Adjusting trigger frame duration for multi-access point transmission

Abstract

In one embodiment, a first access point (AP) receives a first frame from a second AP indicating the number of stations (STAs) for an uplink (UL) transmission to the second AP. The first AP sends a second frame to the second AP indicating the allocated time of the transmit opportunity (TXOP) acquired by the first AP, the identifier of the second AP, and a period for a downlink physical layer protocol data unit (DL PPDU) containing a trigger frame for the STA within the allocated time, the period being based on the number of STAs. In another embodiment, the first AP sends a first frame to the second AP indicating the number of STAs. The first AP receives a second frame from the second AP indicating a time period for the DL PPDU containing a trigger frame for the STAs.

Description

TECHNICAL FIELD

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 543,121 filed on October 9, 2023, the entire contents of which are incorporated herein by reference. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0002] Several examples of various embodiments of the present disclosure are described herein with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] [Figure 1] Illustrates an exemplary wireless communication network in which embodiments of the present disclosure may be implemented. [Figure 2] FIG. 2 is a block diagram illustrating an exemplary implementation of a station (STA) and an access point (AP). [Figure 3] Illustrates an example of a medium access control (MAC) frame format. [Figure 4] Illustrates an example of a quality of service (QoS) null frame indicating buffer status information. [Figure 5] Illustrates an exemplary format of a physical layer (PHY) protocol data unit (PPDU). [Figure 6] Illustrates an example of a multi-user transmission request (MU-RTS) trigger frame that may be used in a triggered transmission opportunity (TXOP) sharing (TXS) procedure. [Figure 7] Illustrates an example of a TXS procedure (Mode=1). [Figure 8] Illustrates an example of a TXS procedure (Mode=2). [Figure 9] Illustrates an exemplary multi-AP network. [Figure 10] Illustrates cooperative orthogonal frequency division multiple access (C-OFDMA). [Figure 11] This is an example illustrating the TXS procedure between APs. [Figure 12] This document illustrates exemplary Physical Layer Protocol Data Units (PPDUs) that may be used for Downlink (DL) PPDUs or Uplink (UL) PPDUs. [Figure 13] Figure 11 illustrates an example of a problem that may arise in the AP-to-TXS procedure. [Figure 14] An example of an AP-to-TXS procedure according to an embodiment will be illustrated. [Figure 15] An example of an AP-to-TXS procedure according to another embodiment is illustrated below. [Figure 16] An exemplary aggregated control (A-control) field that may be used in the embodiment is illustrated below. [Figure 17] Exemplary information elements that may be used in the embodiment are illustrated below. [Figure 18] An exemplary process is illustrated by an embodiment. [Figure 19] Another exemplary process, based on an embodiment, is illustrated. [Figure 20] Another exemplary process, based on an embodiment, is illustrated. [Figure 21] Another exemplary process, based on an embodiment, is illustrated. [Modes for carrying out the invention]

[0004] This disclosure presents various embodiments as examples of how the disclosed techniques may be implemented and / or how the disclosed technologies may be practiced in environments and scenarios. Those skilled in the art will see that various modifications of form and detail can be made without departing from the scope. After reading the specification, methods for implementing alternative embodiments will be apparent to those skilled in the art. These embodiments are not limited by any of the exemplary embodiments described. Embodiments of this disclosure are described with reference to the accompanying drawings. Limitations, features, and / or elements from the exemplary embodiments disclosed can be combined to create further embodiments within the scope of this disclosure. Any figures emphasizing functionality and benefits are presented for illustrative purposes only. The disclosed architecture is sufficiently flexible and configurable to be used in ways other than those shown. For example, any actions listed in any flowchart can be rearranged in some embodiments or used only at will.

[0005] The embodiments may be configured to operate as needed. The disclosed mechanisms may be implemented, for example, in stations, access points, wireless environments, networks, combinations thereof, and / or similar, when certain criteria are met. Illustrative criteria may be based, for example, on wireless devices, or network node configuration, traffic load, initial system setup, packet size, traffic characteristics, combinations thereof, and / or similar, at least in part. Various exemplary embodiments may be applied when one or more criteria are met. Therefore, it may be possible to implement exemplary embodiments that selectively implement the disclosed protocols.

[0006] In this specification, “a” and “an,” and similar phrases, should be interpreted as “at least one” and “one or more.” Similarly, any term ending in the suffix “(s)” should be interpreted as “at least one” and “one or more.” In this disclosure, the term “may” should be interpreted as “for example, may be.” In other words, the phrase “may” indicates that the phrase following the term “may” is one embodiment of several preferred possibilities, which may or may not be adopted by one or more of the various embodiments. As used herein, the terms “comprises” and “consists of” enumerate one or more components of the element described. The term “comprises” is interchangeable with “includes” and does not exclude unlisted components that are included in the element described. In contrast, “consists of” provides a complete enumeration of one or more components of the element described. As used herein, the term “based on” may be interpreted as “at least partially based” rather than, for example, “based solely on.” As used herein, the term “and / or” represents any possible combination of the enumerated elements. For example, “A, B, and / or C” may represent A, B, C, A and B, A and C, B and C, or A, B, and C.

[0007] If A and B are a set and all elements of A are elements of B, then A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, possible subsets of B = {STA1, STA2} are {STA1}, {STA2}, and {STA1, STA2}. The phrase "based on" (or equivalently "at least based on") indicates that the phrase following the term "based on" is one embodiment of many preferred possibilities, which may or may not be adopted in one or more of the various embodiments. The phrase "in response to" (or equivalently "at least in response to") indicates that the phrase following the phrase "in response to" is one embodiment of many preferred possibilities, which may or may not be adopted in one or more of the various embodiments. The phrase "according to" (or equivalently "at least in response to") indicates that the phrase following the phrase "according to" is one embodiment of many preferred possibilities, which may or may not be adopted in one or more of the various embodiments. The phrase “adopt / use” (or equivalently “at least adopt / use”) indicates that the phrase following “adopt / use” is one of many preferred possibilities, in which one or more of the various embodiments may or may not be adopted.

[0008] The term "configured" can relate to the capabilities of a device, whether the device is operational or non-operational. "Configured" can refer to specific settings of a device that affect its operational characteristics, whether the device is operational or non-operational. In other words, hardware, software, firmware, registers, memory values, and / or similar can be "configured" within a device, whether the device is operational or non-operational, to provide the device with specific characteristics. Terms such as "a control message to cause a device to..." can mean that, whether the device is operational or non-operational, a control message may have parameters that can be used to configure a specific characteristic in the device or to perform a specific action that the device is.

[0009] In this disclosure, a parameter (or equivalently referred to as a field, or information element: IE) may contain one or more information objects, and an information object may contain one or more other objects. For example, parameter (IE) N may contain parameter (IE) M, parameter (IE) M may contain parameter (IE) K, and parameter (IE) K may contain parameter (information element) J. Then, for example, N may contain K, and N may contain J. In exemplary embodiments, when one or more messages / frames contain multiple parameters, it means that any parameter among the multiple parameters is included in at least one of the one or more messages / frames, but does not have to be included in each of the one or more messages / frames.

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

[0011] Many of the elements described in the disclosed embodiments may be implemented as modules. Here, a module is defined as an element that performs a defined function and has a defined interface to other elements. The modules described in the present disclosure may be implemented in hardware, software combined with hardware, firmware, wetware (e.g., hardware with biological elements), or a combination thereof, which may be behaviorally equivalent. For example, a module may be implemented as a software routine written in a computer language configured to be executed on a hardware machine (such as C, C++, Fortran, Java®, Basic, Matlab®, or the like) or a modeling / simulation program such as Simulink, Stateflow, GNU Octave, or LabVIEW MathScript. It may also be possible to implement the 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, C++, or the like. FPGAs, ASICs, and CPLDs are often programmed using a hardware description language (HDL) such as VHSIC Hardware Description Language (VHDL) or Verilog, which configures connections between internal hardware modules with less functionality in the programmable device. The above techniques are often used in combination to achieve the results of the functional modules.

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

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

[0014] BSSs 110-1 and 110-2 each include a set of an access point (AP, or AP STA) 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, as well as STAs 106-2 and 106-3. The AP and the at least one STA within a BSS perform an association procedure to communicate with each other.

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

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

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

[0018] For example, in Figure 1, STA106-4, 106-5, and 106-6 may be configured to form a first IBSS112-1. Similarly, STA106-7 and 106-8 may be configured to form a second IBSS112-2. Since IBSS does not include APs, it does not include a centralized management entity. Rather, the STAs within IBSS are managed in a decentralized manner. The STAs that make up IBSS may be fixed or mobile.

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

[0020] A Physical Layer (PHY) Protocol Data Unit (PPDU) can be a composite structure containing a PHY preamble and a payload in the form of a PHY Service Data Unit (PSDU). For example, a PSDU may include a PHY preamble, a header, and / or one or more MAC Protocol Data Units (MPDUs). Information provided in the PHY preamble can be used by a receiving device to decode subsequent data within the PSDU. When a PPDU is transmitted over bonded channels (channels formed through channel bonding), the preamble fields may be duplicated and transmitted in each of the multiple component channels. A PHY preamble may contain both a legacy portion (or "legacy preamble") and a non-legacy portion (or "non-legacy preamble"). The legacy preamble may be used for packet detection, automatic gain control, and channel estimation, among other applications. The legacy preamble may also generally be used to maintain compatibility with legacy devices. The format, coding, and information provided for the non-legacy portion of the preamble are based on the specific IEEE 802.11 protocol used to transmit the payload.

[0021] A frequency band may include one or more subbands or frequency channels. For example, a PPDU conforming to the IEEE 802.11n, 802.11ac, 802.11ax, and / or 802.11be revised standards may be transmitted across the 2.4 GHz, 5 GHz, and / or 6 GHz bands, each of which may be divided into multiple 20 MHz channels. A PPDU may be transmitted over a physical channel having a minimum bandwidth of 20 MHz. Larger channels may be formed through channel bonding. For example, a PPDU may be transmitted over a physical channel having a bandwidth of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding multiple 20 MHz channels together.

[0022] Figure 2 is a block diagram illustrating exemplary implementations of STA210 and AP260. As shown in Figure 2, STA210 may include at least one processor 220, memory 230, and at least one transceiver 240. AP260 may include at least one processor 270, memory 280, and at least one transceiver 290. Processors 220 / 270 may be operably connected to memory 230 / 280 and / or transceivers 240 / 290.

[0023] Processor 220 / 270 may implement the functions of the PHY layer, MAC layer, and / or logic link control (LLC) layer of the corresponding device (STA210 or AP260). Processor 220 / 270 may include one or more processors and / or one or more controllers. One or more processors and / or one or more controllers may include, for example, a general-purpose processor, a digital signal processor (DSP), a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a logic circuit, or a chipset.

[0024] Memory 230 / 280 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage units. Memory 230 / 280 may include one or more non-temporary computer-readable media. Memory 230 / 280 may store computer program instructions or code that can be executed by the processor 220 / 270 to perform one or more of the operations / embodiments considered in this application. Memory 230 / 280 may be implemented (or positioned) within or outside the processor 220 / 270. Memory 230 / 280 may be operably connected to the processor 220 / 270 by various means known in the art.

[0025] Transceivers 240 / 290 may be configured to transmit / receive radio signals. In embodiments, transceivers 240 / 290 may implement the PHY layer of the corresponding device (STA210 or AP260). In embodiments, STA210 and / or AP260 may be multilink devices (MLDs), i.e., devices capable of operating on multiple links as defined by the IEEE 802.11 standard. Thus, STA210 and / or AP260 may each implement multiple PHY layers. Multiple PHY layers may be implemented using one or more transceivers 240 / 290.

[0026] The Target Wake Time (TWT), a feature introduced in the IEEE 802.11ah standard, allows STAs to manage BSS activity by scheduling STAs to operate at different times to reduce contention. TWT can allow STAs to reduce the amount of time they need to wake up by utilizing power management modes. TWTs can be individual TWTs or broadcast TWTs. Individual TWTs are subject to negotiated TWT agreements between STAs. Broadcast TWTs are provided to STAs by APs based on scheduling sets.

[0027] In an individual TWT, the STA requesting a TWT match is called the TWT requesting STA. A TWT requesting STA may be, for example, a non-AP STA. The STA responding to the request is called the TWT responding STA. A TWT responding STA may be, for example, an AP. The TWT requesting STA is allocated a specific time to wake up and exchange frames with the TWT responding STA. The TWT requesting STA may communicate wake scheduling information to the TWT responding STA. The TWT responding STA may send a TWT value to the TWT requesting STA when a TWT match is established between them.

[0028] When an explicit TWT is used, the TWT requesting STA may wake up and perform a frame exchange. The TWT requesting STA may receive the next TWT information in the response from the TWT response STA. When an implicit TWT is used, the TWT requesting STA may calculate the next TWT by adding a fixed value to the current TWT value.

[0029] The TWT value of an implicit TWT may be periodic. A TWT request STA operating with an implicit TWT match may determine the start time of the next TWT service period (TWT SP) by adding the value of the TWT wake interval associated with the TWT match to the start time value of the current TWT SP. A TWT response STA may contain a series of TWT SP start times corresponding to a single TWT flow identifier of the implicit TWT match in the target wake time field of the TWT element. A TWT element may contain the value of "Approved TWT" in the TWT setup command field. The start time of a TWT SP series may indicate the start time of the first TWT SP in the series. The start time of a subsequent TWT SP may be determined by adding the value of the TWT wake interval to the start time of the current TWT SP. In an embodiment, a TWT request STA waking up an implicit TWT SP may enter a dose state after the TWT SP has elapsed, or after receiving an End of Service Period (EOSP) field equal to 1 from the TWT response STA, whichever occurs first.

[0030] A TWT session can be negotiated between an AP and an STA. A TWT session can constitute a TWT SP for DL ​​and UL traffic between the AP and the STA. Expected traffic can be limited within the negotiated SP. A TWT SP can be initiated at a specific time. A TWT SP can run for the duration of the SP. A TWT SP can be repeated at each SP interval.

[0031] Figure 3 illustrates an example of MAC frame format 300. During operation, the STA may construct a subset of MAC frames for transmission and decode a subset of received MAC frames during verification. The specific subset of frames that the STA may construct and / or decode may be determined by the capabilities supported by the STA. The STA may verify received MAC frames using a frame check sequence (FCS) contained within the frame and may interpret certain fields from the MAC header of all frames.

[0032] As shown in Figure 3, a MAC frame includes a MAC header, a variable-length frame body, and a frame check sequence (FCS).

[0033] The MAC header includes a frame control field, an optional duration / ID field, an address field, an optional sequence control field, an optional QoS control field, and an optional HT control field.

[0034] The frame control field includes subfields for protocol version, type, subtype, To DS, From DS, additional fragments, retry, power management, additional data, protected frame, and +HTC.

[0035] The protocol version subfield remains constant in size and placement across all revisions of the IEEE 802.11 standard. The value of the protocol version subfield is 0 for MAC frames.

[0036] The subfields of the type and subtype identify the function of the MAC frame. There are three frame types: control, data, and management. Each frame type has several defined subtypes. The bits in the subtype subfield are used to indicate a specific modification of the basic data frame (subtype 0). For example, in a data frame, the most significant bit (MSB) of the subtype subfield, bit 7 (B7) of the frame control field, is defined as the QoS subfield. When the QoS subfield is set to 1, it indicates a QoS subtype data frame, which is a data frame that includes the QoS control field in its MAC header. The second MSB of the subtype field, bit 6 (B6) of the frame control field, when set to 1 in a data subtype, indicates a data frame that does not include the frame body field.

[0037] The "To DS" subfield indicates whether the data frame is intended for a distribution system (DS). The "From DS" subfield indicates whether the data frame originated from a DS.

[0038] The Additional Fragment subfield is set to 1 in all data frames or management frames that have another subsequent fragment in the MAC Service Data Unit (MSDU) or MAC Management Protocol Data Unit (MMPDU) carried by the MAC frame. It is set to 0 in all other frames where the Additional Fragment subfield exists.

[0039] The retry subfield is set to 1 for any data or management frame that is a retransmission of a previous frame. It is set to 0 for all other frames in which the retry subfield exists. The receiving STA uses this instruction to assist in the process of eliminating duplicate frames. These rules do not apply to frames sent by the STA based on a block agreement.

[0040] The power management subfield is used to indicate the power management mode of the STA.

[0041] The Additional Data subfield indicates to the STA in Power Saving (PS) mode that a bufferable unit (BU) is being buffered for its STA by the AP. The Additional Data subfield is valid in individually addressed data or management frames sent by the AP to the STA in PS mode. The Additional Data subfield is set to 1 to indicate to the STA that at least one additional buffered BU exists.

[0042] The protected frame subfield is set to 1 if the frame body field contains information processed by the cryptographic encapsulation algorithm.

[0043] The +HTC subfield indicates that the MAC frame contains the HT control field.

[0044] The duration / ID field in the MAC header contains various values ​​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-saving polling (PS-Poll) subtype, the duration / ID field carries the association identifier (AID) of the STA that sent the frame in 14 least significant bits (LSBs), and both most significant bits (MSBs) are set to 1. In other frames transmitted by the STA, 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 tells the STA how much time it must withhold access to the shared medium.

[0045] The MAC frame format can contain up to four address fields. These fields are used to identify the Basic Service Set Identifier (BSSID), Source Address (SA), Destination Address (DA), Transmitter Address (TA), and Receiver Address (RA). A particular frame may not contain all of the address fields. The use of a particular address field can be specified by its relative position within the MAC header, regardless of the type of address present in that field. Specifically, address field 1 always identifies the intended receiver of the frame, and address field 2, if present, always identifies the transmitter of the frame.

[0046] 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 present in an aggregated MSDU (A-MSDU)) or the A-MSDU. The sequence number subfield in a management frame indicates the sequence number of the frame. The fragment number subfield indicates the number of fragments in the MSDU or MMPDU. The fragment number is set to 0 for the first fragment of an MSDU or MMPDU, or for only the first fragment, and increments by 1 for each subsequent fragment of that MSDU or MMPDU. The fragment number is set to 0 in MAC protocol data units (MPDUs) containing an A-MSDU, or in MPDUs containing unfragmented MSDUs or MMPDUs. The fragment number remains constant for all retransmissions of the fragment.

[0047] The QoS control field identifies the traffic category (TC) or traffic stream (TS) to which the MAC frame belongs. The QoS control field may also indicate various other QoS-related, A-MSDU-related, and mesh-related information about the frame. This information may vary depending on the frame type, frame subtype, and transmitting STA type. The QoS control field is present in all data frames where the QoS subfield of the subtype's subfield is equal to 1.

[0048] The HT control field exists in QoS data, QoS nulls, and management frames, as determined by the +HTC subfield of the frame control field.

[0049] The frame body field is a variable-length field containing information specific to each frame type and subtype. This may include one or more MSDUs or MMPDUs. The minimum length of the frame body is 0 octets.

[0050] The FCS field contains a 32-bit cyclic redundancy check (CRC) code. The FCS field value is calculated across all fields in the MAC header and frame body.

[0051] Figure 4 illustrates an example 400 of a Quality of Service (QoS) null frame showing buffer status information. A QoS null frame refers to a QoS data frame having an empty frame body. A QoS null frame includes a QoS control field and an optional HT control field which may contain a Buffer Status Report (BSR) control subfield. A QoS null frame showing buffer status information can be sent to an AP by the STA.

[0052] The QoS control fields may include a Traffic Identifier (TID) subfield, an ack policy indicator subfield, and a queue size subfield (or a subfield for the requested duration of the Transmit Opportunity (TXOP)).

[0053] The TID subfield identifies the TC or TS of the traffic for which the TXOP is being requested, through the setting of the requested TXOP duration or the queue size subfield. The encoding of the TID subfield depends on the access policy (for example, a tolerance of 0-7 for Extended Distributed Channel Access (EDCA) access policies to identify user priority for either TC or TS).

[0054] The ack policy indicator subfield, along with other information, identifies the acknowledgment policy followed when delivering the MPDU (e.g., normal ack, implicit block ack request, no ack, block ack, etc.).

[0055] The queue size subfield is an 8-bit field that indicates the amount of buffered traffic for a given TC or TS at the STA for transmission to the AP, identified by the receiver address of the frame containing the subfield. The queue size subfield is present in QoS null frames transmitted by the STA when bit 4 of the QoS control field is set to 1. The AP can use the information contained in the queue size subfield to determine the TXOP duration allocated to the STA or to determine the uplink (UL) resources allocated to the STA.

[0056] For non-high efficiency (non-HE) STAs, or for frames sent to them, the following rules may apply to the queue size value. - The queue size value is the approximate total size, rounded up to the nearest multiple of 256 octets, of all MSDUs and A-MSDUs buffered in the STA within the distribution queue used for MSDUs and A-MSDUs (excluding MSDUs or A-MSDUs included in the current QoS data frame) that have a TID value equal to the value shown in the TID subfield of the QoS control field, and expressed in units of 256 octets. - A queue size value of 0 is used only to indicate that there is no buffered traffic in the queue used for the specified TID. - The queue size value 254 is used for all sizes exceeding 64,768 octets. - A queue size value of 255 is used to indicate an unspecified or unknown size.

[0057] For frames sent to the HE AP by the HE STA, the following rules may apply to the queue size value:

[0058] The queue size value QS is the approximate total size in octets of all MSDUs and A-MSDUs buffered in the STA (including MSDUs or A-MSDUs contained in the same PSDU as the frame containing the queue size subfield) within the delivery queue, used for MSDUs and A-MSDUs that have a TID value equal to the value shown in the TID subfield of the QoS control field.

[0059] The queue size subfield includes a scaling factor subfield in bits B14-B15 of the QoS control field and an unscaled value UV in bits B8-B13 of the QoS control field. The scaling factor subfield provides the scaling factor on.

[0060] The STA obtains the queue size QS from the received QoS control field, which includes the scaling factor SF and the unscaled value UV, as follows: QS= If SF is equal to 0, then 16 × UV, If SF is equal to 1, then 1024 + 256 × UV, If SF is equal to 2, then 17 408 + 2048 × UV, If SF is equal to 3 and UV is less than 62, then 148 480 + 32 768 × UV, If SF is equal to 3 and UV is equal to 62, then >2 147 328, If SF is equal to 3 and UV is equal to 63, then it is unspecified or unknown.

[0061] The TXOP Requested Duration subfield, which may be included instead of the queue size subfield, indicates the duration in 32 microseconds (us) in which the transmitting STA determines the need for the next TXOP for the specified TID. The TXOP Requested Duration subfield is set to 0 to indicate that no TXOP is requested for the specified TID during the current service period (SP). The TXOP Requested Duration subfield is set to a non-zero value so that requested TXOP durations in the range of 32us to 8160us are indicated in 32us increments.

[0062] The HT control field may include a BSR control subfield that can contain buffer status information used for UL MU operation. The BSR control subfield may be formed from an Access Category Index (ACI) bitmap subfield, a Delta TID subfield, an ACI High subfield, a scaling factor subfield, a Queue Size High subfield, and the Queue Size Full subfield of the HT control field.

[0063] The ACI bitmap subfield indicates the access category for which the buffer status was reported (e.g., B0: Best Effort (AC_BE), B1: Background (AC_BK), B2: Video (AC_VI), B3: Audio (AC_VO), etc.). Each bit in the ACI bitmap subfield is set to 1 to indicate that the buffer status of the corresponding AC is included in all subfields of the queue size, and to 0 otherwise. However, if the ACI bitmap subfield is 0 and the delta TID subfield is 3, then the buffer status of all 8 TIDs is included.

[0064] The Delta TID subfield, along with the value of the ACI bitmap subfield, indicates the number of TIDs for which the STA is reporting buffer status.

[0065] The ACI high subfield indicates the ACI of the AC indicated by the queue size high subfield in the BSR. The mapping from ACI to AC is defined as the ACI value 0 mapping to AC_BE, the ACI value 1 mapping to AC_BK, the ACI value 2 mapping to AC_VI, and the ACI value 3 mapping to AC_VO.

[0066] The scaling factor subfield shows the unit SF of the queue size high subfield and the queue size all subfield as an octet.

[0067] The queue size high subfield indicates the amount of buffered traffic in SF octets for the AC identified by the ACI high subfield, which applies to the STA identified by the receiver address of the frame encompassing the BSR control subfield.

[0068] The queue size subfield indicates the amount of buffered traffic in SF octets for all Acs identified by the ACI bitmap subfield, and this applies to STAs identified by the receiving address of the frame, including the BSR control subfield.

[0069] The queue size values ​​in the queue size high subfield and queue size all subfield represent the total size of all MSDUs and A-MSDUs buffered in the STA (including MSDUs or A-MSDUs contained in the same PSDU as the frame containing the BSR control subfield) within the delivery queue, used for MSDUs and A-MSDUs associated with the ACs specified in the ACI high subfield and ACI bitmap subfield, respectively, and are rounded up to the nearest multiple of the SF octet.

[0070] A queue size value of 254 in both the queue size height and all queue size subfields indicates that the amount of buffered traffic is greater than 254 × SF octets. A queue size value of 255 in both the queue size height and all queue size subfields indicates that the amount of buffered traffic is unspecified or unknown. The queue size value of a QoS data frame containing fragments may remain constant even if the amount of traffic added to the queue changes as consecutive fragments are sent.

[0071] The MAC service provides peer entities with the ability to exchange MSDUs. To support this service, the local MAC uses the underlying PHY-level service to transmit MSDUs to the peer MAC entity. Such asynchronous MSDU transmission is performed without connection.

[0072] Figure 5 illustrates an exemplary format of a PPDU. As shown, a PPDU may include a PHY preamble, a PHY header, a PSDU, and tail bits and padding bits.

[0073] A PSDU may contain one or more MPDUs, such as a QoS data frame, MMPDU, MAC control frame, or QoS null frame. In the case of an MPDU carrying a QoS data frame, the frame body of the MPDU may contain an MSDU or A-MSDU.

[0074] By default, MSDU transmission is best-effort; that is, there is no guarantee that transmitted MSDUs will be delivered successfully. However, QoS equipment uses a Traffic Identifier (TID) to specify differentiated service for each MSDU.

[0075] STA can differentiate MSDU deliveries according to the designated traffic category (TC) or traffic stream (TS) of each MSDU. MAC sublayer entities determine user priority (UP) for an MSDU based on the TID value provided to the MSDU. QoS equipment supports eight UP values. The UP values ​​range from 0 to 7, forming the priority level, with 1 being the lowest value, 7 being the highest, and 0 corresponding to 2-3.

[0076] An MSDU with a specific UP is said to belong to the traffic category that has that UP. UPs can be provided directly by each MSDU in the UP parameter at the Media Access Control Service Access Point (MAC SAP). An aggregated MPDU (A-MPDU) may contain MPDUs with different TID values.

[0077] The STA can assist the AP in allocating UL MU resources by distributing Buffer Status Reports (BSRs). The STA may implicitly distribute a BSR within the QoS control field or BSR control subfield of any frame sent to the AP (an unsolicited BSR), or it may explicitly distribute a BSR within a frame sent to the AP in response to a BSRP trigger frame (a solicited BSR).

[0078] The buffer status reported in the QoS control field includes the queue size value for a given TID. The buffer status reported in the BSR control field includes the ACI bitmap, delta TID, high priority AC, and two queue sizes.

[0079] The STA may report the buffer status to the AP in the QoS control field for transmitted QoS null frames and QoS data frames, and in the BSR control subfield (if present) for transmitted QoS null frames, QoS data frames, and management frames, as defined below.

[0080] The STA may report the queue size for a given TID in the queue size subfield of the QoS control field of the transmitted QoS data frame or QoS null frame, and the STA may set the queue size subfield to 255 to indicate an unknown / unspecified queue size for that TID. The STA may aggregate multiple QoS data frames or QoS null frames within the A-MPDU to report the queue sizes for different TIDs.

[0081] If the AP indicates its support for receiving the BSR control subfield, the STA may report the buffer status in the BSR control subfield of the transmitted frame.

[0082] A high-efficiency (HE) STA may report the preferred queue size for an AC, indicated by the ACI high subfield, in the queue size high subfield of the BSR control subfield. The STA may set the queue size high subfield to 255 to indicate an unknown / unspecified queue size for that AC.

[0083] The HE STA may report the queue size of ACs, indicated by the ACI bitmap subfield, in the queue size all subfield of the BSR control subfield. The STA may set the queue size all subfield to 255 to indicate an unknown / unspecified BSR for those ACs.

[0084] Triggered TXOP Share (TXS) is a technique introduced in the IEEE 802.11be revision. TXS allows an AP to allocate the duration within an acquired TXOP to STAs in order to transmit one or more non-trigger-based (non-TB) PPDUs. In the TXS procedure, an AP may send a Multi-User Send Request (MU-RTS) trigger frame by setting the Triggered TXOP Share Mode subfield to a non-zero value. An MU-RTS trigger frame is a trigger frame for triggering CTS frames from multiple users. An MU-RTS trigger frame with the Triggered TXOP Share Mode subfield set to a non-zero value is called a MU-RTS TXS Trigger (MRTT) frame.

[0085] In the embodiment, if the triggered TXOP shared mode subfield is set to 1, the STA may transmit one or more non-TB PPDUs to the AP during the duration of the allocated time. In the embodiment, if the triggered TXOP shared mode subfield is set to 2, the STA may transmit one or more non-TB PPDUs to the AP or peer STA during the duration of the allocated time. The peer STA may be an STA that has a connection for peer-to-peer (P2P) communication or direct communication with the STA. In the embodiment, the direct wireless link is established according to the Tunnel Direct Link Setup (TDLS) protocol.

[0086] Figure 6 illustrates an exemplary MRTT frame 600 that may be used in the TXS procedure. As shown in Figure 6, the exemplary MRTT frame 600 may include a frame control field, a duration field, a receiver address (RA) field, a transmitter address (TA) field, a common information field, a user information list field, a padding field, and / or a frame check sequence (FCS) field.

[0087] In the embodiment, the common information field may be a high-efficiency (HE) variant common information field or an ultra-high-throughput (EHT) variant common information field. The EHT variant common information field may include one or more of the following subfields, as shown in Figure 6: trigger type, UL length, more TF, requested CS, UL BW, GI and HE / EHT-LTF type / triggered TXOP shared mode, number of HE / EHT-LTF symbols, LDPC additional symbol segment, AP Tx Power, pre-FEC padding factor, PE ambiguity, UL space reuse, HE / EHT P160, special user information field flags, EHT reservation, reservation, or trigger-dependent common information.

[0088] The trigger type subfield indicates that frame 600 is an MRTT frame.

[0089] The GI and HE / EHT-LTF type / triggered TXOP shared mode subfield may include a triggered TXOP shared mode subfield. In an embodiment, the triggered TXOP shared mode subfield may be set to a non-zero value (e.g., 1 or 2). In an embodiment, the triggered TXOP shared mode subfield may be set to 1. Thus, the triggered TXOP shared mode subfield may indicate that the STA indicated by the AID12 subfield of the user information field (user information list field) may send one or more non-TB PPDUs to the AP during the time indicated by the allocation duration subfield of the user information field. In another embodiment, the triggered TXOP shared mode subfield may be set to 2. Thus, the triggered TXOP shared mode subfield may indicate that the STA indicated by the AID12 subfield of the user information field (user information list field) may send one or more non-TB PPDUs to the AP or peer STA during the time indicated by the allocation duration subfield of the user information field. In this embodiment, the peer STA may be an STA having a connection for P2P communication or direct communication with another STA.

[0090] The user information list field may contain one or more user information fields. In the embodiment, the EHT variant user information field may contain one or more of the following subfields, as shown in Figure 6: AID12, RU allocation, allocation duration, reservation, or PS160.

[0091] The AID12 subfield may indicate an association identifier (AID) for the STA, which may use the time indicated by the allocation duration subfield.

[0092] The RU allocation subfield may indicate the location and size of the RU allocated to the STA indicated by the AID12 subfield.

[0093] The allocated duration subfield may indicate the time allocated by the AP by sending the MRTT frame 600. The allocated time may be a portion of the TXOP obtained by the AP. In an exemplary embodiment, the allocated duration subfield may indicate a first period.

[0094] Figure 7 illustrates an example 700 of the TXS procedure (mode=1). As shown in Figure 7, the TXS procedure may be initiated by AP710 and send an MRTT frame 720 to STA711. The MRTT frame 720 may allocate a portion of the TXOP acquired by AP710 to STA711 and may indicate a TXS mode equal to 1. Upon receiving the MRTT frame 720, STA711 may use the allocated time to send one or more non-TB PPDUs to AP710. One or more non-TB PPDUs may include data frames, control frames, administration frames, or action frames.

[0095] In the embodiment, the MRTT frame 720 may include a triggered TXOP shared mode subfield indicating TXS mode, and / or a subfield indicating a first period corresponding to the allocated time. In the embodiment, the first period may be set to a value of X microseconds (µs).

[0096] STA711 may respond to MRTT frame 720 by sending CTS frame 721 to AP710. Subsequently, STA711 may send non-TB PPDUs 722, 724 containing one or more data frames to AP710 during the first period indicated in MRTT frame 720. In an embodiment, AP710 may send one or more block Ack(BA) frames 723, 725 in response to one or more data frames contained in the non-TB PPDUs 722, 724 received from STA711.

[0097] Figure 8 illustrates an example 800 of the TXS procedure (mode = 2). As shown in Figure 8, the TXS procedure may be initiated by AP810 and send an MRTT frame 820 to STA811. The MRTT frame 820 may allocate a portion of the TXOP acquired by AP810 to STA811 and may indicate a TXS mode equal to 2. Upon receiving the MRTT frame 820, STA811 may use the allocated time to send one or more non-TB PPDUs to STA812. One or more non-TB PPDUs may include data frames, control frames, management frames, or action frames.

[0098] In the embodiment, the MRTT frame 820 may include a triggered TXOP shared mode subfield indicating TXS mode, and / or a subfield indicating a first period corresponding to the allocated time. In the embodiment, the first period may be set to a value of X microseconds (µs).

[0099] STA811 may respond to MRTT frame 820 by sending CTS frame 821 to AP810. Subsequently, STA811 may send non-TB PPDUs 822, 824 containing one or more data frames to STA818 during the first period indicated in MRTT frame 720. In an embodiment, STA812 may send one or more BA frames 823, 825 in response to one or more data frames contained in the non-TB PPDUs 822, 824 received from STA811.

[0100] Figure 9 illustrates an exemplary multi-AP network 900. The exemplary multi-AP network 900 may be a multi-AP network that conforms to the Wi-Fi Alliance standard specification for multi-AP networks. As shown in Figure 9, the multi-AP network 900 may include a multi-AP controller 902, and several multi-AP groups (or multi-AP sets) 904, 906, and 908.

[0101] The multi-AP controller 902 may be a logical entity that implements the logic for controlling APs within the multi-AP network 900. The multi-AP controller 902 may receive capability information and measurements from the APs and may trigger AP control commands and operations on the APs. The multi-AP controller 902 may also provide onboarding functionality for onboarding and provisioning APs onto the multi-AP network 900.

[0102] Multi-AP groups 904, 906, and 908 may each include multiple APs. APs in a multi-AP group are within each other's communication range. However, APs in a multi-AP group do not need to have the same primary channel. As used herein, the primary channel of an AP refers to the default channel that the AP uses to monitor management frames and / or to transmit beacon frames. For an STA associated with an AP, the primary channel refers to the AP's primary channel advertised through the AP's beacon frames.

[0103] In one approach, one of the APs in a multi-AP group may be designated as the master AP. The designation of the master AP may be made by the AP controller 902 or by the APs in the multi-AP group. The master AP of a multi-AP group may be fixed or may change over time among the APs in the multi-AP group. APs that are not the master AP of a multi-AP group are known as slave APs. In one approach, the master AP may be within the communication range of all slave APs in the multi-AP group, and vice versa. A slave AP may not be within the communication range of another slave AP in the multi-AP group.

[0104] One approach involves APs within a multi-AP group coordinating with each other, including coordinating transmissions within the multi-AP group. One aspect of coordination may include coordinating to perform multi-AP transmissions within the multi-AP group. As used herein, a multi-AP transmission is a transmission event in which multiple APs (of a multi-AP group or multi-AP network) transmit simultaneously over a period of time. The period of simultaneous AP transmission may be a continuous period. A multi-AP transmission may use different transmission techniques, such as coordinated OFDMA, coordinated space reuse, joint transmit and receive, coordinated beamforming and coordinated time-division multiple access (TDMA), or a combination of two or more of the aforementioned techniques.

[0105] Multi-AP group coordination can be enabled by the AP controller and / or the master AP of the multi-AP group. In one approach, the AP controller and / or master AP can control time and / or frequency sharing in a TXOP. For example, when one of the APs in a multi-AP group (e.g., the master AP) acquires a TXOP, the AP controller and / or master AP can control how the time / frequency resources of the TXOP are shared with the other APs in the multi-AP group. In an implementation, the AP in the multi-AP group that acquires the TXOP becomes the master AP of the multi-AP group. The master AP can then share a portion of its acquired TXOP (which may be the entire TXOP) with one or more other APs in the multi-AP group.

[0106] OFDMA is a transmission technique introduced in the revised IEEE 802.11ax standard. OFDMA provides a multi-access scheme that allows multiple STAs to transmit frames simultaneously using non-overlapping (orthogonal) frequency subcarriers.

[0107] In Cooperative OFDMA (C-OFDMA), it is assumed that multiple APs (which may or may not include a coordinating AP) can coordinate multi-AP transmissions by assigning each of the multiple APs (e.g., a master AP) to a respective frequency resource (e.g., a channel / subchannel) of the available frequency resources during the transmission period. The coordinating AP may further specify transmission parameters for multi-AP transmissions (e.g., PPDU format, guard interval, symbol duration, etc.). Multiple APs access their assigned frequency resources simultaneously using OFDMA during the transmission period. Figure 10 illustrates C-OFDMA as a multi-AP channel access compared to Extended Distributed Channel Access (EDCA). As shown in Figure 10, in EDCA, channel access by multiple APs (e.g., AP1, AP2) can occur over a continuous period (e.g., TXOP). During a given channel access, an entire channel (e.g., 80 MHz) may be used by a single AP. In contrast, in C-OFDMA, access by multiple APs (multi-AP channel access) can occur over the same period (e.g., TXOP) via orthogonal frequency resources. For example, as shown in Figure 10, an 80MHz channel may be divided into four non-overlapping 20MHz channels, each assigned to one of the APs of the multiple APs. The multiple APs can, for example, transmit simultaneously to their respective associated STAs within the same period.

[0108] Future drafts of the IEEE 802.11 standard are expected to extend the existing TXS procedure described above to APs. In such a procedure (hereinafter referred to as the AP-to-AP TXS procedure), an AP (hereinafter referred to as the shared AP) may allocate a portion of the acquired TXOP time to one or more other APs (hereinafter referred to as the shared APs). The shared APs may use the allocated time to communicate with their associated STAs and / or shared APs without being triggered by the shared APs. The shared APs may or may not be part of the APs communicating during the allocated time.

[0109] Figure 11 shows an example 1100 illustrating the inter-AP TXS procedure. As shown in Figure 11, Example 1100 includes APs 1102, 1104, 1106, and 1108. The exemplary APs 1102, 1104, 1106, and 1108 may form a multi-AP group, as described above in Figure 9. In the example, AP 1102 may be the master AP of the multi-AP group, and APs 1104, 1106, and 1108 may be slave APs of the multi-AP group. However, the inter-AP TXS procedure described herein is not limited to use in a multi-AP group and / or in the presence of a master AP and slave APs.

[0110] In Example 1100, AP1102 may acquire a TXOP. Subsequently, AP1102 may initiate inter-AP TXS operation by sending an MRTT frame 1110 to AP1104. The MRTT frame 1110 may have a format similar to the MU-RTS trigger frame 600 described above. In this example, the MRTT frame 1110 may indicate the identifier of AP1104 (e.g., in the AID 12 subfield of the user information field in the MRTT frame 1110) and the allocated time 1132 of the TXOP (e.g., in the allocated duration subfield of the user information field). Furthermore, the MRTT frame 1110 may indicate the TXS mode (e.g., in the triggered TXOP shared mode subfield of the common information field in the MRTT frame 1110). The TXS mode may indicate whether AP1104 communicates with AP1102 only during allocated time 1132 (for example, when TXS mode is set to 1), or whether AP1104 can communicate with AP1102 or another STA (for example, an associated non-AP STA or another AP STA) during allocated time 1132.

[0111] AP1104 may respond to MRTT frame 1110 by sending CTS frame 1112 to AP1102. Subsequently, for example, in the short interframe space (SIFS) after sending CTS frame 1112, AP1104 may use the allocated time 1132 for communication according to the TXS mode indicated in MRTT frame 1110, without a trigger from AP1102. In Embodiment 1100, the TXS mode may allow AP1104 to communicate with AP1102 or another STA during the allocated time 1132. Thus, as shown in Figure 11, AP1104 may use the allocated time 1132 to send a (non-TB) downlink (DL) PPDU 1114 to the relevant STA (not shown in Figure 11) and receive an uplink (UL) PPDU 1116 from the relevant STA (not shown in Figure 11).

[0112] In the embodiment, along with the remaining time of the TXOP, AP1102 may initiate another inter-AP TXS operation by sending an MRTT frame 1118 to AP1106 and 1108. The MRTT frame 1118 may have a format similar to the MU-RTS trigger frame 600 described above. In the embodiment, the MRTT frame 1118 may indicate the identifiers of AP1106 and 1108 (e.g., in the respective AID 12 subfield of the respective user information field of the MRTT frame 1118), as well as the allocated time 1134 of the TXOP (e.g., in the respective allocated duration subfield of the user information field). Furthermore, the MRTT frame 1118 may indicate the TXS mode (e.g., the triggered TXOP shared mode subfield of the common information field of the MRTT frame 1118). The TXS mode may indicate whether AP1106 and 1108 communicate with AP1102 only during the allocated time 1134 (for example, when TXS mode is set to 1), or whether AP1106 and 1108 may communicate with AP1102 or other STAs (for example, related non-AP STAs or other AP STAs) during the allocated time 1134.

[0113] AP1106 and 1108 may respond to MRTT frame 1118 by sending CTS frames 1120 and 1122, respectively, to AP1102. Subsequently, for example, after sending CTS frames 1120 and 1122, respectively, AP1106 and 1108 may use the allocated time 1134 for communication according to the TXS mode shown in MRTT frame 1118, without a trigger from AP1102. In Embodiment 1100, the TXS mode may allow AP1106 and 1108 to communicate with AP1102 or another STA during the allocated time 1134. Thus, as shown in Figure 11, AP1104 may use the allocated time 1134 to send a (non-TB)DL PPDU 1124 to the relevant STA (not shown in Figure 11) and receive a UL PPDU 1128 from the relevant STA (not shown in Figure 11). Similarly, AP1108 may use the allocated time 1134 to send (non-TB)DL PPDU 1126 to the relevant STA (not shown in Figure 11) and receive UL PPDU 1130 from the relevant STA (not shown in Figure 11).

[0114] In the embodiment, C-OFDMA may be used to transmit DL PPDUs 1124 and 1126, and UL PPDUs 1128 and 1130. Specifically, AP 1102 may assign APs 1106 and 1108 to their respective frequency resources that are orthogonal to each other with respect to the allocated time 1134. For example, AP 1102 may divide an 80 MHz channel into two non-overlapping 40 MHz channels, each assigned to one of APs 1106 and 1108. In the embodiment, the frequency resources assigned to the APs are shown in the RU allocation subfield of the user information field (indicating the AP identifier) ​​in the MRTT frame 1118. Therefore, DL PPDUs 1124 and UL PPDUs 1128 may be transmitted on RUs orthogonal to the RUs used to transmit DL PPDUs 1126 and UL PPDUs 1130.

[0115] Figure 12 illustrates an exemplary PPDU1200 that may be used for downlink DL PPDU or UL PPDU. For example, PPDU1200 may be an embodiment of DL PPDU1114, 1124, or 1126 described in Figure 11, or an embodiment of UL PPDU1116, 1128, or 1130. PPDU1200 may be an ultra-high reliability (UHR) PPDU that can be used by devices conforming to the IEEE 802.11bn revision. Such devices may operate in the 2.4, 5, and 6 GHz bands. In implementations, PPDU1200 may be transmitted over bandwidths up to 320 MHz. PPDU1200 may be used by devices for both single-user (SU) and multi-user (MU) transmissions. Note that UHR may be referred to by different names (e.g., ultra-high throughput (UHR) or ultra-high efficiency (UHE)).

[0116] As shown in Figure 12, the PPDU1200 includes a non-HT short training field (L-STF), a non-HT long training field (L-LTF), a non-high-throughput (non-HT) signaling field (L-SIG), a non-HT repetitive signaling field (RL-SIG), a universal signaling field (U-SIG), a UHR signaling field (UHR-SIG), a UHR short training field (UHR-STF), one or more UHR long training fields (UHR-LTF), a data field, and a packet extension (PE) field.

[0117] The L-STF is used by the PPDU1200 receiver to synchronize with the carrier frequency and frame timing of the PPDU1200 transceiver and adjust the receiver signal gain.

[0118] L-LTF is used by the PPDU1200 receiver to estimate channel coefficients in both the signal fields (L-SIG, RL-SIG, U-SIG, UHR-SIG) and data fields of the PPDU1200 to equalize channel responses (e.g., amplitude and phase distortion).

[0119] L-SIG and RL-SIG contain the parameters necessary to demodulate the data field. L-SIG can be demodulated using channel coefficients estimated with L-LTF to obtain the demodulation parameters of the data field.

[0120] U-SIG ensures forward compatibility with PPDU1200. This means that any future PPDU that is backward compatible with IEEE 802.11bn will include the same U-SIG field. Therefore, devices compliant with IEEE 802.11bn will be able to understand at least part of PPDUs developed in future revisions, as long as those revisions include the U-SIG field.

[0121] The UHR-SIG includes a per-STA display of resource unit (RU) allocation. The receiving STA can use the display in the UHR-SIG to locate its own payload within the PPDU1200's data field.

[0122] The L-SIG, RL-SIG, U-SIG, and UHR-SIG fields can be considered the PHY headers of the PPDU1200.

[0123] The UHR-STF and one or more UHR-LTFs are used by the receiver of the PPDU1200 to equalize the channel response (e.g., amplitude and phase distortion) within the data field of the PPDU1200 and to estimate the channel coefficients.

[0124] The data field contains one or more payloads carried by the PPDU1200. These one or more payloads may include MPDUs.

[0125] The PE field is an extension of the PPDU1200 designed to give the PPDU1200 receiver sufficient time to respond after receiving the PPDU1200.

[0126] Figure 13 is an embodiment 1300 illustrating a problem that may arise in the inter-AP TXS procedure illustrated in Figure 11. As shown in Figure 13, embodiment 1300 includes APs 1102, 1106, and 1108 described above. Similar to embodiment 1100, AP 1102 initiates the inter-AP TXS operation by sending an MRTT frame 1118 to APs 1106 and 1108. The MRTT frame 1118 may have a similar format to the MU-RTS trigger frame 600 described above. In the embodiment, the MRTT frame 1118 may show the identifiers of APs 1106 and 1108 (for example, in the respective AID 12 subfields of the respective user information fields of the MRTT frame 1118), as well as the allocated time 1134 of the TXOP (for example, in the allocated duration subfields of the respective user information fields). Furthermore, the MRTT frame 1118 may indicate TXS mode (e.g., the triggered TXOP shared mode subfield of the common information field in the MRTT frame 1118). The TXS mode may indicate whether APs 1106 and 1108 communicate with AP 1102 only during allocated time 1134 (e.g., when TXS mode is set to 1), or whether APs 1106 and 1108 may communicate with AP 1102 or other STAs (e.g., related non-AP STAs or other AP STAs) during allocated time 1134.

[0127] AP1106 and 1108 respond to MRTT frame 1118 by sending CTS frames 1120 and 1122, respectively, to AP1102. Subsequently, for example, after sending CTS frames 1120 and 1122, respectively, AP1106 and 1108 may use the allocated time 1134 for communication according to the TXS mode shown in MRTT frame 1118, without a trigger from AP1102. In Embodiment 1300, the TXS mode may allow AP1106 and 1108 to communicate with AP1102 or another STA during the allocated time 1134. Thus, as shown in Figure 13, AP1104 may use the allocated time 1134 to send DL PPDU 1302 to the relevant STA (not shown in Figure 13) and receive UL PPDU 1306 from the relevant STA (not shown in Figure 13). Similarly, AP1108 may use the allocated time 1134 to send DL PPDU 1304 to the relevant STA (not shown in Figure 13) and receive UL PPDU 1308 from the relevant STA (not shown in Figure 13).

[0128] In the embodiment, C-OFDMA may be used to transmit DL PPDUs 1302 and 1304, and UL PPDUs 1306 and 1308. Specifically, AP 1102 may assign APs 1106 and 1108 to their respective frequency resources that are orthogonal to each other with respect to the allocated time 1134. For example, AP 1102 may divide an 80 MHz channel into two non-overlapping 40 MHz channels, each assigned to one of APs 1106 and 1108. In the embodiment, the frequency resources assigned to the APs are shown in the RU allocation subfield of the user information field (indicating the AP identifier) ​​in the MRTT frame 1118. Therefore, DL PPDUs 1302 and UL PPDUs 1306 may be transmitted on RUs orthogonal to the RUs used to transmit DL PPDUs 1304 and UL PPDUs 1308.

[0129] Since AP1106 and 1108 are not triggered by AP1102 during the allocated time 1134, AP1102 may indicate a first period within the allocated time 1134 for DL ​​transmissions and / or a second period within the allocated time 1134 for UL transmissions in the MRTT frame 1118. AP1106 and 1108 may use the first period to transmit DL PPDUs 1302 and 1304, respectively. Similarly, AP1106 and 1108 may use the second period to receive UL PPDUs 1306 and 1308, respectively. The first and second periods assist in the time alignment of DL PPDUs 1302 and 1304, and UL PPDUs 1306 and 1308, as shown in Figure 13, and reduce potential OFDM symbol misalignment in the receiver receiving one of PPDUs 1302, 1304, 1306, or 1308. OFDM symbol misalignment results in a loss of synchronization between the boundary of an OFDM symbol received over a first portion of the channel (e.g., the first 40 MHz) and the boundary of the corresponding OFDM symbol received over a second portion of the channel (e.g., the second 40 MHz). Since the receiver typically receives and processes the entire channel (and there are no dedicated receive filters per subchannel), the receiver may be unable to decode the PPDU resulting from the OFDM symbol misalignment.

[0130] In the implementation, DL PPDU1302 and 1304 may each contain their respective trigger frames. In the implementation, the trigger frame contained in DL PPDU1302 triggers one or more STAs associated with AP1106 for UL transmission to AP1106. The length / size of the trigger frame contained in DL PPDU1302 depends on the total number of STAs associated with AP1106 that are triggered by the trigger frame. UL transmission may be a C-OFDMA transmission to AP1106 by multiple STAs. In the embodiment, UL transmission may be performed via UL PPDU1306 during a second period shown in MRTT frame 1118. In the implementation, the trigger frame contained in DL PPDU1304 triggers one or more STAs associated with AP1108 for UL transmission to AP1108. The length / size of the trigger frame contained in DL PPDU1304 depends on the total number of STAs associated with AP1108 that are triggered by the trigger frame. UL transmission may be a C-OFDMA transmission by multiple STAs to AP1108. In the embodiment, UL transmission may be performed via UL PPDU1308 during a second period shown in MRTT frame 1118.

[0131] In the implementation, AP1102 may have information about the amount of downlink data that AP1106 and 1108 intend to transmit in DL PPDU 1302 and 1304, respectively. AP1102 may take this information into consideration when setting the first period for DL ​​PPDU 1302 and 1304. However, in situations where AP1106 and 1108 do not know the characteristics of the uplink data that they intend to receive during UL transmission (for example, within UL PPDU 1306 and 1308, respectively), the first period may not adequately consider the required / desired length of the trigger frames contained in DL PPDU 1304 and / or the required / desired length of the trigger frames contained in DL PPDU 1304. For example, as shown in Figure 13, AP1102 may set the first period in a manner that substantially exceeds the required length of the respective trigger frames contained in DL PPDU 1302 and 1304. Thus, both AP1106 and 1108 may have to rely on padding of DL PPDU1302 and 1304, respectively, to time-match DL PPDU1302 and 1304. This may result in wasted resources allocated to downlink transmissions. In another embodiment, the first period may be too short for DL ​​PPDU1302 to contain trigger frames of appropriate length / size for triggering one or more STAs associated with AP1106. Alternatively, or additionally, the first period may be too short for DL ​​PPDU1304 to contain trigger frames of appropriate length / size for triggering one or more STAs associated with AP1108. Therefore, resources allocated to UL transmissions (e.g., UL PPDU1306 and / or UL PPDU1308) may be partially unused because AP1106 and / or AP1108 may not be able to trigger all of the STAs they intend to transmit during the UL transmission.

[0132] Embodiments of this disclosure address the aforementioned problems that may arise in inter-AP TXS, as will be further described below. In one embodiment, a first AP may transmit a first frame to a second AP indicating the number of STAs for a UL transmission to the first AP. The STAs whose numbers are indicated in the first frame may be STAs that the first AP wishes to receive from a UL transmission. The STAs may be associated with the first AP. The first AP may be a shared AP, and the second AP may be a sharing AP. A UL transmission may be part of a coordinated transmission. A coordinated transmission may include another UL transmission to the second AP or to a third AP. A coordinated transmission may be a C-OFDMA transmission. A coordinated transmission may be performed within the allocated time of a TXOP acquired by the second AP. The second AP may transmit a second frame to the first AP indicating a period for a DL PPDU that includes a trigger frame for the STAs. The trigger frame triggers the STAs for the UL transmission. In embodiments, the period is based on the number of STAs indicated in the first frame. In an embodiment, the duration is within the allocated time of the TXOP. In another embodiment, the first AP may send a first frame to the second AP indicating a first length (e.g., number of bytes) of a trigger frame for transmission by the first AP to one or more STAs in the DL PPDU. One or more STAs may be associated with the first AP. The first AP may receive a second frame from the second AP indicating the duration of the DL PPDU. The duration may be within the allocated time of the TXOP obtained by the second AP. In an embodiment, the duration is based on the first length of the trigger frame. In another embodiment, the duration is based on a second length of the trigger frame. The second length may be based on the first length. Further embodiments and details of the embodiments are presented in the exemplary embodiments described below.

[0133] Figure 14 illustrates Example 1400 of the AP-to-TXS procedure according to an embodiment. As shown in Figure 14, Example 1400 includes APs 1402, 1404, and 1406. The exemplary APs 1402, 1404, and 1406 may form a multi-AP group as described above in Figure 9. In the embodiment, AP 1402 may be an AP shared by the multi-AP group, and APs 1404 and 1406 may be shared APs (or slave APs) in the multi-AP group. However, the AP-to-TXS procedure described herein is not limited to use in a multi-AP group and / or in the presence of a shared AP (or master AP) and shared APs (or slave APs).

[0134] As shown in Figure 14, Embodiment 1400 may be initiated by AP1404 sending frame 1408 to AP1402. In this embodiment, frame 1408 may indicate the number of STAs for an uplink (UL) transmission to AP1404. The STAs whose number is shown in frame 1408 may be associated with AP1404. The STAs whose number is shown in frame 1408 may be STAs that AP1404 intends to receive or desires to receive in a UL transmission. The STAs whose number is shown in frame 1408 may be scheduled by AP1404 for a UL transmission. A UL transmission may be part of a coordinated transmission. A coordinated transmission may be performed within the allocated time of a TXOP acquired by AP1402. A coordinated transmission may be performed in the context of an AP-to-AP TXS procedure, as described above. A coordinated transmission may or may not include a transmission to AP1402. Coordinated transmission may include transmissions to AP1402 and one or more of AP1404 and AP1406. Alternatively, as shown in Figure 14, coordinated transmission may include transmissions to AP1404 and 1406. Coordinated transmission may include C-OFDMA transmission, Coordinated Space Reuse (C-SR) transmission, Coordinated Beamforming (C-BF), or Coordinated Joint Transmission.

[0135] In another embodiment, frame 1408 may indicate a first length / size (e.g., number of bytes) of a trigger frame for transmission by AP1404 to one or more STAs in the DL PPDU. One or more STAs may be associated with AP1404. One or more STAs may be STAs that AP1404 intends to receive or desires to receive from the UL transmission. UL transmissions from one or more STAs may follow AP1404's transmission of the DL PPDU. UL transmissions from one or more STAs may be triggered by a trigger frame contained in the DL PPDU. The first length / size of the trigger frame may be preferred / recommended / selected by AP1404. The first length / size may be based on the number of one or more STAs.

[0136] In the embodiment, frame 1408 may be, for example, a QoS data / null frame or an action frame. When frame 1408 is a QoS data / null frame, it may include an aggregate control (A-control) field containing the STA count and / or a first length / size of the trigger frame, for example, as illustrated in Figure 16. When frame 1408 is an action frame, it may include an information element (or information field) containing the STA count and / or a first length / size of the trigger frame. The information element is illustrated, for example, in Figure 17.

[0137] In one embodiment, frame 1408 may further include a Buffer Status Report (BSR). The BSR may indicate the amount of traffic buffered for DL ​​transmissions at AP1404. In one implementation, the buffered traffic may correspond to all traffic buffered for DL ​​transmissions at AP1404. In another embodiment, the BSR may indicate the amount of traffic buffered for UL transmissions to AP1404. In one implementation, the buffered traffic may correspond to all traffic buffered for UL transmissions to AP1404 (from all STAs associated with AP1404). In another implementation, the buffered traffic may correspond to traffic buffered for UL transmissions to AP1404 at the number of STAs indicated in frame 1408. In one implementation, the buffered traffic may correspond to traffic buffered for DL / UL transmissions for a specific access category (AC) or TID. The BSR may indicate the amount of buffered traffic as described with reference to Figure 4 above (e.g., in the queue size subfield).

[0138] In an embodiment, Embodiment 1400 may also include AP1406 transmitting frame 1410 to AP1402. Frame 1410 may be transmitted before or after frame 1408. In an embodiment, frame 1410 may indicate a number of STAs for a UL transmission to AP1406. The STAs whose number is indicated in frame 1410 may be associated with AP1406. The STAs whose number is indicated in frame 1410 may be STAs that AP1406 intends to receive or desires to receive in a UL transmission. The STAs whose number is indicated in frame 1410 may be scheduled by AP1406 for a UL transmission. A UL transmission to AP1406 may be part of a coordinated transmission that includes a UL transmission to AP1404. Frame 1410 is similar to frame 1408. The same description above relating to frame 1408 applies to frame 1410.

[0139] Subsequently, AP1402 may acquire a TXOP and initiate inter-AP TXS operation by sending an MRTT frame 1412 to AP1404 and 1406. The MRTT frame 1412 may have a format similar to the MU-RTS trigger frame 600 described above. In this embodiment, the MRTT frame 1412 may indicate the identifiers of AP1404 and 1406 (for example, in the respective AID 12 subfields of the respective user information fields of the MRTT frame 1412). Furthermore, the MRTT frame 1412 may indicate the TXS mode (for example, the triggered TXOP shared mode subfield in the common information field of the MRTT frame 1412) and the allocated time of the TXOP (for example, the allocated duration subfields of the respective user information fields). The TXS mode may indicate whether AP1404 and 1406 communicate with AP1402 only during the allocated time 1414 (for example, when TXS mode is set to 1), or whether AP1404 and 1406 may communicate with AP1402 or other STAs (for example, the associated non-AP STA or another AP STA) during the allocated time 1414.

[0140] In an embodiment, the MRTT frame 1412 may further indicate a period 1428 within the allocated time 1414 for DL ​​transmissions by AP 1404 and / or AP 1406. In an embodiment, period 1428 may be configured to accommodate the transmission of a first DL PPDU by AP 1404. The first DL PPDU may include one or more data frames for one or more STAs associated with AP 1404, and / or trigger frames for STAs indicated by AP 1404 in frame 1408. In an embodiment, period 1428 may further be configured to accommodate the transmission of a second DL PPDU by AP 1406. The second DL PPDU may include one or more data frames for one or more STAs associated with AP 1406, and / or trigger frames for STAs indicated by AP 1406 in frame 1410. The first and second DL PPDUs may be intended for simultaneous transmission (e.g., C-OFDMA transmission).

[0141] In this embodiment, period 1428 may be based on the number of STAs shown in frame 1408 and / or the number of STAs shown in frame 1410.

[0142] In an embodiment, MRTT frame 1412 may alternatively or additionally indicate a period 1430 for trigger frames included in DL transmissions by AP 1404 and / or AP 1406. Period 1430 may be within period 1428. In an embodiment, period 1430 may be based on the number of STAs shown in frame 1408 and / or the number of STAs shown in frame 1410.

[0143] In an embodiment, AP1402 may determine a first length / size for a DL transmission (and / or trigger frames included in a DL transmission) based on the number of STAs shown in frame 1408. In an embodiment, the first length / size may further be based on the number of data frames that AP1404 intends to transmit in a first DL PPDU, and / or the number of STAs that AP1404 intends to serve with the first DL PPDU. In an embodiment, AP1402 may determine a second length / size for a DL transmission (and / or trigger frames included in a DL transmission) based on the number of STAs shown in frame 1410. In an embodiment, the second length / size may further be based on the number of data frames that AP1406 intends to transmit in a second DL PPDU, and / or the number of STAs that AP1406 intends to serve with the second DL PPDU. In the embodiment, based on the number of STAs shown in frames 1408 / 1410, AP1402 may determine the length / size of the trigger frame fields (e.g., user information fields) required to trigger the STAs shown for UL transmission. The fields may include user-specific fields. The fields may be fields whose number in the trigger frame varies depending on the number of STAs triggered by the trigger frame.

[0144] In an embodiment, AP1402 may determine a first duration based on a first length / size. In an embodiment, AP1402 may determine a second duration based on a second length / size. In an embodiment, AP1402 may select the larger of the first and second durations as period 1428 (or period 1430). In this way, it is ensured that period 1428 (or period 1430) is long enough to accommodate the respective trigger frames of both AP1404 and AP1406. In another embodiment, AP1402 may select the shorter of the first and second durations as period 1428 (or period 1430). This ensures that period 1428 is fully utilized by at least one of AP1404 and AP1406.

[0145] In another embodiment, period 1428 (and / or period 1430) may be based on a first length / size of the trigger frame shown in frame 1408 and / or the first length / size of the trigger frame shown in frame 1410. In an embodiment, AP1402 may determine a second length / size of the trigger frame based on a first length / size shown in frame 1408 and / or the first length / size shown in frame 1410. In an embodiment, period 1428 (and / or period 1430) may be based on a second length / size.

[0146] In an embodiment, MRTT frame 1412 may include the duration of period 1428 (and / or period 1430). In an embodiment, the start time of period 1428 (and / or period 1430) may be determined based on MRTT frame 1412. For example, the start time of period 1428 may be the time from the time MRTT frame 1412 was received plus the transmission time of 2SIFS and the CTS frame. The end time of period 1428 may be determined based on the start time and the indicated duration. The start time of period 1430 may be based on the start time of period 1428 (e.g., X u seconds from the start time of period 1428). The end time of period 1430 may be determined based on the start time of period 1430 and the specified duration of period 1430.

[0147] In another embodiment, the MRTT frame 1412 may include the start and end times of period 1428 (and / or period 1430), the start and duration of period 1428 (and / or period 1430), or the duration and end times of period 1428 (and / or period 1430). In such an embodiment, the start time of period 1428 (and / or period 1430) may not be based on the MRTT frame 1412.

[0148] In another embodiment, MRTT frame 1412 may indicate that period 1428 (and / or period 1430) is a segment of the allocated time 1414. For example, MRTT frame 1412 may indicate that period 1428 corresponds to the first half / third / quarter of the allocated time 1414, or the first X microseconds of the allocated time 1414. For example, MRTT frame 1412 may indicate that period 1430 corresponds to the second half / third / quarter of the allocated time 1414, or the last X microseconds of the allocated time 1414.

[0149] In other embodiments, AP1402 may initiate inter-AP TXS operation by transmitting a frame other than an MRTT frame. For example, AP1402 may use a multi-AP trigger frame to initiate inter-AP TXS operation. The multi-AP trigger frame may contain / display the same information described above as contained in / displayed in MRTT frame 1412. AP1404 and 1406 may respond to or acknowledge the multi-AP trigger frame from AP1402, or may not do so.

[0150] As shown in Figure 14, AP1404 and 1406 may respond to MRTT frame 1412 by sending CTS frames 1416 and 1418 to AP1402, respectively. Subsequently, for example, after sending CTS frames 1416 and 1418, AP1404 and AP1406 may communicate using the allocated time 1414, taking into account period 1428 (and / or period 1430), according to the TXS mode indicated in MRTT frame 1412, without a trigger from AP1402. In Embodiment 1400, the TXS mode may allow AP1404 and 1406 to communicate with AP1402 or another STA during the allocated time 1414. Thus, as shown in Figure 14, AP1404 may use period 1428 of the allocated time 1414 to send a (non-TB)DL PPDU 1420 to the relevant STA (not shown in Figure 14). DL PPDU 1420 may contain a trigger frame whose length / size is considered by period 1428 (and / or period 1430). In an embodiment, AP 1404 may use period 1430 to transmit the trigger frame contained in DL PPDU 1420. Similarly, as shown in Figure 14, AP 1406 may use period 1428 of the allocated time 1414 to transmit (non-TB) DL PPDU 1422 to the associated STA (not shown in Figure 14). DL PPDU 1422 may contain a trigger frame whose length / size is considered by period 1428 (and / or period 1430). In an embodiment, AP 1406 may use period 1430 to transmit the trigger frame contained in DL PPDU 1422.

[0151] In Example 1400, the combined length / size of one or more data frames and trigger frames transmitted by AP1404 in DL PPDU 1420 may be greater than the combined length / size of one or more data frames and trigger frames transmitted by AP1406 in DL PPDU 1422. In this example, AP1402 may set period 1428 based on the combined length / size of one or more data frames and trigger frames transmitted by AP1404 in DL PPDU 1420. For example, AP1404 may set the first period 1428 to be equal to the combined length / size of one or more data frames and trigger frames transmitted by AP1404 in DL PPDU 1420. Thus, as shown in Figure 14, AP1404 may not need to insert any padding bits into DL PPDU 1420 and may utilize the entire period 1428 for transmitting data / control information. Thus, the utilization of the allocated time 1414, particularly period 1428, is increased. Because the combined length / size of one or more data frames and trigger frames transmitted by AP1406 in DL PPDU1422 is shorter than the period 1428, AP1406 may insert padding bits into DL PPDU1422. The padding bits may be inserted before or after the trigger frames contained in DL PPDU1422.

[0152] In an embodiment, AP1404 may receive UL PPDU 1424 from one or more associated STAs using the remaining duration of the allocated time 1414, according to any representation of MRTT frame 1412 (not shown in Figure 14). In an embodiment, AP1406 may receive UL PPDU 1426 from one or more associated STAs using the remaining duration of the allocated time 1414, according to any representation of MRTT frame 1412 (not shown in Figure 14). In an embodiment, as described above, frame 1412 may further indicate periods for UL PPDU 1424 and 1426. In an embodiment, AP1404 may signal a period to one or more associated STAs scheduled to transmit UL PPDU 1424. In an embodiment, AP1406 may signal a period to one or more associated STAs scheduled to transmit UL PPDU 1426.

[0153] In the embodiment, C-OFDMA may be used to transmit DL PPDUs 1420 and 1422, and UL PPDUs 1424 and 1426. Specifically, AP 1402 may assign APs 1404 and 1406 to mutually orthogonal frequency resources with respect to the allocated time 1414. For example, AP 1402 may divide an 80 MHz channel into two non-overlapping 40 MHz channels, each assigned to one of APs 1404 and 1406. In the embodiment, the frequency resources assigned to APs are shown in the RU allocation subfield of the user information field (indicating the AP identifier) ​​in the MRTT frame 1412. Therefore, DL PPDUs 1420 and UL PPDUs 1424 may be transmitted on RUs orthogonal to the RUs used to transmit DL PPDUs 1422 and UL PPDUs 1426.

[0154] Figure 15 illustrates Example 1500 of the AP-to-TXS procedure according to another embodiment. As shown in Figure 15, Example 1500 also includes APs 1402, 1404, and 1406, as described above in Figure 15. The exemplary APs 1402, 1404, and 1406 may form a multi-AP group, as described above in Figure 9. In the embodiment, AP 1402 may be an AP shared by the multi-AP group, and APs 1404 and 1406 may be shared APs (or slave APs) in the multi-AP group. However, the AP-to-TXS procedures described herein are not limited to use in a multi-AP group and / or in the presence of a shared AP (or master AP) and shared APs (or slave APs).

[0155] As shown in Figure 15, Embodiment 1500 may be initiated by AP1402 transmitting frame 1502 to AP1404 and / or AP1406. In this embodiment, frame 1502 requests a BSR from AP1404 and / or AP1406 for coordinated transmission. Coordinated transmission may be performed within the allocated time of the TXOP acquired by AP1402. Coordinated transmission may be performed in the context of an inter-AP TXS procedure, as described above. Coordinated transmission may include coordinated DL transmission and / or coordinated UL transmission. Coordinated transmission may include transmissions from / to AP1402. Coordinated transmission may include transmissions from / to AP1402, as well as transmissions from / to one or more of AP1404 and AP1406. Alternatively, as shown in Figure 15, coordinated transmission may include DL transmission by AP1404 and AP1406, and UL transmission to AP1404 and AP1406. Coordinated transmission may include C-OFDMA transmission, Coordinated Space Reuse (C-SR) transmission, Coordinated Beamforming (C-BF), or Coordinated Joint Transmission. Frame 1502 may include a Buffer Status Report Polling (BSRP) trigger frame, a basic trigger frame, a polling frame, or a request frame.

[0156] In one embodiment, AP1404 may respond to frame 1502 by sending frame 1504 to AP1402. In one embodiment, frame 1504 may include a BSR for coordinated transmission. The BSR may indicate the amount of traffic buffered for DL ​​transmissions at AP1404. In an implementation, the buffered traffic may correspond to all traffic buffered for DL ​​transmissions at AP1404. In another embodiment, the BSR may indicate the amount of traffic buffered for UL transmissions to AP1404. In an implementation, the buffered traffic may correspond to all traffic buffered for UL transmissions to AP1404 (from all STAs associated with AP1404). In an implementation, the buffered traffic may correspond to traffic buffered for DL / UL transmissions for a specific access category (AC) or TID. The BSR may indicate the amount of buffered traffic as described with reference to Figure 4 above (e.g., in the queue size subfield).

[0157] In the embodiment, frame 1504 may additionally or alternatively indicate a number of STAs for UL transmission to AP1404. The STAs whose number is shown in frame 1504 may be associated with AP1404. The STAs whose number is shown in frame 1504 may be STAs that AP1404 intends to receive or desires to receive in a UL transmission. The STAs whose number is shown in frame 1504 may be scheduled by AP1404 for UL transmission. A UL transmission to AP1404 may be part of a coordinated transmission shown in frame 1502.

[0158] In another embodiment, frame 1504 may indicate a first length / size (e.g., number of bytes) of a trigger frame for transmission by AP1404 to one or more STAs in the DL PPDU. One or more STAs may be associated with AP1404. One or more STAs may be STAs that AP1404 intends to receive or desires to receive from a UL transmission. UL transmissions from one or more STAs may follow AP1404's transmission of the DL PPDU. UL transmissions from one or more STAs may be triggered by a trigger frame contained in the DL PPDU. The first length / size of the trigger frame may be preferred / recommended / selected by AP1404. The first length / size may be based on the number of one or more STAs.

[0159] In the embodiment, frame 1504 may be, for example, a QoS data / null frame or an action frame. When frame 1504 is a QoS data / null frame, it may include an aggregate control (A-control) field containing the STA count and / or a first length / size of the trigger frame, for example, as illustrated in Figure 16. When frame 1504 is an action frame, it may include an information element (or information field) containing the STA count and / or a first length / size of the trigger frame. The information element is illustrated, for example, in Figure 17.

[0160] In an embodiment, Embodiment 1500 may also include AP1406 transmitting frame 1506 to AP1402. Frame 1506 may be transmitted before or after frame 1504. In an embodiment, frame 1506 may indicate a number of STAs for a UL transmission to AP1406. The STAs whose number is indicated in frame 1506 may be associated with AP1406. The STAs whose number is indicated in frame 1506 may be STAs that AP1406 intends to receive or desires to receive in a UL transmission. The STAs whose number is indicated in frame 1506 may be scheduled by AP1406 for a UL transmission. A UL transmission to AP1406 may be part of a coordinated transmission that includes a UL transmission to AP1404. Frame 1506 is similar to frame 1408. The same description above relating to frame 1408 applies to frame 1506.

[0161] Subsequently, AP1402 may acquire a TXOP and initiate inter-AP TXS operation by sending an MRTT frame 1508 to AP1404 and 1406. The MRTT frame 1508 may have a format similar to the MU-RTS trigger frame 600 described above. In this embodiment, the MRTT frame 1508 may indicate the identifiers of AP1404 and 1406 (for example, in the respective AID 12 subfields of the respective user information fields of the MRTT frame 1508). Furthermore, the MRTT frame 1508 may indicate the TXS mode (for example, the triggered TXOP shared mode subfield in the common information field of the MRTT frame 1508) and the allocated time 1510 of the TXOP (for example, the respective allocated duration subfields of the user information fields). The TXS mode may indicate whether AP1404 and 1406 will communicate with AP1402 only during the allocated time 1510 (for example, when TXS mode is set to 1), or whether AP1404 and 1406 may communicate with AP1402 or other STAs (for example, the associated non-AP STA or another AP STA) during the allocated time 1510.

[0162] In an embodiment, the MRTT frame 1508 may further indicate a period 1524 within the allocated time 1510 for DL ​​transmissions by AP 1404 and / or AP 1406. In an embodiment, period 1524 may be configured to accommodate the transmission of a first DL PPDU by AP 1404. The first DL PPDU may include one or more data frames for one or more STAs associated with AP 1404, and / or trigger frames for STAs indicated by AP 1404 in frame 1504. In an embodiment, period 1524 may further be configured to accommodate the transmission of a second DL PPDU by AP 1406. The second DL PPDU may include one or more data frames for one or more STAs associated with AP 1406, and / or trigger frames for STAs indicated by AP 1406 in frame 1506. The first and second DL PPDUs may be intended for simultaneous transmission (e.g., C-OFDMA transmission).

[0163] In this embodiment, the period 1524 may be based on the number of STAs shown in frame 1504 and / or the number of STAs shown in frame 1506.

[0164] In an embodiment, MRTT frame 1508 may alternatively or additionally indicate a period 1526 for trigger frames included in DL transmissions by AP 1404 and / or AP 1406. Period 1526 may be within period 1524. In an embodiment, period 1526 may be based on the number of STAs shown in frame 1504 and / or the number of STAs shown in frame 1506.

[0165] In an embodiment, AP1402 may determine a first length / size for a DL transmission (and / or trigger frames included in a DL transmission) based on the number of STAs shown in frame 1504. In an embodiment, the first length / size may further be based on the number of data frames that AP1404 intends to transmit in a first DL PPDU, and / or the number of STAs that AP1404 intends to serve with the first DL PPDU. In an embodiment, AP1402 may determine a second length / size for a DL transmission (and / or trigger frames included in a DL transmission) based on the number of STAs shown in frame 1506. In an embodiment, the second length / size may further be based on the number of data frames that AP1406 intends to transmit in a second DL PPDU, and / or the number of STAs that AP1406 intends to serve with the second DL PPDU. In the embodiment, based on the number of STAs shown in frames 1504 / 1506, AP1402 may determine the length / size of the trigger frame fields (e.g., user information fields) required to trigger the STAs shown for UL transmission. The fields may include user-specific fields. The fields may be fields whose number in the trigger frame varies depending on the number of STAs triggered by the trigger frame.

[0166] In an embodiment, AP1402 may determine a first duration based on a first length / size. In an embodiment, AP1402 may determine a second duration based on a second length / size. In an embodiment, AP1402 may select the larger of the first and second durations as period 1524 (or period 1526). In this way, it is ensured that period 1524 (or period 1526) is long enough to accommodate the respective trigger frames of both AP1404 and AP1406. In another embodiment, AP1402 may select the shorter of the first and second durations as period 1524 (or period 1526). This ensures that period 1524 is fully available to at least one of AP1404 and AP1406.

[0167] In another embodiment, period 1524 (and / or period 1526) may be based on a first length / size of the trigger frame shown in frame 1504 and / or the first length / size of the trigger frame shown in frame 1506. In an embodiment, AP1402 may determine a second length / size of the trigger frame based on a first length / size shown in frame 1504 and / or the first length / size shown in frame 1506. In an embodiment, period 1524 (and / or period 1526) may be based on a second length / size.

[0168] In an embodiment, MRTT frame 1508 may include the duration of period 1524 (and / or period 1526). In an embodiment, the start time of period 1524 (and / or period 1526) may be determined based on MRTT frame 1508. For example, the start time of period 1524 may be the time from the time MRTT frame 1508 was received plus the transmission time of 2SIFS and CTS frame. The end time of period 1524 may be determined based on the start time and the indicated duration. The start time of period 1526 may be based on the start time of period 1524 (e.g., X u seconds from the start time of period 1524). The end time of period 1526 may be determined based on the start time of period 1526 and the specified duration of period 1526.

[0169] In another embodiment, the MRTT frame 1508 may include the start and end times of period 1524 (and / or period 1526), ​​the start and duration of period 1524 (and / or period 1526), ​​or the duration and end times of period 1524 (and / or period 1526). In such an embodiment, the start time of period 1524 (and / or period 1526) may not be based on the MRTT frame 1508.

[0170] In another embodiment, MRTT frame 1508 may indicate that period 1524 (and / or period 1526) is a segment of the allocated time 1510. For example, MRTT frame 1508 may indicate that period 1524 corresponds to the first half / third / quarter of the allocated time 1510, or the first X microseconds of the allocated time 1510. For example, MRTT frame 1508 may indicate that period 1526 corresponds to the second half / third / quarter of the allocated time 1510, or the last X microseconds of the allocated time 1510.

[0171] In other embodiments, AP1402 may initiate inter-AP TXS operation by transmitting a frame other than an MRTT frame. For example, AP1402 may use a multi-AP trigger frame to initiate inter-AP TXS operation. The multi-AP trigger frame may contain / display the same information as contained in / displayed in MRTT frame 1508. AP1404 and 1406 may respond to, acknowledge, or not respond to the multi-AP trigger frame from AP1402.

[0172] As shown in Figure 15, AP1404 and 1406 may respond to MRTT frame 1508 by sending CTS frames 1512 and 1514, respectively, to AP1402. Subsequently, for example, after sending CTS frames 1512 and 1514, AP1404 and AP1406 may communicate using the allocated time 1510, taking into account period 1524 (and / or period 1526), ​​according to the TXS mode shown in MRTT frame 1508, without a trigger from AP1402. In Embodiment 1500, the TXS mode may allow AP1404 and 1406 to communicate with AP1402 or another STA during the allocated time 1510. Thus, as shown in Figure 15, AP1404 may use period 1524 of the allocated time 1510 to send a (non-TB)DL PPDU 1516 to the relevant STA (not shown in Figure 15). DL PPDU 1516 may contain a trigger frame whose length / size is considered by period 1524 (and / or period 1526). In an embodiment, AP 1404 may use period 1526 to transmit the trigger frame contained in DL PPDU 1516. Similarly, as shown in Figure 15, AP 1406 may use period 1524 of the allocated time 1510 to transmit (non-TB) DL PPDU 1518 to the associated STA (not shown in Figure 15). DL PPDU 1518 may contain a trigger frame whose length / size is considered by period 1524 (and / or period 1526). In an embodiment, AP 1406 may use period 1526 to transmit the trigger frame contained in DL PPDU 1518.

[0173] In Example 1500, the combined length / size of one or more data frames and trigger frames transmitted by AP1404 in DL PPDU 1516 may be greater than the combined length / size of one or more data frames and trigger frames transmitted by AP1406 in DL PPDU 1518. In the example, AP1402 may set period 1524 based on the combined length / size of one or more data frames and trigger frames transmitted by AP1404 in DL PPDU 1516. For example, AP1404 may set a first period 1524 to be equal to the combined length / size of one or more data frames and trigger frames transmitted by AP1404 in DL PPDU 1516. Thus, as shown in Figure 15, AP1404 may not need to insert any padding bits into DL PPDU 1516 and may utilize the entire period 1524 for transmitting data / control information. Thus, the utilization of the allocated time 1510, particularly period 1524, is increased. Because the combined length / size of one or more data frames and trigger frames transmitted by AP1406 in DL PPDU1518 is shorter than the period 1524, AP1406 may insert padding bits into DL PPDU1518. The padding bits may be inserted before or after the trigger frames contained in DL PPDU1518.

[0174] In an embodiment, AP1404 may receive UL PPDU 1520 from one or more associated STAs using the remaining duration of the allocated time 1510, according to any indication of MRTT frame 1508 (not shown in Figure 15). In an embodiment, AP1406 may receive UL PPDU 1522 from one or more associated STAs using the remaining duration of the allocated time 1510, according to any indication of MRTT frame 1508 (not shown in Figure 15). In an embodiment, as described above, frame 1508 may further indicate periods for UL PPDU 1520 and 1522. In an embodiment, AP1404 may signal a period to one or more associated STAs scheduled to transmit UL PPDU 1520. In an embodiment, AP1406 may signal a period to one or more associated STAs scheduled to transmit UL PPDU 1522.

[0175] In the embodiment, C-OFDMA may be used to transmit DL PPDUs 1516 and 1518, and UL PPDUs 1520 and 1522. Specifically, AP 1402 may assign APs 1404 and 1406 to mutually orthogonal frequency resources with respect to the allocated time 1510. For example, AP 1402 may divide an 80 MHz channel into two non-overlapping 40 MHz channels, each assigned to one of APs 1404 and 1406. In the embodiment, the frequency resources assigned to the APs are shown in the RU allocation subfield of the user information field (indicating the AP identifier) ​​in the MRTT frame 1508. Therefore, DL PPDUs 1516 and UL PPDUs 1520 may be transmitted on RUs orthogonal to the RUs used to transmit DL PPDUs 1518 and UL PPDUs 1522.

[0176] Figure 16 shows exemplary A control fields 1602 and 1604 that may be used in embodiments. A control fields 1602 and 1604 may be used to carry the number of STAs associated with the AP for UL transmission to the AP, and / or the length / size of the trigger frame included in DL transmission from the AP, within the QoS data / null frame. As shown in Figure 16, A control fields 1602 and 1604 may include a control ID field indicating the type of A control field 1602 and 1604. In embodiments, the control ID field may indicate that A control fields 1602 and 1604 include a BSR for DL ​​Cooperative Transmission ("C-BSR"). In embodiments, A control field 1602 includes a "UL STA count" field. The "UL STA count" field indicates the number of STAs associated with the AP for UL transmission to the AP, as described above. In embodiments, A control field 1604 includes a "trigger frame length" field. The "trigger frame length" field may include / indicate the length / size of the trigger frame included in DL transmission from the AP, as described above.

[0177] Figure 17 illustrates exemplary information elements 1702 and 1704 that may be used in embodiments. Information elements 1702 and 1704 may be used within an action frame to carry the number of STAs associated with the AP for a UL transmission to the AP, and / or the length / size of the trigger frame included in a DL transmission from the AP. As shown in Figure 17, information elements 1702 and 1704 may include an element ID field, a length field, and an element ID extension field. The element ID and element ID extension fields indicate the type of information elements 1702 and 1704. In embodiments, the element ID and element ID extension fields may indicate that information elements 1702 and 1704 include a BSR for DL ​​Cooperative Transmission ("C-BSR"). In embodiments, information element 1702 further includes a "UL STA count" field. The "UL STA count" field indicates the number of STAs associated with the AP for a UL transmission to the AP, as described above. In embodiments, information element 1704 further includes a "trigger frame length" field. The "Trigger Frame Length" field may include / indicate the length / size of the trigger frame included in the DL transmission from the AP, as described above.

[0178] Figure 18 illustrates an exemplary process 1800 according to an embodiment. The exemplary process 1800 may be carried out by a first AP, such as AP 1402 described above. As shown in Figure 18, process 1800 includes steps 1802 and 1804.

[0179] Step 1802 includes the first AP receiving a first frame from the second AP indicating an STA number (zero or greater). In embodiments, the first AP and the second AP may form a multi-AP group. In embodiments, the first AP may be the AP shared by the multi-AP group (or master AP), and the second AP may be the AP shared by the multi-AP group (or slave AP). STAs may be associated with the second AP. STAs whose number is indicated in the first frame may be STAs that the second AP wishes to receive from a UL transmission. STAs whose number is indicated in the first frame may be scheduled by the second AP for a UL transmission. A UL transmission may be part of a coordinated transmission. A coordinated transmission may include another UL transmission to the first AP or to a third AP. A coordinated transmission may be a C-OFDMA transmission. A coordinated transmission may be performed within the allocated time of a TXOP acquired by the first AP.

[0180] In one embodiment, the first frame may include an action frame. The action frame may include an information element that includes the STA number. In another embodiment, the first frame may include a QoS null or a data frame. The QoS null or data frame may include an A control field that includes the STA number.

[0181] Step 1804 includes the first AP sending a second frame to the second AP indicating a duration for a DL PPDU, which includes a trigger frame for transmission by the second AP to STAs (the number of which is indicated in the first frame). In embodiments, the duration is based on the number of STAs indicated in the first frame. In embodiments, the duration corresponds to the transmission duration of the DL PPDU. In embodiments, the trigger frame triggers an STA for a UL transmission. In embodiments, the DL PPDU is transmitted for a DL transmission. A DL transmission may be part of a coordinated transmission that includes a UL transmission.

[0182] In the embodiment, the second frame further indicates the allocated time of the TXOP acquired by the first AP. In the embodiment, the period is within the allocated time of the TXOP. In the embodiment, the second frame includes an MRTT frame or a multi-AP trigger frame. In the embodiment, the second frame further indicates the identifier of the second AP.

[0183] In an embodiment, the first frame may include a BSR. The BSR may be a C-OFDMA BSR. In an embodiment, process 1800 may further include sending a third frame requesting a BSR to a second AP and receiving the first frame in response to the third frame. The third frame may include a buffer status report polling (BSRP) trigger frame, a basic trigger frame, a polling frame, or a request frame.

[0184] Figure 19 illustrates another exemplary process 1900 according to an embodiment. The exemplary process 1900 may be carried out by a first AP such as AP 1402 described above. As shown in Figure 19, process 1900 includes steps 1902 and 1904.

[0185] Step 1902 includes the first AP receiving a first frame from the second AP indicating a first length of trigger frames for one or more STAs for transmission by the second AP in a DL PPDU. In embodiments, the first AP and the second AP may form a multi-AP group. In embodiments, the first AP may be a shared AP (or master AP) of the multi-AP group, and the second AP may be a shared AP (or slave AP) of the multi-AP group. One or more STAs may be associated with the second AP. One or more STAs may be STAs that the second AP wishes to receive from a UL transmission. In embodiments, the trigger frame triggers the STAs for a UL transmission.

[0186] A UL transmission may be part of a coordinated transmission. A coordinated transmission may include another UL transmission to a first AP or a third AP. A coordinated transmission may be a C-OFDMA transmission. A coordinated transmission may be performed within the allocated time of a TXOP acquired by the first AP. In embodiments, a DL PPDU is transmitted for a DL transmission. A DL transmission may be part of a coordinated transmission that includes a UL transmission.

[0187] The first length shown in the first frame may be preferred / recommended / selected by the second AP. The first length / size may be based on the number of one or more STAs. In embodiments, the first length is shown in bytes.

[0188] Step 1904 includes the first AP sending a second frame to the second AP indicating the duration of the DL PPDU. In one embodiment, the duration of the DL PPDU is based on a first length of the trigger frame. In another embodiment, the duration is based on a second length of the trigger frame. The second length may be based on the first length. The second length can be determined by the first AP.

[0189] In the embodiment, the second frame may further indicate the allocated time of the TXOP acquired by the first AP. In the embodiment, the duration of the first portion is within the allocated time. In the embodiment, the second frame may further include the identifier of the second AP.

[0190] Figure 20 illustrates another exemplary process 2000 according to an embodiment. The exemplary process 200 may be carried out by a first AP, such as AP 1404 or 1406 described above. As shown in Figure 20, process 2000 includes steps 2002 and 2004.

[0191] Step 2002 includes the first AP transmitting a first frame to the second AP indicating the number of STAs (zero or greater). In embodiments, the first and second APs may form a multi-AP group. In embodiments, the second AP may be the AP (or master AP) shared by the multi-AP group, and the first AP may be the AP (or slave AP) shared by the multi-AP group. STAs may be associated with the first AP. STAs whose number is indicated in the first frame may be STAs that the first AP wishes to receive from a UL transmission. STAs whose number is indicated in the first frame may be scheduled by the first AP for a UL transmission. A UL transmission may be part of a coordinated transmission. A coordinated transmission may include another UL transmission to the second AP or to a third AP. A coordinated transmission may be a C-OFDMA transmission. A coordinated transmission may be performed within the allocated time of a TXOP acquired by the second AP.

[0192] In one embodiment, the first frame may include an action frame. The action frame may include an information element that includes the STA number. In another embodiment, the first frame may include a QoS null or a data frame. The QoS null or data frame may include an A control field that includes the STA number.

[0193] Step 2004 includes the first AP receiving a second frame from the second AP indicating a duration for a DL PPDU, which includes a trigger frame for transmission by the first AP to STAs (the number of which is indicated in the first frame). In embodiments, the duration is based on the number of STAs indicated in the first frame. In embodiments, the duration corresponds to the transmission duration of the DL PPDU. In embodiments, the trigger frame triggers an STA for a UL transmission. In embodiments, the DL PPDU is transmitted for a DL transmission. A DL transmission may be part of a coordinated transmission that includes a UL transmission.

[0194] In the embodiment, the second frame further indicates the allocated time of the TXOP acquired by the second AP. In the embodiment, the period is within the allocated time of the TXOP. In the embodiment, the second frame includes an MRTT frame or a multi-AP trigger frame. In the embodiment, the second frame further indicates the identifier of the first AP.

[0195] In an embodiment, the first frame may include a BSR. The BSR may be a C-OFDMA BSR. In an embodiment, process 2000 may further include receiving a third frame requesting a BSR from a second AP and sending the first frame in response to the third frame. The third frame may include a buffer status report polling (BSRP) trigger frame, a basic trigger frame, a polling frame, or a request frame.

[0196] Figure 21 illustrates another exemplary process 2100 according to an embodiment. The exemplary process 2100 may be carried out by a first AP, such as AP 1404 or 1406 described above. As shown in Figure 21, process 2100 includes steps 2102 and 2204.

[0197] Step 2102 includes the first AP transmitting a first frame to the second AP indicating a first length of trigger frames for one or more STAs for transmission by the first AP in the DL PPDU. In embodiments, the first AP and the second AP may form a multi-AP group. In embodiments, the second AP may be a shared AP (or master AP) of the multi-AP group, and the first AP may be a shared AP (or slave AP) of the multi-AP group. One or more STAs may be associated with the first AP. One or more STAs may be STAs that the first AP wishes to receive from the UL transmission. In embodiments, the trigger frame triggers the STAs for the UL transmission.

[0198] A UL transmission may be part of a coordinated transmission. A coordinated transmission may include another UL transmission to a first AP or a third AP. A coordinated transmission may be a C-OFDMA transmission. A coordinated transmission may be performed within the allocated time of a TXOP acquired by the first AP. In embodiments, a DL PPDU is transmitted for a DL transmission. A DL transmission may be part of a coordinated transmission that includes a UL transmission.

[0199] The first length shown in the first frame may be preferred / recommended / selected by the second AP. The first length / size may be based on the number of one or more STAs. In embodiments, the first length is shown in bytes.

[0200] Step 2104 includes the first AP receiving a second frame from the second AP indicating the duration of the DL PPDU. In one embodiment, the duration of the DL PPDU is based on a first length of the trigger frame. In another embodiment, the duration is based on a second length of the trigger frame. The second length may be based on the first length. The second length can be determined by the second AP.

[0201] In the embodiment, the second frame may further indicate the allocated time of the TXOP acquired by the second AP. In the embodiment, the duration of the first portion is within the allocated time. In the embodiment, the second frame may further include the identifier of the first AP.

Claims

1. It is a method, The first access point (AP) receives a first frame from the second AP indicating the number of stations (STA) for an uplink (UL) transmission to the second AP, The first AP then sends the second AP, The allocated time of the transmission opportunity (TXOP) acquired by the first AP, The identifier of the AP above 2, A method comprising transmitting a second frame indicating a period for a downlink physical layer protocol data unit (DL PPDU) including a trigger frame for the STA within the allocated time, wherein the period is a period based on the number of STAs.

2. It is a method, The first access point (AP) receives a first frame indicating the number of stations (STAs) from the second AP, A method comprising: the first AP transmitting to the second AP a second frame indicating a period for a downlink physical layer protocol data unit (DL PPDU) which includes a trigger frame for transmission by the second AP to the STA.

3. The method according to claim 2, wherein the second frame further indicates the allocated time of a transmission opportunity (TXOP) acquired by the first AP.

4. The method according to claim 3, wherein the period is within the allocated time of the TXOP.

5. The method according to any one of claims 2 to 4, wherein the aforementioned period is based on the number of STAs.

6. The method according to claim 5, wherein the aforementioned period corresponds to the transmission duration of the DL PPDU.

7. The method according to any one of claims 2 to 6, wherein the length of the trigger frame is based on the number of STAs.

8. The method according to any one of claims 2 to 7, wherein the first frame includes a buffer status report (BSR).

9. The first AP transmits a third frame requesting the BSR to the second AP, The method according to claim 8, further comprising receiving the first frame from the second AP by the first AP in response to the third frame.

10. The method according to claim 9, wherein the third frame includes a buffer status report polling (BSRP) trigger frame, a basic trigger frame, a polling frame, or a request frame.

11. The method according to any one of claims 8 to 10, wherein the BSR includes a Cooperative Orthogonal Frequency Division Multi-Access (C-OFDMA) BSR.

12. The method according to any one of claims 2 to 11, wherein the STA is associated with the second AP.

13. The method according to any one of claims 2 to 12, wherein the STA is scheduled by the second AP for uplink (UL) transmission to the second AP.

14. The method according to claim 13, wherein the UL transmission occurs within the allocated time of a transmission opportunity (TXOP) acquired by the first AP.

15. The method according to claim 13 or 14, wherein the trigger frame triggers the STA for the UL transmission.

16. The method according to any one of claims 13 to 15, wherein the UL transmission is part of the C-OFDMA UL transmission.

17. The method according to any one of claims 2 to 16, wherein the second frame includes a multi-user transmit request trigger TXOP shared (MU-RTS TXS) trigger frame or a multi-AP trigger frame.

18. The method according to any one of claims 2 to 17, wherein the first frame includes an action frame.

19. The method according to claim 18, wherein the action frame includes an information element that includes the STA number.

20. The method according to any one of claims 2 to 17, wherein the first frame includes a quality of service (QoS) null or a data frame.

21. The method according to claim 20, wherein the QoS null or data frame includes an aggregate control (A-Control) field that includes the STA count.

22. It is a method, The first access point (AP) receives from the second AP a first frame indicating a first length of a trigger frame for one or more stations (STAs) for transmission by the second AP in a downlink physical layer protocol data unit (DL PPDU), The first AP then sends the second AP, The allocated time of the transmission opportunity (TXOP) acquired by the first AP, The identifier of the AP above 2, A method comprising transmitting a second frame indicating the duration of the DL PPDU within the allocated time.

23. The method according to claim 22, wherein the first length is selected by the second AP.

24. The method according to claim 22 or 23, wherein the first length is based on the number of the one or more STAs.

25. The method according to any one of claims 22 to 24, wherein the duration of the DL PPDU is based on the first length of the trigger frame.

26. The method according to claim 25, wherein the duration of the DL PPDU is based on the second length of the trigger frame.

27. The method according to claim 26, wherein the second length of the trigger frame is based on the first length of the trigger frame.

28. The method according to any one of claims 22 to 27, wherein the first length of the trigger frame is expressed in bytes.

29. It is a method, The first access point (AP) transmits to the second AP a first frame indicating the number of stations (STA) for the uplink (UL) transmission to the first AP, The first AP, from the second AP, The allocated time of the transmission opportunity (TXOP) acquired by the second AP, The identifier of the first AP, A method comprising receiving a second frame indicating a period for a downlink physical layer protocol data unit (DL PPDU) containing a trigger frame for the STA within the allocated time, wherein the period is based on the number of STAs.

30. It is a method, The first access point (AP) transmits a first frame indicating the number of stations (STAs) to the second AP, A method comprising: the first AP receiving from the second AP a second frame indicating a period for a downlink physical layer protocol data unit (DL PPDU) which includes a trigger frame for the STA.

31. The method according to claim 30, wherein the second frame further indicates the allocated time of a transmission opportunity (TXOP) acquired by the second AP.

32. The method according to claim 31, wherein the aforementioned period is within the allocated time of the TXOP.

33. The method according to any one of claims 30 to 32, wherein the aforementioned period is based on the number of STAs.

34. The method according to claim 33, wherein the aforementioned period corresponds to the transmission duration of the DL PPDU.

35. The method according to any one of claims 30 to 34, wherein the length of the trigger frame is based on the number of STAs.

36. The method according to any one of claims 30 to 35, wherein the first frame includes a buffer status report (BSR).

37. The first AP receives a third frame requesting the BSR from the second AP, The method according to claim 36, further comprising transmitting the first frame to the second AP by the first AP in response to the third frame.

38. The method according to claim 37, wherein the third frame includes a buffer status report polling (BSRP) trigger frame, a basic trigger frame, a polling frame, or a request frame.

39. The method according to any one of claims 36 to 38, wherein the BSR includes a Cooperative Orthogonal Frequency Division Multi-Access (C-OFDMA) BSR.

40. The method according to any one of claims 30 to 39, wherein the STA is associated with the first AP.

41. The method according to any one of claims 30 to 40, wherein the STA is scheduled by the first AP for uplink (UL) transmission to the first AP.

42. The method according to claim 41, wherein the UL transmission occurs within the allocated time of a transmission opportunity (TXOP) acquired by the second AP.

43. The method according to claim 41 or 42, wherein the trigger frame triggers the STA for the UL transmission.

44. The method according to any one of claims 41 to 43, wherein the UL transmission is part of the C-OFDMA UL transmission.

45. The method according to any one of claims 30 to 44, wherein the second frame includes a multi-user transmit request trigger TXOP shared (MU-RTS TXS) trigger frame or a multi-AP trigger frame.

46. The method according to any one of claims 30 to 45, wherein the first frame includes an action frame.

47. The method according to claim 46, wherein the action frame includes an information element that includes the STA number.

48. The method according to any one of claims 30 to 45, wherein the first frame includes a quality of service (QoS) null or a data frame.

49. The method according to claim 48, wherein the QoS null or data frame includes an aggregate control (A-Control) field that includes the STA number.

50. It is a method, The first access point (AP) transmits to the second AP a first frame indicating a first length of a trigger frame for one or more stations (STAs) for transmission by the first AP in a downlink physical layer protocol data unit (DL PPDU), The first AP, from the second AP, The allocated time of the transmission opportunity (TXOP) acquired by the second AP, The identifier of the first AP, A method comprising receiving a second frame indicating the duration of the DL PPDU within the allocated time.

51. The method according to claim 50, wherein the first length is selected by the first AP.

52. The method according to claim 50 or 51, wherein the first length is based on the number of the one or more STAs.

53. The method according to any one of claims 50 to 52, wherein the duration of the DL PPDU is based on the first length of the trigger frame.

54. The method according to claim 53, wherein the duration of the DL PPDU is based on the second length of the trigger frame.

55. The method according to claim 54, wherein the second length of the trigger frame is based on the first length of the trigger frame.

56. The method according to any one of claims 50 to 55, wherein the first length of the trigger frame is expressed in bytes.

57. It is a device, One or more processors, A device comprising a memory for storing instructions, wherein when an instruction is executed by one or more processors, the device causes the device to perform the method according to any one of claims 1 to 56.

58. A non-temporary computer-readable medium containing instructions, wherein when the instructions are executed by one or more processors, the one or more processors cause the one or more processors to carry out the method according to any one of claims 1 to 56.

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