Receiving group-addressed frames for non-access point (non-AP) multilink devices (MLD)

Abstract

Some aspects of the present disclosure relate to wireless communication, and more particularly, to multi-link communication. A method that can be performed by an access point (AP) multi-link device (MLD) includes establishing multiple links for communication with a non-AP MLD, where one or more non-AP MLDs including the non-AP MLD communicate with the AP on each link of the multiple links, and taking one or more actions designed to ensure that the non-AP MLD can receive a group-addressed frame. The non-AP MLD is operating in an enhanced multi-link single-radio (EMLSR) mode.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 17 / 454,022, filed November 8, 2021, which is assigned to the assignee of the present application and is expressly incorporated by reference in its entirety as if fully set forth below and for all applicable purposes.

[0002] Certain aspects of the present disclosure relate generally to wireless communications, and more specifically, to multi-link communications. [Background technology]

[0003] Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single Carrier FDMA (SC-FDMA) networks.

[0004] To address the problem of increasing bandwidth requirements for wireless communication systems, different schemes have been developed to enable multiple user terminals to communicate with a single access point by sharing channel resources while achieving high data throughput. Multiple Input Multiple Output (MIMO) technology represents one such approach that has emerged as a popular technology for communication systems. MIMO technology has been adopted in several wireless communication standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. IEEE 802.11 refers to a set of air interface standards for Wireless Local Area Networks (WLANs) developed by the IEEE 802.11 committee for short-range communication (such as tens of meters to hundreds of meters). Summary of the Invention

[0005] The systems, methods, and devices of the present disclosure each have several innovative aspects, no single aspect of which is solely responsible for the desirable properties disclosed herein.Several aspects of the present disclosure relate generally to wireless communications, and more specifically to techniques for link management for managing multi-link communications.

[0006] Some aspects of the present disclosure provide a method of wireless communication in an access point (AP) multi-link device (MLD), the method generally including: establishing a plurality of links for communication with a non-AP MLD, where one or more non-AP MLDs including the non-AP MLD communicate with an AP on each link of the plurality of links; and taking one or more actions designed to ensure that the non-AP MLD can receive group-addressed frames.

[0007] Some aspects of the present disclosure provide a method of wireless communication performed by a non-AP MLD operating in an enhanced multi-link single radio (EMLSR) mode. The method generally includes establishing multiple links for communication with an AP MLD, where one or more non-AP MLDs including the non-AP MLD communicate with an AP on each of the multiple links, and taking one or more actions designed to ensure that the non-AP MLD can receive group-addressed frames.

[0008] Some aspects of the present disclosure may be implemented in an apparatus for wireless communication by an AP MLD. The apparatus generally includes a memory and a processor coupled to the memory, where the processor and the memory are configured to establish a plurality of links for communication with a non-AP MLD, where one or more non-AP MLDs including the non-AP MLD communicate with an AP on each link of the plurality of links, and take one or more actions designed to ensure that the non-AP MLD can receive group-addressed frames.

[0009] Some aspects of the disclosure may be implemented in an apparatus for wireless communication by a non-AP MLD operating in an EMLSR mode. The apparatus generally includes a memory and a processor coupled to the memory, where the processor and memory are configured to establish a plurality of links for communication with an AP MLD, where one or more non-AP MLDs including the non-AP MLD communicate with an AP on each link of the plurality of links, and take one or more actions designed to ensure that the non-AP MLD can receive group-addressed frames.

[0010] Some aspects of the present disclosure may be implemented in an apparatus for wireless communication with an AP MLD. The apparatus generally includes means for establishing a plurality of links for communication with a non-AP MLD, where one or more non-AP MLDs including the non-AP MLD communicate with an AP on each link of the plurality of links, and means for taking one or more actions designed to ensure that the non-AP MLD can receive group-addressed frames.

[0011] Some aspects of the present disclosure may be implemented in an apparatus for wireless communication with a non-AP MLD operating in an EMLSR mode. The apparatus generally includes means for establishing a plurality of links for communication with an AP MLD, where one or more non-AP MLDs including the non-AP MLD communicate with an AP on each link of the plurality of links, and means for taking one or more actions designed to ensure that the non-AP MLD can receive group-addressed frames.

[0012] Some aspects of the present disclosure may be implemented in a computer-readable medium having computer-executable code stored thereon. The computer-readable medium having computer-executable code stored thereon generally includes code for establishing a plurality of links for communication with non-AP MLDs, where one or more non-AP MLDs including the non-AP MLD communicate with an AP on each of the plurality of links, and code for taking one or more actions designed to ensure that the non-AP MLDs can receive group-addressed frames.

[0013] Some aspects of the present disclosure may be implemented in a computer-readable medium having computer-executable code stored thereon. The computer-readable medium having computer-executable code stored thereon generally includes code for establishing a plurality of links for communication with an AP MLD, where one or more non-AP MLDs, including the non-AP MLD, communicate with an AP on each of the plurality of links, and code for taking one or more actions designed to ensure that the non-AP MLD can receive group-addressed frames.

[0014] To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of only a few of the various ways in which the principles of the various aspects may be employed.

[0015] So that the above-mentioned features of the present disclosure may be understood in detail, a more particular description thereof, briefly summarized above, may be had by reference to the embodiments, some of which are illustrated in the accompanying drawings, in which it should be noted, however, that the accompanying drawings illustrate only some typical embodiments of the present disclosure, and that the description may admit of other equally effective embodiments. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 illustrates an example wireless communication network in accordance with certain aspects of the present disclosure. [Diagram 2] 1 is a block diagram of an example access point (AP) and example wireless stations (STAs) in accordance with certain aspects of the present disclosure. [Diagram 3] 1 illustrates an example wireless device in accordance with certain aspects of the present disclosure. [Figure 4]FIG. 2 is a block diagram illustrating an example multi-link operation between multi-link devices (MLDs) in accordance with certain aspects of the present disclosure. [Diagram 5] 1 is an example transmission timeline illustrating a trigger frame being transmitted prior to the transmission of a group addressing frame in accordance with certain aspects of the disclosure. [Figure 6] 1 is an example transmission timeline illustrating the transmission of a group-addressed frame at a given time in accordance with certain aspects of the present disclosure. [Figure 7A] 1 illustrates an example scenario for protecting group-addressed frame reception in accordance with certain aspects of the present disclosure. [Figure 7B] 1 illustrates an example scenario for protecting group-addressed frame reception in accordance with certain aspects of the present disclosure. [Figure 8A] 1 illustrates an example scenario in which a virtual quiet period may be configured on one or more links established between an AP and a non-AP MLD, in accordance with certain aspects of the present disclosure. [Figure 8B] 1 illustrates an example scenario in which a virtual quiet period may be configured on one or more links established between an AP and a non-AP MLD, in accordance with certain aspects of the present disclosure. [Figure 9] 1 is an example transmission timeline illustrating a scenario in which knowledge of the frame transmission rate for each link may be useful for non-AP MLD, in accordance with certain aspects of the disclosure. [Figure 10] 1 is an example transmission timeline illustrating a scenario in which a frame exchange sequence is initiated by a non-AP MLD, in accordance with certain aspects of the disclosure. [Figure 11] 1 is an example transmission timeline illustrating a scenario in which a non-AP MLD decides to participate in a first frame exchange sequence and ignore a second frame exchange sequence initiated by an AP, in accordance with certain aspects of the disclosure. [Figure 12]1 is an example transmission timeline illustrating a scenario in which a non-AP MLD is involved in a first frame exchange sequence and determines to signal the unavailability of the non-AP MLD for a second frame exchange sequence initiated by an AP, in accordance with certain aspects of the disclosure. [Figure 13] 1 is an example transmission timeline illustrating a scenario in which an uplink (UL) frame is transmitted by a non-AP MLD to terminate a frame exchange sequence on an Enhanced Multi-Link Single Radio (EMLSR) link, in accordance with certain aspects of the present disclosure. [Figure 14] 1 is an example transmission timeline illustrating a scenario in which an unsolicited frame is transmitted by a non-AP MLD to indicate unavailability of the non-AP MLD on an EMLSR link, in accordance with certain aspects of the disclosure. [Figure 15] 1 is a flow diagram illustrating example operations for wireless communication with AP MLD in accordance with certain aspects of the present disclosure. [Figure 16] 1 is a flow diagram illustrating example operations for wireless communication with non-AP MLD in accordance with certain aspects of the present disclosure. [Figure 17] 1 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein, in accordance with aspects of the present disclosure. [Figure 18] 1 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein, in accordance with aspects of the present disclosure.

[0017] For ease of understanding, wherever possible, the same reference numbers have been used to designate identical elements common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized in other embodiments without specific recitation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Aspects of the present disclosure provide an apparatus, method, processing system, and computer-readable medium for handling multi-link operations (MLO).

[0019] In some aspects, MLO can be implemented using an enhanced multi-link single radio (EMLSR) architecture. An MLD operating in EMLSR mode can only transmit and receive (e.g., transmit and receive data frames, management frames, etc.) over a single radio. Thus, when an MLD is transmitting and receiving frames on one EMLSR link, the MLD may not be able to transmit or receive frames on other EMLSR link(s) enabled for the MLD. In other words, an MLD can only transmit and receive on one link at a time. If a group-addressed frame is sent to an MLD on one EMLSR link (e.g., a first link) but the MLD is in a full-capability state on another EMLSR link (e.g., a second link), the MLD may miss receiving the group-addressed frame on the first link since the MLD can only transmit and receive frames from the AP MLD on one link at a time (e.g., in a full-capability state).

[0020] Aspects herein present techniques for facilitating reception of group-addressed frame(s) in an MLD, given the single-radio constraint of the MLD. According to aspects described herein, an access point (AP) MLD and / or a non-AP MLD in communication with an AP MLD can take one or more actions designed to ensure that the non-AP MLD can receive the group-addressed frame(s).

[0021] Various aspects of the present disclosure will be described more fully below with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as being limited to any specific structure or function presented throughout the present disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein, those skilled in the art will appreciate that the scope of the present disclosure is intended to encompass any aspect of the present disclosure disclosed herein, whether implemented independently of or in combination with any other aspect of the present disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects described herein. In addition, the scope of the present disclosure is intended to encompass such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the present disclosure described herein. It should be understood that any aspect of the present disclosure disclosed herein may be embodied by one or more elements of a claim.

[0022] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects.

[0023] Although specific aspects are described herein, numerous variations and permutations of these aspects fall within the scope of the present disclosure. Although some benefits and advantages of the preferred aspects are described, the scope of the present disclosure is not limited to any particular benefit, application, or purpose. Rather, the aspects of the present disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the figures and the following description of the preferred aspects. The detailed description and drawings are merely illustrative of the present disclosure, rather than limiting, the scope of the present disclosure being defined by the appended claims and their equivalents.

[0024] The techniques described herein can be used for various broadband wireless communication systems, including communication systems based on orthogonal multiplexing schemes. Examples of such communication systems include Spatial Division Multiple Access (SDMA) systems, Time Division Multiple Access (TDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems, etc. SDMA systems may utilize sufficiently different directions to simultaneously transmit data belonging to multiple user terminals. TDMA systems allow multiple user terminals to share the same frequency channel by dividing the transmission signal into different time slots, each time slot being assigned to a different user terminal. OFDMA systems utilize Orthogonal Frequency Division Multiplexing (OFDM), a modulation technique that partitions the entire system bandwidth into multiple orthogonal subcarriers. These subcarriers may also be referred to as tones, bins, etc. In OFDM, each subcarrier can be independently modulated with data. An SC-FDMA system may utilize Interleaved FDMA (IFDMA) for transmitting on subcarriers distributed across the system bandwidth, Localized FDMA (LFDMA) for transmitting on blocks of adjacent subcarriers, or Enhanced FDMA (EFDMA) for transmitting on multiple blocks of adjacent subcarriers. In general, modulation symbols are sent with OFDM in the frequency domain and with SC-FDMA in the time domain.

[0025] The teachings herein may be incorporated into (e.g., implemented within or performed by) various wired or wireless devices (e.g., nodes). In some aspects a wireless node implemented in accordance with the teachings herein may comprise an access point or an access terminal.

[0026] An access point ("AP") may comprise, be implemented as, or be known as a Node B, Radio Network Controller ("RNC"), evolved Node B (eNB), base station controller ("BSC"), base transceiver station ("BTS"), base station ("BS"), transceiver function ("TF"), wireless router, wireless transceiver, basic service set ("BSS"), enhanced service set ("ESS"), radio base station ("RBS"), or some other terminology.

[0027] An access terminal ("AT") may comprise, be implemented as, or be known as a subscriber station, subscriber unit, mobile station (MS), remote station, remote terminal, user terminal, user agent, user device, user equipment, user station, or some other terminology. In some implementations, an access terminal may comprise a cellular telephone, a cordless telephone, a session initiation protocol ("SIP") telephone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a handheld device with wireless connectivity, a station ("STA"), or some other suitable processing device connected to a wireless modem. Thus, one or more aspects taught herein may be incorporated into a telephone (such as a mobile phone or smartphone), a computer (such as a laptop), a tablet, a portable communication device, a portable computing device (such as a personal data assistant), an entertainment device (such as a music or video device, or satellite radio), a global positioning system (GPS) device, or any other suitable device configured to communicate via a wireless or wired medium. In some aspects, the node is a wireless node. Such a wireless node may, for example, provide connectivity for or to a network (eg, a wide area network such as the Internet or a cellular network) via a wired or wireless communication link.

[0028] Example Wireless Communication System FIG. 1 illustrates an exemplary wireless communication system 100 according to some aspects of the present disclosure. The system 100 may be a multiple-input multiple-output (MIMO) / multi-link operation (MLO) system 100. As shown in FIG. 1, an access point (AP) 110 includes a frame manager 112 that may be configured to take one or more actions designed to ensure that a non-AP multi-link device (MLD) can receive a group-addressed frame according to some aspects of the present disclosure. A wireless station (STA) 120a includes a frame manager 122 that may be configured to take one or more actions designed to ensure that a non-AP MLD can receive a group-addressed frame according to some aspects of the present disclosure. In an aspect, the AP 110 and the wireless station 120a may be MLDs as further described herein with respect to FIG. 3.

[0029] For simplicity, only one AP 110 is shown in FIG. 1. An AP is generally a fixed station that communicates with wireless STAs and may also be referred to as a base station (BS) or some other terminology. A wireless STA may be fixed or mobile and may also be referred to as a mobile STA, wireless device, or some other terminology. An AP 110 may communicate with one or more wireless STAs 120 at any given moment on a downlink (DL) and / or an uplink (UL). The DL (i.e., forward link) is a communication link from the AP 110 to the wireless STAs 120, and the UL (i.e., reverse link) is a communication link from the wireless STAs 120 to the AP 110. A wireless STA 120 may also communicate peer-to-peer with another wireless STA 120 via a direct link, such as, for example, a tunneled direct link setup (TDLS). A system controller 130 may be in communication with the access points and may provide coordination and control for the access points.

[0030] Although the following disclosure describes wireless STAs 120 capable of communicating via spatial division multiple access (SDMA), in some aspects the wireless STAs 120 may also include some wireless STAs 120 that do not support SDMA. Thus, in such aspects, the AP 110 may be configured to communicate with both SDMA and non-SDMA wireless STAs 120. This approach may advantageously allow older version wireless STAs 120 ("legacy" stations) to remain deployed in the enterprise, extending their useful life, while allowing newer SDMA wireless STAs 120 to be introduced as appropriate.

[0031] The system 100 employs multiple transmit antennas and multiple receive antennas for data transmission on the DL and UL. apThe set of K selected wireless stations 120 collectively represents the multiple-input for DL ​​transmissions and the multiple-input for UL transmissions. In the case of pure SDMA, if the data symbol streams for the K wireless STAs are not multiplexed in code, frequency, or time by any means, then the number of selected wireless stations 120 may be N. ap It is desirable that K ≥ 1. If the data symbol streams can be multiplexed using TDMA techniques, different code channels in the case of CDMA, disjoint sets of subbands in the case of OFDM, etc., then K can be a factor of N ap Each selected wireless STA transmits user-specific data to the access point and / or receives user-specific data from the access point. In general, each selected wireless STA may have one or more antennas (i.e., N sta ≧1). The K selected wireless STAs may have the same number of antennas or different numbers of antennas.

[0032] The system 100 may be a time division duplex (TDD) system or a frequency division duplex (FDD) system. For a TDD system, the DL and UL share the same frequency band. For an FDD system, the DL and UL use different frequency bands. The system 100 may also utilize a single carrier or multiple carriers for transmission. Each wireless STA may be equipped with a single antenna or multiple antennas. The system 100 may also be a TDMA system if the wireless STAs 120 share the same frequency channel by dividing transmission / reception into different time slots, with each time slot being assigned to a different wireless STA 120.

[0033] 2 illustrates a block diagram of an AP 110 and two wireless STAs 120m and 120x in a MIMO / MLO system such as system 100, according to some aspects of the disclosure. In some aspects, the AP 110 and / or the wireless STAs 120m and 120x may perform various techniques to ensure that non-AP MLDs can receive group-addressed frames. For example, the AP 110 and / or the wireless STAs 120m and 120x may include respective frame managers as described herein with respect to FIG.

[0034] The AP110 is ap The wireless STA 120m is equipped with N antennas 224a to 224t. sta,m The wireless STA120x is equipped with 252ma to 252mu antennas. sta,x The AP 110 includes antennas 252xa-252xu. The AP 110 is a transmitting entity in DL and a receiving entity in UL. Each wireless STA 120 is a transmitting entity in UL and a receiving entity in DL. As used herein, a "transmitting entity" is an independently operating apparatus or device capable of transmitting data over a wireless channel, and a "receiving entity" is an independently operating apparatus or device capable of receiving data over a wireless channel. The term communication generally refers to transmitting, receiving, or both. In the following description, the subscript "DL" refers to downlink, the subscript "UL" refers to uplink, and the subscript "DL" refers to uplink. UL N wireless STAs are selected for simultaneous transmission on the uplink, DL N wireless STAs are selected for simultaneous transmission on the downlink, UL is N DL may or may not be equal to N UL and N DL may be a static value or may change for each scheduling interval. Beam-steering or some other spatial processing technique may be used at the access point and the wireless station.

[0035] On the UL, for each wireless STA 120 selected for UL transmission, a transmit (TX) data processor 288 receives traffic data from a data source 286 and control data from the controller 280. The TX data processor 288 processes (e.g., encodes, interleaves, and modulates) the traffic data for the wireless station based on a coding and modulation scheme associated with the rate selected for the wireless STA and provides a data symbol stream. A TX spatial processor 290 performs spatial processing on the data symbol stream and provides Ns ta,m N antennas sta,m Each transceiver (TMTR) 254 receives and processes (e.g., converts to analog, amplifies, filters, and frequency upconverts) a respective transmit symbol stream to generate an uplink signal. sta,m The transceivers 254 are N sta,m N for transmission from antennas 252 sta,m UL signals to the AP 110.

[0036] N UL The wireless STAs may be scheduled for simultaneous transmission on the uplink, each performing spatial processing on its data symbol stream and transmitting its set of transmit symbol streams on the UL to the AP 110.

[0037] In AP110, N ap The antennas 224a through 224ap transmit all N UL 10, each of which receives UL signals from one or more wireless STAs. Each antenna 224 provides a received signal to a respective transceiver (RCVR) 222. Each transceiver 222 performs processing complementary to that performed by transceiver 254 and provides a received symbol stream. A receive (RX) spatial processor 240 comprises: ap N from the transceivers 222 apperforming receiver spatial processing on the N received symbol streams; UL The Rx data processor 242 provides uplink recovered data symbol streams. The receiver spatial processing is performed in accordance with Channel Correlation Matrix Inversion (CCMI), Minimum Mean Squared Error (MMSE), Soft Interference Cancellation (SIC), or some other technique. Each recovered UL data symbol stream is an estimate of the data symbol stream transmitted by a respective wireless station. The Rx data processor 242 processes (e.g., demodulates, deinterleaves, and decodes) each recovered uplink data symbol stream in accordance with the rate used for that stream to obtain decoded data. The decoded data for each wireless STA may be provided to a data sink 244 for storage and / or to controller 230 for further processing.

[0038] On the DL, at the AP 110, the TX data processor 210 determines N DL The TX data processor 210 receives traffic data for the N wireless stations from a data source 208, control data from a controller 230, and possibly other data from a scheduler 234. Various types of data may be sent on different transport channels. The TX data processor 210 processes (e.g., encodes, interleaves, and modulates) the traffic data for each wireless station based on the rate selected for that wireless station. ... DL The DL data symbol streams are DL The TX spatial processor 220 provides N DL performing spatial processing (such as precoding or beamforming, as described in this disclosure) on the DL data symbol streams; ap N transmit symbol streams ap Each transceiver 222 receives and processes a respective transmit symbol stream to generate a DL signal. ap The transceivers 222 are N apN for transmission from antennas 224 ap This DL signal is provided to the wireless STA.

[0039] In each wireless STA 120, N sta,m The antennas 252 are connected to the access point 110 through ap Each transceiver 254 processes a received signal from an associated antenna 252 and provides a received symbol stream. The RX spatial processor 260 receives N DL signals. sta,m N out of 254 transceivers sta,m The RX data processor 270 performs receiver spatial processing on the received symbol streams and provides a recovered DL data symbol stream to the wireless station. The receiver spatial processing is performed in accordance with CCMI, MMSE, or some other technique. The RX data processor 270 processes (e.g., demodulates, deinterleaves, and decodes) the recovered DL data symbol stream to obtain decoded data for the wireless station.

[0040] In each wireless STA 120, a channel estimator 278 estimates the DL channel response and provides a DL channel estimate, which may include a channel gain estimate, an SNR estimate, a noise variance, etc. Similarly, a channel estimator 228 estimates the UL channel response and provides a UL channel estimate. The controller 280 for each wireless STA typically calculates the downlink channel response matrix H dn,m The controller 230 derives a spatial filter matrix for the wireless station based on the effective UL channel response matrix H up,eff The controller 230 and 280 also control the operation of various processing units in the AP 110 and the wireless STA 120, respectively.

[0041] 3 illustrates various components that may be utilized in a wireless device 302 that may be used in the system 100 according to some aspects of the disclosure. The wireless device 302 is one example of a device that may be configured to implement various methods described herein. The wireless device 302 may be an AP 110 or a user terminal.

[0042] The wireless device 302 may include a processor 304 that controls the operation of the wireless device 302. The processor 304 may also be referred to as a central processing unit (CPU). The memory 306 may include both read-only memory (ROM) and random access memory (RAM) and provides instructions and data to the processor 304. A portion of the memory 306 may also include non-volatile random access memory (NVRAM). The processor 304 typically performs logical and arithmetic operations based on program instructions stored in the memory 306. The instructions in the memory 306 may be executable to implement the methods described herein.

[0043] The wireless device 302 may also include a housing 308 that may include a transmitter 310 and a receiver 312 to enable transmission and reception of data between the wireless device 302 and a remote location. The transmitter 310 and receiver 312 may be combined into a transceiver 314. Single or multiple transmit antennas 316 may be attached to the housing 308 and may be electrically coupled to the transceiver 314. The wireless device 302 may also include multiple transmitters, multiple receivers, and multiple transceivers (not shown).

[0044] The wireless device 302 may also include a signal detector 318 that can be used to detect and quantify the level of signals received by the transceiver 314. The signal detector 318 may detect such signals as total energy, energy per subcarrier per symbol, power spectral density, and other signals. The wireless device 302 may also include a digital signal processor (DSP) 320 for use in processing the signals.

[0045] The various components of the wireless device 302 may be coupled together by a bus system 322, which may include a power bus, a control signal bus, and a status signal bus in addition to a data bus.

[0046] Some aspects of the present disclosure are directed to apparatuses and techniques for implementing multi-link communication. For example, some aspects provide techniques for managing data flows across multiple links by MLD. Multiple bands can be implemented for a wireless device. For example, a wireless device may support at least one of a 2.4 GHz band, a 5 GHz band, or a 6 GHz band and be capable of operating on two or more links that span across these bands. In multi-link communication, a data flow can be transmitted across multiple wireless links that may be associated with different bands.

[0047] In some wireless communication networks (e.g., 802.11be networks), the MLD may be a wireless communication device having multiple associated APs 110 or STAs 120. The MLD may have a single MAC service access point (SAP) for the logical link control (LLC) layer. The MLD may have a MAC address that uniquely identifies the MLD management entity. The MLD may support various MLOs. In aspects, the MLO may include multi-band aggregation, in which two or more channels in different bands (e.g., 2.4, 5, and 6 gigahertz (GHz) bands) are combined to achieve higher transmission rates. In aspects, the 6 GHz band may include a frequency band from 5.925 to 7.125 GHz. For example, a single frame may be split and transmitted simultaneously through different channels in different bands to reduce frame transmission time or facilitate transmission of a larger aggregate frame. MLO may include multi-band and multi-channel full-duplex communication achieved by simultaneously transmitting and receiving on different channels (within the same or different bands). MLO may include separation of data plane and control plane into different channels (within the same or different bands). In some aspects, MLO may be implemented using a multi-link single radio (MLSR) architecture, where multiple associated APs 110 or STAs 120 of an MLD may be logical devices under a single radio. In some aspects, MLO may be implemented using an enhanced multi-link single radio (EMLSR) architecture.

[0048] FIG. 4 is a block diagram 400 illustrating an example MLO between MLDs according to some aspects of the disclosure. As shown, an AP MLD 402 can communicate with a non-AP MLD 404 via multi-link communication, such as multi-band aggregation. The AP MLD 402 can also be in communication with other systems (e.g., distribution systems (DS), such as local area networks and / or wide area networks) via an interface 418, such as a backhaul interface. The AP MLD 402 can include at least two STA entities 406, 408 (sometimes referred to as STA instances, also referred to simply as STAs herein) that can communicate with associated STA entities 410, 412 of the non-AP MLD 404. The STA entity (or instance) of the AP MLD is generally an AP (sometimes referred to as an AP-STA, or an STA serving as an AP), and the STA entity of the non-AP MLD is generally a non-AP STA (sometimes referred to simply as an STA). MLD can use MLOs such as multi-link aggregation (MLA) (including packet level aggregation), which allows MAC protocol data units (MPDUs) from the same traffic ID (TID) to be transmitted over two or more links 414, 416.

[0049] In an aspect, the STA entities 406, 408 can each communicate on a separate band (e.g., 2.4, 5, and 6 GHz bands), and similarly, the STA entities 410, 412 can each communicate on a separate band (e.g., 2.4, 5, and 6 GHz bands). For example, the STA entities 406, 410 can communicate with each other on a first link 414 via a first band (e.g., 5 GHz band), and the STA entities 408, 412 can communicate with each other on a second link 416 via a second band (e.g., 6 GHz band). The aggregated links 414, 416 can enable a desired throughput and latency between the AP MLD 402 and the non-AP MLD 404. In an aspect, the STA entities (406, 408, or 410, 412) of the MLD may be implemented as separate devices or RF transceiver chips of the MLD, or the STA entities may be integrated into the same device or RF transceiver chip. In some aspects, a link may refer to a physical path having a traversal of a wireless medium (WM) that can be used to transfer various packets, messages, or frames (e.g., MAC service data units (MSDUs)) between two STAs.

[0050] Exemplary Group Addressed Frame Reception for Enhanced Multi-Link Single Radio (EMLSR) Non-Access Point (Non-AP) Multi-Link Device (MLD) Multi-link operation (MLO) allows an access point (AP) multi-link device (MLD) and a non-AP MLD to transmit and receive data from the same traffic flow over multiple radio interfaces, as described in detail above. In some aspects, MLO can be implemented using a multi-link single-radio (MLSR) architecture, where multiple associated APs or non-AP MLDs can be logical devices under a single radio. In some other aspects, MLO can be implemented using an enhanced multi-link single-radio (EMLSR) architecture. An MLD operating in MLSR or EMLSR mode can only transmit and receive (e.g., transmit and receive data frames, management frames, etc.) over a single radio.

[0051] A non-AP MLD can operate in EMLSR mode on a designated set of enabled links. A non-AP MLD operating in EMLSR mode may be referred to herein for simplicity as EMLSR non-AP MLD or non-AP MLD. A designated set of enabled links for EMLSR mode may be referred to as EMLSR links.

[0052] A non-AP MLD may be able to listen on EMLSR links by waking up its associated STA(s) corresponding to those links. In some cases, a non-AP MLD may be able to listen on two or more EMLSR links simultaneously. While performing a listening operation, a non-AP MLD may be said to be in a 1×1 listen state. In the 1×1 listen state, a non-AP MLD may perform various functions, such as clear channel assessment (CCA) to evaluate the radio frequency (RF) medium. CCA may involve listening to RF transmissions at the physical (PHY) layer. Additionally, in the 1x1 listen state, the non-AP MLD can receive the initial control frame of a frame exchange sequence initiated by an AP operating on one of the EMLSR links, and may also be able to receive other types of frames within a subset of the physical layer (PHY) protocol data unit (PPDU) types and PHY rates supported in full capability mode.

[0053] The transmission of an initial control frame from the AP MLD to the non-AP MLD can be used to initiate a frame exchange sequence with the non-AP MLD on one of the EMLSR links enabled for the non-AP MLD. After receiving the initial control frame, the non-AP MLD can enter a transmit (TX) / receive (RX) state (e.g., 2x2 TX / RX state) for transmitting and receiving frames (e.g., with the AP) on the link on which the initial control frame was received. The term "2x2 TX / RX state" can be used interchangeably with "full capability state" herein. In this context, "full capability" generally means that the non-AP can receive any PPDU type transmitted at any supported rate and all medium access control MAC frames without the restrictions that apply in the 1x1 listen state. When transmitting and receiving frames on the link on which the initial control frame was received, the non-AP MLD may not transmit or receive on the other EMLSR link(s) enabled for the non-AP MLD. In other words, the non-AP MLD can transmit and receive only on one link at a time. The non-AP MLD may switch back to listening operation (eg, switch back to a 1×1 listen state) following completion of a frame exchange sequence with the AP.

[0054] In some cases, the non-AP MLD may initiate a frame exchange sequence with the AP. The frame exchange sequence may be initiated by the non-AP MLD at any time on any one of the EMLSR links enabled for the non-AP MLD. When initiated by the non-AP MLD, the first frame of the frame exchange sequence may be subject to fewer or no constraints.

[0055] In some cases, while the non-AP MLD is in a 2x2 TX / RX state on a first link, one or more frames addressed to the non-AP MLD can be transmitted on a different link, e.g., a second link. The frame(s) transmitted to the non-AP MLD on the second link may be a group-addressed frame(s). In some aspects, the group-addressed frame is part of a group-addressed (multicast / broadcast) frame communication. In some embodiments, the group-addressed frame transmitted on the EMLSR link is addressed to one or more non-AP MLDs that have the EMLSR link as the link for group-addressed frame reception. In other words, the EMLSR link may be the anchor link selected by one or more non-AP MLDs addressed in the group-addressed frame.

[0056] In some cases, the non-AP MLD may be able to receive group-addressed frames from the AP MLD while in the 1×1 listen state. Thus, the non-AP MLD may receive group-addressed frames at a different time than when it is involved in the frame exchange sequence. Thus, the non-AP MLD may adhere to its single-radio constraint without missing any group-addressed frame(s) sent to the non-AP MLD.

[0057] However, in some other cases, the non-AP MLD may not be able to receive group-addressed frames from the AP MLD while in the 1×1 listen state. In such cases, reception of group-addressed frames on the EMLSR link may require the non-AP MLD to switch to a 2×2 TX / RX state on that EMLSR link. If a group-addressed frame is transmitted to the non-AP MLD on one EMLSR link (e.g., a first link) but the non-AP MLD is in a 2×2 TX / RX state on another EMLSR link (e.g., a second link), the non-AP MLD may miss receiving the group-addressed frame on the first link because the non-AP MLD can only transmit and receive frames from the AP MLD (e.g., in a 2×2 TX / RX state) on one link at a time.

[0058] Accordingly, aspects herein present techniques for facilitating reception of group-addressed frame(s) in a non-AP MLD, taking into account the single-radio constraints of the non-AP MLD. The AP MLD or the non-AP MLD may take one or more actions designed to ensure that the non-AP MLD is able to receive the group-addressed frame(s). Examples of actions taken by an AP MLD are described in more detail below with respect to Figures 5-9. Examples of actions taken by a non-AP MLD may be described in more detail below with respect to Figures 10-14.

[0059] Actions taken by the AP MLD may include, but are not limited to, (1) changing the transmission time of the group addressing frame(s), (2) protecting the group addressing frame(s) reception in the non-AP MLD, and / or (3) providing additional information to the non-AP MLD that can assist the non-AP MLD in receiving the group addressing frame(s). Actions taken by the AP MLD may also include transmitting a trigger frame that precedes the transmission of the group addressing frame. The trigger frame transmitted to the non-AP MLD prior to the transmission of the group addressing frame may indicate to the non-AP MLD that it needs to enter a 2x2 TX / RX state to receive the group addressing frame.

[0060] FIG. 5 is an example transmission timeline 500 illustrating a trigger frame 510 being transmitted prior to the transmission of group addressing frames (512 and 514) according to some aspects of the disclosure. As shown in FIG. 5, the non-AP MLD and the AP MLD may have established two links for communication, and the non-AP MLD may be toggling between two states, namely, a 1×1 listen state and a 2×2 TX / RX state. In this example, the trigger frame may be transmitted on a first link (e.g., link 1) prior to (e.g., prior in time) the transmission of the two group addressing frames to the non-AP MLD. The trigger frame may be transmitted by the AP and then received by the non-AP MLD while the non-AP MLD is in the 1×1 listen state. The trigger frame received by the non-AP MLD during the 1×1 listen state may indicate to the non-AP MLD to switch from the 1×1 listen state to the 2×2 TX / RX state to receive the group addressing frames (e.g., on link 1).

[0061] By using trigger frames, the AP MLD may be able to send group-addressed frame(s) essentially at any time while increasing the likelihood that non-AP MLDs will receive the group-addressed frame(s). In the example shown in FIG. 5, it may be assumed that the STAs are in active mode (e.g., none of the STAs in the basic service set (BSS) are in power saving (PS) mode) and can receive the group-addressed frame(s) at any given time. These active STAs may include STAs associated with the EMLSR non-AP MLD of interest, as well as other EHT and legacy STAs in the BSS. If any of these STAs were in PS mode, the AP must buffer the GA frame until the DTIM beacon.

[0062] In some cases, the trigger frame may be a first control type frame, such as a buffer status report poll (BSRP) or multiple user (MU) request to send (RTS) (MU-RTS). In this case, the user information field of the MU RTS / BSRP will be addressed, at a minimum, to the EMLSR non-AP MLD and may also be addressed to other (possibly all) EMLSR non-AP MLDs to which the GA frame is destined. In some cases, the trigger frame may be a second control type frame used to indicate to all non-AP MLDs operating in EMLSR mode in communication with the AP MLD on the link on which the control type frame is transmitted, that they each enter a 2x2 TX / RX state to receive group-addressed frames over this link.

[0063] As mentioned above, in some cases, the non-AP MLD may be able to receive frames from the AP MLD while in the 1×1 listen state. Thus, a trigger frame such as trigger frame 510 shown in FIG. 5 may not be required prior to the transmission of a group-addressed frame by the AP. However, in some other cases, the non-AP MLD may be able to receive only frames having a particular rate and / or PPDU type from the AP MLD while in the 1×1 listen state. In other words, a group-addressed frame having a PPDU type that is not supported by the non-AP MLD while in the 1×1 listen state (but possibly supported while in the 2×2 TX / RX state) may not be received by the non-AP MLD in the 1×1 listen state. Thus, a trigger frame may be transmitted prior to the transmission of the group-addressed frame to indicate to all non-AP MLDs that are expected to receive the group-addressed frame to switch to the 2×2 TX / RX state (e.g., on the link on which the trigger frame is transmitted).

[0064] The group addressing frame may include a first bit that indicates to a non-AP MLD receiving the group addressing frame that a subsequent group addressing frame will be transmitted by the AP MLD, or a second bit that indicates to a non-AP MLD that additional group addressing frames will not be transmitted by the AP MLD. After receiving a group addressing frame with the second bit, the non-AP MLD may decide to return to a 1x1 listen state.

[0065] As shown in Figure 5, the first group addressing frame 512 includes a More bit equal to 1, indicating to the non-AP MLD that a second group addressing frame 514 is to be transmitted. Additionally, as shown in Figure 5, the second group addressing frame 514 includes a More bit equal to 0, indicating that the non-AP MLD should not expect another group addressing frame. Thus, the non-AP MLD can know to return to a 1x1 listen state after receiving a group addressing frame with a More bit equal to 0.

[0066] In some aspects, the one or more actions taken by the AP MLD include transmitting the group addressing frame(s) at a predetermined time. More specifically, the one or more actions taken by the AP MLD can include buffering the group addressing frame until a predetermined time to give the non-AP MLD sufficient time to enter a TX / RX state to receive the group addressing frame, and transmitting the group addressing frame at a predetermined time. The transmission of the group addressing frame at the predetermined time can provide a notification to the non-AP MLD of the group addressing frame to be transmitted, thereby allowing the non-AP MLD to switch to a 2×2 TX / RX state prior to the transmission of the group addressing frame(s).

[0067] In some cases, the predetermined time may include a time after transmission of a delivery traffic indication message (DTIM) beacon at a target beacon transmission time (TBTT) interval configured by the AP for the link on which the group-addressed frame is transmitted. Such a case is illustrated in the example transmission timeline 600 of FIG. 6. As used herein, TBTT may be a regular interval at which beacons are transmitted by the AP, and a DTIM beacon may refer to a beacon that informs non-AP MLDs about the presence of buffered frames (e.g., multicast / broadcast, group-addressed frames) at the AP.

[0068] FIG. 6 is an example transmission timeline 600 illustrating the transmission of group addressing frames at a given time according to some aspects of the disclosure. As shown in FIG. 6, similar to FIG. 5, the non-AP MLD and the AP MLD may be establishing two links for communication, and the non-AP MLD may be toggling between two states, namely, 1×1 listen state and 2×2 TX / RX state. A TBTT is also configured by the AP MLD for the first link (e.g., link 1). It may be noted that beacons, TBTT, and / or group addressing frame transmissions 612 / 614 may be present on the second link, e.g., link 2. However, these descriptions are omitted from FIG. 6 for illustrative purposes.

[0069] To aid in transmitting group addressing frame(s) to the non-AP MLD, the AP MLD may wait to transmit group addressing frame(s) 612 / 614 to the non-AP MLD until after a DTIM beacon is received by the non-AP MLD at (or after) one of the TBTTs configured by the AP MLD on link 1. As shown in FIG. 6, at the second illustrated TBTT, a DTIM beacon may be transmitted on link 1. After transmitting the DTIM beacon, the AP MLD may be configured to transmit first and second group addressing frames, the first group addressing frame including a more bit equal to 1 and the second group addressing frame including a more bit equal to 0. After the second group addressing frame (e.g., having a more bit=0), the non-AP MLD returns to a 1×1 listen state. By waiting to transmit the group-addressed frame(s) until after the DTIM beacon has been transmitted, the non-AP MLD is given enough time to switch to the 2x2 TX / RX state on the link on which the DTIM beacon was transmitted before it needs to receive the group-addressed frame.

[0070] In some cases, the non-AP MLD may select to receive beacons and group addressing frames, including DTIM beacons, on one or more links established between the non-AP MLD and the AP. The selected link or links may be referred to as anchor links, which are links on which the non-AP MLD listens for beacons to know when to switch to 2×2 TX / RX mode to receive one or more group addressing frames from the AP. The non-AP MLD may indicate the selected link(s) to the AP, so that the AP MLD knows on which link to communicate beacons and / or group addressing frames with the non-AP MLD. For example, in FIG. 6, the AP MLD may receive a request from the non-AP MLD to receive DTIM beacons only on the first link (and not the second link). Thus, as shown in FIG. 6, the AP MLD transmits DTIM beacons on the first link according to the request (e.g., triggering the non-AP MLD to switch to 2×2 TX / RX state).

[0071] In some cases, the anchor link can be selected by the non-AP MLD with the intent of saving power. For example, the non-AP MLD can listen to beacons carrying TIM and DTIM messages by sleeping through the TBTT on all non-anchor links and waking up only on the anchor links. The non-AP MLD can wake up on non-anchor links to transmit data and control frame exchanges, but sleep through management frames.

[0072] In some cases, the selection or recommendation of the anchor link can be announced by the AP MLD. In such a case, the AP MLD can protect group-addressed frames scheduled on the anchor link (e.g., no frame exchange sequences are scheduled on any non-AP MLD operating in EMLSR mode during this period), but can ensure that group-addressed frames scheduled on any of the non-anchor links do not need to be protected. In some cases, the anchor link can be set up by the AP MLD as a link configured in a lower frequency range to ensure higher reliability and range.

[0073] It may be noted that in some cases, beacon transmission does not always occur in the TBTT configured for the link. In some cases, the beacon may be transmitted by the AP MLD at a time after the TBTT. For example, as shown in FIG. 6, in the third TBTT configured for the first link, the medium may be busy (e.g., OBSS). Therefore, the beacon may be transmitted at a time after the TBTT.

[0074] In some aspects, the one or more actions taken by the AP MLD include actions to protect group-addressed frame reception by non-AP MLDs. To protect group-addressed frame reception by non-AP MLDs, when the AP initiates a frame exchange sequence on a first link between the AP MLD and the non-AP MLD (e.g., by transmitting a control type frame to the non-AP MLD over the first link), it may first (1) determine which link is the anchor link selected by the non-AP MLD and (2) verify that the frame exchange sequence does not overlap in time with the TBTT configured by the AP MLD on the anchor link before initiating the frame exchange sequence. If the group-addressed frame is predetermined to be transmitted after the DTIM beacon, the AP MLD may perform these steps before the transmission of the control type frame to initiate the frame exchange sequence. By first verifying that the frame sequence does not overlap with the TBTT on the anchor link, the AP MLD may ensure that the frame sequence exchange does not interfere with the ability of the non-AP MLD to receive one or more group-addressed frames.

[0075] 7A and 7B illustrate example scenarios 700A, 700B for protecting group addressing frame reception in accordance with certain aspects of the present disclosure. Specifically, FIG. 7A illustrates an example scenario in which group addressing frame reception is not protected, and FIG. 7B illustrates an example scenario in which group addressing frame reception is protected.

[0076] As shown in Figure 7A, similar to Figure 6, the AP MLD can wait to transmit a group-addressed frame(s) 712 / 714 to the non-AP MLD until after a DTIM beacon is received by the non-AP MLD on link 1 at (or after) one of the TBTTs configured by the AP MLD. However, if the AP MLD initiates a frame exchange sequence with the non-AP MLD on a second link, e.g., link 2, before transmitting a DTIM beacon on link 1, in some cases the frame exchange sequence may overlap in time with the DTIM beacon transmitted on link 1. Because the non-AP MLD can only be in a 2x2 TX / RX state on one link at a time, the non-AP MLD may miss a DTIM beacon transmitted on link 1 while in a 2x2 TX / RX state on link 2 during a frame exchange sequence on link 2 between the AP MLD and the non-AP MLD. Therefore, as shown in FIG. 7A, group-addressed frame reception on link 1 may not be protected, and non-AP MLD may not be able to receive group-addressed frames on link 1 sent by the AP.

[0077] To protect group-addressed frame reception on link 1, before initiating a frame exchange sequence on link 2, the AP MLD can (1) determine that link 1 is the anchor link selected by the non-AP MLD and (2) verify that the frame exchange sequence does not overlap in time with a subsequent TBTT on link 1 (e.g., in time). In other words, the AP MLD can ensure that the frame exchange sequence on link 2 with the non-AP MLD is completed on link 2 prior in time to the TBTT on link 1. In some cases, the non-AP MLD can take some additional "switching delay" to transition from one state to another. For example, the AP MLD can finish the frame exchange sequence on link 2 to give the non-AP MLD enough time to switch from link 2 to link 1 to receive the GA frame.

[0078] For example, as shown in Figure 7B, before initiating a frame exchange sequence on link 2 (e.g., by transmitting a BSRP on link 2), the AP MLD verifies that the frame exchange sequence ends before a TBTT on link 1 (e.g., the second TBTT shown). Since in Figure 7B it is determined that the frame sequence ends before the second TBTT on link 1, the AP MLD initiates a frame exchange sequence with the non-AP MLD on link 2. In this way, the non-AP MLD can be given enough time to receive a DTIM beacon frame on link 1 that indicates to the non-AP MLD to switch to 2x2 TX / RX mode on link 1 for reception of a group-addressed frame(s) from the AP.

[0079] 7A and 7B, in some aspects, protection of group-addressed frame reception by non-AP MLD may be the responsibility of the AP. In some cases, the AP MLD may not have knowledge of the anchor link of the non-AP MLD. Thus, in such cases, the AP MLD may need to protect group-addressed frame reception on all links established between the AP MLD and the non-AP MLD.

[0080] In some aspects, the one or more actions taken by the AP MLD include actions to protect group addressing frame reception by non-AP MLDs by the AP MLD (1) determining a period of beacon / group addressing frame transmission on each link established between the non-AP MLD and the AP MLD, and (2) setting a virtual quiet period on other links during those identified periods of beacon / group addressing frame transmission. The period of beacon / group addressing frame transmission may refer to a period during which a beacon and one or more group addressing frames may be transmitted later on the same link.

[0081] In some cases, the period of beacon / group addressing frame transmission on one link may not overlap with the period of beacon / group addressing frame transmission on another link. For example, if two links are established between a non-AP MLD and an AP, the period of beacon / group addressing frame transmission on a first of the two links may not overlap in time with the period of beacon / group addressing frame transmission on a second of the two links. However, in some other cases, the period of beacon / group addressing frame transmission on one link (e.g., the first link) may overlap with the period of beacon / group addressing frame transmission on another link (e.g., the second link). In either case, the AP MLD may protect the group addressing frames for the non-AP MLD using a virtual quiet period, as shown in Figures 8A and 8B.

[0082] 8A and 8B illustrate example scenarios 800A, 800B in which a virtual quiet period may be configured on one or more links established between an AP MLD and a non-AP MLD in accordance with certain aspects of the present disclosure.

[0083] FIG. 8A illustrates an example scenario 800A in which virtual quiet periods are used to protect non-overlapping periods of beacon / group addressing frame transmission on two links. As illustrated in FIG. 8A, on a first link, Link 1, there may be two periods of beacon / group addressing frame transmission (e.g., indicated by "B" on Link 1 in FIG. 8A), and on a second link, Line 2, there may be two periods of beacon / group addressing frame transmission (e.g., indicated by "B" on Link 2 in FIG. 8A). The AP MLD may determine that the two periods of beacon / group addressing frame transmission on Link 1 do not overlap in time with the periods of beacon / group addressing frame transmission on Link 2. Thus, to protect group addressing frame reception by non-AP MLD on Link 1, the AP MLD may set up two virtual quiet periods on Link 2 (e.g., indicated by "Q" on Link 2 in FIG. 8A) that overlap in time with the two identified periods of beacon / group addressing frame transmission on Link 1. In addition, to protect group addressing frame reception by non-AP MLD on link 2, the AP MLD may set up two virtual quiet periods on link 1 (e.g., indicated by "Q" on link 1 in FIG. 8A) that overlap in time with two identified periods of beacon / group addressing frame transmission on link 2. Thus, the duration of the period of beacon / group addressing frame reception on link 1 (e.g., the duration of "B") may be equal to the duration of the virtual quiet period on link 2 (e.g., the duration of "Q"), and vice versa. The AP MLD may conservatively calculate the duration of the period of beacon / group addressing frame reception and / or the duration of the virtual quiet period.

[0084] During each virtual quiet period configured by the AP, the AP MLD may refrain from scheduling a frame exchange sequence with a non-AP MLD. Specifically, during a virtual quiet period configured on link 1, the AP MLD may refrain from scheduling a frame exchange sequence with a non-AP MLD on link 1. Furthermore, during a virtual quiet period configured on link 2, the AP MLD may refrain from scheduling a frame exchange sequence with a non-AP MLD on link 2. In some aspects, when the AP MLD refrains from scheduling a frame exchange with a non-AP MLD on any of the links, it may schedule at least one other frame exchange with another non-AP MLD or another non-AP STA.

[0085] 8B illustrates an example scenario 800B in which a virtual quiet period is used to protect overlapping and / or partially overlapping periods of beacon / group addressing frame transmissions on two links. As shown in FIG. 8B, on a first link, Link 1, there may be three identified periods of beacon / group addressing frame transmissions (e.g., indicated by "B" on Link 1 in FIG. 8B), and on a second link, Link 2, there may be four identified periods of beacon / group addressing frame transmissions (e.g., indicated by "B" on Link 2 in FIG. 8B). The AP MLD may determine that periods of beacon / group addressing frame transmissions on Link 1 at least partially overlap in time with periods of beacon / group addressing frame transmissions on Link 2. For example, AP MLD may determine that a first period in time of beacon / group addressing frame transmissions on link 1 completely overlaps in time with a first period in time of beacon / group addressing frame transmissions on link 2, where each of these first periods in time start and end at the same time. As another example, AP MLD may determine that a second period in time of beacon / group addressing frame transmissions on link 2 only partially overlaps in time with a second period in time of beacon / group addressing frame transmissions on link 1, where each of these first periods in time start at the same time but end at a different time.

[0086] Similar to FIG. 8A, to protect group addressing frame reception by non-AP MLDs on each of Link 1 and Link 2, the AP MLD can set up a virtual quiet period on each of Link 1 and Link 2. However, in the example scenario shown in FIG. 8A, a virtual quiet period may not be set on one link for the entire duration of the period of beacon / group addressing frame transmission on the other link. Instead, if the period of beacon / group addressing frame transmission overlaps on two links, the link with the period of beacon / group addressing frame transmission shorter in time can be quiet until the period of beacon / group addressing frame transmission on the other link (e.g., longer in time) is completed. For example, because the second period in time of beacon / group addressing frame transmission on Link 1 is shorter than the second period in time of beacon / group addressing frame transmission on Link 2, the AP MLD can set a virtual quiet period after the second period in time of beacon / group addressing frame transmission on Link 1. This virtual quiet period may continue in time until the completion of a second period in time of beacon / group addressing frame transmissions on link 2. In some aspects, the AP MLD may schedule at least one other frame exchange sequence with another non-AP MLD or another non-AP STA during the virtual quiet period configured on link 1 (and the one or more virtual quiet periods configured on link 2).

[0087] In some aspects, the AP MLD may not be able to protect group-addressed frame reception by the non-AP MLD on a link established between the AP MLD and the non-AP MLD. Thus, the non-AP MLD may be responsible for protecting group-addressed frame reception. To assist the non-AP MLD in protecting group-addressed frame reception, in some aspects, one or more actions taken by the AP MLD include providing additional information to the non-AP MLD to facilitate successful group-addressed frame reception in the non-AP MLD.

[0088] In some cases, group-addressed frames on different links between the AP MLD and the non-AP MLD may be delivered to the non-AP MLD at different rates. The different delivery rates for each of the different links may be due to different channel conditions, different bandwidths (BW), and / or different frame transmission rates for each of the different links. In some cases, which links have faster rates (e.g., more frequent group-addressed frame delivery) and which links have slower rates (e.g., less frequent group-addressed frame delivery) may change at any given time (or snapshot).

[0089] Specifically, in some cases, each group addressing frame transmitted by the AP MLD on a link established with the non-AP MLD can have a sequence number (SN) assigned to the group addressing frame. In some cases, the SN for the group addressing frame can belong to a common pool of SNs. The SN of each group addressing frame can help keep track of which link has a faster or slate frame transmission rate. For example, the last group addressing frame transmitted on a first link can have an SN of 30, while the last group addressing frame transmitted on a second link can have an SN of 25. Based on the SN of each group addressing frame, the AP MLD can determine that the frame transmission rate for the first link is faster than the frame transmission rate for the second link. Again, which link has a faster rate and which link has a slower rate can change over time.

[0090] The non-AP MLD may benefit from knowing the different rates of frame delivery for each of the different links that the non-AP MLD shares with the AP. Specifically, the non-AP MLD may use this information to determine when it may be acceptable to skip receiving group-addressed frames on one link and instead continue to be involved in the frame exchange sequence on the second link. The non-AP MLD may determine that it is acceptable to skip receiving group-addressed frames when the rate of frame delivery on the second link is less than the rate of frame delivery on the first link. The slower rate of frame delivery on the second link may allow the non-AP MLD to receive frames that it missed on the first link at a later time on the second link (e.g., the non-AP MLD may catch up to the slower link). Thus, the non-AP MLD may not incur a performance loss by skipping group-addressed frames on the first link because the non-AP MLD may receive these frames on the second link at a later time. This scenario is described in more detail with respect to FIG. 9.

[0091] FIG. 9 is an example transmission timeline 900 illustrating a scenario in which knowledge of the rate of frame delivery for each link may be useful to a non-AP MLD, according to some aspects of the disclosure. As shown in FIG. 9, on the second link L2, the AP MLD may initiate a frame exchange sequence by transmitting a BSRP. According to some aspects described herein, the non-AP MLD that receives the BSRP may choose to participate in or decline to participate in the frame exchange sequence with the non-AP MLD. Because the frame exchange sequence is expected to overlap with the second TBTT for the first link L1, in some cases, the non-AP MLD may choose not to participate in the frame exchange sequence on L2 so that the non-AP MLD does not miss receiving group-addressed frames (e.g., group-addressed frames associated with SN45 and SN46) on L1.

[0092] However, in some other cases where the non-AP MLD has knowledge of the rate of frame delivery on L1 and the rate of frame delivery on L2, the non-AP MLD may decide to participate in the frame exchange sequence on L2 and instead skip receiving group addressing frames SN45 and SN46 on L1. Specifically, the non-AP MLD may decide that skipping receiving group addressing frames SN45 and SN46 on L1 may not affect the performance of the non-AP MLD, and later, the non-AP MLD may switch its anchor link from L1 to L2 to receive group addressing frames SN45 and SN46 on L2. The non-AP MLD may make this decision if it knows the SN for each of L1 and L2 (e.g., the SN indicating the rate of frame delivery for L1 and L2). Thus, in this scenario, the non-AP MLD may not have to take any action to switch to L1 to receive group addressing frames SN45 and SN46. Thus, it may not experience a service interruption.

[0093] Thus, in some aspects, the one or more actions taken by the AP MLD include indicating to the non-AP MLD the relative rates for group-addressed frame delivery on different links, which are used by the non-AP MLD to determine whether it can skip receiving group-addressed frames (e.g., without affecting overall performance).

[0094] In some cases, the different rate can be indicated via an indication (e.g., in the RNR entry corresponding to the other link) indicating whether the other link (GA delivery rate on) is "faster" or "slower" than the link on which the single bit is advertised. In some cases, the different rate can be indicated via the SN. Specifically, the AP MLD can indicate to the non-AP MLD the rate of frame delivery for each link by providing the last transmitted SN on each of the links, as well as the ΔSN between the links. For example, in FIG. 9, the DTIM beacon transmitted in the second TBTT on L1 can indicate both (1) an SN equal to 45 for L1, and (2) that a ΔSN of (-7) exists between L1 and L2 (e.g., ΔSN=SN38-SN45=-7) because the last group-addressed frame in time transmitted by the AP MLD on L2 had an SN of 38. In some cases, common information in a multi-link (ML) information element (IE) of a beacon may carry information about the last transmitted SN on the current link (e.g., SN45 on L1), while a per-STA profile in the ML IE of a beacon may carry information about the ΔSN between the current link and other links (e.g., a ΔSN of (-7)).

[0095] As mentioned above, not only can the AP MLD take one or more actions to facilitate reception of a group-addressed frame(s) in the non-AP MLD subject to the single-radio constraints of the non-AP MLD, but in some aspects the non-AP MLD can take one or more actions to facilitate reception of a group-addressed frame(s) in the non-AP MLD in lieu of, or in addition to, actions taken by the AP.

[0096] To improve reception of group-addressed frames(s) in the non-AP MLD, the one or more actions taken by the non-AP may include informing the AP MLD of the anchor link selected by the non-AP MLD. More specifically, the one or more actions taken by the AP MLD may include selecting a first link of the plurality of links as an anchor link and providing an indication of the anchor link to the AP. The AP MLD may use this information to protect group-addressed frames sent to the non-AP MLD. Specifically, since the anchor link of the non-AP MLD is selected by the non-AP MLD to be the first link, the AP MLD may not initiate a frame exchange sequence on the first link, but instead initiate a frame exchange sequence on another link of the plurality of links (e.g., based at least in part on the indication) so as not to interfere with group-addressed frame reception by the non-AP MLD on the first link.

[0097] As an illustrative example, the AP MLD may receive an indication from the non-AP MLD that the non-AP MLD has selected a first link L1 as its anchor link. Thus, when the AP MLD recognizes that the TBTT on L1 is approaching, the AP MLD may postpone initiating a frame exchange sequence with the non-AP MLD on the second link L2 and the third link L3 to ensure that the non-AP MLD is not in a 2×2 TX / RX state on L2 or L3 at a time that overlaps with the TBTT on L1.

[0098] If the AP MLD does not have knowledge of the anchor link of the non-AP MLD, the AP MLD may need to protect group-addressed frames on all established links between the non-AP MLD and the AP MLD. This may cause additional delays in the system, thereby adversely affecting the overall performance of the system. As an example, if three EMLSR links (e.g., L1, L2, and L3) are established between the non-AP MLD and the AP, the AP MLD may need to keep track of the approaching TBTTs on each of these different links in order to protect group-addressed frames on each of these links. If the AP MLD determines that the L1 TBTT is approaching, the AP MLD may decide to postpone transmissions to the non-AP MLD on L2 and L3, if the AP MLD determines that the L2 TBTT is approaching, the AP MLD may decide to postpone transmissions to the non-AP MLD on L1 and L3, if the AP MLD determines that the L3 TBTT is approaching, the AP MLD may decide to postpone transmissions to the non-AP MLD on L1 and L2. Therefore, scheduling in the AP MLD may have difficulty protecting group-addressed frames on each link if the AP MLD does not know the anchor links of the non-AP MLDs. Furthermore, postponing transmissions on each of links L1, L2, and L3 may cause significant delays in one or more transmissions.

[0099] In some cases, the anchor link provided to the AP MLD is a static anchor link selection by the non-AP MLD that is provided during association between the non-AP MLD and the AP MLD. In some cases, the anchor link provided to the AP MLD is a semi-static anchor link selection by the non-AP MLD that is initially provided during association between the non-AP MLD and the AP MLD and is subsequently updated transmission of an action frame to the AP MLD. In some cases, the anchor link provided to the AP MLD is a dynamic anchor link selection by the non-AP MLD that is dynamically updated via transmission of a control type frame to the AP MLD.

[0100] In some aspects, AP MLD may not be able to protect group addressing frame reception by non-AP MLD on all EMLSR links. For example, if AP MLD has knowledge of the TBTT on each link on which AP MLD is protecting group addressing frame reception, as well as good coordination between each of these links, AP MLD may be able to protect group addressing frame reception. Thus, for example, in a loosely coupled AP architecture, this may not be the case. Thus, AP MLD may not be able to protect group addressing frame reception for non-AP MLD in this architecture. As another example, AP MLD may not be able to protect group addressing frame reception for non-AP MLD where high priority downlink (DL) low latency packets are transmitted to clients.

[0101] Thus, in such cases, the non-AP MLD may need to take responsibility for protecting group-addressed frame reception in the non-AP MLD. In some aspects, the one or more actions taken by the non-AP MLD may include choosing to miss a group-addressed frame on a first link in order to receive another group-addressed frame on a second link.

[0102] As described with respect to FIG. 9 above, in some cases, the non-AP MLD can make this determination based on frame transmission rates for each of the first and second links (e.g., indicated to the non-AP MLD by the AP MLD). In some aspects, the one or more actions taken by the non-AP MLD can include choosing to miss a group-addressed frame on the first link in order to receive and participate in a frame exchange sequence on the second link. In some cases, the non-AP MLD can make this determination based on a scheduled frame exchange sequence on the second link that carries frames of higher importance (e.g., low latency packets).

[0103] In some aspects, the frame exchange sequence may be initiated by the non-AP MLD. The non-AP MLD may have knowledge of the TBTT(s) on its anchor link as well as other link(s) established between the non-AP MLD and the AP. Thus, the non-AP MLD may possess the necessary information needed to determine whether a frame exchange sequence should be initiated with the AP MLD (e.g., to protect group-addressed frame reception on another link). Thus, the one or more actions taken by the non-AP MLD may include initiating a frame exchange sequence with the AP MLD over the first link when the non-AP MLD determines that the frame exchange sequence does not overlap in time with the TBTT on the second link of the multiple links before initiating the frame exchange sequence. Alternatively, if the non-AP MLD determines that the frame exchange sequence overlaps in time with the TBTT on the second link of the multiple links, the non-AP MLD may choose not to initiate a frame exchange sequence with the AP MLD over the first link. The second link may be the anchor link selected by the non-AP MLD.

[0104] FIG. 10 is an example transmission timeline 1000 illustrating a scenario in which a frame exchange sequence is initiated by a non-AP MLD, according to some aspects of the disclosure. As shown in FIG. 10, the non-AP MLD may initiate a frame exchange sequence with the AP MLD on the second link L2 by transmitting an uplink (UL) data frame. However, before transmitting the UL data frame on L2, the non-AP MLD may determine that the frame exchange sequence overlaps in time with a time-subsequent TBTT on the first link L1. Since the frame exchange sequence on L2 does not overlap in time with the TBTT on L1, the non-AP MLD may initiate the frame exchange sequence. If the non-AP MLD determines that the frame exchange sequence on L2 overlaps in time with a time-subsequent TBTT on L1 in order to protect group-addressed frame reception on L1, the non-AP MLD may choose not to initiate the frame exchange sequence on L2.

[0105] In some aspects, the frame exchange sequence may be initiated by an AP as opposed to a non-AP MLD. To protect group-addressed frame reception when the frame exchange sequence is initiated by an AP, in some aspects, the one or more actions taken by the non-AP MLD include receiving a control type frame from the AP that initiates a frame exchange sequence with the non-AP MLD over a first link, and determining to ignore the control type frame or respond to the control type frame via signaling indicating unavailability of the non-AP MLD for the first link when a time difference between when the control type frame is received and a start of a TBTT on the second link is less than a threshold time.

[0106] FIG. 11 is an example transmission timeline 1100 illustrating a scenario in which a non-AP MLD decides to participate in a first frame exchange sequence and ignore a second frame exchange sequence initiated by an AP, according to some aspects of the disclosure. As shown in FIG. 11, during the time between the first TBTT and the second TBTT on the first link L1, the AP MLD can initiate a frame exchange sequence with the non-AP MLD on the second link L2 (e.g., by transmitting a BSRP). Upon receiving the BSRP, the non-AP MLD can have knowledge of the next TBTT on L1 (e.g., the second TBTT on L1). Before responding to the BSRP, the non-AP MLD can determine whether the time difference between when the BSRP is received on L2 and the start of the TBTT on L2 is less than a threshold time. In other words, before responding to the BSRP, the non-AP MLD can determine whether the BSRP received on L2 is outside the Δ interval on L1. If the BSRP is outside the Δ interval on L1, the non-AP MLD can respond to the BSRP and participate in the frame exchange sequence. On the other hand, if the BSRP is inside the Δ interval on L1, the non-AP MLD can either (1) ignore the BSRP received on L2 by refraining from responding to the BSRP, or (2) respond to the BSRP via signaling indicating the unavailability of the non-AP MLD for L2. In this case (e.g., case 1 shown in FIG. 11), the non-AP MLD can determine that the BSRP is received outside the Δ interval on L1 and decide to respond to the BSRP by sending a BSR to the AP MLD (and further participate in exchanging frames with the AP).

[0107] As another example shown in FIG. 11, during the time between the third TBTT and the fourth TBTT on L1, the AP MLD can initiate a second frame exchange sequence with the non-AP MLD on L2 (e.g., by transmitting a BSRP). Upon receiving the BSRP on L2, the non-AP MLD can have knowledge of the next fourth TBTT on L1. Unlike the BSRP received on L2 during the time between the first TBTT and the second TBTT on L1, the BSRP received on L2 during the time between the third TBTT and the fourth TBTT on L1 is received within the Δ interval on L1. Thus, in case 2 shown in FIG. 11, the non-AP MLD can ignore the BSRP received on L2 by refraining from responding to the BSRP.

[0108] As shown by the example transmission timeline 1100 of FIG. 11, the Δ interval can be used by the non-AP MLD as a way to determine whether participating in a frame exchange sequence on one link may cause problems with receiving one or more group-addressed frames on another link. For example, a Δ interval for a first link set to 500 usec for the first link can be used by the non-AP MLD as a way to determine whether the non-AP MLD should participate in a frame exchange on a second link (e.g., if a control type frame is transmitted to the non-AP MLD on the second link 600 usec before the TBTT on the first link) or not participate in a frame exchange on the second link (e.g., if a control type frame is transmitted to the non-AP MLD on the second link 300 usec before the TBTT on the first link). In some cases, the non-AP MLD can use the Δ interval for the anchor link to determine whether to participate in a frame exchange sequence on another link when the TBTT on the anchor link is close.

[0109] As mentioned with respect to Figure 11, if a control type frame (e.g., BSRP) is received on the second link by the non-AP MLD inside the Δ interval on the first link, the non-AP MLD may possibly respond to the control type frame via signaling indicating the unavailability of the non-AP MLD for the second link, as opposed to ignoring the control type frame (as shown in Case II of Figure 11). The signaling indicating the unavailability of the non-AP MLD for the second link may indicate to the AP MLD that the non-AP MLD is unavailable to participate in transmitting and / or receiving subsequent frames on the second link at the current time.

[0110] FIG. 12 is an example transmission timeline illustrating a scenario in which a non-AP MLD is involved in a first frame exchange sequence and determines to signal the unavailability of the non-AP MLD for a second frame exchange sequence initiated by an AP, according to some aspects of the disclosure. As shown in FIG. 12, similar to FIG. 11, in case I, the non-AP MLD can determine that the BSRP transmitted on the second link L2 is outside the Δ interval for the first link L1. Thus, the non-AP can respond to the BSRP by transmitting a BSR. Also similar to FIG. 11, in case II, the non-AP MLD can determine that the BSRP transmitted on L2 is within the Δ interval for L1. However, unlike FIG. 11, instead of ignoring the BSRP transmitted on L2, the non-AP MLD can respond to the BSRP. The BSRP can be responded to by signaling to the AP the unavailability of the non-AP MLD to transmit and / or receive subsequent frames from the AP MLD on L2 at the current time.

[0111] In some cases, the signaling indicating the unavailability of the non-AP MLD for L2 is via a new A-control field of a medium access control (MAC) header in the at least one response frame. When the unavailability of the non-AP MLD for the first link is via a new A-control field of a MAC header in the at least one response frame, the at least one response frame includes an aggregate MAC protocol data unit (A-MPDU). The first MPDU of the response frame can indicate a BSR in a BSRP control in the A-control field of the MAC header where the control type frame received from the AP MLD is BSRP, and the second MPDU of the response frame can indicate the unavailability of the non-AP MLD via the new A-control field of the MAC header.

[0112] In some cases, signaling indicating non-AP MLD unavailability for L2 is via a power management (PM) bit in the frame control field of the MAC header in the response frame.

[0113] In some cases, at least one response frame includes one or more Quality of Service (QoS) Null frames. In some cases, at least one response frame includes a QoS Null frame having a QoS Control field indicating BSR and a subfield indicating unavailability (e.g., a new A Control field).

[0114] If only one QoS Null frame is transmitted, the BSR from the non-AP MLD is indicated in the QoS Control field and the unavailability is signaled in the A-Control field.

[0115] In some cases, signaling the unavailability of a non-AP MLD to transmit and / or receive subsequent frames on one link may implicitly indicate the anchor link of the non-AP MLD. For example, a non-AP MLD may signal unavailability on one link to receive group-addressed frames on another link. Thus, when an AP MLD receives unavailability signaling from a non-AP MLD for one or more links (e.g., depending on the number of EMLSR links established between the non-AP MLD and an AP), the AP MLD may be able to determine which link is the anchor link of the non-AP MLD.

[0116] In some aspects, the one or more actions taken by the non-AP MLD to protect group-addressed frame reception by the non-AP MLD can include terminating DL transmissions from the AP MLD on one link when the TBTT on another link is approaching. More specifically, the one or more actions taken by the non-AP MLD can include receiving a control type frame from the AP that initiates a frame exchange sequence with the non-AP MLD over a first link, the frame exchange sequence being for communication of one or more DL or UL frames, and engaging in the frame exchange sequence when a time difference between when the control type frame is received and the start of the TBTT on the second link is greater than a first threshold time.

[0117] When involved in a frame exchange sequence, the non-AP MLD may determine that the start of the TBTT for the second link occurs within the second threshold time before transmitting the last UL frame of the frame exchange sequence, and may transmit a last UL frame with an A-control field or PM bit indicating unavailability of the non-AP MLD based at least in part on the determination. The unavailability of the non-AP MLD indicated in the UL frame may trigger the end of the frame exchange sequence. In some cases, the last UL frame is a UL data frame. In some cases, the last UL frame is a UL control frame.

[0118] 13 is an example transmission timeline 1300 illustrating a scenario in which a UL frame is transmitted by a non-AP MLD to terminate a frame exchange sequence on an EMLSR link in accordance with certain aspects of the disclosure. The example transmission timeline 1300 of FIG. 13 illustrates two cases: Case I in which a UL data frame is transmitted by a non-AP MLD to trigger the end of a frame exchange sequence, and Case II in which a UL control frame is transmitted by a non-AP MLD to trigger the end of a frame exchange sequence.

[0119] As shown in FIG. 13, for both Case I and Case II, a control type frame initiating a frame exchange sequence with the non-AP MLD is received by the non-AP MLD on the second link L2. Each of the control type frames is a BSRP used to initiate communication of one or more DL and UL frames between the non-AP MLD and the AP MLD. Since the BSRP in each case is received a sufficient time before the TBTT on the first link L1 (e.g., the time difference between the BSRP and the second TBTT on L1 in Case I is greater than the first threshold time, and the time difference between the BSRP and the second TBTT on L1 in Case II is greater than the first threshold time), the non-AP MLD participates in a frame exchange sequence with the AP MLD (e.g., by transmitting a BSR in Case I and Case II).

[0120] In both cases, after transmission of UL and DL frames between the AP MLD and the non-AP MLD, the non-AP MLD may determine that the TBTT on link 1 and the TBTT on link 2 are close (e.g., within a second threshold time). Thus, the non-AP MLD transmits in its last UL frame the unavailability of the non-AP MLD to receive and / or transmit any subsequent frames. In case I, the non-AP MLD signals the unavailability in a UL data frame. In case II, the non-AP MLD signals the unavailability in a UL control frame. The last UL frame may have an A-control field or PM bit indicating the unavailability of the non-AP MLD. Transmitting the last UL frame with an A-control field or PM bit indicating the unavailability of the non-AP triggers the end of the frame exchange sequence between the non-AP MLD and the AP. Alternatively, if the non-AP MLD does not respond, indicating the unavailability of the non-AP MLD, the AP may continue to retransmit frames / double its contention window (CW) due to the lack of response of the non-AP MLD.

[0121] After transmitting a UL frame signaling the unavailability of the non-AP MLD, the non-AP MLD may switch to a 2x2 TX / RX state on L1 to receive group-addressed frames. By terminating the frame exchange sequence based on the approaching TBTT, the non-AP MLD facilitates reception of the group-addressed frame(s) in the non-AP MLD.

[0122] In some aspects, the one or more actions taken by the non-AP MLD to protect group-addressed frame reception by the non-AP MLD may include transmitting an unsolicited frame explicitly indicating unavailability of the non-AP MLD. More specifically, the one or more actions taken by the non-AP MLD may include determining that a start of a TBTT configured by the AP MLD for a first link of the plurality of links occurs within a threshold time, and transmitting an unsolicited frame to the AP MLD explicitly indicating unavailability of the non-AP MLD for a second link of the plurality of links, the unavailability indicated in the unsolicited frame indicating to the AP MLD to refrain from initiating frame exchange with the non-AP MLD on the second link. In some aspects, the unavailability explicitly indicated by the non-AP MLD is indicated via a PM bit of the unsolicited frame. In some aspects, the unsolicited frame is a QoS Null frame.

[0123] 14 is an example transmission timeline 1400 illustrating a scenario in which an unsolicited frame is transmitted by a non-AP MLD to indicate the unavailability of the non-AP MLD on the EMLSR link, according to some aspects of the disclosure. As shown in Case II of FIG. 14, an unsolicited frame (e.g., a frame not asked for by the AP) may be spontaneously transmitted to the AP on the second link L2 to explicitly indicate to the AP that the non-AP MLD may be unavailable for frame exchange on L2. The non-AP MLD may transmit an unsolicited frame before the TBTT on the first link L1 to ensure that the non-AP MLD can receive one or more group-addressed frames on L1.

[0124] Example Operation 15 is a flow diagram illustrating example operations 1500 for wireless communication in accordance with certain aspects of the disclosure. The operations 1500 may be performed by a wireless node, such as an AP MLD (such as the AP MLD 402 shown in FIG. 4).

[0125] The operations 1500 begin, at 1505, by establishing a plurality of links for an AP MLD to communicate with non-AP MLDs, where one or more non-AP MLDs including the non-AP MLD communicate with an AP on each of the plurality of links.

[0126] At 1510, the AP MLD takes one or more actions designed to ensure that the non-AP MLD can receive the group-addressed frame.

[0127] 16 is a flow diagram illustrating example operations 1600 for wireless communication according to some aspects of the disclosure. The operations 1600 may be performed by a wireless node, such as a non-AP MLD, such as the non-AP MLD 404 illustrated in FIG. 4. The non-AP MLD may be operating in an EMLSR mode. The operations 1600 may be complementary operations by the non-AP MLD to the operations 1500 performed by the AP MLD.

[0128] The operations 1600 begin, at 1605, by a non-AP MLD operating in EMLSR mode establishing multiple links for communication with an AP MLD, where one or more non-AP MLDs including the non-AP MLD communicate with an AP on each of the multiple links.

[0129] At 1610, the non-AP operating in EMLSR mode takes one or more actions designed to ensure that the non-AP MLD can receive group-addressed frames.

[0130] The various operations of the methods described above may be implemented by any suitable means capable of performing the corresponding functions, which may include various hardware component(s) or software component(s) including, but not limited to, circuits, application specific integrated circuits (ASICs), or processors, or various hardware module(s) or software module(s). Generally, when operations are illustrated in figures, the operations may have corresponding equivalent means-plus-function components that are similarly numbered.

[0131] Exemplary Devices Figure 17 illustrates a communications device 1700 that may include various components operable, configured, or adapted to perform operations for the techniques disclosed herein, such as those illustrated in Figure 15. In some embodiments, the communications device 1700 may be an AP MLD, such as the AP MLD 402 illustrated in Figure 4.

[0132] Communications device 1700 includes a processing system 1702 coupled to a transceiver 1708 (e.g., a transmitter or receiver). The transceiver 1708 is configured to transmit and receive signals for communications device 1700 via an antenna 1710, such as various signals as described herein. The processing system 1702 can be configured to perform processing functions for communications device 1700, including processing signals received by or to be transmitted by communications device 1700.

[0133] The processing system 1702 includes a processor 1704 coupled via a bus 1706 to a computer-readable medium / memory 1712. In some aspects, the computer-readable medium / memory 1712 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1704, cause the processor 1704 to perform the operations illustrated in FIG. 15 or other operations to perform the various techniques described herein for MLO.

[0134] In some aspects, computer readable medium / memory 1712 stores code 1714 for establishing (eg, one embodiment of a means) and code 1716 for taking one or more actions (eg, one embodiment of a means).

[0135] In some aspects, the processor 1704 has circuitry configured to execute code stored on the computer readable medium / memory 1712. The processor 1704 includes circuitry 1724 for establishing (e.g., an embodiment of a means) and circuitry 1726 for taking one or more actions (e.g., an embodiment of a means).

[0136] The transceiver 1708 may provide a means for receiving information, such as packets, user data, or control information associated with various information channels (e.g., control channel, data channel, etc.). The information may be passed to other components of the device 1700. The transceiver 1708 may be an embodiment of an aspect of the transceiver 254 described with reference to FIG. 2. The antenna 1710 may correspond to a single antenna or a set of antennas. The transceiver 1708 may provide a means for transmitting signals generated by other components of the device 1700.

[0137] For example, the means for transmitting (or the means for outputting for transmission) may include a transmitter (such as transmitter unit 222) or antenna(s) 224 of the AP 110, or a transmitter unit 254 or antenna(s) 252 of the STA 120, as shown in Figure 2. The means for receiving (or the means for acquiring) may include a receiver (such as receiver unit 222) or antenna(s) 224 of the AP 110, or a receiver unit 254 or antenna(s) 252 of the STA 120, as shown in Figure 2. The means for communicating may include a transmitter, a receiver, or both. The means for establishing and the means for taking one or more actions may include a processing system, which may include one or more processors, such as the RX data processor 242, the TX data processor 210, the TX spatial processor 220, or the controller 230 of the AP 110 shown in FIG. 2, or the RX data processor 270, the TX data processor 288, the TX spatial processor 290, or the controller 280 of the STA 120.

[0138] In some cases, a device may have an interface (means for outputting) for outputting a frame for transmission, rather than actually transmitting the frame. For example, a processor may output a frame to a radio frequency (RF) front end for transmission via a bus interface. Similarly, a device may have an interface (means for acquiring) for acquiring a frame received from another device, rather than actually receiving the frame. For example, a processor may acquire (or receive) a frame from an RF front end for reception via a bus interface. In some cases, the interface for outputting a frame for transmission and the interface for acquiring a frame (sometimes referred to herein as a first and second interface) may be the same interface.

[0139] Figure 18 illustrates a communications device 1800 that may include various components operable, configured, or adapted to perform operations for the techniques disclosed herein, such as those illustrated in Figure 16. In some embodiments, the communications device 1800 may be a non-AP MLD, such as the non-AP MLD 404 illustrated in Figure 4.

[0140] Communications device 1800 includes a processing system 1802 coupled to a transceiver 1808 (e.g., a transmitter or receiver). The transceiver 1808 is configured to transmit and receive signals for communications device 1800 via an antenna 1810, such as various signals as described herein. Processing system 1802 can be configured to perform processing functions for communications device 1800, including processing signals received by or to be transmitted by communications device 1800.

[0141] The processing system 1802 includes a processor 1804 coupled via a bus 1806 to a computer-readable medium / memory 1812. In some aspects, the computer-readable medium / memory 1812 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1804, cause the processor 1804 to perform the operations illustrated in FIG. 16 or other operations to perform the various techniques described herein for MLO.

[0142] In some aspects, computer readable medium / memory 1812 stores code 1814 for establishing (eg, one embodiment of a means) and code 1816 for taking one or more actions (eg, one embodiment of a means).

[0143] In some aspects, the processor 1804 has circuitry configured to execute code stored on the computer-readable medium / memory 1812. The processor 1804 includes circuitry 1824 for establishing (e.g., an embodiment of a means) and circuitry 1826 for taking one or more actions (e.g., an embodiment of a means).

[0144] The transceiver 1808 may provide a means for receiving information, such as packets, user data, or control information associated with various information channels (e.g., control channel, data channel, etc.). The information may be passed to other components of the device 1800. The transceiver 1808 may be an embodiment of an aspect of the transceiver 254 described with reference to FIG. 2. The antenna 1810 may correspond to a single antenna or a set of antennas. The transceiver 1808 may provide a means for transmitting signals generated by other components of the device 1800.

[0145] For example, the means for transmitting (or the means for outputting for transmission) may include a transmitter (such as transmitter unit 222) or antenna(s) 224 of the AP 110, or a transmitter unit 254 or antenna(s) 252 of the STA 120, as shown in Figure 2. The means for receiving (or the means for acquiring) may include a receiver (such as receiver unit 222) or antenna(s) 224 of the AP 110, or a receiver unit 254 or antenna(s) 252 of the STA 120, as shown in Figure 2. The means for communicating may include a transmitter, a receiver, or both. The means for establishing and the means for taking one or more actions may include a processing system, which may include one or more processors, such as the RX data processor 242, the TX data processor 210, the TX spatial processor 220, or the controller 230 of the AP 110 shown in FIG. 2, or the RX data processor 270, the TX data processor 288, the TX spatial processor 290, or the controller 280 of the STA 120.

[0146] In some cases, a device may have an interface (means for outputting) for outputting a frame for transmission, rather than actually transmitting the frame. For example, a processor may output a frame to a radio frequency (RF) front end for transmission via a bus interface. Similarly, a device may have an interface (means for acquiring) for acquiring a frame received from another device, rather than actually receiving the frame. For example, a processor may acquire (or receive) a frame from an RF front end for reception via a bus interface. In some cases, the interface for outputting a frame for transmission and the interface for acquiring a frame (sometimes referred to herein as a first and second interface) may be the same interface.

[0147] Exemplary Aspects Aspect 1: A method of wireless communication by an access point (AP) multi-link device (MLD), comprising: establishing a plurality of links for communication with non-AP MLDs, where one or more non-AP MLDs including the non-AP MLD communicate with the AP on each link of the plurality of links; and taking one or more actions designed to ensure that the non-AP MLD is able to receive group-addressed frames.

[0148] Aspect 2: The method of aspect 1, wherein the non-AP MLD is operating in an enhanced multi-link single radio (EMLSR) mode.

[0149] Aspect 3: The method of aspect 1 or 2, wherein the one or more actions include transmitting a trigger frame preceding transmission of the group addressing frame, the trigger frame indicating the non-AP MLD to enter a full capability state to receive the group addressing frame via a first link of the multiple links.

[0150] Aspect 4: The method of aspect 3, wherein the trigger frame includes a first control type frame including a Buffer Status Report Poll (BSRP) or a Multiple User (MU) Request to Send (RTS) (MU-RTS), or a second control type frame used to indicate to all non-AP MLDs operating in Enhanced Multi-Link Single Radio (EMLSR) mode in communication with the AP, including the non-AP MLDs, to each enter a full capability state to receive group-addressed frames over the first link.

[0151] Aspect 5: The method of any one of aspects 1 to 4, wherein the one or more actions include buffering the group addressing frame until a predetermined time to enable the non-AP MLD to enter a full capability state to receive the group addressing frame via a first link of the multiple links, and transmitting the group addressing frame via the first link at the predetermined time.

[0152] Aspect 6: The method of aspect 5, wherein the predetermined time includes a time after transmission of a delivery traffic indication message (DTIM) beacon during a target beacon transmission time (TBTT) interval configured by the AP MLD for the first link.

[0153] Aspect 7: The method of any one of aspects 1 to 6, wherein the one or more actions include initiating a frame exchange sequence on a first link of the plurality of links by transmitting a control type frame to the non-AP MLD via the first link, and prior to initiating the frame exchange sequence, the AP MLD determines that a second link of the plurality of links is an anchor link selected by the non-AP MLD, and the frame exchange sequence does not overlap in time with a group addressing frame transmission on the second link.

[0154] Aspect 8: The method of any one of aspects 1 to 7, wherein the one or more actions include determining that a first time period for a first link of the plurality of links does not overlap in time with a second time period for a second link of the plurality of links, wherein the first time period is used for transmitting DTIM beacons and group addressing frames to the non-AP MLD via the first link and the second time period is used for transmitting DTIM beacons and group addressing frames to the non-AP MLD via the second link; and refraining from scheduling frame exchanges with the non-AP MLD via the second link during the first time period or via the first link during the second time period.

[0155] Aspect 9: The method of aspect 8, in which, when refraining from scheduling a frame exchange with a non-AP MLD, the AP MLD schedules at least one other frame exchange with at least one of a non-AP MLD not operating in EMLSR mode or a non-AP station (STA).

[0156] Aspect 10: The method of any one of aspects 1 to 9, wherein the one or more actions include determining that a first time period for a first link of the plurality of links at least partially overlaps in time with a second time period for a second link of the plurality of links, wherein the first time period is used for transmitting DTIM beacons and group addressing frames to the non-AP MLD via the first link and the second time period is used for transmitting DTIM beacons and group addressing frames to the non-AP MLD via the second link; determining that a duration of the first time period is longer than a duration of the second time period; and refraining from scheduling frame exchanges with the non-AP MLD via the second link during a portion of the first time period that does not overlap in time with the second time period.

[0157] Aspect 11: The method of aspect 10, wherein when refraining from scheduling a frame exchange with a non-AP MLD over a second link during a portion of a first period that does not overlap in time with the second period, the AP MLD schedules at least one other frame exchange with at least one of a non-AP MLD or a non-AP station (STA) that is not operating in EMLSR mode.

[0158] Aspect 12: The method of any one of aspects 1 to 11, wherein the one or more actions include indicating to a non-AP MLD a relative rate for group-addressed frame delivery on different links.

[0159] Aspect 13: The method of any one of aspects 1 to 12, when an anchor link associated with the non-AP MLD is not known by the AP MLD, the one or more actions include: determining a TBTT period configured by the AP MLD for each link of the multiple links; determining a first link of the multiple links having a determined TBTT period that starts first in time within each of the determined TBTT periods for each of the links; and delaying scheduling of frame exchanges with the non-AP MLD via each link of the multiple links, except for the first link.

[0160] Aspect 14: A method of wireless communication by a non-access point (non-AP) multi-link device (MLD) operating in an enhanced multi-link single radio (EMLSR) mode, the method including: establishing a plurality of links for communication with an AP MLD, where one or more non-AP MLDs including the non-AP MLD communicate with an AP on each link of the plurality of links; and taking one or more actions designed to ensure that the non-AP MLD is able to receive group-addressed frames.

[0161] Aspect 15: The method of aspect 14, wherein the group addressing frame includes at least one of a first bit indicating to the non-AP MLD that a subsequent group addressing frame will be transmitted by the AP MLD, or a second bit indicating to the non-AP MLD that no additional group addressing frames will be transmitted by the AP MLD, triggering the non-AP MLD to switch from a full capability state to a listen state.

[0162] Aspect 16: The method of aspect 14 or 15, wherein the one or more actions include selecting a first link of the plurality of links as an anchor link and providing an indication of the anchor link to the AP MLD, and the AP MLD initiates a frame exchange sequence on another link of the plurality of links based at least in part on the indication.

[0163] Aspect 17: The method of aspect 16, wherein the indication of the anchor link provided to the AP includes at least one of an indication of a static anchor link selection by the non-AP MLD provided during association between the non-AP MLD and the AP, a semi-static anchor link selection by the non-AP MLD that is initially provided during association between the non-AP MLD and the AP and subsequently updated transmission of an action frame to the AP, or a dynamic anchor link selection by the non-AP MLD that is dynamically updated via transmission of a control type frame to the AP.

[0164] Aspect 18: A method according to any one of aspects 15 to 17, wherein the one or more actions include selecting to miss another group addressing frame in order to receive the group addressing frame, the other group addressing frame being transmitted on a first link of the plurality of links, and the group addressing frame being transmitted on a second link of the plurality of links.

[0165] Aspect 19: The method of aspect 18, wherein selecting to miss another group addressing frame in order to receive the group addressing frame is based at least in part on an indication from the AP MLD of a relative rate for group addressing frame delivery on different links.

[0166] Aspect 20: The method of aspect 18 or 19, wherein selecting to miss a group addressing frame in order to receive another group addressing frame is based at least in part on the priority of one or more frames of the scheduled frame exchange sequence.

[0167] Aspect 21: The method of any one of aspects 14 to 20, wherein the one or more actions include initiating a frame exchange sequence with the AP MLD over a first link of the multiple links, and prior to initiating the frame exchange sequence, the non-AP MLD determines that the frame exchange sequence does not overlap in time with a group addressing frame transmission configured for the non-AP MLD on a second link of the multiple links, the second link including an anchor link selected by the non-AP MLD.

[0168] Aspect 22: The method of any one of aspects 14 to 21, wherein the one or more actions include receiving a control type frame from the AP MLD initiating a frame exchange with a non-AP MLD via a first link of the multiple links, and determining to ignore the control type frame or respond to the control type frame via signaling indicating unavailability of the non-AP MLD for the first link when a time difference between when the control type frame is received and a start of a TBTT configured by the AP MLD on a second link of the multiple links is less than a threshold time.

[0169] Aspect 23: The method of aspect 22, wherein the signaling indicating unavailability of non-AP MLD for the first link is via a new A-control field of a medium access control (MAC) header in at least one response frame or a power management (PM) bit of a frame control field of a MAC header in the response frame.

[0170] Aspect 24: The method of aspect 23, wherein when unavailability of the non-AP MLD for the first link is via a new A-control field of a MAC header in at least one response frame, the at least one response frame includes an aggregate MAC protocol data unit (A-MPDU), a first MPDU of the response frame indicates a Buffer Status Report (BSR), the control type frame received from the AP MLD is a Buffer Status Report Poll (BSRP), and a second MPDU of the response frame indicates unavailability via the new A-control field.

[0171] Aspect 25: The method of aspect 24, when at least one response frame includes one or more quality of service (QoS) null frames.

[0172] Aspect 26: The method of aspect 25, wherein the at least one response frame includes a QoS Null frame having a QoS control field indicating BSR and a subfield indicating unavailability.

[0173] Aspect 27: The method of any one of aspects 14 to 26, wherein the one or more actions include receiving a control type frame from the AP MLD over a first link of the multiple links to initiate a frame exchange sequence with a non-AP MLD for communication of one or more downlink (DL) frames and uplink (UL) frames; engaging in the frame exchange sequence when a time difference between when the control type frame is received and a start of a TBTT configured by the AP MLD on a second link of the multiple links is greater than a first threshold time, including determining, before transmitting a last UL frame of the frame exchange sequence, that a start of a TBTT configured by the AP MLD on the second link occurs within a second threshold time; and transmitting a last UL frame with an A-control field or PM bit indicating unavailability of the non-AP MLD based at least in part on determining, which triggers an end of the frame exchange sequence.

[0174] Aspect 28: The method of aspect 27, wherein the last UL frame is a UL data frame or a UL control frame.

[0175] Aspect 29: The method of any one of aspects 14 to 28, wherein the one or more actions include determining that a start of a TBTT configured by the AP MLD on a first link of the multiple links occurs within a threshold time; and transmitting an unrequested frame to the AP MLD explicitly indicating unavailability of the non-AP MLD for a second link of the multiple links, where the unavailability indicated in the unrequested frame indicates to the AP MLD to refrain from initiating frame exchange with the non-AP MLD on the second link.

[0176] Aspect 30: The method of aspect 29, wherein the explicitly indicated unavailability is indicated via a PM bit of a non-request frame.

[0177] Aspect 31: The method of aspect 29 or 30, wherein the non-request frame is a QoS null frame.

[0178] Embodiment 32: An apparatus comprising means for carrying out the method according to any one of embodiments 1 to 31.

[0179] Aspect 33. An apparatus including at least one processor and a memory coupled to the at least one processor, wherein the memory and the at least one processor are configured to execute a method according to any one of aspects 1 to 31.

[0180] Aspect 34. A computer-readable medium having stored thereon computer-executable code for wireless communication that, when executed by at least one processor, causes an apparatus to perform a method according to any one of aspects 1 to 31.

[0181] Additional Considerations As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" can include calculating, computing, processing, deriving, investigating, searching (such as searching a table, database, or another data structure), ascertaining, and the like. Also, "determining" can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Also, "determining / determining" can include resolving, selecting, electing, establishing, and the like.

[0182] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to encompass a, b, c, ab, ac, bc, and abc.

[0183] The various example logic, logic blocks, modules, circuits, and algorithmic processes described in connection with the implementations disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. Interchangeability between hardware and software has been described generally in terms of functionality and illustrated in the various example components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware or software depends on the particular application and design constraints imposed on the overall system.

[0184] The hardware and data processing devices used to implement the various example logic, logic blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed using general purpose single-chip or multi-chip processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, certain processes and methods may be performed by circuitry specific to a given function.

[0185] In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware, or any combination thereof, including the structures disclosed herein and their structural equivalents. Implementations of the subject matter described herein may also be implemented as one or more computer programs, i.e., as one or more modules of computer program instructions encoded on a computer storage medium for execution by or to control the operation of a data processing apparatus.

[0186] If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. The processes of the methods or algorithms disclosed herein may be executed in processor-executable software modules that may reside on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium that may enable a computer program to be transferred from one place to another. A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection may be properly termed a computer-readable medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where disks typically reproduce data magnetically and discs reproduce data optically using lasers. Combinations of the above should also be included within the scope of computer readable media. Additionally, operations of a method or algorithm may reside on machine readable and computer readable media, which may be embodied in a computer program product as one or any combination or set of code and instructions.

[0187] Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other implementations without departing from the spirit or scope of the disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and novel features disclosed herein.

[0188] Some features described herein in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented in multiple implementations separately or in any suitable subcombination. Furthermore, although features may be described above as working in some combinations and may even initially be claimed as such, one or more features from a claimed combination may in some cases be deleted from the combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination.

[0189] Similarly, although operations are shown in the figures in a particular order, this should not be understood as requiring such operations to be performed in the particular order or sequential order shown, or that all of the operations shown be performed, to achieve desirable results. Furthermore, the figures may generally depict another exemplary process in the form of a flow diagram. However, other operations not shown may be incorporated into the exemplary process depicted in the schematic. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the depicted operations. In some circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the program components and systems described may generally be integrated together in a single software product or packaged in multiple software products. In addition, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve desirable results.

Claims

1. 1. A method of wireless communication by an access point (AP) multi-link device (MLD), comprising: Establishing a plurality of links for communication with a non-AP MLD, wherein the non-AP MLD communicates with the AP MLD over one or more links of the plurality of links, and the non-AP MLD operates in an enhanced multi-link single radio (EMLSR) mode, the EMLSR mode being associated with a 1x1 listen state in which the non-AP MLD is configured to listen on two or more links simultaneously; taking one or more actions designed to ensure that the non-AP MLD is able to receive group-addressed frames; Including, The one or more actions are: buffering the group-addressed frame until a predetermined time to allow the non-AP MLD to enter a full capacity state for receiving the group-addressed frame via a first link of the plurality of links; In the full capability state associated with the EMLSR mode, the non-AP MLD is configured to transmit and receive frames on one of the plurality of links.

2. The one or more actions: transmitting a trigger frame preceding the transmission of the group-addressed frame, the trigger frame indicating the non-AP MLD to enter the full capability state for receiving the group-addressed frame via the first link of the plurality of links, the trigger frame comprising: a first control type frame containing a Buffer Status Report Poll (BSRP) or a Multiple User (MU) Request to Send (RTSm) (MU-RTS); or a second control type frame used to indicate to all non-AP MLDs operating in an enhanced multi-link single radio (EMLSR) mode in communication with the AP, including the non-AP MLD, that each enter the full capability state for receiving the group-addressed frame via the first link; Including, The method of claim 1.

3. The one or more actions: transmitting the group-addressed frame over the first link at the predetermined time; wherein the predetermined time comprises a time after transmission of a Delivery Traffic Indication Message (DTIM) beacon during a Target Beacon Transmission Time (TBTT) interval configured by the AP MLD for the first link. The method of claim 1.

4. The one or more actions: and initiating a frame exchange sequence on the first link of the plurality of links by transmitting a control type frame to the non-AP MLD via the first link, wherein before initiating the frame exchange sequence, the AP MLD: a second link of the plurality of links is an anchor link selected by the non-AP MLD; the frame exchange sequence does not overlap in time with group-addressed frame transmissions on the second link; and decide, The method of claim 1.

5. The one or more actions: determining that a first time period for a first link of the plurality of links does not overlap in time with a second time period for a second link of the plurality of links, the first time period being used to transmit DTIM beacons and group addressing frames to the non-AP MLD via the first link and the second time period being used to transmit DTIM beacons and the group addressing frames to the non-AP MLD via the second link; the second link during the first period of time; or the first link during the second period; refraining from scheduling frame exchanges with the non-AP MLD via Including, The method of claim 1.

6. When refraining from scheduling the frame exchange with the non-AP MLD, the AP MLD: a non-AP MLD not operating in the EMLSR mode, or Non-AP station (STA), scheduling at least one other frame exchange with at least one of the The method of claim 5.

7. The one or more actions: determining that a first time period for a first link of the plurality of links at least partially overlaps in time with a second time period for a second link of the plurality of links, the first time period being used to transmit DTIM beacons and the group addressing frames to the non-AP MLD via the first link and the second time period being used to transmit DTIM beacons and group addressing frames to the non-AP MLD via the second link; determining that the first period of time is longer than the second period of time; refraining from scheduling frame exchanges with the non-AP MLD over the second link during a portion of the first time period that does not overlap in time with the second time period; Including, The method of claim 1.

8. the AP MLD when refraining from scheduling the frame exchange with the non-AP MLD over the second link during the portion of the first period that does not overlap in time with the second period; a non-AP MLD not operating in the EMLSR mode, or Non-AP station (STA), scheduling at least one other frame exchange with at least one of the The method of claim 7.

9. The method of claim 1 , wherein the one or more actions include indicating to the non-AP MLD relative rates for group-addressed frame delivery on different links.

10. When an anchor link associated with the non-AP MLD is not known by the AP MLD, the one or more actions include: determining an AP MLD configured TBTT period for each link of the plurality of links; determining the first link of the plurality of links having the determined TBTT period that begins first in time within each of the determined TBTT periods for each of the links; delaying scheduling of frame exchanges with the non-AP MLD over each link of the plurality of links except for the first link; Including, The method of claim 1.

11. A wireless communication device comprising means configured to perform a method according to any one of claims 1 to 10.

12. 1. A method of wireless communication by a non-access point (non-AP) multi-link device (MLD) operating in an enhanced multi-link single radio (EMLSR) mode, comprising: The EMLSR mode is associated with a 1x1 listen state in which the non-AP MLD is configured to listen on two or more EMLSR links simultaneously; The method comprises: establishing a plurality of links for communication with an AP MLD, wherein the non-AP MLD communicates with the AP over one or more of the plurality of links; taking one or more actions designed to ensure that the non-AP MLD is able to receive group-addressed frames; Including, The one or more actions are: receiving a control type frame from the AP MLD that initiates a frame exchange with the non-AP MLD via a first link of the plurality of links; when a time difference between when the control type frame is received and the start of a TBTT configured by the AP MLD on a second link of the plurality of links is less than a threshold time; Ignoring the control type frame, or responding to the control type frame via signaling indicating unavailability of the non-AP MLD for the first link; and determining that: Including, method.

13. the signaling indicating the unavailability of the non-AP MLD for the first link comprises: a new A-control field in the Medium Access Control (MAC) header in at least one response frame; or a power management (PM) bit in the frame control field of the MAC header in the response frame; Through The method of claim 12.

14. A wireless communication device comprising means configured to perform the method of claim 12 or 13.

15. A computer program comprising program instructions which, when executed by at least one processor, cause an apparatus to perform a method according to any one of claims 1 to 10 or claims 12 and 13.

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