GB2621330A - Multi-link P2P communication method with TID-To-Link mapping dedicated to P2P links - Google Patents

Abstract

A communication method in a wireless network, comprising, at a non-access point, non-AP, multi-link device, MLD having setup links with an AP MLD: establishing a peer-to-peer, P2P, communication session with a peer non-AP MLD, the P2P communication session being operative on multiple links, “P2P links”, amongst the setup links; negotiating, with the peer non-AP MLD, a P2P TID-to-Link mapping specific to the multiple P2P links; and directly communicating with the peer non-AP MLD through the multiple P2P links based on the negotiated TID-to-Link mapping. In another aspect of the invention, a Tunneled Direct Link Setup, TDLS, Action frame used to establish a TDLS direct link forming part of a peer-to-peer, P2P; communication session between non-AP stations or MLDs, comprising a TID-to-Link information element, IE, signalling a mapping of TIDs to P2P links on which the P2P communication session is operative is disclosed. The method may comprise exchanging of a TID-to-Link mapping information element according to the IEEE 802.11be/D2.0 standard.

Description

MULTI-LINK P2P COMMUNICATION METHOD WITH TID-TO-LINK MAPPING DEDICATED TO P2P LINKS

FIELD OF THE INVENTION

The present invention generally relates to wireless communications, in particular to Multi-Link (ML) communications and more specifically to peer-to-peer (P2P) or "Direct Link" (DiL) ML communications.

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.

The 802.11 family of standards adopted by the Institute of Electrical and Electronics Engineers (IEEE -RTM) provides a great number of mechanisms for wireless communications between STAs.

With the development of latency sensitive applications such as online gaming, real-time video streaming, virtual reality, drone or robot remote controlling, better throughput, low latency and robustness requirements and issues need to be taken into consideration. Such problematic issues are currently under consideration by the IEEE 802.11 working group as a main objective to issue the next major 802.11 release, known as 802.11 be or EHT for "Extremely High Throughput".

The IEEE P802.11be/D2.0 version (May 2022, below "D2.0 standard") introduces the Multi-Link (ML) Operation (MLO). MLO improves data throughput by allowing communications between STAs over multiple concurrent and non-contiguous communication links.

MLO enables a non-AP (Access Point) MLD (ML Device) to register with an AP MLD, i.e. to discover, authenticate, associate and set up multiple communication links with the AP MLD. Each communication link so setup (below "setup link") enables channel access and frame exchanges between the non-AP MLD and the AP MLD based on supported capabilities exchanged during the association procedure.

A MLD is a logical entity that has more than one affiliated station (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 AP MLD is thus made of multiple affiliated APs whereas a non-AP MLD is made of multiple affiliated non-AP STAs. The affiliated STAs in both AP MLD and non-AP MLD can use 802.11 mechanisms to communicate with affiliated STAs of another MLD over each of the multiple setup links.

With the introduction of MLO, the D2.0 standard also defines the Traffic IDentifier(TID)-To-Link mapping mechanism. This mechanism allows an AP MLD and a non-AP MLD that performed or are performing multi-link setup to determine how UL (Uplink) and DL (Downlink) QoS traffic corresponding to TID values between 0 and 7 are assigned to the setup links for the non-AP MLD.

A setup link is defined as "enabled" for a non-AP MLD if at least one TID is mapped to that link either in DL or in UL and is defined as disabled if no TIDs are mapped to that link both in DL and UL.

By default, all TIDs are mapped onto all setup links for both DL and UL, and all setup links are enabled.

The D2.0 standard however defines a procedure allowing a TID-To-Link mapping negotiation in DL and/or UL directions between an initiating MLD and a responding MLD.

The TID-To-Link mapping therefore directs data traffic over one or the other enabled links, depending on the TIDs of the data. This advantageously allows the wireless network to be better exploited.

To meet latency requirements in the 802.11 network, peer-to-peer (P2P) communications are considered. The so-called Tunneled direct-link setup, TDLS, mechanism is the only P2P mechanism existing in the current version of the 802.11 standard family.

The existing Tunneled Direct Link Setup (TDLS) has been adapted to coexist with the MLDs of the D2.0 standard.

Formerly endorsed by IEEE 802.11z standard in 2008, TDLS enables devices (called TDLS peer STAs) to link directly to one another when connected to a traditional AP. To set up and maintain a direct or P2P link, both TDLS peer STAs shall be associated with the same infrastructure BSS On short the same AP). The TDLS mechanism provides encapsulation of the setup frames exchanged between the two TDLS peer STAs, in Data frames. This allows the setup frames to be transmitted transparently (or "tunneled") through the AP. The setup frames include so-called TDLS Action frames. Once the direct or P2P link is setup, the TDLS peer STAs can communicate directly with one another, without involving the AP while remaining associated with the AP.

The D2.0 standard adapts the TDLS mechanism to the multi-link feature, by adjusting the signaling of MAC addresses in the TDLS Setup frames when establishing a TDLS session on one of the multiple setup links. As a result, a non-AP STA MLD that has performed multi-link setup with an AP MLD can establish a single link TDLS direct link on one of its links with a peer non-AP STA MLD that has performed multi-link setup with the same AP MLD. The single link (e.g. a 20MHz channel on either of the 2.4, 5 and 6 GHz bands) is referred below to as the P2P link of the TDLS direct link.

There is a need to establish P2P communication sessions over multiple P2P links to improve network efficiency. For example, a video application may exchange several high data rate video streams with a Head Mounted Display device (HMD) device. In addition, some time-critical commands may be transmitted at the same time. Hence, multiple P2P links for directly exchange all these video and command frames could be of high benefit.

The D2.0 standard makes it possible that a non-AP MLD establishes several single link TDLS direct links with the same peer non-AP MLD on its setup links, to define a multi-link P2P or DiL communication session with the peer non-AP MLD.

An efficient management of the multi-link P2P communication session is required to offer good network performance in P2P communications and to not affect other communications within the wireless network.

SUMMARY OF INVENTION

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

The inventors have noticed that a TID-To-Link mapping dedicated to the multiple P2P links can contribute to optimize latency and throughputs in the wireless network. The present invention hence defines new mechanisms that allow such P2P TID-To-Link mapping to be defined.

In this context, embodiments of the invention are directed to a communication method in a wireless network, comprising, at a non-access point, non-AP, multi-link device, MLD having setup links with an AP MLD: establishing a peer-to-peer, P2P, communication session with a peer non-AP MLD, the P2P communication session being operative on multiple links, "P2P links", amongst the setup links, negotiating, with the peer non-AP MLD, a P2P TID-to-Link mapping specific to the multiple P2P links, and directly communicating with the peer non-AP MLD through the multiple P2P links based on the negotiated TID-to-Link mapping.

Such establishing usually includes exchanging frames, e.g. TDLS Action frames in the case of the TDLS mechanism, over enabled links. When one of the peer non-AP MLDs send such a frame, the other peer non-AP MLD receives it.

By "negotiating", it is meant at the least the indication by one non-AP MLD of its desired mapping. The other non-AP MLD may only be offered the possibility to accept it or refuse it in some approaches. In other approaches, the other non-AP MLD may provide counter-proposal with a different P2P TID-to-Link mapping. One round trip or more round trips can be implemented during the negotiation. A more dynamic negotiation is thus obtained.

According to the invention, the peer non-AP MLDs start a negotiation of a TID-to-Link mapping specificto the multiple P2P links on which the direct link (or P2P) communication session operates. It turns out that P2P data traffic can be efficiently routed to one or the other of the P2P links, to improve network latency and throughputs. As an example, the P2P TID-to-Link mapping is particularly beneficial for high-priority TIDs because it allows associated link resources to be physically isolated from other lower-priority TIDs.

Optional features of the invention are defined below with reference to a method, while they can be transposed into device features.

In some embodiments, establishing the P2P communication session includes exchanging, with the peer non-AP MLD, an initial request frame initiating a procedure to establish the P2P communication session, wherein the initial request frame includes a P2P TID-to-Link Mapping Negotiation Supported field set to a value indicating a P2P TID-to-Link mapping specific to the multiple P2P links is to be negotiated.

This configuration allows the peer non-AP MLD to freely decide to negotiate or not the P2P TID-to-Link mapping.

In other embodiments, negotiating the P2P TID-to-Link mapping includes exchanging, with the peer non-AP MLD, a TID-to-Link Mapping information element, 1E, according to the IEEE 802.11be/D2.0 standard and defining a mapping of TIDs to the multiple P2P links of the P2P communication session.

This advantageously reuses already-existing IEs to convey the negotiated P2P-specific mapping.

In some implementations, the TID-to-Link Mapping IE is included in at least one management frame used to establish the P2P communication session. In other words, the negotiation takes place during the establishment of the P2P session. Advantageously, no additional frame is required. Furthermore, the non-AP MLDs can early know whether it is worth to establish the P2P session, given the proposed/negotiated mapping. This saves useless P2P session establishments.

In other implementations, the TID-to-Link Mapping IE is exchanged after the P2P communication session is established. This allows for example the mapping to be changed while the P2P session is running, to dynamically adapt it to network conditions.

Of course, both implementations can be combined where a first P2P TID-to-Link Mapping is negotiated during the P2P session establishment and one or more subsequent P2P TID-to-Link Mapping are negotiated during the lifetime of the P2P session.

In some embodiments, the method further comprises negotiating, with the AP MLD, an initial TID-to-Link mapping that maps TIDs to the setup links, and matching the P2P TID-to-Link mapping with the initial TID-to-Link mapping.

This configuration seeks to check whether the P2P mapping meets the constraints induced by the initial mapping with the AP MLD. Indeed, as a result of this initial mapping, one non-AP MLD is not allowed to transmit, on a setup/enabled link, data traffic of a TID different from the TIDs mapped to that link.

In some implementations, matching the P2P TID-to-Link mapping with the initial TID-toLink mapping includes checking that a mapping of a TID to a P2P link is allowed in the initial TIDto-Link mapping. This may be done for each and every mapping in the P2P TID-to-Link mapping to ensure that each of them is allowed in the initial mapping with the AP MLD. A mapping is allowed when the initial mapping already allows the same mapping.

Of course, although a check between the two initial and P2P mappings is proposed here, the invention may be used in alternative scenario where the initial and P2P mappings are fully independent one to each other, meaning a mapping in the P2P TID-to-Link mapping does not need to meet the constraints of the initial TID-to-Link mapping regarding the same link.

In some embodiments, establishing a P2P communication session includes establishing at least one Tunneled Direct Link Setup, TDLS, direct link with the peer non-AP MLD, by exchanging TDLS Action frames. This explicitly dedicates the invention to the P2P mechanism of 802.11 wireless networks.

In particular embodiments, a TDLS Discovery Request frame or a TDLS Setup Request frame of the TDLS Action frames includes a P2P TID-to-Link Mapping Negotiation Supported field set to a value indicating a P2P TID-to-Link mapping specific to the multiple P2P links is to be negotiated. This advantageously offers signaling for the present invention using existing frame formats. For example, the P2P TID-to-Link Mapping Negotiation Supported field may be included in a Common Info field of a TDLS Multi-Link information element.

In other particular embodiments, the P2P TID-to-Link mapping is carried in a dedicated information element (e.g. TID-to-Link Mapping IE according to the IEEE 802.11be/D2.0) within at least one of the TDLS Action frames. Again, this advantageously reuses already-existing IEs. Correlatively, embodiments of the invention also provide a wireless communication device comprising at least one microprocessor configured for carrying out any method as described above.

Embodiments of the invention also provide a Tunneled Direct Link Setup, TDLS, Action frame used to establish a TDLS direct link forming part of a peer-to-peer, P2P, communication session between non-AP stations or MLDs, comprising a TID-to-Link information element, 1E, signaling a mapping of TIDs to P2P links on which the P2P communication session is operative.

As an example, the TID-to-Link IE is as defined in the IEEE 802.11be/D2.0 standard.

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, 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.

The names of the IEs as provided in the present document intend to reflect those currently used in the 802.11 standards in order to facilitate the reading of the document. Of course, any other naming carrying the same information can be used alternatively.

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 a typical 802.11 network environment involving ML transmissions between MLDs in which one or more single link Tunneled Direct Link Setup, TDLS, direct links can be established; Figure 2 illustrates a TID-to-Link Mapping 1E; Figure 3 illustrates, using frame exchanges in a timeline, a possible scenario for an initiator peer non-AP STA to handle P2P traffic; Figure 3a illustrates the format of 802.11 Action frames according to the 802.11 standards; Figure 4a illustrates a so-called "Link Identifier" IE according to the 802.11 standards; Figure 4b illustrates a so-called "TDLS Multi-Link" IE according to the 802.11 standards; Figure 5 illustrates, using a flowchart, general steps to manage a multi-link P2P session according to the embodiments of the invention; Figure 6 illustrates more detailed operations of the process of Figure Sin the context of the TDLS mechanism, at a TDLS initiator non-AP MLD, in accordance with embodiments of the present invention; Figure 7 illustrates more detailed operations of the process of Figure Sin the context of the TDLS mechanism, at a TDLS responder non-AP MLD, in accordance with embodiments of the present invention; Figure 8 illustrates a modified TDLS IE compared to Figure 4b, in accordance with embodiments of the present invention; Figure 9 illustrates an exemplary 802.11be multi-link reference model for a MLD either AP MLD or non-AP MLD; and Figure 10 shows a schematic representation a communication device according to at least one embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

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. A SDMA system may utilize sufficiently different directions to simultaneously transmit data belonging to multiple user terminals, i.e. wireless devices or STAs. 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. A 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., STAs). In some aspects, a wireless device or STA implemented in accordance with the teachings herein may comprise an access point (so-called AP) or not (so-called non-AP STA or STA).

While the examples are described in the context of VViFi (RTM) networks, the invention may be used in any type of wireless networks like, for example, mobile phone cellular networks that implement very similar mechanisms.

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 STA (gNB), Base STA Controller ("BSC"), Base Transceiver STA ("BTS"), Base STA ("BS"), Transceiver Function (TF"), Radio Router, Radio Transceiver, Basic Service Set ("BSS"), Extended Service Set ("ESS"), Radio Base STA ("RBS"), or some other terminology.

A non-AP STA may comprise, be implemented as, or known as a subscriber STA, a subscriber unit, a mobile STA (MS), a remote STA, a remote terminal, a user terminal (UT), a user agent, a user device, user equipment (UE), a user STA, 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 ("VVLL") STA, 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 STA 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.

The current discussions in the task group 802.11be, as illustrated by draft IEEE P802.11 be/ D2.0 of May 2022, 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. Those links are referred to as "setup links" or "setup communication links".

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 Multi-Link 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. An illustrative architecture of a Multi-Link Device is described below with reference to Figure 8.

A multi-link logical MAC address of an MLD may be a MAC address that uniquely identifies the MLD entity, which manages the affiliated STA entities. The multi-link logical MAC address may be referred to as an "MLD MAC address", which may be a non-AP MLD MAC address or an AP MLD MAC address. The MLD MAC address may be a globally unique MAC address within the MLD considered or a MAC address that is shared with one of its affiliated STA entities. The affiliated STA entities (AP or STA) of an MLD have different per-link MAC addresses or "STA MAC addresses".

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.

The communication links (or "enabled links") setup 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 setup communication 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 setup communication link or merely "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/adad/af/ah/ailay/ax/be) 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.

From architecture point of view, a MLD contains typically several radios in order to implement its affiliated STAs but not necessary a number equal to its number of affiliated STAs. In particular, a non-AP MLD may operate with a number of affiliated STAs greater than its number of radios (which can even be reduced to a single one).

Figure 1 illustrates a typical 802.11 network environment involving ML transmissions between MLDs in which several single link Tunneled Direct Link Setup, TDLS, direct links according to the D2.0 standard can be established.

Wireless communication network 100 involves an AP MLD 110 and two non-AP MLDs 120 and 130. Of course, another number of non-AP MLDs registering to the AP MLD 110 and then exchanging frames with it may be contemplated.

One of the two non-AP MLDs may be a legacy 802.11 station. In that case, the "affiliated non-AP STA" mentioned below merely refer to the legacy station itself.

AP MLD 110 has multiple affiliated APs, two affiliated APs 111 and 112 (also referenced AP1, AP2 respectively) in the exemplary Figure 1, each of which behaves as an 802.11 AP over its operating channel within one frequency band. Known 802.11 frequency bands include the 2.4 GHz band, the 5 GHz band and the 6 GHz band. Of course, other frequency bands may be used in replacement or in addition to these three bands.

The non-AP MLDs 120, 130 have multiple affiliated non-AP STAs, each of which behaves as an 802.11 non-AP STA in a BSS (managed by an affiliated AP 111 or 112) to which it registers. In the exemplary Figure 1, two non-AP STAs 121 and 122 (also referenced Al and A2 respectively) are affiliated with non-AP MLD 120 and two non-AP STAs 131 and 132 (also referenced B1 and B2 respectively) are affiliated with non-AP MLD 130.

Each affiliated AP offers a link towards the AP MLD 110 to the affiliated non-AP STAs of a non-AP MLD (120 or 130). Hence, the links for each non-AP MLD can be merely identified with the identifiers of the respective affiliated APs. In this context, each of the affiliated APs 111 and 112 can be identified by an identifier referred to as "Link ID". The Link ID of each affiliated AP is unique and does not change during the lifetime of the AP MLD. AP MLD may assign the Link ID to its affiliated APs by incrementing the IDs from 0 (for the first affiliated AP). Of course, other wording, such as "AP ID", could be used in a variant.

To perform multi-link communications, each non-AP MLD 120, 130 has to discover, authenticate, associate and set up multiple links with the AP MLD 110, each link being established between an affiliated AP of the AP MLD 110 and an affiliated non-AP STA of the non-AP MLD. Each of such setup communication links, referred to as "enabled link", enables individual channel access and frame exchanges between the non-AP MLD and the AP MLD based on supported capabilities exchanged during association.

The discovery phase is referred to as ML discovery procedure, and the multi-link setup phase (or association phase) is referred to as ML setup procedure. Management frames exchanged with the AP MLD during the ML discovery and ML setup procedures contain a new Information Element specific to the Multi-Link Operation (MLO), referred to as Basic Multi-Link element, which conveys a description of the affiliated STA entities of the MLD sending the frame that are additional to the sending affiliated STA entity (known as "reporting STA"). More precisely, the profile of the reporting STA is provided in Information Elements, IEs, of the frame outside the Basic Multi-Link element. And, the Basic Multi-Link element carries one or more Per-STA Profile subelement(s) corresponding to each additional affiliated STA (known as "reported STA").

The ML discovery procedure allows the non-AP MLD to discover the wireless communication network 100, i.e. the various links to the AP MLD offered by the multiple affiliated APs. The ML discovery procedure thus seeks to advertise the various affiliated APs of the AP MLD, together with the respective network information, e.g. including all or part of capabilities and operation parameters. Once a non-AP MLD has discovered the wireless communication network 100 through the ML discovery procedure and after an MLD authentication procedure, the ML setup procedure allows it to select a set of candidate setup links between its own affiliated non-AP STAs and some of the discovered affiliated APs and to request the AP MLD 110 to set up these links, which may be accepted or refused by the AP MLD. If the AP MLD accepts, the non-AP MLD is provided with an Association Identifier (AID) by the AP MLD, which AID is used by the affiliated non-APs of the non-AP MLD to wirelessly communicate over the multiple setup communication links (communication channels) with their corresponding affiliated APs. During the ML setup procedure, the non-AP MLDs declare part or all of their capabilities.

For instance, they may declare their Tunneled Direct Link Setup (TDLS) capability, which enables devices (called TDLS peer STAs) to communicate directly to one another when connected to a traditional AP. For this, appropriate fields are provided in the management frames. De facto, in all Management frames, a non-AP MLD which may act as TDLS initiator STA or TDLS responder STA (dot11TunneledDirectLinkSetupImplemented to true) sets the TDLS Support bit (bit 37) in the Extended Capabilities element to 1.

For illustrative purpose, in wireless communication network 100, during the ML setup procedures, two candidate setup links have been requested by non-AP MLD 120 and accepted by AP MLD 110: a first link 151 between affiliated AP 111 (API) and affiliated non-AP STA 121 (Al), a second link 152 between affiliated AP 112 (AP2) and affiliated non-AP STA 122 (A2). Similarly, two candidate setup links have been requested by multi-radio non-AP MLD 130 and accepted by AP MLD 110: a first link 161 between affiliated AP 111 (AP1) and affiliated non-AP STA 131 (B1), a second link 162 between affiliated AP 112 (AP2) and affiliated non-AP STA 132 (B2).

As mentioned above, a different number of setup communication links per non-AP MLD may be contemplated. In some embodiments, the non-AP entity B may be a mere legacy 802.11 station in which case a single communication link exists with either AP1 or AP2 (depending on the operation channel).

Traffic may be specialized per link through the TID-To-Link mapping mechanism that has been adapted to the MLO by the D2.0 standard. The specialization results from an agreement made between the AP MLD and the non-AP MLD.

IEEE 802.11 defines a traffic identifier (TID) to classify a packet for differentiated services.

The TID is represented as a four-bit number (0-7) identifying the desired quality of service (QoS) for the traffic. In MLO, the TID is used to determine which link(s) to use for traffic with a specific QoS through the TID-to-link mapping mechanism.

The TID-to-link mapping mechanism allows the AP MLD and the non-AP MLD that performed or are performing multi-link setup to determine how UL and DL QoS traffic corresponding to TID values between 0 and 7 will be assigned to the setup links for the non-AP MLD. If a specific TID is mapped to a set of links, then any link within that set can be used to transmit data frames from that TID. By default, after multi-link setup, all TIDs are mapped to all setup links. However, the TID-to-link mapping can specify either the same or different link sets for each TID. After multi-link setup, the TID-to-link mapping can be updated through negotiation.

An MLD that supports TID-to-link mapping negotiation has dot11TIDtoLinkMappingAcfivated equal to true and sets to a nonzero value (typically value 1 as) the TID-to-Link Mapping Negotiation Supported subfield in the MLD Capabilities and Operations field included in the Common Info subfield of the (Basic) Multi-Link information element (1E) conveyed in a setup frame, typically a (Re)Association Request/Response frame.

Next, in the multi-link (re)setup procedure, the non-AP MLD may initiate the TID-to-link mapping negotiation by including a so-called TID-to-link Mapping element in the (Re)Association Request frame.

The TID-to-Link Mapping IE is illustrated in Figure 2. The TID-to-link mapping IE is only available for the (Re)Association Request/Response frames and for the TID-to-link mapping Request/Response/Teardown frames that are protected EHT action frames.

The TID-to-link mapping IE 200 is made of:

an Element ID field 210 equal to 255,

a Length field 220 defining the length of the Information Element, - an Element ID Extension field 230 set to 109, hence identifying a TID-to-link mapping 1E, a TID-to-Link Mapping Control field 240 contains several subfields: o a Direction subfield 241 indicating whether the mapping concerns downlink (DL), uplink (UL) or both UL and DL transmissions, o a Default Link Mapping subfield 242 set to 1 if the default TID-to-mapping is applied, and o a Link Mapping Presence Indicator subfield 243 carrying a bitmap indicating which link mapping 250-257 are defined in the IE 200. Each bit #n (n from 0 to 7) of the bitmap 243 indicates if the Link mapping of a TID #n (25n) is present or not, and - zero, one or more (up to 7) "Link Mapping Of TID n" fields 520 to 527, depending on the values of the Default Link Mapping subfield 242 and the Link Mapping Presence Indicator subfield 243 (if no default link mapping). The Link Mapping Of TID n field indicates the link(s) on which frames belonging to the TID n are allowed to be sent (i.e., carries a bitmap of the links to which the TID n is mapped to). A value of 1 in bit position i (from 0 to 14) of the Link Mapping Of TID n field indicates that TID n is mapped to the link associated with the link ID i for the direction as specified in the Direction subfield 241. A value of 0 in bit position i indicates that the TID n is not mapped to the link associated with the link ID i. When the Default Link Mapping subfield is set to 1, this field is not present.

After receiving the (Re)Association Request frame containing the TID-To-Link Mapping IE 200, the AP MLD performs the following TID-to-link mapping negotiation procedure: -if the AP MLD accepts the requested TID-to-link mapping, an (Re)Association Response frame with no TID-to-link mapping IE is sent to the requesting non-AP MLD, - otherwise, the AP MLD rejects the proposed mapping by including in the (Re)Association Response frame a different TID-to-link mapping IE containing a preferred TID-to-link mapping.

The TID-to-link mapping setup procedure can also be initiated by any of the MLDs after the multi-link (re)setup, to negotiate a new TID-to-link mapping. In that case, TID-to-link mapping Request/ Response/Teardown frames are used that convey a TID-To-Link Mapping IE 200. Again the responding MLD can accept the request, reject the request or suggest another TID-to-link mapping.

A non-AP MLD, such as MLD A 120, that has performed multi-link setup with AP MLD 110 and optionally has negotiated a TID-to-link Mapping on the setup links with the AP MLD can establish one or more single link TDLS direct links, each on one of its setup links, with MLD B 130. This means that two or more single link TDLS direct links can be established between the same non-AP MLDs, using respectively two or more of their setup communication links. Reference 171 in the Figure illustrates a first single link TDLS direct link (or P2P connection) established between MLD A 120 and MLD B 130 on the first link 151, 161.

Reference 172 in the Figure illustrates a second single link TDLS direct link (or P2P connection) established between MLD A 120 and MLD B 130 on the second link 152, 162. As a result, MLD A 120 and MLD B 130 have established a TDLS direct link session over multiple links, referred to as P2P links. This allows MLD A 120 (through affiliated STA Al 121 over the first TDLS direct link and STA A2 122 over the second TDLS direct link) and MLD B 130 (through affiliated STA B1 131 over the first TDLS direct link and STA B2 132 over the second TDLS direct link) to directly exchange data without relay by AP MLD 110.

The single link TDLS direct link mechanism in the context of MLDs in described with more details with reference to Figure 3 which illustrates, using frame exchanges in a timeline, a possible scenario for an initiator peer non-AP STA (affiliated non-AP STA) to handle P2P traffic.

This example involves STA Al 121 as the initiator for the P2P communication and STA B1 131 as the partner or responder for the P2P communication 171. They both take part of the same BSS (identified by BSSID1) on a given link 1(151/161), and are associated with AP 111. As mentioned above, STA Al and STA B1 may be non-AP stations affiliated with respective non-AP MLDs, while AP 111 may be an AP affiliated with an AP MLD 110.

In the sequence, once STA Al and STA B1 are associated with the AP (association not shown), they can exchange data over their operation link through the AP.

To reduce the amount of traffic that is transferred in the network and prevent congestion at the AP, the IEEE 802.11z amendment has defined mechanisms, known as Tunneled Direct Link Setup (TDLS), that allow the 802.11 non-AP stations to set up a direct or P2P link between them, while also remaining associated with the AP. The D2.0 standard upgrades the conventional TDLS mechanism to work with the multi-link feature.

Tunneled direct-link setup (TDLS) is characterized by the use of signaling frames that are encapsulated in 802.11 Data frames so that the signaling frames are transmitted through the AP transparently. Therefore, the AP does not need to be direct-link aware, nor does it have to support the same set of capabilities that are used on the direct or P2P link, in order for TDLS to be used.

In the sequence shown, a TDLS session or "TDLS direct rink" is established between STA Al and STA B1 (either of both can be the initiator of the TDLS direct link establishment). The establishment may include a TDLS discovery procedure (optional) and a TDLS setup procedure.

TDLS discovery and setup procedures between STA Al and STA B1 involve frames, known as TDLS Action frames, that are usually sent and received via intermediate AP 111.

Figure 3a illustrates the format of 802.11 Action frames 300. The Figure only shows the payload of such Action frames, the MAC header being omitted for conciseness.

An Action frame 300 has the format of a frame, hence has a Category field 301, an Action field 302 immediately after the Category field 301 and an Elements field 303.

Various values of the Category field 301 are defined in the 802.11 standard, corresponding to various Actions frames. Category field set to 12 defines a TDLS Action frame, while Category field set to 4 defines a Public Action frame.

TDLS Action frames conveys TDLS signaling.

1-byte Action field 302 for a TDLS Action frame may take various values from 0 to 10 (11 to 255 being reserved), as shown in Table 9-496 of the 802.11 Standard (as example, IEEE P802.11-REVmeTm/D1.0, December 2021) and reproduced in the Figure, to signal different types of TDLS Action frames having each its own function in the TDLS mechanism. For example, TDLS Setup Request frame 313 is identified by Action field 302 set to 0; TDLS Setup Response frame 314 by Action field 302 set to 1; and TDLS Setup Confirm frame 315 by Action field 302 set to 2.

Elements field 303 comprises various Information Elements, IEs, describing parameters for the TDLS Action.

Back to Figure 3, when attempting to discover TDLS stations in the same BSS, a series of frame exchanges is used. STA Al, which is the initiator in the proposed scenario, sends a TDLS Discovery Request frame 311, tunneled through AP 111 (relay illustrated by the black dot), to an individual destination station, here STA BI.

This request frame conveys so-called "Link Identifier" element and "TDLS Multi-Link" element amongst the IEs of the Elements field 303. Other IEs forming the Elements field 303 are defined in Table 9-507 as defined in IEEE 802.11-REVme/D1.3 (June 2022).

The Link Identifier element is shown in Figure 4a under reference 400. It includes a BBSID field 401, a TDLS initiator STA address field 402 and a TDLS responder STA address field 403. The BSSID field 401 is set to the BSSID of the BSS of which TDLS initiator STA Al is a member, BSSID1 in the example as it corresponds to the affiliated AP AP1 111 with which TDLS initiator STA Al is associated. The TDLS initiator STA Address field 402 is set to the TDLS initiator's MAC address, which is the MLD MAC address of MLD A 120 in the context of MLD operations. The TDLS responder STA Address field 403 is set to the TDLS responder's MAC address, which is the MLD MAC address of MLD B 130 in the context of MLD operations. Such Link Identifier element is present in any type of TDLS Action frame. The MLD MAC address in the Link Identifier element therefore allows the STAs to recognize each other as the MLD MAC address of an MLD is its identity known by the wireless communication network 100.

The BSSID allows the STAs to identify the setup communication link for TDLS operation.

The TDLS Multi-Link element is shown in Figure 4b under reference 450. It is based on the structure of Multi-Link element introduced for supporting several links (e.g. Basic version is used for association of MLDs), and is therefore composed of: an Element ID 451 equal to 255, a Length field 452 defining the length of the Information Element, - an Element ID extension field 453 set to 107 identifying a multi-link 1E, - a Multi-link Control field 460 allowing the type of the multi-link IE to be defined as

TDLS (value:3) within the Type field 461,

a Common Info field 470 containing a Common Info Length field 471 and an AP MLD MAC address field 472 set to the MLD MAC address of the AP MLD with which the TDLS initiator non-AP MLD is associated, a Link info field 480 is reserved (that means not used).

As a result, the TDLS Multi-Link IE allows the initiator non-AP MLD to share its TDLS capabilities and the AP MLD MAC address of the AP MLD with which it is associated, in the multi-link environment. The responder non-AP MLD can thus check it is associated with the same AP MLD. In other words, an affiliated STA will only consider a TDLS Action frame if the frame carries a TDLS Multi-Link element 450 and the MLD MAC address carried in the AP MLD MAC Address field 472 of the TDLS Multi-Link element 450 matches the MLD MAC address of the AP MLD with which the non-AP MLD has already performed a multi-link setup.

This is the case for MLD B in the scenario of Figure 3.

Destination station STA B1 responds to the TDLS Discovery Request frame 311 with a TDLS Discovery Response frame 312, sent directly to STA Al (without relay by AP 111). This response frame conveys a "Link Identifier" element and a "TDLS Multi-Link" element amongst the IEs of the Elements field 303. Other IEs forming the Elements field 303 are defined in Table 9457 as defined in IEEE 802.11-REVme/D1.3 (June 2022).

From that point, STA Al and STA B1 know each other, meaning they know the other operates on the communication link setup with AP 111. They can then establish a TDLS direct link.

When attempting to establish a TDLS direct link over a single link with the discovered TDLS station, a series of TDLS Action frame exchanges is used to set up the single link TDLS direct link.

TDLS initiator STA Al first sends a TDLS Setup Request frame 313, tunneled through AP 111, to target TDLS responder STA Bl. This request frame conveys a "Link Identifier" element and a "TDLS Multi-Link" element amongst the IEs of the Elements field 303. Other IEs forming the Elements field 303 are defined in Table 9-497 as defined in IEEE 802.11-REVme/D1.3 (June 2022), which include information about the capabilities of TDLS initiator STA Al and an AID thereof.

TDLS responder STA B1 responds with a TDLS Setup Response frame 314, also tunneled through AP 111. This response frame conveys a "Link Identifier' element and a "TDLS Multi-Link" element amongst the IEs of the Elements field 303. Other IEs forming the Elements field 303 are defined in Table 9-498 as defined in IEEE 802.11-REVme/D1.3 (June 2022), which include information about the capabilities of TDLS responder STA B1, its AID plus a status code that either accepts or rejects the setup request.

If the Setup Request is accepted, TDLS initiator STA Al then sends a confirmation, TDLS Setup Confirm frame 315, still tunneled through AP 111. This confirmation frame conveys a "Link Identifier" element and a "TDLS Multi-Link" element amongst the IEs of the Elements field 303.

Other IEs forming the Elements field 303 are defined in Table 9-499 as defined in IEEE 802.11-REVme/D1.3 (June 2022).

This concludes the TDLS setup handshake. At this point, the two non-AP MLDs know the identity of the other on the one hand with their MLD MAC address and on the other hand with the AID assigned by the AP MLD.

The stations can then start to communicate directly over link 171 (direct or P2P link): P2P traffic 316 can then be directly (not black dot shown at the AP in the Figure for arrow 316) exchanged between STA Al and STA B1 using the established TDLS direct link. TDLS peers STA Al and STA B1 are then configured to accept Data frames received directly from the other peer. The frame exchanges are performed over the same link, that is to say the same frequency channel so that this P2P traffic becomes concurrent to other traffic for AP 110.

As mentioned above, several TDLS procedure can be executed on different setup links to establish multiple (single link) TDLS direct links on distinct setup links, and thus to setup a P2P communication session over multiple P2P links.

To optimize latency and throughputs, it can be useful to sort TIDs associated with P2P traffic, such as video, command and other data flows.

To do so, a P2P TID-To-Link mapping is negotiated between the two peer non-AP MLDs of the multi-link P2P session. In other words, a TID-To-Link mapping dedicated to the multiple P2P links is defined and signaled between the two MLDs. As apparent from the description below, the P2P TID-To-Link mapping may rely on the existing TID-To-Link Mapping mechanism to rely on existing IEs. It turns out that the peer non-AP MLDs may dynamically negotiate their common TID-To-Link mapping of the multiple P2P links during the lifetime of the multi-link P2P session.

Figure 5 illustrates, using a flowchart, general steps to manage a multi-link P2P session according to the embodiments of the invention. The illustrated flowchart can be implemented at both the P2P session initiator non-AP MLD and the P2P session responder non-AP MLD. It is assumed that the non-AP MLDs have set up multiple communication links with the AP MLD.

For ease of explanation, it is mainly made reference to the TDLS procedure to setup such multi-link P2P session.

At step 510, the two non-AP MLDs having setup links with the AP MLD establish together a peer-to-peer, P2P, or direct link communication session with the other, the P2P communication session being operative on multiple links, "P2P links", amongst the setup links.

This may be implemented by setting up two or more single link TDLS direct links, each one on a different setup link that is common between the two peer non-AP MLDs. Each TDLS direct link is setup by exchanging TDLS Action frames as explained above with reference to Figure 3.

One of the two non-AP MLDs can be the initiator of the P2P session establishment.

At step 520, one of the non-AP MLDs initiates, with the other peer non-AP MLD, a negotiation of a P2P TID-to-Link mapping for the multiple P2P links. In other words, the non-AP MLDs exchange mapping information, e.g. TID-to-Link Mapping IEs, to define which TID or TIDs is/are mapped to which P2P link, concerning the P2P data to be transmitted (exchanged).

This negotiation may take place during the establishment of the multi-link P2P session at step 510. That is, a TID-to-Link Mapping IE defining a proposed P2P TID-to-Link mapping may be included in at least one management frame used to establish the P2P communication session, typically in a TDLS Action frame setting up one of the single link TDLS direct links.

This negotiation or an additional negotiation (e.g. to change the current P2P TID-to-Link mapping) may take place during the lifetime of the established multi-link P2P session. That is, the TID-to-Link Mapping IE is exchanged after the P2P communication session is established. A TID-to-Link Mapping IE defining a proposed P2P TID-to-Link mapping may be exchanged after the P2P communication session is established. Dedicated frames, e.g. new TDLS Action frames, can be defined to carry the TID-to-Link Mapping IE defining the proposed P2P TID-to-Link.

Once the P2P TID-to-Link mapping has been defined, the peer non-AP MLDs can operate, at step 530, the multi-link P2P session given the agreed P2P TID-to-Link mapping. That is, the peer non-AP MLDs can directly communicate P2P data with the peer non-AP MLD through the multiple P2P links (of the multi-link P2P session) based on the negotiated TID-to-Link mapping. P2P data having TID n are transmitted and thus exchanged over the P2P link or one of the P2P links to which said TID n is mapped.

The arrow looping back from step 530 to step 520 illustrates how the P2P TID-to-Link mapping can be renegotiated between the two non-AP MLDs during the lifetime of the multi-link P2P session.

Renegotiation may take place when the network conditions evolve or any other criteria happens. Also renegotiation may occur when the multi-link P2P session evolve over time. As an example, e.g. a P2P link may be added (a new single link TDLS direct link is established) or may be removed (using a TDLS Teardown frame to end a current single link TDLS direct link).

In case of multi-link P2P session evolution, the P2P TID-to-Link mapping may first remain unchanged as long as the P2P TID-to-Link mapping is not renegotiated by the two MLDs. In that case, the new P2P link cannot be used until the mapping is renegotiated, and the TID mapped to the removed P2P link can no longer be transmitted (if there is no other P2P link to which the same TID is mapped) until the mapping is renegotiated.

Figures 6 and 7 illustrates more detailed operations of the process of Figure 5 in the context of the TDLS mechanism, respectively at a TDLS initiator non-AP MLD and a TDLS responder non-AP MLD, in accordance with embodiments of the present invention.

The "initiator" means, here, the peer non-AP MLD that initiates the P2P TID-to-Link mapping negotiation or re-negotiation. It may be the same as the initiator of a TDLS direct link establishment, e.g. when it uses the TDLS Discovery Request frame 311 or TDLS Setup Request frame 313 to initiate the negotiation.

As explained above, the processes of Figures 6 and 7 may take place during the setup of the multi-link P2P communication session (plural single link TDLS direct links) or take place after the multi-link P2P communication session has been established and is when it is operated by the two MLDs.

At step 610, the TDLS initiator non-AP MLD includes a TDLS Multi-Link IE in a TDLS Action frame to be transmitted, the IE signaling that a P2P TID-to-Link Mapping negotiation procedure is launched with the TDLS (responder) peer non-AP MLD addressee of the frame.

The TDLS Action frame may be any of the frames illustrated in Figure 3, preferably the TDLS Discovery Request frame 311 or TDLS Setup Request frame 313. As several single link TDLS direct links can be setup between the two MLDs to establish the multi-link P2P communication session, the signaling may be made in one (or more) TDLS Action frame of one of the TDLS direct link setups, e.g. the last TDLS direct link setup (forming the multi-link P2P session), or may be made in one (or more) TDLS Action frame of multiple (e.g. each) TDLS direct link setups. As an example, an initial request frame initiating a procedure to establish the P2P communication session, e.g. a TDLS Setup Request frame 313 is exchanged with the peer non-AP MLD, wherein the initial request frame includes a P2P TID-to-Link Mapping Negotiation Supported field set to a value indicating a P2P TID-to-Link mapping specific to the multiple P2P links is to be negotiated.

In variants, a new type of TDLS Request frame can be defined that is used after the multi-link P2P communication session has been established, to request a negotiation of the P2P TIDto-Link mapping.

Figure 8 illustrates a modified TDLS multi-link IE compared to Figure 4h, that carries a field dedicated to such signaling. Depicted P2P TID-to-Link Mapping Negotiation Supported field 873 is used to signal whether the P2P TID-to-Link mapping specific to the multiple P2P links is to be negotiated or not. Field 873 may be set to 1 to indicate the negotiation is starting.

In this implementation, the P2P TID-to-Link Mapping Negotiation Supported field 873 is included in the Common Info field 470 of the TDLS Multi-Link information element 800. Of course, other locations within the TDLS Action frame may be contemplated.

The TDLS Action frame carrying the P2P TID-to-Link Mapping Negotiation Supported field 873 is thus sent by the TDLS initiator non-AP MLD. It is received by the TDLS responder non-AP MLD at step 710.

The latter determines at step 720 from a received TDLS Action frame, whether a negotiation of the P2P TID-to-Link mapping for the established multi-link P2P session is launched, by checking the value of field 873. In the negative, the process ends. Otherwise, the TDLS responder non-AP MLD waits for a TID-to-Link Mapping IE 200 from the TDLS initiator non-AP MLD.

At step 620, the TDLS initiator non-AF' MLD provides the TDLS responder non-AP MLD with a proposed P2P TID-to-Link mapping. This starts the concrete negotiation of the mapping. Preferably, the proposed P2P TID-to-Link mapping defining a mapping of TIDs to the multiple P2P links of the P2P communication session is carried in a TID-to-Link Mapping information element, 1E, according to the IEEE 802.11 be/D2.0 standard. In that case, the Link Mapping of TID n fields 250-257 indicates the P2P link(s) (amongst those on which the multi-link P2P session is established) on which frames belonging to the TID n are allowed to be sent, if a default mapping is not used (Default Link Mapping field 242).

The proposed P2P TID-to-Link mapping may be included in the same TDLS Action frame as P2P TID-to-Link Mapping Negotiation Supported field 873, or in a subsequent TDLS Action frame. That means the TID-to-Link Mapping information element, IE defining the proposed P2P TID-to-Link mapping may be included in a frame setting up a single link TDLS direct link (forming part of the multi-link P2P session) or in a frame after the multi-link P2P session has been established.

The frame sent by the TDLS initiator non-AP MLD is received at step 730 by the TDLS responder non-AP MLD. The latter evaluates whether the proposed P2P TID-to-Link mapping is acceptable. Various criteria may be contemplated. For example, the TDLS responder non-AP MLD may check whether the proposed P2P TID-to-Link mapping matches the initial TID-to-Link mapping it has negotiated with the AP MLD for its setup links. In particular, it may check that a mapping of a TID to a P2P link as defined in the proposed P2P TID-to-Link mapping is allowed in its initial TID-to-Link mapping with the AP MLD. As an example, if the TDLS responder non-AP MLD has negotiated with the AP MLD that TID 4 is allowed only on Link 2, a proposed P2P TIDto-Link mapping specifying TID 4 on another P2P link than the one with Link ID = Link 2 cannot be accepted.

In variants, the proposed P2P TID-to-Link may be evaluated regardless of the initial TID-to-Link mapping with the AP MLD (i.e. be independent to the initial TID-to-Link mapping). This allows for an MLD to decorrelate the constraints with the AP MLD and with a peer non-AP MLD.

Of course, other criteria may be contemplated.

In some embodiments, the TDLS responder non-AP MLD may only accept or refuse the proposed P2P TID-to-Link mapping.

In other embodiments, the TDLS responder non-AP MLD may accept, refuse the proposal or also provide the TDLS initiator non-AP MLD with a counter-proposal of P2P TID-to-Link mapping, meaning a new (different) P2P TID-to-Link mapping is proposed in response. The new P2P TID-to-Link mapping may be a modified P2P TID-to-Link mapping, meaning that the unacceptable (as evaluated above) mappings between a TID and a P2P link, may be modified or deleted.

The response may therefore include a TID-to-Link Mapping information element, IE defining the counter-proposal of P2P TID-to-Link mapping, or not, depending on the implementation and response to be provided.

The response, which may be a TDLS Action frame such as a TDLS Discovery Response frame 312 or TDLS Setup Response frame 314 or a new type of response frame if provided after the multi-link P2P communication session has been established, is transmitted by the responder TDLS initiator non-AP MLD at step 740, which is received by the TDLS initiator non-AP MLD at step 630.

The exchange may optionally include a confirmation frame (e.g. a TDLS Setup Confirm frame 315 or the like) to acknowledge the response (and possibly the counter-proposal therein).

Additional exchanges may be implemented if needed to converge to a P2P TID-to-Link mapping acceptable for both MLDs (shown through the dotted arrows back to steps 620 and 730).

When they finally agree on the P2P TID-to-Link mapping, they both store the agreed mapping in their local memory at steps 640 (TDLS initiator non-AP MLD) and 750 (TDLS responder non-AP MLD) in order to use it for their P2P communications (step 530 above). Steps 620-630-640 on one hand and steps 730-740-750 on the other hand may be repeated (shown through the arrows back to steps 620 and 730) during the lifetime of the multi-link P2P communication session to renegotiate the P2P TID-to-Link mapping, as already introduced above.

Figure 9 illustrates an exemplary 802.11be multi-link reference model for a MLD either AP MLD or non-AP MLD.

The MLD comprises a PHY layer 900, a MAC layer 920, a logical link control (LLC) sublayer and upper layers.

Upper layers may include applications that generate traffic data or use received traffic data, for example P2P data packets such as a video stream.

The transmission and the reception of the traffic data are handled by the MAC 920 and PHY 900 layers. Such transmission and the reception of the traffic data may take place over multiple links 90-x, 90-y, 90-z, as the ones 151, 152, 161, 162 introduced with reference to Figure 1, as well as over single link TDLS direct links 171, 172 when established. The references to 2.4 GHz, 5 GHz and 6 GHz at the bottom of the Figure are only provided for illustrative purposes. The links may be implemented on another set of bands and/or within the same band.

Three links and therefore three affiliated stations are shown in the Figure. Of course, other configurations including two affiliated stations or more than three affiliated stations may be contemplated.

The traffic data are provided by the upper layers as a sequence of data frames, or 'traffic stream". Each traffic stream and thus each data frame is associated with an access category (AC) as defined in the EDCA mechanism.

The data frames, also known as MAC service data units (MSDUs), incoming from an upper layer of the protocol stack are mapped, by a classifier, onto one of the four ACs and thus input in a queue of the mapped AC for transmission.

The 802.11be multi-link reference model reflects the fact that MLDs may transmit and receive using several links, particularly at the level of the MAC layer 920 and the PHY layer 900.

The MAC layer 920 comprises one Unified Upper-MAC (UMAC) layer 930, multiple Lower-MAC (LMAC) layers 920-x, 920-y, 920-z coupled with a respective PHY layer 900-x, 900y, 900-z, each couple corresponding to a link 90-x, 90-y, 90-z.

The UMAC 930 performs functionalities that are common across all links and each LMAC 920-x, 920-y, 920-z performs functionalifies that are local to each link 90-x, 90-y, 90-z. The UMAC layer then offers a UMAC interface with the link-specific blocks 920-x, 920-y, 920-z and also provides a UMAC Service Access Point (SAP) to the LLC and upper layers.

The UMAC 930 is responsible for link-agnostic MAC procedures such as authentication, association, security association, sequence number assignments, MAC Protocol Data Unit (MPDU) encryption/decryption, aggregation/de-aggregation, acknowledgement score boarding procedure, etc. Each data unit, MSDU, arriving at the MAC layer 920 from an upper layer (e.g. Link layer) with a type of traffic (User Priority (UP) hence Traffic Identifier (TID)) priority is mapped onto one of the ACs according to the mapping rule at the UMAC layer 930. Then, still at the UMAC layer 930, the data unit, MSDU, is provided with the next sequence number available and is stored in the queue corresponding to its TID (or UP) within the mapped AC.

The UMAC 930 is provided with a MLD MAC address uniquely identifying the MLD as a whole.

Each LMAC 920-x, 920-y, 920-z is in charge of link specific functionalities like the channel access. In particular, each MLD Lower MAC includes its own contention-based channel access procedure. Some of the functionalities require joint processing of both the UMAC 930 and LMACs 920-x, 920-y, 920-z.

Each LMAC 920-x, 920-y, 920-z is provided with a dedicated STA MAC address to communicate over its respective link or channel. One of the STA MAC address may be equal to the MLD MAC address of the MLD, or all the STA MAC addresses may be different one from the other and from the MLD MAC address.

An affiliated STA entity in the MLD is therefore made of specialized PHY and LMAC layers and share the UMAC layer, as is shown through references 901-x and 901-z.

Each LMAC layer 920-x, 920-y, 920-z implements a TID-to-Link Mapping function 921-x, 921-y, 921-z that handles the TID-to-Link mapping set with the AP MLD, for the data transmitted on the respective links 90-x, 90-y, 90-z. Specific to the invention, the TID-to-Link Mapping function 921-x, 921-y, 921-z also handles the P2P TID-to-Link mapping for the P2P communication of the respective affiliated STAs (hence links) with the peer MLD.

The affiliated STA entities 111-121-131 (idem 112-122-132) compete one against each other on their common channel using a conventional EDCA (Enhanced Distributed Channel Access) contention scheme, to access the wireless medium in order to be granted a transmission opportunity (TXOP) and then to transmit (single-user, SU) data frames. The affiliated STAs 121131 (idem 122-132) may also use a multi-user (MU) scheme in which the affiliated AP 111 (idem 112) of the AP MLD 110 is allowed to schedule a MU transmission, i.e. multiple simultaneous transmissions to or from the stations of its BSS, in the wireless network. One implementation of such a MU scheme has been for example adopted in IEEE Std 802.11ax-2021 standard, as the Multi-User Uplink and Downlink OFDMA (MU UL and DL OFDMA) procedures.

On top of the Figure, application layer block 1221 runs an application that generates and receives data packets, for example P2P data packets such as a video stream. Application layer block 1221 represents all the stack layers above MAC layer according to ISO standardization.

Figure 10 schematically illustrates a communication device 1000, in particular a non-AP MLD embedding a plurality of affiliated non-AP stations, of a radio network NETW, configured to implement at least one embodiment of the present invention. The communication device 1000 may preferably be a device such as a micro-computer, a workstation or a light portable device. The communication device 1000 comprises a communication bus 1013 to which there are preferably connected: a central processing unit 1001, such as a processor, denoted CPU; a memory 1003 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 1002 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 1004.

Preferably the communication bus provides communication and interoperability between the various elements included in the communication device 1000 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 1000 directly or by means of another element of the communication device 1000.

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 1002, in order to be stored in the memory of the communication device 1000 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).

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 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 (16)

1. CLAIMS1. A communication method in a wireless network, comprising, at a non-access point, non-AP, multi-link device, MLD having setup links with an AP MLD: establishing a peer-to-peer, P2P, communication session with a peer non-AP MLD, the P2P communication session being operative on mulfiple links, "P2P links", amongst the setup links, negotiating, with the peer non-AP MLD, a P2P TID-to-Link mapping specific to the multiple P2P links, and directly communicating with the peer non-AP MLD through the multiple P2P links based on the negotiated TID-to-Link mapping.
2. 2. The method of Claim 1, wherein establishing the P2P communication session includes exchanging, with the peer non-AP MLD, an inifial request frame initiating a procedure to establish the P2P communication session, wherein the initial request frame includes a P2P TID-to-Link Mapping Negotiation Supported field set to a value indicating a P2P TID-to-Link mapping specific to the multiple P2P links is to be negotiated.
3. 3. The method of Claim 1, wherein negotiating the P2P TID-to-Link mapping includes exchanging, with the peer non-AP MLD, a TID-to-Link Mapping information element, IE, according to the IEEE 802.11be/D2.0 standard and defining a mapping of TIDs to the multiple P2P links of the P2P communication session.
4. 4. The method of Claim 3, wherein the TID-to-Link Mapping IE is included in at least one management frame used to establish the P2P communication session.
5. 5. The method of Claim 3, wherein the TID-to-Link Mapping IE is exchanged after the P2P communication session is established.
6. 6. The method of Claim 1, further comprising negotiating, with the AP MLD, an initial TID-to-Link mapping that maps TIDs to the setup links, and matching the P2P TID-to-Link mapping with the initial TID-to-Link mapping.
7. 7. The method of Claim 6, wherein matching the P2P TID-to-Link mapping with the initial TID-to-Link mapping includes checking that a mapping of a TID to a P2P link is allowed in the initial TID-to-Link mapping.
8. 8. The method of Claim 1, wherein establishing a P2P communication session includes establishing at least one Tunneled Direct Link Setup, TDLS, direct link with the peer non-AP MLD, by exchanging TDLS Action frames.
9. 9. The method of Claim 8, wherein a TDLS Discovery Request frame or a TDLS Setup Request frame of the TDLS Acfion frames includes a P2P TID-to-Link Mapping Negotiation Supported field set to a value indicating a P2P TID-to-Link mapping specific to the multiple P2P links is to be negotiated.
10. 10. The method of Claim 9, wherein the P2P TID-to-Link Mapping Negotiation Supported field is included in a Common Info field of a TDLS Multi-Link information element.
11. 11. The method of Claim 8, wherein the P2P TID-to-Link mapping is carried in a dedicated information element within at least one of the TDLS Action frames.
12. 12. A wireless communication device comprising at least one microprocessor configured for carrying out the method of Claim 1.
13. 13. A Tunneled Direct Link Setup, TDLS, Action frame used to establish a TDLS direct link forming part of a peer-to-peer, P2P; communication session between non-AP stations or MLDs, comprising a TID-to-Link information element, 1E, signaling a mapping of TIDs to P2P links on which the P2P communication session is operative.
14. 14. The TDLS Action frame of Claim 13, wherein the TID-to-Link IE is as defined in the IEEE 802.11be/D2.0 standard.
15. 15. The TDLS Action frame of Claim 13, further comprising a Common Info field in a TDLS Multi-Link information element wherein the Common Info field includes a P2P TID-to-Link Mapping Negotiation Supported field set to a value indicating a P2P TID-to-Link mapping specific to the multiple P2P links is to be negotiated.
16. 16. 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.