Wireless communication method and apparatus implemented in a first multi-link device

Abstract

The present application provides a wireless communication method and an apparatus implemented in a first multi-link device. The method can include: a first multi-link device MLD enabling an enhanced multi-link single radio EMLSR mode; and the first multi-link device establishing a concurrent TWT protocol with a second MLD on a plurality of links including at least a first link and a second link; wherein the establishing the concurrent TWT protocol includes: a first station STA attached to the first MLD sending a TWT request to a first peer STA attached to the second MLD, the TWT request containing a TWT element, the TWT element including a link identification ID bitmap subfield, the link ID bitmap subfield indicating a plurality of links requested for establishing the concurrent TWT protocol; receiving, by the first STA, a TWT response from the first peer STA, the TWT response containing another TWT element, the other TWT element including another link ID bitmap subfield, the other link ID bitmap subfield indicating a plurality of links on which the concurrent TWT protocol is agreed to be established.

Description

Technical Field

[0001] This disclosure generally relates to wireless communications, and more specifically to Enhanced Multi-Link Single-Radio (EMLSR) Target Wake Time (TWT) operation in wireless communications. Background Technology

[0002] Unless otherwise stated herein, the methods described in this section are not prior art to the claims listed below, and are not included as prior art in this section.

[0003] In wireless local area networks (WLANs) conforming to the IEEE 802.11 specification, concurrent Target Wake Time (TWT) agreements pertain to establishing multiple TWT agreements on more than one link between an Access Point (AP) Multi-Link Device (MLD) and a non-AP MLD, with the TWT service periods (SPs) of these multiple TWT agreements overlapping in time. An AP MLD may not establish concurrent TWT agreements for a single radio non-AP MLD unless the single radio non-AP MLD has EMLSR mode enabled (in which case the AP MLD can establish concurrent TWT agreements with that single radio non-AP MLD). However, the details regarding TWT operations between AP MLDs and non-AP MLDs still require further definition. Therefore, a solution for EMLSR TWT operations in wireless communications is needed. Summary of the Invention

[0004] The following overview is illustrative only and is not intended to be limiting in any way. That is, it is provided to introduce the concepts, key points, benefits, and advantages of the novel and non-obvious techniques described herein. Selected embodiments are further described below in a detailed description. Therefore, the following summary is not intended to identify essential features of the claimed subject matter, nor is it intended to define the scope of the claimed subject matter.

[0005] In one aspect, this disclosure provides a wireless communication method that may include: a first multilink device (MLD) enabling an enhanced multilink single radio (EMLSR) mode; and the first multilink device and a second MLD establishing a concurrent TWT protocol on a multilink comprising at least a first link and a second link; wherein establishing the concurrent TWT protocol includes: a first station (STA) attached to the first MLD sending a TWT request to a first peer STA attached to the second MLD, the TWT request including a TWT element including a link identifier (ID) bitmap subfield indicating the multiple links requested for establishing the concurrent TWT protocol; and receiving a TWT response from the first peer STA via the first STA, the TWT response including another TWT element including another link ID bitmap subfield indicating the multiple links on which the concurrent TWT protocol is agreed to be established.

[0006] In another aspect, this disclosure provides an apparatus implemented in a first multi-link device (MLD), which may include: a transceiver configured to wirelessly communicate with a second MLD; and a processor coupled to the transceiver, wherein the processor is configured to perform the following operations: enabling an enhanced multi-link single radio (EMLSR) mode; and establishing a concurrent TWT protocol with the second MLD via the transceiver on a multi-link consisting of at least a first link and a second link; wherein establishing the concurrent TWT protocol includes: sending a TWT request as a first station (STA) attached to the first MLD to a first peer STA attached to the second MLD, the TWT request including a TWT element including a link identifier (ID) bitmap subfield indicating the multiple links requested for establishing the concurrent TWT protocol; and receiving a TWT response as the first STA from the first peer STA, the TWT response including another TWT element including another link ID bitmap subfield indicating the multiple links on which the concurrent TWT protocol is agreed to be established.

[0007] It is worth noting that although the descriptions provided herein may be in the context of certain radio access technologies, networks, and network topologies (e.g., Wi-Fi), the proposed concepts, schemes, and any variations / derivatives can be implemented in other types of radio access technologies, networks, and network topologies, such as, but not limited to, Bluetooth, ZigBee, 5G / New Radio (NR), LTE, LTE-Advanced, LTE-Advanced Pro, Internet of Things (IoT), Industrial Internet of Things (IIoT), and Narrowband Internet of Things (NB-IoT). Therefore, the scope of this disclosure is not limited to the examples described herein. Attached Figure Description

[0008] The accompanying drawings are included to provide a further understanding of this disclosure, and are incorporated in and constitute a part of this disclosure. The drawings illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure. It is understood that the drawings are not necessarily drawn to scale, as some components may be shown out of proportion to actual dimensions in order to clearly illustrate the concepts of the disclosure.

[0009] Figure 1 Example network environment 100 is shown, in which various solutions and schemes according to this disclosure can be implemented.

[0010] Figure 2 According to this disclosure, an example scenario 200 is shown under a proposed scheme for EMLSR TWT operation.

[0011] Figure 3 According to this disclosure, an example scenario 300 is shown under a proposed scheme for EMLSR TWT operation.

[0012] Figure 4 According to this disclosure, an example scenario 400 is shown under a proposed scheme for EMLSR TWT operation.

[0013] Figure 5 The illustration shows an example system 500 that includes at least example device 510 and example device 520 according to the present disclosure.

[0014] Figure 6 An example process 600 according to an embodiment of this disclosure is shown. Detailed Implementation

[0015] This document discloses detailed embodiments and implementations of the claimed subject matter. However, it should be understood that the disclosed embodiments and implementations are merely illustrative of the claimed subject matter, which can be embodied in various forms. This disclosure can be implemented in many different forms and should not be construed as limited to the exemplary embodiments and implementations set forth herein. Rather, these exemplary embodiments and implementations are provided so that the description of this disclosure is thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art. In the following description, details of well-known features and technologies may be omitted to avoid unnecessary obscurity in the presented embodiments and implementations.

[0016] Overview

[0017] Implementations of this disclosure relate to various techniques, methods, schemes, and / or solutions related to EMLSR TWT operation in wireless communication. According to this disclosure, many possible solutions can be implemented individually or in combination. That is, although these possible solutions may be described separately below, two or more of these possible solutions may be implemented in one combination or another.

[0018] Figure 1 Example network environment 100 is shown, in which various solutions and schemes according to this disclosure can be implemented. Figures 2-6 Examples of implementations of various proposed schemes in a network environment 100 according to this disclosure are shown. The following description of the various proposed schemes refers to... Figures 1-6 .

[0019] refer to Figure 1 Network environment 100 may include a first MLD (MLD 110) and a second MLD (MLD 120), which conduct wireless communication over multiple links (e.g., link 1, link 2, and link 3) or in multiple frequency bands according to one or more IEEE 802.11 standards. Each of MLD 110 and MLD 120 can be used as an AP MLD or a non-AP MLD. For example, MLD 110 can be used as a non-AP MLD including multiple virtual STAs operating within MLD 110, and MLD 120 can be used as an AP MLD including multiple virtual APs operating within MLD 120. Alternatively, MLD 110 can be used as an AP MLD including multiple virtual APs operating within MLD 110, and MLD 120 can be used as a non-AP MLD including multiple virtual STAs operating within MLD 120. This is by way of example and not as a limitation of the disclosure. Figure 1In this document, MLD 110 is shown as having multiple APs or non-AP STAs attached (e.g., STA 1 and STA 2), and MLD 120 is shown as having multiple APs or non-AP STAs attached (e.g., STA'1 and STA'2). It is noteworthy that while a certain number of STAs (e.g., two) are shown attached to each of MLD 110 and MLD 120, in actual implementation, the number N of STAs attached to each of MLD 110 and MLD 120 may be the same as or different from the number of corresponding links between MLD 110 and MLD 120. Under the various proposed schemes according to this disclosure, MLD 110 and MLD 120 can be configured to perform EMLSR TWT operations in wireless communication according to the various proposed schemes described herein. It is noteworthy that even though each of the various proposed schemes may be described separately below, the various proposed schemes may be implemented individually or optionally jointly (e.g., two or more proposed schemes implemented together).

[0020] Under current IEEE specifications, regarding the EMLSR procedure, a non-AP MLD (e.g., MLD 110) can operate in EMLSR mode on a specific group of enabled links (including one or more enabled links) between the non-AP MLD and an associated AP MLD (e.g., MLD 120). This specific group of enabled links (including one or more enabled links) applying EMLSR mode can be referred to as EMLSR links. EMLSR links are indicated in the EMLSR link bitmap subfield of the EML control field of the Enhanced Multi-Link (EML) operation mode notification frame by setting the bit positions of the EMLSR link bitmap subfield to 1. For EMLSR mode enabled in a single radio non-AP MLD (e.g., MLD 110), when operating on one of the EMLSR links and a STA attached to the non-AP MLD is awake, one or more STAs attached to that non-AP MLD operating on the link corresponding to a bit position of 0 in the EMLSR link bitmap subfield may be in a sleep state. Furthermore, an MLD with dot11EHTEMLSROptionImplemented set to "true" can set the EML Capabilities Present subfield to 1 and can also set the EML Support subfield of the Common Info field for all management frames (excluding authentication frames) including the Basic Multi-Link element to 1. On the other hand, an MLD with dot11EHTEMLSROptionImplemented set to "false" and dot11EHTEMLMROptionImplemented set to "true" can set the EML Capabilities Present subfield to 1 and can also set the EML Support subfield of the EML Capabilities subfield to 0. On the other hand, MLDs with dot11EHTEMLSROptionImplemented and dot11EHTEMLMROptionImplemented equal to "false" can set the EML Capabilities Present subfield to 0.

[0021] Regarding the execution of the EMLSR procedure, when a non-AP MLD (e.g., MLD 110) with dot11EHTEMLSROptionImplemented equal to "true" wants to operate in EMLSR mode on an EMLSR link, a STA attached to that non-AP MLD can send an EML operation mode notification frame to an AP attached to an AP MLD (e.g., MLD 120) with dot11EHTEMLSROptionImplemented equal to "true", and set the EMLSR mode subfield of the EML control field of the EML operation mode notification frame to 1. Furthermore, an AP attached to the AP MLD that receives an EML operation mode notification frame from a STA attached to the non-AP MLD may send an EML operation mode notification frame to one of the multiple STAs attached to the non-AP MLD within the timeout interval indicated in the Transition Timeout subfield of the EML capability subfield of the basic multilink element, as an acknowledgment of the EML operation mode notification frame sent by the STA attached to the non-AP MLD, wherein the timeout interval begins from the end of the Physical-layer Protocol Data Unit (PPDU) sent by the AP attached to the AP MLD. After a STA attached to a non-AP MLD successfully transmits an EML operation mode notification frame on one of the EMLSR links, the non-AP MLD can operate in EMLSR mode. STAs on other links of the EMLSR link can switch to active mode after the switching delay indicated in the switching timeout subfield of the EML capability subfield of the basic multi-link element. Alternatively, STAs on other links of the EMLSR link can switch to active mode immediately after receiving an EML operation mode notification frame from one of the APs operating on the EMLSR link and attached to the AP MLD. Furthermore, STAs on other links of the EMLSR link may not transmit frames with the power management subfield set to 1 before receiving an EML operation mode notification frame from the AP attached to the AP MLD or before the end of the timeout interval.

[0022] Regarding the disabling EMLSR procedure, when a non-AP MLD (e.g., MLD 110) with dot11EHTEMLSROptionImplemented equal to "true" wants to disable EMLSR mode, a STA attached to that non-AP MLD can send an EML Operation Mode Notification Frame to an AP attached to an AP MLD (e.g., MLD 120) with dot11EHTEMLSROptionImplemented equal to "true", and set the EMLSR Mode subfield of the EML Control Field in the EML Operation Mode Notification Frame to 0. Accordingly, the AP attached to the AP MLD that receives the EML operation mode notification frame from the STA attached to the non-AP MLD may send an EML operation mode notification frame to one of the STAs attached to the non-AP MLD within the timeout interval indicated in the transition timeout subfield of the EML capability subfield of the basic multilink element, as an acknowledgment of the EML operation mode notification frame sent by the STA attached to the non-AP MLD. The timeout interval begins from the end of the physical layer protocol data unit (PPDU) sent by the AP attached to the AP MLD. After a STA attached to the non-AP MLD successfully transmits an EML operation mode notification frame on one of the EMLSR links, the non-AP MLD can disable EMLSR mode, and STAs on other links of the EMLSR link can switch to power-save mode after the switch timeout subfield indicated in the EML capability subfield of the basic multi-link element. Alternatively, STAs on other links of the EMLSR link can switch to power-save mode immediately after receiving an EML operation mode notification frame from one of the APs operating on the EMLSR link and attached to the AP MLD. Furthermore, STAs on other links of the EMLSR link may not transmit frames with the power management subfield set to 0 before receiving an EML operation mode notification frame from the AP attached to the AP MLD or before the end of the timeout interval.

[0023] As described below, certain conditions may apply when a non-AP MLD (e.g., MLD 110) is operating in EMLSR mode, while an AP MLD (e.g., MLD 120) supports EMLSR mode. For example, a non-AP MLD can listen on an EMLSR link by waking up its attached STA corresponding to the EMLSR link. This listening operation may include Clear Channel Assessment (CCA) and receiving the initial control frame for frame switching initiated by the AP MLD. Furthermore, the initial control frame for frame switching can be transmitted at a rate of 6 Mbps, 12 Mbps, or 24 Mbps in Orthogonal Frequency Division Multiplexing (OFDM) PPDU or a non-high throughput (non-HT) duplicated PPDU format. Furthermore, the initial control frame can be a Multi-User Request-To-Send (MU-RTS) trigger frame or a Buffer Status Report Poll (BSRP) trigger frame, and reception of MU-RTS and BSRP trigger frames may be mandatory for non-AP MLDs in EMLSR mode. The number of response space streams for BSRP trigger frames can be limited to one. Additionally, non-AP MLDs can indicate the delay duration in the EML Capability subfield of the Common Information field of the Basic Multilink Element in the EML Padding Delay subfield. Furthermore, an AP attached to an AP MLD (which initiates frame exchange with a non-AP MLD on one of the EMLSR links) can initiate frame exchange by sending an initial control frame to the non-AP MLD using the aforementioned restrictions (including the rate, format, and frame type). After receiving the initial control frame of frame switching until the frame switching ends, a STA attached to a non-AP MLD listening on the corresponding link may send or receive frames on the link where the initial control frame was received, but may not send or receive frames on other EMLSR links. Depending on the spatial stream capability, operating mode, and link switching latency of the STA attached to the non-AP MLD, the STA may be able to receive PPDUs using more than one spatial stream on the link where the initial control frame was received after a short inter-frame space (SIFS) following the completion of the response frame sent in response to the initial control frame request. During frame switching, other APs attached to the AP MLD may not send frames to other STAs attached to the non-AP MLD on other EMLSR links.

[0024] When any of the conditions described below are met, a non-AP MLD can switch back to listening operation on an EMLSR link after the time indicated in the EML capability subfield of the common information field of the basic multi-link element, which can be defined as the end of frame switching. For example, if the Medium Access Control (MAC) layer of a STA attached to a non-AP MLD that received the initial control frame does not receive the PHY-RXSTART.indication primitive during the timeout interval aSIFSTime+aSlotTime+aRxPHYStartDelay, which begins at the end of a PPDU sent by the STA of the non-AP MLD (which is a response to a frame recently received from the AP attached to the AP MLD), or if aSIFSTime+aSlotTime+aRxPHYStartDelay begins at the end of a PPDU containing a frame for the STA received by the AP attached to an AP MLD that does not require immediate acknowledgment. Furthermore, if the MAC layer of a STA attached to a non-AP MLD receives the PHY-RXSTART.indication primitive during the timeout interval aSIFSTime+aSlotTime+aRxPHYStartDelay and the STA attached to the non-AP MLD does not detect any of the following frames (a)-(e) in the PPDU corresponding to PHY-RXSTART.indication, then the STA is attached to the non-AP MLD. Frames (a)-(e) include: (a) a separately addressed frame whose RA (Receiver Address) is equal to the MAC address of the STA attached to the non-AP MLD; (b) a trigger frame whose user information field addresses the STA attached to the non-AP MLD; (c) a CTS-to-self frame whose RA is equal to the MAC address of the AP attached to the AP MLD; (d) a multi-STA block acknowledgment frame whose association IDentifier (AID) and traffic IDentifier (TID) address the STA attached to the non-AP MLD; and (e) a Neighbor Discovery Protocol (NDP) advertisement frame whose STA information field addresses the STA attached to the non-AP MLD. Finally, a STA attached to a non-AP MLD that receives the initial control frame does not respond to frames recently received from an AP attached to the AP MLD, which must respond immediately after SIFS.

[0025] As described below, when a non-AP MLD (e.g., MLD 110) is operating in EMLSR mode and an AP MLD (e.g., MLD 120) supports EMLSR mode, other applicable conditions may exist. For example, if an AP attached to an AP MLD wants to continue frame exchange with a STA attached to a non-AP MLD and the AP does not receive a response frame from that STA after SIFS for the most recently transmitted frame requiring an immediate response, the AP may transmit another initial control frame addressed to that STA attached to the non-AP MLD before the Transmission Network Allocation Vector (TXNAV) timer expires. When a STA of a non-AP MLD initiates a Transmission Opportunity (TXOP), the non-AP MLD may switch back to listen operation on the EMLSR link after the TXOP ends and after the duration indicated by the EMLSR transition delay subfield. Furthermore, only a STA operating on one of the EMLSR links and attached to a non-AP MLD can initiate frame exchange with the AP MLD.

[0026] Figure 2 According to this disclosure, an example scenario 200 is shown under a proposed scheme for EMLSR TWT operation. Figure 2 Section (A) illustrates STA 1 and STA 2, attached to MLD 110, performing EMLSR TWT operations with MLD 120 on Link 1 and Link 2, respectively. Due to the concurrent TWT protocol, the TWT SPs of the TWT protocols on Link 1 and Link 2 may overlap in time. During the TWT SP, STA 1 may receive a BSRP trigger frame on Link 1 and, in response, send a Buffer Status Report (BSR) before receiving data from the corresponding AP (e.g., AP1) attached to MLD 120. Meanwhile, due to EMLSR, STA 2 does not receive anything on Link 2 during the TWT SP. Figure 2 Section (B) illustrates an example format of a single TWT Information Element (IE) (which may be interchangeably referred to herein as a "TWT element") under the proposed scheme. A TWT element may include a set of TWT parameters with multiple parameters, such as... Figure 2The parameters shown in section (B) include link information parameters, which may include a link identifier (ID) bitmap subfield (e.g., occupying fifteen bits B0–B14) and a synchronization TWT request subfield (e.g., occupying bit B15). A predefined value (e.g., 1) in the synchronization TWT request subfield may indicate that the multiple links indicated by the link ID bitmap subfield require TWT SP alignment on all of these multiple links; different values ​​(e.g., 0) in the synchronization TWT request subfield may indicate other cases.

[0027] Under the proposed TWT protocol according to this disclosure, an STA attached to an MLD (e.g., MLD 110) can indicate the link requested to establish the TWT protocol in the Link ID bitmap subfield (if present) of the TWT element in a soliciting TWT request sent to another STA attached to a peer MLD (e.g., MLD 120). If only one link is indicated in the Link ID bitmap subfield of the TWT element, it means that an STA attached to the same MLD can request a single TWT protocol and that the STA operates on the indicated link. The Target Wake-up Time field of the TWT element can reference the Timing Synchronization Function (TSF) time of the link indicated by the TWT element. Furthermore, under the proposed scheme, a STA attached to a peer MLD (e.g., MLD 120 or MLD 110) that receives a TWT request (which includes a Link ID bitmap subfield in its TWT element) can respond with a TWT response that also indicates the link in the Link ID bitmap field of its TWT element. The link in the TWT element of the TWT response (if present) may be the same as the link indicated in the TWT element of the requesting TWT.

[0028] Under the proposed TWT protocol negotiation scheme according to this disclosure, during TWT protocol negotiation, a TWT request STA attached to one MLD (e.g., MLD 110 or MLD 120) and a TWT response STA attached to another MLD (e.g., MLD 120 or MLD 110) may include multiple TWT elements, and each Link ID bitmap subfield in each TWT element indicates a different link in the same TWT setup frame. TWT parameters provided by each TWT element can be applied and referenced to the corresponding link indicated in the TWT element. Furthermore, an STA attached to a peer MLD that receives a TWT request containing multiple TWT elements can respond with a TWT response indicating the link in the Link ID bitmap field of the TWT element. The link in the TWT element of the TWT response may be the same as the link indicated in the TWT element of the TWT request.

[0029] Figure 3 According to this disclosure, an example scenario 300 is shown under a proposed scheme for EMLSR TWT operation. Figure 3 Part (A) shows STA 1 and STA 2 of MLD 110 performing EMLSR TWT operations with MLD 120 on Link 1 and Link 2, respectively. Figure 3 Section (B) illustrates an example format for the TWT Teardown frame Action field. Under the proposed scheme, for a STA1 attached to a non-AP MLD (e.g., MLD 10) that has established concurrent TWT protocols with a peer MLD (e.g., MLD 120) on multiple links in EMLSR mode, the concurrent TWT protocol (e.g., for links 1 and 2) can be terminated by the non-AP MLD sending a TWT teardown frame before switching back to single-radio mode from EMLSR mode (e.g., on link 1). Reference Figure 3 In part (A), the TWT teardown frame can terminate the TWT protocol on STA2 attached to a non-AP MLD (e.g., on link 2). Ultimately, the TWT protocol may exist only on a single link (e.g., on link 1), rather than on multiple links simultaneously.

[0030] refer to Figure 3Part (B) illustrates the format of the TWT Teardown frame Actionfield. Specifically, the TWT Flow field of the TWT teardown frame can include multiple subfields, such as a TWT Flow identifier subfield, a Link ID BitmapPresent subfield, a Reserved subfield, a Negotiation Type subfield, a Teardown All TWT subfield, and a Teardown Link ID subfield (or as...). Figure 3 As shown, this is referred to as the "Link ID Bitmap Subfield". A Link ID Bitmap Subfield can exist if its value is 1; otherwise, it may not exist. The Link ID Bitmap Subfield can indicate links whose concurrent TWT protocols need to be terminated due to a TWT teardown frame sent by an STA attached to the MLD. A value of 1 at bit position i in the Link ID Bitmap Subfield may mean that the relevant link's concurrent TWT protocol is terminated due to a TWT teardown frame sent by an STA attached to the MLD. Conversely, a value of 0 at bit position i in the Link ID Bitmap Subfield may mean that the link associated with Link ID i is not a link whose concurrent TWT protocol needs to be terminated due to a TWT teardown frame sent by an STA attached to the MLD. In other words, a value of 1 in the Link ID Bitmap Subfield indicates that the TWT protocol on each link will be terminated or otherwise torn down. Furthermore, under the proposed scheme, the STA can set the Teardown All TWT subfield to 1 to indicate that the TWT teardown frame will terminate or otherwise tear down all TWT protocols on all links. Alternatively, the Teardown All TWT subfield can be set to 0 to indicate other situations.

[0031] Under the proposed scheme for EMLSR TWT operation according to this disclosure, an STA attached to an MLD can negotiate a separate (individual) TWT protocol with another STA attached to another MLD, with some exceptions. One exception is that an STA attached to an MLD may indicate, if present, the link ID bitmap subfield of the TWT element in the TWT request to establish a TWT protocol for one or more links. If only one link is indicated in the link ID bitmap subfield of the TWT element, it means that an STA attached to the same MLD is requesting a single TWT protocol and that the STA is operating on the indicated link. The target wake-up time field of the TWT element may refer to the Timing Synchronization Function (TSF) time of the link indicated by the TWT element. Another exception is that an STA attached to an MLD may indicate, if present, the link ID bitmap subfield of the TWT teardown frame to which the TWT protocol is requested to be torn down for one or more links. If only one link is indicated in the Link ID bitmap subfield of the TWT teardown frame, it means that an STA attached to the same MLD is requesting the teardown of a single TWT protocol and that the STA is operating on the indicated link.

[0032] Figure 4 This disclosure illustrates an example scenario 400 under a proposed scheme for EMLSR TWT operation. According to the proposed scheme, an STA attached to an MLD can negotiate a separate (individual) TWT agreement with another STA attached to another MLD, with some exceptions. For example... Figure 4 As shown, one exception might be that if the Link ID bitmap subfield (or "Tear Down Link ID Bitmap Subfield") is not present in the TWT teardown frame, then MLD can send a TWT teardown frame on the link requesting the teardown of the TWT protocol. Figure 4 As shown, since TWT teardown frames without a Link ID bitmap subfield can be sent by STA 2 on Link 2, the TWT protocol on Link 2 (but not on Link 1) can be terminated or otherwise torn down. Another exception might be that if MLD wants to terminate all TWTs established on all links, MLD can set the bit value in the Link Bitmap subfield corresponding to all links established by MLD to 1.

[0033] Under the proposed scheme of this disclosure regarding the Negotiated Target Beacon Transmission Time (TBTT) and wake-up interval, a TBTT-scheduled STA intending to operate in power-saving mode can send a TWT request to the TBTT-scheduling AP, which identifies the wake-up TBTT of the first beacon frame and the wake-up interval between subsequent beacon frames that the STA wants to receive. Under the proposed scheme, the TWT request may include: (a) a Negotiation Type subfield equal to 1 and a TWT Setting Command field set to either a proposed TWT or a requested TWT; (b) the requested first wake-up TBTT included in the Target Wake Time field; (c) the requested wake-up interval between consecutive TBTTs in the TWT Mantissa and TWT Exponent fields; (d) the requested TBTT wake-up duration located in the Nominal Minimum TWT Wake Duration field; and (e) all other fields that may be reserved in the TWT element. Under the proposed scheme, an AP that receives a TWT request from an STA and schedules a TBTT with a value of 1 in the Negotiation Type subfield can respond by including a TWT response in the TWT Setting Command field indicating acceptance of the TWT, a standby TWT, or rejection of the TWT. In the case of including acceptance of the TWT, the TWT response may also include: (a) a Negotiation Type subfield equal to 1, (b) the allocated first wake-up TBTT in the Target Wake Time field, (c) the allocated wake-up interval between consecutive TBTTs in the TWT Mantissa and TWT Exponent fields, (d) the allocated TBTT wake-up duration in the Nominal Minimum TWT Wake Duration field, and (e) all other fields that can be retained in the TWT element.

[0034] Under the proposed scheme, after successful negotiation, a STA scheduled for TBTT can enter a sleep state and remain in power-saving mode unless otherwise required to stay awake, until its TSF matches the next negotiated wake-up TBTT. A STA scheduled for TBTT can remain awake to listen for beacon frames sent during the negotiated wake-up TBTT and can operate according to the rules used for STAs scheduled for TWT. If a STA scheduled for TBTT receives a beacon frame from the AP that scheduled the TBTT at or after the TBTT, it can enter a sleep state until the next wake-up TBTT unless otherwise required to stay awake. A STA scheduled for TBTT can enter a sleep state after the nominal minimum TBTT wake-up duration starting from the TBTT start time, unless otherwise required to stay awake. Furthermore, any STA that is a party to an established wake-up TBTT protocol can tear down the wake-up TBTT protocol by following the teardown procedure and setting the negotiation type subfield in the TWT teardown frame to 1.

[0035] According to the scheme for EMLSR TBTT negotiation proposed in this disclosure, a STA attached to a non-AP MLD (e.g., MLD 110) operating in EMLSR mode can negotiate the wake-up TBTT and wake-up interval with an AP attached to the AP MLD (MLD 120). When a first STA attached to a non-AP MLD (e.g., STA 1) negotiates the wake-up TBTT and wake-up interval with a first AP attached to the AP MLD (e.g., AP 1) to receive beacon frames on one of the EMLSR links, a second AP attached to the AP MLD (e.g., AP 2) can terminate a frame exchange initiated with a second STA attached to a non-AP MLD (e.g., STA 2) on another EMLSR link before the first AP attached to the same AP MLD schedules the transmission of beacon frames in the negotiated TBTT. This exchange is indicated in the EMLSR transition delay subfield. Alternatively or additionally, when a first STA attached to a non-AP MLD (e.g., STA 1) negotiates a wake-up TBTT and wake-up interval with a first AP attached to an AP MLD (e.g., AP 1) to receive a beacon frame on one of the EMLSR links, a second STA attached to a non-AP MLD (e.g., STA 2) that initiates frame switching on another EMLSR link may terminate TXOP at least one EMLSR conversion delay (indicated in the EMLSR conversion delay subfield) before the first STA attached to the same non-AP MLD receives the beacon frame in the negotiated TBTT.

[0036] Descriptive implementation

[0037] Figure 5 An example system 500, comprising at least example device 510 and example device 520, is illustrated according to an implementation of this disclosure. Each of devices 510 and 520 can perform various functions to implement the schemes, techniques, processes, and methods described herein relating to EMLSR TWT operation in wireless communications, including the various proposed designs, concepts, schemes, systems, and methods described above and the processes described below. For example, device 510 may be an example implementation of MLD 110, and device 520 may be an example implementation of MLD 120.

[0038] Each of devices 510 and 520 can be part of an electronic device, such as, but not limited to, a portable or mobile device, a wearable device, a wireless communication device, or a computing device. For example, each of devices 510 and 520 can be implemented in a smartphone, smartwatch, personal digital assistant, digital camera, or computing device such as a tablet, laptop, or notebook computer. Each of devices 510 and 520 can also be part of a machine-type device, which can be an IoT device, home device, wired communication device, or computing device, such as a fixed or static device. For example, each of devices 510 and 520 can be implemented in a smart thermostat, smart refrigerator, smart door lock, wireless speaker, or home control center. When implemented in or as a network device, devices 510 and / or 520 can be implemented in a network node (e.g., an access point in a WLAN).

[0039] In some embodiments, each of devices 510 and 520 may be implemented in the form of one or more integrated circuit (IC) chips, such as, but not limited to, one or more single-core processors, one or more multi-core processors, one or more Reduced Instruction Set Computing (RISC) processors, or one or more Complex Instruction Set Computing (CISC) processors. As an example, each of devices 510 and 520 may include... Figure 5 At least some of the components shown may, for example, include, respectively Figure 5 Processors 512 and 522 are shown in the diagram. Each of devices 510 and 520 may also include one or more other components (e.g., internal power supply, display device, and / or user interface device) unrelated to the solutions proposed in this disclosure, and therefore, for simplicity, none of such components (one or more) of devices 510 and 520 are listed in the diagram. Figure 5 As shown in the text, it will not be described further below.

[0040] In one aspect, each of processors 512 and 522 may be implemented as one or more single-core processors, one or more multi-core processors, one or more RISC processors, or one or more CISC processors. That is, even though the singular term "one processor" is used herein to refer to processors 512 and 522, according to the invention, each of processors 512 and 522 may include multiple processors in some implementations and a single processor in other implementations. In another aspect, each of processors 512 and 522 may be implemented as hardware (and, optionally, firmware) having electronic components, including, for example, but not limited to, one or more transistors, one or more diodes, one or more capacitors, one or more resistors, one or more inductors, one or more memristors, and / or one or more varistors, configured and arranged to achieve a specific purpose according to this disclosure. In other words, in at least some embodiments, each of processors 512 and 522 is a dedicated machine specifically designed, arranged, and configured to perform specific tasks, including tasks related to EMLSRTWT operation in wireless communication according to various embodiments of the invention.

[0041] In some implementations, device 510 may further include a transceiver 516 coupled to processor 512. Transceiver 516 may be capable of wirelessly transmitting and receiving data. In some implementations, device 520 may further include a transceiver 526 coupled to processor 522. Transceiver 526 may include a transceiver capable of wirelessly transmitting and receiving data. Transceiver 516 of device 510 and transceiver 526 of device 520 may communicate with each other via one or more of a plurality of links link 1 to link N (e.g., a first link and a second link), where N is a positive integer greater than 1.

[0042] In some embodiments, device 510 may further include a memory 514 coupled to and accessible by processor 512 and capable of storing data therein. In some embodiments, device 520 may further include a memory 524 coupled to and accessible by processor 522 and capable of storing data therein. Each of memory 514 and memory 524 may include a type of random access memory (RAM), such as dynamic RAM (DRAM), static RAM (SRAM), thyristor RAM (T-RAM), and / or zero-capacitance RAM (Z-RAM). Alternatively or additionally, each of memory 514 and memory 524 may include a type of read-only memory (ROM), such as mask ROM, programmable ROM (PROM), erasable programmable ROM (EPROM), and / or electrically erasable programmable ROM (EEPROM). Alternatively or additionally, each of memories 514 and 524 may include a type of non-volatile random access memory (NVRAM), such as flash memory, solid-state memory, ferroelectric RAM (FeRAM), magnetoresistive RAM (MRAM), and / or phase-change memory.

[0043] Each of devices 510 and 520 can be a communication entity capable of communicating with each other using various proposed schemes according to this disclosure. For illustrative purposes and not for limitation, device 510 is described below as having the capability of an MLD 110 that can be a non-AP MLD, and device 520 is described below as having the capability of an MLD 120 that can be an AP MLD. It is worth noting that although the example implementations described below are provided in the context of WLAN, they can also be implemented in other types of networks.

[0044] Under the proposed scheme of EMLSR TWT operation in wireless communication according to this disclosure, processor 512 of device 510, which is a first MLD (e.g., MLD 110), can enable EMLSR mode (e.g., put MLD 110 into EMLSR mode). Furthermore, processor 512 can establish concurrent TWT protocols via transceiver 516 with device 520, which is a second MLD (e.g., MLD 120), on multiple links including at least a first link and a second link. When establishing the concurrent TWT protocol, processor 512 can perform certain operations. For example, processor 512 can send a TWT request, as a first STA attached to the first MLD, to a first peer STA attached to the second MLD. This TWT request includes TWT elements, which include a link ID bitmap subfield indicating the multiple links requested for establishing the concurrent TWT protocol. Additionally, the processor 512 can receive a TWT response from a first peer STA as the first STA. This TWT response contains another TWT element, which includes another link ID bitmap subfield indicating multiple links that agree to establish a concurrent TWT protocol on it.

[0045] In some implementations, the TWT element may also include a Synchronize TWT Request subfield. In this case, all TWT SPs on multiple links can be aligned in response to a predefined value set in the Synchronize TWT Request subfield.

[0046] In some implementations, processor 512 can terminate the concurrent TWT agreement with the second MLD by sending a TWT teardown frame before switching from EMLSR mode to single radio mode.

[0047] In some implementations, when terminating a concurrent TWT protocol, the processor 512 can terminate the concurrent TWT protocol by terminating the TWT protocol on the second link in response to a TWT teardown frame indicating termination of the TWT protocol on the second link.

[0048] In some implementations, a TWT teardown frame may include at least a Link ID bitmap presence subfield, which indicates whether a Link ID bitmap subfield (as described above, or simply "Link ID bitmap subfield") is present in the TWT teardown frame. In this case, in response to the Link ID bitmap presence subfield indicating that a Link ID bitmap subfield is present in the TWT teardown frame, removing the Link ID bitmap subfield may indicate termination of one or more applicable links. Alternatively or additionally, a TWT teardown frame may include at least removing all TWT subfields. In this case, in response to predefined values ​​set in all TWT subfields, termination may include terminating concurrent TWT protocols on all multiple links.

[0049] In some implementations, upon terminating concurrent TWT protocols, processor 512 may, as a first STA, send a TWT teardown frame on a first link to a first peer STA to indicate termination of the corresponding TWT agreement on at least one of the plurality of links. Alternatively or additionally, upon terminating concurrent TWT protocols, processor 512 may, as a second STA attached to a first MLD, send a TWT teardown frame on a second link to a second peer STA attached to a second MLD, wherein the TWT teardown frame, without including the teardown link ID bitmap subfield, indicates termination of the corresponding TWT agreement on the second link.

[0050] In some implementations, processor 512 may perform additional operations. For example, processor 512 may act as a first STA in EMLSR mode to negotiate the TBTT and wake-up interval with a first peer STA attached to a second MLD. Furthermore, processor 512 may act as a first STA and receive one or more beacon frames from the first peer STA on one or more EMLSR links of a plurality of links, according to the negotiated TBTT and wake-up interval. In some implementations, the first MLD may be a non-AP MLD, and the second MLD may be an AP MLD, and the first peer STA may be a first AP.

[0051] In some implementations, processors 512 and 522 may perform certain operations upon receiving one or more beacon frames. For example, processor 522 may act as a second AP attached to the second MLD, terminating at least one EMLSR conversion delay in a frame exchange initiated by a second STA attached to the first MLD on another link of one or more EMLSR links before the first AP transmits each of the one or more beacon frames in the negotiated TBTT. Furthermore, processor 512 may act as the second STA, terminating at least one EMLSR conversion delay in a TXOP on that other link before the first STA receives each of the one or more beacon frames in the negotiated TBTT. In this case, the EMLSR conversion delay may be indicated in the EMLSR conversion delay subfield of the EML capability subfield in the common information field of the basic multilink element in the management frame transmitted between the first MLD and the second MLD.

[0052] Explanatory process

[0053] Figure 6 An example process 600 according to an embodiment of the present disclosure is illustrated. Process 600 may represent one aspect of a design, concept, scheme, system, and method that implements the various proposed above. More specifically, process 600 may represent one aspect of a proposed concept and scheme relating to EMLSR TWT operation in wireless communication according to the present disclosure. Process 600 may include one or more operations, actions, or functions, as illustrated in blocks 610 and 620 and sub-blocks 622 and 624. Although the blocks in the figures are illustrated as discrete blocks, the individual blocks of process 600 may be divided into other blocks, combined into fewer blocks, or eliminated, depending on the desired implementation. Furthermore, the blocks / sub-blocks of process 600 may be arranged in... Figure 6 The process can be executed in the order shown, or in a different order. Furthermore, one or more boxes / sub-boxes of process 600 can be executed repeatedly or iteratively. Process 600 can be implemented by or within devices 510 and 520 and any variations thereof. For illustrative purposes only and without limitation, process 600 is described in the context of devices 510 and 520 as MLD 110 (e.g., non-AP MLD) and MLD 120 (e.g., peer-to-peer STA MLD or AP MLD) in a wireless network (e.g., a WLAN) according to one or more IEEE 802.11 standards. Process 600 may begin at box 610.

[0054] At 610, process 600 may include processor 512 of device 510, which is a first MLD (e.g., MLD 110), enabling EMLSR mode (e.g., putting MLD 110 into EMLSR mode). Process 600 may proceed from 610 to 620.

[0055] At 620, process 600 may include processor 512 establishing a concurrent TWT protocol with device 520, which is a second MLD (e.g., MLD 120), on a multi-link consisting of at least a first link and a second link via transceiver 516. When establishing the concurrent TWT protocol, as shown in 622 and 624, process 600 may include processor 512 performing certain operations.

[0056] At 622, process 600 may include processor 512, acting as a first STA attached to a first MLD, sending a TWT request to a first peer STA attached to a second MLD. The TWT request includes a TWT element, which includes a link ID bitmap subfield indicating the multiple links requested for establishing a concurrent TWT protocol. Process 600 may proceed from 622 to 624.

[0057] At 624, process 600 may include processor 512 receiving a TWT response from a first peer STA as a first STA, the TWT response containing another TWT element, the other TWT element including another link ID bitmap subfield indicating multiple links that agree to establish concurrent TWT protocols on it.

[0058] In some implementations, the TWT element may also include a Synchronize TWT Request subfield. In this case, all TWT SPs on multiple links can be aligned in response to a predefined value set in the Synchronize TWT Request subfield.

[0059] In some implementations, process 600 may further include processor 512 terminating the concurrent TWT agreement with the second MLD by sending a TWT teardown frame before switching from EMLSR mode to single radio mode.

[0060] In some implementations, when terminating concurrent TWT protocols, process 600 may include processor 512 terminating concurrent TWT protocols by terminating the TWT protocol on the second link in response to a TWT teardown frame indicating termination of the TWT protocol on the second link.

[0061] In some implementations, a TWT teardown frame may include at least a Link ID bitmap presence subfield, which indicates whether the TWT teardown frame contains a TWT teardown subfield to remove. In this case, in response to the Link ID bitmap presence subfield indicating the presence of a TWT teardown subfield in the TWT teardown frame, removing the Link ID bitmap subfield may indicate termination of one or more applicable links. Alternatively or additionally, a TWT teardown frame may include at least removing all TWT subfields. In this case, in response to predefined values ​​set in removing all TWT subfields, termination may include terminating concurrent TWT protocols on all multiple links.

[0062] In some implementations, when terminating concurrent TWT protocols, process 600 may include processor 512 acting as a first STA sending a TWT teardown frame to a first peer STA on a first link to indicate termination of the corresponding TWT agreement on at least one of a plurality of links. Alternatively or additionally, when terminating concurrent TWT protocols, process 600 may include processor 512 acting as a second STA attached to a first MLD sending a TWT teardown frame to a second peer STA attached to a second MLD on a second link, wherein the TWT teardown frame indicates termination of the corresponding TWT agreement on the second link without including the teardown link ID bitmap subfield.

[0063] In some implementations, process 600 may further include processor 512 performing additional operations. For example, process 600 may include processor 512, acting as a first STA, negotiating the TBTT and wake-up interval with a first peer STA attached to a second MLD while in EMLSR mode. Furthermore, process 600 may include processor 512 acting as a first STA and receiving one or more beacon frames from the first peer STA on one or more EMLSR links of a plurality of links, based on the negotiated TBTT and wake-up interval. In some implementations, the first MLD may be a non-AP MLD, and the second MLD may be an AP MLD, and the first peer STA may be a first AP.

[0064] In some implementations, upon receiving one or more beacon frames, process 600 may include processor 512 performing certain operations. For example, process 600 may include a second AP attached to the second MLD, terminating frame exchange initiated with a second STA attached to the first MLD on another link of one or more EMLSR links by at least one EMLSR conversion delay before the first AP transmits each of the one or more beacon frames at the negotiated TBTT. Furthermore, process 600 may include the second STA terminating at least one EMLSR conversion delay on the other link via TXOP before the first STA receives each of the one or more beacon frames at the negotiated TBTT. In this case, the EMLSR conversion delay may be indicated in the EMLSR conversion delay subfield of the EML capability subfield in the common information field element of the basic multilink element in the management frame transmitted between the first MLD and the second MLD.

[0065] Supplementary Explanation

[0066] The topics described herein sometimes illustrate different components contained within or connected to different other components. It is to be understood that the architectures depicted in this way are merely examples, and many other architectures that can actually achieve the same functionality can be implemented. Conceptually, multiple components in any arrangement that achieve the same function are effectively “associated” to achieve the desired functionality. Therefore, any two components combined to achieve a particular function can be considered “associated” with each other to achieve the desired functionality, regardless of the architecture or intermediate components. Similarly, any two components so associating can also be considered “operably connected” or “operably coupled” to each other to achieve the desired functionality, and any two components that can be so associating can also be considered “operably coupled to each other” to achieve the desired functionality. Specific examples of operational coupling include, but are not limited to, physically pairable and / or physically interacting components and / or wirelessly interactive and / or logically interacting and / or logically interactive components.

[0067] Furthermore, regarding any plural and / or singular forms used herein, those skilled in the art can convert plural forms to singular forms and / or singular forms to plural forms as appropriate to the context and / or the application. The various singular / plural forms described herein are merely for clarity.

[0068] Furthermore, those skilled in the art will understand that the terms used herein, particularly those in the appended claims, such as the body of the appended claims, are generally intended to be “open-ended” terms. For example, the term “comprising” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “at least having,” and the plural term “comprising” should be interpreted as “including but not limited to.” Those skilled in the art will further understand that if an intention is to introduce a particular quantity into the claims, such intention will be explicitly stated in the claims, and without such a statement, such intention does not exist. For example, to aid understanding, the appended claims may include introductory phrases such as “at least one” and “one or more” to introduce the claims. However, the use of these phrases should not be construed as implying that a claim statement introduced by the indefinite article "a" or "an" is limited to any particular claim containing only one implementation of such a statement, even if the same claim includes the introductory phrases "one or more" or "at least one," and indefinite articles such as "a" or "an," for example, "a" and / or "an," should be interpreted as "at least one" or "one or more"; this interpretation also applies to claims statements introduced by definite articles. Furthermore, even if a specific number of introductory claim statements are explicitly cited, those skilled in the art will recognize that such citations should be interpreted as indicating at least the number cited; for example, the simple statement "two statements," without other modifiers, indicates at least two statements, or two or more statements. Furthermore, in cases where phrases like "at least one of A, B, and C" are used, such a structure is generally intended to be understood by those skilled in the art in the sense of the convention. For example, "a system having at least one of A, B, and C" includes, but is not limited to, having only a single A, a single B, a single C, A and B together, A and C together, B and C together, and / or A, B, and C together, etc. In cases where phrases like "at least one of A, B, or C" are used, such a structure is generally intended to be understood by those skilled in the art in the sense of the convention. For example, "a system having at least one of A, B, or C" will include, but is not limited to, having only a single A, a single B, a single C, A and B together, A and C together, B and C together, and / or A, B, and C together, etc. Those skilled in the art will further understand that any separating words and / or phrases presenting two or more alternative terms, whether appearing in the specification, claims, or drawings, should be understood to include one of the terms, any one of the terms, or both. For example, the phrase “A or B” would be understood to include the possibility of “A” or “B” or “A and B”.

[0069] As can be understood from the foregoing, various implementations of this disclosure have been described herein for illustrative purposes, and various modifications may be made without departing from the scope and spirit of this disclosure. Therefore, the various implementations disclosed herein are not intended to limit the true scope and spirit indicated by the appended claims.

Claims

1. A wireless communication method, characterized in that, include: The first multi-link device, MLD, enables enhanced multi-link single-radio EMLSR mode; and The first MLD and the second MLD establish a concurrent target wake-up time (TWT) protocol on a multi-link consisting of at least a first link and a second link; The concurrent TWT establishment protocol includes: The first STA attached to the first MLD sends a TWT request to the first peer STA attached to the second MLD. The TWT request contains a TWT element, which includes a Link Identifier ID bitmap subfield that indicates the multiple links requested for establishing a concurrent TWT protocol. The first STA receives a TWT response from the first peer STA, the TWT response containing another TWT element, the other TWT element including another link ID bitmap subfield, the other link ID bitmap subfield indicating multiple links that agree to establish concurrent TWT protocols on it; The first MLD sends a TWT teardown frame to terminate the concurrent TWT agreement with the second MLD before switching from the EMLSR mode to the single radio mode.

2. The wireless communication method as described in claim 1, characterized in that, The TWT element also includes a Synchronous TWT Request subfield, wherein all TWT service cycles on the multiple links are aligned in response to a predefined value set in the Synchronous TWT Request subfield.

3. The wireless communication method as described in claim 1, characterized in that, Terminating the concurrent TWT protocol includes: The response indicates that the TWT teardown frame of the TWT protocol on the second link is terminated, thereby terminating the concurrent TWT protocol on the second link.

4. The wireless communication method as described in claim 1, characterized in that, The TWT teardown frame includes at least a Link ID bitmap presence subfield, which indicates whether the TWT teardown frame contains a teardown Link ID bitmap subfield, and wherein, in response to the Link ID bitmap presence subfield indicating that the teardown Link ID bitmap subfield exists in the TWT teardown frame, the teardown Link ID bitmap subfield indicates one or more links to which the termination applies.

5. The wireless communication method as described in claim 1, characterized in that, The TWT teardown frame includes at least tearing down all TWT subfields, and in response to a predefined value set in the teardown of all TWT subfields, the termination includes terminating the concurrent TWT protocol on all the multiple links.

6. The wireless communication method as described in claim 1, characterized in that, Terminating the concurrent TWT protocol includes: The first STA sends the TWT teardown frame to the first peer STA on the first link to indicate the termination of the corresponding TWT agreement on at least one of the plurality of links.

7. The wireless communication method as described in claim 1, characterized in that, Terminating the concurrent TWT protocol includes: The second STA attached to the first MLD sends the TWT teardown frame to the second peer STA attached to the second MLD on the second link, wherein the TWT teardown frame indicates the termination of the corresponding TWT agreement on the second link without including the teardown link ID bitmap subfield.

8. The wireless communication method as described in claim 1, characterized in that, Further includes: The first STA attached to the first MLD, when in EMLSR mode, negotiates the Target Beacon Frame Transmission Time (TBTT) and the wake-up interval with the first peer STA attached to the second MLD; and The first STA receives one or more beacon frames from the first peer STA on one or more EMLSR links of the plurality of links, according to the negotiated TBTT and the wake-up interval; The first MLD includes a non-AP MLD, the second MLD includes an AP MLD, and the first peer STA includes a first AP.

9. The wireless communication method as described in claim 8, characterized in that, Further includes: Before the first AP sends each of one or more beacon frames in the negotiated TBTT, the second AP attached to the second MLD terminates the frame exchange with the second STA attached to the first MLD on another link of one or more EMLSR links, at least one EMLSR conversion delay. and Before the first STA receives each of one or more beacon frames in the negotiated TBTT, the second STA terminates at least one EMLSR conversion delay on the other link via TXOP; The EMLSR conversion delay is indicated in the EML capability subfield of the basic multilink element in the management frame transmitted between the first MLD and the second MLD.

10. An apparatus implemented in a first multi-link device (MLD), characterized in that, include: A transceiver configured to communicate wirelessly with a second MLD; and A processor coupled to the transceiver, wherein the processor is configured to perform the following operations: Enable enhanced multi-link single-radio EMLSR mode; and The transceiver and the second MLD establish a concurrent TWT protocol on a multi-link system comprising at least a first link and a second link. The concurrent TWT establishment protocol includes: As the first STA attached to the first MLD, it sends a TWT request to the first peer STA attached to the second MLD. The TWT request contains a TWT element, which includes a Link Identifier ID bitmap subfield, indicating the multiple links requested for establishing a concurrent TWT protocol. As the first STA receives a TWT response from the first peer STA, the TWT response contains another TWT element, which includes another link ID bitmap subfield indicating multiple links that agree to establish concurrent TWT protocols on it; Before switching from the EMLSR mode to the single radio mode, a TWT teardown frame is sent via the transceiver to terminate the concurrent TWT agreement with the second MLD.

11. The apparatus as claimed in claim 10, characterized in that, The TWT element also includes a Synchronous TWT Request subfield, wherein all TWT service cycles on the multiple links are aligned in response to a predefined value set in the Synchronous TWT Request subfield.

12. The apparatus as claimed in claim 10, characterized in that, Terminating the concurrent TWT protocol includes: The response indicates that the TWT teardown frame of the TWT protocol on the second link is terminated, thereby terminating the concurrent TWT protocol on the second link.

13. The apparatus as claimed in claim 10, characterized in that, The TWT teardown frame includes at least a Link ID bitmap presence subfield, which indicates whether the TWT teardown frame contains a teardown Link ID bitmap subfield, and wherein, in response to the Link ID bitmap presence subfield indicating that the teardown Link ID bitmap subfield exists in the TWT teardown frame, the teardown Link ID bitmap subfield indicates one or more links to which the termination applies.

14. The apparatus as claimed in claim 10, characterized in that, The TWT teardown frame includes at least tearing down all TWT subfields, and in response to a predefined value set in the teardown of all TWT subfields, the termination includes terminating the concurrent TWT protocol on all the multiple links.

15. The apparatus as claimed in claim 10, characterized in that, Terminating the concurrent TWT protocol includes: The first STA sends the TWT teardown frame to the first peer STA on the first link to indicate the termination of the corresponding TWT agreement on at least one of the multiple links.

16. The apparatus as claimed in claim 10, characterized in that, Terminating the concurrent TWT protocol includes: As a second STA attached to the first MLD, the second peer STA on the second link sends the TWT teardown frame to the second peer STA attached to the second MLD, wherein the TWT teardown frame indicates the termination of the corresponding TWT agreement on the second link without including the teardown link ID bitmap subfield.

17. The apparatus as claimed in claim 10, characterized in that, The processor is further configured to perform the following operations: When the first STA, which is attached to the first MLD, is in the EMLSR mode, it negotiates the target beacon frame transmission time (TBTT) and wake-up interval with the first peer STA attached to the second MLD. and As the first STA, it receives one or more beacon frames from the first peer STA on one or more EMLSR links of the plurality of links according to the negotiated TBTT and the wake-up interval; The first MLD includes a non-AP MLD, the second MLD includes an AP MLD, and the first peer STA includes a first AP.

18. The apparatus as claimed in claim 17, characterized in that, Before the first AP transmits each of one or more beacon frames in the negotiated TBTT, the second AP attached to the second MLD terminates the frame exchange with the second STA attached to the first MLD on another link of one or more EMLSR links, involving at least one EMLSR conversion delay; and the processor is further configured to perform the following operations: Before the first STA receives each of one or more beacon frames in the negotiated TBTT, the second STA terminates at least one EMLSR conversion delay on the other link as a TXOP; The EMLSR conversion delay is indicated in the EML capability subfield of the basic multilink element in the management frame transmitted between the first MLD and the second MLD.

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