GB2632129A

GB2632129A - Improved discovery of P2P groups using assistance of APs in infrastructure networks

Info

Publication number: GB2632129A
Application number: GB2311357.4A
Authority: GB
Inventors: Viger Pascal; Guignard Romain
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2023-07-24
Filing date: 2023-07-24
Publication date: 2025-01-29
Also published as: GB202311357D0; WO2025021896A1

Abstract

Mechanisms that favour discovery of communication groups managed by soft access points (APs), e.g. peer-to-peer (P2P) groups controlled by P2P group owners. A first station, belonging to a group managed by a first AP and operating on a first channel, obtains group-related information, and sends a group announcing frame that includes the group-related information to second APs over respective second channels. A second AP, operating a basic service set (BSS) on a second channel, receives, over a second channel, a group announcing frame that includes group-related information describing a group managed by a first AP operating on a first channel. In response, the second AP generates a reported-AP element, and sends, over a second channel, a frame including the reported-AP element to advertise the group within the BSS. A second station, operating on a second channel, receives, from a second AP, a frame including a reported-AP element advertising a group managed by a first AP and configured to operate on a first channel. The second station switches the operating channel from the second to the first channel and joins the group of the first channel.

Description

IMPROVED DISCOVERY OF P2P GROUPS USING ASSISTANCE OF APS IN INFRASTRUCTURE NETWORKS

FIELD OF THE INVENTION

The present invention relates generally to communication networks and more specifically to improved discovery of communication groups, such as Peer-to-Peer (P2P) groups or BSS, in wireless networks having ever more channels.

The invention finds particular applications in the access of an 802.11be/bn standard network.

BACKGROUND OF THE INVENTION

The discovery process of surrounding access points, APs, is an unavoidable procedure in wireless networks, be them infrastructure or ad-hoc (non-infrastructure) networks, to provide seamless connectivity to the stations. Once an AP is known, the stations can associate to it, hence join a communication group or basic service set (BSS) within which they can efficiently communicate.

The discovery process is performed by passive (listening) and active (probing) scanning functions.

It is time consuming because of the periods of listening as well as multiple frames have to be exchanged. It is even more time consuming as the number of channels (or operating bands) to scan increases, for instance by the recent introduction of the 6GHz band.

For example, the discovery procedure in Wi-Fi Direct (RTM) requires that each station performs successive listen phases and search phases, having each a random duration of multiple of 100 TUs (Time Units), on predefined channels (known as social channels). On average a long time is required before the stations are "aligned" on the same channel, i.e., one is searching while the other one is listening on the same channel. Furthermore, once two stations agree on a P2P Group, they switch to an operating channel, that is then impossible for the other stations to know in order to also join the P2P Group.

On top of that, a P2P Group may be created from scratch by any station at any time. It is difficult, even impossible, for the other stations to be aware that such P2P Group exists. IEEE 802.11 (e.g., IEEE Std 802.11-2020) allows an AP to transmit, in Beacon and Probe Response frames, a Reduced Neighbor Report element containing information on neighbor APs. The Reduced Neighbor Report element might not be exhaustive either by choice or by the fact that there may be neighbor APs not known to the AP.

IEEE 802.11be standard, namely EHT standing for "Extremely High Throughput", is being considering a feature called multi-link operation (MLO), wherein a single device can support multiple links and the data of the device can be delivered to another device through the multiple links. A multi-link device or MLD is a station comprising several affiliated stations, where each affiliated station is dedicated to handling one link for the MLD. An Access Point multi-link device (AP MLD) is a multi-link device, wherein each affiliated station (STA) within the MLD is an AP. A non-AP multi-link device (non-AP MLD) is a multi-link device, wherein each affiliated station within the MLD is a non-AP STA.

IEEE 802.11be (e.g., IEEE P802.11be/D3.0) allows an affiliated AP to transmit, in Beacon and Probe Response frames, a Basic Multi-Link element containing information on the other APs affiliated to the same AP MLD.

As all the APs of ad hoc or infrastructure networks (communication groups or BSSs) cannot be known, due for instance to newly created P2P Groups, the discovery procedure remain a tough and time-consuming task despite these signalling tools.

There is a need to provide more efficient or enhanced discovery mechanisms for wireless networks, in particular P2P Groups to promote direct device-to-device connectivity.

SUMMARY OF INVENTION

The present invention has been devised to address one or more of the foregoing concerns. The inventors have developed proactive mechanisms to request assistance of established APs to advertise about a communication group or BSS managed by another AP. Stations operating on the same channel as those established APs become aware of the other communication group or BSS without having to scan the corresponding channel or social channels. Hence, the discovery of communication groups or BSSs is eased. This particularly applies to P2P Groups and ad hoc networks that are usually ephemeral compared to infrastructure networks.

In this context, embodiments of the invention provide a communication method in a wireless network, comprising at a first station belonging to a communication group that is managed by a first access point, AP, and is configured to operate on a first channel: obtaining group-related information describing the communication group, sending a group announcing frame that includes the group-related information, to one or more second APs over respective second channels. The second channels are separate from the first channel of the communication group, as well as the second channels can be separate one from the other.

The first station thus voluntarily goes to the operating channels of the second APs, distinct from its own operating (first) channel, to give notice to the second APs that its communication group exists. This is the group announcing frame. In that way, the second APs are now able to advertise, over their operating channels, other stations about this communication group. There is no need for these other stations to scan or switch to other channels than their own operating channel. Discovery of the communication group is consequently facilitated, and the wireless network is more efficiently used.

In some embodiments, the first station, responsive to the sending, switches to the first channel to operate communication within the communication group, e.g., to directly (P2P) communicate with another station of the group. This ensures for the first station to go back to its own operating channel to operate normal communication.

Conversely, embodiments also provide a communication method in a wireless network, comprising at a second access point, AP, operating a basic service set, BSS, on a second channel: receiving, over the second channel, a group announcing frame that includes group-related information describing a communication group managed by a first AP and configured to operate on a first channel, responsive to the receiving: generating, based on the received group-related information, a reported-AP element describing the communication group, and sending, over the second channel, a frame including the reported-AP element to advertise the communication group within the BSS.

In that way, the second AP actually advertises, over its operating channel, about the existing communication group on another (first) channel. All stations operating on the same operating channel as the second AP can thus become aware of the communication group, hence decide to directly switch to the appropriate (first) channel to join it and take advantage of its communication benefits (e.g. P2P communication).

In that respect, a communication method is also provided in a wireless network, comprising at a second station operating on a second channel: receiving from a second access point, AP, managing an infrastructure network in the second channel, a frame including a reported-AP element advertising a communication group in an ad hoc mode managed by a first station acting as a peer-to-peer, P2P, Group Owner or as a soft or mobile AP, wherein the communication group is configured to operate on a first channel, switching an operating channel of the second station from the second channel to the first channel as retrieved from the reported-AP element, and joining the communication group in the ad hoc mode, on the first channel.

Indeed, thanks to the optimized discovery of ad hoc groups (e.g. P2P groups) made by the second AP above, second stations are now able to detect such ad hoc groups through the beacon frames or the like emitted by the APs of infrastructure networks (BSS). The second stations no longer have to camp on channels where to receive beacons from the manager (e.g. P2P GO) of the ad hoc group.

Correspondingly, a communication device is also provided that comprises at least one microprocessor configured for carrying out the steps of any of the methods above.

A non-transitory computer-readable medium is also provided that stores a program which, when executed by a microprocessor or computer system in a communication device, causes the communication device to carry out the steps of any of the methods above.

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

In some embodiments, the first station is a P2P group owner of the P2P group. Advantageous applications of the invention indeed regard P2P groups which are likely to be ephemeral, hence unknown by the majority of the stations during their lifetime. In this configuration, the group owner takes the initiative to inform the second APs about the existence of its managed P2P Group. Alternatively, any P2P station of the P2P group may take this initiative.

In some embodiments, the first station scans channels to determine the one or more second channels on which second APs operate and switches from the first channel to a first one of the second channels before sending the group announcing frame. The first station hence voluntarily leaves its operating channel to provide the group announcement to the other APs.

In particular embodiments, the first station selects the one or more second channels from detected channels on which other APs operate, wherein the selection is based on channels corresponding to a set of enabled links for an AP multi-link device, MLD, having multiple of the other APs as affiliated APs. As an example, the selection selects only one channel from detected channels corresponding to a given set of enabled links for an AP MLD having multiple of the other APs as affiliated APs.

This configuration takes advantage of the MLD to solicit only one (or few) affiliated APs of the MLD (hence to signal over only one channel) with a view of advertising, without additional signalling costs, the communication group over multiple channels by more (or all) affiliated APs of the MLD.

Correspondingly, from the second AP's perspective, the second AP is affiliated to an AP multi-link device, MLD, and the method further comprises, responsive to the receiving, sending by one or more other APs affiliated to the same AP MLD, over respective other operating channels, a frame including the reported-AP element to advertise the communication group within their respective operating channels. This approach increases the advertising of the communication group over multiple (second) channels. The discovery procedure for that communication group is therefore eased for a high number of stations.

In some embodiments, the group announcing frame includes a discovery assistance request to drive the second AP or APs to include the group-related information in frames sent over their respective operating second channels (e.g. within their BSSs). In such a way, the first station may dynamically decide and signal (hence drive) when help of the second AP to advertise the communication group is needed. A controlled enhanced discovery of the communication group is obtained.

In some embodiments, the communication group is a peer-to-peer, P2P, group. As recalled above, advantageous applications regard P2P groups which are likely to be ephemeral, hence unknown by numerous stations during their lifetime.

In particular embodiments, the first AP is a soft or mobile AP managing an ad hoc network and the second AP is an AP managing a basic service set, BSS, in infrastructure mode. Soft APs managing ephemeral ad hoc networks therefore rely on permanent, and thus reliable, APs of infrastructure networks. This guarantees an efficient spreading of the advertising about the communication group over multiple channels.

It may be noted that a P2P Group owner is considered as a soft or mobile AP in that it provides BSS functionality and services for operating the P2P Group.

In some embodiments, the group announcing frame includes one information element, IE, from: a Reduced Neighbor Report, RNR, element, a Channel Usage element, a Neighbor Report element, a Multi-Band element, and an AP List Response ANQP element.

Those elements are adapted to describe an AP, be it soft/mobile AP or infrastructure AP. These embodiments therefore advantageously reuse existing element formats, although some adjustments may be brought thereto.

In specific embodiments, the information element includes a P2P IE conveying all or part of the group-related information.

In some embodiments, the group-related information includes a Group BSSID defining a BSS IDentifier for the communication group and an Operating Channel providing an Operating Class and a Channel Number that define the first channel. In that way, enough information can be advertised by the second APs to other stations to join the communication group. In particular, these stations are now able to identify the operating channel where to find the communication group and to indicate the communication group (through its BSSID) they want to join when associating on the operating channel.

In specific embodiments, the group-related information further includes a Service Set Identifier, SSID, of the communication group. This particularly eases the choice for the other stations to elect one communication group to join. As an example, such a station can then easily identify a Wi-Fi-Direct group to join, thanks to the SSID starting with the word "DIRECT". Typically, the group-related information reuses the already-existing Group ID formed by a device address of an owner of the communication group and by the SSID of the communication 30 group.

Often the Operating Class and Channel Number are fields already available in the above mentioned RNR, Channel Usage, Neighbor Report and Multi-Band elements, in such a way the additional P2P IE may be used to convey the Group BSSID and/or the Group ID (SSID).

In some embodiments, the group announcing frame is one from: a Probe Request frame, a Generic Advertisement Protocol, GAS, Initial Public Action frame, and a P2P Invitation Request frame.

All these frames can carry one or more of the above RNR, Channel Usage, Neighbor Report and Multi-Band elements, hence ensuring appropriate announcement of the communication group.

With respect to the frame sent by the second APs, the reported-AP element may be included in a Reduced Neighbor Report, RNR, element. Hence, the already-existing RNR element is reused, avoiding substantial changes to the existing standards.

In specific embodiments, the reported-AP element includes a P2P IE conveying all or part of the group-related information.

In other specific embodiments, the reported-AP element includes a Neighbor AP

Information field that comprises:

an Operating Class field and a Channel Number field defining, together, the first channel, and

a TBTT Information Set field made of:

a Neighbor AP TBTT Offset field,

a BSSID field defining a BSS IDentifier for the communication group, and the P2P IE.

Conventional fields in the RNR are therefore reused, optionally supplemented by a dedicated P2P IE. The P2P IE may be optional, should the SSID field not be required. This configuration reduces the size of the Neighbour AP Information field compared to normal use of this field, without any impact on the ability for the stations to join the described communication group In other specific embodiments, the P2P IE includes a Service Set Identifier, SSID, of the communication group, and optionally a device address of an owner of the communication group to hence reuse the already-existing Group ID element. The P2P IE may thus include a unique P2P Group ID attribute. As mentioned above, the SSID may help any station receiving the reported-AP element to decide whether to join or not the communication group.

In other specific embodiments, the Neighbor AP Information field includes a TBTT Information Field Type field set to a value indicating a peer-to-peer, P2P, Group Owner or a soft or mobile AP managing an ad hoc network. Such setting first drives the format of the field as previously described compared to the normal format. It also allows the stations to quickly identify those APs or communication groups signalled according to the invention, hence possibly ad hoc networks such as P2P groups.

In other specific embodiments, no Per-STA Profile element within a Basic Multi-Link element embedded in the same frame sent by the second AP relate to the communication group.

It means there is no link between the Neighbor AP Information field and any of the Per-STA Profile elements within the Basic Multi-Link element. In that way, the Neighbor AP Information field is used in a different way as done in the IEEE 802.11be standard where it is combined with a PerSTA Profile to describe or define a reported affiliated AP of the AP MLD.

In some embodiments, the frame including the reported-AP element is a management frame, such as a Beacon frame or a Probe Response frame, or is a Fast Initial Link Setup, FILS, Discovery Public Action frame. This allows the second AP to perform a wide broadcast of information on the communication groups, to numerous stations.

In some other embodiments, the frame including the reported-AP element is broadcast by the second AP.

With respect to any station receiving the frame from the second APs, the second station may in some embodiments determine that the reported-AP element relates to a peer-to-peer, P2P, Group Owner or a soft or mobile AP managing an ad hoc network (hence the communication group). This is useful for a station that seeks to communicate in a P2P fashion, hence that searches for a dedicated P2P group or ad hoc network.

In some embodiments related to the second station, joining the communication group includes: retrieving, from the reported-AP element, a BSS IDentifier of the communication group, and sending a Probe Request frame having a BSSID field set to the retrieved BSS IDentifier. After having switched to the first channel on which the communication group operates, the second station hence initiates an association with that group (identified by the BSSID). In specific embodiments, joining the communication group further includes retrieving, from the reported-AP element, a device address of an owner of the communication group, wherein the Probe Request frame is sent using the retrieved device address. As the scanning frame (Probe Request) becomes specific to a device, the scan on the first channel is narrowed. As a consequence, the discovery is speeded up, as well as the future association with the communication group. Communication in the wireless network is therefore improved.

In some embodiments still related to the second station, the communication group is a peer-to-peer, P2P, group, and the method further comprises, at the second station, selecting the communication group from amongst multiple groups corresponding to multiple reported-AP elements included in one or more received frames.

For example, selecting the P2P group is responsive to locally determining P2P data to be sent directly to a destination station. In that way, the second station may quickly discover, and thus join, a communication group dedicated to P2P communication.

In specific embodiments, selecting the P2P group includes determining that a Service Set Identifier, SSID, of the communication group specified in the reported-AP element matches a template value. This allows for instance the second station to quickly switch to a Direct Wi-Fi group when the SSID follows the format "DIRECT-xy" where x and y are alphanumerical values.

At least parts of the methods according to the invention may be computer implemented. Accordingly, the present invention may take the form of an entire hardware embodiment, an entire software embodiment (including firmware, resident software, microcode, 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 floppy disk, a CD-ROM, a hard disk drive, a magnetic tape device or a solid-state memory device and the like. A transient carrier medium may include a signal such as an electrical signal, an electronic signal, an optical signal, an acoustic signal, a magnetic signal or an electromagnetic signal, e.g., a microwave or RF signal.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, and with reference to the following drawings in which: Figure 1 illustrates a typical wireless communication system in which embodiments of the invention may be implemented; Figure 2a illustrates an example of a multi-link arrangement in accordance with 802.11 be; Figure 2b illustrates, using frame exchanges in a timeline, an exemplary scenario for discovery and association process between a non-AP MLD and an AP MLD; Figure 2c schematically illustrates the content of a conventional Beacon frame; Figure 2d schematically illustrates the content of a conventional Multi-Link Probe Request frame; Figure 2e schematically illustrates the content of a conventional Multi-Link Probe Response frame; Figure 3 illustrates the conventional format of a reduced Neighbor Report (RNR) information element; Figure 4a illustrates the process of forming a P2P group according to Wi-Fi Direct; Figure 4b illustrates the format of a P2P Information Element, also known as P2P 1E, as defined in the 802.11 family of standards; Figure 5a illustrates, using a flowchart, a communication method facilitating the discovery of communication groups, at a first station notifying existing APs about the communication group, according to embodiments; Figure 5b illustrates, using a flowchart, a communication method facilitating the discovery of communication groups, at an AP receiving a notification about a communication group from a first station and then advertising about the communication group over its operating channel, according to embodiments; Figure 5c illustrates, using a flowchart, a communication method facilitating the discovery of communication groups, at a station being advertised by an AP about the communication group, according to embodiments; Figure 6 illustrates a modified Channel Usage element according to embodiments; Figure 7 illustrates a modified Reduced Neighbor Report element according to embodiments; Figure 8 illustrates a modified Neighbor Report element according to embodiments; Figure 9 illustrates a modified Multi-Band element according to embodiments; Figure 10a illustrates an AP assistance mechanism for improved discovery of a P2P Group, involving single-link APs (i.e., non-MLDs), according to embodiments.

Figure 10b illustrates another AP assistance mechanism for improved discovery of a P2P Group involving an MLD AP, according to embodiments.

Figure 11a shows a schematic representation a communication device in accordance with embodiments of the present invention; and Figure 11b shows a schematic representation of a wireless communication device in accordance with embodiments of the present invention.

DETAILED DESCRIPTION

The invention will now be described by means of specific non-limiting exemplary embodiments and by reference to the figures.

The techniques described herein may be used for various broadband wireless communication systems, including communication systems that are based on an orthogonal multiplexing scheme. Examples of such communication systems include Spatial Division Multiple Access (SDMA) system, Time Division Multiple Access (TDMA) system, Orthogonal Frequency Division Multiple Access (OFDMA) system, and Single-Carrier Frequency Division Multiple Access (SC-FDMA) system. An SDMA system may utilise different directions to simultaneously transmit data belonging to multiple user terminals. 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 utilises orthogonal frequency division multiplexing (OFDM), which is a modulation technique that partitions the overall system bandwidth into multiple orthogonal sub-carriers or resource units. These sub-carriers may also be called tones, bins, etc. With OFDM, each sub-carrier may be independently modulated with data. An SC-FDMA system may utilise interleaved FDMA (IFDMA) to transmit on sub-carriers that are distributed across the system bandwidth, localised 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 a non-access point station (so-called non-AP station or STA) or an access point station (so-called AP station or AP).

While the examples are described in the context of Wi-Fi (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), Base Station Controller ("BSC"), Base Transceiver Station ("BTS"), Base Station ("BS"), Transceiver Function ("TF"), Radio Router, Radio Transceiver, Basic Service Set ("BSS"), Extended Service Set ("ESS"), Radio Base Station ("RBS"), or some other terminology.

A non-AP station may comprise, be implemented as, or known as a subscriber station, a subscriber unit, a mobile station (MS), a remote station, a remote terminal, a user terminal (UT), a user agent, a user device, user equipment (UE), a user station, or some other terminology. In some implementations, a non-AP station 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 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 usually manages a set of stations that together organize their accesses to the wireless medium for communication purposes. The non-AP stations perform an association procedure to associate with the AP, including a discovery phase with passive and/or active scanning followed by an authentication phase and an association phase. The stations (including the AP) in an infrastructure network form a service set, referred to as basic service set, BSS (although other terminology can be used). A same physical station acting as an (infrastructure) access point may manage two or more BSSs (and thus corresponding WLANs): each BSS is thus uniquely identified by a specific basic service set identification, BSSID and managed by a separate virtual AP implemented in the physical AP.

On the other hand, in ad hoc networks, no infrastructure AP that provides medium access control (i.e., a dedicated router forming required infrastructure for the infrastructure network) is needed. A station of the ad hoc network is elected as the group owner or soft AP (standing for software enabled access point) to emulate some of the AP functionalities and services (e.g., discovery procedure through transmission of Beacon frames and Probe Response frames). The ad hoc network is mainly used for direct connectivity, hence communication, between peer stations. An exemplary application of the ad hoc networks includes Wi-Fi Direct. 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 P802.11be/ D3.0 of March 2023, introduce the Multi-Link Operation (MLO) when it comes to MAC layer operation. The MLO allows multi-link devices to establish or setup multiple links and operate them simultaneously.

A multi-link device (MLD) is a logical entity and has more than one affiliated (AP or non-AP) 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. Besides, the MLD also comprises a single address associated with the interface, which can be used to communicate on the distribution system medium (DSM).

The stations forming the same MLD may be partly or all collocated within the same device or geographically dispersed.

An access point multi-link device (AP MLD) corresponds to a MLD where each station (STA) affiliated with the MLD is an AP, referred to as "affiliated AP" hereinafter. A non-access point multi-link device (non-AP MLD) corresponds to a MLD where each station (STA) affiliated with the MLD is a non-AP station, referred to as "affiliated non-AP station".

When referring hereinafter to either an AP MLD or a non-AP MLD, the general term "station MLD" may be used. Depending on the literature, "multilink device", "ML device" (MLD), "multilink logical entity", "ML logical entity" (MLE), "multilink set" and "ML set" are synonyms to designate the same type of ML device.

Multiple affiliated non-AP STAs of a non-AP MLD can then setup communication links with multiple affiliated APs of an AP MLD, hence forming a multi-link channel. This is for instance done through the conventional association procedure: ML Discovery including passive scanning (ML beacons) or active scanning (ML Probe Request and corresponding Response), following by ML Authentication and finally by ML Setup where the non-AP MLD associates with the AP MLD (hence obtained an Association IDenfifier, AID) and sets up the ML links for its affiliated non-AP STAs with the APs affiliated with the AP MLD.

The links established (or "enabled links") for MLDs are theoretically independent, meaning that the channel access procedure (to the communication medium) and the communication are performed independently on each link. Hence, different links may have different data rates (e.g., due to different bandwidths, number of antennas, etc.) and may be used to communicate different types of information (each over a specific link).

A communication link or "link" thus corresponds to a given channel (e.g. 20 MHz, 40 MHz, and so on) in a given frequency band (e.g. 2.4 GHz, 5 GHz, 6 GHz) between an AP affiliated with the AP MLD and a non-AP STA affiliated with the non-AP MLD.

The affiliated APs and non-AP STAs operate on their respective channels in accordance with one or more of the IEEE 802.11 standards (a/b/g/n/ac/ad/af/ah/Way/ax/be/bn) or other wireless communication standards.

Thanks to the multi-link aggregation, traffic associated with a single MLD can theoretically be transmitted across multiple parallel communication links, thereby increasing network capacity and maximizing utilization of available resources.

The terms "traffic" and/or "traffic stream(s)" as used herein, are defined as a data flow and/or stream between wireless devices.

Figure 1 illustrates a wireless communication system in which several communication station devices 101-107, 110 exchange data frames over a radio transmission channel 100 of a wireless local area network (VVLAN), under the management of a central station in the network infrastructure, namely access point device (AP) 110. This is known as the infrastructure mode. Direct communications between STAs (e.g., between STA2 and STA4) can also be implemented without the use of such an infrastructure access point. It is known as the ad-hoc mode.

The radio transmission channel 100 is defined by an operating frequency band constituted by a single channel, a plurality of channels forming a composite channel, or a plurality of distinct channels (links) forming a multi-link operation.

In the following description, the term "station" or "STA" may be used to describe a non-AP station operating on a given link of 100, which may be a standalone non-AP station or an affiliated non-AP station entity of a non-AP MLD device. Similarly, the term "AP" describes an AP station operating on a given link, which may be a standalone AP station or an affiliated AP station entity of an AP MLD device.

Exemplary situations of direct communications, corresponding to an increasing trend nowadays, include the presence of peer-to-peer (P2P, also known as Direct Link or "DiL") transmissions in between non-AP stations, e.g., STA 102 and STA 104 as illustrated in the Figure.

Technologies that support P2P transmissions include for example Wi-Fi Direct, Wi-Fi-Miracast (RTM) or Wireless Display scenario, or Tunneled Direct Link Setup (TDLS). Note that even if P2P flows are usually not numerous, the amount of data per flow may be huge (typically low-compressed video, from 1080p60 up to 8K UHD resolutions).

Each STA 101-107 registers to the AP 110 during an association procedure, at the end of which, the AP 110 assigns a specific Association IDentifier (AID) to the requesting STA. For example, the AID is a 16-bit value uniquely identifying the STA. When the AP and non-AP STA are respectively an affiliated AP of an ML AP device and an affiliated non-AP of a ML non-AP device, they establishing a ML association wherein an unique AID is assigned to the entire non-AP MLD: all affiliated non-AP STAs are identified by same AID value on their respective operation link.

The stations 101-107, 110 may compete on a given link one against the other using EDCA (Enhanced Distributed Channel Access) contention, to access the wireless medium in order to be granted a transmission opportunity (TXOP) and then transmit (single-user, SU) data frames. The stations may also use a multi-user (MU) scheme in which a single station, usually the AP 110, is allowed to schedule a MU transmission, i.e., multiple simultaneous transmissions to or from other stations, 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.

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

Figure 2a illustrates a block diagram example of a multi-link arrangement in accordance with 802.11be in which a Multi-Link logical entity or device may be seen as a collection of two or more STAs: each STA operating on a specific link (frequency band) and comes with its own link specific PHY and lower MAC layer.

Multiple affiliated APs 110 (110-x, 110-y, 110-z in the Figure) are included in a multi-link AP logical entity or device 210. In addition, multiple affiliated STAs 230 (230-x, 230-y, 230-z in the Figure) are included in a multi-link non-AP logical entity or device 220-a.

They co-exist with legacy non-AP stations, but also with single-link stations (as example device 220-b) on a given link.

In some embodiments, an affiliated AP 110 may be configured to operate in a frequency band that is different from a frequency band of at least one of the other affiliated APs 110 of the plurality of APs. In some embodiments, an affiliated AP 110 may be co-located with at least one of the other affiliated APs 110 of the plurality of affiliated APs enclosed in the MLE AP 210. In some embodiments, multiple affiliated APs 110 are collocated in an AP device 210 that supports simultaneous operations to one or more non-AP devices 220-a. Between the AP 210 device and one non-AP device 220-a, there are different interfaces related to links 201, 202, 25 203.

The AP MLD 210 may also be in communication with other systems (e.g. a distribution system (DS) such as a local area network and/or wide band network) via an interface 120, such as a backhaul interface (typically an Ethernet Link).

In MLD operation, simultaneous transmit and receive (STR) operation may be allowed.

That is while one link is transmitting, another link of the same MLD is receiving. Non-AP MLDs may be STR or non-STR (NSTR).

Each affiliated AP 110 offers a link towards the AP MLD 210 to the affiliated non-AP STAs of a non-AP MLD (230). 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 110-x/110-y/110-z 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 220-a has to discover, authenticate, associate and set up multiple links with the AP MLD 210, each link being established between an affiliated AP of the AP MLD 210 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.

Figure 2b illustrates, using frame exchanges in a timeline, an exemplary scenario for discovery and association process between a non-AP MLD or non-AP STA and an AP MLD. The example involves STA Al 121 (either affiliated to the non-AP MLD 220-a or the single-link non-AP station 220-b) and AP1 111 affiliated to the AP MLD 110.

The following description is referring to Multi-Link procedures, in a way that Beacon and Probing frames contain Multi-Link Information element(s) introduced by 802.11be. Legacy devices (prior to 802.11be) are still able to understand those frames, but will ignore the ML Information elements.

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 during the ML discovery and ML setup procedures contains 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. The Basic Multi-Link element carries one or more Per-STA Profile subelement(s) corresponding to each additional affiliated STA (known as "reported STA") within the same MLD.

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.

The discovery may be based on active or passive scanning.

In an active scanning, a non-AP STA transmits a Probe Request frame 212 (with a wildcard SSID) and waits for a Probe Response frame 213 from an AP. The active discovery process thus mainly relies on the exchange of Probe Request and Probe Response frames between an AP and a non-AP. For ML discovery, the discovery procedure may be performed either by using a Probe Request/Response frame exchange per link or one ML Probe Request/Response frame exchange carrying all the information of the various APs affiliated to the AP MLD on one of the available links.

In the passive scanning, the non-AP STA listens on each channel for Beacon frames 211 sent periodically by an AP on its operating channel and then transmits a Probe Request frame 212 with the SSID (retrieved from the Beacon frames) corresponding to an AP of interest.

When sent by a non-AP MLD for instance non-AP MLD 101 through the STA Al 230-x, a Probe Request frame 212 allows the affiliated non-AP station to request an affiliated AP (AP1 110-x; "reporting AP") to include, in addition to its network information, the complete or partial set of capabilities and operation elements (i.e. network information) of the other APs affiliated with the same AP MLD ("reported APs").

When sent by an AP MLD for instance AP MLD 110 through the AP1 110-x, a Beacon frame 211 or a Probe Response frame 213 includes both a Basic Multi-Link element carrying one or more Per-STA Profile subelement(s) which describe network information of the other ("reported") APs affiliated to the AP MLD and a Reduced Neighbor Report (RNR) element describing reduced network information about the same "reported" APs.

Current 802.11 be revision defines two configurations for the Basic Multi-Link element, regarding respectively the Beacon and Probe Response frames.

A first type is used for Beacon frames in which the Basic Multi-Link element carries only information that is common to all reported APs (communication interfaces). The common information is conveyed in a so-called Common Info field of the Basic Multi-Link element. For instance, this includes the MLD MAC address, the set of enabled links, or the STR capability.

Figure 2c schematically illustrates a Beacon frame 211 in which the Basic Multi-Link element 252 only includes common information.

A second type is used for the Probe Response frames in which the Basic Multi-Link element carries, in addition to the common information (Common Info field), partial or complete profile (i.e. network information) of those reported APs different from the advertising one (reporting AP). The profile of each reported AP is conveyed through an individual and independent field, known as Per-STA Profile field. Figure 2e schematically illustrates a Probe Response frame 213 in which the Basic Multi-Link element 252 includes common information and one Per-STA profile per each reported AP of the AP MLD.

Current 802.11be revision also defines a specific Multi-Link element, so-called Probe Request Multi-Link element, regarding the Probe Request frames to which Probe Response frames can be sent by the AP MLD. The Probe Request Multi-Link element is used to request a reporting AP to provide information (complete or partial profile) of other (reported) APs affiliated with the same AP MLD as the reporting AP. The Probe Request Multi-Link element includes PerSTA Profile fields for each requested reported AP. Figure 2d schematically illustrates a Probe Request frame 212 in which the Probe Request Multi-Link element 260 includes common information and one Per-STA profile per each requested reported AP.

Beacon frames only carry partial information at the multi-link level (i.e., Upper-MAC or MLD-level related-information). This makes non-AP stations to take more time to perform the discovery process, as they should scan all the interfaces of the MLD before doing the multi-link setup. This is all the more detrimental to network efficiency that the number of channels to scan still increases (e.g. with the recent introduction of the 6 GHz band).

To avoid such a situation, it has been provided in 802.11be to reuse the Reduced Neighbor Report (RNR) element already defined in 802.11v, as mentioned above, to announce, as soon as the Beacon frames, some basic information about the other interfaces (than the transmitting one) of the same AP MLD.

802.11v defines the use of the RNR information element to include information about a neighbor AP. This is currently used to offer out-of-band discovery by informing clients about 6 GHz APs: the "neighbor AP" is actually the 6 GHz radio housed in the same AP along with the 2.4 GHz and 5 GHz radios. 6 GHz clients will thus learn about the available 6 GHz radio from the RNR information in either Beacon or Probe Response frames sent by the AP's 2.4 and 5 GHz radios.

By using the RNR element in the Multi-Link environment, a station can directly probe the AP MLD to request the complete profile (capabilities, parameters and operation elements) of their other interfaces (reported APs). As a result, a non-AP MLD can use the information gathered from the Reduced Neighbor Report element and the Basic Multi-Link element (from Beacon and Probe Response frames) to decide whether to perform multi-link setup with the AP MLD. Air-time occupancy of management frames, as well as, the time required by the station to pass from the discovery process to the multi-link setup can then be reduced.

Figure 3 illustrates the format of the Reduced Neighbor Report (RNR) information element 300 that is present in Beacon, Probe Response or FILS Discovery frames.

The RNR element 300 contains channel and other information related to neighbor APs, which include "reported APs" in the context of Multi-link environment.

Element ID field 301 is equal to value 101 to indicate the information element is a RNR element. Length field 302 specifies the length, in octets, of the information element including the

Neighbor AP information Fields field 303.

Neighbor AP information Fields field 303 contains a set of one or more ("n" in the example of the Figure) Neighbor AP Information fields 320, each providing elements or network information about a neighbour or "reported" AP different from the reporting AP (AP sending the information element).

Each Neighbor AP Information field 320 comprises a TBTT information header subfield 321, an Operating Class subfield 322, a Channel Number subfield 323 and a TBTT information Set subfield 324, all related to a given reported AP.

TBTT Information Header subfield 321 contains several fields that indicate how many TBTT Information fields 330 are present in the TBTT Information Set subfield 324 (e.g. TBTT Information count, indicating of the number of TBTT Information fields included in 324), and their length type (TBTT Information Field Type has value 0 or 1 for 802.11 devices operating in bands greater than 1 Mhz). Multiple reported APs that have the same operating channel are reported in the same TBTT Information Set subfield 324 (D" in the example of the Figure).

Operating Class field 322 indicates a channel starting frequency that, together with the Channel Number field 323, defines the primary (hence operating) channel of the BSS of the reported AP(s) corresponding to that Neighbor AP Information field 320.

Each TBTT Information field 330 comprises various fields, including a Neighbor AP TBTT Offset subfield 331, a BSS Parameters subfield 340 and possibly an MLD Parameters

subfield 350.

Neighbor AP TBTT Offset subfield 331 indicates the offset in TUs, rounded down to nearest TU, to the next TBTT of the reported AP's BSS from the immediately prior TBTT of the reporting AP that transmits this element. Value 254 indicates an offset of 254 TUs or higher. Value 255 indicates an unknown offset value.

BSS Parameters subfield 340 comprises various fields, including: OCT Recommended subfield 341 set to 1 to indicate that On-channel Tunneling (OCT) is recommended to exchange MMPDUs with the reported AP identified in the TBTT Information field (otherwise set to 0).

Same SSID subfield 342 set to 1 to indicate that the reported AP has the same SSID as the reporting AP (otherwise set to 0).

Multiple BSSID subfield 343 set to 1 to indicate that the reported AP is part of a multiple BSSID set (otherwise set to 0).

Transmitted BSSID subfield 344 set to 1 to indicate that the reported AP is a transmitted BSSID (otherwise set to 0).

Member Of ESS With 2.4/5 GHz Colocated AP subfield 345 indicating whether the reported AP is part of an ESS that has no 6 GHz-only APs that might be detected by a STA receiving this frame. This means that all APs operating in the 6 GHz band that are part of that ESS that might be detected by a STA receiving this frame can be discovered in the 2.4 GHz and/or 5 GHz bands.

Unsolicited Probe Responses Active subfield 346 set to 1 to indicate the reported AP is part of an ESS where all the APs are transmitting unsolicited Probe Response frames every 20 TUs or less (this is for scanning operations in 6GHz) (otherwise set to 0).

Colocated AP subfield 347 set to 1 to indicate when the reported AP is in the same colocated AP set as the transmitting/reporting AP (otherwise set to 0).

MLD Parameters field 350 contains information about the link associated with the reported AP, in particular includes AP MLD ID subfield 351, Link ID subfield 352, BSS Parameters Change Count subfield 353, All Updates Included subfield 354 and Disabled Link Indication

subfield 355.

AP MLD ID subfield 351 specifies the identifier of the AP MLD to which the reported AP is affiliated. If the reported AP is affiliated to the same MLD as the reporting AP, MLD ID subfield 351 is set to O. Otherwise, if the reported AP is part of another AP MLD, AP MLD ID subfield 351 is set to a value higher than 0. For instance, if the reported AP is affiliated to the same MLD as a non-transmitted BSSID that is in the same multiple BSSID set as the reporting AP, AP MLD ID subfield 351 is set to the same value as in the BSSID Index field in the Multiple BSSID-Index element in the non-transmitted BSSID profile corresponding to the non-transmitted BSSID. Otherwise, the AP MLD ID subfield is set to a value chosen by the reporting AP to uniquely identify the AP MLD of the reported AP, such value being higher than 2n-1 and lower than 255 (n corresponding to the value of the MaxBSSID Indicator of the reporting AP). AP MLD ID subfield 351 is set to 255 if the reported AP is not part of an AP MLD, or if the reporting AP does not have information of that MLD.

Link ID subfield 352 is the unique identifier (within an MLD) of the link corresponding to the reported AP. Link ID subfield 352 is set to 15 if the reported AP is not part of an AP MLD, or if the reporting AP does not have that information.

BSS Parameters Change Count subfield 353 contains a counter that is incremented (modulo 255) each time a critical parameter of the BSS managed by the reported AP is updated in the Beacon frame. All Updates Included subfield 354 indicates, in case of update, if all updated elements are present in the current RNR report.

Disabled Link Indication subfield 355 is set to 1 if the reported AP is operating on a link that is advertised as disabled and the reported AP is affiliated with the same AP MLD as the reporting AP.

As defined, MLD Parameters field 350 allows a link (through the Link ID subfield 352) to be made between a Neighbor AP Information field 320 defining a reported AP in the RNR element 300 and the corresponding Per-STA Profile subelement for the same reported AP in the Basic Multi-Link element 252. This is for instance illustrated in Figure 2e, through the arrows. The Beacon frame 211 that is broadcast by an AP thus includes, as shown in Figure 2c, first elements for legacy device (preceding EHT device), such as the SSID element, the Supported Rates and BSS Membership Selectors field, the Extended Supported Rates and BSS Membership Selectors element, optionally one or more RNR elements 300 to describe e.g. reported APs or neighbor APs, and HE ("High-Efficiency" meaning 802.11 ax features) parameters such as HE Capabilities, HE Operation, TVVT element, HE 6 GHz Band Capabilities, etc. (not shown); followed by the EHT ("Extremely High Throughput' meaning 802.11be features) elements, including EHT Operation element 251, Basic Multi-Link element 252 (conveying common information about the reported APs if any), EHT Capabilities element 253, Multi-link Traffic Indication element (not represented), and TID-to-Link Mapping element (not represented). The Probe Request frame 212 in Multi-Link environment includes, as shown in Figure 2d, includes legacy elements followed by a Probe Request Multi-Link element 260, in order to discover the APs affiliated with the requested AP MLD. The frame requests the complete or partial set of capabilities, parameters and operation elements of the AP(s) affiliated with the targeted AP MLD in the response frame as follows: if the Probe Request Multi-Link element 260 in the Probe Request frame 212 does not include any Per-STA Profile subelement, then all APs affiliated with the same AP MLD are requested, on the other hand, if the Probe Request Multi-Link element 260 includes one or more Per-STA Profile subelements each specifying a Link ID, then only APs affiliated with the same AP MLD corresponding to those link IDs are requested APs.

The Probe Response frame 213 in Multi-Link environment includes, as shown in Figure 2e, as the Beacon frame legacy elements (before EHT) followed by EHT elements. In particular, it includes an RNR element 300 carrying a Neighbor AP Information field 320 for each requested reported AP and a Basic Multi-Link element 252 carrying a Per-STA Profile subelement for each requested reported AP. If both elements carry information about the same reported AP (that is affiliated with an AP MLD), then the transmitting AP sets the value of the Link ID subfield contained in the Per-STA Profile subelement corresponding to the reported AP to the same value as the value carried in the Link ID subfield 352 contained in the MLD Parameters field 350 of the Neighbor AP Information field 320 corresponding to that reported AP. It is recalled that the value in AP MLD ID subfield 351 allows to identify the MLD with which the corresponding reported AP is affiliated.

Efficient use of the resources of a wireless local-area network (VVLAN) is important to provide bandwidth and acceptable response times to the users of the WLAN. In order to enhance direct device to device connectivity, use of a "Software Access Point" (Soft AP) is a new trend that allows devices to communicate directly with each other using methods similar to traditional WLAN, except without requiring the use of a central access point provided as an infrastructure of the WLAN.

Recently, 802.11be introduced the concept of non-simultaneous transmit and receive (NSTR) soft access point (AP) multi-link device (MLD). The term NSTR mobile AP MLD is also used. In general, a soft AP represents a software enabled AP and implies a software enabling a device which has not been specifically made to be a router into a wireless AP, to operate as a soft AP. Soft AP in 802.11 be is thus a mechanism allowing a non-AP MLD station to be temporally turned to adopt AP functionality, meaning all its affiliated stations adopt the AP behaviors.

IEEE 802.11be defines mechanisms to support the operation of a Non-STR AP MLD in release 1 (R1). The mechanisms are limited to instantiate a Non-STR Non-AP MLD as a Soft AP that could utilize all its links under AP-like operation: if a non-AP MLD intends to operate as an AP MLD, this device becomes the soft AP MLD. However, when a non-AP MLD is a non-STR MLD defined in IEEE 802.11 TGbe, some issues exist for the soft AP MLD operation due to the restriction that the non-AP MLD cannot transmit and receive simultaneously on the non-STR link pair.

The soft-AP MLD is usually in a mobile device that is typically battery powered. A soft AP has typically limited capacity compared to a regular AP. The limitation may regard the bandwidth, the number of stations that can connect to the soft AP. In a non-ML context, an example of soft AP is the connection sharing functionality of modern smartphones.

Direct device-to-device connectivity was already possible in the original IEEE 802.11 standard by means of the ad-hoc mode of operation where one of the devices operates as an AP.

However, this ad-hoc mode has never been able to mark its presence in the market due to several drawbacks or limitations in the requirements, e.g., lack of efficient power saving support or extended QoS capabilities Wi-H Direct has been designed in 802.11a, g or n to provide an improved ad-hoc mode where the device-to-device connectivity is eased. Wi-Fi Direct falls within the scope of the soft AP because one of the P2P station takes the lead on the P2P group and still provides some AP functionalities to the other P2P stations, such as discovery and registration services.

Figures 4a and 4b illustrate Wi-Fi Direct modes of operation.

Wi-Fi Direct is a direct communication technology that enables devices to be easily connected to each other without using the conventional AP required in an infrastructure WLAN, without a complicated establishment procedure (device-to-device connectivity). Wi-Fi Direct makes it simple and convenient to print, share, sync, play games, and display content on another device. Wi-Fi Direct establishes an ad hoc-like network known as P2P Group, avoiding for the devices to join a traditional home, office or public network. Devices can make a one-to-one connection, or a group of several devices can connect simultaneously.

The Wi-Fi operating peer-to-peer (P2P) mode refers to a mode where each party has the same capabilities and either party can initiate a communication session. More generally, a P2P Device is a VVi-Fi Direct device that is capable of acting as both a P2P Group Owner (hence acting like a soft AP) and a P2P Client. The P2P Client role implements non-AP STA functionality. The P2P Group Owner has a role which is similar to the AP role providing BSS functionality and services for associated Clients (P2P Clients or Legacy Clients).

Figure 4a illustrates the process of forming a P2P group. A Wi-Fi Direct connection is mainly performed through three phases including a device discovery, a service discovery and group establishment. The Device Discovery facilitates two P2P Devices arriving on a common channel and exchanging device information. The Service Discovery is an optional feature that allows a P2P Device to discover available higher-layer services prior to forming a connection. The Group Formation or Establishment is used to determine which device will be the P2P Group Owner and form a new P2P Group.

The device discovery procedure 400 is required when Wi-Fi P2P devices, for example, a first and a second P2P device (401,402), have to recognize each other to configure a connection and to establish the Wi-Fi P2P group. In this phase, each of the P2P devices alternates between a listen state and a search state. A first P2P device searches for neighboring W-Fi P2P devices by repeatedly performing channel scan of IEEE 802.11 channels by listening to predefined channels, known as "social channels" defined as channel 1, 6 and 11 in the 2.4GHz band, and by searching these channels for a predetermined time period. This phase is used to ensure that two simultaneously searching P2P Devices arrive on a common channel to enable communication. This is achieved by cycling between states where the P2P Device waits on a fixed channel for Probe Request frames (in the Listen State) or sends Probe Request frames on a fixed list of channels (in the Search State). Convergence of two devices on the same channel is assisted by randomizing the time spent in each cycle of the Listen State. In other words, the exchanges of Probe Request and Probe Response frames enable the P2P devices to discover each other on a nearby environment.

The optional service discovery procedure 420 is performed after the Device Discovery process to provide a function of exchanging information on services that each P2P device can support. That is, each P2P device may identify a supportable service protocol, a service and the like through exchange of request and response frames (446). P2P Devices thus exchange queries to discover the set of available services and, based on this, decide whether to continue the group formation or not. In other words, this procedure can be used to determine compatibility information on the services offered by a P2P Device.

The Group Formation procedure 430 is a negotiation process to agree on a group owner (GO) for the P2P group being established. It is performed by a three-way exchange of a GO negotiation request, a GO negotiation response, and a GO negotiation confirm frame 445, whereby the two devices agree on which device will act as P2P GO, the other one acting as a client of the GO, and on the channel where the group will operate, which can be, for example, in the 2.4 GHz or 5 GHz bands.

Security provisioning 447 starts after discovery has taken place and, if required, the respective roles have been negotiated upon forming the P2P group.

Once the P2P Group is established, new P2P devices can discover and join the group using active or passive scanning mechanisms like the ones used in traditional Wi-Fi networks.

Like a traditional AP, the P2P GO announces itself through beacons (460), and has to support power saving services for its associated clients. The P2P GO is also required to run a Dynamic Host Configuration Protocol (DHCP) server to provide P2P Clients with IP addresses (not represented in the figure).

Upon successful Wi-Fi Direct Connection Setup between devices, the P2P devices can use the Wi-Fi Direct connection to directly exchange data. Communication within a P2P Group established shall employ WPA2-Personal security.

For example, they may attempt to establish an Audio-Video Session 440. An AV control session, steps 441-442, initiates a Transmission Control Protocol (TCP) connection, wherein one of the P2P devices acts as a P2P Sink (e.g., 402) and the second as a P2P Source (e.g., 401) with regards to the AV data flow. The P2P Source typically plays the TCP server role. The protocol running on the Control Port is a Real Time Streaming Protocol (RTSP). A Real-time Transport Protocol (RTP) or a Real-time Transport Control Protocol (RTCP) may be used as the data path for the AV data session 443; and a RTSP may be used as a control path for the AV control session. AudioNideo elementary streams generated by the P2P Source can be packetized using a MPEG2-TS container format and encapsulated by RTP/UDP/IP headers prior to 802.11 packetization and transmission.

Some devices certified under the Wi-Fi Direct program support connections to both an infrastructure network and Wi-Fi Direct group at the same time (e.g., a laptop may support an infrastructure connection while also belonging to a Wi-Fi Direct-certified group). Simultaneous connection to a Wi-Fi Direct group and an infrastructure network is an optional feature. To do so, the Wi-Fi chip does not use only one interface for wireless communication, but usually uses dual MAC products that support two interfaces.

To signal P2P attributes in the frames exchanged during the above three phases, P2P protocol communication is based on the use of a so-called P2P Information Element (P2P IE, 480) as depicted in Figure 4b. It is based on the Vendor Specific Information Element as defined in IEEE Std 802.11-2012, wherein Element ID 481 is set to OxDD to signal a P2P IE, WFA OUI field 483 indicating WFA specific and OUI Type field 484 indicating P2P version.

A number of P2P attributes 490 is defined. A single P2P IE may carry one or more P2P attributes 490. The P2P attributes 490 are defined to have a common general format consisting of a 1-octet P2P Attribute ID field, a 2-octet Length field and variable-length attribute-specific information fields. Various attributes are listed in the table of the Figure, from among which: The P2P Capability attribute (Attribute ID = 2) contains a set of parameters that can be used to establish a P2P connection. It is included in Beacon frames, Probe Request frames, (Re)association Request frames, and GO Negotiation frames.

The P2P Device ID attribute (Attribute ID = 3) contains the P2P Device's Address (6 octets sized), and is present in the Beacon frame.

The Listen Channel attribute (Attribute ID = 6) contains the Listen Channel and Operating Class information, and is included in Probe Request frames and GO Negotiation Request frames. If the P2P Device has not selected a Listen Channel, the Listen Channel attribute can be omitted.

The P2P Group BSSID attribute (Attribute ID = 7) contains the BSSID used by a P2P Group Owner for a P2P Group.

The Channel List attribute (Attribute ID = 11) contains a list of Operating Class and Channel pair information, and is included in GO Negotiation frames and P2P Invitation frames.

The Operating Channel attribute (Attribute ID = 17) is only present in the P2P IE if the P2P Device is an operating P2P Group Owner. The attribute indicates the Operating class and Channel number on which the P2P Device is operating as P2P Group Owner. In other words, it defines the operating channel of the P2P Group. The Operating Class and Channel Number fields of the Operating Channel attribute corresponds to the same elements as defined in REVme D2.1 (Appendix E).

The P2P Device Info attribute (Attribute ID = 13) contains information on a P2P Device (Device Address, configuration method, device Name etc.). The P2P Device Info attribute is included in the (Re)association Request frame, Probe Response frame, and GO Negotiation frames.

The P2P Group ID attribute (Attribute ID = 15) contains a unique P2P Group identifier of the P2P Group, for example formed by the pair {P2P Device address of the P2P Group Owner, and SSID}. The use of a globally unique P2P Device Address of the P2P Group Owner assures that different P2P Devices create P2P Groups differentiated from each other. Each SSID begins with the ASCII characters "DIRECT-", followed by two ASCII characters "xy", randomly selected. This SSID requirement enables users of Legacy Clients to differentiate between a P2P Group and an infrastructure network. The P2P Group ID attribute is included in the P2P Invitation Request frames.

The above description shows that unknown soft AP (including P2P GO) can be discovered by stations (or P2P devices) only through intensive scanning over multiple channels (either predefined/social channels or potential channels on which such soft AP may operate) because both client and soft AP have to be in-band for the discovery. This issue also exists for any unknown AP of infrastructure BSS.

With the increasing number of operating bands/channels including those of the recent 6 GHz band, traditional scan (active or passive) of the channels takes too much time. Furthermore, specific to Wi-Fi Direct or the link, the P2P GO usually stays on the operating channel of its P2P Group once the latter is established. This means that, by failing to switch back to the social channels, it becomes complicated for new P2P devices to discover and thus to join the P2P Group.

It comes that the known discovery mechanisms are not sufficient to provide efficient network communication in wireless networks. in particular to discover ad hoc networks, including P2P groups, to promote direct device-to-device connectivity.

In this context, the present invention intends to provide new mechanisms that favor discovery of such unknown "communication groups".

Embodiments provide that any device or station participating in such a communication group, e.g. the P2P GO, can notify an existing AP, e.g. the AP of an infrastructure BSS, about its communication group, in order to drive that existing AP to advertise about the communication group over its operating channel. In that way, the device solicits discovery assistance to the existing AP. The stations operating on the same channel as the existing AP then become aware of the communication group without having to scan multiple channels. They may then decide to join the communication group by switching to the corresponding operating channel. To further improved the discovery over channels, the assistance of multiple existing APs can be solicited, meaning the notification is sent to those multiple APs, that each advertises about the communication group over their own operating channel. In particular, multiple APs affiliated to the same AP MLD may advertise about the group, as soon as one of them receives the notification and shares the information with the others.

Thanks to this assistance for advertising about the communication group, the average time needed by stations to discover the group is made shorter. Hence, the initial link setup time to establish a communication link between, e.g., P2P device and soft AP (P2P GO), is substantially decreased.

Figures 5a, 5b and 5c illustrates, using flowcharts, general steps of a communication method respectively at a first station notifying existing APs about the communication group to which it belongs (Figure 5a), at such an AP receiving the notification and advertising about the communication group over its operating channel (Figure 5b) and at any station sharing the same operating channel as the AP and thus receiving the advertisement (Figure 5c).

For ease of explanation, the description of these Figures is mainly made based on the Wi-Fi Direct technology, as described in "Wi-Fi Peer-to-Peer (P2P) Technical Specification", version 2.0, although these embodiments can be applied to any soft AP -i.e., non-AP station emulating AP functionalities and services to manage a communication group.

Figure 5a illustrates, using a flowchart, a communication method facilitating the discovery of communication groups, at a first station (e.g., 101 or 401) notifying existing APs about the communication group. In this method, the first station belongs to the communication group (e.g. P2P Group) that is managed by a first AP (e.g. P2P GO) and that is configured to operate on a first channel. The first station may be the P2P group owner of a P2P group to advertise. Alternatively, any P2P device belonging to the P2P Group can initiate the communication method. More generally, any station of the communication group may initiate the method.

To perform the notification, the first station obtains group-related information describing the communication group, next sends a group announcing frame (i.e. a notification) that includes the group-related information, to one or more second APs over respective second channels. In that way the existing APs, usually those of infrastructure BSSs, become aware of the communication group and can then advertise about it over their respective channels.

Finally, the first station, responsive to the sending, may switch (usually switch back) to the first channel to operate communication within the communication group. In that way, the first station that has voluntarily gone to the operating channels of the existing APs to notify them, comes back to its own operating channel, e.g., its switches back to the channel of the P2P group in order to directly P2P communicate with another P2P device of the group.

The process starts at step 510 where the first station participates to a communication group, e.g., a P2P Group.

The first station may be the soft AP, e.g., P2P Group Owner (GO), of the communication group. In that case, step 510 may merely include activating the software providing soft AP features.

Typically, a P2P Device may autonomously create a P2P Group, where it immediately becomes the P2P GO, by sitting on a first (operating) channel and starting to beacon.

In a variant, the first station and a second station willing to directly communicate (therefore performing the process of Figure 5c) may be initially associated with an existing AP (performing the process of Figure 5b) and may decide, by exchanging frames via the existing AP, to form a P2P Group outside the AP's control. To that end, it is recalled that, among the various capabilities exchanged by the existing AP and the non-AP stations during the discovery procedure, a Channel Usage information may be provided by the AP in Probe Response frame 213 to advise the non-AP stations on how to coexist with the infrastructure network/BSS. The Channel Usage information defines a set of channels provided by the AP to the non-AP stations for operation of a non-infrastructure network or an off-channel. In other words, the AP provides one or more channels that can be used to establish a non-infrastructure communication group.

The first and second stations may thus use one of these channels as the first (operating) channel for the P2P Group they establish.

In any case, the P2P Group Owner assigns a P2P Interface Address (or the like) that it uses as its MAC address and BSSID for the duration of the P2P Group, on the first (operating) channel.

Optionally, the P2P Group Owner may assign a globally unique P2P Group ID (or the like) for the P2P Group when it is formed. The P2P Group ID remains the same for the lifetime of the P2P Group. In embodiments, the AID of the P2P GO (e.g., obtained by the non-AP MLD during association with the AP MLD) can be used to form the unique P2P Group ID (as further described here below to construct the Service Set Identifier, SSID, of the communication group).

Advantageously, the AID is already known by the other stations of the infrastructure BSS, hence the P2P Group is easily identifiable by those other stations. On the other hand, the MAC address of the P2P GO may be used as BSSID for P2P Group. In other embodiments mentioned above, the P2P Group ID remain is made of the P2P Device Address and an SSID for the P2P Group.

In a variant to the above, the first station may be a P2P device different from the soft AP or P2P GO in the communication group. The first station may have established or joined a communication group with the owner of that group.

Whatever the case, the first station retrieves the above network information about the communication group to advertise. It is group-related information.

In embodiments, such information includes a Group BSSID defining a BSS IDenfifier for the communication group and an Operating Channel providing an Operating Class and a Channel Number that define the first (operating) channel. Optionally it may further include a Service Set Identifier, SSID, of the communication group. This is to allow other stations to easily identify the communication group as, e.g., a Wi-Fi Direct group when the SSID starts with "DIRECT". As mentioned above, the SSID may be provided through the P2P Group ID of the communication group.

Once the group-related information describing the communication group have been obtained, the process goes to step 511 in which the first station transitions to a second channel to notify about the communication group, in particular to request assistance to any AP camped on the second channel. In embodiments, the first station may first search for and find an AP operating on the second channel before sending the notification addressed to the AP. Hence, the first station switches from the first channel to a first one of second channels before sending the notification to an existing AP.

The second channel is distinct from the first channel (i.e., the operating channel of the communication group to advertise).

The first station may scan successively multiple channels (through the loop 511-512). The channels to scan may be predefined in a list of channels. They may include channels from either or multiple of the 2.4, 5 and 6 GHz bands.

Once in condition to operate on the second channel (i.e., after it has switched its radio to a second channel), the first station notifies at step 512 any AP operating on that second channel about the communication group, by sending a group announcing frame that includes the group-related information, over the second channel.

To do so, in embodiments, it sends, preferably broadcasts, a Probe Request frame including an information element 500 comprising the group-related information. In embodiments, the frame is a discovery assistance request to drive the AP to include the group-related information in frames (e.g., Beacon frames) sent over their respective operating second channels. In that way, the existence of the soft AP or P2P GO (and thus of the corresponding communication group) can be widely known by non-AP stations.

Plural APs operating on the second channel may receive the broadcast Probe Request frame, to spread the advertisement about the communication group to a higher number of stations.

The first station may optionally receive a Probe Response frame from one or more of these APs. Such Probe Response frame may for instance include a RNR element and a Basic Multi-Link element describing reported APs distinct from the reporting AP, within the same AP MLD.

The information element 500 may be based on various existing IEs to convey the group-related information needed to advertise the communication group. The Probe Request frame may include any of the following IEs to that end: a Channel Usage element, a Reduced Neighbor Report, RNR, element, a Neighbor Report element, and a Multi-Band element.

Channel Usage element 600 adapted to convey the group-related information according to some embodiments is described with reference to Figure 6. Channel usage information is a set of channels provided by an AP to non-AP STAs for operation of a non-infrastructure network. A non-AP STA supporting channel usage may conventionally send a Channel Usage Request frame at any time after association to the AP that supports the use of channel usage to request the channel usage information for supported operating classes.

The data payload of a Channel Usage element is shown under reference 600. The Channel Usage element 600 is made up of four fields: Element ID field 610, Length field 620, Usage Mode field 630 and Channel Entry field 640.

Two different values are defined for the Usage Mode field 630 in the IEEE P802.11-REVme/D2.1 version (January 2023): value 0 for Noninfrastructure IEEE 802.11 network and value 1 for Off-channel TDLS direct link. A recent adaptation of the standard seeks to provide another value, namely value 2, for Noninfrastructure IEEE 802.11 network in which none of the APs belonging to the same ESS operate infrastructure BSSs. Values 3 to 255 are conventionally reserved.

In some embodiments, value 2 is used in the Usage Mode field 630 to indicate the Channel Usage element includes the group-related information. In a preferred variant, new value 3 (or any other reserved value) 664 can be used to that end. New value 3 or the like may for instance be used to flag the frame is a request for discovery assistance as mentioned above. This is to drive the AP to then advertise about the communication group. Furthermore, in some embodiments, new value 3 or the like may indicate that the communication group is restricted to Wi-Fi P2P communication (i.e., it is a P2P Group). A recipient of such Channel Usage element 600 can easily determine the element concerns a software AP or P2P GO.

Channel Entry field 640 includes zero or more Operating Class 641 and Channel 642 fields. Operating Class field 641 indicates an operating class value. Channel field 642 indicates a channel number, which is interpreted in the context of the indicated Operating Class. Operating Class and Channel fields are defined in Annex E in the IEEE P802.11-REVme/D2.1 version. Operating Class and Channel fields can be grouped together to identify/define a noncontiguous channel as described in 9.4.2.70.3 (Location Indication Channels subelement). These two fields may therefore be set to the values (in the group-related information) defining the first channel of the communication group to advertise.

Furthermore, a new field 643 is added in Channel Entry field 640 to provide the other group-related information. For example, the new field 643 is a P2P IE embedding one or more P2P attributes, to convey the other information. In particular, it may include the P2P Group BSSID attribute and optionally the P2P Group ID attribute (including the SSID). In some embodiments, the Operating Channel attribute may be provided in the P2P IE, in which case Operating Class

641 and Channel 642 fields may not be used.

As such, information element 600 includes a P2P IE conveying all or part of the group-related information.

Reduced Neighbor Report (RNR) element 700 adapted to convey the group-related information according to some embodiments is described with reference to Figure 7, which reuses the same references as Figure 3 for the same fields.

The new format 700 (i.e., the indication that it concerns a soft AP or Group owner, or even only a P2P GO) is declared by having TBTT Information Field Type subfield 7211 set to new value 2. A recipient of such RNR element 700 can easily determine the element concerns a software AP or P2P GO.

In most cases, a single Neighbor AP Information field 320 is provided as only one soft AP or P2P GO is defined. Note that the RNR format is organized in such a way that several APs may be reported from a given couple <channel class, channel Number> in 324, therefore Neighbor AP Information field 320 reporting the soft AP or P2P GO may be listed along with other AP(s) the reporting AP is aware of. The following description will be made with only one soft AP or P2P GO, for the sake of illustration.

Therefore, the other fields of TBTT Information Header subfield 321 may be set as follows: - TBTT Information count 7213 is set to 1, as only one reported element (Neighbor AP Information field 320) is present.

- Filtered Neighbor AP subfield 7212 is still reserved.

Operating Class field 322 and Channel Number field 323 are set to the values of the Operating Channel of the communication group (in the same way as fields 641 and 642 discussed above for Channel Usage element 600) to indicate together the primary channel of the communication group.

TBTT Information Set field 730 in Neighbor AP Information field 320 is modified to include three fields (additional fields may be provided if needed). Short SSID, BSS parameters, 20MHz PSD fields, MLD Parameters of 430 are preferably not present in field 730.

Neighbor AP TBTT Offset 331 is set to value 255 indicating an unknown offset value. BSSID subfield 732 is set to the BSSID of the communication group, i.e., to the P2P Group BSSID attribute. A new field 750 is optionally added in TBTT Information Set field 730 to provide the other group-related information. For example, the new field 750 is a P2P IE embedding one or more P2P attributes, to convey the other information. In particular, it may include the P2P Group ID attribute (including the SSID). In some embodiments, P2P IE 750 may include part or all the P2P Group attributes mentioned above (P2P Group BSSID, P2P Group ID, operating channel), in which case corresponding fields 322, 323 and 732 may not be used.

In the example of the Figure, the TBTT Information Length subfield 7214 is set to 47, corresponding to the following fields: Neighbor AP TBTT Offset subfield 331, BSSID subfield 732 and P2P IE 750 embedding the P2P Group ID attribute.

Again, information element 700 includes a P2P IE conveying all or part of the group-related information.

Neighbor Report element 800 adapted to convey the group-related information according to some embodiments is described with reference to Figure 8. Neighbor Report information is typically delivered through a request/report action frame exchange. Client stations use Neighbor Report information to gain information from the associated AP about potential roaming neighbors to perform fast-roaming. Neighbor Report element basically describes an AP.

The new format 800 (i.e. the indication that it concerns a soft AP or Group owner, or even only a P2P GO) may be declared using any reserved bit in reserved fields 823 (any bit B21 to B31 in BSSID Information field 820, or B4 or B5 in Capabilities subfield 821). A recipient of such Neighbor Report element 800 can easily determine the element concerns a software AP or P2P GO.

BSSID field 810 is set to the BSSID of the communication group to advertise, i.e. to the P2P Group BSSID attribute of the group-related information.

BSSID Information field 820 can be used to help determine neighbor service set transition candidates. Inside BSSID Information field 820, one can note Colocated AP subfield 822. Traditionally, it is set to 1 to indicate that the AP reported in this Neighbor Report element is in the same colocated AP set as the AP sending the Neighbor Report element. If the first station in the present communication method is the soft AP or P2P GO, colocated AP subfield 822 is set to 1. Otherwise, it is set to 0.

Operating Class field 830 and Channel Number field 840 are set to the values of the Operating Channel of the communication group (in the same way as fields 641 and 642 discussed above for Channel Usage element 600) to indicate together the primary channel of the communication group.

A single Subelement is provided in Optional Subelements field 850 as only one soft AP or P2P GO is defined.

Subelement field has a common general format consisting of a 1-octet element-specific Subelement ID field 851, a 1-octet Length field 852, and a variable length subelement-specific Data field 853. A unique identifier is provided in Subelement ID field 851. Length field 852 specifies the number of octets in the Data field 853. Data field 853 is used as a field to convey the other group-related information not yet provided in Neighbor Report element 800. In particular, Data field 853 includes a P2P IE embedding one or more P2P attributes. It may include the P2P Group ID attribute (including the SSID) if provided. In some embodiments, P2P IE 853 may include part or all the P2P Group attributes mentioned above (P2P Group BSSID, P2P Group ID, operating channel), in which case corresponding fields 810, 830 and 840 may not be used.

Again, information element 800 includes a P2P IE conveying all or pad of the group-related information.

Multi-Band element 900 adapted to convey the group-related information according to some embodiments is described with reference to Figure 9. Prior to the introduction of Multi-Link devices by 802.11be, a multi-band capable device (as originally defined by 802.11ad standard) was able to manage operation over more than one frequency band/channel. The operation across the different frequency bands/channels could have been simultaneous or non-simultaneous. The multi-band capable device could support operation on one frequency band at a time and transfer between frequency bands. In this context, the Multi-band element was used to indicate that the STA transmitting it was within a multi-band device capable of operating in a frequency band or operating class or channel other than the one in which this element is transmitted. In addition, if used as part of a fast session transfer, this element indicated that the transmitting STA was able to accomplish a fast session transfer from the current channel to a channel using another STA in the same device, in the other or same band.

The new format 900 (i.e., the indication that it concerns a soft AP or Group owner, or even only a P2P GO) may be declared using STA Role subfield 911 in Multi-Band Control field 910 and/or any reserved bit B5-B7 in Multi-Band Connection Capability subfield 950. STA Role subfield 911 specifies the role the transmitting STA plays on the channel of the Operating Class indicated in the Multi-Band element 900. A new value, e.g. value 5 (or the like), is used in STA Role subfield 911 to declare soft AP/P2P GO. Discovery Assistance Enabled subfield 916 in Multi-Band Control field 910 indicates whether the STA supports the multi-band discovery assistance procedure for the BSS defined by the BSSID field on the channel defined by the Band ID field, the Operating Class field, and the Channel Number field. In embodiments, the Discovery Assistance Enabled subfield 916 is set to 1 when STA Role subfield 911 is set to 5 or the like. This clearly declares that discovery assistance is requested to the destination AP. A recipient of such Multi-Band element 900 can easily determine the element concerns a software AP or P2P GO.

Band ID field 960 provides the identification of the frequency band related to the Operating Class and Channel Number fields. Band ID field 960 is defined in Table 9-95 of REVme D2.1, and can takes exemplary values of 2, 4, 6 for respectively 2.4GHz, 5Ghz or 6Ghz.

Operating Class field 920 and Channel Number field 930 are set to the values of the Operating Channel of the communication group (in the same way as fields 641 and 642 discussed above for Channel Usage element 600) to indicate together the primary channel of the communication group.

BSSID field 940 is set to the BSSID of the communication group to advertise, i.e. to the P2P Group BSSID attribute of the group-related information.

Beacon Interval field 970 conventionally specifies the size of the beacon interval for the BSS declared in the Multi-Band element. In embodiments, this field may be set to 0 as no P2P communication group is actually in operation in the indicated Channel and Frequency Band at the time of sending the Multi-Band element.

Multi-band Connection Capability field 950 indicates the connection capabilities supported by the STA on the Channel and Frequency Band indicated in this element. AP field 951 specifies whether the STA can function as an AP on the Channel and Band indicated in the element. It is set to 1 when the STA is capable to function as a soft AP or P2P GO, and it is set to 0 otherwise. Optionally, a soft AP/ P2P GO field can be envisaged (e.g. in location B5 952) to specify whether the STA can function as an soft AP/P2P GO on the Channel and Band indicated in the element. It is set to 1 when the STA is capable to function as a soft AP/P2P GO, and it is set to 0 otherwise.

A new field 980 is optionally added in Multi-Band element 900 to provide the other group-related information. For example, the new field 980 is a P2P IE embedding one or more P2P attributes, to convey the other information. In particular, it may include the P2P Group ID attribute (including the SSID). In some embodiments, P2P IE 980 may include part or all the P2P Group attributes mentioned above (P2P Group BSSID, P2P Group ID, operating channel), in which case corresponding fields 920, 930 and 940 may not be used.

Again, information element 900 includes a P2P IE conveying all or part of the group-related information.

Alternative types of group announcing frame to the Probe Request frame may be used, including e.g., a Generic Advertisement Protocol, GAS, Initial Public Action frame or a P2P Invitation Request frame. More generally, any unicast frame such as an Action frame or a Public Action frame may be used to convey the group-related information in an appropriate information element 500.

For instance, a GAS Initial Response frame may include a Multi-Band element such as the one of Figure 9. It may also (or alternatively) include an Access Network Query Protocol, ANQP, element, which itself contains a Neighbor Report element as the one of Figure 8 or an AP List Response ANQP element which is also adapted to convey the group-related information.

To illustrate, Generic Advertisement Protocol (GAS) specified by 802.11u is a L2 Query /Response protocols implemented through the use of Public Action frames that allow two non-associated 802.11 devices to exchange queries belonging to a higher layer protocol (e.g. a service discovery protocol). GAS is implemented by means of a generic container that allows the recipient device to identify the higher layer protocol being transported, and is used as a container for ANQP (Access Network Query Protocol) elements sent between clients and APs. The ANQP mechanism may be envisaged to inform/notify any AP about the communication group (P2P Group).

Among existing ANQP elements useful for embodiments, there is the Neighbor Report element and a so-called AP List Response element. The Neighbor Report ANQP-element provides zero or more neighbor reports about neighboring APs. A modified Neighbor Report element as in Figure 8 may be used to describe the communication group (i.e. its soft AP or P2P GO). On the other hand, the AP List Response ANQP element conventionally provides responses to a Query AP List ANQP element request. In embodiments of the invention, the AP List Response ANQP element may be used spontaneously by the first station (i.e. not in response to a request/query from an AP) to provide a list of APs, including the soft AP or P2P GO of the communication group. In such a case, the variable-length ANQP-element-specific Information field is used to convey the BSSID of the communication group in which the first station operates. Of course, any new ANQP element may be envisaged (use of Reserved element entries in Table 9-411 of REVme D2.1) to embed the group-related information.

The P2P Invitation mechanism is also adapted to provide notification within the meaning of the invention. Traditionally, a P2P Invitation Request frame (which is a P2P PublicAction frame) transmitted by a P2P Group Owner to another P2P Device includes P2P Group ID, P2P Group BSSID, Channel List, Operating Channel and Configuration Timeout attributes in a P2P IE 480.

In some embodiments, the group announcing frame is a P2P Invitation Request frame sent to an AP operating on a second channel, thereby contrasting with a conventional use of such a frame sent to a P2P device (hence non-AP). In some embodiments, only a subset of those attributes is signalled in a P2P IE of the invitation frame, e.g., P2P Group BSSID, P2P Group ID, optional Channel List and Operating Channel. Note that the Channel List attribute, mandatorily present in a P2P invitation frame, may be limited to list only the operating channel. This is to reduce signalling costs and make the discovery of the soft AP/P2P GO faster, through the assistance of the existing APs.

Once the group announcing frame has been sent over a second channel at step 512, the process loops back to step 511 to select another "second channel" where notifying another (or multiple) APs. The next second channel may be the next one in the predefined list of channels mentioned above.

As mentioned above, the first station may optionally receive a response (e.g. a Probe Response frame) to its group announcing frame from an AP. Usually, such response, in particular a Probe Response frame, may include a RNR element and a Basic Multi-Link element describing reported APs distinct from the reporting AP, within the same AP MLD of the reporting AP belongs to an AP MLD. In that case, the first station becomes aware of other APs operating on other second channels, that are affiliated to the same AP MLD as the one already targeted (with the notification). Taking advantage of this knowledge, the first station may decide the AP MLD is already aware of the communication group and therefore there is no need to notify its other affiliated APs with the same information. Indeed, the AP MLD may itself use the obtained notification to advertise about the communication group over any and all of its affiliated APs. This is described below. At the end, this is to save time to notifying the APs, hence to improve network efficiency. In particular, the first station is liable to switch back sooner to its operating channel to operate its communication group.

In this MLD context, the first station may therefore reduce the predefined list of channels to scan by removing the channels corresponding to the other affiliated APs of the same AP MLD. In that case, the selection of the second channels by the first station is based on channels corresponding to a set of enabled links for an AP MLD having multiple affiliated APs: the selection selects only one channel for scanning, from channels corresponding to a given set of enabled links for an AP MLD having multiple of the other APs as affiliated APs.

The loop 511-512 allows the first station to scan through multiple second channels, hence to notify multiple APs about the communication group.

After all the second channels have been processed, the first station switches back to its operating channel to operate its communication group, either as a soft AP/P2P2 GO or as a mere station of the group. This is step 513.

One may notice that the loops 511-512 take substantially less time than the hundreds of TUs (1 TU = 1024ps) of the conventional Wi-H Direct device discovery procedure 400.

Turning now to Figure 5b, it illustrates, using a flowchart, a communication method facilitating the discovery of communication groups, at an AP (e.g., AP 110) receiving a notification about a communication group from a first station and then advertising about the communication group over its operating channel.

In this method, the AP indeed receives, from the first station and over a second channel (on which the AP operates), a group announcing frame that includes group-related information describing a communication group managed by a first AP and configured to operate on a first channel. Next and responsive to the receiving, the AP has to advertise, over its operating (second) channel, the other stations about such communication group. To do so, it first generates, based on the received group-related information, a reported-AP element describing the communication group, and then sends, over the second channel, a frame including the reported-AP element to advertise the communication group within the BSS. In that way, all stations, e.g., stations willing to operate P2P communication, operating on the same second channel become aware of the communication group, e.g. P2P Group, without requiring them to perform a discovery procedure dedicated to the communication group on specific channels (e.g. social channels).

Preferably, the AP performing the method of the Figure is the AP of an infrastructure BSS, meaning it is an existing and permanent AP.

At step 520, the AP thus receives the group announcing frame over its operating second channel, the frame embedding information element 500 related to a soft AP or P2P GO in another (first) channel. This step mirrors step 512 made by the first station over the same second channel.

The received frame is typically, but not exclusively, a Probe Request frame, a Generic Advertisement Protocol (GAS) Initial Response frame or a P2P Invitation Request frame, as described above.

The information element 500 is typically, but not exclusively, a Reduced Neighbor Report, RNR, element, a Channel Usage element, a Neighbor Report element, a Multi-Band element, or an AP List Response ANQP element, as described above.

Optionally, the AP may determine that the group announcing frame requests discovery assistance to the AP, i.e. requests the AP to include the group-related information in advertising frames. The assistance request indication can transpire from the value of Usage Mode field 630, or TBTT Information Field Type field 7211 or Reserved field 823 or STA Role field 911 or Discovery Assistance Enabled field 916 or Reserved field 952.

Responsive to the reception, at step 521, the information about the communication group is retrieved or decoded from the received information element 500. This step merely consists in retrieving the appropriate fields (e.g., described above with reference to Figures 6 to 9) carrying the Group BSSID, the Operating Class and Channel Number, the Service Set Identifier, SSID, of the communication group, and more generally the P2P Group BSSID, the Operating Channel and the P2P Group ID.

Immediately following step 521, step 522 consists for the AP to prepare a reported-AP element advertising information about the communication group. In other words, the reported-AP is an advertisement information element to be used in an advertisement frame to advertise stations over the second channel about the communication group.

In some embodiments, the reported-AP element is included in or is modified Reduced Neighbor Report, RNR, element 700 as described above with reference to Figure 7. That means that the various formats described above (e.g., Figures 6 to 9) carrying the group-related information are translated into a single RNR format as described in Figure 7.

To illustrate, the reported-AP element may therefore include a Neighbor AP Information field 320 that comprises: an Operating Class field 322 and a Channel Number field 323 defining, together, the first channel, a BSSID field 732 defining a BSS IDentifier for the communication group, and an optional P2P IE 750 which may convey additional group-related information, such a Service Set Identifier, SSID, of the communication group or a Group ID element.

Of course, all or part of the group-related information to advertise may be included in the P2P IE rather than reusing existing fields in the RNR element. In that case, the reported-AP element includes a P2P IE conveying all or part of the group-related information.

To minimize the size of the reported-AP element, the Neighbor AP Information field 320 includes a TBTT Information Set field 324 made of a Neighbor AP TBTT Offset field 331, the BSSID field 732 and the P2P IE 750. To allow quickly identifying the RNR as describing a soft AP/P2P GO, the Neighbor AP Information field 320 includes a TBTT Information Field Type field 7211 set to a value indicating a peer-to-peer, P2P, Group Owner or a soft or mobile AP managing an ad hoc network.

Once the reported-AP element has been prepared, it is sent (still at step 522) in an advertising frame over the second channel in which the AP operates. This ensures the communication group is made known by stations operating on the same second channel (either station belonging to the BSS of the AP or any station, depending on the advertising frame used). The advertising frame including the reported-AP element is preferably a management frame, such as a Beacon frame or a Probe Response frame. Alternatively, it may be a Fast Initial Link Setup, FILS, Discovery Public Action frame.

These frames can advantageously be broadcast to reach the highest number of stations. In particular, the Probe Response frame may be sent in response to a Probe Request frame notifying the communication group (i.e., sent at step 512 by the first station), in which Probe Response frame the destination address in the MAC header is set to broadcast address.

As explained above, comparative to a conventional RNR element describing reported APs of an MLD, in the present advertising frame, there is no Per-STA Profile element relating to the communication group, within a Basic Multi-Link element 252 embedded in the same frame. To take benefit of the MLD context (in case of an AP MLD), the AP receiving the notification (hence being first aware of the communication group within the AP MLD) may decide to share this information with the other APs affiliated to the same AP MLD in order to advertise about the same communication group over the other respective channels. In that case, step 522 which is still responsive to the receiving of the notification includes for the AP to send by one or more other APs affiliated to the AP MLD, over respective other operating channels, an advertising frame (any format mentioned previously) including the reported-AP element to advertise the communication group over their respective operating channels, e.g. within respective BSSs. A high number of stations is thus made aware of the communication group.

Turning now to Figure 5c, it illustrates, using a flowchart, a communication method facilitating the discovery of communication groups, at a station (e.g. 102 or 402) being advertised by an AP about the communication group. The station may be any station listening on an operating channel in which an AP also operated, be it associated or not with the AP. In this method, the station receives from an AP managing an infrastructure network in a second channel, an advertising frame including a reported-AP element advertising a communication group in an ad hoc mode (typically a P2P Group) managed by a first station acting as a P2P GO or soft/mobile AP, the communication group being configured to operate on a first channel. Thanks to this information, the station wishing for example to perform P2P communication may decide to join the advertised communication group, by switching an operating channel of the station from the second channel to the first channel as retrieved from the reported-AP element, and then joining the communication group in the ad hoc mode on the first channel.

As a result, the station becomes able to operate within the communication group although the station has not spent time to gain knowledge of the existence of the communication group and then to perform a dedicated discovery procedure. The station only has to perform conventional discovery on the channel on which it currently operates.

Therefore, at step 530, the station scans its operating channel to detect any reported-AP element according to the invention, from an AP. For example, in a passive scanning, the station detects a Beacon frame or a FILS Discovery frame that is broadcasted by the AP on the operating channel and that includes an RNR element 700 advertising about soft AP/P2P GO. The station may first determine that a received reported-AP or RNR element relates to a peer-to-peer, P2P, Group Owner or a soft or mobile AP managing an ad hoc network. It can be readily recognized by reading TBTT Information Field Type field 7211 set to a value indicating a peer-to-peer, P2P, Group Owner or a soft or mobile AP managing an ad hoc network.

Optionally, if no reported-AP is obtained through passive scanning after a particular time period, the station may perform active scanning at step 531. This may be the case for a station willing to perform P2P communication and therefore willing to join a P2P Group.

To do so, it generates and transmits (e.g., broadcasts) a Probe Request frame over the operating channel. This is to obtain a Probe Response frame from the AP, which would include an RNR element 700 advertising about a soft AP/P2P GO.

In any case where a reported-AP element advertising about a soft AP/P2P GO is obtained, information about the soft AP/P2P GO is obtained by the station at step 532 from the received information. For example, the station may retrieve, from the received RNR element 700 broadcasted by the AP, the Operating Channel on which the soft AP operates (this is the first channel), a TBTT element of the soft AP that indicates the BSSID of the communication group and its SSID.

Decision to search for a soft AP/P2P GO may result from a will of the station to perform P2P communication and thus to join a P2P Group. In that case, selecting the communication group (to join) may be responsive to locally determining P2P data to be sent directly to a destination station.

Of course, various groups may be identified by the station through one or more advertising frames received from one or more APs. In that case, the station selects the communication group from amongst multiple groups corresponding to multiple reported-AP elements included in one or more received frames.

Should P2P be given favour, e.g., a Wi-Fi Direct Group, the station may select a P2P group by determining that a Service Set Identifier, SSID, of the communication group specified in the reported-AP element matches a template value, e.g., the "DIRECT-xy" format.

The BSSID of the communication group can also be retrieved from the received information.

Based on all the information retrieved, the station can exit its current infrastructure BSS and switch its operating channel to the first channel corresponding to the targeted communication group. This is step 533. To do so, it modifies the operating channel of its radio, by targeting the retrieved Operating Channel (Operating Class and Channel Number).

Next, once camped on the first channel of the communication group, the station may join the communication group by using the BSSID. This is step 534. In particular, the station may establish a communication link (e.g., initiate an authentication/association process) with the software access point operated by first station, based on the obtained information from the RNR 700.

In embodiments, the station sends a Probe Request frame having a BSSID field set to the retrieved BSSID. Preferably, the station may narrow its scan to the specific P2P GO of the communication group, by including the P2P Device ID attribute (containing the P2P Device Address field value of RNR 700) in the P2P IE of the Probe Request frame. In particular, the device address of the P2P GO (as retrieved from the P2P Group ID) is used to send the Probe Request frame to the P2P GO only.

From then, the station can enjoy the communication group, in particular to perform efficient P2P communication.

Figure 10a illustrates an AP assistance mechanism for improved discovery of a P2P Group involving single-link APs (i.e., non-MLD), according to embodiments. In the scenario presented, a first non-AP station (first STA performing the method of Figure 5a) creates a P2P Group operating on a first channel Ch.1 (the station may be the P2P GO), a second station (second STA performing the method of Figure 5c) wishes to directly communication with the first station or any station of the P2P Group, and two APs (performing the method of Figure 5b) of infrastructure BSSs exist and operate on different channels Ch.2 (for AP1) & Ch.3 (for AP2) other than Ch.1.

Through implementation of the method of Figure 5a, the first station successively switches to various channels (Ch.2 & Ch.3), optionally determines whether any AP operates on these channels and, in the affirmative, sends the group announcing frame that includes information element 500 describing the P2P Group to such APs over respective channels.

The APs may advertise their capabilities to support the invention, e.g., in a Beacon frame (received by the first station).

A Probe Request frame 1012 (can be single link) is provided as an illustration. It contains any of information elements 600, 700, 800, 900 discussed above. Through the frame, the first station requests assistance to each AP for P2P discovery.

After transmission of the Probe Request frames 1012 to each AP, the first station immediately switches back to its operating channel Ch.1 where it operates as a P2P Group Owner.

Next, each AP builds an advertising frame conveying the information 500 about the P2P Group based on the received information element 500 and then sends it over its operating channel. For example, a Beacon frame 1011a is broadcast, or a FILS Discovery frame, containing a RNR 700 reporting a soft AP/P2P GO (730) on the first channel Ch.1.

Any station, such as the second station, operating on either channel Ch.2 & Ch.3 receives the Beacon frame 1011a, from which it detects that a P2P Group is currently operating on channel Ch.1. Should such station wishing to operate P2P communication, responsive to such detection, it switches to channel Ch.1 where it joins the P2P Group, by sending e.g., a Probe Request frame 212.

Compared to the scenario of Figure 10a, the AP MLD (hence the internal communication between AP1 and AP2) allows the first station, once it detects AP1 operating on channel Ch.2, not to switch on channel Ch.3 to notify AP2 about the P2P Group. This is because, according to embodiments, the AP MLD itself will propagate the information about the P2P Group throughout its affiliated APs as soon as one of them receives such information.

Through implementation of the method of Figure 5a, the first station thus switches to channel Ch.2 first where it sends Probe Request frame 1012 to notify AP1 about the P2P Group. Having knowledge that AP1 belongs to an AP MLD having also AP2 as affiliated AP (e.g. as defined in a Beacon frame sent by AP1 or a Probe Response frame sent by AP1), the first station decides not to switch on channel Ch.3.

Consequently, after transmission of Probe Request frames 1012 to AP1, the first station immediately switches back to its operating channel Ch.1 where it operates as a P2P Group Owner.

Next, AP1 builds Beacon frame 1011 b conveying RNR 700 about the P2P Group based on the received information element 500 and then broadcasts it over its operating channel Ch.2.

Simultaneously, AP2 is notified, within AP MLD, of received information element 500. It can then also build a Beacon frame 1011b conveying RNR 700 about the P2P Group based on the same information element 500 and broadcasts it over its operating channel, here Ch.3.

In the present scenario, the second station operates on channel Ch.3 and therefore receives Beacon frame 1011b from AP2, from which it detects that a P2P Group is currently operating on channel Ch.1.

Alternatively, in embodiments with active scanning, the second station may send a Probe Request frame to AP2 and then receives, in response, a Probe Response frame 1013 that includes RNR 700 about the P2P Group. As a result, the second station detects that a P2P Group is currently operating on channel Ch.1.

Should the second station wishing to operate P2P communication, it can switch to channel Ch.1 responsive to the detection of the P2P Group on channel Ch.1, and then joins the P2P Group, by sending e.g., a Probe Request frame 212.

Of course, scenario may involve both single-link APs and AP MLDs, in particular as the number of channels is increasing.

Figure 11a schematically illustrates a communication device 1100, either a non-AP STA, or a non-AP MLD, embedding a plurality of non-AP stations 110x-y-z0, or an AP 110, or an AP MLD, embedding a plurality of APs 110, of a radio network NETW, configured to implement at least one embodiment of the present invention. The communication device 1100 may preferably be a device such as a micro-computer, a workstation or a light portable device. The communication device 1100 comprises a communication bus 1113 to which there are preferably connected: a central processing unit 1101, such as a processor, denoted CPU; a memory 1103 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 1102 connected to a wireless communication network, for example a communication network according to one of the IEEE 802.11 family of standards, including Wi-Fi alliance protocols such as Wi-Fi P2P, via transmitting and receiving antennas 1104.

Preferably the communication bus provides communication and interoperability between the various elements included in the communication device 1100 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 1100 directly or by means of another element of the communication device 1100.

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 1102, in order to be stored in the memory of the communication device 1100 before being executed.

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

Figure 11b is a block diagram schematically illustrating the architecture of the communication device 1100, adapted to carry out, at least partially, the invention. As illustrated, device 1100 comprises a physical (PHY) layer block 1123, a MAC layer block 1122, and an application layer block 1121.

The PHY layer block 1123 (here a multiple of 802.11 standardized PHY layer modules) has the task of formatting, modulating on or demodulating from any 20MHz channel or the composite channel, and thus sending or receiving frames over the radio medium NETW, such as 802.11 frames, for MAC data, action and management frames based on a 20MHz width to interact with 802.11 stations to/from that radio medium.

The MAC layer block or controller 1122 preferably comprises a MLE MAC 802.11 layer 1124 implementing conventional 802.11 MAC operations, and additional block 1125 for carrying out, at least partially, embodiments of the invention. The MAC layer block 1122 may optionally be implemented in software, which software is loaded into RAM 1103 and executed by CPU 1101.

The MLE MAC 802.11 layer 1124 may implement an Upper-MAC stack along with a series of Lower-MAC modules.

Preferably, the additional block 1125, referred to as P2P discovery module for performing discovery operation for soft AP (or P2P GO) service over single and multi-link communications, implements part of embodiments of the invention. This block performs the operations of Figure 5a or 5b or 5c or 10a or 10b (supplemented with the details of any of Figures 6 to 9) depending on the role of the communication device 1100, AP or non-AP station.

MAC 802.11-layer 1124 and P2P discovery 1125 interact one with the other in order to establish and process accurately communications in between multiple stations according to embodiments of the invention.

On top of the Figure 11b, application layer block 1121 runs an application that generates and receives data packets, for example data packets such as a video stream. Application layer block 1121 represents all the stack layers above MAC layer according to ISO standardization.

Although the present invention has been described herein above 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

CLAIMS1. A communication method in a wireless network, comprising at a first station belonging to a communication group that is managed by a first access point, AP, and is configured to operate on a first channel: obtaining group-related information describing the communication group, and sending a group announcing frame that includes the group-related information, to one or more second APs over respective second channels.
2. The method of Claim 1, wherein the first station, responsive to the sending, switches to the first channel to operate communication within the communication group.
3. The method of Claim 1, wherein the first station is a P2P group owner of the P2P group.
4. The method of Claim 1, wherein the first station scans channels to determine the one or more second channels on which second APs operate and switches from the first channel to a first one of the second channels before sending the group announcing frame.
5. The method of Claim 1, wherein the first station selects the one or more second channels from detected channels on which other APs operate, wherein the selection is based on channels corresponding to a set of enabled links for an AP multi-link device, MLD, having multiple of the other APs as affiliated APs.
6. The method of Claim 5, wherein the selection selects only one channel from detected channels corresponding to a given set of enabled links for an AP MLD having multiple of the other APs as affiliated APs.
7. The method of Claim 1, wherein the group announcing frame includes a discovery assistance request to drive the second AP or APs to include the group-related information in frames sent over their respective operating second channels.
8. A communication method in a wireless network, comprising at a second access point, AP, operating a basic service set, BSS, on a second channel: receiving, over the second channel, a group announcing frame that includes group-related information describing a communication group managed by a first AP and configured to operate on a first channel, responsive to the receiving: generating, based on the received group-related information, a reported-AP element describing the communication group, and sending, over the second channel, a frame including the reported-AP element to advertise the communication group within the BSS.
9. The method of Claim 8, wherein the second AP is affiliated to an AP multi-link device, MLD, and the method further comprises, responsive to the receiving, sending by one or more other APs affiliated to the same AP MLD, over respective other operating channels, a frame including the reported-AP element to advertise the communication group within their respective operating channels.
10. The method of Claim 1 or 8, wherein the communication group is a peer-to-peer, P2P, group.
11. The method of Claim 10, wherein the first AP is a soft or mobile AP managing an ad hoc network and the second AP is an AP managing a basic service set, BSS, in infrastructure mode.
12. The method of Claim 1 or 8, wherein the group announcing frame includes one information element, 1E, from: a Reduced Neighbor Report, RNR, element, a Channel Usage element, a Neighbor Report element, a Multi-Band element, and an AP List Response ANQP element.
13. The method of Claim 12, wherein the information element includes a P2P IE conveying all or part of the group-related information.
14. The method of Claim 1 or 8, wherein the group-related information includes a Group BSSID defining a BSS IDentifier for the communication group and an Operating Channel providing an Operating Class and a Channel Number that define the first channel.
15. The method of Claim 14, wherein the group-related information further includes a Service Set Identifier, SSID, of the communication group.
16. The method of Claim 1 or 8, wherein the group announcing frame is one from: a Probe Request frame, a Generic Advertisement Protocol, GAS, Initial Public Action frame embedding an Access Network Query Protocol, ANQP, element, a P2P Invitation Request frame.
17. A communication method in a wireless network, comprising at a second station operating on a second channel: receiving from a second access point, AP, over the second channel, a frame including a reported-AP element advertising a communication group managed by a first AP and configured to operate on a first channel, switching an operating channel of the second station from the second channel to the first channel as retrieved from the reported-AP element, and joining the communication group on the first channel.
18. The method of Claim 17, wherein the second station determines that the reported-AP element relates to a peer-to-peer, P2P, Group Owner or a soft or mobile AP managing an ad hoc network.
19. The method of Claim 17, wherein joining the communication group includes: retrieving, from the reported-AP element, a BSS IDentifier of the communication group, and sending a Probe Request frame having a BSSID field set to the retrieved BSS IDentifier.
20. The method of Claim 19, wherein joining the communication group further includes retrieving, from the reported-AP element, a device address of an owner of the communication group, wherein the Probe Request frame is sent using the retrieved device address.
21. The method of Claim 17, wherein the communication group is a peer-to-peer, P2P, group, and the method further comprises, at the second station, selecting the communication group from amongst multiple groups corresponding to multiple reported-AP elements included in one or more received frames.
22. The method of Claim 21, wherein selecting the P2P group is responsive to locally determining P2P data to be sent directly to a destination station.
23. The method of Claim 21, wherein selecting the P2P group includes determining that a Service Set Identifier, SSID, of the communication group specified in the reported-AP element matches a template value.
24. The method of Claim 8 or 17, wherein the reported-AP element is included in a Reduced Neighbor Report, RNR, element.
25. The method of Claim 24, wherein the reported-AP element includes a P2P IE conveying all or part of the group-related information.
26. The method of Claim 24, wherein the reported-AP element includes a Neighbor APInformation field that comprises:an Operating Class field and a Channel Number field defining, together, the first channel, anda TBTT Information Set field made of:a Neighbor AP TBTT Offset field,a BSSID field defining a BSS IDentifier for the communication group, and the P2P IE.
27. The method of Claim 26, wherein the P2P IE includes a Service Set Identifier, SSID, of the communication group.
28. The method of Claim 26, wherein the Neighbor AP Information field includes a TBTT Information Field Type field set to a value indicating a peer-to-peer, P2P, Group Owner or a soft or mobile AP managing an ad hoc network.
29. The method of Claim 8 or 17, wherein no Per-STA Profile element within a Basic Multi-Link element embedded in the same frame sent by the second AP relate to the communication group.
30. The method of Claim 8 or 17, wherein the frame including the reported-AP element is a management frame, such as a Beacon frame or a Probe Response frame, or is a Fast Initial Link Setup, FILS, Discovery Public Action frame.
31. The method of Claim 30, wherein the frame including the reported-AP element is broadcast by the second AP.
32. A communication device comprising at least one microprocessor configured for carrying out the steps of the method of Claim 1 or 8 or 17.
33. A non-transitory computer-readable medium storing a program which, when executed by a microprocessor or computer system in a communication device, causes the communication device to carry out the steps of the method of Claim 1 or 8 or 17.