Guard interval coordination for multiple access point communications

Abstract

In one aspect, a first access point (AP) receives a first frame from a second AP, the first frame indicating a first guard interval for transmission from the second AP to a station (STA). The transmission is scheduled during a transmission opportunity (TXOP) of the first AP. The first AP transmits a second frame to the second AP, the second frame indicating a second guard interval for the transmission. The second guard interval is based on the first guard interval. In another aspect, the first AP transmits a first frame to the second AP, the first frame indicating a first guard interval. The first AP receives a second frame from the second AP, the second frame indicating a second guard interval.

Description

Cross Reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 535,325, filed August 30, 2023, which is hereby incorporated by reference in its entirety. BRIEF DESCRIPTION OF DRAWINGS

[0002] Examples of several of the many embodiments of the present disclosure are described herein with reference to the accompanying drawings.

[0003] Figure 1 An example wireless communication network in which embodiments of the present disclosure can be implemented is illustrated.

[0004] Figure 2 is a block diagram illustrating an example implementation of a station (STA) and an access point (AP).

[0005] Figure 3 An example medium access control (MAC) frame format is illustrated.

[0006] Figure 4 An example management frame that can be used as an action frame is illustrated.

[0007] Figure 5 An example control frame that can be used as a trigger frame is illustrated.

[0008] Figure 6 An example data frame that can be used as a quality of service (QoS) null frame is illustrated.

[0009] Figure 7 An example format of a physical layer (PHY) protocol data unit (PPDU) is illustrated.

[0010] Figure 8 An example multi-AP network is illustrated.

[0011] Figure 9 An example network including a set of coordinating APs is illustrated.

[0012] Figure 10 An example multi-AP operation procedure is illustrated.

[0013] Figure 11 An example multi-AP sounding phase is illustrated.

[0014] Figure 12 An example multi-AP downlink data transmission phase is illustrated.

[0015] Figure 13 An example multi-AP uplink data transmission phase is illustrated.

[0016] Figure 14 Another example format of a PPDU is illustrated.

[0017] Figure 15 is an example illustrating an existing multi-AP transmission procedure according to embodiments.

[0018] Figure 16 is an example illustrating a guard interval (GI) coordination procedure for multi-AP communication according to embodiments.

[0019] Figure 17 is an example illustrating a GI coordination procedure for multi-AP communication according to embodiments.

[0020] Figure 18 is an example illustrating a GI coordination procedure for multi-AP communication according to embodiments.

[0021] Figure 19 is an example illustrating a GI coordination procedure for multi-AP communication according to embodiments.

[0022] Figure 20 Example action frames that can be used according to embodiments are illustrated.

[0023] Figure 21 Example QoS null frames that can be used according to embodiments are illustrated.

[0024] Figure 22 An example process according to embodiments of the disclosure is illustrated.

[0025] Figure 23 An example process according to embodiments of the disclosure is illustrated.

[0026] Figure 24 An example process according to embodiments of the disclosure is illustrated. DETAILED DESCRIPTION

[0027] In this disclosure, various embodiments are presented in the form of examples of how the disclosed technology can be implemented and / or how the disclosed technology can be practiced in environments and scenarios. It will be apparent to those skilled in the relevant arts that various changes in form and detail can be made without departing from the scope of the invention. It will be apparent to those skilled in the relevant arts, upon reading this specification, how to implement alternative embodiments. The embodiments of the invention are not to be limited to any described exemplary embodiment. Embodiments of the disclosure will be described with reference to the drawings. Limitations, features and / or elements from the disclosed example embodiments can be combined to create additional embodiments within the scope of the disclosure. The diagrams are only for purposes of illustrating example embodiments and are not limiting. The disclosed architectures are sufficiently flexible and reconfigurable to accommodate different implementations than those shown. For example, the actions listed in any flow diagram can be reordered or only optionally used in some embodiments.

[0028] The embodiments can be configured to operate as needed. When certain criteria are met, the disclosed mechanisms can be executed, for example, in stations, access points, radio environments, networks, combinations thereof, etc. Example standards may be based at least in part on, for example, wireless device or network node configuration, traffic load, initial system settings, packet size, service characteristics, combinations thereof, etc. Various example embodiments can be applied when one or more criteria are met. Therefore, example embodiments that selectively implement the disclosed protocols can be implemented.

[0029] In this disclosure, the terms “a” and “an” and similar phrases will be interpreted as “at least one” and “one or more”. Similarly, any term ending with the suffix “(s)” will be interpreted as “at least one” and “one or more”. In this disclosure, the term “may” is interpreted as “may, for example”. In other words, the term “may” indicates that the phrase following the term “may” is an example of one of a variety of suitable possibilities that may or may not be used in one or more of the various embodiments. As used herein, the terms “comprising” and “consisting of” enumerate one or more components of the element being described. The terms “comprising” and “including” are interchangeable and do not exclude the inclusion of unlisted components in the element being described. In contrast, “consisting of” provides a complete enumeration of the one or more components of the element being described. As used herein, the term “based on” can be interpreted as “at least partially based on” rather than, for example, “based on only”. As used herein, the term “and / or” indicates any possible combination of the enumerated elements. For example, "A, B and / or C" can mean A; B; C; A and B; A and C; B and C; or A, B and C.

[0030] If A and B are sets, and every element of A is also an element of B, then A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, 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 instance of one of a variety of suitable possibilities that may or may not be used in one or more of the various embodiments. The phrase “in response to” (or equivalently “at least in response to”) indicates that the phrase following the phrase “in response to” is an instance of one of a variety of suitable possibilities that may or may not be used in one or more of the various embodiments. The phrase “depends on” (or equivalently “at least depends on”) indicates that the phrase following the phrase “depends on” is an instance of one of a variety of suitable possibilities that may or may not be used in one or more of the various embodiments. The phrase “adopts / uses” (or equivalently “at least adopts / uses”) indicates that the phrase following the phrase “adopts / uses” is an instance of one of a variety of suitable possibilities that may or may not be used in one or more of the various embodiments.

[0031] The term "configured" can refer to the capabilities of a device, whether the device is in an operational or non-operational state. "Configured" can refer to specific settings within the device that affect its operational characteristics, regardless of whether the device is in an operational or non-operational state. In other words, hardware, software, firmware, registers, memory values, etc., can be "configured" within the device to provide specific characteristics to the device, whether the device is in an operational or non-operational state. Similarly, the term "control messages generated in the device" can mean that the control messages have parameters that can be used to configure specific characteristics in the device or to perform certain actions in the device, regardless of whether the device is in an operational or non-operational state.

[0032] 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, and 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 the example embodiment, when one or more messages / frames contain multiple parameters, this means that a parameter among the multiple parameters is in at least one of the one or more messages / frames, but not necessarily in every one of the one or more messages / frames.

[0033] Many of the proposed features are described as optional using the word "may" or parentheses. For brevity and readability, this disclosure does not explicitly describe every permutation that can be obtained by selecting from the group of optional features. This disclosure should be interpreted as explicitly disclosing all such permutations. For example, a system described as having three optional features can be embodied in seven different ways: having only one of the three possible features, having any two of the three possible features, or having three of the three possible features.

[0034] Many elements described in the disclosed embodiments can be implemented as modules. A module is defined herein as an element that performs the defined function and has the defined interface to other elements. Modules described in this disclosure can be implemented as hardware, software combined with hardware, firmware, wet hardware (e.g., hardware with biological elements), or combinations thereof, all of which may be behaviorally equivalent. For example, a module can be implemented as a software routine written in a computer language configured to be executed by a hardware machine (such as C, C++, Fortran, Java, Basic, Matlab, etc.) or a modeling / simulation program (such as Simulink, Stateflow, GNU Octave, or LabVIEW MathScript). It is possible to implement modules using physical hardware incorporating discrete or programmable analog, digital, and / or quantum hardware. Examples of programmable hardware include computers, microcontrollers, microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), and complex programmable logic devices (CPLDs). Computers, microcontrollers, and microprocessors are programmed using languages ​​such as assembly, C, C++, etc. FPGAs, ASICs, and CPLDs are typically programmed using hardware description languages ​​(HDLs), such as VHSIC Hardware Description Language (VHDL) or Verilog, which configure connections between internal hardware modules with limited functionality on the programmable device. The aforementioned techniques are often used in combination to achieve the desired result of functional modules.

[0035] Figure 1 An example wireless communication network 100 in which embodiments of the present disclosure may be implemented is shown.

[0036] like Figure 1 As shown, the example wireless communication network 100 may include an IEEE 802.11 (WLAN) infrastructure network 102. The WLAN infrastructure network 102 may include one or more Basic Service Sets (BSS) 110 and 120 and a Distribution System (DS) 130.

[0037] BSS 110-1 and 110-2 each include a set of access points (APs or AP STAs) and at least one station (STA or non-AP STA). For example, BSS 110-1 includes AP 104-1 and STA 106-1, and BSS 110-2 includes AP 104-2, STA 106-2, and STA 106-3. The APs and at least one STA in the BSS perform association procedures to communicate with each other.

[0038] DS 130 can be configured to connect BSS 110-1 and BSS 110-2. Therefore, DS 130 can enable Extended Service Set (ESS) 150. Within ESS 150, AP 104-1 and AP 104-2 are connected via DS 130 and can have the same Service Set Identifier (SSID).

[0039] The WLAN infrastructure network 102 can be coupled to one or more external networks. For example, such as Figure 1 As shown, WLAN infrastructure network 102 can be connected to another network 108 (e.g., 802.X) via portal 140. Portal 140 can act as a bridge connecting DS 130 of WLAN infrastructure network 102 to the other network 108.

[0040] Figure 1 The example wireless communication network shown may further include one or more self-organizing networks or independent BSSs (IBSSs). A self-organizing network or IBSS is a network of multiple STAs included within each other's communication range. The multiple STAs are configured such that they can communicate with each other using direct peer-to-peer communication (i.e., without through an AP).

[0041] For example, in Figure 1 In this configuration, STAs 106-4, 106-5, and 106-6 can be configured to form a first IBSS 112-1. Similarly, STAs 106-7 and STAs 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. Instead, the STAs within an IBSS are managed in a distributed manner. The STAs forming an IBSS can be fixed or mobile.

[0042] A STA, serving as a predefined functional medium, may include a Media Access Control (MAC) layer conforming to the IEEE 802.11 standard. The physical layer interface of the radio medium can be used in both AP and non-AP stations (STAs). STAs may also be referred to using various other terms, including mobile terminal, radio device, radio transmit / receive unit (WTRU), user equipment (UE), mobile station (MS), mobile subscriber unit, or user. For example, the term "user" may be used to refer to a STA participating in uplink multi-user multiple-input multiple-output (MU MIMO) and / or uplink orthogonal frequency division multiple access (OFDMA) transmissions.

[0043] Physical Layer (PHY) Protocol Data Units (PPDUs) can be composite structures, comprising a PHY preamble and a payload in the form of a PHY Service Data Unit (PSDU). For example, a PSDU may include a PHY preamble and a header and / or one or more MAC Protocol Data Units (MPDUs). The information provided in the PHY preamble can be used by the receiving device to decode subsequent data in the PSDU. When the PPDU is transmitted over a bonded channel (a channel formed by channel bonding), the preamble field can be copied and transmitted in each of the multiple component channels. The PHY preamble may include both a traditional portion (or "traditional preamble") and a non-traditional portion (or "non-traditional preamble"). The traditional preamble can be used for purposes such as packet detection, automatic gain control, and channel estimation. The traditional preamble is also typically used to maintain compatibility with legacy devices. The format, encoding, and information provided in the non-traditional portion of the preamble are based on the specific IEEE 802.11 protocol to be used for transmitting the payload.

[0044] A frequency band can include one or more sub-bands or frequency channels. For example, PPDUs conforming to IEEE 802.11n, 802.11ac, 802.11ax, and / or 802.11be standard modifications can be transmitted in 2.4 GHz, 5 GHz, and / or 6 GHz bands, each band can be divided into multiple 20 MHz channels. PPDUs can be transmitted through physical channels with a minimum bandwidth of 20 MHz. Larger channels can be formed through channel bonding. For example, multiple 20 MHz channels can be bonded together to transmit PPDUs through physical channels with bandwidths of 40 MHz, 80 MHz, 160 MHz, or 1120 MHz.

[0045] Figure 2 Block diagram 200 illustrates an example implementation of STA 210 and AP 260. (As shown...) Figure 2As shown, STA 210 may include at least one processor 220, memory 230, and at least one transceiver 240. AP 260 may include at least one processor 270, memory 280, and at least one transceiver 290. Processors 220 / 270 may be operatively connected to transceivers 240 / 290.

[0046] Transceiver 240 / 290 can be configured to transmit / receive radio signals. In embodiments, transceiver 240 / 290 can implement the PHY layer of the corresponding device (STA 210 or AP 260).

[0047] In this embodiment, STA 210 and / or AP 260 may be a multi-link device (MLD), i.e., a device capable of operating on multiple links as defined by the IEEE 802.11be standard amendment. Therefore, STA 210 and / or AP 260 may each have multiple PHY layers. Multiple PHY layers can be implemented using one or more of transceivers 240 / 290.

[0048] Processors 220 / 270 can implement the functions of the PHY layer, MAC layer and / or logical link control (LLC) layer of the corresponding device (STA 210 or AP 260).

[0049] Processors 220 / 270 and / or transceivers 240 / 290 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processors. Memory 230 / 280 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage units.

[0050] When the embodiments are executed by software, the techniques (or methods) described herein can be performed using modules (e.g., processes, functions, etc.) that perform the functions described herein. Modules can be stored in memory 230 / 280 and executed by processor 220 / 270. Memory 230 / 280 can be implemented (or located) within processor 220 / 270 or external to processor 220 / 270. Memory 230 / 280 can be operatively connected to processor 220 / 270 in various ways known in the art.

[0051] Figure 3 The example format of MAC frame 300 is shown. In operation, the STA can construct a subset of MAC frames for transmission and can decode the received subset of MAC frames during verification. The specific subset of frames that the STA can construct and / or decode can be determined by the functions supported by the STA. The STA can verify the received MAC frames using the Frame Check Sequence (FCS) contained in the frame and can interpret certain fields based on the MAC header of all frames.

[0052] like Figure 3 As shown, MAC frame 300 includes a MAC header, a variable-length frame body, and a frame check sequence (FCS).

[0053] The MAC header includes a frame control field, an optional duration / ID field (not in PS-Poll frames), an address field, an optional sequence control field, an optional QoS control field (only in QoS data frames), and an optional high throughput (HT) control field (only in +HTC frames).

[0054] The frame control field includes the following subfields: protocol version, type, subtype, to DS, from DS, more fragments, retry, power management, more data, protected frames, and high throughput control (+HTC).

[0055] The size and placement of the protocol version subfield remain unchanged across all revisions of the IEEE 802.11 standard. For MAC frames, the value of the protocol version subfield is 0.

[0056] The Type and Subtype subfields together identify the function of a MAC frame. There are three frame types: Control, Data, and Management. Each frame type has several defined subtypes. Bits within the Subtype subfield are used to indicate specific modifications to 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, i.e., a data frame that includes the QoS Control field in its MAC header. When set to 1 in the Data subtype, the second MSB of the Subtype field, bit 6 (B6) of the Frame Control field, indicates a data frame that does not include a Frame Body field.

[0057] The ToDS subfield indicates whether the data frame is destined for DS. The FromDS subfield indicates whether the data frame originated from DS.

[0058] In all data or management frames that have another fragment following the MAC Service Data Unit (MSDU) or MAC Management Protocol Data Unit (MMPDU) carried in a MAC frame, the More Fragments subfield is set to 1. In all other frames in which the More Fragments subfield exists, it is set to 0.

[0059] In any data or management frame that is a retransmission of an earlier frame, the retry subfield is set to 1. In all other frames in which the retry subfield exists, it is set to 0. The receiving STA uses this indication to assist in its process of eliminating duplicate frames. These rules do not apply to frames sent by the STA according to the block protocol.

[0060] The power management subfield is used to indicate the power management mode of the STA.

[0061] The More Data subfield indicates to the STA in Power Saving (PS) mode that a bufferable unit (BU) is buffered at the AP for the STA. The More Data subfield is active in individually addressed data or management frames transmitted by the AP to the STA in PS mode. The More Data subfield is set to 1 to indicate that at least one additional buffered BU exists for the STA.

[0062] If the frame body field contains information that has been processed by an encryption encapsulation algorithm, then the protected frame subfield is set to 1.

[0063] The +HTC subfield indicates that MAC frame 300 contains the HT control field. Frames containing the HT control field are called +HTC frames. Control wrapper frames are +HTC frames.

[0064] The Duration / ID field in the MAC header indicates different content depending on the frame type, subtype, and the QoS capabilities of the sending 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 has transmitted a frame in 14 least significant bits (LSBs), and both most significant bits (MSBs) are set to 1. In other frames transmitted by the STA, the Duration / ID field contains a duration value (in microseconds) for the receiver to use to update the Network Allocation Vector (NAV). The NAV is a counter indicating to the STA the amount of time it must delay access to the shared medium.

[0065] A MAC frame 300 format may contain up to four address fields. These fields are used to indicate the Basic Service Set Identifier (BSSID), source address (SA), destination address (DA), transporter address (TA), and receiver address (RA). Some frames may not contain certain address fields. The use of certain address fields can be specified by the relative order of address fields (1-4) within the MAC header, regardless of the address type present in those fields. Specifically, address 1 always identifies the intended receiver of the frame, and address 2 (if present) always identifies the transporter of the frame.

[0066] The sequence control field includes two subfields: a sequence number subfield and a fragment number subfield. In a data frame, the sequence number subfield indicates the sequence number of the MSDU (if not in an aggregated MSDU (A-MSDU)) or A-MSDU. In a management frame, the sequence number subfield indicates the sequence number of the frame. The fragment number subfield indicates the number of each fragment of the MSDU or MMPDU. In the first or only fragment of an MSDU or MMPDU, the fragment number is set to 0 and increments by one for each subsequent fragment of that MSDU or MMPDU. In a MAC Protocol Data Unit (MPDU) containing an A-MSDU or in an MPDU containing an unfragmented MSDU or MMPDU, the fragment number is set to 0. The fragment number remains constant throughout all retransmissions of the fragment.

[0067] The QoS control field identifies the Traffic Class (TC) or Traffic Stream (TS) to which the MAC frame 300 belongs. The QoS control field can 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 the type of transport STA. The QoS control field exists in all data frames where the QoS subfield of the subtype subfield is equal to 1.

[0068] The HT control field exists in QoS data, QoS empty, and management frames, as determined by the +HTC subfield of the frame control field. The control frame subtype containing the HT control field is the control wrapper frame. A control frame described as +HTC (e.g., Request to Send (RTS) +HTC, Clear to Send (CTS) +HTC, Block Ack +HTC, or Block Ack Req +HTC frame) means that the control frame is carried using a control wrapper frame.

[0069] The frame body field is a variable-length field that contains information specific to each frame type and subtype. It can include one or more MSDUs or MMPDUs. The minimum length of the frame body is 0 octets.

[0070] The FCS field contains a 32-bit Cyclic Redundancy Check (CRC) code. The FCS field value is calculated on all fields of the MAC header and frame body.

[0071] Figure 4 An example management frame 400 that can be used as an action frame is shown. In this example, management frame 400 includes a MAC header, a variable-length frame body, and a frame check sequence (FCS). The MAC header includes a frame control field, a duration field, an address 1 field, an address 2 field, an address 3 field, a sequence control field, and an optional HT control field. The presence of the HT control field is determined by the setting of the +HTC subfield of the frame control field.

[0072] like Figure 4 As shown, when used as an action frame, the frame body of a management frame includes an action field, vendor-specific elements, a management message integrity code element (MME), a message integrity code (MIC), and an authenticated mesh peer exchange element.

[0073] The action field includes a category field and an action details field. The action field provides a mechanism for specifying extended management actions. The category field indicates the category of the action frame. The action details field contains details of the action requested by the action frame. For example, the action frame could be a common action frame. Figure 4 As shown, in the common action frame format, the action detail field includes the common action field in an octet immediately following the category field, followed by the variable-length common action detail field.

[0074] Optionally, one or more supplier-specific elements may exist. These elements do not exist when the category subfield of the action field is supplier-specific.

[0075] When negotiating management frame protection, the MME is present, the frame is a group-addressed robust action frame, and (MBSS only) the action frame's class does not support group-addressed privacy as indicated by the class value; otherwise, it is not present.

[0076] If a shared pair master key (PMK) exists between the sender and receiver of this frame, then the MIC element exists in the self-protection action frame; otherwise, it does not exist.

[0077] If the shared PMK exists between the sender and receiver of this frame, then the authenticated mesh peer-to-peer exchange element exists in the self-protection action frame; otherwise, it does not exist.

[0078] Figure 5 The example format of trigger frame 500 is shown. An AP can use trigger frame 500 to allocate resources to one or more STAs and request one or more TB PPDU transmissions from one or more STAs. Trigger frame 500 may also carry additional information required by a STA to transmit a TB PPDU to the AP.

[0079] like Figure 5 As shown, the trigger frame 500 includes a frame control field, a duration field, a receiver address (RA) field, a transmitter address (TA) field, a public information field, a user list information field, a padding field, and an FCS field.

[0080] The frame control field includes the following subfields: protocol version, type, subtype, to DS, from DS, more fragments, retry, power management, more data, protected frames, and +HTC.

[0081] The duration field indicates various things depending on the frame type and subtype, as well as the QoS capabilities of the sending STA. For example, in a control frame of the Power Saving Polling (PS-Poll) subtype, the duration field carries the association identifier (AID) of the STA that has transmitted the frame in 14 least significant bits (LSBs), and both most significant bits (MSBs) are set to 1. In other frames transmitted by the STA, the duration field contains a duration value (in microseconds) for the receiver to use to update the Network Allocation Vector (NAV).

[0082] The RA field is the address of the STA intended to receive an incoming transmission from the transmission station. If trigger frame 500 is addressed to an STA belonging to a single BSS, then the TA field is the address of the STA transmitting trigger frame 500. If trigger frame 500 is addressed to an STA from at least two different BSSs in a set of multiple BSSIDs, then the TA field is the BSSID being transmitted.

[0083] The common information field specifies the trigger frame type of trigger frame 500, the transmission power of trigger frame 500 in dBm, and several key parameters of the TB PPDU transmitted by the STA in response to trigger frame 500. The trigger frame type used by the AP to receive QoS data using the UL MU is called the basic trigger frame. Non-EHT, non-AP HE STAs interpret the common information field as an HE variant. If B54 and B55 in the common information field are equal to 1, then non-AP EHT STAs interpret the common information field as an HE variant; otherwise, they interpret it as an EHT variant. The HE variant common information field and the EHT variant common information field use the same encoding method for trigger type, UL length, additional TF, required CS, LDPC additional symbol segment, AP TX power, pre-FEC padding factor, PE disambiguation, and trigger-related common information subfields.

[0084] The user information list field contains zero or more user information fields. There are three variations of the user information field: specific user information field, EHT variant user information field, and HE variant user information field.

[0085] The Special User Information field is a user information field that does not carry user-specific information but carries extended public information not provided in the Public Information field. If the Special User Information field is included in the trigger frame, the Special User Information Field Flag subfield of the EHT Variant Public Information field is set to 0; otherwise, it is set to 1. The Special User Information field is identified by the AID12 value 2007 and optionally exists in the trigger frame generated by the EHT AP. The Special User Information field (if present) immediately follows the Public Information field of the trigger frame and carries information for the U-SIG field of the requested EHT TB PPDU. The PHY Version Identifier subfield indicates the PHY version of the requested TB PPDU, which is not an HE TB PPDU. For EHT, the PHY Version Identifier subfield is set to 0. Other values ​​from 1 to 7 are reserved. The UL Bandwidth (BW) Extension subfield, together with the UL BW subfield in the Public Information field, indicates the bandwidth of the requested TB PPDU from the addressed ELT STA (i.e., the bandwidth in the U-SIG field of the EHT TB PPDU). The EHT Space Reuse n subfield carries the value to be included in the corresponding Space Reuse n subfield of the U-SIG field in the EHT TB PPDU. The U-SIG Ignore and Verify subfield carries the value to be included in the Ignore and Verify subfield of the U-SIG field in the requested EHT TB PPDU. The presence and length of the Trigger-Related User Information subfield in the Special User Information field depend on the variant of the trigger frame.

[0086] The EHT variant user information field contains user information fields for each STA addressed in trigger frame 500. Each STA user information field specifically includes the AID12 subfield, RU allocation subfield, UL FEC coding type subfield, UL EHT-MCS subfield, reserved subfield, spatial stream (SS) allocation / RA-RU information subfield, UL target received power subfield, and power saving (PS) 160 subfield for use by the STA in the TB PPDU transmitted in response to trigger frame 500, as well as trigger-related user information subfields. The RU allocation subfield in the EHT variant user information field (not a MU-RTS trigger frame), the UL BW subfield in the common information field, the BW extension subfield in the specific user information field, and the PS160 subfield in the EHT variant user information field identify the size and location of the RU or MRU. The B0 value of the PS160 subfield and RU allocation subfield indicates the 80 MHz frequency subblock where the RU or MRU is located, for 26-mode RU, 52-mode RU, 106-mode RU, 242-mode RU, 484-mode RU, 996-mode RU, 52+26-mode RU, and 106+26-mode RU. The PS160 subfield value indicates the 160 MHz segment where the RU or MRU is located, for 2996-mode RU, 996+484-mode MRU, and 996+484+242-mode MRU. The UL FEC coding type subfield of the User Information field indicates the code type of the requested EHT TB PPDU. The UL FEC coding type subfield is set to 0 to indicate BCC and set to 1 to indicate LDPC. The UL EHT-MCS subfield of the User Information field indicates the EHT-MCS of the requested EHT TB PPDU. The SS allocation subfield of the EHT variant user information field indicates the spatial flow of the requested EHT TB PPDU. The UL target received power subfield indicates the expected received signal power, measured at the AP's antenna connector and averaged by the antenna, for the EHT portion of the EHT TB PPDU transmitted on the assigned RU. The AP can use the trigger-related user information subfield to specify the preferred access class (AC) for each STA. The preferred AC setting can be determined by the minimum priority AC traffic transmitted by the participating STAs. The AP determines the list of participating STAs, and the BW, MCS, RU allocation, SS allocation, Tx power, preferred AC, and maximum duration for each participating STA's TB PPDU. The RA-RU information subfield is retained in the EHT variant user information field.

[0087] The padding field is optionally present in the trigger frame 400 to extend the frame length, thereby giving the receiver STA sufficient time to prepare a response for transmission within one SIFS after receiving the frame. The padding field (if present) is at least two octets in length and is set to all 1s.

[0088] The STA uses the FCS field to verify received frames and interprets certain fields based on the frame's MAC header.

[0089] Figure 6 Example data frame 600, which can be used as a QoS empty frame, is shown. A QoS empty frame is a QoS data frame with an empty frame body. A QoS empty frame includes a QoS control field and an optional HT control field, which may contain a Buffer Status Report (BSR) control subfield. A QoS empty frame indicating buffer status information can be transmitted from a STA to an AP.

[0090] QoS control fields may include a Traffic Identifier (TID) subfield, an Acknowledgment (Ack) Policy Indicator subfield, and a Queue Size subfield (or a Transmission Opportunity (TXOP) Duration Request subfield).

[0091] The TID subfield identifies the TC or TS that is requesting a TXOP by setting the requested TXOP duration or queue size subfield. The encoding of the TID subfield depends on the access policy (e.g., values ​​0 to 7 are allowed for Enhanced Distributed Channel Access (EDCA) access policies to identify the user priority of the TC or TS).

[0092] The ack policy indicator subfield and other information identify the ack policy to be followed after the MPDU is delivered (e.g., normal ack, implicit block ack request, no ack, block ack, etc.). The queue size subfield is an 8-bit field that indicates the amount of buffered traffic at the STA used to transmit a given TC or TS to the AP identified by the receiver address of the frame containing this subfield. The queue size subfield is present in the QoS empty frames transmitted by the STA when bit 4 of the QoS control field is set to 1. The AP can use the information contained in the queue size subfield to determine the duration of the TXOP assigned to the STA or to determine the uplink (UL) resources assigned to the STA.

[0093] In frames sent to or from inefficient (non-HE) STAs, the following rules may be applied to queue size values: - The queue size value is the approximate total size of all MSDUs and A-MSDUs (excluding MSDUs or A-MSDUs contained in this QoS data frame) buffered at the STA in the delivery queue for MSDUs and A-MSDUs, rounded up to the nearest multiple of 256 octets and expressed in units of 256 octets, where the TID value is equal to the value indicated in the TID subfield of the QoS control field.

[0094] - A queue size value of 0 is only used to indicate that there is no buffered traffic in the queue used for the specified TID.

[0095] - For all sizes greater than 64,768 octets, use a queue size value of 254.

[0096] - The queue size value of 255 is used to indicate an unspecified or unknown size.

[0097] In frames sent from HE STA to HE AP, the following rules can be applied to queue size values.

[0098] Queue size value QS It is the approximate total size of all MSDUs and A-MSDUs buffered at the STA in the delivery queue for MSDUs and A-MSDUs (including MSDUs or A-MSDUs contained in the same PSDU as the frame containing the queue size subfield), represented in octets, where the TID value is equal to the value indicated in the TID subfield of the QoS control field.

[0099] The queue size subfield includes the scaling factor subfield in bits B14 to B15 of the QoS control field and the unscaled value in bits B8 to B13 of the QoS control field. UV The scaling factor subfield provides the scaling factor. SF .

[0100] STA receives data containing scaling factors SF and unscaled values UV Get queue size from QoS control field QS ,as follows: QS = 16 × UV ,if SF Equals 0; 1024 + 256 × UV ,if SF It equals 1; 17,408 + 2048 × UV ,if SF It equals 2; 148 480 + 32 768 ×UV ,if SF Equal to 3 and UV Less than 62; >2 147 328, if SF Equal to 3 and UV Equals 62; Not assigned or Unknown ,if SF Equal to 3 and UV It equals 63.

[0101] The requested TXOP duration subfield, which may be included instead of the queue size subfield, indicates to the sending STA the duration, in 32 microseconds (µs), required for the next TXOP for the specified TID. The requested TXOP duration subfield is set to 0 to indicate that no TXOP is requested for the specified TID in the current service period (SP). The requested TXOP duration subfield is set to a non-zero value to indicate the requested TXOP duration in increments of 32 microseconds within the range of 32 microseconds to 8160 microseconds.

[0102] HT control fields may include aggregate control (A-control) subfields. A-control subfields may include control list subfields, which may include one or more control subfields.

[0103] The control subfield can be a BSR control subfield, which can contain buffer status information for UL MU operations. The BSR control subfield can be formed from the following: the Access Class Index (ACI) bitmap subfield of the HT control field, the ΔTID subfield, the ACI high subfield, the scaling factor subfield, the queue size high subfield, and the queue size full subfield.

[0104] The ACI bitmap subfield indicates the access category for reporting buffer status (e.g., B0: Best Effort (AC_BE); B1: Background (AC_BK); B2: Video (AC_VI); B3: Voice (AC_VO), etc.). Each bit of the ACI bitmap subfield is set to 1 to indicate that the buffer status of the corresponding AC is included in the queue size full subfield, and is otherwise set to 0. However, if the ACI bitmap subfield is 0 and the ΔTID subfield is 3, then the buffer status of all 8 TIDs is included.

[0105] The values ​​of the ΔTID subfield and the ACI bitmap subfield indicate the number of TIDs that the STA is reporting in the buffer state.

[0106] The ACI high subfield indicates the ACI of the AC indicated by the BSR in the queue size high subfield. The ACI to AC mapping is defined as ACI value 0 mapping to AC_BE, ACI value 1 mapping to AC_BK, ACI value 2 mapping to AC_VI, and ACI value 3 mapping to AC_VO.

[0107] The scaling factor subfield indicates the units of the queue size height and the queue size full subfield. SF It is represented by an octet.

[0108] The queue size high subfield indicates the amount of buffered traffic for the AC identified by the ACI high subfield. SF The octet is intended for use with the STA identified by the receiver address of a frame containing the BSR control subfield.

[0109] The queue size full subfield indicates the amount of buffered traffic for all ACs identified by the ACI bitmap subfield. SF The octet is intended for use with the STA identified by the receiver address of a frame containing the BSR control subfield.

[0110] The queue size values ​​in the queue size high and queue size full subfields are the total size of all MSDUs and A-MSDUs buffered at the STA in the delivery queues for MSDUs and A-MSDUs associated with the AC, as specified in the ACI high and ACI bitmap subfields respectively, rounded up. SF The closest multiple of an octet.

[0111] The queue size value of 254 in both the queue size high and queue size full subfields indicates that the amount of buffered traffic is greater than 254 × SF Eight-bit byte. The queue size value of 255 in both the queue size high and queue size full subfields indicates that the amount of buffered traffic is unspecified or unknown. The queue size value for QoS data frames containing fragments can remain constant even if the amount of queue traffic changes as consecutive fragments are transmitted.

[0112] The MAC service provides peer entities with the ability to exchange MSDUs. To support this service, the local MAC uses an underlying PHY-level service to transfer MSDUs to the peer MAC entity. This asynchronous MSDU transfer is performed on a connectionless basis.

[0113] Figure 7 The example format of a PPDU is shown. As shown in the figure, a PPDU may include a PHY preamble, a PHY header, a PSDU, and a tail and padding bits.

[0114] A PSDU may include one or more MPDUs, such as a QoS data frame, an MMPDU, a MAC control frame, or a QoS empty frame. When an MPDU carries a QoS data frame, the frame body of the MPDU may include an MSDU or an A-MSDU.

[0115] By default, MSDU transfer is performed on a best-effort basis. That is, there is no guarantee that the transmitted MSDU will be successfully delivered. However, QoS facilities use Traffic Identifiers (TIDs) to specify differentiated services based on each MSDU.

[0116] The STA can differentiate MSDU delivery based on the specified Traffic Category (TC) or Traffic Flow (TS) of each MSDU. The MAC sublayer entity determines the user priority (UP) of the MSDU based on the TID value provided with the MSDU. The QoS facility supports eight UP values. The UP values ​​range from 0 to 7 and form an ordered priority sequence, where 1 is the lowest value, 7 is the highest value, and 0 falls between 2 and 3.

[0117] MSDUs with a specific UP are referred to as belonging to the traffic category with that UP. The UP can be provided directly in the UP parameters at the Media Access Control Service Access Point (MAC SAP) along with each MSDU. A-MPDUs can include MPDUs with different TID values.

[0118] The STA can deliver Buffer Status Reports (BSRs) to help the AP allocate UL MU resources. The STA can deliver a BSR implicitly (unrequested BSR) in the QoS control field or BSR control subfield of any frame transmitted to the AP, or explicitly (requested BSR) in a frame sent to the AP in response to a BSRP trigger frame.

[0119] 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, ΔTID, high-priority AC, and both queue sizes.

[0120] The STA can report the buffer status of transmitted QoS empty frames and QoS data frames to the AP in the QoS control field, and report the buffer status of transmitted QoS empty frames, QoS data frames and management frames in the BSR control subfield (if present), as defined below.

[0121] 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 empty frame; the STA can set the queue size subfield to 255 to indicate an unknown / unspecified queue size for the TID. The STA can aggregate multiple QoS data frames or QoS empty frames in the A-MPDU to report the queue size for different TIDs.

[0122] If the AP has indicated that it supports receiving the BSR control subfield, then the STA can report the buffer status in the BSR control subfield of the transmitted frame.

[0123] The High Efficiency (HE) STA can report the queue size of the preferred AC, indicated by the ACI high subfield, in the queue size high subfield of the BSR control subfield. The STA can set the queue size high subfield to 255 to indicate an unknown / unspecified queue size for the AC.

[0124] The HE STA can report the queue size of the AC, as indicated by the ACI bitmap subfield, in the queue size full subfield of the BSR control subfield. The STA can set the queue size full subfield to 255 to indicate those ACs with unknown / unspecified BSRs.

[0125] A multi-link device (MLD) is an entity capable of managing communication on multiple links. An MLD can be a logical entity and can have more than one affiliated station (STA). An MLD can be an access point MLD (AP MLD), where the STAs affiliated with the MLD are AP STAs (or APs). An MLD can also be a non-access point MLD (non-AP MLD), where the STAs affiliated with the MLD are non-AP STAs (or STAs).

[0126] Depending on the capabilities of both the communication AP MLD and non-AP MLD, communication across different frequency bands / channels can occur simultaneously or at different times.

[0127] MLDs can have a single MAC service access point (MAC-SAP) that includes MAC data services down to the LLC layer. MLDs can support multiple MAC sub-layers coordinated through sub-layer management entities (SMEs). Each APSTA (or non-AP STA) attached to an AP MLD (or non-AP MLD) has a different MAC address within the MLD.

[0128] The SME is responsible for coordinating the MAC sublayer management entity (MLME) of the MLD's affiliated STA to maintain a single robust Secure Network Association (RSNA) key management entity and a single IEEE 802.1X authenticator or provider for multi-link operation (MLO).

[0129] Multi-Link Operation (MLO) procedures allow a pair of MLDs to discover, synchronize, (de-)authenticate, (re)associate, disassociate, and manage resources on any common frequency band or channel supported by both MLDs. The authenticator and MAC-SAP of an AP MLD can be identified by the same AP MLD MAC address. The supplier and MAC-SAP of a non-AP MLD can be identified by the same non-AP MLD MAC address.

[0130] Multilink (re)configuration between a non-AP MLD and an AP MLD may include the exchange of (re)association request / response frames. The exchange of (re)association request / response frames for multilink configuration may include two frames carrying basic multilink elements.

[0131] In a (re)association request frame, the non-AP MLD indicates the link requested for (re)configuration, along with the capabilities and operating parameters of the requested link. A non-AP MLD can request (re)configuration of links with a subset of APs attached to an AP MLD. The link requested for (re)configuration, along with the capabilities and operating parameters of the requested link, is independent of the existing configuration links and their capabilities and operating parameters with the associated AP MLD.

[0132] In the (re)association response frame, the AP MLD can indicate the accepted and rejected requested links for (re)reconfiguration, as well as the capabilities and operating parameters of the requested links. The AP MLD can accept a subset of the links requested for (re)reconfiguration. The (re)association response frame is sent to the non-AP STA attached to the non-AP MLD that sent the (re)association request frame.

[0133] The MLD that requests or accepts multi-link (re)configuration of any two links ensures that each link is located on a different non-overlapping channel. After a successful multi-link (re)configuration between a non-AP MLD and an AP MLD, the non-AP MLD and APMLD configure the link used for multi-link operation, and the non-AP MLD is (re)associated with the AP MLD. For each configured link, the corresponding non-AP STA attached to the non-AP MLD is in the same association state as the non-AP MLD and is associated with the corresponding AP attached to the APMLD. For each configured link, functionality between the non-AP STA and its associated AP is enabled, unless the functionality has been extended to the MLD level or otherwise specified.

[0134] Multilink (re)configuration between a non-AP MLD and an AP MLD may include the exchange of (re)association request / response frames. The exchange of (re)association request / response frames for multilink configuration may include two frames carrying basic multilink elements.

[0135] In a (re)association request frame, the non-AP MLD indicates the link requested for (re)configuration, along with the capabilities and operating parameters of the requested link. A non-AP MLD can request (re)configuration of links with a subset of APs attached to an AP MLD. The link requested for (re)configuration, along with the capabilities and operating parameters of the requested link, is independent of the existing configuration links and their capabilities and operating parameters with the associated AP MLD.

[0136] In the (re)association response frame, the AP MLD can indicate the accepted and rejected requested links for (re)reconfiguration, as well as the capabilities and operating parameters of the requested links. The AP MLD can accept a subset of the links requested for (re)reconfiguration. The (re)association response frame is sent to the non-AP STA attached to the non-AP MLD that sent the (re)association request frame.

[0137] The MLD that requests or accepts multi-link (re)configuration of any two links ensures that each link is located on a different non-overlapping channel. After a successful multi-link (re)configuration between a non-AP MLD and an AP MLD, the non-AP MLD and APMLD configure the link used for multi-link operation, and the non-AP MLD is (re)associated with the AP MLD. For each configured link, the corresponding non-AP STA attached to the non-AP MLD is in the same association state as the non-AP MLD and is associated with the corresponding AP attached to the APMLD. For each configured link, functionality between the non-AP STA and its associated AP is enabled, unless the functionality has been extended to the MLD level or otherwise specified.

[0138] In a multi-link (re)configuration procedure, if the AP MLD has indicated support for TID-to-link mapping negotiation, a non-AP MLD can initiate TID-to-link mapping negotiation by including a TID-to-link mapping element in the (re)association request frame. Upon receiving a (re)association request frame containing a TID-to-link mapping element, the AP MLD can respond to the (re)association request frame according to the following rules: The AP MLD can only accept the requested TID-to-link mapping indicated in the TID-to-link mapping element in the received (re)association request frame if the AP MLD accepts multi-link (re)configuration for all links requesting mapping of at least one TID. In this case, the non-AP MLD does indeed include a TID-to-link mapping element in the (re)association response frame. Otherwise, the non-AP MLD indicates rejection of the proposed TID-to-link mapping by including a TID-to-link mapping element suggesting a preferred TID-to-link mapping in the (re)association response frame.

[0139] Figure 8An example multi-AP network 800 is shown. The example multi-AP network 800 can be a multi-AP network according to the Wi-Fi Alliance standard specifications for multi-AP networks. For example... Figure 8 As shown, the multi-AP network 800 may include a multi-AP controller 802 and multiple multi-AP groups (or multi-AP sets or AP candidate sets), including multi-AP group 804, multi-AP group 806 and multi-AP group 808.

[0140] The multi-AP controller 802 can be a logical entity that implements the logic for controlling the APs in the multi-AP network 800. The multi-AP controller 802 can receive capability information and measurements from the APs, and can trigger AP control commands and operations on the APs. The multi-AP controller 802 can also provide login functionality to log in and provide APs to the multi-AP network 800.

[0141] Multiple AP groups 804, 806, and 808 may each include multiple APs. APs in a multiple AP group are within each other's communication range. However, APs in a multiple 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 used by the AP to monitor management frames and / or transmit beacon frames. For a STA associated with an AP, the primary channel refers to the AP's primary channel, which is advertised via the AP's beacon frames.

[0142] In one approach, one AP in a multi-AP group can be designated as the master AP. The designation of the master AP can be accomplished either through the multi-AP controller 802 or through the APs within the multi-AP group. The master AP of the multi-AP group can be fixed or can change over time among the APs in the group. APs that are not the master APs in the multi-AP group are referred to as slave APs.

[0143] In one approach, a multi-AP group or AP candidate set is a group of APs that can initiate or participate in multi-AP coordination. APs in a multi-AP group can participate as slave APs in multi-AP coordination initiated by a master AP in the same multi-AP group. At least one AP in the multi-AP group should be able to be a master AP.

[0144] In one approach, the APs in a multi-AP group can coordinate 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 (in a multi-AP group or multi-AP network) simultaneously transmit within a certain period. The period of simultaneous AP transmissions can be a continuous period.

[0145] Multi-AP group coordination can be enabled by a multi-AP controller and / or by the primary AP in the multi-AP group. In one approach, the multi-AP controller and / or the primary AP can control time / frequency sharing within a TXOP. For example, when one of the APs in the multi-AP group (e.g., the primary AP) acquires a TXOP, the multi-AP controller and / or the primary AP can control how the time / frequency resources of the TXOP will be shared with other APs in the multi-AP group. In one implementation, the AP in the multi-AP group that acquires the TXOP becomes the primary AP in the multi-AP group. The primary AP can then share a portion (which can be the entire TXOP) of its acquired TXOP with one or more other APs in the multi-AP group.

[0146] Multi-AP operation can be enabled by at least two APs that support multi-AP coordination within one or more multi-AP groups. APs can support multi-AP transmission schemes in a multi-AP network. The master AP can coordinate with slave APs to achieve multi-AP coordination and support multi-AP transmission. Slave APs can participate in multi-AP transmission. The master AP can select slave APs suitable for multi-AP transmission. Slave APs can be candidates for multi-AP transmission before being specified by the master AP.

[0147] Multi-AP transmission schemes may include transmission schemes such as coordinated OFDMA, coordinated time division multiple access (TDMA), coordinated spatial reuse, coordinated beamforming, joint transmission or reception (JT / JR), or combinations of two or more of the above schemes.

[0148] Coordinated OFDMA and coordinated TDMA can be classified as coordinated TXOP, where the frequency or time resources of TXOP can be used to coordinate interference. Coordinated spatial reuse (CSR) can provide spatial domain reuse of adjacent BSSs by adjusting the transmit power of the coordinating AP. Coordinated beamforming (CBF) can provide dedicated air steering with spatial radiation to suppress interference by means of multiple antennas based on channel state information (CSI) feedback from the coordinating AP. JT / JR can use distributed MIMO precoding or detection via shared CSI for data streams across multiple APs.

[0149] Figure 9 Example network 900, including a set of coordinating APs, is shown. Figure 9 As shown, the coordinated AP set may include AP 902-1 and AP 902-2. The coordinated AP set may be a subset of the established multi-AP group. At least one STA may be associated with each of AP 902-1 and 902-2. For example, STA 904-1 may be associated with AP 902-1, and STA 904-2 may be associated with AP 902-2.

[0150] AP 902-1 and 902-2 can be classified as related to the above.Figure 1 The same ESS is described in [reference to a previous section]. In this case, AP902-1 and 902-2 can be connected via DS to support ESS features. Additionally, as part of a coordinated AP set, APs 902-1 and 902-2 can be connected via backhaul. Backhaul is used to quickly share information between APs to support coordinated transmissions. The shared information can be channel state information or data to be sent to the associated STA. Backhaul can be wired or wireless. Wired backhaul is preferred for high-capacity information transmission without burdening the AP's main radio. However, wired backhaul may require higher deployment costs and may impose greater restrictions on AP placement. Wireless backhaul is preferred due to its lower deployment costs and flexibility in AP placement. However, since wireless backhaul relies on the AP's main radio to transmit information, the AP cannot transmit or receive any data when using wireless backhaul.

[0151] Typically, one of APs 902-1 and 902-2 can act as the primary AP, while the other acts as the secondary AP. The primary AP is the AP that owns the TXOP. The primary AP shares frequency resources with the secondary AP during the TXOP. When there are more than two APs in the coordination set, the primary AP may share its TXOP only with a subset of the coordination set of APs. The role of the primary AP can change over time. For example, the primary AP role may be assigned to a specific AP for a period of time. Similarly, the secondary AP role may be dynamically selected by the primary AP or pre-assigned for a period of time.

[0152] Depending on the capabilities of the APs in the coordination AP set, an AP may perform only a certain type of coordinated transmission. For example, in Figure 9 In this configuration, if AP 902-1 supports JT and CSR, while AP 902-2 supports CSR and CBF, then both APs can execute CSR as the coordinated transmission scheme. If the benefits of coordinated transmission do not outweigh the disadvantages (e.g., reduced required flexibility and increased computational power), then the APs may prefer to execute a single AP transmission for a period of time.

[0153] CSR can be derived from, for example Figure 9The illustrated AP 901-1 and AP 902-2 support one type of multi-AP coordination. Spatial reuse using CSR can be more stable than non-AP coordinated spatial reuse schemes, such as SR based on Overlapping Basic Service Set (OBSS) Packet Detection (PD) and PSR based SR. For example, in example network 900, AP 902-1 and 902-2 can perform joint probe operations to measure path loss (PL) on paths in network 900. For example, the joint probe operation can produce measurements of PL 908 for the path between AP 902-1 and 902-2, path loss 910 for the path between AP 902-1 and STA 904-2, and path loss 912 for the path between AP 902-2 and STA 904-1. The measured path loss information can then be shared between APs 902-1 and 902-2 (e.g., using backhaul) to allow simultaneous transmission to their associated STAs 904-1 and 904-2 via APs 902-1 and 902-2, respectively. Specifically, one of APs 902-1 and 902-2 acquires TXOP to become the master AP. The master AP can then send CSR announcement frames to the other APs. In an embodiment, the master AP may perform a polling operation before sending the CSR announcement frame to poll the slave APs about packet availability for transmission. If at least one slave AP responds indicating packet availability, the master AP may continue sending CSR announcement frames. In the CSR announcement, the master AP may limit the transmission power of the slave APs to protect its own transmission to its target STA. Similarly, the slave APs may protect their own transmission to their target STA by selecting a modulation scheme with a sufficiently high signal-to-interference ratio (SIR) tolerance to support interference caused by the master AP's transmission to its target STA.

[0154] Figure 10 Example 1000 of a multi-AP operating procedure is shown. In example 1000, a multi-AP operating procedure is shown relative to a multi-AP network including APs 1002 and 1004 and STAs 1006 and 1008. In this example, APs 1002 and 1004 can form a multi-AP group. AP 1002 can be the master AP, and AP 1004 can be a slave AP of the multi-AP group. For example, AP 1002 can obtain a TXOP, thereby making it the master AP of the multi-AP group. Alternatively, AP 1002 can be designated as the master AP by a multi-AP controller.

[0155] like Figure 10 As shown, the multi-AP operation procedure may include a series of time periods, each of which may contain multiple frame exchanges within the multi-AP network. Specifically, the multi-AP operation procedure may include a multi-AP selection phase 1010, a multi-AP data sharing phase 1012, a multi-AP detection phase 1014, and a multi-AP data transmission phase 1016.

[0156] Multi-AP networks can operate based on a specific multi-AP transmission scheme. The multi-AP transmission scheme can be selected by the master AP based on the capabilities of the slave APs in the multi-AP group. Before multi-AP operation, slave APs can inform the master AP of their associated capability information, including their ability to support one or more multi-AP transmission schemes. Slave APs can also inform the master AP of the slave APs' BSS information and the link quality information of the STAs associated with the slave APs. The master AP can receive information related to all available slave APs. This information may include capability information, BSS information, and link quality information. Based on the information provided by the available slave APs, the master AP can determine, during the multi-AP selection phase, which slave APs will be designated for multi-AP transmission and the specific multi-AP transmission scheme to be used during multi-AP transmission.

[0157] The multi-AP selection phase 1010 may include procedures for requesting, selecting, or specifying slave APs in a multi-AP group by the master AP. (As in...) Figure 10 As seen, the multi-AP selection phase may include the transmission of frame 1018 from AP 1002 and frame 1020 from AP 1004. AP 1002 may transmit frame 1018 to request information about the buffer status of AP 1004. In response, AP 1004 may transmit frame 1020 to inform AP 1002 of its own and its associated STA's buffer status and / or whether it intends to join the multi-AP operation. The multi-AP selection phase 1010 may also be used to exchange information related to the multi-AP operation, including, for example, the BSS information of the APs and the link quality information between each AP and its associated STAs. The BSS information of the APs may include the BSS ID of the AP's BSS, the identifiers and / or capabilities of the STAs belonging to the BSS, information about the STAs' detection capabilities, information about the AP's MIMO capabilities, etc. The link quality information may include Received Signal Strength Indicator (RSSI), Signal-to-Noise Ratio (SNR), Signal-to-Interference-Ratio (SINR), Channel State Information (CSI), and Channel Quality Indicator (CQI).

[0158] Multi-AP data sharing phase 1012 may include procedures for sharing data frames that will be transmitted from the AP to the associated STA via a direct connection between the master AP and selected slave APs. Phase 1012 may be optional for some multi-AP data transmission schemes. For example, phase 1012 may be necessary for JT / JR because data frames may be exchanged between APs before or after multi-AP data transmission phase 1016.

[0159] The multi-AP data sharing phase 1012 can be performed using wired backhaul, in-channel wireless backhaul, or out-of-channel wireless backhaul. In some cases, the multi-AP data sharing phase 1012 can be performed via in-channel backhaul, for example, using the same wireless channel used to transmit data to / receive data from the STA. For example, as... Figure 10 As shown, in stage 1012, AP 1002 may transmit frame 1022, which may be received by AP 1004. Frame 1022 may include an MPDU that AP 1002 wishes to transmit to an associated STA using multi-AP operation. Similarly, AP 1004 may transmit frame 1024, which may be received by AP 1002. Frame 1024 may include an MPDU that AP 1004 wishes to transmit to an associated STA using multi-AP operation.

[0160] The multi-AP probing phase 1014 may include procedures for multi-AP channel probing, including channel estimation and feedback of the channel estimates among the master AP, candidate slave APs, and associated STAs. For some multi-AP transmission schemes, phase 1014 may be optional, such as COFDMA, CDTMA, and CSR. For example, phase 1014 may be executed by the master AP to assist in resource unit allocation when orchestrating COFDMA transmissions.

[0161] Multi-AP data transmission phase 1016 may include the exchange of data frames between the master AP, slave APs, and their associated STAs based on a multi-AP transmission scheme determined by the master AP. Depending on the multi-AP transmission scheme to be used, phase 1016 may include optional synchronization between APs in the multi-AP group before the exchange of data frames between APs and STAs within the multi-AP group.

[0162] The order of stages 1010, 1012, 1014, and 1016 may differ. Figure 10 The order shown is different. For example, in COFDMA, stage 1016 may occur immediately after stage 1010, while in JT / JR, stage 1012 may occur after stage 1010. Furthermore, as mentioned above, some stages can be optional and may or may not be present. For example, stage 1014 may not be necessary for COFDMA, but it may be necessary for JT / JR.

[0163] Figure 11 Example 1100 of a multi-AP detection phase is shown. Multi-AP detection phase 1100 can be an instance of multi-AP detection phase 1014. For example... Figure 11 As shown, instance 1100 may include a master AP 1102 and a slave AP 1104 in a multi-AP group. Instance 1100 may further include a STA 1106 associated with AP 1102 and a STA 1108 associated with AP 1104.

[0164] like Figure 11 As shown, the multi-AP detection phase 1100 may include frame switching to allow AP 1102 (the master AP) to acquire channel state information (CSI) of the channels in the multi-AP group. In an implementation, phase 1100 may include a first sub-phase 1110 and a second sub-phase 1112.

[0165] During the first sub-phase 1110, the AP can initiate channel sensing and the STA can estimate the CSI. For example, AP 1102 can transmit frame 1114 to AP 1104 (from the AP) to trigger multi-AP sensing. Frame 1114 may contain a multi-AP trigger frame. Subsequently, APs 1102 and 1104 can transmit announcement frames 1116-1 and 1116-2 to their respective associated STAs 1106 and 1108 to announce the transmission of the sensing frames. Frames 1116-1 and 1116-2 may contain multi-AP null packet announcement (NDPA) frames. Frames 1116-1 and 1116-2 may be transmitted simultaneously. Next, APs 1102 and 1104 can transmit frames 1118-1 and 1118-2 to STAs 1106 and 1108, respectively. Frames 1118-1 and 1118-2 may contain multi-AP null packet (NDP) frames. STAs 1106 and 1108 receive frames 1118-1 and 1118-2 respectively, and perform channel estimation for the channels from AP 1102 to STA 1106 and from AP 1104 to STA 1108 respectively.

[0166] During the second sub-phase 1112, the AP may initiate a procedure for the STAs to feed back their channel estimates to the AP. For example, AP 1102 may transmit frame 1120 to trigger STAs 1106 and 1108 to transmit their channel estimates to APs 1102 and 1104, respectively. Frame 1120 may contain multiple AP trigger frames. In response, STAs 1106 and 1108 may transmit frames 1122 and 1124, respectively, containing feedback of the channel estimates to APs 1102 and 1104. Frames 1122 and 1124 may contain NDP feedback frames. The feedback of the channel estimates may include NDP feedback, CSI-related information, beamforming report (BFR), or channel quality indication (CQI) report.

[0167] Figure 12 Example 1200 of a multi-AP downlink data transmission phase is shown. Multi-AP downlink data transmission phase 1200 can be an instance of multi-AP data transmission phase 1016. For example... Figure 12 As shown, instance 1200 may include a master AP 1202 and a slave AP 1204 in a multi-AP group. Instance 1200 may further include a STA 1206 associated with AP 1202 and a STA 1208 associated with AP 1204.

[0168] like Figure 12 As shown, the multi-AP downlink data transmission phase 1200 may include frame switching to enable the master AP 1202 to coordinate with the slave AP 1204 to execute a specific multi-AP transmission scheme together with its associated STAs 1206 and 1208, respectively. The multi-AP transmission scheme may include COFDMA, CTDMA, CSR, CBF, JT / JR, or a combination of two or more of the foregoing schemes.

[0169] like Figure 12 As shown, the primary AP 1202 can initiate phase 1200 by transmitting frame 1210 to AP 1204. Frame 1210 may include information related to AP 1204 (e.g., an identifier for AP 1204), synchronization information, information related to the specific multi-AP transmission scheme to be used, and / or information related to resource elements (RUs) used by AP 1204 to acknowledge frame 1210. Frame 1210 may contain control frames. For example, frame 1210 may contain a multi-AP trigger frame.

[0170] AP 1204 can receive frame 1210 and can use synchronization information to synchronize with the master AP 1202. Subsequently, APs 1202 and 1204 can perform data transmissions to their associated STAs 1206 and 1208, respectively. Specifically, AP 1202 can transmit data frame 1212 to its associated STA 1206, and AP 1204 can transmit data frame 1214 to its associated STA 1208. Depending on the multi-AP transmission scheme used, APs 1202 and 1204 can transmit frames 1212 and 1214 to STAs in different BSSs, respectively. For example, when the multi-AP transmission scheme is JT / JR, AP 1202 can also transmit frame 1212 to STA 1208 associated with AP 1204, and AP 1204 can also transmit frame 1214 to STA 1208 associated with AP 1204. The resources used for transmitting and receiving frames 1212 and 1214 may depend on the specific multi-AP transmission scheme employed.

[0171] STAs 1206 and 1208 can acknowledge frames 1212 and 1214, respectively. For example, STA 1206 can transmit frame 1216 to AP 1202, and STA 1208 can transmit frame 1218 to AP 1204. Frames 1216 and 1218 may contain block acknowledgment (BA) frames. STAs 1206 and 1208 can also transmit frames 1216 and 1218 to APs in different BSSs, depending on the multi-AP transmission scheme used. For example, when the multi-AP transmission scheme is JT / JR, STA 1206 can also transmit frame 1216 to AP 1204, and STA 1208 can also transmit frame 1218 to AP 1202. The resources used for transmitting and receiving frames 1216 and 1218 may depend on the specific multi-AP transmission scheme employed.

[0172] Figure 13 Example 1300 of a multi-AP uplink data transmission phase is shown. Multi-AP uplink data transmission phase 1300 can be an instance of multi-AP data transmission phase 1016. For example... Figure 13 As shown, instance 1300 may include a master AP 1302 and a slave AP 1304 in a multi-AP group. Instance 1300 may further include STAs 1306 and 1308 associated with AP 1302 and STA 1310 associated with AP 1304.

[0173] like Figure 13 As shown, the multi-AP uplink data transmission phase 1300 may include frame switching to enable the master AP 1302 to coordinate with the slave AP 1304 to execute a specific multi-AP transmission scheme together with STAs 1306, 1308, and 1310. The multi-AP transmission scheme may include COFDMA, CTDMA, CSR, CBF, JT / JR, or a combination of two or more of the foregoing schemes.

[0174] like Figure 13 As shown, the primary AP 1302 can initiate phase 1300 by transmitting frame 1312 to AP 1304. Frame 1312 may include information related to AP 1304 (e.g., an identifier for AP 1304), synchronization information, information related to the specific multi-AP transmission scheme to be used, and / or information related to the RU used by AP 1304 to acknowledge frame 1312. Frame 1312 may contain control frames. For example, frame 1312 may contain a multi-AP trigger frame.

[0175] AP 1304 can receive frame 1312 and can use synchronization information to synchronize with the master AP 1302. Subsequently, APs 1302 and 1304 can use trigger frames to request uplink data transmission from their associated STAs 1306, 1308, and 1310. Specifically, AP 1302 can transmit trigger frame 1314 to its associated STAs 1306 and 1308, and AP 1304 can transmit trigger frame 1316 to its associated STA 1310. Depending on the multi-AP transmission scheme used, APs 1302 and 1304 can also transmit frames 1314 and 1316 to STAs in different BSSs, respectively. For example, when the multi-AP transmission scheme is JT / JR, AP 1302 can also transmit frame 1314 to STA 1310 associated with AP 1304, and AP 1304 can also transmit frame 1316 to STAs 1306 and 1308 associated with AP 1302. The resources used for transmitting and receiving frames 1314 and 1316 may depend on the specific multi-AP transmission scheme employed.

[0176] STAs 1306 and 1308 can respond to frame 1314, and STA 1310 can respond to frame 1316. For example, STAs 1306 and 1308 can transmit frames 1318 and 1320 to AP 1302 respectively, while STA 1310 can transmit frame 1322 to AP 1304. Frames 1318, 1320, and / or 1322 can be transmitted simultaneously. Frames 1318, 1320, and 1322 can contain data frames or empty data frames. When required by the multi-AP transmission scheme used, STAs 1306, 1308, and 1310 can also transmit frames 1318, 1320, and 1322 to APs in different BSSs respectively. For example, when the multi-AP transmission scheme is JT / JR, STAs 1306 and 1308 can also transmit the corresponding frames 1318 and 1320 to AP 1304, and STA 1310 can also transmit frame 1322 to AP 1302. The resources used for transmitting and receiving frames 1318, 1320, and 1322 may depend on the specific multi-AP transmission scheme adopted.

[0177] One function of the MAC sublayer is to transfer MAC Service Data Units (MSDUs) between MAC sublayer entities. The information required for the allocation system service operation is provided by the associated service. Before the MSDU can be disposed of by the allocation system service, the STA is "associated".

[0178] According to the IEEE 802.11 standard, there are three types of transitions: a) No transition: In this type, the identifiers are usually indistinguishable between two subcategories: 1) Static - no movement. 2) Local movement - movement within the PHY range of the communication STA, i.e., movement within the Basic Service Area (BSA).

[0179] b) BSS Transition: This type is defined as a STA movement from one BSS within an ESS to another BSS within the same ESS. A fast BSS transition is a BSS transition that occurs before, rather than after, the reassociation required to establish a data connection.

[0180] c) ESS-Transition: This type is defined as a STA movement from a BSS in one ESS to a BSS in a different ESS. This case is supported only in the sense that STAs are movable.

[0181] In the future, when delivering MSDUs within an ESS via the DS, the DS needs to know which AP within the ESS is delivering the MSDU so that it can ultimately be delivered to the addressed IEEE 802.11 STA. This information is provided to the DS through the concept of association. Association is necessary but not sufficient to support BSS changeover mobility. Association is sufficient to support changeover-free mobility. Association is one of the services within the DSS.

[0182] Before a STA can send an MSDU via an AP, it must first become associated with the AP.

[0183] At any given time, a STA is associated with no more than one AP. This allows the DS to determine a unique answer to the question, "Which AP serves STA X?". Once the association is established, the STA can fully utilize the DS (via the AP) to communicate. The association is always initiated by a non-AP STA, not by the AP.

[0184] An AP can be associated with many STAs simultaneously.

[0185] The STA learns which APs exist and what operational capabilities it can acquire from each of those APs, and then invokes the association service to establish an association. FILS STAs can discover, authenticate, and associate with APs with a reduced number of frame transmissions.

[0186] Association is sufficient for transition-free MSDU delivery between IEEE 802.11 STAs. Additional functionality is required to support BSS transition mobility. This additional required functionality is provided by the reassociation service. Reassociation is one of the services within the DSS.

[0187] The reassociation service is invoked to "move" the current association of a non-AP STA from one AP to another. Within an ESS, when a STA moves from a BSS to a BSS within the ESS, the reassociation service informs the DS of the current mapping between the AP and the STA. Reassociation also enables changes to the association attributes of established associations without the non-AP STA remaining associated with the same AP. Reassociation is always initiated by a non-AP STA.

[0188] When an existing association is about to terminate, the unassociation service is invoked. Unassociation is one of the services in DSS.

[0189] The unassociation service can be invoked by either party in the association (neither an AP STA nor an AP). Unassociation is a notification, not a request. The receiving STA cannot refuse to unassociate except when management frame protection is negotiated and message integrity verification fails.

[0190] An AP can unassociate a STA so that the AP can be removed from the network for service or other reasons.

[0191] STAs attempt to disassociate themselves when they leave the network. However, the MAC protocol does not depend on the STA that invokes the disassociation service. (MAC management is designed to accommodate the loss of communication with associated STAs).

[0192] In this example, the PHY layer of a WLAN device (e.g., STA 210 or AP 290) can implement an Extremely High Throughput (EHT) Orthogonal Frequency Division Multiplexing (OFDM) system. The EHT-OFDM system provides data payload communication capabilities for the WLAN.

[0193] Inter-symbol interference (ISI) between temporally adjacent OFDM symbols degrades the orthogonality between subcarriers and impairs performance. ISI can be caused by delay spread in the channel and filtering. To minimize the impact of ISI, a guard interval (GI) is added between adjacent OFDM symbols.

[0194] In this implementation, the cyclic prefix (CP) of the OFDM symbol can be transmitted during the GI. In this implementation, the CP of the OFDM symbol is a prefix of the OFDM symbol (the CP precedes the OFDM symbol) that repeats the end portion of the OFDM symbol in the time domain. In an example, the duration of the GI is equal to the duration of the CP, which is a portion of the discrete Fourier transform (DFT) period of the OFDM symbol.

[0195] EHT PHY provides support for guard interval (GI) durations of 0.8 microseconds, 1.6 microseconds, and 3.2 microseconds.

[0196] EHT PHY provides support for long EHT training field (LTF) symbol durations of 3.2 microseconds (1×), 6.4 microseconds (2×), and 12.8 microseconds (4×) (excluding GI duration).

[0197] EHT PHY supports symbol durations of 3.2 microseconds and 12.8 microseconds (excluding GI) for the EHT pre-modulation field and data field in the EHT PPDU.

[0198] The EHT MU PPDU has a GI duration of 2 × EHT-LTF and 0.8 microseconds on both the EHT-LTF and the OFDM symbol for the data field.

[0199] EHT STA should support the following features: The EHT MU PPDU has a GI duration of 2 × EHT-LTF and 1.6 microseconds on both the EHT-LTF and the OFDM symbol of the data field.

[0200] The EHT MU PPDU has a GI duration of 4 × EHT-LTF and 3.2 microseconds on both the EHT-LTF and the OFDM symbol for the data field.

[0201] The EHT TB PPDU has a GI duration of 1 × EHT-LTF and 1.6 microseconds on both the EHT-LTF and the OFDM symbol for the data field.

[0202] The EHT TB PPDU has a GI duration of 2 × EHT-LTF and 1.6 microseconds on both the EHT-LTF and the OFDM symbol for the data field.

[0203] The EHT TB PPDU has a GI duration of 4 × EHT-LTF and 3.2 microseconds on both the EHT-LTF and the OFDM symbol for the data field.

[0204] EHT STA can support the following features: The EHT MU PPDU has a GI duration of 4 × EHT-LTF and 0.8 microseconds on both the EHT-LTF and the OFDM symbol for the data field.

[0205] The structure of the PPDU transmitted by the EHT STA is determined by the TXVECTOR parameter.

[0206] The FORMAT parameter determines the overall structure of the PPDU and can take one of the following values: Non-HT format (NON_HT), HT mixed format (HT_MF), HT green field format (HT_GF), VHT format (VHT), HE SU PPDU format (HE_SU), HE ERSU format (HE_ER_SU), HE MU PPDU format (HE_MU), HE TB PPDU (HE_TB), EHT MU PPDU format (EHT_MU), and EHT TB PPDU format (EHT_TB).

[0207] EHT PHY provides an interface to the EHT MAC through extensions of the generic PHY service interface. This interface includes TXVECTOR, RXVECTOR, PHYCONFIG_VECTOR, and TRIG_VECTOR.

[0208] The EHT MAC uses TXVECTOR to provide each PPDU transmission parameter to the EHT PHY. The EHT PHY uses RXVECTOR to notify the EHT MAC of the received PPDU parameters. The EHT MAC uses PHYCONFIG_VECTOR to configure the EHT PHY to operate independently of frame transmission or reception. The EHT MAC uses TRIG_VECTOR to configure the EHT PHY to receive EHT TB PPDUs through each assigned RU or MRU.

[0209] The EHT STA can receive PPDUs containing L-STF, L-LTF, L-SIG, RL-SIG, and U-SIG fields, but with a PHY version identifier field in the U-SIG field except for 0. In this case, for backward compatibility, it should still report information about the version-independent fields in the U-SIG field within the RXVECTOR. The value of PHY_VER_UNKNOWN is defined in the RXVECTOR parameter FORMAT to indicate this PPDU format. When the RXVECTOR parameter FORMAT is PHY_VER_UNKNOWN, the RXVECTOR contains only six parameters: FORMAT, RSSI_LEGACY, CH_BANDWIDTH, TXOP_DURATION, BSS_COLOR, and UPLINK_FLAG.

[0210] If the condition FORMAT is EHT_MU or EHT_TB, the parameter GI_TYPE indicates the length of the EHT-LTF and the GI of the data field in both TXVECTOR and RXVECTOR. Enumerated types: 0u8s_GI indicates 0.8 microseconds, 1u6s_GI indicates 1.6 microseconds, and 3u2s_GI indicates 3.2 microseconds. The GI length of the EHT premodulation field is 0.8 microseconds.

[0211] If the condition FORMAT is PHY_VER_UNKNOWN, then the parameter GI_TYPE does not exist.

[0212] During transmission, the PSDU (in the case of SU) or one or more PSDUs (in the case of MU) are processed (i.e., scrambled and encoded) and appended to the PHY preamble to create the PPDU. At the receiver, the PHY preamble is processed to aid in the detection, demodulation, and delivery of the PSDU.

[0213] Two EHT PPDU formats are defined: EHT MU PPDU and EHT TB PPDU.

[0214] Figure 14 This shows another example format of PPDU. A PPDU can be an instance of an EHT MU PPDU that can be transmitted to one or more users.

[0215] like Figure 14 As shown, the EHT MU PPDU includes a non-HT short training field (L-STF), a non-HT long training field (L-LTF), a non-HT signal field (L-SIG), a repeated non-HT signal field (RL-SIG), a universal signal field (U-SIG), an EHT signal field (EHT-SIG), an EHT short training field (EHT-STF), an EHT long training field (EHT-LTF), a data field carrying the PSDU, and a packet extension (PE) field.

[0216] The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields are called EHT pre-modulation fields, while the EHT-STF, EHT-LTF, data, and PE fields are called EHT modulation fields.

[0217] The generation of each field in the EHT PPDU uses many of the following blocks: a) pre-forward error correction (FEC) PHY padding, b) scrambler, c) FEC (Binary Convolutional Code (BCC) or Low-Density Parity-Check (LDPC)) encoder, d) post-FECPHY padding, e) stream parser, f) segment parser (for RU or MRU sizes greater than 996 FM), g) BCC interleaver, h) constellation mapper, i) dual-carrier modulation (DCM) FM mapper, j) leader insertion, k) replication on multiple 20 MHz (for bandwidths greater than 20 MHz), l) LDPC FM mapper, m) segment inverse parser, n) frequency domain replication if EHT-MCS equals 14, o) cyclic shift diversity (CSD) for each spatial stream insertion, p) spatial mapper, q) frequency mapping, r) inverse discrete Fourier transform (IDFT), s) CSD for each chain insertion, t) GI insertion, and u) windowing.

[0218] The GI insertion description for each field in the EHT PPDU encoding process is as follows.

[0219] a) To construct an L-STF field, insert the GI (before T_GI_EHT) of the L-STF field.

[0220] b) To construct an L-LTF field, insert the GI (T_GI_L-LTF) of the L-LTF field.

[0221] c) To construct the L-SIG and RL-SIG fields, insert GI (before T_GI_EHT).

[0222] d) To construct the U-SIG field, insert GI (before T_GI_EHT).

[0223] e) For EHT MU PPDU, construct the EHT-SIG field and insert GI (before T_GI_EHT).

[0224] f) To construct the EHT-STF field, insert GI (T_GI_EHT-STF-NT for EHT MU PPDU, or T_GI_EHT-STF-T for EHT TB PPDU, respectively).

[0225] g) To construct the EHT-LTF field, insert the GI (T_GI_EHT) indicated by the TXVECTOR parameter GI_TYPE.

[0226] h) To construct the data field, insert the GI (T_GI_Data) determined by the TXVECTOR parameter GI_TYPE.

[0227] The timing-related constants are described below.

[0228] The period before T_DFT_EHT is the 3.2 microsecond IDFT / DFT period of the EHT pre-modulation field.

[0229] T_DFT_EHT is the 12.8 microsecond IDFT / DFT period of the EHT data field.

[0230] T_GI_EHT is the 0.8 microsecond GI duration of the EHT pre-modulation field, excluding the L-LTF field.

[0231] T_GI_L-LTF is the 1.6 microsecond GI duration of the L-LTF field.

[0232] T_GI_Data is the duration of the GI for the data field. The value of T_GI_Data is one of T_GI1_Data, T_GI2_Data, or T_GI4_Data, depending on the GI used for the data field.

[0233] T_GI1_Data is the base GI duration of 0.8 microseconds for the data field.

[0234] T_GI2_Data is the 1.6 microsecond double GI duration for the data field.

[0235] T_GI4_Data is the 3.2 microseconds four times the GI duration of the data field.

[0236] T_GI_EHT is the GI duration of the EHT-LTF field, which is the same as T_GI_Data.

[0237] T_GI_EHT-STF-NT is the 0.8 microsecond GI duration of the EHT MU PPDU.

[0238] T_GI_EHT-STF-T is the 1.6 microsecond GI duration of the EHT TB PPDU.

[0239] T_SYM indicates the OFDM symbol interval for the EHT data field. The value of T_SYM is one of T_SYM1, T_SYM2, or T_SYM4, depending on the GI used for the EHT data field.

[0240] T_SYM1 indicates the duration of an OFDM symbol with a base GI, where the value of T_SYM1 is 13.6 microseconds = T_DFT_EHT + T_GI1_Data = 1.0625 × T_DFT_EHT.

[0241] T_SYM2 indicates the duration of an OFDM symbol with double GI, where the value of T_SYM2 is 14.4 microseconds = T_DFT_EHT + T_GI2_Data = 1.125 × T_DFT_EHT.

[0242] T_SYM4 indicates the OFDM symbol duration with four times the GI, where the value of T_SYM4 is 16 microseconds = T_DFT_EHT + T_GI4_Data = 1.25 × T_DFT_EHT.

[0243] T_L-STF indicates the duration of a non-HT short training field. The value of T_L-STF is 8 microseconds = 10 × T_DFT_EHT before / 4.

[0244] T_L-LTF indicates the duration of a non-HT long training field. The value of T_L-LTF is 8 microseconds = 2 × T_DFT_EHT_before + T_GI_L-LTF.

[0245] T_L-SIG indicates the duration of the non-HT signal field. The value of T_L-SIG is 4 microseconds.

[0246] T_RL-SIG indicates the duration of the repetitive non-HT signal field. The value of T_RL-SIG is 4 microseconds.

[0247] T_U-SIG indicates the duration of the U-SIG field in the EHT PPDU. The value of T_U-SIG is 8 microseconds = 2 × 4 microseconds.

[0248] T_U-SIG-R indicates the duration of the U-SIG field in the EHT ER preamble. The value of T_U-SIG is 16 microseconds = 4 × 4 microseconds.

[0249] T_EHT-SIG indicates the duration of each OFDM symbol in the EHT-SIG field. The value of T_EHT-SIG is 4 microseconds = T_DFT_EHT_before + T_GI_EHT_before.

[0250] T_EHT-STF-T indicates the duration of the EHT-STF field in the EHT TB PPDU. The value of T_EHT-STF-T is 8 microseconds = 5 × 1.6 microseconds.

[0251] T_EHT-STF-NT indicates the duration of the EHT-STF field in the EHT MU PPDU. The value of T_EHT-STF-NT is 4 microseconds = 5 × 0.8 microseconds.

[0252] T_EHT-LTF indicates the duration of each OFDM symbol that does not have a GI in the EHT-LTF field. The value of T_EHT-LTF is one of T_EHT-LTF-1X, T_EHT-LTF-2X, or T_EHT-LTF-4X, depending on the EHT-LTF duration used.

[0253] T_EHT-LTF-1X indicates the duration of each 1× EHT-LTF OFDM symbol without GI. The value of T_EHT-LTF-1X is 3.2 microseconds.

[0254] T_EHT-LTF-2X indicates the duration of each 2× EHT-LTF OFDM symbol without GI. The value of T_EHT-LTF-2X is 6.4 microseconds.

[0255] T_EHT-LTF-4X indicates the duration of each 4× EHT-LTF OFDM symbol without GI. The value of T_EHT-LTF-4X is 12.8 microseconds.

[0256] T_EHT-LTF-SYM indicates the duration of each OFDM symbol that includes GI in the EHT-LTF field.

[0257] T_SYML indicates the duration of OFDM symbols that include GI in the EHT pre-modulation field.

[0258] T_PE indicates the duration of the PE field. The value of T_PE is one of 0, 4 microseconds, 8 microseconds, 12 microseconds, 16 microseconds, or 20 microseconds, depending on the actual packet extension duration used.

[0259] It is anticipated that the future IEEE 802.11 standard will provide various mechanisms to support the low latency and high throughput Quality of Service (QoS) requirements of APs and STAs.

[0260] Inter-symbol interference (ISI) between temporally adjacent OFDM symbols degrades the orthogonality between subcarriers and impairs performance. ISI can be caused by delay spread in the channel and filtering. To minimize the impact of ISI, a guard interval (GI) is added between adjacent OFDM symbols.

[0261] The required GI duration for transmission can be determined based on various factors. These factors may include, for example, the size of the Discrete Fourier Transform (DFT) used in the PPDU field, the delay spread of the channel state information, and the modulation and coding scheme (MCS) order. In practice, the GI duration for transmission could include a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds.

[0262] For example, in a single AP transmission, the first STA receiving the first PPDU from the AP may experience different delay spreads compared to the second STA receiving the first PPDU from the AP. In another instance, the AP transmitting the second PPDU to the first STA may use a different MCS order compared to transmitting the second PPDU to the second STA. Therefore, the AP can determine whether to use GIs with different durations to receive from or transmit to both the first and second STAs. For example, the AP could choose a GI with double the GI duration to meet the requirement of transmitting to both STAs.

[0263] Similarly, in a multi-AP transmission involving at least two APs, each AP may require a different GI for its transmission.

[0264] Figure 15 This illustrates an example 1500 of an existing multi-AP transmission procedure. For example, example 1500 could be an example of multi-AP data transmission stage 1016. Figure 15 As shown, instance 1500 includes AP 1502, AP 1504, STA 1506, and STA 1508. In this instance, AP 1502 can be the primary AP, and AP 1504 can be a secondary AP. In this instance, STA 1506 can be associated with AP 1502, and STA 1508 can be associated with AP 1504.

[0265] In the examples, AP 1502 and 1504 can be classified as similar to those mentioned above. Figure 1 The same ESS is described in the document. In this case, APs 1502 and 1504 can be connected by DS to support ESS features. In this example, APs 1502 and 1504 belong to different BSSs.

[0266] In this example, APs 1502 and 1504 can form a multi-AP group. In this example, APs 1502 and 1504 can complete the multi-AP setup procedure before starting instance 1500. Additionally, as part of the multi-AP group, APs 1502 and 1504 can be connected via backhaul. In this example, the backhaul can be wireless.

[0267] Before instance 1500 begins, APs 1502 and 1504 can complete the multi-AP selection phase 1010, the optional multi-AP data sharing phase 1012, and the optional multi-AP probing phase 1014, as follows: Figure 10 As described in the text.

[0268] like Figure 15As shown, Example 1500 may include frame switching to enable AP 1502 to coordinate with AP 1504 to perform multi-AP transmission using a specific multi-AP transmission scheme with its associated STAs 1506 and 1508, respectively. The multi-AP transmission scheme may include COFDMA, CTDMA, CSR, CBF, JT / JR, or a combination of two or more of the foregoing schemes.

[0269] like Figure 15 As shown, Example 1500 can begin with AP 1502 transmitting frame 1510 to AP 1504. Frame 1510 may include information related to AP 1504 (e.g., an identifier for AP 1504), synchronization information, information related to a specific multi-AP transmission scheme to be used, and / or information related to resource elements (RUs) used by AP 1504 to acknowledge frame 1510. Frame 1510 may contain control frames. For example, frame 1510 may contain a multi-AP trigger frame.

[0270] Frame 1510 may also include information related to the guard interval (GI) used by APs 1502 and 1504 for downlink transmissions to STAs 1506 and 1508, respectively. In an example, the GI-related information may include an indication of the GI duration (such as 0.8 microseconds, 1.6 microseconds, or 3.2 microseconds) or an indication of the GI type (such as “basic GI duration”, “double GI duration”, or “quadruple GI duration”).

[0271] In this example, AP 1502 can determine the GI duration or GI type based on AP 1502's local information. For instance, AP 1502's local information may include GIs used for downlink transmissions from AP 1502 to its associated STA 1506.

[0272] AP 1504 can receive frame 1510 and can use synchronization information to synchronize with AP 1502.

[0273] Subsequently, APs 1502 and 1504 can perform downlink transmissions to their associated STAs 1506 and 1508, respectively. Specifically, AP 1502 can transmit frame 1512 to STA 1506 using the GI indicated in frame 1510. Simultaneously, AP 1504 can transmit frame 1514 to STA 1508 using the GI indicated in frame 1510.

[0274] AP 1502 can determine the GI indicated in frame 1510 based on the GI duration required to transmit frame 1512 to STA 1506. The GI duration required to transmit frame 1512 is based on the DFT size of the field used to carry frame 1512.

[0275] In this example, the GI durations required for the transmission of frames 1512 and 1514 may differ. In this example, the channel from AP1504 to STA 1508 may exhibit a longer delay spread than the channel from AP 1502 to STA 1506. Therefore, the GI duration required for transmitting frame 1514 from AP 1504 may be longer than the GI duration required for transmitting frame 1512 from AP 1502. For example, AP 1502 transmitting frame 1512 might require a GI duration equal to 1.6 microseconds, which is "double the GI duration." Similarly, AP 1504 transmitting frame 1514 might require a GI duration longer than 1.6 microseconds, which is "double the GI duration."

[0276] In this example, AP 1502 can select a "double GI duration" of 1.6 microseconds for the GI indicated in frame 1510 based on the requirements of transmit / receive frame 1512. Therefore, STA 1506 can receive frame 1512 from AP 1502 without experiencing inter-symbol interference (ISI) between adjacent OFDM symbols carrying the PPDU of frame 1512. STA 1506 can acknowledge frame 1512 by transmitting a BlockAck (BA) frame 1516 to AP 1502. However, because the selected GI indicated in frame 1510 is shorter than the GI required by transmit / receive frame 1514, STA 1508 may experience inter-symbol interference between adjacent OFDM symbols when receiving the PPDU carrying frame 1514. In this example, STA 1508 may not be able to decode frame 1514 correctly and may not be able to acknowledge frame 1514.

[0277] As illustrated in Example 1500, an inappropriate selection of the GI duration for multi-AP transmissions by AP 1502 can lead to transmission failures from AP1504 to STA 1508. This can reduce reliability, increase retransmissions, and introduce significant latency and overhead in multi-AP networks.

[0278] As further described below, embodiments of this disclosure address the aforementioned problems of existing multi-AP procedures. In a first aspect, a first AP may receive a first frame from a second AP, the first frame indicating a first guard interval (GI). The first GI may be used for transmissions from the second AP to a STA or vice versa. The first AP may transmit a second frame to the second AP, the second frame indicating a second GI. The second GI may be used for transmissions from the second AP to a STA or vice versa. In embodiments, the second GI may be based on the first GI. In embodiments, the transmission from the second AP to a STA or vice versa may be part of a multi-AP transmission including both the first and second APs. The first AP may select the second GI to accommodate all transmissions in the multi-AP transmission (e.g., to reduce or eliminate ISI for it). Therefore, the reliability of the multi-AP transmission can be improved, and latency caused by unsuccessful transmissions can be reduced.

[0279] Figure 16 This is example 1600 illustrating a guard interval (GI) coordination procedure for multi-AP communication according to an embodiment. Example 1600 is provided for illustrative purposes only and is not limiting. Figure 16 As shown, Instance 1600 includes AP 1602, AP 1604, STA 1606, and STA 1608. In this instance, STA 1606 may be associated with AP 1602. In this instance, STA 1608 may be associated with AP 1604. AP 1602, AP 1604, STA 1606, and / or STA 1608 may each contain a multilink device (MLD).

[0280] In the examples, AP 1602 and 1604 can be classified as similar to those mentioned above. Figure 1 The same ESS is described in the document. In this case, APs 1602 and 1604 can be connected by DS to support ESS features. In this example, APs 1602 and 1604 belong to different BSSs. In an embodiment, AP 1602 may belong to a first BSS, and AP 1604 may belong to a second BSS. In an embodiment, the second BSS may contain an Overlapping Basic Service Set (OBSS) relative to the first BSS.

[0281] In this embodiment, APs 1602 and 1604 may form a multi-AP group. It is assumed that in instance 1600, APs 1602 and 1604 can complete the multi-AP setup procedure before instance 1600 begins. Additionally, as part of the multi-AP group, APs 1602 and 1604 may be connected via backhaul. In this example, the backhaul may be a wireless backhaul.

[0282] Before instance 1600 begins, APs 1602 and 1604 can complete the multi-AP selection phase 1010, the optional multi-AP data sharing phase 1012, and the optional multi-AP probing phase 1014, as follows: Figure 10 As described in the text.

[0283] like Figure 16 As shown, Instance 1600 may include frame switching to enable AP 1602 to coordinate with AP 1604 to perform multi-AP transmission using a specific multi-AP transmission scheme with its associated STAs 1606 and 1608, respectively. The multi-AP transmission scheme may include COFDMA, CTDMA, CSR, CBF, JT / JR, or a combination of two or more of the foregoing schemes.

[0284] Assume that in instance 1600, both AP 1602 and AP 1604 support GI coordination capability. In this instance, support for GI coordination capability allows AP 1604 to transmit frames (such as frame 1610 described below) to share information related to the first GI with AP 1602. In this instance, support for GI coordination capability allows AP 1602 to receive and process frames (such as frame 1610) and transmit frames (such as frame 1620 described below) to determine a second GI for multi-AP transmission based on the first GI. In another instance, support for GI coordination capability allows AP 1602 and AP 1604 to transmit frames (such as frames 1622 and 1624 described below) to STA 1606 and 1608 respectively using the second GI.

[0285] In the embodiment, in instance 1600 ( Figure 16 Before the start (not shown), APs 1602 and 1604 may exchange a first frame and a second frame to exchange capability information. In an embodiment, the first frame may contain capability information for AP 1602, including a first indication of AP 1602's support for GI coordination capabilities. In an embodiment, the second frame may contain capability information for AP 1604, including a second indication of AP 1604's support for GI coordination capabilities. In an embodiment, the first and second frames may be exchanged during a multi-AP setup procedure or a multi-AP selection phase. In an embodiment, the first and second frames may include management frames.

[0286] like Figure 16 As shown, instance 1600 may begin with AP 1604 transmitting frame 1610 to AP 1602 indicating a first GI. In an embodiment, the first GI may be used for a first transmission from AP 1604 to STA 1608. In an embodiment, frame 1610 may contain a request to AP 1602 for AP 1604 to use the first GI for the first transmission.

[0287] In an embodiment, frame 1610 may include management frames or data frames.

[0288] In an embodiment, AP 1604 may determine a first GI from a set of GIs. For example, the first GI may include a duration selected from a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds. In an example, AP 1604 may select the first GI based on the delay spread of the channel from AP 1604 to STA 1608, within which the first transmission will be transmitted. In an example, AP 1604 may determine that the first transmission requires a GI duration longer than the "double GI duration". For example, AP 1604 may determine that the first transmission must use a GI duration at least equal to the "quadruple GI duration" of 3.2 microseconds to avoid ISI at STA 1608.

[0289] In an embodiment, the first transmission may include the transmission of a PPDU. The PPDU may include frame 1624. A first GI may be used for the data field of the PPDU. That is, the first GI may be used in the OFDM symbol of the data field of the PPDU. In an embodiment, the first transmission may be scheduled during a transmission opportunity (TXOP) owned / acquired by AP 1602. In an embodiment, the first transmission may be part of a multi-AP transmission initiated by AP 1602 and including AP 1604.

[0290] like Figure 16 As shown, AP 1602 can transmit frame 1612 to AP 1604 to acknowledge receipt of frame 1610. In an example, frame 1612 may contain an acknowledgment frame. For example, frame 1612 may contain a BlockAck (BA) frame. In an embodiment, frame 1612 may contain a response to frame 1610.

[0291] In an embodiment, AP 1602 may transmit frame 1620 to AP 1604, the frame indicating a second GI. For example, the second GI may include a duration selected from a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds.

[0292] In an embodiment, the second GI can be used for a first transmission from AP 1604 to STA 1608 and for a second transmission from AP 1602 to STA 1606. The second transmission may include frame 1622.

[0293] In this example, the required GI durations for the first transmission from AP 1604 to STA 1608 and the second transmission from AP 1602 to STA 1606 can differ. In this example, the channel from AP 1604 to STA 1608 may exhibit a longer delay spread than the channel from AP 1602 to STA 1606. Therefore, the required GI duration for the first transmission can be longer than the required GI duration for the second transmission. For example, the second transmission might require a GI duration equal to "double the GI duration" of 1.6 microseconds. Therefore, the first transmission might require a GI duration longer than "double the GI duration" of 1.6 microseconds.

[0294] In an embodiment, AP 1602 can determine the second GI based on the first GI. For example, the second GI can be at least equal to the first GI. In an embodiment, AP 1602 can select the second GI such that it satisfies the GI duration required for both the first and second transmissions. In an embodiment, the first transmission can use the second GI. In an embodiment, the second transmission can also use the second GI. Therefore, STAs 1608 and 1606 can receive the first and second transmissions respectively without experiencing an ISI.

[0295] In an embodiment, the second transmission may include a second PPDU. The second PPDU may include frame 1622. A second GI may be used in the data field of the second PPDU. That is, the second GI may be used in the OFDM symbol of the data field of the second PPDU. In an embodiment, the second transmission may be scheduled during a TXOP owned / acquired by AP 1602. In an embodiment, the second transmission may be part of a multi-AP transmission initiated by AP 1602 and including AP 1604.

[0296] In this embodiment, frame 1620 can initiate a multi-AP transmission. In this example, the multi-AP transmission can include a first transmission and a second transmission. In this embodiment, AP 1602 can transmit frame 1620, which triggers AP 1604, for multi-AP transmission.

[0297] In an embodiment, frame 1620 may allow the first transmission of frame 1624 to be synchronized with the second transmission of frame 1622.

[0298] In this embodiment, frame 1620 may include a trigger frame. In an example, frame 1620 may include multiple AP trigger frames.

[0299] like Figure 16As shown, STA 1606 can transmit frame 1626 to acknowledge receipt of frame 1622. In an embodiment, STA 1608 can transmit frame 1628 to acknowledge receipt of frame 1628. In an example, frames 1626 and 1628 may contain BA frames.

[0300] Figure 17 This is example 1700 illustrating another guard interval (GI) coordination procedure for multi-AP communication according to an embodiment. Example 1700 is provided for illustrative purposes only and is not limiting. Figure 17 As shown, Instance 1700 includes AP1702, AP1704, STA1706, and STA1708. In this instance, STA1706 may be associated with AP1702. In this instance, STA1708 may be associated with AP1704. AP1702, AP1704, STA1706, and / or STA1708 may contain multi-link devices (MLDs).

[0301] In the examples, AP 1702 and 1704 can be classified as similar to those mentioned above. Figure 1 The same ESS is described in the document. In this case, APs 1702 and 1704 can be connected by a DS to support ESS features. In this example, APs 1702 and 1704 belong to different BSSs. In an embodiment, AP 1702 may belong to a first BSS, and AP 1704 may belong to a second BSS. In an embodiment, the second BSS may contain an Overlapping Basic Service Set (OBSS) relative to the first BSS.

[0302] In this embodiment, APs 1702 and 1704 may form a multi-AP group. It is assumed that in instance 1700, APs 1702 and 1704 can complete the multi-AP setup procedure before instance 1700 begins. Additionally, as part of the multi-AP group, APs 1702 and 1704 may be connected via backhaul. In this example, the backhaul may be a wireless backhaul.

[0303] Before instance 1700 begins, AP 1702 and AP 1704 can complete the multi-AP selection phase 1010 and the optional multi-AP data sharing phase 1012, such as... Figure 10 As described in the text.

[0304] like Figure 17 As shown, instance 1700 may include frame switching so that AP 1702 can coordinate with AP 1704 to perform channel detection for multi-AP transmission together with its associated STAs 1706 and 1708, respectively.

[0305] Assume that in Instance 1700, both AP 1702 and AP 1704 support GI coordination capabilities. In this instance, support for GI coordination capabilities allows AP 1702 to transmit a frame (frame 1710 as described below) to request a first GI from AP 1704. In this instance, support for GI coordination capabilities allows AP 1704 to receive and process frames (such as frame 1710) and transmit frames (such as frame 1712 as described below) to share information related to the first GI with AP 1702. In this instance, support for GI coordination capabilities allows AP 1702 to receive and process frames (such as frame 1712) and transmit frames (such as frame 1720 as described below) to determine a second GI for the probe phase of multi-AP transmission based on the first GI. In another instance, support for GI coordination capabilities allows AP 1702 and AP 1704 to transmit frames (such as frames 1722 and 1724 as described below) to STAs 1706 and 1708 respectively using the second GI.

[0306] In the embodiment, in instance 1700 ( Figure 17 Before the start (not shown), APs 1702 and 1704 may exchange a first frame and a second frame to exchange capability information. In an embodiment, the first frame may contain capability information for AP 1702, including a first indication of AP 1702's support for GI coordination capabilities. In an embodiment, the second frame may contain capability information for AP 1704, including a second indication of AP 1704's support for GI coordination capabilities. In an embodiment, the first and second frames may be exchanged during a multi-AP setup procedure or a multi-AP selection phase. In an embodiment, the first and second frames may include management frames.

[0307] like Figure 17 As shown, Example 1700 may begin with AP 1702 transmitting frame 1710 requesting a first GI to AP 1704. In this embodiment, frame 1710 may request feedback from AP 1704. In this embodiment, the first GI may be used for a first transmission from AP 1704 to STA 1708. In this embodiment, the first GI may be used by AP 1704 to perform a first transmission using the first GI.

[0308] In one embodiment, frame 1710 may include a management frame, which includes an action frame. In another embodiment, frame 1710 may include a control frame, which includes a trigger frame.

[0309] In an embodiment, AP 1704 may transmit frame 1712 in response to frame 1710. In an embodiment, frame 1712 may contain feedback requested by frame 1710. In an embodiment, frame 1712 may indicate a first GI as requested in frame 1710.

[0310] In one embodiment, frame 1712 may include a management frame, which in turn includes an action frame. In another embodiment, frame 1712 may include a data frame, which in turn includes a QoS empty frame.

[0311] In an embodiment, AP 1704 may determine a first GI from a set of GIs. For example, the first GI may include a duration selected from a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds. In an example, AP 1704 may select the first GI based on the delay spread of the channel from AP 1704 to STA 1708, within which the first transmission will be transmitted. In an example, AP 1704 may determine that the first transmission requires a GI duration longer than the "double GI duration". For example, AP 1704 may determine that the first transmission must use a GI duration at least equal to the "quadruple GI duration" of 3.2 microseconds to avoid ISI at STA 1708.

[0312] In an embodiment, the first transmission may include the transmission of a PPDU. The PPDU may include frames 1724 and / or 1728. A first GI may be used for the training field of the PPDU. That is, the first GI may be used in the OFDM symbol of the training field of the PPDU. In an embodiment, the training field may include a short training field or a long training field. In an example, frame 1724 may include a Null Packet Advertisement (NDPA) frame. In an example, frame 1728 may include a Null Packet (NDP) frame. In an embodiment, the first transmission may be scheduled during a TXOP owned / acquired by AP 1702. In an embodiment, the first transmission may be part of a probe phase of a multi-AP transmission initiated by AP 1702 and including AP 1704.

[0313] In an embodiment, AP 1702 may transmit frame 1720 to AP 1704, the frame indicating a second GI. For example, the second GI may include a duration selected from a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds.

[0314] In an embodiment, the second GI can be used for a first transmission from AP 1704 to STA 1708 and for a second transmission from AP 1702 to STA 1706. The second transmission can include frame 1722 and / or frame 1726. The first and second transmissions can form a multi-AP transmission. The multi-AP transmission can be a coordinated multi-AP transmission.

[0315] In this example, the required GI durations for the first transmission from AP 1704 to STA 1708 and the second transmission from AP 1702 to STA 1706 may differ. In this example, the channel from AP 1704 to STA 1708 may exhibit a longer delay spread than the channel from AP 1702 to STA 1706. In this example, the required GI duration for the first transmission may be longer than the required GI duration for the second transmission. For example, the second transmission might require a GI duration equal to "double the GI duration" of 1.6 microseconds. Therefore, the first transmission might require a GI duration longer than "double the GI duration" of 1.6 microseconds.

[0316] In an embodiment, AP 1702 can determine the second GI based on the first GI. For example, the second GI can be at least equal to the first GI. In an embodiment, AP 1702 can select the second GI such that it satisfies the GI duration required for both the first and second transmissions. In an embodiment, the first transmission can use the second GI. In an embodiment, the second transmission can also use the second GI. Therefore, STAs 1708 and 1706 can receive the first and second transmissions respectively without experiencing an ISI.

[0317] In an embodiment, the second transmission may include the transmission of a second PPDU. The second PPDU may include frame 1722 or frame 1726. A second GI may be used for the training field of the second PPDU. That is, the second GI may be used in the OFDM symbols of the training field of the second PPDU. In an embodiment, the training field of the second PPDU may include a short training field or a long training field. In an example, frame 1722 may include an NDPA frame. In an example, frame 1726 may include an NDP frame. In an embodiment, the second transmission may be scheduled during a TXOP owned / acquired by AP 1702. In an embodiment, the second transmission may be part of a probe phase of a multi-AP transmission initiated by AP 1702 and including AP 1704.

[0318] In one embodiment, frame 1720 can initiate the probe phase of multi-AP transmission. In another embodiment, AP 1702 can transmit frame 1720, which triggers AP 1704, for the probe phase of multi-AP transmission.

[0319] In one embodiment, frame 1720 may allow transmission synchronization of frames 1724 and 1722. In another embodiment, frame 1720 may further allow transmission synchronization of frames 1726 and 1728.

[0320] In this embodiment, frame 1720 may include a trigger frame. In this example, frame 1720 may include multiple AP trigger frames.

[0321] Figure 18 This is example 1800 illustrating another guard interval (GI) coordination procedure for multi-AP communication according to an embodiment. Example 1800 is provided for illustrative purposes only and is not limiting. Figure 18 As shown, Instance 1800 includes AP1802, AP1804, STA1806, and STA1808. In this instance, STA1806 may be associated with AP1802. In this instance, STA1808 may be associated with AP1804. AP1802, AP1804, STA1806, and / or STA1808 may contain multi-link devices (MLDs).

[0322] In the examples, AP 1802 and 1804 can be classified as similar to those mentioned above. Figure 1 The same ESS is described in the document. In this case, APs 1802 and 1804 can be connected by a DS to support ESS features. In this example, APs 1802 and 1804 belong to different BSSs. In an embodiment, AP 1802 may belong to a first BSS, and AP 1804 may belong to a second BSS. In an embodiment, the second BSS may contain an Overlapping Basic Service Set (OBSS) relative to the first BSS.

[0323] In this embodiment, APs 1802 and 1804 may form a multi-AP group. It is assumed that in instance 1800, APs 1802 and 1804 can complete the multi-AP setup procedure before instance 1800 begins. Additionally, as part of the multi-AP group, APs 1802 and 1804 may be connected via backhaul. In this example, the backhaul may be a wireless backhaul.

[0324] Before instance 1800 begins, AP 1802 and AP 1804 can complete the multi-AP selection phase 1010 and the optional multi-AP data sharing phase 1012, such as... Figure 10 As described in the text.

[0325] like Figure 18 As shown, instance 1800 may include frame switching so that AP 1802 can coordinate with AP 1804 to perform channel sounding and multi-AP transmission together with its associated STAs 1806 and 1808, respectively.

[0326] Assume that in Instance 1800, both AP 1802 and AP 1804 support GI coordination capabilities. In this instance, support for GI coordination capabilities allows AP 1802 to transmit frames (such as frame 1810 described below) to request a first GI and a second GI from AP 1804. In this instance, support for GI coordination capabilities allows AP 1804 to receive and process frames (such as frame 1810) and transmit frames (such as frame 1812 described below) to share information related to the first and second GIs with AP 1802. In this instance, support for GI coordination capabilities allows AP 1802 to receive and process frames (such as frame 1812) and transmit frames (such as frame 1822 described below) to determine a third GI for the probe phase of a multi-AP transmission based on the first GI. In this instance, support for GI coordination capabilities allows AP 1802 to receive and process frames (such as frame 1812) and transmit frames (such as frame 1826 described below) to determine a fourth GI for a multi-AP transmission based on the second GI. In another instance, support for GI coordination capabilities allows AP 1802 and AP 1804 to use a third GI to coordinate frames (as in...). Figure 17 Frames 1722, 1724, 1726, and 1728 in stage 1820 described in the text are transmitted to STAs 1806 and 1808, and frames (as described in the text) are transmitted using the fourth GI. Figure 16 Frames 1622 and 1624 in stage 1824 described in the document are transmitted to STAs 1806 and 1808.

[0327] In the embodiment, in instance 1800 ( Figure 18 Before the start (not shown), APs 1802 and 1804 may exchange a first frame and a second frame to exchange capability information. In an embodiment, the first frame may contain capability information for AP 1802, including a first indication of AP 1802's support for GI coordination capabilities. In an embodiment, the second frame may contain capability information for AP 1804, including a second indication of AP 1804's support for GI coordination capabilities. In an embodiment, the first and second frames may be exchanged during a multi-AP setup procedure or a multi-AP selection phase. In an embodiment, the first and second frames may include management frames.

[0328] like Figure 18 As shown, instance 1800 may begin with frame 1810, in which AP 1802 transmits a request for a first GI and a second GI to AP 1804. In an embodiment, frame 1810 may request feedback from AP 1804. In an embodiment, the first GI may be used for a first transmission from AP 1804 to STA 1808 in phase 1820. In an embodiment, the second GI may be used for a second transmission from AP 1804 to STA 1808 in phase 1824.

[0329] In one embodiment, frame 1810 may include a management frame, which includes an action frame. In another embodiment, frame 1810 may include a control frame, which includes a trigger frame.

[0330] In an embodiment, AP 1802 can request the first GI and the second GI by transmitting a separate frame similar to frame 1810 to AP 1804.

[0331] In an embodiment, AP 1804 may transmit frame 1812 in response to frame 1810. In an embodiment, frame 1812 may contain feedback requested by frame 1810. In an embodiment, frame 1812 may indicate a first GI and a second GI as requested in frame 1810.

[0332] In an embodiment, the first GI and the second GI may be indicated in a separate frame similar to frame 1812 in response to a separate frame similar to frame 1810 from AP 1802.

[0333] In one embodiment, frame 1812 may include a management frame, which in turn includes an action frame. In another embodiment, frame 1812 may include a data frame, which in turn includes a QoS empty frame.

[0334] In an embodiment, AP 1804 can determine a first GI and a second GI from a set of GIs. For example, the first GI and / or the second GI may include a duration selected from a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds. In an example, AP 1804 may select the first GI based on the delay spread of the channel from AP 1804 to STA 1808, with the first transmission being transmitted in the delay spread intrinsic phase 1820. In an example, AP 1802 may select the second GI based on the delay spread of the channel from AP 1804 to STA 1808, with the second transmission being transmitted in the delay spread intrinsic phase 1824. In an example, the first GI and the second GI may be based on the type of information carried by the first transmission (e.g., a training field) and the second transmission (e.g., a data field), respectively.

[0335] In an embodiment, the first transmission in stage 1820 may include a first PPDU. The first PPDU may include a frame (e.g., Figure 17(Frame 1724 or Frame 1728 described herein). The first GI can be used as a training field for the first PPDU. In embodiments, the training field can include a short training field or a long training field. In an example, the first PPDU can include an NDPA frame and / or an NDP frame. In embodiments, the first transmission can be scheduled during a first TXOP owned / acquired by AP 1802. In embodiments, the first transmission can be part of a probe phase of a multi-AP transmission initiated by AP 1802 and including AP 1804.

[0336] In an embodiment, the second transmission in stage 1824 may include a second PPDU. The second PPDU may include a frame (such as...). Figure 16 (Frame 1624 described herein). The second GI can be used for the data field of the second PPDU. In an embodiment, the second transmission can be scheduled during a second TXOP owned / acquired by AP 1802. In one instance, the second TXOP can be the same as the first TXOP. In another instance, the second TXOP can be different from the first TXOP. In an embodiment, the second transmission can be part of a multi-AP transmission initiated by AP 1802 and including AP 1804.

[0337] In this example, AP 1804 can select the same first GI and second GI. For instance, AP 1804 can determine that both the first and second transmissions require a GI duration longer than "double GI duration". For example, AP 1804 can determine that the first and second GIs must use a "quadruple GI duration" of 3.2 microseconds to avoid ISI at STA 1808.

[0338] In another example, AP 1804 can select different first and second GIs. In this example, AP 1804 can determine that a field of the first PPDU in the first transmission requires a longer GI duration than a field of the second PPDU in the second transmission requires. For example, AP 1804 can determine the first GI to be a "base GI duration" of 3.2 microseconds and the second GI to be a "quadruple GI duration" of 1.6 microseconds to avoid ISI at STA 1808.

[0339] In an embodiment, AP 1802 may transmit frame 1822 to AP 1804, the frame indicating a third GI. For example, the third GI may include a duration selected from a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds.

[0340] In an embodiment, the third GI can be used for the first transmission from AP 1804 to STA 1808 in phase 1820 and / or the third transmission from AP 1802 to STA 1806 in phase 1820. In an example, the third transmission may include frames (such as...) Figure 17 (Frame 1722 or Frame 1726 as described in the document).

[0341] In this example, the GI duration required for the first transmission from AP 1804 to STA 1808 and the third transmission from AP 1802 to STA 1806 can differ in phase 1820. In this example, in phase 1820, frames are transmitted from AP 1804 (such as...). Figure 17 The GI duration required for the first transmission of frames 1724 or 1728 described in the document can be longer than the transmission duration of frames from AP 1802 (such as...). Figure 17 The third transmission in frames 1722 or 1726 described herein requires a longer GI duration. For example, the first transmission in phase 1820 may require a GI duration equal to the “base GI duration” of 0.8 microseconds. For example, the second transmission in phase 1820 may require a GI duration longer than the “double GI duration” of 1.6 microseconds.

[0342] In an embodiment, AP 1802 may determine a third GI based on a first GI. For example, the third GI may be at least equal to the first GI. In an embodiment, AP 1802 may select a third GI such that it satisfies both the GI duration required for the first transmission and the GI duration required for the third transmission.

[0343] In one embodiment, the first transmission in stage 1820 may use a third GI. In another embodiment, the third transmission in stage 1820 may also use a third GI. Therefore, STAs 1808 and 1806 may receive the first and third transmissions respectively without undergoing an ISI.

[0344] In an embodiment, the third transmission may include a third PPDU. The third PPDU may include a frame (e.g., Figure 17 (Frame 1722 or Frame 1726 described herein). The third GI can be used in the training field of the third PPDU. That is, the third GI can be used in the OFDM symbol of the training field of the third PPDU. In an embodiment, the training field can include a short training field or a long training field. In an embodiment, the third transmission can be scheduled during the first TXOP owned / acquired by AP 1802. In an embodiment, the third transmission can be part of the probe phase of a multi-AP transmission initiated by AP 1802 and including AP 1804.

[0345] In one embodiment, frame 1822 can initiate the probe phase of multi-AP transmission. In another embodiment, AP 1802 can transmit frame 1822, which triggers AP 1804, for the probe phase of multi-AP transmission.

[0346] In an embodiment, frame 1822 may allow synchronization of the first transmission from AP 1804 and the third transmission from AP 1802 in phase 1820.

[0347] In an embodiment, frame 1822 may include a trigger frame. In an example, frame 1822 may include multiple AP trigger frames.

[0348] In an embodiment, AP 1802 may transmit frame 1826 to AP 1804, the frame indicating a fourth GI. For example, the fourth GI may include a duration selected from a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds.

[0349] In an embodiment, the fourth GI can be used for the second transmission from AP 1804 to STA 1808 in phase 1824 and the fourth transmission from AP 1802 to STA 1806 in phase 1824. In an example, the fourth transmission may include frames (such as...) Figure 16 Frame 1622 as described in [the document].

[0350] In this example, the GI duration required for the second transmission from AP 1804 and the fourth transmission from AP 1802 can differ in phase 1824. In this example, in phase 1824, frames are transmitted from AP 1804 (such as...). Figure 16 The GI duration required for the second transmission of frame 1624 described in the document can be longer than the transmission duration of a frame from AP 1802 (such as...). Figure 16 The fourth transmission in frame 1622 described in [the document] requires a longer GI duration. For example, the second transmission in phase 1824 may require a GI duration equal to 0.8 microseconds of “double GI duration”. For example, the fourth transmission in phase 1824 may require a GI duration longer than 1.6 microseconds of “double GI duration”.

[0351] In an embodiment, AP 1802 may determine the fourth GI based on the second GI. For example, the fourth GI may be at least equal to the second GI. In an embodiment, AP 1802 may select the fourth GI such that it satisfies both the GI duration required for the second transmission and the GI duration required for the fourth transmission.

[0352] In one embodiment, the duration of the fourth GI may be the same as the duration of the third GI. In another embodiment, the duration of the fourth GI may be different from the duration of the third GI.

[0353] In one embodiment, the second transmission in stage 1824 may use a fourth GI. In another embodiment, the fourth transmission in stage 1824 may also use a fourth GI. Therefore, STAs 1808 and 1806 can receive the second and fourth transmissions respectively without undergoing an ISI.

[0354] In an embodiment, the fourth transmission may include a fourth PPDU. The fourth PPDU may include a frame (such as...) Figure 16 (Frame 1622 described herein). The fourth GI can be used in the data field of the fourth PPDU. That is, the fourth GI can be used in the OFDM symbol of the data field of the fourth PPDU. In an embodiment, the fourth transmission can be scheduled during the second TXOP owned / acquired by AP 1802. In an embodiment, the fourth transmission can be part of the probe phase of a multi-AP transmission initiated by AP 1802 and including AP 1804.

[0355] In one embodiment, frame 1826 can initiate multi-AP transmission. In another embodiment, AP 1802 can transmit frame 1826, which triggers AP 1804, for multi-AP transmission.

[0356] In an embodiment, frame 1826 may allow synchronization of the second transmission from AP 1804 and the fourth transmission from AP 1802 in phase 1824.

[0357] In an embodiment, frame 1826 may contain a trigger frame. In an example, frame 1820 may contain a multi-AP trigger frame.

[0358] Figure 19 This is example 1900 illustrating another guard interval (GI) coordination procedure for multi-AP communication according to an embodiment. Example 1900 is provided for illustrative purposes only and is not limiting. Figure 19 As shown, Instance 1900 includes AP1902, AP1904, AP1906, STA1908, STA1910, and STA1912. In this instance, STA1908 may be associated with AP1902. In this instance, STA1910 may be associated with AP1904. In this instance, STA1912 may be associated with AP1906. AP1902, AP1904, AP1906, STA1908, STA1910, and / or STA1912 may contain a multilink device (MLD).

[0359] In the examples, AP 1902, 1904, and 1906 can be classified as belonging to the categories mentioned above. Figure 1The same ESS is described in the document. In this case, APs 1902, 1904, and 1906 can be connected via DS to support ESS features. In this example, APs 1902, 1904, and 1906 belong to different BSSs. In an embodiment, AP 1902 may belong to a first BSS, AP 1904 may belong to a second BSS, and AP 1906 may belong to a third BSS. In an embodiment, the second and third BSSs may contain overlapping basic service sets (OBSSs) relative to the first BSS.

[0360] In this embodiment, APs 1902, 1904, and 1906 can form a multi-AP group. It is assumed that in instance 1900, APs 1902, 1904, and 1906 can complete the multi-AP setup procedure before instance 1900 begins. Additionally, as part of the multi-AP group, APs 1902, 1904, and 1906 can be connected via backhaul. In this example, the backhaul can be a wireless backhaul.

[0361] Before instance 1900 begins, AP 1902, AP 1904, and AP 1906 can complete the multi-AP selection phase 1010 and the optional multi-AP data sharing phase 1012, such as... Figure 10 As described in the text.

[0362] like Figure 19 As shown, instance 1900 may include frame switching so that AP 1902 can coordinate with AP 1904 and AP 1906 to perform multi-AP transmission using a specific multi-AP transmission scheme with their associated STAs 1908, 1910 and 1912, respectively.

[0363] Assume that in Instance 1900, AP 1902, AP 1904, and AP 1906 all support GI coordination capabilities. In this instance, support for GI coordination capabilities allows AP 1902 to transmit a frame (such as frame 1914 described below) to request a first GI and a second GI from AP 1904. In this instance, support for GI coordination capabilities allows AP 1904 and AP 1906 to receive and process frames (such as frame 1914) and transmit frames (such as frames 1916 and 1918 described below) to share information related to the first and second GIs with AP 1902, respectively. In this instance, support for GI coordination capabilities allows AP 1902 to receive and process frames (such as frames 1916 and 1918) and transmit a frame (such as frame 1920 described below) to determine a third GI for multi-AP transmission based on the first and second GIs. In another instance, support for GI coordination capabilities allows AP 1902, AP 1904, and AP 1906 to use third GI transport frames (such as...). Figure 19Frames 1922, 1924, 1926, 1928, 1930, and 1932 described in the document.

[0364] In the embodiment, in instance 1900 ( Figure 19 Before the start of the process (not shown), APs 1902, 1904, and 1906 may exchange a first frame, a second frame, and a third frame to exchange capability information. In one embodiment, the first frame may contain capability information for AP 1902, including a first indication of AP 1902's support for GI coordination capabilities. In another embodiment, the second frame may contain capability information for AP 1904, including a second indication of AP 1904's support for GI coordination capabilities. In yet another embodiment, the third frame may contain capability information for AP 1906, including a third indication of AP 1906's support for GI coordination capabilities. In another embodiment, the first, second, and third frames may be exchanged during a multi-AP setup procedure or a multi-AP selection phase. In yet another embodiment, the first, second, and third frames may include management frames.

[0365] like Figure 19 As shown, Example 1900 may begin with AP 1902 transmitting frame 1914 to AP 1904 and AP 1906, requesting a first GI and a second GI from AP 1904 and AP 1906, respectively. In this embodiment, frame 1914 may request feedback from AP 1904 and AP 1906. In this embodiment, the first GI may be used for a first transmission from AP 1904 to STA 1910. In this embodiment, the second GI may be used for a second transmission from AP 1906 to STA 1912.

[0366] In one embodiment, frame 1914 may include a management frame, which in turn includes an action frame. In another embodiment, frame 1914 may include a control frame, which in turn includes a trigger frame.

[0367] In an embodiment, AP 1902 can request the first GI and the second GI by transmitting a separate frame similar to frame 1914 to AP 1904 and AP 1906.

[0368] In an embodiment, AP 1904 may transmit frame 1916 in response to frame 1914. In an embodiment, frame 1916 may contain feedback requested by frame 1914. In an embodiment, frame 1916 may indicate a first GI as requested in frame 1914.

[0369] In one embodiment, frame 1916 may include a management frame, which in turn includes an action frame. In another embodiment, frame 1916 may include a data frame, which in turn includes a QoS empty frame.

[0370] In an embodiment, AP 1904 may determine a first GI from a set of GIs. For example, the first GI may include a duration selected from a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds. In an example, AP 1906 may select the first GI based on the delay spread of the channel from AP 1904 to STA 1910, within which the first transmission will be transmitted. In an example, AP 1904 may determine that the first transmission requires a GI duration longer than the "double GI duration". For example, AP 1904 may determine that the first transmission must use a GI duration at least equal to the "quadruple GI duration" of 3.2 microseconds to avoid ISI at STA 1910.

[0371] In an embodiment, the first transmission may include a first PPDU. The first PPDU may include frame 1924. A first GI may be used for the data field of the first PPDU. In an embodiment, the first transmission may be scheduled during a TXOP owned / acquired by AP 1902. In an embodiment, the first transmission may be part of a multi-AP transmission initiated by AP 1902 and including AP 1904 and AP 1906.

[0372] In an embodiment, AP 1906 may transmit frame 1918 in response to frame 1914. In an embodiment, frame 1918 may contain feedback requested by frame 1914. In an embodiment, frame 1918 may indicate a second GI as requested in frame 1914.

[0373] In one embodiment, frame 1918 may include a management frame, which in turn includes an action frame. In another embodiment, frame 1918 may include a data frame, which in turn includes a QoS empty frame.

[0374] In an embodiment, AP 1906 can determine a second GI from a set of GIs. For example, the second GI may include a duration selected from a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds. In an example, AP 1906 may select the second GI based on the delay spread of the channel from AP 1906 to STA 1912, within which the second transmission will be transmitted. In an example, AP 1906 may determine that the second transmission requires a GI duration at least equal to the base GI duration. For example, AP 1906 may determine that the second GI must use a GI duration equal to at least 0.8 microseconds of the base GI duration.

[0375] In an embodiment, the second transmission may include a second PPDU. The second PPDU may include frame 1926. A second GI may be used for the data field of the second PPDU. In an embodiment, the second transmission may be scheduled during a TXOP owned / acquired by AP 1902. In an embodiment, the second transmission may be part of a multi-AP transmission initiated by AP 1902 and including AP 1904 and AP 1906.

[0376] In an embodiment, AP 1902 may transmit frame 1920 to AP 1904 and AP 1906, the frame indicating a third GI. For example, the third GI may include a duration selected from a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds.

[0377] In an embodiment, the third GI can be used for a first transmission from AP 1904 to STA 1910, a second transmission from AP 1906 to STA 1912, and an optional third transmission from AP 1902 to STA 1908. The third transmission may include an optional frame 1922.

[0378] In this example, the required GI durations for the first transmission from AP 1904 to STA 1910, the second transmission from AP 1906 to STA 1912, and the optional third transmission from AP 1902 to STA 1908 can differ. In this example, the channel from AP 1904 to STA 1910 may exhibit a longer delay spread than the channel from AP 1906 to STA 1912 and / or the channel from AP 1902 to STA 1908. Therefore, the required GI duration for the first transmission may be longer than the required GI duration for the second and / or third transmissions. For example, the second transmission might require a GI duration equal to the "basic GI duration" of 0.8 microseconds. Therefore, the first transmission might require a GI duration longer than the "double GI duration" of 1.6 microseconds.

[0379] In an embodiment, AP 1902 can determine the third GI based on the first GI and the second GI. For example, the third GI can be at least equal to the first GI or the second GI, whichever is longer. In an embodiment, AP 1902 can select the third GI to satisfy the GI duration required for the first transmission, the GI duration required for the second transmission, and the GI duration required for the third transmission. In an embodiment, the first transmission can use the third GI. In an embodiment, the second transmission can also use the third GI. In an embodiment, the third transmission can also use the third GI. Therefore, STAs 1910, 1912, and 1908 can receive the first transmission, the second transmission, and the third transmission, respectively, without experiencing ISI.

[0380] In an embodiment, an optional third transmission may include an optional third PPDU. The third PPDU may include frame 1922. A third GI may be used for the data field of the third PPDU. In an embodiment, the third transmission may be scheduled during a TXOP owned / acquired by AP 1902. In an embodiment, the third transmission may be part of a multi-AP transmission initiated by AP 1902 and including AP 1904 and AP1906.

[0381] In one embodiment, frame 1920 can initiate multi-AP transmission. In another embodiment, AP 1902 can transmit frame 1920, which triggers AP 1904 and AP 1906 for multi-AP transmission.

[0382] In an embodiment, frame 1920 allows synchronization of a first transmission from AP 1904, a second transmission from AP 1906, and an optional third transmission from AP 1902.

[0383] In this embodiment, frame 1920 may contain a trigger frame. In an example, frame 1920 may contain multiple AP trigger frames.

[0384] like Figure 19 As shown, STA 1908 can transmit optional frame 1928 to acknowledge receipt of optional frame 1922. In an embodiment, STA 1910 can transmit frame 1930 to acknowledge receipt of frame 1924. In an embodiment, STA 1912 can transmit frame 1932 to acknowledge receipt of frame 1926. In this example, frames 1928, 1930, and 1932 may contain BA frames.

[0385] In an embodiment, Figure 16 Frame 1610 described in the document Figure 17 Frame 1712 described in the document Figure 18 Frame 1812 and / or as described in Figure 19 Frames 1916 and 1918 described in the document can be management frames, such as action frames.

[0386] Figure 20 An example action frame 2000 is shown that can be used according to an embodiment. For example, action frame 2000 may be an embodiment of frame 1610, 1712, 1812, 1916, or 1918. In the example, action frame 2000 may contain common action frames.

[0387] In an embodiment, action frame 2000 may include information supporting GI coordination. In an embodiment, the information supporting GI coordination may include an indication of GI duration or an indication of GI type. In an embodiment, the information supporting GI coordination may include an indication of the PPDU field using the GI. The PPDU may be a UHR PPDU.

[0388] In this example, action frame 2000 can be transmitted from the first AP to the second AP. For example, the first AP could be... Figure 16 AP 1604 as described in Figure 17 AP 1704 as described in the document Figure 18 AP 1804 or as described in Figure 19 The embodiments of AP1904 and 1906 described herein. The second AP may be... Figure 16 AP 1602 as described in Figure 17 AP 1702 as described in the document Figure 18 AP 1802 or as described in Figure 19 The embodiments of AP 1902 described herein.

[0389] In an embodiment, action frame 2000 may indicate a GI for a transmission from the first AP to the STA. For example, the STA may be... Figure 16 The embodiment of STA 1608 described herein. In this example, action frame 2000 may include a GI coordination notification frame. The GI coordination notification frame may be a non-requested frame indicating a GI for transmission, such as frame 1610.

[0390] In an embodiment, action frame 2000 may include requesting the second AP to use GI for transmission from the first AP to the STA. For example, the STA may be... Figure 17 The embodiment of STA 1608 described herein. In this example, action frame 2000 may include a GI coordination request frame. The GI coordination request frame may be a non-request frame requesting a GI for transmission, such as frame 1610.

[0391] In an embodiment, action frame 2000 may include a response from the second AP to the first AP requesting the first AP to use GI for transmission from the first AP to the STA. For example, the STA may be... Figure 18 The STA 1708 or described in Figure 19 The embodiment of STA 1808 described herein. In this example, action frame 2000 may include a GI coordination response frame. The GI coordination response frame may be a requested frame, such as frame 1712 or 1812, which responds to a request frame requesting the first AP to use GI.

[0392] like Figure 16As shown, the action frame 2000 may include a frame control field, a duration field, one or more address fields, a sequence control field, an HT control field, a frame body, and an FCS field.

[0393] In this example, Address 1 field 2002 can indicate the receiver address (RA) of action frame 2000. RA can contain the address of the second AP. In this example, Address 2 field 2004 can indicate the transmitter address (TA). TA can contain the address of the first AP.

[0394] like Figure 17 As shown, the frame body of action frame 2000 may include action field 2006. In an embodiment, action field 2006 may contain information supporting GI coordination. In an embodiment, the information supporting GI coordination may indicate a GI used for transmission from the first AP to the STA. In an embodiment, action field 2006 may indicate a request to the second AP for the first AP to use a GI for transmission from the first AP to the STA. In an embodiment, action field 2006 may indicate a response to the second AP's request for the first AP to use a GI for transmission from the first AP to the STA. In an embodiment, action field 2006 may be a GI coordination action field.

[0395] In an embodiment, the action field 2006 may include a category subfield 2008, which indicates that the action frame 2000 is used for GI coordination.

[0396] In an embodiment, the action field 2006 may include the action detail field 2010.

[0397] In an embodiment, the action detail field 2010 may include a GI duration / type information subfield 2012, a GI field information subfield 2014, and an optional additional GI information subfield 2016.

[0398] In an embodiment, the GI duration / type information subfield 2012 may contain an indication of the GI duration or GI type. For example, the GI duration or GI type may include a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds.

[0399] In an embodiment, the GI field information subfield 2014 may include an indication of a PPDU field carrying the transmission from the first AP to the STA, wherein the GI indicated in the GI duration / type information subfield 2012 is used as an indication field for the PPDU. In an example, the field may include a Short Training Field (STF), a Long Training Field (LTF), or a data field. The PPDU may be a UHRPPDU.

[0400] In an embodiment, when action frame 2000 is used to indicate more than one GI from a first AP, an additional GI information subfield 2016 may exist. For example, when action frame 2000 is used as... Figure 18 In the embodiment of frame 1812 described herein, an additional GI information subfield 2016 may exist. In an embodiment, the additional GI information subfield 2016 may include a subfield of a second GI, wherein the subfield may be similar to the GI duration / type information subfield 2012 and the GI field information subfield 2014.

[0401] In an embodiment, Figure 19 Frame 1610 described in the document Figure 21 Frame 1712 described in the document Figure 21 Frame 1812 and described in Figure 18 Frames 1916 and 1918 described in the text can be data frames, such as QoS empty frames.

[0402] Figure 22 An example QoS empty frame 2100 is shown that can be used according to an embodiment. For example, QoS empty frame 2100 could be... Figure 22 Frame 1610 described in the document Figure 23 Frame 1712 described in the document Figure 23 Frame 1812 and described in Figure 24 Examples of frames 1916 and 1918 described herein.

[0403] In an embodiment, the QoS empty frame 2100 may include information supporting GI coordination. In an embodiment, the information supporting GI coordination may include an indication of the GI duration or an indication of the GI type. In an embodiment, the information supporting GI coordination may include an indication of the PPDU field using the GI. The PPDU may be a UHR PPDU.

[0404] In this example, QoS empty frame 2100 can be transmitted from the first AP to the second AP. For example, the first AP could be... Figure 24 AP 1604 as described in ​ AP 1704 as described in the document ​ AP 1804 or as described in ​ The embodiments of AP1904 and 1906 described herein. The second AP may be... ​ AP 1602 as described in ​ AP 1702 as described in the document ​ AP 1802 or as described in ​ The embodiments of AP 1902 described herein.

[0405] In an embodiment, QoS frame 2100 may indicate a GI for transmission from the first AP to the STA. For example, the STA may be... ​ The embodiment of STA 1608 described herein. In this example, the QoS empty frame 2100 may contain a GI coordination notification frame. The GI coordination notification frame may be a non-requested frame indicating a GI for transmission, such as frame 1610.

[0406] In an embodiment, the QoS empty frame 2100 may include a response from the second AP to a request from the second AP for the first AP to use GI for transmission from the first AP to the STA. For example, the STA may be... ​ STA 1708 as described in ​ The STA 1808 or described in ​ The embodiments of STA 1910 or 1912 described herein. In an example, the QoS empty frame 2100 may contain a GI coordination feedback frame. The GI coordination response frame may be a requested frame, such as frames 1712, 1812, 1916, or 1918, which is in response to a trigger frame requesting the first AP to use GI.

[0407] like ​ As shown, the QoS empty frame 2100 may include a frame control field, a duration field, one or more address fields, a QoS control field, an HT control field, and an FCS field.

[0408] In this example, address 1 field 2102 may contain the receiver address (RA) of the QoS empty frame 2100. The RA may contain the address of the current AP. In this example, address 2 field 2104 may indicate the transmitter address (TA). The TA may contain the address of the first AP.

[0409] like ​ As shown, the QoS empty frame 2100 may include an HT control field. In an example, the HT control field may include an A-control subfield. The A-control subfield may include a control list subfield, which includes one or more control subfields. In an embodiment, the control subfield 2106 of the control list subfield may include information supporting GI coordination. In an embodiment, the information supporting GI coordination may indicate a GI for transmission from the first AP to the STA. In an embodiment, control subfield 2106 may indicate feedback to the second AP requesting the first AP to use a GI for transmission from the first AP to the STA. In an embodiment, control subfield 2106 may be a GI coordination control subfield.

[0410] In an embodiment, the control subfield 2106 may include a control ID subfield 2108, which indicates that the QoS empty frame 2100 is used for GI coordination.

[0411] In an embodiment, the control subfield 2106 may include a control information subfield 2110, which may include a GI duration / type information subfield 2112, a GI field information subfield 2114, and an optional additional GI information subfield 2116.

[0412] In an embodiment, the GI duration / type information subfield 2112 may contain an indication of the GI duration or GI type. For example, the GI duration or GI type may include a base GI duration of 0.8 microseconds, a double GI duration of 1.6 microseconds, or a quadruple GI duration of 3.2 microseconds.

[0413] In an embodiment, the GI field information subfield 2114 may include an indication of a PPDU field carrying the transmission from the first AP to the STA, wherein the GI indicated in the GI duration / type information subfield 2112 is used as an indication field for the PPDU. In an example, the field may include a Short Training Field (STF), a Long Training Field (LTF), or a data field. The PPDU may be a UHRPPDU.

[0414] In an embodiment, when action frame 2100 is used to indicate more than one GI from a first AP, an additional GI information subfield 2116 may exist. For example, when action frame 2100 is used as... ​ In the embodiment of frame 1812 described herein, an additional GI information subfield 2116 may exist. In an embodiment, the additional GI information subfield 2116 may include a subfield of a second GI, wherein the subfield may be similar to the GI duration / type information subfield 2112 and the GI field information subfield 2114.

[0415] As those skilled in the art will understand based on the teachings herein, the embodiments described by the above examples can be readily extended to cases involving more than two STAs.

[0416] As those skilled in the art will understand based on the teachings herein, the embodiments described in the above examples can be readily extended to include cases with more than two access points (APs).

[0417] As will be understood by those skilled in the art based on the teachings herein, the embodiments described by the examples above can be readily extended to scenarios in which any of the APs or STAs may include an MLD, the MLD including at least one associated AP or associated STA.

[0418] As those skilled in the art will understand based on the teachings herein, the embodiments described in the examples above can be readily extended to include transmissions from STAs to APs. The transmission may be part of a multi-AP uplink transmission.

[0419] ​ An example process 2200 according to an embodiment is shown. Example process 2200 is provided for illustrative purposes only and is not intended to limit the embodiment. Process 2200 may be executed by a first AP.

[0420] like ​ As shown, process 2200 begins at step 2202, which includes receiving a first frame from a second AP by a first access point (AP), the first frame indicating a first guard interval (GI).

[0421] In step 2204, process 2200 includes transmitting a second frame from the first AP to the second AP, the second frame indicating the second GI.

[0422] In an embodiment, the second GI is based on the first GI.

[0423] In an embodiment, the first GI or the second GI is used for transmission from the second AP to the station (STA).

[0424] In an embodiment, the transmission includes a Physical Layer Protocol Data Unit (PPDU), and a first guard interval or a second guard interval is used for the data field or training field of the PPDU.

[0425] In this embodiment, the training field may include a short training field or a long training field.

[0426] In this embodiment, the transmission is scheduled during the first AP's transmission opportunity (TXOP).

[0427] In this embodiment, the transmission uses a second GI.

[0428] In this embodiment, the transmission is part of a multi-AP transmission initiated by the first AP and including the second AP.

[0429] In this embodiment, the transmission is part of a probe phase for multi-AP transmission.

[0430] In an embodiment, process 2200 may further include receiving a third frame from a second AP by a first AP, the third frame indicating a third GI.

[0431] In an embodiment, the transmission includes a PPDU, and the first GI is used for the data field of the PPDU and the third GI is used for the training field of the PPDU.

[0432] In this embodiment, the third frame is the same as the first frame.

[0433] In an embodiment, process 2200 may further include transmitting a fourth frame from the first AP to the second AP, the fourth frame requesting the first GI.

[0434] In this embodiment, the fourth frame requests the first frame.

[0435] In an embodiment, where the multi-AP transmission further includes a third AP, process 2200 may further include the first AP receiving a fifth frame from the third AP, the fifth frame indicating a fourth GI.

[0436] In an embodiment, the second GI is based on the first GI and the fourth GI.

[0437] In this embodiment, the first frame includes a management frame.

[0438] In an embodiment, the management frame includes a field or element indicating a first protection interval.

[0439] In this embodiment, the first frame contains a data frame.

[0440] In one embodiment, the data frame includes a field indicating the first GI.

[0441] In an embodiment, the second frame includes a management frame or a control frame.

[0442] In an embodiment, process 2200 may further include: receiving a first instruction from the first AP from the second AP regarding the second AP's support for the Coordinated GI capability; and transmitting a second instruction from the first AP to the second AP regarding the first AP's support for the Coordinated GI capability.

[0443] In this embodiment, the first AP and the second AP form a multi-AP group.

[0444] In this embodiment, the first AP belongs to a basic service set (BSS) and the second AP belongs to a first overlapping basic service set (OBSS) relative to the BSS.

[0445] In an embodiment, the first GI or the second GI is used for transmission from the STA to the second AP.

[0446] ​ An example process 2300 according to an embodiment is shown. Example process 2300 is provided for illustrative purposes only and is not intended to limit the embodiment. Process 2300 may be performed by a first AP.

[0447] like ​ As shown, process 2300 begins at step 2302, which includes transmitting a first frame from a first access point (AP) to a second AP, the first frame indicating a first guard interval (GI).

[0448] In step 2304, process 2300 includes receiving a second frame from a second AP by a first AP, the second frame indicating a second GI.

[0449] In an embodiment, the second GI is based on the first GI.

[0450] In an embodiment, the first GI or the second GI is used for transmission from the second AP to the station (STA).

[0451] In an embodiment, the transmission includes a Physical Layer Protocol Data Unit (PPDU), and a first GI or a second GI is used for the data field or training field of the PPDU.

[0452] In this embodiment, the training field may include a short training field or a long training field.

[0453] In this embodiment, the transmission is scheduled during a transmission opportunity (TXOP) of the second AP.

[0454] In an embodiment, process 2300 may further include the first AP transmitting a PPDU to the STA using a second GI.

[0455] In this embodiment, the transmission is initiated by the second AP and is part of a multi-AP transmission that includes the first AP.

[0456] In this embodiment, the transmission is part of a probe phase for multi-AP transmission.

[0457] In an embodiment, process 2300 may further include transmitting a third frame from the first AP to the second AP, the third frame indicating a third GI.

[0458] In this embodiment, the transmission includes a PPDU, and a first guard interval is used for the data field of the PPDU and a third guard interval is used for the training field of the PPDU.

[0459] In this embodiment, the third frame is the same as the first frame.

[0460] In an embodiment, process 2300 may further include receiving a fourth frame from a second AP by a first AP, the fourth frame requesting a first GI.

[0461] In this embodiment, the fourth frame requests the first frame.

[0462] In this embodiment, the first frame includes a management frame.

[0463] In an embodiment, the management frame includes a field or element that indicates the first GI.

[0464] In this embodiment, the first frame contains a data frame.

[0465] In one embodiment, the data frame includes a field indicating the first GI.

[0466] In an embodiment, the second frame includes a management frame or a control frame.

[0467] In an embodiment, process 2300 may further include: transmitting a first instruction from the first AP to the second AP regarding the first AP's support for the Coordinated GI capability; and receiving a second instruction from the first AP from the second AP regarding the second AP's support for the Coordinated GI capability.

[0468] In this embodiment, the first AP and the second AP form a multi-AP group.

[0469] In this embodiment, the first AP belongs to a basic service set (BSS) and the second AP belongs to a first overlapping basic service set (OBSS) relative to the BSS.

[0470] In an embodiment, process 2300 may further include receiving a fourth frame from the STA by the first AP, the fourth frame containing a third GI for transmission.

[0471] In this embodiment, the first GI is based on the third GI.

[0472] In an embodiment, the first GI or the second GI is used for transmission from the STA to the first AP.

[0473] In an embodiment, process 2300 may further include transmitting a third frame from the first AP to the STA, the third frame containing the second GI.

[0474] In one embodiment, the third frame includes a trigger frame for transmission.

[0475] In an embodiment, process 2300 may further include receiving a fourth frame from the STA by the first AP, the fourth frame containing a third GI for transmission.

[0476] In this embodiment, the first GI is based on the third GI.

[0477] As will be understood by those skilled in the art based on the teachings herein, embodiments of this disclosure are not limited to AP-to-AP communication. Rather, embodiments can be extended to AP-to-non-AP, non-AP-to-AP, and non-AP-to-non-AP communication. For illustration, ​ An example process 2400 according to an embodiment is shown. Example process 2400 can be executed by a first station, which may include an APSTA or a non-APSTA. ​ As shown, process 2400 includes steps 2402 and 2404.

[0478] Step 2402 includes receiving a first frame from the second station by the first station, the first frame indicating a first guard interval. The second station may include an AP STA or a non-AP STA. The first guard interval may be used for a first transmission from the second station to a third station. The third station may include an AP STA or a non-AP STA. In an embodiment, the third station is the same as the first station. The first transmission may be part of a multi-station transmission including the first and second stations.

[0479] Step 2404 includes transmitting a second frame from the first station to the second station, the second frame indicating a second guard interval. The second guard interval can be used for a first transmission from the second station to the third station. The second station can use the second guard interval for the first transmission from the second station to the third station.

Claims

1. A method comprising: A first frame is received by a first access point (AP) from a second AP, the first frame indicating a first guard interval for a transmission from the second AP to a station (STA), the transmission being scheduled during a transmission opportunity (TXOP) of the first AP; and A second frame is transmitted from the first AP to the second AP, the second frame indicating a second protection interval for the transmission, the second protection interval being based on the first protection interval.

2. A method comprising: The first access point (AP) receives a first frame from the second AP, the first frame indicating a first protection interval; and The first AP transmits a second frame to the second AP, and the second frame indicates the second protection interval.

3. The method according to claim 2, wherein the second protection interval is based on the first protection interval.

4. The method according to any one of claims 2 to 3, wherein the first protection interval or the second protection interval is used for transmission from the second AP to the station STA.

5. The method of claim 4, wherein the transmission includes a Physical Layer Protocol Data Unit (PPDU), and wherein the first guard interval or the second guard interval is used for the data field or training field of the PPDU.

6. The method according to any one of claims 4 to 5, wherein the transmission is scheduled during a transmission opportunity (TXOP) of the first AP.

7. The method according to any one of claims 4 to 6, wherein the transmission uses the second guard interval.

8. The method according to any one of claims 4 to 7, wherein the transmission is a part of a multi-AP transmission initiated by the first AP and including the second AP.

9. The method according to any one of claims 4 to 7, wherein the transmission is part of a probe phase for multi-AP transmission.

10. The method according to any one of claims 4 to 9, further comprising: The first AP receives a third frame from the second AP, the third frame indicating a third protection interval.

11. The method of claim 10, wherein the transmission includes a Physical Layer Protocol Data Unit (PPDU), and wherein the first guard interval is used for the data field of the PPDU, and the third guard interval is used for the training field of the PPDU.

12. The method according to any one of claims 2 to 11, further comprising: The first AP transmits a fourth frame to the second AP, and the fourth frame requests the first protection interval.

13. The method according to any one of claims 8 to 12, wherein the multi-AP transmission further comprises a third AP, and the method further comprises: The first AP receives a fifth frame from the third AP, the fifth frame indicating a fourth protection interval.

14. The method of claim 13, wherein the second protection interval is based on the first protection interval and the fourth protection interval.

15. A method comprising: A first frame is received by the first access point (AP) from the second AP, the first frame indicating a first protection interval for transmission from the second AP to the station (STA); and A second frame is transmitted from the first AP to the second AP. The second frame indicates a second protection interval for multi-AP transmission that includes the transmission. The second protection interval is based on the first protection interval.

16. A method comprising: A first frame is transmitted from a first access point (AP) to a second AP. The first frame indicates a first protection interval for a transmission from the second AP to a station (STA). The transmission is scheduled during a transmission opportunity (TXOP) of the first AP. The first AP receives a second frame from the second AP, the second frame indicating a second protection interval for the transmission, the second protection interval being based on the first protection interval; as well as The transmission is transmitted from the first AP to the STA using the second guard interval.

17. A method comprising: A first frame is transmitted from the first access point (AP) to the second AP, the first frame indicating a first protection interval; and The first AP receives a second frame from the second AP, the second frame indicating a second protection interval.

18. The method of claim 17, wherein the second protection interval is based on the first protection interval.

19. The method according to any one of claims 17 to 18, further comprising receiving a fourth frame from the STA by the first AP, the fourth frame comprising a third guard interval.

20. The method of claim 19, wherein the first protection interval is based on the third protection interval.

21. The method according to any one of claims 17 to 18, wherein the first protection interval or the second protection interval is used for transmission from the station STA to the first AP.

22. The method of claim 21, further comprising transmitting a third frame from the first AP to the STA, the third frame including the second guard interval.

23. The method of claim 22, wherein the third frame comprises a trigger frame for the transmission.

24. The method according to any one of claims 21 to 23, further comprising receiving a fourth frame from the STA by the first AP, the fourth frame comprising a third guard interval for the transmission.

25. The method of claim 24, wherein the first protection interval is based on the third protection interval.

26. A method comprising: A first frame is transmitted from the first access point (AP) to the second AP, the first frame indicating a first protection interval for transmission from the first AP to the station (STA); The first AP receives a second frame from the second AP, the second frame indicating a second protection interval for multi-AP transmission including the transmission, the second protection interval being based on the first protection interval; as well as The transmission in the multi-AP transmission is transmitted from the first AP to the STA using the second guard interval.

27. An apparatus comprising: One or more processors; and A memory that stores instructions that, when executed by the one or more processors, cause the apparatus to perform the method according to any one of claims 1 to 26.

28. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to perform the method according to any one of claims 1 to 26.

Images