Access point multilink device and communication method

Abstract

The invention relates to an access point multi-link device and a communication method used for the access point multi-link device. This access point multilink device is provided with: a reception unit that receives, from a non-AP MLD that is a non-AP multilink device, an association request frame that includes information for specifying one or more links requested for multilink establishment, and link specifying information for the one or more links requested; a control unit that determines, on the basis of the link-specific information, whether or not to accept each of the one or more requested links; and a transmission unit that transmits an association response frame for indicating the link accepted by the control unit, the association request frame including a common information field for indicating the MAC address of the non-AP MLD.

Description

[0001] This application is a divisional application of the patent application filed on January 29, 2021, with application number 202180020056.1, entitled "Communication apparatus and communication method for multi-link establishment and link maintenance". Technical Field

[0002] This embodiment generally relates to communication devices, and more specifically, to methods and apparatus for establishing and maintaining multiple links. Background Technology

[0003] In today's world, communication devices are expected to operate wirelessly with the same capabilities as wired computing devices. For example, users expect to be able to seamlessly watch high-definition movies streamed to their wireless communication devices. This presents challenges for both the communication devices themselves and the access points to which they are wirelessly connected.

[0004] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 Group recently established the 802.11 Task Group (TG) to address these challenges. Multi-link operation in the 2.4 GHz, 5 GHz, and 6 GHz bands has been identified as a key candidate technology for this type of communication. Multi-channel aggregation on multiple links is a natural way to create exponential increases in communication data throughput.

[0005] To enable this multi-link operation between Access Point (AP) Multilink Devices (MLDs) and non-AP MLDs, multilink establishment can be performed on one of the supported links to establish associations of Subsidiary Stations (STAs) on one or more links. Summary of the Invention

[0006] A non-limiting and exemplary embodiment helps to provide a first station (STA) included in a first plurality of STAs attached to a first multilink device (MLD), the first STA comprising: circuitry that generates a request frame including request information; and a transmitter that sends the request frame to a second STA to request multilink establishment, wherein the second STA is included in a second plurality of STAs attached to a second MLD, and wherein the multilink establishment establishes one or more links between one or more STAs in the first plurality of STAs and corresponding one or more STAs in the second plurality of STAs based on the request information.

[0007] Another non-limiting and exemplary embodiment helps to provide a second STA included in a second plurality of STAs attached to a second multilink device (MLD), the second STA comprising: a receiver receiving a request frame from a first STA, wherein the first STA is included in a first plurality of STAs attached to a first MLD, and wherein the request frame includes request information and is requesting multilink establishment, the multilink establishment being based on the request information to establish one or more links between one or more STAs in the first plurality of STAs and corresponding one or more STAs in the second plurality of STAs; and a transmitter sending a response frame to the first STA to notify of the result of the multilink establishment, wherein the response frame carries information on one or more links already established between one or more STAs in the first plurality of STAs and corresponding one or more STAs in the second plurality of STAs.

[0008] Another non-limiting and exemplary embodiment helps to provide a communication method comprising: generating a request frame at a first STA included in a first plurality of STAs attached to a first MLD, the request frame including request information; and sending a request frame to a second STA to request multi-link establishment, wherein the second STA is included in a second plurality of STAs attached to a second MLD, and wherein the multi-link establishment establishes one or more links between one or more STAs in the first plurality of STAs and corresponding one or more STAs in the second plurality of STAs based on the request information.

[0009] It should be noted that general or specific embodiments may be implemented as systems, methods, integrated circuits, computer programs, storage media, or any alternative combination thereof. Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. Benefits and / or advantages can be obtained individually from the various embodiments and features in the specification and drawings, and it is not necessary to provide all of these embodiments and features to obtain one or more such benefits and / or advantages. Attached Figure Description

[0010] The accompanying drawings are used to illustrate various embodiments and explain the various principles and advantages according to the embodiments. In the drawings, the same reference numerals refer to identical or functionally similar elements in separate views, and they are incorporated into and form a part of the specification together with the following detailed description.

[0011] Figure 1 The diagram illustrates the relationship between the coverage frequency and range of a wireless node.

[0012] Figure 2 The communication flow between an AP MLD and a non-AP MLD is depicted according to an example, which is used for multilink establishment, link quality assessment, traffic identifier (TID) to link mapping and subsequent communication.

[0013] Figure 3 Illustrations depict AP MLDs having multiple Basic Service Sets (BSSs) and multiple non-AP MLDs within the scope of the BSSs, according to various embodiments.

[0014] Figure 4 Illustrations depict Extended Service Sets (ESS) with MLD according to various embodiments.

[0015] Figure 5 The communication flow between AP MLD and non-AP MLD according to the first embodiment is described, which is used for multi-link discovery, authentication, establishment, TID to link mapping and subsequent communication.

[0016] Figure 6 An illustration depicts a multi-link action frame according to the first embodiment.

[0017] Figure 7 An illustration depicts a multi-link establishment frame according to the first embodiment.

[0018] Figure 8 An illustration of a multi-link element according to the first embodiment is depicted.

[0019] Figure 9 An illustration depicts a multi-link teardown frame according to the first embodiment.

[0020] Figure 10 An illustration depicts a transmit power control (TPC) request element according to a first embodiment.

[0021] Figure 11 An illustration depicts a TPC reporting element according to a first embodiment.

[0022] Figure 12 An illustration depicts a multi-link element of multi-link authentication according to a first embodiment.

[0023] Figure 13 An illustration depicts the multi-link elements of a multi-link establishment request according to the first embodiment.

[0024] Figure 14A A variation of the minimum link quality requirement table maintained by the AP MLD according to the first embodiment is depicted.

[0025] Figure 14B It depicts the user priority (UP) to TID mapping table as specified in the 802.11 specification.

[0026] Figure 14C A diagram depicts the multi-link establishment response and TID-to-link mapping elements according to the first embodiment.

[0027] Figure 14D A TID mapping encoding table according to the first embodiment is described.

[0028] Figure 15 The communication flow between an AP MLD and a non-AP MLD, including a multi-link reconstruction request, is described according to the first embodiment.

[0029] Figure 16 A diagram depicts a multi-link action frame of a multi-link establishment response according to the first embodiment.

[0030] Figure 17 A state transition diagram according to the first embodiment is depicted.

[0031] Figure 18 An alternative state transition diagram according to the first embodiment is depicted.

[0032] Figure 19 An illustration depicts how link maintenance is performed according to the first embodiment.

[0033] Figure 20 The communication flow between an AP MLD and a non-AP MLD, including a link quality assessment step, is described according to the second embodiment.

[0034] Figure 21 An alternative state transition diagram according to the second embodiment is depicted.

[0035] Figure 22 A diagram depicts the multi-link elements of multi-link reconstruction requests and link deletions according to the second embodiment.

[0036] Figure 23 An illustration depicts a multi-link teardown frame according to the second embodiment.

[0037] Figure 24 Illustrations depicting multi-link establishment and link maintenance between AP MLDs and non-AP MLDs according to various embodiments.

[0038] Figure 25 Schematic diagrams of the MLD 2500 according to various embodiments are depicted.

[0039] Figure 26 A flowchart 2600 illustrating a method for retransmission with multi-link guarantees according to various embodiments is shown; and

[0040] Figure 27 A schematic partial cross-sectional view is shown of one of the auxiliary STAs of a multilink device 2700 that can be implemented for multilink communication according to various embodiments.

[0041] Those skilled in the art will understand that the elements in the diagram are shown for simplicity and clarity and are not necessarily drawn to scale. Detailed Implementation

[0042] The following detailed description is exemplary in nature only and is not intended to limit the embodiments or their application and use. Furthermore, there is no intention to be bound by any theories set forth in the foregoing background or detailed description. Moreover, other desirable features and characteristics will become apparent from the following detailed description and appended claims, taken in conjunction with the accompanying drawings and the background of this disclosure.

[0043] Typically, when a multi-link connection is established between an AP MLD and a non-AP MLD, the relevant link can be in one of the following states:

[0044] - Established (or already set up): The AP MLD and non-AP MLD have all the information that enables them to perform data operations on each other. This state can be equivalent to state 3 of the state transition diagram of the non-mesh STA, where the IEEE 802.1X controlled port is blocked (i.e., only Extensible Authentication Protocol (EAPOL) data frames on the LAN are allowed, and other data frames are not allowed).

[0045] - Enabled (Activated): Both MLDs agree to begin data operations on the link. For example, if at least one Traffic Identifier (TID) is mapped to the link, then Robust Secure Network Association (RSNA) for that link has been completed. This can be equivalent to state 4 of the non-mesh STA state transition diagram, where the IEEE 802.1X controlled port is not blocked (i.e., all data frames are allowed).

[0046] -Disabled: In this state, a link can be established but data operations are disabled, or RSNA establishment is completed but no TID is mapped to the link, or MLD can ignore frames received on the link.

[0047] It is crucial to clarify how the MLD maintains the link state, define the rules for allowing / disallowing frames, and the MLD's actions related to each link state.

[0048] Furthermore, different links in an MLD may have different range / channel conditions. (Reference) Figure 1 , Figure 1The relationship between the coverage frequency and range of wireless nodes is depicted: 11af coverage (54-698 MHz) has a range of 3 km and greater, cellular coverage (600-900 MHz) has a range of 1-3 km, 11ah coverage (900 MHz) has a range of 1 km, 11 / b / g / n coverage (2.4 GHz) has a range of 100 meters, 11a / ac coverage (5 GHz) has a range of 50 meters, and 11ad coverage (600 MHz) has a range of 10 meters. If multi-link establishment frames are exchanged in links in lower frequency bands (e.g., the 2.4 GHz band), the MLD may not be within range of other links in higher frequency bands (e.g., 5 GHz or 6 GHz). Furthermore, even if the MLD is within range of other supported links, some links may be of poor quality, for example due to excessively overlapping Basic Service Set (OBSS) interference, frequency-dependent fading, or coexistence interference (e.g., due to Bluetooth in the 2.4 GHz band), and therefore may not be suitable for link activation.

[0049] In fact, the link capabilities of a non-AP MLD may not provide enough information to establish a link. After the multi-link establishment process is complete, some (potential) links / STAs of the MLD may be in a fourth state (i.e., not established (not set up / unavailable)). Therefore, frame switching on the link is not possible. However, if conditions change (e.g., a non-MLD moves closer to the AP MLD), such a link may become available for establishment.

[0050] Therefore, links should not be established or configured solely based on capability information. Non-AP MLDs should be able to select which links to establish. Furthermore, the channel quality of the links (especially second and subsequent links) needs to be checked before establishing / enabling them (either during multi-link establishment itself or during subsequent activation operations). The channel quality of enabled links also needs to be checked periodically to ensure that the link is active and suitable for being mapped to one or more TIDs.

[0051] Accordingly, the present invention seeks to solve the above-mentioned problems.

[0052] Figure 2The communication flow between AP MLD 202 and non-AP MLD 204, based on a typical solution for resolving the aforementioned issues, is depicted, including multilink establishment, link quality assessment, traffic identifier (TID) to link mapping, and subsequent communication. During multilink establishment, a multilink establishment request 206 is sent from non-AP MLD 204 to AP MLD 202 on link 2. The multilink establishment request includes information about the link capabilities of links 1, 2, and 3. In response to this request, AP MLD 202 establishes the requested links 1, 2, and 3, and then sends a multilink establishment response 208 to non-AP MLD 204 to notify of the link establishment. At 210, non-AP MLD 204 is now authenticated / associated, and the three links are now established. Multilink RSNA (4-way handshake / group key handshake) between AP MLD 202 and non-AP MLD 204 is then performed on link 2. It should be understood that each of links 1, 2 and 3 connects to the associated STAs of AP MLD 202 and the associated STAs of non-AP MLD 204, enabling these STAs to send or receive any data or frames on the relevant links.

[0053] After establishing multiple links, AP MLD 202 can initiate a link quality assessment process to check the quality of the established links, which can be used to determine the TID-to-link mapping. AP MLD 202 can send a link measurement request 214 on link 1 and a link measurement request 218 on link 3 to assess the link quality of links other than link 2. In response, non-AP MLD 204 sends a link measurement report 216 and a link measurement report 220 to AP MLD 202 via link 1 and link 3, respectively. Link measurement report 216 includes link quality information for link 1, and link measurement report 220 includes link quality information for link 3. The link quality assessment can also be performed before establishing multiple links.

[0054] Subsequently, AP MLD 202 can determine the TID to be mapped to each link based on link quality assessment, and initiate TID-to-link mapping by sending a TID-to-link mapping request 222 to non-AP MLD 204 on link 2. The TID-to-link mapping request includes a TID mapping indicating how each TID is mapped to each link. In response, non-AP MLD 224 sends a TID-to-link mapping response 224 to AP MLD 202 on link 2 to indicate the status of the TID mapping. After all three links are enabled and the TIDs are mapped to those links (at 226), frame switching can then be performed on any / all of those three links (at 228).

[0055] The above solution has some drawbacks. For example, it establishes links solely based on capability information (i.e., the capability information included in the multi-link establishment request 206). Furthermore, it is an AP-centric solution; that is, the STA has no say in which link is established or enabled.

[0056] During multi-link establishment, additional links (i.e., links other than those used to exchange multi-link establishment frames) should not be established solely based on capability information. A first MLD may request a second MLD whose links will be established as part of the multi-link establishment, independent of link capabilities, for example, using the establishment request field in a multi-link establishment request frame. The MLD may also include information about the link quality of the requested links (e.g., uplink / downlink (UL / DL) margin, UL / DL path loss, etc.). Furthermore, the second MLD will only establish links requested by the first MLD during multi-link establishment (e.g., the assignment of association identifiers (AIDs), the contents of association records, etc.). The established links may be referred to as a multi-link set. The second MLD may also consider information about link quality to determine whether to establish / enable a link, especially when TID limitations exist on some links. This information can also be used for subsequent TID-to-link mapping (i.e., link enabling / disabling).

[0057] Figure 3 Illustration 300 depicts an AP MLD 302 with multiple BSSs according to various embodiments, and non-AP MLDs 304, 306, and 308 within the BSS range. AP MLD 302 can be illustrated as a schematic diagram 314, which includes a MAC Service Access Point (MAC-SAP) for Access Distribution Service (DS), an MLD MAC address identifying the AP MLD, and three subordinate APs (i.e., AP1, AP2, and AP3). Each AP has its own STA MAC address at the MAC layer and is connected via links at the PHY layer for sending and receiving data (i.e., AP1 is connected via link 1, AP2 via link 2, and AP3 via link 3).

[0058] Furthermore, non-AP MLDs 304, 306, and 308 can be illustrated as diagram 316, including a MAC-SAP for accessing the DS, an MLD MAC address identifying the non-AP MLD, and three associated STAs (i.e., STA1, STA2, and STA3). Each STA has its own STA MAC address at the MAC layer and is connected via links at the PHY layer for sending and receiving data (i.e., STA1 is connected via link 1, STA2 via link 2, and STA3 via link 3).

[0059] AP MLD 302 establishes multiple (multi-link) BSSs, one for each affiliated AP. Each BSS has its own BSSID, beacon, and can have different coverage areas. For example, AP1 operates its BSS at 6 GHz, AP2 at 5 GHz, and AP3 at 2.4 GHz. The coverage areas of different APs may differ (due to frequency band, transmit (Tx) power, etc.). Coverage can also depend on the modulation and coding scheme (MCS); that is, MCS 0 can have a much larger coverage area compared to MCS 9. Furthermore, non-AP MLDs can be within the coverage of one or more such BSSs. For example, only STA1 of non-AP MLD 304 is within the coverage area of ​​AP MLD 302 via AP1; only STA1 and STA2 of non-AP MLD 306 are within the coverage area of ​​AP MLD 302 via AP1 and AP2, while all three STAs of non-AP MLD 308 are within the coverage area of ​​AP MLD 302 (i.e., all three APs).

[0060] An AP MLD is an entity with Distributed System Access Function (DSAF), which enables associated non-AP MLDs (with one or more affiliated STAs) and traditional STAs to access the DS via wireless media (WM). Different affiliated STAs of a non-AP MLD can connect to different APs of the AP MLD to gain access to the DS. However, all APs of the AP MLD can connect to the DS through the same single MAC-SAP and DSAF.

[0061] This network formed Figure 4The Extended Service Set (ESS) 400 is illustrated in the diagram. STA1, STA2, and STA3, which are attached to a non-AP MLD1, can connect to, for example, AP1, AP2, and AP3 of AP MLD1 to obtain access to the DS. AP1, AP2, and AP3 can connect to the DS via the MAC-SAP and DSAF of AP MLD1. Similarly, STA4, STA5, and STA6, which are attached to a non-AP MLD2, can connect to, for example, AP4, AP5, and AP6 of AP MLD2 to obtain access to the DS. AP4, AP5, and AP6 can connect to the DS via the MAC-SAP and DSAF of AP MLD2. Traditionally, a conventional STA, such as STA7, obtains access to the DS by associating with an AP, and it can even continue to do so by associating with any of the AP MLD's attached APs (e.g., AP4 of AP MLD2). However, for non-AP MLDs, the association process can be replaced by a multi-link establishment process, as described further below. Multilink establishment performed between any pair of affiliated STAs and affiliated APs can provide access to the DS for one or more affiliated STAs of a non-AP MLD.

[0062] Figure 5 A communication flow between an AP MLD and a non-AP MLD according to a first embodiment is depicted, used for multi-link discovery, authentication, establishment, TID-to-link mapping, and subsequent communication. First, in the multi-link discovery phase, the non-AP MLD 504 checks the quality of links 1, 2, and 3 by sending probe request frames 506 to the AP MLD 502 on each link. The probe request frame 506 may include a transmit power control (TPC) request element. In response to receiving the probe request frame 506, the AP MLD 502 may send a beacon or probe response frame 508 to the non-AP MLD 504 on each link. The beacon or probe response frame 508 may include the MLD MAC address of the AP MLD 502 and a TPC report element. After completing the multi-link discovery phase, the non-AP MLD can be considered to be in state 1.

[0063] Following the discovery phase, non-AP MLD 504 can initiate multi-link authentication by sending an authentication request 510 to AP MLD 502 on, for example, link 2. The authentication request may include information about the MLD MAC address of non-AP MLD 504. In response to receiving the authentication request 510, AP MLD 502 can send an authentication response 512 to non-AP MLD 504 on the same link 2. The authentication response may include information about the MLD MAC address of AP MLD 502. For open systems with an Extensible Authentication Protocol (EAP), multi-link authentication may be optional, but it is mandatory for SAE and Fast Initial Link Establishment (FILS). The MLD MAC address can be used during authentication in SAE and FILS. After successful authentication, the multi-link state of the non-AP MLD can be changed to state 2.

[0064] After successful authentication, a non-AP MLD 504 can initiate multi-link establishment / association by sending a multi-link establishment request 514 to the AP MLD 502 on, for example, link 2. The multi-link establishment request 514 can include the link capabilities of links 1, 2, and 3, as well as request information identifying the affiliated STAs of the non-AP MLD 504 for which it will establish links—that is, links 1, 2, and 3 in this case. The request information may also include information about the radio channel quality of each of links 1, 2, and 3. The request information may also include information about the desired traffic characteristics for each of links 1, 2, and 3, such as Traffic Identifier (TID), payload size, delay limits, data rate, minimum PHY rate, etc.

[0065] In response to the request and based on the request information, AP MLD 502 establishes the requested links 1, 2, and 3, and then sends a multilink establishment response 516 to non-AP MLD 504 to notify of the link establishment. At 518, non-AP MLD 504 is now authenticated / associated, and the three requested links are now established. After successful establishment, the multilink state of non-AP MLD can be changed to state 3. Multilink RSNA (4-way handshake / group key handshake) between AP MLD 502 and non-AP MLD 504 can then be performed, for example, on link 2.

[0066] After multi-link establishment is complete, AP MLD 502 can initiate TID-to-link mapping by sending a TID-to-link mapping request 522 to non-AP MLD 504 on, for example, link 2. TID-to-link mapping request 522 can include the requested TID mappings for links 1, 2, and 3, indicating how each TID is mapped to each link. In response, non-AP MLD 524 can send a TID-to-link mapping response 524 to AP MLD 502 on link 2 to indicate the status of the TID mapping. After all three links are enabled and TIDs are mapped to these links (at 526), ​​frame switching can then occur on any / all of the three links (at 528). After TID-to-link mapping is completed at 526, the multi-link state of the non-AP MLD can be changed to state 4. TID-to-link mapping can be optional, and initial mapping can also be performed as part of the multi-link establishment process. By default, all TIDs are mapped to all established links.

[0067] It should also be understood that each of links 1, 2, and 3 connects to an affiliated AP of AP MLD 502 and an affiliated STA of non-AP MLD 504, enabling these STAs to transmit or receive any data or frames on the relevant link. Before sending establishment request 514, the affiliated STA of non-AP MLD 504 can collect information about the radio channel quality of each of one or more links, where radio channel quality includes one or more of link margin, path loss, Received Signal Strength Indication (RSSI), and Received Channel Power Indication (RCPI).

[0068] It can be Figure 5 The multi-link operation shown defines a new (Class 1) action frame. Figure 6 An illustration depicts a novel multilink action frame 600 according to a first embodiment. The multilink action frame 600 may include a frame control field, a duration field, three address fields, a sequence control field, an HT control field, a category field, a multilink action field, a variable field, and a frame check sequence (FCS) field. The multilink action field may have a value of 0, indicating that the action frame is used for multilink establishment, or a value of 1, indicating that the action frame is used for multilink teardown. Values ​​2-255 may be reserved.

[0069] Figure 7An illustration is depicted of a multilink establishment frame 700 according to a first embodiment. The multilink establishment frame 700 may include a frame control field, a duration field, three address fields, a sequence control field, an HT control field, a category field, a multilink action field set to a value of 0 (i.e., set to multilink establishment), a dialogue field, a multilink element field, one or more optional element fields, and an FCS field.

[0070] Figure 8 A diagram depicts a multilink element 800 according to a first embodiment. The multilink element 800 may include an element ID field, a length field, an element ID extension field, an action type field, an action status field, a multilink parameter control field, and a multilink parameter field. The multilink element 800 may be carried in a multilink action frame 600 or other frames such as association request / response frames and other management frames. Multiple multilink elements may also be carried in the same frame if signaling notifies multiple multilink operations (e.g., TID mapping and BA establishment, or multilink establishment and TID mapping) in the same frame exchange. Operations are signaled by the value indicated in the action type field of the multilink element 800. Value 0 may indicate multilink authentication, value 1 may indicate a multilink establishment request, value 2 may indicate a multilink establishment response, value 3 may indicate a TID-to-link mapping request, value 4 may indicate a TID-to-link mapping response, value 5 may indicate a block confirmation establishment request, and value 6 may indicate a block confirmation establishment response. Other values ​​7-255 may be reserved.

[0071] Figure 9 An illustration is depicted of a multi-link teardown frame 900 according to a first embodiment. The multi-link teardown frame 900 may include a frame control field, a duration field, three address fields, a sequence control field, an HT control field, a category field, a multi-link action field set to the value 1 (i.e., set to multi-link teardown), and an FCS field.

[0072] Alternatively, different multilink action frames and different multilink elements can be defined for each category. Alternatively, different signaling (i.e., multilink add_remove requests / responses) can be defined for the purpose of adding / removing links.

[0073] Refer back Figure 5 After discovering a multi-link BSS (i.e., via the multi-link capability element in the beacon frame), in order for the AP to calculate the UL path loss, the non-AP MLD 504 can include its transmit power (i.e., in the modified transmit power control (TPC) request element) in the probe request frame 506 sent in each multi-link BSS (link). Figure 10An illustration is depicted of a TPC request element 1000 according to a first embodiment. The TPC request element 1000 may include an element ID field, a length field, and a transmit power field. The transmit power field may be set to the transmit power used for the main frame (i.e., probe request frame 506).

[0074] Based on the transmit power indicated in the TPC request element of the received probe request frame, AP MLD 502 can estimate UL path loss and UL link margin, and include this information in probe response frame 508 (i.e., in the modified TPC report element) for transmission back to non-AP MLD 504 in each multi-link BSS. Figure 11 An illustration of a TPC reporting element 1100 according to a first embodiment is shown. The TPC reporting element 1000 may include an element ID field, a length field, a transmit power field, a link headroom field, and a path loss field. The transmit power field can be set to the transmit power for the main frame (i.e., probe response frame 508). The link headroom is the difference between the received power (dBm) and the receiver sensitivity (dBm). The link headroom field is encoded as a 2s complement signed integer in decibels and can be set to -128 to indicate that no link headroom is provided. The path loss is the difference between the transmit power and the received power of the frame carrying the TPC request element (e.g., a probe request frame received from a non-AP MLD). The path loss field is encoded as a 2s complement signed integer in decibels and can be set to 128 to indicate that no path loss is provided. The link headroom field is set to the UL link headroom estimated by the AP MLD 502, and the path loss field is set to the UL path loss estimated by the AP MLD 502.

[0075] Upon receiving probe response frame 508, the non-AP MLD 504 can use the transmit power information in the TPC report element to calculate the DL path loss, while the DL link margin can be calculated based on the receive power. The non-AP MLD 504 can use the link margin and path loss information to estimate the UL / DL link quality for each BSS (link). Alternatively, if the link measurement request / report frames are reclassified as Class 1 frames for non-directional multi-gigabit (DMG) / 11be STA, they can be used to achieve similar information. Furthermore, the AP MLD 502 can also advertise its MLD MAC address in beacon / probe response frames (e.g., within the multi-link capability element) for use during multi-link authentication (SAE, FILS) and multi-link establishment. If not, the probe request frame needs to carry an indication of a request for the MAC address for the AP MLD. It will be understood that the link measurement request / response frames mentioned here are alternatives, but any other suitable management frames can also be used for this purpose. In addition, if available, the results of the probing process (e.g., the Channel Quality Index (CQI)) can also be used.

[0076] If authentication is successful, the traditional STA state is changed to state 2. For MLDs, the state can remain at the MLD level (instead of the STA level). For open system authentication (e.g., EAP), two authentication frames are exchanged between the two MLDs. Existing authentication steps can be reused or omitted entirely. For SAE (i.e., authentication using cryptography), four authentication frames are exchanged between the two MLDs using a shared key (e.g., cryptography) to mutually authenticate and generate a pairwise master key (PMK). The MLD MAC address can be used instead of the link MAC address to initialize the STA-A-MAC and STA-B-MAC values ​​used to generate the secret cryptographic element (PWE). For FILS authentication, two authentication frames are exchanged between the two MLDs to mutually authenticate and generate the PMK. The AP-BSSID / STA-MAC can be replaced with the corresponding MLD MAC address to generate the PMK.

[0077] refer to Figure 5 Suppose that a non-AP MLD 504 discovers the MLD MAC address of an AP-MLD during multilink discovery, but the non-AP MLD 504 needs to include its MLD MAC address in the authentication / multilink establishment frame (e.g., in the multilink element) to allow AP MLD 502 to authenticate the non-AP MLD 504, and also to signal AP MLD 502 to use the MLD MAC address for SAE and FILS authentication. For this purpose, the multilink element can be carried in the authentication frame (or multilink establishment frame). Figure 12A diagram depicts a multi-link element 1200 for multi-link authentication according to a first embodiment. Multi-link element 1200 includes the same fields as multi-link element 800. However, the action type field is set to a value of 0, indicating multi-link authentication, and the multi-link parameter field is set to the MLD MAC address of a non-AP MLD 504. It will be understood that multi-link can be used to establish request / response frames, or authentication frames can be reused. Multi-link authentication is used to establish the identity of an MLD as a member of a set of MLDs authorized to be associated with another MLD.

[0078] Figure 13 An illustration depicts a multi-link element 1300 of a multi-link establishment request according to a first embodiment. The action type field is set to multi-link establishment request (i.e., set to the value 1). The multi-link parameter field may also include an MLD MAC address field, a multi-link capability field, a public information field carrying information common to all links, and one or more link information fields (i.e., one link information field for each supported link). Each link information field may include link-specific information, such as a link MAC address subfield, a link capability subfield, an establishment request subfield, a UL link complement subfield, a UL path loss subfield, a DL link complement subfield, and a DL path loss subfield.

[0079] refer to Figure 5 In multi-link establishment, the non-AP MLD 504 can explicitly request which links to establish, i.e., by using the establishment request subfield in the multi-link element 1300. For example, a value of 0 indicates that no establishment has been requested for the relevant link, while a value of 1 indicates that establishment has been requested. The non-AP MLD 504 can consider link quality information to determine which links to request for multi-link establishment. It can also consider other factors, such as the non-AP MLD 504 having the capability for a 2.4 GHz link (i.e., link 1), but choosing not to request the establishment of that link due to coexistence issues with its Bluetooth radio, or choosing not to request the establishment of certain links to save power, etc. The non-AP MLD 504 can also include information about the link quality of the requested links (e.g., UL / DL link headroom obtained during discovery, UL / DL path loss, etc.). If link quality information is unavailable, the Received Signal Strength Indicator (RSSI) / Received Channel Power Indicator (RCPI) of the beacon / probe response frames received on the link can be included as an estimate of the link quality. The results of the probing process (e.g., the Channel Quality Index (CQI)) can also be used as link quality information if available.

[0080] Non-AP MLD 504 may also include fields describing the characteristics of the traffic flow in the relevant link and QoS expectations. Furthermore, if no link establishment request is made for the relevant link, the link quality information in the UL link cofactor field, UL path loss subfield, DL link cofactor field, and DL path loss subfield can be omitted. Advantageously, this ensures that the link is established based on the non-AP MLD request and link quality.

[0081] When receiving a multi-link establishment request from a non-AP MLD 504, the AP MLD 502 will only establish the link requested by the non-AP MLD 504 (i.e., AID allocation, contents of the association record, etc.), and subsequent processes (i.e., TID-to-link mapping, security key generation / distribution, etc.). The AP MLD 502 can use information about link quality to decide whether to establish / enable the requested link, especially when TID restrictions exist on some links. This information can also be used for subsequent TID-to-link mapping (i.e., link enabling / disabling). The AP MLD 502 can maintain a minimum link quality table required to allow non-AP MLDs to use the link.

[0082] Figure 14A A variation of the minimum link quality requirement table maintained by the AP MLD according to the first embodiment is described. Figure 14A This specifies the link quality (in terms of link margin) required to map a TID to a specific link. Different links may have different values. For example, refer to... Figure 14A Links mapped by TID 6 and 7 (AC_VO) may have higher link quality requirements to support higher MCS. The requirements for uplink (UL) and downlink (DL) may be different. Figure 14B It depicts the mapping from user priority (UP) to TID as specified in the 802.11 specification.

[0083] If provided, the AP MLD can also use traffic flow information (similar to TSPEC elements) to determine whether to establish / enable a specific requested link for a non-AP MLD. For example, for a heavy traffic flow already indicated by TID 6, 7 for a non-AP MLD, the AP MLD can refuse to enable the link mapped to TID 6, 7 in order to maintain QoS requirements on the link. In some cases, the AP MLD can establish all requested links and decide whether to enable a link based solely on link quality (e.g., during initial or subsequent TID-to-link mapping). In other cases, the AP MLD can even consider link quality when establishing the requested link.

[0084] AP MLD can include only information about links that have already been established in the multilink establishment response frame. Figure 14C A diagram depicts a multi-link action frame 1400 according to a first embodiment, illustrating a multi-link establishment response and TID-to-link mapping. The multi-link action field of multi-link action frame 1400 is set to multi-link establishment (i.e., set to a value of 0). Multi-link action frame 1400 also includes two multi-link elements 1402 and 1404. Multi-link element 1402 is similar to multi-link element 1300, i.e., its action type field is set to a multi-link establishment request with one or more link information subfields (one for each established link). Multi-link element 1404's action type field is set to a TID-to-link mapping request (i.e., set to a value of 3), and may include (similar to multi-link elements 1300 and 1402) one or more link information fields (one for each established link). However, each of the one or more link information fields may include a link ID subfield, a UL TID mapping, and a DL TID mapping. Each TID mapping can be a bitmap (i.e., 8 bits: 1 bit / TID) that indicates the TID of the link (UL or DL) mapped to that direction, or it can use one or more 4-bit fields to indicate the TID. Figure 14D The diagram illustrates an example of TID mapping encoding based on a 4-bit field, with values ​​ranging from 0 to 15. When a non-AP MLD receives a TID-to-link mapping request frame from an AP MLD, it can send back a TID-to-link mapping response frame indicating acceptance of the TID mapping. If the TID mapping is rejected, a default TID mapping applies to the link, or the AP MLD can disable the link for the non-AP MLD. It will be understood that two multi-link elements can be carried in a multi-link establishment action frame (or associated response frame) to separately signal multi-link establishment and TID-to-link mapping, or they can be combined in a single element.

[0085] Furthermore, not only can multilink establishment request / response frames be used for multilink establishment, but association request / response frames (i.e., those carrying multilink elements) can also be used for multilink establishment. Upon successful multilink establishment, one or more non-AP STAs of the non-AP MLD can / are permitted to invoke the distribution system service via one or more AP STAs of the AP MLD.

[0086] New MAC sub-layer management entity (MLME) primitives can be defined for multi-link establishment, for example, by non-AP MLDs or APMLDs. MLME primitives are used to transfer information between the MLME and the station management entity (SME). The SME uses the services provided by the MLME through the MLME SAP. Primitives for requesting multi-link establishment for non-AP MLDs can be as follows:

[0087] MLME-MULTI-LINK-SETUP.request(

[0088] ...,

[0089] PeerMLDAddress

[0090] PeerLinkAddress

[0091] Dialog Token

[0092] Multi-link element )

[0094] This primitive causes a multilink establishment request frame to be sent to the peer MLD. PeerMLDAddress is set to the MLD MAC address of the peer MLD; PeerLinkAddress is set to the MAC address of the associated STA of the peer MLD (the link in which the multilink establishment request frame will be sent). One or more multilink elements may be included to carry the information required for the multilink establishment request.

[0095] The primitives for multi-link establishment in non-AP MLDs can be confirmed as follows:

[0096] MLME-MULTI-LINK-SETUP.confirm(

[0097] ...,

[0098] PeerMLDAddress

[0099] Dialog Token

[0100] Multi-link element )

[0102] This primitive is generated upon receiving a multilink establishment response frame. PeerMLDAddress is set to the MLD MAC address of the peer MLD; it includes one or more multilink elements carried in the multilink establishment response frame. Dialogue tags are used to identify the multilink establishment request / response transaction.

[0103] Non-AP MLDs indicate that one or more links are available by invoking the MLME-MULTI-LINK-SETUP.confirm primitive. This signals to the applicant that the MLD MAC has transitioned to state 3. If the MLD negotiates the use of IEEE 802.1X authentication during multilink establishment, the MLD's management entity can respond to the MLME-MULTI-LINK-SETUP.confirm (or indicate) primitive by requesting the applicant (or certifier) ​​to initiate IEEE 802.1X authentication. Therefore, in this case, authentication is driven by the decision of the non-AP MLD to initiate multilink establishment and the decision of the AP MLD to accept multilink establishment.

[0104] The primitive indicating that a request for multi-link establishment for AP MLD has been received can be as follows:

[0105] MLME-MULTI-LINK-SETUP.indication(

[0106] ...,

[0107] PeerMLDAddress

[0108] Dialog Token

[0109] Multi-link element )

[0111] This primitive can be generated upon receiving a multilink establishment request frame. PeerMLDAddress is set to the MLD MAC address of the peer MLD. It includes one or more multilink elements carried in the multilink establishment request frame.

[0112] The primitives for responding to requests for multi-link establishment against AP MLD are as follows:

[0113] MLME-MULTI-LINK-SETUP.response(

[0114] ...,

[0115] PeerMLDAddress

[0116] PeerLinkAddress

[0117] Dialog Token

[0118] Multi-link element )

[0120] This primitive causes a multilink establishment response frame to be sent to the peer MLD. PeerMLDAddress is set to the MLD MAC address of the non-APMLD; PeerLinkAddress is set to the MAC address of the affiliated STA of the peer MLD (the link in which the multilink establishment response frame will be sent). One or more multilink elements may be included to carry the information required for the multilink establishment response.

[0121] Furthermore, the primitives for requesting multi-link teardown (for both non-AP MLD and AP MLD) can be as follows:

[0122] MLME-MULTI-LINK-TEARDOWN.request(

[0123] ...,

[0124] PeerMLDAddress

[0125] Link IDs )

[0127] This primitive causes a multi-link teardown frame to be sent. The PeerMLDAddress is set to the MLD MAC address of the peer MLD. Optionally, one or more link IDs may be included, each identifying the link to be torn down.

[0128] Non-AP MLDs can request the addition of new links by re-performing multilink establishment. This can also include link quality and traffic flow information. Figure 15 A diagram 1500 depicts the communication flow between AP MLD 1502 and non-AP MLD 1504, including a multi-link reconstruction request, according to a first embodiment. During multi-link establishment, AP MLD 1502 refuses to establish link 3 due to poor link quality. Therefore, only links 1 and 2 are enabled. Subsequently, non-AP MLD 1504 can request the establishment of link 3 by sending a multi-link establishment request 1506 to AP MLD 1502, including request information such as improved link quality of link 3. The request information may include link capabilities, information identifying link 3, and link quality of link 3. AP MLD 1502 establishes the requested link based on the request information and sends a multi-link establishment response 1508 to non-AP MLD 1504, which includes information about the established link (i.e., link 3) and the TID mapping of link 3. No authentication using an IEEE 802.1X server, PMKSA establishment, etc., are performed. Advantageously, this allows for the flexible addition of new links with improved link quality.

[0129] Because the non-AP MLD 1504 is already considered to have been authenticated / associated with the AP MLD 1502 during the multi-link establishment process, the AP MLD 1504 only performs procedures related to the addition of the new requested link (e.g., AID assignment for the new link, updating the link MAC address in the association record, TID-to-link mapping, etc.). Security keys (i.e., Paired Temporary Keys (PTKs), Group Temporary Keys / (Integrity) Group Temporary Keys (GTKs / IGTKs)) can also be generated / distributed for the new link if needed. If the same PTK is used for all enabled links, the new link does not necessarily require a four-way handshake. If different GTKs / IGTKs are used for the new link, they can be distributed using a group key handshake. Alternatively, different signaling can be defined for this purpose instead of reusing the multi-link establishment (e.g., multi-link link addition request / response).

[0130] Adding a new link may require changing some parameters of the existing block acknowledgment protocol for the TID mapped to the new link. For existing block acknowledgment protocols initiated by the AP MLD (i.e., for DL ​​flows), the AP MLD may also include the relevant block acknowledgment parameters in the same frame carrying the multilink establishment response. Non-AP MLDs may also comply by initiating an update to the block acknowledgment parameters of the TID of the new link mapped to the UL flow (either in the Add Block Acknowledgment (ADDBA) request frame or carried in another frame, such as in the TID to Link Mapping response frame).

[0131] Figure 16 A diagram depicts a multilink action frame 1600 in response to the addition of a new link according to a first embodiment. While similar to multilink action frame 1400, multilink action frame 1600 also includes a multilink element (block acknowledgment establishment request) field 1602. Multilink element 1602 may include one or more link information fields, each of which includes a link ID field and one or more TID information fields. Furthermore, the one or more TID information fields may include a TID subfield, a scoreboard size subfield, and a start sequence number subfield. Therefore, the associated block acknowledgment parameters for the new link can be included in multilink element 1602.

[0132] In response to TID-to-link mapping request 1604, the non-AP MLD that receives multi-link action frame 1600 can send a TID-to-link mapping response frame back to the sending AP MLD. The TID-to-link mapping response frame can be a multi-link action frame carrying multi-link elements, and its action type is set to TID-to-link mapping response.

[0133] Dynamic enabling / disabling of links (using TID-to-link mapping) can affect block acknowledgment parameters (e.g., receive reordering buffer size, uniform BA scoreboard size, etc.) and can trigger ADDBA renegotiation during each link enabling / disabling. For example, if a new link is added, the BA scoreboard size, starting sequence number, etc., need to be specified for the new link. It is also possible to require the receiver's MLD to increase the receive (RX) reordering buffer size to be able to receive additional frames from the added link.

[0134] Figure 17A state transition diagram 1700 according to the first embodiment is depicted. The MLD can store an enumerated type state variable for each MLD that needs to communicate directly with it via one or more links through the WM (rather than maintaining the state between two affiliated STAs). For example, based on state transition diagram 1700, each MLD can be in one of four states: state 1 (unauthenticated, unassociated), state 2 (authenticated, unassociated), state 3 (authenticated, associated, awaiting RSNA authentication), and state 4 (authenticated, associated, RSNA established or not required). Successful authentication changes the MLD's state from state 1 to state 2. Successful multilink establishment (with at least one requested link) changes the MLD's state from state 2 to state 3. Confirmation of security parameters occurs during multilink establishment. MLDs performing IEEE 802.1X authentication use Open Systems Authentication. MLDs performing cryptographic authentication can use SAE authentication. MLDs performing FILS authentication use FILS authentication. SAE and FILS authentication provide mutual authentication and PMK derivation. If Open Systems Authentication is chosen instead, the authenticator or applicant initiates IEEE 802.1X authentication. Before IEEE 802.1X authentication and key installation are completed, the IEEE 802.1X controlled port in the AP MLD blocks all data frames. The IEEE 802.1X uncontrolled port allows IEEE 802.1X frames to be transmitted between the applicant and authenticator. When using SAE / FILS or IEEE Std 802.1X respectively, whether using SAE or FILS authentication via authentication frames or IEEE 802.1X authentication associated with data frames, the authentication process creates a shared encryption key between the encrypted endpoints (between the AP MLD and non-AP MLD, or between the IEEE 802.1X AS (Authentication Server) and non-AP MLD). When using IEEE Std 802.1X, the AS delivers these keys to the AP MLD, and the AP MLD and non-AP MLD use the key confirmation handshake, such as a four-way handshake or FT four-way handshake on any link, to complete the secure association establishment. When using SAE authentication, there is no AS, therefore no key delivery; a four-way handshake is performed directly between the AP MLD and non-AP MLD. The key confirmation handshake indicates when the link has been key-protected and is ready to allow normal data traffic and protected robust management frames. When performing FILS authentication, key confirmation is performed as part of the FILS exchange using associated frames. Therefore, no additional handshake is required. As long as the key confirmation handshake has been completed for at least one link, the IEEE 802.1X controlled port is considered non-blocking for non-AP MLDs. After multiple links are torn down, the IEEE 802.1X controlled port returns to an unauthorized state and blocks all data frames.

[0135] In addition, link state is maintained for each (attached STA pair) / link, and the link state can be one of the following four states:

[0136] - Not Established (Not Established / Unavailable): The AP MLD and non-AP MLD do not have all the information to enable data operations between them. Allowed frames depend on the MLD state. Data frames are not allowed. Access to the DS is not allowed.

[0137] - Established (or already set up): The AP MLD and non-AP MLD possess all the information enabling them to perform data operations on each other. Data frames (except EAPOL frames) are not allowed. Access to the DS is not allowed.

[0138] - Enabled (Activated): Both MLDs agree to begin data operations on the link. For example, at least one TID is mapped to this link, and the link's Security Relationship (RSNA) has been completed. Allows all frames permitted by the TID mapping. Allows access to the DS.

[0139] - Disabled (deactivated): Data frames (except EAPOL frames) are not allowed. Non-data frames are allowed. Access to the DS is not allowed.

[0140] For traditional STAs or non-MLD STAs, the standard authentication / association process can be used, and the status is maintained at the STA level. The establishment of multiple links between a pair of MLDs creates a unique pair of IEEE 802.1X ports, and authentication occurs only relative to these ports. Essentially, for MLDs, the roles of authenticator and applicant can be implemented at the MLD level, not the STA level.

[0141] When a STA / link is in an unestablished state, non-EOPAL data frames are not permitted for that link, even if the IEEE 802.1X controlled port is not blocked at the MLD level. Successful multilink establishment (with the requested link) changes the link's state from unestablished to established. A successful 4-way key handshake + TID-to-link mapping (at least one TID is mapped to the link) changes the link's state from established to enabled. Successful TID-to-link mapping toggles between enabled and disabled states. Multilink teardown changes the MLD state to state 1 and puts all associated STAs / links into an unestablished state. Furthermore, while no TID is mapped to a STA / link in either the established or disabled state, a security key may not yet have been generated for the STA / link in the established state. Conversely, a security key has been generated for the STA / link in the disabled state. However, in both states, no TID is mapped to the link, and the AP cannot forward data frames from the link to the DS, even if the IEEE 802.1X controlled port is not blocked.

[0142] Figure 18 An alternative state transition diagram according to the first embodiment is depicted, wherein the link can be in one of four states: established (MLD authenticated, associated, pending RSNA authentication, IEEE 802.1X controlled port blocked), enabled (authenticated, associated, RSNA established or not required, IEEE 802.1X controlled port not blocked, at least one TID mapped to the link), disabled (MLD authenticated, associated, IEEE 802.1X controlled port not blocked, no TID mapped to the link), and not established. Depending on the MLD state, the not established state includes three sub-states: not established-1 (MLD is in state 1; only Class 1 frames are allowed), not established-2 (MLD is in state 2; only Class 1 and Class 2 frames are allowed), and not established-3 (MLD is in state 3; Class 1, 2, and 3 frames are allowed, but the link does not allow non-EOPAL data frames, even if the IEEE 802.1X controlled port is not blocked at the MLD level).

[0143] According to the first embodiment, MLD can also maintain a record of the link quality of all enabled links based on link quality measurements such as signal-to-noise ratio (SNR), packet error rate (PER), RSSI, etc. Figure 19A diagram illustrating how link maintenance is performed according to the first embodiment is provided. For links with active transmissions, link quality can be measured based on transmitted / received frames. For inactive links (in a wake-up power-saving state), management frames (i.e., requested / unrequested link measurement frames) can be periodically (i.e., once per beacon interval) to access link quality. If the link quality falls below a certain threshold, the link can be considered "offline." Data frames may not be allowed on an "offline" link, or they may be transmitted with a lower MCS. The threshold can depend on the TID mapped to the link, the link's MCS requirements, etc. On the other hand, if the link quality improves above the threshold, the link can be reused as a normally active link. However, if the link quality remains below the threshold level for a certain TIMEOUT duration, the link may be disabled (i.e., via TID-to-link mapping). Advantageously, this ensures that links are established based on link quality.

[0144] According to the second embodiment, a non-AP MLD can implicitly signal to establish links during a multi-link establishment period by including only information about the links it requests to establish (i.e., link capabilities, MAC addresses, etc.). Information about links not requested to be established is not included in the multi-link establishment request. For example, the establishment request may include capability information and MAC address information indicating only the non-AP MLD's affiliated STAs for which links will be established. This can be used as the default option for requesting link establishment. Alternatively, link information can be provided, but the request not to establish a link can be implicitly signaled by setting a very low link quality value (i.e., setting the path loss to the maximum value (e.g., 128) or the link margin to the minimum value (e.g., -128) for the relevant link, for either or both of the UL / DL). For example, the establishment request may include information about the radio channel quality of multiple links that can be established between a first plurality of STAs and a second plurality of STAs, and wherein the radio channel quality is set to implicitly indicate one or more links to be established. Alternatively, as described in the previous embodiments, it is possible to provide an explicit request to establish links in the multi-link establishment frame.

[0145] If link quality information is not included in the multilink establishment request, the AP MLD can initiate a link quality assessment of the requested link, including / excluding the link on which the multilink request was received, before sending the multilink establishment response, to determine whether to establish the link. Figure 20A communication flow 2000 between AP MLD 2002 and non-AP MLD 2004 according to a second embodiment is described, including a link quality assessment step. After non-AP MLD 2004 initiates multi-link establishment by sending a multi-link request to AP MLD on link 2 to request the establishment of links 1, 2, and 3, AP MLD 2002 initiates a link quality assessment (before sending the multi-link establishment response) by sending link measurement requests 2006 and 2010 on each of links 1 and 3. In this example, the link quality assessment of the requested links excludes the link on which the multi-link request was received (i.e., link 2), but AP MLD may also choose to include this link. In response to the link measurement request, non-AP MLD 2004 sends a link measurement report 2008 to AP MLD 2002 on link 1 (in response to link measurement request 2006) and a link measurement report 2012 to AP MLD 2002 on link 3 (in response to link measurement request 2010). Based on the information collected from the link quality reports 2008 and 2012, AP MLD decided to establish / set up only links 1 and 2 (at 2014). Link 3 was rejected. Accordingly, AP MLD 2002 sent a multi-link establishment response indicating that links 1 and 2 were established.

[0146] AP MLD 2002 can use information about link quality to determine whether to establish / enable a requested link, especially when TID limitations exist on some links. However, any link quality assessment of the links needs to be performed so that multiple link establishments can be performed within any timeout values ​​associated with establishment. Furthermore, it will be understood that, although... Figure 20 The example shown illustrates the use of a link measurement request / response frame, but any other suitable management frame can also be used for this purpose.

[0147] Figure 21 An alternative state transition diagram 2100 according to the second embodiment is depicted. Alternative states for the MLD are envisioned for the state transition diagram 2100, where the state is maintained at each subordinate STA level of the MLD, similar to a traditional STA. Furthermore, the roles of certifier and applicant are implemented at the STA level (rather than at the MLD level). This version of the state machine could be used for SAE and FILS certification, i.e., without using IEEE 802.1X certification. Meanwhile, the links maintain their own states, which are the same as in the first embodiment.

[0148] For example, at 2102, both STA1 and STA are in state 1 (unauthenticated, unassociated Class 1 frame, link not established). When an STA / link is in the unestablished state, data frames are not allowed on that link. At 2104, successful (multi-link) authentication brings all affiliated STAs (i.e., STA1 and STA2) to state 2. However, excluded affiliated STAs remain in state 1. Successful multi-link establishment (with the requested link) changes the link's state from unestablished to established and changes the corresponding affiliated STA's state to state 3. Unrequested links remain in the unestablished state, and the corresponding affiliated STAs remain in state 1 or 2. For example, after successful multi-link establishment of requested link 1 (corresponding to STA1), at 2106, STA1 is in state 3, while STA2 remains in state 2. A successful 4-way / key handshake + TID-to-link mapping (at least one TID is mapped to a link) changes the link's state from established to enabled and changes the corresponding affiliated STA's state to state 4. For example, at 2108, after a successful 4-way / key handshake from 2106 + TID-to-link mapping (with one or more TIDs mapped to link 1), STA1 is in state 4 and link 1 is enabled, while STA2 remains in state 2 and link 2 is still not established. At 2110, a request for successful multi-link reconstruction of link 2 brings STA2 from state 2 (i.e., link 2 is established) into state 3. A successful TID-to-link mapping toggles the link state between enabled and disabled, but does not change the state of the associated STAs. For example, at 2114 (from 2112), after a successful TID-to-link mapping (with one or more TIDs mapped to link 2, but no TIDs mapped to link 1) and a successful 4-way / key handshake for link 2, STA 1 remains in state 4, although link 1 is disabled, and STA 2 is now in state 4, while link 2 is enabled. Alternatively, these state changes can occur from 2108 to 2114 after a successful multi-link reconstruction (i.e., requesting link 2), a successful TID-to-link mapping (where one or more TIDs are mapped to link 2, but no TIDs are mapped to link 1), and a successful 4-way / group key handshake for link 2. Furthermore, at 2116, after a successful TID-to-link mapping from 2114 (where one or more TIDs are mapped to link 1, but no TIDs are mapped to link 2), both STA 1 and STA 2 will be in state 4, where link 1 is enabled, but link 2 is disabled. It is also possible to return from 2116 to 2114 via a successful TID-to-link mapping, where one or more TIDs are mapped to link 2, but no TIDs are mapped to link 1.In addition, the multi-link teardown brings the status of all affiliated STAs to state 1 and all links to the unestablished state, which is to return to 2102.

[0149] In this example, the difference between established and disabled is that in both cases, no TID is mapped to the link. In the established state, no security key may be generated for the STA / link, but in the disabled state, a security key has been generated for the STA / link. However, in both states, no TID is mapped to the link, and the AP may not forward data frames from the link to the DS.

[0150] According to the second embodiment, as part of multi-link establishment, the non-AP MLD can request which links to be deleted (i.e., explicitly by using the delete request field in the multi-link establishment request element, or implicitly by indicating low channel quality). The non-AP MLD may also include information about the link quality of the links to be deleted (i.e., UL / DL link margin obtained during discovery, UL / DL path loss, etc.). If link quality information is unavailable, the RSSI / RCPI of beacon / probe response frames received on the link can be included as an estimate of the link quality. The non-AP MLD can consider the link quality information to make a decision on which links to request deletion. It may also consider other factors, such as the non-AP MLD choosing to request deletion of 2.4 GHz links due to coexistence issues with its Bluetooth radio, etc., or it may choose not to request deletion of certain links to save power, etc. Advantageously, this ensures that links are established based on the non-AP MLD's request and link quality.

[0151] Figure 22 A diagram illustrating the multi-link element 2200 for multi-link reconstruction requests and link deletions as described above is provided. The action type field of the multi-link element 2200 is set to multi-link establishment request. One or more link information fields may exist, such that each established link has one link information field. Each link information field may include a link ID subfield, a link MAC address subfield, a deletion request subfield, a UL link residual quantum field, a UL path loss subfield, a DL link residual quantum field, and a DL path loss subfield. The deletion request subfield can be used to indicate whether the deletion of the relevant link is requested (i.e., value 0 = not requested, value 1 = requested). For example, a value of 1 in the deletion request subfield will cause the relevant link to be removed from the multi-link set. Link quality information that may be included in the UL link residual quantum field, UL path loss subfield, DL link residual quantum field, and DL path loss subfield is optional.

[0152] Alternatively, multi-link teardown frames can also be used for link deletion. The reference figure illustrates multi-link teardown frame 2300. Figure 23 The multi-link action field is set to multi-link teardown (i.e., value is 1). One or more link ID fields can exist, so that each established link has one link ID field.

[0153] Link deletion will move the link's state to Unestablished. If each associated STA is maintained in the connected state, the corresponding STA's state will also change to state 1 (Unauthenticated, Unassociated). As long as one link remains in a state other than Unestablished, the corresponding two MLDs are considered connected. If all links are destroyed, the MLD is no longer connected, and if the state is maintained at the MLD level, the MLD's state will change to state 1.

[0154] According to the third embodiment, the AP MLD can restrict frame switching used for multi-link establishment to one of the links, i.e., the link in the highest frequency band (e.g., 6 GHz), to ensure the non-AP MLD's coverage across all links. For example, signaling can be used during the discovery phase (e.g., in a beacon / probe response frame sent on the link, or in a (reduced) neighbor report element sent on another link, etc.) to inform the link whether frame switching for multi-link establishment is permitted or not. Alternatively, the AP MLD may attempt to ensure that the BSS of all its affiliated APs has more or less the same coverage by controlling the transmit power of each affiliated AP. However, this may mean that the transmit power of an AP associated with a BSS in a lower frequency range (e.g., the 2.4 GHz band) may be significantly lower than the transmit power of an AP associated with a BSS in a higher frequency range (e.g., 5 / 6 GHz). Therefore, these may mitigate range difference problems but may not mitigate other link quality problems.

[0155] Figure 24 Illustration 2400 depicts the multilink establishment and link maintenance between an AP MLD and a non-AP MLD. According to an example, at step 2402, both MLDs are capable of operating on links 1, 2, and 3. Before initiating multilink establishment, the non-AP MLD STA can listen for beacons (passive scanning) or perform active scanning (exchanging probe request / response frames) on all three links and measure link quality. The non-AP MLD obtains authentication from the AP MLD by exchanging an authentication frame or a multilink establishment (authentication) frame on one of the links (i.e., link 3). At this stage, the MLD is in state 2. The non-AP MLD initiates a multilink establishment request and requests the establishment of links 2 and 3 by sending a multilink establishment request frame on link 3. Link 1 is excluded from the request due to poor channel quality. The non-AP MLD may also include link quality information for links 2 and 3.

[0156] The AP MLD considers establishing links 2 and 3 and decides to establish these two links. The AP MLD sends a multilink establishment response frame indicating that links 2 and 3 have been established. At this stage, the multilink set consists of links 2 and 3. In this example, the AP uses the default TID-to-link mapping on all links, and therefore the multilink establishment response frame does not include any TID-to-link mapping information. Therefore, at step 2404, the AP MLD and the non-AP MLD are now associated, and the AP MLD records relevant information about the non-AP MLD as well as information about links 2 and 3. No information about link 1 is recorded. At this stage, the MLD is in state 3, but the IEEE 802.1X controlled port remains blocked. Immediately afterwards, IEEE 802.1X authentication is performed, and security keys for links 2 and 3 are generated and distributed to the non-AP MLD. At this stage, the MLD is in state 4, and the IEEE 802.1X controlled port is not blocked. At this stage, links 2 and 3 are considered enabled, while link 1 remains in an unestablished state. At this stage, data and non-data frames can be exchanged on links 2 and 3.

[0157] After a period of time, AP MLD notices that the link quality of Link 2 has fallen below the AP threshold required for that link. It continues to monitor the link, and because the link quality has remained below the required threshold for longer than a certain TIMEOUT duration, the AP decides to disable the link by performing a TID-to-link mapping that does not map any TIDs to Link 2. At step 2406, this disables Link 2, and all traffic is redirected to Link 3.

[0158] Subsequently, both the AP MLD and the non-AP MLD maintain monitoring of the links, and after a period of time, the link quality of both Link 1 and Link 2 improves above the necessary threshold. At this stage, either the MLD (e.g., the non-AP MLD) requests the establishment of Link 1 (i.e., adding Link 1 to the multi-link set) by sending a multi-link establishment request frame. The AP MLD accepts the request, and Link 1 is added to the multi-link set. Simultaneously, at step 2408, the AP MLD also maps TID 6 and TID 7 to both Link 1 and Link 2, thereby transitioning both Link 1 and Link 2 to an enabled state. During this stage, data and non-data frames can be exchanged on Links 1, 2, and 3.

[0159] According to another example, for cases where the state is maintained at STA level, multi-link operation may have slight variations. For example, at step 2402, the affiliated STA, rather than the corresponding MLD, is in state 2. The non-AP MLD only requests the activation of links 2 and 3, but it includes information for all three links (i.e., capability information).

[0160] The AP MLD considers all three links to be established and decides to establish all three links. Therefore, the AP MLD sends a multi-link establishment response frame indicating that links 1, 2, and 3 have been established. At this stage, the multi-link set consists of links 1, 2, and 3. However, the multi-link establishment response frame includes a TID-to-link mapping element that maps all TIDs to only links 2 and 3, while no TIDs are mapped to link 1. In this case, at step 2404, all three affiliated STAs are considered associated (i.e., in state 3), but only links 2 and 3 are in the enabled state, while link 1 is in the established state. The parameters of all links (1 to 3) are recorded by the AP MLD, and all conventional processes related to association (AID allocation, etc.) are performed on all links. However, secret key generation / distribution is performed only on the enabled links. Alternatively, it is also possible that only the affiliated STA corresponding to the enabled link is considered associated (i.e., state 3), while affiliated STAs corresponding to other links are not considered associated (i.e., state 1 or 2). The parameters of all links (1 to 3) are recorded by the AP MLD, but all traditional processes related to association (AID assignment, etc.) and secret key generation / distribution are performed only on the enabled links.

[0161] After a period of time, AP MLD notices that the link quality of Link 2 has fallen below the AP threshold required for that link. It continues to monitor the link, and because the link quality has remained below the required threshold for longer than a certain TIMEOUT duration, the AP decides to disable the link by performing a TID-to-link mapping that does not map any TIDs to Link 2. This disables Link 2, and all traffic is redirected to Link 3, as at step 2406.

[0162] In addition to step 2408 described in the preceding example, the AP MLD can also perform processes related to associations (AID allocation, etc.) that were not completed in step 2404, as well as secret key distribution upon first receiving a request to enable a link. Subsequent enable / disable operations will not require this and can be accomplished via TID-to-link mapping.

[0163] Figure 25Schematic diagrams of the MLD 2500 according to various embodiments are depicted. The MLD 2500 includes a MAC-SAP 2502 for accessing the Distribution Service (DS) via controlled and uncontrolled ports, optional IEEE 802.1X port controlled and uncontrolled filtering, a link activity monitoring module 2504, a link quality assessment module 2506, and a link status module 2508. The MLD 2500 also includes three associated STAs or stations, STA1 2510a, STA2 2510b, and STA3 2510c. Each STA includes a MAC layer and a PHY layer from which transmissions occur via link 1 (for STA1 2510a), link 2 (for STA2 2510b), and link 3 (for STA3 2510c). It will be understood that the MLD 2500 can be an AP MLD (STAs 1 to 3 are affiliated APs) or a non-AP MLD (STAs 1 to 3 are affiliated non-AP STAs), and the number of links and affiliated STAs or stations can be further expanded.

[0164] Figure 26 A flowchart 2600 illustrating a communication method according to various embodiments is shown. At step 2602, a request frame is generated at a first STA included in a first plurality of STAs attached to a first MLD, the request frame including request information. At step 2604, the request frame is sent to a second STA to request multi-link establishment, wherein the second STA is included in a second plurality of STAs attached to a second MLD, and wherein multi-link establishment establishes one or more links between one or more STAs in the first plurality of STAs and corresponding one or more STAs in the second plurality of STAs based on the request information.

[0165] Figure 27 A schematic partial cross-sectional view of a STA 2700 according to the first to third embodiments is shown. The STA 2700 can be implemented for multi-link establishment and link maintenance. According to various embodiments, the STA 2700 can be implemented as a STA or AP included in a plurality of STAs or APs attached to or not attached to an AP MLD.

[0166] The various functions and operations of the STA 2700 are arranged into layers according to a hierarchical model. In this model, lower layers report to and receive instructions from higher layers according to IEEE specifications. For the sake of simplicity, the details of the hierarchical model are not discussed in this disclosure.

[0167] like Figure 27 As shown, STA 2700 may include circuitry 2714, at least one radio transmitter 2702, at least one radio receiver 2704, and multiple antennas 2712 (for simplicity and for illustrative purposes, in...). Figure 27 (The diagram depicts only one antenna). The circuitry may include at least one controller 2706 for performing tasks designed to be carried out with software and hardware assistance, including controlling communication with one or more other multilink devices in a MIMO wireless network. At least one controller 2706 may control at least one transmit signal generator 2708 for generating multilink action frames to be transmitted to one or more other STAs or MLDs via at least one radio transmitter 2702, and at least one receive signal processor 2710 for processing multilink action frames received from one or more other STAs or MLDs via at least one radio receiver 2704. At least one transmit signal generator 2708 and at least one receive signal processor 2710 may be separate modules of STA 2700 that communicate with at least one controller 2706 for the functions described above. Alternatively, at least one transmit signal generator 2708 and at least one receive signal processor 2710 may be included within at least one controller 2706. It will be apparent to those skilled in the art that the arrangement of these functional modules is flexible and may vary depending on actual needs and / or requirements. Data processing, storage and other related control devices can be provided on appropriate circuit boards and / or chipsets.

[0168] In various embodiments, at least one radio transmitter 2702, at least one radio receiver 2704, and at least one antenna 2712 may be controlled by at least one controller 2706. Furthermore, although only one radio transmitter 2702 is shown, it will be understood that there may be more than one such transmitter.

[0169] In various embodiments, at least one radio receiver 2704, together with at least one receive signal processor 2710, forms the receiver of STA 2700. The receiver of STA 2700 provides the functionality required for multi-link communication. Although only one radio receiver 2704 is shown, it will be understood that there may be more than one such receiver.

[0170] STA 2700 provides the functionality required for multilink establishment and link maintenance. For example, STA 2700 may be a first STA included in a first plurality of STAs attached to a first MLD. Circuit 2714 may generate a request frame including request information. Transmitter 2702 may send a request frame to a second STA to request multilink establishment, wherein the second STA is included in a second plurality of STAs attached to a second MLD, and wherein multilink establishment establishes one or more links between one or more STAs in the first plurality of STAs and corresponding one or more STAs in the second plurality of STAs based on the request information.

[0171] The request information may identify one or more STAs among the first plurality of STAs. The request frame may also include information about the radio channel quality of each of one or more links. The first plurality of STAs may collect information about the radio channel quality of each of one or more links before sending the request frame, and the radio channel quality includes one or more of link margin, path loss, Received Signal Strength Indication (RSSI), and Received Channel Power Indication (RCPI). The request information may also include information about the radio channel quality of multiple links that can be established between the first plurality of STAs and the second plurality of STAs, and the radio channel quality is set to implicitly indicate one or more links to be established. The first MLD may be a non-AP MLD, and the second MLD may be an AP MLD.

[0172] For example, STA 2700 may be a second STA included in a second plurality of STAs attached to a second multilink device (MLD). Receiver 2704 may receive a request frame from a first STA, wherein the first STA is included in a first plurality of STAs attached to a first MLD, and wherein the request frame includes request information and requests multilink establishment based on the request information to establish one or more links between one or more STAs in the first plurality of STAs and corresponding one or more STAs in the second plurality of STAs. Transmitter 2702 may send a response frame to the first STA to notify of the result of the multilink establishment, wherein the response frame carries information about one or more links established between one or more STAs in the first plurality of STAs and corresponding one or more STAs in the second plurality of STAs.

[0173] The request information may identify one or more STAs among the first plurality of STAs. Information about one or more links may include operating parameters of one or more links and capability information of one or more STAs among the second plurality of STAs corresponding to one or more links. The response frame may also include Traffic Identifier (TID) information for each link mapped to one or more links, wherein the first plurality of STAs are only permitted to transmit frames belonging to one or more TIDs mapped to that link on each link. The request information may include information about the radio channel quality of one or more links, wherein the second MLD determines whether to establish one or more links based on this information. The response frame may also include information related to block acknowledgment parameters for established links. The second MLD may be an AP MLD, and the first MLD may be a non-AP MLD. Frames including information identifying the public MAC address of the AP MLD may be sent by STAs included among the second plurality of STAs to advertise the AP MLD; this frame is one of a beacon frame or a probe response frame. A frame indicating that the request frame should be addressed by an AP in a second plurality of STAs can be sent by an STA included in the second plurality of STAs to announce the AP MLD. This frame is either a beacon frame or a probe response frame.

[0174] This disclosure can be implemented through software, hardware, or a combination of both. Each functional block used in the description of each of the above embodiments can be implemented partially or entirely by an LSI, such as an integrated circuit, and each process described in each embodiment can be controlled partially or entirely by the same LSI or a combination of LSIs. An LSI can be formed individually from a chip, or a chip can be formed to include some or all of the functional blocks. An LSI may include data inputs and outputs coupled thereto. Depending on the level of integration, the LSI here may be referred to as an IC, a system LSI, a super LSI, or a polar LSI. However, the technology for implementing integrated circuits is not limited to LSIs and can be implemented using dedicated circuits, general-purpose processors, or special-purpose processors. Furthermore, FPGAs (Field-Programmable Gate Arrays) that can be programmed after the LSI is manufactured, or reconfigurable processors in which the connections and settings of circuit cells housed within the LSI can be reconfigured, can be used. This disclosure can be implemented as digital or analog processing. If future integrated circuit technologies replace LSIs due to advancements in semiconductor technology or other derivative technologies, future integrated circuit technologies can be used to integrate the functional blocks. Biotechnology can also be applied.

[0175] This disclosure can be implemented by any kind of means, apparatus or system with communication capabilities (referred to as a communication device).

[0176] The communication device may include a transceiver and processing / control circuitry. The transceiver may include and / or act as both a receiver and a transmitter. As a transmitter and receiver, the transceiver may include an RF (radio frequency) module, which includes amplifiers, RF modulators / demodulators, etc., and one or more antennas.

[0177] Some non-limiting examples of such communication devices include telephones (e.g., cellular phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, netbooks), cameras (e.g., digital cameras / camcorders), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, remote health / telemedicine (remote health and medical) devices, and vehicles that provide communication capabilities (e.g., cars, airplanes, ships), and various combinations thereof.

[0178] Communication devices are not limited to portable or mobile devices, but may also include any kind of non-portable or fixed device, equipment or system, such as smart home devices (e.g., appliances, lighting, smart meters, control panels), vending machines and any other “thing” in an “Internet of Things” network.

[0179] Communication may include the exchange of data through, for example, cellular systems, wireless LAN systems, satellite systems, and various combinations thereof.

[0180] The communication device may include means, such as a controller or sensor, coupled to a communication means that performs the communication functions described in this disclosure. For example, the communication device may include a controller or sensor that generates control signals or data signals used by the communication means performing the communication functions of the communication device.

[0181] Communication equipment may also include infrastructure such as base stations, access points, and any other devices, equipment, or systems that communicate with or control devices such as those in the non-limiting examples above.

[0182] A non-limiting example of a station may be a station included in a first plurality of stations attached to a multi-link station logical entity (i.e., such as an MLD), wherein, as part of the first plurality of stations attached to the multi-link station logical entity, the stations of the first plurality of stations share a common media access control (MAC) data service interface with the upper layer, wherein the common MAC data service interface is associated with a common MAC address or traffic identifier (TID).

[0183] Therefore, it can be seen that this embodiment provides a communication device and method for operating on multiple links in order to fully realize the throughput gain of multi-link communication, especially for multi-link guaranteed retransmission.

[0184] Although exemplary embodiments have been described in the foregoing detailed description of these embodiments, it should be understood that numerous variations exist. It should also be understood that the exemplary embodiments are examples and are not intended to limit the scope, applicability, operation, or configuration of this disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing the exemplary embodiments, and it should be understood that various changes can be made to the arrangements of functions and steps and methods of operation described in the exemplary embodiments, as well as the modules and structures of the devices described in the exemplary embodiments, without departing from the scope of the subject matter set forth in the appended claims.

[0185] According to the example, there exists a second STA included in a second plurality of STAs attached to a second multilink device (MLD). The second STA includes: a receiver that receives a request frame from a first STA, wherein the first STA is included in a first plurality of STAs attached to a first MLD, and wherein the request frame includes request information and is requesting multilink establishment, the multilink establishment being based on the request information to establish one or more links between one or more STAs in the first plurality of STAs and corresponding one or more STAs in the second plurality of STAs; and a transmitter that sends a response frame to the first STA to notify of the result of the multilink establishment, wherein the response frame carries information about one or more links that have been established between one or more STAs in the first plurality of STAs and corresponding one or more STAs in the second plurality of STAs.

[0186] According to the example of the second STA, the request information identifies one or more STAs among the first plurality of STAs.

[0187] According to the example of the second STA, the information of one or more links includes the operating parameters of one or more links and the capability information of one or more STAs in the second plurality of STAs corresponding to one or more links.

[0188] According to the example of the second STA, the response frame also includes information about the Traffic Identifier (TID) of each link mapped to one or more links, and the first plurality of STAs are only allowed to send frames belonging to one or more TIDs mapped to each link on each link.

[0189] According to the example of the second STA, the requested information includes information about the wireless channel quality of one or more links, and the second MLD determines whether to establish one or more links based on this information.

[0190] According to the second STA in the example, the response frame also includes information related to the block acknowledgment parameters of the established link.

[0191] According to the second STA in the example, where the second MLD is an AP MLD and the first MLD is a non-AP MLD; and

[0192] A frame containing information identifying the public MAC address of the AP MLD is sent by one of the STAs included in the second plurality of STAs to notify the AP MLD that the frame is either a beacon frame or a probe response frame.

[0193] According to the example of the second STA, a frame sent by an STA included in a second plurality of STAs indicates that the request frame should address the AP in the second plurality of STAs, in order to notify the AP MLD that the frame is one of a beacon frame or a probe response frame.

Claims

1. An access point multi-link device, comprising: a reception section that receives an association request frame from a non-access point multi-link device (non-AP MLD), the association request frame including information for determining one or more links requested for multi-link setup and link-specific information for the one or more links requested; a control section that decides whether to accept each of the one or more links requested based on the link-specific information; and a transmission section that transmits an association response frame indicating the links accepted by the control section, the association request frame including a common information field indicating a MAC address of the non-AP MLD.

2. The access point multi-link device according to claim 1, wherein the association request frame includes a multi-link element including one or more link information fields, each link information field including information for determining one of the one or more links requested and link-specific information thereof.

3. The access point multi-link device according to claim 1, wherein the link-specific information includes parameters required for setup of the link requested.

4. The access point multi-link device according to claim 1, wherein the reception section receives an authentication frame including the MAC address of the non-AP MLD before the multi-link setup, and the transmission section transmits an authentication response frame.

5. The access point multi-link device according to claim 1, wherein the reception section receives a re-establishment request frame for setup of a new link different from one or more links setup between the non-AP MLD and the access point multi-link device (AP MLD).

6. The access point multi-link device according to claim 1, wherein the reception section receives the association request frame on one link that the non-AP MLD wishes to use as part of the multi-link setup.

7. The access point multi-link device according to claim 1, wherein the association response frame is transmitted on the link on which the association request frame is received.

8. The access point multi-link device according to claim 1, wherein the non-AP MLD has a plurality of terminal STAs associated therewith, and the access point multi-link device (AP MLD) has a plurality of access points (APs) associated therewith, and a multi-link is established between the plurality of STAs associated with the non-AP MLD and the plurality of APs associated with the AP MLD on different frequency bands.

9. A communication method for an access point multi-link device, comprising: receiving an association request frame from a non-access point multi-link device (non-AP MLD), the association request frame including information for determining one or more links requested for multi-link setup and link-specific information for the one or more links requested; deciding whether to accept each of the one or more links requested based on the link-specific information; and transmitting an association response frame indicating the links accepted, the association request frame including a common information field indicating a MAC address of the non-AP MLD. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10. The communication method according to claim 9, wherein the association request frame includes a multi-link element including one or more link information fields, each link information field including information for determining one of the one or more requested links and link-specific information thereof.

11. The communication method according to claim 9, wherein the link-specific information includes parameters required for setup of the requested link.

12. The communication method according to claim 9, wherein prior to the multi-link setup, an authentication frame including a MAC address of the non-AP MLD is received, and an authentication response frame is transmitted.

13. The communication method according to claim 9, wherein a re-establishment request frame for setting up a new link different from one or more links set up between the non-AP MLD and the access point multi-link device (AP MLD) is received.

14. The communication method according to claim 9, wherein the association request frame is received on one link that the non-AP MLD wishes to use as part of the multi-link setup.

15. The communication method according to claim 9, wherein the association response frame is transmitted on a link on which the association request frame is received.

16. The communication method according to claim 9, wherein the non-AP MLD has a plurality of terminal STAs associated therewith, and the access point multi-link device (AP MLD) has a plurality of access points (APs) associated therewith, and a multi-link is set up between the plurality of STAs associated therewith and the plurality of APs associated therewith on different frequency bands.

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