Resource unit configuration control for coordinated spatial multiplexing

Abstract

A first access point (AP) receives a first frame from a second AP, the first frame including a resource unit (RU) request for a multi-AP coordinated transmission. The first AP transmits a second frame to the second AP, the second frame comprising: a first resource unit (RU) for the second AP to use for the multi-AP coordinated transmission; and a first parameter indicating whether a smaller number of subcarriers than the total number of subcarriers of the first RU is allowed to be used for transmission during the multi-AP coordinated transmission.

Description

Cross-references to related applications

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 531,034, filed August 7, 2023, which is incorporated herein by reference in its entirety. Attached Figure Description

[0002] Examples of several embodiments of the various embodiments of this 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 may be implemented is shown.

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

[0005] Figure 3 An example multi-AP network is shown.

[0006] Figure 4 Enhanced Distributed Channel Access (EDCA) and Coordinated Orthogonal Frequency Division Multiple Access (COFDMA) are shown.

[0007] Figure 5 This shows an example network containing a set of coordinated APs.

[0008] Figure 6 Example multi-AP operating procedures are shown.

[0009] Figure 7 This illustrates an example of a multi-AP probe phase.

[0010] Figure 8 This illustrates an example of a multi-AP downlink data transmission phase.

[0011] Figure 9 This illustrates an example of a multi-AP uplink data transmission phase.

[0012] Figure 10 This is an example illustrating an existing measurement procedure.

[0013] Figure 11 This shows the format of the measurement report field of the measurement report element when carrying beacon reports according to the IEEE 802.11 standard.

[0014] Figure 12 It shows the use Figure 10 The example shown is a multi-AP coordinated transmission procedure for the measurement program.

[0015] Figure 13 An example allocation of a non-distributed resource unit is shown.

[0016] Figure 14 An example allocation of a distributed resource unit is shown.

[0017] Figure 15 It is shown in Figure 12 Examples of potential problems in multi-AP coordinated transmission procedures are shown in the figure.

[0018] Figure 16 This is an example illustrating a multi-AP coordinated transmission procedure according to an embodiment.

[0019] Figure 17 This is an example illustrating a multi-AP coordinated transmission procedure according to another embodiment.

[0020] Figure 18 This is an example illustrating a multi-AP coordinated transmission procedure according to another embodiment.

[0021] Figure 19 This is an example illustrating a multi-AP coordinated transmission procedure according to another embodiment.

[0022] Figure 20 This is an example illustrating a multi-AP coordinated transmission procedure according to another embodiment.

[0023] Figure 21 An example process according to an embodiment is shown.

[0024] Figure 22 An example process according to an embodiment is shown.

[0025] Figure 23 An example process according to an embodiment is shown. Detailed Implementation

[0026] In this disclosure, various embodiments are presented as examples of how the disclosed techniques can be implemented and / or how the disclosed techniques can be practiced in environments and scenarios. It will be apparent to those skilled in the art that various changes in form and detail can be made therein without departing from the scope. Alternative embodiments will become apparent to those skilled in the art upon reading this specification. Embodiments of the invention are not limited to any of the exemplary embodiments described. Embodiments of this disclosure will be described with reference to the accompanying drawings. Limitations, features, and / or elements from the disclosed exemplary embodiments can be combined to create further embodiments within the scope of this disclosure. Any diagrams highlighting functionality and advantages are given for illustrative purposes only. The disclosed architecture is flexible and configurable enough that it can be utilized in ways other than those shown. For example, actions listed in any flowchart can be reordered or used only optionally in certain embodiments.

[0027] 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, traffic characteristics, combinations thereof, etc. Various example embodiments can be applied when one or more criteria are met. Therefore, it is possible to implement example embodiments that selectively implement the disclosed protocols.

[0028] In this disclosure, “a” and “an”, and similar phrases, will be interpreted as “at least one” and “one or more”. Similarly, any term ending with the suffix “(s)” will be interpreted as “at least one” and “one or more”. In this disclosure, the term “may” is interpreted as “may, for example.” In other words, the term “may” indicates that the phrase following the term “may” is an example of one 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 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.

[0029] 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 example 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 example of one of a variety of suitable possibilities that may or may not be used in one or more different embodiments. The phrase “depends on” (or equivalently “at least depends on”) indicates that the phrase following the phrase “depends on” is an example of one of a variety of suitable possibilities that may or may not be used in one or more different embodiments. The phrase “adopts / uses” (or equivalently “at least adopts / uses”) indicates that the phrase following the phrase “adopts / uses” is an example of one of a variety of suitable possibilities that may or may not be used in one or more different embodiments.

[0030] The term "configuration" can refer to the capabilities of a device, whether the device is in an operational or non-operational state. "Configuration" 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 message generated in the device" can mean that the control message has 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.

[0031] In this disclosure, a parameter (or equivalently referred to as a field or information element: IE) may include one or more information objects, and an information object may include one or more other objects. For example, if parameter (IE)N includes parameter (IE)M, and parameter (IE)M includes parameter (IE)K, and parameter (IE)K includes parameter (information element)J, then, for example, N includes K, and N includes J. In the example embodiment, when one or more messages / frames include 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.

[0032] By using the word "may" or parentheses, many of the presented features are described as optional. 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.

[0033] Many of the 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 in 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 frequently programmed using hardware description languages ​​(HDLs), such as VHSIC Hardware Description Language (VHDL) or Verilog. These languages ​​configure connections between relatively few internal hardware modules on a programmable device. The techniques mentioned are often used in combination to achieve the result of functional modules.

[0034] Figure 1 An example wireless communication network in which embodiments of the present disclosure may be implemented is shown.

[0035] like Figure 1 As shown, the example wireless communication network 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.

[0036] BSS 110-1 and 110-2 each contain a set of access points (APs or AP STAs) and at least one station (STA or non-AP STA). For example, BSS 110-1 contains AP 104-1 and STA 106-1, and BSS 110-2 contains AP 104-2 and STAs 106-2 and 106-3. The APs and at least one STA in the BSS perform association procedures to communicate with each other.

[0037] 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, APs 104-1 and 104-2 are connected via DS 130 and can have the same Service Set Identifier (SSID).

[0038] 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.

[0039] Figure 1 The example wireless communication network shown may further comprise one or more self-organizing networks or independent BSSs (IBSSs). A self-organizing network or IBSS is a network of multiple STAs contained 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).

[0040] 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 106-8 can be configured to form a second IBSS 112-2. Since an IBSS does not contain an AP, it does not contain 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.

[0041] A STA, serving as the intended 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.

[0042] A Physical Layer (PHY) Protocol Data Unit (PPDU) can be a composite structure containing a PHY preamble and a payload in the form of a PLCP Service Data Unit (PSDU). For example, a PSDU may contain a PHY Convergence Protocol (PLCP) preamble and 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 can contain both a traditional part (or "traditional preamble") and a non-traditional part (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 part of the preamble are based on the specific IEEE 802.11 protocol to be used for transmitting the payload.

[0043] A frequency band can contain 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 520 MHz.

[0044] Figure 2 This is a block diagram illustrating example implementations of the 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 memory 230 / 280 and / or transceiver 240 / 290.

[0045] 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). Processors 220 / 270 may include one or more processors and / or one or more controllers. For example, one or more processors and / or one or more controllers may include, for example, a general-purpose processor, a digital signal processor (DSP), a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), logic circuitry, or a chipset.

[0046] Memory 230 / 280 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage units. Memory 230 / 280 may include one or more non-transitory computer-readable media. Memory 230 / 280 may store computer program instructions or code that can be executed by processor 220 / 270 to perform one or more of the operations / embodiments discussed in this application. Memory 230 / 280 may be implemented (or located) within processor 220 / 270 or external to processor 220 / 270. Memory 230 / 280 may be operatively connected to processor 220 / 270 in various ways known in the art.

[0047] 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). In embodiments, STA 210 and / or AP 260 can be multi-link devices (MLDs), which are devices capable of operating on multiple links defined by the IEEE 802.11 standard. Therefore, STA 210 and / or AP 260 can each implement multiple PHY layers. One or more of transceivers 240 / 290 can be used to implement multiple PHY layers.

[0048] Figure 3 An example multi-AP network 300 is shown. The example multi-AP network 300 can be a multi-AP network according to the Wi-Fi Alliance standard specifications for multi-AP networks. For example... Figure 3As shown, the multi-AP network 300 may include a multi-AP controller 302 and multiple multi-AP groups (or multi-AP sets) 304, 306 and 308.

[0049] The multi-AP controller 302 can be a logical entity that implements the logic for controlling the APs in the multi-AP network 300. The multi-AP controller 302 can receive capability information and measurement results from the APs, and can trigger AP control commands and operations on the APs. The multi-AP controller 302 can also provide mounting functionality to mount and provide APs to the multi-AP network 300.

[0050] Multiple AP groups 304, 306, and 308 may each contain multiple APs. APs in a multiple AP group are within each other's communication range and can coordinate transmissions by the APs and / or from their associated STAs. Coordinated transmissions can involve all APs or a subset of APs in the multiple AP group. A multiple AP group may also be referred to as an AP candidate set because APs in the multiple AP group are considered candidates for coordinated transmissions initiated by the APs. 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 the STA associated with the AP, the primary channel refers to the AP's primary channel, which is advertised via the AP's beacon frames.

[0051] In one approach, a multi-AP group can be established by a coordinating AP during the multi-AP setup phase prior to any multi-AP coordination. APs in the multi-AP group other than the coordinating AP can be referred to as coordinating APs. The coordinating AP can establish one or more multi-AP groups. A coordinating AP can also be a member of multiple multi-AP groups. The coordinating AP of one multi-AP group can be the coordinating AP of another multi-AP group, and vice versa. In another approach, a multi-AP group can be manually established by a network administrator by configuring APs as part of the multi-AP group. In yet another approach, multi-AP groups can be established by APs in a distributed manner without a central controller. In this case, APs can advertise their multi-AP capabilities in beacons or other management frames (e.g., common action frames). Other APs that receive frames with multi-AP capability information can perform multi-AP setup with the APs that advertised their multi-AP capabilities.

[0052] 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 done by the AP controller 302 or by the APs in 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.

[0053] In one approach, APs in a multi-AP group can perform coordinated transmissions together. One aspect of coordination may involve coordinating to perform coordinated transmissions within the multi-AP group. As used herein, coordinated transmission, also known as multi-AP transmission, is a transmission event in which multiple APs (in a multi-AP group or network) transmit in a coordinated manner over a period of time. Coordinated transmission can involve simultaneous transmissions by multiple APs in a multi-AP group. The time period for simultaneous AP transmissions can be a continuous period. Multi-AP transmissions can use different transmission techniques, such as Coordinated OFDMA (COFDMA), Coordinated Spatial Multiplexing (CSR), Joint Transmit or Receive (JT / JR), Coordinated Beamforming (CBF), and Coordinated Time Division Multiple Access (CTDMA), or a combination of two or more of the foregoing techniques.

[0054] Multi-AP transmission can be enabled by an AP controller and / or the master AP of a multi-AP group. In one approach, the AP controller and / or the master AP can control time and / or frequency sharing within a transmission opportunity (TXOP). For example, when one AP in a multi-AP group (e.g., the master AP) acquires a TXOP, the AP controller and / or the master 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 master AP in the multi-AP group. The master 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.

[0055] Different multi-AP transmission schemes can be applied to different privacy-preserving use cases, including whether the transmitted data can be shared with other BSSs in the multi-AP group. For example, some multi-AP transmission schemes, such as CSR, CDTMA, Coordinated Frequency Division Multiple Access (CFDMA), COFDMA, and CBF, allow the master AP to coordinate slave APs by sharing control information among APs, without needing to share user data among APs. Control information may include BSS information for the AP, link quality information of the channel between each AP and its associated STA, and information about the resources to be used for multiplexing in the power, time, frequency, or special domains of multi-AP transmission. The control information exchanged between the master and slave APs can be used for interference avoidance or zeroing to avoid or zero co-channel interference introduced into adjacent BSSs in a multi-AP network. Interference avoidance or zeroing requires that data transmission between APs and STAs is limited to the same BSS. In other words, each AP transmits or receives data frames from its associated STA, while each STA receives or transmits data frames from its associated AP.

[0056] In contrast, other multi-AP transmission schemes allow the master AP to coordinate slave APs by sharing both control information and user data among the APs in the multi-AP group. Control information can include BSS information associated with the AP and link quality information of the channel between each AP and its associated STA. By exchanging user data on the backhaul, the master and slave APs can jointly perform data transmission to achieve spatial diversity, for example, using distributed MIMO, such as joint transmission (JT) for downlink transmission and joint reception (JR) for uplink transmission. Data transmission between APs and STAs can include transmissions within the same BSS and / or across different BSSs. In other words, an AP can transmit data frames to its associated STA and STAs associated with other APs participating in the multi-AP transmission, or receive data frames from said STAs. Similarly, a STA can transmit data frames to or receive data frames from multiple APs.

[0057] Different multi-AP transmission schemes are suitable for different use cases regarding the signal reception level at the STA or APs within a multi-AP group. For example, CBF and JT / JR require each STA participating in the multi-AP transmission to be located within the common signal coverage area of ​​the participating APs. Typically, CBF may be appropriate when the receiving STA suffers potential interference from other APs in the multi-AP group. By using channel-related information such as Channel State Information (CSI), Channel Quality Indication (CQI), or Compressed Beamforming (BF) feedback exchanged between APs, the APs can precode the signal to be transmitted to form a beam that increases the power toward the target STA while reducing the power of STAs associated with neighboring APs that are interfering with the signal. The JT / JR use case may require sufficient received signal power for the JT at the receiving STA and sufficient received signal power for the JR at the receiving AP. In contrast, CSR can perform multi-AP transmission in an interference-coordinated manner. The received signal power at the STA associated with the AP transmitting data may need to be much higher than the received interference power.

[0058] Different multi-AP transmission schemes may require different levels of synchronization and can operate with or without backhaul between the master and slave APs in a multi-AP group. For example, CSR may require PPD-level synchronization, while CBF may require symbol-level synchronization. On the other hand, JT / JR may require tight time / frequency / phase-level synchronization as well as backhaul for data sharing between APs in a multi-AP group.

[0059] Regarding coordination between master and slave APs in a multi-AP group, different multi-AP transmission schemes can have varying degrees of complexity. For example, JT / JR may require extremely high complexity because CSI and user data are shared between APs. CBF may require moderate complexity due to CSI sharing. CFDMA, COFDMA, and CTDMA may require moderate or relatively low complexity because CSI and time / frequency resources need to be shared between APs. CSR may require low complexity because the amount of information related to spatial multiplexing and services that needs to be exchanged between APs may be relatively low.

[0060] Multi-AP groups can employ static multi-AP operation, which includes a static multi-AP transmission scheme. Multi-AP networks can also be dynamic for various reasons. For example, STAs can join or leave the multi-AP network, STAs can switch to power-saving mode, or APs or STAs can change their locations. Such changes may alter the underlying conditions for selecting the multi-AP transmission scheme and may result in the loss of certain requirements for the multi-AP transmission scheme (e.g., synchronization, backhaul, coordination, etc.). This can lead to poor transmission quality in the multi-AP network.

[0061] In COFDMA, a primary AP can share a portion of its TXOP with multiple APs by allocating appropriate frequency resources (e.g., channels / subchannels) from the available frequency resources to each of the multiple APs. Figure 4 The diagram illustrates COFDMA as a multi-AP channel access method, compared to Enhanced Distributed Channel Access (EDCA). For example... Figure 4 As shown, in EDCA, channel access by multiple APs (e.g., AP1, AP2) can occur within consecutive time periods (e.g., TXOPs). During a given channel access period, the channel (e.g., 80 MHz) can be entirely used by a single AP. Conversely, in COFDMA, access by multiple APs (multi-AP channel access) can occur on orthogonal frequency resources within the same time period (e.g., the same TXOP or the same portion of a TXOP). For example, as... Figure 4 As shown, an 80 MHz channel can be divided into four non-overlapping 20 MHz channels, each assigned to a corresponding AP among multiple APs. Multiple APs can transmit simultaneously in a coordinated manner within the same time period to achieve multi-AP transmission. In multi-AP transmission, each AP can send PPDUs to one or more STAs.

[0062] Figure 5 Example network 500 containing a set of coordinating APs is shown. Figure 5As shown, a coordinated AP set can contain two APs—AP 502-1 and AP 502-2. The coordinated AP set can be a subset of the established multi-AP group. At least one STA can be associated with each AP in AP 502-1 and 502-2. For example, STA 504-1 can be associated with AP 502-1, and STA 504-2 can be associated with AP 502-2.

[0063] AP 502-1 and 502-2 can be classified under the above-mentioned... Figure 1 The same ESS described herein. In such cases, APs 502-1 and 502-2 can be connected via DS to support ESS features. Additionally, as part of a coordinated AP set, APs 502-1 and 502-2 can be connected via backhaul. Backhaul is used to quickly share information between APs to support coordinated transmission. 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, because wireless backhaul relies on the AP's main radio to transmit information, the AP cannot transmit or receive any data when using wireless backhaul.

[0064] Typically, one of APs 502-1 and 502-2 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 with only a subset of the coordination set. The role of the primary AP can change over time. For example, the primary AP role can be assigned to a specific AP for a period of time. Similarly, the secondary AP role can be dynamically selected by the primary AP or pre-assigned for a period of time.

[0065] 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 5 In this configuration, if AP 502-1 supports JT and CSR, while AP 502-2 supports CSR and CBF, both APs can execute CSR alone 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.

[0066] CSR is something that can be... Figure 5The APs 501-1 and 502-2 shown support one type of multi-AP coordination. Spatial multiplexing using CSR can be more stable than non-AP coordinated spatial multiplexing schemes such as SR based on OBSS PD and SR based on PSR. For example, in example network 500, APs 502-1 and 502-2 can perform joint probe operations to measure path loss (PL) on paths in network 500. For example, the joint probe operation can achieve the measurement of PL508 for the path between APs 502-1 and 502-2, path loss510 for the path between AP 502-1 and STA 504-2, and path loss512 for the path between AP 502-2 and STA 504-1. The measured path loss information can then be shared between APs 502-1 and 502-2 (e.g., using backhaul) to allow simultaneous transmission to their associated STAs 504-1 and 504-2 via APs 502-1 and 502-2, respectively. Specifically, one of APs 502-1 and 502-2 acquires a TXOP to become the primary AP. The primary AP can then send CSR announcement frames to the other APs. In an implementation, the primary AP can perform a polling operation before sending the CSR announcement frames to poll the slave APs regarding packet transmission availability. If at least one slave AP responds indicating packet availability, the primary AP can continue sending CSR announcement frames. In the CSR announcement, the primary AP can limit the transmission power of the slave APs to protect its own transmission to its target STA. Slave APs can similarly protect their own transmission to their target STA by selecting a modulation scheme that provides a sufficiently high signal-to-interference ratio (SIR) tolerance to support interference caused by the primary AP's transmission to its target STA.

[0067] Figure 6 Example 600 illustrates a multi-AP operating procedure. In example 600, a multi-AP operating procedure is illustrated with respect to a multi-AP network comprising APs 602 and 604, and STAs 606 and 608. In the example, APs 602 and 604 can form a multi-AP group. AP 602 can be the master AP of the multi-AP group, and AP 604 can be a slave AP. For example, AP 602 can obtain a TXOP, thereby becoming the master AP of the multi-AP group. Alternatively, AP 602 can be designated as the master AP by a multi-AP controller.

[0068] like Figure 6 As shown, the multi-AP operation procedure can include a series of time periods, each of which can contain multiple frame exchanges within the multi-AP network. Specifically, the multi-AP operation procedure can include a multi-AP selection phase 610, a multi-AP data sharing phase 612, a multi-AP detection phase 614, and a multi-AP data transmission phase 616.

[0069] 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 the 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 the multi-AP transmission.

[0070] The multi-AP selection phase 610 may include procedures for requesting, selecting, or specifying slave APs in a multi-AP group by the master AP. For example... Figure 6 As shown, the multi-AP selection phase may include the transmission of frame 618 from AP 602 and frame 620 from AP 604. AP 602 may transmit frame 618 to request information about the buffer status of AP 604. In response, AP 604 may transmit frame 620 to inform AP 602 of its buffer status, the buffer status of its associated STAs, and / or whether it intends to join the multi-AP operation. The multi-AP selection phase 610 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).

[0071] Multi-AP data sharing phase 612 may include procedures for sharing data frames that will be transmitted by the AP to the associated STA between the master AP and selected slave APs via direct connections between APs. For some multi-AP data transmission schemes, phase 612 may be optional. For example, JT / JR may require phase 612 because data frames can be exchanged between APs before or after multi-AP data transmission phase 616.

[0072] The multi-AP data sharing phase 612 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 612 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 6 As shown, in stage 612, AP 602 can transmit frame 622, which can be received by AP 604. Frame 622 may contain an MPDU that AP 602 wishes to transmit to an associated STA using multi-AP operation. Similarly, AP 604 can transmit frame 624, which can be received by AP 602. Frame 624 may contain an MPDU that AP 604 wishes to transmit to an associated STA using multi-AP operation.

[0073] Multi-AP probing phase 614 may include procedures for multi-AP channel probing, including channel estimation and feedback from the master AP, candidate slave APs, and associated STAs. For some multi-AP transmission schemes such as COFDMA, CDTMA, and CSR, phase 614 may be optional. For example, phase 614 may be performed by the master AP to assist in resource unit allocation when coordinating COFDMA transmissions.

[0074] Multi-AP data transmission phase 616 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 616 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.

[0075] The order of stages 610, 612, 614, and 616 may differ. Figure 6 The order shown is different. For example, in COFDMA, stage 616 may occur immediately after stage 610, while in JT / JR, stage 612 may occur after stage 610. Furthermore, as mentioned above, some stages may be optional and may or may not be present. For example, stage 614 may not be necessary for COFDMA, but it may be necessary for JT / JR.

[0076] Figure 7 Example 700 of a multi-AP detection phase is shown. Multi-AP detection phase 700 can be an example of multi-AP detection phase 614. For example... Figure 7 As shown, Example 700 may include a master AP 702 and a slave AP 704 in a multi-AP group. Example 700 may also include a STA 706 associated with AP 702 and a STA 708 associated with AP 704.

[0077] like Figure 7 As shown, the multi-AP detection phase 700 may include frame switching to allow AP 702 (the master AP) to acquire channel state information (CSI) of the channels in the multi-AP group. In an implementation, phase 700 may include a first sub-phase 710 and a second sub-phase 712.

[0078] During the first sub-phase 710, the AP can initiate channel probes, and the STA can estimate channel state information (CSI). For example, AP 702 can transmit frame 714 to AP 704 (from the AP) to trigger a multi-AP probe. Frame 714 may include a multi-AP trigger frame. Subsequently, APs 702 and 704 can transmit announcement frames 716-1 and 716-2 to their respective associated STAs 706 and 708 to announce the transmission of the probe frames. Frames 716-1 and 716-2 may include multi-AP null packet announcement (NDPA) frames. Frames 716-1 and 716-2 can be transmitted simultaneously. Next, APs 702 and 704 can transmit frames 718-1 and 718-2 to STAs 706 and 708, respectively. Frames 718-1 and 718-2 may include multi-AP null packet (NDP) frames. STAs 706 and 708 receive frames 718-1 and 718-2 respectively, and perform channel estimation for the channels from AP 702 to STA 706 and from AP 704 to STA 708 respectively.

[0079] During the second sub-phase 712, the AP can initiate a procedure for the STAs to feed back their channel estimates to the AP. For example, AP 702 can transmit frame 720 to trigger STAs 706 and 708 to transmit their channel estimates to APs 702 and 704, respectively. Frame 720 may include a multi-AP trigger frame. In response, STAs 706 and 708 can transmit frames 722 and 724, respectively, containing feedback on the channel estimates, to APs 702 and 704. Frames 722 and 724 may include NDP feedback frames. The feedback on the channel estimates may include NDP feedback, CSI-related information, beamforming report (BFR), or channel quality indication (CQI) report.

[0080] Figure 8 Example 800 of a multi-AP downlink data transmission phase is shown. Multi-AP downlink data transmission phase 800 can be an example of multi-AP data transmission phase 616. (e.g.) Figure 8 As shown, Example 800 may include a master AP 802 and a slave AP 804 in a multi-AP group. Example 800 may also include a STA 806 associated with AP 802 and a STA 808 associated with AP 804.

[0081] like Figure 8As shown, the multi-AP downlink data transmission phase 800 may include frame switching so that the master AP 802 can coordinate with the slave AP 804 to execute specific multi-AP transmission schemes with their respective associated STAs 806 and 808. The multi-AP transmission scheme may include COFDMA, CTDMA, CSR, CBF, JT / JR, or a combination of two or more of the aforementioned schemes.

[0082] like Figure 8 As shown, the primary AP 802 can initiate phase 800 by transmitting frame 810 to AP 804. Frame 810 may contain information related to AP 804 (e.g., an identifier for AP 804), 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 804 to acknowledge frame 810. Frame 810 may include a control frame. For example, frame 810 may include a multi-AP trigger frame.

[0083] Frame 810 can be received from AP 804, and synchronization information can be used to synchronize with the master AP 802. Subsequently, APs 802 and 804 can perform data transmissions to their associated STAs 806 and 808, respectively. Specifically, AP 802 can transmit data frame 812 to its associated STA 806, and AP 804 can transmit data frame 814 to its associated STA 808. Depending on the multi-AP transmission scheme used, APs 802 and 804 can transmit frames 812 and 814 to STAs in different BSSs. For example, when the multi-AP transmission scheme is JT / JR, AP 802 can also transmit frame 812 to STA 808 associated with AP 804, and AP 804 can also transmit frame 814 to STA 808 associated with AP 804. The resources used for transmitting and receiving frames 812 and 814 can depend on the specific multi-AP transmission scheme employed.

[0084] STAs 806 and 808 can acknowledge frames 812 and 814, respectively. For example, STA 806 can transmit frame 816 to AP 802, and STA 808 can transmit frame 818 to AP 804. Frames 816 and 818 may include block acknowledgment (BA) frames. STAs 806 and 808 can also transmit frames 816 and 818 to APs in different BSSs when required by the multi-AP transmission scheme used. For example, when the multi-AP transmission scheme is JT / JR, STA 806 can also transmit frame 816 to AP 804, and STA 808 can also transmit frame 818 to AP 802. The resources used for transmitting and receiving frames 816 and 818 may depend on the specific multi-AP transmission scheme employed.

[0085] Figure 9 Example 900 of a multi-AP uplink data transmission phase is shown. Multi-AP uplink data transmission phase 900 can be an example of multi-AP data transmission phase 616. (e.g.) Figure 9 As shown, Example 900 may include a master AP 902 and a slave AP 904 in a multi-AP group. Example 900 may also include STAs 906 and 908 associated with AP 902, and STA 910 associated with AP 904.

[0086] like Figure 9 As shown, the multi-AP uplink data transmission phase 900 may include frame switching so that the master AP 902 can coordinate with the slave AP 904 to execute a specific multi-AP transmission scheme together with STAs 906, 908, and 910 / 910. The multi-AP transmission scheme may include COFDMA, CTDMA, CSR, CBF, JT / JR, or a combination of two or more of the aforementioned schemes.

[0087] like Figure 9 As shown, the master AP 902 can initiate phase 900 by transmitting frame 912 to AP 904. Frame 912 may contain information related to AP 904 (e.g., an identifier for AP 904), synchronization information, information related to the specific multi-AP transmission scheme to be used, and / or information related to the RU used by AP 904 to acknowledge frame 912. Frame 912 may include a control frame. For example, frame 912 may include a multi-AP trigger frame.

[0088] AP 904 can receive frame 912 and can use synchronization information to synchronize with the master AP 902. Subsequently, APs 902 and 904 can use trigger frames to request uplink data transmission from their associated STAs 906, 908, and 910. Specifically, AP 902 can transmit trigger frame 914 to its associated STAs 906 and 908, and AP 904 can transmit trigger frame 916 to its associated STA 910. Depending on the multi-AP transmission scheme used, APs 902 and 904 can also transmit frames 914 and 916 to STAs in different BSSs. For example, when the multi-AP transmission scheme is JT / JR, AP 902 can also transmit frame 914 to STA 910 associated with AP 904, and AP 904 can also transmit frame 916 to STAs 906 and 908 associated with AP 902. The resources used for transmitting and receiving frames 914 and 916 can depend on the specific multi-AP transmission scheme employed.

[0089] STAs 906 and 908 can respond to frame 914, and STA 910 can respond to frame 916. For example, STAs 906 and 908 can transmit frames 918 and 920 to AP 902 respectively, while STA 910 can transmit frame 922 to AP 904. Frames 918, 920, and / or 922 can be transmitted simultaneously. Frames 918, 920, and 922 may include data frames or empty data frames. STAs 906, 908, and 910 can also transmit frames 918, 920, and 922 to APs in different BSSs as needed by the multi-AP transmission scheme used. For example, when the multi-AP transmission scheme is JT / JR, STAs 906 and 908 can also transmit the corresponding frames 918 and 920 to AP 904, and STA 910 can also transmit frame 922 to AP 902. The resources used for transmitting and receiving frames 918, 920, and 922 can depend on the specific multi-AP transmission scheme employed.

[0090] Figure 10 This is Example 1000 illustrating an existing measurement procedure according to the IEEE 802.11 standard. (As shown...) Figure 10 As shown, Example 1000 includes APs 1002 and 1004, and STAs 1006 and 1008. In Example 1000, APs 1002 and 1004 can be within each other's communication range. Thus, AP 1002 can be an Overlapping Service (OBSS) AP relative to AP 1004, and vice versa. In the example, STA 1006 can be associated with AP 1002, and STA 1008 can be associated with AP 1004. In the example, APs 1002 and 1004 can form a coordinated AP set.

[0091] like Figure 10 As shown, Example 1000 may begin with AP 1002 transmitting Measurement Request Frame 1010 to STA 1006. Measurement Request Frame 1010 may contain Measurement Request Elements for STA 1006. The Measurement Request Elements may contain Beacon Requests that request beacon reports for all observed BSSs that match the BSS Identifier (BSSID) indicated in the Beacon Request.

[0092] Upon receiving measurement request frame 1010, STA 1006 can begin the requested measurement as soon as possible. In this embodiment, the measurement request element may include the duration for which the measurement should be performed. Therefore, STA 1006 can perform the requested measurement during the indicated duration.

[0093] In Example 1000, the measurement request frame 1010 may contain a beacon request indicating the BSSID of the BSS (OBSS) of AP 1004. Thus, the beacon request requests STA 1006 to transmit a beacon report of AP 1004's BSS. In Example 1000, STA 1006 may perform the measurement requested by the beacon request upon hearing beacon frame 1014 from AP 1004. Specifically, upon receiving beacon frame 1014 and determining that the BSSID indicated in beacon frame 1014 matches the BSSID indicated in the beacon request, STA 1006 may perform the measurement requested by the beacon request on beacon frame 1014. Subsequently, STA 1006 may transmit a measurement report frame 1016 containing the beacon report to AP 1002.

[0094] In the implementation scheme, the beacon report is carried in the measurement report field of the measurement report element contained in the measurement report frame 1016. Figure 11 This illustrates the format of the measurement report field in the measurement report element when carrying beacon reports according to the IEEE 802.11 standard. (Example) Figure 11 As shown, the measurement report fields corresponding to the beacon report can include an operation category field, a channel number field, an actual measurement start time field, a measurement duration field, a report frame information field, an RCPI field, an RSNI field, a BSSID field, an antenna ID field, a parent TSF field, and optional child element fields.

[0095] The Operation Category field indicates the operation category of the channel set that is sending the beacon frame beacon report. The Channel Number field indicates the channel number of the beacon frame.

[0096] The Actual Measurement Start Time field is set to the value of the TSF timer for the STA at the start of the measurement. The Measurement Duration field is set to the duration of the measurement beacon report, in TU units.

[0097] The reported frame information field contains two subfields: the compressed PHY type subfield and the reported frame type subfield. The compressed PHY type subfield indicates the type of physical medium on which the beacon frame was received. The reported frame type subfield indicates the type of the frame being reported. When the report involves a beacon frame, the reported frame type subfield has a value of 0.

[0098] The RCPI field indicates the received channel power of the beacon frame. RCPI is a logarithmic function of the received signal power, as defined in Section 9.4.2.36 (RCPI Elements) of the 802.11 standard.

[0099] The RSNI field indicates the received signal-to-noise ratio of the beacon frame, as described in Section 9.4.2.39 (RSNI element) of the 802.11 standard.

[0100] The BSSID field contains the BSSID indicated in the reported beacon frame.

[0101] The Antenna ID field contains the identification number of the antenna or DMG antenna used for the measurement reported in the beacon report. The Antenna ID or DMG antenna ID is defined in Section 9.4.2.38 (Antenna Elements) of the 802.11 standard.

[0102] The parent TSF field contains the value of the STA's TSF timer, which is measured at the start of reception of the first octet of the timestamp field of the beacon frame.

[0103] Optional child element fields may contain zero or more child elements. The format and order of child elements are defined in Section 9.4.3 (Child Elements) of the 802.11 standard.

[0104] Return to Figure 10 In the example, AP 1004 can transmit a measurement request frame 1012 to STA 1008. In example 1000, the measurement request frame 1012 may contain a beacon request indicating the BSSID of AP 1002's BSS (OBSS). Thus, the beacon request requests STA 1008 to transmit a beacon report of AP 1002's BSS. In example 1000, STA 1008 can perform the measurement requested by the beacon request upon hearing a beacon frame 1018 from AP 1002. Specifically, upon receiving beacon frame 1018 and determining that the BSSID indicated in beacon frame 1018 matches the BSSID indicated in the beacon request, STA 1008 can perform the measurement requested by the beacon request on beacon frame 1018. Subsequently, STA 1008 can transmit a measurement report frame 1020 containing the beacon report to AP 1004. As mentioned above, the beacon report may include the Receive Channel Power Indicator (RCPI) and / or Receive Signal-to-Noise Ratio Indicator (RSNI) of beacon frame 1018.

[0105] Figure 12 It shows the use Figure 10 Example 1200 of the multi-AP coordination transmission procedure shown in the measurement procedure. Figure 12 As shown, Example 1200 also includes the references above. Figure 10 The APs 1002 and 1004, and the STAs 1006 and 1008 are described.

[0106] like Figure 12As shown, Example 1200 begins with AP 1002 transmitting Measurement Request Frame 1202 to STA 1006. In this example, Measurement Request Frame 1202 contains a beacon request indicating the BSSID of AP 1004's BSS. Thus, the beacon request requests STA 1006 to transmit a beacon report of AP 1004's BSS.

[0107] Subsequently, AP 1004 can transmit beacon frame 1204. Upon receiving beacon frame 1204 and determining that the BSSID indicated in beacon frame 1204 matches the BSSID indicated in the beacon request, STA 1006 can perform the measurement requested by the beacon request on beacon frame 1204. In this example, the measurement requested by the beacon request includes the RCPI and / or RNSI of beacon frame 1204. Subsequently, STA 1006 can transmit measurement report frame 1206 containing the beacon report to AP 1002. In this implementation, the beacon report is carried in the measurement report field of the measurement report element contained in measurement report frame 1206. The measurement report field may have the features described above. Figure 11 The format described in the document.

[0108] Upon receiving measurement report frame 1206, AP 1002 can initiate a multi-AP coordination transmission involving AP 1002 and AP 1004. In the example, AP 1002 can acquire a TXOP and can share the TXOP with AP 1004 to perform a multi-AP coordination transmission during the TXOP. Therefore, AP 1002 can be referred to as a sharing AP, and AP 1004 can be referred to as a shared AP.

[0109] In Example 1200, after receiving Measurement Report Frame 1206, AP 1002 transmits Trigger Frame 1208 to AP 1004 to initiate a multi-AP coordination transmission. Trigger Frame 1208 may contain a RU for AP 1004 to perform the multi-AP coordination transmission. Trigger Frame 1208 may also indicate the duration of the multi-AP coordination transmission.

[0110] After AP 1002 transmits trigger frame 1208, APs 1002 and 1004 can transmit corresponding data frames 1210 and 1212 for multi-AP coordinated transmission. In an implementation, data frames 1210 and 1212 can be transmitted one SIFS after trigger frame 1208. Figure 12 As shown, data frames 1210 and 1212 can be transmitted simultaneously and can overlap with each other during the duration of multi-AP coordinated transmission.

[0111] In this example, multi-AP coordinated transmission can be CSR transmission. Therefore, the RU used for multi-AP coordinated transmission by AP 1004 can be a shared RU used by both AP 1002 and AP 1004 for multi-AP coordinated transmission. In other words, data frames 1210 and 1212 can both be transmitted through the same RU. Therefore, in addition to coordinating the transmission timing of data frames 1210 and 1212, AP 1002 can also coordinate / control the transmission power of data frames 1210 and 1212 to ensure proper spatial multiplexing by AP 1002 and 1004 for multi-AP coordinated transmission.

[0112] In the example, AP 1002 can use a beacon report from STA 1006 to set a first transmission power for the PPDU carrying data frame 1212, which is transmitted by AP 1004. AP 1002 can indicate the first transmission power or parameters for calculating the first transmission power in trigger frame 1208. AP 1004 can use the first transmission power to limit the transmission power of the PPDU carrying data frame 1212 (i.e., to the maximum transmission power). Therefore, AP 1002 ensures proper spatial multiplexing for multi-AP coordinated transmission, and data frames 1210 and 1212 can be successfully received by STAs 1006 and 1008, respectively.

[0113] In the implementation, the beacon report from STA 1006 may include the RCPI of beacon frame 1204 transmitted by AP 1004. AP 1002 can calculate the first transmission power of AP 1004 as TXP. ref – Retreat (BO), where TXP ref This is the reference transmission power used to transmit beacon frame 1204, where BO is equal to the RCPI of beacon frame 1204 minus the acceptable receive interference level (ARIL) at STA 1006 when receiving data frame 1210. In an implementation, AP 1002 may indicate the first transmission power of AP 1004 in trigger frame 1208. Alternatively, AP 1002 may indicate BO in trigger frame 1208, and AP 1004 may calculate the first transmission power as TXP. ref – BO.

[0114] As mentioned above, an AP can allocate resources to another AP for coordinated multi-AP transmission. These resources can be allocated using the trigger frame described above. The trigger frame can indicate the duration and RU allocation for the other AP. An RU allocation can contain one or more RUs. The size of an RU is defined by the number of subcarriers (tones) within the RU. The IEEE 802.11 standard defines different RU types ranging in size from 26 subcarriers (26-subcarrier RU) to 996 subcarriers (996-subcarrier RU). Table 27-6 of the IEEE 802.11 standard (“IEEE P802.11-REVme / D2.1, January 2023”) provides the maximum number of RUs that a PPDU (e.g., a TB PPDU or a SU / MU PPDU) can have, varying with the PPDU's bandwidth and the RU types used in the PPDU. It should be noted that MU PPDUs used for MU OFDMA can carry a mixture of RU types.

[0115] Tables 27-7, 27-8, and 27-9 of the IEEE 802.11 standard provide RU indices and subcarrier ranges for different RU types and PPDU bandwidth combinations. For example, for a 52-subcarrier RU and a 20 MHz PPDU bandwidth, the PPDU can have four RUs, indexed as RU1, RU2, RU3, and RU4. RU1 corresponds to the subcarrier range [-121:-70], RU2 to the subcarrier range [-68:-17], RU3 to the subcarrier range [17:68], and RU4 to the subcarrier range [70:121]. For example, the allocation including RU1, RU2, RU3, and RU4 can be as follows: Figure 13 As shown, RU1, RU2, RU3, and RU4 each comprise a set of consecutive subcarriers on the corresponding portion of the PPDU bandwidth. The corresponding portions of the PPDU bandwidth covered by different RUs do not overlap and can be separated from each other by one or more empty subcarriers. In the case where the PPDU comprises a single RU, the subcarrier set of the RU covers the entire PPDU bandwidth.

[0116] The existing IEEE 802.11 standard only defines RUs that contain a continuous set of subcarriers (e.g., such as...). Figure 13 (As shown in the image). This type of RU is referred to below as a non-distributed RU. U.S. Patent 11,044,057 proposes an RU called a distributed RU, which contains a non-contiguous set of subcarriers extended over the PPDU bandwidth. An example allocation of a distributed RU is shown below. Figure 14As shown, the distributed RU comprises a set of non-contiguous subcarriers that can be extended across the entire bandwidth of the PPDU, rather than a RU consisting of a set of contiguous subcarriers that only covers the corresponding portion of the PPDU bandwidth.

[0117] Extending the RU across the entire PPDU bandwidth significantly reduces the power spectral density (PSD) of the PPDU. This allows devices transmitting the PPDU (e.g., APs or STAs) to operate in spectrum portions with stricter PSD requirements. For example, under low power indoor (LPI) PSD requirements (5 dBm / MHz for APs, -1 dBm / MHz for STAs), unlicensed use of the extended 6 GHz band allows operation on an additional 1.2 GHz bandwidth (operating bands U-NII-5 (5.925–6.425 GHz), U-NII-6 (6.425–6.525 GHz), U-NII-7 (6.525–6.875 GHz), and U-NII-8 (6.875–7.125 GHz)). Alternatively or additionally, devices can utilize the lower PSD resulting from the use of distributed RUs to increase the transmission power of the PPDU. This could be particularly useful in UL MUOFDMA, as it would allow each transmission STA to increase its transmission power, resulting in higher receive power across all subcarriers and significantly enhanced overall spectral efficiency.

[0118] Figure 15 It is shown in Figure 12 Example 1500 illustrates a potential problem in a multi-AP coordinated transmission procedure. (See example 1500.) Figure 15 As shown, Example 1500 also includes the references above. Figure 10 The APs 1002 and 1004, and the STAs 1006 and 1008 are described.

[0119] Similar to Example 1200 above, Example 1500 may also begin with AP 1002 transmitting a Measurement Request Frame 1502 to STA 1006. In this example, Measurement Request Frame 1502 contains a beacon request indicating the BSSID of AP 1004's BSS. Thus, the beacon request requests STA 1006 to transmit a beacon report of AP 1004's BSS.

[0120] Subsequently, AP 1004 can transmit beacon frame 1504. In this example, beacon frame 1504 can be transmitted via a 20 MHz PPDU. In this example, 242 subcarrier RUs are used. In another example, without using OFDMA to transmit the 20 MHz PPDU, the number of subcarriers can be reduced to 52 or 56, while still occupying a similar bandwidth as 242 subcarrier RUs. Upon receiving beacon frame 1504 and determining that the BSSID indicated in beacon frame 1504 matches the BSSID indicated in the beacon request, STA 1006 can perform the measurement requested in the beacon request on beacon frame 1504. In this example, the measurement requested in the beacon request includes the RCPI and / or RNSI of beacon frame 1504. Subsequently, STA 1006 can transmit measurement report frame 1506 containing the beacon report to AP 1002. In this implementation, the beacon report is carried in the measurement report field of the measurement report element contained in measurement report frame 1506. Measurement report fields can have the above-mentioned... Figure 11 The format described in the document.

[0121] After receiving the measurement report frame 1506, AP 1002 can initiate a multi-AP coordination transmission involving AP 1002 and AP 1004. In Example 1200, after receiving the measurement report frame 1506, AP 1002 transmits a trigger frame 1508 to AP 1004 to initiate the multi-AP coordination transmission. The trigger frame 1508 may contain a RU for AP 1004 to perform the multi-AP coordination transmission. In the example, the RU may be a 242-subcarrier RU consisting of four 52-subcarrier RUs. Thus, the RU can support a 20 MHz PPDU for the multi-AP coordination transmission. The trigger frame 1508 may also indicate the duration of the multi-AP coordination transmission.

[0122] After AP 1002 transmits trigger frame 1508, APs 1002 and 1004 can transmit corresponding data frames 1510 and 1512 for multi-AP coordinated transmission. In an implementation, data frames 1510 and 1512 can be transmitted one SIFS after trigger frame 1508. Figure 15 As shown, data frames 1510 and 1512 can be transmitted simultaneously and can overlap with each other during the duration of multi-AP coordinated transmission.

[0123] In Example 1500, the multi-AP coordinated transmission can be a CSR transmission, and AP 1002 can indicate a first transmission power (or parameters for calculating the first transmission power for AP 1004 to use for CSR transmission) in the trigger frame 1508. In an implementation, AP 1002 can determine the first transmission power for AP 1004 to use for CSR transmission based on the beacon report contained in the measurement report frame 1506. In an implementation, the beacon report from STA 1006 can include the RCPI of the beacon frame 1504 transmitted by AP 1004. AP 1002 can calculate the first transmission power of AP 1004 as TXP. ref – BO, where TXP ref It is the reference transmission power used to transmit beacon frame 1504, and BO is equal to the RCPI of beacon frame 1504 minus ARIL at STA 1006 when receiving data frame 1510.

[0124] AP 1004 can use the first transmission power indicated in trigger frame 1508 to limit the transmission power (i.e., the maximum transmission power) of the PPDU carrying data frame 1512. In the example, to boost the RSNI of data frame 1512 at STA 1008, AP 1004 can use fewer subcarriers than the total number of subcarriers of RUs used for multi-AP coordinated transmission indicated in trigger frame 1508 to transmit the PPDU carrying data frame 1512. For example, suppose the RUs indicated in trigger frame 1508 are as follows: Figure 14 As shown (i.e., for a 20 MHz bandwidth, consisting of RU1, RU2, RU3, and RU4), AP 1004 can, for example, transmit data frame 1512 (for 4 MHz) only via RU1. In a specific example, such as Figure 15 As shown, the RU indicated in trigger frame 1508 can be a 242-subcarrier RU, and AP 1004 can transmit data frame 1512 via 106 subcarrier portions of the RU instead of using all 242 subcarriers of the RU. Using a smaller number of subcarriers than the number indicated in the RU can be an implementation-dependent feature that AP 1004 can support. However, even if AP 1004 uses the first transmission power indicated in trigger frame 1508, the use of such a feature by AP 1004 may cause unacceptable interference at STA 1006. Specifically, using fewer subcarriers than the number indicated in the RU increases the PSD of the PPDU carrying data frame 1512, thereby causing higher than acceptable interference at STA 1006 and failure of STA 1006 to receive data frame 1510.

[0125] As further described below, embodiments of this disclosure address the aforementioned problems. In one aspect, a first AP coordinating multi-AP coordinated transmission involving a second AP may instruct the second AP whether, during multi-AP coordinated transmission, it is permissible to use a smaller number of subcarriers than the total indicated number of subcarriers for the multi-AP coordinated transmission. In another aspect, the first AP may instruct the second AP whether a change in RU size configuration is permissible during multi-AP coordinated transmission. The multi-AP coordinated transmission may be a CSR transmission, for which it may be necessary to limit the transmission power of the second AP. In another aspect, when coordinating multi-AP coordinated transmission, the first AP may instruct multiple transmission powers available to the second AP, depending on whether the second AP uses a smaller number of subcarriers than the indicated total number of subcarriers for the multi-AP coordinated transmission. In yet another aspect, the first AP may instruct the second AP whether it is permissible to use a smaller number of subcarriers than the indicated total number of subcarriers for a particular type of multi-AP coordinated transmission. For example, when the multi-AP coordinated transmission is a CSR transmission, the first AP may instruct the second AP that it may not use a smaller number of subcarriers than the indicated total number of subcarriers for the multi-AP coordinated transmission. Other aspects and details of this disclosure are set forth below and will be apparent to those skilled in the art based on the teachings herein.

[0126] Figure 16 This is an example 1600 illustrating a multi-AP coordinated transmission procedure according to an embodiment. For example... Figure 16 As shown, Example 1600 includes APs 1602 and 1604, and STAs 1606 and 1608. In Example 1600, APs 1602 and 1604 can be within each other's communication range. Thus, AP 1602 can be an OBSS AP relative to AP 1604, and vice versa. In the example, STA 1606 can be associated with AP 1602, and STA 1608 can be associated with AP 1604. In the example, APs 1602 and 1604 can form a coordinated AP set.

[0127] like Figure 16 As shown, Example 1600 may begin with AP 1602 transmitting Measurement Request Frame 1610 to STA 1606. Measurement Request Frame 1610 may contain a Measurement Request element for STA 1606. The Measurement Request element may contain a Beacon Request that requests a beacon report for all observed BSSs matching the BSSID indicated in the Beacon Request.

[0128] Upon receiving measurement request frame 1610, STA 1606 can begin the requested measurement as soon as possible. In this embodiment, the measurement request element may include the duration for which the measurement should be performed. Therefore, STA 1606 can perform the requested measurement during the indicated duration.

[0129] In Example 1600, Measurement Request Frame 1610 may contain a beacon request indicating the BSSID of the BSS of AP 1604. Thus, the beacon request requests STA 1606 to transmit a beacon report of the BSS of AP 1604. In Example 1600, STA 1606 may perform the measurement requested by the beacon request upon hearing beacon frame 1612 from AP 1604. In this example, the measurement requested by the beacon request includes the RCPI and / or RNSI of beacon frame 1612. Specifically, upon receiving beacon frame 1612 and determining that the BSSID indicated in beacon frame 1612 matches the BSSID indicated in the beacon request, STA 1606 may perform the measurement requested by the beacon request on beacon frame 1612. Subsequently, STA 1606 may transmit a Measurement Report Frame 1614 containing the beacon report to AP 1602. In the implementation scheme, the beacon report is carried within the measurement report field of the measurement report element contained in measurement report frame 1614. The measurement report field may have the features described above. Figure 11 The format described in the document.

[0130] After receiving measurement report frame 1614, AP 1602 can initiate a multi-AP coordination transmission involving AP 1602 and AP 1604. In Example 1600, after receiving measurement report frame 1614, AP 1602 transmits trigger frame 1616 to AP 1604 to initiate the multi-AP coordination transmission. Trigger frame 1616 may contain a RU for AP 1604 to perform the multi-AP coordination transmission. Trigger frame 1616 may also indicate the duration of the multi-AP coordination transmission.

[0131] After AP 1602 transmits trigger frame 1616, APs 1602 and 1604 can transmit corresponding data frames 1618 and 1620 for multi-AP coordinated transmission. In an implementation, data frames 1618 and 1620 can be transmitted one SIFS after trigger frame 1616. Figure 16 As shown, data frames 1618 and 1620 can be transmitted simultaneously and can overlap with each other during the duration of multi-AP coordinated transmission.

[0132] In an embodiment, trigger frame 1616 may indicate whether AP 1604 is allowed to use a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1616 for transmission during multi-AP coordinated transmission. Therefore, AP 1604 may use a portion of the RUs, RU', to transmit the PPDU carrying data frame 1620 during multi-AP coordinated transmission. For example, the RU may be a 242-subcarrier RU, and RU' may correspond to 106 subcarriers of the RU. In an embodiment, trigger frame 1616 may include an RU size reduction allow flag. This flag can be set to 1 when using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1616 is permitted.

[0133] In another embodiment, trigger frame 1616 may also indicate the minimum RU size (or the minimum number of modulated subcarriers) that AP 1604 can use during multi-AP coordinated AP transmission. In this embodiment, when the minimum RU size is indicated, the RU size reduction allow flag may not be present in trigger frame 1616. Alternatively, both the RU size reduction allow flag and the minimum RU size may be indicated in trigger frame 1616.

[0134] In another embodiment, trigger frame 1616 may also indicate whether AP 1604 can use a distributed RU during multi-AP coordinated transmission. For example, refer to Figure 13 and 14 In AP 1604, non-distributed RUs are assigned (e.g., Figure 13 In the case of RU 1) for multi-AP coordinated transmission, the permission for the use of distributed RUs may allow AP 1604 to transmit via an assigned non-distributed RU or a distributed RU of the same size (e.g., Figure 14 The distributed RU 1) in the transmission is used. This can be a supplement to using fewer subcarriers than the indicated RU, if permitted.

[0135] In an embodiment, AP 1602 may also indicate a first transmission power (or parameters for calculating the first transmission power used by AP 1604) for multi-AP coordinated transmission in trigger frame 1616. Multi-AP coordinated transmission may be a CSR transmission. In an implementation, AP 1602 may determine the first transmission power used by AP 1604 based on a beacon report contained in measurement report frame 1614. In an implementation, the beacon report from STA 1606 may contain the RCPI of beacon frame 1612 transmitted by AP 1604. AP 1602 may calculate the first transmission power of AP 1604 as TTP. ref – BO, where TTP refThis is the known reference transmission power for both APs 1602 and 1604, where BO is equal to the RCPI of beacon frame 1612 minus the ARIL at STA 1606 when receiving data frame 1618. In the implementation, TXP ref Used for transmitting beacon frame 1612. In an implementation, AP 1602 may indicate the first transmission power of AP 1604 in trigger frame 1616. Alternatively, AP 1602 may indicate BO in trigger frame 1616, and AP 1604 may calculate the first transmission power as TFP. ref – BO.

[0136] In this embodiment, the indication regarding whether AP 1604 is allowed to transmit using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1616 during multi-AP coordinated transmission is conditional upon AP 1604 using a first transmission power for multi-AP coordinated transmission. The first transmission power or a parameter used to calculate the first transmission power may be indicated in trigger frame 1616. In this example, AP 1604 may use a reference transmission power TXP. ref To transmit beacon frame 1612. AP 1602 can calculate the first transmission power as TTP. ref – BO, where BO is equal to the RCPI of beacon frame 1612 (as measured by STA 1606) minus the ARIL at STA 1606 when receiving data frame 1618.

[0137] In one embodiment, the indication regarding whether AP 1604 is allowed to transmit using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1616 during multi-AP coordinated transmission is conditional upon AP 1604 using a first transmission power, and further conditional upon calculating the first transmission power based on a frame transmitted by AP 1604 using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1616 (e.g., based on beacon frame 1612 transmitted using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1616). In another embodiment, the indication regarding whether AP 1604 is allowed to transmit using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1616 during multi-AP coordinated transmission is further conditional upon AP 1604 using the same RU size configuration as used for the frame (on which the first transmission power is determined).

[0138] In Example 1600, trigger frame 1616 may indicate that AP 1604 is allowed to transmit using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1616 during multi-AP coordinated transmission. Trigger frame 1616 may also indicate a minimum RU size. Trigger frame 1616 may also indicate the first transmission power described above for AP 1604 to use during multi-AP coordinated transmission. In the example, as... Figure 16 As shown, AP 1604 can selectively use a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1616 to transmit the PPDU carrying data frame 1620. For example, AP 1604 can use a portion of the RUs, RU', to transmit the PPDU carrying data frame 1620 during multi-AP coordinated transmission. For example, the RU could be a 242-subcarrier RU, and RU' could correspond to 106 subcarriers of the RU. Therefore, AP 1604 can use a first transmission power to limit the transmission power of the PPDU carrying data frame 1620. Since AP 1602 sets the first transmission power to comply with ARIL when receiving data frame 1618 at STA 1606, even though AP 1604 uses a smaller number of subcarriers for transmission, proper spatial multiplexing of multi-AP coordinated transmission is achieved, and data frames 1618 and 1620 can be successfully received by STAs 1606 and 1608, respectively. In one embodiment, when AP 1604 is allowed to transmit using fewer subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1616, AP 1602 may downgrade its modulation and coding scheme (MCS) used during multi-AP coordinated transmission (e.g., relative to the MCS used before or after multi-AP coordinated transmission) to accommodate a potential reduction in the RU size of AP 1604 during multi-AP coordinated transmission. In one embodiment, the downgraded MCS may be determined based on the minimum RU size and / or whether the use of distributed RUs is permitted, as indicated in trigger frame 1616. In another embodiment, AP 1602 may use a lower ARIL than anticipated by the MCS it uses during multi-AP coordinated transmission to calculate the first transmission power, thereby allowing AP 1604 to use a lower first transmission power.

[0139] Figure 17 This is an example 1700 illustrating a multi-AP coordinated transmission procedure according to another embodiment. For example... Figure 17 As shown, Example 1700 also includes the references above. Figure 16 The AP 1602 and 1604 and STA 1606 and 1608 are described.

[0140] like Figure 17As shown, before initiating a multi-AP coordination transmission with AP 1604, AP 1602 can initiate the measurement procedure described above. Specifically, AP 1602 can transmit a measurement request frame 1710 to STA 1606. In Example 1700, the measurement request frame 1710 may contain a beacon request indicating the BSSID of AP 1604's BSS. Thus, the beacon request requests STA 1606 to transmit a beacon report of AP 1604's BSS. In Example 1700, STA 1606 can perform the measurement requested by the beacon request upon hearing beacon frame 1712 from AP 1604. In this example, the measurement requested by the beacon request includes the RCPI and / or RNSI of beacon frame 1712. Specifically, upon receiving beacon frame 1712 and determining that the BSSID indicated in beacon frame 1712 matches the BSSID indicated in the beacon request, STA 1606 can perform the measurement requested in the beacon request on beacon frame 1712. Subsequently, STA 1606 can transmit a measurement report frame 1714 containing the beacon report to AP 1602. In this implementation, the beacon report is carried in the measurement report field of the measurement report element contained in measurement report frame 1714. The measurement report field may have the characteristics described above. Figure 11 The format described in the document.

[0141] After receiving measurement report frame 1714, AP 1602 can initiate a multi-AP coordination transmission involving AP 1602 and AP 1604. In Example 1700, after receiving measurement report frame 1714, AP 1602 transmits trigger frame 1716 to AP 1604 to initiate the multi-AP coordination transmission. Trigger frame 1716 may contain a RU for AP 1604 to perform the multi-AP coordination transmission. Trigger frame 1716 may also indicate the duration of the multi-AP coordination transmission.

[0142] After AP 1602 transmits trigger frame 1716, APs 1602 and 1604 can transmit corresponding data frames 1718 and 1720 for multi-AP coordinated transmission. In an implementation, data frames 1718 and 1720 can be transmitted one SIFS after trigger frame 1716. Figure 17 As shown, data frames 1718 and 1720 can be transmitted simultaneously and can overlap with each other during the duration of multi-AP coordinated transmission.

[0143] In an embodiment, trigger frame 1716 may also indicate whether AP 1604 is permitted to use a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1716 for transmission during multi-AP coordinated transmission. Therefore, AP 1604 may use a portion of the RUs, RU', to transmit the PPDU carrying data frame 1720 during multi-AP coordinated transmission. For example, RU could be a 242-subcarrier RU, and RU' could correspond to 106 subcarriers of the RUs.

[0144] In an embodiment, AP 1602 may indicate a first transmission power (or parameters for calculating the first transmission power) for AP 1604 to use for multi-AP coordinated transmission in trigger frame 1716. Multi-AP coordinated transmission may be a CSR transmission. In an embodiment, AP 1602 may determine the first transmission power for AP 1604 to use for CSR transmission based on a beacon report contained in measurement report frame 1714. In an implementation, the beacon report from STA 1606 may include the RCPI of beacon frame 1712 transmitted by AP 1604. AP 1602 may calculate the first transmission power of AP 1604 as TXP. ref – BO, where TXP ref This is the reference transmission power used to transmit beacon frame 1712, where BO is equal to the RCPI of beacon frame 1712 minus the ARIL at STA 1606 when receiving data frame 1718. In an implementation, AP 1602 may indicate the first transmission power of AP 1604 in trigger frame 1716. Alternatively, AP 1602 may indicate BO in trigger frame 1716, and AP 1604 may calculate the first transmission power as TXP. ref – BO.

[0145] In an embodiment, the indication regarding whether AP 1604 is allowed to transmit using fewer subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1716 during multi-AP coordinated transmission is conditional upon AP 1604 using a first transmission power for multi-AP coordinated transmission.

[0146] In one embodiment, the indication regarding whether AP 1604 is allowed to transmit using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1716 during multi-AP coordinated transmission is conditional upon AP 1604 using a first transmission power, and further conditional upon the first transmission power being calculated based on a first frame transmitted by AP 1704 using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1716 (e.g., based on beacon frame 1712 transmitted using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1716). In another embodiment, the indication regarding whether AP 1604 is allowed to transmit using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1716 during multi-AP coordinated transmission is further conditional upon AP 1604 using the same RU size configuration during multi-AP coordinated transmission as the RU size configuration used for the first frame (based on which the first transmission power is determined).

[0147] In an embodiment, trigger frame 1716 may indicate whether AP 1604 is allowed to use a different RU size configuration (e.g., fewer subcarriers) than the RU size configuration used for the first frame during multi-AP coordinated transmission. In an embodiment, trigger frame 1716 may include an RU size configuration change permission flag. This flag can be set to 1 when a different RU size configuration than the one used for the first frame is permitted. If RU size configuration changes are not permitted, AP 1604 may use fewer subcarriers than the total number of subcarriers for the RUs indicated in trigger frame 1716 during multi-AP coordinated transmission if the same RU size configuration is used for the PPDU carrying data frame 1720 as for the first frame. In such a case, AP 1602 may indicate a first transmission power determined based on the first frame in trigger frame 1716. AP 1602 may use the same ARIL used to determine the first transmission power used by AP 1604 to set its MCS for multi-AP coordinated transmission. If RU size configuration changes are permitted, AP 1604 can use a different RU size configuration during multi-AP coordinated transmission than the RU size configuration used for the first frame. In such cases, AP 1602 can indicate a first transmission power in trigger frame 1716, which is determined to compensate for potential use of a different RU size configuration (e.g., minimum RU size) by AP 1604 during multi-AP coordinated transmission. For example, AP 1602 can determine the transmission power based on the first frame and can reduce the determined power by backoff to determine the first transmission power. AP 1602 can use the same ARIL used to determine the first transmission power used by AP 1604 to set its MCS for multi-AP coordinated transmission.

[0148] In Example 1700, Trigger Frame 1716 may indicate that AP 1604 is allowed to transmit using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in Trigger Frame 1716 during multi-AP coordinated transmission, and also indicates that RU size configuration changes are allowed during multi-AP coordinated transmission. Trigger Frame 1716 may also indicate the first transmission power determined above for AP 1604 to use during multi-AP coordinated transmission. In the example, as... Figure 17 As shown, AP 1604 can optionally use a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 176 for transmission of the PPDU carrying data frame 1720. AP 1604 can use the same or different RU size configuration as used for the first frame (e.g., beacon frame 1712). Therefore, AP 1604 can use a first transmission power to limit the transmission power (i.e., to the maximum transmission power) of the PPDU carrying data frame 1720.

[0149] Because AP 1602 sets the first transmission power to follow ARIL when receiving data frame 1718 at STA 1606, even if AP 1604 transmits the PPDU carrying data frame 1720 using a different RU size configuration than the one used for the first frame, proper spatial multiplexing of multi-AP coordinated transmission is achieved, and data frames 1718 and 1720 can be successfully received by STA 1606 and 1608 respectively.

[0150] Figure 18 This is an example 1800 illustrating a multi-AP coordinated transmission procedure according to another embodiment. For example... Figure 18 As shown, Example 1800 also includes the references above. Figure 16 The AP 1602 and 1604 and STA 1606 and 1608 are described.

[0151] like Figure 18 As shown, Example 1800 may begin with AP 1602 transmitting beacon frame 1802. In one embodiment, beacon frame 1802 may indicate whether AP 1602 is permitted to use a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in a multi-AP coordination transmission initiated by AP 1602 (e.g., the RUs indicated in the trigger frame for the multi-AP coordination transmission). In another embodiment, beacon frame 1802 may indicate whether AP 1602 is permitted to use a smaller number of subcarriers than the total number of subcarriers of the indicated RUs for a particular multi-AP coordination transmission initiated by AP 1602. For example, beacon frame 1802 may indicate whether AP 1602 is permitted to use a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in a CSR transmission initiated by AP 1602.

[0152] In another embodiment, beacon frame 1802 may alternatively or additionally indicate whether distributed RUs are permitted in a multi-AP coordinated transmission initiated by AP 1602. In another embodiment, beacon frame 1802 may also indicate the minimum RU size (or the minimum number of modulated subcarriers) that can be used in a multi-AP coordinated transmission initiated by AP 1602.

[0153] Subsequently, before initiating a multi-AP coordination transmission with AP 1604, AP 1602 can initiate the measurement procedure as described above. Specifically, AP 1602 can transmit a measurement request frame 1810 to STA 1606. In Example 1800, the measurement request frame 1810 may contain a beacon request indicating the BSSID of AP 1604's BSS. Thus, the beacon request requests STA 1606 to transmit a beacon report of AP 1604's BSS. In Example 1800, STA 1606 can perform the measurement requested by the beacon request upon hearing beacon frame 1812 from AP 1604. In this example, the measurement requested by the beacon request includes the RCPI and / or RNSI of beacon frame 1812. Specifically, upon receiving beacon frame 1812 and determining that the BSSID indicated in beacon frame 1812 matches the BSSID indicated in the beacon request, STA 1606 can perform the measurement requested in the beacon request on beacon frame 1812. Subsequently, STA 1606 can transmit a measurement report frame 1814 containing the beacon report to AP 1602. In this implementation, the beacon report is carried in the measurement report field of the measurement report element contained in measurement report frame 1814. The measurement report field may have the features described above. Figure 11 The format described in the document.

[0154] After receiving the measurement report frame 1814, AP 1602 can initiate a multi-AP coordination transmission involving AP 1602 and AP 1604. In Example 1800, after receiving the measurement report frame 1814, AP 1602 transmits a trigger frame 1816 to AP 1604 to initiate the multi-AP coordination transmission. The trigger frame 1816 may contain a RU for AP 1604 to perform the multi-AP coordination transmission. The trigger frame 1816 may also indicate the duration of the multi-AP coordination transmission.

[0155] After AP 1602 transmits trigger frame 1816, APs 1602 and 1604 can transmit corresponding data frames 1818 and 1820 for multi-AP coordinated transmission. In an implementation, data frames 1818 and 1820 can be transmitted one SIFS after trigger frame 1816. Figure 18 As shown, data frames 1818 and 1820 can be transmitted simultaneously and can overlap with each other during the duration of multi-AP coordinated transmission.

[0156] In an embodiment, AP 1602 may indicate a first transmission power (or parameters for calculating the first transmission power used by AP 1604) in trigger frame 1816 for multi-AP coordinated transmission. Multi-AP coordinated transmission may be a CSR transmission. In an implementation, AP 1602 may determine the first transmission power used by AP 1604 based on a beacon report contained in measurement report frame 1814. In an implementation, the beacon report from STA 1606 may include the RCPI of beacon frame 1812 transmitted by AP 1604. AP 1602 may calculate the first transmission power of AP 1604 as TXP. ref – BO, where TXP ref This is the reference transmission power used to transmit beacon frame 1812, where BO is equal to the RCPI of beacon frame 1812 minus the ARIL at STA 1606 when receiving data frame 1818. In an implementation, AP 1602 may indicate the first transmission power of AP 1604 in trigger frame 1816. Alternatively, AP 1602 may indicate BO in trigger frame 1816, and AP 1604 may calculate the first transmission power as TXP. ref – BO.

[0157] In an embodiment, when beacon frame 1802 indicates that AP 1604 is permitted to use a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1816 for transmission during multi-AP coordinated transmission, a first transmission power (or a parameter for calculating the first transmission power used by AP 1604) is determined based on the permitted number of subcarriers. For example, when beacon frame 1812 is transmitted using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1816, AP 1602 can use the beacon report contained in measurement report frame 1814 to determine the first transmission power. AP 1604 may use the same RU size configuration as used for beacon frame 1812 during multi-AP coordinated transmission. In an embodiment, when beacon frame 1802 indicates that AP 1804 is not allowed to use fewer subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1816 for transmission during multi-AP coordinated transmission, a first transmission power (or a parameter for calculating the first transmission power) for AP 1604 for multi-AP coordinated transmission is determined based on allowing the use of fewer subcarriers.

[0158] In Example 1800, Beacon Frame 1802 may indicate that AP 1604 is allowed to transmit using a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in Trigger Frame 1816 during multi-AP coordinated transmission. Therefore, Trigger Frame 1816 may indicate a first transmission power available to AP 1604 during multi-AP coordinated transmission, determined based on the allowed use of a smaller number of subcarriers. In the example, as... Figure 18 As shown, AP 1604 can choose to use a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1816 to transmit the PPDU carrying data frame 1820. Therefore, AP 1604 can use a first transmission power to limit the transmission power of the PPDU carrying data frame 1820 (i.e., the maximum transmission power). Since AP 1602 sets the first transmission power to comply with ARIL when receiving data frame 1818 at STA 1606, even though AP 1604 uses a smaller number of subcarriers for transmission, proper spatial multiplexing for multi-AP coordinated transmission is achieved, and data frames 1818 and 1820 can be successfully received by STAs 1606 and 1608, respectively. In an embodiment, when AP 1604 is allowed to transmit using fewer subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1816 during multi-AP coordinated transmission, AP 1602 may reduce the MCS it uses during multi-AP coordinated transmission (e.g., relative to the MCS used before or after multi-AP coordinated transmission) to accommodate the potential reduction in RU size of AP 1604 during multi-AP coordinated transmission.

[0159] Figure 19 This is an example 1900 illustrating a multi-AP coordinated transmission procedure according to another embodiment. For example... Figure 19 As shown, Example 1900 also includes the references above. Figure 16 The AP 1602 and 1604 and STA 1606 and 1608 are described.

[0160] like Figure 19As shown, before initiating a multi-AP coordination transmission with AP 1604, AP 1602 can initiate the measurement procedure described above. Specifically, AP 1602 can transmit a measurement request frame 1910 to STA 1606. In Example 1900, the measurement request frame 1910 may contain a beacon request indicating the BSSID of AP 1604's BSS. Thus, the beacon request requests STA 1606 to transmit a beacon report of AP 1604's BSS. In Example 1900, STA 1606 can perform the measurement requested by the beacon request upon hearing beacon frame 1912 from AP 1604. In this example, the measurement requested by the beacon request includes the RCPI and / or RNSI of beacon frame 1912. Specifically, upon receiving beacon frame 1912 and determining that the BSSID indicated in beacon frame 1912 matches the BSSID indicated in the beacon request, STA 1606 can perform the measurement requested in the beacon request on beacon frame 1912. Subsequently, STA 1606 can transmit a measurement report frame 1914 containing the beacon report to AP 1602. In this implementation, the beacon report is carried in the measurement report field of the measurement report element contained in measurement report frame 1914. The measurement report field may have the characteristics described above. Figure 11 The format described in the document.

[0161] After receiving measurement report frame 1914, AP 1602 can initiate a multi-AP coordination transmission involving AP 1602 and AP 1604. In Example 1900, after receiving measurement report frame 1914, AP 1602 transmits trigger frame 1916 to AP 1604 to initiate the multi-AP coordination transmission. Trigger frame 1916 may contain a RU for AP 1604 to perform the multi-AP coordination transmission. Trigger frame 1916 may also indicate the duration of the multi-AP coordination transmission.

[0162] After AP 1602 transmits trigger frame 1916, APs 1602 and 1604 can transmit corresponding data frames 1918 and 1920 for multi-AP coordinated transmission. In an implementation, data frames 1918 and 1920 can be transmitted one SIFS after trigger frame 1916. Figure 19 As shown, data frames 1918 and 1920 can be transmitted simultaneously and can overlap with each other during the duration of multi-AP coordinated transmission.

[0163] In an embodiment, trigger frame 1916 may indicate whether AP 1604 is permitted to use a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 1916 for transmission during multi-AP coordinated transmission. Therefore, AP 1604 may use a portion of the RUs, RU', to transmit the PPDU carrying data frame 1920 during multi-AP coordinated transmission. For example, RU may be a 242-subcarrier RU, and RU' may correspond to 106 subcarriers of the RUs.

[0164] In an embodiment, where the use of fewer subcarriers than the total number of subcarriers of the RU indicated in the trigger frame 1916 is permitted during multi-AP coordinated transmission, the trigger frame 1916 may indicate a first transmission power used by AP 1604 during multi-AP coordinated transmission when AP 1604 does not use fewer subcarriers than the total number of subcarriers of the RU, and a second transmission power used by AP 1604 during multi-AP coordinated transmission when AP 1604 uses fewer subcarriers than the total number of subcarriers of the RU. Multi-AP coordinated transmission may be a CSR transmission. The first transmission power may be higher than the second transmission power. For example, the first transmission power may be determined based on a first frame transmitted by AP 1604 using the same number of subcarriers as the total number of subcarriers of the RU, and the second transmission power may be determined based on a second frame transmitted by AP 1604 using fewer subcarriers than the total number of subcarriers of the RU.

[0165] In one embodiment, trigger frame 1916 may indicate a first transmission power and / or a second transmission power. In another embodiment, trigger frame 1916 may indicate a first parameter for determining the first transmission power and / or a second parameter for determining the second transmission power. In one embodiment, trigger frame 1916 may indicate a first transmission power fallback and / or a second transmission power fallback. The first transmission power can be determined by subtracting the first transmission power fallback from a reference transmission power. The second transmission power can be determined by subtracting the second transmission power fallback from a reference transmission power. In another embodiment, trigger frame 1916 may indicate the first transmission power. The second transmission power can be determined by subtracting the fallback from the first transmission power. Fallback may be indicated in trigger frame 1916 or in a management frame (e.g., a beacon) transmitted by AP 1602.

[0166] In another embodiment, a first transmission power can be determined based on a first frame transmitted by AP 1604 using a first RU size configuration, where the first RU size configuration uses a first number of subcarriers less than the total number of RU subcarriers. During multi-AP coordinated transmission, AP 1604 may use the first transmission power when AP 1604 does not use fewer subcarriers than the total number of RU subcarriers, or when AP 1604 uses the first RU size configuration. A second transmission power can be determined as described above by subtracting backoff from the first transmission power. During multi-AP coordinated transmission, AP 1604 may use the second transmission power when AP 1604 does not use fewer subcarriers than the total number of RU subcarriers, when AP 1604 uses the first RU size configuration, or when AP 1604 uses a second RU size configuration different from the first RU size configuration (e.g., a second RU size configuration using a second number of subcarriers less than the first number of subcarriers).

[0167] As described above, AP 1602 can determine the first transmission power based on the beacon report contained in measurement report frame 1914. In an embodiment, the beacon report from STA 1606 may include the RCPI of beacon frame 1912 transmitted by AP 1604. AP 1602 can calculate the first transmission power of AP 1604 as TXP. ref – BO, where TXP ref It is the reference transmission power used to transmit beacon frame 1912, and BO is equal to the RCPI of beacon frame 1912 minus the ARIL at STA 1606 when receiving data frame 1918.

[0168] Figure 20 This is an example 2000 illustrating a multi-AP coordinated transmission procedure according to another embodiment. For example... Figure 20 As shown, Example 2000 also includes the references above. Figure 16 The AP 1602 and 1604 and STA 1606 and 1608 are described.

[0169] like Figure 20As shown, before initiating a multi-AP coordination transmission with AP 1604, AP 1602 can initiate the measurement procedure described above. Specifically, AP 1602 can transmit a measurement request frame 2010 to STA 1606. In Example 2000, the measurement request frame 2010 may contain a beacon request indicating the BSSID of AP 1604's BSS. Thus, the beacon request requests STA 1606 to transmit a beacon report of AP 1604's BSS. In Example 2000, STA 1606 can perform the measurement requested by the beacon request upon hearing beacon frame 2012 from AP 1604. In this example, the measurement requested by the beacon request includes the RCPI and / or RNSI of beacon frame 2012. Specifically, upon receiving beacon frame 2012 and determining that the BSSID indicated in beacon frame 2012 matches the BSSID indicated in the beacon request, STA 1606 can perform the measurement requested in the beacon request on beacon frame 2012. Subsequently, STA 1606 can transmit a measurement report frame 2014 containing the beacon report to AP 1602. In this implementation, the beacon report is carried in the measurement report field of the measurement report element contained in measurement report frame 2014. The measurement report field may have the features described above. Figure 11 The format described in the document.

[0170] After receiving the measurement report frame 2014, AP 1602 can initiate a multi-AP coordination transmission involving AP 1602 and AP 1604. In Example 2000, after receiving the measurement report frame 2014, AP 1602 transmits a trigger frame 2016 to AP 1604 to initiate the multi-AP coordination transmission. The trigger frame 2016 may contain a RU for AP 1604 to perform the multi-AP coordination transmission. The trigger frame 2016 may also indicate the duration of the multi-AP coordination transmission.

[0171] After AP 1602 transmits trigger frame 2016, APs 1602 and 1604 can transmit corresponding data frames 2018 and 2020 for multi-AP coordinated transmission. In an implementation, data frames 2018 and 2020 can be transmitted one SIFS after trigger frame 2016. Figure 20 As shown, data frames 2018 and 2020 can be transmitted simultaneously and can overlap with each other during the duration of multi-AP coordinated transmission.

[0172] In an embodiment, trigger frame 2016 may indicate a transmission scheme for multi-AP coordinated transmission. The transmission scheme may be, for example, one of CSR, CBF, CTDMA, or COFDMA. In one embodiment, AP 1604 may determine, based on the indicated transmission scheme, whether a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 2016 is permitted during multi-AP coordinated transmission. AP 1604 may make this determination based on pre-configuration information (e.g., set in the 802.11 standard) or based on information signaled by AP 1602. For example, AP 1602 may indicate in a beacon frame a transmission scheme that allows the use of a smaller number of subcarriers than the total number of subcarriers of the RUs indicated in trigger frame 2016, and a transmission scheme that does not allow the use of a smaller number of subcarriers. In an embodiment, for CSR, the use of subcarriers with a number less than the total number of subcarriers of the RUs indicated in trigger frame 2016 may not be permitted.

[0173] In an embodiment, trigger frame 2016 may indicate a first transmission power (or a first parameter for determining the first transmission power) for AP 1604 to use during multi-AP coordinated transmission. The first transmission power may be determined based on the transmission scheme indicated in trigger frame 2016 and whether the transmission scheme allows the use of fewer subcarriers than the total number of subcarriers of the RU. For example, if the transmission scheme is CSR and the use of fewer subcarriers is not allowed for CSR, AP 1602 may determine the first transmission power based on a frame (e.g., beacon frame 2012) transmitted by AP 1604 using the same number of subcarriers as the total number of subcarriers of the RU indicated in trigger frame 2016.

[0174] Figure 21 An example process 2100 according to an embodiment is shown. Example process 2100 can be executed by a first AP, such as AP1602. Figure 21 As shown, process 2100 may include steps 2102 and 2104. Step 2102 may be optional.

[0175] Step 2102 includes receiving a first frame from the second AP by the first AP, the first frame including a resource element (RU) request for multi-AP coordinated transmission. In an embodiment, the second AP may be an OBSS AP relative to the first AP.

[0176] Step 2104 involves transmitting a second frame from the first AP to the second AP, the second frame indicating whether the second AP is permitted to use a smaller number of subcarriers than the total number of subcarriers of the RUs during multi-AP coordinated transmission. The RUs may be indicated by the second frame. Multi-AP coordinated transmission may include both the first AP and the second AP. For example, multi-AP coordinated transmission may be one of CSR, CBF, CTDMA, or COFDMA.

[0177] In this embodiment, the second frame includes a management frame, such as a beacon frame or a trigger frame. The trigger frame may be a multi-AP trigger frame that initiates multi-AP coordinated transmission.

[0178] In an embodiment, the second frame may also indicate or include a RU for the second AP to use for multi-AP coordinated transmission. The RU may be a shared RU used by both the first and second APs for multi-AP coordinated transmission.

[0179] In one embodiment, the second frame may also indicate or include a first transmission power for the second AP to use for multi-AP coordinated transmission. In another embodiment, the second frame may also indicate or include a first transmission power backoff. The first transmission power can be determined by subtracting the first transmission power backoff from a reference transmission power.

[0180] In another embodiment, the first transmission power or first transmission power backoff may be indicated in a third frame, different from the second frame. For example, the second frame may be a beacon frame, and the third frame may be a trigger frame (e.g., a multi-AP trigger frame). In embodiments, the second and third frames may be aggregated.

[0181] In an embodiment, the second frame indicates that, under the condition that the second AP uses the first transmission power for multi-AP coordinated transmission, the second AP is allowed to use a smaller number of subcarriers than the total number of subcarriers of the RU for transmission during multi-AP coordinated transmission.

[0182] In an embodiment, process 2100 may further include receiving a third frame from the STA by the first AP, the third frame including the received signal strength of a fourth frame received by the STA from the second AP. In an embodiment, the first transmission power is based on the received signal strength of the fourth frame. In an embodiment, the second AP uses a reference transmission power to transmit the fourth frame.

[0183] In another embodiment, the second frame indicates that the second AP is allowed to transmit using fewer subcarriers than the total number of subcarriers of the RU during multi-AP coordinated transmission, provided that the second AP uses the first transmission power for multi-AP coordinated transmission and the fourth frame is transmitted by the second AP using fewer subcarriers than the total number of subcarriers of the RU.

[0184] In an embodiment, if the second AP uses a first number of subcarriers less than the total number of subcarriers of the RU to transmit the fourth frame, the second frame may indicate whether the second AP is allowed to use a second number of subcarriers different from the first number of subcarriers during multi-AP coordinated transmission.

[0185] In an embodiment, if the second frame indicates that the second AP is allowed to use fewer subcarriers than the total number of subcarriers of the RU during multi-AP coordinated transmission, process 2100 may include the first AP downsampling the MCS during multi-AP coordinated transmission.

[0186] In one embodiment, the second frame may also indicate or include a second transmission power for the second AP to use for multi-AP coordinated transmission. In another embodiment, the second frame may also indicate or include a second transmission power backoff. The second transmission power can be determined by subtracting the second transmission power backoff from the reference transmission power.

[0187] In an embodiment, when the second AP does not use a number of subcarriers less than the total number of subcarriers of the RU during multi-AP coordinated transmission, the second AP uses a first transmission power, and when the second AP uses a number of subcarriers less than the total number of subcarriers of the RU during multi-AP coordinated transmission, the second AP uses a second transmission power. In an embodiment, the first transmission power is higher than the second transmission power.

[0188] Figure 22 An example process 2200 according to an embodiment is shown. Example process 2200 can be executed by a first AP, such as AP1604. Figure 22 As shown, process 2200 may include steps 2202 and 2204. Step 2202 may be optional.

[0189] Step 2202 involves transmitting a first frame from the first AP to the second AP, the first frame including a Resource Unit (RU) request for multi-AP coordinated transmission. The second AP may be an OBSS AP relative to the first AP.

[0190] Step 2202 involves the first AP receiving a second frame from the second AP. This second frame includes an indication of whether the first AP is permitted to transmit using a smaller number of subcarriers than the total number of subcarriers for the RUs during multi-AP coordinated transmission. The RUs may be indicated by the second frame. Multi-AP coordinated transmission may include both the first and second APs. For example, multi-AP coordinated transmission may be one of CSR, CBF, CTDMA, or COFDMA.

[0191] In this embodiment, the second frame includes a management frame, such as a beacon frame or a trigger frame. The trigger frame may be a multi-AP trigger frame that initiates multi-AP coordinated transmission.

[0192] In one embodiment, the second frame may also indicate or include a first transmission power for the first AP to use for multi-AP coordinated transmission. In another embodiment, the second frame may also indicate or include a first transmission power backoff. The first transmission power can be determined by subtracting the first transmission power backoff from a reference transmission power.

[0193] In one embodiment, a first transmission power is determined based on the received signal strength of a third frame transmitted by a first AP and received by a STA. The received signal strength of the third frame may include the RSSI, RCPI, or RSNI of the third frame. The STA may be associated with a second AP. In another embodiment, the first AP uses a reference transmission power to transmit the third frame.

[0194] In another embodiment, the first transmission power or first transmission power backoff may be indicated in a fourth frame, different from the second frame. For example, the second frame may be a beacon frame, and the fourth frame may be a trigger frame (e.g., a multi-AP trigger frame). In embodiments, the second and fourth frames may be aggregated.

[0195] In an embodiment, the second frame indicates that, under the condition that the first AP uses the first transmission power for multi-AP coordinated transmission, the first AP is allowed to use a smaller number of subcarriers than the total number of subcarriers of the RU for transmission during multi-AP coordinated transmission.

[0196] In another embodiment, the second frame indicates that the first AP is allowed to transmit using fewer subcarriers than the total number of subcarriers of the RU during multi-AP coordinated transmission, provided that the first AP uses the first transmission power for multi-AP coordinated transmission and the third frame is transmitted by the first AP using fewer subcarriers than the total number of subcarriers of the RU.

[0197] In an embodiment, when the first AP transmits the third frame using the first RU size configuration, the first frame may indicate whether the first AP is allowed to use a second RU size configuration different from the first RU size configuration during multi-AP coordinated transmission.

[0198] In one embodiment, the second frame may also indicate or include a second transmission power for the first AP to use for multi-AP coordinated transmission. In another embodiment, the second frame may also indicate or include a second transmission power backoff. The second transmission power can be determined by subtracting the second transmission power backoff from the reference transmission power.

[0199] In an embodiment, when the first AP does not use a number of subcarriers less than the total number of subcarriers of the RU during multi-AP coordinated transmission, the first AP uses a first transmission power, and when the first AP uses a number of subcarriers less than the total number of subcarriers of the RU during multi-AP coordinated transmission, the first AP uses a second transmission power. In this embodiment, the first transmission power is higher than the second transmission power.

[0200] Figure 23 An example process 2300 according to an embodiment is shown. Example process 2300 can be executed by a first AP, such as AP1604. Figure 23 As shown, process 2300 may include steps 2302 and 2304.

[0201] Step 2304 includes receiving a first frame from a second AP by the first AP. The first frame indicates the RU (Resource Unit) and the transmission scheme for multi-AP coordinated transmission. The second AP may be an OBSS (Obstacle Service) AP relative to the first AP. In embodiments, the first frame may be a management frame, such as a trigger frame. Multi-AP coordinated transmission may include both the first and second APs. For example, multi-AP coordinated transmission may be one of CSR (Concurrent Support Response), CBF (Continuous Feedback), CTDMA (Continuous Cross-Site DMA), or COFDMA (Continuous Cross-Site DMA).

[0202] Step 2304 involves the first AP determining, based on a transmission scheme, whether it is permitted to use fewer subcarriers than the total number of subcarriers in the RU for transmission during multi-AP coordinated transmission. In embodiments, the first AP may make this determination based on pre-configuration information (e.g., as set in the 802.11 standard) or based on information signaled by the second AP. For example, the second AP may indicate in a beacon frame a transmission scheme that allows transmission using fewer subcarriers than the total number of subcarriers in the RU, and a transmission scheme that does not allow transmission using fewer subcarriers than the total number of subcarriers in the RU. In embodiments, for CSR, transmission using fewer subcarriers than the total number of subcarriers in the RU may not be permitted.

[0203] In an embodiment, the first frame may indicate a first transmission power (or a first parameter for determining the first transmission power) for the first AP to use during multi-AP coordinated transmission. The first transmission power may be determined based on the transmission scheme indicated in the first frame and whether the transmission scheme allows transmission using fewer subcarriers than the total number of subcarriers of the RU. For example, if the transmission scheme is CSR and CSR does not allow transmission using fewer subcarriers than the total number of subcarriers of the RU, the first transmission power may be determined by the second AP based on frames transmitted by the first AP using the same number of subcarriers as the total number of subcarriers of the RU.

Claims

1. A method comprising: The first access point (AP) receives a first frame from the second AP, the first frame including a resource element (RU) request for multi-AP coordinated transmission; The first AP transmits a second frame to the second AP, the second frame including: The first resource unit RU is provided by the second AP for the multi-AP coordinated transmission; and The first parameter indicates whether a smaller number of subcarriers than the total number of subcarriers of the first RU are allowed for transmission during the multi-AP coordinated transmission.

2. A method comprising: A first frame is transmitted from the first access point (AP) to the second AP. The first frame indicates whether the second AP is allowed to use fewer subcarriers than the total number of subcarriers in the resource unit (RU) during multi-AP coordinated transmission including the first AP and the second AP.

3. The method of claim 2, further comprising transmitting a second frame by the first AP, the second frame indicating a first transmission power of the second AP for the multi-AP coordinated transmission.

4. The method of claim 3, wherein the second frame indicates a first transmission power backoff BO, and wherein the first transmission power is determined by subtracting the first transmission power BO from a reference transmission power.

5. The method according to any one of claims 3 to 4, wherein the first frame indicates whether the second AP is allowed to use a smaller number of subcarriers than the total number of subcarriers of the RU for transmission during the multi-AP coordinated transmission, provided that the second AP uses the first transmission power for the multi-AP coordinated transmission.

6. The method according to any one of claims 3 to 5, further comprising receiving a third frame by the first AP slave station STA, the third frame including the received signal strength of a fourth frame received by the STA from the second AP, wherein the first transmission power is based on the received signal strength of the fourth frame.

7. The method of claim 6, wherein the second AP uses a reference transmission power to transmit the fourth frame.

8. The method according to any one of claims 6 to 7, wherein the first frame indicates that the second AP is allowed to transmit using a smaller number of subcarriers than the total number of subcarriers of the RU during the multi-AP coordinated transmission, provided that the second AP uses the first transmission power and the fourth frame is transmitted by the second AP using a smaller number of subcarriers than the total number of subcarriers of the RU.

9. The method of any one of claims 6 to 8, wherein the fourth frame is transmitted by the second AP using a first number of subcarriers less than the total number of subcarriers of the RU, and wherein the second frame indicates whether the second AP is permitted to use a second number of subcarriers different from the first number of subcarriers during the multi-AP coordinated transmission.

10. The method of any one of claims 2 to 9, wherein the first frame indicates that the second AP is allowed to use fewer subcarriers than the total number of subcarriers of the RU during the multi-AP coordinated transmission, and the method further includes the first AP down-regulating the modulation and coding scheme (MCS) during the multi-AP coordinated transmission.

11. The method according to any one of claims 3 to 4, wherein the second frame indicates the second transmission power of the second AP for the multi-AP coordinated transmission.

12. The method of claim 11, wherein the second frame indicates a second transmission power BO, and wherein the second transmission power is determined by subtracting the second transmission power BO from a reference transmission power.

13. The method according to any one of claims 11 to 12, wherein during the multi-AP coordinated transmission, the second AP uses the first transmission power when it does not use a number of subcarriers less than the total number of subcarriers of the RU, and uses the second transmission power when it uses a number of subcarriers less than the total number of subcarriers of the RU.

14. The method according to any one of claims 11 to 13, wherein the first transmission power is higher than the second transmission power.

15. The method according to any one of claims 3 to 14, wherein the second frame includes a multi-AP trigger frame.

16. The method according to any one of claims 3 to 15, wherein the second frame further comprises the resource unit RU for the second AP to use for the multi-AP coordinated transmission.

17. The method according to any one of claims 2 to 16, wherein the first frame includes a management frame.

18. The method according to any one of claims 3 to 17, wherein the first frame is aggregated with the second frame.

19. The method according to any one of claims 2 to 18, wherein the multi-AP coordinated transmission comprises: Coordinated space reuse; Coordinated beamforming; Coordinated Time-Domain Multiple Access; or Coordinated orthogonal frequency division multiple access.

20. A method comprising: A first frame is transmitted from the first access point (AP) to the second AP. The first frame includes a resource unit (RU) request for multi-AP coordinated transmission. The first AP receives a second frame from the second AP, the second frame including: A first resource unit RU, which is provided by the first AP for the multi-AP coordinated transmission; and The first parameter indicates whether transmission using a smaller number of subcarriers than the total number of subcarriers in the RU is permitted during the multi-AP coordinated transmission; and The first AP transmits Physical Layer Protocol Data Units (PPDUs) to the station STA using a first number of subcarriers, which is less than the total number of subcarriers of the RU, based on the first parameter.

21. A method comprising: The first access point (AP) receives a first frame from the second AP. The first frame indicates whether the first AP is allowed to use fewer subcarriers than the total number of subcarriers in the resource unit (RU) during multi-AP coordinated transmission including the first AP and the second AP.

22. The method of claim 21, further comprising receiving a second frame from the second AP by the first AP, the second frame indicating a first transmission power of the first AP for the multi-AP coordinated transmission.

23. The method of claim 22, wherein the second frame indicates a first transmission power backoff BO, and wherein the first transmission power is determined by subtracting the first transmission power BO from a reference transmission power.

24. The method of any one of claims 22 to 23, wherein the first frame indicates whether the first AP is allowed to use a smaller number of subcarriers than the total number of subcarriers of the RU for transmission during the multi-AP coordinated transmission, provided that the first AP is using the first transmission power for the multi-AP coordinated transmission.

25. The method according to any one of claims 23 to 24, further comprising the first AP using the reference transmission power to transmit a third frame.

26. The method of claim 25, wherein the first frame indicates that the first AP is allowed to use a smaller number of subcarriers than the total number of subcarriers of the RU during the multi-AP coordinated transmission, provided that the first AP uses the first transmission power and the third frame is transmitted by the first AP using a smaller number of subcarriers than the total number of subcarriers of the RU.

27. The method according to any one of claims 22 to 23, wherein the second frame indicates the second transmission power of the second AP for the multi-AP coordinated transmission.

28. The method of claim 27, wherein the second frame indicates a second transmission power BO, and wherein the second transmission power is determined by subtracting the second transmission power BO from a reference transmission power.

29. The method of any one of claims 27 to 28, wherein the first AP uses the first transmission power when it uses fewer subcarriers than the total number of subcarriers of the RU during the multi-AP coordinated transmission, and uses the second transmission power when it does not use fewer subcarriers than the total number of subcarriers of the RU during the multi-AP coordinated transmission.

30. The method according to any one of claims 27 to 29, wherein the first transmission power is higher than the second transmission power.

31. The method according to any one of claims 22 to 30, wherein the second frame comprises a multi-AP trigger frame.

32. The method according to any one of claims 22 to 31, wherein the second frame further includes the resource unit RU for the first AP to use for the multi-AP coordinated transmission.

33. The method according to any one of claims 21 to 32, wherein the first frame includes a management frame.

34. The method according to any one of claims 22 to 33, wherein the first frame is aggregated with the second frame.

35. The method according to any one of claims 21 to 34, wherein the multi-AP coordinated transmission comprises: Coordinated space reuse; Coordinated beamforming; Coordinated Time-Domain Multiple Access; or Coordinated orthogonal frequency division multiple access.

36. A method comprising: The first access point (AP) receives the first frame from the second AP, and the first frame indicates: Resource unit RU, which is used by the first AP for multi-AP coordinated transmission; and A transmission scheme for coordinating transmission across multiple APs; as well as The first AP determines, based on the transmission scheme, whether it is allowed to use fewer subcarriers than the total number of subcarriers of the RU for transmission during the multi-AP coordinated transmission.

37. The method of claim 36, wherein the transmission scheme includes coordinated spatial multiplexing.

38. The method according to any one of claims 36 to 37, wherein if the transmission scheme includes coordinated spatial multiplexing, the first AP is not allowed to use fewer subcarriers than the total number of subcarriers of the RU during the multi-AP coordinated transmission.

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