Buffer status report frame transmission in a multi-link communication environment

Abstract

A non-access point (non-AP) multi-link device (MLD) transmits a frame of a traffic identifier (TID) on a first link to an access point (AP) MLD, where the TID is mapped by a TID-to-link mapping. The non-AP MLD receives a trigger frame on a second link from the AP MLD, where the TID is not mapped by the TID-to-link mapping. In response to the trigger frame, the non-AP MLD transmits a quality of service (QoS) null frame including the TID on the second link to the AP MLD.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 304,031, filed January 28, 2022, which is incorporated by reference herein in its entirety. Summary of the Invention [Means for solving the problem]

[0002] In this disclosure, various embodiments are presented as examples of how the disclosed technology may be implemented and / or how the disclosed technology may be practiced in environments and scenarios. It will be apparent to those skilled in the relevant art that various changes in form and details may be made without departing from the scope. After reading the specification, it will be apparent to those skilled in the relevant art how to implement alternative embodiments. This embodiment should not be limited by any of the exemplary embodiments. The embodiments of the present disclosure are described with reference to the accompanying drawings. Limitations, features, and / or elements from the disclosed exemplary embodiments may be combined to create further embodiments within the scope of the present disclosure. The figures that highlight features and advantages are shown only as examples. The disclosed architecture is sufficiently flexible and configurable to be utilized in ways other than those shown. For example, the actions listed in any flowchart may be rearranged in some embodiments or used only optionally.

[0003] The embodiments may be configured to operate as needed. The disclosed mechanisms may be implemented when certain criteria are met, for example, at a station, an access point, a wireless environment, a network, a combination of the above, etc. Exemplary criteria may be based at least in part, for example, on wireless device or network node configuration, traffic load, initial system setup, packet size, traffic characteristics, a combination of the above, etc. When one or more criteria are met, various exemplary embodiments may be applied. Thus, it may be possible to implement exemplary embodiments that selectively implement the disclosed protocols. [Brief description of the drawings]

[0004] Some examples of various embodiments of the present disclosure are described herein with reference to the drawings.

[0005] [Figure 1] FIG. 1 illustrates an example wireless communication network in which embodiments of the present disclosure may be implemented. [Diagram 2] FIG. 2 is a block diagram illustrating an exemplary implementation of a station (STA) and an access point (AP). [Diagram 3] FIG. 3 shows an example of a Medium Access Control (MAC) frame format. [Figure 4] FIG. 4 shows an example of a Quality of Service (QoS) null frame indicating buffer status information. [Diagram 5] FIG. 5 illustrates an example format of a physical layer (PHY) protocol data unit (PPDU). [Figure 6] FIG. 6 illustrates an example embodiment including buffer status reporting by STAs, scheduling of uplink multi-user (MU) transmissions by the AP, and sending of scheduled uplink transmissions by the STAs. [Figure 7] FIG. 7 illustrates an exemplary reference model of a multi-link device (MLD). [Figure 8] FIG. 8 shows an example of an AP MLD and an associated non-AP MLD. [Figure 9] FIG. 9 shows an example of a multi-link setup between an AP MLD and a non-AP MLD. [Figure 10] FIG. 10 illustrates an example of traffic identifier (TID)-to-link mapping in a multi-link communication environment. [Figure 11] FIG. 11 illustrates existing buffer status reporting in the presence of TID-to-link mapping in an exemplary multi-link communication environment. [Figure 12] 12-15 illustrate an example method for buffer status reporting in the presence of TID-to-link mapping, according to an embodiment of the present disclosure. [Figure 13] 12-15 illustrate an example method for buffer status reporting in the presence of TID-to-link mapping, according to an embodiment of the present disclosure. [Figure 14] 12-15 illustrate an example method for buffer status reporting in the presence of TID-to-link mapping, according to an embodiment of the present disclosure. [Figure 15] 12-15 illustrate an example method for buffer status reporting in the presence of TID-to-link mapping, according to an embodiment of the present disclosure. [Figure 16] FIG. 16 illustrates an example process for transmitting buffer status according to an embodiment of the disclosure. [Figure 17] FIG. 17 illustrates an example process for receiving buffer status according to an embodiment of the disclosure. [Figure 18] FIG. 18 illustrates an exemplary process, according to one embodiment. [Figure 19] FIG. 19 illustrates an exemplary process, according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] As used herein, "a" and "an" and similar phrases are to be interpreted as "at least one" and "one or more". Similarly, any term ending with the suffix "(s)" should be interpreted as "at least one" and "one or more". As used herein, the term "may" should be interpreted as "may be, for example". In other words, the term "may" indicates that the phrase following the term "may" is an example of multiple preferred possibilities, which may or may not be used by one or more of the various embodiments. As used herein, the terms "comprises" and "consists of" recite one or more components of a described element. The term "comprises" is interchangeable with "includes" and does not exclude unrecited components included in the described element. In contrast, "consists of" provides a complete recitation of one or more components of a described element. As used herein, the term "based on" may be interpreted as "based at least in part on" rather than "based only on". As used herein, the term "and / or" refers to any possible combination of the listed elements. For example, "A, B, and / or C" can refer to A, B, C, A and B, A and C, B and C, or A, B, and C.

[0007] If A and B are sets and all elements of A are also elements of B, then A is called a subset of B. Only non-empty sets and subsets are considered herein. For example, possible subsets of B={STA1, STA2} are {STA1}, {STA2}, and {STA1, STA2}. The phrase "based on" (or equivalently "based at least on") indicates that the phrase following the term "based on" is an example of a number of suitable possibilities that may or may not be used in one or more of the various embodiments. The phrase "in response to" (or equivalently "in response at least to") indicates that the phrase following the phrase "in response to" is an example of a number of suitable possibilities that may or may not be used in one or more of the various embodiments. The phrase "in response to" (or equivalently "in response at least to") indicates that the phrase following the phrase "in response to" is an example of a number of suitable possibilities that may or may not be used in one or more of the various embodiments. The phrase "adopted / used" (or equivalently "adopted / used at least") indicates that the phrase following the phrase "adopted / used" is one example of many suitable possibilities that may or may not be used in one or more of the various embodiments.

[0008] The term configured may relate to the capacity of a device, whether the device is in an operational or non-operational state. Configured may refer to a particular setting of a device that affects the operational characteristics of the device, whether the device is in an operational or non-operational state. In other words, hardware, software, firmware, registers, memory values, etc. may be "configured" within a device, whether the device is in an operational or non-operational state, to provide the device with a particular characteristic. A term such as "a control message originating at a device" may mean that a control message has parameters that can be used to configure a particular characteristic in a device or to implement a particular action in a device, whether the device is in an operational or non-operational state.

[0009] In this disclosure, a parameter (or equivalently referred to as a field, or information element: IE) may contain one or more information objects, which may contain one or more other objects. For example, if parameter (IE)N contains parameter (IE)M, which contains parameter (IE)K, which contains parameter (IE)J, then, e.g., N contains K and N contains J. In an example embodiment, when one or more messages / frames contain multiple parameters, it means that a parameter of the multiple parameters is included in at least one of the one or more messages / frames, but need not be included in each of the one or more messages / frames.

[0010] Many of the presented features are described as optional through the use of "may" or through the use of parentheses. For the sake of brevity and readability, this disclosure does not explicitly describe each and every combination that may be obtained by selecting from a set of optional features. This disclosure should be construed as explicitly disclosing all such variations. For example, a system described as having three optional features may be embodied in seven ways, i.e., with only one of the three possible features, any two of the three features, or three of the three features.

[0011] Many of the elements described in the disclosed embodiments may be implemented as modules, where a module is defined as an element that performs a defined function and has a defined interface to other elements. The modules described in this disclosure may be implemented in hardware, software in combination with hardware, firmware, wetware (e.g., hardware with biological elements), or a combination thereof, which may be behaviorally equivalent. For example, a module may be implemented in software routines written in a computer language configured to run on a hardware machine (C, C++, Fortran, Java, Basic, Matlab, etc.) or Simulink, Stateflow, GNU Octave, or LabVIEW MathScript. It may also be possible to implement modules using physical hardware that incorporates discrete or programmable analog, digital, and / or quantum hardware. Examples of programmable hardware include computers, microcontrollers, microprocessors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and complex programmable logic devices (CPLDs). Computers, microcontrollers, and microprocessors are programmed using languages ​​such as assembly, C, C++, etc. FPGAs, ASICs, and CPLDs are often programmed using hardware description languages ​​(HDLs) such as Verilog or VHSIC Hardware Description Language (VHDL), which configure the connections between the less functional internal hardware modules of the programmable device. To achieve a functional modular result, the above techniques are often used in combination.

[0012] FIG. 1 illustrates an example wireless communication network in which embodiments of the present disclosure may be implemented.

[0013] 1, an exemplary wireless communication network may include an Institute of Electrical and Electronics Engineers (IEEE) 802.11 (WLAN) infrastructure network 102. The WLAN infrastructure network 102 may include one or more basic service sets (BSSs) 110 and 120, and a distribution system (DS) 130.

[0014] Each of the BSSs 110-1 and 110-2 includes a set of access points (APs or AP STAs) and at least one station (STA or non-AP STA). For example, the BSS 110-1 includes the AP 104-1 and the STA 106-1, and the BSS 110-2 includes the AP 104-2 and the STAs 106-2 and 106-3. The APs and at least one STA in a BSS perform an association procedure to communicate with each other.

[0015] DS 130 may be configured to connect BSS 110-1 and BSS 110-2. In this manner, DS 130 may enable extended service set (ESS) 150. Within ESS 150, APs 104-1 and 104-2 are connected via DS 130 and may have the same service set identification (SSID).

[0016] The WLAN infrastructure network 102 may be coupled to one or more external networks. For example, as shown in FIG. 1, the WLAN infrastructure network 102 may be connected to another network 108 (e.g., 802.X) through a portal 140. The portal 140 may act as a bridge connecting the DS 130 of the WLAN infrastructure network 102 to the other network 108.

[0017] The exemplary wireless communication network shown in Figure 1 may further include one or more ad-hoc networks or independent BSSs (IBSSs). An ad-hoc network or IBSS is a network including multiple STAs that are within communication range of each other. The multiple STAs are configured to communicate with each other using direct peer-to-peer communication (i.e., not through an AP).

[0018] For example, in FIG. 1, STAs 106-4, 106-5, and 106-6 may be configured to form a first IBSS 112-1. Similarly, STAs 106-7 and 106-8 may be configured to form a second IBSS 112-2. An IBSS does not include an AP and therefore does not include a centralized management entity. Rather, the STAs in an IBSS are managed in a distributed manner. The STAs that form an IBSS may be fixed or mobile.

[0019] The STA as a given functional medium may include a medium access control (MAC) layer conforming to the IEEE 802.11 standard. A physical layer interface for the wireless medium may be used between the AP and the non-AP station (STA). The STA may also be referred to using various other terms, including a mobile terminal, a wireless device, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile subscriber unit, or a user. For example, the term "user" may be used to indicate a STA involved in uplink multi-user multiple-input, multiple-output (MU MIMO) and / or uplink orthogonal frequency division multiple access (OFDMA) transmissions.

[0020] A physical layer (PHY) protocol data unit (PPDU) may be a composite structure that includes a PHY preamble and a payload in the form of a PLCP service data unit (PSDU). For example, a PSDU may include a PHY Convergence Protocol (PLCP) preamble and a header and / or one or more MAC protocol data units (MPDUs). Information provided in the PHY preamble may be used by a receiving device to decode subsequent data in the PSDU. If the PPDU is transmitted over a bonded channel (a channel formed via channel bonding), the preamble field may be replicated and transmitted in each of multiple constituent channels. The PHY preamble may include both a legacy portion (or a "legacy preamble") and a non-legacy portion (or a "non-legacy preamble"). The legacy preamble may be used for packet detection, automatic gain control, and channel estimation, among other uses. The legacy preamble may also generally be used to maintain compatibility with legacy devices. The format, coding, and information provided in the non-legacy portion of the preamble is based on the particular IEEE 802.11 protocol used to transmit the payload.

[0021] A frequency band may include one or more sub-bands or frequency channels. For example, a PPDU conforming to the IEEE 802.11n, 802.11ac, 802.11ax, and / or 802.11be standard amendments may be transmitted over the 2.4 GHz, 5 GHz, and / or 6 GHz bands, each of which may be divided into multiple 20 MHz channels. The PPDU may be transmitted over a physical channel having a minimum bandwidth of 20 MHz. Larger channels may be formed through channel bonding. For example, the PPDU may be transmitted over a physical channel having a bandwidth of 40 MHz, 80 MHz, 160 MHz, or 520 MHz by bonding multiple 20 MHz channels together.

[0022] 2 is a block diagram illustrating an example implementation of the STA 210 and the AP 260. As shown in FIG. 2, the STA 210 may include at least one processor 220, a memory 230, and at least one transceiver 240. The AP 260 may include at least one processor 270, a memory 280, and at least one transceiver 290. The processor 220 / 270 may be operatively connected to the transceiver 240 / 290.

[0023] The transceiver 240 / 290 may be configured to transmit / receive wireless signals. In one embodiment, the transceiver 240 / 290 may implement a PHY layer of a corresponding device (STA 210 or AP 260).

[0024] In one embodiment, the STAs 210 and / or the APs 260 may be multi-link devices (MLDs), i.e., devices capable of operating on multiple links, as defined by the IEEE 802.11be standard amendment. As such, the STAs 210 and / or the APs 260 may each have multiple PHY layers. The multiple PHY layers may be implemented using one or more of the transceivers 240 / 290.

[0025] The processor 220 / 270 may implement the functionality of the PHY layer, MAC layer, and / or Logical Link Control (LLC) layer of the corresponding device (STA 210 or AP 260).

[0026] The processor 220 / 270 and / or the transceiver 240 / 290 may include an application specific integrated circuit (ASIC), other chipset, logic circuit, and / or data processor. The memory 230 / 280 may include read only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage units.

[0027] When the embodiments are implemented by software, the techniques (or methods) described herein may be implemented with modules (e.g., processes, functions, etc.) that perform functions described herein. The modules may be stored in memory 230 / 280 and executed by processor 220 / 270. Memory 230 / 280 may be implemented (or located) within processor 220 / 270 or external to processor 220 / 270. Memory 230 / 280 may be operatively connected to processor 220 / 270 via various means known in the art.

[0028] 3 illustrates an example format of a MAC frame. In operation, a STA may construct a subset of MAC frames for transmission and may decode a subset of MAC frames received upon validation. The particular subset of frames that a STA may construct and / or decode may be determined by the capabilities supported by the STA. A STA may validate received MAC frames using a Frame Check Sequence (FCS) included within the frame and may interpret certain fields from the MAC header of all frames.

[0029] As shown in FIG. 3, a MAC frame includes a MAC header, a variable-length frame body, and a Frame Check Sequence (FCS).

[0030] The MAC header includes a Frame Control field, an optional Duration / ID field, an Address field, an optional Sequence Control field, an optional QoS Control field, and an optional HT Control field.

[0031] The frame control field includes the following subfields: protocol version, type, subtype, To DS, From DS, additional fragments, retry, power management, additional data, protected frame, and +HTC.

[0032] The Protocol Version subfield remains constant in size and placement across all revisions of the IEEE 802.11 standard. The value of the Protocol Version subfield is 0 for MAC frames.

[0033] The Type and Subtype subfields identify the function of the MAC frame. There are three frame types: Control, Data, and Management. Each frame type has several defined subtypes. Bits in the Subtype subfield are used to indicate a particular modification of the basic Data frame (Subtype 0). For example, in a Data frame, the most significant bit (MSB) of the Subtype subfield, bit 7 (B7) of the Frame Control field, is defined as the QoS subfield. When the QoS subfield is set to 1, it indicates a QoS subtype Data frame, which is a data frame that contains a QoS Control field in its MAC header. The second MSB of the Subtype field, bit 6 (B6) of the Frame Control field, when set to 1 in the Data subtype, indicates a data frame that does not contain a Frame Body field.

[0034] The To DS subfield indicates whether the data frame is heading to a distribution system (DS), and the From DS subfield indicates whether the data frame originated from a DS.

[0035] In all data or management frames that have a following separate fragment of the MAC Service Data Unit (MSDU) or MAC Management Protocol Data Unit (MMPDU) carried by the MAC frame, the additional fragments subfield is set to 1. It is set to 0 in all other frames in which the additional fragments subfield is present.

[0036] The Retry subfield is set to 1 in any data or management frame that is a retransmission of a previous frame. It is set to 0 in all other frames in which the Retry subfield is present. Receiving STAs use this indication to aid in the process of eliminating duplicate frames. These rules do not apply to frames transmitted by a STA under a blocking agreement.

[0037] The power management subfield is used to indicate the power management mode of the STA.

[0038] The additional data subfield indicates to a STA in power save (PS) mode that a bufferable unit (Bus) is buffered for that STA at the AP. The additional data subfield is valid in individually addressed data or management frames sent by the AP to the STA in PS mode. The additional data subfield is set to 1 to indicate to the STA that there is at least one additional buffered BU.

[0039] The Protected Frame subfield is set to 1 if the Frame Body field contains information that has been processed by a cryptographic encapsulation algorithm.

[0040] The +HTC subfield indicates that the MAC frame contains a HT control field.

[0041] The Duration / ID field of the MAC header indicates various contents depending on the frame type and subtype, as well as the QoS capabilities of the transmitting STA. For example, in a control frame of the Power Save Poll (PS-Poll) subtype, the Duration / ID field carries the Association Identifier (AID) of the STA that transmitted the frame in the 14 least significant bits (LSBs) and the two most significant bits (MSBs) are both set to 1. In other frames transmitted by the STA, the Duration / ID field contains a duration value (in microseconds) that is used by the receiver to update the Network Allocation Vector (NAV). The NAV is a counter that indicates to the STA the length of time that the STA should postpone access to the shared medium.

[0042] There may be up to four address fields present in the MAC frame format. These fields are used to indicate the Basic Service Set Identifier (BSSID), Source Address (SA), Destination Address (DA), Transmitting Address (TA), and Receiving Address (RA). A particular frame may not include some of the address fields. A particular address field usage may be specified by the relative position of the address field (1-4) within the MAC header, regardless of the type of address present in that field. Specifically, the Address 1 field always identifies the intended receiver of the frame, and the Address 2 field, if present, always identifies the transmitter of the frame.

[0043] The sequence control field contains two subfields: a sequence number subfield and a fragment number subfield. The sequence number subfield in a data frame indicates the sequence number of the MSDU (if not in an aggregated MSDU (A-MSDU)) or the A-MSDU. The sequence number subfield in a management frame indicates the sequence number of the frame. The fragment number subfield indicates the number of each fragment of an MSDU or MMPDU. The fragment number is set to 0 in the first fragment or fragments only of an MSDU or MMPDU and is incremented by 1 for each successive fragment of that MSDU or MMPDU. The fragment number is set to 0 in the MAC Protocol Data Unit (MPDU) containing the A-MSDU or in the MPDU containing an unfragmented MSDU or MMPDU. The fragment number remains unchanged for all retransmissions of a fragment.

[0044] The QoS Control field identifies the Traffic Category (TC) or Traffic Stream (TS) to which the MAC frame belongs. The QoS Control field may also indicate various other QoS-related, A-MSDU-related, and mesh-related information about the frame. This information can vary by frame type, frame subtype, and type of transmitting STA. The QoS Control field is present in all data frames with the QoS subfield of the subtype subfield equal to 1.

[0045] The HT Control field is present in QoS Data, QoS Null, and management frames as determined by the +HTC subfield of the Frame Control field.

[0046] The frame-body field is a variable-length field that contains information specific to individual frame types and subtypes. It may contain one or more MSDUs or MMPDUs. The minimum length of the frame-body is 0 octets.

[0047] The FCS field contains a 32-bit cyclic redundancy check (CRC) code that is calculated over all fields in the MAC header and the frame body.

[0048] Figure 4 shows an example of a QoS Null frame indicating buffer status information. A QoS Null frame refers to a QoS data frame having an empty frame body. The QoS Null frame includes a QoS Control field and an optional HT Control field that may include a Buffer Status Report (BSR) control subfield. The QoS Null frame indicating buffer status information may be transmitted by a STA to an AP.

[0049] The QoS Control field may include a Traffic Identifier (TID) subfield, an Ack Policy Indicator subfield, and a Queue Size subfield (or a Transmission Opportunity (TXOP) Duration Request subfield).

[0050] The TID subfield identifies the TC or TS of the traffic for which a TXOP is being requested through the settings of the Requested TXOP Duration or Queue Size subfields. The encoding of the TID subfield depends on the access policy (e.g., allowed values ​​0-7 for Enhanced Distributed Channel Access (EDCA) access policy to identify user priority for either TC or TS).

[0051] The Ack Policy Indicator subfield identifies, among other information, the acknowledgement policy to be followed when delivering the MPDU (eg, normal Ack, implicit Block Ack request, no Ack, Block Ack, etc.).

[0052] The Queue Size subfield is an 8-bit field that indicates the amount of buffered traffic for a given TC or TS at the STA for transmission to the AP identified by the receiving address of the frame containing the subfield. The Queue Size subfield is present in a QoS Null frame transmitted by a STA when bit 4 of the QoS Control field is set to 1. The AP may use the information contained in the Queue Size subfield to determine the t TXOP duration assigned to the STA or to determine the uplink (UL) resources assigned to the STA.

[0053] For frames transmitted by or to non-high efficiency (non-HE) STAs, the following rules may apply to queue size values. - The Queue Size value is the approximate total size, rounded up to the nearest multiple of 256 octets and expressed in units of 256 octets, of all MSDUs and A-MSDUs (excluding any MSDUs or A-MSDUs contained in the current QoS Data Frame) buffered at the STA in the delivery queue used for MSDUs and A-MSDUs with a TID value equal to the value indicated in the TID subfield of the QoS Control field. - A queue size value of 0 is used only to indicate that there is no traffic buffered in the queue used for the specified TID. - A queue size value of 254 is used for all sizes greater than 64,768 octets. - A queue size value of 255 is used to indicate an unspecified or unknown size.

[0054] For frames transmitted by a HE STA to a HE AP, the following rules may be applied to the queue size value:

[0055] The queue size value (QS) is the approximate total size in octets of all MSDUs and A-MSDUs buffered at the STA (including MSDUs or A-MSDUs contained in the same PSDU as the frame containing the queue size subfield) in the delivery queue used for MSDUs and A-MSDUs with a TID value equal to the value indicated in the TID subfield of the QoS Control field.

[0056] The Queue Size subfield includes a Scaling Factor subfield in bits B14-B15 of the QoS Control field and an Unscaled Value (UV) in bits B8-B13 of the QoS Control field. The Scaling Factor subfield provides the Scaling Factor (SF).

[0057] The STA obtains the queue size (QS) from the received QoS control field, which includes the scaling factor (SF) and the unscaled value (UV), as follows: QS= 16×UV (if SF equals 0), 1024+256×UV (when SF is equal to 1), 17 408+2048×UV (if SF is equal to 2), 148 480+32 768×UV (if SF is equal to 3 and UV is less than 62), > 2 147 328 (if SF is equal to 3 and UV is equal to 62), Unspecified or unknown (if SF equals 3 and UV equals 63).

[0058] The TXOP Duration Request subfield, which may be included instead of the Queue Size subfield, indicates the duration in 32 microseconds (us) over which the transmitting STA determines the need for the next TXOP for the specified TID. The TXOP Duration Request subfield is set to 0 to indicate that no TXOP is requested for the specified TID in the current Service Period (SP). The TXOP Duration Request subfield is set to a non-zero value to indicate a requested TXOP duration ranging from 32us to 8160us in increments of 32us.

[0059] The HT Control field may include a BSR Control subfield that may contain buffer status information used for UL MU operations. The BSR Control subfield may be formed from an Access Category Index (ACI) Bitmap subfield, a Delta TID subfield, an ACI High subfield, a Scaling Factor subfield, a Queue Size High subfield, and a Queue Size Total subfield of the HT Control field.

[0060] The ACI Bitmap subfield indicates the access category for which the buffer status was reported (e.g., B0: Best Effort (AC_BE), B1: Background (AC_BK), B2: Video (AC_VI), B3: Voice (AC_VO), etc.). Each bit in the ACI Bitmap subfield is set to 1 to indicate that the buffer status of the corresponding AC is included in the Queue Size Total subfield, and is set to 0 except that when the ACI Bitmap subfield is 0 and the Delta TID subfield is 3, the buffer status of all eight TIDs is included.

[0061] The Delta TID subfield, together with the value of the ACI Bitmap subfield, indicates the number of TIDs for which the STA is reporting buffer status.

[0062] The ACI High subfield indicates the ACI of the AC whose BSR is indicated in the Queue Size High subfield. The ACI to AC mappings are defined as ACI value 0 mapping to AC_BE, ACI value 1 mapping to AC_BK, ACI value 2 mapping to AC_VI, and ACI value 3 mapping to AC_VO.

[0063] The Scaling Factor subfield indicates the units SF of the Queue Size High and Queue Size Total subfields in octets.

[0064] The Queue Size High subfield indicates the amount of buffered traffic, in SF octets, for the AC identified by the ACI High subfield, intended for the STA identified by the receiving address of the frame containing the BSR Control subfield.

[0065] The Queue Size Total subfield indicates the amount of buffered traffic, in SF octets, for all Acs identified by the ACI Bitmap subfield, that is intended for the STA identified by the receiving address of the frame containing the BSR Control subfield.

[0066] The queue size values ​​in the Queue Size High and Queue Size Total subfields are the total sizes of all MSDUs and A-MSDUs buffered at the STA (including MSDUs or A-MSDUs contained in the same PSDU as the frame containing the BSR Control subfield) in the delivery queue used for the MSDUs and A-MSDUs associated with the AC specified in the ACI High and ACI Bitmap subfields, respectively, rounded up to the nearest multiple of SF octets.

[0067] A queue size value of 254 in the Queue Size High and Queue Size Total subfields indicates that the amount of buffered traffic is greater than 254 x SF octets. A queue size value of 255 in the Queue Size High and Queue Size Total subfields indicates that the amount of buffered traffic is of unspecified or unknown size. The queue size value of a QoS data frame that contains fragments may remain unchanged even if the amount of traffic added to the queue changes as successive fragments are transmitted.

[0068] The MAC service provides peer entities with the ability to exchange MSDUs. To support this service, the Local MAC transmits MSDUs to the peer MAC entity using the underlying PHY level services. These asynchronous MSDU transmissions are performed connectionless.

[0069] 5 illustrates an example format of a PPDU. As shown, the PPDU may include a PHY preamble, a PHY header, a PSDU, and tail and padding bits.

[0070] The PSDU may include one or more MPDUs, such as a QoS data frame, an MMPDU, a MAC control frame, or a QoS null frame. For an MPDU carrying a QoS data frame, the frame body of the MPDU may include an MSDU or an A-MSDU.

[0071] By default, MSDU transmission is best effort, i.e. there is no guarantee that a transmitted MSDU will be delivered successfully. However, QoS provisions use Traffic Identifiers (TIDs) to specify differentiated services per MSDU.

[0072] The STA may differentiate MSDU delivery according to the designated Traffic Category (TC) or Traffic Stream (TS) of each MSDU. The MAC sublayer entity determines the User Priority (UP) for an MSDU based on the TID value provided in the MSDU. The QoS facility supports eight UP values. The UP values ​​range from 0 to 7 and form a priority order, with 1 being the lowest value, 7 being the highest value, and 0 corresponding to 2-3.

[0073] An MSDU with a particular UP is said to belong to the traffic category with that UP. The UP may be provided with each MSDU directly with the UP parameters at the Medium Access Control Service Access Point (MAC SAP). A-MPDUs may contain MPDUs with different TID values.

[0074] STAs may deliver Buffer Status Reports (BSRs) to assist the AP in allocating UL MU resources. STAs may deliver BSRs implicitly in the QoS Control field or BSR Control subfield of any frame sent to the AP (unsolicited BSR) or may deliver BSRs explicitly in frames sent to the AP in response to a BSRP trigger frame (solicited BSR).

[0075] The buffer status reported in the QoS control field includes the queue size value for a given TID. The buffer status reported in the BSR control field includes the ACI bitmap, the delta TID, the high priority AC, and the two queue sizes.

[0076] The STA may report to the AP the buffer status of transmitted QoS Null frames and QoS Data frames in the QoS Control field, and of transmitted QoS Null frames, QoS Data frames, and management frames in the BSR Control subfield (if present), as defined below.

[0077] A STA may report the queue size for a given TID in the queue size subfield of the QoS Control field of a transmitted QoS Data or QoS Null frame, and the STA may set the queue size subfield to 255 to indicate an unknown / unspecified queue size for that TID. A STA may aggregate multiple QoS Data or QoS Null frames in an A-MPDU to report queue sizes for different TIDs.

[0078] The STA may report its buffer status in the BSR control subfield of a transmitted frame if the AP has indicated its support for receiving the BSR control subfield.

[0079] A high-efficiency (HE) STA may report the queue size of the preferred AC indicated by the ACI High subfield in the Queue Size High subfield of the BSR Control subfield. The STA may set the Queue Size High subfield to 255 to indicate an unknown / unspecified queue size for that AC.

[0080] The HE STAs may report the queue size of the ACs indicated by the ACI Bitmap subfield in the Queue Size Total subfield of the BSR Control subfield. The STAs may set the Queue Size Total subfield to 255 to indicate an unknown / unspecified BSR for those ACs.

[0081] FIG. 6 illustrates an example embodiment including buffer status reporting by STAs, scheduling of uplink multi-user (MU) transmissions by the AP, and sending of scheduled uplink transmissions by the STAs.

[0082] As shown, an AP may solicit one or more associated STAs (STA 1 and STA 2) for buffer status by transmitting a Buffer Status Report Polling (BSRP) trigger frame. Upon receiving the BSRP trigger frame, STA 1 and / or STA 2 may each generate a trigger-based (TB) PPDU if the BSRP trigger frame contains the 12 LSBs of the STA's AID in the user information field.

[0083] STA 1 and / or STA 2 may each include one or more QoS Null frames in the TB PPDU. The one or more QoS Null frames may include one or more QoS Control fields or one or more BSR Control subfields.

[0084] As mentioned above, the QoS Control field may include a queue size subfield for the TID for which the STA has a queue size to report to the AP. For example, as shown in FIG. 6, STA 1 may respond to a BSRP trigger frame from the AP by transmitting an A-MPDU including multiple QoS Null frames, each indicating the queue size of a respective TID, e.g., TID 0 and TID 2, in its respective QoS Control field. Similarly, STA 2 may respond to the BSRP trigger frame by transmitting an MPDU including a QoS Null frame, indicating the queue size of TID 2 in its QoS Control field.

[0085] The BSR Control subfield may include a Queue Size Total subfield that indicates the queue size of the AC indicated by the ACI Bitmap subfield, so that the STA has a queue size to report to the AP if the AP indicates support for receiving the BSR Control subfield. The STA sets the Delta TID, Scaling Factor, ACI High, and Queue Size High subfields of the BSR Control subfield.

[0086] Upon receiving the BSR from STA 1 and STA 2, the AP may send a basic trigger frame to allocate UL MU resources to STA 1 and STA 2. In response, STA 1 may send a TB PPDU containing QoS data frames with TID 0 and TID 2, and STA 2 may send a TB PPDU containing one or more QoS data frames with the TIDs. The AP may acknowledge the TB PPDUs sent from STA 1 and STA 2 by sending a Multi-STA Block Ack frame.

[0087] FIG. 7 illustrates an exemplary reference model of a multi-link device (MLD).

[0088] An MLD is an entity that can manage communications over multiple links. An MLD can be a logical entity and can have multiple associated stations (STAs). An MLD can be an Access Point MLD (AP MLD), where the STAs associated with the MLD are AP STAs (or APs). An MLD can be a Non-Access Point MLD (Non-AP MLD), where the STAs associated with the MLD are non-AP STAs (or STAs).

[0089] Communications across different frequency bands / channels may occur simultaneously or not depending on the capabilities of both the communicating AP MLD and non-AP MLD.

[0090] As shown in Figure 7, the MLD may have a single MAC Service Access Point (MAC-SAP) to the LLC layer, which contains the MAC data service. The MLD may support multiple MAC sublayers coordinated by a sublayer management entity (SME). Each AP STA (or non-AP STA) associated with an AP MLD (or non-AP MLD) has a different MAC address in the MLD.

[0091] The SME is responsible for coordinating the MAC Sublayer Management Entities (MLMEs) of the associated STAs of the MLD to maintain a single Robust Security Network Association (RSNA) key management entity as well as a single IEEE 802.1X authenticator or supplicant for multi-link operation (MLO).

[0092] The Multi-Link Operation (MLO) procedure allows a pair of MLDs to discover, synchronize, (de)authenticate, (re)associate, disassociate, and manage resources with each other on any common band or channel supported by both MLDs. The authenticator and MAC-SAP of an AP MLD may be identified by the same AP MLD MAC address. The supplicant and MAC-SAP of a non-AP MLD may be identified by the same non-AP MLD MAC address.

[0093] FIG. 8 shows an example of an AP MLD and an associated non-AP MLD.

[0094] As shown, the AP MLD has two associated APs (AP1 and AP2), and the non-AP MLD has two associated STAs (STA 1 and STA 2). The AP MLD and the non-AP MLD may be communicatively coupled by two links (Link 1 and Link 2). Link 1 is established between AP1 and STA1, and Link 2 is established between AP2 and STA2.

[0095] In general, the MAC addresses of an MLD and its associated STAs are different from each other. For example, as shown in Figure 8, an AP MLD may have a MAC address M, AP 1 may have a MAC address w, and AP 2 may have a MAC address x. Similarly, a non-AP MLD may have a MAC address P, STA 1 may have a MAC address y, and STA 2 may have a MAC address z.

[0096] As shown in Figure 8, at each MLD, the MAC sublayer may be further divided into an MLD upper MAC sublayer and an MLD lower MAC sublayer. The MLD upper MAC sublayer (MLD) performs functions that are common across all links. The MLD lower MAC sublayer performs functions that are local to each link. Some of the functions require joint processing of both the MLD upper and MLD lower MAC sublayers.

[0097] The MLD upper MAC sublayer function is - Authentication, association, and reassociation (between AP MLD and non-AP MLD), - Distribution of security associations (e.g., Pairwise Master Key Security Associations (PMKSA), Pairwise Transient Key Security Associations (PTKSA)) and Group Time Keys (GTK) / Integrity GTK (IGTK) / Beacon IGTK (BIGTK), - Sequence Number (SN) / Packet Number (PN) allocation for frames encrypted by Pairwise Transient Key (PTK) for unicast frames; - Encryption / decryption using PTK for unicast frames, - Selection of the MLD lower MAC sublayer for transmission (TID-to-link mapping); - Packet reordering to ensure in-order delivery for each block ack session; - Block Ack scoreboarding of individually addressed frames (in cooperation with the MLD lower MAC sublayer), optionally where the MLD upper MAC sublayer distributes Block Ack records on one link to the MLD lower MAC sublayer of the other link; - May include MLD level management information exchange / indication via the MLD lower MAC sublayer.

[0098] The MLD lower MAC sublayer function is - Maintenance of link-specific GTK / IGTK / BIGTK (between APs associated with AP MLDs and STAs associated with non-AP MLDs), - Link-specific encryption / decryption / integrity protection and PN assignment using GTK / IGTK / BIGTK (between APs associated with AP MLDs and STAs associated with non-AP MLDs), - Link-specific management information exchange / indication (e.g., beacons), - Link-specific control information exchange / indication (e.g. RTS / CTS, acknowledgments, etc.), - Power saving states and modes, - MAC address filtering for receiving frames, and - Block Ack scoreboarding of individually addressed frames (in cooperation with the MLD Upper MAC sublayer), optionally including the MLD Lower MAC sublayer receiving Block Ack records on other links from the MLD Upper MAC sublayer.

[0099] Multilink (re)setup between non-AP MLD and AP MLD may include an exchange of (re)association request / response frames. The (re)association request / response frame exchange for multilink setup may include both frames carrying basic multilink elements.

[0100] In the (re)association request frame, the non-AP MLD indicates the link requested for (re)setup, and the capabilities and operating parameters of the requested link. The non-AP MLD may request to (re)setup a link with a subset of APs associated with the AP MLD. The requested link for (re)setup, and the capabilities and operating parameters of the requested link are independent of the existing setup link with the associated AP MLD, and the capabilities and operating parameters of the setup link.

[0101] In the (re)association response frame, the AP MLD may indicate the requested links that are accepted and those that are rejected for (re)setup, as well as the capabilities and operational parameters of the requested links. The AP MLD may accept a subset of the links requested for (re)setup. The (re)association response frame is sent to the non-AP STA associated with the non-AP MLD that sent the (re)association request frame.

[0102] MLD requesting or approving multilink (re)setup for any two links ensures that each link is on a different non-overlapping channel. After successful multilink (re)setup between non-AP MLD and AP MLD, the non-AP MLD and AP MLD setup links for multilink operation, and the non-AP MLD is (re)associated with the AP MLD. For each setup link, the corresponding non-AP STA associated with the non-AP MLD is in the same association state as the non-AP MLD and associated with the corresponding AP associated with the AP MLD. For each setup link, the functionality between the non-AP STA and its associated AP is enabled unless the functionality is extended to the MLD level or specified otherwise.

[0103] Figure 9 shows an example of multi-link setup between AP MLD and non-AP MLD. As shown, AP MLD has three associated APs: AP 1 operating in the 2.4 GHz band, AP 2 operating in the 5 GHz band, and AP 3 operating in the 6 GHz band. Non-AP MLD has three associated STAs: non-AP STA 1 operating in the 2.4 GHz band, non-AP STA 2 operating in the 5 GHz band, and non-AP STA 3 operating in the 6 GHz band.

[0104] The non-AP MLD may initiate a multilink setup by non-AP STA 1 sending an association request frame to AP 1 associated with the AP MLD. In the association request frame, the transmitter address (TA) field is set to the MAC address of non-AP STA 1, and the receiver address (RA) field is set to the MAC address of AP 1. The association request frame includes the MLD MAC address of the non-AP MLD and basic multilink elements indicating complete information of non-AP STA 1, non-AP STA 2, and non-AP STA 3. The association request frame may request the setup of three links between the non-AP MLD and the AP MLD (a link between AP 1 and non-AP STA 1, a link between AP 2 and non-AP STA 2, and a link between AP 3 and non-AP STA 3).

[0105] The AP MLD may respond to the requested multilink setup by the AP sending an association response frame to non-AP STA 1 associated with the non-AP MLD. In the association response frame, the TA field is set to the MAC address of AP 1 and the RA field is set to the MAC address of non-AP STA 1. The association response frame includes the MLD MAC address of the AP MLD and basic multilink elements indicating the complete information of AP 1, AP 2, and AP 3. The association response frame indicates a successful multilink setup by setting up three links between the non-AP MLD and the AP MLD (Link 1 between AP 1 and non-AP STA 1, Link 2 between AP 2 and non-AP STA 2, and Link 3 between AP 3 and non-AP STA 3).

[0106] By default, all TIDs of non-AP MLD are mapped to all setup links, both uplink and downlink. The TID-to-link mapping mechanism allows AP MLD and non-AP MLD that have performed or are performing multi-link setup to specify how UL and DL QoS traffic corresponding to different TIDs (e.g., 0-7) can be assigned to setup links. In negotiated TID-to-link mapping, a TID can be mapped to a link set that is a subset of setup links, ranging from a single setup link to all setup links.

[0107] A setup link is defined as valid for non-AP MLD if at least one TID is mapped to that link in either DL or UL, and invalid if no TID is mapped to that link in both DL and UL. At any point in time, a TID is always mapped to at least one setup link in both DL and UL, which means that a TID-to-link mapping change can be valid and successful only if it does not result in a TID having a mapped link set consisting of zero setup links.

[0108] By default, all setup links are enabled. When a link is enabled for non-AP MLD, it may be used for exchanging individually addressed frames, subject to the power state of the non-AP STAs operating on the link. Only MSDUs or A-MSDUs with a TID mapped to the link may be transmitted on that link in the direction (DL / UL) corresponding to the TID-to-link mapping. Individually addressed management and control frames may be transmitted on any enabled link between the associated STAs of non-AP MLD and the corresponding AP of AP MLD, both on DL and UL.

[0109] When a link is disabled for non-AP MLD, the link may not be used for exchanging individually addressed frames between associated STAs of the non-AP MLD and the corresponding AP of the AP MLD.

[0110] If a TID is mapped in the UL to a set of links enabled for non-AP MLD, then non-AP MLD may transmit an individually addressed MSDU or A-MSDU corresponding to that TID using any link in this set of enabled links.

[0111] If a TID is mapped to a set of enabled links of a non-AP MLD in DL, the non-AP MLD may retrieve an individually addressed BU buffered in the AP MLD that is an MSDU or A-MSDU corresponding to the TID on any link in the set of enabled links. Conversely, the AP MLD may transmit an individually addressed MSDU or A-MSDU corresponding to the TID using any link in the set of enabled links, subject to the power state of the non-AP STAs on the respective link used.

[0112] When using the default mode, the non-AP MLD may obtain BUs buffered by the AP MLD on any setup link, but the AP MLD may recommend the link.

[0113] The non-AP MLD may obtain buffered BUs that are MMPDUs buffered at the AP MLD on any enabled link. The AP MLD may use any enabled link to transmit individually addressed bufferable management frames that are not measurement MMPDUs, subject to the power state of the non-AP STAs on the link used.

[0114] When a STA associated with a non-AP MLD is in active mode on a link with a set of mapped TIDs for DL ​​transmission, the associated AP associated with the AP MLD may transmit to the STA an MSDU / A-MSDU for the set of mapped TIDs for the non-AP MLD and an MMPDU that is not a measurement MMPDU for the non-AP MLD or its associated STAs, unless the frame is transmitted in active mode to another STA associated with the same non-AP MLD.

[0115] As mentioned above, in the default mapping mode, all TIDs are mapped to all setup links in DL and UL and all setup links are enabled. Non-AP MLD and AP MLD performing multi-link setup will operate in this mode if negotiation of TID-to-link mapping for different mappings does not occur, fails, or is removed.

[0116] In a multilink (re)setup procedure, if the AP MLD indicates support for negotiation of TID-to-link mapping, the non-AP MLD may initiate negotiation of TID-to-link mapping by including a TID-to-link mapping element in the (re)association request frame.

[0117] After receiving a (re)association request frame including a TID-to-link mapping element, the AP MLD may respond to the (re)association request frame according to the following rules: The AP MLD can approve the requested TID-to-link mapping indicated in the TID-to-link mapping element in the received (re)association request frame only if it approves multilink (re)setup for all links to which at least one TID is requested to be mapped. In this case, the non-AP MLD includes a TID-to-link mapping element in the (re)association response frame. Otherwise, the non-AP MLD indicates rejection of the proposed TID-to-link mapping by including a TID-to-link mapping element suggesting a preferred TID-to-link mapping in the (re)association response frame.

[0118] After successful multi-link (re)setup, to negotiate new TID-to-link mappings, the initiating MLD may send an individually addressed TID-to-link mapping request frame to the responding MLD that has indicated support for negotiating TID-to-link mappings.

[0119] Upon receiving an individually addressed TID-to-link mapping request frame, the responding MLD sends an individually addressed TID-to-link mapping response frame to the initiating MLD according to the following rules: The responding MLD may approve the requested TID-to-link mapping indicated in the TID-to-link mapping element in the received TID-to-link mapping request frame by sending a TID-to-link mapping response frame. Otherwise, the responding MLD may indicate rejection of the proposed TID-to-link mapping in the TID-to-link mapping response frame. The responding MLD may propose a preferred TID-to-link mapping in the TID-to-link mapping response frame by including a TID-to-link mapping element in the TID-to-link mapping response frame.

[0120] An MLD may propose a preferred TID-to-link mapping to a peer MLD by transmitting an unsolicited TID-to-link mapping response frame that contains a TID-to-link mapping element.

[0121] If a peer MLD indicates a preferred TID-to-link mapping, the MLD may take the preferred TID-to-link mapping into account when initiating a new TID-to-link mapping. Additionally, the AP MLD may take into account traffic flows associated with non-AP MLDs and the capabilities and constraints (if any) of the non-AP MLDs.

[0122] If two MLDs have negotiated TID-to-link mappings, either MLD may remove the negotiated TID-to-link mapping by sending an individually addressed TID-to-link mapping removal frame. After the removal, the MLD operates in the default mapping mode.

[0123] Once the MLD successfully negotiates the TID-to-link mapping with the peer MLD, both the MLD and the peer MLD update their uplink and / or downlink TID-to-link mapping information according to the negotiated TID-to-link mapping.

[0124] If an MLD successfully negotiates with a peer MLD an uplink and / or downlink TID-to-link mapping in which bit position i of link mapping field n in a TID-to-link mapping element is set to 0, then TID n shall not be mapped to the link associated with link ID i in the uplink and / or downlink. If an MLD successfully negotiates with a peer MLD an uplink and / or downlink TID-to-link mapping in which bit position i of link mapping field n in a TID-to-link mapping element is set to 1, then TID n shall be mapped to the link associated with link ID i in the uplink and / or downlink.

[0125] 10 shows an example of TID-to-link mapping in a multi-link communication environment. As shown, the multi-link communication environment includes an AP MLD with three associated APs and a non-AP MLD with three associated STAs.

[0126] During or after multilink setup, the non-AP MLD and the AP MLD may negotiate TID-to-link mapping. The TID-to-link mapping maps TIDs in the non-AP MLD in UL and DL to set up links between the AP MLD and the non-AP MLD. For example, as shown in FIG. 10, the TID-to-link mapping may map TIDs 0-6 to link 1 in both UL and DL, and map TID 7 to link 2 in both UL and DL. Thus, links 1 and 2 are enabled and link 3 is disabled. The negotiation of the TID-to-link mapping may be performed by exchanging association request / response frames or TID-to-link mapping request / response frames between the non-AP MLD and the AP MLD.

[0127] FIG. 11 illustrates an existing buffer status report in the presence of TID-to-link mapping in an exemplary multi-link communication environment 1100. As shown in FIG. 11, the exemplary environment 1100 may include a non-AP MLD 1110 and an AP MLD 1111. The non-AP MLD 1110 and the AP MLD 1111 may be communicatively coupled by multiple (setup) links (e.g., link 1, link 2, and link 3). The non-AP MLD 1110 may include multiple associated STAs (e.g., STA1, STA2, and STA3). The AP MLD 1111 may include multiple associated APs (e.g., AP1, AP2, and AP3). The multiple associated STAs of the non-AP MLD 1110 may each be configured to communicate with a respective one of the multiple associated APs of the AP MLD 1111 over a respective one of the multiple links communicatively coupling the non-AP MLD 1110 and the AP MLD 1111.

[0128] In the non-AP MLD 1110, there may be multiple UL and / or DL ​​traffic streams. Each traffic may be associated with a TID (e.g., TID 0, TID 1, ..., TID 7). The various traffic streams may be added to queues specified in the non-AP MLD 1110. A queue may be used to add traffic of one or more TIDs to the queue.

[0129] In one embodiment, the non-AP MLD 1110 and the AP MLD 1111 may negotiate a TID-to-link mapping. The TID-to-link negotiation may include an exchange of a TID-to-link mapping element in an association request frame and an association response frame communicated between the non-AP MLD 1110 and the AP MLD 1111. The TID-to-link mapping maps TIDs in the non-AP MLD 1110 to link setup between the non-AP MLD 1110 and the AP MLD 1111 in the uplink and / or downlink. In one embodiment, as shown in FIG. 11, after the successful negotiation of the TID-to-link mapping, TID 0 through TID 6 may be mapped to both link 1 and link 2, and TID 7 may be mapped to link 3.

[0130] The non-AP MLD 1110 may have buffered traffic associated with a TID that it sends to the AP MLD 1111. As described above with reference to FIG. 6, in solicited buffer status reporting, the AP MLD 1111 may solicit the non-AP MLD 1110 to report buffer status by sending a Buffer Status Report Polling Trigger frame (BSRP) to the AP MLD 1110. The non-AP MLD 1110 may respond by sending a QoS Null frame that includes one or more Buffer Status Reports (BSRs). In a single link environment where all of the non-AP STAs' TIDs are mapped to only one link, the non-AP STAs follow a well-defined rule that any BSR for any TID is sent on a single link between the non-AP STA and the AP. However, this is not the case in a multi-link environment where a non-AP MLD may be communicatively coupled via multiple links with an AP MLD, and in particular in a multi-link environment where the non-AP MLD and the AP MLD have negotiated a TID-to-link mapping that assigns each TID in the non-AP MLD to one or more links between the non-AP MLD and the AP MLD.

[0131] In fact, the existing IEEE 802.11 standard specification (e.g., draft P802.11be_D1.3) is silent on which of multiple links the QoS Null frame report buffer status for a given TID may be transmitted when the TID-to-link mapping is negotiated between non-AP MLD and AP MLD. For example, the existing standard specification provides that "only MSDUs or A-MSDUs with TIDs mapped to an enabled link" may be transmitted on that link. Strictly speaking, a QoS Null frame does not contain an MSDU or A-MSDU, while following the same rule for a QoS Null frame containing a TID will have a QoS Null frame transmitted only on the TID's mapped link. The existing standard specification further provides that "management and control frames may be transmitted on any enabled link". However, a QoS Null frame may not be considered a MAC management frame or a MAC control frame.

[0132] Returning to the example environment 1100, operation according to the existing standard specification may have the AP MLD 1111 sending a first Buffer Status Report Polling (BSRP) trigger frame on link 1 to the non-AP MLD 1110. In response to the first BSRP trigger frame, the non-AP MLD 1110 may send a QoS Null frame. According to the negotiated TID-to-link mapping that maps only TIDs 0-6 to link 1, and following rules similar to those that exist for MSDU / A-MSDU, the non-AP MLD 1110 may include in the QoS Null frame BSR sent for only TIDs 0-6 because the BSRP trigger frame was sent on link 1, where only TIDs 0-6 are mapped. Thus, to obtain buffer status for TID 7, the AP MLD 1111 may need to send a second BSRP trigger frame on link 3 to solicit transmission by the non-AP MLD 1110 of a BSR for TID 7. Therefore, overhead and latency may be increased for AP MLD to obtain full buffer status (for all TIDs) for non-AP MLD.

[0133] 12-15 illustrate an exemplary method of buffer status reporting in the presence of TID-to-link mapping according to an embodiment of the present disclosure. For illustrative purposes only, the exemplary method is described below in the context of an exemplary multi-link communication environment including a single non-AP MLD and a single AP MLD. As will be appreciated by those skilled in the art based on the teachings herein, the embodiments are not limited by these examples and may be readily extended to a multi-link environment including multiple non-AP MLDs and multiple AP MLDs. Furthermore, the exemplary method is described with reference to exemplary communications between a non-AP MLD and an AP MLD. These exemplary communications, such as a particular sequence of frame transmissions between a non-AP MLD and an AP MLD, are also provided for illustrative purposes only and shall not be used to limit the embodiments of the present disclosure.

[0134] FIG. 12 illustrates an example method of buffer status reporting, according to one embodiment, with respect to an example environment 1200. As shown in FIG. 12, the example environment 1200 may include a non-AP MLD 1210 and an AP MLD 1211. The non-AP MLD 1210 and the AP MLD 1211 may be communicatively coupled by a plurality of (setup) links (e.g., link 1, link 2, and link 3). The non-AP MLD 1210 may include a plurality of associated STAs (e.g., STA1, STA2, and STA3). The AP MLD 1211 may include a plurality of associated APs (e.g., AP1, AP2, and AP3). The plurality of associated STAs of the non-AP MLD 1210 may each be configured to communicate with a respective one of a plurality of associated APs of the AP MLD 1211 over a respective one of a plurality of links communicatively coupling the non-AP MLD 1210 and the AP MLD 1211.

[0135] In an exemplary embodiment, the non-AP MLD 1210 and the AP MLD 1211 may establish a multi-link setup during an association procedure. The multi-link setup configures multiple links, such as links 1-3, as "setup" links between the non-AP MLD 1210 and the AP MLD 1211. Each link may communicatively couple an associated STA of the non-AP MLD 1210 with a respective associated AP of the AP MLD 1210. In one embodiment, each link may correspond to a particular band of multiple supported frequency bands (e.g., 2.4 GHz, 5 GHz, and 6 GHz) between the non-AP MLD 1210 and the AP MLD 1211.

[0136] In an exemplary embodiment, the non-AP MLD 1210 and the AP MLD 1211 may negotiate a TID-to-link mapping. The TID-to-link negotiation may include exchanging TID-to-link mapping elements during an association procedure between the non-AP MLD 1110 and the AP MLD 1111. In one example, as shown in FIG. 12, TID 0 through TID 6 may be uplink mapped to link 1 that communicatively couples STA1 associated with the non-AP MLD 1210 and AP1 associated with the AP MLD 1211, and TID 7 may be uplink mapped to link 2 that communicatively couples STA2 associated with the non-AP MLD 1210 and AP2 associated with the AP MLD 1211. According to this exemplary TID-to-link mapping, links 1 and 2 may be considered "valid" because at least one TID is mapped to each of links 1 and 2. On the other hand, link 3 may be considered "invalid" since no TID is mapped to link 3.

[0137] Based on the TID-to-link mapping, non-AP MLD 1210 may transmit a frame carrying an MSDU or A-MSDU with any of TIDs 0 through 6 on link 1 (not shown in FIG. 12), and may transmit a frame carrying an MSDU or A-MSDU with TID 7 on link 2 (not shown in FIG. 12).

[0138] The non-AP MLD 1210 may be configured to transmit frames carrying a buffer status report (BSR) to the AP MLD 1211. The BSR frame may be carried by a trigger-based (TB) physical layer protocol data unit (PPDU) or a non-TB PDDU. Various embodiments for transmitting a BSR frame in the presence of a negotiated TID-to-link mapping are now described.

[0139] In one embodiment, the non-AP MLD 1210 may be configured to transmit BSR frames for any TID on any enabled link, independent / unrelated to the negotiated TID-to-link mapping.

[0140] In an example embodiment, the non-AP MLD 1210 may be configured to transmit a BSR frame for any TID (e.g., TID 0-TID 7) on any enabled link in response to a trigger frame transmitted from the AP MLD 1211, independent / unrelated to the negotiated TID-to-link mapping. For example, as shown in FIG. 12, the non-AP MLD 1210 may have traffic buffered on the uplink associated with TID 7 when it receives a first trigger frame 1220 on link 1 from the AP MLD 1211. The first trigger frame 1220 may be a Buffer Status Report Polling (BSRP) trigger frame or a basic trigger frame. Independent of the TID-to-link mapping that maps TID 7 to only link 2, the non-AP MLD 1210 may transmit a BSR frame 1221 including a buffer status for TID 7 on link 1 in response to the first trigger frame 1220. The BSR frame 1221 may include TID 7 and a QoS Null frame indicating queue size information for TID 7. The BSR frame 1221 may be included in a TB-PPDU.

[0141] In another exemplary embodiment, the non-AP MLD 1210 may be configured to transmit an unsolicited BSR frame for any TID to the AP MLD 1211 on any enabled link, independent / unrelated to the negotiated TID-to-link mapping. The unsolicited BSR may be transmitted without receiving a trigger frame from the AP MLD 1211 and may be transmitted after accessing the wireless medium (WM) using Extended Distributed Access Control (EDCA). For example, as shown in FIG. 12, when the non-AP MLD 1210 gets a transmission opportunity (TXOP) on link 2, it may have traffic buffered in the uplink for TID 7 and at least one other TID (e.g., any of TID 0-TID 6). Independent / unrelated to the TID-to-link mapping that maps only TID 7 to link 2, the non-AP MLD 1210 may transmit a non-TB PPDU carrying an unsolicited BSR frame 1223 for at least one other TID (other than TID 7). The unsolicited BSR frame 1223 may include one or more QoS Null frames indicating buffer status associated with at least one other TID and queue size information for at least one other TID in the non-AP MLD 1210. The non-TB PPDU may also carry an MSDU or A-MSDU for TID 7.

[0142] In another example embodiment, the non-AP MLD 1210 may be configured to transmit a BSR frame for any TID to the AP MLD 1211 on the disabled link, independent / unrelated to the negotiated TID-to-link mapping, in response to a trigger frame transmitted from the AP MLD 1211. For example, as shown in FIG. 12, the non-AP MLD 1210 may receive a second trigger frame 1224 from the AP MLD 1211 indicating one or more resource units (RUs) for uplink OFDMA random access (UORA) on the disabled link 3. The second trigger frame 1224 may be a BSRP trigger frame or a basic trigger frame. In response to the second trigger frame 1224, the non-AP MLD 1210 may transmit a BSR frame 1225 on link 3, even though the TID is not mapped to link 3 in the TID-to-link mapping. The BSR frame 1225 may include a QoS null frame indicating any TID (eg, TID 0 to TID 7) and queue size information for that TID. The BSR frame 1225 may be included in a TB-PPDU.

[0143] In another exemplary embodiment, the non-AP MLD 1210 may be configured to transmit an unsolicited BSR frame for a TID to the AP MLD 1211 according to the TID-to-link mapping. The unsolicited BSR may be transmitted without receiving a trigger frame from the AP MLD 1211 and may be transmitted after accessing the wireless medium (WM) using EDCA. For example, as shown in FIG. 12, the non-AP MLD 1210 may obtain a transmission opportunity (TXOP) on link 1. According to the TID-to-link mapping, the non-AP MLD 1210 may transmit an unsolicited BSR frame 1222 carrying an unsolicited BSR frame 1222 for any of TIDs 0-6 on link 1. The unsolicited BSR frame 1222 may include one or more QoS null frames indicating any of TIDs 0-6 and queue size information for the indicated TID. The unsolicited PPDU may also carry an MSDU or A-MSDU for TID 0 to TID 6.

[0144] FIG. 13 illustrates a further exemplary method of buffer status reporting, according to one embodiment, with respect to an exemplary environment 1300. As shown in FIG. 13, the exemplary environment 1300 may include a non-AP MLD 1310 and an AP MLD 1311. The non-AP MLD 1310 and the AP MLD 1311 may be communicatively coupled by a plurality of (setup) links (e.g., link 1, link 2, and link 3). The non-AP MLD 1310 may include a plurality of associated STAs (e.g., STA1, STA2, and STA3). The AP MLD 1311 may include a plurality of associated APs (e.g., AP1, AP2, and AP3). The plurality of associated STAs of the non-AP MLD 1310 may each be configured to communicate with a respective one of a plurality of associated APs of the AP MLD 1311 over a respective one of a plurality of links communicatively coupling the non-AP MLD 1310 and the AP MLD 1311.

[0145] As described above with reference to FIG. 12, in an exemplary embodiment, non-AP MLD 1310 and AP MLD 1311 may establish a multi-link setup and negotiate a TID-to-link mapping during the association procedure. In one example, as shown in FIG. 13, TID 0 through TID 6 may be uplink mapped to link 1 that communicatively couples STA1 and AP1, and TID 7 may be uplink mapped to link 2 that communicatively couples STA2 and AP2. According to this exemplary TID-to-link mapping, links 1 and 2 may be considered "valid" because at least one TID is mapped to each of links 1 and 2. Meanwhile, link 3 may be considered "invalid" because no TID is mapped to link 3.

[0146] Based on the TID-to-link mapping, non-AP MLD 1310 may transmit a frame carrying an MSDU or A-MSDU with any of TIDs 0 through 6 on link 1 (not shown in FIG. 13), and may transmit a frame carrying an MSDU or A-MSDU with TID 7 on link 2 (not shown in FIG. 13).

[0147] In one embodiment, the AP MLD 1311 may transmit a first trigger frame 1320 (e.g., a BSRP trigger frame, a basic trigger frame, etc.) to the non-AP MLD 1310 on the enabled link (e.g., Link 1). The non-AP MLD 1310 receiving the first trigger frame 1320 may respond with a BSR frame 1321 in a first TB PPDU on the enabled link (e.g., Link 1) indicating buffer status for any TID regardless of TID-to-link mapping. For example, the BSR frame 1321 may include one or more QoS Null frames indicating any TID from TID 0 to TID 7 and queue size information for the indicated TID.

[0148] When the AP MLD 1311 receives a BSR frame 1321 indicating one or more TIDs between TID 0 and TID 6, the AP MLD 1311 may transmit a second trigger frame 1322 (e.g., a basic trigger frame, a MU-RTS TXS trigger frame) on link 1 to allocate uplink resources to the non-AP MLD 1310 for the one or more TIDs indicated in the BSR frame 1321. In response to the second trigger frame 1322, the non-AP MLD 1310 may transmit a second TB-PPDU including one or more QoS data frames 1323 for the one or more indicated TIDs on link 1. The QoS data frames 1323 may include MSDUs or A-MSDUs for the one or more indicated TIDs. The AP MLD 1311 receiving the second TB PPDU may transmit a first acknowledgment frame 1324 on link 1 in response to the QoS data frame 1323 included in the second TB PPDU.

[0149] If the BSR frame 1321 indicates TID 7, the AP MLD 1311 may transmit a third trigger frame 1325 (e.g., a basic trigger frame, a MU-RTS TXS trigger frame) on link 2 to allocate uplink resources to the non-AP MLD 1310 for transmission of TID 7. In response to the third trigger frame 1325, the non-AP MLD 1310 may transmit a third TB PPDU including one or more QoS data frames 1326 for TID 7 on link 2. The QoS data frames 1326 may include an MSDU or A-MSDU for TID 7. The AP MLD 1311 receiving the third TB PPDU may transmit a second acknowledgment frame 1327 in response to the QoS data frame 1326 included in the third TB PPDU.

[0150] In another embodiment, the AP MLD 1311 may transmit a fourth trigger frame 1330 (e.g., a BSRP trigger frame, a basic trigger frame, etc.) on a disabled link (e.g., Link 3) to the non-AP MLD 1310. The non-AP MLD 1310 receiving the fourth trigger frame 1330 on the disabled link may respond on the disabled link with a BSR frame 1331 in the fourth TB PPDU indicating buffer status for any TID, regardless of the TID-to-link mapping. For example, the BSR frame 1331 may include one or more QoS Null frames indicating any TID from TID 0 to TID 7 and queue size information for the indicated TID. The AP MLD 1311 receiving the fourth TB PPDU may transmit a subsequent trigger frame on Link 1 and / or Link 2 to allocate UL resources to the non-AP MLD 1310 based on the indicated TIDs and their queue size information indicated in the BSR frame 1331.

[0151] FIG. 14 illustrates a further exemplary method of buffer status reporting, according to one embodiment, with respect to an exemplary environment 1400. As shown in FIG. 14, the exemplary environment 1400 may include a non-AP MLD 1410 and an AP MLD 1411. The non-AP MLD 1410 and the AP MLD 1411 may be communicatively coupled by a plurality of (setup) links (e.g., link 1, link 2, and link 3). The non-AP MLD 1410 may include a plurality of associated STAs (e.g., STA1, STA2, and STA3). The AP MLD 1411 may include a plurality of associated APs (e.g., AP1, AP2, and AP3). The plurality of associated STAs of the non-AP MLD 1410 may each be configured to communicate with a respective one of a plurality of associated APs of the AP MLD 1411 over a respective one of a plurality of links communicatively coupling the non-AP MLD 1410 and the AP MLD 1411.

[0152] As described above with reference to FIG. 12, in an exemplary embodiment, non-AP MLD 1410 and AP MLD 1411 may establish a multi-link setup and negotiate a TID-to-link mapping during the association procedure. In one example, as shown in FIG. 14, TID 0 through TID 6 may be uplink mapped to link 1 that communicatively couples STA1 and AP1, and TID 7 may be uplink mapped to link 2 that communicatively couples STA2 and AP2. According to this exemplary TID-to-link mapping, links 1 and 2 may be considered "valid" because at least one TID is mapped to each of links 1 and 2. Meanwhile, link 3 may be considered "invalid" because no TID is mapped to link 3.

[0153] Based on the TID-to-link mapping, non-AP MLD 1410 may transmit a frame carrying an MSDU or A-MSDU with any of TIDs 0 through 6 on link 1 (not shown in FIG. 14), and may transmit a frame carrying an MSDU or A-MSDU with TID 7 on link 2 (not shown in FIG. 14).

[0154] In one example, the non-AP MLD 1410 may use EDCA to transmit a BSR frame 1420 in a first non-TB PPDU indicating buffer status for any TID on an enabled link (e.g., Link 1) independent / unrelated to the TID-to-link mapping. For example, the BSR frame 1420 may include one or more QoS Null frames indicating any TID from TID 0 to TID 7 and queue size information for the indicated TID.

[0155] When the AP MLD 1411 receives a BSR frame 1420 indicating one or more TIDs between TID 0 and TID 6, the AP MLD 1411 may transmit a first trigger frame 1422 (e.g., a basic trigger frame, a MU-RTS TXS trigger frame) on link 1 to allocate uplink resources to the non-AP MLD 1410 for the one or more TIDs indicated in the BSR frame 1420. In response to the first trigger frame 1422, the non-AP MLD 1410 may transmit a first TB PPDU including one or more QoS data frames 1423 for the one or more indicated TIDs on link 1. The QoS data frame 1423 may include an MSDU or an A-MSDU for the one or more indicated TIDs. The AP MLD 1411 receiving the first TB PPDU may transmit a first acknowledgment frame 1424 in response to the QoS data frame 1423 included in the first TB PPDU.

[0156] If the BSR frame 1420 indicates TID 7, the AP MLD 1411 may transmit a second trigger frame 1425 (e.g., a basic trigger frame, a MU-RTS TXS trigger frame) on link 2 to allocate uplink resources to the non-AP MLD 1410 for transmission of TID 7. In response to the second trigger frame 1425, the non-AP MLD 1410 may transmit a second TB PPDU including one or more QoS data frames 1426 on link 2. The one or more QoS data frames may include an MSDU or A-MSDU for TID 7. The AP MLD 1411 receiving the second TB PPDU may transmit a second acknowledgment frame 1427 in response to the QoS data frame 1426 included in the second TB PPDU.

[0157] In another embodiment, the non-AP MLD 1410 may be configured to transmit a BSR frame indicating the buffer status of TIDs on enabled links other than the link to which the indicated TID is mapped. For example, as shown in FIG. 14, the non-AP MLD 1410 may transmit a BSR frame 1421 in a second non-TB PPDU indicating the buffer status of one or more of TIDs 0-6 on enabled link 2. The BSR frame 1421 may include one or more QoS null frames indicating one or more of TIDs 0-6 and queue size information for the indicated TIDs. The AP MLD 1411 receiving the second non-TB PPDU may transmit a trigger frame (not shown) on link 1 based on the TIDs and their queue size information indicated in the BSR frame 1421. In response to the trigger frame, the non-AP MLD 1410 may transmit a TB PPDU (not shown) on link 1 including one or more QoS data frames for the indicated TIDs. The one or more QoS frames may include MSDUs or A-MSDUs for the indicated TIDs. The AP MLD 1411 receiving the TB PPDU may transmit an acknowledgement frame (not shown) in response to the QoS data frame included in the TB PPDU.

[0158] FIG. 15 illustrates a further exemplary method of buffer status reporting, according to one embodiment, with respect to an exemplary environment 1500. As shown in FIG. 15, the exemplary environment 1500 may include a non-AP MLD 1510 and an AP MLD 1511. The non-AP MLD 1510 and the AP MLD 1511 may be communicatively coupled by a plurality of (setup) links (e.g., link 1, link 2, and link 3). The non-AP MLD 1510 may include a plurality of associated STAs (e.g., STA1, STA2, and STA3). The AP MLD 1511 may include a plurality of associated APs (e.g., AP1, AP2, and AP3). The plurality of associated STAs of the non-AP MLD 1510 may each be configured to communicate with a respective one of a plurality of associated APs of the AP MLD 1511 over a respective one of a plurality of links communicatively coupling the non-AP MLD 1510 and the AP MLD 1511.

[0159] As described above with reference to FIG. 12, in an exemplary embodiment, non-AP MLD 1510 and AP MLD 1511 may establish a multi-link setup and negotiate a TID-to-link mapping during the association procedure. In one example, as shown in FIG. 15, TID 0 through TID 6 may be uplink mapped to link 1 that communicatively couples STA1 and AP1, and TID 7 may be uplink mapped to link 2 that communicatively couples STA2 and AP2. According to this exemplary TID-to-link mapping, links 1 and 2 may be considered "valid" because at least one TID is mapped to each of links 1 and 2. Meanwhile, link 3 may be considered "invalid" because no TID is mapped to link 3.

[0160] Based on the TID-to-link mapping, the non-AP MLD 1510 may transmit a frame carrying an MSDU or an A-MSDU with any of TIDs 0 through 6 on link 1 (not shown in FIG. 15), and may transmit a frame carrying an MSDU or an A-MSDU with TID 7 on link 2 (not shown in FIG. 15).

[0161] In one example, the non-AP MLD 1510 may be configured to transmit an unsolicited BSR frame on an enabled link using EDCA to indicate the buffer status of the TIDs according to the TID-to-link mapping. For example, as shown in FIG. 15, the non-AP MLD 510 may transmit a first non-TB PPDU on link 1 including an unsolicited BSR 1520 indicating the buffer status of any TID (i.e., TID 0-TID 6) mapped to link 1. The BSR frame 1520 may include one or more QoS null frames indicating any TID from TID 0-TID 6 and queue size information for the indicated TID.

[0162] When the AP MLD 1511 receives the BSR frame 1520, the AP MLD 1511 may transmit a first trigger frame 1521 (e.g., a basic trigger frame, a MU-RTS TXS trigger frame) on link 1 to allocate uplink resources to the non-AP MLD 1510 for one or more TIDs indicated in the BSR frame 1520. In response to the first trigger frame 1521, the non-AP MLD 1510 may transmit a first TB PPDU including one or more QoS data frames 1522 for the one or more indicated TIDs on link 1. The QoS data frames may include MSDUs or A-MSDUs for the one or more indicated TIDs. The AP MLD 1511 receiving the first TB PPDU may transmit a first acknowledgment frame 1523 in response to the QoS data frame 1522 included in the first TB PPDU.

[0163] In another embodiment, the AP MLD 1411 may send a second trigger frame 1524 (e.g., a BSRP trigger frame) on link 2 to solicit the non-AP MLD 1510 for a buffer status at the non-AP MLD 1510. In response to the second trigger frame 1524, the non-AP MLD 1510 may send a second TB PPDU including a BSR frame 1525 indicating the buffer status for TID 7 (e.g., a QoS null frame indicating TID 7 and queue size information for TID 7) according to the TID-to-link mapping on link 2. The AP MLD 1511 receiving the BSR frame 1525 may send a third trigger frame 1526 (e.g., a basic trigger frame, a MU-RTS TXS trigger frame) on link 2 to allocate uplink resources for TID 7 to the non-AP MLD 1510. In response to the third trigger frame 1526, the non-AP MLD 1510 may transmit on link 2 a third TB PPDU including one or more QoS data frames 1527 for TID 7. The one or more QoS data frames 1527 may include an MSDU or an A-MSDU for TID 7. The AP MLD 1511 receiving the third TB PPDU may transmit a second acknowledgment frame 1528 in response to the QoS data frame 1527 included in the third TB PPDU.

[0164] FIG. 16 illustrates an example process 1600 for transmitting a buffer status according to an embodiment of the present disclosure. The example process 1600 may be implemented in an example environment including an AP MLD and a non-AP MLD. The non-AP MLD and the AP MLD may be communicatively coupled by a plurality of links and may be associated with a TID-to-link mapping. The TID-to-link mapping may include a first mapping of a first TID in an uplink to a link of a first set of the plurality of links and a second mapping of a second TID in an uplink to a link of a second set of the plurality of links. In an embodiment, the TID-to-link mapping is based on a TID-to-link mapping element exchanged in an association request frame and an association response frame between the non-AP MLD and the AP MLD, or a default mapping mode in which the TID is mapped to all of the plurality of links for both the downlink and the uplink.

[0165] The example process 1600 may be performed by a non-AP MLD.

[0166] As shown in FIG. 16, process 1600 may include, at step 1610, transmitting a frame of a first TID in accordance with the TID-to-link mapping on a first link of the first set of links.

[0167] In one embodiment, the frames of the first TID include frames carrying one or more MSDUs or A-MSDUs for the first TID.

[0168] In step 1620, the process 1600 may include determining a buffer status for the first TID.

[0169] In step 1630, the process 1600 may include transmitting a BSR frame indicating a buffer status for the first TID on any link of the multiple links, independent / unrelated to the TID-to-link mapping.

[0170] In one embodiment, the link over which the BSR frame is transmitted is an enabled link, i.e., a link that has at least one TID mapped to it according to the TID-to-link mapping.

[0171] In one embodiment, the link on which the BSR frame is transmitted belongs to a first set of links of the plurality of links.

[0172] In one embodiment, the link on which the BSR frame is transmitted belongs to a second set of links of the plurality of links.

[0173] In one embodiment, the link over which the BSR frame is transmitted is a link over which the first TID is not mapped in the TID-to-link mapping.

[0174] In one embodiment, the link on which the BSR frame is transmitted is a disabled link, ie, a link that does not have a TID mapped to it according to the TID-to-link mapping.

[0175] In one embodiment, the BSR frame includes a QoS Null frame indicating the first TID and queue size information for the first TID.

[0176] In one embodiment, the BSR frame comprises a QoS Null frame that includes a QoS Control field or a QoS Null frame that includes a QoS Control field and a BSR Control subfield.

[0177] In one embodiment, the QoS control field includes at least one of a TID subfield, where the TID subfield identifies the traffic class (TC) or traffic stream (TS) for which a transmission opportunity (TXOP) is being requested, and a queue size subfield, where the queue size subfield indicates the total size in octets of MSDUs or A-MSDUs having a TID equal to the value of the TID subfield and buffered in the non-AP MLD.

[0178] In one embodiment, the BSR Control subfield includes at least one of an Access Category Index (ACI) Bitmap subfield, a Delta TID subfield, an ACI High subfield, a Scaling Factor subfield, a Queue Size High subfield, and a Queue Size Total subfield. The ACI Bitmap subfield indicates at least one Access Category (AC) for which buffer status is reported in the BSR frame. The Delta TID subfield indicates the number of TIDs for which buffer status is reported in the BSR frame. The ACI High subfield indicates the ACI of at least one AC for which buffer status is indicated in the Queue Size High subfield. The Scaling Factor indicates the size in octets of the Queue Size High and Queue Size Total subfields in units (SF). The Queue Size High subfield indicates the amount of buffered traffic in SF units for the AC identified by the ACI High subfield. The Queue Size Total subfield indicates the amount of buffered traffic in SF units for the at least one AC identified by the ACI Bitmap subfield.

[0179] In one embodiment, transmitting the BSR frame in Step 1630 includes transmitting the BSR frame in a TB PPDU or a non-TB PPDU.

[0180] In one embodiment, the sending of the BSR frame in step 1630 is in response to a trigger frame received from the AP MLD. The trigger frame may include a BSRP trigger frame or a basic trigger frame. The BSR frame may be sent in a TB PPDU.

[0181] In one embodiment, transmitting the BSR frame in step 1630 includes performing an ECDA-based transmission. The EDCA-based transmission may include transmitting a non-TB PPDU.

[0182] In one embodiment, process 1600 may optionally include steps 1640 and 1650.

[0183] In step 1640, the process 1600 may include the non-AP MLD receiving a trigger frame from the AP MLD in response to the BSR frame. The trigger frame may be received on a link to which the first TID is mapped in the TID-to-link mapping. The trigger frame may be a basic trigger frame or a MU-RTS TXS trigger frame.

[0184] In step 1650, the non-AP MLD that receives the trigger frame in step 1640 may transmit a frame carrying an MSDU or an A-MSDU for the first TID on the link on which the trigger frame is received.

[0185] FIG. 17 illustrates an example process 1700 for receiving a buffer status according to an embodiment of the present disclosure. The example process 1700 may be implemented in an example environment including an AP MLD and a non-AP MLD. The non-AP MLD and the AP MLD may be communicatively coupled by a plurality of links and may be associated with a TID-to-link mapping. The TID-to-link mapping may include a first mapping of a first TID in an uplink to a first set of links of the plurality of links and a second mapping of a second TID in an uplink to a second set of links of the plurality of links. In an embodiment, the TID-to-link mapping is based on a TID-to-link mapping element exchanged in association request and association response frames between the non-AP MLD and the AP MLD, or a default mapping mode in which the TID is mapped to all of the plurality of links for both the downlink and the uplink.

[0186] The example process 1700 may be performed by an AP MLD.

[0187] 17, process 1700 may include receiving a frame for a first TID from the non-AP MLD on a first link of a first set of links according to the TID-to-link mapping, at step 1710. The first frame may carry a MAC Service Data Unit (MSDU) or an aggregated MSDU (A-MSDU) for the first TID.

[0188] In step 1720, the process 1700 may include receiving a buffer status report (BSR) frame for the first TID on any link of the multiple links, independently / without regard to the TID-to-link mapping.

[0189] In one embodiment, the link on which the BSR frame is received is an enabled link, i.e., a link that has at least one TID mapped to it according to the TID-to-link mapping.

[0190] In one embodiment, the link on which the BSR frame is received belongs to a first set of links of the plurality of links.

[0191] In one embodiment, the link on which the BSR frame is received belongs to a second set of links of the plurality of links.

[0192] In one embodiment, the link on which the BSR frame is received is a link on which the first TID is not mapped in the TID-to-link mapping.

[0193] In one embodiment, the link on which the BSR frame is received is a disabled link, ie, a link that does not have a TID mapped to it according to the TID-to-link mapping.

[0194] In one embodiment, the BSR frame includes a QoS Null frame indicating the first TID and queue size information for the first TID.

[0195] In one embodiment, the BSR frame comprises a QoS Null frame that includes a QoS Control field or a QoS Null frame that includes a QoS Control field and a BSR Control subfield.

[0196] In one embodiment, the QoS control field includes at least one of a TID subfield, where the TID subfield identifies the traffic class (TC) or traffic stream (TS) for which a transmission opportunity (TXOP) is being requested, and a queue size subfield, where the queue size subfield indicates the total size in octets of MSDUs or A-MSDUs having a TID equal to the value of the TID subfield and buffered in the non-AP MLD.

[0197] In one embodiment, the BSR Control subfield includes at least one of an Access Category Index (ACI) Bitmap subfield, a Delta TID subfield, an ACI High subfield, a Scaling Factor subfield, a Queue Size High subfield, and a Queue Size Total subfield. The ACI Bitmap subfield indicates at least one Access Category (AC) for which buffer status is reported in the BSR frame. The Delta TID subfield indicates the number of TIDs for which buffer status is reported in the BSR frame. The ACI High subfield indicates the ACI of at least one AC for which buffer status is indicated in the Queue Size High subfield. The Scaling Factor indicates the size in octets of the Queue Size High and Queue Size Total subfields in units (SF). The Queue Size High subfield indicates the amount of buffered traffic in SF units for the AC identified by the ACI High subfield. The Queue Size Total subfield indicates the amount of buffered traffic in SF units for the at least one AC identified by the ACI Bitmap subfield.

[0198] In one embodiment, receiving the BSR frame in Step 1720 includes receiving the BSR frame in a TB PPDU or a non-TB PPDU.

[0199] In one embodiment, receiving the BSR frame is in response to a trigger frame transmitted by the AP MLD. The trigger frame may include a BSRP trigger frame or a basic trigger frame.

[0200] In one embodiment, process 1700 may optionally include steps 1730 and 1740.

[0201] In step 1730, the process 1700 may include transmitting a trigger frame in response to the BSR on a link to which the first TID is mapped in the TID-to-link mapping. The link may be any link in the first set of links. The trigger frame allocates uplink resources to the AP MLD for the first TID. The trigger frame may include a basic trigger frame or a MU-RTS TXS trigger frame.

[0202] In step 1740, process 1700 may include receiving one or more MSDUs or A-MSDUs for the first TID on the link over which the trigger frame is transmitted.

[0203] In an example embodiment, the non-AP MLD may send frames to the AP MLD based on a TID-to-link mapping, which indicates a mapping of a first TID to a link of a first set and a mapping of a second TID to a link of a second set. The non-AP MLD may send a Buffer Status Report (BSR) frame to the AP MLD indicating a buffer status for the first TID on any link, regardless of the TID-to-link mapping.

[0204] In an exemplary embodiment, the non-AP MLD and the AP MLD may set up multiple links for multi-link operation and negotiate a TID-to-link mapping during an association procedure between the non-AP MLD and the AP MLD, where the TID-to-link mapping may include a first mapping of a first TID in an uplink to a link of a first set of the multiple links and a second mapping of a second TID in an uplink to a link of a second set of the multiple links. The non-AP MLD may send a frame carrying an MSDU or an A-MSDU for the first TID on the first link of the first set of links to the AP MLD. The non-AP MLD may determine a buffer status of the first TID. The non-AP MLD may send a BSR frame indicating a buffer status of the first TID (e.g., a QoS Null frame indicating the first TID and including queue size information for the first TID) on any link of the multiple links, independent of the TID-to-link mapping.

[0205] In an example embodiment, the transmission of a BSR frame on any link of the multiple links, regardless of the negotiated TID-to-link mapping, may reduce the latency of the AP MLD to obtain the buffer status of the non-AP MLD. Furthermore, the signaling overhead may be reduced by the AP MLD not sending a trigger frame to poll buffer status report of each enabled link. The AP MLD may obtain an accurate buffer status of the non-AP MLD in time by receiving a PPDU including a buffer status report frame.

[0206] In an exemplary embodiment, the BSR frame may be transmitted based on different rules depending on which PPDU carries the BSR frame when the TID-to-link mapping is negotiated. In an exemplary embodiment, a trigger-based (TB) PPDU containing a BSR frame (e.g., a QoS Null frame) indicating the buffer status of a TID may be transmitted on any of the multiple links regardless of the TID-to-link mapping, and the TB PPDU is transmitted by a non-AP MLD in response to a trigger frame (e.g., a Buffer Status Report Polling (BSRP) trigger frame, a basic trigger frame, etc.) transmitted by an AP MLD. In another exemplary embodiment, a non-TB PPDU containing a BSR frame (e.g., a QoS Null frame) indicating the buffer status of a TID may be transmitted on a link to which the TID is mapped according to the TID-to-link mapping.

[0207] In an exemplary embodiment, the transmission of the BSR frame in the non-TB PPDU may follow the TID-to-link mapping rules, and the non-AP MLD may have the same implementation for the transmission of a frame with a TID using EDCA channel access when the TID-to-link mapping is negotiated. In an exemplary embodiment, the transmission of the BSR frame in the TB PPDU for any TID on any link of multiple links may provide low latency and more accurate BSR to the AP MLD by the AP MLD sending a trigger frame to the non-AP MLD when the AP MLD needs to obtain BSR information from the non-AP MLD, regardless of the TID-to-link mapping.

[0208] FIG. 18 illustrates an example process 1800 according to one embodiment. The example process 1800 may be implemented in an example environment including an AP MLD and a non-AP MLD. The non-AP MLD and the AP MLD may be communicatively coupled by a plurality of links and may be associated with a TID-to-link mapping. The TID-to-link mapping may include a mapping of a TID in an uplink and / or a downlink to a link of a first set of the plurality of links. The example process 1800 may be implemented by the non-AP MLD.

[0209] 18, process 1800 may begin at optional step 1802, which includes transmitting to the AP MLD a frame for a TID on a first link of a first set of links to which the TID is mapped in a TID-to-link mapping. In one embodiment, the frame for the TID includes an MSDU or A-MSDU for the TID.

[0210] In step 1804, the process 1800 includes receiving a trigger frame on the second link from the AP MLD, where the TID is not mapped in the TID-to-link mapping. In one embodiment, the trigger frame includes a BSRP trigger frame or a basic trigger frame.

[0211] In step 1806, the process 1800 includes transmitting a QoS Null frame to the AP MLD in response to the trigger frame, the QoS Null frame including a TID on the second link. In one embodiment, the second link is an enabled link with at least one TID mapped according to a TID-to-link mapping. In another embodiment, the second link is a disabled link with no TID mapped according to a TID-to-link mapping. In one embodiment, the QoS Null frame includes a BSR for the TID. In another embodiment, the QoS Null frame further includes a BSR for another TID mapped to the second link.

[0212] In one embodiment, the QoS Null frame includes a QoS Control field that includes a BSR for a TID. In one embodiment, the QoS Control field includes at least one of a TID subfield that identifies a Traffic Class (TC) or Traffic Stream (TS) for which a Transmission Opportunity (TXOP) is requested, and a Queue Size subfield that indicates the total size in octets of MSDUs and A-MSDUs that have a TID equal to the value of the TID subfield and are buffered in the non-AP MLD. In another embodiment, the QoS Null frame includes a BSR Control subfield that includes a BSR for a TID.

[0213] In one embodiment, process 1800 may further include, prior to step 1802, receiving an association frame from the AP MLD that includes a TID-to-link mapping that maps the TIDs to the first set of links.

[0214] In one embodiment, process 1800 may further include receiving a trigger frame on the first link from the AP MLD in response to the QoS Null frame, where the trigger frame allocates uplink resources on the first link to the non-AP MLD for the TID, and transmitting a frame including a QoS data frame for the TID to the AP MLD in response to the trigger frame.

[0215] FIG. 19 illustrates an example process 1900 according to one embodiment. The example process 1900 may be implemented in an example environment including an AP MLD and a non-AP MLD. The non-AP MLD and the AP MLD may be communicatively coupled by a plurality of links and may be associated with a TID-to-link mapping. The TID-to-link mapping may include mapping of TIDs in the uplink and / or downlink to links of a first set of the plurality of links. The example process 1900 may be implemented by the AP MLD.

[0216] 19, process 1900 may begin at optional step 1902, which includes receiving a frame for a TID (to which the TID is mapped in a TID-to-link mapping) from a non-AP MLD on a first link of a set of links. In one embodiment, the frame for the TID includes an MSDU or A-MSDU for the TID.

[0217] In step 1904, the process 1900 includes transmitting a trigger frame on the second link, where the TID is not mapped to a TID-to-link mapping, to the non-AP MLD. In one embodiment, the trigger frame includes a BSRP trigger frame or a basic trigger frame.

[0218] In step 1906, the process 1900 includes receiving, from the non-AP MLD in response to the trigger frame, a QoS Null frame including a TID on the second link. In one embodiment, the second link is an enabled link with at least one TID mapped according to a TID-to-link mapping. In another embodiment, the second link is a disabled link with no TID mapped according to a TID-to-link mapping. In one embodiment, the QoS Null frame includes a BSR for the TID. In another embodiment, the QoS Null frame further includes a BSR for another TID mapped to the second link.

[0219] In one embodiment, the QoS Null frame includes a QoS Control field that includes a BSR for the TID. In one embodiment, the QoS Control field includes at least one of a TID subfield that identifies the TC or TS for which the TXOP is requested, a Queue Size subfield that indicates the total size in octets of the MSDU, and an A-MSDU with a TID equal to the value of the TID subfield that is buffered in the non-AP MLD. In another embodiment, the QoS Null frame includes a BSR Control subfield that includes a BSR for the TID.

[0220] In one embodiment, the process 1800 may further include, prior to step 1902, sending to the non-AP MLD an association frame including a TID-to-link mapping that maps the TIDs to the first set of links.

[0221] In one embodiment, process 1900 may further include transmitting a trigger frame on the first link to the non-AP MLD in response to the QoS Null frame, the trigger frame allocating uplink resources on the first link to the non-AP MLD for the TID, and receiving a frame including a QoS data frame for the TID from the non-AP MLD in response to the trigger frame.

[0222] In an exemplary embodiment, the non-AP MLD may receive a trigger frame from the AP MLD on a first link of the multiple links between the non-AP MLD and the AP MLD. In response to the trigger frame, the non-AP MLD may transmit a QoS Null frame including the TID to the AP MLD on a second link of the multiple links, regardless of whether the TID is mapped to the second link in the TID-to-link mapping. In one embodiment, the TID is not mapped to the second link in the TID-to-link mapping. The TID may or may not be mapped to the first link in the TID-to-link mapping. In another embodiment, the TID is mapped to the second link in the TID-to-link mapping. The TID may or may not be mapped to the first link in the TID-to-link mapping.

[0223] In another exemplary embodiment, the AP MLD may transmit a trigger frame on a first link of the plurality of links between the AP MLD and the non-AP MLD to the non-AP MLD. In response to the trigger frame, the AP MLD may receive a QoS Null frame including the TID on a second link of the plurality of links from the non-AP MLD, regardless of whether the TID is mapped to the second link in the TID-to-link mapping. In one embodiment, the TID is not mapped to the second link in the TID-to-link mapping. The TID may or may not be mapped to the first link in the TID-to-link mapping. In another embodiment, the TID is mapped to the second link in the TID-to-link mapping. The TID may or may not be mapped to the first link in the TID-to-link mapping.

Claims

1. 1. A method comprising: receiving, by a non-access point (non-AP) multi-link device (MLD) from an access point (AP) MLD, an association frame including a traffic identifier (TID)-to-link mapping that maps a TID to a set of links among a plurality of links between the non-AP MLD and the AP MLD; transmitting, by the non-AP MLD, to the AP MLD, a frame including a Medium Access Control (MAC) Service Data Unit (MSDU) or an Aggregate MSDU (A-MSDU) corresponding to the TID on a first link of the set of links; receiving, by the non-AP MLD, a Buffer Status Report Polling (BSRP) trigger frame from the AP MLD on a second link of the plurality of links that does not belong to the set of links to which the TID is mapped; transmitting, by the non-AP MLD to the AP MLD in response to the BSRP trigger frame, a Quality of Service (QoS) Null frame including a Buffer Status Report (BSR) for the TID on the second link.

2. 1. A method comprising: Transmitting a frame of a traffic identifier (TID) on a first link to an access point (AP) MLD by a non-access point (non-AP) multi-link device (MLD), the traffic identifier (TID) being mapped to the first link; receiving, by the non-AP MLD, a trigger frame on a second link from the AP MLD to which the TID is not mapped; transmitting, by the non-AP MLD in response to the trigger frame, a Quality of Service (QoS) Null frame including the TID on the second link to the AP MLD.

3. 3. The method of claim 2, further comprising receiving, by the non-AP MLD from the AP MLD, an association frame including a TID-to-link mapping that maps the TID to the first link.

4. The method according to any one of claims 2 to 3, wherein the trigger frame comprises a Buffer Status Report Polling (BSRP) trigger frame or a basic trigger frame.

5. The method of any one of claims 2 to 4, wherein the frame of the TID comprises a Medium Access Control (MAC) Service Data Unit (MSDU) or an Aggregated MSDU (A-MSDU) for the TID.

6. The method according to any one of claims 3 to 5, wherein the second link is an enabled link to which at least one TID is mapped according to the TID-to-link mapping.

7. The method according to any one of claims 3 to 5, wherein the second link is a disabled link to which a TID is not mapped according to the TID-to-link mapping.

8. The method of any one of claims 2 to 7, wherein the QoS Null frame includes a Buffer Status Report (BSR) for the TID.

9. 9. The method of claim 8, wherein the QoS Null frame includes a BSR for another TID mapped to the second link.

10. The method according to any one of claims 8 to 9, wherein the QoS Null frame includes a QoS Control field containing the BSR for the TID.

11. The QoS control field is a TID subfield which identifies the traffic class (TC) or traffic stream (TS) for which a transmission opportunity (TXOP) is requested; and a queue size subfield indicating a total size in octets of MAC service data units (MSDUs) and aggregated MSDUs (A-MSDUs), having a TID equal to the value of the TID subfield, and buffered at the non-AP MLD.

12. The method according to any one of claims 8 to 9, wherein the QoS Null frame includes a BSR Control subfield containing the BSR for the TID.

13. receiving, by the non-AP MLD, a trigger frame on the first link from the AP MLD in response to the QoS Null frame, the trigger frame allocating uplink resources on the first link to the non-AP MLD for the TID; A method according to any one of claims 2 to 12, comprising: transmitting, by the non-AP MLD in response to the trigger frame, a frame including a QoS data frame for the TID to the AP MLD.

14. A non-access point (non-AP) multi-link device (MLD), one or more processors; and a memory storing instructions that, when executed by said one or more processors, cause said non-AP MLD to perform a method according to any one of claims 1 to 13.

15. A non-transitory computer readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to perform the method of any one of claims 1 to 13.

16. 1. A method comprising: transmitting, by an access point (AP) multi-link device (MLD), to a non-access point (non-AP) MLD, an association frame including a traffic identifier (TID)-to-link mapping that maps a TID to a set of links among a plurality of links between the non-AP MLD and the AP MLD; receiving, by the AP MLD, from the non-AP MLD, a frame including a Medium Access Control (MAC) Service Data Unit (MSDU) or an Aggregate MSDU (A-MSDU) corresponding to the TID on a first link of the set of links; sending, by the AP MLD, to the non-AP MLD, a Buffer Status Report Polling (BSRP) trigger frame on a second link of the plurality of links that does not belong to the set of links to which the TID is mapped; receiving, by the AP MLD, a Quality of Service (QoS) Null frame including a Buffer Status Report (BSR) for the TID on the second link from the non-AP MLD in response to the BSRP trigger frame.

17. 1. A method comprising: receiving, by an access point (AP) multi-link device (MLD), from a non-access point (non-AP) MLD, a frame of a traffic identifier (TID) on a first link to which the TID is mapped; transmitting, by the AP MLD, to the non-AP MLD, a trigger frame on a second link to which the TID is not mapped; receiving, by the AP MLD, a Quality of Service (QoS) Null frame including the TID on the second link from the non-AP MLD in response to the trigger frame.

18. 18. The method of claim 17, further comprising: transmitting, by the AP MLD to the non-AP MLD, an association frame including a TID-to-link mapping that maps the TID to the first link.

19. The method according to any one of claims 17 to 18, wherein the trigger frame comprises a Buffer Status Report Polling (BSRP) trigger frame or a basic trigger frame.

20. The method of any one of claims 17 to 19, wherein the frame of the TID comprises a Medium Access Control (MAC) Service Data Unit (MSDU) or an Aggregated MSDU (A-MSDU) for the TID.

21. The method according to any one of claims 18 to 20, wherein the second link is an enabled link to which at least one TID is mapped according to the TID-to-link mapping.

22. The method according to any one of claims 18 to 20, wherein the second link is a disabled link to which a TID is not mapped according to the TID-to-link mapping.

23. The method of any one of claims 17 to 22, wherein the QoS Null frame includes a Buffer Status Report (BSR) for the TID.

24. 24. The method of claim 23, wherein the QoS Null frame includes a BSR for another TID mapped to the second link.

25. The method according to any one of claims 23 to 24, wherein the QoS Null frame includes a QoS Control field containing the BSR for the TID.

26. The QoS control field is a TID subfield which identifies the traffic class (TC) or traffic stream (TS) for which a transmission opportunity (TXOP) is requested; and a Queue Size subfield indicating a total size in octets of MAC Service Data Units (MSDUs) and Aggregated MSDUs (A-MSDUs), having a TID equal to the value of the TID subfield, and buffered at the non-AP MLD.

27. The method according to any one of claims 23 to 24, wherein the QoS Null frame includes a BSR Control subfield containing the BSR for the TID.

28. by the AP MLD to the non-AP MLD in response to the QoS Null frame, transmitting a trigger frame on the first link, the trigger frame allocating uplink resources on the first link to the non-AP MLD for the TID; A method according to any one of claims 17 to 27, comprising receiving, by the AP MLD, a frame from the non-AP MLD in response to the trigger frame, the frame including a QoS data frame for the TID.

29. An access point (AP) multi-link device (MLD), one or more processors; and a memory storing instructions that, when executed by said one or more processors, cause said AP MLD to perform a method according to any one of claims 16 to 28.

30. A non-transitory computer readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to perform the method of any one of claims 16 to 28.

31. 1. A method comprising: receiving, by a non-access point (non-AP) multi-link device (MLD), from an access point (AP) MLD, a trigger frame on a first link of a plurality of links between the non-AP MLD and the AP MLD; and transmitting, by the non-AP MLD in response to the trigger frame, to the AP MLD a Quality of Service (QoS) Null frame including a traffic identifier (TID) on a second link of the plurality of links, regardless of whether the TID is mapped to the second link in a TID-to-link mapping.

32. 32. The method of claim 31, wherein the TID is not mapped to the second link in the TID-to-link mapping.

33. 32. The method of claim 31, wherein the TID is mapped to the second link in the TID-to-link mapping.

34. The method of any one of claims 31 to 33, wherein the TID is mapped to the first link in the TID-to-link mapping.

35. The method of any one of claims 31 to 33, wherein the TID is not mapped to the first link in the TID-to-link mapping.

36. 1. A method comprising: transmitting, by an access point (AP) multi-link device (MLD) to a non-access point (non-AP) MLD, a trigger frame on a first link of a plurality of links between the AP MLD and the non-AP MLD; receiving, by the AP MLD in response to the trigger frame, a quality of service (QoS) null frame at the non-AP MLD including a traffic identifier (TID) on a second link of the plurality of links, regardless of whether the TID is mapped to the second link in a TID-to-link mapping.

37. 37. The method of claim 36, wherein the TID is not mapped to the second link in the TID-to-link mapping.

38. 37. The method of claim 36, wherein the TID is mapped to the second link in the TID-to-link mapping.

39. The method of any one of claims 36 to 38, wherein the TID is mapped to the first link in the TID-to-link mapping.

40. The method of any one of claims 36 to 38, wherein the TID is not mapped to the first link in the TID-to-link mapping.

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