Multi-link reconfiguration and TIM broadcast procedure for multi-link operation

Abstract

Methods and apparatus for facilitating automatic link reestablishment of a multi-link device (MLD) in a wireless local area network. A non-access point (AP) MLD includes at least one processor and a station (STA). The STA includes a first STA configured to establish a first link with a first AP of the APs included in the AP MLD. The first STA is configured to receive a first message from the first AP on the first link, the first message including an advertisement to add a second AP to the AP MLD. The at least one processor is operably coupled to the STAs and is configured to determine to establish a second link between the second AP and a second one of the STAs based on the first message.

Description

Technical Field

[0001] The present disclosure generally relates to multi-link operation in a wireless communication system including a multi-link device. Embodiments of the present disclosure relate to a method and apparatus for multi-link reconfiguration in a wireless local area network communication system. Background Art

[0002] Wireless Local Area Network (WLAN) technology allows devices to access the Internet in the 2.4 GHz, 5GHz, 6GHz, or 60GHz frequency bands. WLAN is based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. The IEEE 802.11 family of standards is designed to increase speed, reliability, and extend the operating range of wireless networks.

[0003] Next generation Extremely High Throughput (EHT) WI-FI systems (e.g., IEEE 802.11be) support multiple operating bands, called links, over which access points (APs) and non-AP devices can communicate with each other. Therefore, both APs and non-AP devices are able to communicate on different bands / links, which is called Multi-Link Operation (MLO). WI-FI devices that support MLO are called Multi-Link Devices (MLDs). Using MLO, a non-access point (non-AP) MLD can discover, authenticate, associate with an AP MLD, and establish multiple links with an AP MLD. On each link established between an AP MLD and a non-AP MLD, channel access and frame exchange are possible. The component of the MLD responsible for transmission and reception on one link is called a station (STA). Summary of the invention

[0004] Embodiments of the present disclosure provide methods and apparatus for facilitating automatic reestablishment of a link between a STA affiliated to a non-AP MLD and a newly added AP affiliated to an AP MLD in a WLAN.

[0005] In one embodiment, a non-AP MLD is provided, comprising a STA and at least one processor operably coupled to the STA. The STA comprises a first STA, which is configured to establish a first link with a first AP among the APs included in the AP MLD. The first STA is configured to receive a first message from the first AP on the first link, the first message comprising a notification of adding a second AP to the AP MLD. The at least one processor is configured to determine, based on the first message, that a second link is to be established between the second AP and a second STA among the STAs.

[0006] In another embodiment, a method performed by a non-AP MLD including STAs is provided. The STA includes a first STA configured to establish a first link with a first AP among APs included in the AP MLD. The method includes the following steps: receiving a first message including a notification of adding a second AP to the AP MLD from the first AP on the first link, and determining to establish a second link between the second AP and a second STA among the STAs based on the first message.

[0007] In another embodiment, an AP MLD is provided, comprising an AP and at least one processor operably coupled to the AP. The AP comprises a first AP configured to establish a first link with a first STA among STAs included in a non-AP MLD. The at least one processor is configured to generate a first message, the first message comprising a notification of adding a second AP to the AP MLD. The first AP is configured to send a first message to the first STA on the first link. A second link is established between the second AP and a second STA among the STAs based on the first message.

[0008] Other technical features may be apparent to those skilled in the art from the following drawings, descriptions and claims.

[0009] Before the following detailed description, it may be advantageous to set forth the definitions of certain words and phrases used throughout this patent document. The term "coupling" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not these elements are in physical contact with each other. The terms "send", "receive" and "communication" and their derivatives cover both direct and indirect communication. The terms "include" and "comprise" and their derivatives mean including but not limited to. The term "or" is inclusive, meaning and / or. The phrase "associated with ... " and its derivatives mean including, included in ..., interconnected with ..., including, included in ..., connected to or with ..., coupled to or with ..., can communicate with ..., collaborate with ..., interlace, juxtapose, approach, bind to or with ..., have, have the nature of ..., have to or with ..., etc. The term "controller" means any device, system or part thereof that controls at least one operation. Such a controller can be implemented in hardware or a combination of hardware and software and / or firmware. The function associated with any particular controller can be centralized or distributed, whether local or remote. The phrase "at least one of..." when used with a list of items means that different combinations of one or more of the listed items may be used, and only one item in the list may be required. For example, "at least one of A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C. As used herein, terms such as "first" and "second" or "first" and "second" can be used to simply distinguish a corresponding component from another component, and do not limit the component in other aspects (e.g., importance or order). It should be understood that if an element (e.g., a first element) is referred to as being "coupled", "coupled to", "connected to" or "connected to" another element (e.g., a second element) with or without the terms "operably" or "communicatively", it means that the element can be coupled to another element directly (e.g., wired), wirelessly, or via a third element.

[0010] As used herein, the term "module" may include a unit implemented in hardware, software, or firmware, and may be used interchangeably with other terms (e.g., "logic," "logic block," "component," or "circuit"). A module may be a single integrated component or its smallest unit or part suitable for performing one or more functions. For example, according to an embodiment, a module may be implemented in the form of an application specific integrated circuit (ASIC).

[0011] In addition, the various functions described below may be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and embodied in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data, or a portion thereof, suitable for implementation in a suitable computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disk (CD), a digital video disk (DVD), or any other type of memory. "Non-transitory" computer-readable media excludes wired, wireless, optical, or other communication links that transmit temporary electrical or other signals. Non-transitory computer-readable media include media in which data can be permanently stored and media in which data can be stored and later rewritten, such as rewritable optical disks or erasable memory devices.

[0012] Definitions for certain other words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals represent like parts:

[0014] FIG1 illustrates an example wireless network according to various embodiments of the present disclosure;

[0015] FIG2A illustrates an example AP according to various embodiments of the present disclosure;

[0016] FIG2B illustrates an example STA according to various embodiments of the present disclosure;

[0017] 3A to 3D illustrate an example process for a non-AP MLD to request to establish a link with a newly added AP of an AP MLD according to an embodiment of the present disclosure;

[0018] 4A and 4B illustrate an example process for automatically reestablishing a link with a newly added AP of an AP MLD according to an embodiment of the present disclosure;

[0019] FIG5 shows an example format of a common information field of a basic multi-link element for MLD-level automatic link reestablishment capability indication according to an embodiment of the present disclosure;

[0020] 6 shows an example format of a per-STA profile sub-element of a basic multi-link element for STA-level automatic link reestablishment capability indication according to an embodiment of the present disclosure;

[0021] FIG. 7 shows an example of an AP adding a time indication through a beacon and a probe response frame according to an embodiment of the present disclosure;

[0022] FIG8 illustrates an example format of the STA Control field of the Per-STA Profile sub-element of the Reconfiguration Multilink element according to an embodiment of the present disclosure;

[0023] FIG. 9 illustrates an example format of the STA Information field of the Per-STA Profile sub-element of the Reconfiguration Multilink element according to an embodiment of the present disclosure;

[0024] FIG10 illustrates an example of an MLO key update process from the perspective of an AP MLD according to an embodiment of the present disclosure;

[0025] FIG11 shows an example of an MLO critical update procedure using TIM broadcast according to an embodiment of the present disclosure;

[0026] FIG. 12 shows an example format of an EHT variant TIM action field according to an embodiment of the present disclosure;

[0027] FIG. 13 illustrates an example process of using the EHT variant TIM action field from the perspective of the AP MLD according to an embodiment of the present disclosure;

[0028] FIG. 14 illustrates an example process of using the EHT variant TIM Action field from the perspective of a non-AP MLD according to an embodiment of the present disclosure;

[0029] FIG. 15 shows an example format of an EHT variant TIM action field for implementing multi-link indication according to an embodiment of the present disclosure;

[0030] FIG. 16 shows another example format of an EHT variant TIM action field implementing multi-link indication according to an embodiment of the present disclosure; and

[0031] 17 illustrates an example process for facilitating automatic re-establishment of a link between a STA affiliated to a non-AP MLD and a newly added AP affiliated to an AP MLD according to various embodiments of the present disclosure. DETAILED DESCRIPTION

[0032] FIG. 1 to FIG. 17 discussed below and the various embodiments used to describe the principles of the present disclosure in this patent document are illustrative only and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will appreciate that the principles of the present disclosure can be implemented in any suitably arranged system or device.

[0033] Multi-link (ML) reconfiguration refers to a set of processes by which an AP MLD can add one or more subordinate APs to or remove one or more subordinate APs from the AP MLD.

[0034] When an AP MLD adds one or more subordinate APs to an AP MLD, each added subordinate AP is announced in beacons and probe response frames sent by other APs subordinate to the same AP MLD through the Basic Multilink element (by changing the Maximum Number of Simultaneous Links subfield of the MLD Capabilities and Operations subfields), and through the Reduced Neighbor Report element (by including the TBTT Information field with the MLD Parameters field for the added AP).

[0035] When an AP MLD removes one or more of its subordinate APs, the AP MLD announces the removal of any subordinate APs through a Reconfigure Multilink element sent in all beacon frames of all its subordinate APs and in all probe response frames it sends until the subordinate APs are removed.

[0036] For each subordinate AP that the AP MLD intends to remove, the Reconfigure Multilink element includes a Per-STA Profile sub-element with subfields of the Per-STA Control field set as follows: The Link ID subfield shall identify the AP, the Complete Profile subfield shall be set to 0, the Removal Timer Exists subfield shall be set to 1, and the Removal Timer subfield shall be set to the number of Target Beacon Transmission Times (TBTT) for that subordinate AP before it is removed. The initial value of the Removal Timer subfield shall be longer than the MLD Maximum Idle Period. The Per-STA Profile sub-element shall not include the STA Profile field.

[0037] At the TBTT indicated by the value of the Delete Timer subfield in the sent Reconfigure Multilink element, the APMLD removes the associated AP indicated by the Link ID subfield in the STA Control field of the Per-STA Profile subelement including the Delete Timer subfield. Additionally, if the link corresponding to the removed AP is the only established link between the AP MLD and the non-AP MLD, the AP MLD shall disassociate the non-AP MLD.

[0038] In addition, at the TBTT indicated by the value of the Delete Timer subfield in the sent Reconfigure Multilink element, the associated non-AP MLD shall consider the link corresponding to the removed AP to be non-existent, and the SMEs of the affiliated non-AP STAs associated with the removed affiliated AP shall delete any information maintained for the link. After the non-AP MLD deletes any information maintained for the link corresponding to the removed AP, the non-AP MLD shall disassociate from the AP MLD if there are no other established links with the AP MLD.

[0039] Embodiments of the present disclosure recognize that the behavior of a non-AP MLD upon receiving notification from an AP MLD that a new link has been added is currently unclear. Embodiments of the present disclosure further recognize that when a link was previously established between an AP and a non-AP STA before the AP MLD removed the AP, there is no defined process that would enable the non-AP MLD to automatically re-establish a link between a STA attached to the non-AP MLD and a newly added AP attached to the AP MLD. Such a process would reduce the overhead in the frame exchanges required to re-establish a link between a newly added AP and a corresponding STA attached to the non-AP MLD.

[0040] Therefore, embodiments of the present disclosure provide a mechanism for facilitating automatic re-establishment of a link between a STA affiliated to a non-AP MLD and a newly added AP affiliated to an AP MLD.

[0041] Whenever there is a critical update on any AP attached to an AP MLD (e.g., a new attached AP is added to the AP MLD), each of the APs will include the BSS Parameter Change Count subfield in the beacon frames (in the MLD Parameters subfield of the RNR corresponding to the AP), Probe Response frames (in the MLD Parameters subfield of the RNR corresponding to the AP), or Association / Reassociation Response frames (in the Per-STA Profile of the Basic Multilink Element corresponding to the AP) sent by the AP. The BSS Parameter Change Count subfield value will be incremented for the AP whose BSS (Basic Service Set) operating parameters have changed. Whenever any AP associated with the same AP MLD has a critical update, the AP will set the Critical Update Flag in the beacons it sends.

[0042] At the non-AP MLD, after receiving the BSS Parameter Change Count subfield of the AP that has been incremented since the non-AP MLD last received the subfield, the STA associated with the AP attempts to receive a beacon or probe response frame from the AP, and any STA attached to the non-AP MLD attempts to send a probe request frame to retrieve updated information from the AP.

[0043] Traffic Information Map (TIM) frames are typically shorter than beacons and are sent at a higher data rate. Using TIM broadcasts, STAs can skip beacons and can therefore save power. TIM broadcasts can be established using a request-response based approach, where the TIM broadcast interval is a negotiated parameter. Once the TIM broadcast interval is stabilized, a sequence of target TIM transmission times (TTTT) is set.

[0044] TIM frames may also be used to indicate MLO critical updates. In this case, when a critical update occurs, the AP will increase the value of the Check Beacon field of the TIM frame. Non-AP STAs that receive the TIM frame then attempt to receive subsequent beacons to retrieve critical information. In MLO, when a critical update occurs on any AP attached to an AP MLD, all APs attached to the AP MLD will increase the value of the Check Beacon field of their respective TIM frames. Embodiments of the present disclosure recognize that when a STA attached to a non-AP MLD activates TIM broadcasts (e.g., to save power), it may unnecessarily attempt to retrieve critical information in response to a TIM frame, even though there may not be any relevant critical information for the non-AP MLD. For example, when a STA attached to a non-AP MLD receives a TIM frame indicating a critical update, the STA will wake up to retrieve the critical information, even if none of the STAs attached to the non-AP MLD has an established link with the AP with the critical update.

[0045] Therefore, embodiments of the present disclosure provide a mechanism for facilitating identification by a non-AP MLD STA of a link to which a critical update indicated by a TIM frame is applicable.

[0046] Embodiments of the present disclosure further recognize that a non-AP MLD may want to disable or delete one or more of the links that the non-AP MLD has established with the APMLD (e.g., for power saving or measurement purposes). Currently, the non-AP MLD also cannot request link deletion. Instead, if the non-AP MLD wants to remove or delete a link from the set of established links it has established with the AP MLD, the non-AP MLD needs to first disassociate with the AP MLD and then send a new association request with a reduced set of links. This disassociation and association takes a long time to be effective.

[0047] Therefore, embodiments of the present disclosure provide a mechanism for facilitating a non-AP MLD request to delete a link from its established links.

[0048] FIG1 illustrates an example wireless network 100 according to various embodiments of the present disclosure. The embodiment of the wireless network 100 shown in FIG1 is for illustration only. Other embodiments of the wireless network 100 may be used without departing from the scope of the present disclosure.

[0049] The wireless network 100 includes APs 101 and 103. The APs 101 and 103 communicate with at least one network 130, such as the Internet, a proprietary Internet Protocol (IP) network, or other data network. The AP 101 provides wireless access to the network 130 for a plurality of STAs 111-114 within a coverage area 120 of the AP 101. The APs 101-103 may communicate with each other and with the STAs 111-114 using Wi-Fi or other WLAN communication technologies.

[0050] Depending on the network type, other well-known terms may be used instead of "access point" or "AP", such as "router" or "gateway". For convenience, the term "AP" is used in this disclosure to refer to a network infrastructure component that provides wireless access to a remote terminal. In a WLAN, assuming that the AP also competes for a wireless channel, the AP may also be referred to as a STA (e.g., AP STA). In addition, depending on the network type, other well-known terms may be used instead of "station" or "STA", such as "mobile station", "subscriber station", "remote terminal", "user equipment", "wireless terminal" or "user device". For convenience, the terms "station" and "STA" are used in this disclosure to refer to remote wireless equipment that wirelessly accesses an AP or competes for a wireless channel in a WLAN, whether the STA is a mobile device (such as a mobile phone or smart phone) or is generally considered to be a fixed device (such as a desktop computer, AP, media player, fixed sensor, TV, etc.). This type of STA may also be referred to as a non-AP STA.

[0051] In various embodiments of the present disclosure, each of the APs 101 and 103 and each of the STAs 111-114 may be an MLD. In such an embodiment, the APs 101 and 103 may be AP MIDs, and the STAs 111-114 may be non-AP MIDs. Each MLD is attached to more than one STA. For ease of explanation, an AP MLD is described herein as being attached to more than one AP (e.g., more than one AP STA), and a non-AP MLD is described herein as being attached to more than one STA (e.g., more than one non-AP STA).

[0052] Dashed lines illustrate the approximate extents of coverage areas 120 and 125, which are shown as approximately circular for purposes of illustration and explanation only. It should be clearly understood that coverage areas associated with APs, such as coverage areas 120 and 125, may have other shapes, including irregular shapes, depending on the configuration of the AP and variations in the radio environment associated with natural and man-made obstacles.

[0053] As described in more detail below, one or more of the APs may include circuitry and / or programming for facilitating automatic reestablishment of links between STAs attached to non-AP MLDs and newly added APs attached to AP MLDs in the WLAN. Although FIG. 1 shows an example of a wireless network 100, various changes may be made to FIG. 1. For example, the wireless network 100 may include any number of APs and any number of STAs in any suitable arrangement. In addition, the AP 101 may communicate directly with any number of STAs and provide those STAs with wireless broadband access to the network 130. Similarly, each AP 101-103 may communicate directly with the network 130 and provide the STAs with direct wireless broadband access to the network 130. In addition, the APs 101 and / or 103 may provide access to other or additional external networks, such as an external telephone network or other types of data networks.

[0054] FIG. 2A shows an example AP 101 according to various embodiments of the present disclosure. The embodiment of the AP 101 shown in FIG. 2A is for illustration only, and the AP 103 of FIG. 1 may have the same or similar configuration. In the embodiments discussed below, the AP 101 is an AP MLD. However, the AP has a wide variety of configurations, and FIG. 2A does not limit the scope of the present disclosure to any particular implementation of the AP.

[0055] The AP MLD 101 is attached to a plurality of APs 202A-202N (which may be referred to as, for example, AP1-APn). Each of the attached APs 202a-202n includes a plurality of antennas 204a-204n, a plurality of RF transceivers 209a-209n, a transmit (TX) processing circuit 214, and a receive (RX) processing circuit 219. The AP MLD 101 also includes a controller / processor 224, a memory 229, and a backhaul or network interface 234.

[0056] The illustrated components of each subordinate AP 202a-202n may represent the physical (PHY) layer and the lower media access control (LMAC) layer in the open systems interconnection (OSI) network model. In such an embodiment, the illustrated components of the AP MLD 101 represent a single upper MAC (UMAC) layer in the OSI model and other higher layers shared by all subordinate APs 202A-202N.

[0057] For each satellite AP 202a-202n, an RF transceiver 209a-209n receives an incoming RF signal from an antenna 204a-204n, such as a signal transmitted by a STA in the network 100. In some embodiments, each satellite AP 202a-202n operates at a different bandwidth (e.g., 2.4 GHz, 5 GHz, or 6 GHz), and thus the incoming RF signal received by each satellite AP may be at a different RF frequency. The RF transceiver 209a-209n down-converts the incoming RF signal to generate an IF or baseband signal. The IF or baseband signal is sent to the RX processing circuit 219, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. The RX processing circuit 219 sends the processed baseband signal to the controller / processor 224 for further processing.

[0058] For each of the attached APs 202a-202n, the TX processing circuitry 214 receives analog or digital data (such as voice data, web data, email, or interactive video game data) from the controller / processor 224. The TX processing circuitry 214 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceivers 209a-209n receive the outgoing processed baseband or IF signals from the TX processing circuitry 214 and up-convert the baseband or IF signals to RF signals that are transmitted via the antennas 204a-204n. In embodiments where each of the attached APs 202a-202n operates at a different bandwidth (e.g., 2.4 GHz, 5 GHz, or 6 GHz), the outgoing RF signals transmitted by each of the attached APs may be at different RF frequencies.

[0059] The controller / processor 224 may include one or more processors or other processing devices that control the overall operation of the AP MLD 101. For example, the controller / processor 224 may control the reception of forward channel signals and the transmission of reverse channel signals by the RF transceivers 209a-209n, the RX processing circuit 219, and the TX processing circuit 214 according to well-known principles. The controller / processor 224 may also support additional functions, such as more advanced wireless communication functions. For example, the controller / processor 224 may support beamforming or directional routing operations, in which outgoing signals from multiple antennas 204a-204n are weighted differently to effectively direct the outgoing signals in the desired direction. The controller / processor 224 may also support OFDMA operations, in which outgoing signals are assigned to different subcarrier subsets of different recipients (e.g., different STAs 111-114). The controller / processor 224 may support any of a variety of other functions in the APMLD 101, including facilitating the automatic reconstruction of links between STAs attached to non-AP MLDs and newly added APs attached to AP MLDs in a WLAN. In some embodiments, the controller / processor 224 includes at least one microprocessor or microcontroller. The controller / processor 224 is also capable of executing programs and other processes, such as an OS, residing in the memory 229. The controller / processor 224 can move data into or out of the memory 229 as required by the executing process.

[0060] The controller / processor 224 is also coupled to a backhaul or network interface 234. The backhaul or network interface 234 allows the AP MLD 101 to communicate with other devices or systems over a backhaul connection or over a network. The interface 234 can support communication over any suitable wired or wireless connection. For example, the interface 234 can allow the AP MLD 101 to communicate over a wired or wireless local area network or over a wired or wireless connection to a larger network (such as the Internet). The interface 234 includes any suitable structure that supports communication over a wired or wireless connection, such as an Ethernet or RF transceiver. The memory 229 is coupled to the controller / processor 224. A portion of the memory 229 may include RAM, and another portion of the memory 229 may include flash memory or other ROM.

[0061] As described in more detail below, the AP MLD 101 may include circuitry and / or programming for facilitating automatic reestablishment of a link between a STA attached to a non-AP MLD and a newly added AP attached to an AP MLD in a WLAN. Although FIG. 2A shows an example of an AP MLD 101, various changes may be made to FIG. 2A. For example, the AP MLD 101 may include any number of each component shown in FIG. 2A. As a specific example, the AP MLD 101 may include a plurality of interfaces 234, and the controller / processor 224 may support a routing function to route data between different network addresses. As another specific example, although each attached AP 202a-202n is shown as including a single instance of a TX processing circuit 214 and a single instance of a RX processing circuit 219, the AP MLD 101 may include multiple instances of each of one or more of the attached APs 202a-202n (such as one for each RF transceiver). Alternatively, only one antenna and RF transceiver path may be included in one or more of the attached APs 202a-202n, such as in a conventional AP. Furthermore, various components in FIG. 2A may be combined, further subdivided, or omitted, and additional components may be added according to particular needs.

[0062] FIG. 2B illustrates an example STA 111 according to various embodiments of the present disclosure. The embodiment of STA 111 shown in FIG. 2B is for illustration only, and STAs 111-115 of FIG. 1 may have the same or similar configurations. In the embodiments discussed below, STA 111 is a non-AP MLD. However, STAs have a variety of configurations, and FIG. 2B does not limit the scope of the present disclosure to any particular implementation of a STA.

[0063] The non-AP MLD 111 is attached to a plurality of STAs 203a-203n (which may be referred to as, for example, STA1-STAn). Each attached STA 203a-203n includes an antenna 205, a radio frequency (RF) transceiver 210, a TX processing circuit 215, and a receive (RX) processing circuit 225. The non-AP MLD 111 also includes a microphone 220, a speaker 230, a controller / processor 240, an input / output (I / O) interface (IF) 245, a touch screen 250, a display 255, and a memory 260. The memory 260 includes an operating system (OS) 261 and one or more applications 262.

[0064] The components shown for each dependent STA 203a-203n may represent the PHY layer and the LMAC layer in the OSI network model. In such an embodiment, the components shown for the non-AP MLD 111 represent a single UMAC layer in the OSI model and other higher layers shared by all dependent STAs 203a-203n.

[0065] For each affiliated STA 203a-203n, the RF transceiver 210 receives an incoming RF signal sent by the AP of the network 100 from the antenna 205. In some embodiments, each affiliated STA 203a-203n operates at a different bandwidth (e.g., 2.4 GHz, 5 GHz, or 6 GHz), and thus the incoming RF signal received by each affiliated STA can be at a different RF frequency. The RF transceiver 210 down-converts the incoming RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is sent to the RX processing circuit 225, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. The RX processing circuit 225 sends the processed baseband signal to the speaker 230 (such as for voice data) or to the controller / processor 240 for further processing (such as for web browsing data).

[0066] For each affiliated STA 203a-203n, the TX processing circuit 215 receives analog or digital voice data from the microphone 220, or receives other outgoing baseband data (such as web data, email, or interactive video game data) from the controller / processor 240. The TX processing circuit 215 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceiver 210 receives the outgoing processed baseband or IF signal from the TX processing circuit 215 and up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna 205. In an embodiment where each affiliated STA 203a-203n operates at a different bandwidth (e.g., 2.4 GHz, 5 GHz, or 6 GHz), the outgoing RF signal transmitted by each affiliated STA can be at a different RF frequency.

[0067] The controller / processor 240 may include one or more processors and execute a basic OS program 261 stored in the memory 260 to control the overall operation of the non-AP MLD 111. In one such operation, the main controller / processor 240 controls the reception of forward channel signals and the transmission of reverse channel signals by the RF transceiver 210, the RX processing circuit 225, and the TX processing circuit 215 according to well-known principles. The main controller / processor 240 may also include a processing circuit configured to facilitate automatic reestablishment of a link between a STA attached to a non-AP MLD and a newly added AP attached to an AP MLD in a WLAN. In some embodiments, the controller / processor 240 includes at least one microprocessor or microcontroller.

[0068] The controller / processor 240 is also capable of executing other processes and programs resident in the memory 260, such as operations for facilitating automatic reestablishment of a link between a STA attached to a non-AP MLD and a newly added AP attached to an AP MLD in a WLAN. The controller / processor 240 may move data into or out of the memory 260 as needed for the execution of the process. In some embodiments, the controller / processor 240 is configured to execute a plurality of applications 262, such as applications for facilitating automatic reestablishment of a link between a STA attached to a non-AP MLD and a newly added AP attached to an AP MLD in a WLAN. The controller / processor 240 may operate the plurality of applications 262 based on an OS program 261 or in response to a signal received from an AP. The main controller / processor 240 is also coupled to an I / O interface 245, which provides the non-AP MLD 111 with the ability to connect to other devices such as laptop computers and handheld computers. The I / O interface 245 is a communication path between these accessories and the main controller 240.

[0069] The controller / processor 240 is also coupled to a touch screen 250 and a display 255. An operator of the non-AP MLD 111 can input data into the non-AP MLD 111 using the touch screen 250. The display 255 can be a liquid crystal display, a light emitting diode display, or other display capable of presenting text and / or at least limited graphics, such as from a website. A memory 260 is coupled to the controller / processor 240. A portion of the memory 260 can include random access memory (RAM), and another portion of the memory 260 can include flash memory or other read-only memory (ROM).

[0070] Although FIG. 2B shows an example of a non-AP MLD 111, various changes may be made to FIG. 2B. For example, various components in FIG. 2B may be combined, further subdivided, or omitted, and additional components may be added as needed. In a specific example, one or more affiliated STAs 203a-203n may include any number of antennas 205 for MIMO communication with the AP 101. In another example, the non-AP MLD 111 may not include voice communications, or the controller / processor 240 may be divided into multiple processors, such as one or more central processing units (CPUs) or one or more graphics processing units (GPUs). In addition, although FIG. 2B shows a non-AP MLD 111 configured as a mobile phone or smart phone, the non-AP MLD may be configured to operate as other types of mobile or fixed devices.

[0071] Embodiments of the present disclosure provided herein below enable a non-AP MLD to automatically reestablish a link between a STA attached to the non-AP MLD and a newly added AP attached to the AP MLD when a link was previously established between an AP and a non-AP STA before the AP MLD removed the AP.

[0072] As described above, when the AP MLD adds one or more new subordinate APs to the AP MLD, each added subordinate AP is announced in beacon and probe response frames by other APs affiliated with the same AP MLD. In one embodiment, when the AP MLD announces in its BSS that a new AP has been added (and the new AP is affiliated with the same AP MLD), the non-AP MLD in the BSS, upon observing the announcement from the AP MLD, may send a request to the AP MLD for establishing a link between the newly added AP affiliated with the AP MLD and the corresponding STA affiliated with the non-AP MLD. Upon receiving the request from the non-AP MLD, the AP MLD may accept the request to establish a link or reject the request, and the AP MLD may send a response frame to indicate acceptance or rejection of the request.

[0073] 3A-3D illustrate an example process for a non-AP MLD to request to establish a link with a newly added AP of an AP MLD according to an embodiment of the present disclosure. In this example, the AP MLD may be AP MLD 101, and the non-AP MLD may be non-AP MLD 111. Although AP MLD 101 is initially shown as an AP MLD with two attached APs, and non-AP MLD 111 is shown as a non-AP MLD with three attached non-AP STAs, it should be understood that the process may be applied to a suitable MLD with any number of attached APs or STAs. For ease of explanation, it should be understood that references to AP MLDs and non-AP MLDs in further embodiments below refer to AP MLD 101 and non-AP MLD 111, respectively.

[0074] Referring to FIG3A , the initial state of the system is shown. The AP MLD initially has 2 subordinate APs (AP1 and AP2), and the non-AP MLD has 3 subordinate STAs (STA1, STA2, and STA3). Two links (Link 1 between STA1 and AP1 and Link 2 between STA2 and AP2) are established between the AP MLD and the non-AP MLD.

[0075] 3B , the AP MLD adds a new subordinate AP (AP3) and announces the addition in its BSS. For example, the APMLD announces the newly added AP3 in beacons such as beacon frame 302 and probe response frames.

[0076] 3C, after receiving the beacon frame 302, the non-AP MLD sends a request 304 to the AP MLD to establish a third link between the newly added AP3 attached to the AP MLD and the STA3 attached to the non-AP MLD. The AP MLD accepts the request from the non-AP MLD in a response frame 306 sent to the non-AP MLD.

[0077] Referring now to FIG. 3D , after the non-AP MLD receives the response frame 306 , a new link 308 (eg, link 3 ) is established between the AP MLD and the non-AP MLD.

[0078] In the above process, the request and response based method has an overhead problem. For example, if there are many non-AP MLDs sending such requests to the AP MLD to establish a link with the newly added AP, this will cause significant overhead to the AP MLD and will take up significant talk time. In addition, this method does not consider any previous information about whether the non-AP MLD has previously established a link with the newly added AP attached to the APMLD.

[0079] According to one embodiment, if a STA attached to a non-AP MLD was previously associated with an AP attached to an AP MLD but removed from the AP MLD, and if the AP is added to the AP MLD again after a period of unavailability, the link between the newly added AP and the STA can be automatically reestablished when the AP is re-added to the AP MLD. This will save a lot of overhead (e.g., due to request-response message exchanges) in dense networks with many non-AP MIDs.

[0080] 4A-4B illustrate an example process for automatically reestablishing a link with a newly added AP of an AP MLD according to an embodiment of the present disclosure. In the initial state of the system in this example, the AP MLD has 2 subordinate APs (AP1 and AP2), and the non-AP MLD has 3 subordinate STAs (STA1, STA2, and STA3). Two links (Link 1 between STA1 and AP1 and Link 2 between STA2 and AP2) are established between the AP MLD and the non-AP MLD. The AP MLD intends to add AP3 to the AP MLD.

[0081] 4A , AP MLD announces the upcoming addition of AP3 by including a Reconfigure Multilink element in the beacon and probe response frames (eg, beacon frame 402 ) it sends on Link 1 and Link 2 .

[0082] In this example, STA3 attached to the non-AP MLD was previously associated with AP3 when it was previously attached to the AP MLD. Therefore, as shown in FIG3B , when AP3 is re-added to the AP MLD, the link 404 (eg, link 3) of STA3 and AP3 is automatically re-established.

[0083] Not all MLDs may have the capability to automatically reestablish a link when a new AP has been added to the AP MLD. According to some embodiments, MLDs that do have this capability may indicate this using a capability indication message. According to one such embodiment, this may be an MLD level capability indication.

[0084] 5 shows an example format of a common information field 500 of a basic multilink element for MLD-level automatic link reestablishment capability indication according to an embodiment of the present disclosure. In this example, the support automatic link addition subfield 502 in the MLD capability and operation subfield 504 indicates whether the MLD supports automatic link addition. If the support automatic link addition subfield 502 is set to 1, it indicates that all STAs affiliated with the MLD support automatic link addition. If the subfield is set to 0, it may indicate that none of the STAs support the automatic link addition feature.

[0085] According to other embodiments, the automatic link reestablishment capability may also be indicated on a per-STA basis. According to one such embodiment, support for this functionality may be indicated in a per-STA configuration file of the base multi-link element.

[0086] 6 shows an example format of a per-STA profile sub-element 600 of a basic multi-link element for STA-level automatic link reestablishment capability indication according to an embodiment of the present disclosure. In this example, if the support automatic link addition sub-field 602 in the STA control field 604 of the per-STA profile sub-element of the basic multi-link element is set to 1, it will indicate that the STA affiliated to the MLD and corresponding to the per-STA profile supports automatic link establishment. Otherwise, the STA does not support this function.

[0087] According to one embodiment, before adding a new AP, the AP MLD may announce the time when the new AP is expected to be added in advance. The AP affiliated with the AP MLD may announce the time of the new AP addition in the beacon and probe response frames sent by the AP (e.g., according to the TBTT). According to one embodiment, the AP affiliated with the AP MLD may start announcing the new AP addition time at least a threshold amount of time before the AP MLD adds the new AP. This can help non-AP MLDs that intend to establish a link with the new AP to better manage traffic.

[0088] According to one embodiment, the AP affiliated with the AP MLD can indicate the time of new AP addition in the reconfiguration multilink element sent by the AP in the beacon and probe response frame. For example, the AP addition timer subfield can be introduced in the reconfiguration multilink element to indicate the AP addition timer subfield.

[0089] 7 shows an example of adding time indication by an AP of a beacon and a probe response frame according to an embodiment of the present disclosure. In this example, an add timer subfield 702 is added to a reconfigure multilink element 704 in a beacon frame 706.

[0090] In some embodiments, the Add Timer subfield may be conditionally present in the Reconfigure Multilink element. Its presence may be indicated by the Add Timer Present subfield of the STA Control field of the Per STA Profile subelement of the Reconfigure Multilink element.

[0091] 8 shows an example format of a STA control field 800 of a per-STA profile sub-element of a reconfiguration multilink element according to an embodiment of the present disclosure. In this example, the STA control field 800 includes an add timer presence sub-field 802. If the add timer presence sub-field 802 is set to 1, it indicates that the add timer sub-field is present in the per-STA profile field of the reconfiguration multilink element. Otherwise, the add timer sub-field is not present in the per-STA profile sub-element of the reconfiguration multilink element.

[0092] According to one embodiment, the Add Timer subfield may be present in the STA Information field of the Per-STA Profile subelement of the Reconfigure Multilink element.

[0093] 9 shows an example format of the STA Information field 900 of the per-STA profile sub-element of the reconfiguration multilink element according to an embodiment of the present disclosure. In this example, the STA Information field 900 includes an Add Timer sub-field 902. The Add Timer sub-field 902 indicates the time when the AP MLD intends to add a new AP corresponding to the per-STA profile sub-element of the reconfiguration multilink element in TBTT.

[0094] According to one embodiment, for the scenario where an AP MLD adds a new AP, if a STA was previously associated with an AP before the AP was removed, after the AP is re-added, a link between the newly added AP and the STA is established, and the traffic identifier (TID) mapped on the newly established link with the newly added AP may follow the same mapping as the TID mapped on the link before the AP was removed. According to another embodiment, immediately after the AP is added and the link is reestablished, all TIDs are mapped on the reestablished link. According to yet another embodiment, immediately after the AP is re-added, the link is reestablished, but no TID is mapped on the link corresponding to the newly added AP.

[0095] According to another embodiment of a scenario in which the AP MID adds a new AP, no TID is mapped onto the link between the STA and the newly added AP immediately after the link is established or set up between the STA and the newly added AP, regardless of whether the STA was previously associated with the AP.

[0096] According to another embodiment, when the non-AP MLD sends a request to establish a link with the newly added AP (e.g., as shown in FIG. 3C ), the non-AP MLD may include a TID-to-link mapping element along with the request frame. The TID-to-link mapping element will indicate the TID-to-link mapping preferred by the non-AP MLD when establishing a link with the newly added AP. In a corresponding response frame, the AP may indicate whether the AP MLD accepts the request to establish a link with the newly added AP and the proposed TID-to-link mapping of the non-AP MLD. The AP MLD may accept both the request to establish a link and the proposed TID-to-link mapping, reject both the request to establish a link and the proposed TID-to-link mapping, or accept the request to establish a link but reject the proposed TID-to-link mapping.

[0097] According to one embodiment, in the case where the AP MLD accepts the request to establish a link but rejects the proposed TID-to-link mapping, a link is established between the newly added AP and the corresponding STA affiliated with the non-AP MLD, but the link is not enabled.

[0098] According to one embodiment, when the non-AP MLD sends a request to establish a link with the newly added AP, the non-AP MLD may include information about partial TID to link mapping, which will indicate the non-AP MLD's preferred TID mapping for the link corresponding to the newly added AP.

[0099] According to one embodiment, whether a STA was previously associated with an AP before the AP was removed from the AP MLD and whether the STA is eligible to automatically reestablish a link with the AP when the AP is re-added by the AP MLD may be determined based on the following criteria (or any subset of these criteria):

[0100] -Whether the BSS identifier (BSSID) of the newly added AP matches the BSS identifier of the AP to which the STA was previously associated.

[0101] -Whether the frequency band and operating channel of the newly added AP match the frequency band and operating channel of the AP to which the STA was previously associated.

[0102] -Whether the bandwidth of the newly added AP matches the bandwidth of the AP to which the STA was previously associated.

[0103] - Whether the subset of information contained in the EHT Operation Element corresponding to the newly added AP matches the subset of APs with which the STA was previously associated.

[0104] - Whether the subset of information corresponding to the newly added AP contained in the HE Operation element matches the subset of information of the AP with which the STA was previously associated.

[0105] -Whether the BSSID information field of the neighbor report element corresponding to the newly added AP matches the BSSID information field of the AP to which the STA was previously associated.

[0106] FIG10 shows an example of an MLO critical update process 1000 from the perspective of an AP MLD according to an embodiment of the present disclosure. In the example process 1000, AP3 has a critical update. Therefore, as described above, each AP attached to the AP MLD sets the critical update flag to 1 in the beacon it sends, and the BSS parameter change count subfield for AP3 will be incremented.

[0107] FIG11 shows an example of an MLO critical update process 1100 using TIM broadcast according to an embodiment of the present disclosure. In the example of FIG11 , two links are established between the AP MLD and the non-AP MLD—Link 1 between AP1 and STA1, and Link 2 between AP2 and STA2. The non-AP MLD is not associated with AP3, which is attached to the AP MLD.

[0108] In the example process 1100, AP3 has a critical update. Therefore, as described above, each AP attached to an AP MLD increases the value of the Check Beacon subfield of its TIM frame. For example, as shown in Figure 11, AP1 will set the Check Beacon subfield in the TIM frame 1102 to 1. STA1 will wake up to retrieve only the critical update information to find that - because the non-AP MLD to which STA1 belongs is not associated with AP3 - there is no relevant information for the non-AP MLD. This will disrupt the power saving of the TIM non-AP MLD. This same problem may also occur if the legacy STA is associated with an AP MLD instead of the non-AP MLD shown.

[0109] According to one embodiment, in order to solve the above critical update indication problem of TIM broadcast, an EHT variant TIM action field may be introduced. Other names may also be used to refer to the new action field. The EHT variant TIM action field may contain link ID information to indicate the link on which the AP MLD has a critical update.

[0110] 12 shows an example format of an EHT variant TIM Action field 1200 according to an embodiment of the present disclosure. The example EHT variant TIM Action field 1200 includes a Check Beacon Link ID subfield 1202. The Check Beacon Link ID subfield 1202 may indicate a link on which an operating AP attached to the AP MLD has a critical update.

[0111] In FIG. 12 , the definition and explanation of the Category subfield, the Unprotected WNM Action subfield, the Check Beacon subfield, the Timestamp subfield, and the TIM Element subfield are the same as those of the existing TIM frame Action field.

[0112] According to one embodiment, referring to FIG. 12 , if the non-AP MLD has established a link corresponding to Link 1 with the AP MLD, the non-AP MLD may attempt to retrieve a critical update from the AP MLD, the non-AP MLD being associated with the AP MLD and receiving the EHT variant TIM Action field 1200 for a first AP that is affiliated with the same AP MLD and operating on the first link (e.g., Link 1) indicated in the Check Beacon Link ID subfield 1202.

[0113] 13 illustrates an example process 1300 of using the EHT variant TIM Action field from the perspective of the AP MLD according to an embodiment of the present disclosure. The EHT variant TIM Action field used in the example process 1300 may be the EHT variant TIM Action field 1200.

[0114] 14 illustrates an example process 1400 of using the EHT variant TIM Action field from the perspective of a non-AP MLD according to an embodiment of the present disclosure. The EHT variant TIM Action field used in the example process 1400 may be the EHT variant TIM Action field 1200.

[0115] According to one embodiment, the EHT variant TIM action field field may be used to indicate critical updates corresponding to multiple links on which the sending AP MLD is operating. To achieve this, the EHT variant TIM action field may include a bitmap to indicate that there are critical updates and links that are recommended to check beacons, and one or more TIM elements corresponding to the links indicated in the link ID bitmap of the EHT variant TIM action field.

[0116] FIG. 15 shows an example format of an EHT variant TIM action field 1500 for implementing multi-link indication according to an embodiment of the present disclosure. The example EHT variant TIM action field 1500 includes a check beacon link ID bitmap subfield 1502 and a TIM information set 1504. The check beacon link ID bitmap subfield 1502 indicates that there is a critical update and requests one or more links to check the beacon. The TIM information set 1504 includes one or more TIM elements 1506 corresponding to the links indicated in the check beacon link ID bitmap subfield 1502. FIG. 15 shows an example format of a TIM information set 1504.

[0117] According to one embodiment, referring to FIG15 , the number of TIM elements 1506 present in the TIM information set 1504 may correspond to the number of 1s present in the check beacon link ID bitmap subfield 1502. According to one embodiment, the first TIM element 1506 corresponds to the link corresponding to the first 1 in the check beacon link ID bitmap subfield 1502, and so on. For example, if the check beacon link ID bitmap subfield 1502 is set to 0010100000000000, the TIM information set 1504 may contain two TIM elements 1506, wherein the first TIM element 1506 corresponds to link 3 and the second TIM element 1506 corresponds to link 5.

[0118] In FIG. 15 , the definition and explanation of the Category subfield, the Unprotected WNM Action subfield, the Check Beacon subfield, the Timestamp subfield, and the TIM Element subfield are the same as those of the existing TIM frame Action field.

[0119] 16 shows another example format of an EHT variant TIM action field 1600 for implementing multi-link indication according to an embodiment of the present disclosure. In the example EHT variant TIM action field 1600, the same TIM element 1506 can be used for critical updates of multiple links, as indicated in the Check Beacon Link ID Bitmap subfield 1502 of the EHT variant TIM action field 1600.

[0120] As described above, the non-AP MLD may want to disable or delete one or more of the links that the non-AP MLD has established with the AP MLD (e.g., for power saving or measurement purposes). According to one embodiment, the non-AP MLD associated with the AP MLD may send a request to the AP MLD to delete or remove a link from the set of established links between the AP MLD and the non-AP MLD over any enabled link between the AP MLD and the non-AP MLD.

[0121] According to one embodiment, when the non-AP MLD sends a link removal request, the non-AP MLD may indicate one or more links that the non-AP MLD requests to be removed. A link ID bitmap may be included in the link removal request to indicate the links that the non-AP MLD requests to be removed. If a bit position in the link ID bitmap is If set to 1, it indicates that the non-AP MLD requests to delete the first link.

[0122] According to one embodiment, when the non-AP MLD sends a request to remove or delete one or more established links, the non-AP MLD ensures that the non-AP MLD does not request removal of all established links between the AP MLD and the non-AP MLD.

[0123] According to one embodiment, upon receiving a link removal request from a non-AP MLD, the AP MLD may send a link removal response to the non-AP MLD indicating whether the AP MLD accepts or rejects the request. The link removal response may also suggest an alternative link set for link removal.

[0124] According to one embodiment, upon receiving a link removal request from a non-AP MLD, if the AP MLD accepts the request, the requested link is removed for the non-AP MLD. Other links not requested to be removed are not affected by the link removal of the requested link.

[0125] According to one embodiment, when the non-AP MLD sends a request to remove or delete one or more established links, the non-AP MLD may also include link removal timing information, ie, information related to the time when, after or before the non-AP MLD requests to remove the link.

[0126] According to one embodiment, upon receiving a link removal request including link removal timing information from a non-AP MLD, if the AP MLD accepts the request, the requested link is removed for the non-AP MLD at the indicated time. The AP MLD may also include the link removal timing information in a link removal response frame.

[0127] FIG. 17 illustrates an example process 1700 for facilitating automatic reestablishment of a link between a STA attached to a non-AP MLD and a newly added AP attached to an AP MLD according to various embodiments of the present disclosure. The process 1700 of FIG. 17 is discussed as being performed by a non-AP MLD, but it should be understood that the corresponding AP MLD performs the corresponding process. In addition, for convenience, the process 1700 of FIG. 17 is discussed as being performed by a WI-FI non-AP MLD including a plurality of STAs, each STA including a transceiver configured to form a link with a corresponding AP of a WI-FI AP MLD attached to which the non-AP MLD is associated. However, it should be understood that any suitable wireless communication device may perform these processes.

[0128] 17 , the process 1700 begins with the non-AP MLD generating a capability indication message indicating that a first STA of the non-AP MLD can automatically re-establish a previously established link when a new AP is added to the AP MLD (step 1705 ).

[0129] Then, the non-AP MLD sends a capability indication message to the AP MLD (step 1710).

[0130] Next, the non-AP MLD receives a first message from the AP MLD including a notification of adding a new AP to the AP MLD (step 1715). For example, a transceiver of one of the STAs of the non-AP MLD that has established a link with a corresponding AP of the AP MLD may receive the first message from the corresponding AP. In some embodiments, the first message includes an indication of a time at which the new AP will be added to the AP MLD. In addition, the first message may be received at least a predetermined threshold amount of time before the indicated time at which the new AP will be added to the AP MLD.

[0131] The non-AP MLD then determines to establish a new link between the new AP and the transceiver of the first STA (step 1720). The first STA is a STA that is not currently associated with any AP of the AP MID. If the first message includes an indication of the time when the new AP will be added to the AP MLD, the non-AP MLD may determine to establish the new link at or after the indicated time.

[0132] In some embodiments, the non-AP MLD determines based on the first message that the first STA has previously established a link with the new AP (step 1725). In this case, the non-AP MLD automatically re-establishes the previously established link as a new link between the first STA and the new AP (step 1730). If the previous TID-to-link mapping was applied to the previously established link, the previous TID-to-link mapping may be applied to the new link.

[0133] In step 1725, the non-AP MLD can determine whether the identification information or capability information associated with the new AP matches the identification information or capability information associated with the first AP with which the first STA was previously associated, and based on determining that at least some of the identification information or capability information associated with the new AP matches the identification information or capability information associated with the first AP, determine that the first STA has previously established a link with the new AP.

[0134] In some embodiments, instead of automatically reestablishing the link, the non-AP MLD generates a second message including a request to establish a new link and an indication of a preferred TID-to-link mapping for the new link (step 1735). In this case, the non-AP MLD then sends the second message to the AP MLD (step 1740).

[0135] In some embodiments, when a new link is established, all TIDs are mapped to the new link. Alternatively, when a new link is established, no TIDs are mapped to the new link.

[0136] The above flow charts illustrate example methods or processes that can be implemented according to the principles of the present disclosure, and various changes can be made to the methods or processes shown in the flow charts. For example, although shown as a series of steps, various steps can overlap, occur in parallel, occur in different orders, or occur multiple times. In another example, a step can be omitted or replaced by another step.

[0137] Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be suggested to those skilled in the art. The present disclosure is intended to cover these changes and modifications that fall within the scope of the appended claims. The description in this application should not be interpreted as implying that any particular element, step or function is an essential element that must be included in the scope of the claims. The scope of the patent subject matter is defined by the claims.

Claims

1. A non-access point (AP) multi-link device (MLD), include: A station (STA), including a first STA, wherein the first STA is configured to establish a first link with a first AP among the APs included in the AP MLD; as well as at least one processor operably coupled to the STA, The first STA is configured to receive a first message from the first AP on the first link, the first message including a notification of adding a second AP to the AP MLD, and The at least one processor is configured to determine, based on the first message, that a second link is to be established between the second AP and a second STA among the STAs.

2. The non-AP MLD according to claim 1, in, The at least one processor is further configured to: determining, based on the first message, that the first STA has a previously established link with the second AP; as well as The previously established link is re-established as the second link between the second STA and the second AP.

3. The non-AP MLD according to claim 2, in: The at least one processor is further configured to generate a capability indication message indicating that the second STA is capable of reestablishing a previously established link when a new AP is added to the AP MLD, and The first STA is further configured to send the capability indication message to the first AP.

4. The non-AP MLD according to claim 2, in, The at least one processor is further configured to: mapping a previous traffic identifier (TID) or all TIDs applied to the previously established link to the second link; or The TID is not mapped to the second link.

5. The non-AP MLD according to claim 2, in, The at least one processor is further configured to: determining whether identification information or capability information associated with the second AP matches identification information or capability information associated with a third AP with which the second STA was previously associated; as well as Based on determining that at least some of the identification information or capability information associated with the second AP matches the identification information or capability information associated with the third AP, it is determined that the second STA has the previously established link with the second AP.

6. The non-AP MLD of claim 1 , wherein the at least one processor is further configured to generate a second message, the second message comprising a request to establish the second link and an indication of a mapping of a preferred traffic identifier (TID) to a link for the second link, and The first STA is further configured to send the second message to the first AP.

7. The non-AP MLD according to claim 1, in: The first message includes an indication of a time at which the second AP will be added to the AP MID, The first message is received at least a predetermined threshold amount of time before an indicated time at which the second AP is to be added to the AP MLD, and The at least one processor is further configured to determine that the second link is to be established at or after the indicated time.

8. A method performed by a non-access point (AP) multi-link device (MLD), the non-access point (AP) multi-link device (MLD) comprising a station (STA), the STA comprising a first STA configured to establish a first link with a first AP among APs included in the AP MLD, the method include: receiving a first message from the first AP on the first link, the first message comprising an advertisement to add a second AP to the AP MLD; as well as A determination is made based on the first message that a second link is to be established between the second AP and a second STA among the STAs.

9. The method according to claim 8, further comprising: include: determining, based on the first message, that the first STA has a previously established link with the second AP; as well as The previously established link is re-established as the second link between the second STA and the second AP.

10. The method according to claim 9, further comprising: include: generating a capability indication message, the capability indication message indicating that the first STA of the non-AP MLD is capable of re-establishing a previously established link when a new AP is added to the AP MLD; as well as Sending the capability indication message to the first AP.

11. The method according to claim 9, further comprising: include: mapping a previous traffic identifier (TID) or all TIDs applied to the previously established link to the second link; or The TID is not mapped to the second link.

12. The method according to claim 9, further comprising: include: determining whether identification information or capability information associated with the second AP matches identification information or capability information associated with a third AP with which the second STA was previously associated; as well as Based on determining that at least some of the identification information or capability information associated with the second AP matches the identification information or capability information associated with the third AP, it is determined that the second STA has a previously established link with the second AP.

13. The method according to claim 8, further comprising: include: generating a second message comprising a request to establish the second link and an indication of a preferred TID-to-link mapping for the second link; as well as Send the second message to the first AP.

14. The method according to claim 8, in: The first message includes an indication of a time at which the second AP will be added to the AP MID, The first message is received at least a predetermined threshold amount of time before an indicated time at which the second AP is to be added to the AP MLD, and The method further includes determining to establish the second link at or after the indicated time.

15. An access point (AP) multi-link device (MLD), include: The AP includes a first AP configured to establish a first link with a first STA among stations (STAs) included in the non-AP MLD; as well as at least one processor operably coupled to the AP, the at least one processor configured to generate a first message, the first message comprising an advertisement to add a second AP to the AP MLD, wherein the first AP is configured to send the first message to the first STA on the first link, and A second link is established between the second AP and a second STA among the STAs based on the first message.

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