Method and apparatus for tdls discovery of NSTR constrained devices

Abstract

Methods and apparatus for assisting a multi-link device (MLD) in discovering a point-to-point (P2P) direct link that overlaps with a non-simultaneous transmit / receive (NSTR) constrained link of the MLD without violating the NSTR constraints. A non-access point (AP) MLD includes a station (STA) configured to form a link with an AP of the AP MLD, and at least one processor. Two of the links form an NSTR link pair. The at least one processor is configured to generate a first message that identifies a first link in the NSTR link pair as a target link for establishing a P2P direct link with the peer STA. The STA corresponding to one of the two links in the NSTR link pair is configured to transmit a first message to one of the APs. The STA corresponding to a second link, which is not the target link, of the two links in the NSTR link pair is configured to wait for a predetermined period of time after the first message is transmitted before uplink (UL) transmission is performed to the second AP.

Description

Technical Field

[0001] The present disclosure generally relates to point-to-point (P2P) communication in a wireless communication system including a multi-link device (MLD) with non-simultaneous transmit / receive (NSTR) constraints. Embodiments of the present disclosure relate to methods and apparatus for facilitating discovery of P2P direct links that overlap with NSTR-constrained links between peer MLDs in a wireless local area network (WLAN) communication system. Background Art

[0002] WLAN technology allows devices to access the Internet in the 2.4GHz, 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 and reliability and extend the operating range of wireless networks.

[0003] The next generation of extremely high throughput (EHT) WI-FI systems (e.g., IEEE 802.11be) supports multiple operating bands (referred to as links) through 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 referred to as multi-link operation (MLO). WI-FI devices that support MLO are called multi-link devices (MLDs). Using MLO, non-access point (non-AP) MLDs can discover, authenticate, associate, and establish multiple links with AP MLDs. On each link established between AP MLDs and non-AP MLDs, channel access and frame exchange are possible. The component of the MLD responsible for sending and receiving on a link is called a station (STA). Summary of the invention

[0004] Technical issues

[0005] There are two variants of multi-link operation. The first type is simultaneous transmit / receive (STR), in which STAs attached to the MLD can transmit and receive independently of each other. The second variant is non-simultaneous transmit / receive (NSTR), in which the links formed by the attached STAs do not form a STR link pair. If the link pair forms an NSTR link pair, the transmission on one link may cause interference to the other link due to signal leakage that the device's radio transceiver cannot withstand. Therefore, the two STAs forming the NSTR link pair cannot send and receive frames at the same time. Since the STR operating mode requires two or more radio devices with sufficient isolation, it is expected that AP MLDs will have STR capabilities, while non-AP MLDs may potentially not have STR capabilities.

[0006] Solution to the problem

[0007] Embodiments of the present disclosure provide methods and apparatus for assisting a non-AP MLD in discovering a P2P direct link that overlaps with an NSTR-constrained link without violating the NSTR constraint.

[0008] In one embodiment, a non-AP MLD is provided. The non-AP MLD includes a STA configured to form a link with an AP of the AP MLD, wherein two links in the link form an NSTR link pair constrained by NSTR, and a first STA in the STA forms a first link in the NSTR link pair with a first AP in the AP, and a second STA in the STA forms a second link in the NSTR link pair with a second AP in the AP. At least one processor is operably coupled to the STA. The at least one processor is configured to generate a first message, which identifies the first link in the NSTR link pair as a target link for establishing a P2P direct link with a peer STA. The STA corresponding to one of the two links is configured to send the first message to one of the first AP or the second AP. The second STA corresponding to the second link in the NSTR link pair that is not the target link is configured to wait for a predetermined time period after the first message is sent and before performing UL transmission to the second AP.

[0009] In another embodiment, a wireless communication method performed by a non-AP MLD is provided, the non-AP MLD including a first STA forming a first link with a first AP of the AP MLD, and a second STA forming a second link with a second AP of the AP MLD, so that the first link and the second link form an NSTR link pair subject to NSTR constraints. The method includes the steps of generating a first message identifying a first link in the NSTR link pair as a target link for establishing a P2P direct link with a peer STA, sending the first message to one of the first AP or the second AP through one of the first link and the second link in the NSTR link pair, and waiting for a predetermined period of time after the first message is sent and before performing UL transmission to the second AP through the second link in the NSTR link pair that is not the target link.

[0010] In another embodiment, an AP MLD is provided. The AP MLD includes an AP configured to form a link with a STA of a non-AP MLD, and at least one processor operably coupled to the AP. A first AP among the APs is also configured to form a link with a peer STA. Two links among the links formed with the STA of the non-AP MLD form an NSTR link pair constrained by NSTR. An AP among the APs corresponding to one of the two links in the NSTR link pair is configured to receive a first message from the non-AP MLD. The at least one processor is configured to determine that the first message identifies the first link in the NSTR link pair as a target link for establishing a P2P direct link with the peer STA. A second AP among the APs corresponding to the second link in the NSTR link pair that is not a target link is configured to wait for a predetermined time period after the first message is received and before requesting uplink UL transmission to the non-AP MLD.

[0011] Other technical features may be clear to those skilled in the art from the following drawings, descriptions and claims.

[0012] Before carrying out the following specific embodiments, 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 include both direct and indirect communication. The terms "include" and "comprise" and their derivatives refer to including but not limited to this. The term "or" is inclusive, referring to and / or. The phrase "associated with..." and its derivatives refer to including, being included in, interconnected with, being included in, being connected to or connected with, being coupled to or coupled with, being communicable with, collaborating with, interweaving, juxtaposing, being close to, being bound to or bound with, having, having the nature of, having a relationship with, etc. The term "controller" refers to 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 functions associated with any particular controller can be centralized or distributed, whether local or remote. When used with a list of items, the phrase "at least one of..." 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" 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 "coupled to another element (e.g., a second element)", "coupled to another element (e.g., a second element)", "connected to another element (e.g., a second element)" or "connected to another element (e.g., a second element)" with or without the term "operably" or "communicatively", it means that the element can be coupled to another element directly (e.g., wired), wirelessly, or via a third element.

[0013] 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 portion 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).

[0014] In addition, the various functions described below can 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 parts 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 disk drive, a compact disk (CD), a digital video disc (DVD) or any other type of memory. "Non-transitory" computer-readable media does not include wired, wireless, optical or other communication links that transmit temporary electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data and media that can store data and overwrite data later, such as rewritable optical disks or erasable memory devices.

[0015] 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

[0016] 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, in which like reference numerals represent like parts:

[0017] Figure 1 An example wireless network according to various embodiments of the present disclosure is shown;

[0018] Figure 2A An example AP according to various embodiments of the present disclosure is shown;

[0019] Figure 2B An example STA according to various embodiments of the present disclosure is shown;

[0020] Figure 3 and Figure 4 An example process for discovering a single TDLS peer STA according to an embodiment of the present disclosure is shown;

[0021] Figure 5 An example of PPDU end time alignment on an NSTR link according to an embodiment of the present disclosure is shown;

[0022] Figure 6 An example system utilizing TDLS discovery response latency according to an embodiment of the present disclosure is shown;

[0023] Figure 7 An example of a TDLS discovery process performed by an NSTR non-AP MLD on an NSTR link according to an embodiment of the present disclosure is shown;

[0024] Fig. 8A and Figure 8B An example system for performing cross-link discovery using TDLS discovery response latency according to an embodiment of the present disclosure is shown; and

[0025] Fig. 9 An example process for assisting a non-AP MLD in discovering a P2P direct link that overlaps with an NSTR-constrained link without violating the NSTR constraint is shown according to various embodiments of the present disclosure. DETAILED DESCRIPTION

[0026] Discussed below Figures 1 to 9 The various embodiments used to describe the principles of the present disclosure in this patent document are for illustration 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 appropriately arranged system or device.

[0027] Tunneled direct link setup (TDLS) is a function of WI-FI that assists P2P communication between WI-FI devices. The embodiments of the present disclosure recognize that the TDLS discovery process defined in the current 802.11be specification is broken for non-AP MLDs that are subject to NSTR constraints. For example, when an NSTR non-AP MLD is a TDLS initiator and sends a TDLS discovery request, the TDLS responder can send a TDLS discovery response via a first link (direct link), and the NSTR non-AP MLD sends an uplink (UL) frame to the AP MLD on a second link, where the first link forms an NSTR link pair with the second link. Therefore, due to the NSTR constraint, the NSTR non-AP MLD will not be able to receive a response frame from the TDLS responder.

[0028] Therefore, the embodiments of the present disclosure provide methods and apparatuses for assisting the P2P discovery and establishment process with an MLD constrained by NSTR. In particular, the embodiments of the present disclosure provide methods and apparatuses for assisting the TDLS discovery and establishment process with an MLD constrained by NSTR.

[0029] Figure 1 An example wireless network 100 is shown in accordance with various embodiments of the present disclosure. Figure 1The embodiment of the wireless network 100 shown is for illustration only. Other embodiments of the wireless network 100 may be used without departing from the scope of the present disclosure.

[0030] 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.

[0031] 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 the present 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., APSTA). 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 device", "wireless terminal" or "user device". For convenience, the terms "station" and "STA" are used in the present disclosure to refer to a remote wireless device 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.

[0032] 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 MLDs, and the STAs 111-114 may be non-AP MLDs. 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).

[0033] The 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 APs and variations in the radio environment associated with natural and man-made obstacles.

[0034] As described in more detail below, one or more of the APs may include circuitry and / or programming for assisting non-AP MLDs in discovering P2P direct links that overlap with NSTR-constrained links without violating NSTR constraints. Figure 1 One example of a wireless network 100 is shown, but may be Figure 1 Various changes may be made. 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 these 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).

[0035] Figure 2A An example AP 101 is shown in accordance with various embodiments of the present disclosure. Figure 2A The embodiment of AP 101 shown in FIG. 1 is for illustration only, and Figure 1 The APs 103 of FIG. 104 may have the same or similar configurations. In the embodiments discussed below, the AP 101 is an AP MLD. However, the APs have a variety of configurations, and Figure 2A The scope of the present disclosure is not limited to any particular implementation of an AP.

[0036] 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.

[0037] The illustrated components of each attached AP 202a-202n may represent the physical (PHY) layer and the lower media access control (lower MAC, LMAC) layer in the open system interconnection (OSI) networking model. In such an embodiment, the illustrated components of the AP MLD 101 represent a single upper MAC (UMAC) layer and other higher layers in the OSI model, which are shared by all attached APs 202a-202n.

[0038] For each attached 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 attached 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 attached 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.

[0039] For each attached AP 202a-202n, the TX processing circuit 214 receives analog or digital data (such as voice data, network data, email, or interactive video game data) from the controller / processor 224. The TX processing circuit 214 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceiver 209a-209n receives the outgoing processed baseband or IF signal from the TX processing circuit 214 and up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna 204a-204n. In embodiments where each attached AP 202a-202n operates at a different bandwidth (e.g., 2.4 GHz, 5 GHz, or 6 GHz), the outgoing RF signals transmitted by each attached AP may be at a different RF frequency.

[0040] 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 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 allocated to different subcarrier subsets for different recipients (e.g., different STAs 111-114). The controller / processor 224 may support any of a variety of other functions in the AP MLD 101, including assisting non-AP MLDs in discovering P2P direct links that overlap with NSTR-constrained links without violating NSTR constraints. 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 may move data into or out of the memory 229 as needed by the executed process.

[0041] 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.

[0042] As described in more detail below, AP MLD 101 may include circuitry and / or programming for assisting non-AP MLDs in discovering P2P direct links that overlap with NSTR-constrained links without violating NSTR constraints. Figure 2A An example of AP MLD 101 is shown, but the Figure 2A For example, AP MLD 101 may include any number of Figure 2A. As a specific example, the AP MLD 101 may include multiple interfaces 234, and the controller / processor 224 may support routing functions 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 the TX processing circuit 214 and a single instance of the 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, in one or more of the attached APs 202a-202n, such as in a traditional AP, only one antenna and RF transceiver path may be included. In addition, Figure 2A The various components in may be combined, further subdivided, or omitted, and additional components may be added according to specific needs.

[0043] Figure 2B An example STA 111 is shown according to various embodiments of the present disclosure. Figure 2B The embodiment of STA 111 shown in FIG. is for illustration only, and Figure 1 STAs 111-115 may have the same or similar configurations. In the embodiments discussed below, STA 111 is a non-AP MLD. However, STAs may have a variety of configurations, and Figure 2B The scope of this disclosure is not limited to any particular implementation of a STA.

[0044] The non-AP MLD 111 is attached with a plurality of STAs 203a-203n (which may be referred to as, for example, STA1-STAn). Each of the attached STAs 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.

[0045] The illustrated components of each attached STA 203a-203n may represent the PHY layer and LMAC layer in the OSI networking model. In such an embodiment, the illustrated components of the non-AP MLD 111 represent a single UMAC layer and other higher layers in the OSI model, which are shared by all attached STAs 203a-203n.

[0046] For each attached 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 attached 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 attached STA may 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).

[0047] For each attached 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 network 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 embodiments where each attached 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 attached STA may be at a different RF frequency.

[0048] 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 processing circuits configured to assist the non-AP MLD in discovering a P2P direct link that overlaps with a link subject to an NSTR constraint without violating the NSTR constraint. In some embodiments, the controller / processor 240 includes at least one microprocessor or microcontroller.

[0049] The controller / processor 240 is also capable of executing other processes and programs resident in the memory 260, such as operations for assisting non-AP MLDs in discovering P2P direct links that overlap with links subject to NSTR constraints without violating NSTR constraints. The controller / processor 240 can 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 multiple applications 262, such as applications for assisting non-AP MLDs in discovering P2P direct links that overlap with links subject to NSTR constraints without violating NSTR constraints. The controller / processor 240 can operate multiple applications 262 based on the OS program 261 or in response to signals received from the 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 laptops and handheld computers. The I / O interface 245 is the communication path between these accessories and the main controller 240.

[0050] 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).

[0051] although Figure 2B An example of a non-AP MLD 111 is shown, but the Figure 2B Make various changes. For example, Figure 2B The various components in the may be combined, further subdivided, or omitted, and additional components may be added as required. In a specific example, one or more of the attached 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) and one or more graphics processing units (GPUs). In addition, although Figure 2B The non-AP MLD 111 is shown configured as a mobile phone or smart phone, but the non-AP MLD may also be configured to operate as other types of mobile or fixed devices.

[0052] Figure 3 and Figure 4An example process for discovering a single tunneled direct link setup (TDLS) peer STA according to an embodiment of the present disclosure is shown. In this example, the AP MLD (MLD_A) may be the AP MLD 101, and the non-AP MLD (MLD_S) may be the non-AP MLD 111. Although the AP MLD 101 is shown as having two attached APs (AP1 and AP2), and the non-AP MLD 111 is shown as a non-AP MLD having two attached non-AP STAs (STA1 and STA2), it should be understood that the process may be applied to a suitable MLD having any number of attached APs or STAs. For ease of explanation, it should be understood that in further embodiments below, references to the AP MLD and the non-AP MLD refer to the AP MLD 101 and the non-AP MLD 111, respectively.

[0053] Figure 3 and Figure 4 A scenario is shown in which TDLS discovery is initiated by a non-AP MLD (MLD_S). MLD_S has performed multi-link establishment with an AP MLD (MLD_A). As described above, MLD_S has two subordinate STAs - STA1 and STA2. STA3 cannot perform multi-link operation and is not subordinate to the non-AP MLD. MLD_A has two subordinate APs - AP1 and AP2, where AP1 operates on link 1 and AP2 operates on link 2. STA1 and STA3 operate on link 1 and are associated with AP1. STA2 operates on link 2 and is associated with AP2.

[0054] In this example, MLD_S initiates TDLS discovery by sending two TDLS discovery request frames, which are data frames, because it does not know on which link STA3 is operating and whether STA3 is affiliated with the MLD or is a STA not affiliated with the MLD. Figure 3 The first TDLS discovery request frame shown sets the basic service set identifier (BSSID) field in the link identifier element to the BSSID of AP1, and Figure 4 The second TDLS Discovery Request frame shown has this field set to the BSSID of AP2. Both frames have their A3 (DA) set to the STA3 MAC address and the To DS subfield of the Frame Control field set to 1.

[0055] The TDLS discovery request frame may be sent on link 1 (by STA1 as represented by a solid line) or on link 2 (by STA2 as represented by a dashed line). When the TDLS discovery request frame is received at the AP MLD (i.e., by AP1 or AP2), it routes the frame to STA3 through AP1 by setting the From DS subfield of the frame control field to 1 and setting A3(SA) to a non-AP MLD address (i.e., MLD_S).

[0056] STA3 discards the TDLS discovery request frame with the BSSID field of its link identifier element set to the BSSID of AP2 because it does not recognize the BSSID. STA3 recognizes the BSSID set to AP1 and responds with a TDLS discovery response frame as a management frame (in which RA is set to MLD_S and both the To DS and From DS subfields are set to 0). The TDLS STA attached to MLD_S receives the TDLS discovery response frame sent on the TDLS direct link. The TDLS initiator STA address field and the TDLS responder STA address field contained in the link identifier element (represented as LI in the figure) are carried in the TDLS discovery request frame and the TDLS discovery response frame, and are set to MLD_S and STA3, respectively.

[0057] Data transmission rules for NSTR non-AP MLDs are defined in the 802.11be standard, where STAs attached to non-AP MLDs form one or more NSTR link pairs. According to the current specification, for physical layer protocol data unit (PPDU) transmission on links that form an NSTR link pair with another STA attached to the same non-AP MLD, the end time of the PPDUs transmitted on these links needs to be aligned to prevent self-interference on the non-AP MLD side due to NSTR constraints.

[0058] Figure 5 An example of PPDU end time alignment on an NSTR link according to an embodiment of the present disclosure is shown. In this example, AP1 and AP2 are two APs attached to the AP MLD 101. In addition, STA1 and STA2 are two non-AP STAs attached to the non-AP MLD 111. 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 an NSTR non-AP MLD, that is, Link 1 and Link 2 form an NSTR link pair. In addition, Link 1 and Link 2 are both enabled links.

[0059] exist Figure 5In the example of FIG. 1 , AP2 transmits a DL PPDU 502 to STA2 on link 2. Shortly thereafter, AP1 transmits a DL PPDU 504 to STA1 on link 1. The transmission of the DL PPDU 504 on link 1 is completed earlier than the end time of the DL PPDU 502 transmitted on link 2. In this case, in order to avoid self-interference at the non-AP MLD, according to the current 802.11be specification, AP1 aligns the end time of the DL PPDU 504 on link 1 with the end time of the DL PPDU 502 on link 2. In this example, the alignment is performed by appending additional padding bits 506 within the DL PPDU 504 transmitted on link 1.

[0060] As described above, embodiments of the present disclosure provide methods and apparatus for assisting a TDLS discovery and establishment process for a non-AP MID subject to NSTR constraints. According to one embodiment, when an NSTR non-AP MLD intends to discover its TDLS peer STA on any link (e.g., on a first link) that is part of an NSTR link pair (e.g., with a second link), after sending a TDLS discovery request frame on the first link, the non-AP MLD may wait for a threshold amount of time (or a predetermined time period) before the non-AP MLD starts sending on the second link. The threshold amount of time may be referred to as a TDLS discovery response wait time. The threshold amount of time may be equal to the value indicated in a dot11TDLSResponseTimeout management information base (MIB) variable. According to one embodiment, if the threshold amount of time has passed and the non-AP MLD has not received a TDLS discovery response frame in response to the sent TDLS discovery request frame, the non-AP MLD may terminate the current TDLS discovery process on the link.

[0061] Figure 6 An example system utilizing TDLS discovery response waiting time according to an embodiment of the present disclosure is shown. Figure 6 In the example, TDLS discovery is initiated by a non-AP MLD (MLD_S). MLD_S has performed a multi-link establishment with an AP MLD (MLD_A). MLD_S has two subordinate STAs, STA1 and STA2. MLD_A has two subordinate APs, AP1 and AP2, where AP1 operates on link 1 and AP2 operates on link 2. STA1 operates on link 1 and is associated with AP1. STA2 and STA3 operate on link 2 and are associated with AP2. Link 1 and link 2 form an NSTR link pair at MLD_S.

[0062] In this example, MLD_S intends to discover TDLS peer STAs on link 1, and initiates TDLS discovery by sending a TDLS discovery request frame 602 (which is a data frame) on link 1 - this may be referred to as same-link discovery. The TDLS discovery request frame 602 sets the BSSID field in the link identifier element to the BSSID of AP1, sets A3 (DA) to the STA3 MAC address, and sets the TO_DS subfield of the frame control field to 1.

[0063] When the TDLS discovery request frame 602 is received at the AP MLD (i.e., by AP1), it routes the frame to STA3 by setting the From DS subfield of the frame control field to 1 and setting A3 (SA) to a non-AP MLD address (i.e., MLD_S) through AP2. In this example, STA3 discards the TDLS discovery request frame 602 with the BSSID field of its link identifier element set to the BSSID of AP1 because it does not recognize the BSSID. Therefore, STA3 does not send a TDLS discovery response frame at all.

[0064] In this example, after sending the TDLS discovery request frame 602 on link 1, MLD_S waits for a period of time corresponding to the TDLS discovery response wait time 604 before performing any UL transmission (i.e., transmission from STA2 to AP2) on link 2. Therefore, STA1 will be available to receive a TDLS discovery response frame sent by STA3 on the TDLS direct link established through link 1.

[0065] However, as described above, since STA3 is not associated with AP1 on link 1, it does not send any TDLS discovery response frame in response to the TDLS discovery request frame 602. Therefore, the TDLS discovery response wait time 604 elapses. Thereafter, MLD_S resumes UL transmission on link 2, and STA2 sends UL PPDU 606 to AP2 through link 2. In some embodiments, when the TDLS discovery response wait time 604 elapses without receiving a TDLS discovery response frame, MLD_S may terminate the TDLS discovery process on link 1.

[0066] According to another embodiment, when a TDLS discovery request frame is sent on a first link in an NSTR link pair to discover a TDLS peer STA on the first link, the non-AP MLD may start sending on a second link in the NSTR link pair after the TDLS discovery response wait duration has elapsed or after a STA attached to the non-AP MLD and operating on the first link receives a TDLS discovery response frame in response to a TDLS discovery request frame sent by the STA, whichever event occurs first.

[0067] Figure 7 An example of a TDLS discovery process 700 performed by an NSTR non-AP MLD on an NSTR link according to an embodiment of the present disclosure is shown. In this example, the TDLS discovery process 700 is a same-link discovery, but it should be understood that a similar process can be used for cross-link discovery, as discussed below.

[0068] According to another embodiment, an NSTR non-AP MLD may intend to use a TDLS discovery request frame sent on one link of the NSTR link pair (i.e., the first link) to discover its TDLS peer STA on any other link (e.g., on the second link) that is part of the NSTR link pair (e.g., with the first link), which may be referred to as cross-link discovery. After sending a TDLS discovery request frame on the first link to discover the TDLS peer STA on the second link (i.e., in the link identifier of the TDLS discovery request frame, the AP address (BSSID subfield of the link identifier element) is set to the AP attached to the AP MLD associated with the non-AP MLD and operating on the second link), the non-AP MLD may wait for a threshold amount of time before the non-AP MLD starts any UL transmission on the first link. Similar to the same-link discovery scenario, the threshold amount of time may be indicated as a duration indicated in the TDLS discovery response wait time.

[0069] According to another embodiment, after sending a TDLS discovery request frame on the first link to discover a TDLS peer STA on the second link, the non-AP MLD may start UL transmission on the first link after the TDLS discovery response wait duration has elapsed or after a STA attached to the non-AP MLD and operating on the second link receives a TDLS discovery response frame in response to the TDLS discovery request frame sent on the first link, whichever event occurs first.

[0070] Fig. 8A and Figure 8B An example system for cross-link discovery using TDLS discovery response latency according to various embodiments of the present disclosure is shown. Fig. 8A A system similar to Figure 6 system, but in Fig. 8A In the example of , MLD_S intends to discover the TDLS peer STA on link 2 by sending a TDLS discovery request frame 802 on link 1, that is, this example is cross-link discovery. Therefore, the TDLS discovery request frame 802 sets the BSSID field in the link identifier element to the BSSID of AP2 and sets A3 (DA) to the STA3 MAC address.

[0071] When the TDLS discovery request frame 802 is received at the AP MLD (i.e., by AP1), it routes the frame to STA3 by setting the From DS subfield of the frame control field to 1 and setting A3 (SA) to the non-AP MLD address (i.e., MLD_S) through AP2. In this example, after sending the TDLS discovery request frame 802 on link 1, MLD_S waits for a period of time corresponding to the TDLS discovery response wait time 604 before performing any UL transmission (i.e., transmission from STA1 to AP1) on link 1. Therefore, STA2 will be available to receive the TDLS discovery response frame 804 sent by STA3 on the TDLS direct link established through link 2.

[0072] In this example, STA3 recognizes the BSSID set to AP2 and responds with a TDLS discovery response frame 804 (which is a management frame) in which RA is set to MLD_S and both the To DS and From DS subfields are set to 0. The TDLS peer STA (i.e., STA2) attached to MLD_S receives the TDLS discovery response frame 804, which is sent on the TDLS direct link (also link 2). The TDLS initiator STA address field and the TDLS responder STA address field contained in the link identifier element (denoted as LI in the figure) are carried in the TDLS discovery request frame 802 and the TDLS discovery response frame 804, and are set to MLD_S and STA3, respectively.

[0073] In this example, MLD_S has completed receiving the TDLS discovery response frame 804 at time 808. MLD_S may resume UL transmission on Link 1 at time 808 even though the TDLS discovery response wait time 604 has not elapsed.

[0074] Except that STA3 operates on link 1 and is associated with AP1, Figure 8B A system similar to Fig. 8A In this example, STA3 discards the TDLS discovery request frame 802 whose BSSID field of its link identifier element is set to the BSSID of AP2 because it does not recognize the BSSID. Therefore, STA3 does not send a TDLS discovery response frame at all.

[0075] After sending the TDLS discovery request frame 802 on link 1, MLD_S waits for a period of time corresponding to the TDLS discovery response wait time 604 before performing any UL transmission (i.e., transmission from STA1 to AP1) on link 1. Therefore, STA2 will be available to receive a TDLS discovery response frame sent by STA3 on the TDLS direct link established through link 2, however, as described above, STA3 does not send any TDLS discovery response frame in response to the TDLS discovery request frame 802. Therefore, the TDLS discovery response wait time 604 elapses. Thereafter, MLD_S resumes UL transmission on link 1, and STA1 sends ULPPDU 806 to AP1 on link 1. In some embodiments, when the TDLS discovery response wait time 604 elapses without receiving a TDLS discovery response frame, MLD_S may terminate the TDLS discovery process on link 2.

[0076] According to one embodiment, when the AP MLD receives a TDLS discovery request frame from an associated NSTR non-AP MLD through a first link between the AP MLD and the non-AP MLD, for discovering a TDLS peer STA on the first link between the AP MLD and the non-AP MLD (i.e., in the link identifier element of the TDLS discovery request frame, the AP address, i.e., the BSSID subfield of the link identifier element, is set to an AP that is affiliated with the AP MLD and operates on the first link), if a second link between the same AP MLD and the non-AP MLD forms an NSTR link pair at the non-AP MLD (i.e., in a same-link discovery scenario), the APMLD may not send a request frame to the non-AP MLD on the second link (or the AP MLD may not send a frame requesting an immediate response to the non-AP MLD to the non-AP MLD on the second link) until a threshold amount of time indicated by the TDLS discovery response wait time has passed after the AP MLD receives the TDLS discovery request frame.

[0077] According to another embodiment of the same-link discovery scenario, when a TDLS discovery response frame is received through the TDLS direct link (corresponding to the first link) in response to the TDLS discovery request frame, the non-AP MLD may send a notification frame to the AP MLD to notify the APMLD that the non-AP MLD has received the corresponding TDLS discovery response frame. Therefore, if the AP MLD has the intention, even if the threshold amount of time indicated by the TDLS discovery response wait time has not passed after the AP MLD receives the TDLS discovery request frame, the AP MLD may still send a PPDU to the non-AP MLD on the second link to request an immediate response from the non-AP MLD.

[0078] According to one embodiment, when the AP MLD receives a TDLS discovery request frame from an associated NSTR non-AP MLD over a first link between the AP MLD and the non-AP MLD, for discovering a TDLS peer STA on a second link between the same AP MLD and the non-AP MLD (i.e., in a link identifier element of the TDLS discovery request frame, the AP address, i.e., the BSSID subfield of the link identifier element, is set to an AP operating on the second link and affiliated with the AP MLD), in a case where the first link and the second link form an NSTR link pair at the non-AP MLD (i.e., in a cross-link discovery scenario), the AP MLD may not send a request frame to the non-AP MLD on the first link (or the AP MLD may not send a frame requesting an immediate response to the non-AP MLD on the first link) until a threshold amount of time indicated by the TDLS discovery response wait time has passed after the AP MLD receives the TDLS discovery request frame.

[0079] According to another embodiment of the cross-link discovery scenario, when a TDLS discovery response frame is received through a TDLS direct link (corresponding to the second link) in response to a TDLS discovery request frame, the non-AP MLD may send a notification frame to the AP MLD to notify the APMLD that the non-AP MLD has received the corresponding TDLS discovery response frame. Therefore, if the AP MLD intends, even if the threshold amount of time indicated by the TDLS discovery response wait time has not passed after the AP MLD receives the TDLS discovery request frame, the AP MLD may still send a PPDU to the non-AP MLD on the first link to request an immediate response from the non-AP MLD.

[0080] Fig. 9 An example process 900 for assisting a non-AP MLD in discovering a P2P direct link that overlaps with a link subject to an NSTR constraint without violating the NSTR constraint according to various embodiments of the present disclosure is shown. Process 900 is discussed as being performed by a first non-AP MLD, but it should be understood that the corresponding AP MLD performs the corresponding process. In addition, for convenience, process 900 is discussed as being performed by a WI-FI non-AP MLD including a first STA, each of which includes a transceiver configured to form a link with a corresponding AP attached to a WI-FI AP MLD, wherein two of the links form an NSTR link pair subject to the NSTR constraint. However, it should be understood that any suitable wireless communication device may perform these processes.

[0081] refer to Fig. 9, process 900 begins with a first non-AP MLD generating a first message that identifies a first link in an NSTR link pair as a target link for establishing a P2P direct link (eg, a TDLS direct link) with a peer STA (step 905).

[0082] Next, the first non-AP MLD sends a first message to the AP MLD through one of the links in the NSTR link pair (step 910). That is, the first non-AP MLD sends the first message via one of the first STAs forming an NSTR link with the corresponding AP in the AP MLD's AP.

[0083] Then, after the first message is sent, the first non-AP MLD waits for a predetermined period of time before performing UL transmission to the AP MLD through the second link in the NSTR link pair that is not the target link (step 915). The predetermined period of time may be, for example, a TDLS discovery response wait time and may be defined as a value in a MIB variable.

[0084] If the first non-AP MLD does not receive a response to the first message before a predetermined time period has elapsed, then at step 920, the first non-AP MLD terminates the P2P discovery process on the first link of the NSTR link pair.

[0085] Alternatively, the first non-AP MLD receives a second message in response to the first message from the peer STA over the first link of the NSTR link pair before the predetermined time period elapses (step 925).

[0086] In this case, the first non-AP MLD then sends a notification message to the AP MLD indicating that the first non-AP MLD has received the second message (step 930). In addition, after the second message is received, the first non-AP MLD resumes UL transmission to the corresponding AP of the AP MLD through the second link in the NSTR link pair (step 935).

[0087] In some embodiments, the first non-AP MLD sends the first message via the first NSTR link (for same-link discovery). In other embodiments, the first non-AP MLD sends the first message via the second NSTR link (for cross-link discovery).

[0088] The above flow charts illustrate example methods 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, the 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.

[0089] 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) configured to form a link with an AP of an AP MLD, wherein two of the links form a non-simultaneous transmission / reception (NSTR) link pair subject to an NSTR constraint, a first STA of the STAs and a first AP of the APs form a first link of the NSTR link pair, and a second STA of the STAs and a second AP of the APs form a second link of the NSTR link pair; and at least one processor operably coupled to the STA, the at least one processor configured to generate a first message identifying a first link of the NSTR link pair as a target link for establishing a point-to-point (P2P) direct link with a peer STA, The STA corresponding to one of the two links is further configured to send a first message to one of the first AP or the second AP, and Wherein, a second STA corresponding to a second link in the NSTR link pair that is not the target link is configured to wait for a predetermined period of time after the first message is sent and before performing an uplink (UL) transmission to the second AP.

2. The non-AP MLD according to claim 1, in: The first STA is further configured to receive, before the predetermined time period elapses, a second message from the peer STA in response to the first message; as well as The second STA is further configured to resume UL transmission to the second AP after the second message is received.

3. The non-AP MLD according to claim 2, in: The first STA is further configured to receive, before the predetermined time period elapses, a second message from the peer STA in response to the first message; as well as The STA corresponding to one of the two links is further configured to send a notification message to one of the first AP or the second AP indicating that the non-AP MLD has received the second message.

4. The non-AP MLD according to claim 1, in, The at least one processor is further configured to terminate the P2P discovery process on a first link of the NSTR link pair after the predetermined time period has elapsed.

5. The non-AP MLD according to claim 1, in, The predetermined time period is indicated as a value in a Management Information Base (MIB) variable.

6. A method of wireless communication performed by a non-access point (AP) multi-link device (MLD), the non-AP MLD comprising a first station (STA) forming a first link with a first AP in the AP MLD and a second STA forming a second link with a second AP in the AP MLD, such that the first link and the second link form a non-simultaneous transmit / receive (NSTR) link pair subject to NSTR constraints, the method include: generating a first message identifying a first link of the NSTR link pair as a target link for establishing a point-to-point (P2P) direct link with a peer STA; sending a first message to one of the first AP or the second AP via one of the first link and the second link in the NSTR link pair; as well as After the first message is sent, a predetermined period of time is waited before performing an uplink (UL) transmission to a second AP over a second link of the NSTR link pair that is not the target link.

7. The method according to claim 6, further comprising: include: receiving, before the predetermined time period elapses, from the peer STA via a first link in the NSTR link pair, a second message in response to the first message; as well as After the second message is received, UL transmission to the second AP over the second link in the NSTR link pair is resumed.

8. The method according to claim 7, further comprising: include: receiving, before the predetermined time period elapses, from the peer STA via a first link in the NSTR link pair, a second message in response to the first message; as well as A notification message indicating that the non-AP MLD has received the second message is sent to one of the first AP or the second AP through one of the first link and the second link.

9. The method according to claim 6, further comprising: include: After the predetermined time period has elapsed, the P2P discovery process on the first link of the NSTR link pair is terminated.

10. The method according to claim 6, in, The predetermined time period is indicated as a value in a Management Information Base (MIB) variable.

11. An access point (AP) multi-link device (MLD), include: The AP is configured to form a link with a non-AP MLD station (STA); as well as at least one processor operably coupled to the AP, The first AP among the APs is further configured to form a link with a peer STA, wherein two of the links formed with the STA of the non-AP MLD form a non-simultaneous transmission / reception (NSTR) link pair subject to a non-simultaneous transmission / reception (NSTR) constraint, wherein one of the APs corresponding to one of the two links in the NSTR link pair is configured to receive a first message from the non-AP MLD, wherein the at least one processor is configured to determine that the first message identifies the first link of the NSTR link pair as a target link for establishing a point-to-point (P2P) direct link with the peer STA, and Wherein, a second AP among the APs corresponding to a second link in the NSTR link pair that is not the target link is configured to wait for a predetermined period of time after a first message is received and before requesting uplink (UL) transmission to the non-AP MLD.

12. The AP MLD according to claim 11, in, The first AP forming the link with the peer STA is also configured to send a first message to the peer STA.

13. The AP MLD according to claim 12, in: The first AP is further configured to receive, before the predetermined time period elapses, a second message from the non-AP MLD indicating that the non-AP MLD has received a response to the first message from a second STA, and The second AP corresponding to the second link of the NSTR link pair is further configured to resume UL transmission of MLD requests to the non-AP after the second message is received.

14. The AP MLD according to claim 13, in, The predetermined time period is indicated as a value in a Management Information Base (MIB) variable.

15. A method of wireless communication performed by an access point (AP) multi-link device (MLD), the method comprising operations performed by at least one processor of the AP MLD according to one of claims 11 to 14.

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