Info field destined to it, thanks to the AID12 field 431. When the receiving station does not identify such User Info field destined to it, it means that the receiving station is not a target of the current shared TXOP. Then, the receiving station obtains, in step 712, its resource allocation into User Info field of the trigger frame. It reads the Extended Sharing Mode field 651 to identify the allowed data frames to be transmitted during the allocated TXS timeslot. Then, the receiving STA operates on the allocated time for instance as illustrated by Figure 5. Finally, the sharing AP detects the end of the shared communication with the end of the TXOP, or the end of time duration allocated to the receiving STA or by receiving a frame that shortens the sharing durations. Figure 8a schematically illustrates a communication device 800 configured to implement at least one embodiment of the present invention, for instance any of AP or AP MLD shown in Figure 1. The communication device 800 is an AP able to initiate a MU-RTS TXS procedure. The communication device 800 may preferably be a device such as a microcomputer, a workstation or a light portable device. The communication device 800 comprises a communication bus 813 to which there are preferably connected: a central processing unit 801, such as a processor, denoted CPU; a memory 803 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 802 connected to a wireless communication network, for example a communication network according to one of the IEEE 802.11 family of standards or Wi-Fi alliance protocols, via transmitting and receiving antennas 804. Preferably the communication bus provides communication and interoperability between the various elements included in the communication device 800 or connected to it. The representation of the bus is not limiting and in particularthe central processing unit is operable to communicate instructions to any element of the communication device 800 directly or by means of another element of the communication device 800. 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 802, in order to be stored in the memory of the communication device 800 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). As illustrated by Figure 8b, device 800 comprises a physical (PHY) layer block 823, a MAC layer block 822, and an application layer block 821. The PHY layer block 823 (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 MAC data and management frames based on a 20MHz width to interact with legacy 802.11 stations (non-AP, AP, non-AP MLD, AP MLD), as well as of MAC data frames of OFDMA type having smaller width than 20MHz legacy (typically 2 or 5 MHz) to / from that radio medium. The MAC layer block or controller 822 preferably comprises a MAC 802.11 layer 824 implementing conventional 802.11 be MAC operations, and additional block 825 for carrying out, at least partially, the invention. The MAC layer block 822 may optionally be implemented in software, which software is loaded into RAM 803 and executed by CPU 801. The MAC 802.11 layer 824 may implement an Upper-MAC stack along with a series of Lower-MAC modules. Preferably, the additional block 825, referred to as MU-RTS TXS managing module which has different operations to implement parts of the invention, depending on the role played by the communication device 800. As the same device can play different roles overtime, the additional block825 is preferably designed to selectively perform the different operations relative to MAP. MAC 802.11 layer 824 and MU-RTS TXS managing module 825 interact one with the other in order to process accurately communications over the medium, e.g. over single-user or OFDMA Rlls addressed to multiple stations according to embodiments of the invention. On top of the Figure, application layer block 821 runs an application that generates and receives data packets, for example data packets such as a video stream. Application layer block 821 represents all the stack layers above MAC layer according to ISO standardization. Any step of the algorithms of the invention may be implemented in software by execution of a set of instructions or program by a programmable computing machine, such as a PC (“Personal Computer”), a DSP (“Digital Signal Processor”) or a microcontroller; or else implemented in hardware by a machine or a dedicated component, such as an FPGA (“Field-Programmable Gate Array”) or an ASIC (“Application-Specific Integrated Circuit”). 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 making reference 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. Each of the embodiments of the invention described above can be implemented solely or as a combination of a plurality of the embodiments. Also, features from different embodiments can be combined where necessary or where the combination of elements or features from individual embodiments in a single embodiment is beneficial. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used.

Claims

1. A method of communication in a wireless network, the method comprising at an access point, AP, of the wireless network the following steps:- transmitting a Multi User - Ready To Send Triggered TXOP Sharing trigger frame, MU-RTS TXS TF, for reserving a transmission opportunity, TXOP, on a communication channel, the MU-RTS TXS TF defining at least one TXS timeslot within the TXOP, the MU-RTS TXS TF comprising a Triggered TXOP Sharing Mode subfield (316) for indicating a type of traffic allowed in the TXS timeslots;- wherein a value of the Triggered TXOP Sharing Mode subfield indicates that a sharing mode is indicated in an Extended Sharing Mode field of the MU-RTS TXS TF (620, 651, 661).

2. The method of claim 1, wherein the Extended Sharing Mode field indicates the type of traffic allowed in all the TXS timeslots defined in the MU-RTS TXS TF.

3. The method of claim 1, wherein a different Extended Sharing Mode filed is associated with each TXS timeslot.

4. The method of claim 3, wherein the Extended Sharing Mode fields (620) associated with the TXS timeslots are comprised in a common info field of the MU-RTS TXS TF.

5. The method of claim 5, wherein the common info field further comprises a subfield (600) indicating that it comprises the Extended Sharing Mode fields.

6. The method of claim 5, wherein the common info field further comprises a subfield (610) indicating the number of Extended Sharing Mode fields (620).

7. The method of claim 3, wherein each Extended Sharing Mode field (651, 661) is comprised in a user info field (650, 660) associated with a TXS timeslot in the user info list field (305) of the MU-RTS TXS TF.

8. The method of any one claims 1 to 7, wherein at least one of the TXS timeslots is allocated to one or more station outside a BSS handled by the AP.

9. The method of any one claims 1 to 8, wherein the sharing modes indicated in an Extended Sharing Mode filed comprise at least one of the following sharing modes:- Time slot allocated to one or more STA associated to the BSS with no data traffic restriction for uplink transmission;- Time slot allocated to one or more STA associated to the BSS used for low-latency traffics for uplink transmission;- Time slot allocated to one or more AP for multi-AP transmissions;- Time slot allocated to one or more STA associated to the BSS used for peer-to-peer traffics;- Time slot allocated to one or more STA used for traffic relay;- Time slot allocated to one or more STA associated to the BSS used for random medium access;- Time slot allocated to one or more STA not associated to the BSS used for random medium access.

10. A computer program product for a programmable apparatus, the computer program product comprising a sequence of instructions for implementing a method according to any one of claims 1 to 9, when loaded into and executed by the programmable apparatus.

11. A computer-readable storage medium storing instructions of a computer program for implementing a method according to any one of claims 1 to 9.

12. A computer program which upon execution causes the method of any one of claims 1 to 9 to be performed.

13. An access point, AP, device in a wireless network, the AP device comprising a processor configured for:- transmitting a Multi User - Ready To Send Triggered TXOP Sharing trigger frame, MU-RTS TXS TF, for reserving a transmission opportunity, TXOP, on a communication channel, the MU-RTS TXS TF defining atleast one TXS timeslot within the TXOP, the MU-RTS TXS TF comprising a Triggered TXOP Sharing Mode subfield (316) for indicating a type of traffic allowed in the TXS timeslots;- wherein a value of the Triggered TXOP Sharing Mode subfield indicates5 that a sharing mode is indicated in an Extended Sharing Mode field of theMU-RTS TXS TF (620, 651, 661).

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