The present invention generally relates to wireless communications and more specifically to Multi-Link (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 stations. With the development of latency sensitive applications such as online gaming, realtime 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/D1.0 version (May 2021) introduces the Multi-Link (ML) Operation (MLO). MLO improves data throughput by allowing communications between stations over multiple concurrent and non-contiguous communication links.

Multi-Link Operation (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 links with the AP MLD. Each 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. Multiple links can also be reconfigured during MLO, e.g. a link added or removed, without requiring a disassociation between the non-AP MLD and the AP MLD. 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 stations. The affiliated stations in both AP MLD and non-AP-MLD can use 802.11 mechanisms to communicate with affiliated stations of another MLD over each of the multiple communication links that are set up.

As defined in the D1 .0 standard, a non-AP MLD may operate in a so-called EMLSR (Enhanced Multi-Link Single Radio) mode on the enabled links between the non-AP MLD and its associated AP MLD. This mode is directed to non-AP MLD operating with a single radio with a view of providing throughput enhancement and latency reduction. The single-radio non-AP MLD listens to two (or more) pre-configured channels (links) simultaneously, but switches on one single link for exchanging data with the AP MLD.

Also, a non-AP MLD may operate in a so-called EMLMR (Enhanced Multi-Link Multi- Radio) mode on a specified set of the enabled links between the non-AP MLD and its associated AP MLD. The specified set of the enabled links in which the EMLMR mode is applied is called EMLMR links. This mode is directed to non-AP MLD operating with multiple radios with a view of providing throughput enhancement and latency reduction.

The multi-radio non-AP MLD supporting and activating this EMLMR mode is able to aggregate the physical resources, typically the antennas, of different radios used on different links to temporarily upgrade its performance on one link. As example, for a multi-radio non-AP MLD supporting the EMLMR mode on two links (with associated radios), when the EMLMR mode is desactivated, the non-AP MLD communicates on the two different links using the two radios, for example in a 2x2 MIMO antenna configuration.

On the other hand, when the EMLMR mode is activated, the non-AP MLD communicate on one of the two links using one of its radio with the aggregated physical resources of the two radios, i.e. a 4x4 MIMO antenna configuration in this example. In the meantime, the other link (deprived of its physical antenna) cannot be used. In other words, an activation of the EMLMR mode introduces some constraints on and dependences between the EMLMR links.

SUMMARY OF INVENTION

The EMLMR capability is managed by the non-AP MLD on its side, at its affiliated non-AP stations. Therefore, to efficiently use the enabled links given the constraints on the EMLMR links, the AP MLD needs to know which enables links form part of the EMLMR links, for instance to avoid sending data on the links deprived of their physical antennas in case of EMLMR activation.

In this context, embodiments of the invention provide a communication method in a wireless network, comprising at a multi-radio non-access point, non-AP, multi-link device, MLD: signaling Enhanced Multi-Link Multi-Radio, EMLMR, links to an AP MLD, wherein the signaling of an EMLMR link is included in a Per-STA profile subelement of the concerned link in a management frame sent to the AP MLD.

Correspondingly, a communication method in a wireless network, comprises at an access point, AP, multi-link device, MLD: receiving, from a non-AP MLD, signaling of Enhanced Multi-Link Multi-Radio, EMLMR, links, wherein the signaling of an EMLMR link is included in a Per-STA profile subelement of the concerned link in a management frame received from the non-AP MLD.

The present invention thus proposes to signal the EMLMR links at link level, rather than at MLD level. This advantageously avoids signaling again the EMLMR links at each change in the MLD configuration, such as when a link is removed or modified or created (for instance through the reconfiguration procedure). On the contrary, the signaling of the invention is restricted to only the EMLMR link or links affected by the change. For instance, when the link configuration changes do not affect EMLMR links, there may be no need to send any signaling of EMLMR links. Hence, bandwidth is saved.

Optional features of these embodiments of the invention are defined in the appended claims. Some of these features are explained here below with reference to a method, while they can be transposed into device features.

In some embodiments, the management frame is exchanged over a link with an affiliated AP of the AP MLD, and each EMLMR link other than this link for exchange is signalled in the concerned Per-STA profile subelement.

In specific embodiments, a signaling of whether the link for exchange is an EMLMR link or not is included in an EML Capabilities field of the management frame.

In some embodiments, the signaling specifies an EMLMR link set from a plurality of sets.

In specific embodiments, the signaling includes a first subfield that indicates to which EMLMR link set the concerned link belongs.

In more specific embodiments, the signaling includes a second subfield indicating whether the first subfield is included in the Per-STA profile.

In some embodiments, the signaling includes a first subfield which takes value from amongst a set of predefined values, one of the predefined values being used to signal in a Per- STA profile subelement of another link that the other link is not an EMLMR link.

In some embodiments, the Per-STA subelement includes a link ID uniquely identifying an affiliated AP of the AP MLD and a profile of an affiliated non-AP station of the non- AP MLD, both affiliated AP and non-AP station forming the concerned link.

In some embodiments, the management frame is one of a ML association request frame and a ML reconfiguration request frame.

Although the above embodiments allows signaling plural EMLMR link sets in the Per- STA subelements of the links, other embodiments of the invention expands this signaling of plural EMLMR link sets at any level. This advantageously expands possibilities of having parallel (simultaneous or overlapping) EMLMR modes for plural sets of EMLMR links.

In this context, the other embodiments provide a communication method in a wireless network, comprising at a multi-radio non-access point, non-AP, multi-link device, MLD: signaling Enhanced Multi-Link Multi-Radio, EMLMR, links to an AP MLD, wherein the signaling associates an EMLMR link to an EMLMR link set from a plurality of sets.

Correspondingly, a communication method in a wireless network, comprises at an access point, AP, multi-link device, MLD: receiving, from a non-AP MLD, signaling of Enhanced Multi-Link Multi-Radio, EMLMR, links, wherein the signaling associates an EMLMR link to an EMLMR link set from a plurality of sets.

In some embodiments, the signaling is included in an EML Capabilities subelement of a management frame sent to the AP MLD.

In some embodiments, the EML Capabilities subelement is included in a Common Info field of a ML association request frame or a ML reconfiguration request frame.

In some embodiments, the signaling includes a subfield per Link ID corresponding to an affiliated AP of the AP MLD, each subfield indicating to which EMLMR link set the link corresponding to the Link ID belongs. For instance, the subfield may be a bitmap, the bits of which are associated with respective EMLMR link sets.

In other embodiments, the signaling includes a subfield per EMLMR link set, each subfield indicating which link or links with the AP MLD belongs to the associated EMLMR link set. For instance, the subfield may be a bitmap, the bits of which are associated with respective Link IDs, i.e. with respective links between affiliated non-AP stations and affiliated APs corresponding to the Link IDs. The signaling may further includes a subfield indicating the number of EMLMR link sets.

For all the embodiments above, the MLDs perform appropriate ML operations.

In embodiments at the multi-radio non-AP MLD, the method may further comprise performing ML operations in an EMLMR mode on a set of signaled EMLMR links.

In embodiments at the multi-radio non-AP MLD, the method may further comprise performing ML operations based on the signaled EMLMR links when an EMLMR mode is activated by the non-AP station.

In some embodiments, performing ML operations based on the signaled EMLMR links includes exchanging first data with the non-AP MLD over a first EMLMR link of an EMLMR link set and controlling local resources not to transmit second data over a second EMLMR link of the EMLMR link set as long as the EMLMR mode is activated.

Correlatively, the invention also provides a wireless communication device comprising at least one microprocessor configured for carrying out the steps of any of the above methods. The wireless communication device is thus either a non-AP MLD or an AP MLD.

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 defined above.

At least parts of the methods according to the invention may be computer implemented. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit", "module" or "system". Furthermore, the present invention may take the form of a computer program product embodied in any tangible medium of expression having computer usable program code embodied in the medium.

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

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of example only, and with reference to the following drawings in which:

Figure 1 illustrates a typical 802.11 network environment involving ML transmissions;

Figure 2 schematically illustrates an exemplary sequence of management frames for operating the ML discovery and ML setup procedure when establishing a Multi-Link transmission as well as the ML reconfiguration procedure;

Figure 3 illustrates the Basic variant Multi-Link Element included in ML Discovery management frames as specified in document IEEE P802.11 be/D1.0;

Figure 4 illustrates the EML Capabilities field of Figure 3 as specified in document IEEE P802.11 be/D1.0;

Figure 5 illustrates Per-STA profile subelements in Basic variant and Reconfiguration variant Multi-Link Element included in ML Discovery and ML Reconfiguration management frames as specified in documents IEEE P802.11be/D1.0 and IEEE 802.11- 21/534r3, respectively; Figure 6 illustrates the Reconfiguration variant Multi-Link Element included in ML reconfiguration management frames as specified in document IEEE 802.11-21 /534r3;

Figure 7 illustrates modified Per-STA profile subelements and a modified EML Capabilities field for the Basic variant ML element including the signaling of EMLMR links sets according to embodiments of the invention; Figure 8 illustrates modified Per-STA profile subelements and a modified EML

Capabilities field for the Reconfiguration variant ML element including the signaling of EMLMR links sets according to embodiments of the invention; Figure 9 illustrates modified EML Capabilities fields for both the Basic variant and the Reconfiguration variant ML element including the signaling of EMLMR links sets according to embodiments of the invention;

Figure 10 illustrates, using two flowcharts, general steps implementing embodiments of the present invention at a non-AP MLD and at an AP MLD, respectively;

Figure 11 schematically illustrates an EMLMR capable architecture for an MLD to implement embodiments of the invention; and

Figure 12 shows a schematic representation of a wireless communication device in accordance with embodiments 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 stations. A TDMA system may allow multiple user terminals to share the same frequency channel by dividing the transmission signal into different time slots or resource units, each time slot being assigned to different user terminal. An OFDMA system utilizes orthogonal frequency division multiplexing (OFDM), which is a modulation technique that partitions the overall system bandwidth into multiple orthogonal sub-carriers or resource units. These sub-carriers may also be called tones, bins, etc. With OFDM, each sub-carrier may be independently modulated with data. 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., 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).

While the examples are described in the context of WiFi (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 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 stations that together organize their accesses to the wireless medium for communication purposes. The stations (including the AP) form a service set, here below referred to as basic service set, BSS (although other terminology can be used). A same physical station 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.

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 802.11 be, as illustrated by draft IEEE P802.11 be/D1.0 of May 2021 (below D1.0 standard), 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 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 Access Point Multi-Link Device (or AP MLD) then corresponds to a MLD where each station (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 station (STA) affiliated with the MLD is a non-AP STA, referred to as “affiliated non-AP station”. 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 stations 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 links established 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 stations 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) 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.

However, a non-AP MLD may have less radio stacks or chains compared to the number of links enabled with the associated AP MLD. For instance, two or more or all the affiliated non-AP stations of the non-AP MLD can be implemented through a single radio in the non-AP MLD. In that case, the latter may operate in a so-called EMLSR (Enhanced Multi-Link Single Radio) mode on the corresponding links between the non-AP MLD and its associated AP MLD. The non-AP MLD listens to the two or more or all pre-configured links simultaneously, but switches on one single link of these links for exchanging data with the AP MLD.

More efficient are the multi-radio non-AP MLDs which have preferably a radio chain or stack per link to be configured or enabled with the associated AP MLD. Hence, a non-AP MLD may operate in a so-called EMLMR (Enhanced Multi-Link Multi-Radio) mode on a specified set of the enabled links between the non-AP MLD and its associated AP MLD. The specified set of the enabled links in which the EMLMR mode is applied is called EMLMR links.

The multi-radio non-AP MLD supporting and activating this EMLMR mode is able to aggregate the physical resources, typically the antennas, of different radios used on different links to temporarily upgrade its performance on one link. As example, for a multi-radio non-AP MLD supporting the EMLMR mode on two links (with associated radios), when the EMLMR mode is desactivated, the non-AP MLD communicates on the two different links using the two radios, for example in a 2x2 MIMO antenna configuration.

On the other hand, when the EMLMR mode is activated, the non-AP MLD communicate on one of the two links using one of its radio with the aggregated physical resources of the two radios, i.e. a 4x4 MIMO antenna configuration in this example. In the meantime, the other link (deprived of its physical antenna) cannot be used. In other words, an activation of the EMLMR mode introduces some constraints on and dependences between the EMLMR links. Figure 1 illustrates a typical 802.11 network environment involving ML transmissions in which the present invention may be implemented.

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.

AP MLD 110 has multiple affiliated APs, four affiliated APs 111 , 112, 113 and 114 (also referenced AP1 , AP2, AP3, AP4 respectively) in the exemplary Figure, 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 stations, each of which behaves as an 802.11 non-AP station in a BSS (managed by an affiliated AP 111 , 112, 113, 114) to which it registers. In the exemplary Figure, three non-AP STAs 121 , 122 and 123 (also referenced A1 , A2, A3 respectively) are affiliated with non-AP MLD 120 and four non-AP STAs 131 , 132, 133 and 134 (also referenced B1 , B2, B3 and B4 respectively) are affiliated with non- AP MLD 130.

In the scenario of the invention, non-AP MLD 130 is a multi-radio non-AP MLD. Non- AP MLD 120 is either a multi-radio non-AP MLD or a single-radio non-AP MLD.

For illustrative purpose, AP 111 is set to operate on channel 10 corresponding to an operating 20 MHz channel in the 2.4 GHz frequency band, AP 112 is set to operate on channel 36-40 corresponding to an operating 40 MHz channel in the 5 GHz frequency band, AP 113 is set to operate on channel 149-153 corresponding to an operating 40 MHz channel in the 5GHz frequency band too, and AP 114 is set to operate on channel 301 corresponding to an operating 160 MHz channel in the 6GHz frequency band. In this example, the affiliate stations operate on various frequency bands.

Each affiliated AP offers a link towards the AP MLD 110 to the affiliated non-AP stations. 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 111-114 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 station of the non-AP MLD. Each link enables individual channel access and frame exchanges between the non-AP MLD and the AP MLD based on the supported capabilities exchanged during association.

The discovery phase is referred below to as ML discovery procedure, and the multilink setup phase (or association phase) is referred below to as ML setup procedure. 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.

The network information of an affiliated AP may include all or part of capabilities and operation parameters.

Typically, the network information contains at least the operating class, the channel number and the BSSID of the affiliated AP. It may also include more complete information elements related to its capabilities and operational parameters. The capability elements may indicate inter alia one or more of high-throughput (HT) capabilities, very high-throughput (VHT) capabilities, high efficiency (HE) capabilities, HE 6 GHz Band capabilities, or extremely high- throughput (EHT) capabilities. The operating elements may indicate inter alia one or more of HT operation parameters, VHT operation parameters, HE operation parameters, EHT operation parameters, enhanced distributed channel access (EDCA) parameters, multi-user (MU) EDCA parameters, uplink (UL) orthogonal frequency division multiple access (OFDMA) random access (UORA) parameters, target wait time (TWT) parameters, fast initial link setup (FILS) parameters, or spatial reuse (SR) 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 stations 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 accepted, 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 links (communication channels) with their corresponding affiliated APs.

For illustrative purpose, in wireless communication network 100, three candidate setup links have been requested by non-AP MLD 120 to AP MLD 110 and have been accepted by AP MLD 110: a first link 151 between affiliated AP 111 (AP1) and affiliated non-AP STA 121 (A1), a second link 152 between affiliated AP 112 (AP2) and affiliated non-AP STA 122 (A2), and a third link 153 between affiliated AP 114 (AP4) and affiliated non-AP STA 123 (A3).

Similarly, four candidate setup links have been requested by multi-radio non-AP MLD 130 to AP MLD 110 and have been 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), a third link 163 between affiliated AP 113 (AP3) and affiliated non-AP STA 133 (B3) and a fourth link 164 between affiliated AP 114 (AP4) and affiliated non-AP STA 134 (B4).

During the ML setup procedure, the non-AP MLDs can declare part or all of their capabilities. For instance, they may declare their EMLSR capability and/or EMLMR capability. As described below, appropriate fields are provided in the management frames, for instance in the ML Association Request frame 221 .

In a scenario, non-AP MLD 120 does not support the EMLMR mode. Hence, it indicates this lack of EMLMR capability (non-support of EMLMR mode) to AP MLD 110 during the ML setup procedure. To this purpose, it may use the EMLMR support field of the EML Capabilities field located in the Common info field of the Basic variant ML element 200a carried in a ML Association Request frame (as defined in the D1.0 standard) sent by non-AP MLD 120 to AP MLD 110.

Similarly, multi-radio non-AP MLD 130 supports the EMLMR mode. Hence, it indicates this EMLMR capability (support of EMLMR mode) to AP MLD 110 during the ML setup procedure, using the same EMLMR support field.

Once the links have been setup and capabilities been exchanged, the non-AP MLDs 120, 130 perform Multi-Link Operation (MLO) with their associated AP MLD 110. An example of MLO is an exchange of frames (uplink and/or downlink communication).

During MLO, the non-AP MLD may activate the EMLSR or EMLMR mode if appropriate.

In the scenario of the Figure, non-AP MLD 130 supports the EMLMR mode between:

- on one hand, the radio of its affiliated non-AP STA 131 (B1) and the radio of its affiliated non- AP STA 132 (B2), and

- on the other hand, the radio of its affiliated non-AP STA 133 (B3) and the radio of its affiliated non-AP STA 134 (B4).

Two sets of EMLMR links are thus implemented in non-AP MLD 130, each depicted in the Figure as a dashed rectangle.

To activate the EMLMR mode, non-AP MLD 130 sends an EHT Action frame to AP MLD 110, typically an EML Operating Mode Notification frame with its EMLMR Mode subfield equal to 1 . Once the EMLMR mode is activated:

- the affiliated non-AP STA 131 (B1) communicates in the EMLMR mode on its link 161 by aggregating the antenna resources of its radio and the antenna resources of the radio of the affiliated non-AP STA 132 (B2). In the meantime, the affiliated non-AP STA 132 (B2) can no longer use its link 162 (this link is represented using a dashed line). In this example, links 161 and 162 belong to a first set of EMLMR links;

- the affiliated non-AP STA 133 (B3) communicates in the EMLMR mode on its link 163 by aggregating the antenna resources of its radio and the antenna resources of the radio of the affiliated non-AP STA 134 (B4). In the meantime, the affiliated non-AP STA 134 (B4) can no longer use its link 164 (also represented in dashed line). In this example, links 163 and 164 belong to a second set of EMLMR links.

After the ML discovery procedure and ML setup procedure have been completed, some changes on the setup links may be necessary during the runtime of the network 100 due to different reasons such as interferences from another incoming BSS, congestion on one or several links, changes in data traffic loads and so on...

A ML Reconfiguration procedure as described in document 802.11 -21 /534r3 allows modifying the configuration of the links between a non-AP MLD and its associated AP, without dissociation. This is a set of post-association procedures through which an AP MLD and an associated non-AP MLDs can make changes to their multi-link (ML) configuration, or the set of links between their affiliated STAs, while the non-AP MLD stays in the associated state throughout the procedure.

As examples, a non-AP MLD can request to add and/or delete multiple links to the AP MLD it is associated with; an AP MLD can add multiple APs to or remove multiple APs from its multi-link operation; an AP MLD can indicate deletion of one or more links to an associated non-AP MLD; an AP MLD can prompt an associated non-AP MLD to request to add and/or delete multiple links, and provide a recommended configuration.

Management frames, namely ML Reconfiguration Request and ML Reconfiguration Response frames, are used that include only the parameters related to the added, deleted and modified links. The reconfiguration request can be initiated by the non-AP MLD.

The management frames can be exchanged on an enabled link, while data are simultaneously exchanged over another link and/or a new additional link is being added between the concerned non-AP MLD and associated AP MLD.

The ML Reconfiguration Request frame includes an EML Capabilities field (comprising an EMLMR support field). Hence, the non-AP MLD is also able to provide its EML Capabilities, for instance its EMLMR capability or not, to its associated AP MLD during the ML Reconfiguration procedure.

Figure 2 schematically illustrates an exemplary sequence of management frames for operating the ML discovery and ML setup procedure when establishing a ML transmission between AP MLD 110 and non-AP MLD 130.

In order to establish a ML transmission, the non-AP MLD initiates the ML discovery procedure 210 to retrieve the available links proposed by AP MLD 110. This can be done through passive and/or active scanning operations on frequency channels in one or more of the frequency bands (typically 2.4 GHz, 5 GHz and 6 GHz bands).

The passive scanning consists in listening ML beacon frames 213 sent periodically by an affiliated AP of AP MLD 110 (AP1 in the example) on its operation channel. Each or part or all of the affiliated APs can periodically send ML beacon frames on its operating channel.

The active scanning consists in an exchange of management frames between the non-AP MLD and the AP MLD. In particular, the non-AP MLD transmits (through its affiliated non- AP stations) a ML probe request frame 211 on each channel to be scanned by its affiliated non- AP stations 131 , 132, 133 and 134 and listens for the reception of ML probe response frames 212 from the AP MLD (by the respective affiliate APs on its operating channel). A ML probe request frame 211 can be transmitted by each affiliated non-AP station overthe operating channel on which it is configured.

The ML probe request frame 211 allows the affiliated non-AP station to request an affiliated AP to include, in addition to its network information, the complete or partial set of capabilities and operation elements (i.e. network information) of other APs affiliated with the same AP MLD.

The affiliated stations involved in the management frame exchange are referred to as “reporting” affiliated stations, while the other affiliated stations of the same MLDs are referred to as “reported” affiliated stations.

Therefore, in the example of Figure 2, reporting affiliated non-AP station 131 (B1) sends the ML Probe Request frame 211 to reporting affiliated AP 111 (AP1) to obtain the network information of AP1 as well as the network information of the reported affiliated APs 112, 113, 114 (AP2, AP3, AP4).

Although the example shows AP1 111 and station B1 131 as reporting affiliated stations, any other pair of affiliated stations operating on the same operating channel (e.g. AP4 with B4) can be used as reporting affiliated stations.

The ML Probe Request frame 211 is a Probe Request frame as defined in 802.11 ax (for example IEEE P802.11ax/D8.0 of October 2020) augmented with a Probe Request variant Multi-Link element as defined in IEEE P802.11 be/D1 .0.

Upon receiving the ML Probe Request 211 , AP MLD 110 shall respond with a ML Probe Response 212 which carries the requested network information for its targeted affiliated APs as indicated in the ML Probe Request 211 .

The ML Probe Response 212 is a Probe Response frame as defined in 802.11 ax (for example IEEE P802.11ax/D8.0 of October 2020) augmented with a Basic variant Multi-Link element as defined in IEEE P802.11 be/D1.0. The Basic variant Multi-Link element carries complete or partial per-STA profile(s), based on the soliciting request, for each of the requested AP(s) affiliated with AP MLD 110.

Thanks to ML Probe Responses 212 advertising the profiled of the affiliated APs, non-AP MLD 120 and 130 are aware (discovery) of the various affiliated APs available at AP MLD 110 and of their network information. In a conventional manner, this information helps non-AP MLDs to choose the BSSs their affiliated non-AP stations should register to (i.e. should join).

The passive scanning through ML beacon frames 213 provides the same information. In this respect, ML beacon frames sent by the affiliated AP can carry the same ML element additional to convention 802.11 ax fields conveying network information of the reporting affiliated AP. Preferably, ML beacon frame 213 provides all the network information (Complete Profile) for all the affiliated APs.

The ML Discovery procedure provided non-AP MLD 130 with information on the available affiliated APs of AP MLD 110. Next, non-AP MLD 130 initiates a ML setup procedure 220 to setup the links to be involved in the ML transmission to establish, referred to as “setup links”. The ML setup procedure consists in an exchange of ML Association Request and ML Association Response frames between the reporting non-AP station (B1 131 in the example) affiliated with non-AP MLD 130 and the reporting AP (AP1 111 in the example) affiliated with AP MLD 110.

To prepare the ML Association Request 221 , the reporting affiliated non-AP station B1 determine which candidate setup links should be requested to AP MLD 110 (through reporting affiliated AP AP1) based on the information obtained during the ML Discovery procedure.

Once the candidate setup links are known, the non-AP MLD requests AP MLD 110 to setup those links. This is done by sending, by any (reporting) affiliated non-AP station of the non-AP MLD, the ML Association Request frame indicating the candidate setup links with affiliated APs of the AP MLD that are requested for ML setup.

ML Association Request frame 221 is an Association Request frame as defined in 802.11 ax (for example IEEE P802.11ax/D8.0 of October 2020) augmented with a Basic variant Multi-Link element 300a as illustrated in Figure 3 and defined in IEEE P802.11 be/D1.0.

The 802.11ax fields of the Association Request frame are used in a conventional way, for instance to request the association of the reporting affiliated non-AP station (here B1 131) with the addressee reporting affiliated AP (here AP1 111). This defines a requested setup link defined between the reporting affiliated non-AP station and a reporting affiliated AP addressee of the ML Association Request frame.

MAC header of frame 221 sets the transmitting address TA to the MAC address of the reporting affiliated non-AP station B1 and the destination address RA to the MAC address of the destination affiliated AP AP1 .

Basic variant Multi-Link element 300a includes Element ID field 301 , Length field 302 (enabling to know the presence or not of the optional fields as well as the number of Per-STA profiles in field 330), Element ID Extension field 303, Multi-Link Control field 310, optional Common Info field 320a and optional Link Info field 330.

Multi-Link Control field 310 includes a Type subfield 311 , a Reserved subfield 312 and a Presence Bitmap subfield 340a. The Type subfield 311 is set to value 0 in order to signal the Multi-Link element 300 is a Basic variant ML element.

Presence Bitmap subfield 340a is used to indicate which subfields are included in Common Info field 320a. Presence Bitmap subfield 340a thus includes a MLD MAC Address Present subfield 341 , a Link ID Info Present subfield 342, a BSS Parameters Change Count Present subfield 343, a Medium Synchronization Delay Information Present subfield 344, an EML Capabilities Present subfield 345, a MLD Capabilities Present subfield 346 and a Reserved subfield 347.

MLD MAC Address Present subfield 341 is set to 1 if a MLD MAC Address field is present in the Common Info field 320a; otherwise, the subfield is set to 0.

Link ID Info Present subfield 342 is set to 1 if a Link ID Info subfield is present in the Common Info field 320a; otherwise, Link ID Info Present subfield is set to 0 BSS Parameters Change Count Present subfield 343 is set to 1 if a BSS Parameters Change Count subfield is present in the Common Info field 320a; otherwise, BSS Parameters Change Count Present subfield is set to 0.

Medium Synchronization Delay Information Present subfield 344 is set to 1 if a Medium Synchronization Delay Information subfield is present in the Common Info field 320a; otherwise, Medium Synchronization Delay Information Present subfield is set to 0.

EML Capabilities Present subfield 345 is set to 1 if an EML Capabilities field is present in the Common Info field 320a; otherwise, EML Capabilities Present subfield is set to 0.

MLD Capabilities Present subfield 346 is set to 1 if a MLD Capabilities subfield is present in the Common Info field 320a. Otherwise, the MLD Capabilities Present subfield is set to 0.

According to the values specified in Presence Bitmap subfield 340a, Common Info field 320a includes optionally a MLD MAC Address subfield 321 , a Link ID Info subfield 322, a BSS Parameters Change Count subfield 323, a Medium Synchronization Delay Information subfield 324, an EML Capabilities subfield 325 and a MLD Capabilities subfield 326.

Those various fields are described in the standard. For instance, Link ID Info subfield 322 includes a Link ID subfield 322a and a Reserved field 322b. Link ID Info subfield in the Common info field is not present if the Basic variant Multi-Link element is sent by the non-AP STA, as it is the case for a ML association Request 221 .

Of interest for embodiments of the present invention, EML Capabilities subfield 325 is used to declare the non-AP MLD's capabilities in terms of enhanced multi-link, in particular regarding EMLSR and EMLMR.

As shown in Figure 4, Enhanced Multi-Link (EML) Capabilities subfield 325 of Common Info field 320a includes an EMLSR Support field 401 , an EMLSR Delay field 402, an EMLMR support field 403, an EMLMR Delay field 404, a Transition Timeout field 405, a Reserved field 406, an EMLMR Rx NSS field 407 and an EMLMR Tx NSS field 48.

EMLSR Support field 401 indicates support of the EMLSR operation for the MLD. EMLSR Support field 251 is set to 1 if the MLD supports the EMLSR operation; otherwise it is set to 0.

EMLSR Delay field 402 indicates the MAC padding duration of the Padding field of the initial Control frame. EMLSR Delay subfield is 3 bits and set to 0 for 0 ps, set to 1 for 32 ps, set to 2 for 64 ps, set to 3 for 128 ps, set to 4 for 256 ps, and the values 5 to 7 are reserved.

EMLMR Support field 403 indicates support of the EMLMR operation for the MLD. EMLMR Support field is set to 1 if the MLD supports the EMLMR operation; otherwise it is set to 0.

EMLMR Delay field 404 indicates the minimum padding duration required for a non- AP MLD for EMLMR link switch when operating in EMLMR mode. When EMLMR Delay subfield 404 is included in a frame sent by a non-AP STA affiliated with a non-AP MLD, EMLMR Delay subfield is set to 0 for 0 ps, set to 1 for 32 ps, set to 2 for 64 ps, set to 3 for 128 ps, set to 4 for 256 ps, and the values 5 to 7 are reserved. When EMLMR Delay subfield 404 is included in a frame sent by an AP affiliated with an AP MLD, EMLMR Delay subfield is set to 0.

Transition Timeout field 405 indicates the timeout value for EML Operating Mode Notification frame exchange in EMLMR mode. When Transition Timeout field 405 is included in a frame sent by an AP affiliated with an AP MLD, Transition Timeout field 405 is set to 0 for 0 TU, set to 1 for 1 TU, set to 2 for 2 TUs, set to 3 for 4 TUs, set to 4 for 8 TUs, set to 5 for 16 TUs, set to 6 for 32 TUs, set to 7 for 64 TUs, set to 8 for 128 TUs, and the values 9 and 15 are reserved. When Transition Timeout field 405 is included in a frame sent by a non-AP STA affiliated with a non-AP MLD, Transition Timeout subfield is set to 0.

EMLMR Rx NSS field 407 indicates the maximum receive Nss (Number of spatial stream) that is supported by the non-AP MLD in the EMLMR mode.

EMLMR Tx NSS field 408 indicates the maximum transmit Nss (Number of spatial stream) that is supported by the non-AP MLD in the EMLMR mode.

More details on these fields can be found in the D1 .0 standard.

Back to Figure 3 depicting Basic variant Multi-Link element 300a, Link Info field 330 contains a set of subelements. Only two subelements formats are available for the Basic variant Multi-Link element: a first format identified by a Subelement ID set to 0 corresponding to a Per- STA Profile subelement and a second one identified by a Subelement ID set to 221 corresponding to a Vendor Specific subelement.

In the example of the Figure, Link Info field 330 contains a set 331 of Per-STA Profile subelements 350a gathering several Per-STA profiles. The Per-STA Profile subelements are used by reporting non-AP station B1 to indicate which links corresponding non-AP MLD 130 whishes to establish with AP MLD 110. Each Per-STA Profile subelement 350a is used to specify one specific desired link, by indicating which affiliated AP is targeted and which affiliated non-AP STA is concerned.

As shown in Figure 5, a Per-STA Profile subelement 350a of the Link Info field 330 consists of a Per-STA Control Field 360 and of Profile subelements 370.

Per-STA Control field 360 includes a Link ID subfield 361 , a Complete Profile subfield 362, a MAC Address Present subfield 363, a Beacon Interval Present subfield 364, a DTIM Info Present subfield 365, a NSTR Link Pair Present subfield 366, a NSTR Bitmap Size subfield 367 and a Reserved field 368. Link ID subfield 361 is set to the Link ID of the targeted affiliated AP for the desired link.

Profile subelements 370 includes several subelements not shown in the Figure, for instance a Subelement ID subfield, a Length subfield and two STA profile subfields. The goal of Profile subelements 370 is to provide all the network information elements of the affiliated non- AP station corresponding to the desired link.

All these fields are described in the D1 .0 standard.

The pair {Link ID subfield 361 , Per-STA Profile subelements 370} thus indicates an affiliated AP and an affiliated non-AP station, hence defining a desired link. Although a large number of fields has been described with reference to Figures 3- 5, some of the fields may be omitted and some may be added. Of interest for embodiments of the invention are the EML Capabilities subfield 325 and Per-STA Profile subfield 350a.

Back to Figure 2, a similar ML Association Request 221 may be sent by affiliated non-AP station 121 (11) of non-AP MLD 120, which defines candidate setup links to be established between its affiliated non-AP STAs and the affiliated APs of AP MLD 110 (for example those shown in Figure 1.

In the scenario of Figure 1 , non-AP MLD 120 requests three links (151 , 152, 153) to be established while non-AP MLD 130 requests four links (161 to 164). AP MLD 110 may accept or refuse the link proposal of non-AP MLDs 120, 130. It provides its decision by sending ML Association Response 222 responsive to the reception of ML Association Request 221. In the scenario, all requested candidate setup links are accepted and then enabled (i.e. setup).

ML Association Response 222 is an Association Response frame as defined in 802.11 ax (for example IEEE P802.11ax/D8.0 of October 2020) augmented with a Basic variant Multi-Link element, defined in IEEE P802.11 be/D1.0.

The ML setup procedure between non-AP MLD 130 and AP MLD 110 thus terminates with the establishment of one or more setup links. In this situation, non-AP MLD 130 becomes in associated state with AP MLD 110 and is assigned an AID for wireless communication over the multiple enabled links. Non-AP MLD 130 then configures its affiliated non-AP stations for ML transmitting/receiving through the established setup links.

Next, the Multi-Link Operation (MLO) 230, i.e. exchange of frames, can take place on the established setup links.

During MLO 230, non-AP MLD 130 may activate the EMLMR mode to improve throughput over some links. It is done by sending an EHT Action frame 231 to AP MLD 110, typically an EML Operating Mode Notification frame with its EMLMR Mode subfield equal to 1 .

In the scenario shown, affiliated non-AP STA 131 sends frame 231 to activate the EMLMR mode. As defined in the D1 .0 standard, AP 111 responds by a similarframe. The EMLMR mode may be activated for a predefined duration. The EMLMR mode is activated for each EMLRM link set. In the first set, EMLRM link 161 is enhanced by aggregating the antenna resources of non-AP STA B2 132, meaning EMLRM link 162 is no longer operating. In the second set, EMLRM link 163 is enhanced by aggregating the antenna resources of non-AP STA B4 134, meaning EMLRM link 164 is no longer operating.

Also during MLO 230, AP MLD 110 and/or non-AP MLD 130 may decide modifying their link configuration, for instance by adding a new link, deleting a link, modifying a link, ... To that end, the MLD requesting the reconfiguration sends a ML Reconfiguration request frame 241 to the other MLD.

In the scenario shown, non-AP MLD 130 initiates the reconfiguration through its non- AP STA B1 131. The reconfiguration may also happen while data transmission occurs on other links (here 163 and 164 not impacted by the reconfiguration for instance). As defined in document IEEE 802.11-21 /534r3, the ML Reconfiguration request frame is defined as a Protected EHT Action frame with its Protected EHT Action field set to 7. It has quite a similar format to the management frames and comprises a Reconfiguration variant Multi-Link element 300b as illustrated in Figure 6 and defined in IEEE 802.11-21 /534r3. The fields and subfields of the ML element 300b that are similar to those of Figure 3 are labelled with the same numeral reference.

Similar to ML element 300a, Reconfiguration variant Multi-Link element 300b includes Element ID field 301 , Length field 302 (enabling to know the presence or not of the optional fields as well as the number of Per-STA profiles in field 330), Element ID Extension field 303, Multi-Link Control field 310, a Common Info field 320b and optional Link Info field 330.

Multi-Link Control field 310 includes a Type subfield 311 , a Reserved subfield 312 and a Presence Bitmap subfield 340b. Type subfield 311 is set to value 2 in order to signal that the Multi-Link element 300b is a Reconfiguration variant ML element.

Presence Bitmap subfield 340b includes an EML Capabilities Present subfield 345, a MLD Capabilities Present subfield 346 and a Reserved subfield 347.

EML Capabilities Present subfield 345 is set to 1 if an EML Capabilities field is present in the Common Info field 320b; otherwise, EML Capabilities Present subfield is set to 0.

MLD Capabilities Present subfield 346 is set to 1 if a MLD Capabilities subfield is present in the Common Info field 320b; otherwise, MLD Capabilities Present subfield is set to 0.

According to the values specified in Presence Bitmap subfield 340b, the Common Info field 320b includes optionally an EML Capabilities subfield 325 and a MLD Capabilities subfield 326, as described above. In particular, EML Capabilities subfield 325 follows the format of Figure 4.

Compared to Figure 3, the Per-STA Profile subelements 350b of the Link Info field 330 follow another slightly different format as shown in Figure 5.

Per-STA Profile subelement 350b also consists of a Per-STA Control Field 360 and of Profile subelements 370.

Per-STA Control field 360 includes a Link ID subfield 361 , a Complete Profile subfield 362, a New Link ID subfield 500, a Delete Request subfield 501 and a Reserved field 368.

For instance, New Link ID subfield 500 identifies a new AP that the non-AP MLD is requesting to associate the subject non-AP STA with, or is set to 15 if the non-AP MLD is not making a request to create a new link. The subfield is reserved when the Delete Request subfield 501 is nonzero.

Delete Request subfield 501 is set to 1 to request to delete the link to the subject non-AP STA, and set to 0 otherwise. The subfield is reserved when New Link ID subfield 500 is not 15.

Profile subelements 370 are similar to those of Figure 3 and aims at providing all the network information elements of the affiliated non-AP station subject to the link of the Per6STA Profile subelement 350b. Thanks to the Reconfiguration variant Multi-Link element 300b, the non-AP MLD are also able to declare their EML capabilities (EMLSR and EMLMR) to the AP MLD during the ML Reconfiguration procedure, although they are already associated.

For example, non-AP MLD 120 indicates to AP MLD 110 during the ML Reconfiguration procedure, that it does not support the EMLMR mode through the EMLMR support field 403 of the EML Capabilities field 325 located in the Common info field 320b of the Reconfiguration variant ML element 300b carried in an ML Reconfiguration Request frame 241 sent by non-AP MLD 120 to AP MLD 110.

Similarly, multi-radio non-AP MLD 130 indicates to AP MLD 110 during the ML Reconfiguration procedure, that it supports the EMLMR through the EMLMR support field 403 (the same as above) carried in an ML Reconfiguration Request frame 241 sent by non-AP MLD 130 to AP MLD 110.

Back to Figure 2, AP MLD 110 (and more generally the addressee MLD) may accept or refuse the reconfiguration proposal of non-AP MLD 130. It provides its decision by sending ML Reconfiguration Response 242 responsive to the reception of ML Reconfiguration Request 241 .

As shown with the scenario of Figure 1 , when the EMLMR mode is activated on one EMLMR link, the other EMLMR links belonging to the same set of EMLMR links cannot be used. As the activation of the EMLMR mode introduces some constraints and dependence between the EMLMR links, it is preferable for a non-AP MLD supporting this mode to signal its set or sets of EMLMR links to the AP MLD.

Specific signaling may thus be proposed.

Embodiments shown in Figures 7 and 8 signaling EMLMR links to the AP MLD, wherein the signaling of an EMLMR link is included in the Per-STA profile subelement of the concerned link in a management frame exchanged with the AP MLD.

Figure 7 concerns more specifically such a signaling in a Basic variant ML element 300a of typically a ML association request frame 221 . Figure 8 concerns more specifically such a signaling in a Reconfiguration variant ML element 300b of typically a ML Reconfiguration request frame 241 .

In both cases, as the Per-STA profile subelements 350a concern all the requested link other that the link on which the management frame is exchanged, each EMLMR link other than this link for exchange is preferably signalled in the concerned Per-STA profile subelement. The same signaling fields may signal when a link (defined in a Per-STA profile subelement) is not an EMLMR link.

The modified Per-STA profile subelement 350a' of Figure 7 illustrates a first embodiment for the Basic variant ML element to signal an EMLMR link. The fields and subfields of the modified Per-STA profile subelement 350a’ that are similar to those of Figure 5 are labelled with the same numeral reference. The modified Per-STA profile subelement 350a' is similar to the Per-STA profile 350a with the addition of an EMLMR Links Sets field 700. The latter may be added to the Per-STA Control Field 360. In a variant, it is included in the Per-STA Profile subelements 370.

EMLMR Links Sets field 700 is present in the modified Per-STA profile subelement 350a’ when the EMLMR support field 403 is set to 1 .

EMLMR Links Sets field 700 is advantageously used by the non-AP MLD to signal its EMLMR links sets to AP MLD.

EMLMR Links Sets field 700 may be a one-bit field, a two-bit field or more generally a n-bit field.

In a first variant, EMLMR Links Sets field 700 is one-bit width and is used to signal whether the link defined by the Per-STA profile subelement (through the Link ID subfield 361 defining the affiliated AP and the Profile subelements 370 defining the affiliated non-AP STA) is EMLMR or not. It means that this signaling is used when the non-AP MLD has only one set of EMLMR links.

For example, EMLMR Links Sets field 700 is set to 0 to report that the affiliated non- AP STA of this Per-STA profile does not belong to the set of EMLMR capable non-AP STAs in the non-AP MLD. As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is not an EMLMR link, i.e. it is not part of the EMLMR links set.

EMLMR Links Sets field 700 is set to 1 to report that the affiliated non-AP STA of this Per-STA profile belongs to the set of EMLMR capable non-AP STAs in the non-AP MLD. As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is an EMLMR link, i.e. it is part of the EMLMR links set.

In a second variant, EMLMR Links Sets field 700 is still one-bit width and is used to signal to which EMLMR links set the link defined by the Per-STA profile subelement belongs. As the field has two possible values, this signaling is used when the non-AP MLD has two sets of EMLMR links.

For example, EMLMR Links Sets field 700 is set to 0 to report that the affiliated non- AP STA of this Per-STA profile belongs to a first set of EMLMR capable non-AP STAs in the non- AP MLD. As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is an EMLMR link of a first EMLMR links set.

EMLMR Links Sets field 700 is set to 1 to report that the affiliated non-AP STA of this Per-STA profile belongs to a second set of EMLMR capable non-AP STAs in the non-AP MLD. As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is an EMLMR link of a second EMLMR links set.

An additional bit may be provided, if necessary, to signal those links that are not EMLMR links (e.g. using bit 701 below).

In a third variant, EMLMR Links Sets field 700 is two-bit width and is used to signal whether the link defined by the Per-STA profile subelement is EMLMR or not, and in the affirmative to which EMLMR links set it belongs. It means that this signaling is used when the non-AP MLD has only at most three sets of EMLMR links. For example, EMLMR Links Sets field 700 is set to 00 to report that the affiliated non-AP STA of this Per-STA profile does not belong to the set of EMLMR capable non-AP STAs in the non-AP MLD. As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is not an EMLMR link, i.e. it is not part of any EMLMR links set.

EMLMR Links Sets field 700 is set to 01 to report that the affiliated non-AP STA of this Per-STA profile belongs to a first set of EMLMR capable non-AP STAs in the non-AP MLD. As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is an EMLMR link, i.e. it is part of a first EMLMR links set.

EMLMR Links Sets field 700 is set to 10 to report that the affiliated non-AP STA of this Per-STA profile belongs to a second set of EMLMR capable non-AP STAs in the non-AP MLD. As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is an EMLMR link, i.e. it is part of a second EMLMR links set.

EMLMR Links Sets field 700 is set to 11 to report that the affiliated non-AP STA of this Per-STA profile belongs to a third set of EMLMR capable non-AP STAs (if any) in the non- AP MLD. As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is an EMLMR link, i.e. it is part of a third EMLMR links set (if any).

In a fourth variant, EMLMR Links Sets field 700 is still two-bit width, but (similar to the second variant) it is only used to signal to which EMLMR links set (from amongst four sets) the link defined by the Per-STA profile subelement belongs.

For example, EMLMR Links Sets field 700 is set to 00 to report that the affiliated non-AP STA of this Per-STA profile belongs to a fourth set of EMLMR capable non-AP STAs in the non-AP MLD (rather than reporting non-EMLMR capability of the non-AP STA). As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is an EMLMR link, i.e. it is part of a fourth EMLMR links set.

An additional bit may be provided, if necessary, to signal those links that are not EMLMR links (e.g. using bit 701 below).

In a fifth variant that generalizes this approach to any integer n (1 , 2, 3, 4, ...), EMLMR Links Sets field 700 is n-bit width and is used: to report that the affiliated non-AP STA of this Per-STA profile does not belong to the set of EMLMR capable non-AP STAs in the non-AP MLD (if value of field 700 is 0 for example). As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is not an EMLMR link, i.e. it is not part of any EMLMR links set. The signaling thus includes a first subfield 700 which takes value from amongst a set of predefined values, one of the predefined values being used to signal in a Per-STA profile subelement that the corresponding link is not an EMLMR link, and to report that the affiliated non-AP STA of this Per-STA profile belongs to a k-th set of EMLMR capable non-AP STAs in the non-AP MLD (if value of field 700 is k). As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is an EMLMR link, i.e. it is part of a k-th EMLMR links set. Such signaling can be used when the non-AP MLD has 2 ⁿ -1 sets of EMLMR links.

In a sixth variant, instead of signaling non-EMLMR capability of the non-AP STA using value 0, such value may be used to report that the affiliated non-AP STA of this Per-STA profile belongs to a 2 ⁿ -th set of EMLMR capable non-AP STAs in the non-AP MLD (if value of field 700 is k). As a result, the Link identified in the Link ID field 361 in this same Per-STA profile is an EMLMR link, i.e. it is part of a 2 ⁿ -th EMLMR links set. Such signaling can be used when the non-AP MLD has 2 ⁿ sets of EMLMR links.

An additional bit may be provided, if necessary, to signal those links that are not EMLMR links (e.g. using bit 701 below).

In these embodiments with n>1 , the signaling specifies an EMLMR link set from a plurality of sets. Except when the additional bit is used, the signaling of these embodiments includes only a first subfield that indicates to which EMLMR link set the concerned link belongs.

The modified Per-STA profile subelement 350a" of Figure 7 illustrates a second embodiment for the Basic variant ML element to signal an EMLMR link.

EMLMR Links Sets field 700 as above is provided in Per-STA Profile subelements 370. In variant, it may be provided in Per-STA Control field 360.

The signaling of the second embodiment includes a second subfield 701 , called EMLMR Links Sets Present field (one-bit width), indicating whether EMLMR Links Sets field 700 is included in the Per-STA profile 350a”.

EMLMR Links Sets Present field 701 is present in the Control Field of the Per-STA profile 350a” when EMLMR support field 403 is set to 1 .

EMLMR Link Sets field 700 is present when EMLMR Links Sets Present field 701 is set to 1 ; otherwise it is absent.

Any of the variants of the first embodiment can be used for EMLMR Link Sets field 700 in the second embodiment. As EMLMR Links Sets Present field 701 equal to 0 implicitly indicates when the link is not EMLMR link (because no EMLMR Link Sets field 700 is provided), preference is given to the above variants where the possible values of EMLMR Link Sets field 700 only indicate one of the EMLMR links sets. This increases the number (2 ⁿ ) of EMLMR links sets that can be signalled.

As explained above, an EMLMR Link Sets field 700 in each Per-STA Profile subelement 360 only signals the EMLMR nature (or not) of the links other than the link over which the management frame is exchanged.

An additional signaling may thus be provided to signal whether the link for such exchange is an EMLMR link or not. Preferably, it is included in an EML Capabilities field of the management frame as shown in Figure 7. It may however be located in other fields of the Basic variant ML Element 320a.

Modified EML Capabilities subfield 325' of Figure 7 includes, in addition to those fields of Figure 4, an EMLMR Link Sets field 750 that is similar to above-described EMLMR Link Sets field 700: the value of this field indicates whether the link over which the management frame is exchanged is an EMLMR Link or not (if value is 0) and in the affirmative (value not zero) to which EMLMR links set this link belongs. In variant, EMLMR Link Sets field 700 may only indicate an EMLMR links set, without the possibility to only signal the link for the exchange is not EMLMR. In that case an additional bit (such as EMLMR Links Sets Present field 701) may be added, to signal whether EMLMR Link Sets field 750 is present, hence whether the link is EMLMR or not.

An exemplary signaling of the EMLMR links and EMLMR link sets in the Reconfiguration variant ML element 300b of typically a ML Reconfiguration request frame 241 is described with reference to Figure 8. This allows providing the EMLMR link indication even when reconfiguring the links between a non-AP MLD and an associated AP MLD.

The same approaches as above for the Basic variant ML element 300a apply:

- an EMLMR Link Sets field 700 can be added to the Per-STA Control field 360 (or in a variant to the Per-STA Profile subelements 370). It is 1 , 2 or n-bit width to signal whether the concerned link is EMLMR or not, and in the affirmative to which EMLMR link set it belongs. As an alternative, the field may only indicate an EMLMR link set (without the option of value 0 to indicate a link is not EMLMR). This corresponds to field 350b’,

- or the EMLMR Link Sets field 700 with the additional EMLMR Links Sets Present field 701 . This corresponds to field 350b”, and

- an EMLMR Link Sets field 750, possibly in the EML Capabilities field 325’, to signal the EMLMR nature of the link over which the management frame is exchanged is an EMLMR Link or not (if value is 0) and in the affirmative (value not zero) to which EMLMR links set this link belongs. An additional EMLMR Links Sets Present field 701 may also be added to have EMLMR Link Sets field 700 only indicating an EMLMR link set (without the option of value 0 to indicate the link for management frame exchange is not EMLMR).

The embodiments of Figures 7 and 8 offer the same EMLMR link signaling format for the ML Association Request frames 221 and the ML Reconfiguration Request frames 241 , and advantageously avoid systematically providing again the sets of EMLRM links when a reconfiguration of the links occurs. Indeed, as the signaling is made in fields specific to each link and not at MLD-level fields, when no EMLRM link is impacted by a reconfiguration, there is no need to re-signal the EMLRM links.

Furthermore, although they may signal a single set of EMLRM links (see the first variant for example), they advantageously allows plural EMLRM links sets to be reported, and not only one. The signaling thus associates an EMLMR link (preferably each EMLMR link specified in the management frame except the link over which the frame is exchanged) to an EMLMR link set from a plurality of sets

Other embodiments to signal plural EMLRM links are now described with reference to Figure 9. These embodiments advantageously provide the signaling in the same location for all links, including the link over which the frame is exchanged.

In these embodiments, the signaling is included in the EML Capabilities subelement variant or Reconfiguration variant ML element conveyed in a ML association request frame 221 or a ML reconfiguration request frame 241 .

In a third embodiment shown by modified EML Capabilities subelement 325’, the signaling includes a subfield 900-i per Link ID “i” corresponding to an affiliated AP of the AP MLD, each subfield 900-i indicating to which EMLMR link set the link “i" corresponding to the Link ID belongs.

Modified EML Capabilities subelement 325’ is similar to the EML Capabilities subelement 325 of Figure 4, with the only addition of one EMLMR Links Sets field 900-i for each link connection requested (they can already been set up in case of reconfiguration for instance) by the non-AP MLD to the AP MLD. The ordering of the EMLMR links Sets field 900-i is assumed to start from the link ID = 0 and being contiguous up to n (the number of affiliated APs of AP MLD minus 1). As an example, the EMLMR Links Sets field 900-0 signals the EMLMR link set of the link 0, the EMLMR Links Sets field 900-n-1 signals the EMLMR link set of the link n- 1 and the EMLMR Links Sets field 900-n signals the EMLMR link set of the link n.

The EMLMR Links Sets fields 900-i are present in the EML capabilities 325’ when EMLMR support field 403 is set to 1 .

In a first variant of the third embodiment, each EMLMR Links Sets field 900-i is one- bit width and is used to signal to which EMLMR links set (from amongst two sets) the link “i" (i.e. involving affiliated AP “i") belongs.

For example, EMLMR Links Sets field 900-i is set to 0 to report that the link with Link ID = i is an EMLMR link of a first EMLMR links set.

EMLMR Links Sets field 900-i is set to 1 to report that the link with Link ID = i is an EMLMR link of the second EMLMR links set.

In a second variant, each EMLMR Links Sets field 900-i is two-bit width and is used to signal whether the corresponding link (i.e. with Link ID = i) is EMLMR or not, and in the affirmative to which EMLMR links set it belongs.

For example, EMLMR Links Sets field 900-i is set to 00 to report that the link with Link ID = i is not an EMLMR link, i.e. it is not part of any EMLMR links set.

EMLMR Links Sets field 900-i is set to 01 to report that the link with Link ID = i is an EMLMR link and it belongs to a first EMLMR links set.

EMLMR Links Sets field 900-i is set to 10 to report that the link with Link ID = i is an EMLMR link and it belongs to a second EMLMR links set.

EMLMR Links Sets field 900-i is set to 11 to report that the link with Link ID = i is an EMLMR link and it belongs to a third EMLMR links set (if any).

In a third variant, the value 00 is no longer used to indicate a non-EMLMR link, but report that the link with Link ID = i belongs to a fourth EMLMR links set (if any).

In a fourth variant that generalizes this approach to any integer n (1 , 2, 3, 4, ...), each EMLMR Links Sets field 900-i is n-bit width and is used: to report that the link with Link ID = i is not an EMLMR link, i.e. it is not part of any EMLMR links set, and to report that the link with Link ID = i is an EMLMR link and belongs to the i-th EMLMR links set.

Such signaling can be used when the non-AP MLD has at most 2 ⁿ -1 sets of EMLMR links.

In a fifth variant, instead of signaling the EMLMR nature or not of the link with Link ID = i using value 0, such value may be used to report that the link with Link ID = i (is an EMLMR link and) belongs to the 2 ⁿ -th EMLMR links set. Such signaling can be used when the non-AP MLD has 2 ⁿ sets of EMLMR links.

In a fourth embodiment shown by modified EML Capabilities subelement 325”, the signaling includes a subfield 950-j per EMLMR link set “j", each subfield indicating which link or links with the AP MLD belongs to the associated EMLMR link set. The subfield 950-j can be a mere bitmap, the bit b, of which providing a signaling for the link with Link ID = i (i.e. involving affiliates AP “i"). Hence, the bitmap has a bit width at least equal to the number of Link IDs. Preferably, it is 8 or 16-bit width. Of course, other widths can be used.

Modified EML Capabilities subelement 325” is similar to the EML Capabilities subelement 325 of Figure 4, with the only addition of one EMLMR Links Bitmap 950-j for each set “j” of EMLMR links. The ordering of the EMLMR Links Bitmaps 950-j is assumed to start from the first EMLMR links set (j=1) up to the m ^th EMLMR links set (j=m). As example, EMLMR Links Bitmap 950-1 signals the first set of EMLMR links, EMLMR Links Bitmap 950-m-1 signals the (m- 1) ^th set of EMLMR links and EMLMR Links Bitmap 950-m signals the m ^th set of EMLMR links.

The EMLMR Links Bitmaps 950-j are present in the EML capabilities 325” when EMLMR support field 403 is set to 1 .

In a first variant of the fourth embodiment, EMLMR Links Bitmaps 950-j are 8-bit width and are used to provide the following signaling: the bit b, at the index i in the EMLMR Link Bitmap 950-j is set to 1 if the link with Link ID = i belongs to the j-th EMLMR links set.

In a second variant, it is 16-bit width and provide the same signaling.

The number of EMLMR links sets may be predefined or known in advance, for example exchanged in a previous frame. In some embodiments, the number of EMLMR links sets is specified in modified EML Capabilities subelement 325”, using EMLMR Sets Number field 051. This allows the AP MLD to know the number of bitmaps 950-j, hence to correctly parse the fields of the received frame.

Figure 10 illustrates, using two flowcharts, general steps implementing embodiments of the present invention at a non-AP MLD and at an AP MLD, respectively.

As far as non-AP MLD is concerned, step 1000 is triggered when the non-AP MLD contemplates sending a management frame, such as a ML association request frame 221 or a ML Reconfiguration request frame 241 . Step 1000 consists for the non-AP MLD in retrieving the EMLMR properties of each of its affiliated non-AP STAs (hence of each link already setup and/or to be requested) and the EMLMR Links set to which they belong. This step may restrict the retrieving to the sole links concerned by the management frame, in particular for the first and second embodiments above (Figures 7 and 8) where the signaling is made at link level.

Next, at step 1005, the non-AP MLD signals (by sending the management frame) the EMLMR links to the AP MLD using any of the signaling format proposed above.

Next, at step 1010, the non-AP MLD performs ML operations 230 with the AP MLD, in respect of the signaled EMLMR links and associated EMLMR Links sets. In particular, when the EMLMR mode is activated, the non-AP MLD controls that the aggregation of antenna resources is made within the same EMLMR Links set.

On the AP MLD side, step 1050 consists in receiving a management frame comprising the above signaling of the EMLMR links.

At step 1055, the AP MLD performs ML operations 230 with the non-AP MLD having sent the management frame, in respect of the received signaled EMLMR links and associated EMLMR Links sets. In particular, when the EMLMR mode is activated, if first data are exchanged with the non-AP MLD over a first EMLMR link of a first EMLMR link set, the AP MLD controls local resources such as its radio chain or stack not to transmit second data over a second EMLMR link of the same first EMLMR link set, as long as the EMLMR mode remains activated.

Figure 11 schematically illustrates an EMLMR capable architecture for an MLD. This Figure takes the example of two affiliated non-AP STAs sharing their antenna resources when the EMLMR mode is activated.

The architecture comprises two radio stacks, one for each non-AP STA.

A radio stack comprises a full 802.11 be MAC module 1100a or 1100b (exchanging data with higher layers), a full 802.11 be PHY module 1105a or 1105b connected with the MAC module, a radio-frequency chain 1110a or 1110b connected with the PHY module, an EMLMR switch 1115 shared by the two radio stacks and configured to perform the aggregation of the antenna resources when the EMLMR mode is activated, and an antenna array 1120a or 1120b.

The diagram on the bottom left illustrates the functioning when the EMLMR mode is disabled: the common EMLMR switch 1115 connects each antenna array to its RF chain. Hence, each radio stack is complete and can serve a respective link using for example a 2x2 MIMO antenna configuration. As shown in the Figure, two links are available.

The diagram on the bottom right illustrates the functioning when the EMLMR mode is activated: the common EMLMR switch 1115 aggregates the antenna resource to the first link. To do so, it connects the antenna array 1120b of the second radio stack to the RF chain 1110a of the first radio stack. Hence, the first radio stack can operate in a 4x4 MIMO antenna configuration to improve the throughput of link 1 . On the other hand, link 2 can no longer be used as its antenna array 1120b is no longer available for the second radio stack. Although the illustrative aggregation of the antenna resources deprives the second radio stack of all its antenna resources in the EMLMR mode, it may be contemplated that the EMLMR mode only aggregate a part of these antenna resources to the first radio stack.

Figure 12 schematically illustrates a communication device 1200, typically any of the MLDs discussed above, of a wireless network, configured to implement at least one embodiment of the present invention. The communication device 1200 may preferably be a device such as a micro-computer, a workstation or a light portable device. The communication device 1200 comprises a communication bus 1213 to which there are preferably connected: a central processing unit 1201 , such as a processor, denoted CPU; a memory 1203 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 two communication interfaces 1202 and 1202’ connected to the wireless communication network, for example a communication network according to one of the IEEE 802.11 family of standards, via transmitting and receiving antennas 1204 and 1204’, respectively.

Preferably the communication bus 1213 provides communication and interoperability between the various elements included in the communication device 1200 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 1200 directly or by means of another element of the communication device 1200.

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 1202 or 1202’, in order to be stored in the memory of the communication device 1200 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.