Multiple access point coordination per TXOP frame sequence with post feedback scheduling

Abstract

Embodiments of the present disclosure relate to multiple access point coordination per TXOP frame sequence with post feedback scheduling. At least one aspect of the technical solution may relate to a system. The system may include a first access point (AP) that may be configured to transmit a first message for initiating a transmission opportunity (TXOP) to a second AP capable of participating in coordinated beamforming (CBF) and a first set of candidate stations of the first AP. The second AP may be configured to transmit a second message to the first AP and a second set of candidate stations identified as a second AP participating in the TXOP. The second AP may be configured to transmit a third message with a CBF response to the first AP. The first AP may be configured to transmit a fourth message with a CBF trigger to a second AP, which may include information about a preamble of a CBF transmission communicated during the TXOP.

Description

[0001] Cross - reference to related patent applications

[0002] This application claims the benefit and priority of U.S. Provisional Application No. 63 / 689,021, filed on Aug. 30, 2024, and claims the benefit and priority of Indian Provisional Application No. 202421002187, filed on Jan. 11, 2024. The entire contents of the two applications are incorporated herein by reference. Technical Field

[0003] The present disclosure generally relates to systems and methods for wireless communication between an access point and a wireless communication device, including (but not limited to) communication that reduces interference to unintended communication devices. Background Art

[0004] An access point (AP) (e.g., a Wi-Fi router) can facilitate wireless communication with any number of client wireless communication devices (also referred to as clients, stations, or STAs, e.g., smartphones, tablet computers, computers that can be within the wireless communication range of the AP). Sometimes, a client can experience interference caused by the AP (e.g., within the same or a different wireless communication network) transmitting data to other clients or STAs. Such interference can be exacerbated when network density increases and transmission opportunities decrease. Summary of the Invention

[0005] The technical solutions of the present disclosure relate to systems and methods for establishing coordinated beamforming (CBF) for each transmission opportunity (TXOP) frame sequence, where CBF transmission scheduling is performed in response to feedback data from participating station devices. When multiple base stations (BSs) or access points (APs) are performing coordinated beamforming to transmit data to user devices or user equipment, the lack of a trigger frame from any AP before the CBF physical protocol data unit (PPDU) poses a challenge in providing an accurate and reliable start time for CBF PPDU transmission. In such cases, one AP can start the CBF PPDU earlier than other APs, resulting in synchronization problems between the APs. Additionally, it becomes more difficult to accurately and efficiently establish CBF communication as the AP cannot consider the varying parameters or availability of all AP and station device participants. Such synchronization problems can lead to timing mismatches, which ultimately result in phase misalignment and reduced beamforming efficiency. The synchronization problems can further lead to different oscillator frequencies at different APs, resulting in phase and amplitude errors. The technical solution can overcome these challenges through systems and methods that synchronize APs by utilizing a CBF-TXOP frame sequence when transmitting CBF PPDUs based on a CBF transmission schedule established in response to data from participating devices.

[0006] At least one aspect of the technical solution may relate to a system. The system may include a first access point (AP), which may be configured, for example, via instructions or data stored in a memory for access and execution by one or more processors of the first AP. The first AP may be configured to transmit a first message for initiating a transmission opportunity (TXOP) to a second AP capable of participating in coordinated beamforming (CBF) and a first group of candidate stations of the first AP. The second AP may be configured to transmit a second message to the first AP and a second group of candidate stations identified as participating in the TXOP of the second AP. In response to the first AP not terminating the CBF TXOP, the second AP may be configured to transmit a third message with a CBF response to the first AP. In response to the second AP indicating participation in CBF in the CBF response, the first AP may be configured to transmit a fourth message with a CBF trigger to the second AP, and the CBF trigger may include information about a preamble of the CBF transmission communicated during the TXOP.

[0007] The information about the preamble may include the content of the preamble for synchronizing the timing of the CBF transmission with at least one of the first AP or the second AP. The content of the preamble may include at least one of information about the start time of the CBF physical protocol data unit (PPDU) of the CBF transmission or information about the frequency offset between the first AP and the second AP. The first message may include an initial control frame (ICF) for the first group of candidate stations. The ICF may include at least one of a multi-user request to send (MU-RTS) or a buffer status report poll (BSRP) and information about at least one of enhanced multi-link single radio (EMLSR), in-device coexistence (IDC), or power saving mode.

[0008] The first AP may include padding in the first message to provide additional time for the first group of candidate stations and the second AP to process the first message. The first group of candidate stations may be configured to transmit one or more messages in response to the first message, and the one or more messages are configured in one of the format of a triggered physical protocol data unit (TB-PPDU) or a non-high throughput duplicate (non-HT DUP) format. The first group of candidate stations may be configured to transmit one or more initial control responses (ICRs) in response to the initial control frame (ICF) from the first AP, and the one or more ICRs indicate at least one of the availability of participating in CBF during the TXOP or the duration of data transmission for in-device coexistence (IDC) configuration.

[0009] The second AP may be configured to indicate to the first AP and a second group of candidate stations via a second message that the second AP will participate in CBF during the TXOP. One or more stations in the second group of candidate stations are configured to transmit one or more responses in response to the indication by the second AP via the second message, the one or more responses indicating at least one of the availability of participating in CBF during the TXOP or the duration of data transmission for in-device coexistence (IDC) configuration.

[0010] The second AP may be configured to transmit a third message to the first AP. The third message may include a CBF response having information about the second group of candidate stations and an adjustment to a previous transmitted CBF response to the first message from the first AP. The adjustment is generated based on feedback from the second group of candidate stations. The first AP may be configured to include an adjustment to a previously transmitted CBF request by the first AP in the CBF trigger. The adjustment is determined based on feedback from stations in the first group of candidate stations regarding the availability of participating in CBF during the TXOP. The first AP may be configured to include an indication in the CBF trigger for the second AP to terminate the CBF TXOP.

[0011] At least one aspect of the technical solution relates to a system. The system may include a first access point (AP) that may be configured, for example, via instructions or data stored in a memory for access and execution by one or more processors of the first AP. The first AP may be configured to transmit a first message for initiating a transmission opportunity (TXOP) with an embedded CBF request to a second AP capable of participating in coordinated beamforming (CBF) and a first group of candidate stations of the first AP. The second AP may be configured to transmit a second message with an embedded first CBF response to a second group of candidate stations identified as participating in the TXOP in response to the CBF request. The second AP may be configured to transmit a third message with a second CBF response to the first AP in response to the first AP not terminating the CBF TXOP, the second CBF response including information about the second group of candidate stations. The first AP may be configured to transmit a fourth message with a CBF trigger to the second AP in response to the second AP indicating participation in CBF, the CBF trigger including information for synchronizing CBF transmissions during the TXOP.

[0012] The first AP is configured to include in a first message a list of identifiers of a first set of candidate stations and information about a suggested start time for a CBF transmission, and the second AP is configured to include in a second message a response to the suggested start time for the CBF transmission. The response from the second AP to the suggested start time for the CBF transmission includes an acknowledgement of the suggested start time and a list of identifiers of a second set of candidate stations for the first AP to determine a schedule for the CBF transmission. The first AP is configured to include in the CBF trigger information about the timing of the CBF transmission and information about an adjustment to the first CBF response based on feedback from the first set of candidate stations and information about an adjustment to the second CBF response based on feedback from the second set of candidate stations. The first AP and the second AP are configured to include padding to provide additional time for the first set of candidate stations or the second set of candidate stations to generate information about availability to participate in CBF during a TXOP.

[0013] Aspects of the technical solution relate to a method. The method may include transmitting, by a first access point (AP), a first message for initiating a transmission opportunity (TXOP) to a second AP capable of participating in coordinated beamforming (CBF) and a first set of candidate stations of the first AP. The method may include transmitting, by the second AP, a second message to the first AP and a second set of candidate stations of the second AP identified as participating in the TXOP. The method may include transmitting, by the second AP, a third message with a CBF response to the first AP in response to the first AP not terminating the CBF TXOP. The method may include transmitting, by the first AP, a fourth message with a CBF trigger to the second AP in response to the second AP indicating participation in CBF in the CBF response, the CBF trigger including information about a preamble of the CBF transmission communicated during the TXOP.

[0014] The method may include the first AP including, in the information about the preamble, the content of the preamble for synchronizing the timing of the CBF transmission with at least one of the first AP or the second AP. The content of the preamble includes at least one of information about a start time of a CBF physical protocol data unit (PPDU) of the CBF transmission or information about a frequency offset between the first AP and the second AP. The method may include the first AP including an initial control frame (ICF) of the first set of candidate stations in the first message. The ICF may include at least one of a multi-user request to send (MU-RTS) or a buffer status report poll (BSRP) and information about at least one of enhanced multi-link single radio (EMLSR), in-device coexistence (IDC), or power saving mode.

[0015] The method may include the first AP including padding in a first message to provide additional time for the first set of candidate stations and the second AP to process the first message. The method may include the first set of candidate stations transmitting one or more messages in response to the first message. The one or more messages may be configured in one of a format based on a Triggered Physical Protocol Data Unit (TB-PPDU) or a Non-High Throughput Duplicate (Non-HT DUP) format. The method may include the first set of candidate stations transmitting one or more Initial Control Responses (ICRs) in response to an Initial Control Frame (ICF) from the first AP. The one or more ICRs indicate at least one of the availability to participate in CBF during a TXOP or the duration of data transmission for In-Device Coexistence (IDC) configuration.

[0016] The method may include the second AP transmitting, via a second message, an indication to the first AP that the second AP will participate in CBF during a TXOP for a second set of candidate stations. The method may include one or more stations among the second set of candidate stations transmitting one or more responses in response to the indication by the second AP via the second message, the one or more responses indicating at least one of the availability to participate in CBF during a TXOP or the duration of data transmission for In-Device Coexistence (IDC) configuration. The method may include the second AP transmitting a third message to the first AP. The third message includes a CBF response having information about the second set of candidate stations and an adjustment to a previous transmitted CBF response to the first message from the first AP. The adjustment is generated based on feedback from the second set of candidate stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various objects, aspects, features, and advantages of the present disclosure will become more apparent and better understood by reference to the detailed description taken in conjunction with the accompanying drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numerals generally denote identical, functionally similar, and / or structurally similar elements.

[0018] Figure 1A is a block diagram depicting a network environment including one or more access points communicating with one or more devices or stations according to some embodiments.

[0019] Figure 1B and 1C is a block diagram depicting a computing device that may be used in conjunction with the methods and systems described herein according to some embodiments.

[0020] Figure 2 illustrates an example system for coordinated partial rank zeroing in a multi-AP and multi-STA environment according to some embodiments.

[0021] Figure 3 is an example plot of the signal space of STA transmissions in the context of single-AP partial rank zeroing.

[0022] Figure 4 It is an example drawing of two signal spaces transmitted by two STAs in the context where the 2AP coordination partial rank is zeroed.

[0023] Figure 5 It is an example block diagram of a system for multi - access point coordination for each CBF TXOP frame sequence.

[0024] Figure 6 It is an example flowchart of a method for multi - access point coordination for each CBF TXOP frame sequence.

[0025] Details of various embodiments of the method and system are set forth in the accompanying drawings and the description below. Detailed Description

[0026] The following IEEE standards (including any draft versions of these standards) are hereby incorporated by reference in their entirety and made part of this disclosure for all purposes: Wi - Fi Alliance standards and IEEE 802.11 standards, including (but not limited to) IEEE 802.11a TM 、IEEE 802.11b TM 、IEEE 802.11g TM 、IEEE P802.11n TM ;IEEE P802.11ac TM ;and IEEE P802.11be TM Draft version D3.0 standard. Although aspects of these standards may be referenced in this disclosure, this disclosure is in no way limited by these standards.

[0027] For the purpose of reading the description of the various embodiments below, the following description of the sections of the specification and their corresponding content may be helpful:

[0028] - Section A describes the network environment and computing environment that can be used to practice the embodiments described herein;

[0029] - Section B describes variants of multi - access point coordination for each CBF TXOP frame sequence with station feedback scheduling; and

[0030] A. Computing and network environment

[0031] Before discussing the specific embodiments of the solution, it may be helpful to describe aspects of the operating environment and associated system components (e.g., hardware elements) in the context of the methods and systems described herein.

[0032] Reference Figure 1A, depicting an embodiment of a network environment. Briefly summarized, the network environment includes a wireless communication system, the wireless communication system including one or more access points (APs) or network devices 205, one or more stations (also referred to as STAs) or wireless communication devices 240, and network hardware components or network hardware 192. The wireless communication device or STA 240 may include, for example, a laptop computer, a tablet computer, a personal computer, and / or a cellular phone device. Reference may be made to Figure 1B and 1C for a more detailed description of the details of the embodiments of each station or wireless communication device 240 and the AP or network device 205 (such as its internal hardware and software configuration). In one embodiment, the network environment may be an ad hoc network environment, an infrastructure wireless network environment, a subnet environment, etc. The network device 205 or AP may be operatively coupled to the network hardware 192 via a local area network connection. The network device 205 or AP may include, for example, a Wi-Fi device providing a WLAN, or a 5G base station for providing a cellular network. The network hardware 192, which may include routers, gateways, switches, bridges, modems, system controllers, appliances, etc., may provide a local area network connection for the communication system. Each of the network devices 205 or APs may have an associated antenna or antenna array to communicate with the wireless communication devices in its area. The wireless communication device 240 may register with a specific network device 205 or AP to receive services from the communication system (e.g., via a SU-MIMO or MU-MIMO configuration). For direct connections (e.g., peer-to-peer communication), some wireless communication devices may communicate directly via an assigned channel and communication protocol. Some of the wireless communication devices 240 may be mobile or relatively stationary with respect to the network device 205 or AP.

[0033] In some embodiments, network device 205 or AP includes a device or module (including a combination of hardware and software) that allows wireless communication device 240 to connect to a wired network using Wi-Fi (Wireless Fidelity) or other standards. Network device 205 or AP is sometimes referred to as a wireless access point (WAP). Network device 205 or AP can be implemented (e.g., configured, designed, and / or constructed) to operate in a wireless local area network (WLAN). In some embodiments, network device 205 or AP can be connected to a router as a stand-alone device (e.g., via a wired network). In other embodiments, network device 205 or AP can be a component of a router. Network device 205 or AP can provide access to the network for multiple devices. Network device 205 or AP can be connected to a wired Ethernet connection, for example, and use a radio frequency link to provide a wireless connection for other devices 240 to utilize the wired connection. Network device 205 or AP can be implemented to support standards for sending and receiving data using one or more radio frequencies. Those standards and the frequencies they use can be defined by the IEEE (e.g., the IEEE 802.11 standard). Network device 205 or AP can be configured and / or used to support a public Internet hotspot and / or to extend the range of a Wi-Fi signal on a network.

[0034] In some embodiments, access point or network device 205 can be used in a wireless network (e.g., IEEE 802.11, Bluetooth, ZigBee, any other type of radio-frequency-based network protocol, and / or variants thereof) (e.g., within a home, in a vehicle, or within a building). Each of the wireless communication devices 240 can include a built-in radio and / or be coupled to a radio. Such wireless communication devices 240 and / or access point or network device 205 can operate in accordance with various aspects of the present disclosure presented herein to enhance performance, reduce cost and / or size, and / or enhance broadband applications. Each wireless communication device 240 can have the ability to act as a client node seeking access to resources (e.g., data and connections to networked nodes such as servers) via one or more access points or network devices 205.

[0035] The network connection can include any type and / or form of network and can include any of the following: a point-to-point network, a broadcast network, a telecommunications network, a data communication network, a computer network. The network topology can be a bus, star, or ring network topology. The network can be any such network topology known to those of ordinary skill in the art that is capable of supporting the operations described herein. In some embodiments, different types of data can be transmitted via different protocols. In other embodiments, the same type of data can be transmitted via different protocols.

[0036] The communication device 240 and the access point or network device 205 can be deployed as any type and form of computing device and / or executed on any type and form of computing device, such as a computer, network device, or appliance capable of communicating on any type and form of network and performing the operations described herein. Figure 1B and 1C FIG. depicts a block diagram of a computing device 100 that can be used to practice embodiments of the wireless communication device 240 or the network device 205. As Figure 1B and 1C shown, each computing device 100 includes a processor 121 (e.g., a central processing unit) and a main memory unit 122. As Figure 1B shown, the computing device 100 may include a storage device 128, a mounting device 116, a network interface 118, an I / O controller 123, display devices 124a to 124n, a keyboard 126, and a pointing device 127 (e.g., a mouse). The storage device 128 may include an operating system and / or software. As Figure 1C shown, each computing device 100 may also include additional optional elements that communicate with the central processing unit or processor 121, such as a memory port 103, a bridge 170, one or more input / output devices 130a to 130n, and a cache memory 140.

[0037] The central processing unit or processor 121 is any logic circuitry that responds to and processes instructions fetched from the main memory unit 122. In many embodiments, the central processing unit or processor 121 is provided by a microprocessor unit, such as: a microprocessor unit manufactured by Intel Corporation of Santa Clara, California; a microprocessor unit manufactured by International Business Machines of White Plains, New York; or a microprocessor unit manufactured by Advanced Micro Devices of Sunnyvale, California. The computing device 100 can be based on any of these processors or any other processor capable of operating as described herein.

[0038] The main memory unit 122 may be one or more memory chips capable of storing data and allowing any storage location to be directly accessed by the microprocessor or processor 121, such as any type or variant of static random access memory (SRAM), dynamic random access memory (DRAM), ferroelectric RAM (FRAM), NAND flash memory, NOR flash memory, and solid state drives (SSD). The main memory unit 122 may be based on any of the above memory chips, or any other available memory chip capable of operating as described herein. In Figure 1B the illustrated embodiment, the processor 121 communicates with the main memory unit 122 via a system bus 150 (described in more detail below). Figure 1C An embodiment of the computing device 100 is depicted, where the processor communicates directly with the main memory unit 122 via a memory port 103. For example, in Figure 1C this case, the main memory unit 122 may be DRDRAM.

[0039] Figure 1C An embodiment is depicted where the main processor 121 communicates directly with the cache memory 140 via a secondary bus (sometimes referred to as a backside bus). In other embodiments, the main processor 121 uses the system bus 150 to communicate with the cache memory 140. The cache memory 140 typically has a faster response time than the main memory unit 122 and is provided by, for example, SRAM, BSRAM, or EDRAM. In Figure 1C the illustrated embodiment, the processor 121 communicates with various I / O devices 130 via a local system bus 150. Various buses can be used to connect the central processing unit or processor 121 to any of the I / O devices 130, such as, for example, the VESA VL bus, ISA bus, EISA bus, Micro Channel Architecture (MCA) bus, PCI bus, PCI-X bus, PCI-Express bus, or NuBus. For embodiments where the I / O device is a video display 124, the processor 121 may use an Advanced Graphics Port (AGP) to communicate with the display 124. Figure 1C An embodiment of a computer or computer system 100 is depicted where the main processor 121 may communicate directly with the I / O device 130b, for example, via HYPERTRANSPORT, RAPIDIO, or INFINIBAND communication technologies. Figure 1C An embodiment is also depicted where a hybrid of local bus and direct communication is used: the processor 121 uses a local interconnect bus to communicate with the I / O device 130a while communicating directly with the I / O device 130b.

[0040] A variety of I / O devices 130a to 130n may be present in the computing device 100. Input devices include keyboards, mice, trackpads, trackballs, microphones, dials, touchpads, touchscreens, and graphics tablets. Output devices include video displays, speakers, inkjet printers, laser printers, projectors, and dye-sublimation printers. As Figure 1B shown, the I / O devices may be controlled by an I / O controller 123. The I / O controller may control one or more I / O devices, such as the keyboard 126 and the pointing device 127, such as a mouse or an optical pen. In addition, the I / O devices may also provide storage and / or installation media for the computing device 100. In still other embodiments, the computing device 100 may provide a USB connection (not shown) to accommodate a handheld USB storage device, such as a USB flash drive series device of a device manufactured by Twintech Industry, Inc. of Los Alamitos, California.

[0041] Referring again to Figure 1B , the computing device 100 may support any suitable installation device 116, such as a disk drive, a CD-ROM drive, a CD-R / RW drive, a DVD-ROM drive, a flash drive, tape drives of various formats, a USB device, a hard disk drive, a network interface, or any other device suitable for installing software and programs. The computing device 100 may further include a storage device, such as one or more hard disk drives or redundant arrays of independent disks, for storing an operating system and other related software and for storing application software programs (e.g., any program or software 120 for implementing (e.g., configured and / or designed for) the systems and methods described herein). Optionally, any of the installation devices 116 may also be used as a storage device. In addition, the operating system and software may run from a bootable medium.

[0042] In addition, computing device 100 may include a network interface 118 to interface to a network via various connections, including (but not limited to) standard telephone lines, LAN or WAN links (such as 802.11, T1, T3, 56 kb, X.25, SNA, DECNET), broadband connections (such as ISDN, frame relay, ATM, gigabit Ethernet, Ethernet-over-SONET), wireless connections, or some combination of any or all of the above connections. Various communication protocols (e.g., TCP / IP, IPX, SPX, NetBIOS, Ethernet, ARCNET, SONET, SDH, Fiber Distributed Data Interface (FDDI), RS232, IEEE 802.11, IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, IEEE 802.11ac, IEEE 802.11ad, CDMA, GSM, WiMax, and direct asynchronous connection) may be used to establish the connection. In one embodiment, computing device 100 communicates with other computing devices 100' via any type and / or form of gateway or tunneling protocol (such as Secure Sockets Layer (SSL) or Transport Layer Security (TLS)). Network interface 118 may include a built-in network adapter, network interface card, PCMCIA network card, card bus network adapter, wireless network adapter, USB network adapter, modem, or any other device suitable for interfacing computing device 100 to any type of network capable of communicating and performing the operations described herein.

[0043] In some embodiments, computing device 100 may include or be coupled to one or more display devices 124a through 124n. Accordingly, any one of I / O devices 130a through 130n and / or I / O controller 123 may include any type and / or form of suitable hardware, software, or a combination of hardware and software to support, enable, or provide the connection and use of (a) display device(s) 124a through 124n by computing device 100. For example, computing device 100 may include any type and / or form of video adapter, video card, driver, and / or library to interface, communicate with, connect to, or otherwise use (a) display device(s) 124a through 124n. In one embodiment, the video adapter may include multiple connectors to interface to (a) display device(s) 124a through 124n. In other embodiments, computing device 100 may include multiple video adapters, where each video adapter is connected to (a) display device(s) 124a through 124n. In some embodiments, any portion of the operating system of computing device 100 may be configured to use multiple display devices 124a through 124n. In additional embodiments, I / O device 130 may be a bridge between system bus 150 and an external communication bus such as a USB bus, Apple Desktop bus, RS-232 serial connection, SCSI bus, FireWire bus, FireWire 800 bus, Ethernet bus, AppleTalk bus, Gigabit Ethernet bus, Asynchronous Transfer Mode bus, FibreChannel bus, Fibre bus, Serial Attached Small Computer System Interface bus, USB connection, or HDMI bus.

[0044] Figure 1B and 1CThe computing device 100 of the type depicted may operate under the control of an operating system that controls the scheduling of tasks and access to system resources. The computing device 100 may run any operating system, such as any version of the MICROSOFT WINDOWS operating system, different versions of Unix and Linux operating systems, any version of MAC OS for Macintosh computers, any embedded operating system, any real-time operating system, any open-source operating system, any proprietary operating system, any operating system for mobile computing devices, or any other operating system capable of running on a computing device and performing the operations described herein. Exemplary operating systems include, but are not limited to: Android, produced by Google Inc.; WINDOWS 7, 8, and 10, produced by Microsoft Corporation of Redmond, Washington; MAC OS, produced by Apple Computer of Cupertino, California; WebOS, produced by Research In Motion (RIM); OS / 2, produced by International Business Machines of Armonk, New York; and Linux, a freely available operating system released by Caldera of Salt Lake City, Utah, or any type and / or form of Unix operating system and other operating systems.

[0045] The computer system or computing device 100 may be any workstation, telephone, desktop computer, laptop or notebook computer, server, handheld computer, mobile phone or other portable telecommunications device, media playback device, gaming system, mobile computing device, or any other type and / or form of computing, telecommunications, or media device capable of communicating. In some embodiments, the computing device 100 may have different processors, operating systems, and input devices consistent with the device. For example, in one embodiment, the computing device 100 is a smartphone, mobile device, tablet computer, or personal digital assistant. Additionally, the computing device 100 may be any workstation, desktop computer, laptop or notebook computer, server, handheld computer, mobile phone, any other computer, or other form of computing or telecommunications device capable of communicating and having sufficient processor power and memory capacity to perform the operations described herein.

[0046] In the context of the systems and methods disclosed herein, aspects of the operating environments and components described above will become apparent.

[0047] When an AP transmits data to a specific intended recipient STA within its own basic service set (BSS), other STAs within the same or an adjacent BSS (e.g., other WLANs) can be within the range of the transmitting AP and experience interference. Interference can include any undesired interruption or degradation of a signal, communication, or system caused by an external signal, noise, or other factor that is present during the intended transmission or reception of interfering information. Interference can include an unwanted signal interruption caused by the transmission from one access point (AP), affecting the communication between another AP and its associated station (STA). The CBF can mitigate such interference by adjusting the transmission mode to minimize signal overlap with unintended STA recipients. For example, when transmissions to different STAs occur simultaneously on the same channel, interference caused by the transmissions can be difficult to resolve because the information from one or more of the transmissions can be unknown, and the relationship between the transmissions can be unknown. Such interference can result in latency, delay, or network packet loss, increase processing power, and thus increase power consumption, reduce the optimization of beamforming networks, make data transmission within such networks more difficult, and have an adverse impact on the user experience.

[0048] The technical solution of the present disclosure overcomes these challenges by facilitating multi-AP coordinated beamforming (CBF) for each transmission opportunity (TXOP) frame sequence. CBF can include any technique or method in which multiple APs cooperatively adjust their beamforming patterns to deliver their signals or transmissions to the intended station while minimizing or eliminating interference from such signals or transmissions at unintended stations. For example, APs from different BSSs (e.g., WLANs) can use the CBF TXOP frame sequence to configure their transmissions to be sent along a vector where interference from these APs is minimized at the unintended receiving STA, client, or user device. The technical solution can include a client device (STA) that receives data streams or vectors from the APs of its corresponding network. The network (e.g., the WLAN of a particular AP) can include one or more basic service sets (BSSs) that have an AP and one or more STAs configured for wireless communication via the same AP (e.g., through the local WLAN configured to the AP). Since an AP can transmit any number of data streams to any number of STAs within its BSS, there can be synchronization of the APs when initiating data streams, resulting in phase misalignment that reduces beamforming efficiency. The technical solution of the present disclosure can utilize various messages to convey all information (e.g., preamble content) associated with CBF PPDU transmission to the corresponding STAs of each AP. Thus, the technical solution of this solution allows multiple APs to communicate at the same time and frequency (e.g., transmit simultaneously on the same channel), while avoiding interference, thereby increasing the throughput of the transmission, reducing latency, and minimizing spectrum usage to avoid interference.

[0049] The technical solution of the present disclosure can include a system and method for multi-AP CBF TXOP frame sequences. The system and method can use nulling to initially reduce interference between the AP and the STA. Nulling can include one of the candidate features being considered for the next-generation Wi-Fi standard (UHR, 11bn). Nulling can include any technique in which the AP minimizes the interference experienced by the STA by reducing the strength or power of unwanted signals from other sources. Nulling can include a technique in which the system can combine one signal with another signal to create a null value (e.g., cancel the original signal). Nulling can be utilized or included to minimize the AP interference seen by the STA due to the AP's transmissions to other STAs.

[0050] A CBF TXOP can be a time interval or time window that provides at least one AP access for uninterrupted data transmission. The CBF TXOP duration can be specified by physical layer (PHY) or media access control (MAC) layer parameters. By utilizing the CBF TXOP, the AP can minimize (e.g., reduce to below an acceptable threshold) synchronization and timing issues. For example, the CBF TXOP frame sequence can include techniques to minimize interference by improving the synchronization of CBF PPDU transmissions. For example, if an AP attempts to transmit a CBF PPDU, the AP can transmit a message indicating information (e.g., MCS / Nss per STA, duration, preamble content, etc.) to other APs to align the phase of each AP before the CBF PPDU transmission. This solution can provide a mechanism or process to coordinate each AP to minimize interference at the STA while improving the timing of CBF PPDU transmissions at each AP.

[0051] Now refer to Figure 2 , an example of a system 200 for implementing coordinated nulling for multi-AP transmission is described. The system 200 can include one or more access points (APs) 205 (e.g., Wi-Fi routers) that provide transmissions to stations or STAs 240 within their BSS 250. The AP 205 can also have a wireless transmission range 255 that can include STAs 240 outside of its BSS (e.g., STAs that are not configured to the corresponding AP's WLAN but are still capable of receiving transmissions or interference from these APs).

[0052] Figure 2It may include a first AP 205 and a second AP 205. The first AP 205 has a first BSS 250 including a first station 240 and a third station 240, and the second AP 205 has a second BSS 250 including a second station 240 and a fourth station 240. Each of the first and second APs 205 may include one or more coordinators 210, a communication controller 215, a nulling function 220, an antenna 225, and a spatial stream 230. Each STA 240 (e.g., the first, second, third, and fourth stations 240 in the system 200) may include one or more antennas 225, a communication controller 215, a spatial stream function 235, and a spatial stream 230. In addition to the STAs 240 within its own BSS 250, each of the APs 205 may also have a wireless signal range 255, which may cover or include the STAs 240 within its own BSS 250 and the STAs 240 outside its BSS 250. For example, in addition to the first and third STAs 240, the first range 255 of the first AP 205 may also include the second STA 240 (e.g., from the BSS of the second AP 205). Similarly, in addition to the second and fourth STAs 240, the second AP 205 may also have a second signal range 255, which may include the first STA 240 (e.g., from the BSS of the first AP 205).

[0053] Figure 2 An environment can be described in which the AP 205 can coordinate its transmissions according to its pre-negotiated and configured partial rank nulling. For example, the system 200 can be used to provide single-AP partial rank nulling (e.g., nulling a part of the interference to non-receiving STAs within the BSS of the transmitting AP) and multi-AP partial rank nulling (e.g., nulling a part of the interference to non-receiving STAs within the same or different BSSs relative to the transmitting AP).

[0054] The AP 205 can include any combination of hardware and software that allows a wireless communication device (e.g., STA 240) to wirelessly connect to a wired network or the World Wide Web or the Internet. The AP 205 can include any combination of hardware and software for facilitating wireless communication within the WLAN of the AP that includes any STA 240 within its BSS 250. The AP 205 can include one or more communication devices (e.g., Wi-Fi router, switch, Bluetooth hub, cellular network base station), and can utilize any wireless communication protocol or standard (e.g., 802.11) for wireless communication.

[0055] AP 205 and STA 240 can be configured for wireless communication in a wireless communication network, such as a LAN, WAN, or cellular network. For example, each AP 205 can include, be associated with, be coupled to, provide, or facilitate a communication network, such as a WLAN of Wi-Fi, for any client or station 240 in its own basic service set (BSS).

[0056] BSS250 is a term used to identify a collection of stations (e.g., devices) associated with the same wireless access point within a WLAN. For example, a BSS can identify a set or collection of one or more stations and / or one or more APs that communicate together within a wireless network. BSS250 can include one or more APs within a specific coverage area (e.g., range 255) and client devices (e.g., STA 240) coupled to the APs. BSS250 can provide infrastructure for an AP 205 to provide network communication to STA 240 within its frequency coverage area. Within BSS250, an AP 205 can manage data distribution to various connected devices (e.g., STA 240), facilitate the implementation of security protocols or functions, and roam as STA 240 may move into and out of its coverage area (e.g., range 255). Range 255 can include an area where a signal from AP 205 can reach a receiving STA 240. Range 255 can include a STA 240 within the BSS250 of a given AP205 or a STA 240 that is part of the BSS250 of another AP 205. For example, a first STA 240 that is part of the first BSS250 of a first AP 205 but is also within the second range 255 of a second AP 205 that serves the second and fourth STA 240 of a second BSS250.

[0057] The coordinator 210 can include any combination of hardware and software for coordinating communication between AP 205 and / or STA 240. The coordinator 210 can include functions (e.g., applications, computer code, or programs) that facilitate the coordination of communication (e.g., transmission) between AP 205 and STA 240 or among AP 205. The coordinator 210 can include functions for implementing a coordination phase to identify STA 240s for which interference needs to be fully or partially nulled and for exchanging STA 240 information between AP 205s. The coordinator 210 can include functions for coordinating timing and frequency (e.g., exchanging timing and frequency information (e.g., communication bands or channels) between AP 205s). The coordinator 210 can generate, facilitate, implement, and apply settings or configurations to AP 205 and / or STA 240 to facilitate coordinated partial rank nulling.

[0058] The coordinator 210 may include a precoder function, such as a precoder algorithm for calculating a beamforming vector for each STA 240 to achieve partial rank nulling. The precoder may include a function for calculating a direction or vector for beamforming transmissions to the STA 240. The precoder may include a function for: using information or data related to a direction or vector at which interference at the STA 240 is minimized or reduced to a threshold below an acceptable interference level (e.g., achieving partial rank nulling) to determine a direction or vector for beamforming transmissions to perform partial rank nulling at such STA 240.

[0059] The coordinator 210 may include a function for performing channel sounding on the STA 240. For example, the coordinator 210 may facilitate, indicate, or request each STA to measure one or more MIMO channels of each sounding AP and provide measurement returns to the coordinator 210. When measuring channels of different APs 205, the relative phase offsets across the receive antennas 225 for the STA 240 may be maintained at a constant value. The coordinator 210 may exchange estimates of the MIMO channels of the sounding APs (e.g., via a compressed beamforming report format (CBR) as provided in 802.11, or in Cartesian form) with the STA 240. The coordinator 210 may exchange information on interfering APs 205 (e.g., APs 205 from an external BSS 250), such as when the STA 240 provides a linear transformation of the MIMO channel from the particular interfering AP 205. The linear transformation may be determined using a previously measured MIMO channel between the STA and its own AP 205 (e.g., the AP 205 of the STA's BSS 250). For example, the linear transformation of the MIMO channel may represent a projection onto one or more eigenmodels of the MIMO channel measured between the STA and the AP 205 of its own BSS. For example, if the STA is receiving a particular number of expected spatial streams from its own AP 205 (e.g., the AP 205 from the STA's own BSS 250), then the coordinator 210 may exchange (e.g., receive) a set of directions in which the AP 205 will minimize interference.

[0060] The coordinator 210 may include functionality for facilitating or performing channel sounding for the STAs 240. Channel sounding may include transmitting a signal and, in response, receiving characteristics (such as signal strength, latency, and phase), and then using such received characteristics to determine the quality of the communication channel. The coordinator 210 may transmit one or more null data packets (NDPs) (e.g., individually or jointly with the APs 205 of other BSSs 250). The NDPs may be synchronized in time and / or frequency (e.g., among multiple APs 205 performing simultaneous channel sounding). The number of sounding dimensions in the NDPs may include the total number of antennas across the APs. NDPs transmitted jointly may precede one or more NDP announcement (NDPA) frames. For example, an AP 205 may transmit an NDPA to all the STAs 240 being sounded on behalf of all the APs 205 performing channel sounding. For example, each of the APs 205 may sequentially send an NDPA to its own STAs 240. For example, all the APs 205 may transmit their NDPAs simultaneously but individually in frequency (e.g., via OFDMA), where each AP 205 addresses the STAs 240 within its own BSS 250. For example, the coordinator 210 may provide or facilitate a trigger frame transmitted by the APs 205, based on which all the APs 205 participating in channel sounding may synchronize their carrier frequency offsets (CFOs) and the start time of their coordinated transmissions.

[0061] The communication controller 215 may include any combination of hardware and software for implementing wireless communication between the AP 205 and the STA 240. The communication controller 215 may include functionality for providing and transmitting data (such as spatial streams) to the intended STAs 240. The communication controller 215 may transmit a message to the STAs 240, such as information, data, or a description asking for the direction or vector in which interference is to be minimized at each STA 240. The communication controller 215 may include functionality for configuring the transmission characteristics of the AP 205 to perform and implement the transmission of the spatial streams 230 according to partial rank nulling. For example, the communication controller 215 may configure the antennas 225 and any other settings to facilitate or implement the transmission of the spatial streams 230 according to a particular direction or vector (e.g., as determined by the coordinator 210) to perform partial rank nulling at a particular STA 240. The communication controller 215 may control, manage, and implement the transmission (e.g., communication) according to timing and frequency (such as a selected channel or band) and in the direction or vector in which partial rank nulling is to be performed.

[0062] AP 205 and / or STA 240 may include a communication controller 215 to facilitate wireless communication with each other. The communication controller 215 may include and / or utilize wireless communication interfaces that facilitate communication via standards such as 802.11a / b / g / n / ac / ax, Bluetooth, cellular (e.g., 3G, 4G, 5G), Zigbee, Z-Wave, NFC, and others, such as hardware and software, including transceivers, antennas, RF interfaces, ports, and processing devices. The communication controller 215 may control the reception and transmission of signals, data, or messages to facilitate or implement multi-AP transmission using coordinated partial rank nulling.

[0063] AP 205 may include a nulling function 220 for implementing nulling according to coordinated (e.g., agreed) communication between AP 205s. Partial rank nulling may include any technique or action in array signal processing for suppressing interference from signals in a particular direction while retaining any signals arriving from other directions. For example, partial rank nulling may include manipulating the array response to create nulls or zeros in the radiation pattern of interference from a particular direction. The nulling function 220 may include any combination of hardware and software for reducing or eliminating unwanted signals or interference at a receiver (e.g., STA 240), such as by adjusting the phase and amplitude of incoming signals. The nulling function 220 may include any combination of hardware and software for minimizing or reducing unwanted signals or interference (e.g., to below an acceptable threshold level) (e.g., without completely removing the interference).

[0064] The nulling function 220 may include a function for measuring interference from a particular AP 205 from various receive vectors or directions relative to STA 240. Direction may include any path or route along which a transmitted signal moves, is directed, or points (e.g., as a vector), and may be specified by its position relative to a reference point or object (e.g., an AP and / or STA). The nulling function 220 may identify or use signals (e.g., probe signals) measured from multiple angles, directions, or vectors, and identify the angle, direction, or vector from, along, or at which the interference is lowest or below an acceptable threshold. The nulling function 220 may include or utilize a precoder (e.g., resident within the coordinator 210) to determine the direction or angle along which the interference is lowest or reduced below the threshold.

[0065] AP 205 and station 240 may include an antenna 225. The antenna 225 may include any transmitting or receiving antenna. The antenna 225 may include or be coupled to a communication link and / or transceiver that implements communication, including a chain of circuitry (e.g., amplifiers, filters, analog-to-digital and / or digital-to-analog converters, processors, signal combiners, and other circuitry that facilitates signal transmission or reception).

[0066] AP 205 and station 240 can perform spatial stream 230 communication (e.g., spatial stream M intended for a specific STA 240 by AP 205, or all numbers of spatial streams N transmitted by AP 205). The spatial stream 230 can include any data stream transmitted or received through separate antennas in a MIMO wireless communication system. For example, a spatial stream can be transmitted or received on more than one antenna, and multiple spatial streams can share the same set of antennas. For example, when transmitted on multiple antennas, each spatial stream can use a unique beamforming vector, which can be different from the vectors for other spatial streams transmitted on the same set of antennas. The spatial stream 230 can provide or facilitate improved throughput and reliability by using multiple antennas to create distinct data paths. The spatial stream 230 can be suitable for directional control and transmission with partial rank nulling.

[0067] System 200 can include or use any number of spatial streams 230, including any independent data streams transmitted simultaneously on multiple antennas in a MIMO (multiple input multiple output) system. System 200 can include STA 240, which can be configured to communicate with a wireless network (e.g., the WLAN of BSS250) to receive and transmit data. System 200 can allow STA 240 to simultaneously receive multiple spatial streams 230 via one or more receive antennas 225 (e.g., two receive antennas for each STA 240). Each spatial stream 230 can represent an independent data stream transmitted from AP 205, which can minimize interference in several dimensions / directions. The number of dimensions or directions in which partial rank nulling can reduce interference can be less than the number of spatial streams 230 that STA 240 can receive. For example, if the STA has two receive antennas 225 (e.g., can receive signals in two dimensions or directions), then partial rank nulling can minimize interference along one dimension or direction as seen by STA 240.

[0068] The number of spatial streams 230 that STA 240 can support can vary based on the capabilities of the network and the MIMO configuration. For example, if STA 240 has multiple receive antennas 225 and the network is configured for 2x2 MIMO, then STA 240 can simultaneously receive two spatial streams 230. Each spatial stream 230 can carry independent data, thus effectively increasing the data capacity and improving the overall throughput, data rate, increased system capacity, and / or wireless network reliability.

[0069] Now refer to Figure 3, an example of the plot 300 of the signal space 302 of the transmission received by the STA 240 is an aspect of the technical solution. As shown in the plot 300, a station 240 (e.g., STA1) having a total of K = 2 receive antennas 225 can receive a total number N = 3 spatial data streams 230 transmitted by the AP 205 (AP1). STA1 can be within the BSS 250 of the transmitting AP1 205 and can receive all 3 spatial data streams 230 transmitted by AP1, even though only one of these spatial data streams 230 is intended for STA1.

[0070] For example, AP1 can transmit N = 3 spatial streams 230 to multiple STAs 240 within its BSS 250 via downlink (DL) MU-MIMO. Among the total N = 3 spatial data streams 230 transmitted by AP1, M = 1 stream (e.g., a single spatial data stream 230, where M < N) can be intended for STA1. Although the plot 300 shows the STA1 stream (e.g., the stream intended for STA1) being directed at an angle away from the X-axis, the remaining two spatial data streams 230 (e.g., interfering streams from AP1) are directed along the X-axis. The Y-axis (which is orthogonal or perpendicular to the X-axis) can represent the direction or vector along which transmissions on the signal space 302 of STA1 are nulled or partially nulled. Thus, the STA1 stream (which is at least partially directed along the Y-axis) has interference below a threshold in at least one direction and can therefore be received by STA1. For example, the STA1 stream can have no interference in at least one direction.

[0071] In Figure 3 the example, the receiving station 240 (e.g., STA1) can have any number K of receive antennas 225 such that M < K < N, where M corresponds to the total number of data streams intended for the receiving station 240 and N corresponds to the total number of data streams transmitted by the AP 205 to any number of receivers. In the plot 300 example, N = 3, M = 1, and K = 2. In such a scenario, in order for STA1 240 to be able to decode its own M intended spatial streams 230, AP1 205 can beamform the transmitted spatial streams such that the signal strength from the interfering streams (e.g., the N - M = 2 streams aligned with the X-axis) causes the signal at STA1 to be minimized at STA1 240 in a set of M linearly independent directions. As shown by the STA1 stream, the M intended streams 230 can be recovered by STA1 240 by projecting them away from the X-axis.

[0072] AP1 205 may include a properly configured Long Training Field (LTF) in its transmission such that STA1 240 can estimate both: i) the directions of its M expected streams and ii) M distinct directions in which interference is minimized. The technical solution may include or provide a framework for scenarios in which any number of APs 205 perform partial rank nulling towards any number of STAs 240. For example, when two APs 205 are utilized, before implementing coordinated transmission, the first AP 205 (e.g., AP1) and the second AP 205 (e.g., AP2) may perform coordination (e.g., during a coordination phase), in which messages may be exchanged between AP1 and AP2 to identify each receiving STA for which interference is to be fully or partially nulled. For example, AP 205 may identify an STA 240 that has more receiving antennas than its expected spatial streams (e.g., antenna K = 2, while the received streams N = 10, where only M = 1 is expected for the STA).

[0073] Such identified STAs may include interference that is sufficiently prominent as seen by the OBSS AP to include nulling (e.g., the STA may have an interference signal strength or power above a specific threshold). For example, the threshold may include the background signal noise level, or 2, 3, 4, 5, 10 or greater multiples of the background noise level. For example, the threshold may be defined with reference to other signals, such as the signal strength, amplitude or power of the expected received stream (e.g., 1 / 2, 1 / 3, 1 / 4 or 1 / 8 of the signal strength, amplitude or power of the expected received spatial stream).

[0074] For each STA identified to have its interfering streams partially nulled, AP1 and AP2 may identify a set of linearly independent receiving directions in which interference from the two APs will be minimized. The linearly independent receiving directions may include distinct and uncorrelated paths, directions or channels through which signals may be received by multiple receiving antennas 225. AP1 and AP2 may dynamically change such a set of directions from one coordinated transmission to the next depending on: i) other receiving STAs and ii) the number of spatial streams expected for each STA.

[0075] Once a set of directions is identified, AP1 and AP2 can start coordinated transmissions that are synchronized in both time and frequency. For example, among the total number N1 of spatial streams transmitted from AP1, a subset of M1 spatial streams can be expected to be used for STA1 having a number K1 of receive antennas. The configuration can include the M1 spatial streams expected for STA1, which is less than the number K1 of receive antennas and also less than the total number N1 of spatial streams from AP1 (e.g., M1 < K1 < N1). Similarly, among the N2 streams transmitted from AP2, M2 streams can be expected to be used for STA2 having K2 receive antennas such that M2 < K2 < N2. In such a configuration, both STA1 and STA2 can be selected, determined, or configured such that partial rank nulling is performed on them by AP1 or AP2. AP1 or AP2 can use beamforming for the directions on which partial rank nulling is to be performed to coordinate the transmission of their data streams in time and frequency to reduce interference and allow simultaneous transmissions.

[0076] Now referring to Figure 4 , example plots 402 and 404 illustrate the received signal space 406 of STA1 and the received signal space 408 of STA2, which are the receivers of transmissions where AP1 and AP2 perform coordinated partial rank nulling in a multi-AP transmission example. Figure 4 can correspond to an example in which the present technical solution utilizes two APs 205 (e.g., Figure 2 those illustrated in). The APs 205 can apply appropriate beamforming vectors to their respective spatial streams 230 to transmit the streams at least along the specified directions or vectors as expected to be received by the intended STAs such that the same streams will be partially or completely nulled along the specified directions at the unintended receiving STAs. For example, the beamforming vectors applied to the spatial streams can minimize the interference from both AP1 and AP2 at a set of M1 independent receiving directions at STA1, as pre-agreed during the coordination phase. By projecting the streams onto such determined M1 directions, the M1 expected streams for STA1 can be recovered. For example, this can be similarly applied to STA2, which has a corresponding set of M2 directions. AP1 and AP2 can include appropriately constructed long training fields (LTFs) in the coordinated transmissions such that STA1 and STA2 can estimate both: i) the directions of their respective expected streams and ii) the directions in which the interference from AP1 and AP2 is minimized.

[0077] AP1 and AP2 can each transmit a total number N = 2 spatial streams 230, where only M = 1 spatial stream 230 is expected to be received by the STAs 240 of its own BSS 250 of the corresponding transmitting AP 205, and each receiving STA 240 includes K = 2 receiving antennas 225. For example, for STA1, the remaining one spatial stream from AP1 and the two spatial streams from AP2 can generate interference that will be partially nulled. As illustrated, a total of 3 spatial streams are partially nulled (e.g., aligned with the X-axis or X-direction in Figure 4 ).

[0078] As shown in plot 402, the interfering stream 412 from AP1 and the interfering streams 414 and 416 from AP2 are directed along the X-direction of the STA1 received signal space 406, and minimized or removed along the Y-direction, while the desired stream 410 from AP1 is directed along a different direction (e.g., closer to the Y-direction or more closely aligned with the Y-direction), and thus is not minimized or removed along the Y-axis or Y-direction and is received by STA1. For example, the Y-axis (also referred to as the Y-direction) can be orthogonal or perpendicular to the X-axis (also referred to as the X-direction). For example, when the desired spatial stream has a component greater than a threshold in the Y-direction, the STA1 received signal space allows such a stream to be received at STA1. For example, the threshold can be as high as 5% of the total received signal strength of the desired spatial stream. For example, depending on the design, the threshold can be as high as 5%, 10%, 15%, 20%, 30%, or greater than 30%.

[0079] Similarly, as shown in plot 404, the interfering streams 410 and 412 from AP1 and the interfering stream 416 from AP2 are directed along the X-direction of the STA2 received signal space 408, and their signals are also minimized or removed along the Y-direction, while the desired stream 414 from AP2 is directed along a different direction (e.g., closer to the Y-axis or more closely aligned with the Y-axis), and thus is not minimized or removed along the Y-direction and is received by STA2. In some embodiments, AP1 and AP2 can simultaneously transmit the streams 410, 412, 414, and 416 in the presence and range of STA1 and STA2, and the interference and non-interference of the streams can occur simultaneously. Thus, AP1 and AP2 can simultaneously and in a coordinated manner (e.g., at the same time and frequency) transmit spatial streams to their respective STAs 240, using partial rank nulling to prevent interference to non-desired STAs 240.

[0080] In one example, as part of the coordination phase, the APs 205 (e.g., AP1 and AP2) may exchange information about a precoder algorithm that is used to compute the beamforming vectors for each STA 240 (e.g., STA1 and STA2) to achieve partial rank nulling. For example, as part of the coordination phase, the APs 205 may exchange information, data, or descriptions of the direction vectors where interference will be minimized at the receive antennas 225 of each STA. For example, as part of the coordination phase, a single AP 205 may compute the beamforming vectors for all spatial streams and share these vectors with other participating APs.

[0081] Using the information exchanged during the coordination phase, a receive direction for minimizing interference for each STA 240 may be determined or generated based on or using a policy (e.g., a policy specified in a standard). The choice of policy may be fixed to a "default" implementation, or may be determined based on the capabilities of the APs 205 and / or the STAs 240. For example, for an STA receiving M expected spatial streams from the AP 205 of its own BSS 250, the policy may include interfering with the AP 205 to minimize interference at the receiver of the STA along M directions that correspond to the M strongest eigenmodes of the channel between the STA 240 and its AP 205 (e.g., the AP 205 of the STA's own BSS 250). For example, for an STA receiving M expected spatial streams from the AP of the STA's own BSS, the policy may include interfering with the AP 205 to minimize interference at the receiver of the STA along M directions that correspond to the M strongest eigenmodes of the channel between the STA 240 and the interfering AP 205.

[0082] For example, as part of the coordination phase, AP1 and AP2 may each perform channel sounding on STA1 and STA2. Each STA 240 may measure the MIMO channel from each sounding AP 205 and may provide a response that includes the measurements. When measuring channels from different APs, the relative phase offsets across the receive antennas of the STAs 240 may be maintained at a constant value.

[0083] During the coordination phase, different independent variants and their combinations can be implemented. For example, STA 240 can feedback an estimate of the MIMO channel from a sounding AP in a compressed beamforming report format (CBR) (e.g., one defined in 802.11). For example, STA 240 can feedback an estimate of the MIMO channel from a sounding AP in Cartesian form. For example, for an AP 205 (e.g., an interfering AP) from another BSS 250 different from the BSS 250 of the STA, STA 240 can feedback a linear transformation of the MIMO channel from the AP 205. The linear transformation can be determined by the previously measured MIMO channel between the STA and its own BSS AP. For example, the linear transformation can represent a projection on one or more eigenmodels of the MIMO channel measured between STA 240 and its own BSS AP 205. For example, for a sounding AP 205, if STA 240 is receiving M expected spatial streams from its own BSS AP 205, then STA 240 can feedback M preferred sets of directions, where the corresponding AP can minimize interference.

[0084] As part of the coordination phase, AP 205 (e.g., AP1 and AP2) can jointly perform channel sounding of STA 240. AP 205 can jointly transmit null data packets (NDPs) that can be synchronized in time / frequency. The total number of sounding dimensions in the NDP can be equal to the total number of antennas 225 across AP 205. The jointly transmitted NDP can be preceded by one or more NDP announcements (NDPAs) frames. For example, a single AP 205 can transmit an NDPA on behalf of all APs to the STAs to be sounded across BSS 250. For example, all AP 205 can sequentially transmit their NDPAs, where the NDPA of each AP addresses the STA 240 within its own BSS 250. For example, all AP 205 can simultaneously transmit their NDPAs, but separated in frequency (e.g., via OFDMA), where each AP 205 addresses the STA 240 within its own corresponding BSS 250. The coordinated transmission can be preceded by a trigger frame transmitted by one of the AP 205. Based on the trigger frame, all participating AP 205 can synchronize their carrier frequency offset (CFO) relative to the AP 205 that transmitted the trigger frame and synchronize the start time of their coordinated transmission.

[0085] B. Multi - AP coordination of each CBF TXOP frame sequence with relay feedback scheduling

[0086] The technical solution of the present disclosure may include multi-access coordination for each CBF TXOP frame, where a schedule for CBF communication is established in response to feedback data from participating STAs. For example, when coordinating or synchronizing CBF communication, the technical solution may utilize a system in which an initial control frame (ICF) can be sent by a first (e.g., initiating) AP to a second (e.g., responding) AP and the stations (STAs) of the first AP to initiate a CBF synchronization process. Then, the STAs of the first AP can respond with their initial control responses (ICRs), and the second (e.g., responding) AP can send a CBF response along with its own ICF of the STAs of the second AP. These messages or transmissions allow for the collection of feedback to complete information about the participating STAs, and then the APs can use this information to establish a schedule for CBF communication based on data from the APs and STAs. Such a schedule can then be used for efficient and effective CBF communication during a CBF TXOP, thereby improving the efficiency and reliability of communication between devices.

[0087] Figure 5 FIG. 4 is an example block diagram of a system 500 for multi-access point coordination for each CBF TXOP frame sequence. The example system 500 may incorporate, utilize, or include any features or functions of system 200 or example features 300 and 400, and vice versa. The system 500 may include one or more APs 210 that communicate wirelessly with one or more stations (STAs) 240 and one or more APs 210 via one or more links 560. For example, a first AP 210 may communicate wirelessly with one or more stations (e.g., a first STA 240) via a link 560, and the first STA 240 is in the BSS 250 of the first AP. Additionally, a second AP 205 may communicate wirelessly with one or more stations (e.g., a second STA 240) via a link 560, and the second STA 240 may be in the BSS 250 of the second AP. The first AP 205 and the second AP 205 and any additional APs 205 described herein may communicate wirelessly with each other via one or more links 550 to coordinate CBF between each other and with respect to any station 240 with which they communicate (including the first and second stations 240 or any other station 240 served by either of the APs 205). Although Figure 5 FIG. 4 illustrates two APs 205 and two STAs 240, it should be understood that the systems and methods described herein may be applicable to any number of APs 205 and STAs 240. Each AP 205 (e.g., a first AP 205, a second AP 205) may include at least one coordinated beamforming manager 505 (CBFM 505), at least one station selector 510, and at least one communication controller 215.

[0088] A Coordinated Beamforming Manager (also referred to as CBFM 505) may include hardware and software for establishing, managing, and operating CBF operations. CBF operations may include Channel State Information (CSI) acquisition, CSI exchange, beamforming weight calculation, transmission coordination, and other operations. CBFM 505 operations may include, for example, communication or exchange of messages for synchronizing CBF communications, such as exchange (e.g., sending or receiving) of CBF messages 520, including CBF requests 525, CBF responses 530, Initial Control Frames (ICF) 535, Initial Control Responses (ICR) 540, or CBF triggers 545. For example, the CBFM 505 of the first AP 205 may perform CSI acquisition for the first station 240 and the second AP 205. The CBFM 505 may include at least one CBF synchronizer 515. The CBF synchronizer 515 may synchronize, coordinate, or otherwise align each AP 205 when performing CBF PPDU transmission. The CBF PPDU may correspond to the transmission of a PPDU that employs CBF operations or techniques. The CBF synchronizer 515 may utilize frames and parameters of multiple CBF messages 520.

[0089] The CBF synchronizer 515 may include any combination of hardware and software for synchronizing or negotiating CBF communications. The CBF synchronizer 515 may include computer code, instructions, or data for exchanging communications with other (e.g., remote) APs 205 or stations 240 of the same or different BSSs 250 to, for example, facilitate negotiation or synchronization of the timing or configuration of CBF communications. The CBF synchronizer 515 may include, generate, transmit, or receive one or more CBF messages 520 for communicating with either an AP 205 or a station 240 via a link 560. The CBF messages 520 may include information associated with CBD PPDU transmission of the corresponding AP 205. Each CBF message 520 may correspond to at least one of a CBF request 525, a CBF response 530, an Initial Control Frame 535 (ICF 535), an Initial Control Response (ICR 540), or a CBF trigger 545. Each CBF message 520 transmitted between participating devices (e.g., AP 205 and STA 240) may be separated by an SIFS to provide a duration or delay interval between transmissions. The SIFS (Short Inter-Frame Space) may include a short time interval (e.g., 10 ms) used in a wireless communication protocol to allow for timely receipt of acknowledgments and synchronization between transmissions. For example, before the CBF PPDU transmission of the first AP 205, the CBFM 505 may trigger the CBF synchronizer 515 to transmit a CBF message 520 to the second AP 205. The CBF message 520 may be preceded by an SIFS to separate it in time from the previous CBF message 520, and may also be followed by an SIFS to separate it from the CBF transmission (e.g., CBF PPDU) to be transmitted.

[0090] The CBF request 525 can be any message or transmission for initiating coordinated beamforming (CBF) communication between the AP 205 and the station 240. The CBF request 525 can include, for example, a message sent by the first (e.g., initiating) AP 205 to the second (e.g., receiving) AP 205 and the STA 240 of the initiating AP 205 to signal the start of a transmission opportunity (TXOP) for CBF coordination. The CBF request 525 can include information about the participating STA 240, such as its identifier and the expected parameters of the CBF (e.g., the station capability data 550, including, for example, the number of spatial streams, transmission power, beamforming weights, timing synchronization, and channel state information). The CBF request 525 can act as an initial control frame (ICF) 535, which is transmitted and configured to request or collect and convey information for CBF coordination to the second AP and its own STA 240. The CBF request 525 can be transmitted by the first AP at the start of the TXOP to initiate the CBF synchronization or coordination process.

[0091] For example, if the station of the first AP (e.g., AP1-STA) does not have availability for a particular TXOP (e.g., Msg4 in the station feedback schedule), then the CBF request 525 (also referred to as CBF-req) can signal the CBF-TXOP termination. The CBF request 525 can indicate 'N' candidate STA groups (e.g., N = 3), where one group can be selected for a particular upcoming or current TXOP. Each group can identify a particular combination of the station of the first AP (e.g., AP1-STA) and the station of the second AP (e.g., AP2-STA), which can be limited to a total of 4 STAs, thus dividing the participation into, for example, 2 STAs per AP. Example signaling options can include the AID per STA (e.g., 11 bits), the "short AID" per STA (represented with fewer bits (e.g., 6 bits) and having a pre-negotiated / defined mapping to the AID), or a group ID (e.g., 8 bits) (having a pre-negotiated / defined mapping to a particular combination of AP1-STA and AP2-STA) (e.g., similar to the VHT GID). Additional information signaled per group can include one or more of the following: Nss per STA (e.g., 2 bits), MCS information per AP1-STA (e.g., 6 bits), RU indication (e.g., 9 bits), and the maximum payload duration supported by AP1 (e.g., the number of payload symbols without padding) (e.g., 9 bits). The common information for all STA groups, such as bandwidth (e.g., 3 bits) and puncturing (e.g., 5 bits), can be signaled in the common information and / or special user information field of the trigger frame containing the CBF-req. It can additionally include transmission information (e.g., MCS, Nss, or RU allocation) that causes AP2 to transmit a response in a subsequent PPDU (e.g., TB-PPDU or non-HT DUP PPDU).

[0092] For example, if no AP1-STA is available for the current TXOP (e.g., Msg4 in the station feedback scheduling), then the CBF request 525 (e.g., CBF-req) can signal the termination of the CBF-TXOP. For example, the CBF request 525 can indicate information of 'N' AP1-STAs (e.g., N = 2) participating in this CBF TXOP. The signaling options include the AID of the participating AP1-STA (e.g., 11 bits per STA) or a "short AID" with a pre-negotiated / defined mapping to the AID (represented by fewer bits, e.g., 6 bits per STA). The CBF request 525 can include the number (e.g., Nss) of spatial streams (e.g., spatial stream limitation) for each participating AP1-STA (e.g., 2 bits per STA), RU indication (e.g., 9 bits), BW (e.g., 3 bits), and puncturing (e.g., 5 bits), which can be signaled in the common information and / or special user information fields of the trigger frame containing the CBF-req. The CBF request can specify the maximum number of participating AP2-STAs (e.g., 2 or 3 bits) allowed for the next CBF transmission in this TXOP and the total maximum number of spatial streams (Nss) of the AP2-STAs allowed for the next CBF transmission in this TXOP (e.g., 2 or 3 bits). The CBF request can include the transmission information (e.g., MCS, Nss, RU allocation data) for the second AP to transmit a response in a subsequent PPDU (e.g., TB-PPDU or non-HT DUP PPDU).

[0093] The CBF response 530 can be any message or transmission for responding to the CBF request 525 and providing feedback on CBF coordination. The CBF response 530 can include, for example, a message indicating the participation of the second AP 205 in the CBF process sent by the second AP 205 to the first AP 205 and its STAs (e.g., the STAs of the second AP). The CBF response 530 can include information about the participating STAs 240 of the second AP 205, such as their availability, duration, and parameters required for CBF coordination (e.g., the number of spatial streams (Nss), modulation and coding scheme (MCS) index, transmission power, beamforming weights, timing synchronization, and channel state information). The CBF response 530 can respond to the CBF request 525 or the ICF 535 sent by the first AP. The CBF response 530 can be configured to provide the requested information to the first (e.g., initiating) AP205 to establish, determine, generate, modify, or update the schedule or synchronization of the CBF transmission, such as in response to any information that the AP205 has about the STAs 240 of the responding AP 205.

[0094] For example, the CBF response 530 (also referred to as CBF-resp) may signal or indicate whether the transmitting AP (e.g., AP2) will participate in the current CBF TXOP. If AP2 is to participate or if the CBF response is sent in response to a previous CBF-req in the same TXOP (e.g., from AP1), then the CBF-resp may signal the preferred group in the group signaled in the CBF-req. For example, the CBF response 530 may indicate or signal from a list of choices provided in an ICF (e.g., CBF request) from a first AP (e.g., AP1) the preferred group of stations participating in the CBF. The CBF response 530 may indicate or include the maximum payload duration (e.g., the number of payload symbols not including padding) (e.g., 9 bits) that can be supported by AP2 for the group and the relevant information (e.g., MCS) of each AP2-STA in the group that needs to be included in the preamble of the CBF PPDU. The CBF response 530 may indicate or include the nominal padding amount (e.g., 0 us, 8 us, 16 us, or 20 us) required by the AP2-STAs in the group. The CBF response 530 may include the transmission information (e.g., MCS, Nss, or RU allocation) for the response transmitted by AP1 in a subsequent PPDU (e.g., TB-PPDU or non-HT DUP PPDU).

[0095] For example, the CBF response 530 (e.g., CBF-resp) may indicate or signal whether the transmitting AP (e.g., AP2) will participate in this CBF TXOP, and if so, then it may signal a list of 'M' (e.g., M = 2) AP2-STAs participating in this CBF TXOP. The signaling option may include the AID (e.g., 11 bits) of each participating AP2-STA or a "short AID" with a pre-negotiated / defined mapping to the AID (represented with fewer bits, e.g., 6 bits per STA). The CBF response 530 may include data on the MCS (e.g., 6 bits) and Nss (e.g., 1 or 2 bits) of each participating AP2-STA and the maximum payload duration (e.g., the number of payload symbols not including padding) (e.g., 9 bits) that can be supported by AP2 for the participating AP2-STAs. The CBF response 530 may include the transmission information (e.g., MCS, Nss, or RU allocation) for the response transmitted by AP1 in a subsequent PPDU (e.g., TB-PPDU or non-HT DUP PPDU).

[0096] The Initial Control Frame (ICF) 535 can be any message or transmission for controlling and coordinating CBF communication between an AP and a STA. The ICF 535 can include a message sent by the first AP 205 to the second AP 205 and its STA 240 to initiate a TXOP for CBF coordination, including a Multi-User Request to Send (MU-RTS) or a Buffer Status Report Poll (BSRP) transmission. The ICF 535 can include information used by the CBF synchronizer 515 to establish the final schedule or determination for CBF communication, such as the participating STAs and their expected parameters (e.g., transmission power, beamforming weights, timing synchronization, and channel state information). The ICF 535 can be responsive to determining to initiate CBF synchronization and coordination (e.g., in response to data to be transmitted). The ICF 535 can operate by signaling the start of the CBF process and collecting the required information from the STA and the second AP. The ICF 535 can be transmitted by the first AP at the start of a TXOP to initiate the CBF process. Examples of TXOPs can include at least one of CBF, Wi-Fi QoS, multi-user transmission, high throughput Wi-Fi, and other TXOPs. The second AP 205 can transmit the ICF 535 to each second STA 240 and the first AP 205 to notify of an upcoming TXOP. In response to the first ICF 535 transmitted by the first AP, the second AP 205 can transmit a second ICF 535 to each second STA 240 to notify of an upcoming CBF TXOP. The notification can indicate the time interval during which the first AP and the second AP can access to transmit data packets or data to one or more stations of the first AP and one or more stations of the second AP without interruption (e.g., by means of one or more CBF transmissions). The notification can indicate the time interval during which the second STA 240 can access to transmit data packets or data to the second AP without interruption. The ICF 535 can allow the second STA 240 to transmit multiple frames within the allocated time. The notification of the ICF 535 can indicate that the upcoming TXOP is a CBF TXOP by using action frames, duration fields, control frame signaling (e.g., CBF reports), QoS TXOP management, frame sequences, and others. For example, the CBFM 505 can include NDPA frames (e.g., indicating the start of CBF feedback), NDP frames (e.g., sounding), and CBF feedback frames to provide CSI to indicate that the TXOP is a CBF TXOP.

[0097] The Initial Control Response (ICR) 540 can be any message or transmission for responding to the Initial Control Frame (ICF) 535 and providing feedback regarding CBF coordination (including an indication of capabilities, availability, or duration) for participating in the CBF TXOP. The ICR 540 can be any message sent by a STA 240 of the first AP 205 or the second AP 205 to its respective AP, indicating its availability for participating in the TXOP and the duration of data transmission for the IDC and the parameters for CBF coordination. The ICR 540 can contain information regarding the availability, duration, and parameters of the STA 240 for CBF coordination. For example, the parameters can include information or values for transmission power, beamforming weights, timing synchronization, and channel state information. The ICR 540 can respond to the ICF 535 sent by the first AP or the second AP. The ICR 540 can operate to update its scheduling and synchronization for CBF transmission by providing the required information to the AP. The ICR 540 can be transmitted by the STAs of the first and second APs after receiving the ICF 535 from their respective APs.

[0098] The CBF trigger 545 can be used to signal the start of a CBF transmission and synchronize any messages between the participating APs and STAs. The CBF trigger 545 can be a message sent from a first AP to a second AP to include any updated information and a final schedule (e.g., based on the ICR feedback from the STA 240 or based on the feedback from the second AP 205) to initiate a CBF PPDU transmission according to the latest parameters and data (e.g., and according to the updated transmission schedule). The first (e.g., initiating) AP 205 can generate a transmission schedule with updated transmission timing for each piece of information in the ICR received from the STA 240 after the CBF response from the non-initiating AP 205 in response to the ICF of the initiating AP 205. The CBF trigger 545 can include updated information about the participating STAs (e.g., per-STA MCS, per-STA Nss, etc.), parameters of the CBF transmission (e.g., duration or length of the transmission, bandwidth, puncturing information, guard interval, symbol duration, number of long training field (LTF) symbols, LTF type, pre-forward error correction (e.g., FEC) padding factor, error correction code for data reliability (e.g., LDPC additional symbols), packet extension (PE) disambiguation (e.g., duration and presence of the packet extension field at the end of the PPDU), transmission power, beamforming weights, timing synchronization, or channel state information), or scheduling timing for the CBF PPDU transmission (e.g., transmission power, beamforming weights, timing synchronization, and channel state information). The CBF trigger 545 can respond to the final schedule consensus and any updated information from the ICR received from the STA 240 or the CBF response received from the non-initiating AP. The CBF trigger 545 can operate by signaling the start of the CBF PPDU transmission and ensuring synchronization between the participating APs and STAs. The CBF trigger 545 can be transmitted by the first AP after updating its schedule and synchronization information based on the ICR received from the STA 240 of the first AP or the second AP 205.

[0099] The CBF trigger 545 can be transmitted before a CBF PPDU (e.g., a previous SIFS) and can perform one or more of the following functions to prepare for CBF PPDU transmission: provide preamble content for CBF transmission, assist the receiving AP and the transmitting AP in synchronizing timing / frequency offset, or signal a CBF-TXOP cancellation when the transmitting AP can no longer or does not intend to participate. The CBF trigger 545 can include the following preamble content for the CBF PPDU: "common" information (i.e., common / shared among STAs), such as one or more of L-SIG length, bandwidth, puncturing information, GI+LTF, number of LTFs, pre-FEC padding factor, LDPC additional symbols, PE disambiguation, etc., similar to the content present in the common information and special user information fields of a trigger frame addressed to an STA. Additionally, the CBF trigger 545 can include an indication of the MCS used to encode a portion of the CBF preamble with a variable MCS, the number of symbols in the portion of the CBF preamble with a variable MCS, or the number of STAs served by the CBF PPDU. The values of certain parameters can also be pre-negotiated between APs, such as one or more of BSS color, TXOP duration, GI+LTF, pre-FEC padding factor, LDPC additional symbols, or spatial reuse. Such parameters with pre-negotiated values may not be signaled / included in the CBF trigger 545. Additionally, the CBF trigger 545 can include per-STA information, such as one or more of MCS, Nss, spatial configuration, and encoding. The CBF trigger 545 can indicate the order in which the user fields appear in the preamble of the CBF PPDU. The CBF trigger 545 can indicate the order in which the spatial streams of each STA appear in the preamble and payload of the CBF PPDU. The CBF trigger 545 can also include padding (e.g., pre-negotiated between AP1 and AP2) to provide the receiving AP with additional time to process the CBF trigger 545 content frame and prepare for any upcoming transmission.

[0100] The CBF synchronizer 515 may include various CBF request 525 and CBF response 530 functions to initiate or respond to the initiation of CBF synchronization between APs 205. The CBF synchronizer 515 may configure or generate a CBF request 525 or a CBF response 530 to include any information, data, parameters, specifications, signals, indications, and other forms of data for indicating and coordinating the CBF PPDU transmission. The CBF requests 525 and CBF responses 530 may indicate the initial control frame 535 (ICF 535) of the AP 205 or STA 240. The ICF 535 may occur at the beginning of the CBF message 520 to indicate, identify, or otherwise establish the parameters, specifications, metrics, or signals for transmitting the CBF PPDU via the link 560. The ICF 535 may trigger or otherwise initiate communication between the first AP 205 and the first STA 240 or between the first AP 205 and the second AP 205. The ICF 535 may include a message, transmission, or data structure including information for CBF operations, including any transmission or message exchanged between APs 205 or between an AP 205 and an STA 240 during CBF setup or coordination. The ICF 535 may include and carry data such as station capabilities 550 or AP capability data 555. The ICF 535 may include any one or more of the following: one or more multi-user request to send (MU-RTS) frames, one or more buffer status report poll (BSRP) frames, one or more synchronization signal blocks (SSB) frames, or a paging frame addressable to the STA 240 participating in the CBF TXOP. The MU-RTS / BSRP may perform the functions of the ICF 535 and initiate the synchronization process between the initiating devices (e.g., the AP 205 and the STA 240). The ICF 535 may perform functions related to EMLSR, IDC, power saving, and signaling to the STA 240 of the AP and other APs 205 the intention or preliminary determination that the initiating AP 205 will use CBF communication in the current or upcoming transmission opportunity (TXOP).

[0101] The CBF synchronizer 515 may include functions that configure the multi-user request to send (MU-RTS) to facilitate or trigger communication from multiple devices (e.g., multiple STAs 240) based on reserved or coordinated time slots in the transmission period. For example, the buffer status report poll (BSRP) may include a transmission for requesting buffer status information (e.g., buffer size, queue status, or priority information) about the amount of data of the stations queued for transmission. For example, the asynchronous signal block (SSB) may include a broadcast by the AP 205 providing initial synchronization and access information.

[0102] The CBF synchronizer 515 may include any functionality for generating, establishing, or updating a schedule for synchronizing or coordinating CBF communications. The schedule may be any plan, structure, or information for coordinating or synchronizing CBF communications between participating devices, including any participating AP 205 and STA 240. The schedule may include data identifying each participant and any time intervals in the CBF PPDU transmissions for the participant or its data. The schedule may be a final schedule between two or more AP 205s based on an initial CBF response, an initial control frame (ICF), an initial control response (ICR) (e.g., including data on the STAs and APs that the AP 205 may determine are expected to participate). The schedule may include an updated schedule incorporating feedback from participating STAs or APs and adjustments made in response to no communication from a participant, in which case (e.g., when it has not responded for a predetermined duration), the participant may be determined to not be participating in the CBF TXOP. The schedule may include information such as transmission timing, participating STAs, their parameters (e.g., MCS, Nss, coding (LDPC or BCC), amount of outstanding data or enqueued traffic, nominal padding requirements, duration of station availability), transmission parameters (e.g., duration or length of transmission, bandwidth, puncturing information, symbol duration, number of long training field (LTF) symbols, GI+LTF type, pre-FEC padding factor, LDPC extra symbols, PE disambiguation, transmission parameters (e.g., transmit power, beamforming weights, timing synchronization, or channel state information)), and any parameters or data for synchronizing the communications. The schedule may include data for controlling the timing and coordination of CBF transmissions, including the timing for individual participants to transmit their data, thereby allowing for reduced phase misalignment and optimized beamforming efficiency.

[0103] Station 240 may include the function of receiving ICF 535 from AP 205 and generating a response (e.g., an initial control response (ICR) 540). For example, when STA 240 receives the CBF message 520, STA 240 may use the communication controller 215 to respond to the CBF message 520 by transmitting ICR 540 to provide any requested information to the requesting AP 205, such as the current or future availability of the CBF TXOP, the duration of the availability, the available bandwidth for receiving CBF transmissions, or transmission parameters, including MCS, Nss, or allocated RU information. The communication controller 215 may use ICR 540 to indicate, establish, or otherwise confirm the receipt of ICF 535 and provide additional or requested information for CBF PPDU transmission. When confirming ICF 535, ICR 540 may trigger STA 240 to initiate preparation for receiving the CBF PPDU, such as re-enabling receiver functions that were previously disabled (e.g., due to being in a power-saving state) or blocking any functions that may interrupt future reception (e.g., channel switching, power saving, or any scheduled transmissions on the same or different links). The CBF trigger 545 may initiate, trigger, or otherwise cause coordinated beamforming of the antennas 225 of AP 205 and STA 240 by optimizing the signal to direct radio waves at maximum signal strength while minimizing interference to unintended STA 240. The first AP 205 may transmit the CBF trigger 545 to each participating device related to the CBF PPDU transmission (e.g., the second AP 205, the first STA 240, the second STA 240).

[0104] Each AP 205 may include one or more station selectors 510 to select, determine, or otherwise identify the selection of STAs 240 for CBF operation. The station selector 510 may include any combination of hardware and software for identifying and selecting suitable stations 230 within the range 255 of the AP 205. The station selector 510 may include the function of selecting the stations 240 within one or more BSSs 250 that participate in CBF. The station selector 510 may utilize any combination of station capability data 550 or AP capability data 555 to select suitable candidate stations 240 based on various capabilities (such as the number of antennas of the AP or candidate stations, bandwidth support, and nulling capabilities, which can be used to determine the suitability of the station 240 to participate in CBF operation). For example, the station selector 510 may identify STAs 240 that can support CBF based on the reported capabilities exchanged during the CBF setup process between APs 205. For example, the station selector 510 may utilize traffic characteristics, such as information on the downlink data traffic of each STA 240 at the AP 205 within its BSS 250 or the attributes of the downlink data traffic available for each STA 240 at the AP 205. The downlink data traffic attributes may include specific QoS requirements, such as the maximum allowable latency or the minimum required data rate or zero packet loss, and the data traffic can be intermittent and continuous. For example, the station selector 510 may utilize channel characteristics, such as the RSSI observed at each STA 240 due to the transmissions from each AP 205, the proximity of the STA 240 and a specific AP 205 relative to other APs 205, or the downlink channel state information (DL CSI) at each STA 240 relative to each AP 205.

[0105] The communication controller 215 may include functions for managing and facilitating the communication exchange between the AP 205 and the STA 240 for CBF establishment and operation. The communication controller 215 may include the use, communication, or implementation of sequences and the exchange of ICF 535, ICR 540, AP capability data 555, and station capability data 550 between APs 205 to coordinate and establish CBF between APs 205. For example, the communication controller 215 facilitates and manages the exchange of ICF 535 between the AP 210 and the station 240 and between different APs 205 during the CBF setup and data transmission phases.

[0106] The CBF synchronizer 515 may include functionality for generating, constructing, or producing a schedule for CBF communication in response to data or information received from the participating STA 240, the non-originating AP 205, and the originating AP 205. For example, the CBF synchronizer 515 may be configured to defer or delay generating the CBF communication schedule until an ICR is received from each STA of the participating APs 205 or until a CBF response is received from the non-originating (responding) AP. The CBF synchronizer 515 may be configured to generate a schedule for CBF communication in response to at least one or all of an ICR from an STA of the participating AP 205 identified in the ICF from the originating AP 205 and a CBF response from the responding AP 205.

[0107] The CBF synchronizer 515 may include functionality for adjusting CBF determination and scheduling based on updated information from the STA 240 (including any ICR messages from the STA 240 after the CBF response from the responding AP 205). The CBF synchronizer 515 may include functionality for adjusting CBF determination and scheduling based on updated information from the STA 240. For example, the CBF synchronizer 515 of the second AP 205 may receive one or more ICRs 540 from the second AP STA 240. These ICRs 540 may include updated information of the STA 240, which may be used to generate a final schedule. When receiving the CBF response 530, the first AP 205 may utilize the station capabilities 550 and information of the ICR 540 from the first STA 240 (e.g., station capability data 550 and AP 205 capability data 555) to determine whether to generate an abort signal for the CBF TXOP. In some examples, the first AP 205 may transmit a CBF message 520 embedded with the abort signal to the AP 205 and the STA 240. The abort signal generated by the first AP 205 may cancel or abort the CBF TXOP based on a plurality of factors detected by the first AP 205 to prevent resource waste and performance degradation of the system 500. The factors may include CSI issues (e.g., incorrect CSI, incomplete CSI feedback), AP 205 or STA 240 failures (e.g., misaligned timing, non-responsive AP 205), interference detection (e.g., external interference, self-interference), network resource allocation (e.g., prioritized traffic, congestion), and other factors affecting the CBF TXOP. For example, the first AP 205 may generate an abort signal in response to a CBF response 530 from the second AP indicating insufficient power resources for the CBF PPDU. In another example, the first AP 205 may generate an abort signal in response to the first AP 205 detecting a failure at the AP 205 and the STA 240. The first AP 205 may determine whether to generate an abort signal based on the detection of at least one of the above factors.

[0108] For example, in response to the first AP 205 not detecting one or more parameters or factors from a previous transmission, the first AP 205 may convey, send, or otherwise provide a CBF adjustment (e.g., CBF request 525) to the second AP 205 to indicate whether the second AP 205 may participate in the CBF TXOP. The CBF request 525 may include station capability data 550 (of the first STA 240 and the first AP 205) and AP capability data 555 of the first AP 205. By transmitting the CBF message 520 to the second AP 205, the AP 205 may convey beamforming information and parameters for synchronization according to the CBF synchronizer 515. In some examples, the CBF message 520 may embed the CBF request 525 at the initiation of the CBF TXOP. For example, the CBF synchronizer 515 may perform the functions of the ICF 535 for the first STA 240 and the second AP 205 within the set of candidates for the STA 240 for the CBF message 520 addressed to the second AP 205 and the first STA 240. The functions may include EMLSR, IDC, power saving, and other functions for the ICF 535. For example, the CBF synchronizer 515 may embed the CBF request 525 within the CBF message 520.

[0109] The CBF synchronizer 515 may transmit messages providing CBF adjustments from other APs 205. For example, the CBF synchronizer may generate, transmit, send, or otherwise provide a third message (e.g., CBF adjustment) indicating a CBF adjustment to the first AP 205, where the CBF adjustment may be provided in the form of an updated CBF response 530 to a CBF request from the first AP 205. The CBF response 530 may indicate that the second AP 205 and the second STA 240 participate in the CBF TXOP. By transmitting the CBF request and the CBF response, the first AP 205 and the second AP 205 may tune the scheduling consensus. The scheduling consensus may correspond to multiple entities (e.g., STA 240, AP 205, antenna 225) that transmit and receive scheduling parameters for CBF PPDU transmission. The scheduling consensus may provide each AP with knowledge of which STAs of each AP will participate in the CBF TXOP and the number of spatial streams intended for each participating STA in the CBF transmission, thereby facilitating the AP to optimally calculate the beamforming vectors. The scheduling consensus may allow any AP to determine which MCSs may be used for its STAs in the CBF transmission. The scheduling consensus may provide any AP with information about which MCSs may be used for the STAs of other APs in the CBF transmission. The scheduling consensus may provide any AP with information about the duration of the CBF transmission. The scheduling consensus may provide the AP with a partial or complete indication of the PHY preamble content and the relevant parameters for constructing the CBF PPDU. The scheduling consensus may allow each participating entity in the CBF operation to synchronize and align with respect to the timing of the CBF PPDU transmission to reduce the occurrence of phase misalignment based on the ICR 540 from the first STA 240 and the second STA 240. Additionally, using the ICR 540 from the STA 240 and the parameters of the first AP 205 and the parameters of the second AP 205, the AP 205 may generate a schedule for the CBF PPDU transmission. The schedule may indicate the updated optimal time for the CBF PPDU transmission to synchronize the AP 205 while minimizing the interference to the AP 205.

[0110] The station capability data 550 (also referred to as station capability 550) may include any data or information related to the capabilities, settings, and parameters of the STA 240 within the AP 205 that is involved in CBF operations. The station capability data 550 may include information such as the number of antennas of the STA 240, the bandwidth support corresponding to the station or channel, the downlink CSI (e.g., channel gain, phase information, delay spread, Doppler spread, signal-to-noise ratio), the received signal strength indicator (e.g., signal quality, power level), or the sounding and nulling capabilities of the STA 240, including data on whether the station supports specific sounding frames or has the ability to provide or determine CSI. The station capability data 550 may include or correspond to the maximum client limit of the STA 240, the antenna configuration, the nulling capability, the type and capacity of traffic handled by the station, the path loss observations, the role in the network topology (e.g., whether the station is a relay or a primary endpoint), and any data regarding channel conditions, interference levels, data loss, or network congestion.

[0111] The AP capability data 550 (also referred to as AP capability 555) may include any characteristics or attributes that define the performance or functionality of the AP 205. The AP capability data 555 may include characteristics or attributes related to wireless network communication. For example, the AP capability data 555 may include the number of antennas used for transmitting or receiving wireless signals supported by the AP 205, the bandwidth supported by the AP 205, the sounding capabilities supported by the AP 205 (e.g., joint sounding or individual sounding), or the nulling capabilities supported by the AP 205 (e.g., full-rank nulling, partial-rank nulling, maximum number of nulling dimensions). For example, the AP capability data 555 may include the maximum number of OBSS stations (e.g., stations that may be part of CBF operations) whose information (e.g., including channel sounding reports) can be stored. The AP capability data 555 may include precoder types, such as the minimum mean square error (MMSE) or zero-forcing (ZF) techniques. The AP capability 555 may include channel and traffic characteristics for selecting the STA 240 to participate in CBF operations. The AP capability 555 may include information regarding the amount of padding included in frames exchanged between the AP and the STA or between APs. Padding may provide additional processing time for the receiving device before it responds. The AP capability data 555 may include information indicating the common basic service set (BSS) color or the association identifier (AID) of the participating station 240. The AID may include a unique identifier used in a wireless network to identify and manage devices accessing the network within the same network infrastructure.

[0112] The capabilities that include AP capabilities 555 or station capabilities data 550 may include information about the number of antennas, bandwidth, and detection capabilities, the availability of one or more stations 240 to participate in a TXOP (e.g., based on previous power saving indications from stations 240), or information about the duration of data transmissions of one or more STAs 240 (e.g., based on the amount of queued or pending data traffic at stations 240 or the average duration measured from previous data transmissions from stations 240). The capabilities may include nulling capabilities or the maximum client limit of the AP 205. The AP 205 may be configured to perform handshakes and exchange various information (e.g., via ICF and CBF responses), including information about modulation and coding schemes (MCS) and their associated error vector magnitude (EVM). The MCS may include or identify one or more parameters that indicate the data rate or error correction level in wireless communication, which may be used, for example, to balance the speed of communication with the reliability of transmission. The MCS may define or set a combination of modulation type and error correction coding rate. For example, a value parameter above the threshold of the MCS may use 64 quadrature amplitude modulation (64-QAM) with a lower coding rate for faster data transmission (e.g., a transmission greater than the transmission rate threshold), while a value parameter of the MCS below the threshold may use BPSK with a higher coding rate for more reliable communication under poor signal conditions but at a lower transmission rate (e.g., a transmission less than the transmission rate threshold).

[0113] The capabilities that include AP capabilities 555 or station capabilities 550 may include information about parameters such as the AID of each candidate STA, the physical layer capabilities of each candidate station (e.g., station capabilities data), such as operating bandwidth, the maximum number of receive spatial streams (e.g., receive Nss), detection feedback capabilities, and MAC capabilities, and any padding preferences. The capabilities may further include a station list for a particular AP, the number of per-STA spatial streams (e.g., Nss) for the AP, STA, or STA group, and any resource unit (RU) allocation for the AP, STA, or STA group.

[0114] Still referring to Figure 5, the first AP 205 can use the station selector 510 to select one or more potential stations 240 within its own BSS 250 to participate in CBF. To make such a selection, the station selector 510 can use, for example, the station capability data 550 of the station 240 and its own AP capability data 555 (such as channel and traffic characteristics or previous station availability information) to select the STA 240 to participate in the CBF operation. The station capability data 550 can include or indicate the capabilities, settings, or parameters of the individual station 230 related to the capabilities and functions of the station 240 relative to CBF. The AP capability 555 can include the characteristics or attributes that define the performance or functions of the AP 205 for implementing wireless communication. The AP capability data 555 can include, for example, information about the amount of padding included in the frames exchanged between the AP and the STA or between the APs. Padding can provide additional processing time for the receiving device before it responds. The AP capability data 555 can include, for example, signals or data indicating the amount of padding requested by the receiving device or provided by the transmitting device. The first AP 205 can use the communication controller 215 to exchange one or more station capability data 550 indicating the capabilities of the candidate STA 240 with the second AP 205. The second AP 205 can similarly collect and then share with the first AP 205 the AP capability data 555 of the second AP 205 and the station capability data 550 of the stations 240 in the second BSS 250 of the second AP 205. Based on the collected and exchanged capabilities of all candidate stations 240, the first AP 210, the second AP 205, or the first and second APs 205 together can determine which stations 240 will participate in the CBF operation. The first AP 205 and the second AP 205 can implement a sequence (such as, ICF 535) between each other to establish a group of stations 240 for the CBF 505 operation.

[0115] During the process of the ICF 535 for CBF establishment, the first AP 205 and the second AP 205 can exchange their AP capability data 555, such as the number or dimensions of the supported antennas 225, the detection capability, and the nulling capability of the AP 205. The first and second APs 205 can use parameters, such as indicating the specified common basic service set (BSS) color or the association identifier (AID) of the participating stations 240. The AID can include a unique identifier used in the wireless network to identify and manage the devices accessing the network within the same network infrastructure. The first AP 210 can handshake with the second AP 205 to exchange the candidate station capability data 550 (such as the number of antennas, bandwidth, detection, and nulling capabilities) or the AP capability data 555 (such as the maximum client limit). This first AP 205 can enter the CBF coordination phase with the second AP 205 to determine the parameters of the CBF operation (such as, nulling direction, type, or duration), and use the information from the frame preamble of the second AP to perform the CBF 505 operation based on the common BSS color or AID.

[0116] AP 205 may include a CBF synchronizer 515 to coordinate or synchronize CBF communications using any combination of CBF messages 520. The CBF messages 520 may include any messages for collecting, coordinating, or adjusting information for CBF communications, including CBF requests 525, CBF responses 530, ICFs 535, ICRs 540, or CBF triggers 545. For example, a first AP 205 may include a CBF synchronizer 515 configured to generate, transmit, send, receive, or otherwise provide a CBF message 520 (e.g., a first message, such as an ICF 535) to a second AP 205 or an STA 240 of the first AP 205 to initiate a TXOP for CBF coordination or synchronization between two or more APs 205 and two or more STAs 240 of the first and second APs. The CBF message 520 (e.g., an ICF 535) may be transmitted by the CBF synchronizer 515 or the CBFM 505 as part of a coordination phase to collect information from STAs 240 within its BSS 255 or to exchange information between APs 205. The CBF message 520 may identify or indicate at least one AP 205 capable of performing CBF operations. In some examples, the identification of at least one AP 205 may occur before receiving an ICR 540 from an STA 240 associated with a CBF PPDU transmission. The second AP 205 addressed by the first message (e.g., an ICF 535 or a CBF request 520) may respond to the first AP 205 by transmitting a CBF response 530. The CBF response 530 may include information about the participating STAs 240 of AP2 205 and any parameters of those STAs for CBF coordination (e.g., MCS, Nss, bandwidth, puncturing information, nominal padding requirements, amount of pending or queued traffic, duration of station availability, transmit power, beamforming weights, timing synchronization, and channel state information). For example, the CBF response 530 may signal the availability and duration of AP2-STAs, allowing the first AP 205 to update its scheduling and synchronization information accordingly.

[0117] By transmitting their initial CBF messages 520 (e.g., ICF 535 or CBF request and CBF response 530), the first AP 205 and the second AP 205 can reach a scheduling consensus. The scheduling consensus can include a plurality of entities (e.g., STA 240, AP 205, antenna 225) determined and set by the first AP and the second AP based on their available information and can correspond to transmitting and receiving scheduling parameters for CBF PPDU transmission. The scheduling consensus can be completed based on the ICR 540 of the STA 240 from the first AP or the second AP, which can be used to transmit updated information about the availability of the STA or the parameters for participating in CBF to the AP. The scheduling consensus can allow each participating entity in the CBF operation to synchronize and align the timing of CBF PPDU transmission to reduce the occurrence of phase misalignment, without any change or correction to the scheduling consensus in subsequent ICR 540 (e.g., from STA 240). The scheduling can include at least one of a modulation and coding scheme (MCS) for one or more STAs, Nss for one or more STAs, packetization or sequencing for each participating STA, the duration of CBF transmission, and the parameters signaled in the CBF preamble. For example, the scheduling can include one or more MCS settings for each STA 240 participating in the CBF TXOP. To establish one or more MCS settings, the CBF synchronizer 515 can utilize conditions such as the distance, interference, and obstacles between each STA 240. By utilizing the conditions, the CNF synchronizer 515 can establish one or more MCS settings to dynamically adapt the MCS of each STA 240 using link adaptation.

[0118] The CBF message 520 (e.g., ICF 535 or ICR 540) can include any information for coordinating CBF communication, including information about the timing, availability, and parameters of any participants, such as the timing of data transmission of each participant within the TXOP of each AP or STA. The CBF message 520 can include information about the direction in which interference from the second AP 205 will be completely or partially nulled. For example, the CBF message 520 can include a plurality of directions for the second AP 205 to partially null for full null interference. The first AP 205 and the second AP 205 can select a subset of the set of directions to partially or completely null the interference from the second AP 205 when transmitting the CBF PPDU. The CBF message 520 can include a list of identifiers of a first set of candidate stations, information about the proposed start time or duration of CBF transmission, and the proposed number of spatial streams. The proposed start time or duration can correspond to the scheduling consensus of the first AP and the second AP.

[0119] The set of directions for making the interference partially or fully zero may correspond to a configuration of beamforming weights or spatial directions that increases the likelihood that antenna 225, AP 205, or STA 240 does not interfere with the transmitted signal. To achieve this, the set of directions may use linear algebra (e.g., vectors, matrices) to find beamforming weights that are orthogonal to the interference channel. By communicating the parameters before the CBF PPDU transmission by AP 205, AP 205 can effectively improve the synchronization of the CBF PPDU transmission.

[0120] The first AP 205 may transmit a CBF message 530, such as an ICF 535, to at least the first STA 240 in a set of one or more candidate STAs 240. The first AP 205 may use the station selector 510 to select, identify, or otherwise indicate the first STA 240 from the candidate set of STAs 240 based on information that the first AP 205 receives, retrieves, or otherwise obtains regarding the availability of participating in the TXOP and the duration of data transmission from the first set of candidate stations. For example, the first AP 205 may retrieve the availability of the first STA 240 to participate in the TXOP and the average duration of the data transmission of the first STA 240. Once retrieved from the first STA 240, the CBFM 505 may compare the availability and the average duration with a threshold. The threshold may indicate the minimum availability and duration for the corresponding STA 240 to participate in the TXOP. In response to the availability of the first STA 240 and the average duration of the data transmission meeting the threshold, the first AP 205 may determine, identify, or otherwise indicate that the first STA 240 participates in the CBF TXOP. The first AP may iteratively repeat this process for each first STA 240 within the range of the first AP 205. Upon completion of the iteration, the first AP 205 may determine, identify, or otherwise indicate the first set of STAs 240 of the first AP 205 to participate in the CBF TXOP during the TXOP. Each STA 240 in the first set of STAs 240 may include the availability and the duration of the data transmission that meet the threshold. The reception of the ICF 535 by the second AP 205 or the first STA 240 may initiate the CBF TXOP. The CBF TXOP may allow the first AP 205 to generate and transmit the CBF message 520 using the CBFM 505 without interference or interruption from other APs 205 or STAs 240.

[0121] By transmitting a CBF message 520 (e.g., ICF 535) to the second AP 205, the AP 205 can convey the beamforming information and parameters of the first AP 205 and its STA 240 to synchronize the information with the second AP 205 according to or using the CBF synchronizer 515. For example, the CBF synchronizer 515 can perform the functions of the ICF 535 on the first STA 240 and the second AP 205 within the candidate group of STAs 240. The functions of the ICF 535 can be used to address the CBF message 520 to the second AP 205 and the first STA 240. The functions of the ICF 535 can include EMLSR, IDC, power saving, and other functions of the ICF 535. The functions of the ICF 535 can cause the second AP 205 to respond to the first AP 205 with the beamforming information, parameters, and station capability data of the second AP 205. Concurrently, the CBF synchronizer 515 can embed the CBF request 525 within the CBF message 520.

[0122] The second AP 205 can receive, retrieve, or otherwise obtain the CBF message 520 (e.g., ICF 535 from the first AP) via the communication controller 215. The CBF message 520 (e.g., ICF 535) can include an indication for the second AP 205 to solicit information about a second group of candidate stations. The indication can cause, trigger, or enable the second AP 205 to retrieve information about availability and duration of data transmission from the second STA 240. The solicited information can allow the CBFM 505 of the second AP 205 to select a second group of stations of the second AP from the second group of candidate stations 240 to participate in CBF during the TXOP. The second group of STAs 240 can be different from the first group of STAs 240. The second AP can use the information (e.g., availability and duration) to select each STA 240 within the group of STAs 240. The CBF message 520 (e.g., ICF 535) can include information, parameters, data, or signals for initiating a CBF TXOP, such as power requirements, station capability data 550, AP capability data 555, available resources, and other parameters for initiating a CBF TXOP.

[0123] The first STA 240 may receive, retrieve, or otherwise obtain a CBF message 520 (e.g., ICF 535) from the first AP 205 via the communication controller 215. The first STA 240 may receive the CBF message 520 (e.g., ICF 535) from the first AP 205 over the link 560. In response to the first CBF message 520 from the first AP 205, the first STA 240 may provide the station capability data 550 of the STA 240 to the first AP 205 via the ICR 540 in response to the receipt of the CBF message 520. The station capability data 550 of the first STA 240 may include an indication of the availability of the station and the duration of the availability of the station. The first STA 240 may formulate the station capability data 550 using the ICR 540 and transport the ICR 540 to the first AP 205 as a response to the CBF message including the ICF 535. In response to the first message, the first AP 205 may receive one or more indications from the first STA 240. The one or more indications may correspond to one or more durations of data transmission for each of one or more first STAs 240. The one or more indications may correspond to the availability of the first STA 240 in the candidate group of STAs 240 to participate in a TXOP. The one or more indications may be flags, indications, frames in the preamble of a data packet, and other indications. The one or more indications may be received via at least one of a triggered-based physical protocol data unit (TB-PPDU) format or a non-high throughput duplicate transmission (non-HT DUP) format. For example, a first subset of the first STAs 240 may indicate the non-availability of participating in a TXOP, while a second subset of the first STAs 240 may indicate the availability of participating in a TXOP. In another example, a subset of the first STAs 240 may provide the duration of data transmission to the first AP 205. Using the duration of data transmission for each of the subsets of the first STAs 240, the first AP 205 may determine the availability of each of the subsets of the first STAs 240.

[0124] The second AP 205 may transmit, send, or otherwise provide a second message (e.g., CBF-resp-init, also known as CBF initial response) to the first AP and the multiple candidate second STAs 240. The CBF-resp-init (e.g., CBF initial response) may indicate whether the second AP may participate in the TXOP based on current transmission parameters (e.g., the presence of downlink traffic, the applicability of CBF, etc.). The multiple candidate second STAs 240 may include the total number of second STAs 240 within the range of the second AP 205. The multiple second candidate STAs 240 may be based on current transmission parameters as a hypothesis or estimate. The CBF-resp-init may not include specific information about the second STA 240, such as the availability of the second STA 240 to participate in the TXOP or the duration of data transmission for the availability of the second STA 240.

[0125] Upon receiving one or more indications and the CBF-resp-init, the first AP 205 may determine, create, or otherwise generate a third message (e.g., CBF request) to indicate the availability of a subset of the first STAs 240 to participate in the TXOP. Information within the ICR 540 of each first STA 240 may be used to generate the third message. The information may include the availability of the subset of the first STAs 240 and the duration of the availability of the first STAs 240 to participate in the TXOP within the ICR. In some embodiments, the first AP 205 may transmit, send, or otherwise provide the third message (e.g., CBF-request) to the second AP 205 and the first STAs 240. The CBF request may indicate or include information associated with the TXOP. For example, the CBF request may signal that the third message indicates that the CBF TXOP is aborted or terminated based on the ICR of the first STA 240. The CBF TXOP may be aborted or terminated in response to one or more of the first STAs 240 in the subset of the STAs 240 not being available for the CBF TXOP. In another example, the CBF request may signal that the third message indicates that the CBF TXOP is aborted or terminated based on the information within the CBF-resp-init (e.g., the downlink traffic is high enough). Based on the information within the ICR 530 or the CBF-resp-init, the first AP may determine, indicate, or otherwise identify whether to initiate the TXOP or abort / terminate the TXOP.

[0126] If the first AP 205 determines to initiate a CBF TXOP, the first AP 205 may transmit, send, or otherwise provide a third message to the second AP 205. Upon receiving the third message, the second AP 205 may generate a CBF message 520 (e.g., CBF response) for transmission to one or more STAs 240 as indicated within the CBF-resp-init. The second AP 205 may extract parameters (e.g., ICF 535) from the CBF message 520 and generate a CBF response 530 (e.g., CBF message 520) to provide parameters of the second AP 205, such as the station capability data 550 of the second AP's STAs 240, the AP capability data 555 of the second AP 205, including any information regarding the available resources within the ICR 540 received by the second AP 205 from the second AP's STAs 240 and others. In response to the first AP 205 not terminating the CBF TXOP as indicated in the CBF request within the third message, the second AP 205 may transmit the CBF message 520 to one or more second STAs 240 during the coordination phase of the first and second APs 205. The CBF message 520 may identify the second station 240 of the second AP 205 for which interference from the first AP 205 will be partially nulled or fully nulled. The message 520 may include or identify a second direction in which interference from the first AP is partially nulled or fully nulled at the second station 510. The direction or group of directions may be linearly independent vectors or directions along which transmissions from the first AP 205 can be reduced to below a predetermined threshold (e.g., corresponding to the power or gain level of the signal or a threshold defined according to the noise signal level). The message 520 may include location information (e.g., the position of the STA relative to the AP 205, the coordinates of the STA 240 relative to the AP 205, information regarding the spatial orientation of the STA, or any other information corresponding to the spatial orientation of the STA). The message 520 may be embedded or encrypted with the CBF response 530 for transmission to the first AP 205. The second AP 205 may transmit the CBF response 530 to the first AP 205 to confirm receipt of the CBF request 525 and indicate the second STAs 240 participating in the CBF TXOP.

[0127] The second AP 205 may use a station selector 510 to select, identify, or otherwise indicate a second STA 240 (e.g., participating in a CBF TXOP) from a pool of a second group of candidate STAs 240. The second group of candidate STAs 240 selected for the CBF TXOP may include any number of STAs 240 of the second AP 205 and may have the same or different number of STAs as the first group of candidate STAs 240 selected by the first AP 205. The station selector 510 may use the presence of data traffic (e.g., pending or queued downlink (DL) data traffic of the STA 240), the applicability of CBF, and other factors to identify STAs 240 to participate in the CBF TXOP. The second STA 240 may be connected to the second AP 205 via a link 560. The second STA 240 may be co-located with the second BSS 250 and located within a second range 255B of the second AP 205. Once the second STA 240 is connected, the second AP 205 may generate an ICF 535 for the second STA 240 and a CBF response 530 for the first AP 205. For example, the second AP 205 may select the second STA 240 based on reduced data traffic in the channel. Reduced data traffic may indicate a lower amount of interference for the CBF PPDU.

[0128] The second AP 205 may transmit the ICF 535 to the second STA 240. The ICF 535 of the second AP 205 may be transmitted in response to the transmission of the ICF 535 of the first AP 205 to the second AP 205. The ICF 535 may be one or more (e.g., a series of) frames that are ordered or organized for exchange between the second STA 240 and the second AP 205. Using one or more frames of the ICF 535, the second STA 240 may be configured to set, establish, or otherwise manage communication parameters to allow synchronization, resource allocation, and interference reduction between the first AP 205 and the second AP 205. The ICF 535 may include various frame sequences such as RTS / CTS, trigger frames, beacon and probe frames, CSI feedback, null frames, coordination frames, CBF PPDU, and other frames. Upon receiving the ICF 535, the second STA 240 may generate an ICR 540 for transmission to the second AP 205 to confirm the receipt of the ICF 535. The second AP 205 may use the ICR 540 from the second STA 240 or a subset of the second STA 240 to update the CBF resp with a subset of the second STA 240 participating in the CBF TXOP.

[0129] The first station 240 may be configured to receive a wireless transmission from the first AP via the wireless local area network (WLAN) of the first AP. The second station 240 may be configured to receive a wireless transmission from the second AP via the WLAN of the second AP. The first station 240 and the second station 240 may each be located within a first range 255 of the wireless transmission from the first AP 205 and a second range 255 of the wireless transmission from the second AP 205.

[0130] In some examples, the first AP 205 may be configured to determine, identify, or otherwise calculate the spatial orientation of one or more antennas 225 of the first AP 205 based at least on a second set of one or more directions. The spatial orientation of one or more antennas 225 of the first AP 205 may be the physical spatial orientation of the antennas or a vector (e.g., a beamforming vector) of different beamforming weights (e.g., amplitude and phase) that vary with any change in frequency. The spatial orientation of one or more antennas 225 of the first AP 205 may be determined based at least on one or more of the following: downlink channel state information (CSI) at the first STA 240 as measured from the first AP 205 or the second AP 205, downlink channel state information (CSI) at the second STA 240 as measured from the first AP 205 or the second AP 205, the locations (e.g., coordinates or GPS location) of the first station 240, the second station 240, and / or the first AP 205. The first AP 205 may be configured to beamform a transmission relative to the first station 240 based at least on the spatial orientation of one or more antennas 225 of the first AP 205.

[0131] In some examples, the first AP 205 may be configured to receive, retrieve, or otherwise obtain a packet that includes information about the first STA 240. The packet may include a network packet, message, or transmission that may include information about the characteristics of the channels of the first station 240 and / or the second station 240. The first AP 205 may be configured to identify from the received packet information that indicates the spatial orientation of the first client relative to the second AP. For example, the first AP 205 may determine linear independent vectors at the STA 240 where the interference at the STA 240 is partially or fully nulled. The first AP 205 may be configured to use the spatial orientation to determine a first set of one or more directions of one or more antennas.

[0132] Packet information from the first STA 240 may trigger, cause, or otherwise initiate the first AP 205 to embed timing, frequency, and control information of the first AP 205 (e.g., the direction of the antenna, the MCS assigned to each STA, the Nss assigned to each STA 240, the content of the preamble, etc.) into one or more fields of the packet or the fourth message (e.g., CBF trigger 545). The timing, frequency, and control information may be embedded within the end of the frame sequence. For example, the first AP 205 may embed the timing and control information of the first AP 205 within the end of the frame of the packet (e.g., CBF trigger 545) transmitted to the second AP 205. By embedding the timing and control information within the end of the frame sequence, the second AP 205 may start incrementing a counter for the time interval to the CBF PPDU. As the counter increments, the second AP 205 may adjust one or more antennas to align with the first AP 205 to allow synchronization. In another example, the first AP 205 may embed the MCS requirements assigned to each first STA 240 of the first AP 205 into the third message before transmitting to the second AP 205. By embedding the MCS requirements, the first AP 205 may broadcast the MCS requirements to the AP 205 and the STA 240. Based on the broadcast MCS requirements, the STA 240 and the AP 205 may further synchronize the CBF PPDU through the AP 205 by using scheduling consensus and the parameters of the first AP 205. The packet may include CSI information for beamforming weights to align the STA 240 and the AP 205 and feedback packets from the AP 205 and the STA 240 to adjust the timing and synchronize the transmitter to improve signal reception.

[0133] The first AP 205 may be configured to transmit, send, or otherwise provide a fourth message (e.g., CBF trigger 545) to the second AP 205 in response to receiving a CBF response 540 from the second AP 205. Before the transmission of the fourth message, the first AP 205 may utilize the information from the first STA 240, the second STA 240, and the second AP 205 within the CBF response 530 and the ICR 540 to update the scheduling and timing of the transmissions of each participant (e.g., AP and STA) within the TXOP. The ICR 540 may indicate the candidate group of STAs 240 that includes the availability and duration of data transmission that meet the threshold. The ICR 540 may further indicate how long the STA 240 can be used to participate in the CBF TXOP. The CBF response 530 may indicate that the second AP 205 can participate in the CBF TXOP, the group of STAs 240 that can be used to participate in the CBF TXOP, and the downlink traffic available for the second AP 205 and the group of STAs 240. For example, the first AP 205 may receive the ICR 540 and the CBF response 530 from the STA 240 and the AP 205. Upon receipt, the first AP 205 may generate a fourth message (e.g., CBF trigger) for the second AP 205 based on the CBF response 530 and the ICR 540. The first AP 205 may use the timing adjustment, frequency synchronization confirmation, phase alignment (e.g., signal-to-noise ratio, pilot measurement), resource allocation, and timing / frequency instructions from the ICR 540. Additionally, the first AP 205 may use the timing alignment information (e.g., to avoid inter-symbol interference), CSI, pilot signal, CSI feedback (e.g., phase information), beamforming weights, beamforming strategy, and spatial alignment from the CBF response 530. Based on the information from the CBR response 530 and the ICR 540, the first AP 205 may embed the information within the fourth message (e.g., CBF trigger 545).

[0134] In some examples, the CBF trigger 545 within the fourth message may be broadcast to the AP 205. The CBF trigger 545 may be a signal or broadcast for initiating, managing, or otherwise establishing a CBF transmission (e.g., CBF PPDU) for configuring the AP 205 prior to the CBF transmission. The CBF trigger 545 may include instructions for the AP 205 to participate in the CBF TXOP. The CBF trigger 545 may indicate multiple resources (e.g., time slots, frequency subcarriers, spatial streams), each AP 205 involved in the CBF TXOP, timing information, feedback instructions, beamforming instructions, and others. In some examples, the CBT trigger 545 may include a CSI request for establishing beamforming weights for the CBF PPDU. In some examples, the CBF trigger 545 may include timing and control signals for aligning each antenna of the AP 205 for the CBF PPDU. In some examples, the CBF trigger 545 may include an abort signal generated by the first AP 205 for canceling or aborting the CBF TXOP. Based on multiple factors detected by the first AP 205, the abort signal may prevent waste of resources and performance degradation of the system 500. The factors may include CSI issues (e.g., incorrect CSI, incomplete CSI feedback), AP 205 or STA 240 failures (e.g., misaligned timing, unresponsive AP 205), interference detection (e.g., external interference, self-interference), network resource allocation (e.g., priority traffic, congestion), unavailability of the STA 240 of the first AP 205 (e.g., as indicated by the ICR from the STA 240 of the first AP), availability of the second AP 205 or the STA 240 of the second AP 205 within a limited duration (e.g., as indicated by the CBF response), selection of the set of STA 240 and associated Nss of the second AP 205 (e.g., the first AP may utilize a beamforming vector that results in poor or low MCS or data rate for the STA 240 of the first AP (i.e., where the first AP 205 has to sacrifice too much of its own STA data rate to accommodate the STA 240 of the second AP)) and other factors affecting the CBF TXOP. For example, the first AP 205 may generate an abort signal in response to the CBF response 530 from the second AP based on the indication of insufficient power resources for the CBF PPDU from the ICR of the second STA 240. In another example, the first AP 205 may generate an abort signal in response to the first AP 205 detecting a failure at the AP 205 and the STA 240.

[0135] The second AP 205 may be configured to receive, retrieve, or otherwise obtain a fourth message from the first AP 205. Upon receiving the fourth message, the second AP 205 may extract the CBF trigger 545 from the fourth message to obtain information and parameters associated with the first AP 205. Using the information, the second AP 205 may adjust the timing, frequency, and control signals to synchronize with the first AP 205. For example, the second AP 205 may adjust the timing of the CDFPPDU based on the scheduling consensus and the resources available to the STA 240 (e.g., the station data capabilities 550). In another example, the second AP 205 may adjust the frequency of the CBFPPDU based on the AP capabilities data 555 and the station capabilities data 550. The CBF trigger 545 may further contain information about the preamble of the CBF PPDU. The second AP may include the CBF trigger 545 in the preamble of the CBFPPDU to ensure that both APs transmit the same preamble for the CBF PPDU, enabling the STAs of both APs to correctly decode the preamble without error.

[0136] Using the parameters of the first AP 205 and the parameters of the second AP 205, the AP 205 (e.g., the first AP) may generate (e.g., via its CBF synchronizer 515) a schedule for CBF PPDU transmission. This schedule may be a final schedule generated based on the data available to the AP 205 after a data update from the STA 240. This schedule may be a schedule completed based on the data feedback from the ICR 540 of the STA to update the information about the AP 205. For example, the second AP 205 may embed an acknowledgment of the proposed start time for the first AP and a list of identifiers of a second set of candidate stations to determine the schedule for the CBF transmission within the CBF response. The schedule may indicate the desired, selected, or optimal time (e.g., the proposed start time) for the CBF PPDU transmission to synchronize the AP 205 while minimizing interference to the AP 205.

[0137] The first AP 205 may establish, set, modify, or configure one or more settings of the first AP 205. The one or more settings may be settings for establishing or coordinating with the second AP 205 the time and frequency for transmission to the first station 240. The transmission may be a message, a request, a response to a request, or a network data packet (e.g., a packet of the spatial data stream 230). The time may be the time at which the first AP 205 will transmit the transmission to the first station 240. The time may be synchronized to the same time as the transmission from the second AP 205 to the second station 240. The time may be synchronized to a time different from the time at which the second AP 205 transmits a second transmission to the second station 240. The one or more settings may be used to cause the first AP 205 to send or transmit a transmission to the second station 240 in a second direction to partially or fully nullify interference at the second station 240. The one or more settings may configure the first AP 205 and the second AP 205 according to the scheduling of CBF PPDU transmissions.

[0138] The coordinated beamforming manager 525 or the CBF synchronizer 515 of the AP 205 may be configured to implement and manage CBF communications, including transmitting or receiving various CBF transmissions. For example, after the coordination or synchronization of the CBF TXOP, the AP 205 and the STA 240 may participate in CBF TXOP communications. These CBF transmissions may be implemented to include acknowledgments (e.g., ACK). For example, after transmitting a CBF PPDU, one or more acknowledgments (e.g., ACK) from the AP1-STA and the AP2-STA addressed by the transmitted CBF PPDU may be collected or solicited via one of the following methods. In one example, the ACK may be included in a single TB-PPDU transmitted simultaneously by both the AP1-STA and the AP2-STA after the CBF PPDU. The TB PPDU may be solicited (e.g., within an A-MPDU addressed to the STA) by individual trigger frames or fields of each STA contained in the CBF PPDU / transmission. The trigger content for the AP1-STA may be transmitted by AP1, and the trigger content for the AP2-STA may be transmitted by AP2. Each STA may occupy a different RU and / or spatial stream as specified by the trigger content it receives. The APs may signal to each other or pre-negotiate the RU or spatial stream allocated to each STA from which an ACK is solicited.

[0139] For example, after a CBF PPDU, one or more ACKs may be serially solicited in two TB PPDUs, one for AP1-STA and another for AP2-STA. In one instance, an ACK from AP1-STA may be solicited in TB-PPDU-1 immediately following the CBF transmission, where the individual trigger frame or field soliciting the ACK is contained within the A-MPDU addressed to each AP1-STA in the CBF PPDU. An ACK from AP2-STA may be solicited by a separate multi-user block acknowledgment request (MU-BAR) frame transmitted by AP2 after TB-PPDU-1, and the AP2-STA addressed by the MU-BAR responds by transmitting TB-PPDU-2 containing its ACK. In another variant, after the CBF PPDU, AP1 transmits a first MU-BAR soliciting an ACK from AP1-STA, and the AP1-STA responds to the first MU-BAR by transmitting TB-PPDU-1. After TB-PPDU-1, AP2 transmits a second MU-BAR soliciting an ACK from AP2-STA, and the AP2-STA responds to the second MU-BAR by transmitting TB-PPDU-2. Successive, adjacent, or neighboring frames in the above sequence may be separated by SIFS.

[0140] In various embodiments, the CBF request 525 or the CBF response 530 may be encapsulated as part of the ICF from AP1 or AP2, where the content of the CBF-req or CBF-resp is signaled within a user information field addressed with a particular pre-negotiated or predefined AID value. These user information fields may be processed by the AP and ignored by the AP1-STA and the AP2-STA. These fields may be signaled at the start of the ICF frame (e.g., after the common information and special user information fields, for example). The CBF adjustment message (e.g., CBF-adj) may be included or encapsulated as part of an ICR message or a standalone frame. The format of the ICR message or the standalone frame may be a multi-STA block ACK (M-STA-BA). For any CBF-TXOP frame sequence, the participating AP1-STA and AP2-STA notified by the ICF from their respective APs may be requested to remain in the receive mode, where the participating AP1-STA and AP2-STA are capable of receiving CBF PPDUs. If such a device does not receive an indication of the CBF PPDU or an upcoming PPDU (within the same TXOP) that the device desires within a predetermined or pre-negotiated duration starting from the receipt of the ICF, then such a device may be allowed to exit the receive mode and transition to the listen mode (i.e., having a limited ability that does not permit receiving CBF PPDUs) after this period. The CBF-TXOP frame sequences disclosed herein may also be applied to other forms of multi-AP coordination that utilize concurrent transmissions across two or more BSs, such as coordinated spatial reuse (CSR) and coordinated orthogonal frequency division multiple access (C-OFDMA).

[0141] Now referring to Figure 6 , an example method 600 for multi-AP coordination that provides CBF is described. For example, method 600 may be implemented to implement a configuration of CBF operations or a CBF setup. Method 600 may be implemented using, for example, system 200, system 500, or any of the features discussed in conjunction with Figures 1A to 5 . Method 600 may include acts 605 through 620. At step 605, the method may include transmitting, by a first access point (AP), a first message for initiating a transmission opportunity (TXOP) to a second AP capable of participating in coordinated beamforming (CBF) and a first set of candidate stations of the first AP. At step 610, the method may include transmitting, by the second AP, a second message to the first AP and a second set of candidate stations of the second AP identified as participating in the TXOP. At step 615, the method may include transmitting, by the second AP, a third message with a CBF response to the first AP in response to the first AP not terminating the CBF TXOP. At step 620, the method may include transmitting, by the first AP, a fourth message with a CBF trigger to the second AP in response to the second AP indicating participation in CBF in the CBF response, the CBF trigger including information about the preamble of the CBF transmission to be conveyed during the TXOP.

[0142] At step 605, the method may include a first AP (e.g., the initiating AP) transmitting a first message for initiating a transmission opportunity (TXOP) to a second AP capable of participating in coordinated beamforming (CBF) and a first set of candidate stations of the first AP. The first AP may transmit one or more messages to the second AP and the STAs of the first AP. The first message may be referred to as Msg1 (e.g., ICF for AP1-STA and for AP2). The ICF of the first AP STA may include a request providing the first AP STA with updated information regarding the availability and parameters for participating in a CBF TXOP. The portion of Msg1 for AP2 may include a CBF request.

[0143] For example, the first AP (e.g., AP1) may initiate a TXOP with a first message (e.g., Msg1). The first message (e.g., Msg1) may be addressed to the stations of the first AP (e.g., AP1-STA) and the second AP (e.g., AP2). The ICF may include data for initiating, causing, or performing the functions of the ICF, such as MU-RTS or BSRP for AP1-STA. The ICF may include or correspond to information for enhanced multi-user remote (EMLSR) communication, in-device coexistence (IDC) coordination or tuning, or power-saving settings or configurations. Msg1 may signal to at least AP1-STA or AP2 the possibility or determination of participating in CBF transmissions during this TXOP. As pre-negotiated by AP1-STA and / or AP2 with AP1, padding of the transmission (e.g., additional time slots, buffering periods, or extended guard intervals) may be included to, for example, provide AP1-STA and AP2 with additional time to process received frames and prepare for any responses.

[0144] For example, the first message may include an initial control frame (ICF) of the first set of candidate stations. The ICF may include at least one of a multi-user request to send (MU-RTS) or a beamforming sounding request (BSRP) and information regarding at least one of enhanced multi-link single radio (EMLSR), in-device coexistence (IDC), or power-saving mode. The first AP may include padding in the first message to provide the first set of candidate stations and the second AP with additional time to process the information of the first message.

[0145] In response to an ICF (e.g., Msg1), the stations of the first AP can respond with one or more Initial Control Response (ICR) messages (which can be referred to as Msg2). In response to Msg1, the ICR message (e.g., Msg2) can be transmitted by AP1-STA and optionally by AP2 to AP1. If AP1 wants to individually identify each transmitting device, then Msg2 can be implemented or transmitted based on the Triggered Physical Protocol Data Unit (TB-PPDU) format. Msg2 can be transmitted in a non-high throughput duplicate (non-HT DUP) format. The AP1-STA addressed by Msg1 can transmit an ICR (e.g., CTS / BSR) in response to the ICF from AP1, thereby indicating availability or duration, e.g., for IDC management purposes (e.g., timing different transmissions within a single device, e.g., in a shared antenna or circuitry to avoid in-device communication conflicts). For example, a first group of candidate stations can transmit one or more ICRs in response to the ICF from the first AP, the one or more ICRs indicating at least one of the availability to participate in CBF during the TXOP or the duration of data transmission for in-device coexistence (IDC) configuration.

[0146] The transmission of the ICR (e.g., Msg2) by the second AP (e.g., AP2) can depend on whether AP2 supports this capability (as pre-negotiated between the APs) or whether AP1 solicits this response from AP2 (e.g., in Msg1). When capable or when the response is solicited, the second AP (e.g., AP2) can respond to the first AP (e.g., AP1) with an ICR, e.g., as an acknowledgement of Msg1 or for media reservation, etc. The transmission parameters for the response from AP2 can include, for example, MCS, Nss, RU allocation parameters, which can be enumerated or specified in a previous transmission, e.g., (by way of example) using Msg1 (e.g., the ICF from the first AP) or via a previous negotiation between AP1 and AP2. For example, when AP2 is capable of participating in the CBF responded to with Msg2 or AP1 solicits or requests this response but AP2 does not respond (e.g., AP1 does not receive Msg2 within a predetermined time period), in such examples, the first AP (e.g., AP1) can determine that AP2 does not intend to participate in the CBF of this TXOP. The transmission of the ICR (e.g., Msg2) can include padding, which can provide or allow AP1 to have additional duration to process the received frame (e.g., AP1 can specify a longer duration or length for Msg2 in Msg1), or can provide AP2 with additional time to prepare or generate Msg3 (e.g., the initial CBF response). For example, AP2 can request that a specific duration (e.g., a longer duration or time length) be specified for Msg2 in Msg1 (e.g., via a previous negotiation with AP1) to allow for processing time adjustment.

[0147] At step 610, the method may include transmitting, by a second AP, a second message to a first AP and a second group of candidate stations identified as participating in the TXOP. The second message may be Msg3 (e.g., ICF for AP2-STA and CBF request for AP1). For example, the second AP (e.g., AP2) may transmit Msg3 (e.g., based on the presence of traffic, applicability of CBF, etc.) addressed to AP1 and any candidate AP2-STA that the second AP may identify as participating in the current TXOP. The second AP may transmit to AP1 a preliminary or initial CBF response indicating whether it can participate in CBF (e.g., an initial CBF response, which may also be referred to as CBF-resp-init). More information about the participating AP2-STA, for example, may be missing in the preliminary or initial CBF response. The initial or preliminary CBF response may be provided to the first AP to provide available information or data to start the synchronization process while collecting additional data from the STAs (e.g., while waiting for ICR from the STAs). For example, if an AP2-STA is addressed, then Msg3 may perform the function of ICF for these STAs. Padding (e.g., pre-negotiated by the addressed AP2-STA and / or between AP1 and AP2) may be included to provide additional time for the addressed AP2-STA and AP1 to process the received frame and prepare for any response. For example, the second AP is configured to indicate to the first AP and the second group of candidate stations via the second message (e.g., Msg3) that the second AP will participate in CBF during the TXOP.

[0148] For example, an ICR (e.g., Msg4) may be transmitted to AP2 by any AP2-STA addressed by the ICF of AP2 and by AP1 or in response to Msg3. Msg4 (e.g., ICR from an AP2 STA) may be transmitted in TB-PPDU format (e.g., as specified by AP2 in Msg3) because individual responses may differ in content and AP2 should be able to correctly decode each response. If any AP2-STA is addressed by Msg3, then such STA may respond with Msg4 containing an ICR, which may indicate any combination of availability or duration (e.g., for IDC purposes). For example, one or more stations in the second group of candidate stations (e.g., of the second AP) may transmit one or more responses (e.g., ICR) in response to an indication by the second AP via the second message (e.g., Msg3), the one or more responses indicating at least one of availability to participate in CBF during the TXOP or duration of data transmission for in-device coexistence (IDC) configuration.

[0149] AP1 can transmit a CBF request for AP2 (e.g., CBF-req) and signal information regarding participating AP1-STAs (e.g., based on the ICR from the AP1-STA in Msg2) and request information regarding participating AP2-STAs. For example, the CBF request from AP1 can indicate that the CBF TXOP is aborted / terminated (e.g., based on the ICR feedback from the AP1-STA in Msg2, which indicates that due to IDC requirements, one or more AP1-STAs are not available for part or all of this TXOP). The CBF request can also indicate various TB-PPDU transmission parameters for AP1 (e.g., MCS, Nss, RU allocation), any of which can be pre-specified, e.g., as part of Msg3, or via prior negotiation between AP1 and AP2. Padding can be included, which can provide AP2 with additional time to process the received frame (e.g., AP2 can specify a longer duration or length for Msg4 in Msg3).

[0150] At step 615, the method can include the second AP transmitting a third message with a CBF response to the first AP in response to the first AP not terminating the CBF TXOP. The third message can be Msg5. For example, if AP1 does not terminate the CBF TXOP in Msg4, then AP2 can transmit Msg5 containing the CBF-resp for AP1. Signal information regarding participating AP2-STAs is signaled. Alternatively, this can also signal that AP2 is not participating in CBF (e.g., based on ICR feedback from the AP2-STA indicating that due to IDC requirements, one or more AP2-STAs are not available for part or all of this TXOP). Padding can be included (e.g., as pre-negotiated between AP1 and AP2) to provide AP1 with additional time to process the received frame.

[0151] For example, one or more stations in the second group of candidate stations (e.g., STAs of AP2) can transmit one or more responses in response to an indication by AP2 via the second message (Msg3 containing the ICF of the AP2 STA), the one or more responses indicating at least one of the availability of participating in CBF during the TXOP or the duration of data transmission for an in-device coexistence (IDC) configuration.

[0152] At step 620, the method may include the first AP transmitting a fourth message with a CBF trigger to the second AP in response to the second AP indicating participation in the CBF in the CBF response, the CBF trigger including information about the preamble of the CBF transmission communicated during the TXOP. The fourth message may include, for example, Msg6 (e.g., CBF trigger). For example, if AP2 indicates participation in the CBF in the CBF-resp (in Msg5), then AP1 transmits Msg6 to AP2 that may include the CBF trigger. The CBF trigger may signal the preamble content for the CBF transmission and enable AP2 to synchronize with AP1 (e.g., align the start time of the CBF PPDU, estimate and compensate for the frequency offset of AP2 relative to AP1, etc.). Padding may be included (e.g., as pre-negotiated between AP1 and AP2) to provide AP2 with additional time to process the received frame. AP1 and AP2 initiate CBF PPDU transmission after Msg6 with the same preamble content to ensure correct decoding at the STA.

[0153] The CBF trigger may include information about the preamble that includes the content of the preamble for synchronizing the timing of the CBF transmission with at least one of the first AP or the second AP, such as information about padding, IDC, or MCS. For example, the content of the preamble includes at least one of information about the start time of the CBF physical protocol data unit (PPDU) of the CBF transmission or information about the frequency offset between the first AP and the second AP. The first AP may include in the CBF trigger an adjustment to a CBF request previously transmitted by the first AP, the adjustment determined based on feedback from stations in the first set of candidate stations about the availability of participating in the CBF during the TXOP. The adjustment may include updated parameters (e.g., updated station capability data or AP capability data) that may be adjusted based on any one or more of Msg2, Msg3, Msg4, or Msg5. In some embodiments, AP1 may include in the CBF trigger an indication that the CBF TXOP of the second AP has been cancelled. The indication may be transmitted to one or more STAs of the first AP and the second AP to indicate the CBF TXOP cancellation (e.g., in response to updated data or parameters from the STA or AP).

[0154] Showing the method 600 Figure 6 Any consecutive, adjacent, or neighboring frames in may be separated by SIF. AP1 and AP2 initiate CBF PPDU transmission after Msg6 with the same preamble content to ensure correct decoding at the STA.

[0155] References to "or" may be construed as inclusive such that any term described using "or" may indicate any one of a single, more than one, and all of the described terms. References to at least one of a list of joined terms may be construed as inclusive or to indicate any one of a single, more than one, and all of the described terms. For example, a reference to "at least one of 'A' and 'B'" may include only 'A', only 'B', and both 'A' and 'B'. Such references used in conjunction with "comprising" or other open terms may include additional items.

[0156] It should be noted that, for the purpose of identifying or differentiating one from another or others, some paragraphs of this disclosure may refer to terms such as "first" and "second" with respect to a subset of transmission space streams, probe frames, responses, and devices. These terms are not intended to associate entities (e.g., a first device and a second device) only in terms of time or sequence, but in some cases, these entities may include such a relationship. These terms also do not limit the number of possible entities (e.g., STA, AP, beamformer, and / or beamformee) that may operate in a system or environment. It should be understood that the above system may provide multiple of any or each of those components, and these components may be provided on a single machine or, in some embodiments, on multiple machines in a distributed system. Additionally, bit field positions may change, and multi-bit words may be used. Further, the above system and method may be provided as one or more computer-readable programs or executable instructions embodied on or in one or more articles of manufacture (e.g., floppy disk, hard disk, CD-ROM, flash card, PROM, RAM, ROM, or magnetic tape). The program may be implemented in any programming language (e.g., LISP, PERL, C, C++, C#) or in any byte code language (e.g., JAVA). The software program or executable instructions may be stored as object code on or in one or more articles of manufacture.

[0157] Although the written description of the methods and systems above enables one of ordinary skill in the art to make and use their embodiments, one of ordinary skill in the art will understand and appreciate that there are variations, combinations, and equivalents to the specific embodiments, methods, and examples herein. Thus, the methods and systems of this disclosure should not be limited by the above embodiments, methods, and examples, but rather by all embodiments and methods within the scope and spirit of this disclosure.

Claims

1. A system, comprising: A first access point AP, configured to: Transmit a first message for initiating a transmission opportunity TXOP to a second AP capable of participating in coordinated beamforming CBF and a first group of candidate stations of the first AP, Wherein the second AP is configured to: Transmit a second message to the first AP and a second group of candidate stations of the second AP identified as participating in the TXOP; Wherein in response to the first AP not terminating the CBF TXOP, the second AP transmits a third message with a CBF response to the first AP; Wherein in response to the second AP indicating participation in CBF in the CBF response, the first AP transmits a fourth message with a CBF trigger to the second AP, the CBF trigger including information about the preamble of the CBF transmission during the TXOP.

2. The system according to claim 1, wherein the information about the preamble includes the content of the preamble for synchronizing the timing of the CBF transmission with at least one of the first AP or the second AP.

3. The system according to claim 2, wherein the content of the preamble includes at least one of information about the start time of the CBF physical protocol data unit PPDU of the CBF transmission or information about the frequency offset between the first AP and the second AP.

4. The system according to claim 1, wherein the first message includes an initial control frame ICF of the first group of candidate stations, the ICF including at least one of a multi-user request to send MU-RTS or a buffer status report poll BSRP and information about at least one of enhanced multi-link single radio EMLSR, in-device coexistence IDC, or power saving mode.

5. The system according to claim 4, wherein the first AP includes padding in the first message to provide additional time for the first group of candidate stations and the second AP to process the first message.

6. The system according to claim 1, wherein the first group of candidate stations transmits one or more messages in response to the first message, the one or more messages being configured in one of the format of a triggered physical protocol data unit TB-PPDU or a non-high throughput duplicate non-HT DUP format.

7. The system according to claim 6, wherein the first group of candidate stations transmits one or more initial control responses ICRs in response to an initial control frame ICF from the first AP, the one or more ICRs indicating at least one of the availability of participating in CBF during the TXOP or the duration of data transmission for in-device coexistence IDC configuration.

8. The system according to claim 1, wherein the second AP is configured to indicate via the second message to the first AP and the second group of candidate stations that the second AP will participate in the CBF during the TXOP.

9. The system according to claim 8, wherein one or more stations in the second set of candidate stations are configured to transmit one or more responses in response to the indication by the second AP via the second message, the one or more responses indicating at least one of the availability of participating in CBF during the TXOP or the duration of data transmission for in-device coexistence (IDC) configuration.

10. The system according to claim 1, wherein the second AP transmits the third message to the first AP, the third message including a CBF response having information about the second set of candidate stations and an adjustment to a previous transmission CBF response to the first message from the first AP, the adjustment being generated based on feedback from the second set of candidate stations.

11. The system according to claim 1, wherein the first AP is configured to include, in the CBF trigger, an adjustment to a CBF request previously transmitted by the first AP, the adjustment being determined based on feedback from stations in the first set of candidate stations regarding the availability of participating in CBF during the TXOP.

12. The system according to claim 1, wherein the first AP is configured to include, in the CBF trigger, an indication of the termination of the CBF TXOP of the second AP.

13. A method, comprising: transmitting, by a first access point (AP), a first message for initiating a transmission opportunity (TXOP) to a second AP capable of participating in coordinated beamforming (CBF) and a first set of candidate stations of the first AP; transmitting, by the second AP, a second message to the first AP and a second set of candidate stations of the second AP identified as participating in the TXOP; transmitting, by the second AP, a third message having a CBF response to the first AP in response to the first AP not terminating the CBF TXOP; transmitting, by the first AP, a fourth message having a CBF trigger to the second AP in response to the second AP indicating participation in CBF in the CBF response, the CBF trigger including information about a preamble of a CBF transmission communicated during the TXOP.

14. The method according to claim 13, comprising including, by the first AP, in the information about the preamble, content of a preamble for synchronizing the timing of the CBF transmission with a preamble of at least one of the first AP or the second AP, wherein the content of the preamble includes at least one of information about a start time of a CBF physical protocol data unit (PPDU) of the CBF transmission or information about a frequency offset between the first AP and the second AP.

15. The method according to claim 13, comprising: including, by the first AP, in the first message, an initial control frame (ICF) of the first set of candidate stations, the ICF including at least one of a multi-user request to send (MU-RTS) or a buffer status report poll (BSRP) and information about at least one of enhanced multi-link single radio (EMLSR), in-device coexistence (IDC), or power saving mode; and The first AP includes padding in the first message to provide additional time for the first group of candidate stations and the second AP to process the first message.

16. The method according to claim 13, comprising: Transmitting, by the first group of candidate stations in response to the first message, one or more messages configured to be in a format of a triggered physical protocol data unit (TB-PPDU) or a format of non-high throughput duplicate (non-HT DUP).

17. The method according to claim 16, comprising: Transmitting, by the first group of candidate stations in response to an initial control frame (ICF) from the first AP, one or more initial control responses (ICR) indicating at least one of the availability of participating in the CBF during the TXOP or the duration of data transmission for in-device coexistence (IDC) configuration.

18. The method according to claim 13, comprising: Transmitting, by the second AP to the first AP via the second message, an indication that the second AP of the second group of candidate stations will participate in the CBF during the TXOP; and Transmitting, by one or more stations of the second group of candidate stations in response to the indication of the second AP via the second message, one or more responses indicating at least one of the availability of participating in the CBF during the TXOP or the duration of data transmission for in-device coexistence (IDC) configuration.

19. The method according to claim 13, comprising: Transmitting, by the second AP to the first AP, the third message, the third message including a CBF response having information about the second group of candidate stations and an adjustment to a previous transmission CBF response to the first message from the first AP, the adjustment being generated based on feedback from the second group of candidate stations.

20. A system, comprising: A first access point (AP) configured to: Transmit a first message for initiating a transmission opportunity (TXOP) to a second AP capable of participating in coordinated beamforming (CBF) and a first group of candidate stations of the first AP, the first message including an initial control frame including a beamforming sounding request (BSRP) and information about establishing the CBF, wherein the second AP is configured to: Transmit a second message to the first AP and a second group of candidate stations identified as participating in the TXOP, the second message including one or more parameters of the second group of candidate stations; wherein in response to the first AP not terminating the CBF TXOP in response to the second message, the second AP transmits a third message having a CBF response to the first AP; In response to the second AP indicating participation in the CBF in the CBF response, the first AP transmits a fourth message with a CBF trigger to the second AP, where the CBF trigger includes information about the content of the preamble of the CBF transmission communicated during the TXOP, and the information about the content of the preamble includes information for synchronizing the start time of the CBF transmission.

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