Buffer status report frame transmission in multi-link communication environment

Abstract

A non-access point (non-AP) multilink device (MLD) transmits a frame for a traffic identifier (TID) to an access point (AP) MLD on a first link to which the TID is mapped in a TID-to-link mapping. The non-AP MLD receives a trigger frame from the AP MLD on a second link to which 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 to the AP MLD on the second link.

Description

[0001] This application is a divisional application of the application filed on January 27, 2023, with Chinese national application number 2023800190639 and invention name “Buffer status report frame transmission in a multi-link communication environment”.

[0002] Cross-reference to related applications

[0003] This application claims the benefit of U.S. Provisional Application No. 63 / 304,031, filed January 28, 2022, which is incorporated herein by reference in its entirety. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Examples of several of the various embodiments of the present disclosure are described herein with reference to the accompanying drawings.

[0005] Figure 1 An example wireless communication network is shown in which embodiments of the present disclosure may be implemented.

[0006] Figure 2 is a block diagram illustrating an example implementation of a station (STA) and an access point (AP).

[0007] Figure 3 An example of a medium access control (MAC) frame format is shown.

[0008] Figure 4 An example of a Quality of Service (QoS) null frame indicating buffer status information is shown.

[0009] Figure 5 An example format of a physical layer (PHY) protocol data unit (PPDU) is shown.

[0010] Figure 6 An example is shown including buffer status reporting by STAs, scheduling by the AP of uplink multi-user (MU) transmissions, and transmission of the scheduled uplink transmissions by STAs.

[0011] Figure 7 An example reference model of a multi-link device (MLD) is shown.

[0012] Figure 8 An example of an AP MLD and associated non-AP MLDs is shown.

[0013] Figure 9 An example of multi-link setup between AP MLD and non-AP MLD is shown.

[0014] Figure 10 An example of traffic identifier (TID) to link mapping in a multi-link communication environment is shown.

[0015] Figure 11 Existing buffer status reporting is shown in the presence of TID-to-link mapping in an example multi-link communication environment.

[0016] Figure 12-15 An example method of buffer status reporting in the presence of TID-to-link mapping according to an embodiment of the present disclosure is shown.

[0017] Figure 16 An example process for transmitting buffer status according to an embodiment of the present disclosure is shown.

[0018] Figure 17 An example process for receiving buffer status according to an embodiment of the present disclosure is shown.

[0019] Figure 18 An example process according to an embodiment is shown.

[0020] Figure 19 An example process according to an embodiment is shown. DETAILED DESCRIPTION

[0021] In the present disclosure, various embodiments are presented in the form of examples of how the disclosed technology can be implemented and / or how the disclosed technology can be practiced in environments and scenarios. It will be apparent to those skilled in the relevant art that various changes in form and detail can be made therein without departing from the scope. After reading this specification, it will be apparent to those skilled in the relevant art how to implement alternative embodiments. The embodiments of the present invention shall not be limited by any described exemplary embodiments. The embodiments of the present disclosure will be described with reference to the accompanying drawings. Limitations, features and / or elements from the disclosed example embodiments can be combined to create additional embodiments within the scope of the present disclosure. Any figures that highlight functionality and advantages are provided for illustrative purposes only. The disclosed architecture is flexible and configurable enough that it can be utilized in a manner different from that shown. For example, the actions listed in any flow chart can be reordered or only optionally used in certain embodiments.

[0022] The embodiments can be configured to operate as desired. When certain criteria are met, the disclosed mechanisms can be implemented, for example, in a station, access point, radio environment, network, combinations thereof, and the like. Example criteria can be based, at least in part, on, for example, wireless device or network node configuration, traffic load, initial system setup, packet size, traffic characteristics, combinations thereof, and the like. When one or more criteria are met, various example embodiments can be applied. Thus, example embodiments that selectively implement the disclosed protocol can be implemented.

[0023] In this disclosure, "a" and "an" and similar phrases will be interpreted as "at least one" and "one or more". Similarly, any term ending with the suffix "(s)" will be interpreted as "at least one" and "one or more". In this disclosure, the term "may" is interpreted as "may, for example". In other words, the term "may" indicates that the phrase following the term "may" is an example of one suitable possibility among multiple suitable possibilities that may or may not be used for one or more embodiments in various embodiments. As used herein, the terms "including" and "consisting of" list one or more components of the element being described. The terms "including" and "comprising" are interchangeable and do not exclude that unlisted components are included in the element being described. In contrast, "consisting of" provides a complete enumeration of one or more components of the element being described. As used herein, the term "based on" can be interpreted as "based at least in part on" rather than, for example, "based only on". As used herein, the term "and / or" represents any possible combination of the listed elements. For example, "A, B and / or C" can mean A; B; C; A and B; A and C; B and C; or A, B and C.

[0024] If A and B are sets, and every element of A is also an element of B, then A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, the 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 one of multiple 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 to at least") indicates that the phrase following the phrase "in response to" is an example of one of multiple suitable possibilities that may or may not be used in one or more different embodiments. The phrase "depends on" (or equivalently, "depends at least on") indicates that the phrase following the phrase "depends on" is an example of one of multiple suitable possibilities that may or may not be used in one or more different embodiments. The phrase "employing / using" (or equivalently, "at least employing / using") indicates that the phrase following the phrase "employing / using" is an example of one of multiple suitable possibilities that may or may not be used in one or more different embodiments.

[0025] The term "configured" can refer to the capabilities of a device, whether the device is in an operational or non-operational state. "Configured" can also refer to specific settings in a device that affect 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. can be "configured" within a device to provide specific characteristics to the device, whether the device is in an operational or non-operational state. Terms such as "a control message induced in a device" can mean that the control message has parameters that can be used to configure specific characteristics in the device or parameters that can be used to implement certain actions in the device, whether the device is in an operational or non-operational state.

[0026] In the present disclosure, a parameter (or equivalently referred to as a field or information element: IE) may include one or more information objects, and an information object may include one or more other objects. For example, if parameter (IE) N includes parameter (IE) M, and parameter (IE) M includes parameter (IE) K, and parameter (IE) K includes parameter (information element) J. Then, for example, N includes K, and N includes J. In an example embodiment, when one or more messages / frames include multiple parameters, this means that the parameters in the multiple parameters are in at least one of the one or more messages / frames, but not necessarily in every one of the one or more messages / frames.

[0027] Many of the features presented are described as being optional, either by using the word "may" or by using parentheses. For the sake of brevity and readability, this disclosure does not explicitly recite every permutation that can be obtained by selecting from the set of optional features. This disclosure should be interpreted as explicitly disclosing all such permutations. For example, a system described as having three optional features can be embodied in seven different ways, namely, having only one of the three possible features, having any two of the three possible features, or having three of the three possible features.

[0028] Many elements described in the disclosed embodiments can be implemented as modules. Modules are defined here as elements that perform defined functions and have defined interfaces to other elements. The modules described in this disclosure can be implemented with hardware, software, firmware, wetware (e.g., hardware with biological elements) or a combination thereof in conjunction with hardware, all of which can be equivalent in behavior. For example, a module can be implemented as a software routine written in a computer language that is configured to be executed by a hardware machine (such as C, C++, Fortran, Java, Basic, Matlab, etc.) or a modeling / simulation program (such as Simulink, Stateflow, GNU Octave, or LabVIEW MathScript). It is possible to implement a module 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, and C++. FPGAs, ASICs, and CPLDs are often programmed using a hardware description language (HDL), such as VHSIC Hardware Description Language (VHDL) or Verilog, which configures the connections between the smaller internal hardware blocks on the programmable device. The mentioned techniques are often used in combination to achieve the results of the functional blocks.

[0029] Figure 1 An example wireless communication network is shown in which embodiments of the present disclosure may be implemented.

[0030] like Figure 1 As shown, an example 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.

[0031] Each BSS 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, BSS 110-1 includes AP 104-1 and STA 106-1, and BSS 110-2 includes AP 104-2 and STAs 106-2 and 106-3. The AP and at least one STA in the BSS perform an association procedure to communicate with each other.

[0032] DS 130 may be configured to connect BSS 110-1 and BSS 110-2. DS 130 may therefore 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 identifier (SSID).

[0033] The WLAN infrastructure network 102 may be coupled to one or more external networks. Figure 1 As shown, the WLAN infrastructure network 102 can connect to another network 108 (eg, 802.X) through a portal 140. The portal 140 can act as a bridge connecting the DS 130 of the WLAN infrastructure network 102 with the other network 108.

[0034] Figure 1 The example wireless communication network shown in the figure may further include one or more ad hoc networks or independent BSSs (IBSSs). An ad hoc network or IBSS is a network that includes multiple STAs within communication range of each other. The multiple STAs are configured so that they can communicate with each other using direct peer-to-peer communication (i.e., not through an AP).

[0035] For example, in Figure 1 In FIG. 1 , STAs 106-4, 106-5, and 106-6 can be configured to form a first IBSS 112-1. Similarly, STAs 106-7 and 106-8 can be configured to form a second IBSS 112-2. Because an IBSS does not include an AP, it does not include a centralized management entity. Instead, the STAs within the IBSS are managed in a distributed manner. The STAs forming the IBSS can be fixed or mobile.

[0036] The STA as a predetermined functional medium may include a medium access control (MAC) layer compliant with the IEEE 802.11 standard. The physical layer interface of the radio medium may be used in both APs and non-AP stations (STAs). STAs may also be referred to using various other terms, including mobile terminals, wireless devices, wireless transmit / receive units (WTRUs), user equipment (UEs), mobile stations (MSs), mobile user units, or users. For example, the term "user" may be used to refer to a STA that participates in uplink multi-user multiple input, multiple output (MU MIMO) and / or uplink orthogonal frequency division multiple access (OFDMA) transmissions.

[0037] A physical layer (PHY) protocol data unit (PPDU) may be a composite structure comprising a PHY preamble and a payload in the form of a PLCP service data unit (PSDU). For example, a PSDU may comprise a PHY convergence protocol (PLCP) preamble and a header and / or one or more MAC protocol data units (MPDUs). The information provided in the PHY preamble may be used by the receiving device to decode subsequent data in the PSDU. In the case where the PPDU is transmitted over a bonded channel (a channel formed by channel bonding), the preamble field may be replicated and transmitted in each of the multiple constituent channels. The PHY preamble may comprise both a traditional portion (or "traditional preamble") and a non-traditional portion (or "non-traditional preamble"). Traditional preambles may be used for purposes such as packet detection, automatic gain control, and channel estimation. Traditional preambles may also typically be used to maintain compatibility with legacy devices. The format, encoding, and information provided therein of the non-traditional portion of the preamble are based on the specific IEEE 802.11 protocol to be used to transmit the payload.

[0038] A frequency band may include one or more sub-bands or frequency channels. For example, a PPDU compliant with IEEE 802.11n, 802.11ac, 802.11ax, and / or 802.11be standard amendments may be transmitted in the 2.4 GHz, 5 GHz, and / or 6 GHz frequency bands, each of which may be divided into multiple 20 MHz channels. A PPDU may be transmitted over a physical channel with a minimum bandwidth of 20 MHz. Larger channels may be formed through channel bonding. For example, a PPDU may be transmitted over a physical channel with a bandwidth of 40 MHz, 80 MHz, 160 MHz, or 520 MHz by bonding multiple 20 MHz channels together.

[0039] Figure 2 is a block diagram illustrating an example embodiment of STA 210 and AP 260. Figure 2 As shown, STA 210 may include at least one processor 220, memory 230, and at least one transceiver 240. AP 260 may include at least one processor 270, memory 280, and at least one transceiver 290. Processors 220 / 270 may be operatively connected to transceivers 240 / 290.

[0040] The transceiver 240 / 290 may be configured to transmit / receive radio signals. In an embodiment, the transceiver 240 / 290 may implement the PHY layer of the corresponding device (STA 210 or AP 260).

[0041] In an embodiment, STA 210 and / or AP 260 may be a multi-link device (MLD), i.e., a device capable of operating on multiple links as defined by the IEEE 802.11be standard amendment. Accordingly, STA 210 and / or AP 260 may each have multiple PHY layers. Multiple PHY layers may be implemented using one or more of transceivers 240 / 290.

[0042] The processor 220 / 270 may implement functions of a PHY layer, a MAC layer, and / or a logical link control (LLC) layer of a corresponding device (STA 210 or AP 260 ).

[0043] The processor 220 / 270 and / or the transceiver 240 / 290 may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and / or data processors. The memory 230 / 280 may include a read-only memory (ROM), a random access memory (RAM), a flash memory, a memory card, a storage medium, and / or other storage units.

[0044] When the embodiment is implemented by software, the techniques (or methods) described herein can be implemented with modules (e.g., procedures, functions, etc.) that perform the functions described herein. The modules can be stored in the memory 230 / 280 and executed by the processor 220 / 270. The memory 230 / 280 can be implemented (or located) within the processor 220 / 270 or external to the processor 220 / 270. The memory 230 / 280 can be operatively connected to the processor 220 / 270 in various ways known in the art.

[0045] Figure 3 An example format of a MAC frame is shown. In operation, a STA can construct a subset of MAC frames for transmission and can decode a subset of received MAC frames for verification. The specific subset of frames that a STA can construct and / or decode can be determined by the functions supported by the STA. A STA can verify a received MAC frame using the frame check sequence (FCS) contained in the frame and can interpret certain fields based on the MAC header of all frames.

[0046] like Figure 3 As shown, the MAC frame includes a MAC header, a variable-length frame body, and a frame check sequence (FCS).

[0047] The MAC header contains 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.

[0048] The Frame Control field contains the following subfields: Protocol Version, Type, Subtype, To DS, From DS, More Fragments, Retry, Power Management, More Data, Protected Frame, and +HTC.

[0049] The Protocol Version subfield is constant in size and placement across all revisions of the IEEE 802.11 standard. For MAC frames, the value of the Protocol Version subfield is 0.

[0050] Together, the Type and Subtype subfields identify the function of the MAC frame. There are three frame types: Control, Data, and Management. Each of these frame types has several defined subtypes. The bits within the Subtype subfield are used to indicate specific modifications 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, i.e., a data frame that includes a QoS Control field in its MAC header. When set to 1 in a data subtype, the second MSB of the Subtype field, Bit 6 (B6) of the Frame Control field, indicates a data frame that does not include a Frame Body field.

[0051] The To DS subfield indicates whether the data frame is directed to a Distribution System (DS). The From DS subfield indicates whether the data frame originates from a DS.

[0052] In all data or management frames that have another fragment after a MAC Service Data Unit (MSDU) or MAC Management Protocol Data Unit (MMPDU) carried by the MAC frame, the More Fragments subfield is set to 1. In all other frames in which the More Fragments subfield is present, it is set to 0.

[0053] In any data or management frame that is a retransmission of an earlier frame, the Retry subfield is set to 1. In all other frames in which the Retry subfield is present, it is set to 0. The receiving STA uses this indication to assist in its process of eliminating duplicate frames. These rules do not apply to frames sent by STAs according to the block protocol.

[0054] The Power Management subfield is used to indicate the power management mode of the STA.

[0055] The More Data subfield indicates to a STA in power save (PS) mode that bufferable units (BU) are buffered at the AP for that STA. The More Data subfield is valid in individually addressed data or management frames transmitted by the AP to the STA in PS mode. The More Data subfield is set to 1 to indicate that at least one additional buffered BU exists for the STA.

[0056] If the Frame Body field contains information that has been processed through the encryption encapsulation algorithm, the Protected Frame subfield is set to 1.

[0057] The +HTC subfield indicates that the MAC frame contains the HT Control field.

[0058] The Duration / ID field in the MAC header indicates different 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), with both of the two most significant bits (MSBs) set to 1. In other frames sent by STAs, the Duration / ID field contains a duration value (in microseconds) used by the receiver to update the Network Allocation Vector (NAV). The NAV is a counter that indicates to the STA the amount of time during which it must defer access to the shared medium.

[0059] There can be up to four address fields in the MAC frame format. These fields are used to indicate the Basic Service Set Identifier (BSSID), Source Address (SA), Destination Address (DA), Transport Address (TA), and Receive Address (RA). Some frames may not contain some address fields. The use of certain address fields can be specified by the relative position of the Address fields (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 recipient of the frame, and the Address 2 field (if present) always identifies the transmitter of the frame.

[0060] The Sequence Control field contains two subfields: the Sequence Number subfield and the Fragment Number subfield. The Sequence Number subfield in a data frame indicates the sequence number of the MSDU (if not in an Aggregate MSDU (A-MSDU)) or 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 the MSDU or MMPDU. In the first or only fragment of an MSDU or MMPDU, the fragment number is set to 0 and increments by one for each consecutive fragment of that MSDU or MMPDU. In a MAC Protocol Data Unit (MPDU) containing an A-MSDU or in an MPDU containing an unfragmented MSDU or MMPDU, the fragment number is set to 0. The fragment number remains constant across all retransmissions of the fragment.

[0061] The QoS Control field identifies the Traffic Class (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 may vary depending on the frame type, frame subtype, and the type of transmitting STA. The QoS Control field is present in all data frames where the QoS subfield of the Subtype subfield is equal to 1.

[0062] 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.

[0063] The Frame Body field is a variable length field that contains information specific to individual frame types and subtypes. It can contain one or more MSDUs or MMPDUs. The minimum length of the Frame Body is 0 octets.

[0064] The FCS field contains a 32-bit cyclic redundancy check (CRC) code. The FCS field value is calculated over all fields in the MAC header and frame body fields.

[0065] Figure 4 An example of a QoS Null frame indicating buffer status information is shown. A QoS Null frame is a QoS data frame with an empty frame body. The QoS Null frame contains a QoS Control field and an optional HT Control field, which may contain a Buffer Status Report (BSR) Control subfield. A QoS Null frame indicating buffer status information can be transmitted by a STA to an AP.

[0066] The QoS control field may include a traffic identifier (TID) subfield, an ack policy indicator subfield, and a queue size subfield (or a requested transmission opportunity (TXOP) duration subfield).

[0067] The TID subfield identifies the TC or TS for the traffic for which a TXOP is being requested by setting the Requested TXOP Duration or Queue Size subfield. The encoding of the TID subfield depends on the access policy (for example, values ​​0 to 7 are allowed for the Enhanced Distributed Channel Access (EDCA) access policy to identify the user priority of the TC or TS).

[0068] The ack policy indicator subfield, along with other information, identifies the acknowledgment policy to follow after delivering the MPDU (e.g., normal ack, implicit block ack request, no ack, block ack, etc.)

[0069] The Queue Size subfield is an 8-bit field that indicates the amount of buffered traffic at the STA for a given TC or TS for transmission to the AP identified by the receive address of the frame containing this subfield. When bit 4 of the QoS Control field is set to 1, the Queue Size subfield is present in QoS Null frames transmitted by the STA. The AP can use the information contained in the Queue Size subfield to determine the TXOP duration assigned to the STA or to determine the uplink (UL) resources assigned to the STA.

[0070] In frames sent by or to non-high-efficiency (non-HE) STAs, the following rules may apply to the queue size value:

[0071] - The queue size value is the approximate total size of all MSDUs and A-MSDUs buffered at the STA in the delivery queue for MSDUs and A-MSDUs (excluding the MSDUs or A-MSDUs contained in this QoS data frame), rounded up to the nearest multiple of 256 octets and expressed in units of 256 octets, where the TID value is equal to the value indicated in the TID subfield of the QoS Control field.

[0072] - A queue size value of 0 is used only to indicate that there is no buffered traffic in the queue for the specified TID.

[0073] - For all sizes greater than 64 768 octets, use a queue size value of 254.

[0074] - A queue size value of 255 is used to indicate an unspecified or unknown size.

[0075] In frames sent by a HE STA to a HE AP, the following rules may apply to the queue size value.

[0076] The queue size value QS is the approximate total size of all MSDUs and A-MSDUs (including MSDUs or A-MSDUs contained in the same PSDU as the frame containing the Queue Size subfield) buffered at the STA in the delivery queue for MSDUs and A-MSDUs, expressed in octets, where the TID value is equal to the value indicated in the TID subfield of the QoS Control field.

[0077] The Queue Size subfield contains the Scaling Factor subfield in bits B14-B15 of the QoS Control field and the Unscaled Value UV in bits B8-B13 of the QoS Control field. The Scaling Factor subfield provides the Scaling Factor SF.

[0078] The STA obtains the queue size QS from the received QoS control field containing the scaling factor SF and the unscaled value UV as follows:

[0079] QS=

[0080] 16×UV, if SF is equal to 0;

[0081] 1024+256×UV, if SF is equal to 1;

[0082] 17 408 + 2048 × UV, if SF is equal to 2;

[0083] 148 480 + 32 768 × UV, if SF is equal to 3 and UV is less than 62;

[0084] >2 147 328, if SF equals 3 and UV equals 62;

[0085] Unspecified or unknown if SF equals 3 and UV equals 63.

[0086] The Requested TXOP Duration subfield, which may be included instead of the Queue Size subfield, indicates the duration the transmitting STA determines it requires for the next TXOP for the specified TID, in units of 32 microseconds (µs). The Requested TXOP Duration subfield is set to 0 to indicate that no TXOP is requested for the specified TID in the current Service Period (SP). The Requested TXOP Duration subfield is set to a non-zero value to indicate a requested TXOP duration in increments of 32 µs within the range of 32 µs to 8160 µs.

[0087] The HT Control field may include a BSR Control subfield, which may contain buffer status information for UL MU operation. The BSR Control subfield may be formed by the Access Category Index (ACI) Bitmap subfield, Incremental TID subfield, ACI High subfield, Scale Factor subfield, Queue Size High subfield, and Queue Size Full subfield of the HT Control field.

[0088] The ACI Bitmap subfield indicates the access category for which the buffer status is reported (e.g., B0: Best Effort (AC_BE); B1: Background (AC_BK); B2: Video (AC_VI); B3: Voice (AC_VO), etc.). Each bit of the ACI Bitmap subfield is set to 1 to indicate that the buffer status of the corresponding AC is included in the Queue Size Full subfield, and is set to 0 in other cases. However, if the ACI Bitmap subfield is 0 and the Increment TID subfield is 3, the buffer status of all 8 TIDs is included.

[0089] The value of the Incremental TID subfield and the ACI Bitmap subfield indicates the number of TIDs for which the STA is reporting buffer status.

[0090] The ACI High subfield indicates the ACI of the AC indicated by the BSR in the Queue Size High subfield. The ACI to AC mapping is defined as ACI value 0 maps to AC_BE, ACI value 1 maps to AC_BK, ACI value 2 maps to AC_VI, and ACI value 3 maps to AC_VO.

[0091] The Scale Factor subfield indicates the unit SF of the Queue Size High and Queue Size Full subfields, expressed in octets.

[0092] The Queue Size High subfield indicates the amount of buffered traffic for the AC identified by the ACI High subfield, in units of SF octets, intended for the STA identified by the receive address of the frame containing the BSR Control subfield.

[0093] The Queue Size Full subfield indicates the amount of buffered traffic for all ACs identified by the ACI Bitmap subfield, in units of SF octets, intended for the STA identified by the receive address of the frame containing the BSR Control subfield.

[0094] The queue size value in the Queue Size High and Queue Size Full subfields is the total size of all MSDUs and A-MSDUs buffered at the STA in the delivery queues for MSDUs and A-MSDUs associated with the AC specified in the ACI High and ACI Bitmap subfields, respectively (including MSDUs or A-MSDUs contained in the same PSDU as the frame containing the BSR Control subfield), rounded up to the nearest multiple of SF octets.

[0095] A Queue Size value of 254 in the Queue Size High and Queue Size Full 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 Full subfields indicates that the amount of buffered traffic is an unspecified or unknown size. The Queue Size value for a QoS data frame containing fragments may remain constant even if the amount of queued traffic changes when transmitting consecutive fragments.

[0096] The MAC service provides peer entities with the ability to exchange MSDUs. To support this service, the local MAC uses the underlying PHY-level services to transfer MSDUs to the peer MAC entity. This asynchronous MSDU transfer is performed on a connectionless basis.

[0097] Figure 5 An example format of a PPDU is shown. As shown in the figure, a PPDU may include a PHY preamble, a PHY header, a PSDU, a tail, and padding bits.

[0098] A PSDU may contain one or more MPDUs, such as QoS data frames, MMPDUs, MAC control frames, or QoS null frames. In the case where an MPDU carries a QoS data frame, the frame body of the MPDU may contain an MSDU or an A-MSDU.

[0099] By default, MSDU transmission is on a best-effort basis. That is, there is no guarantee that a transmitted MSDU will be successfully delivered. However, QoS facilities use traffic identifiers (TIDs) to specify differentiated services on a per-MSDU basis.

[0100] STAs can differentiate between MSDU deliveries based on their assigned traffic class (TC) or traffic stream (TS). The MAC sublayer entity determines the user priority (UP) of an MSDU based on the TID value provided with the MSDU. The QoS facility supports eight UP values. UP values ​​range from 0 to 7 and form an ordered priority sequence, with 1 being the lowest value, 7 being the highest, and 0 falling between 2 and 3.

[0101] An MSDU with a particular UP is said to belong to the traffic class with that UP. The UP may be provided directly with each MSDU at the Medium Access Control Service Access Point (MAC SAP) in the UP parameter. An A-MPDU may contain MPDUs with different TID values.

[0102] STAs can send buffer status reports (BSRs) to assist the AP in allocating UL MU resources. STAs can send BSRs implicitly in the QoS Control field or BSR Control subfield of any frame transmitted to the AP (unsolicited BSR), or explicitly in frames sent to the AP in response to a BSRP trigger frame (solicited BSR).

[0103] The buffer status reported in the QoS control field contains the queue size value for a given TID. The buffer status reported in the BSR control field contains the ACI bitmap, incremental TID, high priority AC, and two queue sizes.

[0104] The STA may report the buffer status of transmitted QoS null frames and QoS data frames to the AP in the QoS control field, and report the buffer status of transmitted QoS null frames, QoS data frames, and management frames in the BSR control subfield (if present), as defined below.

[0105] 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 frame or QoS Null frame. A STA may set the Queue Size subfield to 255 to indicate an unknown / unspecified queue size for the TID. A STA may aggregate multiple QoS Data frames or QoS Null frames in an A-MPDU to report queue sizes for different TIDs.

[0106] If the AP has indicated that it supports receiving the BSR Control subfield, the STA may report the buffer status in the BSR Control subfield of the transmitted frame.

[0107] 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 the AC.

[0108] HE STAs may report the queue sizes of the ACs indicated by the ACI Bitmap subfield in the Queue Size Full subfield of the BSR Control subfield. STAs may set the Queue Size Full subfield to 255 to indicate unknown / unspecified BSRs for those ACs.

[0109] Figure 6 An example is shown including buffer status reporting by STAs, scheduling by the AP of uplink multi-user (MU) transmissions, and transmission of the scheduled uplink transmissions by STAs.

[0110] As shown in the figure, the AP can request the buffer status of one or more associated STAs (STA 1 and STA 2) by sending a Buffer Status Report Poll (BSRP) trigger frame. After receiving the BSRP trigger frame, if the BSRP trigger frame contains the 12 LSBs of the STA AID in the user information field, STA 1 and / or STA 2 can each generate a trigger-based (TB) PPDU.

[0111] 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 contain one or more QoS control fields or one or more BSR control subfields.

[0112] As described earlier, the QoS Control field may contain a Queue Size subfield for the TIDs whose queue sizes the STA has to report to the AP. Figure 6As shown in FIG, STA 1 can respond to the BSRP trigger frame from the AP by transmitting an A-MPDU containing multiple QoS Null frames. Each QoS Null frame indicates the queue size of the corresponding TID in its corresponding QoS Control field, such as TID 0 and TID 2. Similarly, STA 2 can respond to the BSRP trigger frame by transmitting an MPDU containing a QoS Null frame, wherein the QoS Null frame indicates the queue size of TID 2 in its QoS Control field.

[0113] The BSR Control subfield may include a Queue Size Full subfield indicating the queue size for the AC indicated by the ACI Bitmap subfield. If the AP has indicated that it supports receiving the BSR Control subfield, then the STA has a queue size to report to the AP. The STA sets the Incremental TID, Scale Factor, ACI High, and Queue Size High subfields of the BSR Control subfield.

[0114] Upon receiving a BSR from STA 1 and STA 2, the AP may transmit a Basic Trigger frame to allocate UL MU resources to STA 1 and STA 2. In response, STA 1 may transmit a TB PPDU containing QoS data frames with TIDs 0 and 2, and STA 2 may transmit a TB PPDU containing one or more QoS data frames with TIDs 0 and 2. The AP may acknowledge the TB PPDUs transmitted from STA 1 and STA 2 by sending a Multi-STA Block Ack frame.

[0115] Figure 7 An example reference model of a multi-link device (MLD) is shown.

[0116] An MLD is an entity capable of managing communications over multiple links. An MLD can be a logical entity and can have more than one attached station (STA). An MLD can be an access point MLD (AP MLD), where the STA attached to the MLD is an AP STA (or AP). An MLD can be a non-access point MLD (non-AP MLD), where the STA attached to the MLD is a non-AP STA (or STA).

[0117] Depending on the capabilities of both the communicating AP MLD and the non-AP MLD, the communication across different frequency bands / channels may or may not occur simultaneously.

[0118] like Figure 7 As shown, the MLD can have a single MAC Service Access Point (MAC-SAP) to the LLC layer, including MAC data services. The MLD can support multiple MAC sublayers coordinated by a sublayer management entity (SME). Each AP STA (or non-AP STA) attached to an AP MLD (or non-AP MLD) has a different MAC address within the MLD.

[0119] The SME is responsible for coordinating the MAC sublayer management entity (MLME) of the MLD's subordinate STAs to maintain a single robust security network association (RSNA) key management entity and a single IEEE 802.1X authenticator or provisioner for multi-link operation (MLO).

[0120] The Multi-Link Operation (MLO) procedure allows a pair of MLDs to discover, synchronize, (de)authenticate, (re)associate, disassociate, and manage resources on any common band or channel supported by both MLDs. The authenticator and MAC-SAP of an AP MLD can be identified by the same AP MLD MAC address. The provisioner and MAC-SAP of a non-AP MLD can be identified by the same non-AP MLD MAC address.

[0121] Figure 8 An example of an AP MLD and associated non-AP MLDs is shown.

[0122] As shown in the figure, an AP MLD has two subordinate APs (AP1 and AP2), and a non-AP MLD has two subordinate STAs (STA1 and STA2). The AP MLD and the non-AP MLD can 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.

[0123] Typically, the MAC addresses of an MLD and its affiliated STAs are different. Figure 8 As shown, AP MLD may have MAC address M, AP 1 may have MAC address w, and AP 2 may have MAC address x. Similarly, non-AP MLD may have MAC address P, STA 1 may have MAC address y, and STA 2 may have MAC address z.

[0124] like Figure 8 As shown, for each MLD, the MAC sublayer can be further divided into the MLD upper MAC sublayer and the MLD lower MAC sublayer. The MLD upper MAC sublayer (MLD) performs functions common to all links. The MLD lower MAC sublayer performs functions local to each link. Some functions require joint processing by both the MLD upper MAC layer and the MLD lower MAC sublayer.

[0125] The MAC sublayer functions above MLD include:

[0126] - Authentication, association, and reassociation (between AP MLD and non-AP MLD);

[0127] - Distribution of security associations (e.g., Pairwise Master Key Security Association (PMKSA), Pairwise Transient Key Security Association (PTKSA)) and Group Temporal Key (GTK) / Integrity GTK (IGTK) / Beacon IGTK (BIGTK);

[0128] - Assigning a sequence number (SN) / packet number (PN) to a frame encrypted by a pairwise transient key (PTK) for unicast frames;

[0129] -Use PTK to encrypt / decrypt unicast frames;

[0130] -Selection of the MLD lower MAC sublayer for transmission (TID to link mapping);

[0131] - Reorder packets to ensure in-order delivery for each Block Ack session;

[0132] - Block Ack scoreboard for individually addressed frames (in collaboration with the MLD lower MAC sublayer); optionally, the MLD upper MAC sublayer delivers Block Ack records on one link to the MLD lower MAC sublayer of the other link; and - MLD-level management information exchange / indication via the MLD lower MAC sublayer

[0133] The MAC sublayer functions under MLD include:

[0134] - Maintenance of link-specific GTK / IGTK / BIGTK (between an AP attached to an AP MLD and a STA attached to a non-AP MLD);

[0135] - Link-specific encryption / decryption / integrity protection and PN assignment using GTK / IGTK / BIGTK (between an AP attached to an AP MLD and a STA attached to a non-AP MLD);

[0136] - Link-specific management information exchange / indication (e.g., beacons);

[0137] - Link-specific control information exchange / indication (e.g., RTS / CTS, acknowledgments, etc.);

[0138] -Power saving states and modes;

[0139] - MAC address filtering for frame reception; and

[0140] - Block Ack scoreboard for individually addressed frames (in collaboration with the MLD upper MAC sublayer); optionally, the MLD lower MAC sublayer receives Block Ack records on other links from the MLD upper MAC sublayer.

[0141] The multilink (re)setup between the non-AP MLD and the AP MLD may include an exchange of (re)association request / response frames. The (re)association request / response frame exchange for the multilink setup may include two frames carrying basic multilink elements.

[0142] In the (re)association request frame, the non-AP MLD indicates the link being requested for (re)configuration and the capabilities and operating parameters of the requested link. The non-AP MLD can request (re)configuration of links with a subset of APs affiliated with the AP MLD. The requested link and the capabilities and operating parameters of the requested link are independent of the existing configured link and the capabilities and operating parameters of the configured link with the associated AP MLD.

[0143] In the (re)association response frame, the AP MLD may indicate the requested links accepted and rejected for (re)configuration, as well as the capabilities and operating parameters of the requested links. The AP MLD may accept a subset of the links requested for (re)configuration. The (re)association response frame is sent to a non-AP STA attached to a non-AP MLD that has sent a (re)association request frame.

[0144] The MLD that requests or accepts multilink (re)configuration for any two links ensures that each link is on a different, non-overlapping channel. After a successful multilink (re)configuration between a non-AP MLD and an AP MLD, the non-AP MLD and the APMLD configure the links for multilink operation, and the non-AP MLD (re)associates with the AP MLD. For each configured link, the corresponding non-AP STA attached to the non-AP MLD is placed in the same association state as the non-AP MLD and is associated with the corresponding AP attached to the APMLD. For each configured link, functionality between the non-AP STA and its associated AP is enabled, unless functionality has been extended to the MLD level or otherwise specified.

[0145] Figure 9 This figure shows an example of a multilink setup between an AP MLD and a non-AP MLD. As shown, the AP MLD has three subordinate 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. The non-AP MLD has three subordinate 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.

[0146] The non-AP MLD can initiate multi-link setup by sending an association request frame from non-AP STA 1 to AP 1, which is affiliated 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 contains a basic multi-link element, which indicates the MLD MAC address of the non-AP MLD and complete information about non-AP STA 1, non-AP STA 2, and non-AP STA 3. The association request frame can request the setup of three links between the non-AP MLD and the AP MLD: the link between AP 1 and non-AP STA 1, the link between AP 2 and non-AP STA 2, and the link between AP 3 and non-AP STA 3.

[0147] AP MLD can respond to the requested multi-link setup by sending an association response frame to non-AP STA 1, which is attached to 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 contains a basic multi-link element, which indicates the MLD MAC address of AP MLD and complete information about AP 1, AP 2, and AP 3. The association response frame signals the successful multi-link setup by setting up three links between non-AP MLD and 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.

[0148] By default, all TIDs at a non-AP MLD are mapped to all setup links for both uplink and downlink. The TID-to-link mapping mechanism allows both AP MLDs and non-AP MLDs that have performed or are performing multi-link setup to specify how UL and DL QoS traffic corresponding to different TIDs (e.g., between 0 and 7) can be assigned to setup links. In the negotiated TID-to-link mapping, a TID can be mapped to a link set, which is a subset of the setup links, ranging from a single setup link to all setup links.

[0149] A link is defined as enabled for non-APMLD if at least one TID is mapped to a setup link in either DL or UL, and is defined as disabled if no TID is mapped to the 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 is valid and successful only if it does not result in a TID having a mapped link set consisting of zero setup links.

[0150] By default, all setup links are enabled. If a link is enabled for non-AP MLD, the link can be used to exchange individually addressed frames, depending on the power state of the non-AP STA operating on the link. Only MSDUs or A-MSDUs with a TID mapped to the link can be transmitted on the link in the direction (DL / UL) corresponding to the TID-to-link mapping. Individually addressed management frames and control frames can be sent on any enabled link between a non-AP MLD's affiliated STA and the corresponding AP of an AP MLD, in both DL and UL.

[0151] If a link is disabled for non-AP MLD, the link may not be used to exchange individually addressed frames between the affiliated STAs of the non-AP MLD and the corresponding AP of the AP MLD.

[0152] If a TID is mapped in the UL to a set of enabled links for a non-AP MLD, the non-AP MLD may use any link within the set of enabled links to transmit an individually addressed MSDU or A-MSDU corresponding to the TID.

[0153] If a TID is mapped in the DL to a set of enabled links for a non-AP MLD, the non-AP MLD may retrieve individually addressed BUs for MSDUs or A-MSDUs corresponding to the TID buffered at the AP MLD on any link in the set of enabled links. Conversely, the AP MLD may use any link within the set of enabled links to transmit individually addressed MSDUs or A-MSDUs corresponding to the TID, depending on the power state of the non-AP STA on each used link.

[0154] If the default mode is used, a non-AP MLD can retrieve a BU buffered by an AP MLD on any setup link, although the AP MLD can recommend a link.

[0155] The non-AP MLD can retrieve buffered BUs, which are MMPDUs buffered at the AP MLD on any enabled link. The AP MLD can use any enabled link to transmit separately addressed bufferable management frames that are not measurement MMPDUs, depending on the power state of the non-AP STA on the link used.

[0156] If a STA attached to a non-AP MLD is in active mode on a link with a set of TIDs mapped for DL ​​transmission, its associated AP attached to an AP MLD may transmit to the STA: MSDUs / A-MSDUs for the non-AP MLD's mapped set of TIDs; and MMPDUs that are not measurement MMPDUs for the non-AP MLD or its attached STAs, unless the frame is transmitted to another STA attached to the same non-AP MLD and in active mode.

[0157] As mentioned above, in the default mapping mode, all TIDs are mapped to all setup links for DL ​​and UL, and all setup links are enabled. Non-AP MLD and AP MLD that perform multi-link setup should operate in this mode if TID-to-link mapping negotiation for different mappings does not occur, is unsuccessful, or is torn down.

[0158] In the multilink (re)setup procedure, if the AP MLD has indicated support for TID-to-link mapping negotiation, the non-AP MLD may initiate TID-to-link mapping negotiation by including a TID-to-link mapping element in the (re)association request frame.

[0159] After receiving a (Re)Association Request frame containing a TID-to-Link Mapping element, the AP MLD may reply to the (Re)Association Request frame according to the following rules. The AP MLD may accept the requested TID-to-link mapping indicated in the TID-to-Link Mapping element in the received (Re)Association Request frame only if the AP MLD accepts the multilink (re)configuration for all links for which at least one TID is requested to be mapped. In this case, the non-AP MLD does include 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 in the (Re)Association Response frame that suggests a preferred TID-to-link mapping.

[0160] After a successful multilink (re)setup, in order to negotiate a new TID-to-link mapping, the initiating MLD may send an individually addressed TID-to-link mapping request frame to the responding MLD that has indicated support for TID-to-link mapping negotiation.

[0161] 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 accept the requested TID-to-link mapping indicated in the TID-to-link mapping element in the received TID-to-link mapping request frame by transmitting a TID-to-link mapping response frame. Otherwise, the responding MLD may indicate a rejection of the proposed TID-to-link mapping in a TID-to-link mapping response frame. The responding MLD may propose a preferred TID-to-link mapping in a TID-to-link mapping response frame by including a TID-to-link mapping element in the TID-to-link mapping response frame.

[0162] An MLD may propose a preferred TID-to-link mapping to a peer MLD by sending an unsolicited TID-to-link mapping response frame containing a TID-to-link mapping element.

[0163] When a peer MLD indicates a preferred TID-to-link mapping, the MLD may consider the preferred TID-to-link mapping when initiating a new TID-to-link mapping. Additionally, the AP MLD may consider traffic flows attached to the non-AP MLD and the capabilities and constraints (if any) of the non-AP MLD.

[0164] When two MLDs have negotiated a TID-to-link mapping, either MLD can tear down the negotiated TID-to-link mapping by sending a separately addressed TID-to-link mapping teardown frame. After teardown, the MLD operates in the default mapping mode.

[0165] When the MLD successfully negotiates TID-to-link mapping with a peer MLD, both the MLD and the peer MLD update uplink and / or downlink TID-to-link mapping information according to the negotiated TID-to-link mapping.

[0166] When the MLD has successfully negotiated uplink and / or downlink TID-to-link mappings with a peer MLD, wherein bit position i of the LinkMap field n in the TIDToLinkMap element is set to 0, TID n shall not be mapped to the link associated with LinkIDi in the uplink and / or downlink. When the MLD has successfully negotiated uplink and / or downlink TID-to-link mappings with a peer MLD, wherein bit position i of the LinkMap field n in the TIDToLinkMap element is set to 1, TID n is mapped to the link associated with LinkIDi in the uplink and / or downlink.

[0167] Figure 10 An example of TID-to-link mapping in a multi-link communication environment is shown. As shown in the figure, the multi-link communication environment includes an AP MLD with three attached APs and a non-AP MLD with three attached STAs.

[0168] During or after multi-link setup, the non-AP MLD and the AP MLD can negotiate a TID-to-link mapping. The TID-to-link mapping maps the TIDs at the non-AP MLD in UL and DL to set up a link between the AP MLD and the non-AP MLD. For example, Figure 10 As shown, TID-to-link mapping can map TIDs 0-6 in both UL and DL to link 1, and map TID 7 in both UL and DL to link 2. Therefore, links 1 and 2 are enabled, and link 3 is disabled. TID-to-link mapping negotiation can 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.

[0169] Figure 11FIG. 1 shows an existing buffer status report with TID to link mapping in the example multi-link communication environment 1100. Figure 11 As shown, example environment 1100 may include non-AP MLD 1110 and AP MLD 1111. Non-AP MLD 1110 and AP MLD 1111 may be communicatively coupled by a plurality of (set) links (e.g., Link 1, Link 2, and Link 3). Non-AP MLD 1110 may include a plurality of subordinate STAs (e.g., STA1, STA2, and STA3). AP MLD 1111 may include a plurality of subordinate APs (e.g., AP1, AP2, and AP3). The plurality of subordinate STAs of non-AP MLD 1110 may each be configured to communicate with a corresponding subordinate AP of AP MLD 1111's plurality of subordinate APs on a corresponding link of the plurality of links communicatively coupling non-AP MLD 1110 and AP MLD 1111.

[0170] At the non-AP MLD 1110, there may be multiple UL and / or DL ​​traffic flows. Each flow may be associated with a TID (e.g., TID 0, TID 1, ..., TID 7). The various traffic flows may be queued in designated queues at the non-AP MLD 1110. Queues may be used to queue traffic for one or more TIDs.

[0171] In an example, the non-AP MLD 1110 and the AP MLD 1111 may negotiate a TID-to-link mapping. The TID-to-link negotiation may include exchanging TID-to-link mapping elements in association request frames and association response frames transmitted between the non-AP MLD 1110 and the AP MLD 1111. The TID-to-link mapping maps the TID at the non-AP MLD 1110 to the link set up between the non-AP MLD 1110 and the AP MLD 1111 in the uplink and / or downlink. In an example, as Figure 11 As shown, after a successful TID-to-link mapping negotiation, TIDs 0 through 6 may be mapped to both link 1 and link 2, and TID 7 may be mapped to link 3.

[0172] Non-AP MLD 1110 may have buffered traffic associated with the TID to transmit to AP MLD 1111. Figure 6As described, in a requested buffer status report, AP MLD 1111 may request non-AP MLD 1110 to report the buffer status by transmitting a Buffer Status Report Poll Trigger frame (BSRP) to AP MLD 1110. Non-AP MLD 1110 may respond by sending a QoS Null frame containing one or more Buffer Status Reports (BSRs). In a single-link environment where all TIDs at a non-AP STA are mapped to only one link, the non-AP STA follows a clearing rule, where 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 with an AP MLD via multiple links, and particularly where the non-AP MLD and the AP MLD have negotiated a TID-to-link mapping that assigns each TID at the non-AP MLD to one or more links between the non-AP MLD and the AP MLD.

[0173] In fact, the existing IEEE 802.11 standard specifications (e.g., draft P802.11be_D1.3) do not specify on which of multiple links a QoS NULL frame reporting buffer status for a given TID can be transmitted when a TID-to-link mapping has been negotiated between a non-AP MLD and an AP MLD. For example, the existing standard specification states, "An MSDU or A-MSDU with a TID mapped to an enabled link may only be transmitted on that link." While strictly speaking, a QoS NULL frame does not contain an MSDU or A-MSDU, similar rules for QoS NULL frames containing a TID would result in QoS NULL frames being transmitted only on the TID's mapped link. The existing standard specification further states, "Management frames and control frames may be sent on any enabled link." However, QoS NULL frames are not considered MAC management frames or MAC control frames.

[0174] Returning to example environment 1100, operation according to existing standard specifications may cause AP MLD 1111 to send a first Buffer Status Report Poll (BSRP) trigger frame on Link 1 to non-AP MLD 1110. In response to the first BSRP trigger frame, non-AP MLD 1110 may transmit a QoS Null frame. Based on the negotiated TID-to-link mapping that maps only TIDs 0-6 to Link 1, and following similar rules to existing MSDU / A-MSDU rules, non-AP MLD 1110 may include in the transmitted QoS Null frame a BSR for only TIDs 0-6, since the BSRP trigger frame is sent on Link 1, which is mapped only to TIDs 0-6. Therefore, to obtain the buffer status for TID 7, AP MLD 1111 may need to transmit a second BSRP trigger frame on Link 3 to request that non-AP MLD 1110 send a BSR for TID 7. Consequently, this may increase the AP MLD's overhead and latency in obtaining the non-AP MLD's complete buffer status (for all TIDs).

[0175] Figure 12-15 An example method for buffer status reporting in the presence of a TID-to-link mapping is illustrated according to an embodiment of the present disclosure. For illustrative purposes only, the example method is described below in the context of an example 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 to these examples and can be readily extended to a multi-link environment including multiple non-AP MLDs and multiple AP MLDs. Furthermore, the example method is described with reference to example communications between a non-AP MLD and an AP MLD. These example communications, such as the specific frame transmission sequence between the non-AP MLD and the AP MLD, are also provided for illustrative purposes only and should not be used to limit the embodiments of the present disclosure.

[0176] Figure 12 An example method for buffer status reporting for example environment 1200 is shown according to an embodiment. Figure 12As shown, example environment 1200 may include non-AP MLD 1210 and AP MLD 1211. Non-AP MLD 1210 and AP MLD 1211 may be communicatively coupled by a plurality of (set) links (e.g., Link 1, Link 2, and Link 3). Non-AP MLD 1210 may include a plurality of subordinate STAs (e.g., STA1, STA2, and STA3). AP MLD 1211 may include a plurality of subordinate APs (e.g., AP1, AP2, and AP3). The plurality of subordinate STAs of non-AP MLD 1210 may each be configured to communicate with a corresponding subordinate AP of AP MLD 1211 on a corresponding link of the plurality of links communicatively coupling non-AP MLD 1210 and AP MLD 1211.

[0177] In an example embodiment, non-AP MLD 1210 and 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 non-AP MLD 1210 and AP MLD 1211. Each link may communicatively couple a subordinate STA of non-AP MLD 1210 with a corresponding subordinate AP of AP MLD 1210. In an embodiment, each link may correspond to a specific frequency band among multiple supported frequency bands (e.g., 2.4 GHz, 5 GHz, and 6 GHz) between non-AP MLD 1210 and AP MLD 1211.

[0178] In an example embodiment, non-AP MLD 1210 and 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 non-AP MLD 1110 and AP MLD 1111. Figure 12 As shown, TIDs 0 through 6 can be mapped to link 1 in the uplink, which communicatively couples STA1 attached to non-AP MLD 1210 and AP1 attached to AP MLD 1211; and TID 7 can be mapped to link 2 in the uplink, which communicatively couples STA2 attached to non-AP MLD 1210 and AP2 attached to AP MLD 1211. According to this example TID-to-link mapping, links 1 and 2 can be considered "enabled" because at least one TID is mapped to each of links 1 and 2. On the other hand, link 3 can be considered "disabled" because no TID is mapped to link 3.

[0179] Based on the TID to link mapping, non-AP MLD 1210 may transmit frames carrying MSDUs or A-MSDUs with any of TIDs 0 to 6 on Link 1 ( Figure 12 ), and a frame carrying an MSDU or A-MSDU with TID 7 may be transmitted on link 2 ( Figure 12 not shown).

[0180] The non-AP MLD 1210 may be configured to transmit a frame 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.

[0181] In an embodiment, non-AP MLD 1210 may be configured to transmit BSR frames for any TID on any enabled link, regardless of the negotiated TID-to-link mapping.

[0182] In an example embodiment, non-AP MLD 1210 may be configured to transmit a BSR frame for any TID (e.g., TID 0 to TID 7) on any enabled link in response to a trigger frame sent from AP MLD 1211, regardless of the negotiated TID-to-link mapping. Figure 12 As shown, when non-AP MLD 1210 receives a first trigger frame 1220 on Link 1 from AP MLD 1211, it may have uplink buffered traffic associated with TID 7. First trigger frame 1220 may be a Buffer Status Report Poll (BSRP) trigger frame or a Basic Trigger frame. Regardless of the TID-to-link mapping that maps TID 7 only to Link 2, non-AP MLD 1210 may transmit a BSR frame 1221 on Link 1 containing the buffer status of TID 7 in response to first trigger frame 1220. BSR frame 1221 may include a QoS Null frame indicating TID 7 and queue size information for TID 7. BSR frame 1221 may be included in a TB-PPDU.

[0183] In another example embodiment, non-AP MLD 1210 may be configured to transmit an unsolicited BSR frame for any TID on any enabled link to AP MLD 1211, regardless of the negotiated TID-to-link mapping. The unsolicited BSR is sent without receiving a trigger frame from AP MLD 1211 and may be transmitted after accessing the wireless medium (WM) using Enhanced Distributed Access Control (EDCA). For example, Figure 12 As shown, when non-AP MLD 1210 obtains a transmission opportunity (TXOP) on link 2, it may have uplink buffered traffic for TID 7 and at least one other TID (e.g., any one of TIDs 0 to 6). Independently of the TID-to-link mapping that maps only TID 7 to link 2, non-AP MLD 1210 may transmit a non-TB PPDU carrying an unsolicited BSR frame 1223 for at least one other TID (in addition to TID 7). Unsolicited BSR frame 1223 may include one or more QoS null frames at non-AP MLD 1210, indicating the buffer status associated with the at least one other TID and queue size information for the at least one other TID. The non-TB PPDU may also carry an MSDU or A-MSDU for TID 7.

[0184] In another example embodiment, non-AP MLD 1210 may be configured to transmit a BSR frame for any TID on a disabled link to AP MLD 1211 in response to a trigger frame sent from AP MLD 1211, regardless of the negotiated TID-to-link mapping. Figure 12 As shown, non-AP MLD 1210 may receive a second trigger frame 1224 from AP MLD 1211, indicating one or more resource units (RUs) for disabling uplink OFDMA random access (UORA) on link 3. Second trigger frame 1224 may be a BSRP trigger frame or a basic trigger frame. Since all STAs are allowed to transmit on the indicated uplink RUs in response to second trigger frame 1224, non-AP MLD 1210 may transmit a BSR frame 1225 on link 3, even if no TID is mapped to link 3 in the TID-to-link mapping. BSR frame 1225 may include a QoS null frame indicating any TID (e.g., TID 0 to TID 7) and queue size information for the TID. BSR frame 1225 may be included in a TB-PPDU.

[0185] In another example embodiment, non-AP MLD 1210 may be configured to transmit an unsolicited BSR frame for a TID to AP MLD 1211 based on the TID-to-link mapping. The unsolicited BSR is sent without receiving a trigger frame from AP MLD 1211 and may be transmitted after accessing the wireless medium (WM) using EDCA. For example, Figure 12 As shown, non-AP MLD 1210 may obtain a transmission opportunity (TXOP) on Link 1. Based on the TID-to-link mapping, non-AP MLD 1210 may transmit a non-TB PPDU on Link 1 that carries an unsolicited BSR frame 1222 for any one of TIDs 0 to 6. Unsolicited BSR frame 1222 may include one or more QoS null frames indicating any one of TIDs 0 to 6 and queue size information for the indicated TID. The non-TB PPDU may also carry an MSDU or A-MSDU for TIDs 0 to 6.

[0186] Figure 13 Other example methods for buffer status reporting for example environment 1300 are shown according to an embodiment. Figure 13 As shown, example environment 1300 may include non-AP MLD 1310 and AP MLD 1311. Non-AP MLD 1310 and AP MLD 1311 may be communicatively coupled by a plurality of (set) links (e.g., Link 1, Link 2, and Link 3). Non-AP MLD 1310 may include a plurality of subordinate STAs (e.g., STA1, STA2, and STA3). AP MLD 1311 may include a plurality of subordinate APs (e.g., AP1, AP2, and AP3). The plurality of subordinate STAs of non-AP MLD 1310 may each be configured to communicate with a corresponding subordinate AP of AP MLD 1311 on a corresponding link of the plurality of links communicatively coupling non-AP MLD 1310 and AP MLD 1311.

[0187] As mentioned above Figure 12 As described, in an example embodiment, non-AP MLD 1310 and AP MLD 1311 may establish a multi-link setup and negotiate TID to link mapping during the association procedure. Figure 13 As shown, TIDs 0 through 6 can be mapped to link 1 in the uplink that communicatively couples STA 1 and AP 1, and TID 7 can be mapped to link 2 in the uplink that communicatively couples STA 2 and AP 2. According to this example TID-to-link mapping, links 1 and 2 can be considered "enabled" because at least one TID is mapped to each of links 1 and 2. On the other hand, link 3 can be considered "disabled" because no TID is mapped to link 3.

[0188] Based on the TID to link mapping, non-AP MLD 1310 may transmit frames carrying MSDUs or A-MSDUs with any of TIDs 0 to 6 on Link 1 ( Figure 13 ), and a frame carrying an MSDU or A-MSDU with TID 7 may be transmitted on link 2 ( Figure 13 not shown).

[0189] In an example, 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 an enabled link (e.g., link 1). The non-AP MLD 1310 receiving the first trigger frame 1320 may respond with a BSR frame 1321 indicating the buffer status of any TID in the first TB PPDU on the enabled link (e.g., link 1), regardless of the TID-to-link mapping. For example, the BSR frame 1321 may include one or more QoS null frames indicating a TID of any one of TID 0 to TID 7 and queue size information for the indicated TID.

[0190] 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 on link 1 (e.g., a basic trigger frame, a MU-RTS TXS trigger frame) to allocate uplink resources to the non-AP MLD 1310 of 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 on link 1, which includes one or more QoS data frames 1323 for the one or more indicated TIDs. The QoS data frame 1323 may include an MSDU or A-MSDU for the one or more indicated TIDs. The AP MLD 1311 that receives 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.

[0191] When 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 frame 1326 may include an MSDU or an A-MSDU for TID 7. The AP MLD 1311, having received 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.

[0192] In another example, AP MLD 1311 may transmit a fourth trigger frame 1330 (e.g., a BSRP trigger frame, a basic trigger frame, etc.) to non-AP MLD 1310 on a disabled link (e.g., Link 3). Non-AP MLD 1310, upon receiving the fourth trigger frame 1330 on the disabled link, may respond with a BSR frame 1331 on the disabled link, indicating the buffer status of any TID in the fourth TB PPDU, regardless of the TID-to-link mapping. For example, BSR frame 1331 may include one or more QoS null frames indicating a TID of any one of TIDs 0 to 7 and queue size information for the indicated TID. AP MLD 1311, upon receiving the fourth TB PPDU, may transmit subsequent trigger frames on Link 1 and / or Link 2 to allocate UL resources to non-AP MLD 1310 based on the indicated TID and its queue size information indicated in BSR frame 1331.

[0193] Figure 14 Other example methods for buffer status reporting for example environment 1400 are shown according to an embodiment. Figure 14 As shown, example environment 1400 may include non-AP MLD 1410 and AP MLD 1411. Non-AP MLD 1410 and AP MLD 1411 may be communicatively coupled by a plurality of (set) links (e.g., Link 1, Link 2, and Link 3). Non-AP MLD 1410 may include a plurality of subordinate STAs (e.g., STA1, STA2, and STA3). AP MLD 1411 may include a plurality of subordinate APs (e.g., AP1, AP2, and AP3). The plurality of subordinate STAs of non-AP MLD 1410 may each be configured to communicate with a corresponding subordinate AP of AP MLD 1411 on a corresponding link of the plurality of links communicatively coupling non-AP MLD 1410 and AP MLD 1411.

[0194] As mentioned above Figure 12 As described, in an example embodiment, non-AP MLD 1410 and AP MLD 1411 may establish a multi-link setup and negotiate TID to link mapping during the association procedure. Figure 14 As shown, TIDs 0 through 6 can be mapped to link 1 in the uplink that communicatively couples STA 1 and AP 1, and TID 7 can be mapped to link 2 in the uplink that communicatively couples STA 2 and AP 2. According to this example TID-to-link mapping, links 1 and 2 can be considered "enabled" because at least one TID is mapped to each of links 1 and 2. On the other hand, link 3 can be considered "disabled" because no TID is mapped to link 3.

[0195] Based on the TID to link mapping, the non-AP MLD 1410 may transmit frames carrying MSDUs or A-MSDUs with any of TIDs 0 to 6 on Link 1 ( Figure 14 ), and a frame carrying an MSDU or A-MSDU with TID 7 may be transmitted on link 2 ( Figure 14 not shown).

[0196] In an example, the non-AP MLD 1410 may transmit a BSR frame 1420 indicating the buffer status of any TID in the first non-TB PPDU on an enabled link (e.g., link 1) using EDCA, regardless of the TID-to-link mapping. For example, the BSR frame 1420 may include one or more QoS null frames indicating the TID of any one of TID 0 to TID 7 and the queue size information of the indicated TID.

[0197] When AP MLD 1411 receives a BSR frame 1420 indicating one or more TIDs between TID 0 and TID 6, AP MLD 1411 may transmit a first trigger frame 1422 on Link 1 (e.g., a basic trigger frame, a MU-RTS TXS trigger frame) to allocate uplink resources to non-AP MLD 1410 for the one or more TIDs indicated in BSR frame 1420. In response to the first trigger frame 1422, non-AP MLD 1410 may transmit a first TB PPDU on Link 1, which includes one or more QoS data frames 1423 for the one or more indicated TIDs. The QoS data frames 1423 may include MSDUs or A-MSDUs for the one or more indicated TIDs. AP MLD 1411, having received the first TB PPDU, may transmit a first acknowledgment frame 1424 in response to the QoS data frames 1423 included in the first TB PPDU.

[0198] When 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 an A-MSDU for TID 7. The AP MLD 1411, having received 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.

[0199] In another example, the non-AP MLD 1410 may be configured to transmit a BSR frame indicating the buffer status of the TID on an enabled link other than the link to which the indicated TID is mapped. Figure 14 As shown, non-AP MLD 1410 may transmit a BSR frame 1421 on enabled link 2, indicating the buffer status of one or more TIDs 0 to 6 in a second non-TB PPDU. BSR frame 1421 may include one or more QoS null frames indicating one or more TIDs 0 to 6 and queue size information for the indicated TIDs. AP MLD 1411, having received the second non-TB PPDU, may transmit a trigger frame (not shown) on link 1 based on the TIDs and queue size information indicated in BSR frame 1421. In response to the trigger frame, 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 an MSDU or A-MSDU for the indicated TID. AP MLD 1411, having received the TB PPDU, may transmit an acknowledgment frame (not shown) in response to the QoS data frames included in the TB PPDU.

[0200] Figure 15 Other example methods for buffer status reporting for example environment 1500 are shown according to an embodiment. Figure 15As shown, example environment 1500 may include non-AP MLD 1510 and AP MLD 1511. Non-AP MLD 1510 and AP MLD 1511 may be communicatively coupled by a plurality of (set) links (e.g., Link 1, Link 2, and Link 3). Non-AP MLD 1510 may include a plurality of subordinate STAs (e.g., STA1, STA2, and STA3). AP MLD 1511 may include a plurality of subordinate APs (e.g., AP1, AP2, and AP3). The plurality of subordinate STAs of non-AP MLD 1510 may each be configured to communicate with a corresponding subordinate AP of AP MLD 1511 on a corresponding link of the plurality of links communicatively coupling non-AP MLD 1510 and AP MLD 1511.

[0201] As mentioned above Figure 12 As described, in an example embodiment, non-AP MLD 1510 and AP MLD 1511 may establish a multi-link setup and negotiate TID to link mapping during the association procedure. Figure 15 As shown, TIDs 0 through 6 can be mapped to link 1 in the uplink that communicatively couples STA 1 and AP 1, and TID 7 can be mapped to link 2 in the uplink that communicatively couples STA 2 and AP 2. According to this example TID-to-link mapping, links 1 and 2 can be considered "enabled" because at least one TID is mapped to each of links 1 and 2. On the other hand, link 3 can be considered "disabled" because no TID is mapped to link 3.

[0202] Based on the TID to link mapping, non-AP MLD 1510 may transmit frames carrying MSDUs or A-MSDUs with any of TIDs 0 to 6 on Link 1 ( Figure 15 ), and a frame carrying an MSDU or A-MSDU with TID 7 may be transmitted on link 2 ( Figure 15 not shown).

[0203] In an example, the non-AP MLD 1510 may be configured to transmit an unsolicited BSR frame on an enabled link using EDCA that indicates the buffer status of a TID according to a TID-to-link mapping. Figure 15 As shown, non-AP MLD 510 may transmit a first non-TB PPDU on link 1, which includes an unsolicited BSR 1520 indicating the buffer status of any TID (i.e., TID 0 to TID 6) mapped to link 1. The BSR frame 1520 may include one or more QoS null frames indicating the TID of any one of TID 0 to TID 6 and the queue size information of the indicated TID.

[0204] 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 the 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 on Link 1, which includes one or more QoS data frames 1522 for the one or more indicated TIDs. The QoS data frames may include an MSDU or A-MSDU for the one or more indicated TIDs. The AP MLD 1511, having received 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.

[0205] In another example, the AP MLD 1411 may transmit a second trigger frame 1524 (e.g., a BSRP trigger frame) on Link 2 to request the buffer status of the non-AP MLD 1510 at the non-AP MLD 1510. In response to the second trigger frame 1524, the non-AP MLD 1510 may transmit a second TB PPDU on Link 2, which includes a BSR frame 1525 (e.g., a QoS null frame indicating TID 7 and queue size information for TID 7) indicating the buffer status of TID 7 according to the TID-to-link mapping. The AP MLD 1511, which receives the BSR frame 1525, may transmit a third trigger frame 1526 (e.g., a basic trigger frame, a MU-RTS TXS trigger frame) on Link 2 to allocate uplink resources to the non-AP MLD 1510 for TID 7. In response to the third trigger frame 1526, the non-AP MLD 1510 may transmit a third TB PPDU on link 2, which includes one or more QoS data frames 1527 for TID 7. The one or more QoS data frames 1527 may include an MSDU or A-MSDU for TID 7. The AP MLD 1511 that receives the third TB PPDU may transmit a second acknowledgment frame 1528 in response to the QoS data frames 1527 included in the third TB PPDU.

[0206] Figure 16An example process 1600 for transmitting buffer status according to an embodiment of the present disclosure is shown. Example process 1600 can be performed in an example environment including an AP MLD and a non-AP MLD. The non-AP MLD and the AP MLD can be communicatively coupled by a plurality of links and can be associated with a TID-to-link mapping. The TID-to-link mapping can include a first mapping of a first TID in an uplink to a first set of links in the plurality of links and a second mapping of a second TID in the uplink to a second set of links in the plurality of links. In an embodiment, the TID-to-link mapping is based on: TID-to-link mapping elements exchanged in association request frames and association response frames between the non-AP MLD and the AP MLD; or a default mapping mode in which a TID is mapped to all links in the plurality of links in both the downlink and uplink.

[0207] Example process 1600 may be performed by a non-AP MLD.

[0208] like Figure 16 As shown, at step 1610 , process 1600 may include transmitting a frame for a first TID on a first link in a first set of links according to a TID-to-link mapping.

[0209] In an embodiment, the frame of the first TID includes a frame carrying one or more MSDUs or A-MSDUs of the first TID.

[0210] At step 1620 , process 1600 may include determining a buffer status for the first TID.

[0211] In step 1630 , process 1600 may include transmitting a BSR frame indicating a buffer status for the first TID on any link of the plurality of links, regardless of / regardless of the TID-to-link mapping.

[0212] In an embodiment, the link on which the BSR frame is transmitted is an enabled link, ie, a link that has at least one TID mapped thereto according to the TID-to-link mapping.

[0213] In an embodiment, the link on which the BSR frame is transmitted belongs to a first group of links among the plurality of links.

[0214] In an embodiment, the link on which the BSR frame is transmitted belongs to a second group of links in the plurality of links.

[0215] In an embodiment, the link on which the BSR frame is transmitted is the link to which the first TID is not mapped in the TID-to-link mapping.

[0216] In an embodiment, the link on which the BSR frame is transmitted is a disabled link, ie, a link that has no TID mapped thereto according to the TID-to-link mapping.

[0217] In an embodiment, the BSR frame includes a QoS null frame indicating the first TID and queue size information for the first TID.

[0218] In an embodiment, the BSR frame includes: a QoS Null frame including a QoS Control field therein; or a QoS Null frame including a QoS Control field and a BSR Control subfield therein.

[0219] In an embodiment, the QoS control field includes at least one of: a TID subfield, wherein the TID subfield identifies a traffic class (TC) or traffic stream (TS) for which a transmission opportunity (TXOP) is being requested; and a queue size subfield, wherein the queue size subfield indicates a total size in octets of MSDUs or A-MSDUs having a TID equal to the value of the TID subfield and buffered at the non-AP MLD.

[0220] In an embodiment, the BSR Control subfield includes at least one of the following: an Access Category Index (ACI) bitmap subfield; an Incremental TID subfield; an ACI High subfield; a Scaling Factor subfield; a Queue Size High subfield; and a Queue Size Full subfield. The ACI Bitmap subfield indicates at least one Access Category (AC) for which buffer status is reported in the BSR frame. The Incremental 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 of the Queue Size High and Queue Size Full subfields in units of SF octets. The Queue Size High subfield indicates the amount of buffered traffic in units of SF for the AC identified by the ACI High subfield. The Queue Size Full subfield indicates the amount of buffered traffic in units of SF for at least one AC identified by the ACI Bitmap subfield.

[0221] In an embodiment, transmitting the BSR frame in step 1630 includes transmitting the BSR frame in a TB PPDU or a non-TB PPDU.

[0222] In an embodiment, transmitting 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 transmitted in a TB PPDU.

[0223] In an embodiment, transmitting the BSR frame in step 1630 includes performing ECDA-based transmission. EDCA-based transmission may include transmitting a non-TB PPDU.

[0224] In an embodiment, process 1600 may optionally include steps 1640 and 1650 .

[0225] At step 1640, 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 the link to which the first TID in the TID-to-link mapping is mapped. The trigger frame may be a basic trigger frame or a MU-RTS TXS trigger frame.

[0226] In step 1650 , the non-AP MLD that received the trigger frame in step 1640 may transmit a frame carrying the MSDU or A-MSDU of the first TID on the link on which the trigger frame was received.

[0227] Figure 17 An example process 1700 for receiving buffer status according to an embodiment of the present disclosure is shown. Example process 1700 can be performed in an example environment including an AP MLD and a non-AP MLD. The non-AP MLD and the AP MLD can be communicatively coupled by a plurality of links and can be associated with a TID-to-link mapping. The TID-to-link mapping can include a first mapping of a first TID in an uplink to a first set of links in the plurality of links and a second mapping of a second TID in the uplink to a second set of links in the plurality of links. In an embodiment, the TID-to-link mapping is based on: TID-to-link mapping elements exchanged in association request frames and association response frames between the non-AP MLD and the AP MLD; or a default mapping mode in which a TID is mapped to all links in the plurality of links in both the downlink and uplink.

[0228] Example process 1700 may be performed by an AP MLD.

[0229] like Figure 17 As shown, in step 1710, process 1700 may include receiving a frame for a first TID from a non-AP MLD on a first link in a first set of links according to a TID-to-link mapping. The first frame may carry a MAC service data unit (MSDU) or an aggregated MSDU (A-MSDU) for the first TID.

[0230] In step 1720 , process 1700 may include receiving a buffer status report (BSR) frame for the first TID on any link of the plurality of links, regardless of / regardless of the TID-to-link mapping.

[0231] In an embodiment, the link on which the BSR frame is received is an enabled link, ie, a link that has at least one TID mapped to it according to the TID-to-link mapping.

[0232] In an embodiment, the link on which the BSR frame is received belongs to a first group of links among the plurality of links.

[0233] In an embodiment, the link on which the BSR frame is received belongs to a second group of links in the plurality of links.

[0234] In an embodiment, the link on which the BSR frame is received is a link to which the first TID is not mapped in the TID-to-link mapping.

[0235] In an embodiment, the link on which the BSR frame is received is a disabled link, ie, a link that has no TID mapped to it according to the TID-to-link mapping.

[0236] In an embodiment, the BSR frame includes a QoS null frame indicating the first TID and queue size information for the first TID.

[0237] In an embodiment, the BSR frame includes: a QoS Null frame including a QoS Control field therein; or a QoS Null frame including a QoS Control field and a BSR Control subfield therein.

[0238] In an embodiment, the QoS control field includes at least one of: a TID subfield, wherein the TID subfield identifies a traffic class (TC) or traffic stream (TS) for which a transmission opportunity (TXOP) is being requested; and a queue size subfield, wherein the queue size subfield indicates a total size in octets of MSDUs or A-MSDUs having a TID equal to the value of the TID subfield and buffered at the non-AP MLD.

[0239] In an embodiment, the BSR Control subfield includes at least one of the following: an Access Category Index (ACI) bitmap subfield; an Incremental TID subfield; an ACI High subfield; a Scaling Factor subfield; a Queue Size High subfield; and a Queue Size Full subfield. The ACI Bitmap subfield indicates at least one Access Category (AC) for which buffer status is reported in the BSR frame. The Incremental 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 of the Queue Size High and Queue Size Full subfields in units of SF octets. The Queue Size High subfield indicates the amount of buffered traffic in units of SF for the AC identified by the ACI High subfield. The Queue Size Full subfield indicates the amount of buffered traffic in units of SF for at least one AC identified by the ACI Bitmap subfield.

[0240] In an embodiment, receiving the BSR frame in step 1720 includes receiving the BSR frame in a TB PPDU or a non-TB PPDU.

[0241] In an embodiment, receiving the BSR frame is in response to a trigger frame sent by the AP MLD. The trigger frame may include a BSRP trigger frame or a basic trigger frame.

[0242] In an embodiment, process 1700 may optionally include steps 1730 and 1740 .

[0243] At step 1730, process 1700 may include transmitting a trigger frame in response to the BSR on the 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.

[0244] At 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 was transmitted.

[0245] In an example embodiment, the non-AP MLD may transmit a frame to the AP MLD based on a TID-to-link mapping, wherein the TID-to-link mapping indicates a mapping of a first TID to a first set of links and a mapping of a second TID to a second set of links. The non-AP MLD may transmit a buffer status report (BSR) frame indicating a buffer status of the first TID to the AP MLD on any link, regardless of the TID-to-link mapping.

[0246] In an example embodiment, a non-AP MLD and an 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, wherein the TID-to-link mapping may include a first mapping of a first TID in an uplink to a first set of links in the multiple links and a second mapping of a second TID in the uplink to a second set of links in the multiple links. The non-AP MLD may transmit a frame carrying an MSDU or A-MSDU for the first TID to the AP MLD on a first link in the first set of links. The non-AP MLD may determine a buffer status for the first TID. The non-AP MLD may transmit a BSR frame (e.g., a QoS NULL frame indicating the first TID and including queue size information for the first TID) indicating the buffer status for the first TID on any link in the multiple links, regardless of the TID-to-link mapping.

[0247] In an example embodiment, regardless of the negotiated TID-to-link mapping, transmitting a BSR frame on any of the multiple links can reduce the latency for the AP MLD to obtain the buffer status of the non-AP MLD. Furthermore, the AP MLD can reduce signaling overhead by not transmitting a trigger frame on every enabled link to poll for buffer status reports. The AP MLD can obtain the accurate buffer status of the non-AP MLD on time by receiving a PPDU containing a buffer status report frame.

[0248] In an example embodiment, a BSR frame may be transmitted based on different rules depending on which PPDU carries the BSR frame when a TID-to-link mapping has been negotiated. In an example 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 a plurality of links, regardless of the TID-to-link mapping, wherein the TB PPDU is transmitted by a non-AP MLD in response to a trigger frame (e.g., a buffer status report poll (BSRP) trigger frame, a basic trigger frame, etc.) sent by an AP MLD. In another example 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.

[0249] In an example embodiment, when TID-to-link mapping has been negotiated, transmission of a BSR frame in a non-TB PPDU may follow the TID-to-link mapping rules, and the non-AP MLD may have the same embodiment for transmitting frames with TIDs using EDCA channel access. In an example embodiment, transmitting a BSR frame in a TB PPDU for any TID on any link among multiple links regardless of the TID-to-link mapping may provide low latency and more accurate BSR to the AP MLD by the AP MLD transmitting a trigger frame to the non-AP MLD when the AP MLD needs to obtain BSR information from the non-AP MLD.

[0250] Figure 18 An example process 1800 is shown, according to an embodiment. Example process 1800 may be performed 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 multiple links and may be associated with a TID-to-link mapping. The TID-to-link mapping may include mapping TIDs in an uplink and / or downlink to a first set of links in the multiple links. Example process 1800 may be performed by the non-AP MLD.

[0251] like Figure 18 As shown, process 1800 may begin with optional step 1802, which includes transmitting a frame for the TID to the AP MLD on a first link in a first set of links to which the TID is mapped in a TID-to-link mapping. In an embodiment, the frame for the TID includes an MSDU or A-MSDU for the TID.

[0252] In step 1804, process 1800 includes receiving a trigger frame from the AP MLD on a second link to which the TID is not mapped in the TID-to-link mapping. In an embodiment, the trigger frame comprises a BSRP trigger frame or a basic trigger frame.

[0253] In step 1806, process 1800 includes transmitting, in response to the trigger frame, a QoS null frame including a TID on the second link to the AP MLD. In one embodiment, the second link is an enabled link to which at least one TID is mapped according to the TID-to-link mapping. In another embodiment, the second link is a disabled link to which no TID is mapped according to the TID-to-link mapping. In one embodiment, the QoS null frame includes a BSR for the TID. In another embodiment, the QoS null frame also includes a BSR for another TID mapped to the second link.

[0254] In an embodiment, the QoS Null frame includes a QoS Control field of a BSR including a TID. In an embodiment, the QoS Control field includes at least one of: a TID subfield identifying the traffic class (TC) or traffic stream (TS) for which a transmission opportunity (TXOP) is being requested; and a Queue Size subfield indicating the total size in octets of MSDUs or A-MSDUs having a TID equal to the value of the TID subfield and buffered at the non-AP MLD. In another embodiment, the QoS Null frame includes a BSR Control subfield of a BSR including a TID.

[0255] In an embodiment, process 1800 may also include, prior to step 1802 , receiving, from the AP MLD, an association frame including a TID-to-link mapping that maps the TID to the first set of links.

[0256] In an embodiment, process 1800 may further include: receiving a trigger frame from the AP MLD on the first link 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 transmitting a frame including a QoS data frame for the TID to the AP MLD in response to the trigger frame.

[0257] Figure 19 An example process 1900 is shown, according to an embodiment. Example process 1900 may be performed 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 multiple links and may be associated with a TID-to-link mapping. The TID-to-link mapping may include mapping TIDs in an uplink and / or downlink to a first set of links in the multiple links. Example process 1900 may be performed by the AP MLD.

[0258] like Figure 19As shown, process 1900 may begin with optional step 1902, which includes receiving a frame for the TID from a non-AP MLD on a first link in the set of links to which the TID is mapped in the TID-to-link mapping. In an embodiment, the frame for the TID includes an MSDU or A-MSDU for the TID.

[0259] At step 1904, process 1900 includes transmitting a trigger frame to the non-AP MLD on a second link to which the TID is not mapped in the TID-to-link mapping. In an embodiment, the trigger frame comprises a BSRP trigger frame or a basic trigger frame.

[0260] At step 1906, process 1900 includes receiving, in response to the trigger frame, a QoS null frame including a TID from a non-AP MLD on a second link. In one embodiment, the second link is an enabled link to which at least one TID is mapped according to a TID-to-link mapping. In another embodiment, the second link is a disabled link to which no TID is 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 also includes a BSR for another TID mapped to the second link.

[0261] In an embodiment, the QoS Null frame includes a QoS Control field of the BSR including a TID. In an embodiment, the QoS Control field includes at least one of: a TID subfield identifying the TC or TS for which a TXOP is being requested; and a Queue Size subfield indicating the total size, expressed in octets, of MSDUs or A-MSDUs having a TID equal to the value of the TID subfield and buffered at the non-AP MLD. In another embodiment, the QoS Null frame includes a BSR Control subfield of the BSR including the TID.

[0262] In an embodiment, process 1800 may also include, prior to step 1902, transmitting to the non-AP MLD an association frame including a TID-to-link mapping that maps the TID to the first set of links.

[0263] In an embodiment, process 1900 may further include: transmitting a trigger frame to the non-AP MLD on the first link 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.

[0264] In an example embodiment, a non-AP MLD may receive a trigger frame from an AP MLD on a first link among 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 a TID to the AP MLD on a second link among the multiple links, regardless of whether the TID is mapped to the second link in a 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.

[0265] In another example embodiment, the AP MLD may transmit a trigger frame to the non-AP MLD on a first link among multiple links between the AP MLD and the non-AP MLD. In response to the trigger frame, the AP MLD may receive a QoS null frame including a TID from the non-AP MLD on a second link among 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.

Claims

1. A method comprising: receiving, by a non-access point non-AP multi-link device MLD, an association frame from an access point AP MLD, the association frame including a TID-to-link mapping that maps a traffic identifier TID to a first link; receiving, by the non-AP MLD, a first trigger frame from the AP MLD on a second link to which the TID is not mapped; as well as In response to the first trigger frame, the non-AP MLD transmits a Quality of Service (QoS) null frame including the TID to the AP MLD on the second link. 2 . The method according to claim 1 , wherein the first trigger frame comprises a buffer status report polling (BSRP) trigger frame or a basic trigger frame.

3. The method of claim 1 , wherein the second link is an enabled link having at least one TID mapped to it according to the TID-to-link mapping. 4 . The method according to claim 1 , wherein the QoS null frame comprises a buffer status report (BSR) of the TID. 5 . The method of claim 4 , wherein the QoS null frame includes a BSR mapped to another TID of the second link. 6 . The method of claim 4 , wherein the QoS null frame includes a QoS control field of the BSR including the TID. 7 . The method of claim 4 , wherein the QoS null frame includes a BSR control subfield of the BSR including the TID.

8. The method according to claim 1, further comprising: In response to the QoS null frame, the non-AP MLD receives a second trigger frame from the AP MLD on the first link, the second trigger frame allocating uplink resources on the first link to the non-AP MLD for the TID; as well as In response to the second trigger frame, the non-AP MLD transmits a frame including a QoS data frame for the TID to the AP MLD.

9. A method comprising: Transmitting, by the access point AP multi-link device MLD, an association frame to the non-access point non-AP MLD, the association frame including a TID-to-link mapping that maps a traffic identifier TID to the first link; The AP MLD transmits a first trigger frame to the non-AP MLD on a second link to which the TID is not mapped; as well as In response to the first trigger frame, the AP MLD receives a Quality of Service (QoS) null frame including the TID from the non-AP MLD on the second link. 10 . The method according to claim 9 , wherein the first trigger frame comprises a buffer status report polling (BSRP) trigger frame or a basic trigger frame.

11. The method of claim 9, wherein the second link is an enabled link having at least one TID mapped to it according to the TID-to-link mapping.

12. The method of claim 9, wherein the QoS null frame comprises a buffer status report (BSR) of the TID.

13. The method according to claim 9, further comprising: In response to the QoS null frame, the AP MLD transmits a second trigger frame to the non-AP MLD on the first link, wherein the second trigger frame allocates uplink resources on the first link to the non-AP MLD for the TID; as well as In response to the second trigger frame, the AP MLD receives a frame including a QoS data frame for the TID from the non-AP MLD.

14. A multi-link device (MLD), comprising: one or more processors; as well as A memory storing instructions that, when executed by the one or more processors of the MLD, cause the MLD to perform the method according to any one of claims 1 to 13. 15 . A non-transitory computer-readable medium comprising instructions which, when executed by one or more processors of a multi-link device (MLD), cause the MLD to perform the method according to claim 1 .

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