Multi-AP cooperation based on TWT

Abstract

A first access point (AP) device receives information related to a target wakeup time (TWT) schedule established in a second basic service set (BSS). The second BSS is established by the second AP device. A first AP device should ensure that a transmission opportunity (TXOP) established in a first BSS ends before a start time of a TWT service period of a TWT schedule established in a second BSS. The first BSS is established by the first AP device.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communication systems, and more particularly to multi-AP coordination in, for example but not limited to, wireless communication systems. Background Art

[0002] Since the late 1990s, wireless local area network (WLAN) technology has been evolving toward increasing data rates and continues to grow in various markets, including homes, businesses, and hotspots. WLANs allow devices to access the internet in the 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz frequency bands. WLANs are based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards. The IEEE 802.11 family of standards is designed to increase speed, reliability, and extend the range of wireless networks.

[0003] WLAN devices are increasingly required to support a variety of delay-sensitive or real-time applications, such as augmented reality (AR), robotics, artificial intelligence (AI), cloud computing, and self-driving cars. To achieve the extremely low latency and high throughput required for such applications, multi-link operation (MLO) is recommended for WLANs. A WLAN is formed by WLAN devices within a limited area, such as a home, school, apartment, or office building. Each WLAN device may have one or more stations (STAs), such as access point (AP) STAs and non-access point (non-AP) STAs.

[0004] MLO enables a non-AP Multi-Link Device (MLD) to establish multiple links with an AP MLD. Each of the multiple links can independently perform channel access and frame exchange between the non-AP MLD and the AP MLD, which can reduce latency and increase throughput.

[0005] The description given in the Background section should not be considered as prior art merely because it is set forth in the Background section. The Background section may describe various aspects or embodiments of the present disclosure. Summary of the Invention

[0006] Technical Solution One aspect of the present disclosure provides a first access point (AP) device in a wireless network. The first AP device includes a memory and a processor coupled to the memory. The processor is configured to: receive information related to a target wake time (TWT) schedule established in a second basic service set (BSS), wherein the second BSS is established by a second AP device, and ensure that a transmission opportunity (TXOP) established in a first BSS ends before a start time of a TWT service period of the TWT schedule established in the second BSS. The first BSS is established by the first AP device.

[0007] In some embodiments, the processor is further configured to cause: during the TWT service period, no frames to be sent to any station associated with the first AP device in the first BSS.

[0008] In some embodiments, the processor is further configured to: not send frames to any station associated with the first AP device in the first BSS after the start time of the TWT service period, and initiate communication with the station associated with the first AP device within a time indicated from the second AP device, wherein the time is before the end time of the TWT service period.

[0009] In some embodiments, the TWT scheduling established in the second BSS is associated with communication of delay sensitive traffic.

[0010] In some embodiments, the processor is further configured to: not send frames to any station associated with the first AP device in the first BSS after the start time of the TWT service period, receive a trigger frame to request a response frame from the second AP device, and initiate communication with the station associated with the first AP device before the end time of the TWT service period.

[0011] In some embodiments, the processor is further configured to: receive a request frame for multi-AP coordination from the second AP device, and send a response frame indicating acceptance of the request for multi-AP coordination to the second AP device.

[0012] In some embodiments, the processor is further configured to: receive an advertisement frame for the multi-AP coordination from the second AP device, and send a frame indicating the ability to participate in the multi-AP coordination to the second AP device.

[0013] In some embodiments, information related to the TWT scheduling is received from the second AP device.

[0014] In some embodiments, the processor is further configured to cause: sending a TWT element including information for the TWT schedule to one or more stations associated with the first AP device.

[0015] In some embodiments, the TWT element includes information indicating that the TWT scheduling is established in the second BSS.

[0016] In some embodiments, the processor is further configured to: receive a request frame for multi-AP coordination from the controller, send a response frame to the controller indicating acceptance of the request for multi-AP coordination, receive TWT coordination information including information related to the TWT scheduling from the controller, and send a confirmation to the controller in response to the TWT coordination information.

[0017] One aspect of the present disclosure provides a station in a wireless network. The station includes a memory and a processor coupled to the memory. The processor is configured to: receive a target wake time (TWT) element from a first AP device associated with the station, wherein the TWT element includes information indicating that a TWT schedule corresponding to the TWT element is established in a second service set (BSS) established by a second AP device, and ensure that a transmission opportunity (TXOP) established in a first BSS ends before a start time of a TWT service period of the TWT schedule, wherein the first BSS is established by the first AP device.

[0018] In some embodiments, the processor is further configured to: not send frames to the first AP device during the TWT service period.

[0019] In some embodiments, the processor is further configured to: not send frames to the first AP device after the start time of the TWT service period, and initiate communication with the first AP device within a time indicated by the first AP device, the time being before the end time of the TWT service period.

[0020] In some embodiments, the processor is further configured to: not send frames to the first AP device after the start time of the TWT service period, and initiate communication with the first AP device when a trigger frame requesting a response frame is received from the first AP device before the end time of the TWT service period.

[0021] In some embodiments, the TWT scheduling established in the second BSS is associated with communication of delay-sensitive traffic.

[0022] One aspect of the present disclosure provides a first access point (AP) device in a wireless network. The first AP device includes a memory and a processor coupled to the memory. The processor is configured to: send a request frame for multi-AP coordination to a second AP device, wherein the request frame includes a TWT schedule established in a first basic service set (BSS), and the first BSS is established by the first AP device; and receive a response frame from the second AP device indicating acceptance of the multi-AP coordination.

[0023] In some embodiments, the processor is further configured to: send a notification frame for the multi-AP coordination to one or more second AP devices, wherein the notification frame includes mode information for the multi-AP coordination, and receive a frame indicating the ability to participate in the multi-AP coordination from the second AP device.

[0024] In some embodiments, the TWT scheduling is associated with communication of delay-sensitive traffic.

[0025] In some embodiments, the processor is further configured to: send a trigger frame to the second AP device before the end time of the TWT service period corresponding to the TWT schedule, wherein the trigger frame indicates that the second AP is allowed to initiate communication with the associated station in the second BSS. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 An example of a wireless network according to an embodiment is shown.

[0027] Figure 2A An example of an AP according to an embodiment is shown.

[0028] Figure 2B An example of a STA according to an embodiment is shown.

[0029] Figure 3 An example of a multi-link communication operation according to an embodiment is shown.

[0030] Figure 4 An example of a separate TWT operation according to an embodiment is shown.

[0031] Figure 5 An example of broadcast TWT operation according to an embodiment is shown.

[0032] Figure 6 An example of broadcast TWT operation according to an embodiment is shown.

[0033] Figure 7 An example of separate TWT negotiation between an AP MLD and a non-AP MLD according to an embodiment is shown.

[0034] Figures 8A to 8C An example illustrating interference from a neighboring BSS according to an embodiment is shown.

[0035] Figure 9 An example of multi-AP coordination according to an embodiment is shown.

[0036] Figure 10 An example of Mode 1 R-TWT multi-AP coordination according to an embodiment is shown.

[0037] Figure 11An example of Mode 2 R-TWT multi-AP coordination according to an embodiment is shown.

[0038] Figure 12 Example operations of Mode 5 R-TWT multi-AP coordination according to an embodiment are shown.

[0039] Figure 13 An example format of a TWT element according to an embodiment is shown.

[0040] Figure 14 A flow chart illustrating example operations for multi-AP coordination according to an embodiment is shown.

[0041] Figure 15 An example architecture for coordinated TWT negotiation according to an embodiment is shown.

[0042] Figure 16 An example of a Type 1 architecture for C-TWT negotiation according to an embodiment is shown.

[0043] Figure 17 Another example of a Type 1 architecture for C-TWT negotiation according to an embodiment is shown.

[0044] Figure 18 A flowchart illustrating example operations of TWT multi-AP coordination according to an embodiment is shown.

[0045] Figure 19 An example of a Type 2 architecture for C-TWT negotiation according to an embodiment is shown.

[0046] Figure 20 An example timing diagram of a Type 2 architecture for C-TWT negotiation is shown according to an embodiment.

[0047] Figure 21 A flowchart illustrating example operations of TWT multi-AP coordination according to an embodiment is shown.

[0048] In one or more embodiments, all components depicted in each figure may not be required, and one or more embodiments may include additional components not shown in the figures. Without departing from the scope of this disclosure, the arrangement and type of components may be changed. Additional components, different components, or fewer components may be used within the scope of this disclosure. DETAILED DESCRIPTION

[0049] The detailed description set forth below in conjunction with the accompanying drawings is intended to describe various embodiments and is not intended to represent the only embodiment in which the subject technology can be practiced. On the contrary, the detailed description includes specific details for providing a thorough understanding of the subject technology of the present invention. As will be appreciated by those skilled in the art, the described embodiments can be modified in various ways without departing from the scope of this disclosure. Therefore, the drawings and description should be considered illustrative in nature, rather than restrictive. The same reference numerals represent the same elements.

[0050] The following description is directed to certain embodiments to illustrate the innovative aspects of the present disclosure. However, one of ordinary skill in the art will readily recognize that the teachings herein can be applied in a variety of different ways. The examples in this disclosure are based on WLAN communications according to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, including the IEEE 802.11be standard and any future revisions of the IEEE 802.11 standard. However, the described embodiments can be implemented in any device, system, or network capable of sending and receiving radio frequency (RF) signals in accordance with the IEEE 802.11 standard, the Bluetooth standard, Global System for Mobile Communications (GSM), GSM / General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio (TETRA), Wideband CDMA (W-CDMA), Evolution-Data Optimized (EV-DO), 1xEV-DO, EV-DO Rev A, EV-DO Rev B, High Speed ​​Packet Access (HSPA), High Speed ​​Downlink Packet Access (HSDPA), High Speed ​​Uplink Packet Access (HSUPA), Evolved High Speed ​​Packet Access (HSPA+), Long Term Evolution (LTE), 5G NR (New Radio), AMPS, or other known signals for communication within a wireless, cellular, or Internet of Things (IoT) network, such as a system utilizing technology of 3G, 4G, 5G, 6G, or further implementations thereof.

[0051] Depending on the type of network, other well-known terms may be used instead of "access point" or "AP," such as "router" or "gateway." For convenience, the term "AP" as used in this disclosure refers to a network infrastructure component that provides wireless access to remote terminals. In a WLAN, assuming that the AP also competes for a wireless channel, the AP may also be referred to as a STA. In addition, depending on the type of network, 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" as used in this disclosure refer to a remote wireless device that wirelessly accesses an AP or competes for a wireless channel in a WLAN, regardless of whether the STA is a mobile device (such as a mobile phone or smartphone) or a device generally considered to be stationary (such as a desktop computer, AP, media player, stationary sensor, television, etc.).

[0052] Multi-Link Operation (MLO) is a key feature currently being developed by standards bodies for the next-generation Extremely High Throughput (EHT) Wi-Fi systems in IEEE 802.11be. Wi-Fi devices that support MLO are called Multi-Link Devices (MLDs). Using MLO, non-AP MLDs can discover, authenticate, associate, and set up multiple links with AP MLDs. Channel access and frame exchange are possible on each link between the AP MLD and the non-AP MLD.

[0053] Figure 1 An example of a wireless network 100 is shown according to an embodiment. Figure 1 The embodiment of the wireless network 100 shown in FIGURE 1 is for illustration purposes only. Other embodiments of the wireless network 100 may be used without departing from the scope of this disclosure.

[0054] like Figure 1 As shown, the wireless network 100 may include multiple wireless communication devices. Each wireless communication device may include one or more stations (STAs). A STA may be a logical entity that is a single addressable instance of the media access control (MAC) layer and the physical (PHY) layer that interfaces to a wireless medium. STAs may be classified as access point (AP) STAs and non-access point (non-AP) STAs. An AP STA may be an entity that provides access to distribution system services for associated STAs via a wireless medium. A non-AP STA may be a STA that is not included in an AP-STA. To simplify the description, an AP STA may be referred to as an AP and a non-AP STA may be referred to as a STA. In Figure 1In the example of FIG, APs 101 and 103 are wireless communication devices, each of which may include one or more AP STAs. In such an embodiment, APs 101 and 103 may be AP Multi-Link Devices (MLDs). Similarly, STAs 111-114 are wireless communication devices, each of which may include one or more non-AP STAs. In such an embodiment, STAs 111-114 may be non-AP MLDs.

[0055] 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. AP 101 provides wireless access to network 130 for a plurality of stations (STAs) 111-114 within a coverage area 120 of AP 101. APs 101 and 103 may communicate with each other and with the STAs using Wi-Fi or other WLAN communication technologies.

[0056] Depending on the type of network, other well-known terms may be used instead of "access point" or "AP," such as "router" or "gateway." For convenience, the term "AP" as used in this disclosure refers to a network infrastructure component that provides wireless access to remote terminals. In a WLAN, assuming that the AP also competes for a wireless channel, the AP may also be referred to as a STA. In addition, depending on the type of network, 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" as used in this disclosure refer to a remote wireless device that wirelessly accesses an AP or competes for a wireless channel in a WLAN, regardless of whether the STA is a mobile device (such as a mobile phone or smartphone) or a device generally considered to be stationary (such as a desktop computer, AP, media player, stationary sensor, television, etc.).

[0057] exist Figure 1 , dashed lines illustrate the approximate extents of coverage areas 120 and 125 of APs 101 and 103, which are shown as generally circular for purposes of illustration and explanation. It should be clearly understood that, depending on the configuration of the APs, coverage areas associated with the APs, such as coverage areas 120 and 125, may have other shapes, including irregular shapes.

[0058] As described in more detail below, one or more APs may include circuitry and / or programming for managing Multi-User Multiple Input Multiple Output (MU-MIMO) and Orthogonal Frequency Division Multiple Access (OFDMA) channel sounding in a WLAN. Figure 1 One example of a wireless network 100 is shown, but may be Figure 1Various changes may be made. For example, wireless network 100 may include any number of APs and any number of STAs in any suitable arrangement. Furthermore, AP 101 may communicate directly with any number of STAs and provide these STAs with wireless broadband access to network 130. Similarly, each of APs 101 and 103 may communicate directly with network 130 and provide STAs with direct wireless broadband access to network 130. Furthermore, APs 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.

[0059] Figure 2A An example of an AP 101 according to an embodiment is shown. Figure 2A The embodiment of the AP 101 shown in FIG is for illustration purposes, and Figure 1 The APs 103 may have the same or similar configurations. However, there is a wide range of AP configurations, and Figure 2A The scope of this disclosure is not limited to any particular implementation of an AP.

[0060] like Figure 2A As shown, AP 101 may include multiple antennas 204a-204n, multiple radio frequency (RF) transceivers 209a-209n, transmit (TX) processing circuitry 214, and receive (RX) processing circuitry 219. AP 101 may also include a controller / processor 224, memory 229, and a backhaul or network interface 234. The RF transceivers 209a-209n receive incoming RF signals from the antennas 204a-204n, such as signals transmitted by STAs in network 100. The RF transceivers 209a-209n downconvert the incoming RF signals to generate intermediate frequency (IF) or baseband signals. The IF or baseband signals are sent to RX processing circuitry 219, which generates processed baseband signals by filtering, decoding, and / or digitizing the baseband or IF signals. The RX processing circuitry 219 sends the processed baseband signals to the controller / processor 224 for further processing.

[0061] The TX processing circuitry 214 receives analog or digital data (such as voice data, web page 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 processed baseband or IF signals. 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 into RF signals that are transmitted via the antennas 204a-204n.

[0062] The controller / processor 224 may include one or more processors or other processing devices that control the overall operation of the AP 101. For example, the controller / processor 224 may control the reception of uplink signals and the transmission of downlink signals by the RF transceivers 209a-209n, RX processing circuitry 219, and TX processing circuitry 214 in accordance with well-known principles. The controller / processor 224 may also support additional functionality, such as more advanced wireless communication functionality. For example, the controller / processor 224 may support beamforming or directional routing operations, in which the output signals from the multiple antennas 204a-204n are weighted differently to effectively steer the output signals in a desired direction. The controller / processor 224 may also support OFDMA operations, in which the output signals are assigned to different subcarrier subsets for different recipients (e.g., different STAs 111-114). The controller / processor 224 may support any of a variety of other functions within the AP 101, including the combination of DL MU-MIMO and OFDMA within the same transmission opportunity. In some embodiments, the controller / processor 224 may include at least one microprocessor or microcontroller. The controller / processor 224 is also capable of executing programs and other processes, such as the OS, that reside in the memory 229. The controller / processor 224 can move data into or out of the memory 229 as required by the executing process.

[0063] Controller / processor 224 is also coupled to a backhaul or network interface 234. Backhaul or network interface 234 enables AP 101 to communicate with other devices or systems via a backhaul connection or over a network. Interface 234 can support communication via any suitable wired or wireless connection. For example, interface 234 can enable AP 101 to communicate via a wired or wireless local area network or via a wired or wireless connection to a larger network (such as the Internet). Interface 234 can include any suitable structure that supports communication via a wired or wireless connection, such as an Ethernet or RF transceiver. Memory 229 is coupled to controller / processor 224. A portion of memory 229 can include RAM, and another portion of memory 229 can include flash memory or other ROM.

[0064] As described in more detail below, AP 101 may include circuitry and / or programming for managing the channel sounding process in a WLAN. Figure 2A An example of AP 101 is shown, but the Figure 2A For example, AP101 may include Figure 2A. As a specific example, the AP may include multiple interfaces 234, and the controller / processor 224 may support routing functionality to route data between different network addresses. As another example, although shown as including a single instance of the TX processing circuit 214 and a single instance of the RX processing circuit 219, the AP 101 may include multiple instances of each TX processing circuit and RX processing circuit (such as one per RF transceiver). Alternatively, only one antenna and RF transceiver path may be included, 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.

[0065] like Figure 2A As shown, in some embodiments, AP 101 may be an AP MLD that includes multiple APs 202a-202n. Each AP 202a-202n is associated with AP MLD 101 and includes multiple antennas 204a-204n, multiple radio frequency (RF) transceivers 209a-209n, transmit (TX) processing circuitry 214, and receive (RX) processing circuitry 219. Each AP 202a-202n may independently communicate with controller / processor 224 and other components of AP MLD 101. Figure 2A Each AP 202a-202n is shown with a separate multiple antennas, but each AP 202a-202n may share multiple antennas 204a-204n rather than requiring separate multiple antennas.Each AP 202a-202n may represent a physical (PHY) layer and a lower medium access control (MAC) layer.

[0066] Figure 2B An example of STA 111 according to an embodiment is shown. Figure 2B The embodiment of STA 111 shown in FIG is for illustration purposes. Figure 1 STAs 111-114 may have the same or similar configurations. However, STAs have a variety of configurations. Figure 2B The scope of this disclosure is not limited to any particular implementation of STA.

[0067] like Figure 2B As shown, STA 111 may include antenna(s) 205, RF transceiver 210, TX processing circuitry 215, microphone 220, and RX processing circuitry 225. STA 111 may also include speaker 230, controller / processor 240, input / output (I / O) interface (IF) 245, touch screen 250, display 255, and memory 260. Memory 260 may include an operating system (OS) 261 and one or more applications 262.

[0068] RF transceiver 210 receives incoming RF signals from antenna 205, transmitted by an AP of network 100. RF transceiver 210 downconverts the incoming RF signals to generate an IF or baseband signal. The IF or baseband signal is sent to RX processing circuitry 225, which filters, decodes, and / or digitizes the baseband or IF signal to generate a processed baseband signal. RX processing circuitry 225 sends the processed baseband signal to speaker 230 (e.g., for voice data) or controller / processor 240 for further processing (e.g., for web browsing data).

[0069] TX processing circuitry 215 receives analog or digital voice data from microphone 220 or other outgoing baseband data (such as web page data, email, or interactive video game data) from controller / processor 240. TX processing circuitry 215 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. RF transceiver 210 receives the outgoing processed baseband or IF signal from TX processing circuitry 215 and up-converts the baseband or IF signal into an RF signal for transmission via antenna 205.

[0070] 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 STA 111. In one such operation, the controller / processor 240 controls the RF transceiver 210, the RX processing circuit 225, and the TX processing circuit 215 to receive downlink signals and transmit uplink signals according to well-known principles. The controller / processor 240 may also include processing circuitry configured to provide management of the channel sounding process in the WLAN. In some embodiments, the controller / processor 240 may include at least one microprocessor or microcontroller.

[0071] Controller / processor 240 is also capable of executing other processes and programs residing in memory 260, such as operations for managing the channel sounding process in the WLAN. Controller / processor 240 can move data into or out of memory 260 as needed by the executed processes. In some embodiments, controller / processor 240 is configured to execute multiple applications 262, such as those for channel sounding, including feedback calculations based on received Null Data Packet Advertisements (NDPAs) and Null Data Packets (NDPs), and the transmission of beamforming feedback reports in response to trigger frames (TFs). Controller / processor 240 can operate multiple applications 262 based on OS program 261 or in response to signals received from the AP. Controller / processor 240 is also coupled to I / O interface 245, which provides STA 111 with the ability to connect to other devices, such as laptops and handheld computers. I / O interface 245 serves as the communication path between these accessories and the main controller / processor 240.

[0072] Controller / processor 240 is also coupled to input 250 (such as a touch screen) and display 255. An operator of STA 111 can use input 250 to enter data into STA 111. Display 255 can be a liquid crystal display, a light-emitting diode display, or other display capable of presenting text (such as from a website) and / or at least limited graphics. Memory 260 is coupled to controller / processor 240. A portion of memory 260 may include random access memory (RAM), while another portion of memory 260 may include flash memory or other read-only memory (ROM).

[0073] although Figure 2B An example of STA 111 is shown. Figure 2B Make various changes. For example, Figure 2B The various components in the 240 may be combined, further subdivided, or omitted, and additional components may be added as needed. In a specific example, the STA 111 may include any number of antennas 205 for MIMO communication with the AP 101. In another example, the STA 111 may not include voice communication, 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 STA 111 is shown configured as a mobile phone or smartphone, but the STA may be configured to operate as other types of mobile or stationary devices.

[0074] like Figure 2BAs shown, in some embodiments, STA 111 may be a non-AP MLD that includes multiple STAs 203a-203n. Each STA 203a-203n is associated with non-AP MLD 111 and includes (one or more) antennas 205, RF transceiver 210, TX processing circuitry 215, and RX processing circuitry 225. Each STA 203a-203n may independently communicate with controller / processor 240 and other components of non-AP MLD 111. Figure 2B Each STA 203a-203n is shown with a separate antenna, but each STA 203a-203n may share antenna 205 rather than requiring a separate antenna.Each STA 203a-203n may represent a physical (PHY) layer and a lower medium access control (MAC) layer.

[0075] Figure 3 An example of a multi-link communication operation according to an embodiment is shown. The multi-link communication operation can be used in the IEEE 802.11be standard and any future revisions of the IEEE 802.11 standard. Figure 3 In the example, AP MLD 310 can be Figure 1 The wireless communication devices 101 and 103 in the embodiment of the present invention and the non-AP MLD 320 may be Figure 1 One of the wireless communication devices 111-114 in.

[0076] like Figure 3 As shown, AP MLD 310 may include multiple subordinate APs, such as AP 1, AP 2, and AP 3. Each subordinate AP may include a PHY interface to the wireless medium (Link 1, Link 2, or Link 3). AP MLD 310 may include a single MAC Service Access Point (SAP) 318, through which subordinate APs of AP MLD 320 communicate with higher layers (Layer 3 or the network layer). Each subordinate AP of AP MLD 310 may have a different MAC address (lower MAC address) than any other subordinate AP of AP MLD 320. AP MLD 310 may have an MLD MAC address (upper-layer MAC address), and the subordinate APs share the single MAC SAP 318 at Layer 3. Consequently, the subordinate APs share a single IP address, and Layer 3 identifies AP MLD 310 by assigning a single IP address.

[0077] A non-AP MLD 320 may include multiple subordinate STAs, such as STA 1, STA 2, and STA 3. Each subordinate STA may include a PHY interface to a wireless medium (Link 1, Link 2, or Link 3). The non-AP MLD 320 may include a single MAC SAP 328 through which the subordinate STAs of the non-AP MLD 320 communicate with higher layers (Layer 3 or the network layer). Each subordinate STA of the non-AP MLD 320 may have a different MAC address (lower MAC address) than any other subordinate STA of the non-AP MLD 320. The non-AP MLD 320 may have an MLD MAC address (upper-layer MAC address), and the subordinate STAs share the single MAC SAP 328 at Layer 3. Consequently, the subordinate STAs share a single IP address, and Layer 3 identifies the non-AP MLD 320 by assigning the single IP address.

[0078] AP MLD 310 and non-AP MLD 320 can set up multiple links between their associated APs and STAs. In this example, AP 1 and STA 1 can set up Link 1, which operates in the 2.4 GHz band. Similarly, AP 2 and STA 2 can set up Link 2, which operates in the 5 GHz band, and AP 3 and STA 3 can set up Link 3, which operates in the 6 GHz band. Each link can independently enable channel access and frame exchange between AP MLD 310 and non-AP MLD 320, which can improve data throughput and reduce latency. After associating with an AP MLD on a set of links (setting up links), each non-AP device is assigned a unique association identifier (AID).

[0079] The following documents are incorporated by reference into this disclosure in their entirety as if fully set forth herein: i) IEEE 802.11-2020, “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications” and ii) IEEE P802.11be / D3.0, “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications”.

[0080] Target Wake Time (TWT) operation is a power management feature in WLAN networks. TWT operation was introduced in the IEEE 802.11ah standard and later modified in the IEEE 802.11ax standard. TWT operation enables the AP to manage activity within the Basic Service Set (BSS) to minimize contention between STAs and reduce the required wake-up time for STAs during TWT operation. This is achieved by assigning STAs to operate on non-overlapping time or frequency and performing frame exchange sequences during pre-scheduled service periods. In TWT operation, STAs can wake up at pre-scheduled times negotiated with the AP or another STA in the BSS. STAs do not need to know the TWT parameter values ​​of other STAs within the BSS or STAs in other BSSs. STAs do not need to know when a TWT service period (SP) is used to exchange frames with other STAs. Frames transmitted during a TWT SP can use any PPDU (Physical Layer Protocol Data Unit) format supported by the STA pair that has established the corresponding TWT protocol, including but not limited to HE MU (Efficient Multi-User) PPDUs and HE TB (Efficient Trigger-based) PPDUs.

[0081] The EEE 802.11 standard describes two types of TWT operations: individual TWT operations and broadcast TWT operations. In individual TWT operations, an individual TWT protocol can be established between two STAs or between a STA and an AP. Negotiation of individual TWT operations can be performed separately between two STAs or between a STA and an AP. An AP can sign a TWT agreement with multiple STAs. Any changes to the TWT agreement between an AP and one STA will not affect the TWT agreement between the AP and other STAs.

[0082] Figure 4 An example of a separate TWT operation according to an embodiment is shown. Figure 4 The operations depicted in FIG. 5 are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation.

[0083] exist Figure 4 In , STA 1 and STA 2 are TWT requesting STAs, and AP is TWT responding STA. Figure 4In the example shown in FIG4 , STA1 sends a TWT request 401 to the AP to set up a triggered TWT protocol. The AP accepts the TWT request 401 with STA 1 and confirms the acceptance in a TWT response 403 sent to STA 1. Subsequently, the AP sends an unsolicited TWT response 405 to STA 2 to set up a triggered TWT protocol with STA 2. Both TWT protocols are set up according to the advertised TWT. During the triggered TWT SP, the AP sends a basic trigger frame 407 to the TWT requesting STAs (STA 1 and STA 2), which may indicate that they are awake during the TWTSP. STA 1 indicates that it is awake by sending a PS (power save) poll frame 409, and STA 2 indicates that it is awake by sending a QoS (quality of service) null frame 411 in response to the basic trigger frame 407. Subsequently, the AP sends a multi-STA block acknowledgment (Ack) 413 frame and a DL MU (downlink multi-user) PPDU 415 to both STA 1 and STA 2. Afterwards, STA1 and STA 2 send Block Ack frames 417 and 419 to the AP respectively, and then enter the sleep state.

[0084] On the other hand, Broadcast TWT operates in a membership-based manner. In Broadcast TWT operation, the AP can set up a shared TWT session for a group of STAs. The AP is typically the controller of the Broadcast TWT schedule. A non-AP STA in the BSS can request membership in the Broadcast TWT schedule, or the AP can send an unsolicited response to the STA to make the STA a member of the Broadcast TWT schedule maintained by the AP in the BSS. The AP can advertise and maintain multiple Broadcast TWT schedules in the BSS. When a change is made to any Broadcast TWT schedule in the BSS, it can affect all or some of the STAs that are members of the corresponding Broadcast TWT schedule.

[0085] Figure 5 An example of broadcast TWT operation according to an embodiment is shown. Figure 5 The operations depicted in FIG. 5 are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation.

[0086] exist Figure 5 In , STA 1 and STA 2 are TWT scheduled STAs, and AP is TWT scheduling AP. Figure 5In the example of , STA 1 and the AP may conduct an optional TBTT (target beacon transmission time) negotiation by exchanging a TWT request frame 501 and a TWT response frame 503. After the first TBTT, the AP sends a beacon frame 505 including a broadcast TWT element indicating a broadcast TWT SP. During the TWT SP, the AP may send a trigger frame or a downlink bufferable unit (BU) to the STAs (STA 1 and STA 2) for which the TWT is scheduled. STA 1 and STA 2 wake up to receive the beacon frame 505 to determine the broadcast TWT. During the triggered TWT SP, the AP sends a basic trigger frame 507 to STA 1 and STA 2, indicating that they are awake during the TWT SP. STA 1 indicates that it is awake by sending a PS-poll frame 509, and STA 2 indicates that it is awake by sending a QoS null frame 511 in response to the basic trigger frame 508. STA 1 and STA 2 receive their DL BUs in subsequent frame exchanges with the AP (e.g., Multi-STA Block ACK 513, DL MU PPDU 515, and Block ACKs 517 and 519) and enter a sleep state outside of the TWT SP. After the TWT SP, the AP periodically sends beacon frames 521 and 523 to STA 1 and STA 2. As shown in the figure, the AP can advertise / announce and maintain multiple broadcast TWT schedules in the BSS. When a change is made to any broadcast TWT schedule, it can affect all STAs that are members of the specific TWT schedule.

[0087] Figure 6 An example of broadcast TWT operation according to an embodiment is shown. Figure 6 The operations depicted in FIG. 5 are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation.

[0088] exist Figure 6 In the example, STA 1 establishes a broadcast TWT schedule using STA 1. STA 1 is the STA for which TWT is scheduled, and AP ( Figure 6 (not shown) is the associated TWT scheduling AP. In the present disclosure, the STA for which TWT is scheduled is the STA that follows the broadcast TWT schedule provided in the broadcast TWT element. The TWT scheduling AP is the AP that schedules broadcast TWT and provides these broadcast TWT schedules in the broadcast TWT element. In the broadcast TWT parameter set field of the broadcast TWT element, t1 is the value of the target wake-up time indicated in the Target Wake-up Time field of the Broadcast TWT Parameter Set field of the Broadcast TWT element. t1 This is the ideal time for STA 1 to initiate the frame exchange sequence with AP 1. t1Initially, the duration that STA 1 needs to stay awake may be the value of the nominal awake duration (T) indicated in the nominal minimum TWT awake duration field in the broadcast TWT parameter set field. In some embodiments, STA 1 may not be able to stay awake at the nominal SP start time. t1 Initiates the frame exchange sequence with AP 1, and the actual SP start time may be much later. Figure 6 In the example, the actual SP start time is indicated as t2 Therefore, due to the actual SP startup time delay, the minimum wakeup duration of STA 1 may be adjusted, which is expressed as "AdjustedMinimumTWTWakeDuration = T - (t2 - t1)".

[0089] In a separate TWT protocol between multi-link devices (MLDs) that support multi-link operation, a STA attached to the MLD (i.e., a TWT requesting STA) may indicate the link requested for establishing the TWT protocol in the link ID bitmap subfield of the TWT element in the TWT request frame. When only one link is indicated in the link ID bitmap subfield, a single TWT protocol is requested for the STA attached to the MLD, which operates on the indicated link. The target wakeup time field of the TWT element may refer to the TSF (Timing Synchronization Function) time of the link indicated in the TWT element. Subsequently, the TWT responding STA attached to the peer MLD that received the TWT request may respond with a TWT response that indicates the link in the link ID bitmap subfield of the TWT element. The link in the TWT element of the TWT response may be the same link as the link indicated in the TWT element of the TWT request.

[0090] Figure 7 An example of separate TWT negotiation between an AP MLD and a non-AP MLD according to an embodiment is shown. Figure 7 The operations depicted in FIG. 5 are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation.

[0091] exist Figure 7In the example, AP 1, AP 2, and AP 3 are affiliated with AP MLD 710. Non-AP STA 1, non-AP STA 2, and non-AP STA 3 are affiliated with non-AP MLD 720. In some embodiments, AP 1 and non-AP STA 1 operate on the 2.4 GHz band, AP 2 and non-AP STA 2 operate on the 5 GHz band, and AP 3 and non-AP STA 3 operate on the 6 GHz band. Non-AP STA 1, affiliated with non-AP MLD 720, can send three TWT elements in a TWT request to AP 1, affiliated with AP MLD 710, for three TWT protocols. The three TWT elements indicate the links of AP 1, AP 2, and AP 3, respectively, and request that the three TWT protocols be set up on the three links. The three TWT protocols can have different TWT parameters, such as the target wake-up time and the value of the desired TWT in the TWT setup command field. Subsequently, AP 1 sends the three TWT elements to non-AP STA 1 in a TWT response. The three TWT elements indicate the links of AP 1, AP 2, and AP 3 respectively, and have different TWT parameters (such as the value of accepting TWT) in the TWT setting command field. After the TWT protocol is successfully set on the three links, there are three TWT SPs with different TWT parameters on the three links.

[0092] Restricted TWT (R-TWT) operation is another important feature of the next generation WLAN. R-TWT operation provides better support for delay-sensitive applications. For example, services in real-time applications have strict requirements on delay and its jitter as well as certain reliability constraints. In the present disclosure, such services may be referred to as delay-sensitive services. R-TWT operation can provide protected service periods (SPs) for R-TWT member STAs by sending quiet elements to non-member STAs in the BSS in the R-TWT scheduling. In some embodiments, the quiet interval of the quiet element overlaps with the initial part of the R-TWT SP. Therefore, it can provide R-TWT member STAs with greater channel access opportunities compared to non-member STAs, thereby improving delay-sensitive service flows.

[0093] Interference from one BSS often causes performance issues for STAs and APs in neighboring BSSs. This interference can lead to a decrease in overall network throughput. Overlapping BSS (OBSS) interference can also increase overall latency because the interference occupies the channel, requiring more time to access the channel. If STAs in the BSS have latency-sensitive services, this delay in channel access can severely hinder the performance of the STA's latency-sensitive applications.

[0094] When a STA in a BSS is an R-TWT scheduled STA and the STA has delay-sensitive traffic, the R-TWT scheduled STA may not be able to access the channel during the R-TWT SP due to interference, even if any ongoing TXOPs of other STAs in its BSS end before the R-TWT SP starts. This may interfere with the transmission of the STA's delay-sensitive traffic.

[0095] Figures 8A to 8C An example of interference from a neighboring BSS according to an embodiment is shown. Figure 8B and Figure 8C The examples depicted in Figure 8A The scene shown in .

[0096] Figure 8A An example scenario of OBSS interference according to an embodiment is shown. Figure 8A In , AP 1 establishes BSS 1 and AP 2 establishes BSS 2. BSS 1 and BSS 2 overlap, making them overlapping BSSs (OBSSs). STA 1 and STA 2 are associated with AP 1, while STA 3 is associated with AP 2. Figure 8A In the example shown in FIG1 , AP 1 is the R-TWT scheduling AP, and STA 2 is the R-TWT scheduled STA. STA 2 is located in the overlapping region 810 between BSS 1 and BSS 2. Therefore, as shown in the figure, when STA 2 attempts to access the channel during the R-TWT SP, STA 2 may experience OBSS interference from BSS 2.

[0097] Figure 8B An example timing diagram of OBSS interference according to an embodiment is shown. Figure 8B , the R-TWTSP for STA 2 is scheduled to t2 Start at time t3 At the same time, AP 2 can t1 Start transmitting to STA 3 associated with AP 2 and continue frame exchange (e.g., DL PPDU and Block Ack frames) until time t4 Therefore, when STA 2 is at time t2 Upon waking up, STA 2 observes the channel as busy due to the transmission from AP 2 to STA 3, and the channel remains busy throughout the scheduled R-TWT SP. As a result, the delay-sensitive traffic of the R-TWT scheduled STA (STA 2) may not be delivered as planned, disrupting STA 2's delay-sensitive applications. Figure 8B The problem depicted in Figure 2 may occur because AP 2 and STA 3 do not comply with the R-TWT rules of BSS 1.

[0098] Figure 8C Another example timing diagram of OBSS interference according to an embodiment is shown. Figure 8C , because both STA 1 and STA 2 are members of BSS 1, and STA 2 is the STA for which R-TWT is scheduled, STA 1 ends its TXOP before the start of R-TWT for STA 2. However, AP 2 does not end transmission before the start time of R-TWT for STA 2 because AP 2 is a member of a different BSS (BSS 2).

[0099] Therefore, multi-AP coordination based on TWT can be an important feature for the next generation of WLAN to solve the interference problem from OBSS. The present disclosure provides the concept and mechanism of multi-AP coordination based on TWT. In addition, the present disclosure provides how R-TWT operation can be extended or applied to multi-AP coordination, as well as the operating rules of R-TWT for multi-AP coordination.

[0100] Coordination between neighboring APs by sharing STA wake-up pattern information may facilitate interference management. In an embodiment, the coordinating APs may share TWT information of STAs in their BSS, which may be referred to as "coordinated TWT (C-TWT)" in this disclosure. This coordination may help mitigate OBSS interference or enhance signal power during TWT SP.

[0101] In some embodiments, an R-TWT shared AP may refer to an AP that has R-TWT scheduling in its BSS and initiates a TWT coordination request to another AP. In the present disclosure, for convenience, an "R-TWT shared AP" may be referred to as a "TWT shared AP". An AP is designated as an R-TWT shared AP if it has established R-TWT scheduling in its BSS and requests help from a neighboring AP to protect channel access during its R-TWT SP. In some embodiments, an R-TWT shared AP may send a coordination request to a STA or STA group in a neighboring BSS instead of sending a TWT coordination request to a neighboring AP.

[0102] In some embodiments, an R-TWT shared AP may refer to an AP that receives a TWT coordination request from another AP. In this disclosure, for convenience, an "R-TWT shared AP" may be referred to as a "TWT shared AP."

[0103] In some embodiments, an R-TWT coordination AP set may refer to a group of APs that coordinate to ensure channel access protection during an R-TWT SP corresponding to an R-TWT schedule in the BSS of any or all APs.

[0104] Figure 9An example of multi-AP coordination according to an embodiment is shown. Figure 9 The scenarios and operations depicted in the present disclosure are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation.

[0105] exist Figure 9 In this example, AP 1 establishes BSS 1, AP 2 establishes BSS 2, and AP 3 establishes BSS 3. STA 1 and STA 2 are associated with AP 1 in BSS 1, STA 3 is associated with AP 2 in BSS 2, and STA 4 is associated with AP 3 in BSS 3. In this example, AP 1 is the R-TWT scheduling AP in BSS 1, and STA 2 is the R-TWT scheduled STA in BSS 1. In this case, the APs and STAs in each BSS may cause interference to the APs and STAs in neighboring BSSs. For example, the APs and STAs in BSS 2 and BSS 3 may cause interference to STA 2. Therefore, AP 1, AP 2, and AP 3 may agree to cooperate to protect the R-TWT scheduling in their BSSs. Therefore, AP 1, AP 2, and AP 3 may jointly form an R-TWT coordination AP set. In an embodiment, AP 1 may request help from AP 2 and AP 3 to protect the R-TWT scheduling in BSS 1. In this scenario, AP 1 acts as an R-TWT shared AP, while AP 2 and AP 3 serve as R-TWT shared APs within the R-TWT coordination AP set.

[0106] In an embodiment, there may be different levels or modes of multi-AP R-TWT coordination. Some operating modes are provided below as examples.

[0107] In an embodiment, a first AP that is an R-TWT shared AP operating in a first BSS has a first R-TWT schedule established in the first BSS and is also a member of the R-TWT coordinated AP set. In addition, a second AP operating in a second BSS is also a member of the R-TWT coordinated AP set. In this scenario, i) the second AP and any non-AP STA associated with the second AP and operating in the second BSS should ensure that the TXOP ends before the start time of the R-TWT SP corresponding to the first R-TWT schedule in the first BSS, ii) the second AP and any non-STA associated with the second AP and operating in the second BSS do not send frames during the R-TWT SP corresponding to the first R-TWT schedule in the first BSS. This R-TWT multi-AP coordination mode may be referred to as "Mode 1 R-TWT multi-AP coordination".

[0108] Figure 10 An example of Mode 1 R-TWT multi-AP coordination according to an embodiment is shown. Figure 10 The operations depicted in FIG. 5 are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation.

[0109] Figure 10 The example shown is based on Figure 8A Scenario shown. Therefore, AP 1 establishes BSS 1, and AP 2 establishes BSS 2. BSS 1 and BSS 2 overlap such that they are each other's overlapping BSSs (OBSS). STA 1 and STA 2 are associated with AP 1 while STA 3 is associated with AP 2. AP 1 is the R-TWT scheduling AP in BSS 1, and STA 2 is the R-TWT scheduled STA in BSS 1. STA 2 is located within the overlapping region 810 of BSS 1 and BSS 2. In this example, AP 1 and AP 2 are members of the R-TWT coordinating AP set, while AP 1 is the R-TWT sharing AP and AP 2 is the R-TWT shared AP. Figure 10 , in BSS 1, the R-TWTSP for STA 2 is scheduled to start at time t2 Start and in time t3 End. Start time of R-TWT SP of BSS 1 of which STA 2 is a member t2 Previously, the TXOP established between AP 2 and STA 3 in BSS 2 ended. During the R-TWT SP in BSS 1, STA 3 and AP 2 in BSS 2 refrained from transmitting frames. After the R-TWT SP in BSS 1 ends, STA 3 can start contending for uplink PPDU transmission.

[0110] In an embodiment, a first AP that is an R-TWT shared AP operating in a first BSS has a first R-TWT schedule established in the first BSS and is also a member of the R-TWT coordinated AP set. In addition, a second AP operating in a second BSS is also a member of the R-TWT coordinated AP set. In this scenario, i) the second AP and any non-AP STA associated with the second AP and operating in the second BSS should ensure that the TXOP ends before the start time of the R-TWT SP corresponding to the first R-TWT schedule in the first BSS, ii) the second AP and any non-STA associated with the second AP and operating in the second BSS can send frames during the R-TWT SP corresponding to the first R-TWT schedule in the first BSS. This R-TWT multi-AP coordination mode may be referred to as "Mode 2 R-TWT multi-AP coordination".

[0111] Figure 11 An example of Mode 2 R-TWT multi-AP coordination according to an embodiment is shown.

[0112] Figure 11 The examples depicted in are also based on Figure 8A . Thus, AP 1 establishes BSS 1, and AP 2 establishes BSS 2. BSS 1 and BSS 2 overlap such that they are each other's overlapping BSSs (OBSS). STA 1 and STA 2 are associated with AP 1, while STA 3 is associated with AP 2. AP 1 is the R-TWT scheduling AP in BSS 1, and STA 2 is the R-TWT scheduled STA in BSS 1. STA 2 is located within the overlapping region 810 of BSS 1 and BSS 2. In this example, AP 1 and AP 2 are members of the R-TWT coordinating AP set, while AP 1 is the R-TWT sharing AP and AP 2 is the R-TWT shared AP. Figure 11 , in BSS 1, the R-TWT SP for STA 2 is scheduled to be at time t2 Start at time t3 The start time of the R-TWT SP in BSS 1 of which STA 2 is a member, for the TXOP established between AP 2 and STA 3 in BSS 2. t2 However, AP 2 and STA 3 can send frames during the R-TWT SP established in BSS 1. In an embodiment, at the time indicated by the target wake-up time of the R-TWT SP t4 , AP 2 or any associated STA in BSS 2 may start contending for channel access and send frames after winning the contention. In some embodiments, at the time indicated by the target wake-up time of the R-TWT SP t4 , the contention of any STA in BSS 1 and BSS 2 can start at the same time. Therefore, the contention start time of any STA in BSS 1 and BSS 2 can be aligned.

[0113] In an embodiment, a first AP that is an R-TWT shared AP operating in a first BSS has a first R-TWT schedule established in the first BSS and is a member of the R-TWT coordinated AP set. In addition, a second AP operating in a second BSS is also a member of the R-TWT coordinated AP set. In this scenario, i) if a TXOP has not yet been obtained for low-latency services, the second AP and any non-AP STA associated with the second AP and operating in the second BSS should ensure that the TXOP ends before the start time of the R-TWT SP corresponding to the first R-TWT schedule in the first BSS, in which case there is no need to end the TXOP, ii) the second AP and any non-STA associated with the second AP and operating in the second BSS can send frames during the R-TWT SP corresponding to the first R-TWT schedule in the first BSS. This mode of R-TWT multi-AP coordination can be referred to as "Mode 3 R-TWT multi-AP coordination".

[0114] In an embodiment, a first AP that is an R-TWT shared AP operating in a first BSS has a first R-TWT schedule established in the first BSS and is a member of the R-TWT coordinated AP set. In addition, a second AP operating in a second BSS is also a member of the R-TWT coordinated AP set. In this scenario, i) the second AP operating in the second BSS should ensure that the TXOP ends before the start time of the R-TWT SP corresponding to the first R-TWT schedule in the first BSS, and ii) any STA associated with the second AP and operating in the second BSS may not end its TXOP before the start time of the R-TWTSP corresponding to the first R-TWT schedule in the first BSS. This mode of R-TWT multi-AP coordination may be referred to as "Mode 4 R-TWT multi-AP coordination".

[0115] In an embodiment, a first AP that is an R-TWT shared AP operating in a first BSS has a first R-TWT schedule established in the first BSS and is a member of the R-TWT coordinated AP set. In addition, a second AP operating in a second BSS is also a member of the R-TWT coordinated AP set. In this scenario, i) the second AP operating in the second BSS should ensure that the TXOP ends before the start time of the R-TWT SP corresponding to the first R-TWT schedule in the first BSS, and ii) the second AP or any STA associated with the second AP and operating in the second BSS can start contending for channel access after being triggered by the first AP. If the second AP or any STA associated with the second AP receives a trigger frame, the second AP or any STA associated with the second AP can send a frame during the R-TWT SP established in BSS 1. This mode of R-TWT multi-AP coordination can be referred to as "Mode 5 R-TWT multi-AP coordination".

[0116] Figure 12 Example operations of Mode 5 R-TWT multi-AP coordination according to an embodiment are shown. Figure 12 The operations depicted in FIG. 5 are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation.

[0117] Figure 12 The examples depicted in are also based on Figure 8A Scenario shown in . Therefore, AP 1 establishes BSS 1 and AP 2 establishes BSS 2. BSS 1 and BSS 2 overlap such that they are each other's overlapping BSS (OBSS). STA 1 and STA 2 are associated with AP 1, while STA 3 is associated with AP 2. AP 1 is the R-TWT scheduling AP in BSS 1, and STA 2 is the R-TWT scheduled STA in BSS 1. STA 2 is located within the overlapping region 810 of BSS 1 and BSS 2. In this example, AP 1 and AP 2 are members of the R-TWT coordinating AP set, while AP 1 is the R-TWT sharing AP and AP 2 is the R-TWT shared AP. Figure 12 , before the start time of the R-TWT SP established between AP 1 and STA 2, AP 1 and AP 2 have successfully conducted C-TWT negotiation. AP 2 can start the R-TWT SP in BSS 1 at the start time t2 The TXOP established between AP 2 and STA 3 is previously ended (not shown). However, when AP 2 receives a C-TWT trigger from AP 1, AP 2 responds by sending a CTS (clear to send) frame to AP 1 and starts contending for channel access to send a DL PPDU to STA 3.

[0118] In an embodiment, a first AP that is an R-TWT shared AP operating in a first BSS has a first R-TWT schedule established in the first BSS and is a member of the R-TWT coordinated AP set. In addition, a second AP operating in a second BSS is also a member of the R-TWT coordinated AP set. In this scenario, when advertising an R-TWT schedule in the second BSS, the second AP can indicate that the advertised R-TWT schedule is an OBSS R-TWT schedule. This indication can be achieved by setting the OBSS R-TWT subfield in the TWT element.

[0119] Figure 13 An example format of a TWT element according to an embodiment is shown.

[0120] exist Figure 13 In the TWT element 1300, the TWT element 1300 may include an element identifier (ID) field, a length field, a control field, and a TWT parameter information field. The element ID field may include information for identifying the TWT element 1300. The length field may indicate the length of the TWT element 1300.

[0121] The control field may include a Null Data PPDU (Physical Layer Protocol Data Unit) (NDP) Paging Indicator subfield, a Responder Power Management (PM) Mode subfield, a Negotiation Type subfield, a TWT Information Frame Disable subfield, a Wake-Up Duration Units subfield, a Link ID Bitmap Present subfield, and an OBSS R-TWT subfield. The NDP Paging Indicator subfield may indicate whether the NDP Paging field is present in the Individual TWT Parameter Set field. The Responder PM Mode subfield may indicate a power management mode, such as active mode or power save (PS) mode. The Negotiation Type subfield may indicate whether the information included in the TWT element is a parameter for negotiating a broadcast or individual TWT or wake-up TBTT (Target Beacon Transmission Time) interval. The MSB (Most Significant Bit) of the Negotiation Type subfield is the Broadcast field, which indicates whether one or more broadcast TWT parameter sets are included in the TWT element. The TWT Information Frame Disable subfield may indicate whether the STA disables reception of TWT information frames. The Wake-Up Duration Units subfield may indicate the units of the Nominal Minimum TWT Wake-Up Duration subfield in the Broadcast TWT Parameter Set field 1310. The Link ID Bitmap Presence subfield may indicate the presence of the Link ID Bitmap field in the separate TWT parameter set field. The OBSS R-TWT subfield may indicate whether the R-TWT scheduling corresponding to the Broadcast TWT Parameter Set field in the TWT element is the R-TWT scheduling of the neighboring BSS. When the OBSS R-TWT subfield is set to "1", it may indicate that the R-TWT scheduling in the TWT element is the R-TWT scheduling of the neighboring BSS. Otherwise, it indicates that there is no R-TWT scheduling of the neighboring BSS in the TWT element.

[0122] The TWT Parameter Information field may include one or more Broadcast TWT Parameter Set fields 1310. The Broadcast TWT Parameter Set field 1310 may include a Request Type field, a Target Wake-up Time field, a Nominal Minimum TWT Wake-up Duration field, a TWT Wake-up Interval Mantissa field, a Broadcast TWT Information field, and an optional Restricted TWT Service Information field. The Request Type field includes information about the TWT element. The Target Wake-up Time field may include an unsigned integer corresponding to the TSF (Time Synchronization Function) time for TWT-scheduled STAs to wake up. The Target Wake-up Time field may indicate the start time of a TWT Service Period (SP) on the corresponding link. The Nominal Minimum TWT Wake-up Duration field may indicate the minimum amount of time a TWT-scheduled STA is expected to wake up to complete a frame exchange within the TWT Wake-up Interval. The TWT Wake-up Interval is the average time that a TWT-scheduled STA is expected to elapse between consecutive TWT SPs. The TWT Wake-up Interval Mantissa field may indicate the mantissa value of the TWT Wake-up Interval value. The Broadcast TWT Information field may include information related to the Broadcast TWT, such as the Broadcast TWT ID and the Broadcast TWT persistence.

[0123] In some embodiments, when the OBSS R-TWT subfield in the TWT element is set to "1", there may be another indication in the field or subfield of the TWT element that may indicate the mode of R-TWT multi-AP coordination requested by the neighboring BSS. In some embodiments, a three-bit subfield may be used for this indication, which may be referred to as an "R-TWT coordination mode subfield". The following table shows an example encoding of the R-TWT coordination mode subfield.

[0124] [Table 1]

[0125] Figure 14 8 and 9 show a flowchart of an example operation of multi-AP coordination according to an embodiment. For the purpose of explanation and illustration, the example process 1400 may be represented by FIG. Figure 11 Although one or more operations are described or shown in a particular order, in other embodiments, the operations may be rearranged in a different order, which may include performing multiple operations during at least partially overlapping time periods.

[0126] Process 1400 may begin in operation 1401. In operation 1401, a STA associates with an AP and operates in a BSS established by the AP.

[0127] In operation 1403 , the STA receives a TWT element from the AP in a beacon frame or a probe response frame.

[0128] In operation 1405, the STA receives an indication from the AP that the TWT element corresponds to the R-TWT schedule of the neighboring BSS. In some embodiments, the indication may be included in the OBSS R-TWT subfield in the TWT element.

[0129] In operation 1407 , the STA also receives an indication that the neighboring BSS has requested Mode 2 R-TWT multi-AP coordination.

[0130] In operation 1409 , the STA ends any TXOP before the start time of the R-TWT SP corresponding to the R-TWT schedule of the neighboring BSS.

[0131] In operation 1411 , the STA starts contention for channel access at a time indicated by a target wake-up time corresponding to an R-TWT schedule in a neighboring BSS.

[0132] In an embodiment, a first AP may coordinate with a nearby second AP to coordinate with the AP's individual TWT protocols, broadcast TWT scheduling, or R-TWT scheduling. The coordination mechanism may take different formats based on the architecture of the C-TWT negotiation.

[0133] Figure 15 An example architecture for coordinated TWT negotiation according to an embodiment is shown.

[0134] exist Figure 15 In , AP 1, AP 2, AP 3 and AP 4 establish BSS 1, BSS 2, BSS 3 and BSS 4 respectively. In addition, AP 1, AP 2, AP 3 and AP 4 are members of the R-TWT coordinated AP set and participate in TWT multi-AP coordination. Figure 15 In the present disclosure, the AP can be an R-TWT scheduling AP in its BSS. The APs participating in TWT multi-AP coordination can exchange frames directly between APs to negotiate TWT multi-AP coordination. In this disclosure, this may be referred to as "Type 1 architecture for coordinated TWT (C-TWT) negotiation."

[0135] In an embodiment of a type 1 architecture for C-TWT negotiation, a first AP that intends to participate in TWT multi-AP coordination may send a C-TWT request frame to a second AP in its vicinity in order to request TWT multi-AP coordination. Negotiation for TWT multi-AP coordination may be initiated by sending a C-TWT request frame, which may include one or more TWT elements indicating the desired TWT schedule. For example, for multi-AP coordination based on R-TWT, the first AP may include a TWT element in a C-TWT request frame, which includes one or more broadcast TWT parameter set fields corresponding to the R-TWT schedule. An example format of a C-TWT request frame is shown in Table 2 below.

[0136] [Table 2]

[0137] In an embodiment, the second AP may send a C-TWT response frame to the first AP in response to the C-TWT request frame. If the second AP indicates acceptance of the C-TWT request in the C-TWT response frame, the first AP and the second AP become members of the R-TWT multi-AP coordination set. An example format of the C-TWT response frame is shown in Table 3 below.

[0138] [Table 3]

[0139] Figure 16 An example of a Type 1 architecture for C-TWT negotiation according to an embodiment is shown. Figure 16 The operations depicted in FIG. 5 are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation.

[0140] exist Figure 16In the figure, AP 1 is the R-TWT scheduling AP and sends a C-TWT request frame to AP 2, AP2 and AP 4, indicating Mode 1 R-TWT multi-AP coordination. In response to the C-TWT request frame, AP 2 rejects the R-TWT coordination request by sending a reject C-TWT frame to AP 1. AP 3 may not support Mode 1 R-TWT multi-AP coordination. Therefore, AP 3 sends a substitute C-TWT frame, indicating the ability to support Mode 2 R-TWT multi-AP coordination and Mode 3 R-TWT multi-AP coordination. At the same time, AP 4 accepts the C-TWT request from AP 1 by sending an accept C-TWT frame indicating its ability to support Mode 1 R-TWT multi-AP coordination and Mode 2 R-TWT multi-AP coordination. Subsequently, AP 1 sends another C-TWT request frame to AP 3 and AP 4, indicating Mode 2 R-TWT multi-AP coordination, so that both AP3 and AP4 participate in R-TWT multi-AP coordination. In response to the second C-TWT request, AP 3 and AP 4 respectively send an accept C-TWT frame to AP 1. As a result, AP 1, AP 3, and AP 4 become members of the R-TWT multi-AP coordination set.

[0141] In an embodiment, in a Type 1 architecture for C-TWT negotiation, an advertisement phase may precede active negotiation between APs.

[0142] Figure 17 Another example of a Type 1 architecture for C-TWT negotiation according to an embodiment is shown. Figure 17 The operations depicted in FIG. 5 are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation.

[0143] exist Figure 17 In the figure, AP 1 intends to initiate R-TWT multi-AP coordination with other APs (e.g., AP 2, AP 3, and AP 4). AP1 sends a C-TWT announcement frame to identify neighboring APs that are willing to participate in R-TWT multi-AP coordination. The C-TWT announcement frame can be a broadcast frame or a multicast frame. In response to the C-TWT announcement frame, AP 2 and AP 4 send a C-TWT preparation frame to AP 1, indicating their ability to participate in R-TWT multi-AP coordination. In the C-TWT preparation frame, AP 2 and AP 4 can also indicate the modes of R-TWT multi-AP coordination that they support in their BSS. Subsequently, as Figure 16 As shown, active negotiation occurs between APs by exchanging C-TWT request frames and C-TWT response frames. Figure 17 In the example, the C-TWT request frame can serve as a trigger frame, which triggers the C-TWT response frame from the receiving AP. Figure 17As shown, the coordinated TWT announcement phase between APs can be performed before the C-TWT negotiation phase.

[0144] Figure 18 A flowchart illustrating example operations for TWT multi-AP coordination according to an embodiment is shown. For purposes of explanation and illustration, the example process 1800 may be performed based on a Type 1 architecture for C-TWT negotiation. Although one or more operations are described or shown in a particular order, in other embodiments, the operations may be rearranged in a different order, which may include performing multiple operations in at least partially overlapping time periods.

[0145] The process 1800 may begin in operation 1801. In operation 1801, a first AP intends to perform TWT multi-AP coordination with neighboring APs. The first AP may be an R-TWT scheduling AP in its BSS.

[0146] In operation 1803, the first AP sends a C-TWT announcement frame to neighboring APs to identify APs willing to participate in TWT multi-AP coordination. The C-TWT announcement frame can be a broadcast frame, a multicast frame, or a unicast frame.

[0147] In operation 1803, the first AP determines whether it has received a C-TWT preparation frame from at least one neighboring AP. When the first AP has received the C-TWT preparation frame, the process 1800 proceeds to operation 1807. Otherwise, the process 1800 proceeds to operation 1809.

[0148] In operation 1807, the first AP transmits a C-TWT request frame to the second AP. The C-TWT prepare frame may serve as a trigger frame for requesting a C-TWT response frame from the second AP.

[0149] In operation 1809 , the first AP does not perform TWT multi-AP coordination.

[0150] In operation 1811, the first AP determines whether it has received a C-TWT response frame from the second AP. When the first AP receives the C-TWT response frame, the process 1800 proceeds to operation 1813. Otherwise, the process 1800 proceeds to operation 1815. The C-TWT response frame may be an accept C-TWT frame.

[0151] In operation 1813 , the first AP and the second AP successfully negotiate TWT multi-AP coordination, and the first AP and the second AP become members of the R-TWT multi-AP coordination set.

[0152] In operation 1815, the negotiation for TWT multi-AP coordination is unsuccessful.

[0153] The example format of the C-TWT announcement frame is shown in Table 4 below.

[0154] [Table 4]

[0155] An example format of the C-TWT preparation frame is shown in Table 5 below.

[0156] [Table 5]

[0157] In an embodiment, the negotiation between APs based on multi-AP coordination of R-TWT can be controlled by a controller (e.g., an R-TWT central controller). In this disclosure, this may be referred to as a "Type 2 architecture for C-TWT negotiation."

[0158] Figure 19 An example of a Type 2 architecture for C-TWT negotiation according to an embodiment is shown. Figure 19 The operations depicted in FIG. 5 are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation.

[0159] exist Figure 19 In the example, AP 1, AP 2, and AP 3 establish BSS 1, BSS 2, and BSS 3, respectively. All three APs are connected to the R-TWT central controller 1910. The R-TWT central controller 1910 coordinates AP 1, AP 2, and AP 3 for C-TWT negotiation, and AP 1, AP 1, and AP 3 serve as R-TWT coordinated APs.

[0160] Reference Figure 19, AP 1 may intend to initiate TWT multi-AP coordination with neighboring APs (e.g., AP 2 and AP 3). First, AP 1 may send an R-TWT coordination request frame to the R-TWT central controller 1910. The R-TWT central controller 1910 may have information about the R-TWT schedule of all APs (AP 1, AP 2, and AP 3) connected to the R-TWT central controller 1910. After receiving the R-TWT coordination request frame from AP 1, the R-TWT central controller 1910 may send a response frame to AP 1 based on the overall network situation. In addition, if the R-TWT central controller 1910 accepts the coordination request from AP 1, the R-TWT central controller 1910 may send R-TWT coordination information frames to other APs (e.g., AP 2 and AP 3) that the R-TWT central controller 1910 considers suitable for multi-AP coordination. The R-TWT coordination information frame serves as a trigger frame to request the APs to participate in the R-TWT coordination initiated by AP 1. In response, the APs (eg, AP 2 and AP 3) that receive the R-TWT coordination information frame may send an R-TWT coordination confirmation frame to the R-TWT central controller 1910 as confirmation of receipt of the R-TWT coordination information frame. Figure 19 The embodiment depicted in and other embodiments of the present disclosure are described based on R-TWT, but the coordination negotiation mechanism can also be applied to individual TWTs or broadcast TWTs. The format of the R-TWT coordination request frame and the R-TWT coordination response frame can be the same as the format of the C-TWT request frame and the C-TWT notification frame described previously. An example format of the R-TWT coordination information frame is shown in Table 6.

[0161] [Table 6]

[0162] Figure 20 An example timing diagram of a Type 2 architecture for C-TWT negotiation is shown according to an embodiment. Figure 20 The operations depicted in FIG. 5 are for illustrative purposes and do not limit the scope of the present disclosure to any particular implementation. Figure 20 The example depicted in Figure 19 The topology depicted in .

[0163] exist Figure 20 For convenience, Figure 19The R-TWT central controller 1910 may be referred to as AP 0. As shown, AP 1 may send an R-TWT coordination request frame to AP 0. AP 1 may be the R-TWT scheduling AP in its BSS. In response, AP 0 may accept the request by sending an R-TWT coordination response frame to AP 1. Subsequently, AP 0 may send an R-TWT coordination information frame to AP 2 and AP 3. The R-TWT coordination information frame may be a multicast frame, a broadcast frame, or a unicast frame. In response to receiving the R-TWT coordination information frame, AP 2 and AP 3 may respectively send an R-TWT coordination confirmation frame.

[0164] Figure 21 21. A flowchart illustrating an example operation of TWT multi-AP coordination according to an embodiment is shown. For purposes of explanation and illustration, the example process 2100 may be performed by Figure 19 Although one or more operations are described or shown in a particular order, in other embodiments, the operations may be rearranged in a different order, which may include performing multiple operations in at least partially overlapping time periods.

[0165] In operation 2101, process 2100 may begin. In operation 2101, the R-TWT central controller receives an R-TWT coordination request frame from a first AP. The R-TWT central controller, acting as an R-TWT coordinating AP, controls the first AP. The first AP may be an R-TWT scheduling AP in its BSS and may intend to perform R-TWT-based multi-AP coordination with neighboring APs including a second AP. The R-TWT coordination request frame may include one or more R-TWT elements requesting multi-AP coordination. Process 2100 may then proceed to operation 2103.

[0166] In operation 2103, the R-TWT central controller determines whether it accepts the R-TWT coordination request. When the R-TWT central controller accepts the R-TWT coordination request, it sends an R-TWT coordination response frame to the first AP, and then the process 2100 proceeds to operation 2105. Otherwise, the process 2100 proceeds to operation 2107, where the first AP may not be able to perform the requested multi-AP coordination.

[0167] In operation 2105, the R-TWT central controller transmits an R-TWT coordination information frame to one or more second APs. The R-TWT coordination information frame serves as a trigger frame including one or more TWT elements to request a response frame from the one or more second APs.

[0168] In operation 2109, the R-TWT central controller determines whether it receives an R-TWT coordination confirmation frame from one or more second APs in response to the R-TWT coordination information frame. If the R-TWT central controller receives the confirmation frame from at least one second AP, the process 2100 proceeds to operation 2111. When the R-TWT central controller does not receive the confirmation frame from any second AP, the process 1200 proceeds to operation 2113, where the negotiation between the first AP and the one or more second APs becomes unsuccessful.

[0169] In operation 2111, the negotiation of multi-AP coordination based on R-TWT succeeds. Therefore, the first AP and at least the second AP become members of the multi-AP coordination set controlled by the R-TWT central controller.

[0170] In an embodiment, all APs in the R-TWT coordination AP set may be R-TWT scheduling APs in their respective BSSs. In another embodiment, one or more APs in the R-TWT coordination AP set may not be R-TWT scheduling APs in their respective BSSs. In some embodiments, at least one AP in the R-TWT coordination SP set is an R-TWT scheduling AP in its BSS.

[0171] In an embodiment, whether one or more APs in the R-TWT coordination AP set is an R-TWT scheduling AP depends on the observation timeline. For example, during the R-TWT multi-AP negotiation, one or more APs are used as R-TWT scheduling APs. However, after the R-TWT multi-AP coordination negotiation, no AP can be used as an R-TWT scheduling AP. For example, after the R-TWT multi-AP coordination negotiation, the AP can terminate all R-TWT scheduling in its respective BSS.

[0172] In an embodiment, the R-TWT coordination AP set may be disassembled if all APs in the R-TWT coordination AP set remove all R-TWT schedules in their respective BSSs. In another embodiment, each AP may send an indication to the other APs in the R-TWT coordination AP set when the AP removes its R-TWT schedule. In some embodiments, when all APs in the R-TWT coordination AP set remove all R-TWT schedules in their respective BSSs, the APs remain as members of the R-TWT coordination set.

[0173] In an embodiment, when an R-TWT scheduling AP in an R-TWT coordination AP set removes R-TWT scheduling, the AP may no longer be a member of the R-TWT coordination AP set. In another embodiment, even when an R-TWT scheduling AP in an R-TWT coordination AP set removes R-TWT scheduling, the AP remains a member of the R-TWT coordination AP set.

[0174] In an embodiment, two or more APs that are not R-TWT scheduling APs may form an R-TWT coordinating AP set.

[0175] According to various embodiments in the present disclosure, R-TWT-based multi-AP coordination can be utilized to maintain seamless delay-sensitive traffic flow.

[0176] Although some embodiments in the present disclosure are described in terms of R-TWT for ease of explanation, all embodiments are also applicable to general TWT, including broadcast TWT or standalone TWT.

[0177] Unless otherwise specified, reference to an element in the singular does not mean one or only one, but rather one or more. For example, "a" module may refer to one or more modules. Reference to an element beginning with "a," "an," "the," or "the" does not, without further limitation, exclude the presence of other identical elements.

[0178] Headings and subheadings, if any, are used for convenience only and do not limit the invention. The term "exemplary" is used to mean serving as an example or illustration. When the terms "including," "having," or similar terms are used, they are to be interpreted in a manner similar to the word "comprising" when used as a transitional term in the claims. Relational terms such as "first" and "second" may be used to distinguish one entity or action from another without requiring or implying an actual relationship or order between such entities or actions.

[0179] Phrases such as an aspect, this aspect, another aspect, some aspects, one or more aspects, an embodiment, this embodiment, another embodiment, some embodiments, one or more embodiments, an example, this example, another example, some examples, one or more examples, a configuration, this configuration, another configuration, some configurations, one or more configurations, subject technology, this disclosure, the present disclosure, other variations thereof are for convenience and do not mean that the disclosure associated with these phrases is essential to the subject technology, nor do they mean that this disclosure is applicable to all configurations of the subject technology. The disclosure associated with these phrases can be applicable to all configurations, or one or more configurations. The disclosure associated with these phrases can provide one or more examples. Phrases such as an aspect or some aspects can refer to one or more aspects, and vice versa, and this rule applies equally to the aforementioned other terms.

[0180] The phrase "at least one of" preceding a list of items, with the use of "and" or "or" to separate any of the items, acts to modify the entire list, not each individual member of the list. The phrase "at least one of" does not require the selection of at least one item; rather, the phrase allows for the meaning of at least one of any one of the items, and / or at least one of any combination of the items, and / or at least one of each of the items. For example, each of the phrases "at least one of A, B, and C" or "at least one of A, B, or C" means: only A, only B, or only C; any combination of A, B, and C; and / or at least one of each of A, B, and C.

[0181] It should be understood that the specific order or hierarchy of steps, operations, or processes disclosed is illustrative of exemplary methods. Unless expressly stated otherwise, it is understood that the specific order or hierarchy of steps, operations, or processes may be performed in a different order. Some steps, operations, or processes may be performed simultaneously or as part of one or more other steps, operations, or processes. The accompanying method claims (if any) present elements of various steps, operations, or processes in an example order and are not meant to be limited to the specific order or hierarchy presented. These steps, operations, or processes may be performed serially, linearly, in parallel, or in a different order. It should be understood that the described instructions, operations, and systems may generally be integrated into a single software / hardware product or packaged into multiple software / hardware products.

[0182] This disclosure is provided to enable any person skilled in the art to practice the various aspects described herein. In some cases, well-known structures and components are shown in block diagram form to avoid obscuring the concepts of the subject technology. This disclosure provides various examples of the subject technology, and the subject technology is not limited to these examples. Various modifications to these aspects will be clear to those skilled in the art, and the principles described herein can be applied to other aspects.

[0183] All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. In addition, nothing disclosed herein is intended to be disclosed to the public regardless of whether the claims explicitly reference the disclosure. No claim element should be excluded under 35 U.S.C. 112, paragraph 6, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for”.

[0184] The title, background, brief description of the drawings, abstract, and drawings are all incorporated into this disclosure and are provided as illustrative examples of the disclosure and not as limiting descriptions. This disclosure is filed with the express understanding that they will not be used to limit the scope or meaning of the claims. Furthermore, in the detailed description, it can be seen that the description provides illustrative examples and that various features are grouped together in various embodiments for the purpose of simplifying the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the claimed subject matter requires more features than expressly recited in each claim. On the contrary, as reflected in the following claims, the inventive subject matter lies in fewer than all features of a single disclosed configuration or operation. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separately claimed subject matter.

[0185] The claims are not intended to be limited to the aspects described herein, but are to be accorded the full scope consistent with the claim language and encompassing all legal equivalents. However, no claim is intended to encompass subject matter that is inconsistent with applicable patent law requirements, nor should it be so construed.

Claims

1. A first access point (AP) device in a wireless network, the first AP device comprising: Memory; as well as a processor coupled to the memory, the processor being configured to: receiving information related to a target wake-up time (TWT) schedule established in a second basic service set (BSS), wherein the second BSS is established by a second AP device; and Ensure that a transmission opportunity TXOP established in a first BSS ends before a start time of a TWT service period of the TWT schedule established in the second BSS, wherein the first BSS is established by the first AP device.

2. The first AP device according to claim 1, wherein: The processor is further configured to: During the TWT service period, no frames are sent to any station in the first BSS associated with the first AP device.

3. The first AP device according to claim 1, wherein: The processor is further configured to: After the start time of the TWT service period, not sending frames to any station associated with the first AP device in the first BSS; as well as Initiate communication with a station associated with the first AP device within a time indicated from the second AP device, wherein the time is before an end time of the TWT service period.

4. The first AP device according to claim 1, wherein: The TWT scheduling established in the second BSS is associated with the communication of delay-sensitive services.

5. The first AP device according to claim 1, wherein: The processor is further configured to: After the start time of the TWT service period, not sending frames to any station associated with the first AP device in the first BSS; receiving a trigger frame to request a response frame from the second AP device; as well as Before an end time of the TWT service period, communication is initiated with a station associated with the first AP device.

6. The first AP device according to claim 1, wherein: The processor is further configured to: receiving a request frame for multi-AP coordination from the second AP device; and Sending a response frame to the second AP device indicating acceptance of the request for multi-AP coordination.

7. The first AP device according to claim 6, wherein: The processor is further configured to: receiving an announcement frame for the multi-AP coordination from the second AP device; and Sending a frame indicating the ability to participate in the multi-AP coordination to the second AP device.

8. The first AP device according to claim 1, wherein: Receive information related to the TWT scheduling from the second AP device.

9. The first AP device according to claim 1, wherein: The processor is further configured to: sending a TWT element including information for the TWT schedule to one or more stations associated with the first AP device, and The TWT element includes information indicating that the TWT scheduling is established in the second BSS.

10. The first AP device according to claim 1, wherein: The processor is further configured to: Receive a request frame for multi-AP coordination from the controller; Sending a response frame indicating acceptance of the request for multi-AP coordination to the controller; receiving TWT coordination information including information related to the TWT schedule from the controller; and In response to the TWT coordination information, an acknowledgement is sent to the controller.

11. A station in a wireless network, the station comprising: Memory; a processor coupled to the memory, the processor being configured to: receiving a target wake time (TWT) element from a first access point (AP) device associated with the station, wherein the TWT element includes information indicating that a TWT schedule corresponding to the TWT element is established in a second service set (BSS) established by a second AP device; and Ensure that a transmission opportunity TXOP established in a first BSS ends before the start time of a TWT service period scheduled by the TWT, wherein the first BSS is established by the first AP device.

12. The station according to claim 11, wherein The processor is further configured to: During the TWT service period, no frames are sent to the first AP device.

13. A first access point (AP) device in a wireless network, the first AP device comprising: Memory; as well as a processor coupled to the memory, the processor being configured to: Sending a request frame for multi-AP coordination to a second AP device, wherein the request frame includes a TWT schedule established in a first basic service set BSS, and the first BSS is established by the first AP device; as well as A response frame indicating acceptance of the multi-AP coordination is received from the second AP device.

14. The first AP device according to claim 17, wherein: The processor is further configured to: Sending a notification frame for the multi-AP coordination to one or more second AP devices, wherein the notification frame includes mode information for the multi-AP coordination; and A frame indicating an ability to participate in the multi-AP coordination is received from the second AP device.

15. The first AP device according to claim 13, wherein: The processor is further configured to: Before an end time of a TWT service period corresponding to the TWT schedule, a trigger frame is sent to the second AP device, wherein the trigger frame indicates that the second AP is allowed to initiate communication with associated stations in a second BSS.

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