Apparatus and method for target wake-up time in multi-link operation

Abstract

A first broadcast target wake time (TWT) schedule may be established on a first link between an access point (AP) multi-link device (MLD) and a non-AP MLD, and the first link may be about to become unavailable. The AP MLD may announce that the first broadcast TWT schedule on the first link becomes unavailable and a replacement broadcast TWT schedule is available on an alternative link starting from a time indicated in a link replacement time subfield of the broadcast TWT link replacement element by including a broadcast TWT link replacement element in a beacon frame or a probe response frame.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communication systems, and more particularly to, for example but not limited to, target wake time (TWT) operations in wireless communication systems. Background Art

[0002] Since the late 1990s, wireless local area network (WLAN) technology has evolved toward increased data rates and continues its growth in various markets such as home, enterprise, and hotspots. WLAN allows devices to access the Internet in the 2.4GHz, 5GHz, 6GHz, or 60GHz frequency bands. WLAN is based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. The IEEE802.11 family of standards is designed to increase speed and reliability and extend the operating range of wireless networks.

[0003] WLAN devices are increasingly required to support various delay-sensitive or real-time applications, such as augmented reality (AR), robotics, artificial intelligence (AI), cloud computing, and driverless vehicles. In order to achieve the extremely low latency and extremely high throughput required for such applications, multi-link operation (MLO) has been proposed for WLAN. A WLAN is formed by WLAN devices in a limited area such as a home, school, apartment, or office building. Each WLAN device may have one or more stations (STAs), such as an access point (AP) STA and a non-access point (non-AP) STA.

[0004] MLO can enable a non-AP multi-link device (MLD) to establish multiple links with an AP MLD. Each of the multiple links can independently implement channel access and frame exchange between the non-AP MLD and the AP MLD, which can reduce latency and increase throughput.

[0005] The descriptions set forth in the Background section should not be assumed to be prior art merely because they are set forth in the Background section. The Background section may describe aspects or embodiments of the present disclosure. Summary of the invention

[0006] Solution to the problem

[0007] One embodiment of the present disclosure may provide an AP MLD associated with a non-access point (AP) multi-link device (MLD) in a wireless network. The AP MLD includes at least two affiliated APs, and a processor is coupled to the at least two APs. The processor is configured to: establish a first broadcast target wake-up time (TWT) schedule on a first link between a first AP affiliated to the AP MLD and a first station (STA) affiliated to the non-AP MLD; send TWT link replacement information to the non-AP MLD via at least one link between the AP MLD and the non-AP MLD, the TWT link replacement information indicating that the first broadcast TWT schedule on the first link is replaced by a second broadcast TWT schedule on a second link between a second AP affiliated to the AP MLD and a second STA affiliated to the non-AP MLD; receive a link replacement acknowledgment from the non-AP MLD via a link between the AP MLD and the non-AP MLD; and move the first broadcast TWT schedule on the first link to the second broadcast TWT schedule on the second link.

[0008] In some embodiments, the processor is configured to move a first broadcast TWT schedule on a first link to a second broadcast TWT schedule on a second link at a time indicated in the TWT link replacement information.

[0009] In some embodiments, a first broadcast TWT schedule on a first link becomes unavailable at a time indicated in the TWT link replacement information, and a second broadcast TWT schedule on a second link becomes available at a time indicated in the TWT link replacement information.

[0010] In some embodiments, the TWT link replacement information is included in a beacon frame or a probe response frame.

[0011] In some embodiments, the link replacement confirmation includes the same information as the TWT link replacement information sent by the AP MLD.

[0012] In some embodiments, the TWT link replacement information includes an identifier of the first broadcast TWT schedule and an identifier of the second broadcast TWT schedule.

[0013] In some embodiments, the TWT link replacement information includes a minimum amount of time that the second STA is expected to wake up on the second link for the TWT wake-up interval period.

[0014] In some embodiments, the TWT link replacement information includes an identifier of the first link and an identifier of the second link.

[0015] In some embodiments, the first broadcast TWT schedule is a first restricted TWT (R-TWT) schedule, and the second broadcast TWT schedule is a second R-TWT schedule, and one or more R-TWT traffic identifiers (TIDs) of the second R-TWT schedule on the second link are derived using an intersection of a first TID set and a second TID set. The first TID set is one or more R-TWT TIDs of the first R-TWT schedule, and the second TID set is one or more TIDs mapped on the second link using a TID to link mapping.

[0016] In some embodiments, the TWT parameters of the second R-TWT schedule that are not included in the TWT link replacement information are the same as the TWT parameters of the first R-TWT schedule.

[0017] One embodiment of the present disclosure provides a non-AP MLD associated with an access point (AP) multi-link device (MLD) in a wireless network. The non-AP MLD includes at least two affiliated stations (STAs) and a processor coupled to the at least two STAs. The processor is configured to: establish membership of a first broadcast target wake-up time (TWT) schedule on a first link between a first STA affiliated with the non-AP MLD and a first AP affiliated with the AP MLD; receive TWT link replacement information from the AP MLD via at least one link between the non-AP MLD and the AP MLD, the TWT link replacement information indicating that the first broadcast TWT schedule on the first link is replaced by a second broadcast TWT schedule on a second link between a second STA affiliated with the non-AP MLD and a second AP affiliated with the AP MLD; and send a link replacement confirmation to the AP MLD via a link between the non-AP MLD and the AP MLD in response to receiving the TWT link replacement information.

[0018] In some embodiments, a first broadcast TWT schedule on a first link is moved to a second broadcast TWT schedule on a second link at a time indicated in the TWT link replacement information.

[0019] In some embodiments, a first broadcast TWT schedule on a first link becomes unavailable at a time indicated in the TWT link replacement information, and a second broadcast TWT schedule on a second link becomes available at a time indicated in the TWT link replacement information.

[0020] In some embodiments, the TWT link replacement information is included in a beacon frame or a probe response frame.

[0021] In some embodiments, the link replacement confirmation includes the same information as the TWT link replacement information received from the AP MLD.

[0022] In some embodiments, the TWT link replacement information includes an identifier of the first broadcast TWT schedule and an identifier of the second broadcast TWT schedule.

[0023] In some embodiments, the TWT link replacement information includes a minimum amount of time that the second STA is expected to wake up on the second link for the TWT wake-up interval period.

[0024] In some embodiments, the TWT link replacement information includes an identifier of the first link and an identifier of the second link.

[0025] In some embodiments, the first broadcast TWT schedule is a first restricted TWT (R-TWT) schedule, and the second broadcast TWT schedule is a second R-TWT schedule, and one or more R-TWT traffic identifiers (TIDs) of the second R-TWT schedule on the second link are derived using an intersection of a first TID set and a second TID set. The first TID set is one or more R-TWT TIDs of the first R-TWT schedule, and the second TID set is one or more TIDs mapped on the second link using a TID to link mapping.

[0026] In some embodiments, the TWT parameters of the second R-TWT schedule that are not included in the TWT link replacement information are the same as the TWT parameters of the first R-TWT schedule. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 An example of a wireless network according to an embodiment is shown.

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

[0029] Figure 2b An example of a STA according to an embodiment is shown.

[0030] Figure 3 An example of multi-link operation according to an embodiment is shown.

[0031] Figure 4 An example of a TID-to-link mapping element according to an embodiment is shown.

[0032] Figure 5 An example of wireless communication according to an embodiment is shown.

[0033] Figure 6 An example of wireless communication according to an embodiment is shown.

[0034] Figure 7 An example of an R-TWT link replacement element according to an embodiment is shown.

[0035] Figure 8 An example of wireless communication according to an embodiment is shown.

[0036] Fig. 9 An example of wireless communication according to an embodiment is shown.

[0037] Fig.10a and Fig.10b An example of an R-TWT link replacement element format according to an embodiment is shown.

[0038] Fig.11 An example of a broadcast TWT link replacement element format according to an embodiment is shown.

[0039] Fig.12 An example of a link replacement procedure performed by an AP MLD according to an embodiment is shown.

[0040] Fig.13 An example of a link replacement procedure performed by a non-AP MLD according to an embodiment is shown.

[0041] Fig.14a and Fig.14b An example of wireless communication according to an embodiment is shown.

[0042] In one or more embodiments, all of the components depicted in each figure may not be required, and one or more embodiments may include additional components not shown in the figures. The arrangement and type of components may be varied without departing from the scope of the present disclosure. Additional components, different components, or fewer components may be utilized within the scope of the present disclosure. DETAILED DESCRIPTION

[0043] The detailed description set forth below in conjunction with the drawings is intended to be a description of 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 of the present invention. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways, all without departing from the scope of the present disclosure. Therefore, the drawings and descriptions are considered to be illustrative and non-restrictive in nature. The same reference numerals represent the same elements.

[0044] For the purpose of describing the innovative aspects of the present invention, the following description is directed to certain embodiments. 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 may be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals in accordance with the IEEE 802.11 standard, the Bluetooth standard, the 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 communicating within a wireless, cellular, or Internet of Things (IoT) network, such as a system utilizing 3G, 4G, 5G, 6G, or further implementations thereof.

[0045] Figure 1 An example of a wireless network 100 according to an embodiment is shown. Figure 1 The embodiment of the wireless network 100 shown in FIG. 1 is for illustration purposes only. Other embodiments of the wireless network 100 may be used without departing from the scope of the present disclosure.

[0046] 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 separately addressable instance of a medium access control (MAC) layer and a physical (PHY) layer interface to a wireless medium. A STA may be classified into an access point (AP) STA and a non-access point (non-AP) STA. An AP STA may be an entity that provides access to distribution system services to 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 , 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.

[0047] 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 multiple stations 111-114 having a coverage area 120 of AP 101. APs 101 and 103 may communicate with each other and with STAs using Wi-Fi or other WLAN communication technologies.

[0048] Depending on the network type, other well-known terms may be used instead of "access point" or "AP", such as "router" or "gateway". For convenience, the term "AP" is used in this disclosure to refer to a network infrastructure component that provides wireless access to a remote terminal. In a WLAN, assuming that the AP also competes for a wireless channel, the AP may also be referred to as a STA. In addition, depending on the network type, other well-known terms may be used instead of "station" or "STA", such as "mobile station", "subscriber station", "remote terminal", "user equipment", "wireless terminal" or "user device". For convenience, the terms "station" and "STA" are used in this disclosure to refer to a remote wireless device that wirelessly accesses an AP or competes for a wireless channel in a WLAN, whether the STA is a mobile device (such as a mobile phone or smart phone) or is generally considered to be a fixed device (such as a desktop computer, AP, media player, fixed sensor, television, etc.).

[0049] exist Figure 1 , the dashed lines show the approximate extents of the coverage areas 120 and 125 of APs 101 and 103, which are shown as approximately circular for purposes of illustration and explanation. It should be clearly understood that the coverage areas associated with APs, such as coverage areas 120 and 125, may have other shapes, including irregular shapes, depending on the configuration of the APs.

[0050] As described in more detail below, one or more of the APs may include circuitry and / or programming for managing MU-MIMO and 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, the wireless network 100 may include any number of APs and any number of STAs in any suitable arrangement. In addition, the AP 101 may communicate directly with any number of STAs and provide these STAs with wireless broadband access to the network 130. Similarly, each of the APs 101 and 103 may communicate directly with the network 130 and provide the STAs with direct wireless broadband access to the network 130. In addition, the APs 101 and / or 103 may provide access to other or additional external networks (such as an external telephone network or other types of data networks).

[0051] Figure 2a An example of an AP 101 according to an embodiment is shown. Figure 2a The embodiment of AP 101 shown in FIG. 1 is for illustrative purposes, and Figure 1 The APs 103 may have the same or similar configurations. However, APs have a wide range of configurations, and Figure 2a The scope of the present disclosure is not limited to any particular implementation of an AP.

[0052] like Figure 2a As shown, the 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. The AP 101 may also include a controller / processor 224, a 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 the network 100. The RF transceivers 209a-209n down-convert the incoming RF signals to generate intermediate (IF) or baseband signals. The IF or baseband signals are sent to the 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.

[0053] The TX processing circuit 214 receives analog or digital data (such as voice data, network data, email, or interactive video game data) from the controller / processor 224. The TX processing circuit 214 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceivers 209a-209n receive the outgoing processed baseband or IF signals from the TX processing circuit 214 and up-convert the baseband or IF signals to RF signals that are transmitted via the antennas 204a-204n.

[0054] 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, the RX processing circuit 219, and the TX processing circuit 214 according to well-known principles. The controller / processor 224 may also support additional functions, such as more advanced wireless communication functions. For example, the controller / processor 224 may support beamforming or directional routing operations, in which outgoing signals from multiple antennas 204a-204n are weighted differently to effectively direct the outgoing signals in the desired direction. The controller / processor 224 may also support OFDMA operations, in which outgoing signals are assigned to different subcarrier subsets of different recipients (e.g., different STAs 111-114). The controller / processor 224 may support any of a variety of other functions in the AP 101, including a combination of DL MU-MIMO and OFDMA in the same transmit 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 an OS, residing in the memory 229. The controller / processor 224 may move data into or out of the memory 229 as required by the execution process.

[0055] The controller / processor 224 is also coupled to a backhaul or network interface 234. The backhaul or network interface 234 allows the AP 101 to communicate with other devices or systems over a backhaul connection or over a network. The interface 234 can support communication over any suitable wired or wireless connection. For example, the interface 234 can allow the AP 101 to communicate over a wired or wireless local area network or over a wired or wireless connection to a larger network (such as the Internet). The interface 234 can include any suitable structure that supports communication over a wired or wireless connection, such as an Ethernet or RF transceiver. The memory 229 is coupled to the controller / processor 224. A portion of the memory 229 may include RAM, and another portion of the memory 229 may include flash memory or other ROM.

[0056] 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 functions to route data between different network addresses. As another example, although shown as including a single instance of TX processing circuitry 214 and a single instance of RX processing circuitry 219, the AP 101 may include multiple instances of each (such as one for each 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.

[0057] like Figure 2a As shown, in some embodiments, the AP 101 may be an AP MLD including a plurality of APs 202a-202n. Each AP 202a-202n is attached to the AP MLD 101 and includes a plurality of antennas 204a-204n, a plurality of radio frequency (RF) transceivers 209a-209n, a transmit (TX) processing circuit 214, and a receive (RX) processing circuit 219. Each AP 202a-202n may independently communicate with the controller / processor 224 and other components of the 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.

[0058] Figure 2b An example of STA 111 according to an embodiment is shown. Figure 2b The embodiment of STA 111 shown in FIG. 1 is for illustrative purposes, and Figure 1 STAs 111-114 may have the same or similar configurations. However, STAs have a variety of configurations, and Figure 2b The scope of this disclosure is not limited to any particular implementation of a STA.

[0059] like Figure 2b As shown, STA 111 may include antenna 205, RF transceiver 210, TX processing circuit 215, microphone 220, and RX processing circuit 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 operating system (OS) 261 and one or more applications 262.

[0060] RF transceiver 210 receives incoming RF signals sent by APs of network 100 from antenna 205. RF transceiver 210 downconverts the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are sent to RX processing circuitry 225, which generates processed baseband signals by filtering, decoding, and / or digitizing the baseband or IF signals. RX processing circuitry 225 sends the processed baseband signals to speaker 230 (such as for voice data) or to controller / processor 240 for further processing (such as for web browsing data).

[0061] The TX processing circuit 215 receives analog or digital voice data from the microphone 220, or receives other outgoing baseband data (such as network data, email, or interactive video game data) from the controller / processor 240. The TX processing circuit 215 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceiver 210 receives the outgoing processed baseband or IF signal from the TX processing circuit 215 and up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna 205.

[0062] 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 reception of downlink signals and the transmission of uplink signals by the RF transceiver 210, the RX processing circuit 225, and the TX processing circuit 215 according to well-known principles. The controller / processor 240 may also include a processing circuit 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.

[0063] The controller / processor 240 is also capable of executing other processes and programs resident in the memory 260, such as operations for managing the channel sounding process in the WLAN. The controller / processor 240 can move data into or out of the memory 260 as needed for the execution process. In some embodiments, the controller / processor 240 is configured to execute multiple applications 262, such as applications for channel sounding, including feedback calculations based on received null data packet announcements (NDPA) and null data packets (NDP), and sending beamforming feedback reports in response to trigger frames (TFs). The controller / processor 240 can operate multiple applications 262 based on the OS program 261 or in response to signals received from the AP. The controller / processor 240 is also coupled to the I / O interface 245, which provides the STA 111 with the ability to connect to other devices such as laptops and handheld computers. The I / O interface 245 is a communication path between these accessories and the main controller / processor 240.

[0064] The controller / processor 240 is also coupled to an input 250 (such as a touch screen) and a display 255. An operator of the STA 111 can use the input 250 to enter data into the STA 111. The display 255 can be a liquid crystal display, a light emitting diode display, or other display capable of presenting text and / or at least limited graphics, such as from a website. A memory 260 is coupled to the controller / processor 240. A portion of the memory 260 can include random access memory (RAM), and another portion of the memory 260 can include flash memory or other read-only memory (ROM).

[0065] although Figure 2b An example of STA 111 is shown, but the 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 required. 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 communications, or the controller / processor 240 may be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). In addition, although Figure 2b STA 111 is shown configured as a mobile phone or smart phone, but the STA may be configured to operate as other types of mobile or stationary devices.

[0066] like Figure 2bAs shown, in some embodiments, STA 111 may be a non-AP MLD including multiple STAs 203a-203n. Each STA 203a-203n is attached to the non-AP MLD 111 and includes an antenna 205, an RF transceiver 210, a TX processing circuit 215, and an RX processing circuit 225. Each STA 203a-203n may independently communicate with the controller / processor 240 and other components of the 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.

[0067] 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, and the non-AP MLD 220 may be Figure 1 One of the wireless communication devices 111-114 in.

[0068] like Figure 3 As shown, AP MLD 310 may include multiple subordinate APs, including, for example, AP 1, AP 2, and AP 3. Each subordinate AP may include a PHY interface (Link 1, Link 2, or Link 3) to a wireless medium. AP MLD 310 may include a single MAC Service Access Point (SAP) 318 through which subordinate APs of AP MLD 310 communicate with a higher layer (Layer 3 or Network Layer). Each subordinate AP of AP MLD 310 may have a different MAC address (lower MAC address) from any other subordinate AP of AP MLD 310. AP MLD 310 may have an MLD MAC address (upper MAC address), and the subordinate APs share a single MAC SAP 318 to Layer 3. Therefore, the subordinate APs share a single IP address, and Layer 3 identifies AP MLD 310 by assigning a single IP address.

[0069] The non-AP MLD 320 may include a plurality of subordinate STAs, for example, including STA 1, STA 2, and STA 3. Each subordinate STA may include a PHY interface (Link 1, Link 2, or Link 3) to a wireless medium. 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 a higher layer (Layer 3 or network layer). Each subordinate STA of the non-AP MLD 320 may have a different MAC address (lower MAC address) from any other subordinate STA of the non-AP MLD 320. The non-AP MLD 320 may have an MLD MAC address (higher MAC address), and the subordinate STAs share a single MAC SAP 328 to Layer 3. Therefore, the subordinate STAs share a single IP address, and Layer 3 identifies the non-AP MLD 320 by assigning a single IP address.

[0070] The AP MLD 310 and the non-AP MLD 320 may establish multiple links between their subordinate APs and STAs. In this example, AP 1 and STA 1 may establish Link 1 operating in the 2.4 GHz band. Similarly, AP 2 and STA 2 may establish Link 2 operating in the 5 GHz band, and AP 3 and STA 3 may establish Link 3 operating in the 6 GHz band. Each link may independently enable channel access and frame exchange between the AP MLD 310 and the non-AP MLD 320, which may increase data throughput and reduce latency.

[0071] In order to prioritize the transmission of different types of traffic identified by traffic identifiers (TIDs) between established links, the non-AP MLD 320 may negotiate a TID-to-link mapping with the AP MLD 310. The TID-to-link mapping allows the AP MLD 310 and the non-AP MLD 320 to determine how frames belonging to a TID are allocated for transmission on each established link in the uplink and downlink directions, respectively. When at least one TID associated with the non-AP MLD 320 is mapped to an established link in the uplink or downlink direction, the link is referred to as an enabled link of the non-AP MLD 320. By default, all TIDs are mapped to all established links between the AP MLD 310 and the non-AP MLD 320, and the mapping is referred to as a default TID-to-link mapping. During association, the non-AP MLD 320 may negotiate a non-default mapping of TIDs to established links using a negotiation process by including a TID-to-link mapping element in an association request frame or a reassociation request frame. The non-default mapping may be the case where all TIDs are mapped to the same subset of established links, or the case where not all TIDs are mapped to the same subset of established links. The AP MLD 310 may also use a broadcast process to indicate a switch to a non-default mapping for all associated non-AP MLDs. In the default mapping mode, all TIDs are mapped to all established links for downlinks and uplinks, and all established links are enabled. When TID-to-link mapping negotiation does not occur or is unsuccessful, the non-AP MLD 320 operates in the default mapping mode.

[0072] Figure 4 An example of a TID-to-link mapping element 400 is shown according to an embodiment. Figure 4 This example may be applicable to the IEEE 802.11be standard and any future revisions of the IEEE 802.11 standard. The TID-to-link mapping element 400 may indicate the link over which frames belonging to each TID may be exchanged.

[0073] like Figure 4 As shown, the TID to link mapping element 400 may include an element ID field, a length field, an element ID extension field, a TID to link mapping control field, a mapping switch time field, an expected duration field, and an optional link mapping of a TID n field.

[0074] The element ID field and the element ID extension field may include information for identifying the TID-to-link mapping element 400. The length field may indicate the length of the TID-to-link mapping element 400.

[0075] The TID to link mapping control field may include a direction subfield, a default link mapping subfield, a mapping switch time existence subfield, an expected duration existence subfield, a link mapping size subfield, a reserved subfield, and an optional link mapping existence indicator subfield. The direction subfield may indicate whether the TID to link mapping element 400 is for a downlink frame, an uplink frame, or both. For example, for a downlink frame, the direction subfield may be set to 0, for an uplink frame, the direction subfield may be set to 1, and for a frame sent on a downlink and an uplink, the direction subfield may be set to 2. The default link mapping subfield may indicate whether the TID to link mapping element 400 represents a default TID to link mapping. For example, for a default mapping, the subfield may be set to 1, and for a non-default mapping, the subfield may be set to 0. The mapping switch time existence subfield may indicate whether the mapping switch time field exists in the TID to link mapping element 400. The expected duration existence subfield may indicate whether the expected duration field exists in the TID to link mapping element 400. The link mapping size subfield may indicate the length of the link mapping of the TID n field. The link mapping present indicator subfield may indicate whether a link mapping for the TID n field exists in the TID to link mapping element 400 .

[0076] The Mapping Switch Time field is present when the TID-to-Link Mapping element 400 is sent in a beacon or probe response frame by an AP attached to an AP MLD and the indicated TID-to-link mapping has not yet been established.

[0077] The expected duration field may indicate the duration for which the proposed TID-to-link mapping is expected to be valid when the mapping switch time field is present, and the remaining duration for which the proposed TID-to-link mapping is expected to be valid when the mapping switch time field is not present.

[0078] The Link Mapping of TID n field (e.g., where n=0, 1, ..., 7) may indicate links on which frames belonging to TID n are allowed to be sent. The Link Mapping of TID n field may carry a bitmap of links to which TID n is mapped. The Link Mapping of TID n field may not exist when the Default Link Mapping subfield of the TID to Link Mapping Control field indicates a default TID to link mapping. For example, when the Direction subfield is set to 0, the Default Link Mapping subfield is set to 0, and the Link Mapping of TID 0 field is configured as 10000 ... 0, the configuration indicates that downlink data corresponding to TID 0 is sent on Link 1.

[0079] The TID-to-link mapping element 400 may be included in various management frames, such as a beacon frame, an association request / response frame, a reassociation request / response frame, or a probe response frame.

[0080] The IEEE 802.11be standard introduces restricted target wake time (R-TWT) operation to provide better support for delay-sensitive applications. R-TWT operation based on broadcast TWT operation is a feature that provides enhanced medium access protection and resource reservation for delivering delay-sensitive services.

[0081] R-TWT operation provides protected service periods (SP) for R-TWT member STAs by sending one or more Quiet elements to other STAs in the BSS that are not members of R-TWT. The quiet interval indicated by the Quiet element overlaps with the initial part of the R-TWT SP. Therefore, it can provide more channel access opportunities for R-TWT member STAs, and it can certainly help improve signal-sensitive services.

[0082] Figure 5 An example of wireless communication according to an embodiment is shown. This example may be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard. The AP MLD 510 and the non-AP MLD 520 may be respectively Figure 3 An example of an APMLD 310 and a non-AP MLD 320 is shown. The AP MLD 510 may include three subordinate APs (AP 1, AP 2, and AP 3), and the non-AP MLD 520 may include three subordinate STAs (STA 1, STA 2, and STA 3). AP 1 and STA 1 may operate on link 1, AP 2 and STA 2 may operate on link 2, and AP 3 and STA 3 may operate on link 3. Link 1 may use a 2.4 GHz frequency band, link 2 may use a 5 GHz frequency band, and link 3 may use a 6 GHz frequency band.

[0083] exist Figure 5, an R-TWT schedule may be established on link 1. The first R-TWT SP (R-TWT SP-1) may start at time t1 and end at time t2. The second R-TWT SP (R-TWT SP-2) may start at time t4 and end at time t5. However, for some reason, link 1 may be scheduled to be deleted or disabled at time t3. For example, link 1 may be muted or become unavailable due to power saving purposes or regulatory reasons. AP MLD 510 has established an R-TWT schedule for delay-sensitive services on link 1. Therefore, if the second R-TWT SP (R-TWT SP-2) is not available to non-AP MLD 520, the delay-sensitive services of non-AP MLD 520 will be affected. For other non-AP MLDs ( Figure 5 ), a similar situation may occur. Therefore, the APMLD 510 needs a mechanism for establishing a replacement R-TWT scheduling on a different link (e.g., link 2 or link 3) before the R-TWT scheduling on link 1 becomes unavailable. Such a mechanism can allow the non-AP MLD 520 and the AP MLD 510 to seamlessly exchange delay-sensitive services or bufferable units (BUs) on another link before link 1 becomes unavailable. Currently, the IEEE 802.11 standard does not provide such a mechanism. Therefore, the AP MLD 510 and the non-AP MLD 520 need to renegotiate another R-TWT scheduling on the alternative link, which may not be a seamless process. In addition, there may be multiple non-AP MLDs in the BSS that have R-TWT scheduling on link 1. If the AP MLD 510 needs to perform a 1-to-1 negotiation with all non-AP MLDs to establish a replacement R-TWT scheduling on the alternative link, it may take a lot of time. Therefore, the non-AP MLD carrying delay-sensitive services may be affected by the excessive time required to negotiate the replacement R-TWT scheduling. This situation will cause problems for non-AP MLD with delay-sensitive applications.

[0084] The present disclosure provides a mechanism for transitioning an R-TWT schedule from one link to another in a broadcast manner. In some embodiments, an AP attached to an AP MLD may announce in its BSS that a first R-TWT schedule established in a first link will become unavailable due to some reason (e.g., link deletion or link disabling). In addition, an AP attached to an APMLD may announce the establishment of one or more alternative R-TWT schedules on one or more alternative links for one or more associated non-AP MLDs, which operate on the first link and have R-TWT membership for the first R-TWT schedule. In the present disclosure, an alternative R-TWT schedule on an alternative link may be referred to as a replacement R-TWT schedule or a link replacement R-TWT schedule. In some embodiments, an AP MLD may use a new element to make an announcement about a link state (e.g., link replacement). The new element may be included in a broadcast frame such as a beacon frame or a probe response frame, which is sent on any link between an AP MLD and a non-AP MLD. In some implementations, the AP MLD may unilaterally establish an alternate R-TWT schedule on an alternate link for all non-AP MLDs associated with the AP MLD. Thus, there may be no need to negotiate an alternate R-TWT schedule.

[0085] Figure 6 An example of wireless communication according to an embodiment is shown. This example may be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard. The AP MLD 610 and the non-AP MLD 620 may be respectively Figure 3 An example of an APMLD 310 and a non-AP MLD 320 is shown. The AP MLD 610 may include three subordinate APs (AP 1, AP 2, and AP 3), and the non-AP MLD 620 may include three subordinate STAs (STA 1, STA 2, and STA 3). AP 1 and STA 1 may operate on link 1 (a first link), AP 2 and STA 2 may operate on link 2 (a second link), and AP 3 and STA 3 may operate on link 3 (a third link). Link 1, link 2, and link 3 may use a 2.4 GHz band, a 5 GHz band, and a 6 GHz band, respectively.

[0086] exist Figure 6, a first R-TWT schedule (R-TWT schedule-1) is established on link 1. The AP MLD 610 may send a beacon frame including an R-TWT link replacement element via all links between the AP MLD 610 and the non-AP MLD 620. In some embodiments, the AP MLD 610 may send one or more beacon frames including an R-TWT link replacement element via a portion of all links (including replacement links) between the AP MLD 610 and the non-AP MLD 620. The R-TWT link replacement element is configured to announce that the first R-TWT schedule on link 1 is about to become unavailable, and as a replacement, a second R-TWT schedule (R-TWT schedule-2) will be established on link 2 from the time indicated by the R-TWT link replacement element. In some embodiments, the R-TWT link replacement element may be included in a probe response frame sent from the AP MLD 610.

[0087] When STA 1 of non-AP MLD 620 has obtained membership of the first R-TWT schedule on link 1 and non-AP MLD 620 receives the R-TWT link replacement element included in the beacon frame, the second R-TWT schedule may start from the time indicated in the link replacement time subfield of the R-TWT link replacement element. In addition, the first R-TWT schedule on link 1 may be suspended for STA 1 of non-AP MLD 620 at the time indicated in the link replacement time subfield of the R-TWT link replacement element. STA 2 of non-AP MLD 620 becomes a member of the second R-TWT schedule on link 2. Figure 6 In the example, the second R-TWT scheduling (R-TWT scheduling-2) on link 2 is a replacement R-TWT scheduling. Figure 6 The second R-TWT schedule (R-TWT schedule-2) in the may have an SP duration different from that of the first R-TWT schedule (R-TWT schedule-1), but have the same period as the first R-TWT schedule (R-TWT schedule-1).

[0088] Figure 7 An example of an R-TWT link replacement element according to an embodiment is shown. This example may be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard.

[0089] exist Figure 7 In the R-TWT link replacement element 700, a broadcast TWT ID field, a link replacement time field, a duration field, a from link ID field, a to link ID field, a periodicity field, a target wake-up time field, and a reserved field.

[0090] refer to Figure 6 and Figure 7 , the broadcast TWT ID field may indicate a broadcast TWT ID corresponding to the first R-TWT schedule on the first link (link 1) indicated by the from link ID field. When the first R-TWT schedule on link 1 and the second R-TWT schedule on link 2 both have the same broadcast TWT ID, the two broadcast TWT IDs may be identified by the broadcast TWT ID field. In some embodiments, the first R-TWT schedule on link 1 and the second R-TWT schedule on link 2 may have different broadcast TWT IDs. In this case, the R-TWT link replacement element may include two broadcast TWT ID fields: a previous broadcast TWT ID field and a replacement broadcast TWT ID field. Therefore, the first broadcast TWT ID on link 1 may be identified by the previous broadcast TWT ID field, and the second broadcast TWT ID on link 2 may be identified by the replacement broadcast TWT ID field.

[0091] The link replacement time field may indicate the time at which the R-TWT schedule moves from the first link to the second link (ie, the alternative link). In some implementations, the link replacement time field may be specified in terms of a target beacon transmission time (TBTT).

[0092] The Duration field may indicate the amount of time for the service period (SP) of the replacement TWT schedule on the alternative link. Figure 6 In the example, the duration subfield can indicate the SP of the second TWT scheduling on link 2.

[0093] The From Link ID field may indicate the link of the AP MLD from which the R-TWT schedule is moved to the alternate link. The To Link ID field may indicate the link of the AP MLD to which the R-TWT schedule is moved. Figure 6 In the example of , the from link ID field and the to link ID field may indicate link 1 and link 2, respectively.

[0094] The Periodicity field may indicate the periodicity of the replacement R-TWT schedule on the replacement link. The Target Wake-up Time field may indicate the target wake-up time of the replacement R-TWT schedule on the replacement link. Figure 6 In the example, the periodicity field and the target wake-up time field can indicate the periodicity and target wake-up time of the second R-TWT scheduling on link 2.

[0095] In some embodiments, one or more parameters of the second R-TWT schedule on the second link may be the same as those of the first R-TWT schedule on the first link.

[0096] In some embodiments, the parameters of the second R-TWT schedule on the second link that are not included in the R-TWT link replacement element may be the same as those of the first R-TWT schedule on the first link.

[0097] In some embodiments, when the AP MLD establishes a replacement R-TWT schedule on the second link as a replacement for the first R-TWT schedule on the first link, if a non-AP MLD is also operating on the second link, the STA of the same non-AP MLD operating on the second link becomes a member of the replacement R-TWT schedule starting from the time indicated in the link replacement time field.

[0098] In some embodiments, the SP duration of the replacement R-TWT schedule on the second link may be different from the SP duration of the first R-TWT schedule on the first link. The SP duration of the replacement R-TWT schedule may be adjusted to account for the operating channel, frequency, and bandwidth of the second link compared to the first link.

[0099] Figure 8 An example of wireless communication according to an embodiment is shown. This example may be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard. The AP MLD 810 and the non-AP MLD 820 may be respectively Figure 3 An example of an APMLD 310 and a non-AP MLD 320 is shown. The AP MLD 810 may include three subordinate APs (AP 1, AP 2, and AP 3), and the non-AP MLD 820 may include three subordinate STAs (STA 1, STA 2, and STA 3). AP 1 and STA 1 may operate on link 1 (a first link), AP 2 and STA 2 may operate on link 2 (a second link), and AP 3 and STA 3 may operate on link 3 (a third link). Link 1, link 2, and link 3 may use a 2.4 GHz band, a 5 GHz band, and a 6 GHz band, respectively.

[0100] exist Figure 8, two R-TWT schedules (R-TWT schedule-1) can be established on link 1. STA 1 attached to non-AP MLD 820 can be a member of the two R-TWT schedules. Link 1 may be scheduled to be unavailable due to some reasons. Before link 1 becomes unavailable, AP MLD 810 may announce in its BSS that the two R-TWT schedules (R-TWT schedule-1) can be replaced with another two R-TWT schedules (R-TWT schedule-2) on link 2. STA 2 of non-AP MLD 820 becomes a member of the new R-TWT schedule on link 2. In some embodiments, if an AP attached to AP MLD 810 intends to establish a replacement R-TWT schedule on an alternative link, any AP attached to AP MLD 810 may announce the time when the replacement R-TWT schedule will be effective. The replacement R-TWT schedules may have different SP durations but the same periodicity.

[0101] In some embodiments, when any AP affiliated with the AP MLD 810 intends to establish an alternative R-TWT schedule on an alternative link, an R-TWT broadcast link assignment element may be included in its beacon frame or probe response frame sent by the AP MLD 810. The R-TWT broadcast link assignment element may be included in the per-STA profile sub-element of the basic multilink element. The R-TWT broadcast link assignment element may include, but is not limited to, the following fields:

[0102] A time field indicating when the R-TWT schedule on the first link is scheduled to be unavailable and the replacement R-TWT schedule will be effective to replace the R-TWT schedule. The time can be expressed in TBTT;

[0103] SP field, indicating the service period (SP) of the replacement R-TWT;

[0104] Target wake-up time field, indicating the target wake-up time of the replacement R-TWT;

[0105] A periodicity field indicating the periodicity of replacing the R-TWT;

[0106] From the Link ID field, indicating the link of the AP MLD from which the R-TWT scheduler moved to the alternate link;

[0107] To Link ID field, indicating the link of the AP MLD to which the R-TWT scheduling is moved; and

[0108] • A Broadcast TWT ID field indicating the Broadcast TWT ID corresponding to the R-TWT schedule on the first link indicated by the From Link ID subfield.

[0109] The subfields of the R-TWT broadcast link assignment element are Figure 7 The corresponding fields of the R-TWT link replacement element in are the same or similar.

[0110] In some embodiments, when the AP MLD establishes a replacement TWT schedule on a second link as a replacement for a first R-TWT schedule on a first link, the TID applicable to the replacement R-TWT schedule on the second link may be the same as the TID applicable to the first R-TWT schedule on the first link, starting from the time indicated by the R-TWT broadcast link assignment element.

[0111] In some embodiments, when the AP MLD establishes a replacement R-TWT schedule on the second link as a replacement for the first R-TWT schedule on the first link, from the time indicated by the R-TWT broadcast link assignment element, the TID mapped on the first link is also mapped on the second link.

[0112] In some embodiments, when the AP MLD establishes a replacement R-TWT schedule on a second link as a replacement for a first R-TWT schedule on a first link, the TID negotiated for the first R-TWT schedule on the first link is mapped on the second link from the time indicated by the R-TWT broadcast link assignment element.

[0113] In some embodiments, when the AP MLD establishes a replacement R-TWT schedule on the second link as a replacement for the first R-TWT schedule on the first link, the non-AP MLD falls into the default mapping. Thus, all TIDs are mapped to all links between the AP MLD and the non-AP MLD.

[0114] Fig. 9 An example of wireless communication according to an embodiment is shown. This example may be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard. The AP MLD 910 and the non-AP MLD 920 may be respectively Figure 3 An example of an APMLD 310 and a non-AP MLD 320 is shown. The AP MLD 910 may include three subordinate APs (AP 1, AP 2, and AP 3), and the non-AP MLD 920 may include three subordinate STAs (STA 1, STA 2, and STA 3). AP 1 and STA 1 may operate on link 1 (a first link), AP 2 and STA 2 may operate on link 2 (a second link), and AP 3 and STA 3 may operate on link 3 (a third link). Link 1, link 2, and link 3 may use a 2.4 GHz band, a 5 GHz band, and a 6 GHz band, respectively.

[0115] exist Fig. 9 , two R-TWT schedules (Schedule-A and Schedule-B) of the first R-TWT schedule may be established on link 1. STA 1 attached to the non-AP MLD 920 may be a member of the two R-TWT schedules. Due to some reasons, link 1 may be unavailable starting from time t1. Before link 1 becomes unavailable, the AP MLD 910 may announce in its BSS that Schedule-A on link 1 is replaced by an alternative schedule on link 3, and Schedule-B on link 1 is replaced by an alternative schedule on link 2. The alternative schedule on link 3 is a replacement for Schedule-A of the first R-TWT schedule on link 1, and the alternative schedule on link 2 is a replacement for Schedule-B of the first R-TWT schedule on link 1. Therefore, STA 3 of the non-AP MLD 920 becomes a member of the new R-TWT schedule on link 3, and STA 2 of the non-AP MLD 920 becomes a member of the new R-TWT schedule on link 2.

[0116] Fig.10a An example of the R-TWT link replacement element format according to an embodiment is shown. This example can be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard.

[0117] The R-TWT link replacement element 1000 may include an element ID field, a length field, and a link replacement information field. The element ID field may include information for identifying the R-TWT link replacement element. The length field may indicate the length of the R-TWT link replacement element. The link replacement information field may include a broadcast TWT ID subfield, a link replacement time subfield, a minimum TWT wake-up duration subfield, a from link ID subfield, a to link ID subfield, and a reserved subfield.

[0118] The Broadcast TWT ID subfield may indicate a broadcast TWT ID corresponding to an R-TWT schedule that is moved from one link (eg, the first link) between the AP MLD and the non-AP MLD to another link (eg, the second link) using an R-TWT link replacement element.

[0119] The Link Replacement Time subfield may include a positive unsigned integer corresponding to a timing synchronization function (TSF) time at which the R-TWT schedule identified by the Broadcast TWT ID subfield moves from one link (e.g., the first link) to another link (e.g., the second link). The TSF time indicated in the Link Replacement Time subfield may be with respect to the TSF of the link from which the R-TWT schedule moves.

[0120] The Minimum TWT Wake-up Duration subfield may indicate the minimum amount of time that an R-TWT scheduled STA is expected to be awake during a TWT wake-up interval period corresponding to a replacement R-TWT schedule on the link to which the R-TWT schedule is moved. The units of the Minimum TWT Wake-up Duration subfield value of the Broadcast TWT Link Replacement element are the same as the units of the value of the Nominal Minimum TWT Wake-up Duration subfield from the original R-TWT schedule on the link indicated in the Link ID subfield.

[0121] The From Link ID subfield may indicate a link (eg, a first link) of the AP MLD from which the R-TWT scheduling moves to another link (eg, a second link).

[0122] The To Link ID subfield may indicate a link (eg, a second link) of the AP MLD to which the R-TWT scheduling is moved.

[0123] Fig.10b Another example of the R-TWT link replacement element format according to an embodiment is shown. This example can be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard.

[0124] In addition to a portion of the Link Replacement Information field, Fig.10b The fields in the R-TWT link replacement element 1010 can be used with Fig.10a The R-TWT link replacement element 1000 is the same or similar.

[0125] exist Fig.10b In the link replacement information field, the link replacement information field may include two broadcast TWT ID subfields: a from broadcast TWT ID subfield and a to broadcast TWT ID subfield. Fig.10a The link replacement information field in has a broadcast TWT ID subfield.

[0126] The From Broadcast TWT ID subfield can indicate a broadcast TWT ID corresponding to an R-TWT schedule that uses an R-TWT link replacement element to move from one link indicated by the From Link ID subfield (e.g., the first link) to another link (e.g., the second link) between the AP MLD and the non-AP MLD.

[0127] The To Broadcast TWT ID subfield may indicate a broadcast TWT ID corresponding to a replacement R-TWT schedule established on a link (e.g., a second link) indicated by the To Link ID subfield, to which the original R-TWT schedule is moved using an R-TWT link replacement element.

[0128] In various embodiments, when a first R-TWT schedule is established on a first link and the first link is scheduled to be unavailable, the AP MLD may declare that the first R-TWT schedule on the first link may be unavailable and a second R-TWT schedule may be established on a second link using an R-TWT link replacement element in a beacon frame or a probe response frame. The replacement R-TWT schedule (second R-TWT schedule) may be effective from the time indicated by the link replacement time subfield of the R-TWT link replacement element.

[0129] In some embodiments, a first STA attached to a non-AP MLD associated with an AP MLD has obtained membership in a first R-TWT schedule on a first link. The non-AP MLD may receive an R-TWT link replacement element included in a beacon frame or a probe response frame. The R-TWT link replacement element may indicate that the first R-TWT schedule on the first link is scheduled to be unavailable, and a second R-TWT schedule is established on a second link between the AP MLD and the non-AP MLD as a replacement. Then, the first R-TWT schedule on the first link may be suspended for the first STA at the time indicated in the link replacement time subfield of the R-TWT link replacement element. Starting from the time indicated in the link replacement time subfield of the R-TWT link replacement element, the second STA attached to the non-AP MLD may become a member of the second R-TWT schedule on the second link. The first link and the second link may be identified by the from link ID subfield and the to link ID subfield of the R-TWT link replacement element, respectively. The first R-TWT schedule on the first link may be specified by the broadcast TWT ID subfield of the R-TWT link replacement element. The minimum wake-up duration of the second R-TWT schedule on the second link is indicated by the Minimum TWT Wake-up Duration subfield of the R-TWT link replacement element. The other TWT parameters of the second R-TWT schedule on the second link may remain the same as the TWT parameters of the first R-TWT schedule on the first link. In an embodiment, the broadcast TWT ID of the second R-TWT schedule on the second link may be the same as the broadcast TWT ID of the first R-TWT schedule on the first link. It may be identified by the Broadcast TWT ID subfield of the R-TWT link replacement element. Alternatively, the broadcast TWT ID of the second R-TWT schedule on the second link may be different from the broadcast TWT ID of the first R-TWT schedule on the first link.

[0130] In some implementations, the beacon frame may include an R-TWT link replacement element. Table 1 shows an example of a beacon frame body including an R-TWT link replacement element in the last row.

[0131] [Table 1]

[0132]

[0133]

[0134] In some implementations, the probe response frame may include an R-TWT link replacement element. Table 2 shows an example of a probe response frame body including an R-TWT link replacement element in the last row.

[0135] [Table 2]

[0136]

[0137] In some embodiments, a first STA attached to a non-AP MLD associated with an AP MLD has obtained membership in a first R-TWT schedule on a first link between the AP MLD and the non-AP MLD. The non-AP MLD may receive an R-TWT link replacement element included in a beacon frame or a probe response frame, which indicates that the first R-TWT schedule on the first link is scheduled to be unavailable and a second R-TWT schedule is established on a second link between the AP MLD and the non-AP MLD as a replacement. The non-AP MLD may then send a link replacement confirmation frame to the APMLD on any enabled link between the AP MLD and the non-AP MLD. The link replacement confirmation frame may include an R-TWT link replacement element having the same parameters as the R-TWT link replacement element previously received from the AP MLD. When the non-AP MLD successfully sends the link replacement confirmation frame, the first R-TWT schedule on the first link may be suspended for the first STA at the time indicated in the link replacement time subfield of the R-TWT link replacement element. Starting from the time indicated in the Link Replacement Time subfield of the R-TWT Link Replacement element, the second STA affiliated with the non-AP MLD may become a member of the second R-TWT schedule on the second link.

[0138] In some embodiments, when a first R-TWT schedule becomes unavailable due to unavailability of a TID-to-link mapping advertised by a first link, when the link is reenabled, starting from the first R-TWT SP after the reenabled time of the first link, the first R-TWT schedule is reestablished on the first link and the second R-TWT schedule is deleted on the second link.

[0139] Table 3 below shows an example of protected EHT (Extreme High Throughput) Action field values. In this example, the Link Replacement Confirmation frame has a value of 8 in Table 3. Other values ​​of the Link Replacement Confirmation frame are also possible.

[0140] [Table 3]

[0141]

[0142] Table 4 shows an example of an element ID of an R-TWT link replacement element applicable to the IEEE 802.11be standard and any future revisions to the IEEE 802.11 standard.

[0143] [Table 4]

[0144]

[0145] Table 5 below shows an example of a link replacement confirmation frame format, which may be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard. The category field may have a specific value to indicate a protected EHT action frame. The protected EHT action field may have a value for indicating a link replacement confirmation. For example, the protected EHT action field has a value of 8 in Table 3. The dialogue token field is set to a non-zero value selected by the STA sending the link replacement confirmation frame. The link replacement confirmation frame may have the same parameters as the R-TWT link replacement element received from the AP MLD.

[0146] [Table 5]

[0147]

[0148] In some embodiments, a first TID set (S1) may be mapped on a first link, and a second TID set (S2) may be mapped on a second link. A first R-TWT schedule for a first R-TWT TID set (R1) may be established on the first link. The AP MLD may then decide to remove the first R-TWT schedule from the first link, and instead, may intend to establish a second R-TWT schedule on the second link. The second R-TWT TID set (R2) may be applicable to a second R-TWT schedule on the second link. The second R-TWT TID set (R2) may be the intersection of R1 and S2, expressed as R2=(R1∩S2). In other words, the second set of R-TWT TIDs on the second link may include common TID values ​​for the two sets (R1 and S2). For example, if S2={TID3, TID4, TID7} and R1={TID4, TID5, TID7}, then R2={TID4, TID7}. In some embodiments, the second R-TWT TID set (R2) may be the same as the first R-TWT TID set (R1), i.e., R2=R1. This would be applicable if the first set of R-TWT TIDs (R1) is not a subset of the second set of TIDs (S2). In an embodiment, when the first R-TWT TID set (R1) is not a subset of the second set of TIDs (S2), the new second set of TIDs (S2) new ) will be created as the union of sets R1 and S2, denoted as S2 new =R1∪S2. In some embodiments, upon receiving the R-TWT link replacement element from the AP MLD, the STA affiliated with the non-AP MLD may send a link replacement confirmation frame including information about the TID mapped on the second link. In an embodiment, the AP MLD may initiate a new TID to link mapping to map all R-TWT TIDs corresponding to the set R1 on the second link before establishing a second R-TWT schedule on the second link.

[0149] In some embodiments, the AP MLD may initiate the R-TWT link replacement process for various purposes. That is, the R-TWT link replacement may occur due to reasons other than link unavailability or link deletion.

[0150] In some embodiments, a first R-TWT schedule for a first R-TWT TID set (R1) may be established on a first link. When the AP MLD decides to remove the first R-TWT schedule on the first link and establish a second R-TWT schedule on the second link as a replacement, any AP attached to the AP MLD may include a corresponding R-TWT link replacement element in a beacon frame or a probe response frame. That is, each AP attached to the AP MLD may announce information related to link replacement via its corresponding link. For example, a first AP of the AP MLD may include its R-TWT link replacement element in a beacon frame or a probe response frame sent on the first link, and a second AP of the AP MLD may include its R-TWT link replacement element in a beacon frame or a probe response frame sent on the second link.

[0151] The R-TWT link replacement process described above in this disclosure can be generalized to be applicable to any broadcast TWT schedule.

[0152] Fig.11 An example of a broadcast TWT link replacement element format according to an embodiment is shown. This example can be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard.

[0153] The broadcast TWT link replacement element 1100 may include an element ID field, a length field, an element ID extension field, and a link replacement information field. The element ID field and the element ID extension field may include information for identifying the broadcast TWT link replacement element. The length field may indicate the length of the broadcast TWT link replacement element. The link replacement information field may include a from broadcast TWT ID subfield, a to broadcast TWT ID subfield, a link replacement time subfield, a minimum TWT wake-up duration subfield, a from link ID subfield, a to link ID subfield, and a reserved subfield.

[0154] The broadcast TWT ID from subfield may indicate a broadcast TWT ID of a broadcast TWT schedule on a link (e.g., a first link) indicated by the link ID from subfield, and the broadcast TWT schedule may be moved from the link (e.g., the first link) to a different link (e.g., the second link) using a broadcast TWT link replacement element.

[0155] The To Broadcast TWT ID subfield may indicate a broadcast TWT ID of a broadcast TWT schedule on a link (eg, a second link) indicated by the To Link ID subfield, to which the broadcast TWT schedule is moved using a broadcast TWT link replacement element.

[0156] The Link Replacement Time subfield may include a positive unsigned integer corresponding to the TSF time at which the broadcast TWT schedule identified by the Broadcast TWT ID subfield is moved from one link (e.g., the first link) to another link (e.g., the second link) between the APMLD and the non-AP MLD. The TSF time indicated in the Link Replacement Time subfield may be with respect to the TSF of the link from which the broadcast TWT schedule is moved.

[0157] The Minimum TWT Wake-up Duration subfield may indicate the minimum amount of time that a TWT-scheduled STA is expected to wake up during a TWT wake-up interval period corresponding to a replacement R-TWT schedule on the link to which the R-TWT schedule is moved. The units of the Minimum TWT Wake-up Duration subfield value of the Broadcast TWT Link Replacement element may be the same as the units of the value of the Nominal Minimum TWT Wake-up Duration subfield of the original Broadcast TWT schedule on the link indicated in the Link ID subfield of the Link Replacement Information field.

[0158] The From Link ID subfield may indicate a link (eg, a first link) from which the broadcast TWT schedule of the AP MLD is moved to another link (eg, a second link).

[0159] The To Link ID subfield may indicate a link (eg, a second link) of the AP MLD to which the broadcast TWT schedule is moved.

[0160] Table 6 shows an example of an element ID for a broadcast TWT link replacement element.

[0161] [Table 6]

[0162]

[0163] Table 7 shows an example of a beacon frame body including a broadcast TWT link replacement element.

[0164] [Table 7]

[0165]

[0166] Table 8 shows an example of a probe response frame body including a broadcast TWT link replacement element.

[0167] [Table 8]

[0168]

[0169] Table 9 below shows examples of protected EHT Action field values.

[0170] [Table 9]

[0171]

[0172] Table 10 shows an example of the link replacement confirmation frame format. The category field may have a specific value to indicate a protected EHT action frame. The protected EHT action field may have a value used to indicate a link replacement confirmation. For example, the protected EHT action field has a value of 10 in Table 9. The dialogue token field is set to a non-zero value selected by the STA sending the link replacement confirmation frame. The link replacement confirmation frame may have the same parameters as the broadcast TWT link replacement element received from the AP MLD.

[0173] [Table 10]

[0174]

[0175] In some embodiments, a first broadcast TWT schedule may be established on a first link between an AP MLD and one or more non-AP MLDs, and the first link may be about to become unavailable. In this case, the AP MLD may announce that the first broadcast TWT schedule on the first link becomes unavailable by including a broadcast TWT link replacement element in a beacon frame or a probe response frame, and as a replacement, a second broadcast TWT schedule is available to members on the second broadcast TWT schedule on the second link from the time indicated in the link replacement time subfield of the broadcast TWT link replacement element. The AP MLD may notify the associated non-AP MLDs of one or more broadcast TWT link replacement elements via all or part of the enabled links. The second broadcast TWT schedule may be an existing schedule on the second link or a schedule newly created on the second link by an AP attached to the AP MLD.

[0176] In some embodiments, a first STA attached to a non-AP MLD associated with an AP MLD has obtained membership in a first broadcast TWT schedule on a first link between the AP MLD and the non-AP MLD. The non-AP MLD may receive a broadcast TWT link replacement element included in a beacon frame or a probe response frame, which indicates that the first broadcast TWT schedule on the first link is scheduled to be unavailable, and as a replacement, the second broadcast TWT schedule is available on the second link. Then, the non-AP MLD may send a link replacement confirmation frame to the AP MLD on any enabled link between the AP MLD and the non-AP MLD. The link replacement confirmation frame may include a broadcast TWT link replacement element having the same parameters as the broadcast TWT link replacement element received from the AP MLD. When the non-AP MLD successfully sends the link replacement confirmation frame, the first broadcast TWT schedule on the first link may be deleted for the first STA attached to the non-AP MLD at the time indicated in the link replacement time subfield of the broadcast TWT link replacement element. Then, starting from the time indicated in the link replacement time subfield, the second STA attached to the non-AP MLD becomes a member of the second broadcast TWT schedule on the second link. The first link and the second link can be identified by the From Link ID subfield and the To Link ID subfield of the Broadcast TWT Link Replacement element, respectively. The Broadcast TWT ID subfields corresponding to the broadcast TWT schedules on the first link and the second link are identified by the From Broadcast TWT ID subfield and the To Broadcast TWT ID subfield of the Broadcast TWT Link Replacement element, respectively. The minimum wake-up duration of the second broadcast TWT schedule on the second link can be indicated by the Minimum TWT Wake-up Duration subfield of the Broadcast TWT Link Replacement element.

[0177] In some embodiments, if a first R-TWT schedule established on a first link between an AP MLD and a non-AP MLD is replaced by a second R-TWT schedule available on a second link between the AP MLD and the non-AP MLD using a broadcast TWT link replacement element, the R-TWT TIDs for uplink and downlink corresponding to the second R-TWT schedule on the second link can be derived by taking the intersection of two sets (set-1 and set-2). Wherein set-1 represents the R-TWT TID corresponding to the first R-TWT schedule on the first link, and set-2 represents the TID mapped on the second link using the TIDs for uplink and downlink to the link, respectively. Other parameters of the second R-TWT schedule on the second link can remain the same as the TWT parameters of the first R-TWT schedule on the first link.

[0178] Fig.12An example of a link replacement process 1200 performed by an AP MLD according to an embodiment is shown.

[0179] In operation 1201, a first AP affiliated with an AP MLD establishes a first broadcast TWT schedule on a first link with a first STA affiliated with one or more non-AP MLDs. When the first link is scheduled or is about to be unavailable for some reason, process 1200 proceeds to operation 1203.

[0180] In operation 1203, when the first link is scheduled or is about to be unavailable, the AP MLD may announce a broadcast TWT link replacement to the associated non-AP MLDs in its BSS by announcing that the first broadcast TWT schedule on the first link becomes unavailable and a replacement broadcast TWT schedule is available on the replacement link. The necessary information for the broadcast TWT link replacement may be included in a broadcast TWT link replacement element in a beacon frame or a probe response frame. The broadcast TWT link replacement element includes the time when the first broadcast TWT schedule is unavailable and the replacement broadcast TWT schedule becomes available. The AP MLD may announce a broadcast TWT link replacement on all or part of the enabled links with the associated non-AP MLDs.

[0181] In operation 1205, the AP MLD receives a confirmation frame from one or more non-AP MLDs. The confirmation frame may be a link replacement confirmation frame. The link replacement confirmation frame may include a broadcast TWT link replacement element having the same parameters as the broadcast TWT link replacement element sent by the AP MLD. Then, process 1200 proceeds to operation 1207.

[0182] In operation 1207, the AP MLD makes the first broadcast TWT schedule on the first link unavailable from the time indicated by the broadcast TWT link replacement element. At the same time, the AP MLD makes one or more replacement broadcast TWT schedules on one or more replacement links available from the time indicated by the broadcast TWT link replacement element. Therefore, one or more second STAs of the associated non-AP MLD become members of the one or more replacement broadcast TWT schedules on the one or more replacement links.

[0183] Fig.13 An example of a link replacement process 1300 performed by a non-AP MLD according to an embodiment is shown.

[0184] In operation 1301, a first STA affiliated with a non-AP MLD establishes membership of a first broadcast TWT schedule on a first link with a first AP affiliated with an associated AP MLD. Thus, the first broadcast TWT schedule is established on the first link.

[0185] In operation 1303, the non-AP MLD receives a notification about a broadcast TWT link replacement in a beacon frame or a probe response frame sent from the AP MLD. The announcement notifies that the first broadcast TWT schedule on the first link becomes unavailable and a replacement broadcast TWT schedule becomes available on an alternative link. The necessary information for broadcast TWT link replacement may be included in a broadcast TWT link replacement element in a beacon frame or a probe response frame. The broadcast TWT link replacement element includes the time when the first broadcast TWT schedule becomes unavailable and the replacement broadcast TWT schedule becomes available. The broadcast TWT link replacement element may be received by all or part of the enabled links between the non-AP MLD and the associated AP MLD. Then, process 1300 proceeds to operation 1305.

[0186] In operation 1305, in response to receiving the announcement, the non-AP MLD sends a confirmation frame to the AP MLD via any enabled link between the non-AP MLD and the AP MLD. The confirmation frame can be a link replacement confirmation frame. The link replacement confirmation frame can include a broadcast TWT link replacement element having the same parameters as the broadcast TWT link replacement element sent by the AP MLD. Then, process 1300 proceeds to operation 1307.

[0187] In operation 1307, when the non-AP MLD successfully sends an acknowledgment to the AP MLD, the first broadcast TWT schedule on the first link is deleted starting from the time indicated by the broadcast TWT link replacement element, and the second STA attached to the non-AP MLD becomes a member of the replacement broadcast TWT schedule on the replacement link.

[0188] In some embodiments, multiple TWT schedules can be established on multiple links between an AP MLD and a non-AP MLD, and multiple TWT SPs on multiple links can overlap or align with each other. In these cases, a first AP attached to an AP MLD can perform part of a PPDU transmission to a first STA attached to a non-AP MLD during a TWT SP on the first link, and can then end the PPDU transmission on the first link. Subsequently, a second AP attached to the same AP MLD can perform the rest of the PPDU transmission on the second link during an overlapping TWT SP established on the second link. Therefore, part of the PPDU transmission occurs on the first link, and the rest of the PPDU transmission occurs on the second link. That is, the TWT link switching from the first link to the second link can occur when a PPDU is sent on two links during a TWT SP. TWT link switching can be useful for devices operating in EMLSR (Enhanced Multi-Link Single Radio), EMLMR (Enhanced Multi-Link Multi-Radio), or NSTR (Non-Simultaneous Transmit and Receive) operating modes.

[0189] Similarly, when multiple TWT schedules are established on multiple links between an AP MLD and a non-AP MLD and multiple TWT SPs on the multiple links overlap or align with each other, a first STA attached to the non-AP MLD can perform part of the PPDU transmission to the first AP attached to the AP MLD during the TWTSP on the first link, and can then end the PPDU transmission on the first link. Subsequently, a second STA attached to the same non-AP MLD can perform the remaining part of the PPDU transmission on the second link during the overlapping TWT SP established on the second link. Therefore, part of the PPDU transmission occurs on the first link, and the rest of the PPDU transmission occurs on the second link. That is, TWT link switching from the first link to the second link can occur when a PPDU is sent on both links during the TWT SP. TWT link switching can be useful for devices operating in EMLSR, EMLMR, or NSTR operating modes.

[0190] In some embodiments, before switching a link from a first link to a second link during a TWT SP, the AP or STA may send a frame including a link switch indicator (LSI) on the first link where the frame exchange occurs. The LSI may indicate the switching link for sending the remainder of the PPDU on other TWT SPs on the second link, which overlap with the TWT SP on the first link.

[0191] Fig.14a and Fig.14b 14 shows an example of wireless communication according to an embodiment. These examples may be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard. The AP MLD 1410 and the non-AP MLD 1420 may be respectively Figure 3 14. An example of an AP MLD 310 and a non-AP MLD 320 is shown in FIG. The AP MLD 1410 may include three subordinate APs (AP 1, AP 2, and AP 3), and the non-AP MLD 1420 may include three subordinate STAs (STA 1, STA 2, and STA 3). AP 1 and STA 1 may operate on link 1 (a first link), AP 2 and STA 2 may operate on link 2 (a second link), and AP 3 and STA 3 may operate on link 3 (a third link). Link 1, link 2, and link 3 may use a 2.4 GHz band, a 5 GHz band, and a 6 GHz band, respectively.

[0192] Fig.14aAn example of TWT link switching during a TWT SP according to an embodiment is shown. Two TWT schedules may be established on link 1 and link 3, and the two TWT SPs established on link 1 and link 3 may overlap or align with each other. In this example, AP 1 of AP MLD 1410 performs frame exchange in TWT SP (Schedule-A) on link 1. For example, AP 1 sends a PPDU to STA 1 of non-AP MLD 1420 and receives an ACK frame from STA 1. Then, AP 1 ends PPDU transmission in the middle of the TWT SP on link 1. Afterwards, AP 3 resumes PPDU transmission on link 3 within the TWT SP on link 3. More specifically, AP3 sends the remaining PPDU to STA 3 and receives an ACK frame from STA 3. In the Figure 3 In the example, the TWT scheduling on link 3 can be an alternative TWT scheduling to the TWT scheduling on link 1 (Schedule-A).

[0193] Fig.14b Another example of TWT link switching during TWT SP according to an embodiment is shown. Fig.14b , AP 1 of AP MLD 1410 may transmit a frame including a link switch indicator (LSI) before switching a link from link 1 to link 3 during a TWT SP. More specifically, AP 1 of AP MLD 1410 transmits a PPDU to STA 1 of non-AP MLD 1420 and receives an ACK frame from STA 1. Then, AP 1 transmits a link switch indicator (LSI) indicating that the TWT link is switched from link 1 to link 3 at the TWT SP to STA 1. Then, AP 3 of AP MLD 1410 transmits the remaining PPDU to STA 3 and receives an ACK frame from STA 3.

[0194] Unless otherwise specified, references to singular elements are not intended to mean one and only one, but rather one or more. For example, "a" module may refer to one or more modules. Without further limitation, an element preceded by "a", "an", "the" or "said" does not exclude the presence of additional identical elements.

[0195] Headings and subheadings, if any, are used for convenience only and do not limit the invention. The word "exemplary" is used to mean serving as an example or illustration. To the extent that the terms "including," "having," and the like are used, such terms are intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when used as a transitional word in the claims. Relational terms such as first and second, and the like may be used to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

[0196] Phrases such as aspect, this aspect, another aspect, some aspects, one or more aspects, implementation, this implementation, another implementation, some implementations, one or more implementations, embodiment, this embodiment, another embodiment, some embodiments, one or more embodiments, configuration, this configuration, another configuration, some configurations, one or more configurations, subject technology, the present disclosure, the present disclosure, other variations thereof, etc. are for convenience and do not imply that the disclosure associated with such phrases is essential to the subject technology or that such disclosure applies to all configurations of the subject technology. The disclosure associated with such phrases may apply to all configurations or one or more configurations. The disclosure associated with such phrases may provide one or more examples. Phrases such as aspect or some aspects may refer to one or more aspects and vice versa, and this applies similarly to the other aforementioned phrases.

[0197] The phrase "at least one of," preceding a list of items, where the terms "and" or "or" are used to separate any one of the items, modifies the list as a whole, rather than each member of the list. The phrase "at least one of" does not require selection of at least one of the items; rather, the phrase allows for a meaning that includes at least one of any one item and / or at least one of any combination of items and / or at least one of each item. 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.

[0198] It should be understood that the specific order or hierarchy of steps, operations or processes disclosed is an illustration of an exemplary method. Unless otherwise explicitly stated, it should be understood that the specific order or hierarchy of steps, operations or processes can be performed in a different order. Some of the steps, operations or processes can be performed simultaneously or as part of one or more other steps, operations or processes. The attached method claims (if any) present the elements of various steps, operations or processes in a sample order and are not meant to be limited to the specific order or hierarchy presented. These can be performed serially, linearly, in parallel or in different orders. It should be understood that the instructions, operations and systems described can generally be integrated together in a single software / hardware product or packaged into multiple software / hardware products.

[0199] The present disclosure is provided to enable any person skilled in the art to practice the various aspects described herein. In some instances, known structures and components are shown in block diagram form to avoid blurring the concept of the subject technology. The present disclosure provides various examples of the subject technology, and the subject technology is not limited to these examples. It will be apparent to those skilled in the art that various modifications to these aspects will be apparent, and the principles described herein can be applied to other aspects.

[0200] 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 one 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 dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element should be excluded under 35 USC 112, paragraph 6, unless the element is explicitly recited using the phrase “means for” or, in the case of a method claim, the phrase “step for” is used to recite the element.

[0201] The title, background technology, figure description, abstract, and drawings are incorporated into the present disclosure and are provided as illustrative examples of the present disclosure rather than as limiting descriptions. It should be understood that the submitted abstract will not be used to limit the scope or meaning of the claims. In addition, in the specific implementation, it can be seen that the description provides illustrative examples, and various features are grouped together in various implementations for the purpose of simplifying the present disclosure. The method of the present disclosure should not be interpreted as reflecting the intention that the claimed subject matter requires more features than the features explicitly stated in each claim. On the contrary, as reflected in the following claims, the inventive subject matter lies in less than all the features of a single disclosed configuration or operation. The attached claims are incorporated into the specific implementation, wherein each claim itself is a subject matter claimed separately.

[0202] The claims are not intended to be limited to the aspects described herein, but are to be given the full scope consistent with the language of the claims and to encompass all legal equivalents. Nevertheless, the claims are not intended to encompass subject matter that does not satisfy applicable patent law requirements, nor should they be interpreted in such a manner.

Claims

1. An AP multi-link device (MLD) associated with a non-access point (AP) MLD in a wireless network, the AP MLD comprising: At least two APs, each AP is attached to an AP MLD; as well as A processor is coupled to the at least two APs, the processor being configured to: establishing a first broadcast target wake time (TWT) schedule on a first link between a first AP attached to the AP MLD and a first station (STA) attached to the non-AP MLD; Sending TWT link replacement information to the non-AP MLD via at least one link between the AP MLD and the non-AP MLD, the TWT link replacement information indicating that a first broadcast TWT schedule on a first link is replaced by a second broadcast TWT schedule on a second link between a second AP attached to the AP MLD and a second STA attached to the non-AP MLD; receiving a link replacement confirmation from the non-AP MLD via a link between the AP MLD and the non-AP MLD; as well as Move a first broadcast TWT schedule on a first link to a second broadcast TWT schedule on a second link.

2. The AP MLD according to claim 1, wherein: The processor is configured to move a first broadcast TWT schedule on a first link to a second broadcast TWT schedule on a second link at a time indicated in the TWT link replacement information.

3. The AP MLD according to claim 1 or claim 2, wherein: At the time indicated in the TWT link replacement information, the first broadcast TWT schedule on the first link becomes unavailable and the second broadcast TWT schedule on the second link becomes available.

4. The AP MLD according to any one of the preceding claims, wherein: The TWT link replacement information is included in a beacon frame or a probe response frame.

5. The AP MLD according to any one of the preceding claims, wherein: The link replacement confirmation includes the same information as the TWT link replacement information sent by the AP MLD.

6. A non-AP MLD associated with an access point (AP) multi-link device (MLD) in a wireless network, the non-AP MLD comprising: At least two stations (STAs), each STA is attached to a non-AP MLD; as well as A processor, coupled to the at least two STAs, the processor being configured to: establishing membership of a first broadcast target wake time (TWT) schedule on a first link between a first STA attached to the non-AP MLD and a first AP attached to the AP MLD; receiving TWT link replacement information from the AP MLD via at least one link between the non-AP MLD and the AP MLD, the TWT link replacement information indicating that a first broadcast TWT schedule on a first link is replaced by a second broadcast TWT schedule on a second link between a second STA attached to the non-AP MLD and a second AP attached to the APMLD; as well as In response to receiving the TWT link replacement information, a link replacement confirmation is sent to the AP MLD via a link between the non-AP MLD and the AP MLD.

7. The non-AP MLD according to claim 6, wherein: At the time indicated in the TWT link replacement information, the first broadcast TWT schedule on the first link is moved to the second broadcast TWT schedule on the second link.

8. The non-AP MLD according to claim 6 or claim 7, wherein: At the time indicated in the TWT link replacement information, the first broadcast TWT schedule on the first link becomes unavailable and the second broadcast TWT schedule on the second link becomes available.

9. The non-AP MLD according to any one of claims 6 to 8, wherein: The TWT link replacement information is included in a beacon frame or a probe response frame.

10. The non-AP MLD according to any one of claims 6 to 9, wherein: The link replacement confirmation includes the same information as the TWT link replacement information received from the AP MLD.

11. The non-AP MLD according to any one of claims 6 to 10, wherein: The TWT link replacement information includes an identifier of the first broadcast TWT schedule and an identifier of the second broadcast TWT schedule.

12. The non-AP MLD according to any one of claims 6 to 11, wherein: The TWT link replacement information includes the minimum amount of time that the second STA is expected to wake up on the second link for the TWT wake-up interval period.

13. The non-AP MLD according to any one of claims 6 to 12, wherein: The TWT link replacement information includes an identifier of the first link and an identifier of the second link.

14. The non-AP MLD according to any one of claims 6 to 13, wherein: The first broadcast TWT schedule is a first restricted TWT (R-TWT) schedule, and the second broadcast TWT schedule is a second R-TWT schedule, and One or more R-TWT traffic identifiers (TIDs) for a second R-TWT schedule on a second link are derived using an intersection of a first TID set and a second TID set, wherein the first TID set is one or more R-TWT TIDs of the first R-TWT schedule and the second TID set is one or more TIDs mapped on the second link using a TID to link mapping.

15. The non-AP MLD according to any one of claims 6 to 14, wherein: The TWT parameters of the second R-TWT scheduling that are not included in the TWT link replacement information are the same as the TWT parameters of the first R-TWT scheduling.

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