Synchronization of TXS procedures between access points

Abstract

The first access point (AP) receives a frame from the second AP indicating the allocated time of the transmit opportunity (TXOP) acquired by the second AP, the identifier of the first AP, and a first period within the allocated time for downlink physical layer protocol data unit (DL PPDU) transmission. The first AP transmits the first DL PPDU during the first period for DL ​​PPDU transmission. In one embodiment, the DL PPDU transmission includes cooperative DL PPDU transmission.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 471,999, filed on June 9, 2023, which is hereby incorporated by reference in its entirety.

Summary of the Invention

Means for Solving the Problems

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

[0003] 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. 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.

[0004] In this disclosure, “a” and “an,” as well as 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 a multiple preferred possible embodiment, which may or may not be used 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” could mean A, B, C, A and B, A and C, B and C, or A, B, and C.

[0005] A is called a subset of B if A and B are a set and all elements of A are also elements 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 an embodiment of many preferred possibilities, which may or may not be used 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 an embodiment of many preferred possibilities, which may or may not be used in one or more of the various embodiments. The phrase "according to" (or equivalently "at least in accordance with") indicates that the phrase following the phrase "according to" is an embodiment of many preferred possibilities, which may or may not be used 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 an embodiment of many preferred possibilities, which may or may not be used in one or more of the various embodiments.

[0006] The term "configured" can relate to the capabilities of a device, whether it is operational or non-operational. "Configured" can refer to specific settings of a device that affect its operational characteristics, whether it is operational or non-operational. In other words, hardware, software, firmware, registers, memory values, and / or similar can be "configured" within a device, whether it is operational or non-operational, in order for the device to provide certain characteristics. Terms such as "control messages occurring in a device" can mean that control messages, whether the device is operational or non-operational, have parameters that can be used to configure certain characteristics in the device or to implement certain actions in the device.

[0007] 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, if parameter (IE) N contains parameter (IE) M, parameter (IE) M contains parameter (IE) K, and parameter (IE) K contains parameter (information element) J, then, for example, N contains K, and N contains J. In exemplary embodiments, if one or more messages / frames contain multiple parameters, it means that some of the multiple parameters are included in at least one of the one or more messages / frames, but not each of the one or more messages / frames.

[0008] Many of the features presented are described as optional through the use of "may" or parentheses. For brevity and readability, this disclosure does not expressly describe all possible combinations that can be obtained by selecting from a set of optional features. This disclosure should be construed as expressly disclosing all such variations. For example, a system described as having three optional features can be embodied in seven ways: by just one of the three possible features, by any two of the three features, or by three of the three features.

[0009] Many of the elements described in the disclosed embodiments can be implemented as modules, where a module is defined as an element that performs a defined function and has a defined interface to other elements. Modules described in this disclosure may be implemented in hardware, software combined with hardware, firmware, wetware (e.g., hardware with biological elements), or a combination thereof, and they can be behaviorally equivalent. For example, a module may be implemented in a hardware machine (such as C, C++, Fortran, Java®, Basic, Matlab®) or in software routines written in a computer language configured to run in a modeling / simulation program such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript. Modules may also be implemented 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 similar. FPGAs, ASICs, and CPLDs are often programmed using hardware description languages ​​(HDLs) such as VHSIC (VHDL) or Verilog, which constitute connections between internal hardware modules with fewer functionalities in the programmable device. The above techniques are often used in combination to achieve the results of functional modules. [Brief explanation of the drawing]

[0010] Some of the various embodiments of this disclosure are described herein with reference to the drawings.

[0011] [Figure 1] Figure 1 shows an exemplary wireless communication network in which embodiments of the present disclosure may be implemented. [Figure 2] Figure 2 is a block diagram showing an exemplary implementation of a station (STA) and an access point (AP). [Figure 3] Figure 3 shows an example of a Media Access Control (MAC) frame format. [Figure 4] Figure 4 shows an example of a Quality of Service (QoS) null frame that displays buffer status information. [Figure 5] Figure 5 shows an exemplary format for a Physical Layer (PHY) Protocol Data Unit (PPDU). [Figure 6] Figure 6 shows an example of a Multi-User Send Request (MU-RTS) trigger frame that may be used in a Triggered Send Opportunity (TXOP) Share (TXS) procedure. [Figure 7] Figure 7 shows an example of the TXS procedure (mode=1). [Figure 8] Figure 8 shows an example of the TXS procedure (mode = 2). [Figure 9] Figure 9 shows an example of a multi-AP network. [Figure 10] Figure 10 shows Cooperative Orthogonal Frequency Division Multiple Access (COFDMA). [Figure 11] Figure 11 shows an example illustrating the TXS procedure between APs. [Figure 12] Figure 12 shows an exemplary Physical Layer Protocol Data Unit (PPDU) that may be used for a Downlink (DL) PPDU or an Uplink (UL) PPDU. [Figure 13] Figure 13 is an example illustrating a potential problem that may occur in the AP-to-TXS procedure shown in Figure 11. [Figure 14] Figure 14 further illustrates the problem shown in Figure 13. [Figure 15] Figure 15 shows an example of an AP-to-TXS procedure according to one embodiment. [Figure 16]FIG. 16 shows an example of the AP - to - AP TXS procedure according to another embodiment. [Figure 17] FIG. 17 shows an example of the AP - to - AP TXS procedure according to another embodiment. [Figure 18] FIG. 18 shows an exemplary process according to one embodiment. [Figure 19] FIG. 19 shows another exemplary process according to one embodiment. **DETAILED DESCRIPTION OF THE INVENTION**

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

[0013] As shown in FIG. 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 (BSSs) 110 and 120, and 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, and STAs 106 - 2 and 106 - 3. The AP and at least one STA within a BSS perform an association procedure for communicating with each other.

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

[0016] The WLAN infrastructure network 102 can be coupled to one or more external networks. For example, as shown in FIG. 1, the WLAN infrastructure network 102 can be connected to another network 108 (e.g., 802.X) via a portal 140. The portal 140 can 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 shown in FIG. 1 can further include one or more ad hoc networks, or independent BSSs (IBSSs). An ad hoc network, or IBSS, is a network that includes a plurality of STAs within each other's communication range. The plurality of STAs are configured to communicate with each other using direct peer-to-peer communication (i.e., not via an AP).

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

[0019] An STA as a given functional medium can include a media access control (MAC) layer that complies with the IEEE 802.11 standard. A physical layer interface for the wireless medium can be used between an AP and a non-AP station (STA). An STA can also be referred to using various other terms, including a mobile terminal, a wireless device, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile subscriber unit, or a user. For example, the term "user" can 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) transmission.

[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 PLCP Service Data Unit (PSDU). For example, a PSDU may contain a PHY preamble, a header, and / or one or more MAC Protocol Data Units (MPDUs). The 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 via 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 in 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 modifications of the IEEE 802.11n, 802.11ac, 802.11ax, and / or 802.11be 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. The PPDU may be transmitted over a physical channel having a minimum bandwidth of 20 MHz. Larger channels may be formed through channel bonding. For example, 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 showing exemplary implementations of STA 210 and AP 260. As shown in Figure 2, STA 210 may include at least one processor 220, memory 230, and at least one transceiver 240. AP 260 may include at least one processor 270, memory 280, and at least one transceiver 290. Processors 220 / 270 may be 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 (STA 210 or AP 260). 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] The transceivers 240 / 290 may be configured to transmit / receive radio signals. In one embodiment, the transceivers 240 / 290 may implement the PHY layer of the corresponding device (STA 210 or AP 260). In one embodiment, the STA 210 and / or AP 260 may be multilink devices (MLDs), i.e., devices that can operate on multiple links as defined by the IEEE 802.11 standard. Thus, the STA 210 and / or AP 260 may each implement multiple PHY layers. Multiple PHY layers may be implemented using one or more of the transceivers 240 / 290.

[0026] The Target Wake Time (TWT) 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 assigned to 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 using an explicit TWT, the TWT requesting STA may wake up and perform a frame exchange. The TWT requesting STA may receive the next WT information in the response from the TWT responseing STA. When using an implicit WT, the TWT requesting STA may calculate the next WT 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 WT 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 WT 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 one embodiment, a TWT request STA waking up an implicit TWT SP may enter a dose state after the WTSP 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 shows an example 300 of the MAC frame format. 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 specific 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. For MAC frames, the value of the protocol version subfield is 0.

[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 within the subtype subfield are used to indicate a specific modification of the base 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 within 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 destined for the Distribution System (DS). The From DS subfield indicates whether the data frame originated from the DS.

[0038] In all data or management frames that have another follow-up fragment of a MAC Service Data Unit (MSDU) or MAC Management Protocol Data Unit (MMPDU) carried by a MAC frame, the Additional Fragment subfield is set to 1. This 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. When an STA is received, this metric is used to help in the process of removing duplicate frames. These rules do not apply to frames that the STA sends 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 (Bus) is being buffered for that STA by the AP. The Additional Data subfield is valid for individually addressed data or management frames sent to the STA by the AP in PS mode. The Additional Data subfield is set to 1 to indicate that at least one additional buffered BU exists for the STA.

[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 an 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 delay 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). Certain frames may not contain all of the address fields. The use of a particular address field can be determined by its relative position within the MAC header, regardless of the type of address present in that field. Specifically, the Address 1 field always identifies the intended receiver of the frame, and the Address 2 field, if present, always identifies the transmitter of the frame.

[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 A-MSDU. The sequence number subfield in a management frame indicates the sequence number of the frame. The fragment number subfield indicates the number of each fragment in the MSDU or MMPDU. The fragment number is set to 0 for the first fragment or only fragments of an MSDU or MMPDU, 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 A-MSDUs, or in MPDUs containing unfragmented MSDUs or MMPDUs. The fragment number remains constant across all retransmissions of fragments.

[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 can 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 is present in the QoS data, QoS null, and management frame, 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. It may contain 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 shows an example 400 of a Quality of Service (QoS) null frame displaying 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 include a Buffer Status Report (BSR) control subfield. A QoS null frame displaying buffer status information may be sent to the 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 Transmit Opportunity (TXOP) duration request subfield).

[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 queue size subfield. The encoding of the TID subfield is dependent 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 indicating the amount of buffered traffic for a given TC or TS at the STA for transmission to the AP, identified by the receiving address of the frame containing the subfield. The queue size subfield is present in QoS null frames transmitted by the STA when bit 4 of the QoS control field is set to 1. The AP may use the information contained in the queue size subfield to determine the TXOP duration allocated to the STA or 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 delivery queue (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. - The queue size value 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 the scaling factor subfield in bits B14-B15 of the QoS control field and the unscaled value (UV) in bits B8-B13 of the QoS control field. The scaling factor subfield provides the scaling factor.

[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= 16 × UV (if SF is equal to 0), 1024 + 256 × UV (if SF is equal to 1), 17 408 + 2048 × UV (if SF is equal to 2), 148 480 + 32 768 × UV (if SF is equal to 3 and UV is less than 62), >2 147 328 (when SF is equal to 3 and UV is equal to 62), Unspecified or unknown (if SF is equal to 3 and UV is equal to 63).

[0061] The TXOP Duration Request 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 Duration Request subfield is set to 0 to indicate that no TXOP is requested for the specified TID during the current service period (SP). The TXOP Duration Request subfield is set to a non-zero value to indicate requested TXOP durations in the range of 32us to 8160us in increments of 32us.

[0062] The HT control field may include a BSR control subfield that may 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 the queue size subfield, and is set to 0 except when the ACI bitmap subfield is 0 and the Delta TID subfield is 3, which means that 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 receiving address of the frame, including 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 the MSDUs and A-MSDUs associated with the ACs specified in the ACI high subfield and ACI bitmap subfield, respectively, 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 the ability to exchange MSDUs with peer entities. To support this service, the local MAC uses the underlying PHY-level service to transmit MSDUs to the peer MAC entity. This asynchronous MSDU transmission is performed without connection.

[0072] Figure 5 shows 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 traffic identifiers (TIDs) to specify differentiated services for each MSDU.

[0075] STA can differentiate MSDU deliveries according to the designated traffic category (TC) or traffic stream (TS) of each individual 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 considered 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 may deliver a Buffer Status Report (BSR) to help the AP allocate UL MU resources. The STA may implicitly deliver a BSR within the QoS control field or BSR control subfield of any frame sent to the AP (non-requested BSR), or it may explicitly deliver a BSR within a frame sent to the AP in response to a BSRP trigger frame (requested 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 of transmitted QoS null frames and QoS data frames to the AP in the QoS control field, and in the BSR control subfield (if any), as defined below, for transmitted QoS null frames, QoS data frames, and management frames.

[0080] The STA can 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 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 standard revision. TXS allows an AP to allocate a duration within an acquired TXOP to an STA for transmitting 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 one embodiment, if the triggered TXOP shared mode subfield is set to 1, the STA may send one or more non-TB PPDUs to the AP during the duration of the allocated time. In one embodiment, if the triggered TXOP shared mode subfield is set to 2, the STA may send one or more non-TB PPDUs to the AP or peer STA during the duration of the allocated time. A peer STA may be an STA that has a connection for peer-to-peer (P2P) communication or direct communication with an STA. In one embodiment, a direct wireless link is established according to the Tunnel Direct Link Setup (TDLS) protocol.

[0086] Figure 6 shows 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 a frame check sequence (FCS) field.

[0087] In one 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 one embodiment, the triggered TXOP shared mode subfield may be set to a non-zero value (e.g., 1 or 2). In one 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 allocated 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 allocated duration subfield of the user information field. In one embodiment, a peer STA may be an STA that has a P2P communication or direct communication connection with another STA.

[0090] The user information list field may contain one or more user information fields. In one 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 period, reservation, or PS160.

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

[0092] The RU assignment subfield may indicate the location and size of the RU assigned 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 shows an embodiment 700 of the TXS procedure (mode=1). As shown in Figure 7, the TXS procedure may be initiated by AP 710 and send an MRTT frame 720 to STA 711. The MRTT frame 720 may allocate a portion of the TXOP acquired by AP 710 to STA 711 and may indicate a TXS mode equal to 1. Upon receiving the MRTT frame 720, STA 711 may use the allocated time to send one or more non-TB PPDUs to AP 710. One or more non-TB PPDUs may include data frames, control frames, administration frames, or action frames.

[0095] In one 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 an allocated time. In one embodiment, the first period may be set to a value of X microseconds (µs).

[0096] STA 711 may respond to MRTT frame 720 by sending CTS frame 721 to AP 710. Subsequently, STA 711 may send non-TB PPDUs 722, 724 containing one or more data frames to AP 710 during the first period indicated in MRTT frame 720. In one embodiment, AP 710 may send one or more Blockack (BA) frames 723, 725 in response to one or more data frames contained in the non-TB PPDUs 722, 724 received from STA 711.

[0097] Figure 8 shows an embodiment 800 of the TXS procedure (mode = 2). As shown in Figure 8, the TXS procedure may be initiated by AP 810 and send an MRTT frame 820 to STA 811. The MRTT frame 820 may allocate a portion of the TXOP acquired by AP 810 to STA 811 and may represent a TXS mode equal to 2. Upon receiving the MRTT frame 820, STA 811 may use the allocated time to send one or more non-TB PPDUs to STA 812. One or more non-TB PPDUs may include data frames, control frames, management frames, or action frames.

[0098] In one 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 an allocated time. In one embodiment, the first period may be set to a value of X microseconds (µs).

[0099] STA 811 may respond to MRTT frame 820 by sending CTS frame 821 to AP 810. Subsequently, STA 811 may send non-TB PPDUs 822, 824 containing one or more data frames to STA 818 during the first period indicated in MRTT frame 720. In one embodiment, STA 812 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 STA 811.

[0100] Figure 9 shows an exemplary multi-AP network 900. An embodiment of the 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 actions 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 contain 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 for 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 via 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 this 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 transmissions may be a continuous period. Multi-AP transmissions may use different transmission techniques, such as cooperative OFDMA, cooperative space reuse, joint transmit and receive, cooperative beamforming and cooperative 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 the time and / or frequency sharing of 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 TXOP's time / frequency resources are shared with the other APs in the multi-AP group. In one 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 technology 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 (COFDMA), it is assumed that multiple APs (which may or may not include a coordinating AP) can coordinate multi-AP transmissions by allocating each of the multiple APs (e.g., a master AP) to each of the available frequency resources (e.g., a channel / subchannel) for the duration of the transmission. The coordinating AP may further specify transmission parameters (e.g., PPDU format, guard interval, symbol duration, etc.) for the multi-AP transmission. The multiple APs access their allocated frequency resources simultaneously using OFDMA during the transmission period. Figure 10 shows COFDMA as 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 COFDMA, 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 multiple APs. The multiple APs can, for example, transmit simultaneously to their respective associated STAs within the same period.

[0108] Future IEEE 802.11 standard drafts 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 time of the acquired TXOP 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 other shared APs without being triggered by the shared APs themselves. The shared APs may or may not be a portion of the APs communicating during the allocated time.

[0109] Figure 11 shows an example 1100 illustrating an AP-to-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 one embodiment, 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 AP-to-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, AP 1102 may acquire a TXOP. AP 1102 may then initiate inter-AP TXS operation by sending an MRTT frame 1110 to AP 1104. The MRTT frame 1110 may have a format similar to the MU-RTS trigger frame 600 described above. In one embodiment, the MRTT frame 1110 may indicate the identifier of AP 1104 (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 AP 1104 communicates with AP 1102 only during the allocated time 1132 (for example, when TXS mode is set to 1), or whether AP 1104 may communicate with AP 1102 or another STA (for example, the associated non-AP STA or another AP STA) during the allocated time 1132.

[0111] AP 1104 may respond to MRTT frame 1110 by sending CTS frame 1112 to AP 1102. Then, for example, in the short interframe space after sending CTS frame 1112, AP 1104 may use the allocated time 1132 for communication according to the TXS mode shown in MRTT frame 1110, without a trigger from AP 1102. In Embodiment 1100, the TXS mode may allow AP 1104 to communicate with AP 1102 or another STA during the allocated time 1132. Thus, as shown in Figure 11, AP 1104 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 one embodiment, along with the remaining time of the TXOP, AP 1102 may initiate another inter-AP TXS operation by sending an MRTT frame 1118 to APs 1106 and 1108. The MRTT frame 1118 may have a format similar to the MU-RTS trigger frame 600 described above. In one embodiment, the MRTT frame 1118 may indicate the identifiers of APs 1106 and 1108 (for example, 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 (for example, in the respective allocated duration subfield of the user information field). Furthermore, the MRTT frame 1118 may indicate the TXS mode (for example, the triggered TXOP shared mode subfield of the common information field of the MRTT frame 1118). The TXS mode may indicate whether APs 1106 and 1108 will communicate with AP 1102 only during the allocated time 1134 (for example, when the TXS mode is set to 1), or whether APs 1106 and 1108 may communicate with AP 1102 or other STAs (for example, related non-AP STAs or other AP STAs) during the allocated time 1134.

[0113] APs 1106 and 1108 may respond to the MRTT frame 1118 by sending CTS frames 1120 and 1122, respectively, to AP 1102. Subsequently, for example, after sending CTS frames 1120 and 1122, respectively, APs 1106 and 1108 may use the allocated time 1134 for communication according to the TXS mode indicated in the MRTT frame 1118, without a trigger from AP 1102. In embodiment 1100, the TXS mode may allow APs 1106 and 1108 to communicate with AP 1102 or another STA during the allocated time 1134. Thus, as shown in Figure 11, AP 1104 may use its allocated time 1134 to transmit (non-TB)DL PPDU 1124 to the relevant STA (not shown in Figure 11) and receive UL PPDU 1128 from the relevant STA (not shown in Figure 11). Similarly, AP 1108 may use its allocated time 1134 to transmit (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 one embodiment, COFDMA 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 80MHz channel into two non-overlapping 40MHz channels, each assigned to one of APs 1106 and 1108. In one example, the frequency resources assigned to the APs are shown in the RU assignment subfield of the user information field (indicating the AP identifier) ​​in the MRTT frame 1118. Thus, DL PPDUs 1124 and UL PPDUs 1128 may be transmitted over the RU, orthogonal to the RU, used for transmitting DL PPDUs 1126 and UL PPDUs 1130.

[0115] Figure 12 shows an exemplary PPDU 1200 that may be used for downlink DL PPDU or UL PPDU. For example, PPDU 1200 may be an embodiment of DL PPDU 1114, 1124, or 1126 described in Figure 11, or an embodiment of UL PPDU 1116, 1128, or 1130. PPDU 1200 may be an ultra-high reliability (UHR) PPDU that can be used by devices conforming to the IEEE 802.11bn standard revision. Such devices may operate in the 2.4, 5, and 6 GHz bands. In one implementation, PPDU 1200 may be transmitted over bandwidths up to 320 MHz. PPDU 1200 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 UHR PPDU 1200 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 PPDU 1200 receiver to synchronize with the PPDU 1200 transmitter's carrier frequency and frame timing, and to adjust the receiver signal gain.

[0118] L-LTF is used by the receiver of the PPDU 1200 to estimate channel coefficients in order to equalize the channel response (e.g., amplitude and phase distortion) in both the signal field (L-SIG, RL-SIG, U-SIG, UHR-SIG) and data field of the PPDU 1200.

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

[0120] The U-SIG ensures forward compatibility for PPDU 1200. This means that future PPDUs that are backward compatible with IEEE 802.11bn will include the same U-SIG field. Therefore, IEEE 802.11bn compliant devices will be able to understand PPDUs developed in future revisions, at least partially, provided that those revisions also include the U-SIG field.

[0121] The UHR-SIG includes a per-STA display of resource unit (RU) allocations. Receiving an STA allows the display within the UHR-SIG to position its payload within the data fields of the PPDU 1200.

[0122] The L-SIG, RL-SIG, U-SIG, and UHR-SIG fields can be considered the PHY headers of the PPDU 1200.

[0123] The UHR-STF and one or more UHR-LTFs are used by the receiver of the PPDU 1200 to equalize the channel response (e.g., amplitude and phase distortion) within the data field of the PPDU 1200 and to estimate the channel coefficients.

[0124] The data field contains one or more payloads carried by the PPDU 1200. One or more payloads may include MPDUs.

[0125] The PE field is an extension of the PPDU 1200 designed to give the receiver of the PPDU 1200 sufficient time to respond after receiving the PPDU 1200.

[0126] Figure 13 is an embodiment 1300 illustrating a problem that may occur in the AP-to-TXS procedure shown 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 AP-to-TXS operation by sending an MRTT frame 1118 to APs 1106 and 1108. The MRTT frame 1118 may have a format similar to the MU-RTS trigger frame 600 described above. In one embodiment, the MRTT frame 1118 may contain identifiers for APs 1106 and 1108 (e.g., in the respective AID subfields of the respective user information fields in the MRTT frame 1118) and the allocated time 1134 of the TXOP (e.g., in the respective allocated duration subfields of the user information fields). Furthermore, the MRTT frame 1118 may indicate TXS mode (e.g., the triggered TXOP shared mode subfield in the common information field of the MRTT frame 1118). The TXS mode may indicate whether APs 1106 and 1108 will communicate with AP 1102 only during the 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 the allocated time 1134.

[0127] APs 1106 and 1108 respond to MRTT frame 1118 by sending CTS frames 1120 and 1122 to AP 1102, respectively. Subsequently, for example, after sending CTS frames 1120 and 1122, respectively, APs 1106 and 1108 may use the allocated time 1134 for communication according to the TXS mode shown in MRTT frame 1118, without a trigger from AP 1102. In Embodiment 1300, the TXS mode may allow APs 1106 and 1108 to communicate with AP 1102 or another STA during the allocated time 1134. Thus, as shown in Figure 13, AP 1104 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, AP 1108 may use its 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 one embodiment, COFDMA may be used to transmit DL PPDUs 1302 and 1304, 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 80MHz channel into two non-overlapping 40MHz channels, each assigned to one of APs 1106 and 1108. In one example, the frequency resources assigned to the APs are shown in the RU assignment subfield of the user information field (indicating the AP identifier) ​​in the MRTT frame 1118. Thus, DL PPDUs 1302 and UL PPDUs 1306 may be transmitted over RUs that are orthogonal to the RUs used to transmit DL PPDUs 1304 and UL PPDUs 1308.

[0129] As shown in Figure 13, because APs 1106 and 1108 are not triggered by AP 1102 during the allocated time 1134, PPDUs 1302 and 1306 transmitted / received by AP 1106 during the allocated time 1134 may not be synchronized with PPDUs 1304 and 1308 transmitted / received by AP 1108. For example, DL PPDUs 1302 and 1304 may have the same transmission start time, but the transmission of DL PPDU 1302 may end at a later point than the transmission of DL PPDU 1304. Similarly, the transmission of UL PPDU 1308 may start before the transmission of UL PPDU 1306 begins. The lack of synchronization between transmitted PPDUs can lead to the receiving STA failing to decode the PPDU addressed to it, as time-overlapping PPDUs interfering with each other in the receiving STA. Figure 14 further illustrates this problem.

[0130] Figure 14 shows Embodiment 1400 in which UL PPDU 1306 and UL PPDU 1308 may interfere with each other due to a lack of synchronization between PPDUs transmitted during the allocated time 1134. In particular, Embodiment 1400 shows a situation in which the OFDM symbol of UL PPDU 1306 may be temporally misaligned with the OFDM symbol of UL PPDU 1308 due to the lack of synchronization. At the receiver, this OFDM symbol misalignment results in the boundary of the OFDM symbol received over the first part of the channel (e.g., the first 40 MHz) and the boundary of the corresponding OFDM symbol received over the second part of the channel (e.g., the second 40 MHz) being out of sync. Since the receiver typically receives and processes the entire channel (if there is no dedicated receive filter per subchannel), the receiver may be unable to decode PPDUs 1306 and 1308 where the OFDM symbol misalignment occurs.

[0131] Existing techniques for UL OFDMA transmissions to APs by multiple STAs propose maintaining OFDM symbol alignment at the AP by configuring multiple STAs to use the same OFDM symbol duration (including the same guard interval) for each UL transmission. The underlying assumption of this technique is that the AP triggers multiple STAs for each UL transmission to ensure that the STAs initiate each transmission in a synchronous manner. However, such an assumption may not always hold true in AP-to-AP TXS. In fact, a shared AP can initiate AP-to-AP TXS operation by sending a trigger frame, but the shared AP may use its allocated time for non-TB PPDU transmissions without any specific trigger from the shared AP for DL / UL transmissions during that time.

[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 shared AP may indicate in a trigger frame that it will initiate inter-AP TXS operation for at least one period within the allocated time for communication by the shared AP. At least one period may indicate a first period for DL ​​PPDU transmission. DL PPDU transmission may include coordinated DL PPDU transmission. In coordinated DL PPDU transmission, the shared AP may coordinate the transmission parameters of the DL PPDU to be transmitted for the coordinated DL PPDU transmission (e.g., PPDU format, guard interval, symbol duration, etc.). During the first period, the shared AP may transmit an aligned non-TB DL PPDU. At least one period may indicate a second period for UL PPDU transmission. UL PPDU transmission may include coordinated UL PPDU transmission. In cooperative UL PPDU transmission, the shared AP can adjust the transmission parameters of the UL PPDU sent for transmission (e.g., PPDU format, guard interval, symbol duration, etc.). The shared AP may receive the aligned UL PPDU during the second period. In another embodiment, the shared AP may indicate the number of iterations of the first and / or second period within the allocated time. Further embodiments and details of the embodiment are presented in the exemplary embodiments described below.

[0133] Figure 15 shows Example 1500 of an AP-to-TXS procedure according to one embodiment. As shown in Figure 15, Example 1500 includes APs 1502, 1504, and 1506. The exemplary APs 1502, 1504, and 1506 may form a multi-AP group as described above in Figure 9. In one embodiment, AP 1502 may be the master AP of the multi-AP group, and APs 1504 and 1506 may be slave APs of 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 master AP and slave APs.

[0134] In Example 1500, AP 1502 may acquire a TXOP. AP 1502 may then initiate inter-AP TXS operation by sending an MRTT frame 1508 to APs 1504 and 1506. The MRTT frame 1508 may have a format similar to the MU-RTS trigger frame 600 described above. In one embodiment, the MRTT frame 1508 may indicate the identifiers of APs 1504 and 1506 (for example, in the respective AID12 subfield of the respective user information field of the MRTT frame 1508), as well as the allocated time 1522 of the TXOP (for example, in the respective allocated duration subfield of the user information field). Furthermore, the MRTT frame 1508 may indicate the TXS mode (for example, in the triggered TXOP shared mode subfield of the common information field of the MRTT frame 1508). The TXS mode may indicate whether APs 1504 and 1506 will communicate with AP 1502 only during the allocated time 1522 (for example, when TXS mode is set to 1), or whether APs 1504 and 1506 may communicate with AP 1502 or other STAs (for example, related non-AP STAs or other AP STAs) during the allocated time 1522.

[0135] In one embodiment, the MRTT frame 1508 may further indicate a first period 1524 within the allocated time 1522 for DL ​​PPDU transmission. The DL PPDU transmission may be a coordinated DL PPDU transmission by AP 1502 and one or more of APs 1504 and 1506. Alternatively, the DL PPDU transmission may be a coordinated DL PPDU transmission by APs 1504 and 1506. As described above, in a coordinated DL PPDU transmission, AP 1502 may adjust various transmission parameters (e.g., PPDU format, guard interval, symbol duration, etc.) of the DL PPDU transmitted for the DL PPDU transmission. In another embodiment, the first period 1524 may be for UL PPDU transmission. The UL PPDU transmission may be a coordinated UL PPDU transmission which may or may not include AP 1502 as a receiver. In cooperative UL PPDU transmission, AP 1502 can adjust various transmission parameters of the UL PPDU being transmitted for UL PPDU transmission (e.g., PPDU format, guard interval, symbol duration, etc.).

[0136] In one embodiment, MRTT frame 1508 may include the duration of a first period 1524. In one embodiment, the start time of the first period 1524 may be determined based on MRTT frame 1508. For example, the start time of the first period 1524 may be the time from receiving MRTT frame 1508 to transmitting 2SIFS+CTS frames. The end time of the first period 1524 may be determined based on the start time and the indicated duration.

[0137] In another embodiment, the MRTT frame 1508 may include the start and end times of the first period 1524, the start and duration of the first period 1524, or the duration and end times of the first period 1524. In such an embodiment, the start time of the first period 1524 does not have to be based on the MRTT frame 1508.

[0138] In another embodiment, the MRTT frame 1508 may represent the first period 1524 as a segment of the allocated time 1522. For example, the MRTT frame 1508 may indicate that the first period 1524 corresponds to the first / last half of the allocated time 1522, or the first / last X microseconds of the allocated time 1522, etc.

[0139] In another embodiment, the MRTT frame 1508 may indicate the first period 1524 by indicating the number of OFDM symbols transmitted during the first period 1524 (of a given period).

[0140] In one embodiment, the MRTT frame 1508 may further indicate that the remainder of the allocated time 1522 following the first period 1524 is for DL ​​PPDU transmission. In another embodiment, the MRTT frame 1508 may further indicate that the remainder of the allocated time 1522 following the first period 1524 is for UL PPDU transmission. In a further embodiment, the MRTT frame 1508 may further indicate that the remainder of the allocated time 1522 following the first period 1524 is for DL ​​and / or UL PPDU transmission. In one embodiment, after the first period 1524, the remainder of the allocated time 1522 starts SIFS after the end of the first period 1524.

[0141] In one embodiment, information regarding the first period 1524 (e.g., duration, start time, end time, DL / UL, etc.) and / or information regarding the remaining period of the allocated time 1522 (e.g., UL / DL) may be carried in the common information field of MRTT frame 1508. For example, the information may be transmitted in the trigger-dependent common information subfield of the common information field. In another embodiment, information related to the first period 1524 and / or information related to the remaining period of the allocated time 1522 may be carried in the user information field of MRTT frame 1508. The user information field may indicate the identifier of the shared AP. In one embodiment, the information may be transmitted in the trigger-dependent user information subfield of the user information field. In a further embodiment, information related to the first period 1524 and / or information related to the remaining period of the allocated time 1522 may be carried in the special user information field of MRTT frame 1508. For example, the special user information field of MRTT frame 1507 may be identified by the AID12 value 2007. The AP does not have to use the AID12 value 2007 as the AID of any associated STA. In another embodiment, information related to the first period 1524 and / or information related to the remaining period of the allocated time 1522 may be carried in the Single Response Scheduling (SRS) control field of a QoS null frame, aggregated in the MRTT frame 1508. A one-bit field of the MRTT frame 1508 may indicate the presence of a QoS null frame having an SRS control field following the MRTT frame 1508.

[0142] In other embodiments, AP 1502 may initiate an AP-to-AP TXS operation by transmitting a frame other than an MRTT frame. For example, AP 1502 may use a multi-AP trigger frame to initiate an AP-to-AP TXS operation. The multi-AP trigger frame may contain / display the same information as contained in / displayed in the MRTT frame 1508. APs 1504 and 1506 may respond to the multi-AP trigger frame from AP 1502, acknowledge the information, or not.

[0143] APs 1504 and 1506 may respond to MRTT frame 1508 by sending CTS frames 1510 and 1512, respectively, to AP 1502. Subsequently, for example, after sending CTS frames 1510 and 1512, respectively, APs 1504 and 1506 may use the allocated time 1522 to communicate according to TXS mode, taking into account the first period 1524, as indicated in MRTT frame 1508, without a trigger from AP 1502. In Embodiment 1500, TXS mode may allow APs 1504 and 1506 to communicate with AP 1502 or another STA during the allocated time 1522. Thus, as shown in Figure 15, AP 1504 may use the first period 1524 of the allocated time 1522 to send a (non-TB) DL PPDU 1514 to the relevant STA (not shown in Figure 15). DL PPDU 1514 has a transmission period equal to the first period 1524. In one embodiment, AP 1504 may receive UL PPDU 1518 from the relevant STA using the remainder of the allocated time 1522, according to any representation of MRTT frame 1508 (not shown in Figure 15). Similarly, AP 1506 may transmit (non-TB)DL PPDU 1516 to the relevant STA using the first period 1524 (not shown in Figure 15). DL PPDU 1516 has a transmission period equal to the first period 1524. In one embodiment, AP 1506 may insert padding bits into the payload of DL PPDU 1516 so that the transmission period of PPDU 1516 is equal to the first period 1524. In one embodiment, AP 1506 may receive UL PPDU 1520 from the relevant STA using the remainder of the allocated time 1522, according to any representation of MRTT frame 1508 (not shown in Figure 15).

[0144] If APs 1504 and 1506 use (exactly) the first period 1524 to transmit DL PPDUs 1514 and 1516 respectively, then DL PPDUs 1514 and 1516 will have the same transmission start time and the same transmission end time. Therefore, assuming that DL PPDUs 1514 and 1516 use the same PPDU format, then DL PPDUs 1514 and 1516 may not interfere with each other at the receiver due to misalignment of OFDM symbols. Similarly, if UL PPDUs 1518 and 1520 are transmitted during the remainder of the allocated time 1522 (specifically, following the first period 1524), then UL PPDUs 1518 and 1520 will have the same transmission start time and the same transmission end time. Assuming that UL PPDU 1518 and 1520 use the same PPDU format, UL PPDU 1518 and 1520 may not interfere with each other at the receiver (e.g., AP 1504 or AP 1506) due to misalignment of OFDM symbols. Furthermore, since DL PPDU 1514 and 1516 do not overlap temporally with UL PPDU 1520 and 1518, respectively, there may be no interference between DL PPDU 1514 and UL PPDU 1520, or between DL PPDU 1516 and UL PPDU 1518.

[0145] In one embodiment, COFDMA may be used to transmit DL PPDUs 1514 and 1516, and UL PPDUs 1518 and 1520. Specifically, AP 1502 may assign APs 1504 and 1506 to their respective frequency resources, orthogonal to each other for the allocated time 1522. For example, AP 1502 may divide an 80MHz channel into two non-overlapping 40MHz channels, each assigned to one of APs 1504 and 1506. In one example, the frequency resources assigned to the APs are shown in the RU assignment subfield of the user information field (indicating the AP identifier) ​​in the MRTT frame 1508. Thus, DL PPDUs 1514 and UL PPDUs 1518 may be transmitted on RUs orthogonal to the RUs used to transmit DL PPDUs 1516 and UL PPDUs 1520.

[0146] Figure 16 shows an example of the inter-AP TXS procedure according to another embodiment. As shown in Figure 16, Example 1600 also includes APs 1502, 1504, and 1506, as described above in Figure 15.

[0147] In Example 1600, AP 1502 may acquire a TXOP. AP 1502 may then initiate inter-AP TXS operation by sending an MRTT frame 1602 to APs 1504 and 1506. The MRTT frame 1602 may have a format similar to the MU-RTS trigger frame 600 described above. In one embodiment, the MRTT frame 1602 may indicate the identifiers of APs 1504 and 1506 (for example, in the respective AID12 subfields of the respective user information fields of the MRTT frame 1602), as well as the allocated time 1616 of the TXOP (for example, in the respective allocated duration subfields of the user information fields). Furthermore, the MRTT frame 1602 may indicate the TXS mode (for example, in the triggered TXOP shared mode subfield of the common information field of the MRTT frame 1602). The TXS mode may indicate whether APs 1504 and 1506 will communicate with AP 1502 only during the allocated time 1616 (for example, when TXS mode is set to 1), or whether APs 1504 and 1506 may communicate with AP 1502 or other STAs (for example, related non-AP STAs or other AP STAs) during the allocated time 1616.

[0148] In one embodiment, MRTT frame 1602 may further indicate a first period 1618 within the allocated time 1616 for DL ​​PPDU transmission. DL PPDU transmission may be a coordinated DL PPDU transmission by AP 1502 and one or more of APs 1504 and 1506. Alternatively, DL PPDU transmission may be a coordinated DL PPDU transmission by APs 1504 and 1506. As described above, in a coordinated DL PPDU transmission, AP 1502 may adjust various transmission parameters (e.g., PPDU format, guard interval, symbol duration, etc.) of the DL PPDU transmitted for DL ​​PPDU transmission. In another embodiment, the first period 1618 may be for UL PPDU transmission. UL PPDU transmission may be a coordinated UL PPDU transmission which may or may not include AP 1502 as a receiver. In cooperative UL PPDU transmission, AP 1502 can adjust various transmission parameters of the UL PPDU being transmitted for UL PPDU transmission (e.g., PPDU format, guard interval, symbol duration, etc.).

[0149] In one embodiment, MRTT frame 1602 may include the duration of a first period 1618. In one embodiment, the start time of the first period 1618 may be determined based on MRTT frame 1602. For example, the start time of the first period 1618 may be the time from receiving MRTT frame 1602 to transmitting a 2SIFS+CTS frame. The end time of the first period 1618 may be determined based on the start time and the indicated duration.

[0150] In another embodiment, the MRTT frame 1602 may include the start and end times of the first period 1618, the start and duration of the first period 1618, or the duration and end times of the first period 1618. In such an embodiment, the start time of the first period 1618 does not have to be based on the MRTT frame 1602.

[0151] In another embodiment, the MRTT frame 1602 may represent the first period 1618 as a segment of the allocated time 1616. For example, the MRTT frame 1602 may indicate that the first period 1618 corresponds to the first / last half of the allocated time 1616, or the first / last X microseconds of the allocated time 1616, etc.

[0152] In another embodiment, the MRTT frame 1602 may indicate the first period 1618 by indicating the start or end time of the first period 1618 and the number of OFDM symbols transmitted during the first period 1618 (of a given period).

[0153] In one embodiment, MRTT frame 1602 may further indicate a second period 1620 within the allocated time 1616 for UL PPDU transmission. The second period 1620 may follow or precede the first period 1618. The UL PPDU transmission may be a coordinated UL PPDU transmission by AP 1502 and one or more of APs 1504 and 1506. Alternatively, the UL PPDU transmission may be a coordinated UL PPDU transmission by APs 1504 and 1506. As described above, in a coordinated UL PPDU transmission, AP 1502 may adjust various transmission parameters (e.g., PPDU format, guard interval, symbol duration, etc.) of the UL PPDU transmitted for the UL PPDU transmission. In another embodiment, the second period 1620 may be for DL ​​PPDU transmission. DL PPDU transmission can be a cooperative DL PPDU transmission, which may or may not include AP 1502 as a transmitter. In cooperative DL PPDU transmission, AP 1502 can adjust various transmission parameters (e.g., PPDU format, guard interval, symbol duration, etc.) of the DL PPDU transmitted for DL ​​PPDU transmission.

[0154] In one embodiment, MRTT frame 1602 may include the duration of a second period 1620. In one embodiment, the start time of the second period 1620 may be determined based on MRTT frame 1602 and / or the first period 1618. For example, the start time of the second period 1618 may be SIFS after the first period 1618 (which may or may not be based on MRTT frame 1602 as described above). The end time of the second period 1620 may be determined based on the start time and the indicated duration.

[0155] In another embodiment, the MRTT frame 1602 may include the start and end times of the second period 1620, the start and duration of the second period 1620, or the duration and end times of the second period 1620. In such an embodiment, the start time of the second period 1620 may not be based on the MRTT frame 1602 and / or the first period 1618.

[0156] In another embodiment, MRTT frame 1602 may represent the second period 1620 as a segment of the allocated time 1616. For example, MRTT frame 1602 may indicate that the second period 1620 corresponds to the first / last half of the allocated time 1616, or the first / last X microseconds of the allocated time 1616, etc.

[0157] In another embodiment, the MRTT frame 1602 may indicate the second period 1620 by indicating the start or end time of the second period 1620 and the number of OFDM symbols transmitted during the first period 1618 (of a given period).

[0158] In one embodiment, MRTT frame 1602 may further indicate that the remainder of the allocated time 1616 following the second period 1620 is for DL ​​PPDU transmission. In another embodiment, MRTT frame 1602 may further indicate that the remainder of the allocated time 1616 following the second period 1620 is for UL PPDU transmission. In a further embodiment, MRTT frame 1602 may further indicate that the remainder of the allocated time 1616 after the second period 1620 is for DL ​​and / or UL PPDU transmission. In one embodiment, the remainder of the allocated time 1616 after the second period 1620 starts SIFS after the end of the second period 1620.

[0159] In one embodiment, information regarding the first period 1618 (e.g., duration, start time, end time, DL / UL, etc.), the second period 1620 (e.g., duration, start time, end time, DL / UL, etc.), and / or the remaining period of the allocated time 1616 (e.g., UL / DL) may be carried in the common information field of MRTT frame 1602. For example, the information may be transmitted in the trigger-dependent common information subfield of the common information field. In another embodiment, information regarding the first period 1618, the second period 1620, and / or the remaining duration of the allocated time 1616 may be carried in the user information field of MRTT frame 1602. The user information field may indicate the identifier of the shared AP. In one embodiment, the information may be transmitted in the trigger-dependent user information subfield of the user information field. In a further embodiment, information relating to the first period 1618, the second period 1620, and / or the remaining period of the allocated time 1616 may be carried in the special user information field of MRTT frame 1602. For example, the special user information field of MRTT frame 1602 may be identified by an AID12 value of 2007. The AP does not have to use the AID12 value 2007 as the AID of any associated STA. In another embodiment, information regarding the first period 1618, the second period 1620, and / or the remainder of the allocated time 1616 may be carried in the SRS control field of a QoS null frame, aggregated in MRTT frame 1602. A 1-bit field of MRTT frame 1602 may indicate the presence of a QoS null frame having an SRS control field following MRTT frame 1602.

[0160] In other embodiments, AP 1502 may initiate an AP-to-AP TXS operation by transmitting a frame other than an MRTT frame. For example, AP 1502 may use a multi-AP trigger frame to initiate an AP-to-AP TXS operation. The multi-AP trigger frame may contain / show the same information as contained / shown in MRTT frame 1602. APs 1504 and 1506 may respond to the multi-AP trigger frame from AP 1502, acknowledge the information, or not.

[0161] APs 1504 and 1506 may respond to MRTT frame 1602 by sending CTS frames 1604 and 1606, respectively, to AP 1502. Subsequently, for example, after sending CTS frames 1604 and 1606, respectively, APs 1504 and 1506 may use the allocated time 1616 for communication, according to the TXS mode indicated in MRTT frame 1602, and considering the first period 1618 and the second period 1620, without a trigger from AP 1502. In embodiment 1600, the TXS mode may allow APs 1504 and 1506 to communicate with AP 1502 or another STA during the allocated time 1616. Thus, as shown in Figure 16, AP 1504 may transmit a (non-TB)DL PPDU 1608 to the associated STA using a first period 1618 of the allocated time 1616 (not shown in Figure 16). The DL PPDU 1608 has a transmission period equal to the first period 1618. In one embodiment, AP 1504 may insert padding bits into the payload of the DL PPDU 1608 to ensure that the transmission period of the PPDU 1608 is equal to the first period 1618. Similarly, AP 1506 may transmit a (non-TB)DL PPDU 1610 to the associated STA using a first period 1618 (not shown in Figure 16). The DL PPDU 1610 has a transmission period equal to the first period 1618.

[0162] Subsequently, AP 1504 may use the second period 1620 to receive UL PPDU 1612 from the associated STA (not shown in Figure 16). Similarly, AP 1506 may use the second period 1620 to receive UL PPDU 1614 from the associated STA (not shown in Figure 16). In one embodiment, the transmitter of UL PPDU 1614 may insert padding bits into the payload of UL PPDU 1614 so that the transmission period of PPDU 1614 is equal to the second period 1620.

[0163] In one embodiment, AP 1504 may transmit / receive DL / UL PPDUs using the remainder of the allocated time 1616, according to any representation of MRTT frame 1602 (not shown in Figure 16). Similarly, AP 1506 may transmit / receive DL / UL PPDUs using the remainder of the allocated time 1616, according to any representation of MRTT frame 1602 (not shown in Figure 16).

[0164] APs 1504 and 1506 use (exactly) the first period 1618 to transmit DL PPDUs 1608 and 1610, respectively, and DL PPDUs 1608 and 1610 have the same transmission start time and the same transmission end time. Therefore, assuming that DL PPDUs 1608 and 1610 use the same PPDU format, DL PPDUs 1608 and 1610 may not interfere with each other due to misalignment of OFDM symbols at the receiver. Similarly, if UL PPDUs 1612 and 1614 are transmitted during (exactly) the second period 1620, UL PPDUs 1612 and 1614 have the same transmission start time and the same transmission end time. Assuming that UL PPDU 1612 and 1614 use the same PPDU format, UL PPDU 1612 and 1614 may not interfere with each other due to misalignment of OFDM symbols in the receiver (e.g., AP 1504 or AP 1506). Furthermore, since DL PPDU 1608 and 1610 do not overlap temporally with UL PPDU 1614 and 1612, respectively, there may be no interference between DL PPDU 1608 and UL PPDU 1610, or between DL PPDU 1614 and UL PPDU 1612.

[0165] In one embodiment, COFDMA may be used to transmit DL PPDU 1608 and 1610, and UL PPDU 1612 and 1614. Specifically, AP 1502 may assign APs 1504 and 1506 to their respective frequency resources that are orthogonal to each other for the allocated time 1616. For example, AP 1502 may divide an 80MHz channel into two non-overlapping 40MHz channels, each assigned to one of APs 1504 and 1506. In one embodiment, the frequency resources assigned to the APs are shown in the RU assignment subfield of the user information field (indicating the AP identifier) ​​in the MRTT frame 1602. Thus, DL PPDU 1608 and UL PPDU 1612 may be transmitted over the RU, orthogonal to the RU, used for transmitting DL PPDU 1610 and UL PPDU 1614.

[0166] Figure 17 shows Example 1700 of the inter-AP TXS procedure according to another embodiment. As shown in Figure 17, Example 1700 also includes APs 1502, 1504 and 1506, as described above in Figure 15.

[0167] In Example 1700, AP 1502 may acquire a TXOP. AP 1502 may then initiate inter-AP TXS operation by sending an MRTT frame 1702 to APs 1504 and 1506. The MRTT frame 1702 may have a format similar to the MU-RTS trigger frame 600 described above. In one embodiment, the MRTT frame 1702 may indicate the identifiers of APs 1504 and 1506 (for example, in the respective AID12 subfield of the respective user information field of the MRTT frame 1702), as well as the allocated time 1716 of the TXOP (for example, in the respective allocated duration subfield of the user information field). Furthermore, the MRTT frame 1702 may indicate the TXS mode (for example, the triggered TXOP shared mode subfield of the common information field of the MRTT frame 1702). The TXS mode may indicate whether APs 1504 and 1506 will communicate with AP 1502 only during the allocated time 1716 (for example, when TXS mode is set to 1), or whether APs 1504 and 1506 may communicate with AP 1502 or other STAs (for example, related non-AP STAs or other AP STAs) during the allocated time 1716.

[0168] In one embodiment, the MRTT frame 1702 may further indicate a plurality of first periods 1718-1, ..., 1718-n within the allocated time 1716 for each DL PPDU transmission. The DL PPDU transmission for each DL PPDU transmission may be a coordinated DL PPDU transmission by AP 1502 and one or more of APs 1504 and 1506. Alternatively, the DL PPDU transmission may be a coordinated DL PPDU transmission by APs 1504 and 1506. As described above, in a coordinated DL PPDU transmission, AP 1502 may adjust various transmission parameters (e.g., PPDU format, guard interval, symbol duration, etc.) of the DL PPDU transmitted for the DL PPDU transmission. In another embodiment, the first period 1718 may be for each UL PPDU transmission. Each UL PPDU transmission may be a cooperative UL PPDU transmission, which may or may not include AP 1502 as a receiver. In a cooperative UL PPDU transmission, AP 1502 can adjust various transmission parameters (e.g., PPDU format, guard interval, symbol duration, etc.) of the UL PPDU transmitted for the UL PPDU transmission.

[0169] In one embodiment, the MRTT frame 1702 may include one or more durations from the first periods 1718-1, ..., 1718-n. The first periods 1718-1, ..., 1718-n may or may not have equal durations.

[0170] In one embodiment, the start time of the first period 1718-1, ..., and / or 1718-n may be determined based on MRTT frame 1702. For example, the start time of the first period 1718-1, ..., and / or 1718-n may be 2SIFS plus the CTS frame transmission time and X microseconds from the time MRTT frame 1702 (where 0 ≤ X ≤ allocated time 1716) is received. The end time of the first period 1718-1, ..., and / or 1718-n may be determined based on the start time and the indicated duration.

[0171] In another embodiment, the MRTT frame 1702 may include the start and end times of a first period 1718-1, ..., and / or 1718-n, the start and duration of a first period 1718-1, ..., and / or 1718-n, or the duration and end times of a first period 1718-1, ..., and / or 1718-n. In such an embodiment, the start times of the first periods 1718-1, ..., and / or 1718-n may not be based on the MRTT frame 1702.

[0172] In another embodiment, MRTT frame 1702 may represent a first period 1718-1, ..., and / or 1718-n as segments of the allocated time 1716. For example, MRTT frame 1702 may indicate that the first period 1718-1, ..., and / or 1718-n corresponds to the first / last half of the allocated time 1716, or the first / last X microseconds of the allocated time 1716, etc.

[0173] In another embodiment, the MRTT frame 1702 may indicate the first periods 1718-1, ..., and / or 1718-n by indicating the start or end time of each first period 1718-1, ..., and / or 1718-n, as well as the number of OFDM symbols transmitted during the first periods 1718-1, ..., and / or 1718-n (a given period).

[0174] In one embodiment, the MRTT frame 1702 may further indicate a plurality of second periods 1720-1, ..., 1720-n within the allocated time 1716 for each UL PPDU transmission. The second periods 1720-1, ..., 1720-n may follow or precede the first periods 1718-1, ..., 1718-n, or may be interleaved with the first periods 1718-1, ..., 1718-n. For example, as shown in Figure 17, the first periods 1718-1, ..., 1718-n and the second periods 1720-1, ..., 1720-n may be interleaved to have repeating period pairs including the first period 1718 and the second period 1720. Each UL PPDU transmission may be a coordinated UL PPDU transmission by AP 1502 and one or more of APs 1504 and 1506. Alternatively, the UL PPDU transmission may be a coordinated UL PPDU transmission by APs 1504 and 1506. As described above, in a coordinated UL PPDU transmission, AP 1502 can adjust various transmission parameters (e.g., PPDU format, guard interval, symbol duration, etc.) of the UL PPDU transmitted for the UL PPDU transmission. In another embodiment, the second period 1720-1, ..., 1720-n may be for each DL PPDU transmission. Each DL PPDU transmission may be a coordinated DL PPDU transmission that may or may not include AP 1502 as a transmitter. In cooperative DL PPDU transmission, AP 1502 can adjust various transmission parameters of the DL PPDU sent for DL ​​PPDU transmission (e.g., PPDU format, guard interval, symbol duration, etc.).

[0175] In one embodiment, the MRTT frame 1702 may include one or more durations from among the second periods 1720-1, ..., 1720-n. The second periods 1720-1, ..., 1720-n may or may not have equal durations. Each of the second periods 1720-1, ..., 1720-n may or may not have a duration equal to the first period 1718-1, ..., 1718-n.

[0176] In one embodiment, the start time of the second period 1720-1, ..., and / or 1720-n may be determined based on MRTT frame 1702, and / or each of the first periods 1718-1, ..., and / or 1718-n. For example, the start time of the second period 1720-1, ..., and / or 1720-n may each be an SIFS after the first period 1718-1, ..., and / or 1718-n (which may or may not be based on MRTT frame 1702 as described above). The end time of the second period 1720-1, ..., and / or 1720-n may be determined based on the start time and the indicated duration.

[0177] In another embodiment, the MRTT frame 1702 may include the start and end times of a second period 1720-1, ..., and / or 1720-n, the start and duration of a second period 1720-1, ..., and / or 1720-n, or the duration and end times of a second period 1720-1, ..., and / or 1720-n. In such an embodiment, the start times of a second period 1720-1, ..., and / or 1720-n may not be based on the MRTT frame 1702, and / or each of the first periods 1718-1, ..., and / or 1718-n.

[0178] In another embodiment, MRTT frame 1702 may indicate second periods 1720-1, ..., and / or 1720-n as segments of the allocated time 1716. For example, MRTT frame 1702 may indicate that the second periods 1720-1, ..., and / or 1720-n correspond to the first / last half of the allocated time 1716, or the first / last X microseconds of the allocated time 1716, etc.

[0179] In another embodiment, the MRTT frame 1702 may indicate the second period 1720-1, ..., and / or 1720-n by indicating the start or end time of the second period 1720-1, ..., and / or 1720-n, as well as the number of OFDM symbols transmitted during the first period 1720-1, ..., and / or 1720-n (a given period).

[0180] In one embodiment, the MRTT frame 1702 may represent a single pair of first periods (e.g., first period 1718-1) and second periods (e.g., 1720-1), as well as an iteration count indicating the number of times the pair of first and second periods is repeated within the allocated time 1716. For example, an iteration count equal to 0 indicates that the pair of first and second periods is not repeated within the allocated time 1716. An iteration count equal to 1 indicates that the pair of first and second periods is repeated once within the allocated time 1716. The period separating the consecutive pair of first and second periods may be equal to SIFS and or any other value that may be represented in the MRTT frame 1702.

[0181] In one embodiment, MRTT frame 1702 may further indicate that the remainder of the allocated time 1716, following the first period 1718-1, ..., 1718-n and the second period 1720-1, ..., 1720-n, is for DL ​​PPDU transmission. In another embodiment, MRTT frame 1702 may further indicate that the remainder of the allocated time 1716, following the first period 1718-1, ..., 1718-n and the second period 1720-1, ..., 1720-n, is for UL PPDU transmission. In a further embodiment, MRTT frame 1702 may further indicate that the remainder of the allocated time 1716, following the first period 1718-1, ..., 1718-n and the second period 1720-1, ..., 1720-n, is for DL ​​and / or UL PPDU transmission. In one embodiment, the remaining period of the allocated time 1716, following the first period 1718-1, ..., 1718-n and the second period 1720-1, ..., 1720-n, starts SIFS after the end of the first period 1718-1, ..., 1718-n and the second period 1720-1, ..., 1720-n.

[0182] In one embodiment, information relating to the first period 1718-1, ..., 1718-n (e.g., duration, start time, end time, DL / UL, etc.), the second period 1720-1, ..., 1720-n (e.g., duration, start time, end time, DL / UL, etc.), the remaining period of the allocated time 1716 (e.g., UL / DL), and / or the number of iterations may be carried in the common information field of the MRTT frame 1702. For example, the information may be transmitted in the trigger-dependent common information subfield of the common information field. In another embodiment, information relating to the first period 1718-1, ..., 1718-n, the second period 1720-1, ..., 1720-n, the remaining period of the allocated time 1716, and / or the number of iterations may be carried in the user information field of the MRTT frame 1702. The user information field may indicate the identifier of the shared AP. In one embodiment, the information may be transmitted in the trigger-dependent user information subfield of the user information field. In a further embodiment, information regarding the first period 1718-1, ..., 1718-n, the second period 1720-1, ..., 1720-n, the remaining period of the allocated time 1716, and / or the number of iterations may be carried in the special user information field of the MRTT frame 1702. For example, the special user information field of the MRTT frame 1702 may be identified by the AID12 value 2007. The AP does not have to use the AID12 value 2007 as the AID of any STA associated with it. In another embodiment, information regarding the first period 1718-1, ..., 1718-n, the second period 1720-1, ..., 1720-n, the remaining period of the allocated time 1716, and / or the number of iterations may be carried in the SRS control field of the QoS null frame, which is aggregated in the MRTT frame 1702. The single bit field of MRTT frame 1702 may indicate the presence of a QoS null frame following MRTT frame 1702, which has an SRS control field.

[0183] In other embodiments, AP 1502 may initiate an AP-to-AP TXS operation by transmitting a frame other than an MRTT frame. For example, AP 1502 may use a multi-AP trigger frame to initiate an AP-to-AP TXS operation. The multi-AP trigger frame may contain / show the same information as contained / shown in MRTT frame 1602. APs 1504 and 1506 may respond to the multi-AP trigger frame from AP 1502, acknowledge the information, or not.

[0184] APs 1504 and 1506 may respond to MRTT frame 1702 by sending CTS frames 1704 and 1706, respectively, to AP 1502. Subsequently, for example, after sending CTS frames 1704 and 1706, respectively, APs 1504 and 1506 may use their allocated time 1716 for communication, without trigger from AP 1502, according to the TXS mode shown in MRTT frame 1702, considering a first period 1718-1, ..., 1718-n and a second period 1720-1, ..., 1720-n. In embodiment 1700, the TXS mode may allow APs 1504 and 1506 to communicate with AP 1502 or another STA during their allocated time 1716. Thus, as shown in Figure 17, AP 1504 may transmit (non-TB)DL PPDU 1708-1 to the relevant STA using a first period 1718-1 (not shown in Figure 17). DL PPDU 1708-1 has a transmission period equal to the first period 1718-1. Similarly, AP 1506 may transmit (non-TB)DL PPDU 1710-1 to the relevant STA using a first period 1718-1 (not shown in Figure 17). DL PPDU 1710-1 has a transmission period equal to the first period 1718-1. DL PPDU 1708-1 and / or DL ​​PPDU 1710-1 may include padding bits to ensure that the transmission periods of both DL PPDU 1708-1 and DL PPDU 1710-1 are equal to the first period 1718-1.

[0185] Subsequently, AP 1504 may receive UL PPDU 1712-1 from the relevant STA using the second period 1720-1 (not shown in Figure 17). Similarly, AP 1506 may receive UL PPDU 1714-1 from the relevant STA using the second period 1720-1 (not shown in Figure 17). UL PPDU 1712-1 and / or UL PPDU 1714-1 may include padding bits to ensure that the transmission periods of both UL PPDU 1712-1 and UL PPDU 1714-1 are equal to the second period 1720-1.

[0186] The same operation described above for the first period 1718-1 and the second period 1720-1 may then be repeated for the subsequent first period 1718-2, ..., 1718-n and the second period 1720-2, ..., 1720-n.

[0187] In one embodiment, AP 1504 may transmit / receive DL / UL PPDUs using the remainder of the allocated time 1716, according to any representation of MRTT frame 1702 (not shown in Figure 17). Similarly, AP 1506 may transmit / receive DL / UL PPDUs using the remainder of the allocated time 1716, according to any representation of MRTT frame 1702 (not shown in Figure 17).

[0188] With APs 1504 and 1506 using (exactly) the first period 1718-1, ..., 1718-n to transmit DL PPDUs 1708-1, ..., 1708-n and 1710-1, ..., 1710-n respectively, DL PPDUs 1708-1, ..., 1708 have the same transmission start time and the same transmission end time as DL PPDUs 1710-1, ..., 1710-n, respectively. Therefore, assuming that DL PPDU 1708-1, ..., 1708-n and DL PPDU 1710-1, ..., 1710-n use the same PPDU format, DL PPDU 1708-1, ..., 1708-n, it is possible that a receiver may not interfere with DL PPDU 1710-1, ..., 1710-n due to misalignment of OFDM symbols. Similarly, if UL PPDU 1712-1, ..., 1712-n and UL PPDU 1714-1, ..., 1714-n are transmitted (exactly) during the second period 1720-1, ..., 1720-n, then UL PPDU 1712-1, ..., 1712-n will each have the same transmission start time and transmission end time as UL PPDU 1714-1, ..., 1714-n. Assuming that UL PPDU 1712-1, ..., 1712-n and UL PPDU 1714-1, ..., 1714-n use the same PPDU format, UL PPDU 1712-1, ..., 1712-n, it is possible that UL PPDU 1714-1, ..., 1714-n may not interfere at a receiver (e.g., AP 1504 or AP 1506) due to misalignment of OFDM symbols.Furthermore, since DL PPDU 1708-1, ..., 1708-n, and DL PPDU 1710-1, ..., 1710-n do not overlap in time with UL PPDU 1714-1, ..., 1714-n, and UL PPDU 1712-1, ..., 1712-n, interference may not occur between DL PPDU 1708-1, ..., 1708-n and UL PPDU 1714-1, ..., 1714-n, or between DL PPDU 1710-1, ..., 1710-n and UL PPDU 1712-1, ..., 1712-n.

[0189] In one embodiment, COFDMA may be used for transmitting DL PPDU 1708-1, ..., 1708-n, and 1710-1, ..., 1710-n, as well as UL PPDU 1712-1, ..., 1712-n, and 1714-1, ..., 1714-n. Specifically, AP 1502 may assign APs 1504 and 1506 to their respective frequency resources that are orthogonal to each other with respect to the allocated time 1716. For example, AP 1502 may divide an 80MHz channel into two non-overlapping 40MHz channels, each assigned to one of APs 1504 and 1506. In one example, the frequency resources assigned to the APs are shown in the RU assignment subfield of the user information field (indicating the AP identifier) ​​in the MRTT frame 1702. Therefore, DL PPDU 1708-1, ..., 1708-n, and UL PPDU 1712-1, ..., 1712-n can be transmitted on RUs orthogonal to RUs, which are used for transmitting DL PPDU 1710-1, ..., 1710-n, and UL PPDU 1714-1, ..., 1714-n.

[0190] Figure 18 shows an exemplary process 1800 according to one embodiment. The exemplary process 1800 may be carried out by a first AP, such as AP 1504 or AP 1506. The first AP may be part of a multi-AP group. The multi-AP group may include a second AP. The first AP may be a slave AP of the multi-AP group, and the second AP may be the master AP of the multi-AP group. As shown in Figure 18, the process 1800 includes steps 1802 and 1804.

[0191] Step 1804 includes the first AP receiving from the second AP a frame indicating the allocated time of the TXOP obtained by the second AP, the identifier of the first AP, and the first period within the allocated time for DL ​​PPDU transmission.

[0192] Step 1804 includes sending a first DL PPDU by the first AP during the first period for DL ​​PPDU transmission.

[0193] In one embodiment, DL PPDU transmission includes cooperative DL PPDU transmission. In one embodiment, cooperative DL PPDU transmission includes a first DL PPDU from a first AP and a second DL PPDU from a second AP. In another embodiment, cooperative DL PPDU transmission includes a first DL PPDU from a first AP and a second DL PPDU from a third AP. In such an embodiment, the frame may further indicate the identifier of the third AP.

[0194] In one embodiment, the first DL PPDU and the second DL PPDU have the same transmission start time and the same transmission end time.

[0195] In one embodiment, the first DL PPDU and the second DL PPDU each have a transmission period equal to the first period.

[0196] In one embodiment, the first DL PPDU or the second DL PPDU may include padding bits.

[0197] In one embodiment, the frame may further include a second period within the allocated time for UL PPDU transmission.

[0198] In one embodiment, the UL PPDU transmission includes a cooperative UL PPDU transmission. In one embodiment, the cooperative UL PPDU transmission includes a first UL PPDU for a first AP and a second UL PPDU for a second AP. In another embodiment, the cooperative UL PPDU transmission includes a first UL PPDU for a first AP and a second UL PPDU for a third AP. In such an embodiment, the frame may further indicate the identifier of the third AP.

[0199] In one embodiment, the first UL PPDU and the second UL PPDU have the same transmission start time and the same transmission end time.

[0200] In one embodiment, the first UL PPDU and the second UL PPDU each have a transmission period equal to the second period.

[0201] In one embodiment, the frame may further indicate the number of iterations, which represents the number of DL PPDU transmissions and UL PPDU transmissions within the allocated time.

[0202] In one embodiment, process 1800 may further include sending a third DL PPDU by the first AP for the remainder of the allocated time following the first and second periods.

[0203] In one embodiment, the frame includes an MRTT frame. In such an embodiment, process 1800 may further include the first AP sending a CTS frame to the second AP in response to the MRTT frame.

[0204] In another embodiment, the frame includes an aggregation of an MRTT frame and a QoS null frame containing an SRS control field.

[0205] Figure 19 shows another exemplary process 1900 according to one embodiment. Process 1900 may be carried out by a first AP, such as AP 1502. The AP may be part of a multi-AP group. The multi-AP group may include a second AP. The first AP may be the master AP of the multi-AP group, and the second AP may be a slave AP of the multi-AP group. As shown in Figure 19, process 1900 may include step 1902 and an optional step 1904.

[0206] Step 1902 includes the first AP transmitting a frame indicating the allocated time of the TXOP obtained by the first AP, the first period within the allocated time for DL ​​PPDU transmission, and the identifier of the second AP.

[0207] In one embodiment, DL PPDU transmission includes cooperative DL PPDU transmission. In one embodiment, cooperative DL PPDU transmission includes a first DL PPDU from a first AP and a second DL PPDU from a second AP. In another embodiment, cooperative DL PPDU transmission includes a first DL PPDU from a first AP and a second DL PPDU from a third AP. In such an embodiment, the frame may further indicate the identifier of the third AP.

[0208] In one embodiment, the first DL PPDU and the second DL PPDU have the same transmission start time and the same transmission end time.

[0209] In one embodiment, the first DL PPDU and the second DL PPDU each have a transmission period equal to the first period.

[0210] In one embodiment, the frame may further include a second period within the allocated time for UL PPDU transmission.

[0211] In one embodiment, the UL PPDU transmission includes a cooperative UL PPDU transmission. In one embodiment, the cooperative UL PPDU transmission includes a first UL PPDU for a first AP and a second UL PPDU for a second AP. In another embodiment, the cooperative UL PPDU transmission includes a first UL PPDU for a first AP and a second UL PPDU for a third AP. In such an embodiment, the frame may further indicate the identifier of the third AP.

[0212] In one embodiment, the first UL PPDU and the second UL PPDU have the same transmission start time and the same transmission end time.

[0213] In one embodiment, the first UL PPDU and the second UL PPDU each have a transmission period equal to the second period.

[0214] In one embodiment, the frame may further indicate the number of iterations, which represents the number of DL PPDU transmissions and UL PPDU transmissions within the allocated time.

[0215] In one embodiment, the frame includes an MRTT frame. In such an embodiment, process 1900 may further include, in an optional step 1904, receiving a CTS frame from a second AP in response to an MRTT frame by a first AP.

[0216] In another embodiment, the frame includes an aggregation of an MRTT frame and a QoS null frame containing an SRS control field.

Claims

1. It is a method, The first access point (AP) receives a Multi-User (MU) Send Request (RTS) Trigger Send Opportunity (TXOP) Shared Trigger (MRTT) frame from the second AP, wherein the frame is The allocated time of the TXOP obtained by the second AP, The identifier of the first AP, The first period for Cooperative Downlink Physical Layer Protocol Data Unit (DL PPDU) transmission within the allocated time is indicated as follows: The first AP transmits a Ready to Transmit (CTS) frame to the second AP in response to the MRTT frame. A method comprising transmitting a DL PPDU to a station (STA) during the first period for the cooperative DL PPDU transmission using the first AP.

2. It is a method, The first access point (AP) receives a frame from the second AP, and the frame is The allocated time of the transmission opportunity (TXOP) acquired by the second AP, The identifier of the first AP, To indicate a first period within the allocated time for downlink physical layer protocol data unit (DL PPDU) transmission, A method comprising transmitting a first DL PPDU during the first period for the DL PPDU transmission using the first AP.

3. The method according to claim 2, wherein the DL PPDU transmission includes cooperative DL PPDU transmission.

4. The method according to claim 3, wherein the cooperative DL PPDU transmission includes the first DL PPDU by the first AP and the second DL PPDU by the second AP.

5. The method according to claim 3, wherein the cooperative DL PPDU transmission includes the first DL PPDU by the first AP and the second DL PPDU by the third AP.

6. The method according to claim 5, wherein the frame further indicates the identifier of the third AP.

7. The method according to any one of claims 4 to 6, wherein the first DL PPDU and the second DL PPDU have the same transmission start time and the same transmission end time.

8. The method according to any one of claims 4 to 7, wherein the first DL PPDU and the second DL PPDU each have a transmission period equal to the first period.

9. The method according to any one of claims 2 to 8, wherein the first DL PPDU includes padding bits.

10. The method according to any one of claims 2 to 9, wherein the frame further comprises a second period within the allocated time for uplink (UL) PPDU transmission.

11. The method according to claim 10, wherein the UL PPDU transmission includes cooperative UL PPDU transmission.

12. The method according to claim 11, wherein the cooperative UL PPDU transmission includes a first UL PPDU to the first AP and a second UL PPDU to the second AP.

13. The method according to claim 11, wherein the cooperative UL PPDU transmission includes a first UL PPDU to the first AP and a second UL PPDU to the third AP.

14. The method according to claim 13, wherein the frame further indicates the identifier of the third AP.

15. The method according to any one of claims 12 to 14, wherein the first UL PPDU and the second UL PPDU have the same transmission start time and the same transmission end time.

16. The method according to any one of claims 12 to 15, wherein the first UL PPDU and the second UL PPDU each have a transmission period equal to the second period.

17. The method according to any one of claims 10 to 16, wherein the frame further indicates the number of repetitions of the DL PPDU transmission and the UL PPDU transmission within the allocated time.

18. The method according to any one of claims 10 to 17, further comprising transmitting a third DL PPDU by the first AP for the remainder of the allocated time following the first period and the second period.

19. The method according to any one of claims 2 to 18, wherein the frame includes a multi-user send request trigger TXOP shared trigger (MRTT) frame.

20. The method according to claim 19, further comprising the first AP transmitting a Ready to Transmit (CTS) frame to the second AP in response to the MRTT frame.

21. The method according to any one of claims 2 to 19, wherein the frame comprises an aggregation of a multi-user send request trigger TXOP shared trigger (MRTT) frame and a quality of service (QoS) null frame including a single response scheduling (SRS) control field.

22. It is a method, The first access point (AP) transmits a Multi-User (MU) Send Request (RTS) Trigger Send Opportunity (TXOP) Shared Trigger (MRTT) frame, wherein the frame is The allocated time of the TXOP obtained by the first AP, The identifier of the second AP, The first period for Cooperative Downlink Physical Layer Protocol Data Unit (DL PPDU) transmission within the allocated time is indicated as follows: A method comprising the first AP receiving a Ready to Transmit (CTS) frame from the second AP in response to the MRTT frame.

23. It is a method, The first AP transmits a frame, and the frame is The allocated time of the transmission opportunity (TXOP) acquired by the first AP, A first period within the allocated time for transmitting a Downlink Physical Layer Protocol Data Unit (DL PPDU), A method including indicating the identifier of the second AP.

24. The method according to claim 23, wherein the DL PPDU transmission includes cooperative DL PPDU transmission.

25. The method according to claim 24, wherein the cooperative DL PPDU transmission includes a first DL PPDU by the first AP and a second DL PPDU by the second AP.

26. The method according to claim 24, wherein the cooperative DL PPDU transmission includes a first DL PPDU by the second AP and a second DL PPDU by the third AP.

27. The method according to claim 26, wherein the frame further indicates the identifier of the third AP.

28. The method according to any one of claims 25 to 27, wherein the first DL PPDU and the second DL PPDU have the same transmission start time and the same transmission end time.

29. The method according to any one of claims 25 to 28, wherein the first DL PPDU and the second DL PPDU each have a transmission period equal to the first period.

30. The method according to any one of claims 23 to 29, wherein the frame further comprises a second period within the allocated time for uplink (UL) PPDU transmission.

31. The method according to claim 30, wherein the UL PPDU transmission includes cooperative UL PPDU transmission.

32. The method according to claim 31, wherein the cooperative UL PPDU transmission includes a first UL PPDU to the first AP and a second UL PPDU to the second AP.

33. The method according to claim 31, wherein the cooperative UL PPDU transmission includes a first UL PPDU to the second AP and a second UL PPDU to the third AP.

34. The method according to claim 33, wherein the frame further indicates the identifier of the third AP.

35. The method according to any one of claims 32 to 34, wherein the first UL PPDU and the second UL PPDU have the same transmission start time and the same transmission end time.

36. The method according to any one of claims 32 to 35, wherein the first UL PPDU and the second UL PPDU each have a transmission period equal to the second period.

37. The method according to any one of claims 30 to 36, wherein the frame further indicates the number of repetitions of the DL PPDU transmission and the UL PPDU transmission within the allocated time.

38. The method according to any one of claims 23 to 37, wherein the frame includes a multi-user send request trigger TXOP shared trigger (MRTT) frame.

39. The method according to claim 38, further comprising the first AP receiving a Ready to Transmit (CTS) frame from the second AP in response to the MRTT frame.

40. The method according to any one of claims 23 to 39, wherein the frame comprises an aggregation of a multi-user send request trigger TXOP shared trigger (MRTT) frame and a quality of service (QoS) null frame including a single response scheduling (SRS) control field.

41. It is a device, One or more processors, A device comprising: a memory for storing instructions that, when executed by one or more processors, cause the device to perform the method according to any one of claims 1 to 40.

42. A non-temporary computer-readable medium that, when executed by one or more processors, includes instructions causing one or more processors to perform the method according to any one of claims 1 to 40.

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