Target wakeup time demolition procedure for multi-link devices

Abstract

Methods and apparatus for facilitating target wakeup time (TWT) removal operations for 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) configured to form a link with an AP of the AP MLD, where at least one TWT plan or agreement is established on the at least one link. The at least one processor is operably coupled to the STA and configured to generate or interpret a first message identifying at least one of the links and indicating that a TWT demolition is to be performed for the identified at least one link. A first one of the STAs is configured to transmit a first message to or receive a first message from a first one of the APs on a first one of the links.

Description

Technical Field

[0001] The present disclosure generally relates to power management in wireless communication systems including multi-link devices. Embodiments of the present disclosure relate to methods and apparatus for enhancing target wake-up time operation of multi-link devices in wireless local area network communication systems. Background Art

[0002] Wireless Local Area Network (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] Next generation Extremely High Throughput (EHT) WI-FI systems (e.g., IEEE 802.11be) support multiple operating bands (referred to as 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 referred to as multi-link operation (MLO). WI-FI devices that support MLO are referred to as multi-link devices (MLDs). Using MLO, non-access point (non-AP) MLDs can discover, authenticate, attach to AP MLDs, 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 transmission and reception on one link is referred to as a station (STA).

[0004] Target Wake Time (TWT) is one of the most important features of power management in WI-FI networks, which was developed by IEEE802.11ah and later adopted and modified into IEEE 802.11ax. With TWT operation, it is sufficient for the STA to wake up only at a pre-planned time negotiated with another STA or AP in the network. In the IEEE 802.11ax standard, two types of TWT operations are possible-individual TWT operation and broadcast TWT operation. An individual TWT agreement can be established between two STAs or between a STA and an AP. On the other hand, with broadcast TWT operation, an AP can set up a shared TWT session for a group of STAs.

[0005] Restricted TWT (rTWT or r-TWT) operation is a newly introduced feature in IEEE 802.11be, which provides more protection for STAs of the restricted TWT plan to serve delay-sensitive applications in a timely manner. Restricted TWT is based on the broadcast TWT mechanism, however, there are some key characteristics that make restricted TWT operation an important feature for supporting low-latency applications in next-generation WLAN systems. Restricted TWT provides protected service periods for its member STAs by sending silent elements to other STAs in the basic service set (BSS) that are not members of the rTWT plan, where the silent interval corresponding to the silent element overlaps with the initial part of the restricted TWT service period (SP). Therefore, it gives more channel access opportunities to STAs of the rTWT member plan, which helps delay-sensitive business flows. Summary of the invention

[0006] Solution to the problem

[0007] Embodiments of the present disclosure provide methods and apparatus for facilitating TWT teardown operations of MLD in a WLAN.

[0008] In one embodiment, a non-AP MLD is provided, comprising a STA and at least one processor operably coupled to the STA. The STA is configured to form a link with an AP of the AP MLD. At least one TWT plan or agreement is established on at least one of the links. The at least one processor is configured to generate or interpret a first message, which identifies at least one of the links and indicates that a TWT teardown is to be performed for at least one of the identified links. A first STA among the STAs is configured to send a first message to a first AP among the APs on a first link among the links or receive a first message from the first AP.

[0009] In another embodiment, an AP MLD is provided, comprising an AP and at least one processor operably coupled to the AP. The AP is configured to form a link with a non-AP MLD STA. At least one TWT plan or agreement is established on at least one of the links. The at least one processor is configured to generate or interpret a first message, which identifies at least one of the links and indicates that a TWT teardown is to be performed for at least one of the identified links. The first AP in the AP is configured to send a first message to a first STA in the STA on a first link in the link or receive a first message from the first STA.

[0010] In another embodiment, a method for wireless communication performed by a non-AP MLD including a STA is provided. The STA is configured to form a link with an AP of the AP MLD, and establish at least one TWT plan or agreement on at least one link. The method includes the following steps: generating or interpreting a first message that identifies at least one link in the links and indicates that TWT teardown will be performed for at least one of the identified links, and sending a first message to a first AP in the APs on a first link in the links or receiving a first message from the first AP.

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

[0012] 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 components 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.

[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 a portion thereof that are 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 signals 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 rewritten 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, wherein 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 3shows examples of different timing components related to a TWT SP according to an embodiment of the present disclosure;

[0021] Figure 4 An example format of a TWT stream field according to an embodiment of the present disclosure is shown;

[0022] Figure 5 An example format of a TWT stream field according to an embodiment of the present disclosure is shown;

[0023] Figure 6 An example format of a TWT stream field according to an embodiment of the present disclosure is shown;

[0024] Figure 7 An example format of a TWT stream field including a link ID bitmap according to an embodiment of the present disclosure is shown;

[0025] Figure 8 An example format of a TWT stream field including a link ID bitmap according to an embodiment of the present disclosure is shown;

[0026] Fig. 9 An example format of a TWT flow field including a link ID bitmap according to an embodiment of the present disclosure is shown;

[0027] Fig.10 An example of using a TWT teardown frame in the context of multi-link operation according to an embodiment of the present disclosure is shown;

[0028] Fig.11 An example format of a TWT flow field including a link ID subfield according to an embodiment of the present disclosure is shown;

[0029] Fig.12 An example format of a TWT flow field including a link ID subfield according to an embodiment of the present disclosure is shown;

[0030] Fig.13 An example format of a TWT flow field including a link ID subfield according to an embodiment of the present disclosure is shown;

[0031] Fig.14 An example format of a TWT flow field including a TWT schedule exclusion subfield according to an embodiment of the present disclosure is shown;

[0032] Fig.15 An example process for using a TWT teardown frame in the context of a multi-link device is shown; and

[0033] Fig.16A and 16B An example process for facilitating a TWT teardown operation of an MLD according to various embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0034] Discussed below Figures 1 to 16B 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 to limit the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0035] The TWT Teardown frame is used to tear down a TWT agreement or TWT schedule that has been established between an AP and a non-AP STA. Embodiments of the present disclosure recognize that the use of the TWT Teardown frame in multi-link operations is not defined in the current 802.11 specification.

[0036] Accordingly, various embodiments of the present disclosure provide mechanisms for facilitating the use of TWT teardown frames by MLDs to tear down TWT schedules or agreements in multi-link operations.

[0037] The various embodiments of the present disclosure further recognize that there is currently no way to exclude any particular TWT protocol or plan from the set of plans or protocols being torn down. This is not very conducive to restricted TWT operation because a STA with an r-TWT plan may have multiple broadcast TWT plans and restricted TWT plans, and a planned STA may want to tear down the broadcast TWT plan for, for example, power saving purposes, while maintaining the r-TWT plan for low-latency business purposes.

[0038] Accordingly, various embodiments of the present disclosure provide mechanisms for facilitating selective TWT schedule exclusion from a TWT teardown process using a TWT teardown frame.

[0039] The various embodiments of the present disclosure also recognize that the current TWT teardown frame is a unicast frame that cannot be sent to multiple STAs at the same time. For example, an r-TWT schedule AP attached to an AP MLD may want to disable a link for a certain period of time, but there is currently no way to use a TWT teardown frame to tear down all TWT schedules operating on the link before the link is disabled or deleted.

[0040] Therefore, embodiments of the present disclosure provide a mechanism for facilitating MLD to use broadcast TWT teardown frames.

[0041] The various embodiments of the present disclosure further recognize that the current TWT teardown frame cannot operate at the MLD level. For example, the MLD may want to tear down a TWT plan or agreement on multiple links to save power, but there is currently no way to indicate one or more links among the multiple links between the AP MLD and the non-AP MLD that the TWT teardown frame is for.

[0042] 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.

[0043] 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.

[0044] 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 a 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.

[0045] 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).

[0046] 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.

[0047] As described in more detail below, one or more of the APs may include circuitry and / or programming for facilitating TWT teardown operations for MLD in a WLAN. Figure 1 One example of a wireless network 100 is shown, but may be Figure 1 Various changes may be made. For example, wireless network 100 may include any number of APs and any number of STAs in any suitable arrangement. In addition, AP 101 may communicate directly with any number of STAs and provide those STAs with wireless broadband access to network 130. Similarly, each AP 101-103 may communicate directly with network 130 and provide STAs with direct wireless broadband access to network 130. In addition, AP 101 and / or 103 may provide access to other or additional external networks (such as an external telephone network or other type of data network).

[0048] 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 the AP.

[0049] 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.

[0050] 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 and other higher layers in the OSI model, which are shared by all subordinate APs 202A-202N.

[0051] 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.

[0052] 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.

[0053] 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 AP MLD 101, including facilitating TWT removal operations of the MLD in the 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, that reside in the memory 229. The controller / processor 224 may move data into or out of the memory 229 as required by the executing process.

[0054] 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.

[0055] As described in more detail below, AP MLD 101 may include circuitry and / or procedures for facilitating TWT teardown operations for MLDs in a WLAN. Figure 2A An example of AP MLD 101 is shown, but the same may be applied to 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 satellite 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 satellite 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 satellite APs 202a-202n, such as in a traditional AP. 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.

[0056] 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 the present disclosure is not limited to any particular implementation of a STA.

[0057] 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 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.

[0058] The components shown for each dependent STA 203a-203n may represent the PHY layer and 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 and other higher layers in the OSI model, which are shared by all dependent STAs 203a-203n.

[0059] 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., 2.4GHz, 5GHz, or 6GHz), 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).

[0060] 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 embodiments 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 may be at a different RF frequency.

[0061] 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 facilitate TWT teardown operations of MLDs in the WLAN. In some embodiments, the controller / processor 240 includes at least one microprocessor or microcontroller.

[0062] The controller / processor 240 is also capable of executing other processes and programs resident in the memory 260, such as operations for facilitating TWT teardown operations for MLDs in a WLAN. The controller / processor 240 can move data into or out of the memory 260 as needed for the executed process. In some embodiments, the controller / processor 240 is configured to execute multiple applications 262, such as applications for facilitating TWT teardown operations for MLDs in a WLAN. The controller / processor 240 can operate multiple applications 262 based on the OS program 261 or in response to signals 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 laptops and handheld computers. The I / O interface 245 is the communication path between these accessories and the main controller 240.

[0063] 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 use the touch screen 250 to input data into the non-AP MLD 111. 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).

[0064] although Figure 2B An example of a non-AP MLD 111 is shown, but the Figure 2B For example, they can be combined, further subdivided, or omitted Figure 2B 101, and additional components may be added as needed. In a specific example, one or more of the 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) 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 be configured to operate as other types of mobile or stationary devices.

[0065] Figure 3An example of different timing components related to a TWT SP according to an embodiment of the present disclosure is shown. In this example, STA1 may be a non-AP STA, such as STA 111. STA1 is a TWT scheduled STA, and AP1 (not shown) is its associated TWT scheduled AP.

[0066] STA1 establishes a broadcast TWT schedule with AP1. t1 is the value of the target wake-up time indicated in the target wake-up time field in the broadcast TWT parameter set field of the TWT element. Therefore, t1 is the time when STA1 should ideally be able to start frame exchange with AP1. Starting from t1, the duration for which STA is required to remain awake is the value of the nominal wake-up time (T) indicated in the nominal minimum TWT wake-up duration field in the broadcast TWT parameter set field. Due to various reasons, STA1 may not be able to start frame exchange with AP1 at the nominal SP start time t1. The actual SP start time may be much later. In the figure, the actual SP start time is represented as time t2. Using the delayed actual SP start time, the minimum wake-up duration of STA1 is also adjusted and represented as AdjustedMinimumTWTWakeDuration=T-(t2-t1).

[0067] As described above, the TWT teardown frame is used to tear down the TWT agreement or TWT plan established between the AP and the non-AP STA. The format of the TWT teardown frame is shown in Table 1.

[0068] [Table 1]

[0069] order information 1 category 2 Unprotected S1G operation 3 TWT Stream

[0070] Figure 5 An example format of a TWT flow field 502 according to an embodiment of the present disclosure is shown. The TWT flow field 502 is an example format of a TWT flow field in a TWT teardown frame of Table 1 when the negotiation type subfield is set to 2.

[0071] Figure 6 An example format of a TWT flow field 602 according to an embodiment of the present disclosure is shown. The TWT flow field 602 is an example format of a TWT flow field in a TWT teardown frame of Table 1 when the negotiation type subfield is set to 3.

[0072] According to one embodiment, during multi-link operation, a STA attached to an MLD may send a TWT teardown frame on a first link to tear down a TWT agreement or schedule established on a second link. The intended link on which the TWT schedule or agreement is to be torn down may be indicated by including a TWT link identifier (ID) subfield or a TWT link ID bitmap subfield in the TWT teardown frame.

[0073] Figure 7 An example format of a TWT flow field 702 including a link ID bitmap according to an embodiment of the present disclosure is shown. The TWT flow field 702 is an example format of a TWT flow field in a TWT teardown frame of Table 1 when the negotiation type subfield is set to 0 or 1. According to this embodiment, a link ID bitmap subfield 704 may be included in the TWT flow field 702 of the TWT teardown frame. According to some embodiments, a link ID bitmap presence subfield 706 may be present in the TWT flow field to indicate the presence of the link ID bitmap subfield 704 in the TWT flow field 702.

[0074] If the Link ID Bitmap Present Subfield in the TWT Stream Field is set to 1, it indicates that the Link ID Bitmap Subfield is present in the TWT Stream Field of the TWT Teardown Frame. Otherwise, the Link ID Bitmap Subfield is not present in the TWT Stream Field of the TWT Teardown Frame. According to one embodiment, when present in the TWT Stream Field of the TWT Teardown Frame, the size of the Link ID Bitmap Subfield is 16 bits long. According to another embodiment, when present in the TWT Stream Field, the size of the Link ID Bitmap Subfield is 8 bits long.

[0075] According to some embodiments, the link ID bitmap subfield in the TWT flow field of the TWT teardown frame indicates one or more links to which the TWT teardown frame sent by the STA attached to the MLD applies. A value of 1 in bit position i of the link ID bitmap subfield of the TWT flow field indicates that the link associated with link IDi is a link to which the TWT teardown frame sent by the STA attached to the MLD applies. A value of 0 in bit position i of the link ID bitmap subfield of the TWT flow field indicates that the link associated with link IDi is not a link to which the TWT teardown frame sent by the STA attached to the MLD applies.

[0076] According to one embodiment, the link ID bitmap subfield of the TWT flow field may indicate at most one link. According to this embodiment, at most one bit position in the link ID bitmap subfield may be set to 1. According to another embodiment, the link ID bitmap subfield of the TWT flow field may indicate more than one link. According to this embodiment, more than one bit position in the link ID bitmap subfield may be set to 1.

[0077] Figure 8An example format of a TWT flow field 802 including a link ID bitmap according to an embodiment of the present disclosure is shown. The TWT flow field 802 is an example format variation of the TWT flow field 702 when the negotiation type subfield is set to 2.

[0078] Fig. 9 An example format of a TWT flow field 902 including a link ID bitmap according to an embodiment of the present disclosure is shown. The TWT flow field 902 is an example format variation of the TWT flow field 702 when the negotiation type subfield is set to 3.

[0079] According to one embodiment, if a STA affiliated with an MLD sends a TWT teardown frame that does not include a link ID bitmap subfield in a TWT flow field, it may indicate that the TWT teardown frame applies to the link on which the TWT teardown frame is sent.

[0080] According to one embodiment, the all-zero value in the link ID bitmap subfield in the TWT flow field is reserved. According to another embodiment, the all-zero value in the link ID bitmap subfield in the TWT flow field of the TWT teardown frame indicates that the TWT teardown frame applies to the link on which the TWT teardown frame is sent.

[0081] Fig.10 An example of using a TWT teardown frame in the context of multi-link operation according to an embodiment of the present disclosure is shown. Fig.10 , the AP MLD may be AP MLD 101, and the non-AP MLD may be non-AP MLD 111. It should be understood that further references to an AP MLD or a non-AP MLD herein refer to the AP MLD 101 or the non-AP MLD 111, respectively. Although the AP MLD 101 is illustrated as having three subordinate APs—AP1, AP2, and AP3—and the non-AP MLD 111 is illustrated as having three subordinate STAs—STA1, STA2, and STA3—it should be understood that this is merely an example, and any suitable MLD with any number of subordinate APs or STAs may be used.

[0082] In this example, three links are established between the AP MLD and its associated non-AP MLD - Link 1 between AP1 and STA1, Link 2 between AP2 and STA2, and Link 3 between AP3 and STA3. Three TWT plans or agreements are established. TWT Plan 1 is established on Link 1, TWT Plan 2 is established on Link 2, and TWT Plan 3 is established on Link 3. STA2 attached to the non-AP MLD sends a TWT teardown frame 1002 to AP2 attached to the AP MLD through Link 2. In the TWT teardown frame 1002, STA2 indicates Link 1 and Link 3. Therefore, TWT Plan 1 and TWT Plan 3 on Link 1 and Link 3 are respectively torn down, while Plan 2 on Link 2 is maintained.

[0083] According to one embodiment, if multiple links are indicated in the link ID bitmap subfield of the TWT flow field of the TWT teardown frame, the broadcast TWT ID subfield or the TWT flow identifier subfield of the TWT flow field is retained. According to another embodiment, if multiple links are indicated in the link ID bitmap subfield, the TWT teardown frame is applied to the TWT plan or agreement as indicated by the broadcast TWT ID subfield or the TWT flow identifier subfield on the link indicated in the link ID bitmap subfield.

[0084] Fig.11 An example format of a TWT flow field 1102 including a link ID subfield according to an embodiment of the present disclosure is shown. The TWT flow field 1102 is an example format of a TWT flow field in the TWT teardown frame of Table 1 when the negotiation type subfield is set to 0 or 1. According to this embodiment, a link ID subfield 1104 may be included in the TWT flow field 1102 of the TWT teardown frame to indicate a link to which the TWT teardown frame applies.

[0085] Fig.12 An example format of a TWT flow field 1202 including a link ID subfield according to an embodiment of the present disclosure is shown. The TWT flow field 1202 is an example format variation of the TWT flow field 1102 when the negotiation type subfield is set to 2.

[0086] Fig.13 An example format of a TWT flow field 1302 including a link ID subfield according to an embodiment of the present disclosure is shown. The TWT flow field 1302 is an example format variation of the TWT flow field 1102 when the negotiation type subfield is set to 3.

[0087] As described above, there is currently no way to exclude any specific TWT protocol or schedule from the set of schedules or protocols being torn down using the TWT Teardown frame. For example, when the Teardown All TWT subfield in the TWT Stream field of the TWT Teardown frame is set to 1, it indicates that all individual TWT agreements or broadcast TWT schedules will be torn down by the TWT Teardown frame.

[0088] Fig.14 An example format of a TWT flow field 1402 including a TWT schedule exclusion subfield according to an embodiment of the present disclosure is shown. The TWT flow field 1402 is an example format of a TWT flow field in the TWT teardown frame of Table 1 when the negotiation type subfield is set to 3. According to this embodiment, an R-TWT exclusion subfield 1404 may be included in the TWT flow field 1402 of the TWT teardown frame to facilitate an indication that a restricted TWT schedule will not be torn down by the TWT teardown frame.

[0089] The size of the R-TWT Exclusion subfield 1404 may be 1 bit. If the Dismantle All TWT subfield 1406 in the TWT Flow field is set to 1 and the R-TWT Exclusion subfield 1404 is set to 0, it may indicate that all TWT plans or TWT agreements on the identified link are intended to be dismantled, including restricted TWT plans. If the Dismantle All TWT subfield 1406 in the TWT Flow field is set to 1 and the R-TWT Exclusion subfield 1404 is set to 1, it indicates that all TWT plans or TWT agreements on the identified link are intended to be dismantled, except for the R-TWT plan.

[0090] Fig.15 An example process 1502 for using a TWT teardown frame in the context of a multi-link device is shown. In this example, a non-AP MLD has established at least two links between its affiliated STAs and corresponding APs affiliated with an associated AP MLD. The non-AP MLD sends a TWT teardown frame on one of the links (the second link) to tear down a TWT schedule or agreement on a different link (the first link).

[0091] Fig.16A and 16B An example process for facilitating a TWT teardown operation of an MLD according to various embodiments of the present disclosure is shown. Fig.16A and 16B The processes 1600 and 1601 are discussed as being performed by a non-AP MLD, but it should be understood that the corresponding AP MLD performs the corresponding process. Fig.16A and 16BThe processes are 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 attached to the WI-FI AP MLD. However, it should be understood that any suitable wireless communication device may perform these processes.

[0092] refer to Fig.16A , process 1600 begins with the non-AP MLD generating a first message that identifies at least one of the links and indicates that a TWT teardown will be performed for the at least one identified link (step 1605). In some embodiments, the first message is a TWT teardown frame that includes a TWT flow field that identifies the at least one link.

[0093] Then, the non-AP MLD sends a first message to the AP MLD through a first link among the links (step 1610).

[0094] In some embodiments, the at least one link identified includes at least one link other than the first link. That is, the first message is sent on one link to dismantle the TWT plan or agreement on other links. In some embodiments, the at least one link identified may also include the first link (i.e., the link on which the first message is sent).

[0095] In some embodiments, in order to identify at least one link on which TWT teardown is to be performed, the non-AP MLD may include in the first message a bitmap having entries corresponding to a link identifier of each of the links, and the entries of the bitmap may be set during generation of the first message to identify at least one link on which TWT teardown is to be performed.

[0096] In other embodiments, in order to identify a link on which TWT teardown is to be performed, the non-AP MLD may include a link identifier subfield in the first message, and the link identifier subfield may be set during generation of the first message to identify a link on which TWT teardown is to be performed.

[0097] In some embodiments, the first message includes an indication of excluding at least one type of TWT plan or agreement from the TWT teardown on at least one identified link. This can be, for example, an indication of excluding a restricted TWT plan from the TWT teardown.

[0098] Reference now Fig. 16B , process 1601 begins with the non-AP MLD receiving a first message from the AP MLD via a first link among the links (step 1615).

[0099] Then, the non-AP MLD interprets the first message, which identifies at least one of the links and indicates that a TWT teardown is to be performed for the at least one identified link (step 1620). Fig.16A In the embodiment, the first message may be a TWT teardown frame including a TWT flow field identifying the at least one link.

[0100] As in Fig.16A In some embodiments, at least one of the identified links includes at least one link other than the first link. That is, the first message is sent on one link to dismantle the TWT plan or agreement on other links. In some embodiments, at least one of the identified links may also include the first link (i.e., the link on which the first message is sent).

[0101] Similar to Fig.16A In some embodiments, the first message may include a bitmap having entries corresponding to a link identifier of each link in the links, and the non-AP MLD may interpret the entries of the bitmap after receiving the first message to identify at least one link on which TWT teardown is to be performed.

[0102] Similar to Fig.16A In some embodiments, the first message may include a link identifier subfield, and the non-APMLD may interpret the link identifier subfield after receiving the first message to identify a link on which a TWT teardown is to be performed.

[0103] like Fig.16A In some embodiments, the first message includes an indication of excluding at least one type of TWT plan or agreement from TWT removal on at least one identified link. This can be, for example, an indication of excluding restricted TWT plans from TWT removal.

[0104] 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.

[0105] 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. None of the descriptions in this application should be interpreted as implying that any particular element, step or function is an essential element that must be included within 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 at least one target wake time (TWT) schedule or agreement is established on at least one of the links; and at least one processor operably coupled to the STA, the at least one processor being configured to generate or interpret a first message that identifies at least one of the links and indicates that a TWT teardown is to be performed for the at least one identified link, The first STA among the STAs is configured to send the first message to a first AP among the APs or receive the first message from the first AP on a first link among the links.

2. The non-AP MLD according to claim 1, in, The identified at least one link includes at least one link other than the first link.

3. The non-AP MLD according to claim 1, in: The first message includes a bitmap having an entry corresponding to a link identifier for each of the links, and The at least one processor is further configured to: setting an entry of the bitmap during generation of the first message to identify the at least one link on which the TWT teardown is to be performed; or The entries of the bitmap are interpreted after receiving the first message to identify the at least one link on which the TWT teardown is to be performed.

4. The non-AP MLD according to claim 1, in: The first message includes a link identifier subfield, and The at least one processor is further configured to: setting the link identifier subfield during generation of the first message to identify a link on which the TWT teardown is to be performed; or The link identifier subfield is interpreted after receiving the first message to identify the one link on which the TWT teardown is to be performed.

5. The non-AP MLD according to claim 1, in, The first message includes an indication to exclude at least one type of TWT plan or agreement from TWT removal on at least one identified link, and Wherein, the indication to exclude at least one type of TWT plan or agreement from the TWT dismantling is an indication to exclude restricted TWT plans from the TWT dismantling.

6. The non-AP MLD according to claim 1, in, The first message is a TWT teardown frame, and the TWT teardown frame includes a TWT flow field identifying the at least one link.

7. An access point (AP) multi-link device (MLD), include: an AP configured to form links with stations that are not AP MLDs, wherein at least one target wake time (TWT) schedule or agreement is established on at least one of the links; and at least one processor operably coupled to the AP, the at least one processor configured to generate or interpret a first message that identifies at least one of the links and indicates that a TWT teardown is to be performed for the at least one identified link, The first AP among the APs is configured to send the first message to a first STA among the STAs or receive the first message from the first STA on a first link among the links.

8. The AP MLD according to claim 7, in, The identified at least one link includes at least one link other than the first link.

9. The AP MLD according to claim 7, in: The first message includes a bitmap having an entry corresponding to a link identifier for each of the links, and The at least one processor is further configured to: setting an entry of the bitmap during generation of the first message to identify the at least one link on which the TWT teardown is to be performed; or The entries of the bitmap are interpreted after receiving the first message to identify the at least one link on which the TWT teardown is to be performed.

10. The AP MLD according to claim 7, in: The first message includes a link identifier subfield, and The at least one processor is further configured to: setting the link identifier subfield during generation of the first message to identify a link on which the TWT teardown is to be performed; or The link identifier subfield is interpreted after receiving the first message to identify the one link on which the TWT teardown is to be performed.

11. The AP MLD according to claim 7, in, The first message includes an indication to exclude at least one type of TWT plan or agreement from TWT removal on at least one identified link, and Wherein, the indication to exclude at least one type of TWT plan or agreement from the TWT dismantling is an indication to exclude restricted TWT plans from the TWT dismantling.

12. The AP MLD according to claim 7, in, The first message is a TWT teardown frame, and the TWT teardown frame includes a TWT flow field identifying the at least one link.

13. A method of wireless communication, the method comprising operations performed by at least one processor of a non-access point (AP) multi-link device (MLD) as claimed in any one of claims 1 to 6.

14. A method of wireless communication, the method comprising operations performed by at least one processor of the access point (AP) multi-link device (MLD) of any one of claims 7 to 12.

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