Aligned target wake-up time operations in wireless communication systems

Abstract

A wireless communication network includes an access point (AP) multilink device (MLD) and a non-AP MLD. A target wakeup time (TWT) scheduling AP associated with an AP MLD transmits a broadcast frame announcing broadcast TWT scheduling to a TWT scheduled station (STA) associated with a non-AP MLD. The broadcast frame indicates whether there is a schedule aligned with the TWT schedule on other links. When the TWT scheduled STA is interested in joining the alignment scheduling, it sends a request to join the alignment scheduling on the link.

Description

Technical Field

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

[0002] Wireless local area network (WLAN) technology has evolved toward increased data rates and has continued to grow in various markets such as home, enterprise, and hotspots in the years since the late 1990s. WLAN allows devices to access the Internet in the 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz frequency bands. WLAN is based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards. The IEEE 802.11 family of standards is designed to increase speed 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 unmanned 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] Technical Solution

[0007] One embodiment of the present disclosure may provide an AP MLD associated with a non-AP multi-link device (MLD) in a wireless network. The AP MLD may include at least two APs and a processor coupled to the at least two APs. The processor is configured to send a first broadcast frame announcing a first TWT schedule to a first STA on a first link between the first AP and the first STA attached to the non-AP MLD by a first AP attached to the AP MLD, the first broadcast frame indicating whether the first TWT schedule is an aligned schedule. The processor is configured to receive a first request to join the first TWT schedule from the first STA on the first link by the first AP. The processor is configured to establish a first TWT schedule on the first link by the first AP, the first TWT schedule being aligned with a second TWT schedule established on a second link between a second AP attached to the AP MLD and a second STA attached to the non-AP MLD.

[0008] In some embodiments, the first broadcast frame includes a TWT element including an alignment subfield indicating whether alignment scheduling is available on more than one link of the APMLD.

[0009] In some embodiments, when the alignment subfield is set to a first value, the alignment subfield indicates that there is a schedule on the other link that is aligned with the first TWT schedule on the first link within a predetermined interval.

[0010] In some embodiments, when the alignment subfield is set to a second value, the alignment subfield indicates that there is no schedule on the other link that is aligned with the first TWT schedule on the first link within a predetermined interval.

[0011] In some embodiments, the alignment subfield is retained when the negotiation type subfield of the control field of the TWT element indicates that the first AP manages membership in the TWT schedule by including the TWT element in individually addressed management frames.

[0012] In some embodiments, the aligned schedule is a broadcast TWT schedule available across multiple links, and the target wake-up times of the broadcast TWT schedules on the multiple links are aligned.

[0013] In some embodiments, the TWT parameters of the aligned TWT scheduling on multiple links are identical to each other.

[0014] In some embodiments, the processor is configured to send a second broadcast frame announcing a second TWT schedule to the second STA by the second AP on the second link. The processor is configured to receive a second request to join the second TWT schedule from the second STA on the second link by the second AP, and the second TWT schedule is aligned with the first TWT schedule established on the first link. The processor is configured to establish a second TWT schedule on the second link by the second AP.

[0015] In some embodiments, the processor is configured to send a third broadcast frame announcing a third TWT schedule from a third STA on a third link between the third AP and a third STA attached to a non-AP MLD by a third AP attached to the AP MLD. The processor is configured to receive a third request to join a third TWT schedule from a third STA on the third link by the third AP, the third TWT schedule being aligned with the first TWT schedule established on the first link. The processor is configured to establish a third TWT schedule on the third link by the third AP.

[0016] One embodiment of the present disclosure may provide a non-access point (AP) multi-link device (MLD) associated with an AP MLD in a wireless network. The non-AP MLD may include at least two stations (STAs) and a processor coupled to the at least two STAs. The processor is configured to receive, by a first STA attached to the non-AP MLD, a first broadcast frame announcing a first TWT schedule from a first AP on a first link between the first STA and a first AP attached to the AP MLD, the first broadcast frame indicating whether the first TWT schedule is an aligned schedule. The processor is configured to send, by the first STA, a first request to join the first TWT schedule to the first AP on the first link. The processor is configured to join the first TWT schedule established on the first link, the first TWT schedule being aligned with a second TWT schedule established on a second link between a second STA attached to the non-AP MLD and a second AP attached to the AP MLD.

[0017] In some embodiments, the first broadcast frame includes a TWT element including an alignment subfield indicating whether alignment scheduling is available on more than one link of the APMLD.

[0018] In some embodiments, when the alignment subfield is set to a first value, the alignment subfield indicates that there is a schedule on the other link that is aligned with the first TWT schedule on the first link within a predetermined interval.

[0019] In some embodiments, when the alignment subfield is set to a second value, the alignment subfield indicates that there is no schedule on the other link that is aligned with the first TWT schedule on the first link within a predetermined interval.

[0020] In some embodiments, the alignment subfield is retained when the negotiation type subfield of the control field of the TWT element indicates that the first AP manages membership in the TWT schedule by including the TWT element in individually addressed management frames.

[0021] In some embodiments, the aligned schedule is a broadcast TWT schedule available across multiple links, and the target wake-up times of the broadcast TWT schedules on the multiple links are aligned.

[0022] In some embodiments, the TWT parameters of the aligned TWT scheduling on multiple links are identical to each other.

[0023] In some embodiments, the processor is configured to receive, by the second STA, a second broadcast frame announcing a second TWT schedule from the second AP on the second link. The processor is configured to determine, by the second STA based on the TWT parameters of the second TWT schedule, that the second TWT schedule is an aligned schedule aligned with the first TWT schedule. The processor is configured to send, by the second STA, a second request to join the second TWT schedule to the second AP on the second link. The processor is configured to join the second TWT schedule established on the second link, and the second TWT schedule is aligned with the first TWT schedule established on the first link.

[0024] In some embodiments, the processor is configured to receive, by a third STA attached to a non-AP MLD, a third broadcast frame announcing a third TWT schedule from a third AP on a third link between the third STA and a third AP attached to an AP MLD. The processor is configured to determine, by the third STA based on a TWT parameter of the third TWT schedule, that the third TWT schedule is an aligned schedule aligned with the first TWT schedule. The processor is configured to send, by the third STA, a third request to join the third TWT schedule to the third AP on the second link. The processor is configured to join the third TWT schedule established on the third link, and the third TWT schedule is aligned with the first TWT schedule established on the first link.

[0025] One embodiment of the present disclosure may provide a computer-implemented method for facilitating wireless communications. The method may include receiving, by a first station (STA) attached to a non-access point (AP) multi-link device (MLD), a broadcast frame announcing a broadcast TWT schedule from a first AP on a link between the first AP and a first AP attached to an AP MLD associated with the non-AP MLD, the broadcast frame indicating whether the broadcast TWT schedule is an aligned schedule. The method may include: when the first STA is interested in joining the broadcast TWT schedule, the first STA sends a request to join the broadcast TWT schedule to the first AP on the link. The method may include joining a broadcast TWT schedule established on the link, the broadcast TWT schedule being aligned with another broadcast TWT schedule established on other links between the non-AP MLD and the AP MLD.

[0026] In some embodiments, the broadcast frame includes a TWT element including an alignment subfield indicating whether alignment scheduling is available on more than one link of the AP MLD. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 shows an example of a wireless network according to an embodiment.

[0028] FIG. 2A shows an example of an AP according to an embodiment.

[0029] FIG. 2B shows an example of a STA according to an embodiment.

[0030] FIG. 3 shows an example of multi-link operation according to an embodiment.

[0031] FIG4 shows an example of aligned TWT scheduling according to an embodiment.

[0032] FIG. 5 shows an example of a TWT element according to an embodiment.

[0033] FIG. 6A shows an example of aligning TWT information elements according to an embodiment.

[0034] FIG. 6B shows an example of aligning the control fields of TWT information elements according to an embodiment.

[0035] FIG6C shows another example of aligning the control fields of TWT information elements according to an embodiment.

[0036] FIG. 6D shows an example of an Aligned TWT Parameter Set field included in an Aligned TWT Information Element.

[0037] FIG. 6E shows another example of an Aligned TWT Parameter Set field included in an Aligned TWT Information Element.

[0038] FIG. 6F shows another example of an Aligned TWT Parameter Set field included in an Aligned TWT Information Element.

[0039] FIG. 7 shows another example of aligning TWT information elements according to an embodiment.

[0040] FIG. 8 shows another example of aligning TWT information elements according to an embodiment.

[0041] FIG9 shows a flow chart illustrating an example process of an AP MLD supporting aligned TWT operations according to an embodiment.

[0042] FIG. 10 shows a flow chart illustrating an example process of a non-AP MLD supporting aligned TWT operations according to an embodiment.

[0043] In one or more embodiments, not all components depicted in each figure are 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 subject disclosure. Additional components, different components, or fewer components may be utilized within the scope of the present subject disclosure. DETAILED DESCRIPTION

[0044] 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 embodiments in which the subject technology can be practiced. On the contrary, for the purpose of providing a thorough understanding of the subject of the present invention, the specific embodiments include specific details. As will be appreciated by those skilled in the art, the described implementations 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.

[0045] 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 sending and receiving radio frequency (RF) signals in accordance with the IEEE 802.11 standard, the Bluetooth standard, Global System for Mobile Communications (GSM), GSM / General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio (TETRA), Wideband CDMA (W-CDMA), Evolution-Data Optimized (EV-DO), 1xEV-DO, EV-DO Rev A, EV-DO Rev B, High Speed ​​Packet Access (HSPA), High Speed ​​Downlink Packet Access (HSDPA), High Speed ​​Uplink Packet Access (HSUPA), Evolved High Speed ​​Packet Access (HSPA+), Long Term Evolution (LTE), 5G NR (New Radio), AMPS, or other known signals for communicating within a wireless, cellular or Internet of Things (IoT) network, such as systems utilizing 3G, 4G, 5G, 6G or further implementations thereof.

[0046] 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 contends 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 equipment that wirelessly accesses an AP or contends 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.).

[0047] Multi-link operation (MLO) is a key feature currently being developed by the standards bodies for the next generation Extremely High Throughput (EHT) Wi-Fi system in IEEE 802.11be. Wi-Fi devices that support MLO are called Multi-link Devices (MLDs). With MLO, non-AP MLDs can discover, authenticate, associate with, and establish multiple links with AP MLDs. Channel access and frame exchange can occur on each link between AP MLDs and non-AP MLDs.

[0048] FIG1 shows an example of a wireless network 100 according to an embodiment. The embodiment of the wireless network 100 shown in FIG1 is for illustration purposes only. Other embodiments of the wireless network 100 may be used without departing from the scope of the present disclosure.

[0049] As shown in FIG. 1 , a 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 as an access point (AP) STA and a non-access point (non-AP) STA. An AP STA may be an entity that provides access to a distribution system service for an associated STA 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 the example of FIG. 1 , 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.

[0050] 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.

[0051] 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 contends 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 equipment that wirelessly accesses an AP or contends 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.).

[0052] 1, dashed lines illustrate the approximate extents of 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 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.

[0053] As described in more detail below, one or more of the APs may include circuitry and / or programming for management of MU-MIMO and OFDMA channel sounding in a WLAN. Although FIG. 1 shows an example of a wireless network 100, various changes may be made to FIG. 1. 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 those STAs with wireless broadband access to the network 130. Similarly, each AP 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.

[0054] FIG2A shows an example of an AP 101 according to an embodiment. The embodiment of the AP 101 shown in FIG2A is for illustrative purposes, and the AP 103 of FIG1 may have the same or similar configuration. However, APs have a wide range of configurations, and FIG2A does not limit the scope of the present disclosure to any particular implementation of the AP.

[0055] As shown in FIG. 2A , 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 frequency (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.

[0056] The TX processing circuit 214 receives analog or digital data (such as voice data, web data, email, or interactive video game data) from the controller / processor 224. The TX processing 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.

[0057] The controller / processor 224 can include one or more processors or other processing devices that control the overall operation of the AP 101. For example, the controller / processor 224 can 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 can also support additional functions, such as more advanced wireless communication functions. For example, the controller / processor 224 can 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 can also support OFDMA operations, in which outgoing signals are assigned to subsets of different subcarriers of different receivers (e.g., different STAs111-114). The controller / processor 224 can 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 is capable of moving data into or out of the memory 229 as required by the execution process.

[0058] 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.

[0059] As described in more detail below, AP 101 may include circuits and / or programming for the management of the channel sounding process in a WLAN. Although FIG. 2A shows an example of AP 101, various changes may be made to FIG. 2A. For example, AP 101 may include any number of each component shown in FIG. 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 the TX processing circuit 214 and a single instance of the RX processing circuit 219, AP 101 may include multiple instances of each (such as one instance per RF transceiver). Alternatively, only one antenna and RF transceiver path may be included, such as in a traditional AP. In addition, the various components in FIG. 2A may be combined, further subdivided, or omitted, and additional components may be added according to specific needs.

[0060] As shown in FIG. 2A , in some embodiments, the AP 101 may be an AP MLD including multiple APs 202a-202n. Each AP 202a-202n is attached to the AP MLD 101 and includes multiple antennas 204a-204n, multiple 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. FIG. 2A shows that each AP 202a-202n has a separate multiple antenna, but each AP 202a-202n may share multiple antennas 204a-204n without separate multiple antennas. Each AP 202a-202n may represent a physical (PHY) layer and a lower medium access control (MAC) layer.

[0061] FIG2B shows an example of STA 111 according to an embodiment. The embodiment of STA 111 shown in FIG2B is for illustrative purposes, and STAs 111-114 of FIG1 may have the same or similar configurations. However, STAs have a variety of configurations, and FIG2B does not limit the scope of the present disclosure to any particular implementation of a STA.

[0062] 2B , STA 111 may include an antenna 205, an RF transceiver 210, a TX processing circuit 215, a microphone 220, and an RX processing circuit 225. STA 111 may also include a speaker 230, a controller / processor 240, an input / output (I / O) interface (IF) 245, a touch screen 250, a display 255, and a memory 260. The memory 260 may include an operating system (OS) 261 and one or more applications 262.

[0063] 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).

[0064] The TX processing circuit 215 receives analog or digital voice data from the microphone 220, or receives other outgoing baseband data (such as web data, email, or interactive video game data) from the controller / processor 240. The TX processing circuit 215 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceiver 210 receives the outgoing processed baseband or IF signal from the TX processing circuit 215 and up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna 205.

[0065] The controller / processor 240 can 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.

[0066] The controller / processor 240 is also capable of executing other processes and programs resident in the memory 260, such as operations for the management of 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.

[0067] The controller / processor 240 is also coupled to an input 250 (e.g., 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).

[0068] Although FIG. 2B shows an example of STA 111, various changes may be made to FIG. 2B. For example, various components in FIG. 2B may be combined, further subdivided, or omitted, and additional components may be added as needed. In a specific example, STA 111 may include any number of antennas 205 for MIMO communication with AP 101. In another example, STA 111 may not include voice communication, or the controller / processor 240 may be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). In addition, although FIG. 2B shows STA 111 configured as a mobile phone or smart phone, the STA may be configured to operate as other types of mobile or fixed devices.

[0069] As shown in FIG2B , 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. FIG2B shows that each STA 203a-203n has a separate antenna, but each STA 203a-203n may share the antenna 205 without a separate antenna. Each STA 203a-203n may represent a physical (PHY) layer and a lower medium access control (MAC) layer.

[0070] FIG3 shows an example of a multi-link communication operation according to an embodiment. The multi-link communication operation can be used in the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard. In FIG3, the AP MLD 310 can be the wireless communication devices 101 and 103 in FIG1, and the non-AP MLD 220 can be one of the wireless communication devices 111-114 in FIG1.

[0071] As shown in FIG. 3 , the AP MLD 310 may include a plurality of subordinate APs, including, for example, AP 1, AP 2, and AP 3. Each subordinate AP may include a PHY interface to a wireless medium (Link 1, Link 2, or Link 3). The AP MLD 310 may include a single MAC Service Access Point (SAP) 318 through which the subordinate APs of the AP MLD 310 communicate with a higher layer (Layer 3 or Network Layer). Each subordinate AP of the AP MLD 310 may have a different MAC address (lower MAC address) from any other subordinate AP of the AP MLD 310. The AP MLD 310 may have an MLD MAC address (higher 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 the AP MLD 310 by assigning a single IP address.

[0072] 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 to a wireless medium (Link 1, Link 2, or Link 3). The non-AP MLD 320 may include a single MAC SAP 328 through which the subordinate STAs of the non-AP MLD 320 communicate with 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 the 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.

[0073] 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.

[0074] Target wake time (TWT) operation is a feature for power management in WLAN networks. TWT operation has been introduced in the IEEE 802.11ah standard and subsequently modified in the IEEE 802.11ax standard. In TWT operation, a STA can wake up only at a pre-scheduled time that has been negotiated with an AP or another STA in a basic service set (BSS). The IEEE 802.11ax standard describes two types of TWT operations: independent TWT operation and broadcast TWT operation. In independent TWT operation, an independent TWT agreement can be established between two STAs or between a STA and an AP. On the other hand, in broadcast TWT operation, an AP can set up a shared TWT session for a group of STAs. The IEEE 802.11be standard describes restricted TWT (R-TWT) operation, which can provide more predictable latency with higher reliability for latency-sensitive services in a timely manner. R-TWT operation is based on broadcast TWT operation. TWT operation is one of the important features to support low-latency applications in next-generation WLAN systems.

[0075] Delay-sensitive traffic can be bursty and periodic. When there is a traffic identifier (TID) associated with the delay-sensitive traffic, the non-AP MLD may preferably map the TID associated with the delay-sensitive traffic to more than one or all established links. For the TID associated with the delay-sensitive traffic, the STA attached to the non-AP MLD can be woken up simultaneously on multiple links, so that the delay-sensitive traffic with the TID can flow on multiple links, thereby increasing the channel access opportunities for the delay-sensitive traffic. In this scenario, the non-AP MLD can benefit from becoming a member of the TWT scheduling aligned across multiple links. However, the broadcast TWT scheduling established across multiple links may not be able to be aligned across multiple links by scheduling the TWT of the AP of the AP MLD attached to it in the current WLAN system. Accordingly, the AP MLD may need to align or synchronize specific TWT scheduling sets across multiple links, and indicate which TWT scheduling is aligned across multiple links during the broadcast TWT announcement phase. However, currently, there is no appropriate mechanism for aligning TWT scheduling or announcing such alignment.

[0076] In some embodiments, the aligned schedule is a broadcast TWT schedule provided by an AP attached to an AP MLD across multiple links, wherein the target wake-up times (TWTs) of the schedules on multiple established links are aligned and the TWT parameters used for the aligned schedules on the multiple links are identical to each other.

[0077] FIG4 shows an example of aligned TWT scheduling according to an embodiment. This example may be applicable to the IEEE 802.11be standard and any future revision of the IEEE 802.11 standard. AP MLD 410 and non-AP MLD 420 may be examples of AP MLD 310 and non-AP MLD 320 shown in FIG3 , respectively. AP MLD 410 may include three subordinate APs (AP 1, AP 2, and AP3), and non-AP MLD 420 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. For example, link 1, link 2, and link 3 may use the 2.4 GHz band, the 5 GHz band, and the 6 GHz band, respectively.

[0078] Referring to Figure 4, a broadcast TWT schedule 1 is established on link 1 between AP 1 and STA 1. Similarly, a broadcast TWT schedule 2 is established on link 2 between AP 2 and STA 2, and a broadcast TWT schedule 3 is established on link 3 between AP 3 and STA 3. In Figure 4, broadcast TWT schedules 1-3 are aligned with each other on their respective links. In some embodiments, the timing synchronization function (TSF) values ​​T1, T2, and T3 on link 1, link 2, and link 3 indicate the start time of the TWT service period (SP) of the broadcast TWT schedules 1-3 on their respective links. As shown in Figure 4, these values ​​can be aligned with each other.

[0079] 4, the AP MLD 410 may establish three broadcast TWT schedules across multiple links, such as Link 1, Link 2, and Link 3. However, since the TWT scheduled STAs attached to the non-AP MLD 420 operate independently on their respective links, the TWT scheduled STAs operating on their respective links may not know which TWT schedules are aligned. Accordingly, if the schedule is marked or indicated as an "aligned" schedule during the advertising or announcement phase, the TWT scheduled STAs attached to the non-AP MLD may gain advantages by joining the aligned schedule across multiple links, thereby enhancing the performance of their delay-sensitive applications.

[0080] In some embodiments, an AP attached to an AP MLD may advertise or announce which TWT schedule is an aligned schedule. For example, an AP of an AP MLD may send a broadcast frame on its corresponding link to indicate whether the corresponding TWT schedule is an aligned schedule. More specifically, an indication of an aligned TWT schedule may be included in a broadcast TWT parameter set field of a broadcast TWT element.

[0081] 5 shows an example of a TWT element 500 according to an embodiment. The TWT element 500 may be applicable to the IEEE 802.11be standard and any future revisions to the IEEE standard. The TWT element 500 may be included in a broadcast frame sent by an AP attached to an AP MLD, such as a beacon frame, an association response frame, a reassociation response frame, or a probe response frame.

[0082] In Figure 5, the TWT element 500 may include a broadcast TWT parameter set field 520, which includes a request type field 540. The request type field 540 may include an alignment subfield 542. The alignment subfield 542 may indicate whether the corresponding TWT scheduling is available on more than one link of the APMLD. For example, if the subfield is set to 1, it may indicate that the scheduling is available on multiple links and the target wake-up times of the scheduling on the multiple links are aligned. Otherwise, the scheduling is not available on more than one link of the AP MLD.

[0083] The details of each field and subfield of the TWT element 500 are further explained below. In Figure 5, the TWT element 500 may include an element identifier (ID) field, a length field, a control field, and a TWT parameter information field. The element ID field may include information for identifying the TWT element 500. The length field may indicate the length of the TWT element 400.

[0084] The control field may include a null data PPDU (physical layer protocol data unit) (NDP) paging indicator subfield, a responder power management (PM) mode subfield, a negotiation type subfield, a TWT information frame disable subfield, a wake-up duration unit subfield, a link ID bitmap presence subfield, and a reserved subfield. The NDP paging indicator subfield may indicate whether an NDP paging field exists in an independent TWT parameter set field. The responder PM mode subfield may indicate a power management mode, such as an active mode and a power saving (PS) mode. The negotiation type subfield may indicate whether the information included in the TWT element is used for negotiation of parameters for a broadcast or independent TWT or wake-up TBTT (target beacon transmission time) interval. The MSB (most significant bit) of the negotiation type subfield is a broadcast field indicating whether one or more broadcast TWT parameter sets are included in the TWT element. The TWT information frame disable subfield may indicate whether the STA disables the reception of TWT information frames. The wake-up duration unit subfield may indicate the unit of the nominal minimum TWT wake-up duration subfield in the broadcast TWT parameter set field 520. The link ID bitmap exists subfield may indicate the presence of the link ID bitmap field in the independent TWT parameter set field.

[0085] The TWT parameter information field of the TWT element 500 may include a single independent TWT parameter set field or one or more broadcast TWT parameter set fields 520. In some embodiments, if the broadcast subfield of the negotiation type subfield in the control field is 0, the TWT parameter information field includes a single independent TWT parameter set field. Otherwise, the TWT parameter information field includes one or more broadcast TWT parameter set fields. Figure 5 describes a broadcast TWT as an example in which the TWT parameter information field may include a broadcast TWT parameter set field 520.

[0086] The broadcast TWT parameter set field 520 may include a request type field, a target wake-up time field, a nominal minimum TWT wake-up duration field, a TWT wake-up interval mantissa field, a broadcast TWT information (information) field, and an optional restricted TWT service information field. The request type field will be explained in further detail below. The target wake-up time field may include an unsigned integer corresponding to the TSF (time synchronization function) time for waking up the TWT scheduled STA. The target wake-up time field may indicate the start time of the TWT service period (SP) on the corresponding link. The nominal minimum TWT wake-up duration field may indicate the minimum amount of time that the TWT scheduled STA is expected to be awakened in order to compete for the frame exchange of the TWT wake-up interval period. The TWT wake-up interval is the average time that the TWT scheduled STA is expected to elapse between consecutive TWT SPs. The TWT wake-up interval mantissa field may indicate the mantissa value of the TWT wake-up interval value.

[0087] The broadcast TWT information field 550 may include a restricted TWT service information presence subfield, a restricted TWT scheduling information subfield, a broadcast TWT ID subfield, and a broadcast TWT persistence subfield. The restricted TWT service information presence subfield may indicate whether the restricted TWT traffic information field exists. The restricted TWT scheduling information subfield may include information about the restricted TWT schedule. The broadcast TWT ID subfield may indicate a specific broadcast TWT for which the sending AP or STA is requesting to participate or for which the sending AP or STA is providing TWT parameters. In some embodiments, the broadcast TWT ID subfield may indicate the broadcast TWT ID of the aligned TWT schedule corresponding to the aligned TWT parameter set field.

[0088] The broadcast TWT persistence subfield may indicate the number of TBTTs during which the broadcast TWT SP corresponding to the broadcast TWT parameter set exists. The restricted TWT service information field may exist when the restricted TWT service information existence subfield of the broadcast TWT information subfield is set to 1. In some embodiments, the restricted TWT service information field may exist when the service is a delay-sensitive service.

[0089] The request type field 540 may include a TWT request subfield, a TWT setup instruction subfield, a trigger subfield, a last broadcast parameter set subfield, a stream type subfield, a broadcast TWT recommendation subfield, a TWT wakeup interval index subfield, and an alignment subfield. The request type field 540 may be used for broadcast TWT operations.

[0090] The TWT request subfield may indicate whether the sending STA is a TWT scheduling AP (or STA) or a TWT scheduled STA (or AP). The TWT setup instruction subfield may indicate the type of TWT instruction, such as requesting TWT, suggesting TWT, requiring TWT, TWT grouping, accepting TWT, replacing TWT, dictating TWT, and rejecting TWT. The trigger subfield may indicate whether the TWT SP indicated by the TWT element includes a trigger frame. The last broadcast parameter set subfield may indicate whether another broadcast TWT parameter set field follows the broadcast TWT parameter set field. The stream type subfield may indicate the type of interaction, for example, an announced TWT or an unannounced TWT at the TWT between the TWT scheduled STA and the TWT scheduling AP. The broadcast TWT recommendation subfield may indicate a recommendation on the frame type sent by the TWT scheduled STA and the TWT scheduling AP during the broadcast TWT SP. For example, the frame type may be a PS poll (Poll) and a QoS empty frame, a management frame, a control response frame, or no constraints on the frame. The TWT wake-up interval index may indicate the value of the index of the TWT wake-up interval value.

[0091] In some embodiments, the Negotiation Type subfield in the Control field may determine the interpretation of the Target Wake Time, TWT Wake Interval Mantissa, and TWT Wake Interval Index subfields of the TWT element, as given in Table 1 below.

[0092]

Table 1

[0093]

[0094] The alignment subfield 542 may indicate whether the corresponding TWT schedule is available on more than one link of the AP MLD. More specifically, if the subfield is set to 1, it may indicate that the schedule is available on multiple links and the target wake-up times of the schedules on the multiple links are aligned. Otherwise, the schedule is not available on more than one link of the AP MLD. In some embodiments, when a schedule is aligned with another schedule within a predetermined interval (e.g., 1 TU (time unit)), those schedules may be designated as aligned schedules. The predetermined interval associated with another schedule may vary depending on various embodiments. For example, it may be a multiple of 1 TU interval or an interval shorter than 1 TU. TU may be a time measurement equal to 1024 μ s. If the negotiation type subfield of the control field in the broadcast TWT element 500 is set to 3 in Table 1 above, the alignment subfield 542 may be retained. For example, when a TWT scheduling AP or a TWT scheduled STA manages membership in a broadcast TWT schedule by including a TWT element in an individually addressed management frame, the alignment subfield 542 may be retained. In an embodiment, if the negotiation type subfield of the control field in the broadcast TWT element is set to 2 in Table 1 above, the alignment subfield 542 may be valid. For example, when the TWT scheduling AP provides a broadcast TWT schedule to the TWT scheduled STA by including the TWT element in the broadcast management frame, the alignment subfield 542 may be valid.

[0095] In some embodiments, when an AP attached to an AP MLD includes a broadcast TWT parameter set field 520 containing an alignment schedule within a TWT element 500 during a broadcast TWT announcement phase, the AP may also include an alignment TWT information element in the same management frame or any other broadcast frame that includes the TWT element. Details of the alignment TWT information element will be shown below.

[0096] Fig. 6A shows an example of an alignment TWT information element 600 according to an embodiment. In Fig. 6A, the alignment TWT information element 600 may include an element ID field, a length field, an element ID extension field, a control field, and an alignment scheduling information field.

[0097] The element ID field and the element ID extension field may include information for identifying the aligned TWT information element 600. The length field may indicate the length of the aligned TWT information element 600.

[0098] The control field may include an alignment scheduling link bitmap existence subfield, an all links subfield, and a reserved bit, as shown in FIG6B . The alignment scheduling link bitmap existence subfield may indicate whether the alignment scheduling link bitmap subfield exists in the alignment TWT parameter set field included in the alignment scheduling information field. One or more alignment TWT parameter set fields may be included in the alignment scheduling information field. More specifically, if the alignment scheduling link bitmap existence subfield is set to 1, it may indicate that all alignment TWT parameter set fields include the alignment scheduling link bitmap subfield. Otherwise, no alignment TWT parameter set field includes the alignment scheduling link bitmap subfield. The all links subfield may indicate whether all scheduling specified by the broadcast TWT ID subfield of the alignment TWT parameter set field in the alignment TWT information element is available on all links of the AP MLD. If the all links subfield is set to 1, it may indicate that all scheduling included in the alignment TWT information element is available on all links of the AP MLD. Otherwise, all scheduling included in the alignment TWT information element is unavailable on all links.

[0099] In another embodiment, the control field can be implemented as shown in Figure 6C. The control field 620 may include an alignment scheduling link bitmap existence subfield and a reserved bit. In Figure 6C, the alignment scheduling link bitmap existence subfield may be similar or identical to the alignment scheduling link bitmap existence subfield in Figure 6B. However, the control field shown in Figure 6C may not include all link subfields of Figure 6B.

[0100] The alignment schedule information field of the alignment TWT information element 600 may include one or more alignment TWT parameter set fields. Each alignment TWT parameter set field may be associated with a corresponding one of a plurality of alignment schedules advertised by an AP affiliated with the AP MLD.

[0101] 6D shows an example of an aligned TWT parameter set field 630 included in the aligned TWT information element 600. In FIG6D, the aligned TWT parameter set field 630 may include a broadcast TWT ID subfield, a reserved subfield, and an aligned scheduling link bitmap subfield.

[0102] The broadcast TWT ID subfield may indicate the broadcast TWT ID of the aligned TWT schedule corresponding to the aligned TWT parameter set field. In some embodiments, when an aligned schedule is advertised on multiple links by an AP attached to an AP MLD, the broadcast TWT ID subfield in each aligned TWT parameter set field on its corresponding link may have the same value. However, in some embodiments, the broadcast TWT IDs corresponding to the aligned schedules announced on the two links may be different.

[0103] The alignment scheduling link bitmap subfield may indicate a link ID corresponding to a link of the AP MLD on which the alignment scheduling specified by the broadcast TWT ID subfield is applied. In some embodiments, if the bit position i of the alignment scheduling link bitmap subfield is set to 1, it may indicate that the corresponding alignment scheduling is available on link i of the AP MLD. Otherwise, the corresponding scheduling is not available on link i of the AP MLD. The alignment scheduling link bitmap subfield may be optional. In some embodiments, the alignment scheduling link bitmap subfield may not exist when the alignment scheduling link bitmap subfield within the control field indicates that it does not exist.

[0104] Figure 6E shows another example of an alignment TWT parameter set field 640 included in the alignment TWT information element 600. In Figure 6E, the alignment TWT parameter set field 640 may include a broadcast TWT ID subfield, a reserved subfield, an all enabled link subfield, and an alignment scheduling link bitmap subfield. The broadcast TWT ID subfield and the alignment scheduling link bitmap subfield in Figure 6E are similar or identical to those in Figure 6D. All enabled link subfields may indicate the availability of alignment scheduling on all links. For example, if all enabled link subfields are set to 1, it may indicate that the corresponding alignment scheduling is available on all links. Otherwise, the corresponding alignment scheduling is not available on all links. In some embodiments, if all enabled link subfields are set to 1, the alignment scheduling link bitmap may not exist in the alignment TWT parameter set field.

[0105] 6F shows another example of an aligned TWT parameter set field 650 included in the aligned TWT information element 600. In FIG6F , the aligned TWT parameter set field 650 may include a broadcast TWT ID subfield and a reserved subfield. Compared to FIGS. 6D and 6E , the aligned TWT parameter set field 650 does not include the aligned scheduling link bitmap subfield shown in FIGS. 6D and 6E and the all enabled link subfields shown in FIG6E . The broadcast TWT ID subfield may be the same as in FIG6D .

[0106] In some embodiments, a TWT scheduling AP attached to an AP MLD can indicate whether a broadcast TWT schedule is an aligned schedule when announcing the schedule in its BSS. An aligned schedule is a broadcast TWT schedule available across multiple links so that the target wake-up times of the schedules on the multiple links are aligned. Other TWT parameters of the schedules on those multiple links can remain the same as each other. In some embodiments, a TWT scheduling AP attached to an AP MLD can explicitly indicate whether the schedule is an aligned schedule by setting the alignment subfield 542 in the request type field of the corresponding broadcast TWT parameter set field 520 in Figure 5 to 1.

[0107] FIG7 shows another example of an alignment TWT information element 700 according to an embodiment. In FIG7 , the alignment TWT information element 700 may include an element ID field, a length field, an element ID extension field, and an alignment scheduling information field. The various fields and subfields of the alignment TWT information element 700 are the same or similar to the corresponding fields and subfields of the alignment TWT information element 600 shown in FIGS. 6A and 6D . Compared to the alignment TWT information element 600 shown in FIGS. 6A and 6D , the alignment TWT information element 700 does not include a control field, and the alignment scheduling link bitmap subfield is always present.

[0108] More specifically, the element ID field and the element ID extension field may include information for identifying the alignment TWT information element 700. The length field may indicate the length of the alignment TWT information element 700. The alignment schedule information field of the alignment TWT information element 700 may include one or more alignment TWT parameter set fields. Each alignment parameter set field may be associated with a corresponding one of a plurality of alignment schedules advertised by an AP affiliated with the AP MLD.

[0109] The alignment TWT parameter set field 710 may include a broadcast TWT ID subfield, a reserved subfield, and an alignment scheduling link bitmap subfield. The alignment scheduling link bitmap subfield 710 may be similar or identical to the alignment scheduling link bitmap subfield 630 shown in Figure 6D. In this example, the alignment scheduling link bitmap subfield 710 has a length of 16 bits and may always be present in the alignment TWT parameter set field. However, the alignment scheduling link bitmap subfields 630 and 640 shown in Figures 6D and 6E are optional and may not exist in some cases.

[0110] FIG8 shows another example of an aligned TWT information element 800 according to an embodiment. In FIG8 , the aligned TWT information element 800 may include an element ID field, a length field, an element ID extension field, and an aligned TWT information field. The element ID field, the length field, and the element ID extension field are the same or similar to the corresponding fields of the aligned TWT information element 600 in FIG6A. The aligned TWT information field may include information related to the aligned TWT. The aligned TWT information field may be associated with an independent TWT or a broadcast TWT.

[0111] In some embodiments, the element ID field and the element ID extension field of the aligned TWT information elements 600, 700, and 800 may be implemented as shown in Table 2 below.

[0112]

Table 2

[0113]

[0114] In some embodiments, the alignment TWT information elements 600 and 700 may be included in a beacon frame body, an association response frame body, a reassociation response frame body, or a probe response frame body, as shown in Tables 3-6 below.

[0115]

Table 3

[0116]

[0117]

Table 4

[0118]

[0119]

Table 5

[0120]

[0121]

Table 6

[0122]

[0123] In some embodiments, when a broadcast TWT schedule is announced in the BSS of the AP, the TWT scheduling AP attached to the AP MLD may optionally indicate a specific link of the AP MLD on which the alignment schedule is available. This can be achieved by specifying the relevant links in the alignment schedule link bitmap subfield of the alignment information element.

[0124] In some embodiments, a TWT scheduled STA attached to a non-AP MLD that is interested in joining an existing alignment schedule on multiple links may deliver its request to join the schedule on those links individually. In some embodiments, a TWT scheduled STA attached to a non-AP MLD may receive a broadcast TWT element having a broadcast TWT parameter set field, in which the alignment subfield in the request type subfield is set to 1. The TWT scheduled STA may expect to receive an alignment TWT information element in a broadcast frame sent by a TWT scheduling AP attached to the APMLD. The TWT scheduled STA may be notified of the link on which the alignment scheduling is available, as indicated by the alignment scheduling link bitmap subfield in the alignment TWT information element. For example, if bit i of the alignment scheduling link bitmap subfield is set to 1, it may indicate that the alignment scheduling is available on the i-th link. Otherwise, the alignment scheduling is not available on the i-th link. In addition, if all link subfields of the control field 610 of the alignment TWT information element 600 are set to 1, it can indicate that all schedules corresponding to all alignment TWT parameter set fields included in the alignment TWT information element 600 are available on all links corresponding to the APs attached to the AP MLD. Otherwise, all schedules corresponding to all alignment TWT parameter set fields included in the alignment TWT information element are not available on all links corresponding to the APs attached to the APMLD. When a STA attached to a non-AP MLD receives an alignment TWT information element that does not include an alignment scheduling link bitmap subfield, the STA attached to the same non-AP MLD and operating on the link between the AP MLD and the non-AP MLD can check the beacon frame, probe response frame or other broadcast frame to determine whether the corresponding alignment schedule is available on the link.

[0125] In some embodiments, when alignment scheduling is available on any two links between an AP MLD and a non-AP MLD, any changes made to the TWT parameters of the alignment scheduling on the first link may also be applied to the alignment scheduling on the second link. For example, when a first AP operating on a first link makes any change to the value of the broadcast persistence subfield in the broadcast TWT information field 550 within the broadcast TWT parameter set field 520 corresponding to the alignment scheduling on the first link (as shown in FIG. 5 ), a second AP operating on a second link also makes the same change to the value of the broadcast persistence subfield of the broadcast TWT parameter set field corresponding to the alignment scheduling on the second link.

[0126] In some embodiments, alignment scheduling may be established on any two links between an AP MLD and a non-AP MLD. In this scenario, if the alignment scheduling on the first link is terminated or suspended for a first STA affiliated with a non-AP MLD operating on the first link, the alignment scheduling on the second link may continue to remain the same or unchanged for a second STA affiliated with a non-AP MLD operating on the second link. Therefore, the second scheduling for the second link may not be terminated or suspended. In some embodiments, when the alignment scheduling is terminated or suspended for a first STA operating on the first link, the alignment scheduling on the second link may also be terminated or suspended for a second STA affiliated with the same non-AP MLD.

[0127] FIG9 shows a flow chart illustrating an example process 900 of an AP MLD supporting aligned TWT operation according to an embodiment. To illustrate each operation of process 900, the examples of FIG4 and FIG5 will be used for illustration. Although one or more operations are described or shown in a particular sequential order, in other embodiments, the operations may be rearranged in a different order, which may include performing multiple operations in at least partially overlapping time periods.

[0128] Process 900 may start in operation 901. In operation 901, a TWT scheduling AP attached to the AP MLD 410 may explicitly indicate whether the corresponding TWT schedule is an aligned schedule when announcing a broadcast TWT schedule in the BSS of the AP using a broadcast frame such as a beacon frame or a probe response frame. This may be achieved by setting the alignment subfield 542 in the corresponding broadcast TWT parameter set field 520 within the TWT element 500 to 1. An aligned schedule is a broadcast TWT schedule that is available across multiple links so that the target wake-up times of those schedules on the multiple links are aligned with each other. The other TWT parameters of the aligned schedules on those multiple links remain the same as each other. The alignment subfield 542 may indicate whether the corresponding schedule is available on more than one link of the AP MLD 410.

[0129] In operation 903, the TWT scheduling AP attached to the AP MLD 410 may receive a request to join the alignment schedule from the TWT scheduled STA attached to the non-AP MLD 420. In some embodiments, multiple TWT scheduling APs attached to the AP MLD 410 may separately receive multiple requests to join the alignment schedule on their respective links from multiple TWT scheduled STAs attached to the non-AP MLD 420 that are interested in joining the existing alignment schedule on multiple links. Then, the process 900 proceeds to operation 905.

[0130] At operation 905, the TWT scheduling AP affiliated with AP MLD 410 may establish aligned TWT scheduling on its operating links. In some embodiments, multiple TWT scheduling APs affiliated with AP MLD 410 may establish aligned TWT scheduling on their respective links between AP MLD 410 and non-AP MLD 420.

[0131] FIG10 shows a flowchart illustrating an example process 1000 for a non-AP MLD supporting aligned TWT operations according to an embodiment. To illustrate each operation of process 1000, an explanation will be given using the examples of FIG4 and FIG5. Although one or more operations are described or shown in a particular sequential order, in other embodiments, the operations may be rearranged in a different order, which may include performing multiple operations in at least partially overlapping time periods.

[0132] Process 1000 may start in operation 1001. In operation 1001, a TWT scheduled STA attached to a non-AP MLD 420 may receive a broadcast frame from a TWT scheduling AP attached to an AP MLD 410, the broadcast frame including an indication of whether the corresponding TWT schedule is an aligned schedule. The broadcast frame may be a beacon frame or a probe response frame. In addition, the indication may be implemented by setting the alignment subfield 542 in the corresponding broadcast TWT parameter set field 520 within the TWT element 500 to 1. Aligned scheduling is a broadcast TWT schedule available across multiple links so that the target wake-up times of those schedules on the multiple links are aligned with each other. The other TWT parameters of the aligned schedules on those multiple links remain the same as each other. The alignment subfield 542 may indicate whether the corresponding schedule is available on more than one link of the APMLD 410. In some embodiments, the TWT scheduled STA may use the TWT parameters of the TWT schedule to determine which TWT schedule on its corresponding link is the aligned schedule. For example, referring to FIG. 4 , after STA 1 of non-AP MLD 420 operating on link 1 receives a beacon frame and observes that TWT schedule 1 is marked as an alignment schedule by TWT element 500 in the beacon frame, STA 2 and STA 3 of non-AP MLD 420 operating on link 2 and link 3, respectively, may process communications with AP 2 and AP 3 of AP MLD 410 on their respective links to determine which TWT schedules on their respective links match the TWT parameters of TWT schedule 1. More specifically, both STA 2 and STA 3 wake up to receive beacon frames on link 2 and link 3, respectively, to identify the presence of the alignment schedule announced on link 1 on their respective links by checking whether the TWT parameters of their TWT schedules match TWT schedule 1. After identifying the alignment schedule on their respective links, each STA of non-AP MLD 420 may determine whether they are interested in joining the alignment schedule.

[0133] In operation 1003, when a TWT scheduled STA attached to the non-AP MLD 420 is interested in joining the alignment scheduling, the TWT scheduled STA may send a request to join the alignment scheduling to the TWT scheduling AP attached to the AP MLD 410. In some embodiments, when multiple TWT scheduled STAs attached to the non-AP MLD 420 are interested in joining the alignment scheduling on multiple links, the multiple TWT scheduled STAs may send their requests to the corresponding TWT scheduling APs attached to the AP MLD 410 to separately join the alignment scheduling on their respective links. Then, the process 1000 proceeds to operation 1005.

[0134] In operation 1005, the TWT scheduled STAs attached to the non-AP MLD 420 may join the aligned TWT scheduling on the corresponding links established by the TWT scheduling AP attached to the AP MLD 410. In some embodiments, multiple TWT scheduled STAs attached to the non-AP MLD 420 may join the aligned TWT scheduling on their respective links established by the corresponding TWT scheduling APs attached to the AP MLD 410.

[0135] Unless specifically stated otherwise, 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 constraints, an element beginning with "a", "an", "the" or "said" does not exclude the presence of additional identical elements.

[0136] 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 a claim. 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.

[0137] 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, example, this example, another example, some examples, one or more examples, configuration, this configuration, another configuration, some configurations, one or more configurations, subject technology, 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.

[0138] The phrase "at least one of" preceding a list of items (where the terms "and" or "or" are used to separate any 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 permits a meaning that includes at least one of any of the items, and / or at least one of any combination of the items, and / or at least one of each of the items. For example, each of the phrases "at least one of A, B, and C" or "at least one of A, B, or C" means only A, only B, or only C; any combination of A, B, and C; and / or at least one of each of A, B, and C.

[0139] 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.

[0140] The 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 disclosure provides various examples of the subject technology, and the subject technology is not limited to these examples. Various modifications to these aspects will be apparent to those skilled in the art, and the principles described herein can be applied to other aspects.

[0141] All structural and functional equivalents of the elements of various aspects described throughout the present disclosure are expressly incorporated herein by reference and are intended to be covered by the claims, which are known or later become known to those of ordinary skill in the art. 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 interpreted under the provisions of 35 U.S.C. §112, sixth paragraph, unless the phrase "means for..." is used to expressly recite the element, or, in the case of a method claim, the phrase "step for..." is used to recite the element.

[0142] 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 at the time of submission that they 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 for the purpose of simplifying the present disclosure, various features are grouped together in various implementations. This 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 thus incorporated into the specific implementation, with each claim independently serving as a separately claimed subject matter.

[0143] 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) in a wireless network, the AP MLD comprising: At least two APs, each AP is attached to an AP MLD; as well as at least one processor coupled to the at least two APs, the at least one processor being configured to: A first AP attached to the AP MLD sends a first broadcast frame announcing a first target wake time (TWT) schedule to a first STA on a first link between the first AP and a first STA attached to the non-AP MLD, the first broadcast frame indicating whether the first TWT schedule is an aligned schedule; Receiving, by the first AP, a first request from the first STA on the first link to join a first TWT schedule; and A first TWT schedule is established by the first AP on the first link that is aligned with a second TWT schedule established on a second link between a second AP attached to the AP MLD and a second STA attached to the non-AP MLD.

2. The AP MLD according to claim 1, wherein: The first broadcast frame includes a TWT element including an alignment subfield indicating whether alignment scheduling is available on more than one link of the AP MLD.

3. The AP MLD according to claim 2, wherein: In response to the alignment subfield being set to a first value, the alignment subfield indicating that there is a schedule on the other link that is aligned with the first TWT schedule on the first link within a predetermined interval, wherein, in response to the alignment subfield being set to a second value, the alignment subfield indicates that there is no schedule on the other link that is aligned with the first TWT schedule on the first link within a predetermined interval, and In which, in response to the negotiation type subfield of the control field of the TWT element instructing the first AP to manage membership in the TWT schedule by including the TWT element in an individually addressed management frame, the alignment subfield is retained.

4. The AP MLD according to claim 1, wherein: An aligned schedule is a broadcast TWT schedule available across multiple links, and the target wake-up times of the broadcast TWT schedules on the multiple links are aligned, and Among them, the TWT parameters of the alignment scheduling on multiple links are the same.

5. The AP MLD according to claim 1, wherein: The at least one processor is further configured to: The second AP sends a second broadcast frame announcing a second TWT schedule to the second STA on the second link; Receiving, by the second AP from the second STA on the second link, a second request to join a second TWT schedule aligned with the first TWT schedule established on the first link; as well as A second TWT schedule is established on the second link by the second AP.

6. The AP MLD according to claim 5, wherein: The at least one processor is further configured to: A third AP attached to the AP MLD sends a third broadcast frame announcing a third TWT schedule to a third STA on a third link between a third STA attached to the non-AP MLD and the third AP; Receiving, by the third AP from the third STA on the third link, a third request to join a third TWT schedule aligned with the first TWT schedule established on the first link; as well as A third TWT schedule is established by the third AP on the third link.

7. 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 At least one processor is coupled to the at least two STAs, the at least one processor being configured to: receiving, by a first STA attached to a non-AP MLD, from a first AP on a first link between the first STA and a first AP attached to an AP MLD, a first broadcast frame announcing a first target wake time (TWT) schedule, the first broadcast frame indicating whether the first TWT schedule is an aligned schedule; The first STA sends a first request to join the first TWT scheduling to the first AP on the first link; and The first TWT schedule established on the first link is joined and aligned with the second TWT schedule established on the second link between the second STA attached to the non-AP MLD and the second AP attached to the AP MLD.

8. The non-AP MLD according to claim 7, wherein: The first broadcast frame includes a TWT element including an alignment subfield indicating whether alignment scheduling is available on more than one link of the AP MLD.

9. The non-AP MLD according to claim 8, wherein: In response to the alignment subfield being set to a first value, the alignment subfield indicating that there is a schedule on the other link that is aligned with the first TWT schedule on the first link within a predetermined interval, wherein, in response to the alignment subfield being set to a second value, the alignment subfield indicates that there is no schedule on the other link that is aligned with the first TWT schedule on the first link within a predetermined interval, and In which, in response to the negotiation type subfield of the control field of the TWT element instructing the first AP to manage membership in the TWT schedule by including the TWT element in an individually addressed management frame, the alignment subfield is retained.

10. The non-AP MLD according to claim 7, wherein: An aligned schedule is a broadcast TWT schedule available across multiple links, and the target wake-up times of the broadcast TWT schedules on the multiple links are aligned, and Among them, the TWT parameters of the alignment scheduling on multiple links are the same.

11. The non-AP MLD according to claim 7, wherein: The at least one processor is further configured to: Receiving, by the second STA from the second AP on the second link, a second broadcast frame announcing a second TWT schedule; The second STA determines, based on the TWT parameters of the second TWT schedule, that the second TWT schedule is an aligned schedule aligned with the first TWT schedule; The second STA sends a second request to join the second TWT scheduling to the second AP on the second link; as well as Join the second TWT schedule established on the second link, and the second TWT schedule is aligned with the first TWT schedule established on the first link.

12. The non-AP MLD according to claim 11, wherein: The at least one processor is further configured to: receiving, by a third STA attached to the non-AP MLD, a third broadcast frame announcing a third TWT schedule from a third AP on a third link between the third STA and a third AP attached to the AP MLD; The third STA determines, based on the TWT parameters of the third TWT schedule, that the third TWT schedule is an aligned schedule aligned with the first TWT schedule; The third STA sends a third request to join the third TWT scheduling to the third AP on the second link; as well as Join the third TWT schedule established on the third link, and the third TWT schedule is aligned with the first TWT schedule established on the first link.

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

14. A method performed by an access point (AP) multi-link device (MLD) associated with a non-AP MLD in a wireless network, the method comprising operations performed by at least one processor in the non-AP MLD of one of claims 7 to 12.

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