Improved off-channel communication method and system for multi-link P2P stations

Abstract

An improved off-channel communication method and system for multilink P2P stations is provided. A non-AP MLD acquires a link ID defining an off-link corresponding to at least one off-channel that does not overlap with a channel used by an AP device. The non-AP MLD establishes a TDLS direct link between a first TDLS STA and a second TDLS STA belonging to the non-AP MLD using the link ID as an off-link indication for the TDLS direct link through the channel used by the AP device. The non-AP operates peer-to-peer communication between the first TDLS STA and the second TDLS STA via the off-link.

Description

[Technical Field]

[0001] The present invention relates generally to wireless communications, and more particularly to peer-to-peer (P2P) communications with multi-link (ML) devices. [Background technology]

[0002] Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing available network resources. Examples of such multiple-access networks include code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, and single-carrier FDMA (SC-FDMA) networks.

[0003] The 802.11 family of standards adopted by the Institute of Electrical and Electronics Engineers (IEEE®) provides numerous mechanisms for wireless communication between STAs.

[0004] With the development of latency-sensitive applications such as online gaming, real-time video streaming, virtual reality, and remote control of drones and robots, the requirements and issues of better throughput, lower latency, and robustness must be considered. These issues are currently under consideration by the IEEE 802.11 Working Group with the primary objective of issuing the next major 802.11 release, known as 802.11be or EHT (Extremely High Throughput).

[0005] The IEEE P802.11be / D2.2 version (October 2022, hereinafter referred to as the "D2.2 standard") introduced multi-link (ML) operation (MLO), which improves data throughput by enabling communication between STAs over multiple simultaneous and discontinuous communication links.

[0006] MLO allows a non-AP (access point) MLD (ML device) to register with an AP MLD, i.e., discover, authenticate, associate, and establish multiple communication links with the AP MLD. Each communication link thus set up (hereinafter referred to as a "setup link" or, once activated, an "activated link") enables channel access and frame exchange between the non-AP MLD and the AP MLD based on the supported capabilities exchanged during the association procedure.

[0007] An MLD is a logical entity with a single Medium Access Control (MAC) Service Access Point (SAP) for a Logical Link Control (LLC) with multiple affiliated stations (STAs) and one MAC data service. Thus, an AP MLD consists of multiple affiliated APs, while a non-AP MLD consists of multiple affiliated non-AP STAs. Affiliated STAs in both AP and non-AP MLDs can use 802.11 mechanisms to communicate with affiliated STAs in another MLD over each of the configured multiple communication links.

[0008] The existing Tunneled Direct Link Setup (TDLS) is adapted to coexist with the MLD in the D2.2 standard. More precisely, the D2.2 standard adapts the TDLS mechanism to the multi-link function by adjusting the signaling of MAC addresses in the setup frame when establishing a TDLS session over one of multiple setup links. As a result, a direct link consisting of a single communication link (e.g., a 20 MHz channel in either the 2.4, 5, or 6 GHz band) is established between two wireless STAs (TDLS peer STAs), each of which belongs to the MLD.

[0009] TDLS, approved by the IEEE 802.11z standard in 2008, enables devices (called TDLS peer STAs) to directly link with each other when connected to a conventional AP. To establish and maintain a direct link, both TDLS peer STAs must associate with the same infrastructure BSS (i.e., the same AP). TDLS encapsulates setup frames exchanged between two TDLS peer STAs in data frames. This allows the setup frames to be transmitted transparently (or "tunneled") through the AP. The setup frames contain so-called TDLS action frames. Furthermore, because the setup frames are transmitted transparently through the AP, the AP does not need to be TDLS-aware or have the same capabilities as the TDLS peer STAs involved in TDLS-based peer-to-peer communication. After the direct link is set up, the TDLS peer STAs can communicate directly with each other through the set up direct link without going through the AP, although they maintain their association with the AP. It should be noted that when TDLS peer STAs communicate directly over a direct link, P2P traffic competes with other traffic to / from the AP because the P2P traffic and other traffic to / from the AP are carried over the same communication link, i.e., the same frequency channel.

[0010] To reduce contention with AP-related traffic, it has been proposed to switch between such a channel used by the AP (called the "base channel") and an associated off-channel. This mechanism is known as "TDLS channel switching".

[0011] The IEEE P802.11-REVme / D2.0 version (October 2022) defines the off-channel. An off-channel is a channel used by a TDLS peer STA that does not overlap with the channel used by the AP with which the TDLS peer STA is associated. In other words, an off-channel is a channel that does not belong to the AP's operating channel and can be used for P2P communication. TDLS devices can negotiate a switch from a base channel (shared with the AP and used to set up a TDLS direct link) to such an off-channel (not shared with the AP). Two TDLS devices advertise in advance in TDLS setup frames (typically requests and responses) that they at least partially support the same channels, including the off-channel. Before switching from the base channel to the off-channel, the TDLS device is in power save (PS) mode with the AP and is not involved in any active service period with the AP.

[0012] When operating off-channel, a TDLS device remains in power save mode on the base channel and is unable to communicate with the AP, so it must periodically, or repeatedly, return to the base channel to receive beacons, check the Traffic Indication Map (TIM) for buffered packets, and communicate with other devices in the network.

[0013] Despite the great interest in improving the coexistence of infrastructure and P2P communications, the use of off-channels, as defined in the P802.11-REVme / D2.0 version, requires following legacy behavior, i.e., repeated TDLS channel switching (to switch back and forth between the base channel and off-channel), which is of course not optimal, since the repeated TDLS channel switching means that TDLS devices (TDLS peer STAs) cannot permanently use off-channels for TDLS (P2P) communications.

[0014] Therefore, there is a need to improve off-channel utilization mechanisms in the context of multi-link (multi-radio) mechanisms. Summary of the Invention

[0015] A broad object of the present invention is to overcome some of the above-mentioned concerns.

[0016] The inventors have realized that the above-mentioned deficiency is due to the fact that a non-AP MLD, regardless of its multi-link (multi-radio) capability, cannot persistently use an off-channel for TDLS transmission while maintaining (i.e., remaining active) a channel for communication with an AP, for example, to obtain beacon frames. Therefore, the present invention defines a new mechanism that enables a non-AP MLD to persistently use an off-channel for TDLS transmission, eliminating the need to repeatedly switch between the off-channel and the base channel.

[0017] In this context, an embodiment of the present invention is a method of communication in a wireless network, comprising: in a non-AP multi-link device (MLD) associated with an access point (AP) device: Obtaining a link identifier (ID) defining an off-link corresponding to at least one off-channel that does not overlap with a channel used by the AP device; establishing a Tunneled Direct Link Setup (TDLS) direct link between a first TDLS station (STA) belonging to the non-AP MLD and a second TDLS STA belonging to another non-AP MLD, via the channel used by the AP device, by using the link ID as the off-link indication for the TDLS direct link; operating peer-to-peer communication between the first TDLS STA and the second TDLS STA via the off-link; This is directed to a communication method including:

[0018] Therefore, a new link ID is proposed to define a new link called "off-link" that is independent of the base channel and link setup with the AP device. As detailed below, establishing a TDLS direct link using this new link ID: Directly, i.e., using the link ID directly to define the off-link as a TDLS direct link (there is no channel switch in this case), or Indirectly, i.e., by a two-step mechanism of first setting up a TDLS direct link (in the traditional way) and then performing a channel switch using the off-link's channel as the target channel of the target link, or by performing a link switch using the link ID to define the off-link as the target link of the link switch. It can be executed.

[0019] In both cases, the off-channel is defined as its own link (i.e., a new off-link) through the use of a new link ID that is independent of the base channel (which defines the link over which the traditional TDLS direct link is established). Indeed, in the first case, there is no base channel, since there is no channel switch. In the second case, once the switch is performed, there is no dependency on the base channel. It should be noted that in the second case, it is also possible to remove or disable the initial TDLS direct link (which operates on the base channel), as will be explained later.

[0020] As a result, the non-AP MLD does not need to switch back from the off-channel to the base channel to receive the beacon frame, which means that the non-AP MLD can permanently use the off-link (and the corresponding off-channel or channels) for TDLS transmission.

[0021] Furthermore, even if the first TDLS STA of a non-AP MLD is operating over an off-link, the non-AP MLD can, if necessary, communicate with the AP over other links that other of its affiliated STAs potentially establish with any affiliated APs thanks to the multilink capability. Thus, the non-AP MLD can receive beacons, check TIMs for buffered packets, and communicate with other devices in the network without having to perform repeated channel switches.

[0022] In other words, the proposed solution leverages the multi-link (multi-radio) capability of non-AP MLD to establish a persistent TDLS direct link on one or more off-channels while maintaining communication with the AP device through another link through an autonomous (i.e., base channel independent) off-link.

[0023] Optional features of the invention are defined below with reference to methods, but these may be replaced by apparatus features.

[0024] Advantageously, the method further comprises operating a communication with said AP device on another link corresponding to at least one of said channels used by said AP device.

[0025] As already mentioned above, the non-AP MLD can communicate with the AP via another link established by another of the affiliated STAs, if necessary, and therefore does not need to perform a channel switch to receive beacons, check TIMs for buffered packets, and communicate with other devices in the network.

[0026] In some implementations, obtaining the link ID includes obtaining information from the AP device that is an AP MLD about a virtual AP that belongs to the AP MLD, the virtual AP defining the off-link and associated with the link ID, and the virtual AP not communicating in the basic service set (BSS) of the virtual AP.

[0027] A "virtual AP" refers to an affiliated AP that does not actually operate (communicate). Such a virtual AP advantageously provides a link identifier of a link corresponding to an off-channel to a non-AP MLD.

[0028] In these implementations, a link ID is created by the AP MLD through the creation of a virtual AP, which is a new kind of AP that is not used for communication between non-AP STAs or MLDs and the AP MLD.

[0029] In some other implementations, establishing the TDLS direct link by the non-AP MLD includes defining the off-link and the link ID based on information about the at least one off-channel received from the AP device.

[0030] In these other implementations, the link ID is created by the non-AP MLD and other non-AP STAs or MLDs (no AP MLD is involved).

[0031] In some implementations, establishing the TDLS direct link includes setting up the TDLS direct link using the link ID to define the off-link as the TDLS direct link.

[0032] As mentioned above, in this first case, establishing a TDLS direct link using a new link ID is performed directly, i.e., using the link ID directly to define the off-link as a TDLS direct link (there is no channel switch in this case), with the corresponding advantages already mentioned above.

[0033] In some other implementations, establishing the TDLS direct link comprises: setting up an initial TDLS direct link that enables peer-to-peer communication between the first TDLS STA and the second TDLS STA; performing a channel switch to move the peer-to-peer communication from the initial TDLS direct link to a target link, the target link using a channel of the off-link as a target channel for the target link or using the link ID to define the off-link as the target link; Includes:

[0034] As mentioned above, in this second case, the establishment of a TDLS direct link using a new link ID is performed indirectly, i.e., by a two-step mechanism that includes the initial TDLS direct link setup and the subsequent execution of a channel switch, with the corresponding advantages already mentioned above.

[0035] In various embodiments, the method further includes disabling or deleting the initial TDLS direct link in the non-AP MLD.

[0036] Therefore, channels corresponding to deleted or disabled links can be reused, optimizing these network resources.

[0037] An embodiment of the present invention is a method of communication in a wireless network, comprising: in a non-AP multilink device (MLD) associated with an access point (AP), receiving, from the AP MLD, information about a virtual AP that belongs to the AP MLD, does not communicate in a basic service set (BSS) of the virtual AP, defines an off-link corresponding to at least one off-channel that does not overlap with a channel used by the AP MLD, and is assigned a link identifier (ID) that identifies the off-link; communicating over the wireless network using the link ID; The present invention provides a communication method including:

[0038] Thus, the non-AP MLD receives new types of information (information about the virtual AP, which is a new type of AP that is not used for communication between non-AP STAs or MLDs and AP MLDs), in particular, a specific link ID that enables it to communicate over the wireless network.

[0039] This configuration advantageously allows defining additional links to those operated by AP MLD, which may be used, for example, for direct communication within the wireless network.

[0040] The fact that a virtual AP does not communicate in its own BSS does not prevent the solution from being applied in a multi-AP context, i.e., using off-channel (and off-link) for multi-AP communication, in some embodiments.

[0041] In various embodiments, communicating over the wireless network using the link ID comprises: Establishing a Tunneled Direct Link Setup (TDLS) direct link between a first TDLS station (STA) and a second TDLS STA belonging to the non-AP MLD, using the link ID as the off-link indication for the TDLS direct link, through the channel used by the AP device; operating peer-to-peer communication between the first TDLS STA and the second TDLS STA via the off-link; Includes:

[0042] Therefore, the above mechanism based on receiving information about the virtual AP is compatible with the TDLS mechanism and allows the non-AP MLD to persistently use an off-link (and at least one corresponding off-channel) for TDLS transmission. In fact, even when a first TDLS STA of the non-AP MLD is operating over an off-link (corresponding to at least one off-channel), the non-AP MLD can communicate with the AP via another link established by another of its affiliated STAs, if necessary. Therefore, the non-AP MLD does not need to perform a channel switch to receive beacons, check TIMs for buffered packets, and communicate with other devices in the network.

[0043] In various embodiments, establishing the TDLS direct link comprises: including a link identifier in a TDLS setup frame exchanged between the first TDLS STA and the second TDLS STA, the link identifier including a Basic Service Set Identifier (BSSID) field set with a BSSID corresponding to the virtual AP and thus the off-link; adding the off-link to a per STA profile sub-element carried in a TDLS Multi-Link element exchanged between the first TDLS STA and the second TDLS STA; Including a Multi-Link Information element including a Link ID bitmap indicating the off-link in a TDLS setup frame exchanged between the first TDLS STA and the second TDLS STA; It includes at least one of the following:

[0044] Each of these operations advantageously limits overhead while reusing and / or slightly modifying existing elements and / or frames.

[0045] Also, an embodiment of the present invention is a method of communication in a wireless network, comprising: in an access point (AP) multilink device: instantiating an affiliated virtual AP that defines an off-link corresponding to at least one off-channel that does not overlap with a channel used by the AP MLD, the affiliated virtual AP being assigned a link identifier (ID) to identify the off-link, the affiliated virtual AP not performing communication in a basic service set (BSS) of the affiliated virtual AP; transmitting information about the affiliated virtual AP defining the off-link including the link ID to the non-AP MLD; A communication method including the above is provided.

[0046] The advantages of using virtual APs to define off-link have already been discussed above.

[0047] In various embodiments, the method further includes receiving a trigger for the instantiation of the affiliated virtual AP, the trigger comprising: receiving a Probe Request frame from the non-AP MLD, the Probe Request frame including off-link capabilities as a new entry in Extended Capabilities and / or in a Channel Usage element if the non-AP MLD is not already associated with the AP MLD; receiving a Channel Usage Request frame from the non-AP MLD, the Channel Usage Request frame including a Channel Usage element requesting setup of the off-link if the non-AP MLD is not already associated with the AP MLD; receiving a quality of service (QoS) characteristic; Detecting a trigger within the AP MLD; It belongs to a group that has

[0048] In some implementations, the information about the affiliated virtual AP includes, in addition to the link ID: Operation class, Channel number, A channel width that defines the operating frequency band; BSSID, Information about a BSSID that indicates that the virtual AP is not reachable (e.g., an AP Reachability field from the BSSID Information element as defined in IEEE P802.11-REVme / D1.3), and Non-Inheritance elements, Contains one or more parameters that belong to a group containing

[0049] In some embodiments, the virtual AP can be distinguished from APs with which it can communicate using a particular value of the AP Reachability field from the BSSID Information element (e.g., as defined in IEEE P802.11-REVme / D1.3).

[0050] This advantageously limits overhead while reusing the existing AP Reachability field.

[0051] In various embodiments, the information about the affiliated virtual APs is exchanged at least in part as part of a Multi-link element in a Probe Response frame, a Beacon frame, or an Association Response frame; The Affiliated Virtual AP is declared as an additional STA in a Multi-link element with a separate per STA profile sub-element containing information to distinguish the Affiliated Virtual AP from other Affiliated APs in the AP MLD, or The Common Info field of the Multi-link element includes an off-link Bitmap or Virtual AP Bitmap subfield.

[0052] Each of these configurations advantageously limits overhead while reusing and / or slightly modifying existing elements and / or frames.

[0053] In various embodiments, the per STA profile sub-element, individual to the affiliated virtual AP, comprises: a Non-Inheritance element conveying AP capabilities and / or behaviors that cannot be used in the context of the virtual AP that do not communicate in a basic service set (BSS) of the virtual AP and that should not be inherited by the virtual AP from a reporting STA; It is not subject to inheritance.

[0054] This avoids unnecessary inheritance.

[0055] In various embodiments, the information about the affiliated virtual AP is exchanged at least in part as part of a Neighbor Report element or a Reduced Neighbor Report element included in a beacon frame, the part being an off-link field or a Usage Mode field included in an MLD Parameters subfield, providing information about the link corresponding to the contents of a Link ID field included in the MLD Parameters subfield.

[0056] Each of these configurations advantageously limits overhead while reusing and / or slightly modifying existing elements and / or frames.

[0057] In various embodiments, the information about the affiliated virtual AP includes information about at least one of the off-channels of the AP MLD exchanged as a Channel Usage element; The Channel Usage element a Link ID Information field containing said Link ID and associated with every Channel entry in the Channel Entry field; or a Link ID Information subfield of the Channel Entry field containing the link ID and associated with every Channel entry of the Channel Entry field; Including, The Channel Usage element is included in a Probe Response frame or a Channel Usage Response frame.

[0058] Each of these configurations advantageously limits overhead while reusing and / or slightly modifying existing elements and / or frames.

[0059] In some embodiments, obtaining the link ID includes the non-AP MLD creating a TDLS link using a unique link ID that defines the off-link corresponding to at least one off-channel that does not overlap with the channel used by the AP. This implementation advantageously takes advantage of the MLD capabilities of non-AP MLDs that engage in peer-to-peer communication with connections with legacy APs, i.e., APs that do not support multi-link functionality.

[0060] In some specific embodiments, creating the TDLS link includes triggering the creation of an identical TDLS link in the other non-AP MLD. This means that two non-AP MLDs that want to directly exchange simultaneously create the same off-link for this purpose. This configuration therefore facilitates the immediate and temporary creation of an off-link for a temporary direct link session.

[0061] In some embodiments, creating the TDLS link includes establishing a TDLS direct link with the second TDLS STA that targets the created off-link. In other words, establishing the TDLS direct link includes setting up the TDLS direct link using the link ID to define the off-link as the TDLS direct link.

[0062] This means that once the off-link is created (on both sides) independently of the link setup with the AP device, two non-AP MLDs can set up a TDLS direct link on the off-link using the conventional TDLS direct link mechanism. This configuration fully integrates the standardized mechanism.

[0063] In some embodiments, a TDLS setup frame exchanged during the establishment of the TDLS direct link includes a MAC address of the first TDLS STA for identifying the off-link to be created.

[0064] As mentioned above, in this first case, establishing a TDLS direct link with a new link ID is performed directly, i.e., directly using the link ID to define the off-link as a TDLS direct link.

[0065] In some embodiments, creating the TDLS link includes exchanging TDLS action frames with the other non-AP MLD tunneled by the AP device to create the off-link in both of the non-AP MLDs in parallel, thereby allowing the non-AP MLDs to exchange signaling frames (here, TDLS action frames) for the purpose of creating and establishing off-links for direct communication with each other using any links they have set up (and enabled) with the AP device.

[0066] In certain embodiments, exchanging TDLS action frames includes, for the non-AP MLD: transmitting a link setup request to create an off-link corresponding to at least one candidate off-channel that does not overlap with the channel used by the AP device; and In response thereto, receiving a link setup response including an alternative off-link corresponding to at least one alternative off-channel that does not overlap with the channel used by the AP device; Includes:

[0067] Therefore, non-AP MLD can be negotiated off-link.

[0068] In some embodiments, the method further includes, in a first link setup with the AP device, establishing a first TDLS direct link between the two non-AP MLDs for a first session, and switching the first TDLS session to the off-link.

[0069] In some embodiments, switching the first TDLS session to the off-link includes performing TDLS Link switching to move the first TDLS session to the off-link, which was created in the previous step. This two-step approach advantageously involves only a link ID to perform the switch, which can be reused later. A separate (dedicated) TDLS action frame can be used for switching.

[0070] In a specific embodiment, performing the TDLS Link switching includes directly exchanging TDLS action frames via the first TDLS link. This configuration takes advantage of the already established TDLS direct link to efficiently (quickly) transition off-link, typically with a view to releasing the already established TDLS direct link (on the first link) when switching occurs. This is intended to reduce access contention on the first link.

[0071] In some embodiments, switching the first TDLS session to the off-link comprises performing TDLS Channel switching targeting one or more off-channels of the off-link in order to move the first TDLS session to the off-link. This configuration advantageously relies on conventional (standardized) TDLS direct link mechanisms (so-called "TDLS channel switching" in section 11.20.6 of REVme2.0) and allows disabling a TDLS direct link in the first link and simultaneously enabling (or setting up) a TDLS direct link in the off-link in the sense of the present invention.

[0072] In some embodiments, the method further includes deleting or disabling the setup of the first link with the AP device. This advantageously does not delete or disable the TDLS direct link on the off-link because the TDLS direct link on the off-link was created independently of the first link. This configuration eliminates the need for non-AP MLD affiliated STAs to continue activity with the corresponding AP (e.g., switching back to the AP's channel, etc.).

[0073] Thus, channels corresponding to deleted or disabled links can be reused, optimizing these network resources.

[0074] According to an alternative embodiment, removing or disabling the first link comprises: updating a TID-To-Link mapping of the link setup with the AP device to remove all TIDs assigned to the first link; performing a multilink setup with the AP device excluding the first link; It may include any of the following:

[0075] In some embodiments, the link ID defining the off-link is selected from a set of candidate link IDs excluding the link ID used by the AP device. For example, it may be selected from more than 15 values. This configuration ensures that conflicts between link IDs are avoided in non-AP MLD.

[0076] In some embodiments, the method further includes, in response to creating the off-link, notifying the AP device of the created off-link. One or more off-channels, and possibly a link ID, may be notified, allowing the AP to coordinate management of the BSS, for example, by avoiding use of off-channels that conflict with the created off-link.

[0077] In some embodiments, the off-link is assigned a BSSID (Basic Service Set Identifier) set to the MAC address of one of the TDLS STAs or one of the two non-AP MLDs. This means that the first TDLS STA and the second TDLS STA operate in separate BSSs (identified by BSSIDs) separate from the AP device, while other affiliated stations of the non-AP MLDs can operate in a BSS managed by the AP device. This configuration advantageously allows the definition of an ad-hoc BSS without modifying existing information elements, specifically the Link Identifier IE.

[0078] In some embodiments, obtaining the link identifier includes obtaining a recommended channel from the AP device that is not an infrastructure BSS or an off-channel TDLS direct link, and selecting one or more of the off-channels from the recommended channel.

[0079] In some embodiments, the TDLS action frame includes a multi-link element having one or more per-STA profiles for respectively signaling one or more off-channels for the off-link.

[0080] This configuration allows a TDLS STA to define an off-link for multiple channels using existing IEs, in which case all off-channels can be used to define the created off-link.

[0081] On the other hand, this configuration may alternatively allow a TDLS STA (e.g., a first TDLS station) to define multiple candidate channels for creating an offlink, in which case a responding TDLS STA may select one of the candidate channels defined in the per-STA profile (e.g., a channel that best suits the responding station's capabilities) to form / create an offlink.

[0082] Relatedly, embodiments of the present invention also provide a wireless communication device including at least one microprocessor configured to perform any of the methods as described above.

[0083] Another aspect of the present invention is a Tunneled Direct Link Setup (TDLS) action frame exchanged between an access point (AP) device and two associated non-AP multi-link devices (MLDs), the action frame comprising: an Action field set to a value strictly greater than 10 to indicate a request to create a TDLS link, using a unique link ID to define an off-link corresponding to at least one off-channel that does not overlap with channels used by the AP device; and at least one information element (IE) defining said link ID and including said at least one off-channel; Regarding TDLS action frames containing

[0084] Yet another aspect of the present invention is a Tunneled Direct Link Setup (TDLS) action frame exchanged between an access point (AP) device and two associated non-AP multi-link devices (MLDs), the action frame comprising: an Action field set to a value strictly greater than 10 to indicate a request to move a current TDLS session on a first link having a first link ID to a second link having a different second link ID; an information element (IE) field indicating the second link ID; Regarding TDLS action frames containing

[0085] In practice, such frames may be tunneled by AP devices to other non-AP MLDs.

[0086] In particular, the second link ID may identify an off-link defined in at least one off-channel that does not overlap with the channel used by the AP device.

[0087] The at least one IE may also include a BSSID field associated with the second link, the BSSID field being set to a MAC address of one of the non-AP MLDs or a station belonging to one of the non-AP MLDs.

[0088] Another aspect of the present invention relates to a non-transitory computer-readable medium having stored thereon a program which, when executed by a microprocessor or computer system within a wireless device, causes the wireless device to perform any of the above-described methods.

[0089] At least part of the methods according to the present invention may be computer-implemented. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all of which may be referred to generally 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.

[0090] Because the present invention can be implemented in software, it may be embodied as computer-readable code for provision to a programmable device on any suitable carrier medium. Tangible, non-transitory carrier media may include storage media such as floppy disks, CD-ROMs, hard disk drives, magnetic tape devices, or solid-state memory devices. Transient carrier media may include signals such as electrical, electronic, optical, acoustic, magnetic, or electromagnetic signals, e.g., microwave or RF signals.

[0091] The names of the information elements (IEs) provided in this document are intended to reflect those currently used in the 802.11 standard for the sake of readability. Of course, other names that convey the same information may be used instead. [Brief explanation of the drawings]

[0092] Embodiments of the invention will now be described, by way of example only, with reference to the following drawings, in which: [Figure 1] Figure 1 shows a typical 802.11 network environment including ML transmission between MLDs over which a single-link Tunneled Direct Link Setup (TDLS) direct link is established. [Figure 1ab] 1a and 1b show an exemplary 802.11be multilink reference model for MLD, either AP MLD or non-AP MLD. [Figure 2] FIG. 2 illustrates possible scenarios for the discovery and association process between non-AP MLD and AP MLD using timeline frame exchanges. [Figure 2a] Figure 2a illustrates a possible scenario for an initiator's peer non-AP STA to process P2P traffic using a timeline frame exchange. [Figure 3] FIG. 3 shows the format of an 802.11 action frame according to the 802.11 standard. [Figure 4a] Figure 4a shows the so-called "Link Identifier" IE according to the 802.11 standard. [Figure 4b] Figure 4b shows the so-called "TDLS Multi-Link" IE according to the 802.11 standard. [Figure 4c] Figure 4c shows the so-called "Multi-Link Link" IE according to the 802.11 standard. [Figure 5a1] Figure 5a1 shows the so-called "Basic variant Multi-Link" IE according to the 802.11 standard. [Figure 5a2] Figure 5a2 shows the so-called "Per-STA Profile" sub-element according to the 802.11 standard. [Figure 5b] FIG. 5b illustrates the "Per-STA Profile" sub-element modified according to an embodiment of the present invention. [Figure 6] Figure 6 shows the so-called "Channel Usage" IE according to the 802.11 standard. [Figure 6a] FIG. 6a shows the "Channel Usage" IE modified according to an embodiment of the present invention. [Figure 6b] FIG. 6b shows the "Channel Usage" IE modified according to another embodiment of the present invention. [Figure 6c] FIG. 6c shows a Channel Usage Request frame. [Figure 7a] FIG. 7a illustrates an 802.11 network environment including a multi-radio device MLD such as that of FIG. 1 in which embodiments of the present invention may be implemented. [Figure 7b] FIG. 7b illustrates another 802.11 network environment including a multi-radio device MLD such as that of FIG. 1 in which embodiments of the present invention may be implemented. [Figure 7c]FIG. 7c illustrates an example of wireless communication operations performed by AP MLD for virtual AP instantiation in accordance with certain aspects of the present invention. [Figure 7d] FIG. 7d illustrates an example of wireless communication operation performed by non-AP MLD for TDLS setup off-link according to certain aspects of the present invention. [Figure 8] Figure 8 illustrates the scenarios of Figures 2 and 2a with a timeline frame exchange when the AP MLD notifies the non-AP MLD, which is the TDLS initiator, that an off-link is available to handle P2P traffic. [Figure 8b] Figure 8b illustrates the scenarios of Figures 2 and 2a with frame exchanges in a timeline when a non-AP MLD already associated with an AP MLD requests the creation of an off-link for P2P traffic through a Channel Usage Request frame. [Figure 8c] Figure 8c illustrates the scenarios of Figures 2 and 2a using timeline frame exchanges when a non-AP MLD already associated with an AP MLD performs TDLS setup on a link shared with the AP and moves off-link using a TDLS channel switch. [Figure 9] FIG. 9 shows the format of the reduced Neighbor Report (RNR) information element present in all beacons. [Figure 9a] FIG. 9a illustrates the TBTT Information field (contained in the RNR information element) including the MLD Parameters field modified (by including the new Off-link field) according to a specific embodiment of the present invention. [Figure 9b] FIG. 9b shows the TBTT Information field (contained in the RNR information element) including the MLD Parameters field modified (by including the new Usage Mode field) according to another specific embodiment of the present invention. [Figure 10a] FIG. 10a is a schematic diagram of a communication device in accordance with at least one embodiment of the present invention. [Figure 10b] FIG. 10b shows a schematic architecture of the communication device of FIG. 10a. [Figure 11a] FIG. 11a illustrates an 802.11 network environment including a non-AP multi-radio device MLD associated with an AP device in which embodiments of the present invention may be implemented. [Figure 11b] FIG. 11b illustrates, by way of a flow chart, exemplary steps for direct communication according to certain aspects of the present invention. [Figure 11c] FIG. 11c illustrates, with frame exchanges on a timeline, the creation and use of an off-link according to an embodiment of the present invention, where Channel Usage information is obtained from a Probe Response frame. [Figure 11d] FIG. 11d illustrates, with frame exchanges in a timeline, the creation and use of an off-link according to another embodiment of the present invention, in which Channel Usage information is obtained from a Channel Usage Response frame. [Figure 12a] FIG. 12a illustrates another 802.11 network environment including a multi-radio device MLD such as that of FIG. 1 in which the present invention may be implemented. [Figure 12b] FIG. 12b illustrates, by way of a flow chart, exemplary steps of direct linking according to certain aspects of the present invention. [Figure 12c] FIG. 12c illustrates, with a timeline frame exchange, one of two different scenarios for off-link creation and use according to an embodiment of the present invention. [Figure 12d] FIG. 12d illustrates, with a timeline frame exchange, one of two different scenarios for off-link creation and usage according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0093] The techniques described herein may be used for various broadband wireless communication systems, including communication systems based on orthogonal multiplexing. Examples of such communication systems include spatial division multiple access (SDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems. SDMA systems may utilize sufficiently different directions to transmit data belonging to multiple user terminals, i.e., wireless devices or STAs, in parallel. TDMA systems may allow multiple user terminals to share the same frequency channel by dividing the transmission signal into different time slots or resource units and assigning each time slot to a different user terminal. OFDMA systems utilize orthogonal frequency division multiplexing (OFDM), a modulation technique that divides the overall system bandwidth into multiple orthogonal subcarriers or resource units. These subcarriers may also be referred to as tones, bins, etc. In OFDM, each subcarrier may be independently modulated with data. An SC-FDMA system may utilize Interleaved FDMA (IFDMA), which transmits on subcarriers distributed across the system bandwidth, Localized FDMA (LFDMA), which transmits on blocks of adjacent subcarriers, or Enhanced FDMA (EFDMA), which transmits on multiple blocks of adjacent subcarriers.

[0094] The teachings herein may be incorporated into (e.g., implemented within or performed by) a variety of devices (e.g., STAs). In some aspects, a wireless device or STA implemented in accordance with the teachings herein may or may not constitute an access point (a so-called AP) (a so-called non-AP STA or STA).

[0095] Although the present example is described in the context of a Wi-Fi network, the invention can be used in any type of wireless network, such as, for example, a mobile telephone cellular network, which implements very similar mechanisms.

[0096] An AP may include, be implemented as, or be known as a Node B, Radio Network Controller ("RNC"), Evolved Node B ("eNB"), 5G Next Generation Base Station ("gNB"), Base Station Controller ("BSC"), Base Transceiver Station ("BTS"), Base Station ("BS"), Transceiver Function ("TF"), wireless router, wireless transceiver, Basic Service Set ("BSS"), Enhanced Service Set ("ESS"), Radio Base Station ("RBS"), or other terminology.

[0097] A non-AP STA may include, be implemented as, or be known as a subscriber STA, subscriber unit, mobile STA (MS), remote STA, remote terminal, user terminal (UT), user agent, user device, user equipment (UE), user STA, or other terminology. In some implementations, a STA may include a mobile phone, a cordless phone, a session initiation protocol ("SIP") phone, a wireless local loop ("WLL") STA, a personal digital assistant ("PDA"), a handheld device with wireless connectivity capabilities, 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 mobile phone or smartphone), 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 satellite radio), a global positioning system (GPS) device, or any other suitable device configured to communicate via a wireless or wired medium. In some aspects, a non-AP STA may be a wireless node. Such a wireless node may, for example, provide connectivity to 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.

[0098] An AP manages a set of STAs (registered or associated with the AP) that organize access to the wireless medium for communication purposes. The STAs (including the APs they register with) form a service set, hereafter called a Basic Service Set (BSS), although other terms can also be used. The same physical STA acting as an access point may manage two or more BSSs (and thus corresponding WLANs), each BSS being therefore uniquely identified by a specific Basic Service Set Identification (BSSID) and managed by a separate virtual AP implemented in the physical AP. Each STA is identified within a BSS by an identifier (AID) assigned by the AP upon registration.

[0099] The 802.11 family of standards defines a variety of medium access control (MAC) mechanisms for driving access to the wireless medium.

[0100] Current discussions in the 802.11be task group, as described in the October 2022 draft IEEE P802.11be / D2.2, introduce multilink operation (MLO) for MAC layer operation. MLO allows a multilink device to establish or set up multiple links and operate them simultaneously. These links are called "setup links" or "setup communication links."

[0101] A multilink device (MLD) is a logical entity that has multiple affiliated STAs (STAs) and a single medium access control (MAC) service access point (SAP) for a logical link control (LLC) containing one MAC data service. An access point multilink device (or AP MLD) corresponds to an MLD in which each STA belonging to the MLD is an AP and is therefore referred to as an "affiliated AP." A non-access point multilink device (or non-AP MLD) corresponds to an MLD in which each STA belonging to the MLD is a non-AP STA and is therefore referred to as an "affiliated non-AP STA." In some literature, the terms "multilink device," "ML device" (MLD), "multilink logical entity," "ML logical entity" (MLE), "multilink set," and "ML set" are synonyms that designate the same type of ML device. An exemplary architecture of a multilink device is described below with reference to Figures 1a and 1b.

[0102] Multiple affiliated non-AP STAs in a non-AP MLD can set up communication links with multiple affiliated APs in an AP MLD, thus forming a multi-link channel.

[0103] The communication links (or "enabled links") set up for MLD are theoretically independent, meaning that channel access procedures (to the communication medium) and communication are performed independently on each link. Thus, different set up communication links may have different data rates (e.g., due to different bandwidths, number of antennas, etc.) and may be used to communicate different types of information (over each particular link).

[0104] Thus, the setup communication link or activation link or simply "link" corresponds to a predetermined channel (e.g., 20 MHz, 40 MHz, etc.) in a predetermined frequency band (e.g., 2.4 GHz, 5 GHz, 6 GHz) between an AP belonging to an AP MLD and a non-AP STA belonging to a non-AP MLD.

[0105] Affiliated APs and affiliated non-AP STAs operate on their respective channels in accordance with one or more of the IEEE 802.11 standards (a / b / g / n / ac / ad / af / ah / aj / ay / ax / be) or other wireless communication standards.

[0106] With multi-link aggregation, traffic associated with one MLD can theoretically be transmitted across multiple parallel communication links, thereby increasing network capacity and making the best use of available resources.

[0107] From an architectural perspective, an MLD typically includes several radios to implement the affiliated STAs, but the number does not have to be equal to the number of affiliated STAs. In particular, a non-AP MLD may operate with a number of affiliated STAs greater than the number of radios (or even as few as one).

[0108] Figure 1 shows a typical 802.11 network environment including ML transmission between MLDs, which can establish a single-link Tunneled Direct Link Setup (TDLS) direct link according to the D2.2 standard.

[0109] The wireless communication network 100 includes an AP MLD 110 and two non-AP MLDs 120 and 130. Of course, other numbers of non-AP MLDs that register with the AP MLD 110 and exchange frames with the AP MLD 110 may be contemplated.

[0110] One of the two non-AP MLDs may be a legacy 802.11 station, in which case the term "affiliated non-AP STA" below simply refers to the legacy station itself.

[0111] The AP MLD 110 has multiple affiliated APs, two affiliated APs 111 and 112 (also referred to as AP1 and AP2, respectively) in the exemplary FIG. 1 , each operating as an 802.11 AP on an operating channel within a frequency band. Known 802.11 frequency bands include the 2.4 GHz band, the 5 GHz band, and the 6 GHz band. Of course, other frequency bands may be used instead of or in addition to these three frequency bands.

[0112] The non-AP MLDs 120, 130 have multiple affiliated non-AP STAs, each operating as an 802.11 non-AP STA in the BSS (managed by the affiliated AP 111 or 112) to which it registers. In the exemplary Figure 1, two non-AP STAs 121 and 122 (also referred to as A1 and A2, respectively) belong to the non-AP MLD 120, and two non-AP STAs 131 and 132 (also referred to as B1 and B2, respectively) belong to the non-AP MLD 130.

[0113] For example, AP 111 may be configured to operate on channel 38, which corresponds to an operating 40 MHz channel in the 5 GHz frequency band, and AP 112 may be configured to operate on channel 151, which corresponds to another operating 40 MHz channel, also in the 5 GHz frequency band. In another example, affiliated STAs may operate on different frequency bands.

[0114] Each affiliated AP provides a link to the AP MLD 110 for affiliated non-AP STAs in the non-AP MLD (120 or 130). Therefore, each non-AP MLD link can be identified simply by the identifier of the respective affiliated AP. In this context, each affiliated AP 111 and 112 can be identified by an identifier called a "link ID." The link ID of each affiliated AP is unique and does not change during the lifetime of the AP MLD. The AP MLD may assign link IDs to affiliated APs by incrementing the ID from 0 (for the first affiliated AP). Of course, in variants, other terms, such as "AP ID," may be used.

[0115] To perform multi-link communications, each non-AP MLD 120, 130 must discover, authenticate, associate, and set up multiple links with the AP MLD 110, with each link established between an affiliated AP of the AP MLD 110 and an affiliated non-AP STA of the non-AP MLD. Each such setup communication link, called an "enabling link," enables separate channel access and frame exchange between the non-AP MLD and the AP MLD based on the supported capabilities exchanged during association.

[0116] Figure 2 shows possible scenarios in the discovery and association process between non-AP MLD and AP MLD using a timeline of frame exchanges.

[0117] This example includes STA A1 121 belonging to the non-AP MLD 120 and AP1 111 belonging to the AP MLD 110.

[0118] The discovery phase is called the ML discovery procedure, and the multilink setup phase (or association phase) is called the ML setup procedure. Management frames exchanged during the ML discovery and setup procedures contain a new information element specific to multilink operation (MLO) called the Basic Multi-Link element, which carries a description of the affiliated STA entity of the MLD that is sending the frame, in addition to the sending affiliated STA entity (known as the "reporting STA"). More precisely, the profile of the reporting STA (i.e., the STA that is sending the frame) is provided in an information element (IE) of the frame other than the Basic Multi-Link element. The Basic Multi-Link element then carries one or more Per STA profile sub-elements corresponding to each of the additional affiliated STAs (known as the "reportee STAs").

[0119] The ML discovery procedure enables a non-AP MLD to discover various links to the wireless communication network 100, i.e., the AP MLDs provided by multiple affiliated APs. Thus, the ML discovery procedure attempts to advertise the various affiliated APs in the AP MLD along with their respective network information, including, for example, all or part of their capabilities and operating parameters. The discovery process primarily relies on the exchange of probe requests and probe responses between APs and non-APs. In the case of ML discovery, discovery is performed either by using a probe request / response frame exchange for each link or by using a single ML probe request / response frame exchange that carries all information of the various APs belonging to the AP MLD on one of the available links. Furthermore, discovery may be based on active scanning or passive scanning. In active scanning, a non-AP STA sends a probe request 212 (using a wildcard SSID) and waits for a probe response 213 from the AP. In passive scanning, a non-AP STA listens on each channel for beacons 211 transmitted periodically by APs on its operating channel, and then transmits probe requests 212 using the SSIDs corresponding to the APs of interest.

[0120] When sent by a non-AP MLD through STA A1 121, e.g., for non-AP MLD 120, the probe request frame 212 allows an affiliated non-AP station to request that the affiliated AP (to AP 111) include, in addition to its network information, a complete or partial set of capabilities and operational elements (i.e., network information) of other APs belonging to the same AP MLD.

[0121] When transmitted through AP1 111, for example by the AP MLD of AP MLD 110, a beacon frame 211 or probe response frame 213 includes both a Reduced Neighbor Report element (further described in FIG. 9) containing channel and other information related to neighboring APs, and a Basic Multi-Link element containing one or more Per STA Profile sub-elements that describe all the information of the APs belonging to the AP MLD. The Multi-Link element in its basic variant will be described below with reference to FIGS. 5a1 and 5a2.

[0122] Among the various capabilities exchanged by the AP and non-AP during the discovery procedure, Channel Usage information may be provided by the AP to the non-AP STA in the probe response frame 213 to advise the STA how to coexist with the infrastructure network, and more particularly, to recommend a channel for a BSS that is not an infrastructure BSS or an off-channel TDLS direct link. Thus, the non-AP STA can use the channel usage information as part of the channel selection process for a BSS that is not an infrastructure BSS or an off-channel TDLS direct link.

[0123] This Channel Usage information is a set of channels that the AP provides to non-AP STAs for operation in a non-infrastructure network or an off-channel TDLS direct link. A non-AP STA that supports Channel Usage and is interested in using a non-infrastructure network or an off-channel TDLS direct link may include both a Supported Operating Classes element (as defined in IEEE 802.11-REVme / D1.3 (June 2022), 9.4.2.53 Supported Operating Classes element) and a Channel Usage element (as defined in IEEE 802.11-REVme / D2.0 (October 2022), 9.4.2.85 Channel Usage element) in a probe request frame 212. An AP that supports Channel Usage must then transmit a probe response frame 213 that includes one or more Channel Usage elements. The Channel Usage element is further described with reference to FIG. 6. It may also be noted that a non-AP STA that supports Channel Usage may send a Channel Usage Request frame at any time after association to an AP that supports the use of Channel Usage to request Channel Usage information for supported operation classes, i.e., to request a channel for non-infrastructure network operation or off-channel TDLS direct link operation.

[0124] A non-AP MLD discovers the wireless communication network 100 through an ML discovery procedure, and after an MLD authentication procedure, an ML setup procedure (based on Association Request 214 and Association Response 215 frames) enables it to select a set of candidate setup links between its affiliated non-AP STAs and some of the discovered affiliated APs and request the AP MLD 110 to set up these links, which the AP MLD may accept or reject. If the AP MLD accepts, the AP MLD provides the non-AP MLD with an association identifier (AID), which is used by the non-AP MLD's affiliated non-APs to wirelessly communicate with the corresponding affiliated APs over multiple links (communication channels).

[0125] During the MLD setup procedure, a non-AP MLD declares some or all of its capabilities. For example, it may declare Tunneled Direct Link Setup (TDLS) capabilities, which enable devices (called TDLS peer STAs) to communicate directly with each other when connected to a traditional AP. For this purpose, an appropriate field is provided in the management frame. In virtually all management frames, a non-AP MLD that can act as a TDLS initiator STA or a TDLS responder STA (dot11TunneledDirectLinkSetupImplemented is true) sets the TDLS Support bit (bit 37) in the Extended Capabilities element to 1.

[0126] Similar to TDLS support, a non-AP MLD or AP MLD may declare whether Channel Usage is enabled (dot11ChannelUsageActivated is true) by setting the Channel Usage bit (bit 24) of the Extended Capabilities element to 1, allowing devices to exchange Channel Usage Information.

[0127] For illustrative purposes, in wireless communication network 100, during an ML setup procedure, two candidate setup links are requested by non-AP MLD 120 and accepted by AP MLD 110: a first link 151 between affiliated AP 111 (AP1) and affiliated non-AP STA 121 (A1) and a second link 152 between affiliated AP 112 (AP2) and affiliated non-AP STA 122 (A2). Similarly, two candidate setup links are requested by multi-radio non-AP MLD 130 and accepted by AP MLD 110: a first link 161 between affiliated AP 111 (AP1) and affiliated non-AP STA 131 (B1) and a second link 162 between affiliated AP 112 (AP2) and affiliated non-AP STA 132 (B2).

[0128] 6, the data payload of a Channel Usage element is shown under reference numeral 600. The Channel Usage element consists of four fields: an Element ID field 610, a Length field 620, a Usage Mode field 630, and a Channel Entry field 640.

[0129] Two different values are defined for the Usage Mode field 630 in IEEE P802.11-REVme / D2.0 version (October 2022): 0 for non-infrastructure IEEE 802.11 networks and 1 for off-channel TDLS direct links. A recent adaptation of the standard is providing a new value, 2, for non-infrastructure IEEE 802.11 networks where none of the APs belonging to the same ESS operate an infrastructure BSS. Values 3 to 255 are reserved.

[0130] The Channel Entry field 640 contains zero or more Operating Class 641 and Channel 642 fields. The Operating Class field 641 indicates an operating class value. The operating class (which defines the radio frequency, channel center frequency, maximum channel width, and operating constraints) is interpreted in the context of the country specified in the Beacon frame. The Channel field 642 indicates a channel number, which is interpreted in the context of the indicated operating class. The operating class and channel numbers are defined in Annex E of IEEE P802.11-REVme / D1.3 version. As described in 9.4.2.70.3 (Location Indication Channels subelement), the Operating Class and Channel fields can be grouped together to identify non-contiguous channels.

[0131] FIG. 9 illustrates the format of the Reduced Neighbor Report (RNR) information element 910 that is present in every beacon.

[0132] The Element ID field 911 is equal to the value 101, indicating that the type of the information element is RNR.

[0133] The Length field 912 indicates the length in octets of the containing information element.

[0134] The Neighbor AP information Fields field 913 includes a set of one or more (n in the example of FIG. 9) Neighbor AP Information fields 920, each providing elements related to a reported AP that is different from the reporting AP (the AP sending the information element). For example, in the example of FIG. 2, the beacon 211 includes at least one Neighbor AP information field 920 corresponding to AP2 (as the reported AP). Additionally, several other fields 920 may be present to provide information from APs that are not part of the reporting AP MLD but are known to the reporting AP (such as APs co-located in the same housing but operating different MLDs).

[0135] Each Neighbor AP information field 920 includes a TBTT information header subfield 921 , an Operating class subfield 922 , a Channel Number subfield 923 , and a TBTT information Set subfield 924 .

[0136] The TBTT information header subfield 921 includes several fields that indicate how many TBTT information fields 930 exist in the TBTT information Set subfield 924 (TBTT Information Count) and their types (TBTT information Field Type).

[0137] Each TBTT information field 930 includes a Neighbor AP TBTT Offset subfield 931 and an MLD Parameters subfield 940 .

[0138] The Neighbor AP TBTT Offset subfield 931 indicates the offset, in TUs, from the previous TBTT of the AP transmitting this element to the next TBTT of the AP's BSS, rounded down to the nearest TU. A value of 254 indicates an offset of 254 TUs or greater. A value of 255 indicates an unknown offset value.

[0139] The MLD Parameters field 940 contains information related to the link associated with the reported AP. More precisely, the MLD Parameters field 940 includes an MLD ID subfield 941, a Link ID subfield 942, and a BSS Parameters Change Count subfield 943.

[0140] The MLD ID subfield 941 indicates the identifier of the AP MLD to which the reported AP belongs. If the reported AP belongs to the same MLD as the reporting AP, the MLD ID subfield 941 is set to 0. If the reported AP is part of another AP MLD, the MLD ID subfield is set to a value greater than 0. For example, if the reported AP belongs to the same MLD as a non-transmitting BSSID that is included in the same multiple BSSID set as the reporting AP, the MLD ID subfield 941 is set to the same value as the BSSID Index field of the Multiple BSSID-Index element in the non-transmitting BSSID profile that corresponds to the non-transmitting BSSID.

[0141] The Link ID subfield 942 is a unique identifier (within the MLD) of the link.

[0142] The BSS Parameters Change Count subfield 943 contains a counter that is incremented (modulo 255) each time a critical parameter of the BSS is updated in the reporting AP's beacon frame.

[0143] 5a1 and 5a2 show the format of the Basic variant Multi-Link element 500. The Basic variant Multi-Link element 500 includes an Element ID field 501, a Length field 502 (which indicates the presence or absence of optional fields, as well as the number of Per-STA profiles in field 530), an Element ID Extension field 503, a Multi-Link Control field 510, a Common Info field 520, and an optional Link Info field 529.

[0144] The Multi-Link Control field 510 includes a Type subfield 511, a Reserved subfield 512, and a Presence Bitmap subfield 513. The Type subfield 511 is set to a value of 0 to indicate that the Multi-Link element 300 is a Basic variant ML element. The Presence Bitmap subfield 513 indicates which parameters are present or absent in the Common Info field 520. It includes a Link ID Info Present subfield, a BSS Parameters Change Count Present subfield, a Medium Synchronization Delay Information Present subfield, an EML Capabilities Present subfield, an MLD Capabilities and Operations Present subfield, an MLD ID Present subfield, and a Reserved subfield.

[0145] The Common Info field 520 always includes a Common Info Length field 521, an MLD MAC Address subfield 522, and, depending on the value specified in the Presence Bitmap subfield 320, the Common Info field 520 optionally includes a Link ID Info subfield 523, a BSS Parameters Change Count subfield 524, a Medium Synchronization Delay Information subfield 525, an EML Capabilities subfield 526, an MLD Capabilities and Operations subfield 527, and an MLD ID subfield 528.

[0146] More precisely, the Link ID Info subfield 523 includes a Link ID subfield 523a and a Reserved field 523b. The Link ID subfield 523a conveys the link ID on which the reporting affiliated (AP or non-AP) STA operates.

[0147] If the Link Info field 529 is present, it contains one or more Per-STA Profile sub-elements 530 as a list of sub-elements 530, each describing one reporting affiliated (AP or non-AP) STA of the same MLD.

[0148] As detailed in FIG. 5a2, the Per-STA Profile subelement 530 includes a Subelement ID field 531, a Length field 532, a STA Control field 533, a STA Info field 534, and a STA Profile field 535.

[0149] The STA Control field 533 includes a Link ID subfield 540 that specifies a value that uniquely identifies the link on which the reporting STA is operating.

[0150] The STA Control field 533 further includes a Complete Profile subfield 541, a STA MAC Address Present subfield 542, a Beacon interval Present subfield 543, a TSF Offset Present subfield 544, a DTIM Info Present subfield 545, an NSTR Link Pair Present subfield 546, an NSTR Bitmap Size subfield 547, a BSS Parameters Change Count Present subfield 548, and a Reserved subfield 549.

[0151] The STA MAC Address Present subfield 542 is set to 1 if the STA MAC Address field is present in the STA Info field 534. Otherwise, this subfield is set to 0.

[0152] The Beacon interval Present subfield 543 is set to 1 if the Beacon interval subfield is present in the STA Info field 534. Otherwise, this subfield is set to 0.

[0153] The TSF Offset Present subfield 544 is set to 1 if the TSF Offset subfield is present in the STA Info field 534. Otherwise, this subfield is set to 0.

[0154] The DTIM Info Present subfield 545 is set to 1 if the DTIM Info subfield is present in the STA Info field 534. Otherwise, this subfield is set to 0.

[0155] The NSTR Link Pair Present subfield 546 is set to 1 if the NSTR Indication Bitmap subfield is present in the STA Info field 534. Otherwise, this subfield is set to 0.

[0156] The BSS Parameters Change Count Present subfield 548 is set to 1 if the BSS Parameters Change Count subfield is present in the STA Info field 534. Otherwise, this subfield is set to 0.

[0157] The STA Info field 534 includes a STA Info Length subfield 550, and, according to the values specified in the STA Control subfields (542-548), the STA Info field 534 optionally includes a STA MAC Address subfield 551, a Beacon interval subfield 552, a TSF Offset subfield 553, a DTIM Info subfield 554, an NSTR Indication Bitmap subfield 555 (whose size depends on the NSTR Bitmap Size subfield), and a BSS Parameters Change Count subfield 556.

[0158] The STA Profile field 535 carries a variable number of fields and elements in the order defined in the different frame bodies corresponding to the frame carrying the Multi-Link element. For example, the STA Profile included in the Multi-Link element carried in the Association Request frame refers to Table 9-62 Association Request frame body.

[0159] The per-STA profile MUST NOT contain a Neighbor Report element, a Reduced Neighbor Report element, a Multiple BSSID element, a TIM element, a Multiple BSSID-Index element, a Multiple BSSID Configuration element, or other Basic Multi-Link elements in the Per STA Profile subelement.

[0160] FIG. 1a shows an exemplary 802.11be multilink reference model for MLD, which may be either AP MLD or non-AP MLD.

[0161] MLD includes a PHY layer 200, a MAC layer 220, a Logical Link Control (LLC) sublayer, and upper layers, which may include applications that generate or use received traffic data.

[0162] The transmission and reception of traffic data is handled by the MAC 220 layer and the PHY 200 layer. Such transmission and reception of traffic data may occur over multiple links 20-x, 20-y, 20-z, such as links 151, 152, 161, 162 introduced with reference to FIG. 1, as well as over a single-link TDLS direct link 171 (see FIG. 1), if established. Three links, and therefore three affiliated stations, are shown in the figure. Of course, other configurations including two affiliated stations or more than three affiliated stations may also be envisioned.

[0163] Traffic data is provided from higher layers as a series of data frames, or "traffic streams." Each traffic stream, and therefore each data frame, is associated with an Access Category (AC), as defined by the EDCA mechanism (FIG. 1b). This mapping between streams or data frames and ACs is performed by classifier 213.

[0164] It is recalled that 802.11 stations (AP and non-AP stations) maintain four access categories (ACs), each with one or more corresponding transmit buffers or queues. The four ACs are conventionally defined as follows: AC1 and AC0 are reserved for best effort and background traffic, which have the second lowest and lowest priority, respectively; and - AC3 and AC2 are typically reserved for real-time applications (e.g., voice and video transmission). These traffic types have the highest and second-highest priority, respectively.

[0165] Data frames, also known as MAC service data units (MSDUs), coming from higher layers of the protocol stack are mapped by classifier 213 to one of the four ACs and are therefore queued for transmission in the queue of the AC to which they are mapped.

[0166] Figure 1b shows an implementation model with four transmission queues, one for each access category.

[0167] The 802.11be multi-link reference model reflects the fact that an MLD may transmit and receive using multiple links, particularly at the MAC layer 220 and PHY layer 200 levels.

[0168] The MAC layer 220 includes one United Upper-MAC (UMAC) layer 230 and multiple Lower-MAC (LMAC) layers 220-x, 220-y, 220-z coupled to respective PHY layers 200-x, 200-y, 200-z, each combination corresponding to a link 20-x, 20-y, 20-z.

[0169] The UMAC 230 performs functions common to all links, and each LMAC 220-x, 220-y, 220-z performs functions local to each link 20-x, 20-y, 20-z. The UMAC layer provides the UMAC interface to the link-specific blocks 220-x, 220-y, 220-z and provides a UMAC Service Access Point (SAP) to the LLC layer and upper layers.

[0170] The UMAC 230 is responsible for link lossy MAC procedures such as authentication, association, security association, sequence number allocation, MAC Protocol Data Unit (MPDU) encryption / decryption, aggregation / deaggregation, and acknowledgement scoreboarding procedures.

[0171] Each data unit (MSDU) arriving at the MAC layer 220 from a higher layer (e.g., link layer) is mapped to one of the ACs according to a mapping rule in the UMAC layer 230 using the priority of the traffic type (user priority (UP) and therefore traffic identifier (TID)). Then, also in the UMAC layer 230, the data unit (MSDU) is provided with the next available sequence number and stored in the queue corresponding to its TID (or UP) within the mapped AC.

[0172] Each LMAC 220-x, 220-y, 220-z is responsible for link-specific functions such as channel access. In particular, each MLD's Lower MAC contains its own contention-based channel access procedure, e.g., EDCA 221-x, 221-y, 221-z. Some functions require joint processing by both the UMAC 230 and the LMAC 220-x, 220-y, 220-z.

[0173] As shown in Figures 1a and 1b, each EDCA 221-x, 221-y, and 221-z per link performs contention for each queue per link. In that regard, each AC has its own set of queue contention parameters per link, associated with a priority value, thus defining high- or low-priority traffic for MSDUs. Thus, for a given link, multiple traffic queues exist to serve data traffic with different priorities. The contention window CW and backoff values, known as EDCA variables, are specific to each link 20-x, 20-y, and 20-z.

[0174] This means that each AC operates as an independent DCF contention entity on a given link, including a respective queue backoff engine 211. Thus, each queue backoff engine 211 is associated with a respective traffic queue 210 for using queue contention parameters and for deriving a backoff value (from the CW) to initialize a respective queue backoff counter, which is specific to each AC and link. The backoff counter is used to contend for access to the links 20-x, 20-y, 20-z to transmit data stored in the AC's queue. In practice, the backoff counter is decremented from its initialized value when the medium is idle, and when the backoff counter reaches zero, the corresponding affiliated STA 201-x, 201-z is allowed to transmit (is granted access).

[0175] When an AC on a link is granted access to the wireless medium, the MSDUs stored for that AC are sent to the physical (PHY) layers 200-x, 200-y, 200-z for transmission over that link.

[0176] The affiliated STA entities 111-121-131 (similarly 112-122-132) are granted a transmission opportunity (TXOP) using a conventional Enhanced Distributed Channel Access (EDCA) contention scheme and then compete one-by-one with each other on their common channel for access to the wireless medium to transmit (single-user, SU) data frames. The affiliated STAs 121-131 (similarly 122-132) may also use a multi-user (MU) scheme that allows the affiliated AP 111 (similarly 112) of the AP MLD 110 to schedule MU transmissions, i.e., multiple simultaneous transmissions to or from stations in its BSS, in the wireless network. One implementation of such a MU scheme is adopted, for example, in the IEEE Std 802.11ax-2021 standard as the Multi-User Uplink and Downlink OFDMA (MU UL and DL OFDMA) procedure.

[0177] The mechanism of single-link TDLS direct link in the context of MLD will now be described with reference to Figure 2a, which illustrates possible scenarios for an initiator's peer non-AP STA or an initiator TDLS peer STA (affiliated non-AP STA) to process P2P traffic using frame exchanges in a timeline.

[0178] In this example, STA A1 121 is involved as the initiator of the P2P communication and STA B1 131 is involved as the partner or responder of the P2P communication 171. Both are part of the same BSS on a given link 1 (151 / 161) and are associated with AP 111. As mentioned above, STA A1 and STA B1 may be non-AP stations belonging to their respective non-AP MLDs, and AP 111 may be an AP belonging to AP MLD 110.

[0179] In sequence, STA A1 and STA B1 associate with the AP (association not shown) and are able to exchange data over an operational link via the AP.

[0180] To reduce the amount of traffic forwarded within the network and prevent congestion at APs, the IEEE 802.11z amendment defines a mechanism known as Tunneled Direct Link Setup (TDLS), which allows 802.11 non-AP stations to set up a direct link between them while maintaining their association with the AP. The D2.2 standard upgrades the traditional TDLS mechanism to work with multi-link capabilities.

[0181] Tunneled direct-link setup (TDLS) is characterized by the use of signaling frames encapsulated in 802.11 data frames so that the signaling frames are transmitted transparently through the AP. Therefore, to use TDLS, the AP does not need to be aware of the direct link or support the same set of features used by the direct link.

[0182] In the illustrated sequence, a TDLS session or "TDLS direct link" is established between STA A1 and STA B1 (either of which can be the initiator of the TDLS direct link establishment). The establishment may include a TDLS discovery procedure (optional) and a TDLS setup procedure.

[0183] The TDLS discovery and setup procedures between STA A1 and STA B1 typically involve frames known as TDLS action frames (see Figure 3) that are transmitted and received via an intermediate AP 111. The TDLS procedure is characterized by encapsulating signaling frames (TDLS action frames) into 802.11 data frames, allowing them to be transmitted transparently (hence "tunneled") through the AP.

[0184] When attempting to discover TDLS stations within the same BSS, a series of frame exchanges is used. In the proposed scenario, the initiator, STA A1, sends a TDLS Discovery Request frame 221 tunneled (relayed as indicated by the black dots) through AP 111 to the respective destination station (here, STA B1).

[0185] This request frame (similar to the TDLS Setup Request / Response / Confirm and TDLS Discovery Response frames described below) carries the so-called "Link Identifier" element (see Figure 4a) and the "TDLS Multi-Link" element (see Figure 4b) from among the IEs in the Elements field 303. The other IEs that make up the Elements field 303 are specified in Table 9-507 defined in IEEE802.11-REVme / D2.0 (October 2022).

[0186] The Link Identifier element is shown in FIG. 4a under reference numeral 400. It includes a BBSID field 401, a TDLS initiator STA address field 402, and a TDLS responder STA address field 403. The BSSID field 401 is set to the BSSID of the BSS to which the TDLS initiator STA A1 belongs if the frame carrying the element is sent by a STA that does not belong to a non-AP MLD. Otherwise, in the context of MLD operation, the BSSID field is set to the BSSID of the AP operating on the link over which the non-AP MLD 120 attempts to establish a single-link TDLS direct link. The TDLS initiator STA address field 402 is set to the TDLS initiator MAC address, which is the MLD MAC address of MLD A120 in the context of MLD operation. The TDLS responder STA address field 403 is set to the TDLS responder MAC address, which is the MLD MAC address of MLD B130 in the context of MLD operation.

[0187] The destination station STA B1 responds to the TDLS Discovery Request frame 221 with a TDLS Discovery Response frame 222 that is sent directly to STA A1 (without relaying through the AP 111). This response frame carries the "Link Identifier" element and the "TDLS Multi-Link" element from the IEs in the element field 303.

[0188] From this point on, STA A1 and STA B1 know each other, know that the other is operating with the same link setup as AP 111, and they can establish a TDLS direct link.

[0189] When attempting to establish a TDLS direct link on a single link with a discovered TDLS station, a series of TDLS action frame exchanges are used to set up a TDLS direct link on a single link.

[0190] The TDLS initiator STA A1 first sends a TDLS Setup Request frame 223 to the target TDLS responder STA B1, tunneled (relayed as indicated by a black dot) via the AP 111. This request frame carries the "Link Identifier" element and the "TDLS Multi-Link" element among the IEs in the Elements field 303. The other IEs forming the Elements field 303 are defined in Table 9-497 defined in IEEE802.11-REVme / D2.0 (October 2022) and include information about the capabilities of the TDLS initiator STA A1 and its AID.

[0191] The TDLS responder STA B1 responds with a TDLS Setup Response frame 224, which is also tunneled through the AP 111. This response frame carries the "Link Identifier" element and the "TDLS Multi-Link" element among the IEs in the Elements field 303. The other IEs that make up the Elements field 303 are defined in Table 9-498 defined in IEEE 802.11-REVme / D2.0 (October 2022) and contain information about the capabilities of the TDLS responder STA B1, its AID, as well as a status code indicating whether the setup request is accepted or rejected.

[0192] If the Setup Request is accepted, the TDLS initiator STA A1 then sends a confirmation (TDLS Setup Confirm frame 225), which is also tunneled through the AP 111. This confirmation frame carries the "Link Identifier" element and the "TDLS Multi-Link" element among the IEs in the Elements field 303. The other IEs that make up the Elements field 303 are defined in Table 9-499 defined in IEEE 802.11-REVme / D2.0 (October 2022).

[0193] This completes the TDLS setup handshake. At this point, the two non-AP MLDs know each other's identifiers: on the one hand, the MLD MAC address, and on the other hand, the AID assigned by the AP MLD.

[0194] During the TDLS setup handshake, the TDLS STAs (initiator and responder) may establish a robust security network association (RSNA) for the TDLS direct link. This security protection for the TDLS direct link follows the security method in the connection between the STA and the AP, whereby if any security method is enabled in the connection between the STA and the AP, the STA requires the security protocol to be successfully completed before using the TDLS direct link. If no security method is enabled in the connection between the STA and the AP, the STA will not use the security protocol in the TDLS direct link.

[0195] To protect the TDLS direct link, the TDLS STAs use the TDLS PeerKey (TPK) security protocol (as defined in Section 12.7.8 of IEEE802.11-REVme / D2.0 (October 2022)). The TPK key is derived by each TDLS STA during the TDLS setup handshake and depends on the information elements included in the TDLS frame: the "Link Identifier" element, the "robust security network" element (RSNE), the "Timeout Interval" (TPK key validity period) or TIE element, and the "fast BSS transition" or FTE element (listed in Table 399 below). Some information related to the TDLS session itself is used for TPK derivation. Such information, e.g., the MAC address of the TDLS initiator, the MAC address of the TDLS responder, and the BSSID, are obtained directly from the Link Identifier element shared between both TDLS STAs. The D2.2 standard slightly modifies this procedure to support the establishment of a single-link TDLS direct link via non-AP MLD. Therefore, to support this new procedure, a "TDLS Multi-Link" element is added to the TDLS setup frame, and the AP MLD MAC address carried by this "TDLS Multi-Link" element is added as a new parameter for deriving the TPK used for the multi-link TDLS session.

[0196] The stations can then begin communicating directly over link 171 (the direct link): P2P traffic 226 can be exchanged directly (no black dots are shown on the APs in the diagram for arrow 226) between STA A1 and STA B1 using the established TDLS session. TDLS peers STA A1 and STA B1 are configured to accept data frames received directly from the other peer. The frame exchange occurs over the same link, i.e., the same frequency channel, so that this P2P traffic is simultaneous with other traffic on AP1 111.

[0197] Reference numeral 171 in FIG. 1 indicates a single-link TDLS direct link that, when established, enables MLD A120 (through affiliated STA A1 121) and MLD B130 (through affiliated STA B1 131) to exchange data directly without relaying by AP MLD 110.

[0198] To avoid conflicts with AP traffic, tunneled direct link setup (TDLS) stations that support TDLS channel switching can decide to perform a TDLS Channel Switch to a Supported Channel. TDLS stations inform each other about their supported channels during the TDLS setup procedure, i.e., they include a Supported Channel element and a Supported Operating Classes element in all TDLS Setup Request and TDLS Setup Response frames with the TDLS Channel Switching subfield equal to 1. Further advantageously, a TDLS station can move from the base channel (i.e., the channel corresponding to the link set up with the AP (AP1 111 in the above example)) to an off-channel, i.e., a channel that does not overlap with the channel used by the access point (AP) to which the TDLS station is associated. Recall that the off-channels available for use by the TDLS are provided by the AP through the Channel Usage element 600 sent in the Probe Response 213 frame or the Channel Usage Response frame.

[0199] Returning to the example of Figure 2a, the TDLS STA initiator 121 sends a TDLS Channel Switch Request frame 231 on the TDLS direct link. This frame includes the target channel, i.e., the destination off-channel for the intended channel switch. The target channel is identified by the STA initiating the channel switch from the set of operation classes supported by both TDLS peer STAs. Upon receiving the TDLS Channel Switch Request frame 231, the target partner STA B 131 responds with a TDLS Channel Switch Response frame 232 to accept or reject the Channel Switch. If the status code indicated in the response frame is set to REQUEST_DECLINED, both stations continue operating on the current channel. Otherwise, if the status code is set to SUCCESS in the response frame, both stations must move to the target channel before the switch time also indicated in the TDLS Channel Switch frame, but must not start their first transmission before the end of the switch time. Finally, after the switch time has elapsed, the initiator STA A1 can send P2P data frames on the target channel.

[0200] The off-channel usage remains within the scope of the TDLS STA's operation on the initially established TDLS direct link, i.e., associated with AP1 111 and the link ID of the link still being set up.

[0201] When operating over an off-channel, the TDLS STA enters power-save mode with the AP and is unable to communicate with the AP over the link's base channel, so it must periodically return to the base channel to receive beacons, check the Traffic Indication Map (TIM) for buffered packets, and communicate with other devices in the network.

[0202] The TDLS procedure is detailed in IEEE802.11z and has been upgraded to be established over one of several possible links as provided in the D2.2 standard.

[0203] Figure 3 shows the format of an 802.11 action frame 300. In this figure, only the payload of such an action frame is shown, with the MAC header omitted for simplicity.

[0204] The action frame 300 has a frame format, and therefore has a Category field 301 , an Action field 302 immediately following the Category field 301 , and an Elements field 303 .

[0205] The different values of the Category field 301 are defined in the 802.11 standard and correspond to different Actions frames: a Category field set to 12 defines a TDLS Action frame, and a Category field set to 4 defines a Public Action frame.

[0206] The TDLS action frame carries the TDLS signaling.

[0207] The 1-byte Action field 302 of a TDLS action frame can take on various values from 0 to 10 (11 to 255 are reserved) as shown in Table 9-496 of the 802.11 standard (e.g., IEEE802.11-REVme / D2.0 (October 2022)) to signal different types of TDLS action frames, each with its own unique function in the TDLS mechanism. For example, a TDLS Setup Request frame 213 is identified by its Action field 302 set to 0, a TDLS Setup Response frame 214 is identified by its Action field 302 set to 1, a TDLS Setup Confirm frame 215 is identified by its Action field 302 set to 2, a TDLS Channel Switch Request frame 231 is identified by its Action field 302 set to 5, and a TDLS Channel Switch Response frame 232 is identified by its Action field 302 set to 6.

[0208] The following table 399 is provided for illustrative purposes only to show example IEs in the Elements field 303 that are provided in a TDLS Setup action frame (i.e., a frame with the Action field 302 set to 0, 1, or 2). Each type of TDLS action frame has its own set of elements 303 (Category, TDLS Action, and Dialog Token, as defined in the standard) that are provided to identify the frame.

[0209] The Action field of the TDLS Setup Request Action field contains the following information, but the corresponding TDLS Setup Response Action field contains that information only if the status code is SUCCESS. TIFF2025526224000002.tif175158TIFF2025526224000003.tif242158

[0210] The Action field of the TDLS Setup Confirm Action field may contain a subset of this list, where the Capabilities IE is replaced with an Operation IE (e.g., the HT / VHT / HE / EHT Capabilities IE is replaced with the HT / VHT / HE / EHT Operation IE).

[0211] Of the elements that are of most interest for the present invention, the Supported Channel and Supported Operating Classes elements are used by peer STAs to inform each other about possible channels for operating off-channel.

[0212] The IEEE P802.11be / D2.2 version is expected to enable the setup of a TDLS direct link in one communication link for MLD.

[0213] All TDLS Discovery and Setup request and response frames include the TDLS multi-link IE as illustrated in Figure 4b. The TDLS multi-link IE 450 is based on the structure of the Multi-Link element introduced to support multiple links (e.g., the basic version is used for MLD associations), and is therefore structured as follows: Element ID equal to 255, The Length field 452 defines the length of the information element, The Element ID extension field 453 is set to 107 to identify the multi-link IE, The Multi-Link Control field 460 can define the type of the multi-link IE as TDLS (value 3) using the Type field 461; The Common Info field 470 includes a Common Info Length field 471 and an AP MLD MAC address field 472 set to the MAC address of the AP to which the TDLS initiator's non-AP STA belongs; The Link Info field 480 is reserved (meaning it is not used).

[0214] As a result, the TDLS Multi-Link IE450 allows each peer non-AP STA to share the AP MLD MAC address for AP MLD in a multi-link environment.

[0215] A TDLS STA belonging to a non-AP MLD considers a TDLS (Discovery / Setup) frame only if the frame is transmitted through a TDLS Multi-Link element 450 and the MLD MAC address carried in the AP MLD MAC address field 472 of the TDLS Multi-Link element 450 matches the MLD MAC address of the AP MLD for which the non-AP MLD has already performed multi-link setup.

[0216] Outside the scope of TDLS, the IEEE P802.11be / D2.2 version also envisions enabling link description for MLDs. Between an AP MLD and a non-AP MLD associated with it, the MLD may transmit individual address management frames (MMPDUs) to other STAs, targeted at one or more STAs belonging to the associated MLD. In other words, the MMPDU is intended to be delivered over a given link(s) different from the link(s) associated with the management information (e.g., the information may be directed to multiple STAs / links, or retransmissions may be intended for different STAs). According to FIG. 4c, the Multi-Link Link Information element 490 identifies the intended link of the MMPDU carrying that element. The Link ID Bitmap field indicates the link on which the intended STA is operating (see 35.3.2.1 (General) for the use of Link IDs). This description of link identification is further considered as another means useful for embodiments.

[0217] As a result, the D2.2 standard allows direct link communication between non-AP MLDs using one or more single-link TDLS direct links, which means that separate and independent TDLS sessions can be established on multiple links via multiple affiliated STAs of the same non-AP MLD.

[0218] From the above explanation, we can see that off-channel usage follows legacy behavior that does not utilize the multi-radio / multi-link capabilities of devices, despite the significant interest in improving the coexistence of infrastructure and P2P communications. Therefore, a non-AP MLD cannot maintain communication with an AP MLD (or AP) through one link, while another link may be camped off-channel for P2P communications. On the other hand, off-channel usage is performed by a TDLS channel switch from the base channel to one of the off-channels, so repeated TDLS channel switches are required to switch back and forth between the base channel and off-channels.

[0219] Note that this constraint between the base channel and the off-channel arises from using the same enabled link to support both channels, since for the time being, non-AP MLD relies only on the link set up with the AP MLD.

[0220] The present inventors intend to overcome some of the aforementioned concerns by providing an off-link scheme, an extension of off-channel usage that allows sustained use of network resources while maintaining a dedicated link for communication with an AP. This is achieved by dedicating a link (and therefore a link ID) for direct communication over the off-channel. Thus, an "off-link" is defined that is separate from the link on which the AP operates.

[0221] As an example, an AP MLD (or device) may instantiate a virtual AP that does not communicate in the AP MLD's BSS. The virtual AP defines an off-link corresponding to at least one off-channel that does not overlap with channels used by other APs belonging to the AP MLD. The virtual AP is therefore assigned a link identifier (ID) that identifies the off-link that the non-AP MLD should use to set up a TDLS direct link.

[0222] FIG. 7a illustrates an 802.11 network environment including a multi-radio device MLD such as that of FIG. 1, in which the present invention may be implemented. The example of FIG. 7a shows two non-AP MLDs (non-AP MLD A 120 and non-AP MLD B 130) with three affiliated STAs (121 to 123 and 131 to 133, respectively), and an AP MLD 110 with three affiliated APs 111, 112, and 113. AP 113 is an instantiation of a virtual AP, whose purpose is to obtain link IDs corresponding to a set of off-channels (at least one off-channel) to support off-link 173 for operation outside the control of the AP MLD. As a result, the non-AP MLDs 120 and 130 can use off-link 173 with one of the affiliated stations while maintaining their previous connection with the AP MLD via links 1 and 2, corresponding to their connections with affiliated APs 1 and 2, respectively.

[0223] Of course, the number of illustrative links shown in this figure is not limiting.

[0224] FIG. 7b illustrates another 802.11 network environment including a multi-radio device MLD such as that of FIG. 1, in which the present invention may be implemented. The example of FIG. 7b shows two non-AP MLDs (non-AP MLD A 120 and non-AP MLD B 130) with two affiliated STAs (121-122 and 131-132, respectively), and an AP MLD 110 with four affiliated APs 111, 112, 113, and 114. APs 113 and 114 are instantiations of virtual APs, and the purpose of each of these virtual APs is to obtain a link ID. The link associated with AP 113 corresponds to a first set of off-channels and enables off-link 173. The link associated with AP 114 corresponds to a second set of off-channels that enables another off-link (not shown). The virtual APs 113 and 114 may optionally belong to a virtual AP MLD 110b with a specific MLD ID. As a result, non-AP MLDs 120 and 130 can use an off-link (e.g., 173) with one of their affiliated stations while maintaining their previous connection with the AP MLD via link 1, which corresponds to their connection with affiliated AP 1.

[0225] FIG. 7c illustrates an example of wireless communication operations performed by AP MLD for virtual AP instantiation in accordance with certain aspects of the present invention.

[0226] The operation may begin in step 710, when the AP MLD (e.g., 110) receives a trigger to instantiate a virtual AP. For example, this trigger may be a Probe Request frame 212 received from a not-yet-associated non-AP MLD, including off-link capabilities as a new entry in the Extended Capabilities element (e.g., bit 90) and / or Channel Usage element. After association, the non-AP MLD may request assistance in setting up a non-infrastructure network off-channel, i.e., off-link setup, by sending a Channel Usage Request to the AP MLD with the Usage mode field of the Channel Usage element set to 2. Alternatively, the trigger may be QoS characteristics as defined in Draft 2.0, with the Direction subfield having a value corresponding to direct link communication. In another alternative, the trigger may be an internal trigger; for example, if the AP MLD supports virtual AP or off-link functionality, the AP MLD may set up an off-link by instantiating a virtual AP. In another alternative, the AP MLD may instantiate a virtual AP for any reason, without a specific trigger.

[0227] In other words, the trigger for instantiating an affiliated virtual AP is: - receiving a Probe Request frame (212, 812) from a non-AP MLD, including off-link capabilities as a new entry in the Extended Capabilities and / or in the Channel Usage element (600) if the non-AP MLD is not already associated with the AP MLD; receiving a Channel Usage Request frame (815) from the non-AP MLD, the Channel Usage element requesting off-link setup, if the non-AP MLD is not yet associated with the AP MLD; receiving quality of service (QoS) characteristics; -Detecting a trigger within the AP MLD; belongs to a group that includes

[0228] In step 720, the AP MLD (e.g., 110) instantiates a virtual AP 113 (at least one, even if the description focuses on one VAP), i.e., assigns an AP ID that can further be used as a link ID. The purpose of instantiating a virtual AP is to obtain at least a link ID. In other words, the AP MLD instantiates an affiliated virtual AP that defines an off-link corresponding to at least one off-channel that does not overlap with the channel used by the AP MLD, and the affiliated virtual AP is assigned a link identifier (ID) so that it can identify the off-link, and the virtual AP does not communicate in its own basic service set (BSS).

[0229] Next, in step 730, the AP MLD defines the characteristics of the virtual AP, such as, in addition to the link ID, the operating class, the channel number, the channel width defining the operating frequency band, the BSSID, information related to the BSSID indicating that the virtual AP is unreachable, a Non-Inheritance element, etc.

[0230] In a particular embodiment, a virtual AP can be distinguished from an AP with which it can communicate using a particular value of the AP Reachability field from the BSSID Information element, as defined in IEEE 802.11-REVme / D1.3.

[0231] And finally, in step 740, the AP MLD notifies the non-AP MLD or STAs of the characteristics of the virtual AP. In other words, the AP MLD sends information about the affiliated virtual AP defining the off-link, including the link ID, to the non-AP MLD. To do this, the AP MLD may send the information in different frames depending on the event that triggered the instantiation of the virtual AP and the type of information the AP MLD wants to share with the STAs.

[0232] Complete the characteristics of the virtual AP The AP MLD may include the identity and characteristics of the virtual AP as part of the Multi-Link element of the Probe Response frame 213, the Beacon frame 211, or the Association Response frame 215. Therefore, the virtual AP may be an additional STA in the Link Info 530 with its own per STA profile. The per STA profile corresponding to the virtual AP must include information for distinguishing the virtual AP from other APs. For example, as shown in FIG. 5b, a new Off-link field 560 may be included in the STA Control field 533. The Off-link field is set to 1 if the link corresponding to the link ID is an off-link bound to a virtual AP that is not directly reachable. The STA Info field 534 may also include a Usage Mode subfield 561. The Usage Mode subfield 561 is a number that identifies the (recommended / restricted) usage of the link corresponding to the link ID carried in subfield 540. In a variant, the Usage Mode field 561 may be conditionally present if the Off-link subfield 561 is set to 1. The Usage Mode subfield may be the same as the subfield 630 depicted in FIG. 6 / 6a / 6b. The Usage Mode definition table 660 depicted in FIG. 6a includes, in addition to existing values, new values "3," "4," and "5" that can be used to specify how the link is used. The new value "3" 664 indicates that the link should be restricted to P2P communication, the value "4" 665 indicates that the link is dedicated to AP-to-AP communication, and the value "5" 666 indicates that the link is dedicated to coexistence with communication over another wireless access technology, e.g., a device may incorporate multiple communication chips (cellular, Wi-Fi, Bluetooth) and attempt to optimize coexistence between these different wireless access technologies. The usage mode definitions may be a separate table from the table used for the channel usage element to define link usage, as depicted in FIG. 5b.In this table 570, a value of "0" 571 indicates that the link should be restricted to P2P communication, a value of "1" 572 indicates that the link is dedicated to communication between APs, and a value of "2" 573 indicates that the link is dedicated to low latency communication.

[0233] In an alternative embodiment, the Common Info field 520 (FIG. 5a1) includes a new Off-link Bitmap or Virtual AP Bitmap subfield. Each bit in the Off-link Bitmap (or Virtual AP Bitmap) subfield included in the Common Info field 520 corresponds to a link, and bit position i in the bitmap corresponds to a link whose link ID is equal to i. A value of 1 in bit position i of the bitmap corresponding to a link to which the STA belongs in the non-AP MLD indicates that this link is an off-link or that the AP corresponding to this link is a virtual AP; otherwise, the bit position is set to 0. This variation may be interesting for improving the parsing of per-STA profile elements. This allows the STA to skip per-STA profiles corresponding to links identified as off-link or that the AP corresponding to this link is a virtual AP if the STA is not interested in the off-link / virtual AP functionality.

[0234] Furthermore, the per STA profile may include all elements necessary to characterize the virtual AP.

[0235] In other words, information about the affiliated virtual APs is exchanged at least in part as part of the Multi-Link element 500 in a Probe Response frame 213, or a Beacon frame 211, or an Association Response frame 215, where: The Affiliated Virtual AP is declared as an additional STA in the Multi-Link element 500 using a dedicated per STA profile sub-element 530 containing information 560, 561 to distinguish the Affiliated Virtual AP from other Affiliated APs in the AP MLD; The Common Info field 520 of the Multi-Link element 500 includes an off-link Bitmap subfield or a Virtual AP Bitmap subfield.

[0236] Optionally, the Non-Inheritance element appears as the last element in the STA Profile field and carries a list of elements not inherited by the reported STA from the reporting STA. In one embodiment, this element carries all element IDs corresponding to AP capabilities or behaviors (HE, EHT, QoS) that are not useful in the virtual AP context. As an example, all capabilities or behavior parameters commonly used to describe links for non-AP MLD operation (e.g., HT / HE / VHT / EHT capabilities or behavior IEs) must not be inherited by the reportee virtual link / AP from the reporting STA; therefore, these elements are specified in the Non-Inheritance element, which exists as a site element in the per STA profile of the Basic Multi-Link element. In another embodiment, the per-STA profile of the virtual AP is defined only by the elements included in that per-STA profile, not subject to inheritance from the reporting STA. In other words, the per-STA profile may exclude all elements necessary to characterize communication through the virtual AP.

[0237] In other words, the per STA profile sub-element 530 for each affiliated virtual AP is: - including a Non-Inheritance element conveying AP capabilities and / or behaviors that cannot be used in the context of the virtual AP due to the virtual AP not communicating in its own Basic Service Set (BSS); -Not subject to inheritance.

[0238] Virtual AP operating channel The AP MLD may also send a Channel Usage Response frame (either in response to receiving the Channel Usage Request frame of step 710 or autonomously) that includes a Channel Usage element. To inform the STA of the operating channel of the virtual AP, i.e., the off-link operating channel, a new variant of the Channel Usage element may be envisioned. Accordingly, this new variant of the Channel Usage element (presented with reference to FIG. 6A) includes, at the end of the payload 600, a new field 650 that carries the link ID associated with the different channel entry 640. This field 650 may be the Link ID Info subfield 523 shown in FIG. 5a1. Another variant, shown with reference to FIG. 6b, includes the link ID Info subfield 643 as a new subfield of the Channel entry field 640.

[0239] The variations of the Channel Usage element presented with reference to Figures 6a and 6b may be included in the Probe Response frame body for the reporting AP (AP1 in the example of Figure 8) or in the per-STA profile included in the Multi-Link element for the reported AP (AP2 in the example of Figure 8). If the Channel Usage element (shown with reference to Figures 6, 6a, and 6b) is included only in the frame body for the reporting AP, it may include channel usage information for all bands (2.4 GHz, 5 GHz, and 6 GHz) supported by all APs belonging to the AP MLD of the reporting AP. The reporting AP may optionally advertise the Supported Channels for other affiliated APs (reported APs) using the multi-band element (as defined in IEEE 802.11-REVme / D1.3 (June 2022), Clause 9.4.2.138, Multi-Band element). In another alternative, the Channel Usage element may be included in the Common Info field 520 along with the channel usage of the AP MLD (including all affiliated APs). Alternatively, channel usage information may be advertised per band corresponding to the bands of different APs belonging to the AP MLD, whereby, as described above, the Channel Usage element is carried in the frame body for the reporting AP and in the per-STA profile of the Multi-Link element for one or more reported APs. For example, if AP1 is operating in the 2.4 GHz band, AP1 may report only the channel usage corresponding to the 2.4 GHz band, and if AP2 is operating in the 5 GHz band, AP2 may report only the channel usage corresponding to the 5 GHz band.

[0240] In other words, the information about the affiliated virtual AP includes information about at least one off-channel of the AP MLD exchanged as a Channel Usage element 600, which includes: a Link ID Information field 650 containing a link ID and associated with every Channel entry in the Channel Entry field 640; or a Link ID Information subfield 643 of the Channel Entry field 640 containing a link ID and associated with every Channel entry in the Channel Entry field 640; Including, The Channel Usage element is included in the Probe Response frame 213 or the Channel Usage Response frame 816.

[0241] Additionally, AP MLD may use a Neighbor Report element or a Reduced Neighbor Report element to convey partial or complete characteristics of a virtual AP / off-link. Examples of the TBTT information field included in a Reduced Neighbor Report element according to an embodiment of the present invention are shown in Figures 9a and 9b.

[0242] Returning to Figure 9, in the example of Figure 7a, a beacon frame carrying a Reduced Neighbor Report element includes at least two information fields 920 corresponding to AP2 and AP3 (as reported APs). AP3 is a virtual AP. Now, in the example of Figure 7b, a beacon frame carrying a Reduced Neighbor Report element includes at least three information fields 920 corresponding to AP2, AP3, and AP4 (as reported APs). AP3 and AP4 are virtual APs. The value of the MLD ID field 941 may differ between AP2 and virtual AP3 and virtual AP4.

[0243] 9a, the MLD Parameters field 940 includes a new Off-link field 944. The Off-link field is set to 1 if the link corresponding to the link ID carried in field 942 is an off-link bound to a virtual AP that is not directly reachable.

[0244] In the second embodiment of Figure 9b, MLD Parameters field 940 includes a new Usage Mode field 945. Usage Mode field 945 is a number that identifies the usage of the link corresponding to the link ID carried in field 942. The value that identifies the usage of the link may depend on table 660 presented in Figure 6a, table 570 presented in Figure 5b, or table 9-265 presented in Figure 6 and published from IEEE P802.11-REVme / D1.3 version, or any combination of values presented in these tables.

[0245] In other words, information about the affiliated virtual APs is exchanged at least in part as part of the Neighbor Report element or Reduced Neighbor Report element 910 included in the beacon frame 211, part of which is the off-link field 944 or Usage Mode field 945 included in the MLD Parameters subfield 940, which provides information about the link corresponding to the contents of the Link ID field 942 also included in the MLD Parameters subfield 940.

[0246] A third embodiment may be a combination of the previous two. In this case, MLD Parameters 940 includes an Off-link field 944 and a Usage Mode field 945. The Off-link field is set to 1 if the link corresponding to the link ID carried in field 942 is an Off-link bound to a virtual AP that is not directly reachable. The Usage Mode field 945 is a number that identifies the usage status of the Off-link corresponding to the Link ID carried in field 942. The Usage mode element may only be present if the Off-link field 944 is set to 1.

[0247] In a variant, the AP MLD may create a virtual AP based on an existing affiliated AP. For example, the AP MLD may unmap all downlink and uplink TIDs of the link corresponding to the AP to be converted in the virtual AP. Furthermore, the AP MLD may map only some of the TIDs in the P2P TID-to-Link mapping of the link bound to the virtual AP.

[0248] Additionally, the AP MLD's virtual AP or off-link capabilities may be reported to non-AP MLDs through a new entry (e.g., bit 90) in the Extended Capabilities element or a new subfield (e.g., one of the reserved bits) of the MLD Capabilities and Operations of the Multi-Link element, carried, for example, in the beacon frame 211, the Probe Response frame 213, the Association Response 215, or the Reassociation Response frame. This capability advertises to non-AP MLDs that the AP MLD supports virtual AP or off-link capabilities, and although the off-link is currently unavailable, one or more non-AP MLDs may further trigger the creation of an off-link, for example, by sending a Channel Usage Request frame as described in FIG. 8b.

[0249] FIG. 7d illustrates an example of wireless communication operation performed by non-AP MLD for off-link TDLS setup according to an embodiment of the present invention.

[0250] The operation begins in step 750, when a non-AP MLD (e.g., 120) sends a trigger to acquire an off-link, e.g., for P2P communication. This trigger can be a Probe Request frame 212 containing the off-link capabilities as a new entry in the Extended Capabilities element (e.g., bit 90) and / or a new entry in the Channel Usage element received from a non-AP MLD that is not yet associated. Note that the Extended Capabilities element containing the off-link capabilities can be carried in an Association Request frame or a Reassociation Request frame in addition to a Probe Request frame. After association, the non-AP MLD can request off-link setup by sending a Channel Usage Request to the AP MLD. The Channel Usage Request frame can contain either the legacy Channel Usage element as defined in IEEE P802.11-REVme / D1.3 version or the new variant of the Channel usage element (shown in FIG. 6a or 6b). In this variation, the Link ID Info field 650 may be set with a particular value requesting the AP MLD to allocate an off-link.

[0251] In step 760, the non-AP MLD receives information related to the AP MLD, either as a direct response to step 750 or following an autonomous transmission of the AP MLD (eg, a beacon or autonomous Channel Usage Response frame).

[0252] In particular, the non-AP MLD obtains a link identifier (ID) that defines an off-link corresponding to at least one off-channel that does not overlap with the channels used by the AP MLD.

[0253] Based on the received information, in step 770, the non-AP MLD 120 initiates multi-link setup with the AP MLD 110, similar to procedure 210 described in FIG. 2. This procedure relies on the exchange of Association request 214 / response 215 frames, each containing a Multi-Link element. The Multi-Link element describes and selects a set of candidate setup links between its affiliated non-AP STAs and some of the discovered affiliated APs, and allows it to request the AP MLD 110 to set up these links, which the AP MLD can accept or reject. In the present invention, if the non-AP MLD intends to use an off-link, it includes information about the virtual AP (off-link) in addition to information about other APs (other links) in the Multi-Link element sent in the Association Request 214. This information is useful for the AP MLD to obtain metrics about off-link usage, such as the number of non-AP MLDs attempting to use the off-link. According to this metric, the AP MLD can further decide to instantiate a new virtual AP to support more P2P communication, or modify an existing one by expanding the operating band. Once the ML setup is complete, both the AP MLD and the non-AP MLD can communicate over the setup link according to the TID-to-Link mapping rules, except for off-links whose use is restricted, for example, for P2P communication.

[0254] Next, in step 780, the non-AP MLD 120 performs a TDLS setup with the second non-AP MLD 130 using the off-link as a target link. In other words, the non-AP MLD establishes a tunneled direct link setup (TDLS) direct link between a first TDLS station (STA) and a second TDLS STA belonging to the non-AP MLD over the channel (and therefore the link) used by the AP device, using the link ID as an indication of the off-link of the TDLS direct link.

[0255] In a particular embodiment, establishing the TDLS direct link includes setting up the TDLS direct link using a link ID to define the off-link as the TDLS direct link.

[0256] This link ID is, for example, the contents of BSSID field 401 in FIG. 4a, the contents of Link ID field 540 in FIG. 5a2, or the bits of Link ID Bitmap field 491 in FIG. 4c.

[0257] In a variant, step 780 can be performed in two consecutive steps. First, the non-AP MLD 120 performs TDLS setup with the second non-AP MLD 130 on the link on which the AP (not the virtual AP) operates, and both non-AP MLDs collect each other's supported channels. Then, the two non-AP MLDs move to one off-link corresponding to the mutually supported off-channel, for example, by using the TDLS channel switch procedure 230. This variant is further described with reference to FIG. 8c.

[0258] In other words, in this modification, establishing a TDLS direct link: setting up an initial TDLS direct link that enables peer-to-peer communication between a first TDLS STA and a second TDLS STA; performing a channel switch to move peer-to-peer communication from the initial TDLS direct link to a target link, the target link using a channel of the off-link as a target channel for the target link or using a link ID to define the off-link as the target link; Includes:

[0259] In a specific implementation of this variant (see below), the non-AP MLD disables or removes the initial TDLS direct link.

[0260] TDLS setup can be performed via any of the links (excluding off-link) set up with the AP MLD. In the example of FIG. 8, the TDLS initiator STA A1 121 performs TDLS setup with the TDLS responder STA B1 131 via AP1 111. Each TDLS setup frame includes a link identifier 400. The TDLS initiator STA Address field 402 included in the link identifier is set with the MLD MAC address of the non-AP MLD 120, the TDLS responder STA Address field 403 is set with the MLD MAC address of the non-AP MLD 130, and the BSSID field 401 is set with the BSSID corresponding to the off-link. In another variant, the off-link can be added to the per STA profile carried in the TDLS Multi-Link element. The ML element sent by the TDLS initiator non-AP MLD in the TDLS Setup Request notifies the peer non-AP MLD on which links the TDLS can be established. In response, the ML element sent by the non-AP MLD of the TDLS responder in the TDLS Setup Response informs the non-AP MLD of the TDLS initiator on which link the TDLS session has been validly established, i.e. the accepted link.

[0261] In another variation, the TDLS setup frame includes a Multi-Link Link Information element 490 that includes a Link ID bitmap 491. This Link ID bitmap 491 indicates the target link of the TDLS setup when the Multi-Link Link Information element 490 is sent in a TDLS Setup Request frame, and indicates the accepted link when the Multi-Link Link Information element 490 is sent in a TDLS Setup Response frame. One bit in the Link ID bitmap may correspond to an off-link in the present invention.

[0262] In other words, establishing a TDLS direct link: - including a link identifier 400 in a TDLS setup frame exchanged between the first TDLS STA and the second TDLS STA, the link identifier including a Basic Service Set Identifier (BSSID) field set with a BSSID corresponding to the off-link according to the virtual AP; Adding an off-link to a per STA profile sub-element 530 carried in a TDLS Multi-Link element 500 exchanged between a first TDLS STA and a second TDLS STA; - Including a Multi-Link Information element 490 including a Link ID bitmap 491 indicating off-link in a TDLS setup frame exchanged between a first TDLS STA and a second TDLS STA; It includes at least one of the following:

[0263] As a result, in step 790, if the TDLS setup is successful, STAs A3 123 and B3 133 (TDLS peer STAs) belonging to non-AP MLDs 120 and 130, respectively, can communicate over off-link. In other words, the non-AP MLD operates peer-to-peer communication between a first TDLS STA and a second TDLS STA over off-link.

[0264] It should be noted that the non-AP MLD may operate communications with the AP device on another link (e.g., 151 in Figures 7a and 7b) corresponding to at least one of the channels used by the AP device.

[0265] Figure 8 illustrates the scenario of Figures 2 and 2a with frame exchanges in a timeline where the AP MLD notifies the non-AP MLD of the TDLS initiator that an off-link is available to handle P2P traffic. The same references as in Figures 2 and 2a correspond to the same phases / steps / frames / entities.

[0266] At the start of the frame exchange, STA A1 121, which belongs to the non-AP MLD 120, does not belong to any AP or AP MLD. In the context of multilink discovery, STA A1 121 transmits a Probe Request frame 812 containing some of the STA capabilities. In the context of the present invention, the Probe Request frame 812 includes a Supported Operating Classes element (positioned 6 in the Probe Request frame body) and a Channel Usage element (positioned 11 in the Probe Request frame body). The Supported Operating Classes element is used by a STA to advertise the operating classes in which it is currently configured to operate, or by a non-AP MLD if the reporting STA belongs to a non-AP MLD. The Channel Usage element includes a link ID Info field (650 in FIG. 6a or 643 in FIG. 6b). The link ID Info subfield is set to a wildcard value, which requests the AP MLD to allocate an off-link. The Usage Mode carried in the Channel Usage element advertises to the AP MLD that the station wishes to use the off-link. The multi-link version of the Probe Request also contains a Multi-Link element that allows it to request information from the AP MLD. If the Multi-Link element does not contain a per-STA profile, the AP MLD shall include information about all affiliated APs; otherwise, the AP MLD shall advertise non-AP MLDs only in per-STA profiles with link IDs equal to the value of the Link ID field contained in the per-STA profile contained in the Multi-Link element of the Probe Request frame.In another embodiment, the Supported Operating Classes may be carried in a per-STA profile included in the Multi-Link element to advertise to each STA belonging to a non-AP MLD the operating class that each STA is currently configured to operate in. Additionally, the STA Control field of the Probe Request Multi-Link element may include a new subfield indicating that this per-STA profile is for AP information, while the per-STA profile of a Multi-Link probe request typically identifies the AP for which that information is requested.

[0267] In another embodiment, the non-AP MLD may use the Multi-band element (order 14 in the Probe Request frame body) to advertise the AP MLD for Supported Operating Classes over different frequency bands. In effect, the Multi-band element indicates that the STA transmitting this element (the transmitting STA) is in a multi-band device capable of operating in frequency bands or operating classes or channels other than the one in which this element is transmitted.

[0268] The target AP MLD 110 responds with a Probe Response frame 813 to STA A1 121 through its affiliated AP1 111. The Probe Response frame contains one or more Channel Usage elements. The Channel Usage element must contain a channel that is valid for the regulatory domain in which the AP transmitting the element operates and that matches the Country element in the Beacon or Probe Response frame; the Channel Usage element must not contain any other channels. The Channel Usage element contains the link ID associated with the virtual AP that is instantiated to create the off-link (step 720 if the AP MLD supports virtual AP or off-link functionality). The operating band assigned to the off-link depends on the Supported Operating Classes collected from the non-AP MLD and the operating frequency band currently used by the AP MLD. Note that the off-channel does not overlap with the channels used by the access point. Additionally, the AP MLD may further consider some non-simultaneous transmit and receive constraints. In an alternative embodiment, the Probe Response frame includes a legacy Usage Channel element. In that case, the Probe Response frame includes a Multi-Link element with the virtual AP identity (i.e., link ID) and characteristics (at least the operating class / band / channel) of the dedicated per-STA profile, in addition to per-STA profiles for other requested APs. The per-STA profile, with reference to FIG. 5b, includes an off-link subfield 560 and / or a Usage Mode subfield 561. In another embodiment, the virtual AP identity and information related to Usage are included in a Reduced Neighbor Report element as described in FIGS. 9a and 9b.In the different variants mentioned above, the Usage mode is set to a value that restricts the use to P2P communication (for example, the value 3 in FIG. 6a).

[0269] Upon receiving the Probe Response frame 813, the non-AP MLD 120 may attempt to associate with the AP MLD 110. The non-AP MLD 120 sends an Association Request frame 214 via STA A1 111, containing a Multi-Link element with a per-STA profile for each link (corresponding to each AP belonging to the AP MLD) requested by the non-AP MLD for association. The virtual AP may be added as a requested AP in the per-STA profile to inform the AP MLD that the non-AP MLD will use an off-link.

[0270] If the AP MLD agrees to the Association request, the AP MLD 110 responds to the non-AP MLD 120 with an Association Response frame 215. The Association Response frame includes a per-STA profile for each link corresponding to each AP belonging to the AP MLD that accepts the association. Links corresponding to virtual APs shall always be accepted.

[0271] If the off-link is dedicated to P2P communication, the non-AP MLD 120 may decide to establish a TDLS setup targeting this off-link, which follows the procedure 220 described with reference to Figure 2a.

[0272] The TDLS initiator STA A1 121 performs TDLS discovery and TDLS setup with the TDLS responder STA B1 131 via AP1 111. Each of the TDLS discovery and setup frames includes a link identifier 400. The TDLS initiator STA Address field 402 carried in the link identifier is set to the MLD MAC address of the non-AP MLD 120, the TDLS responder STA Address field 403 is set to the MLD MAC address of the non-AP MLD 130, and the BSSID field 401 is set using the BSSID corresponding to off-link.

[0273] In another variant, off-links can be added to the per-STA profile carried in the TDLS Multi-Link element. The Multi-Link element sent by the TDLS initiator non-AP MLD in a TDLS Discovery Request frame 221 informs the peer non-AP MLD on which links the TDLS can be discovered. In response, the Multi-Link element sent by the TDLS responder non-AP MLD in a TDLS Discovery Response frame 222 informs the TDLS initiator non-AP MLD on which links it can operate.

[0274] In a TDSL Setup Request frame 223, the TDLS initiator non-AP MLD 120 sends a Multi-Link element via STA A1 121 to inform the peer non-AP MLD 130 on which of one or more links the TDLS session has been successfully established. In response, in a TDLS Setup Response frame 224, the TDLS responder non-AP MLD 130 sends a Multi-Link element via its affiliated station STA B1 131 to inform the TDLS initiator non-AP MLD on which of one or more links the TDLS session will be effectively established, i.e., the accepted link. In a TDSL Setup Confirm frame 225, the TDLS initiator non-AP MLD 120 sends a Multi-Link element via STA A1 121 to inform the peer non-AP MLD 130 on which of one or more links the TDLS session will be established.

[0275] In another variation, the TDLS setup frame includes a Multi-Link Link Information element 490 that includes a Link ID Bitmap 491. This Link ID Bitmap 491 indicates the target link of the TDLS setup when the Multi-Link Link Information element 490 is sent in the TDLS Setup Request frame 223, and the Link ID Bitmap 491 indicates the accepted link when the Multi-Link Link Information element 490 is sent in the TDLS Setup Response frame 224. One bit in the Link ID Bitmap may correspond to an off-link in the present invention.

[0276] Then, once the TDLS session is established, the peer non-AP MLDs may communicate P2P data traffic 226 directly with their respective affiliated stations (STA A3 123 belonging to non-AP MLD 120 and STA B3 133 belonging to non-AP MLD 130, respectively) over off-link 173. Each non-AP MLD may continue operation with the AP MLD using one or more other setup links.

[0277] FIG. 8b illustrates the scenario of FIGS. 2 and 2A with frame exchanges in a timeline when a non-AP MLD already associated with an AP MLD requests the creation of an off-link for P2P traffic through a Channel Usage Request frame.

[0278] In this example, no off-link is created or used during association with the AP MLD. The non-AP MLD 120 requests the AP MLD 110 to create a P2P off-link, for example, to meet the needs of a new application.

[0279] The non-AP MLD 120 sends a Channel Usage Request frame 815 to the AP MLD 110 via STA A1 121.

[0280] The Channel Usage Request frame will be described with reference to Fig. 6c. It mainly includes a Channel Usage Element field 681 and a Supported Operating Classes Element field 682. The WNM field 680 defines the type of the frame, i.e., the Channel Usage Request frame.

[0281] The Channel Usage Element field contains one or more Channel Usage elements to identify the requested Usage Mode. Channel Usage elements are described in Figures 6, 6a, and 6b. The Channel Usage element contains a link ID Info field (650 in Figure 6a or 643 in Figure 6b). The link ID Info subfield is set to a wildcard value that requests off-link allocation from the AP MLD.

[0282] The Supported Operating Classes Element field contains a Supported Operating Classes element that indicates the operating classes supported in the requested network type that match the Country element advertised by the AP.

[0283] Alternatively, frame 815 may be a new off-link Creation Request frame with the same elements but without the link ID field of the Channel Usage element, identified by a new value in the NWM field (WNM Action field value set to 28).

[0284] In the example of FIG. 8b, upon receiving the Channel Usage Request frame 815, the AP MLD performs steps 720 and 730 to create an off-link dedicated to P2P communication. The AP MLD 110 then responds to the non-AP MLD 120 via AP1 111 with a Channel Usage Response frame 816. The Channel Usage Response frame, like the Channel Usage Request frame, includes the NWM field 680 and the Channel Usage Element field 681. The Channel Usage element includes the link ID associated with the virtual AP instantiated to create the off-link (step 720 if the AP MLD supports the virtual AP or off-link functionality). The operating band assigned to the off-link depends on the Supported Operating Classes collected from the non-AP MLD and the operating frequency band currently used by the AP MLD. Note that the off-channel does not overlap with the channel used by the access point. Furthermore, the AP MLD may consider some non-simultaneous transmit and receive constraints. The other fields are beyond the scope of this invention.

[0285] In a variant, frame 816 may be a new off-link Creation Response frame having the same elements as the Channel Usage Response frame and identified by a new value of the NWM field (WNM Action field value set to 29).

[0286] Once an off-link is created by the AP MLD 120, the AP MLD 120 may advertise all surrounding stations by including the virtual AP / off-link characteristics in a Beacon frame 211. The Beacon frame 211 includes variations based on the Reduced Neighbor Report element and the Multi-Link element described in the previous figures.

[0287] The rest of the frame exchange is similar to that described in FIG.

[0288] Figure 8c illustrates the scenarios of Figures 2 and 2a using a timeline frame exchange when a non-AP MLD that is already associated with an AP MLD (an association that includes off-link as described in Figure 8 by procedure 820) performs TDLS setup on a link shared with the AP and moves off-link using a TDLS channel switch. This figure is related to the 802.11 network environment of Figure 7b, where the non-AP MLD has two affiliated STAs, one dedicated to P2P communication and the other dedicated to communication with the AP MLD.

[0289] The procedure 820 corresponding to multi-link setup with the AP MLD including the off-link in the Multi-Link element encompasses steps 812, 813, 214, and 215 described in Figure 8. This procedure is performed between the non-AP MLD 120 and the AP MLD 110, and also between the non-AP MLD 130 and the AP MLD 110. As a result, the non-AP MLD 120 and the non-AP MLD 130 are associated with the AP MLD 110 and have knowledge of the off-link dedicated to P2P communication.

[0290] The TDLS initiator STA A2 122 performs TDLS discovery and TDLS setup with the TDLS responder STA B2 132 via AP2 112. Each TDLS discovery and setup frame includes a link identifier 400. The TDLS initiator STA Address field 402 carried in the Link Identifier is set with the MLD MAC address of the non-AP MLD 120, and the TDLS responder STA Address field 403 is set with the MLD MAC address of the non-AP MLD 130, but contrary to Figure 8, the BSSID field 401 is set with the BSSID corresponding to a normal AP (not a virtual AP) operating on the base channel. This AP is associated with the STA (AP2 in this example) that will be used for further P2P communication. The TDLS setup frame shares a Supported Channel element between both TDLS peer STAs to confirm that they support the off-channel for off-link operation.

[0291] Next, the TDLS initiator STA A2 sends a TDLS Channel Switch Request frame 231 to move the P2P communication to the offlink. The TDLS Channel Switch Request includes the link identifier 400 defined in the TDLS setup, the target channel and its operating class, and the timing information for the channel switch. The target channel corresponds to the offlink operating channel (i.e., the off-channel). The off-link channel used as the target channel may be the off-link base channel, the off-link primary channel, or one of the channels in the channel entry (Channel Usage element) corresponding to the offlink. The target partner STA B2 responds with a TDLS Channel Switch Response frame 232 with the link identifier and a status code set to SUCCESS (if it agrees to switch to the target channel), after which both peer STAs switch (from the base channel) to the target channel. If the TDLS Channel Switch Response frame 232 contains a STATUS code different from SUCCESS, both STAs continue operating on the current base channel.

[0292] We now describe some variations in which the channel switch indicates a target link instead of a target channel.

[0293] In the first variant, the non-AP MLD infers that this is a link switch because the target channel corresponds to an off-link created by the AP MLD.

[0294] In a second variant, similar to the setup, a link identifier included in the channel switch is used to indicate the target link through its BSSID. Thus, the BSSID field 401 of the link identifier 400 is set to the BSSID of the virtual AP corresponding to the off-link. Furthermore, the TDLS initiator STA Address field 402 and the TDLS responder STA Address field 403 can be set to the addresses of the STAs involved in the switch (instead of the addresses of the MLD). In the example of Fig. 8c, the TDLS initiator STA Address field is set to the address of STA A2 122, the TDLS responder STA Address field is set to the address of STA B2 132, and the BSSID field is set to the BSSID of AP3 113 corresponding to the off-link.

[0295] In the third modification, a Link ID field is added to the Channel Switch Request / Response frame.

[0296] The first and second variants can maintain existing signaling.

[0297] To avoid the obligation to switch back to the base channel, the non-AP MLD 120 and the non-AP MLD 130 must disable or delete the link (referred to as the "previous link") previously used by AP2 112 to communicate with STA A2 122 and STA B2 132. This can be done by updating the TID-to-LINK mapping by deleting all TIDs from the previous link and thereby disabling the previous link, or by removing the previous link from one or more setup links through multilink (re)setup between the AP MLD 110 and the non-AP MLD 120 and the non-AP MLD 130. This procedure of link deletion or disabling is indicated by arrow 850 in the figure. In the illustrated example, the link deletion / disabling is performed after the TDLS channel switch, so the message corresponding to this procedure is sent through STA A1 121 and STA B1 131. Alternatively, STA A2 and STA B2 may send this message before performing the TDLS channel switch.

[0298] As a result, after the deletion / disabling of the previous link, both STAs (STA A2 and STA B2) are dedicated to P2P communication and can perform direct link communication off-link without having to switch back to the base channel.

[0299] Relying on a virtual AP involves additional processing for AP MLDs, such as additional signaling in management frames. Other mechanisms are given below. In these mechanisms, one of the (peer) non-AP MLDs creates a TDLS link with its own link ID, which defines an off-link corresponding to at least one off-channel that does not overlap with the channels used by the AP device. Then, that TDLS link (i.e., link ID) can be used to establish a TDLS direct link between the non-AP MLDs using conventional TDLS mechanisms.

[0300] The AP MLD is advantageously not involved in the creation process. To efficiently select one or more off-channels that do not affect the operation of the AP MLD, the non-AP MLD may obtain recommended channels from the AP MLD that are not infrastructure BSS or off-channel TDLS direct links. One or more off-channels that define the off-link are then selected from the recommended channels.

[0301] A first embodiment will be described with reference to Figures 11a to 11d. In these embodiments, a TDLS link is created by exchanging TDLS action frames with another (peer) non-AP MLD. Such frames may be TDLS action frames, which are new compared to the D2.2 standard. As TDLS action frames, they are tunneled by the AP device, and off-links are created simultaneously in both (peer) non-AP MLDs.

[0302] Next, the establishment of a TDLS direct link between two non-AP MLDs simply involves performing a TDLS direct link establishment targeting the created off-link. Conventional TDLS direct link establishment is defined in Section 11.20.4 of IEEE P802.11-REVme / D2.0. This involves exchanging TDLS Setup Request / Response frames as described above with reference to Figure 2a, where these frames include the MAC address of the affiliated peer STA associated with the created off-link (e.g., in Link Identifier IE400).

[0303] 11a illustrates an 802.11 network environment including a non-AP multi-radio device MLD associated with an AP device, in which an embodiment of the present invention may be implemented. The illustrated example shows two non-AP MLDs (non-AP MLD A 120 and non-AP MLD B 130) with two affiliated STAs (121-122 and 131-132, respectively), and an AP MLD 1101 with only one affiliated AP 111. In another embodiment, the AP 1101 may be a legacy AP, i.e., an AP without multi-link capabilities. Each non-AP MLD has set up a link with the AP device, where STA A1 121 has set up link 151 with AP1 111, and STA B1 131 has set up link 161 with AP1 111.

[0304] The non-AP MLD 120 and the non-AP MLD 130 instantiate or create a TDLS link on a set of off-channels (that do not overlap with the AP device's operating channels) to obtain an off-link 172 for operation outside of AP management. The created TDLS link or off-link 172 is set up at an affiliated station other than the sender, here STA A2 122 of the non-AP MLD A 120 and STA B2 132 of the non-AP MLD B 130.

[0305] Typically, this off-link is used for TDLS communication, which means that non-AP MLD 120 and non-AP MLD 130 establish a TDLS session (TDLS direct link) over off-link 172 by exchanging TDLS action frames via affiliated stations STA A1 121 and STA B1 131, where the frames are tunneled by AP1 111.

[0306] As a result, non-AP MLD 120 and non-AP MLD 130 can use off-link 172 with one of the affiliated stations while maintaining their previous connection with the AP device through the initial link corresponding to their connection with AP1 111.

[0307] Of course, the number of links shown for illustrative purposes is not limiting.

[0308] 11b illustrates, by means of a flowchart, exemplary steps of direct communication according to a particular embodiment of the present invention, which are performed by a (peer) non-AP MLD initiating the creation or instantiation of a TDLS link (off-link) on a set of off-channels.

[0309] The operation begins in step 1210, where the non-AP MLD of the TDLS initiator obtains a recommended channel that is not an infrastructure BSS or an off-channel TDLS direct link from an AP device. For example, it may receive Channel Usage information from AP1, as described above with reference to FIG. 6.

[0310] The Channel Usage information can be carried either in a Probe Response frame exchanged during the association procedure with the AP MLD, or in a Channel Usage Response frame exchanged with the AP MLD after the non-AP MLD (its affiliated STAs) has associated with the AP MLD. The Channel Usage information is provided by the AP MLD to the TDLS initiator's non-AP MLD to recommend a channel for a BSS that is not an infrastructure BSS or an off-channel TDLS direct link. The non-AP MLD can use the Channel Usage information as part of the channel selection process for a BSS that is not an infrastructure BSS or an off-channel TDLS direct link (4.3.21.4 Channel usage in REVme2.0 (October 2022)). In other words, the Channel Usage information provides the TDLS initiator non-AP MLD with a channel that does not overlap with the AP MLD's operating channel.

[0311] 11c illustrates the creation and use of an off-link in accordance with an embodiment of the present invention using a frame exchange in a timeline, where Channel Usage information is obtained from a Probe Response frame. This figure is based on the scenario of FIG. 11a, where STA A1 121 and STA B1 131 register with AP1 111.

[0312] At the start of the frame exchange, STA A1 121, which belongs to the non-AP MLD 120, is not associated with an AP or AP MLD. In the context of discovery, STA A1 121 transmits a Probe Request frame 212 containing its STA capabilities. Of interest to the present scenario, the Probe Request frame 212 contains a Supported Operating Classes element (order 6 in the Probe Request frame body) and a Channel Usage element (order 11 in the Probe Request frame body).

[0313] The Supported Operating Classes element advertises the operating classes that the non-AP MLD is currently configured to operate in. The Usage Mode carried in the Channel Usage element advertises the usage that the non-AP MLD wishes to perform off-channel.

[0314] In some embodiments, the Probe Request frame 212 is the Multi-Link version (802.11be), meaning that it also includes a Multi-Link element (defined in section 9.4.2.312.1 of the D2.2 standard) that is used to request additional information from the AP MLD. If no per-STA profile is present in the Multi-Link element, the AP MLD includes information about all affiliated APs (in the Probe Response frame); otherwise, the AP MLD advertises non-AP MLD only in per-STA profiles with Link IDs equal to the value in the link ID field included in the per-STA profile carried in the Multi-Link element of the Probe Request frame.

[0315] In another embodiment, the Supported Operating Classes may be carried in a per-STA profile included in the Multi-link element for each STA belonging to a non-AP MLD to advertise the operating class in which each STA is currently configured to operate.

[0316] In yet another embodiment, the non-AP MLD uses the Multi-band element (order 14 in the Probe Request frame body) to advertise to the AP MLD about Supported Operating Classes over different frequency bands. In effect, the Multi-band element indicates that the STA transmitting this element (the transmitting STA) is in a multi-band device capable of operating in frequency bands or operating classes or channels other than the one in which this element (Probe Request frame 212) is transmitted.

[0317] The AP MLD 1101 responds to the transmitting STA A1 121 through its affiliated AP1 111 with a Probe Response frame 213. The Probe Response frame 213 includes one or more Channel Usage elements, as described above, that provide recommended channels (a set of channels for operation in a non-infrastructure network or an off-channel TDLS direct link) that do not overlap with one or more channels used by the AP MLD.

[0318] Upon receiving the Probe Response frame 213, the non-AP MLD 120 requests association with the AP MLD (via affiliated AP1 111). To do so, the non-AP MLD 120 transmits an Association Request frame 214 via STA A1 111. The Association Request frame 214 includes a Multi-Link element with a per-STA profile for each link (corresponding to each AP belonging to the AP MLD) with which the non-AP MLD requests association. Of course, if the AP 1101 is a legacy AP without multi-link capabilities, such a Multi-Link element is not included in the Association Request frame 214.

[0319] If the AP MLD agrees to the Association request, AP1 111 responds to the non-AP MLD 120 with an Association Response frame 215, which includes a per-STA profile for each link corresponding to each AP belonging to the AP MLD for which association was accepted (only if the AP is an MLD AP).

[0320] 11d is a diagram illustrating the creation and use of an off-link according to another embodiment of the present invention using a frame exchange in a timeline, where Channel Usage information is obtained from a Channel Usage Response frame exchanged with an AP MLD when a non-AP MLD (its affiliated STA) associates with the AP MLD. This diagram is based on the scenario of FIG. 11A where STA A1 121 and STA B 131 are registered with AP1 111.

[0321] A non-AP STA that supports Channel Usage may transmit a Channel Usage Request frame any time after associating with an AP that supports the use of Channel Usage to request Channel Usage information for the supported operating classes.

[0322] In this example, non-AP MLD 120 and non-AP MLD 130 are already associated with AP 1101. Therefore, non-AP MLD 120 requests Channel Usage information from the AP MLD by sending a Channel Usage Request frame 815. The AP MLD responds with a Channel Usage Response frame 816 that includes the Channel Usage information.

[0323] Returning to Figure 11b, optionally, in step 1220, the TDLS initiator's non-AP MLD performs a TDLS discovery procedure (as already described above) to obtain information about one or more channels and bands supported by its peer non-AP MLD. This step includes sending a TDLS Discovery Request frame 221 and receiving a TDLS Discovery Response frame 222, as already described above with reference to Figure 2a.

[0324] This optional step is illustrated in the scenarios of Figures 11c and 11d.

[0325] When attempting to discover TDLS stations within the same BSS, a series of frame exchanges is used.

[0326] The initiator STA A1 transmits a TDLS Discovery Request frame 221 to an individual destination station (here, peer STA B1), tunneled (relayed as indicated by the black dot) through AP1 111. The TDLS Discovery Request frame includes a Link Identifier element 400 as shown in FIG. 4a, and may also include a Multi-band element as defined above to indicate that the STA transmitting this element is in a multi-band device capable of operating in a frequency band, operating class, or channel other than the one in which this element is transmitted. Furthermore, the STA announces the role (e.g., TDLS STA) that the transmitting STA plays on the channel of the operating class indicated in the Multi-band element. This Multi-band element allows the initiator STA to announce its channel capabilities to the receiving STA. Finally, the TDLS Discovery Request frame may include a TDLS Multi-Link element 450 as shown in FIG. 4b, for example, to convey the per-STA profile of each STA of the TDLS initiator's non-AP MLD (here, non-AP MLD A 120) and to inform about the channel capabilities supported by the non-AP MLD.

[0327] The peer STA B1 responds to the TDLS Discovery Request frame 221 with a TDLS Discovery Response frame 222 that is sent directly to STA A1 (without relaying through the AP 111). This response frame carries the Link Identifier element 400 and the TDLS Multi-Link element 450 among the IEs in the Elements field 303. Additionally, the TDLS Discovery Response frame may include supported channel and Multi-band elements to inform the TDLS initiator's non-AP MLD through its affiliated STAs about the channels and bands that the peer non-AP MLD supports.

[0328] From this point on, STA A1 and STA B1 know each other, which means they know that the other is operating in a communication link set up with AP 111. Also, from an MLD perspective, both non-AP MLD 120 and non-AP MLD 130 know the other's supported channels.

[0329] Next, in step 1230, based on the recommended channels collected from the AP MLD, and optionally based on the supported channels / bands collected from the peer non-AP MLD and its own supported channels / bands, the non-AP MLD of the TDLS initiator selects one or more channels as off-channels, which means that the non-AP MLD selects one or more recommended channels that follow its own supported channels / bands and the supported channels / bands of the peer non-AP MLD.

[0330] The selected channel or channels may be in the same band as the AP MLD operating band, or in a different band.

[0331] Then, a TDLS link targeting the selected set of off-channels is created by exchanging TDLS action frames tunneled by the AP MLD with the peer non-AP MLD, thus creating off-links for TDLS communication in both peer non-AP MLDs simultaneously.

[0332] In the following, a new type of TDLS action frame, referred to below as a TDLS Link Setup Request frame, a corresponding TDLS Link Setup Response frame, and a TDLS Link Setup Confirm frame, may be used in the same manner as the TDLS Setup frame. Of course, the TDLS Setup frame may also be upgraded to carry the signaling required by the TDLS Link Setup frame described here (rather than creating a new frame).

[0333] The TDLS Link Setup Request frame may be assigned a value of 11 in the Action field 302 , the TDLS Link Setup Response frame may be assigned a value of 12 in the Action field 302 , and the TDLS Link Setup Confirm frame may be assigned a value of 13 in the Action field 302 .

[0334] For example, the non-AP MLD of the TDLS initiator initiates the creation of a TDLS off-link by sending a TDLS Link Setup Request frame to the peer non-AP STA, which includes a link identifier and the operating band of this new link, i.e., the selected off-channel or channels.

[0335] The TDLS Link Setup Request frame is A Target Channel element (as defined in 9.4.1.35 (Target Channel) of REVme2.0) to specify the channel number of the selected off-channel for the off-link to be created; An Operating Class element (as defined in 9.4.1.36 (Operating Class) of REVme2.0) to specify the operating band of the off-link to be created; A link ID, i.e., a number that identifies the off-link to be created in the future. A Link ID element such as element 523 in FIG. 5a1 can be used; and It may be a TDLS action frame including:

[0336] A link ID (hereinafter also referred to as a TDLS link ID) is selected by the non-AP MLD of the TDLS initiator. Preferably, the TDLS link ID defining the off-link is selected from a set of candidate link IDs excluding the link ID used by the AP MLD. This is to avoid conflicts.

[0337] For example, the value of the TDLS link ID is outside the range of values managed by the AP MLD (i.e., a value greater than 15). In fact, as a result, the TDLS link ID may be compatible with the link ID managed by the AP.

[0338] As a variant, the TDLS Link Setup Request frame may include a Link Identifier element (as shown in FIG. 4a) for conveying a link ID. For example, the TDLS initiator's non-AP MLD may specify therein the MAC address of the affiliated STA (STA A2 in the example of FIG. 11a) that intends to operate on the off-link. In particular, this MAC address is included in the BSSID field 401 to identify the target link, i.e., the off-link to be created. In that case, the off-link is assigned a BSSID (Basic Service Set Identifier) set to the MAC address of the affiliated STA (here, STA A2) involved in the TDLS initiator's non-AP MLD. In a variant, the BSSID of the off-link may be set to the MAC address of the TDLS initiator's non-AP MLD.

[0339] The MAC address may be used as a single identification off-link, or alternatively, in combination with the aforementioned link ID specified in element 523.

[0340] In some embodiments where a TDLS initiator intends to declare multiple off-links to a non-AP MLD, the TDLS Link Setup Request frame may include a Multi-link element with multiple per-STA profiles, each carrying a target channel, operating class, and link identifier for the corresponding off-link to be created. This allows multiple off-links to be created with a peer non-AP STA through a single procedure (a single exchange of TDLS Link Setup Request / Response and Confirm frames).

[0341] In response, the non-AP MLD of the TDLS initiator receives a TDLS Link Setup Response frame intended to confirm the creation of the off-link using a dedicated code.

[0342] The TDLS Link Setup Response frame has the same format as the TDLS Link Setup Request frame and may additionally have a response code.

[0343] The TDLS Link Setup Response frame may reject the creation of the off-link (or multiple off-links) if a reject code is carried.

[0344] In some embodiments, the TDLS Link Setup Response frame includes an alternative off-link (or multiple off-links using a Multi-Link element) corresponding to at least one alternative off-channel that does not overlap with the channel used by the AP device. This means that a peer non-AP MLD that does not accept the proposed off-link will make another proposal. Thus, off-link negotiation occurs.

[0345] Alternative off-links may be defined on different operating bands / channels.

[0346] The negotiation continues as follows:

[0347] If multiple alternative off-channels are proposed, the non-AP MLD of the TDLS initiator may select one of them as the new target channel.

[0348] The TDLS initiator's non-AP MLD then starts the TDLS off-link creation procedure again (sending a TDLS Link Setup Request frame) using the new target channel advised by the peer non-AP MLD if the initiator agrees. In a variant, the TDLS Link Setup Confirm frame described below can be used to confirm the TDLS link creation using alternative parameters (mainly one or more operating channels) provided by the peer non-AP MLD through a TDLS Link Setup Response frame.

[0349] Of course, the TDLS Link Setup Response frame may simply be a denial without suggesting an alternative off-link.

[0350] Finally, if the link proposed in the TDLS Link Setup Request frame is accepted by the peer non-AP MLD, the TDLS Link Setup Response frame accepts the creation of the off-link (or multiple off-links) along with an acceptance code.

[0351] Then, a TDLS Link Setup Confirm frame can be sent by the non-AP MLD of the TDLS initiator to confirm the creation of the off-link.

[0352] Note that whenever an off-link is created, the TDLS initiator's non-AP MLD (and / or peer non-AP MLD) may inform the AP MLD about the created link ID and the created off-link, which may be done by using the reserved bit 523b in subsequent frames that include the Link ID Info field 523.

[0353] The off-link creation is illustrated in the same manner as in Figures 11c and 11d, where the TDLS Link Setup Request frame is shown under reference number 1301, the TDLS Link Setup Response frame is shown under reference number 1302, and the TDLS Link Setup Confirm frame is shown under reference number 1303.

[0354] In detail, the TDLS initiator non-AP MLD A120 transmits a TDLS Link Setup Request frame 1301 to the peer non-AP MLD B130 via its affiliated STA B1 131 via its affiliated STA A1 121 over an existing link with the AP MLD (here, AP1 111). This frame includes the target operating band and channel on which the link must be established, a link identifier for identifying the TDLS link or off-link to be created, and the MAC address of STA A2 122 belonging to the non-AP MLD used to operate on the off-link. This MAC address can be used instead of the off-link BSSID.

[0355] In response to the TDLS Link Setup Request frame 1301, the peer non-AP MLD responds to the initiator's non-AP MLD through its affiliated STA B1 131 with a TDLS Link Setup Response frame 1302. This frame includes the TDLS link ID received through frame 1301 as well as a status code (accepted or rejected) to indicate whether the link creation is accepted. In the case of a link creation rejection, STA B1 131 adds one or more alternative bands and / or channels to the response frame 1302.

[0356] If frames 1301 and 1302 contain a Multi-Link element with one or more per-STA profiles, link-level authorization can be performed. Each STA profile carried in a TDLS Link Setup Request frame targets one different TDLS link or off-link to be created. And in response, each STA profile carried in a TDLS Link Setup Response frame corresponds to a TDLS link accepted by a peer non-AP STA. Other TDLS links are rejected.

[0357] Finally, the non-AP MLD of the TDLS initiator sends a TDLS Link Setup Confirm frame 1303 via its affiliated STA A1 121 to acknowledge receipt of the TDLS Link Setup Response frame 1302. The TDLS Link Setup Confirm frame 1303 conveys the link ID of the created off-link.

[0358] The TDLS Link Setup Confirm frame allows sharing of MAC addresses of STAs belonging to initiator non-AP MLDs operating on different created off-links (in the Multi-Link element, if any).

[0359] As a result, a TDLS link, i.e., an off-link, is created.

[0360] Once the off-link is created, the TDLS initiator's non-AP MLD initiates TDLS direct link establishment in step 1240 to set up a TDLS direct link with a second non-AP MLD that targets the off-link. This may be done using conventional TDLS Setup frames 223, 224, 225, where each TDLS Setup frame includes a Link Identifier 400 whose BSSID field 401 is set to the MAC address of a STA belonging to the initiator's non-AP MLD operating on the target link. This is to indicate which off-link is the target of the TDLS setup. In some embodiments, a TDLS Peer Key (TPK) security protocol is derived based on the BSSID included in the Link Identifier that corresponds to the MAC address of a STA (STA A2 in the example of FIG. 11a) belonging to the TDLS initiator's non-AP MLD that intends to operate on the off-link.

[0361] In a variant of signaling off-link in the BSSID field 401, the target off-link may be specified in the per-STA profile transmitted in the TDLS Multi-Link element 450. The Multi-Link element sent by the TDLS initiator non-AP MLD in the TDLS Setup Request frame 223 informs the peer non-AP MLD on which link the TDLS can be established. In response, the Multi-Link element received by the TDLS initiator non-AP MLD from the peer non-AP MLD in the TDLS Setup Response frame 224 informs the TDLS initiator non-AP MLD on which link the TDLS session will effectively be established, i.e., the accepted off-link. In this variant, the BSSID field 401 may be set to the MAC address of the BSSID corresponding to the BSS of which the TDLS initiator non-AP MLD is a member, i.e., the MAC address of the AP 111 or AP MLD 1101. If a TDLS session is established across multiple links (off-link only, or multiple classic direct links (with a shared operating band with the AP), or a mix of classic and off-link), the TDLS peers may create unique group TPK keys for the multiple links. Since each affiliated STA in the MLD uses a different MAC address, the key creation process may be adapted. Several variations are envisioned.

[0362] (1) The TDLS PeerKey (TPK) security protocol can be derived based on the BSSIDs of all links set up by the TDLS setup procedure. These BSSIDs can be obtained from the per-STA profile of the Multi-Link element. These BSSIDs correspond to the MAC addresses of the APs for classic links and to the addresses of the TDLS STAs (initiators or responders) for off-links. If the frames sent during the TPK handshake by both peers contain the TDLS Multi-Link element and the setup is multiple links including off-links, the TPK is derived as follows: TPK = KDF-Hash-Length(TPK-Key-Input, “TDLS PMK”, min (MAC_I, MAC_R) || max (MAC_I, MAC_R) || BSSID1 || BSSID2 ||… BSSIDn || AP MLD MAC) where TPK-Key-Input is derived from the hash algorithm and KDF-Hash-Length is the key derivation function as defined in section 12.7.1.6.2 of REVme D2.0.

[0363] MAC_I and MAC_R are the MAC addresses of the TDLS initiator STA and the TDLS responder STA, respectively. The n listed BSSIDs are set to the BSSIDs of the BSSs of which the TDLS initiator STA is a member, The AP MLD MAC is the MLD MAC address of the AP MLD that the initiating non-AP MLD performed multi-link setup.

[0364] If the number of links in a TDLS session changes, the TDLS peers may decide to use the current TPK for its entire (limited) validity period, and at the end of the validity period, update the TPK to take into account the new (changed) set of links and associated BSSIDs.

[0365] (2) In a variant, the TDLS PeerKey (TPK) can be derived based on the BSSID of one side of the link, a wildcard BSSID, or a BSSID corresponding to a BSS of which the TDLS initiator's non-AP MLD is a member, i.e., the MAC address of the AP 111 or AP MLD 1101. The TPK is derived as follows: TPK = KDF-Hash-Length(TPK-Key-Input, “TDLS PMK”, min (MAC_I, MAC_R) || max (MAC_I, MAC_R) || BSSID || AP MLD MAC) Here, in addition to the above parameters defined above, The BSSID is the BSSID of the BSS of which the TDLS initiator STA is a member.

[0366] (3) In another variation, the TDLS PeerKey (TPK) can be derived based on the MAC addresses of the non-AP MLD and AP MLD without considering the BSSID corresponding to the link used. The TPK can be derived as follows: TPK = KDF-Hash-Length(TPK-Key-Input, “TDLS PMK”, min (MLD MAC_I, MLD MAC_R) || max (MLD MAC_I, MLD MAC_R) || AP MLD MAC) Here, in addition to the above parameters defined above, MLD MAC_I and MLD MAC_R are the MLD MAC addresses of the MLD STA of the (non-AP) TDLS initiator and the MLD STA of the (non-AP) TDLS responder, respectively.

[0367] (4) In yet another variation, when a non-AP MLD is associated with a legacy AP (e.g., AP 111 in the example of FIG. 11a), a TDLS PeerKey (TPK) may be derived based on the MAC address of the non-AP MLD and the BSSID of the BSS of which the TDLS initiator's STA is a member. The TPK may be derived as follows: TPK = KDF-Hash-Length(TPK-Key-Input, “TDLS PMK”, min (MLD MAC_I, MLD MAC_R) || max (MLD MAC_I, MLD MAC_R) || BSSID)

[0368] Variations (2), (3) and (4) advantageously allow the number of links in a TDLS session to be changed without changing the TPK.

[0369] Any combination of TPK variations may be envisioned.

[0370] In another variation on the off-link signaling described above, the TDLS Setup frame includes a Multi-Link Link element 490 that includes a Link ID Bitmap 491, where each bit in the Link ID Bitmap 491 corresponds to a previously created off-link. The Link ID Bitmap 491 in the TDLS Setup Request frame 223 indicates the target off-link for the TDLS setup, and the Link ID Bitmap 491 in the TDLS Setup Response frame 224 indicates the accepted off-link.

[0371] The setup of the TDLS direct link based on the off-link is similarly shown in Figure 11c and Figure 11d.

[0372] The TDLS initiator STA A1 121 performs TDLS setup with the peer STA B1 131 via AP1 111. Each TDLS Setup frame includes a Link Identifier 400. The TDLS initiator STA Address field 402 included in the Link Identifier is set to the MLD MAC address of the non-AP MLD 120, the TDLS responder STA Address field 403 is set to the MLD MAC address of the non-AP MLD 130, and the BSSID field 401 is set to the MAC address of STA A2 122, which is a STA belonging to the TDLS initiator's non-AP MLD A operating off-link of the target. The MAC address of STA A2 122, which is used as the BSSID, is collected by the peer non-AP MLD B through a TDLS Link Setup Request or Confirm frame according to the embodiment.

[0373] As mentioned above, in a variant, it may be considered to signal the target off-link in the per-STA profile transmitted in the TDLS Multi-Link element 450 or via the Link ID Bitmap 491 provided in the Multi-Link Link Information element 490.

[0374] As a result, if the TDLS direct link establishment is successful in step 1250, STA A2 122 and STA B2 132 (TDLS peer STAs) belonging to the TDLS peer non-AP MLDs 120 and 130, respectively, can communicate directly (P2P) via the set-up off-link. Thus, P2P data traffic 226 is exchanged directly between the two TDLS peer STAs, as shown in Figures 11c and 11d. Advantageously, each TDLS peer's non-AP MLDs A and B can continue operation with AP1 111 via the other set-up links (here, link 151 via STA A1 121 of non-AP MLD A 120 and link 161 via STA B1 131 of non-AP MLD B 130).

[0375] A second embodiment will be described with reference to Figures 12a to 12d. In these embodiments, a first TDLS direct link is established between two non-AP MLDs over a first link set up with an AP device. Then, the first TDLS session is switched to an off-link. In this way, a TDLS session on the off-link is established by the switch.

[0376] The first link initially supporting the first TDLS session may then be removed or disabled to remove the activity of the affiliated STA (now engaged in off-link) with the AP device.

[0377] 12a illustrates an 802.11 network environment including a multi-radio device MLD, such as that of FIG. 1, in which embodiments of the present invention may be implemented. In the illustrated example, two non-AP MLDs (non-AP MLD A 120 and non-AP MLD B 130) are shown with two affiliated STAs (121-122 and 131-132, respectively), and the AP MLD 110 is shown with two affiliated APs 111 and 112. Both non-AP MLDs associated with the AP MLD 110 initially set up a TDLS direct link session 172a with AP2 112 on the same operating band, i.e., link #2.

[0378] The non-AP MLDs 120 and 130 instantiate or create a TDLS link on a set of one or more off-channels to obtain an off-link 172b for operation outside of AP management. The non-AP MLD then moves the TDLS session from link 172a operating on the same channel / band as AP2 112 to off-link 172b that is not on the operating channel / band of one or more APs belonging to the AP MLD 110. The non-AP MLDs then may delete their own connections to AP2 112 via links 152 and 162, respectively.

[0379] As a result, the non-AP MLDs 120 and 130 can use the off-link 172b with one of the affiliated stations (STA A2 122 and STA B2 132, respectively) while maintaining their previous connection with the AP MLD via link #1, which corresponds to their connection with affiliated AP1.

[0380] Of course, for purposes of illustration, the number of links shown in this diagram is not limiting.

[0381] Figure 12b illustrates, using a flowchart, exemplary steps for direct communication according to a specific embodiment of the present invention. These steps are performed by a (peer) non-AP MLD initiating a TDLS link (off-link) over a set of off-channels. This process includes similar steps to Figure 11b, as described below.

[0382] The operation begins in step 1510, where the non-AP MLD of the TDLS initiator obtains a recommended channel from the AP device that is not an infrastructure BSS or an off-channel TDLS direct link. Step 1510 is similar to step 1210 described above.

[0383] 12c and 12d illustrate two different scenarios for creating and using an off-link according to an embodiment of the present invention, using frame exchanges in a timeline. In both scenarios, when a non-AP MLD (its affiliated STAs) associates with an AP MLD, it obtains Channel Usage information from a Channel Usage Response frame 816 exchanged with the AP MLD. Of course, Channel Usage information may alternatively be obtained from a Probe Response frame.

[0384] Optionally, in step 1520, the non-AP MLD of the TDLS initiator performs a TDLS discovery procedure to obtain information about the channels and bands supported by the peer non-AP MLD and its capabilities. Step 1520 is similar to step 1220 already described.

[0385] This is shown schematically in Figure 12d, while it is omitted in Figure 12c but can also be implemented in this scenario. Each TDLS Discovery frame 221, 222 includes a Link Identifier 400 with the TDLS initiator STA Address field 402 set to the MLD MAC address of the non-AP MLD 120, the TDLS responder STA Address field 403 set to the MLD MAC address of the non-AP MLD 130, and the BSSID field 401 set to the BSSID corresponding to AP2 112 operating on the base channel.

[0386] Next, in step 1530, the TDLS initiator non-AP MLD initiates a conventional TDLS setup (i.e., TDLS direct link establishment) with the peer non-AP MLD using the link shared and set up with the AP MLD (AP2 112 in the example of FIG. 12a) as the target link. Note that each TDLS Setup frame contains a Link Identifier 400 whose BSSID field 401 is set to the BSSID of the AP (AP2 112 in the same example) operating on the link over which the non-AP MLD intends to establish a single-link TDLS direct link. During the TDLS setup phase, both non-AP MLDs may share their capabilities, supported channels, and supported bands. Therefore, the TDLS Discovery procedure may be omitted. In other words, two peer non-AP MLDs can learn about each other (about supported channels and bands) through the TDLS Discovery procedure or the TDLS Setup procedure.

[0387] Upon successful completion of the TDLS setup procedure, STA A2 122 and STA B2 132 (TDLS peer STAs) belonging to non-AP MLDs 120 and 130, respectively, can communicate directly in parallel with the AP's traffic (P2P data - not shown in Figures 12c and 12d) via the set-up TDLS direct link.

[0388] At this stage, the TDLS initiator's non-AP MLD may select one or more channels as off-channels based on the recommended channels collected from the AP MLD (through the Probe Response frame 213 or the Channel Usage Response frame 816), and optionally based on the supported channels / bands collected from the peer non-AP MLD (during the TDLS Discovery or TDLS Setup procedure) and its own supported channels / bands. This or these off-channels define the target off-link to be created according to the second embodiment, for use in direct or P2P communication.

[0389] Next, the non-AP MLD of the TDLS initiator decides to move or switch the set-up TDLS session (direct link) from the TDLS link shared with the AP's traffic to the target's off-link.

[0390] In some embodiments, such as shown in Figure 12d, the transfer is performed in two steps, while in other embodiments, such as shown in Figure 12c, one step is required. Switching in the two-step approach is based on the target link (corresponding to an off-link that has not yet been created), while switching in the one-step approach is based on the target channel (defining an off-link that has not yet been created in the same operation).

[0391] In step 1540, which is specific to the two-step approach, the non-AP MLD of the TDLS initiator creates a TDLS link targeting a selected set of off-channels, i.e., off-links, by exchanging TDLS action frames tunneled by the AP MLD with the peer non-AP MLD via an existing TDLS session. Thus, off-links for TDLS communication are created simultaneously in both peer non-AP MLDs. This step is very similar to step 1230 described above.

[0392] For example, a non-AP MLD of a TDLS initiator initiates the creation of a TDLS off-link by sending a TDLS Link Setup Request frame to a peer non-AP STA, which includes a link identifier and the operating band of this new link, i.e., one or more selected off-channels. The frame may be a TDLS action frame that includes a Target Channel element, an Operating Class element, and a link ID, i.e., a numeric value that identifies the off-link to be created. In a variant, the TDLS Link Setup Request frame may include a Multi-Link element with multiple per-STA profiles, each of which conveys the target channel, operating class, and link identifier of the corresponding off-link to be created.

[0393] In response, the non-AP MLD of the TDLS initiator receives a TDLS Link Setup Response frame using a dedicated code to confirm or not to create one or more off-links. The response frame may include a counterproposal for performing off-link negotiation, as described above with reference to step 1230.

[0394] If approved, a TDLS Link Setup Confirm frame is sent from the non-AP MLD of the TDLS initiator to confirm the creation of the off-link. The AP MLD can be notified about the created link ID and the created off-link.

[0395] FIG. 12 d shows the exchange of a TDLS Link Setup Request frame 1301 , a TDLS Link Setup Response frame 1302 , and a TDLS Link Setup Confirm frame 1303 .

[0396] The next step is step 1550, where the non-AP MLD of the two peers actually switches the TDLS session (set up in step 1530) off-link.

[0397] In the two-step scenario of Fig. 12d, switching consists of performing TDLS Link switching, i.e., changing the link of an existing TDLS session (rather than changing only the channel or bandwidth as in conventional TDLS Channel switching).

[0398] The link switch may be performed by exchanging TDLS action frames with the peer non-AP MLD directly (without being tunneled by the AP MLD) over the existing TDLS session (on AP2 112's channel).

[0399] In the same scheme as the TDLS Switch frame, new types of TDLS Action frames may be used, hereafter referred to as TDLS Link Switch Request frames and corresponding TDLS Link Switch Response frames. Of course, the TDLS Switch frame may be updated (rather than creating a new frame) to carry signaling such as that required by the TDLS Link Setup frame described here.

[0400] A TDLS Link Switch Request frame may be assigned a value of 14 in the action field 302 , and a TDLS Link Switch Response frame may be assigned a value of 15 in the action field 302 .

[0401] For example, one of the two non-AP MLDs sends a TDLS Link Switch Request frame 1620 to the other via either STA A2 122 or STA B2 132.

[0402] Frame 1620 includes the link ID of the target off-link to which the non-AP MLD of the initiator of the TDLS switch is to move, which is the link ID specified when the off-link was created and configured (step 1540).

[0403] The peer non-AP MLD then responds with a TDLS Link Switch Response frame 1621 repeating the link ID and including a status code.

[0404] To confirm the Link Switch, the response includes a success status code (e.g., SUCCESS), so that both peer STAs involved in the initial TDLS session (set up in step 1540) configure themselves to operate on the target's off-link.

[0405] If the Link Switch is rejected, the response includes a rejection status code (e.g., REQUEST_DECLINED), so that both STAs continue to operate on the same link (the TDLS session does not move).

[0406] To ensure synchronicity between two peer STAs when configuring themselves off-link to a target, the TDLS Link Switch Request and Response frames 1620, 1621 may include a timing information element (9.4.2.63 Channel Switch Timing element in REVme2.0) to synchronize the moment when a link switch actually occurs.

[0407] In the one-step scenario of Figure 12c, switching consists of performing TDLS Channel switching targeting one or more off-channels of the off-link to move the first TDLS session off-link. TDLS Channel switching is a conventional operation defined in clause 11.20.6 of REVme2.0 and involves exchanging TDLS Switch Request and corresponding Response frames.

[0408] For example, one of the two non-AP MLDs sends a TDLS Channel Switch Request frame 1610 to the other via STA A2 122 or B2 132 to move the P2P communication / session off-link.

[0409] The TDLS Channel Switch Request frame 1610 includes the target operating band and channel for which an off-link must be established, and a link identifier for identifying the newly created off-link, in the same way as the previously described TDLS Link Setup Request frame 1301. Furthermore, as a Switch frame, the frame 1610 includes channel switch timing information (9.4.2.63 Channel Switch Timing element in REVme2.0).

[0410] The target channel corresponds to the off-link operating channel (ie, the off-channel) that is used as the target channel.

[0411] If an off-link is defined using multiple off-channels, the TDLS Channel Switch Request frame 1610 may further include a Multi-link element with one or more per-STA profiles defining the multiple off-channels. In this case, the operating channel of the off-link used as the target channel may be any of the channels in the channel entry (Channel Usage element) corresponding to the off-link. This allows the peer STA to clearly identify which off-link is the target of the switch.

[0412] The peer STA (B2 in this example) responds with a TDLS Channel Switch Response frame 1611 carrying the same link identifier and status code.

[0413] To confirm the Channel Switch, the response includes a success status code (e.g., SUCCESS), so that both peer STAs involved in the initial TDLS session (set up in step 1540) configure themselves to operate on the target's off-link.

[0414] If the Channel Switch is rejected, the response contains a rejection status code (e.g., REQUEST_DECLINED), and as a result, both STAs continue to operate on the same link (the TDLS session does not move).

[0415] As is clear from the above, the TDLS Link Switch frame and the TDLS Channel Switch frame are distinguished from one another primarily by the signaling of the Link ID field (in the former case) rather than the target operating band and channel (in the latter case).

[0416] As a result (in both the one-step and two-step approaches), after a sufficient period of clear channel assessment (CCA) on the off-link (as described in 11.20.6 TDLS channel switching in REVme2.0), STAs A2 122 and B2 132 (TDLS peer STAs) belonging to non-AP MLD 120 and non-AP MLD 130, respectively, may communicate on the off-link in step 1570.

[0417] In other words, two non-AP MLDs perform peer-to-peer communication between a first TDLS STA and a second TDLS STA via the created off-link.

[0418] To remove the peer STAs' subordination to the AP MLD and thus the need to switch back to their base channel, optional step 1560 (before or during step 1570) removes or disables the links set up by the peer STAs involved in the AP MLD, i.e., the setup links underlying the off-links. In the scenario of Figure 12a, this means that links 152 and 162 with AP2 112 are both removed or disabled.

[0419] In a variant, the deletion / invalidation may be performed before the switching.

[0420] Various implementations of this behavior can be envisaged. For example, the deletion or invalidation of a link setup by one of the two peer STAs with AP MLD: Update the TID-To-Link mapping of the link setup with the AP MLD by the corresponding non-AP MLD and remove all TIDs assigned to the link to be deleted / disabled. Performing a new multi-link setup (i.e., re-setup) with AP MLD excluding the link to be deleted / disabled; It may include any of the following.

[0421] This operation is indicated in Figures 12c and 12d by arrow 850. Because two peer STAs are involved in P2P communication over off-link, a different affiliated STA is used for this operation in both peer non-AP MLDs.

[0422] In the illustrated example, a frame intended to remove / disable link 152 is transmitted from STA A1 121 to AP1 111, and a frame intended to remove / disable link 162 is also transmitted from STA B1 131 to AP1 111.

[0423] 10a shows a schematic diagram of a communication device 1000, which is either a non-AP MLD incorporating multiple non-AP stations 120, 130 or an AP MLD incorporating multiple APs 110, of a wireless network NETW, configured to carry out at least one embodiment of the present invention. The communication device 1000 may preferably be a device such as a microcomputer, a workstation, or a lightweight handheld device. The communication device 1000 may include: a central processing unit 1001 such as a processor referred to as a CPU; a memory 1003 for storing executable code of a method or method steps according to an embodiment of the invention and registers adapted to record variables and parameters necessary for the execution of the method; at least one communication interface 1002 connected via a transmitting and receiving antenna 1004 to a wireless communication network, for example a communication network according to one of the standards of the IEEE 802.11 family; 11. The system has a communication bus 1113 that is preferably connected to the

[0424] Preferably, a communications bus provides communication and interoperability between the various elements included in or connected to communications device 1800. The representation of a bus is not limiting, and in particular a central processing unit is operable to communicate instructions to any element of communications device 1800 directly or with another element of communications device 1800.

[0425] The executable code may be stored in a memory, either read-only, on a hard disk, or on a removable digital medium, such as a disk. According to an optional variant, the executable code of the program may be received by the communication network, via the interface 1002, to be stored in the memory of the communication device 1000 before being executed.

[0426] In an embodiment, the device is a programmable device that uses software to implement embodiments of the invention, however, embodiments of the invention may alternatively be implemented in whole or in part in hardware (e.g., in the form of an application specific integrated circuit (ASIC)).

[0427] 10b is a block diagram that schematically illustrates the architecture of a communications device 1000 adapted to at least partially implement the present invention. As shown, the device 1000 has a physical (PHY) layer block 1023, a MAC layer block 1022, and an application layer block 1021.

[0428] The PHY layer block 1023 (here, multiple 802.11 standardized PHY layer modules) has the task of formatting, modulating, or demodulating any 20 MHz channel or composite channel and transmitting or receiving 802.11 frames, such as medium access trigger frames for reserving transmission slots, MAC data and management frames based on a 20 MHz width for interacting with legacy 802.11 stations, and OFDMA-type MAC data frames with a width smaller than the 20 MHz legacy (typically 2 MHz or 5 MHz), to or from the wireless medium NETW.

[0429] The MAC layer block or controller 1022 preferably includes an MLE MAC 802.11 layer 1824 that performs conventional 802.11 MAC operations, and additional blocks 1025 for at least partially implementing embodiments of the present invention. The MAC layer block 1022 may optionally be implemented in software that is loaded into RAM 1003 and executed by CPU 1801. The MLE MAC 802.11 layer 1024 may implement an Upper-MAC stack with a series of Lower-MAC modules.

[0430] Preferably, an additional block 1025 called P2P management module for performing off-link operations for TDLS services via multi-link communication implements part of the embodiments of the present invention (in peer non-AP MLD), which performs the operations described with reference to Figures 5b, 6a-6c, 7a-7d, 8-8c and 9a-9b, or 11a-11d and 12a-12d, depending on the embodiment implemented.

[0431] The MAC 802.11 layer 1024 and P2P management 1025 interact with each other to establish and handle accurate communications over OFDMA RUs among multiple non-AP MLD stations in accordance with an embodiment of the present invention.

[0432] On Fig. 10b, an application layer block 1021 executes applications that generate and receive data packets, e.g., video streams, etc. The application layer block 1021 represents all stack layers above the MAC layer according to the ISO standard.

[0433] In an embodiment, the device is a programmable device that uses software to implement embodiments of the invention, however, embodiments of the invention may alternatively be implemented in whole or in part in hardware (e.g., in the form of an application specific integrated circuit (ASIC)).

[0434] Although the present invention has been described with reference to particular embodiments, it is not limited to those embodiments, and modifications within the scope of the invention will be apparent to those skilled in the art.

[0435] Many further modifications and variations will be suggested to those skilled in the art upon reference to the exemplary embodiments described above, but these embodiments are given by way of example only and are not intended to limit the scope of the invention, which is determined solely by the appended claims. In particular, different features from different embodiments may be interchanged where appropriate.

[0436] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do 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 used to advantage.

Claims

1. A communication device that operates as a non-access point multilink device (non-AP MLD), comprising:

10. A communications device comprising: transmitting means configured to transmit a frame including a subfield indicating whether the non-AP MLD has intra-device coexistence activity on one or more links of the non-AP MLD.

2. The non-AP MLD conforms to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 series of standards; The communication device according to claim 1 , wherein the subfield indicates that one or more links of the non-AP MLD are links used for coexistence with communications of radio access technologies other than radio access technologies conforming to the IEEE 802.11 standard series.

3. The communication device described in Claim 1, characterized in that the non-AP MLD incorporates multiple communication chips and optimizes coexistence between different wireless access technologies.

4. The communication device described in Claim 3, characterized in that the multiple communication chips include at least two communication chips for cellular, Wi-Fi, and Bluetooth.

5. A communication device operating as an access point multilink device (AP MLD), comprising:

1. A communication device comprising: receiving means for receiving a frame from a non-access point multilink device (non-AP MLD) including a subfield indicating whether the non-AP MLD has intra-device coexistence activity on one or more links of the non-AP MLD.

6. The non-AP MLD conforms to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 series of standards; 6. The communication device according to claim 5, wherein the subfield indicates that one or more links of the non-AP MLD are links used for coexistence with communications of radio access technologies other than radio access technologies conforming to the IEEE 802.11 standard series.

7. A control method for controlling a non-access point multi-link device (non-AP MLD), comprising: generating a frame including a subfield indicating whether the non-AP MLD has intra-device coexistence activity on one or more links of the non-AP MLD; a transmitting step of transmitting the generated frame; A control method comprising:

8. A control method for controlling an access point multi-link device (AP MLD), comprising: receiving a frame from a non-AP multilink device (non-AP MLD) including a subfield indicating whether the non-AP MLD has intra-device coexistence activity on one or more links of the non-AP MLD; an interpretation step for interpreting the received frame; A control method comprising:

9. A non-access point multi-link device (non-AP MLD), a generating step of generating a frame including a subfield indicating whether the non-AP MLD has intra-device coexistence activity on one or more links of the non-AP MLD; a transmitting step for transmitting the generated frame; A program to execute.

10. An access point multi-link device (AP MLD), a receiving procedure for receiving a frame from a non-AP multilink device (non-AP MLD) including a subfield indicating whether the non-AP MLD has intra-device coexistence activity on one or more links of the non-AP MLD; Interpretation procedure for interpreting received frames A program to execute.

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