Method and apparatus for TWT operation of WLAN system

Abstract

A method and apparatus for facilitating broadcast target wake time (TWT) negotiation on one link between multi-link devices (MLDs) in a wireless local area network to establish broadcast TWT scheduling on other links between the same MLD. A non-access point (AP) MLD includes a processor and stations (STAs), each including a transceiver configured to form a link with a corresponding AP of the AP MLD. The processor is operably coupled to the STA and configured to generate or receive a first message for broadcast TWT negotiation, where the first message indicates that the broadcast TWT negotiation is for broadcast TWT scheduling on at least one first of the links. The transceiver of the first STA is further configured to transmit the first message to or receive the first message from the AP MLD over the second link.

Description

Technical Field

[0001] The present disclosure generally relates to power management in a wireless communication system including multi-link devices. Embodiments of the present disclosure relate to methods and apparatus for facilitating establishment of a broadcast target wakeup schedule on links between multi-link devices in a wireless local area network communication system. Background Art

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

[0003] The next generation of ultra-high throughput (EHT) WI-FI systems (e.g., IEEE 802.11be) supports multiple operating bands (called 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 frequency bands / links, which is called 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 set up multiple links with AP MLDs. Channel access and frame exchange can be performed on each link established between AP MLDs and non-AP MLDs. The component of the MLD responsible for transmission and reception on a link is called a station (STA).

[0004] Target Wake Time (TWT) is one of the most important features for power management in WI-FI networks, which was developed by IEEE802.11ah and later adopted and modified to IEEE 802.11ax. With TWT operation, the STA only needs to wake up at a predetermined 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. A separate TWT protocol can be established between two STAs or between a STA and an AP. On the other hand, with broadcast TWT operation, the AP can set up a shared TWT session for a group of STAs.

[0005] Restricted TWT (rTWT, r-TWT or R-TWT) operation is a newly introduced feature in IEEE 802.11be, which provides more protection for STAs scheduled with restricted TWT to provide services for 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 schedule, where the silent interval corresponding to the silent element overlaps with the initial part of the restricted TWT service period (SP). Therefore, it grants more channel access opportunities to STAs scheduled by rTWT members, which is beneficial to delay-sensitive business flows. Summary of the invention

[0006] Technical Solution

[0007] Embodiments of the present disclosure provide methods and apparatus for facilitating broadcast TWT negotiation on one link between MLDs in a WLAN to establish broadcast TWT schedules on other links between the same MLDs.

[0008] In one embodiment, a non-AP MLD is provided, which includes a STA and a processor operably connected to the STA. The STAs each include a transceiver configured to form a link with the corresponding AP of the AP MLD. The processor is configured to generate or receive a first message for broadcast TWT negotiation, wherein the first message indicates that the broadcast TWT negotiation is for a broadcast TWT schedule on at least one first link in the link. The transceiver of the first STA is also configured to transmit a first message to the AP MLD via a second link or receive a first message from the AP MLD.

[0009] In one embodiment, a method for wireless communication performed by a non-AP MLD including STAs is provided. The STAs each include a transceiver configured to form a link with a corresponding AP of the AP MLD. The method includes the following steps: generating or interpreting a first message for broadcast target wake-up time (TWT) negotiation, wherein the first message indicates that the broadcast TWT negotiation is for a broadcast TWT schedule on at least one first link in the link; and transmitting the first message to the AP MLD or receiving the first message from the AP MLD via a second link.

[0010] In one embodiment, an AP MLD is provided, which includes an AP and a processor operably connected to the AP. The APs each include a transceiver configured to form a link with a corresponding STA of a non-AP MLD. The processor is configured to generate or receive a first message for broadcast TWT negotiation, wherein the first message indicates that the broadcast TWT negotiation is for a broadcast TWT schedule on at least one first link in the link. The transceiver of the first AP is also configured to transmit a first message to the non-AP MLD via a second link or receive a first message from the non-AP MLD.

[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 "connection" 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 "transmit", "receive" and "communication" and their derivatives cover 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, included in, included in, connected to, connected to, connected to, connected to, connected to, communicated with, collaborated with, interlaced, paralleled, adjacent to, coupled to, coupled to, coupled to, having ... 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 "1st" and "2nd" or "first" and "second" may 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 will be understood that if an element (e.g., a first element) is referred to as "coupled to," "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 may be coupled to the other 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, such as "logic", "logic block", "part", or "circuitry". A module may be a single integrated component adapted to perform one or more functions or its smallest unit or part. 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 embedded in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, steps, functions, objects, classes, instances, related data or a part thereof suitable for being implemented with 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 disc (CD), a digital video disc (DVD) or any other type of memory. "Non-transitory" computer-readable media excludes wired, wireless, optical or other communication links that transmit instantaneous electrical signals or other signals. Non-transitory computer-readable media include media that can store data permanently, and media that can store data and rewrite data later, such as rewritable optical discs 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 exemplary wireless network according to one embodiment of the present disclosure is shown;

[0018] Figure 2a An exemplary AP according to one embodiment of the present disclosure is shown;

[0019] Figure 2b An exemplary STA according to one embodiment of the present disclosure is shown;

[0020] Figure 3 An example of broadcast TWT negotiation according to an embodiment of the present disclosure is shown;

[0021] Figure 4 An example of performing broadcast TWT negotiation on one link to establish a broadcast TWT schedule on another link according to an embodiment of the present disclosure is shown;

[0022] Figure 5 shows an exemplary format of a Broadcast TWT Parameter Set field in a Broadcast TWT element according to an embodiment of the present disclosure; and

[0023] Figure 6 An exemplary process for facilitating broadcast TWT negotiation on one link between MLDs to establish broadcast TWT schedules on other links between the same MLDs according to one embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0024] The following discussion Figures 1 to 6 The various embodiments used to describe the principles of the present disclosure in this patent document are only for illustration and should not be interpreted in any way as limiting 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.

[0025] Embodiments of the present disclosure recognize that the current 802.11 specification is unclear about how to establish a broadcast TWT schedule on a link between an AP MLD and a non-AP MLD. According to the current specification, in order to establish a broadcast TWT schedule on a first link between an AP MLD and an associated non-AP MLD, a corresponding TWT negotiation will need to be performed on the first link—that is, an exchange of TWT setup frames corresponding to the broadcast TWT negotiation of the first link between the AP MLD and the non-AP MLD will need to occur on the first link.

[0026] Currently, it is not possible to perform broadcast TWT negotiation on a second link between an AP MLD and a non-AP MLD in order to establish a TWT schedule on a first link between the same AP MLD and a non-AP MLD. This may increase the latency of establishing a TWT schedule on the first link because a STA associated with a non-AP MLD and operating on the second link can access the channel faster than a STA associated with a non-AP MLD and operating on the first link.

[0027] Therefore, embodiments of the present disclosure provide a mechanism for facilitating broadcast TWT negotiation on one link between MLDs to establish broadcast TWT scheduling on other links between the same MLDs.

[0028] Figure 1 An exemplary wireless network 100 is shown according to one embodiment of the present disclosure. Figure 1 The 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.

[0029] 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 to 114 within a coverage area 120 of the AP 101. The APs 101 to 103 may communicate with each other and with the STAs 111 to 114 using Wi-Fi or other WLAN communication technologies.

[0030] Depending on the network type, other well-known terms such as "router" or "gateway" may be used instead of "access point" or "AP". 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, given that an AP also participates in the competition for a wireless channel, an AP may also be referred to as a STA (e.g., an AP STA). In addition, depending on the network type, other well-known terms such as "mobile station", "subscriber station", "remote terminal", "user equipment", "wireless terminal" or "user device" may be used instead of "station" or "STA". For convenience, the term "station" or "STA" is used in the present disclosure to refer to a remote wireless device that wirelessly accesses an AP or participates in the competition for a wireless channel in a WLAN, regardless of whether the STA is a mobile device (e.g., a mobile phone or smart phone) or is generally regarded as a fixed device (e.g., a desktop computer, an AP, a media player, a fixed sensor, a television, etc.). This type of STA may also be referred to as a non-AP STA.

[0031] In one embodiment of the present disclosure, each of the APs 101 and 103 and each of the STAs 111 to 114 may be an MLD. In such an embodiment, the APs 101 and 103 may be AP MLDs, and the STAs 111 to 114 may be non-AP MLDs. Each MLD is associated with more than one STA. For ease of explanation, an AP MLD is described herein as being associated with more than one AP (e.g., more than one AP STA), and a non-AP MLD is described herein as being associated with more than one STA (e.g., more than one non-AP STA).

[0032] The dashed lines illustrate the approximate extents of coverage areas 120 and 125, which are shown as generally 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.

[0033] As described in more detail below, one or more APs may include circuitry and / or programming to facilitate broadcast TWT negotiation on one link between MLDs in a WLAN to establish a broadcast TWT schedule on other links between the same MLDs. Figure 1 An 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 to 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 (e.g., external telephone networks or other types of data networks).

[0034] Figure 2a An exemplary AP 101 is shown according to one embodiment of the present disclosure. Figure 2a The illustrated embodiment of AP 101 is for illustration only, and Figure 1 The APs 103 may have the same or similar configurations. In the embodiments discussed below in this document, the AP 101 is an AP MLD. However, the APs have a wide variety of configurations, and Figure 2a The scope of the present disclosure is not limited to any particular implementation of the AP.

[0035] The AP MLD 101 is associated with a plurality of APs 202a to 202n (e.g., which may be referred to as AP1 to APn). Each of the associated APs 202a to 202n includes a plurality of antennas 204a to 204n, a plurality of RF transceivers 209a to 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.

[0036] The illustrated components of each associated AP 202a to 202n may represent the physical (PHY) layer and the lower media access control (LMAC) layer in the open systems 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 that are shared by all associated APs 202a to 202n.

[0037] For each associated AP 202a to 202n, the RF transceiver 209a to 209n receives an incoming RF signal (e.g., a signal transmitted by a STA in the network 100) from the antenna 204a to 204n. In some embodiments, each associated AP 202a to 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 associated AP may be at a different RF frequency. The RF transceiver 209a to 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 transmits the processed baseband signal to the controller / processor 224 for further processing.

[0038] For each associated AP 202a to 202n, the TX processing circuit 214 receives analog or digital data (e.g., 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 transceivers 209a to 209n receive the outgoing processed baseband or IF signals from the TX processing circuit 214 and up-convert the baseband or IF signals to RF signals transmitted via the antennas 204a to 204n. In embodiments where each associated AP 202a to 202n operates at a different bandwidth (e.g., 2.4 GHz, 5 GHz, or 6 GHz), the outgoing RF signals transmitted by each associated AP may be at a different RF frequency.

[0039] 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 through the RF transceivers 209a to 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 to 204n are weighted differently to effectively direct the outgoing signals to the desired direction. The controller / processor 224 may also support OFDMA operations, in which the output signals are allocated to different subsets of subcarriers for different recipients (e.g., different STAs 111 to 114). The controller / processor 224 may support any of a variety of other functions in the AP MLD 101, including facilitating broadcast TWT negotiation on one link between MLDs in the WLAN to establish broadcast TWT scheduling on other links between the same MLDs. 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 (e.g., 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 executing process.

[0040] 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 may support communication over any appropriate wired or wireless connection. For example, the interface 234 may allow the AP MLD 101 to communicate with a larger network (e.g., the Internet) over a wired or wireless local area network or over a wired or wireless connection. The interface 234 includes any appropriate structure (e.g., an Ethernet or RF transceiver) that supports communication over a wired or wireless connection. 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.

[0041] As described in more detail below, AP MLD 101 may include circuitry and / or programming for facilitating broadcast TWT negotiation on one link between MLDs in a WLAN to establish a broadcast TWT schedule on other links between the same MLDs. 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 2aeach component shown. As a specific example, the AP MLD 101 may include multiple interfaces 234, and the controller / processor 224 may support routing functions for routing data between different network addresses. As another specific example, although each associated AP 202a to 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 (e.g., one instance per RF transceiver) in one or more of the associated APs 202a to 202n. Alternatively, only one antenna and RF transceiver path may be included in one or more of the associated APs 202a to 202n (e.g., 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.

[0042] Figure 2b An exemplary STA 111 is shown according to one embodiment of the present disclosure. Figure 2b The embodiment of STA 111 shown is for illustration only, and Figure 1 STAs 111 to 115 may have the same or similar configurations. In the embodiments discussed below in this document, STA 111 is a non-AP MLD. However, STAs may have a wide variety of configurations, and Figure 2b The scope of the present disclosure is not limited to any particular implementation of a STA.

[0043] The non-AP MLD 111 is associated with a plurality of STAs 203a to 203n (for example, which may be referred to as STA1 to STAn). Each of the associated STAs 203a to 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 application programs 262.

[0044] The illustrated components of each associated STA 203a to 203n may represent the PHY layer and LMAC layer in the OSI networking model. In such embodiments, 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 associated STAs 203a to 203n.

[0045] For each associated STA 203a to 203n, the RF transceiver 210 receives an incoming RF signal transmitted by an AP of the network 100 from the antenna 205. In some embodiments, each associated STA 203a to 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 associated 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 transmits the processed baseband signal to the speaker 230 (e.g., for voice data) or the controller / processor 240 (e.g., for web browsing data) for further processing.

[0046] For each associated STA 203a to 203n, the TX processing circuit 215 receives analog or digital voice data from the microphone 220 or other outgoing baseband data (e.g., 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 transmitted via the antenna 205. In an embodiment where each associated STA 203a to 203n operates at a different bandwidth (e.g., 2.4 GHz, 5 GHz, or 6 GHz), the outgoing RF signal transmitted by each associated STA can be at a different RF frequency.

[0047] 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 through the RF transceiver 210, the RX processing circuit 225, and the TX processing circuit 215 according to well-known principles. The main controller / processor 240 may also include a processing circuit configured to facilitate broadcast TWT negotiation on one link between MLDs in the WLAN to establish a broadcast TWT schedule on other links between the same MLDs. In some embodiments, the controller / processor 240 includes at least one microprocessor or microcontroller.

[0048] The controller / processor 240 is also capable of executing other processes and programs resident in the memory 260, such as operations for facilitating broadcast TWT negotiation on one link between MLDs in the WLAN to establish broadcast TWT scheduling on other links between the same MLDs. The controller / processor 240 can move data into or out of the memory 260 as needed for the execution process. In some embodiments, the controller / processor 240 is configured to execute multiple applications 262 (e.g., applications for facilitating broadcast TWT negotiation on one link between MLDs in the WLAN to establish broadcast TWT scheduling on other links between the same MLDs). The controller / processor 240 can operate multiple applications 262 based on the OS program 261 or in response to a signal received from the AP. The main controller / processor 240 is also connected to an I / O interface 245, which provides the non-AP MLD111 with the ability to connect to other devices (e.g., laptop computers and handheld computers). The I / O interface 245 is a communication path between these accessories and the main controller 240.

[0049] 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).

[0050] 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 embodiment may be combined, further subdivided, or omitted, and additional components may be added as required. In a specific example, one or more of the associated STAs 203a to 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 fixed devices.

[0051] Figure 3 An example of a broadcast TWT negotiation according to an embodiment of the present disclosure is shown. In this example, 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 the AP MLD or non-AP MLD herein refer to the AP MLD 101 or the non-AP MLD 111, respectively. Although the AP MLD 101 is shown as having three associated APs (AP1, AP2, and AP3), and the non-AP MLD 111 is shown as having three associated STAs (STA1, STA2, and STA3), it should be understood that this is merely an example, and any appropriate MLD with any number of associated APs or STAs may be used. In this example, there are three links formed between the AP MLD and the non-AP MLD, namely, link 1 between AP1 and STA1, link 2 between AP2 and STA2, and link 3 between AP3 and STA3.

[0052] exist Figure 3 In the example, in order to establish a broadcast TWT schedule on a given link between an AP MLD and an associated non-AP MLD, a corresponding TWT negotiation needs to be performed on the same link. For example, in order to establish a first broadcast TWT schedule (e.g., a schedule including a TWT service period (SP) TWT SP1) on a first link (e.g., link 1) between an AP MLD and a non-AP MLD, an exchange of TWT setup frames (e.g., TWT request frame 302 and TWT response frame 304) corresponding to the broadcast TWT negotiation for the first broadcast TWT schedule needs to occur on the first link (link 1).

[0053] Various embodiments of the present disclosure facilitate performing a broadcast TWT negotiation on a second link between an AP MLD and a non-AP MLD in order to establish a broadcast TWT schedule on a first link between the same AP MLD and the non-AP MLD. Compared to performing this TWT negotiation on the first link, this can reduce the delay in establishing the TWT schedule on the first link because a STA associated with the non-AP MLD and operating on the second link can access the channel faster than a STA associated with the non-AP MLD and operating on the first link.

[0054] According to some embodiments, the TWT scheduling AP associated with the AP MLD and the TWT scheduling STA associated with the non-AP MLD used to negotiate to join the broadcast TWT scheduling will follow the general rules defined for TWT in the current 802.11 specifications (for example, the rules in Section 26.8.3.1 (General), Section 26.8.3.2 (Rules for TWT scheduling APs), and Section 26.8.3.3 (Rules for TWT scheduling STAs) of IEEE P802.11be D2.1) and the following additional rules: When negotiating the broadcast TWT scheduling, the TWT scheduling STA associated with the non-AP MLD or the TWT scheduling AP associated with the AP MLD may indicate (for example, in the broadcast TWT element transmitted in the TWT setup frame) the link between the AP MLD and the non-AP MLD for which it is negotiating. The TWT scheduling AP or TWT scheduling STA that transmits the broadcast TWT element may make a link indication in the link ID bitmap subfield in the broadcast TWT parameter set field corresponding to the broadcast TWT scheduling (discussed further below).

[0055] Figure 4 An example of performing broadcast TWT negotiation on one link to establish a broadcast TWT schedule on another link according to an embodiment of the present disclosure is shown. Figure 4 In the example, Figure 3 Similar to the example of , there are three links formed between AP MLDs and non-AP MLDs, namely, link 1 between AP1 and STA1, link 2 between AP2 and STA2, and link 3 between AP3 and STA3.

[0056] In this example, to establish a broadcast TWT schedule (e.g., a schedule including TWT SP 406) on a first link (e.g., link 2) between an AP MLD and a non-AP MLD, an exchange of TWT setup frames (e.g., TWT request frame 402 and TWT response frame 404) corresponding to a broadcast TWT negotiation for the broadcast TWT schedule occurs on a second link (e.g., link 1) between the same AP MLD and the non-AP MLD. Although the non-AP MLD is shown as transmitting the TWT request frame 402 and the AP MLD is shown as transmitting the TWT response frame 404, it should be understood that these roles can be reversed.

[0057] In some embodiments, a TWT request frame (e.g., TWT request frame 402) includes a broadcast TWT element having a broadcast TWT parameter set field corresponding to the broadcast TWT schedule being negotiated. A link indication may be included in the broadcast TWT parameter set field to indicate the link for which the broadcast TWT schedule is being negotiated.

[0058] Figure 5FIG. 5 shows an exemplary format of a broadcast TWT parameter set field 500 in a broadcast TWT element according to an embodiment of the present disclosure. Figure 5 In the example of , the broadcast TWT parameter set field 500 includes a link ID bitmap subfield 502.

[0059] According to one embodiment, the link ID bitmap subfield 502 in the broadcast TWT parameter set field 500 indicates whether the broadcast TWT parameter set field 500 is applicable to a specific link between the AP MLD and the non-AP MLD. If bit i in the link ID bitmap subfield 502 is set to 1, it indicates that the TWT negotiation corresponding to the broadcast TWT parameter set field 500 is applicable to the i-th link between the AP MLD and the non-AP MLD. Otherwise, the broadcast TWT parameter set field 500 is not applicable to the i-th link between the AP MLD and the non-AP MLD.

[0060] According to one embodiment, the presence of the link ID bitmap subfield 502 in the broadcast TWT parameter set field 500 can be indicated by the link ID bitmap present subfield in the control field of the broadcast TWT element. If the link ID bitmap present subfield in the control field is set to 1, the link ID bitmap subfield 502 is present in the broadcast TWT parameter set field 500. Otherwise, the link ID bitmap subfield 502 is not present in the broadcast TWT parameter set field 500.

[0061] According to one embodiment, if only one link is indicated in the link ID bitmap subfield in the broadcast TWT parameter set field transmitted by a TWT scheduling STA associated with a non-AP MLD or a TWT scheduling AP associated with an AP MLD, the corresponding broadcast TWT scheduling is negotiated for STAs associated with the same MLD and operates on the indicated link between the AP MLD and the non-AP MLD. In addition, the target wake-up time field in the broadcast TWT parameter set field will reference the timing synchronization function (TSF) time of the link indicated in the link ID bitmap subfield in the broadcast TWT parameter set field.

[0062] According to one embodiment, a TWT scheduling AP associated with an AP MLD or a TWT scheduling STA associated with a non-AP MLD (e.g., Figure 4 The AP MLD that receives the TWT request frame 402 in the TWT request frame 402 may then transmit a response frame (e.g., Figure 4The link is indicated in the link ID bitmap subfield of the corresponding broadcast TWT parameter set field in the TWT element in the TWT response frame 404 transmitted by the AP MLD in the received request frame. In this case, the link ID bitmap subfield in the response frame should indicate the same link as indicated in the corresponding broadcast TWT parameter set field in the TWT element in the received request frame.

[0063] In some embodiments, a broadcast TWT element may include multiple broadcast TWT parameter set fields. Each broadcast TWT parameter set field may correspond to a corresponding broadcast TWT schedule being negotiated. According to one embodiment, if the link ID bitmap exists subfield in the control field in such a broadcast TWT element is set to 1, all broadcast TWT parameter set fields contained in the broadcast TWT element should include a link ID bitmap subfield. If the link ID bitmap exists subfield is set to 0, any broadcast TWT parameter set field contained in the broadcast TWT element should not include a link ID bitmap subfield.

[0064] According to one embodiment, if a TWT scheduling AP associated with an AP MLD or a TWT scheduling STA associated with a non-AP MLD receives a broadcast TWT element with a link ID bitmap present subfield set to 0, it indicates that any broadcast TWT parameter sets contained in the received broadcast TWT element are applicable to the link on which the broadcast TWT element is received.

[0065] According to one embodiment, if the corresponding k-th link is disabled for the non-AP MLD through the TID-to-link mapping, the AP MLD or the non-AP MLD should not transmit the following TWT element on the link established between the AP MLD and the non-AP MLD: the element includes a TWT parameter set field including a link ID bitmap subfield, wherein the k-th bit in the bitmap is set to 1.

[0066] In accordance with some embodiments, in the context of multi-link operation, the R-TWT scheduling AP or R-TWT scheduling STA used to negotiate to join restricted TWT scheduling will follow the general rules for broadcasting TWT defined in the current 802.11 specifications (e.g., the rules in Section 35.8.3 (Broadcast TWT Operation) of IEEE P802.11be D2.1) and the additional rules described herein below.

[0067] According to one embodiment, for R-TWT operation between an AP MLD and a non-AP MLD, when a TID k of a corresponding direction (i.e., a downlink (DL) or uplink (UL) direction) is not mapped to a target link for which restricted TWT scheduling is being negotiated, the AP MLD or the non-AP MLD shall not transmit the following TWT element on any link established between the AP MLD and the non-AP MLD: the element includes an R-TWT parameter set, in which the kth bit in the Restricted TWT DL TID Bitmap subfield or the Restricted TWT UL TID Bitmap subfield (if present) is set to 1. In addition, if any TID is not mapped to a target link in the corresponding direction, the AP MLD or the non-AP MLD shall not transmit the following TWT element on any link between them: the element includes an R-TWT parameter set, in which the DL TID Bitmap Valid subfield or the UL TID Bitmap Valid subfield (if present) is set to 0.

[0068] According to one embodiment, an R-TWT scheduling AP that receives a request from a non-AP STA (e.g., a non-AP STA associated with a non-AP MLD) to join an R-TWT schedule (where the R-TWT schedule full subfield is set to 1) may reject the request. According to one embodiment, the R-TWT scheduling AP may respond with any of the following responses: accept TWT, reject TWT, spare TWT, or specify TWT. According to one embodiment, the R-TWT scheduling AP may adjust the TWT parameters of the R-TWT schedule to accommodate the request of the non-AP STA.

[0069] According to one embodiment, if a TWT scheduling STA associated with a non-AP MLD sends a TWT element to its associated AP (associated with AP MLD), the element including a link ID bitmap subfield in the broadcast TWT parameter set field, wherein the link indicated in the link ID bitmap subfield of the broadcast TWT parameter set field is a link different from the link on which the TWT element is sent, then the TWT setup command subfield in the request type field of the broadcast TWT parameter set field may be set to 0 (request TWT).

[0070] According to one embodiment, if a TWT scheduling STA associated with a non-AP MLD sends a TWT element to its associated AP (associated with the AP MLD), the element including a link ID bitmap subfield in the broadcast TWT parameter set field, wherein the link indicated in the link ID bitmap subfield of the broadcast TWT parameter set field is a link different from the link on which the TWT element is sent, then the TWT setup command subfield in the request type field of the broadcast TWT parameter set field cannot be set to 1 or 2 (TWT recommended or TWT required).

[0071] According to some embodiments, a first STA associated with a non-AP MLD and operating on a first link that negotiates to establish a TWT schedule for a second STA associated with the same non-AP MLD and operating on a second link may request to establish a broadcast TWT schedule for the second STA, where the broadcast TWT schedule already exists in the BSS. That is, the first STA may negotiate to have the second STA join the existing broadcast TWT schedule (i.e., become a member thereof). According to one such embodiment, in this case, the first STA can only request to establish a TWT schedule for the second STA if a TWT schedule already exists in the BSS (i.e., the first STA cannot request the TWT scheduling AP to create a new broadcast TWT schedule for the second STA). That is, a TWT request negotiated through cross-link TWT in MLD may only apply to a TWT schedule that already exists in the BSS.

[0072] Figure 6 An exemplary process 600 for facilitating broadcast TWT negotiation on one link between MLDs to establish broadcast TWT schedules on other links between the same MLDs is shown according to one embodiment of the present disclosure. Figure 6 The process 600 is discussed as being performed by a non-AP MLD, but it is understood that the corresponding AP MLD performs the corresponding process. Figure 6 The process is discussed as being performed by a WI-FI non-AP MLD, which includes a plurality of STAs, each STA including a transceiver configured to form a link with a corresponding AP associated with the WI-FI AP MLD. However, it is understood that any suitable wireless communication device may perform this process.

[0073] refer to Figure 6 , process 600 begins with the non-AP MLD generating (or parsing) a first message for broadcast TWT negotiation, wherein the first message indicates that the broadcast TWT negotiation is for a broadcast TWT schedule on at least one first link among the links between the non-AP MLD and the AP MLD (step 605). In the case where the non-AP MLD is the initiator of the broadcast TWT negotiation, the non-AP MLD generates the first message. When the AP MLD is the initiator of the broadcast TWT negotiation, the non-AP MLD parses the first message.

[0074] Then, the non-AP MLD transmits the first message to the AP MLD via the second link (step 610). In this case, the non-AP MLD is the initiator of the broadcast TWT negotiation. When the AP MLD is the initiator of the broadcast TWT negotiation, step 610 occurs before step 605 instead, and the non-AP MLD receives the first message from the AP MLD via the link at step 610.

[0075] In some embodiments of process 600, the first message includes a link ID bitmap associated with a broadcast TWT parameter set corresponding to a broadcast TWT schedule under negotiation, and the entry in the link ID bitmap corresponding to each of the first links is set to indicate that the broadcast TWT negotiation is for a broadcast TWT schedule on the first link. In such embodiments, the non-AP MLD receives (or generates) a second message for broadcast TWT negotiation as a response to the first message, and the second message includes a second link ID bitmap in a second broadcast TWT parameter set that corresponds to the broadcast TWT schedule under negotiation. An entry corresponding to each first link is set in the second link ID bitmap, and the transceiver of the first STA is also configured to receive a second message from the AP MLD or transmit a second message to the AP MLD via the second link.

[0076] In some embodiments of process 600, the first message includes a set of broadcast TWT parameters, each parameter set corresponding to a different broadcast TWT schedule being negotiated, and the first message includes an indication that either the first message includes a corresponding link ID bitmap associated with each broadcast TWT parameter set, or the first message does not include a link ID bitmap associated with any broadcast TWT parameter set. In some such embodiments, the indication that the first message does not include a link ID bitmap is an indication that all different broadcast TWT schedules are being negotiated for the second link.

[0077] In some embodiments of process 600, the first link is a link that has not been disabled for non-AP MLD via TID-to-link mapping.

[0078] In some embodiments of process 600, the broadcast TWT negotiation is for a restricted TWT schedule, and the first message includes an indication of an uplink (UL) TID and a downlink (DL) TID, for which UL traffic and DL traffic transmission will be allowed, respectively, according to the restricted TWT schedule. In these embodiments, the indicated UL TID and DL TID are mapped to the first link by TID-to-link mapping.

[0079] The above flow charts illustrate exemplary 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, the individual 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.

[0080] Although the present disclosure has been described using exemplary embodiments, various changes and modifications may be suggested to those skilled in the art. It is intended that the present disclosure encompasses such changes and modifications as fall within the scope of the appended claims. Any description in this application should not be construed 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, comprising: A plurality of stations STA, each STA comprising a transceiver configured to form a link with a corresponding AP of the AP MLD; as well as A processor, the processor being operably connected to the plurality of STAs, the processor being configured to generate or receive a first message for a broadcast target wake-up time TWT negotiation, wherein the first message indicates that the broadcast TWT negotiation is for a broadcast TWT schedule on at least one first link of the links, The transceiver of the first STA is further configured to transmit the first message to the AP MLD or receive the first message from the AP MLD through a second link among the links.

2. The non-AP MLD according to claim 1, wherein: The first message includes a link ID bitmap associated with a broadcast TWT parameter set corresponding to the broadcast TWT schedule under negotiation, and The entry in the link ID bitmap corresponding to each of the first links is set to indicate that the broadcast TWT negotiation is for the broadcast TWT scheduling on the first link.

3. The non-AP MLD according to claim 1 or claim 2, wherein: The processor is further configured to receive or generate a second message for the broadcast TWT negotiation as a response to the first message, The second message includes a second link ID bitmap in a second broadcast TWT parameter set, and the second broadcast TWT parameter set corresponds to the broadcast TWT schedule in the negotiation, The entry corresponding to each of the first links in the second link ID bitmap is set, and The transceiver of the first STA is further configured to receive the second message from the AP MLD or transmit the second message to the AP MLD through the second link.

4. A non-AP MLD as claimed in any preceding claim, wherein: The first message includes a plurality of broadcast TWT parameter sets, each broadcast TWT parameter set corresponding to a different negotiated broadcast TWT schedule, and The first message includes the following instructions: The first message contains a corresponding link ID bitmap associated with each broadcast TWT parameter set, or The first message does not include a link ID bitmap associated with any broadcast TWT parameter set.

5. A non-AP MLD as claimed in any preceding claim, wherein: Indicating that the first message does not contain a link ID bitmap indicates that all different broadcast TWT schedules are being negotiated for the second link.

6. A non-AP MLD as claimed in any preceding claim, wherein: Through the traffic identifier TID to link mapping, the first link has not been disabled for the non-AP MLD.

7. A non-AP MLD as claimed in any preceding claim, wherein: The broadcast TWT negotiation is for restricted TWT scheduling. The first message includes an indication of an uplink UL TID and a downlink DL TID for which UL traffic and DL traffic transmission are allowed respectively according to the restricted TWT scheduling, and The indicated UL TID and DL TID are mapped to the first link through TID-to-link mapping.

8. A wireless communication method performed by a non-access point AP multi-link device MLD, the method comprising: Generate or parse a first message for broadcast target wake time TWT negotiation, wherein the first message indicates that the broadcast TWT negotiation is for a broadcast TWT schedule on at least one first link of the links, and wherein the non-AP MLD includes a plurality of stations STA, each STA including a transceiver configured to form a link with a corresponding AP of the AP MLD; and The first message is transmitted to or received from the AP MLD through a second link among the links.

9. The method of claim 8, wherein: The first message includes a link ID bitmap associated with a broadcast TWT parameter set corresponding to the broadcast TWT schedule under negotiation, and The entry in the link ID bitmap corresponding to each of the first links is set to indicate that the broadcast TWT negotiation is for the broadcast TWT scheduling on the first link.

10. An access point AP multi-link device MLD, comprising: A plurality of APs, each AP comprising a transceiver configured to form a link with a corresponding station STA of the non-AP MLD; as well as A processor, the processor being operably connected to the plurality of APs, the processor being configured to generate or receive a first message for a broadcast target wake time TWT negotiation, wherein the first message indicates that the broadcast TWT negotiation is for a broadcast TWT schedule on at least one first link of the links, The transceiver of the first AP is further configured to transmit the first message to the non-AP MLD or receive the first message from the non-AP MLD through a second link among the links.

11. The AP MLD according to claim 10, wherein: The first message includes a link ID bitmap associated with a broadcast TWT parameter set corresponding to the broadcast TWT schedule under negotiation, and The entry in the link ID bitmap corresponding to each of the first links is set to indicate that the broadcast TWT negotiation is for the broadcast TWT scheduling on the first link.

12. The AP MLD according to claim 10 or claim 11, wherein: The processor is further configured to receive or generate a second message for the broadcast TWT negotiation as a response to the first message, The second message includes a second link ID bitmap in a second broadcast TWT parameter set, and the second broadcast TWT parameter set corresponds to the broadcast TWT schedule in the negotiation, The entry corresponding to each of the first links in the second link ID bitmap is set, and The transceiver of the first AP is further configured to receive the second message from the non-AP MLD or transmit the second message to the non-AP MLD through the second link.

13. The AP MLD according to any one of claims 10 to 12, wherein: The first message includes a plurality of broadcast TWT parameter sets, each broadcast TWT parameter set corresponding to a different negotiated broadcast TWT schedule, and The first message includes the following instructions: The first message contains a corresponding link ID bitmap associated with each broadcast TWT parameter set, or The first message does not include a link ID bitmap associated with any broadcast TWT parameter set.

14. The AP MLD according to any one of claims 10 to 13, wherein: Through the traffic identifier TID to link mapping, the first link has not been disabled for the non-AP MLD.

15. The AP MLD according to any one of claims 10 to 14, wherein: The broadcast TWT negotiation is for restricted TWT scheduling. The first message includes an indication of an uplink UL TID and a downlink DL TID for which UL traffic and DL traffic transmission are allowed respectively according to the restricted TWT scheduling, and The indicated UL TID and DL TID are mapped to the first link through TID-to-link mapping.

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