Channel sounding in OBSS scenario in wireless LAN system

Abstract

The present disclosure relates to channel sounding in an overlapping basic service set (OBSS) scenario in a wireless LAN system. According to an embodiment of the present disclosure, a method performed by a first access point (AP) configured to operate in a wireless LAN system comprises the steps of: initiating a negotiation procedure for multi-AP cooperation with a second AP; in the negotiation procedure, acquiring information about one or more neighboring STAs connected to the second AP; on the basis of the information about the one or more neighboring STAs, transmitting a channel measurement signal to the one or more neighboring STAs; after transmitting the channel measurement signal, acquiring channel information about a channel between the first AP and the one or more neighboring STAs; and on the basis of the channel information, performing transmission related to the multi-AP cooperation to the one or more STAs connected to the first AP.

Description

Channel Sounding in OBSS Scenarios in Wireless LAN Systems

[0001] The present disclosure relates to channel sounding in an overlapping basic service set (OBSS) scenario in a wireless LAN system.

[0002] Next-generation Wi-Fi (e.g., IEEE 802.11be and / or later) aims to support ultra-high reliability in signal transmission to STAs, and various technologies are being considered to support high throughput, low latency, and extended range.

[0003] For example, in wireless LAN systems, it is essential for a transmitting device to obtain channel state information (CSI) from a receiving device to perform beamforming for space division multiplexing (SDM) or multi-user MIMO (MU-MIMO). For this purpose, Null Data Packet (NDP) and channel sounding protocols are used. These channel sounding protocols may also be required in OBSS scenarios.

[0004] The present disclosure provides a method and apparatus for channel sounding in an OBSS scenario in a wireless LAN system.

[0005] According to an embodiment of the present disclosure, a method performed by a first access point (AP) configured to operate in a wireless LAN system includes: initiating a negotiation procedure for multi-AP cooperation with a second AP; acquiring information about one or more neighboring STAs connected to the second AP in the negotiation procedure; transmitting a channel measurement signal to the one or more neighboring STAs based on the information about the one or more neighboring STAs; acquiring channel information about a channel between the first AP and the one or more neighboring STAs after transmitting the channel measurement signal; and performing a transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information.

[0006] According to an embodiment of the present disclosure, a method performed by an STA connected to a second AP configured to operate in a wireless LAN system comprises: receiving a channel measurement signal from a first AP; performing channel measurement on a channel between the first AP and the STA based on the channel measurement signal; and transmitting channel information including a result of the channel measurement to the first AP, wherein the first AP is configured to perform operations including: initiating a negotiation procedure for multi-AP cooperation with the second AP; in the negotiation procedure, acquiring information about the STA; transmitting the channel measurement signal to the STA based on the information about the STA; and performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information.

[0007] In various embodiments, devices for implementing the above-described methods are provided.

[0008] The present disclosure may have various advantageous effects.

[0009] For example, more efficient OBSS channel sounding can be performed using C-TDMA technology without requiring each AP to perform individual sounding procedures with individually acquired TXOPs.

[0010] The beneficial effects that can be achieved through specific embodiments of the present disclosure are not limited to the beneficial effects listed above. For example, various technical effects may be understood and / or derived from the present disclosure by those skilled in the art. Therefore, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of the present disclosure.

[0011] FIG. 1 illustrates an example of a transmitting device and / or a receiving device of the present disclosure.

[0012] Figure 2 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

[0013] Figure 3 is a diagram illustrating a general link setup process.

[0014] Figure 4 illustrates an embodiment of multi-link (ML).

[0015] FIG. 5 illustrates a modified example of a transmitting device and / or a receiving device of the present disclosure.

[0016] FIG. 6 illustrates an example of a PPDU (physical protocol data unit or physical layer (PHY) protocol data unit) transmitted / received by an STA of the present disclosure.

[0017] Figure 7 shows the operation according to UL-MU.

[0018] Figure 8 shows an example of an OBSS scenario.

[0019] Figure 9 shows an example of a channel sounding procedure.

[0020] Figure 10 shows an example of a header of a MAC frame.

[0021] Figure 11 shows the trigger frame format.

[0022] Figure 12 shows an example of the user information field format of MU-RTS TXS TF.

[0023] Figure 13 shows an example of multi-AP operation based on Co-TDMA between APs.

[0024] FIG. 14 illustrates an example of a method performed by a first AP for channel sounding in an OBSS scenario according to an embodiment of the present disclosure.

[0025] FIG. 15 illustrates an example of signal flow between a STA connected to a first AP and a second AP for channel sounding in an OBSS scenario according to an embodiment of the present disclosure.

[0026] FIG. 16 illustrates a first example of an OBSS channel TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0027] FIG. 17 illustrates a second example of an OBSS channel TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0028] FIG. 18 illustrates a third example of an OBSS channel TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0029] FIG. 19 illustrates a fourth example of an OBSS channel TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0030] FIG. 20 illustrates a first example of an OBSS channel non-TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0031] FIG. 21 illustrates a second example of an OBSS channel non-TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0032] FIG. 22 illustrates a third example of an OBSS channel non-TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0033] FIG. 23 illustrates a fourth example of an OBSS channel non-TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0034] In this disclosure, “A or B” can mean “only A,” “only B,” or “both A and B.” In other words, “A or B” in this disclosure can be interpreted as “A and / or B.” For example, “A, B or C” in this disclosure can mean “only A,” “only B,” “only C,” or “any combination of A, B, and C.”

[0035] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "A and / or B." Accordingly, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0036] In the present disclosure, “at least one of A and B” may mean “only A,” “only B,” or “both A and B.” Additionally, in the present disclosure, the expressions “at least one of A or B” or “at least one of A and / or B” may be interpreted identically to “at least one of A and B.”

[0037] In addition, parentheses used in the present disclosure may mean “for example.” Specifically, when “control information (UHR-Signal field)” is indicated, the “UHR-Signal field” may be suggested as an example of “control information.” In other words, the “control information” of the present disclosure is not limited to the “UHR-Signal field,” and the “UHR-Signal field” may be suggested as an example of “control information.” In addition, even when indicated as “control information (UHR-Signal field),” the “UHR-Signal field” may be suggested as an example of “control information.”

[0038] Additionally, as used herein, “a / an” can mean “at least one” or “one or more.” Additionally, terms ending in “(s)” can mean “at least one” or “one or more.”

[0039] Additionally, the expressions “based on” or “on the basis of” or “according to” used in this disclosure mean “based at least in part on” and do not mean “based solely on.”

[0040] Technical features individually described in one drawing in this disclosure may be implemented individually or simultaneously.

[0041] The following examples of the present disclosure can be applied to various wireless communication systems. For example, the following examples of the present disclosure can be applied to a wireless local area network (WLAN) system. For example, the present disclosure can be applied to the IEEE 802.11a / g / n / ac / ax / be / bn standards. Furthermore, the examples of the present disclosure can be applied to the Ultra High Reliability (UHR) standard or a next-generation wireless LAN standard that enhances IEEE 802.11bn. Furthermore, the examples of the present disclosure can be applied to a mobile communication system. For example, the examples of the present disclosure can be applied to a mobile communication system based on the Long Term Evolution (LTE) standard and its evolution based on the 3rd Generation Partnership Project (3GPP) standard.

[0042] In order to explain the technical features of the present disclosure, technical features to which the present disclosure can be applied are described below.

[0043] FIG. 1 illustrates an example of a transmitting device and / or a receiving device of the present disclosure.

[0044] An example of FIG. 1 can perform various technical features described below. FIG. 1 relates to at least one STA (station). For example, the STA (110, 120) of the present disclosure may also be referred to by various names such as a mobile terminal, a wireless device, a Wireless Transmit / Receive Unit (WTRU), a User Equipment (UE), a Mobile Station (MS), a Mobile Subscriber Unit, or simply a user. The STA (110, 120) of the present disclosure may also be referred to by various names such as a network, a base station, a Node-B, an access point (AP), a repeater, a router, a relay, etc. The STA (110, 120) of the present disclosure may also be referred to by various names such as a receiving apparatus, a transmitting apparatus, a receiving STA, a transmitting STA, a receiving device, a transmitting device, etc.

[0045] For example, STA (110, 120) may perform the role of an AP (access point) or a non-AP role. That is, STA (110, 120) of the present disclosure may perform the functions of an AP and / or a non-AP. In the present disclosure, an AP may also be indicated as an AP STA.

[0046] The STA (110, 120) of the present disclosure can support various communication standards other than the IEEE 802.11 standard. For example, it can support communication standards according to the 3GPP standard (e.g., LTE, LTE-A, 5G NR standard). In addition, the STA of the present disclosure can be implemented in various devices such as a mobile phone, a vehicle, a personal computer, etc. In addition, the STA of the present disclosure can support communication for various communication services such as voice calls, video calls, data communications, and autonomous driving (Self-Driving, Autonomous-Driving).

[0047] In the present disclosure, STA (110, 120) may include a medium access control (MAC) and a physical layer interface for a wireless medium that follow the provisions of the IEEE 802.11 standard.

[0048] Based on the sub-drawing (a) of Fig. 1, STA (110, 120) is described as follows.

[0049] The first STA (110) may include a processor (111), a memory (112), and a transceiver (113). The illustrated processor, memory, and transceiver may each be implemented as separate chips, or at least two blocks / functions may be implemented through a single chip.

[0050] The transceiver (113) of the first STA performs signal transmission and reception operations. Specifically, it can transmit and receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0051] For example, the first STA (110) can perform the intended operation of the AP. For example, the processor (111) of the AP can receive a signal through the transceiver (113), process the received signal, generate a transmission signal, and perform control for signal transmission. The memory (112) of the AP can store a signal received through the transceiver (113) (i.e., a reception signal) and store a signal to be transmitted through the transceiver (i.e., a transmission signal).

[0052] For example, the second STA (120) can perform the intended operation of a non-AP STA. For example, the transceiver (123) of the non-AP performs signal transmission and reception operations. Specifically, it can transmit and receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0053] For example, the processor (121) of the Non-AP STA can receive a signal through the transceiver (123), process the received signal, generate a transmission signal, and perform control for signal transmission. The memory (122) of the Non-AP STA can store a signal received through the transceiver (123) (i.e., a reception signal) and store a signal to be transmitted through the transceiver (i.e., a transmission signal).

[0054] For example, in the specification below, the operation of a device indicated as AP may be performed in the first STA (110) or the second STA (120). For example, if the first STA (110) is an AP, the operation of the device indicated as AP may be controlled by the processor (111) of the first STA (110), and a related signal may be transmitted or received through a transceiver (113) controlled by the processor (111) of the first STA (110). In addition, control information related to the operation of the AP or a transmission / reception signal of the AP may be stored in the memory (112) of the first STA (110). In addition, when the second STA (110) is an AP, the operation of the device indicated as an AP is controlled by the processor (121) of the second STA (120), and a related signal can be transmitted or received through a transceiver (123) controlled by the processor (121) of the second STA (120). In addition, control information related to the operation of the AP or the transmission / reception signal of the AP can be stored in the memory (122) of the second STA (110).

[0055] For example, in the specification below, the operation of a device indicated as a non-AP (or User-STA) may be performed in the STA (110) or the second STA (120). For example, if the second STA (120) is a non-AP, the operation of the device indicated as a non-AP may be controlled by the processor (121) of the second STA (120), and a related signal may be transmitted or received through a transceiver (123) controlled by the processor (121) of the second STA (120). In addition, control information related to the operation of the non-AP or the transmission / reception signal of the AP may be stored in the memory (122) of the second STA (120). For example, if the first STA (110) is a non-AP, the operation of a device indicated as a non-AP is controlled by the processor (111) of the first STA (110), and a related signal may be transmitted or received through a transceiver (113) controlled by the processor (111) of the first STA (120). In addition, control information related to the operation of the non-AP or the transmission / reception signal of the AP may be stored in the memory (112) of the first STA (110).

[0056] In the following specification, devices called (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) Terminal, (transmitting / receiving) device, (transmitting / receiving) apparatus, network, etc. may refer to the STA (110, 120) of FIG. 1. For example, devices indicated as (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) Terminal, (transmitting / receiving) device, (transmitting / receiving) apparatus, network, etc. without specific drawing symbols may also refer to the STA (110, 120) of FIG. 1. For example, in the example below, the operation of various STAs transmitting and receiving signals (e.g., PPPDU) may be performed by the transceiver (113, 123) of FIG. 1. In addition, in the example below, the operation of various STAs generating transmission and reception signals or performing data processing or calculations in advance for transmission and reception signals may be performed by the processor (111, 121) of FIG. 1.For example, an example of an operation for generating a transmission / reception signal or performing data processing or operation in advance for a transmission / reception signal may include 1) an operation for determining / obtaining / configuring / computing / decoding / encoding bit information of a subfield (SIG, STF, LTF, Data) field included in a PPDU, 2) an operation for determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) used for a subfield (SIG, STF, LTF, Data) field included in a PPDU, 3) an operation for determining / configuring / obtaining a specific sequence (e.g., a pilot sequence, an STF / LTF sequence, an extra sequence applied to SIG) used for a subfield (SIG, STF, LTF, Data) field included in a PPDU, 4) a power control operation and / or a power saving operation applied to an STA, 5) an operation related to determining / obtaining / configuring / computing / decoding / encoding an ACK signal, etc. Additionally, in the examples below, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs for determining / acquiring / configuring / computing / decoding / encoding transmission / reception signals can be stored in the memory (112, 122) of FIG. 1.

[0057] The device / STA of the sub-drawing (a) of FIG. 1 described above can be modified as in the sub-drawing (b) of FIG. 1. Hereinafter, the STA (110, 120) of the present disclosure will be described based on the sub-drawing (b) of FIG. 1.

[0058] For example, the transceiver (113, 123) illustrated in sub-drawing (b) of FIG. 1 may perform the same function as the transceiver illustrated in sub-drawing (a) of FIG. 1 described above. For example, the processing chip (114, 124) illustrated in sub-drawing (b) of FIG. 1 may include a processor (111, 121) and a memory (112, 122). The processor (111, 121) and the memory (112, 122) illustrated in sub-drawing (b) of FIG. 1 may perform the same function as the processor (111, 121) and the memory (112, 122) illustrated in sub-drawing (a) of FIG. 1 described above.

[0059] The mobile terminal, wireless device, Wireless Transmit / Receive Unit (WTRU), User Equipment (UE), Mobile Station (MS), Mobile Subscriber Unit, user, user STA, network, Base Station, Node-B, Access Point (AP), repeater, router, relay, receiving device, transmitting device, receiving STA, transmitting STA, receiving Device, transmitting Device, receiving Apparatus, and / or transmitting Apparatus described below may refer to the STA (110, 120) illustrated in the sub-drawings (a) / (b) of FIG. 1, or may refer to the processing chip (114, 124) illustrated in the sub-drawing (b) of FIG. 1. That is, the technical feature of the present disclosure may be performed in the STA (110, 120) illustrated in the sub-drawings (a) / (b) of FIG. 1, or may be performed only in the processing chip (114, 124) illustrated in the sub-drawings (b) of FIG. 1. For example, the technical feature that the transmitting STA transmits a control signal may be understood as a technical feature that the control signal generated in the processor (111, 121) illustrated in the sub-drawings (a) / (b) of FIG. 1 is transmitted through the transceiver (113, 123) illustrated in the sub-drawings (a) / (b) of FIG. 1. Alternatively, the technical feature that the transmitting STA transmits a control signal may be understood as a technical feature that the control signal to be transmitted to the transceiver (113, 123) is generated in the processing chip (114, 124) illustrated in the sub-drawings (b) of FIG. 1.

[0060] For example, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal being received by a transceiver (113, 123) illustrated in sub-drawing (a) of FIG. 1. Alternatively, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal received by a transceiver (113, 123) illustrated in sub-drawing (a) of FIG. 1 being acquired by a processor (111, 121) illustrated in sub-drawing (a) of FIG. 1. Alternatively, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal received by a transceiver (113, 123) illustrated in sub-drawing (b) of FIG. 1 being acquired by a processing chip (114, 124) illustrated in sub-drawing (b) of FIG.

[0061] Referring to the sub-drawing (b) of FIG. 1, software code (115, 125) may be included in the memory (112, 122). The software code (115, 125) may include instructions that control the operation of the processor (111, 121). The software code (115, 125) may be included in various programming languages.

[0062] The processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device. The processor may be an application processor (AP). For example, the processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). For example, the processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may be a SNAPDRAGON® series processor manufactured by Qualcomm®, an EXYNOS® series processor manufactured by Samsung®, an A series processor manufactured by Apple®, a HELIO® series processor manufactured by MediaTek®, an ATOM® series processor manufactured by INTEL®, or an enhanced processor thereof.

[0063] In the present disclosure, uplink may mean a link for communication from a non-AP STA to an AP STA, and uplink PPDU / packet / signal, etc. may be transmitted through the uplink. In addition, in the present disclosure, downlink may mean a link for communication from an AP STA to a non-AP STA, and downlink PPDU / packet / signal, etc. may be transmitted through the downlink.

[0064] Figure 2 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

[0065] The upper part of Figure 2 shows the structure of the infrastructure BSS (basic service set) of IEEE (institute of electrical and electronic engineers) 802.11.

[0066] Referring to the top of FIG. 2, the wireless LAN system may include one or more infrastructure BSSs (200, 205) (hereinafter, BSS). The BSSs (200, 205) are a collection of APs and STAs, such as an access point (AP) 225 and a station (STA1, 200-1), that have successfully synchronized and can communicate with each other, and are not a concept that designates a specific area. The BSS (205) may also include one or more STAs (205-1, 205-2) that can be associated with one AP (230).

[0067] A BSS may include at least one STA, an AP (225, 230) providing a distribution service, and a distribution system (DS, 210) connecting multiple APs.

[0068] A distributed system (210) can connect multiple BSSs (200, 205) to implement an extended service set (ESS, 240). An ESS (240) can be used as a term to indicate a network formed by connecting one or more APs through the distributed system (210). APs included in a single ESS (240) can have the same SSID (service set identification).

[0069] The portal (portal, 220) can act as a bridge to connect a wireless LAN network (IEEE 802.11) to another network (e.g., 802.X).

[0070] In a BSS such as the upper part of Fig. 2, a network between APs (225, 230) and a network between APs (225, 230) and STAs (200-1, 205-1, 205-2) can be implemented. However, it may also be possible to establish a network and perform communication between STAs without an AP (225, 230). A network that establishes a network and performs communication between STAs without an AP (225, 230) is defined as an ad-hoc network or an independent basic service set (IBSS).

[0071] The bottom of Figure 2 is a conceptual diagram showing IBSS.

[0072] Referring to the bottom of Fig. 2, the IBSS is a BSS that operates in ad-hoc mode. Since the IBSS does not include an AP, there is no centralized management entity. That is, in the IBSS, the STAs (250-1, 250-2, 250-3, 255-4, 255-5) are managed in a distributed manner. In the IBSS, all STAs (250-1, 250-2, 250-3, 255-4, 255-5) can be mobile STAs, and access to the distributed system is not permitted, forming a self-contained network.

[0073] Figure 3 is a diagram illustrating a general link setup process.

[0074] In step S310, the STA may perform a network discovery operation. This network discovery operation may include scanning by the STA. That is, for the STA to access the network, it must find a network it can join. Before joining a wireless network, the STA must identify compatible networks. The process of identifying networks in a specific area is called scanning. Scanning methods include active scanning and passive scanning.

[0075] Figure 3 illustrates a network discovery operation that includes an active scanning process as an example. In active scanning, an STA performing scanning transmits a probe request frame to discover which APs exist in the vicinity while moving between channels and waits for a response. A responder transmits a probe response frame to the STA that transmitted the probe request frame in response to the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame in the BSS of the channel being scanned. In a BSS, the AP transmits the beacon frame, so the AP becomes the responder. In an IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not constant. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning (i.e., transmitting and receiving probe requests / responses on channel 2) in the same manner.

[0076] Although not shown in the example of FIG. 3, the scanning operation can also be performed in a passive scanning manner. An STA performing scanning based on passive scanning can wait for a beacon frame while moving between channels. A beacon frame is one of the management frames in IEEE 802.11. It announces the presence of a wireless network and is periodically transmitted so that the scanning STA can find the wireless network and participate in the wireless network. In the BSS, the AP periodically transmits the beacon frame, and in the IBSS, the STAs within the IBSS take turns transmitting the beacon frame. When the scanning STA receives a beacon frame, it stores the information about the BSS included in the beacon frame and moves to another channel, recording the beacon frame information on each channel. An STA that receives a beacon frame can store the BSS-related information included in the received beacon frame, move to the next channel, and perform scanning on the next channel in the same manner.

[0077] An STA that discovers a network can perform an authentication process through step S320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation of step S340 described below. The authentication process of S320 may include a process in which the STA transmits an authentication request frame to the AP, and the AP responds by transmitting an authentication response frame to the STA. The authentication frame used for the authentication request / response corresponds to a management frame.

[0078] The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), and a Finite Cyclic Group.

[0079] An STA can transmit an authentication request frame to an AP. The AP can determine whether to grant authentication to the STA based on the information contained in the received authentication request frame. The AP can provide the result of the authentication process to the STA via an authentication response frame.

[0080] A successfully authenticated STA may perform an association process based on step S330. The association process includes a process in which the STA transmits an association request frame to the AP, and the AP transmits an association response frame to the STA in response. For example, the association request frame may include information related to various capabilities, such as a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, RSN, mobility domain, supported operating classes, a Traffic Indication Map Broadcast request, and interworking service capabilities. For example, the association response frame may contain information related to various capabilities, status codes, Association ID (AID), supported rates, Enhanced Distributed Channel Access (EDCA) parameter sets, Received Channel Power Indicator (RCPI), Received Signal to Noise Indicator (RSNI), mobility domains, timeout interval (association comeback time), overlapping BSS scan parameters, TIM broadcast response, QoS maps, etc.

[0081] In step S340, the STA may perform a security setup process. The security setup process of step S340 may include, for example, a process of setting up a private key through a four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame.

[0082] Figure 4 illustrates an example of a multi-link (ML).

[0083] As illustrated in FIG. 4, multiple multi-link devices (MLDs) can communicate over a remote link. The MLDs can be categorized into AP MLDs including multiple AP STAs and non-AP MLDs including multiple non-AP STAs. That is, the AP MLD can include affiliated APs (i.e., AP STAs), and the non-AP MLD can include affiliated STAs (i.e., non-AP STAs, or user-STAs).

[0084] A multilink may include a first link and a second link, and different channels / subchannels / frequency resources may be allocated to the first and second links. The first and second multilinks may be identified through a link ID of 4 bits (or other n bits). The first and second links may be configured in the same 2.4 GHz, 5 GHz, or 6 GHz band. Alternatively, the first link and the second link may be configured in different bands.

[0085] The AP MLD of FIG. 4 includes three affiliated APs. In the example of FIG. 4, AP1 may operate in the 2.4 GHz band, AP2 may operate in the 5 GHz band, and AP3 may operate in the 6 GHz band. In the example of FIG. 4, the first link in which AP1 and non-AP1 operate may be defined as a channel / subchannel / frequency resource within the 2.4 GHz band. Furthermore, in the example of FIG. 4, the second link in which AP2 and non-AP2 operate may be defined as a channel / subchannel / frequency resource within the 5 GHz band. Furthermore, in the example of FIG. 4, the third link in which AP3 and non-AP3 operate may be defined as a channel / subchannel / frequency resource within the 6 GHz band.

[0086] In the example of FIG. 4, AP1 may initiate a multi-link setup procedure (ML setup procedure) by transmitting an Association Request frame to non-AP STA1. In the example of FIG. 4, non-AP STA1 may transmit an Association Response frame in response to the Association Request frame. Each AP (e.g., AP1 / 2 / 3) illustrated in FIG. 4 may be identical to the AP illustrated in FIG. 1 and / or FIG. 2, and each non-AP (e.g., non-AP1 / 2 / 3) illustrated in FIG. 4 may be identical to the STA (i.e., user-STA or non-AP STA) illustrated in FIG. 1 and / or FIG. 2.

[0087] The specific features of the present disclosure are not limited to the specific features of FIG. 4. That is, the number of links can be defined in various ways, and multiple links can be defined in various ways within at least one band.

[0088] FIG. 5 illustrates a modified example of a transmitting device and / or a receiving device of the present disclosure.

[0089] The devices (e.g., AP STA, non-AP STA) illustrated in FIGS. 1 to 4 may be modified as illustrated in FIG. 5. The transceiver (530) of FIG. 5 may be identical to the transceivers (113, 123) of FIG. 1. The transceiver (530) of FIG. 5 may include a receiver and a transmitter.

[0090] The processor (510) of FIG. 5 may be identical to the processor (111, 121) of FIG. 1. Alternatively, the processor (510) of FIG. 5 may be identical to the processing chip (114, 124) of FIG. 1.

[0091] The memory (150) of FIG. 5 may be the same as the memory (112, 122) of FIG. 1. Alternatively, the memory (150) of FIG. 5 may be a separate external memory different from the memory (112, 122) of FIG. 1.

[0092] Referring to FIG. 5, a power management module (511) manages power to a processor (510) and / or a transceiver (530). A battery (512) supplies power to the power management module (511). A display (513) outputs results processed by the processor (510). A keypad (514) receives input to be used by the processor (510). The keypad (514) may be displayed on the display (513). A SIM card (515) may be an integrated circuit used to securely store an international mobile subscriber identity (IMSI) and an associated key used to identify and authenticate a subscriber in a mobile phone device, such as a mobile phone or computer.

[0093] Referring to FIG. 5, the speaker (540) can output sound-related results processed by the processor (510). The microphone (541) can receive sound-related input to be used by the processor (510).

[0094] FIG. 6 illustrates an example of a PPDU (physical protocol data unit or physical layer (PHY) protocol data unit) transmitted / received by an STA of the present disclosure.

[0095] The STA (e.g., AP STA, non-AP STA, AP MLD, non-AP MLD) of the present disclosure can transmit and / or receive the PPDU of FIG. 6. The PPDU described in the present disclosure may have, for example, the structure of FIG. 6. In addition, the PPDU described in the present disclosure may be called by various names such as a transmission PPDU, a reception PPDU, a first type PPDU, or an Nth type PPDU, etc. The PPDU described in the present disclosure can be used in a WLAN system defined according to IEEE 802.11bn and / or a next-generation WLAN system that improves upon IEEE 802.11bn.

[0096] The PPDU of FIG. 6 may be related to various PPDU types used in a UHR system. For example, the example of FIG. 6 may be used for at least one of a single-user (SU) mode / type / transmission, a multi-user (MU) mode / type / transmission, and a null data packet (NDP) mode / type / transmission related to channel sounding. For example, if the example of FIG. 6 is related to NDP, the Data field illustrated may be omitted. If the PPDU of FIG. 6 is used for a trigger-based (TB) mode, the UHR-SIG of FIG. 6 may be omitted. In other words, an STA that has received a trigger frame for UL-MU (Uplink-MU) communication may transmit a PPDU with the UHR-SIG omitted in the example of FIG. 6.

[0097] In FIG. 6, L-STF or UHR-LTF may be called a preamble or physical preamble, and may be generated / transmitted / received / acquired / decoded in the physical layer (included in the transmitting / receiving STA).

[0098] Each block illustrated in Fig. 6 may be called a field / subfield / signal, etc. The names of these fields / subfields / signals may be, as illustrated in Fig. 6, L-STF (legacy short training field), L-LTF (legacy long training field), L-SIG (legacy signal), RL-SIG (repeated L-SIG), U-SIG (Universal Signal), UHR-SIG (UHR-signal), etc.

[0099] The subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG fields in FIG. 6 may be set to 312.5 kHz, and the subcarrier spacing of the UHR-STF, UHR-LTF, and Data fields may be set to 78.125 kHz. That is, the tone index (or subcarrier index) of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG fields may be expressed in units of 312.5 kHz, and the tone index (or subcarrier index) of the UHR-STF, UHR-LTF, and Data fields may be expressed in units of 78.125 kHz.

[0100] In the PPDU of Fig. 6, L-LTF and L-STF may be identical to conventional fields (e.g., non-HT LTF and non-HT STF defined in conventional WLAN standards).

[0101] The L-SIG field of FIG. 6 may include, for example, 24 bits of bit information. For example, the 24 bits of information may include a 4 bit Rate field, a 1 bit Reserved bit, a 12 bit Length field, a 1 bit Parity bit, and a 6 bit Tail bit. For example, the 12 bit Length field may include information about the length or time duration of the PPDU. For example, the value of the 12 bit Length field may be determined based on the type of the PPDU. For example, if the PPDU is a non-HT (non-High Throughput), HT (High Throughput), VHT (Very High Throughput) PPDU, or an EHT (extremely high throughput) PPDU or UHR PPDU, the value of the Length field may be determined as a multiple of 3. For example, if the PPDU is a HE PPDU, the value of the Length field may be determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, for non-HT, HT, VHT PPDU, EHT PPDU, UHR PPDU, the value of the Length field can be determined as a multiple of 3, and for HE (High-Efficiency) PPDU, the value of the Length field can be determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, the Length field in an UHR PPDU is set to a value satisfying the condition that the remainder is zero when LENGTH is divided by 3.

[0102] For example, (non-AP and AP) STAs can apply BCC encoding based on a code rate of 1 / 2 to the 24 bits of information in the L-SIG field. Then, the transmitting STA can obtain 48 BCC coded bits. BPSK modulation can be applied to the 48 coded bits to generate 48 BPSK symbols. The transmitting STA can map the 48 BPSK symbols to positions excluding the pilot subcarriers {subcarrier index -21, -7, +7, +21} and the DC subcarrier {subcarrier index 0}. As a result, the 48 BPSK symbols can be mapped to subcarrier indices -26 to -22, -20 to -8, -6 to -1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA can additionally map the signal {-1, -1, -1, 1} to the subcarrier indices {-28, -27, +27, +28}. The above signal can be used for channel estimation for the frequency domain corresponding to {-28, -27, +27, +28}.

[0103] For example, (non-AP and AP) STA can generate RL-SIG, which is generated in the same manner as L-SIG. BPSK modulation can be applied to RL-SIG. Receiving (non-AP and AP) STA can determine whether the received PPDU is a HE PPDU, EHT PPDU, or UHR PPDU based on the presence of RL-SIG. In other words, if RL-SIG is present, receiving (non-AP and AP) STA can determine whether the received PPDU is one of HE PPDU, EHT PPDU, or UHR PPDU. In other words, if RL-SIG is not present, receiving (non-AP and AP) STA can determine whether the received PPDU is one of non-HT PPDU, HT PPDU, or VHT PPDU. In other words, the RL-SIG field is a repeat of the L-SIG field and is used to differentiate an UHR PPDU from a non-HT PPDU, HT PPDU, and VHT PPDU.

[0104] After the RL-SIG in Fig. 6, a U-SIG (Universal SIG) may be inserted. The U-SIG may be called by various names such as the first SIG field, the first SIG, the first type SIG, the control signal, the control signal field, the first (type) control signal, the common control field, and the common control signal.

[0105] A U-SIG can contain N bits of information and can include information for identifying the type of EHT PPDU. For example, a U-SIG can be formed based on two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., an OFDM symbol) for a U-SIG can have a duration of 4 microseconds. Each symbol of a U-SIG can be used to transmit 26 bits of information. For example, each symbol of a U-SIG can be transmitted and received based on 52 data tones and 4 pilot tones.

[0106] For example, A bit information (e.g., 52 uncoded bits) can be transmitted through U-SIG, and the first symbol of U-SIG can transmit the first X bits of information (e.g., 26 uncoded bits) out of the total A bit information, and the second symbol of U-SIG can transmit the remaining Y bits of information (e.g., 26 uncoded bits) out of the total A bit information. For example, the transmitting STA can obtain 26 uncoded bits included in each U-SIG symbol. The transmitting STA can perform convolutional encoding (i.e., BCC encoding) based on a rate of R=1 / 2 to generate 52 coded bits, and perform interleaving on the 52 coded bits. The transmitting STA can perform BPSK modulation on the interleaved 52 coded bits to generate 52 BPSK symbols allocated to each U-SIG symbol. A single U-SIG symbol can be transmitted based on 56 tones (subcarriers) from subcarrier index -28 to subcarrier index +28, excluding DC index 0. The 52 BPSK symbols generated by the transmitting STA can be transmitted based on the remaining tones (subcarriers) excluding the pilot tones -21, -7, +7, and +21.

[0107] For example, A bit information (e.g., 52 uncoded bits) transmitted by U-SIG may include a CRC field (e.g., a 4-bit long field) and a tail field (e.g., a 6-bit long field). The CRC field and the tail field may be transmitted through the second symbol of the U-SIG. The CRC field may be generated based on 26 bits allocated to the first symbol of the U-SIG and the remaining 16 bits excluding the CRC / tail field within the second symbol, and may be generated based on a conventional CRC calculation algorithm. In addition, the tail field may be used to terminate the trellis of the convolutional decoder and may be set to, for example, "000000".

[0108] The A bit information (e.g., 52 uncoded bits) transmitted by the U-SIG (or U-SIG field) can be divided into version-independent bits and version-dependent bits. For example, the size of the version-independent bits can be fixed or variable. For example, the version-independent bits can be assigned only to the first symbol of the U-SIG, or the version-independent bits can be assigned to both the first symbol and the second symbol of the U-SIG. For example, the version-independent bits and the version-dependent bits can be called by various names, such as the first control bit and the second control bit.

[0109] For example, the version-independent bits of the U-SIG may include a 3-bit PHY version identifier. For example, the 3-bit PHY version identifier may include information related to the PHY version of the transmitted and received PPDU. For example, a first value (e.g., a value of 000) of the 3-bit PHY version identifier may indicate that the transmitted and received PPDU is an EHT PPDU. In addition, a second value (e.g., a value of 001) of the 3-bit PHY version identifier may indicate that the transmitted and received PPDU is an UHR PPDU.

[0110] In other words, when the (AP / non-AP) STA transmits an EHT PPDU, it can set the 3-bit PHY version identifier to the first value. In other words, the receiving (AP / non-AP) STA can determine that the received PPDU is an EHT PPDU based on the PHY version identifier having the first value, and can determine that the received PPDU is an UHR PPDU based on the PHY version identifier having the second value.

[0111] For example, the version-independent bits of U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication.

[0112] For example, the version-independent bits of U-SIG may include information about the length of a transmission opportunity (TXOP) and information about the BSS color ID.

[0113] For example, if a UHR PPDU is classified into various types (e.g., a type related to SU transmission (performed based on UL or DL), a type related to DL transmission, a type related to NDP transmission, a type related to DL non-MU-MIMO, a type related to DL MU-MIMO, a type related to Multi-AP operation, a type related to CO-BF (Coordinated beamforming), SR (Spatial Reuse), a type related to C-OFDMA (Coordinated OFDMA), a type related to CO-TDMA (Coordinated TDMA)), information about the type of the EHT PPDU (e.g., 2-bit or 3-bit information) can be included in the version-dependent bits of the U-SIG.

[0114] For example, a U-SIG may include information about 1) a bandwidth field including information about a bandwidth, 2) a field including information about a Modulation and Coding Scheme (MCS) technique applied to the UHR-SIG, 3) an indication field including information about whether a dual subcarrier modulation (DCM) technique is applied to the UHR-SIG, 4) a field including information about the number of symbols used for the UHR-SIG, 5) a field including information about whether the UHR-SIG is generated over the entire band, 6) a field including information about the type of UHR-LTF / STF, and 7) a field indicating the length of the UHR-LTF and the CP length.

[0115] Preamble puncturing may be applied to the PPDU of FIG. 6. Preamble puncturing refers to applying puncturing to a portion of the entire bandwidth of the PPDU (e.g., the secondary 20 MHz band). For example, when an 80 MHz PPDU is transmitted, the STA may apply puncturing to the secondary 20 MHz band within the 80 MHz band, and transmit the PPDU only through the primary 20 MHz band and the secondary 40 MHz band.

[0116] For example, the pattern of preamble puncturing can be preset. For example, when the first puncturing pattern is applied, puncturing can be applied only to the secondary 20 MHz band within the 80 MHz band. For example, when the second puncturing pattern is applied, puncturing can be applied only to one of the two secondary 20 MHz bands included in the secondary 40 MHz band within the 80 MHz band. For example, when the third puncturing pattern is applied, puncturing can be applied only to the secondary 20 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band). For example, when the fourth puncturing pattern is applied, a primary 40 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band) may be present, and puncturing may be applied to at least one 20 MHz channel that does not belong to the primary 40 MHz band.

[0117] Information regarding preamble puncturing applied to the PPDU may be included in the U-SIG and / or UHR-SIG. For example, the first field of the U-SIG may include information regarding the contiguous bandwidth of the PPDU, and the second field of the U-SIG may include information regarding preamble puncturing applied to the PPDU.

[0118] For example, U-SIG and UHR-SIG may include information regarding preamble puncturing based on the following method. If the bandwidth of the PPDU exceeds 80 MHz, the U-SIG may be individually configured in units of 80 MHz. For example, if the bandwidth of the PPDU is 160 MHz, the PPDU may include a first U-SIG for the first 80 MHz band and a second U-SIG for the second 80 MHz band. In this case, the first field of the first U-SIG may include information regarding the 160 MHz bandwidth, and the second field of the first U-SIG may include information regarding preamble puncturing applied to the first 80 MHz band (i.e., information regarding the preamble puncturing pattern). Additionally, the first field of the second U-SIG may include information about a 160 MHz bandwidth, and the second field of the second U-SIG may include information about preamble puncturing applied to the second 80 MHz band (i.e., information about a preamble puncturing pattern). Meanwhile, the UHR-SIG consecutive to the first U-SIG may include information about preamble puncturing applied to the second 80 MHz band (i.e., information about a preamble puncturing pattern), and the UHR-SIG consecutive to the second U-SIG may include information about preamble puncturing applied to the first 80 MHz band (i.e., information about a preamble puncturing pattern).

[0119] Additionally or alternatively, U-SIG and UHR-SIG may include information regarding preamble puncturing based on the following methods. U-SIG may include information regarding preamble puncturing for all bands (i.e., information regarding preamble puncturing patterns). That is, UHR-SIG may not include information regarding preamble puncturing, and only U-SIG may include information regarding preamble puncturing (i.e., information regarding preamble puncturing patterns).

[0120] U-SIGs can be configured in 20 MHz units. For example, if an 80 MHz PPDU is configured, U-SIGs can be duplicated. That is, four identical U-SIGs can be included within an 80 MHz PPDU. PPDUs exceeding the 80 MHz bandwidth can contain different U-SIGs.

[0121] The UHR-SIG of FIG. 6 may include control information for a receiving STA. The UHR-SIG may be transmitted via at least one symbol, and each symbol may have a length of 4 us. Information regarding the number of symbols used for the UHR-SIG may be included in the U-SIG.

[0122] UHR-SIG provides additional signals to the U-SIG field to enable STAs to interpret / decode UHR PPDUs. The UHR-SIG field may contain U-SIG overflow bits that are common to all users. The UHR-SIG field also contains resource allocation information, allowing STAs to look up resources used in fields containing data fields / UHR-STF / UHR-LTF (i.e., UHR modulated fields of an UHR PPDU).

[0123] The frequency resources of the UHR-LTF, UHR-STF, and data fields illustrated in FIG. 6 can be determined based on RUs (resource units) defined by multiple subcarriers / tones. That is, the UHR-LTF, UHR-STF, and data fields of the present disclosure can be transmitted / received through RUs (resource units) defined by multiple subcarriers / tones.

[0124] Figure 7 illustrates an operation according to UL-MU. As illustrated, a transmitting STA (e.g., AP) can acquire a TXOP (725) by performing channel access through contending (i.e., backoff operation) and transmit a trigger frame (730). That is, the transmitting STA (e.g., AP) can transmit a PPDU including a trigger frame (730). When a PPDU including a trigger frame is received, a TB (trigger-based) PPDU is transmitted after a delay of SIFS.

[0125] TB PPDUs (741, 742) are transmitted at the same time and can be transmitted from multiple STAs (e.g., User STAs) whose AIDs are indicated in the Trigger frame (730). The ACK frame (750) for the TB PPDU can be implemented in various forms. For example, the ACK frame (750) for the TB PPDU can be implemented in the form of a BA (block ACK).

[0126] In FIG. 7, transmission(s) of a Trigger Frame (730), a TB PPDU (741, 742) and / or an ACK frame (750) may be performed within a TXOP (725).

[0127] Figure 8 shows an example of an OBSS scenario.

[0128] Referring to FIG. 8, AP 1 and STA 1-1, STA 1-2, and STA 1-3 associated with AP 1 may belong to BSS 1. AP 2 and STA 2-1, STA 2-2, and STA 2-3 associated with AP 2 may belong to BSS 2. As illustrated in FIG. 8, the areas covered by AP 1 / BSS 1 and AP 2 / BSS 2 may overlap, which may be referred to as an OBSS (overlapping BSS) (or OBSS scenario).

[0129] Based on BSS 1, BSS 2 may be an OBSS. Accordingly, an AP belonging to BSS 2 based on BSS 1 (or an AP / STA belonging to BSS 1) may be referred to as an OBSS AP, and an STA belonging to BSS 2 may be referred to as an OBSS STA. Similarly, BSS 1 may be an OBSS based on BSS 2. Accordingly, an AP belonging to BSS 1 based on BSS 2 (or an AP / STA belonging to BSS 2) may be referred to as an OBSS AP, and an STA belonging to BSS 1 may be referred to as an OBSS STA. On the other hand, based on BSS 1 (or an AP / STA belonging to BSS 1), an AP belonging to BSS 1 may be referred to as an In-BSS AP, and an STA belonging to BSS 1 may be referred to as an In-BSS STA. Based on BSS 2 (or, AP / STA belonging to BSS 2), an AP belonging to BSS 2 may be referred to as an In-BSS AP, and an STA belonging to BSS 2 may be referred to as an In-BSS STA.

[0130] In OBSS, two or more BSSs may share the same or adjacent physical channel, and their signal ranges may overlap. In OBSS scenarios, when BSSs operate on the same channel, collisions / interference can occur, leading to increased retransmissions and reduced radio resource efficiency.

[0131] For example, assume a situation where AP 1 and AP 2 simultaneously transmit on the same channel to their associated STAs. In this case, since STA 1-1, STA 1-2, STA 2-1, and STA 2-2 are in the overlapping area in the OBSS scenario, i) transmissions from AP 1 to STA 1-1 / STA 1-2 may be interfered by transmissions from BSS 2 / OBSS (i.e., transmissions from AP 2 to STA 2-1 / STA 2-2), and ii) transmissions from AP 2 to STA 2-1 / STA 2-2 may be interfered by transmissions from BSS 1 / OBSS (i.e., transmissions from AP 1 to STA 1-1 / STA 1-2). On the other hand, since STA 1-3 and STA 2-3 are not in overlapping areas, transmissions from AP 1 to STA 1-3 may not be interfered with by transmissions of BSS 2 / OBSS (i.e., transmissions from AP 2 to STA 2-1 / STA 2-2 / STA 2-3), and transmissions from AP 2 to STA 2-3 may not be interfered with transmissions of BSS 1 / OBSS (i.e., transmissions from AP 1 to STA 1-1 / STA 1-2 / STA 1-3).

[0132] Below, (channel) sounding is described as an example of channel measurement.

[0133] Figure 9 shows an example of a channel sounding procedure.

[0134] Referring to FIG. 9, channel sounding is initiated by a first STA, called a beamformer. Channel sounding may be performed between the beamformer and a second STA, called a beamformee. For DL ​​channel measurements, the beamformer may be an AP STA, and the beamformee may be a non-AP STA. For UL channel measurements, the beamformer may be a non-AP STA, and the beamformee may be an AP STA.

[0135] In step S901, the beamformer may initiate channel sounding by transmitting a Null Data Packet Announcement (NDPA) frame to the beamformee, which is used to control the channel and identify the beamformee. The number of beamformees may be one or more. When the number of beamformees is N, the NDPA may include N STA information fields. Each STA information field is associated with a corresponding beamformee and may include information about the corresponding beamformee (e.g., information identifying the beamformee, e.g., AID / AID12). At least one beamformee performs a response to the NDPA frame. STAs other than the beamformee may postpone channel access until the sounding sequence (i.e., sequential frame exchange for sounding) is completed.

[0136] In step S903, after the NDPA frame is transmitted, the beamformer can transmit an NDP (Null Data Packet) frame. The NDP is defined based on the VHT / HE / EHT / UHR PPDU. For example, the NDP may be a PPDU in which a data field corresponding to a payload signal (or MAC data) is omitted from the VHT / HE / EHT / UHR PPDU. Since the NDP includes multiple OFDM training fields, the beamformer that receives the NDP can calculate a channel response. In addition, the NDP may be used to calculate a steering matrix (e.g., a Q matrix) related to beamforming. In some cases, multiple NDPs may be configured for multiple beamformees. As illustrated, an interframe space of SIFS (Short Interframe Space) may exist between the NDPA frame and the NDP frame. That is, after the NDPA frame is transmitted, the NDP frame may be transmitted after a time equivalent to the SIFS has elapsed.

[0137] In step S905, the beamformer can calculate a feedback matrix / CQI (channel quality indicator) based on the received NDP. In other words, the beamformer can perform channel measurement based on the received NDP and obtain channel information including the result of the channel measurement (e.g., feedback matrix / CQI). The feedback matrix is ​​expressed by various names such as V matrix, and enables the beamformer to calculate a steering matrix. The beamformer transmits a feedback / report signal including the channel information to the beamformer. The beamformer can calculate a steering matrix based on the feedback / report signal, and can calculate a steering matrix for communication directed to the beamformer, for example. The channel information and / or the feedback / report signal can include a compressed beamforming signal, as illustrated.

[0138] If there is only one beamformer, that beamformer can transmit a feedback / report signal to the beamformer after a time equal to SIFS has elapsed since receiving the NDP.

[0139] When multiple beamformees exist, the multiple beamformees can sequentially transmit feedback / report signals. The beamformee associated with the first STA information field among the STA information fields can transmit the feedback / report signal to the beamformer after a time equivalent to SIFS has elapsed after receiving the NDP without receiving a separate polling frame. On the other hand, the remaining beamformees can transmit the feedback / report signal to the beamformer after a time equivalent to SIFS has elapsed after receiving the polling frame (e.g., BFRP frame) transmitted by the beamformer. Here, the polling frame can be transmitted after a time equivalent to SIFS has elapsed after the feedback / report signal is transmitted / received.

[0140] When multiple beamformees exist, the multiple beamformees can transmit feedback / report signals simultaneously through RUs allocated through a trigger frame. For example, the trigger frame may be a beamforming report poll (BFRP) trigger frame. The BFRP trigger frame may include information for identifying beamformees (e.g., AID / 12 LSBs) and information about frequency resources (i.e., RUs) for each beamformee to transmit feedback / report signals. The beamformees identified by the BFRP trigger frame can transmit feedback / report signals (simultaneously / together) based on the corresponding RU resources. The BFRP trigger frame may be transmitted after a time equivalent to SIFS has elapsed after the NDP is transmitted / received. The feedback / report signals of the multiple beamformees may be transmitted after a time equivalent to SIFS has elapsed after the BFRP trigger frame is transmitted / received.

[0141] Below, the structure and types / subtypes of MAC frames are described.

[0142] Figure 10 shows an example of a header of a MAC frame.

[0143] As illustrated, the MAC frame may include a frame control field / information of 2 octets in length, a duration field / information of 2 octets in length, a RA (Receiver Address) field / information of 6 octets in length, and a TA (Transmitter Address) field / information of 6 octets in length. As illustrated in FIG. 10, the four fields may be consecutive to each other. The MAC header of FIG. 10 may be modified in various ways, and a new field may be inserted between the four illustrated fields, or at least one of the illustrated fields may be omitted.

[0144] The MAC header illustrated in Fig. 10 may be positioned at the very front of the MAC frame. That is, the MAC frame may include a MAC header as illustrated in Fig. 10 and MAC body fields / information subsequent to the MAC header. The MAC frame including the MAC header of Fig. 10 is inserted / included in the data field of the PPDU (e.g., UHR PPDU) illustrated in Fig. 5.

[0145] The MAC frames included in the data field of the PPDU of this specification can be classified into various types. For example, the MAC frames of this specification can be classified into control frames, management frames, and data frames.

[0146] For example, the management frame includes Association Request, Association Response, Reassociation Request, Reassociation Response, Probe Request, Probe Response, Beacon, Disassociation, Authentication, and Deauthentication frames / signals defined in conventional WLAN. For the management frame, the values ​​of the type fields (B3 and B2) in FIG. 10 are set to 00. In addition, the values ​​of the subtype fields (B7, B6, B5, B4) in FIG. 10 are as follows: Association Request (0000), Association Response (0001), Reassociation Request (0010), Reassociation Response (0011), Probe Request (0100), Probe Response (0101), Beacon (1000), Disassociation (1010), Authentication (1011), Deauthentication (1100).

[0147] For example, the control frame includes Trigger Beamforming Report Poll, NDP Announcement (NDPA), Control Frame Extension, Control Wrapper, Block Ack Request (BlockAckReq), Block Ack (BlockAck), PS-Poll, RTS, CTS, Ack, and CF-End frames / signals defined in conventional WLAN. For the control frame, the values ​​of the type fields (B3 and B2) in FIG. 10 are set to 01. Also, the values ​​of the subtype fields (B7, B6, B5, B4) of FIG. 10 are as follows: Trigger (0010), Beamforming Report Poll (0100), NDP Announcement (0101), Control Frame Extension (0110), Control Wrapper (0111), BlockAckReq (1000), BlockAck (1001), PS-Poll (1010), RTS (1011), CTS (1100), Ack (1101), CF-End (1110).

[0148] For example, the data frame includes (QoS) Data, (QoS) Null, etc. defined in conventional WLAN. For the management frame, the value of the type field (B3 and B2) of FIG. 10 is set to 10.

[0149] The MAC frame / signal used in this specification can be identified through the type field / information and subtype field / information described above. For example, the “trigger frame” in this specification can mean a MAC frame in which the type bits B3 and B2 bits in the frame control field of the MAC header are set to 01, and the subtype bits B7, B6, B5, B4 bits in the frame control field are also set to 0010. Various MAC frames described in this specification are inserted / included in the data field of various PPDUs (e.g., HE / VHT / HE / EHT / UHR PPDU).

[0150] Figure 11 illustrates a trigger frame format. The trigger frame format may also be referred to as the structure of a trigger frame.

[0151] Referring to FIG. 11, a trigger frame may include a frame control field, a duration / ID field, a receiver address (RA) field, a transmitter address (TA) field, a common info field, a user info list field, a padding field, and / or a frame check sequence (FCS) field. Optionally, the trigger frame may further include a special user info field between the common info field and the user info list field. The user info list field may include one or more user info fields. The frame control field, the duration / ID field, the RA field, and the TA field may constitute a MAC header.

[0152] For example, the common information field may include a trigger type subfield. The trigger type subfield value may indicate a trigger frame variant, as shown in Table 1:

[0153] Trigger type subfield valueTrigger frame variant0Basic1Beamforming Report Poll (BFRP)2MU-BAR3MU-RTS4Buffer Status Report Poll (BSRP)5GCR MU-BAR6Bandwidth Query Report Poll (BQRP)7NDP Feedback Report Poll (NFRP)8Ranging9-15Reserved

[0154] For example, if the value of the trigger type subfield is set to 0, the trigger frame may be a basic trigger frame. For example, if the value of the trigger type subfield is set to 3, the trigger frame may be a MU (multi-user) RTS trigger frame. Meanwhile, according to the EHT (or 802.11be) standard, in order to support peer-to-peer (P2P) transmission to a non-AP STA, an AP may allocate a portion of the time interval within the TXOP acquired by the AP. In order to allocate a portion of the time interval within the TXOP, a TXOP Sharing Mode subfield may be defined within the Common Info Field of the MU-RTS trigger frame. When the value of the TXOP Sharing Mode subfield is non-zero, such an MU-RTS trigger frame may be referred to as an MU-RTS TXOP Sharing (TXS) trigger frame (TF). The values ​​of the TXOP Sharing Mode subfield are described in Table 2 below:

[0155] Triggered TXOP Sharing Mode subfield valueDescription0MU-RTS that does not initiate MU-RTS TXOP sharing procedure.1MU-RTS that initiates MU-RTS TXOP sharing procedure wherein a scheduledSTA can only transmit MPDU(s) addressed to its associated AP.2MU-RTS that initiates MU-RTS TXOP sharing procedure wherein a scheduled STA can transmit MPDU(s) addressed to its associated AP or addressed to another STA.3Reserved.

[0156] For example, if the value of the TXOP shared mode subfield is 1, one or more (non-TB) PPDU transmissions to the AP may be supported. If the value of the TXOP shared mode subfield is 2, not only (non-TB) PPDU transmissions to the AP but also P2P transmissions may be supported. In the present disclosure, the MU-RTS TXS TF may also be briefly referred to as a TXS trigger frame.

[0157] Figure 12 shows an example of the user information field format of MU-RTS TXS TF.

[0158] Referring to FIG. 12, the user information field may include an AID subfield, an RU allocation subfield, an allocation duration subfield, reserved bits, and / or a PS160 subfield.

[0159] The AID subfield may indicate the AID for the corresponding STA. The RU allocation subfield may indicate RU allocation for the corresponding STA.

[0160] The allocation interval subfield can contain 9 bits from B20 to B28 in the MU-RTS TXS TF and can indicate an allocation interval in units of 16us. In this case, the maximum length of the allocation interval that can be indicated by the allocation interval subfield can be 2^9= 8192us.

[0161] The PS160 subfield may indicate the primary 160MHz channel or the second 160MHz channel to which RU or MRU allocation applies.

[0162] Meanwhile, to enable terminals to maintain continuous WLAN connectivity over a wider area, numerous APs are being installed adjacent to each other. However, overlapping BSSs of multiple APs can lead to issues such as radio interference and transmission collisions between APs. To address these issues, various technologies related to coordination between APs in the frequency, time, and spatial domains (e.g., RU selection, joint transmission, nulling) have been proposed. Furthermore, various issues that may arise during inter-AP cooperation need to be addressed.

[0163] In this disclosure, multi-AP operation is proposed. Multi-AP operation may be based on a technique for reducing various interferences, such as inter-symbol interference (ISI), through coordination with neighboring APs (e.g., APs located in overlapping BSSs).

[0164] For example, multi-AP operation can be categorized into multi-AP cooperation schemes (or, cooperative schemes) based on various technologies / types / formats / protocols. For example, the cooperative scheme may include Coordinated TDMA (Co-TDMA), which distinguishes wireless resources allocated to multiple APs based on the time domain. Additionally or alternatively, the cooperative scheme may include Coordinated OFDMA (C-OFDMA), which distinguishes wireless resources allocated to multiple APs based on the frequency domain. Additionally or alternatively, the cooperative scheme may include Coordinated Spatial Reuse (Co-SR), which applies spatial reuse (SR) to at least one AP. Additionally or alternatively, the cooperative scheme may include Coordinated beamforming (Co-BF) / nulling, which transmits by nulling interference generated from neighboring APs (e.g., adjacent APs / STAs, and / or OBSS APs / OBSS STAs). Additionally or alternatively, the cooperative scheme may include AP selection, in which an AP with a good channel condition among neighboring APs (e.g., at least one AP located within a BSS or OBSS and with a good channel condition) transmits. Additionally or alternatively, the cooperative scheme may include Joint Transmission (JTX) or Joint Transmission (JT), in which multiple APs (e.g., multiple APs within the same BSS / OBSS, or multiple APs within different BSS / OBSS) cooperate to perform simultaneous transmission and reception, and JTX / JT may be implemented based on Joint Beamforming or Joint MU-MIMO.

[0165] In this disclosure, “multi-AP (cooperative) operation” may also be referred to as “multi-AP (cooperative) transmission.” Furthermore, “multi-AP (cooperative) operation / transmission” and “multi-AP cooperative scheme (or cooperative scheme)” may be used interchangeably.

[0166] When the triggered TXOP sharing protocol is utilized for multi-AP cooperation (e.g., Co-TDMA), transmissions within the BSS of each cooperative AP are divided into time units, so that each cooperative AP can perform frame exchange without affecting other cooperative APs. In this case, the AP in the triggered TXS protocol may be an AP that shares TXOP in multi-AP cooperation operation, and the STA in the triggered TXS protocol may be an AP that shares TXOP in multi-AP cooperation operation.

[0167] In the present disclosure, an AP that shares a TXOP may be referred to as a SAP (sharing AP), and an AP that receives a TXOP from a SAP may be referred to as a DAP (shared AP). Here, the term SAP does not limit the entity that shares a TXOP to only AP STAs, and a SAP may also include non-AP STAs that share a TXOP. In addition, the term DAP does not limit the entity that shares a TXOP to only AP STAs, and a DAP may also include non-AP STAs that share a TXOP (or transmit and receive with an AP STA that shares a TXOP).

[0168] Additionally, a frame exchange performed by a DAP with a non-AP STA or SAP belonging to the DAP BSS during the allocated time (i.e., the allocated period for the DAP within the TXOP indicated by the MU-RTS TXS TF transmitted from the SAP, which is the time allocated in the MU-RTS TXS TF) may be referred to as a BSS frame exchange (FE) of the DAP. For example, a data frame transmission and a block ACK frame response following an RTS / CTS frame exchange between the DAP and a non-AP STA, a UL data frame transmission of non-AP STAs by a trigger frame transmitted from the DAP, and / or a data frame transmission of the DAP by a trigger frame transmitted from the SAP may be performed.

[0169] In the present disclosure, "frame exchange (FE)" may include frame transmission and / or reception operations between STAs. The STAs may be APs or non-AP STAs. Here, the frames may include various types of frames (e.g., data frames, control frames, management frames).

[0170] Figure 13 shows an example of multi-AP operation based on Co-TDMA between APs.

[0171] Referring to Fig. 13, SAP and non-AP STA1 may belong to BSS1, and DAP and non-AP STA2 may belong to BSS2. SAP may acquire TXOP and share TXOP with DAP by transmitting MU-RTS TXS TF including information about allocated interval (time allocated in MU-RTS TXS TF in Fig. 13) within TXOP. DAP may transmit CTS in response to MU-RTS TXS TF and perform frame exchange with non-AP STA2 belonging to its BSS (i.e., BSS2) in the allocated interval shared from SAP. Although not shown, after frame exchange is completed (or after allocated interval ends), DAP may transmit TXOP return frame to return TXOP to SAP. After frame exchange is completed within a TXOP (or after the allocation interval ends), a remaining TXOP interval may exist, and the SAP can perform frame exchange with a non-AP STA1 belonging to its own BSS (i.e., BSS1) within the remaining TXOP interval.

[0172] In order for multi-AP cooperation to be achieved between two APs, the two APs must be in a connected / bonded state, and / or a negotiation procedure must be performed in advance to exchange cooperation request frames / cooperation response frames containing capability information / requirement information of each AP, and then multi-AP transmission (e.g., Co-TDMA (coordinated time division multiple access), C-OFDMA (coordinated orthogonal frequency division multiple access), Co-SR (coordinated spatial reuse), Co-BF (coordinated beamforming), AP selection, or Jo-TX (joint transmission)) can be performed based on the obtained information. In other words, in order for multi-AP transmission to be performed smoothly, a negotiation procedure for configuring / managing multi-AP cooperation and / or transmitting based on a specific multi-AP cooperation method must be performed in advance between the above-described SAP and DAP. A multi-AP set can be set up / configured through the negotiation procedure. Therefore, the negotiation procedure may also be referred to as a multi-AP set setup / configuration procedure.

[0173] For successful multi-AP cooperation, a multi-AP selection procedure (or AP selection procedure for multi-AP cooperation) may be performed to select a DAP with which the SAP wishes to share TXOPs within a multi-AP set established / configured through a negotiation procedure and / or to notify that the TXOPs will be shared. Through the multi-AP selection procedure, the SAP can determine whether a DAP requires TXOP sharing within the acquired TXOPs, and if a specific DAP does not require TXOP sharing, it can decide to share the TXOPs with subsequent / other DAPs. Alternatively, the SAP can simply notify the target DAPs that it intends to share TXOPs during the multi-AP selection procedure, thereby enabling multi-AP cooperation to be performed while reducing the overhead caused by the multi-AP selection procedure.

[0174] In a multi-AP selection procedure, a SAP may transmit a request frame (i.e., a request frame for AP selection / selection request frame) to one or more DAPs to select a DAP to share TXOP from a multi-AP set established / configured through a negotiation procedure, and one or more DAP(s) receiving the request frame may transmit a response frame (i.e., a response frame for AP selection / selection response frame) to the request frame based on whether TXOP sharing is required. If a response frame including an indication that TXOP sharing is not required is received from a DAP(s), or if a response frame is not received from a DAP(s), the SAP may transmit a request frame for AP selection to another DAP - i.e., the SAP may perform AP re-selection. Alternatively, the SAP may simply inform the target DAP(s) that it intends to share TXOP in the multi-AP selection procedure. For example, a SAP can send an AP selection request frame that does not solicit a response frame to the target DAP with which it wishes to share a TXOP, and the DAP receiving such an AP selection request frame can prepare an action for the intended TXOP sharing.

[0175] The SAP transmits a frame for TXOP sharing (e.g., TXOP sharing frame / MU-RTS TXS trigger frame) to the selected DAP through a multi-AP selection procedure, and the DAP can exchange frames with non-AP STA(s) connected to the DAP in the time interval (e.g., allocation interval) allocated by the TXOP sharing frame.

[0176] Basically, C-TDMA does not require interference measurements between cooperating BSSs, but for Co-SR and Co-BF to work, the OBSS APs must be able to know channel information (e.g., RSSI, TX power, SINR, AINR, path loss) for the target STAs of each AP. To obtain this channel information, an OBSS channel sounding procedure can be performed between cooperating APs and their associated STAs, and C-TDMA can be utilized in the OBSS channel sounding procedure.

[0177] Accordingly, the present disclosure provides a method for performing OBSS channel TB (trigger-based) and / or non-TB sounding procedures utilizing C-TDMA and a device implementing the method.

[0178] According to various embodiments of the present disclosure, each AP can obtain interference and / or channel information for STAs connected to neighboring cooperative APs through OBSS channel TB and / or non-TB sounding procedures, and can use and / or initiate various multi-AP cooperation technologies (e.g., Co-SR, Co-BF, J-TX) based on the obtained information.

[0179] According to various embodiments of the present disclosure, more effective OBSS channel sounding can be performed using C-TDMA technology without requiring each AP to perform individual sounding procedures with individually acquired TXOPs.

[0180] The specific designations / names proposed in this disclosure may be changed and are not limited thereto.

[0181] FIG. 14 illustrates an example of a method performed by a first AP for channel sounding in an OBSS scenario according to an embodiment of the present disclosure.

[0182] Referring to FIG. 14, in step S1401, the first AP may initiate a negotiation procedure for multi-AP cooperation with the second AP.

[0183] In step S1403, the first AP may obtain information about one or more neighboring STAs connected to the second AP in a negotiation procedure.

[0184] In step S1405, the first AP may transmit a channel measurement signal to one or more neighboring STAs based on information about the one or more neighboring STAs.

[0185] In step S1407, after the first AP transmits a channel measurement signal, the first AP can obtain channel information about a channel between the first AP and one or more neighboring STAs.

[0186] In step S1409, the first AP may perform transmission related to multi-AP cooperation to one or more STAs connected to the first AP based on channel information.

[0187] According to various embodiments, the BSS associated with the second AP may be an OBSS for the BSS associated with the first AP. One or more neighboring STAs may belong to the OBSS.

[0188] According to various embodiments, the information about one or more neighboring STAs may include at least one of a media access control (MAC) address of one or more neighboring STAs, an association identifier (AID) of one or more neighboring STAs, a received signal strength indicator (RSSI) associated with one or more neighboring STAs, or a signal to interference plus noise ratio (SINR) associated with one or more neighboring STAs.

[0189] According to various embodiments, after transmitting an announcement frame to initiate channel measurement to one or more neighboring STAs, the first AP may transmit a channel measurement signal to one or more neighboring STAs. The announcement frame may include information about one or more neighboring STAs.

[0190] According to various embodiments, after an announcement frame for initiating channel measurement with one or more connected STAs is transmitted by a first AP, a second AP may transmit a channel measurement signal to one or more neighboring STAs. The announcement frame may include information about one or more connected STAs. The channel measurement signal transmitted by the second AP may include BSS color information of the first AP.

[0191] According to various embodiments, after an announcement frame for initiating channel measurement with one or more connected STAs is transmitted by a first AP, the first AP and the second AP may simultaneously transmit a channel measurement signal to one or more STAs. The announcement frame may include information about one or more connected STAs. The channel measurement signal transmitted by the second AP may include BSS color information of the first AP.

[0192] According to various embodiments, the first AP may transmit an announcement frame.

[0193] According to various embodiments, the announcement frame may be transmitted by the second AP.

[0194] According to various embodiments, the announcement frame may further include information about one or more STAs associated with the first AP. The information about the one or more STAs associated with the first AP may include at least one of a MAC (media access control) address of one or more STAs associated with the first AP, or an AID (association identifier) ​​of one or more STAs associated with the first AP.

[0195] According to various embodiments, the channel measurement signal may be a null data packet (NDP) frame. The announcement frame may be an NDP announcement (NDPA) frame.

[0196] According to various embodiments, the first AP may transmit a channel measurement signal to one or more STAs connected to the first AP, and then obtain channel information about a channel between the first AP and one or more STAs connected to the first AP.

[0197] According to various embodiments, the first AP may obtain a transmission opportunity (TXOP). During the TXOP: i) a channel measurement signal may be transmitted by the first AP, and ii) channel information may be obtained by the first AP.

[0198] According to various embodiments, a first AP may transmit a TXOP shared frame to a second AP, the TXOP shared frame including information about an allocated interval within a TXOP interval. In the allocated interval: i) a channel measurement signal may be transmitted by the second AP, and ii) channel information may be acquired by the second AP.

[0199] According to various embodiments, in the allocation interval: i) a channel measurement signal may be transmitted by the first AP, and ii) channel information may be acquired by the first AP.

[0200] According to various embodiments, the first AP may receive channel information acquired by the second AP from the second AP. The channel information acquired by the second AP may include at least one of: channel information about a channel between the second AP and one or more neighboring STAs; or channel information about a channel between the second AP and one or more STAs associated with the first AP.

[0201] According to various embodiments, the first AP may transmit channel information acquired by the first AP to the second AP. The channel information acquired by the first AP may include at least one of: channel information about a channel between the first AP and one or more neighboring STAs; or channel information about a channel between the first AP and one or more STAs associated with the first AP.

[0202] According to various embodiments, the channel information may include the results of channel measurement performed based on a channel measurement signal. The results of the channel measurement may include at least one of a feedback matrix, a channel quality indicator (CQI), a received signal strength indicator (RSSI), a signal to interference plus noise ratio (SINR), transmission power, path loss, or compressed beamforming information.

[0203] According to various embodiments, a first AP may transmit a frame requesting channel information to one or more neighboring STAs. The channel information may be received from one or more neighboring STAs in response to the frame requesting channel information.

[0204] According to various embodiments, the frame for requesting channel information may include a beamforming report poll (BFRP) trigger frame.

[0205] According to various embodiments, a first AP may perform interference nulling for one or more neighboring STAs based on at least one of channel information about a channel between the first AP and one or more neighboring STAs or channel information about a channel between the first AP and one or more STAs associated with the first AP. The first AP may perform transmissions related to multi-AP cooperation by applying interference nulling.

[0206] According to various embodiments, the first AP may perform transmission based on a coordination scheme for multi-AP cooperation.

[0207] According to various embodiments, the cooperative scheme may include at least one of coordinated beamforming (Co-BF) or coordinated spatial reuse (Co-SR).

[0208] FIG. 15 illustrates an example of signal flow between a STA connected to a first AP and a second AP for channel sounding in an OBSS scenario according to an embodiment of the present disclosure.

[0209] Referring to FIG. 15, in step S1501, the first AP may initiate a negotiation procedure for multi-AP cooperation with the second AP.

[0210] In step S1503, the first AP can obtain information about the STA connected to the second AP in the negotiation procedure.

[0211] In step S1505, the STA may receive a channel measurement signal from the first AP. The first AP may transmit the channel measurement signal to the STA based on information about the STA.

[0212] In step S1507, the STA may perform channel measurement on a channel between the first AP and the STA based on the channel measurement signal.

[0213] In step S1509, the STA may transmit channel information including the result of channel measurement to the first AP.

[0214] In step S1511, the first AP may perform transmission related to multi-AP cooperation to one or more STAs connected to the first AP based on channel information.

[0215] Below, a detailed implementation for channel sounding in the OBSS scenario is described.

[0216] Each AP that has performed a multi-AP negotiation procedure (or, multi-AP set setup / configuration, or multi-AP agreement) may perform an interference measurement procedure (referred to as interference measurement (IM) in this disclosure) for efficient multi-AP cooperation-based transmission and / or to initiate a specific multi-AP cooperation-based transmission.

[0217] The IM procedure may include a channel sounding procedure for an In-BSS STA and / or a channel sounding procedure for an OBSS STA. If channel information for the In-BSS STA exists through individual frame exchanges and / or procedures upon connection with STAs within the BSS (e.g., probe request / response, association request / response, authentication request / response), the channel sounding procedure for the In-BSS STA may be omitted in the IM procedure. On the other hand, for multi-AP cooperation-based transmission / methods, a sounding procedure for OBSS STAs in a multi-AP cooperation relationship needs to be performed.

[0218] A method of performing OBSS channel sounding when each AP individually acquires a TXOP can be considered, but using C-TDMA technology, multiple cooperating APs can perform OBSS channel sounding together within a single TXOP acquired by one AP.

[0219] I. TB Sounding

[0220] FIG. 16 illustrates a first example of an OBSS channel TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0221] In Fig. 16, it is assumed that each AP has previously transmitted information about its BSS STAs (or some target STAs) to neighboring cooperative APs through a multi-AP negotiation procedure. Information about the BSS STAs may include at least one of a MAC address, AID, RSSI, or SINR value for identifying each STA. Cooperative APs that determine that an IM procedure is necessary to initiate some multi-AP schemes through the multi-AP negotiation procedure may perform OBSS channel sounding upon acquiring a TXOP. For example, AP 1 in Fig. 16 may acquire a TXOP and perform OBSS channel TB sounding.

[0222] At this time, the OBSS channel sounding procedure of AP 1 can be performed on APs among the surrounding cooperative APs that wish to cooperate based on a multi-AP method (e.g., Co-SR, Co-BF) that requires an IM procedure. In other words, the OBSS channel sounding procedure for surrounding cooperative APs that wish to perform multi-AP operation based on a multi-AP method (e.g., C-TDMA) that does not require an IM procedure can be omitted.

[0223] AP 1 can transmit an NDPA including information of one or more OBSS STAs (e.g., STA 2-1 and STA 2-2 in FIG. 16) and transmit an NDP frame after an SIFS. AP 1 can receive feedback frames (e.g., compressed beamforming / CQI reporting) including channel information from OBSS STAs by transmitting a BFRP TF after an SIFS. At this time, in order for AP 1 to receive feedback frames from STAs within its BSS (e.g., STA 1-1 and STA 1-2 in FIG. 16), information of the corresponding STAs can be included in the NDPA.

[0224] Next, AP 1 may transmit an MU-RTS TXS TF (or control frame) to AP 2, a potential Co-SR / Co-BF based cooperative AP, and perform TXOP sharing (i.e., C-TDMA). At this time, the interval / ID field of the MU-RTS TXS TF (or control frame) may be set to 0 (or an interval until a CTS frame is received), set to an interval corresponding to a value included in the allocated interval field, or set to the remaining TXOP interval of AP 1. Additionally, the MU-RTS TXS TF may include information of OBSS STAs (e.g., STA 2-1 and STA 2-2) acquired through the IM procedure of AP 1 (e.g., channel information received / acquired from the OBSS STAs). For this purpose, the MU-RTS TXS TF may include one or more user information fields and / or special user information fields including information of the OBSS STAs.

[0225] Additionally or alternatively, AP 1 may use the re-acquired TXOP to forward information obtained from the IM procedure to AP 2.

[0226] After SIFS, AP 2 can transmit a CTS frame (or CTS-to-Self frame) and initiate the IM procedure. AP 2, which performed the same sequence as AP 1, can transmit a TXOP return frame (e.g., TXR in FIG. 16) containing information about the acquired OBSS STAs (e.g., STA 1-1 and STA 1-2) to AP 1, thereby ending the allocated time.

[0227] Additionally or alternatively, AP 2 may expire its allocated time without transmitting a TXR frame. If it does not transmit a TXR frame, AP 2 may use a separately acquired TXOP to forward information acquired in the IM procedure to AP 1.

[0228] FIG. 17 illustrates a second example of an OBSS channel TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0229] In Fig. 17, it is assumed that each AP has previously transmitted information about its BSS STAs (or some target STAs) to neighboring cooperative APs through a multi-AP negotiation procedure. Information about the BSS STAs may include at least one of a MAC address, AID, RSSI, or SINR value for identifying each STA. Cooperative APs that determine that an IM procedure is necessary to initiate some multi-AP schemes through the multi-AP negotiation procedure may perform OBSS channel sounding upon acquiring a TXOP. For example, AP 1 in Fig. 17 may acquire a TXOP and perform OBSS channel TB sounding.

[0230] At this time, the OBSS channel sounding procedure of AP 1 can be performed on APs among the surrounding cooperative APs that wish to cooperate based on a multi-AP method (e.g., Co-SR, Co-BF) that requires an IM procedure. In other words, the OBSS channel sounding procedure for surrounding cooperative APs that wish to perform multi-AP operation based on a multi-AP method (e.g., C-TDMA) that does not require an IM procedure can be omitted.

[0231] AP 1 can transmit an NDPA including information of one or more OBSS STAs (e.g., STA 2-1 and STA 2-2 in FIG. 17) and / or information of In-BSS STAs (e.g., STA 1-1 and STA 1-2 in FIG. 17), and transmit an NDP frame after an SIFS. AP 1 can transmit a BFRP TF to the In-BSS STAs (e.g., STA 1-1 and STA 1-2 in FIG. 17) after an SIFS to receive feedback frames (e.g., compressed beamforming / CQI reporting) including channel information from the In-BSS STAs. In addition, AP 1 can transmit a BFRP TF to the OBSS STAs (e.g., STA 2-1 and STA 2-2 in FIG. 17) after an SIFS to receive feedback frames (e.g., compressed beamforming / CQI reporting) including channel information from the OBSS STAs.

[0232] Additionally or alternatively, AP 1 may first transmit the BFRP TF to the OBSS STAs (e.g., STA 2-1 and STA 2-2 in FIG. 17) to receive feedback frames containing channel information (e.g., compressed beamforming / CQI reporting) from the OBSS STAs. That is, each AP may arbitrarily determine the order of BFRP TF transmission.

[0233] Next, AP 1 may transmit an MU-RTS TXS TF (or control frame) to AP 2, a potential Co-SR / Co-BF based cooperative AP, and perform TXOP sharing (i.e., C-TDMA). At this time, the interval / ID field of the MU-RTS TXS TF (or control frame) may be set to 0 (or an interval until a CTS frame is received), set to an interval corresponding to a value included in the allocated interval field, or set to the remaining TXOP interval of AP 1. Additionally, the MU-RTS TXS TF may include information on OBSS STAs (e.g., STA 2-1 and STA 2-2) acquired through the IM procedure of AP 1. For this purpose, the MU-RTS TXS TF may include one or more user information fields and / or special user information fields including information on OBSS STAs.

[0234] Additionally or alternatively, AP 1 may use the re-acquired TXOP to forward information obtained from the IM procedure to AP 2.

[0235] After SIFS, AP 2 can transmit a CTS frame (or CTS-to-Self frame) and initiate the IM procedure. AP 2, which performed the same sequence as AP 1, can transmit a TXOP return frame (e.g., TXR in FIG. 17) containing information about the acquired OBSS STAs (e.g., STA 1-1 and STA 1-2) to AP 1, thereby ending the allocated time.

[0236] Additionally or alternatively, AP 2 may expire its allocated time without transmitting a TXR frame. If it does not transmit a TXR frame, AP 2 may use a separately acquired TXOP to forward information acquired in the IM procedure to AP 1.

[0237] FIG. 18 illustrates a third example of an OBSS channel TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0238] In Fig. 18, it is assumed that each AP has previously transmitted information about its BSS STAs (or some target STAs) to surrounding cooperative APs through a multi-AP negotiation procedure. Information about the BSS STAs may include at least one of a MAC address, AID, RSSI, or SINR value for identifying each STA. Cooperative APs that determine that an IM procedure is necessary to initiate some multi-AP schemes through the multi-AP negotiation procedure may perform OBSS channel sounding upon acquiring a TXOP. For example, AP 1 in Fig. 18 may acquire a TXOP and perform OBSS channel TB sounding.

[0239] At this time, the OBSS channel sounding procedure initiated by AP 1 can be performed on APs among the surrounding cooperative APs that wish to cooperate based on a multi-AP scheme (e.g., Co-SR, Co-BF) that requires an IM procedure. Alternatively, the OBSS channel sounding procedure can be performed between two APs that have established pair-wise cooperation for multi-AP operation based on Co-SR, Co-BF. In other words, the OBSS channel sounding procedure for surrounding cooperative APs that wish to perform multi-AP operation based on a multi-AP scheme (e.g., C-TDMA) that does not require an IM procedure can be omitted.

[0240] AP 1 can transmit an NDPA containing only information of In-BSS STAs (e.g., STA 1-1 and STA 1-2 in FIG. 18), and then transmit an NDP frame after SIFS. After SIFS, AP 1 can transmit a BFRP TF targeting In-BSS STAs to obtain feedback frames / CSI (e.g., compressed beamforming / CQI reporting) containing channel information from In-BSS STAs. The NDP frame at this time can include BSS color information for AP 1.

[0241] To enable AP 2 to acquire CSI for STAs in BSS 1, AP 1 may additionally transmit an NDPA containing information about In-BSS STAs. After an SIFS, AP 2 may transmit an NDP frame targeting STAs in BSS 1. The NDP frame may include BSS color information for AP 1. Subsequently, AP 1 may transmit a BFRP TF targeting In-BSS STAs after an SIFS to receive feedback frames containing channel information from In-BSS STAs. At this time, AP 2 may acquire CSI information about STAs in BSS 1 by overhearing the feedback frame.

[0242] In order to perform an OBSS channel sounding procedure for BSS 2 within the TXOP acquired by AP 1, AP 1 may transmit an MU-RTS TXS trigger frame (or control frame) to AP 2, a potential Co-SR / Co-BF based cooperative AP, to perform TXOP sharing (i.e., C-TDMA). At this time, the interval / ID field of the MU-RTS TXS TF (or control frame) may be set to 0 (or an interval until a corresponding response frame is received), set to an interval corresponding to a value included in the Assigned Interval field, or set to the remaining TXOP interval of AP 1. Additionally, the MU-RTS TXS TF may include information on In-BSS STAs acquired from the IM procedure for BSS 1 performed by AP 1. For this purpose, one or more user information fields or special user information fields containing information of In-BSS STAs may exist within the MU-RTS TXS TF.

[0243] After SIFS, AP 2 may transmit a CTS frame (or a corresponding response frame, a CTS-to-Self frame) and initiate an IM procedure for BSS 2. AP 2, having performed the same IM procedure in the same sequence that AP 1 performed for BSS 1, may end its allocated time by transmitting a TXOP return frame (TXR in FIG. 18) that may include information about the acquired In-BSS STAs (i.e., STAs of BSS 2). Additionally or alternatively, AP 2 may end its allocated time without transmitting a TXR frame.

[0244] FIG. 19 illustrates a fourth example of an OBSS channel TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0245] In Fig. 19, it is assumed that each AP has previously transmitted information about its BSS STAs (or some target STAs) to neighboring cooperative APs through a multi-AP negotiation procedure. Information about the BSS STAs may include at least one of a MAC address, AID, RSSI, or SINR value for identifying each STA. Cooperative APs that determine that an IM procedure is necessary to initiate some multi-AP schemes through the multi-AP negotiation procedure may perform OBSS channel sounding upon acquiring a TXOP. For example, AP 1 in Fig. 19 may acquire a TXOP and perform OBSS channel TB sounding.

[0246] At this time, the OBSS channel sounding procedure initiated by AP 1 can be performed on APs among the surrounding cooperative APs that wish to cooperate based on a multi-AP scheme (e.g., Co-SR, Co-BF) that requires an IM procedure. Alternatively, the OBSS channel sounding procedure can be performed between two APs that have established pair-wise cooperation for multi-AP operation based on Co-SR, Co-BF. In other words, the OBSS channel sounding procedure for surrounding cooperative APs that wish to perform multi-AP operation based on a multi-AP scheme (e.g., C-TDMA) that does not require an IM procedure can be omitted.

[0247] AP 1 can transmit an NDPA that only includes information of In-BSS STAs (e.g., STA 1-1 and STA 1-2 in FIG. 19), and can transmit an NDP frame simultaneously with AP 2 after an SIFS. At this time, the NDP frame transmitted by AP 2 can include BSS color information of AP 1. After an SIFS, AP 1 can transmit a BFRP TF targeting In-BSS STAs to obtain feedback frames / CSI (e.g., compressed beamforming / CQI reporting) information including channel information from In-BSS STAs. AP 2 can overhear the feedback frame and obtain CSI information about STAs of BSS 1 together with AP 1.

[0248] In order to perform an OBSS channel sounding procedure for BSS 2 within the TXOP acquired by AP 1, AP 1 may transmit an MU-RTS TXS trigger frame (or control frame) to AP 2, a potential Co-SR / Co-BF based cooperative AP, to perform TXOP sharing (i.e., C-TDMA). At this time, the interval / ID field of the MU-RTS TXS TF (or control frame) may be set to 0 (or an interval until a corresponding response frame is received), set to an interval corresponding to a value included in the Assigned Interval field, or set to the remaining TXOP interval of AP 1. Additionally, the MU-RTS TXS TF may include information on In-BSS STAs acquired from the IM procedure for BSS 1 performed by AP 1. For this purpose, one or more user information fields or special user information fields containing information of In-BSS STAs may exist within the MU-RTS TXS TF.

[0249] After SIFS, AP 2 may transmit a CTS frame (or, correspondingly, a response frame, a CTS-to-Self frame) and initiate an IM procedure for BSS 2. AP 2 may perform the same IM procedure sequence that AP 1 performed for BSS 1. Afterwards, AP 2 may end its allocated time by transmitting a TXOP return frame (TXR in FIG. 19), which may include information about the acquired In-BSS STAs (i.e., STAs of BSS 2). Additionally or alternatively, AP 2 may end its allocated time without transmitting a TXR frame.

[0250] II. Non-TB Sounding

[0251] FIG. 20 illustrates a first example of an OBSS channel non-TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0252] In Fig. 20, it is assumed that each AP has previously transmitted information about its BSS STAs (or some target STAs) to surrounding cooperative APs through a multi-AP negotiation procedure. To perform an OBSS channel non-TB sounding procedure, AP 1 may transmit information about STA 1-1, and AP 2 may transmit information about STA 2-2. Information about BSS STAs may include at least one of a MAC address, AID, RSSI, or SINR value for identifying each STA. Cooperative APs that determine that an IM procedure is necessary to initiate some multi-AP schemes through the multi-AP negotiation procedure may perform OBSS channel sounding when acquiring a TXOP. For example, AP 1 in Fig. 20 may acquire a TXOP and perform OBSS channel non-TB sounding.

[0253] At this time, the OBSS channel non-TB sounding procedure of AP 1 can be performed on APs among the surrounding cooperative APs that wish to cooperate based on a multi-AP method (e.g., Co-SR, Co-BF) that requires an IM procedure. In other words, the OBSS channel sounding procedure for the surrounding cooperative APs that wish to perform multi-AP operation based on a multi-AP method (e.g., C-TDMA) that does not require an IM procedure can be omitted.

[0254] AP 1 can transmit an NDPA containing information of an OBSS STA (e.g., STA 2-2 in FIG. 20) previously received from AP 2 to STA 2-2, and transmit an NDP frame after SIFS. AP 1 can receive a feedback frame containing channel information (e.g., compressed beamforming / CQI reporting) from STA 2-2, which is the target OBSS STA, after SIFS.

[0255] Next, AP 1 may transmit an MU-RTS TXS TF (or control frame) to AP 2, a potential Co-SR / Co-BF based cooperative AP, and perform a TXOP sharing (i.e., C-TDMA) procedure. At this time, the interval / ID field of the MU-RTS TXS TF (or control frame) may be set to 0 (or the interval until a CTS frame is received), set to an interval corresponding to a value included in the Assigned Interval field, or set to the remaining TXOP interval of AP 1. Additionally, the MU-RTS TXS TF may include information about an OBSS STA (e.g., STA 2-2) acquired through the IM procedure of AP 1. Additionally or alternatively, the MU-RTS TXS TF may include information about a target (e.g., STA 1-1) for which AP 2 should perform an OBSS channel sounding procedure. To this end, the MU-RTS TXS TF may have one or more user information fields and / or special user information fields containing information about the OBSS STAs and / or the target for which AP 2 should perform the OBSS channel sounding procedure (e.g., STA 1-1).

[0256] Additionally or alternatively, AP 1 may forward information obtained from the IM procedure performed using the re-acquired TXOP to AP 2.

[0257] After SIFS, AP 2 can transmit a CTS frame (or CTS-to-Self frame) and initiate the IM procedure. AP 2, which performed the same sequence as AP 1, can transmit a TXOP return frame (e.g., TXR in FIG. 20) containing information about the target OBSS STA (e.g., STA 1-1) to AP 1, thereby ending the allocated time.

[0258] Additionally or alternatively, AP 2 may expire its allocated time without transmitting a TXR frame. If it does not transmit a TXR frame, AP 2 may use a separately acquired TXOP to forward information acquired in the IM procedure to AP 1.

[0259] FIG. 21 illustrates a second example of an OBSS channel non-TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0260] In Fig. 21, it is assumed that each AP has previously transmitted information about its BSS STAs (or some target STAs) to surrounding cooperative APs through a multi-AP negotiation procedure. To perform an OBSS channel non-TB sounding procedure, AP 1 may transmit information about STA 1-1, and AP 2 may transmit information about STA 2-2. Information about BSS STAs may include at least one of a MAC address, AID, RSSI, or SINR value for identifying each STA. Cooperative APs that determine that an IM procedure is necessary to initiate some multi-AP schemes through the multi-AP negotiation procedure may perform OBSS channel sounding when acquiring a TXOP. For example, AP 1 in Fig. 21 may acquire a TXOP and perform OBSS channel non-TB sounding.

[0261] At this time, the OBSS channel sounding procedure of AP 1 can be performed on APs among the surrounding cooperative APs that wish to cooperate based on a multi-AP method (e.g., Co-SR, Co-BF) that requires an IM procedure. In other words, the OBSS channel sounding procedure for surrounding cooperative APs that wish to perform multi-AP operation based on a multi-AP method (e.g., C-TDMA) that does not require an IM procedure can be omitted.

[0262] AP 1 can first transmit an NDPA including information of an In-BSS STA (e.g., STA 1-1 in FIG. 21), and then transmit an NDP frame after an SIFS. AP 1 can receive a feedback frame including channel information (e.g., compressed beamforming / CQI report) from the In-BSS STA (e.g., STA 1-1) after an SIFS. Subsequently, AP 1 can transmit an NDPA including information of an OBSS STA (e.g., STA 2-2 in FIG. 21), and then transmit an NDP frame after an SIFS. AP 1 can receive a feedback frame including channel information (e.g., compressed beamforming / CQI report) from the OBSS STA (e.g., STA 2-2 in FIG. 21) after an SIFS.

[0263] Additionally or alternatively, AP 1 may first transmit NDPA to an OBSS STA (e.g., STA 2-2 in FIG. 21) to receive a feedback frame containing channel information (e.g., compressed beamforming / CQI reporting) from the OBSS STA. That is, each AP may arbitrarily determine the order of NDPA transmissions.

[0264] Next, AP 1 may transmit an MU-RTS TXS TF (or control frame) to AP 2, a potential Co-SR / Co-BF based cooperative AP, and perform TXOP sharing (i.e., C-TDMA). At this time, the interval / ID field of the MU-RTS TXS TF (or control frame) may be set to 0 (or the interval until a CTS frame is received), set to an interval corresponding to a value included in the allocated interval field, or set to the remaining TXOP interval of AP 1. Additionally, the MU-RTS TXS TF may include information about an OBSS STA (e.g., STA 2-2) acquired through an IM procedure of AP 1. Additionally or alternatively, the MU-RTS TXS TF may include information about a target (e.g., STA 1-1) for which AP 2 should perform an OBSS channel sounding procedure. To this end, the MU-RTS TXS TF may have one or more user information fields and / or special user information fields containing information about the OBSS STAs and / or the target for which AP 2 should perform the OBSS channel sounding procedure (e.g., STA 1-1).

[0265] Additionally or alternatively, AP 1 may use the re-acquired TXOP to forward information obtained from the IM procedure to AP 2.

[0266] After SIFS, AP 2 can transmit a CTS frame (or CTS-to-Self frame) and initiate the IM procedure. AP 2, which performed the same sequence as AP 1, can transmit a TXOP return frame (e.g., TXR in FIG. 21) containing information about the acquired OBSS STA (e.g., STA 1-1) to AP 1, thereby ending the allocated time.

[0267] Additionally or alternatively, AP 2 may expire its allocated time without transmitting a TXR frame. If it does not transmit a TXR frame, AP 2 may use a separately acquired TXOP to forward information acquired in the IM procedure to AP 1.

[0268] FIG. 22 illustrates a third example of an OBSS channel non-TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0269] In Fig. 22, it is assumed that each AP has previously transmitted information about its BSS STAs (or some target STAs) to neighboring cooperative APs through a multi-AP negotiation procedure. Information about the BSS STAs may include at least one of a MAC address, AID, RSSI, or SINR value for identifying each STA. Cooperative APs that determine that an IM procedure is necessary to initiate some multi-AP schemes through the multi-AP negotiation procedure may perform OBSS channel sounding upon acquiring a TXOP. For example, AP 1 in Fig. 22 may acquire a TXOP and perform OBSS channel non-TB sounding.

[0270] At this time, the OBSS channel sounding procedure initiated by AP 1 can be performed on APs among the surrounding cooperative APs that wish to cooperate based on a multi-AP scheme (e.g., Co-SR, Co-BF) that requires an IM procedure. Alternatively, the OBSS channel sounding procedure can be performed between two APs that have established pair-wise cooperation for multi-AP operation based on Co-SR, Co-BF. In other words, the OBSS channel sounding procedure for surrounding cooperative APs that wish to perform multi-AP operation based on a multi-AP scheme (e.g., C-TDMA) that does not require an IM procedure can be omitted.

[0271] AP 1 can transmit an NDPA containing only information about the target In-BSS STA (e.g., STA 1-1 in FIG. 22), and then transmit an NDP frame after an SIFS. After the SIFS, AP 1 can obtain feedback frame / CSI (e.g., compressed beamforming / CQI reporting) information containing channel information from the target In-BSS STA. The NDP frame at this time can include BSS color information for AP 1.

[0272] To enable AP 2 to acquire CSI for the target STA of BSS 1, AP 1 may additionally transmit an NDPA including information of the target In-BSS STA. After an SIFS, AP 2 may transmit an NDP frame to the target STA of BSS 1. The NDP frame may include BSS color information for AP 1. After an SIFS, AP 1 may receive a feedback frame including channel information from the target In-BSS STA. At this time, AP 2 may acquire CSI information for the target STA of BSS 1 by overhearing the feedback frame.

[0273] In order to perform an OBSS channel sounding procedure for BSS 2 within the TXOP acquired by AP 1, AP 1 may transmit an MU-RTS TXS trigger frame (or control frame) to AP 2, a potential Co-SR / Co-BF based cooperative AP, to perform TXOP sharing (i.e., C-TDMA). At this time, the interval / ID field of the MU-RTS TXS TF (or control frame) may be set to 0 (or an interval until a corresponding response frame is received), set to an interval corresponding to a value included in the Assigned Interval field, or set to the remaining TXOP interval of AP 1. Additionally, the MU-RTS TXS TF may include information on In-BSS STAs acquired from the IM procedure for BSS 1 performed by AP 1. For this purpose, one or more user information fields or special user information fields containing information of In-BSS STAs may exist within the MU-RTS TXS TF.

[0274] After SIFS, AP 2 may transmit a CTS frame (or a corresponding response frame, a CTS-to-Self frame) and initiate an IM procedure for BSS 2. AP 2, having performed the same IM procedure as AP 1 performed for BSS 1, may end its allocated time by transmitting a TXOP return frame (TXR in FIG. 22) that may include information about the acquired target In-BSS STA (i.e., the STA of BSS 2). Additionally or alternatively, AP 2 may end its allocated time without transmitting a TXR frame.

[0275] FIG. 23 illustrates a fourth example of an OBSS channel non-TB sounding sequence using C-TDMA according to an embodiment of the present disclosure.

[0276] In Fig. 23, it is assumed that each AP has previously transmitted information about its BSS STAs (or some target STAs) to neighboring cooperative APs through a multi-AP negotiation procedure. Information about the BSS STAs may include at least one of a MAC address, AID, RSSI, or SINR value for identifying each STA. Cooperative APs that determine that an IM procedure is necessary to initiate some multi-AP schemes through the multi-AP negotiation procedure may perform OBSS channel sounding upon acquiring a TXOP. For example, AP 1 in Fig. 23 may acquire a TXOP and perform OBSS channel non-TB sounding.

[0277] At this time, the OBSS channel sounding procedure initiated by AP 1 can be performed on APs among the surrounding cooperative APs that wish to cooperate based on a multi-AP scheme (e.g., Co-SR, Co-BF) that requires an IM procedure. Alternatively, the OBSS channel sounding procedure can be performed between two APs that have established pair-wise cooperation for multi-AP operation based on Co-SR, Co-BF. In other words, the OBSS channel sounding procedure for surrounding cooperative APs that wish to perform multi-AP operation based on a multi-AP scheme (e.g., C-TDMA) that does not require an IM procedure can be omitted.

[0278] AP 1 can transmit an NDPA that only includes information of a target In-BSS STA (e.g., STA 1-1 in FIG. 23), and can transmit an NDP frame simultaneously with AP 2 after an SIFS. At this time, the NDP frame transmitted by AP 2 can include BSS color information of AP 1. After an SIFS, AP 1 can obtain feedback frame / CSI (e.g., compressed beamforming / CQI reporting) information including channel information from the target In-BSS STA. AP 2 can overhear the feedback frame and obtain CSI information about the target STA of BSS 1 together with AP 1.

[0279] In order to perform an OBSS channel sounding procedure for BSS 2 within the TXOP acquired by AP 1, AP 1 may transmit an MU-RTS TXS trigger frame (or control frame) to AP 2, a potential Co-SR / Co-BF based cooperative AP, to perform TXOP sharing (i.e., C-TDMA). At this time, the interval / ID field of the MU-RTS TXS TF (or control frame) may be set to 0 (or an interval until a corresponding response frame is received), set to an interval corresponding to a value included in the Assigned Interval field, or set to the remaining TXOP interval of AP 1. Additionally, the MU-RTS TXS TF may include information on In-BSS STAs acquired from the IM procedure for BSS 1 performed by AP 1. For this purpose, one or more user information fields or special user information fields containing information of In-BSS STAs may exist within the MU-RTS TXS TF.

[0280] After SIFS, AP 2 may transmit a CTS frame (or, correspondingly, a response frame, a CTS-to-Self frame) and initiate an IM procedure for BSS 2. AP 2 may perform the same IM procedure sequence that AP 1 performed for BSS 1. Afterwards, AP 2 may end the allocated time by transmitting a TXOP return frame (TXR in FIG. 23), which may include information about the acquired target In-BSS STA (i.e., the STA of BSS 2). Additionally or alternatively, AP 2 may end the allocated time without transmitting a TXR frame.

[0281] According to various embodiments of the present disclosure, through OBSS channel TB and / or non-TB sounding procedures, each AP can obtain interference and / or channel information for STAs connected to neighboring cooperative APs, and use and / or initiate various multi-AP cooperation techniques (e.g., Co-SR, Co-BF, J-TX) based on the obtained information. A method of performing OBSS channel sounding when each AP individually obtains a TXOP can be considered, but using C-TDMA technology, multiple cooperative APs can perform OBSS channel sounding together within a single TXOP obtained by one AP.

[0282] The technical features of the present disclosure described above can be applied to various devices and methods. For example, the technical features of the present disclosure described above can be performed / supported by the devices of FIG. 1 and / or FIG. 5. For example, the technical features of the present disclosure described above can be applied only to a portion of FIG. 1 and / or FIG. 5. For example, the technical features of the present disclosure described above can be implemented based on the processing chip (114, 124) of FIG. 1, or based on the processor (111, 121) and memory (112, 122) of FIG. 1, or based on the processor (510) and memory (520) of FIG. 5.

[0283] For example, the processor (121) and / or the processing chip (124) of FIG. 1 may be configured to execute instructions stored in the memory (122) to perform operations performed by the first AP in the present disclosure. The operations include: initiating a negotiation procedure for multi-AP cooperation with a second AP; acquiring information about one or more neighboring STAs connected to the second AP in the negotiation procedure; transmitting a channel measurement signal to the one or more neighboring STAs based on the information about the one or more neighboring STAs; acquiring channel information about a channel between the first AP and the one or more neighboring STAs after transmitting the channel measurement signal; and performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information.

[0284] For example, the processor (111), the processing chip (114) of FIG. 1, and / or the processor (510) of FIG. 5 may be configured to execute instructions stored in the memory (112, 520) to perform operations performed by an STA connected to a second AP in the present disclosure. The operations include: receiving a channel measurement signal from a first AP; performing channel measurement on a channel between the first AP and the STA based on the channel measurement signal; and transmitting channel information including a result of the channel measurement to the first AP, wherein the first AP is configured to perform operations including: initiating a negotiation procedure for multi-AP cooperation with the second AP; in the negotiation procedure, acquiring information about the STA; transmitting the channel measurement signal to the STA based on the information about the STA; and performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information.

[0285] The technical features of the present disclosure can be implemented based on a computer-readable medium (CRM). For example, the CRM proposed by the present disclosure is at least one computer-readable recording medium containing instructions that are executed by at least one processor.

[0286] For example, the CRM may be the memory (122) of FIG. 1 and / or a separate external memory / storage medium / disk. The CRM may store commands that perform operations performed by the first AP in the present disclosure based on being executed by a processor (e.g., the processor (121) and / or the processing chip (124) of FIG. 1). The operations include: initiating a negotiation procedure for multi-AP cooperation with a second AP; acquiring information about one or more neighboring STAs connected to the second AP in the negotiation procedure; transmitting a channel measurement signal to the one or more neighboring STAs based on the information about the one or more neighboring STAs; acquiring channel information about a channel between the first AP and the one or more neighboring STAs after transmitting the channel measurement signal; and performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information.

[0287] For example, the CRM may be the memory (112) of FIG. 1, the memory (520) of FIG. 5, and / or a separate external memory / storage medium / disk. The CRM may store commands that perform operations performed by an STA connected to a second AP in the present disclosure based on being executed by a processor (e.g., the processor (111), the processing chip (114) of FIG. 1, and / or the processor (510) of FIG. 5). The operations include: receiving a channel measurement signal from a first AP; performing channel measurement on a channel between the first AP and the STA based on the channel measurement signal; and transmitting channel information including a result of the channel measurement to the first AP, wherein the first AP: initiating a negotiation procedure for multi-AP cooperation with the second AP; acquiring information about the STA in the negotiation procedure; transmitting the channel measurement signal to the STA based on the information about the STA; And based on the channel information, it is configured to perform operations including an operation of performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP.

[0288] The technical features of the present disclosure described above are applicable to various applications and business models. For example, the technical features described above can be applied to wireless communication in devices that support artificial intelligence (AI).

[0289] Artificial intelligence (AI) is the study of artificial intelligence or the methodologies for creating it, while machine learning (ML) defines various problems in the field of AI and studies the methodologies for solving them. Machine learning is also defined as an algorithm that improves performance on a task through consistent experience.

[0290] An artificial neural network (ANN) is a model used in machine learning. It can refer to a model with problem-solving capabilities, consisting of artificial neurons (nodes) formed by the connection of synapses to form a network. An ANN can be defined by the connection patterns between neurons in different layers, the learning process that updates model parameters, and the activation function that generates output values.

[0291] An artificial neural network may include an input layer, an output layer, and optionally one or more hidden layers. Each layer contains one or more neurons, and the artificial neural network may include synapses connecting neurons. In an artificial neural network, each neuron can output a function value of an activation function based on input signals, weights, and biases received through the synapses.

[0292] Model parameters are parameters determined through learning, including synaptic connection weights and neuron biases. Hyperparameters are parameters that must be set before learning in machine learning algorithms, including the learning rate, number of iterations, mini-batch size, and initialization function.

[0293] The goal of artificial neural network training can be seen as determining model parameters that minimize a loss function. The loss function can be used as an indicator for determining optimal model parameters during the artificial neural network training process.

[0294] Machine learning can be classified into supervised learning, unsupervised learning, and reinforcement learning depending on the learning method.

[0295] Supervised learning refers to a method for training an artificial neural network when given labels for the training data. The labels can refer to the correct answer (or output value) that the artificial neural network must infer when the training data is input to the artificial neural network. Unsupervised learning can refer to a method for training an artificial neural network when the training data is not given labels. Reinforcement learning can refer to a learning method in which an agent defined within a given environment is trained to select actions or action sequences that maximize the cumulative reward in each state.

[0296] Machine learning implemented with a deep neural network (DNN) containing multiple hidden layers among artificial neural networks is also called deep learning, and deep learning is a subset of machine learning. Hereinafter, the term "machine learning" is used to encompass deep learning.

[0297] Additionally, the above-described technical features can be applied to wireless communication of robots.

[0298] A robot can be defined as a machine that automatically performs or operates a given task based on its own capabilities. Specifically, a robot capable of perceiving its environment, making independent judgments, and performing actions can be called an intelligent robot.

[0299] Robots can be categorized into industrial, medical, household, and military applications based on their intended use or field. Robots are equipped with actuators or motors, enabling them to perform various physical actions, such as moving robot joints. Furthermore, mobile robots incorporate wheels, brakes, and propellers into their actuators, enabling them to move on the ground or fly in the air.

[0300] Additionally, the above-described technical features can be applied to devices that support extended reality.

[0301] Extended reality is a general term for virtual reality (VR), augmented reality (AR), and mixed reality (MR). VR technology presents real-world objects and backgrounds as CG images only, AR technology presents virtual CG images over images of real objects, and MR technology is a computer graphics technology that blends and combines virtual objects with the real world.

[0302] MR technology is similar to AR in that it presents both real and virtual objects simultaneously. However, while AR uses virtual objects to complement real objects, MR uses virtual and real objects on an equal footing.

[0303] XR technology can be applied to HMD (Head-Mount Display), HUD (Head-Up Display), mobile phones, tablet PCs, laptops, desktops, TVs, digital signage, etc., and devices to which XR technology is applied can be called XR devices.

[0304] The present disclosure may have various advantageous effects.

[0305] For example, more efficient OBSS channel sounding can be performed using C-TDMA technology without requiring each AP to perform individual sounding procedures with individually acquired TXOPs.

[0306] The beneficial effects that can be achieved through specific embodiments of the present disclosure are not limited to the beneficial effects listed above. For example, various technical effects may be understood and / or derived from the present disclosure by those skilled in the art. Therefore, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of the present disclosure.

[0307] The claims set forth in this disclosure may be combined in various ways. For example, the technical features of the method claims of this disclosure may be combined and implemented as a device, and the technical features of the device claims of this disclosure may be combined and implemented as a method. Furthermore, the technical features of the method claims of this disclosure and the technical features of the device claims of this disclosure may be combined and implemented as a device, and the technical features of the method claims of this disclosure and the technical features of the device claims of this disclosure may be combined and implemented as a method.

Claims

1. A step in which the first AP (access point) initiates a negotiation procedure for multi-AP cooperation with the second AP; A step in which the first AP obtains information about one or more neighboring STAs connected to the second AP in the negotiation procedure; A step in which the first AP transmits a channel measurement signal to one or more neighboring STAs based on information about the one or more neighboring STAs; A step of obtaining channel information about a channel between the first AP and one or more neighboring STAs after the first AP transmits the channel measurement signal; and A method comprising a step of the first AP performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information.

2. In claim 1, the BSS (basic service set) associated with the second AP is an OBSS (overlapping BSS) for the BSS associated with the first AP, A method in which one or more neighboring STAs belong to the OBSS.

3. A method according to claim 1, wherein the information about the one or more neighboring STAs includes at least one of a MAC (media access control) address of the one or more neighboring STAs, an AID (association identifier) ​​of the one or more neighboring STAs, an RSSI (received signal strength indicator) related to the one or more neighboring STAs, or an SINR (signal to interference plus noise ratio) related to the one or more neighboring STAs.

4. In claim 1, the step of transmitting a channel measurement signal to the one or more neighboring STAs includes a step in which the first AP transmits a channel measurement signal to the one or more neighboring STAs after an announcement frame for initiating channel measurement is transmitted to the one or more neighboring STAs, A method wherein the above notification frame includes information about one or more neighboring STAs.

5. A method according to claim 4, further comprising a step of the first AP transmitting the announcement frame.

6. A method according to claim 4, wherein the notification frame is transmitted by the second AP.

7. In claim 4, the notification frame further includes information about one or more STAs connected to the first AP, A method in which information about the one or more STAs connected to the first AP includes at least one of a MAC (media access control) address of the one or more STAs connected to the first AP or an AID (association identifier) ​​of the one or more STAs connected to the first AP.

8. In claim 4, the channel measurement signal is a NDP (null data packet) frame, The above announcement frame is an NDPA (NDP announcement) frame.

9. A method according to claim 1, further comprising the step of obtaining channel information about a channel between the first AP and the one or more STAs connected to the first AP after the first AP transmits a channel measurement signal to the one or more STAs connected to the first AP.

10. In claim 1, the first AP further includes a step of acquiring a TXOP (transmission opportunity), In the above TXOP section: i) the channel measurement signal is transmitted by the first AP, and ii) the channel information is acquired by the first AP.

11. In claim 10, the first AP further includes a step of transmitting a TXOP shared frame including information about an allocated section within the TXOP section to the second AP, In the above allocation section: i) a channel measurement signal is transmitted by the second AP, and ii) a method in which channel information is acquired by the second AP.

12. A method according to claim 11, wherein in the allocation section: i) the channel measurement signal is transmitted by the first AP, and ii) the channel information is acquired by the first AP.

13. In claim 11, the first AP further includes a step of receiving channel information acquired by the second AP from the second AP, A method wherein the channel information acquired by the second AP includes at least one of: channel information about a channel between the second AP and the one or more neighboring STAs; or channel information about a channel between the second AP and the one or more STAs connected to the first AP.

14. In claim 1, the first AP further includes a step of transmitting channel information acquired by the first AP to the second AP, A method in which the channel information acquired by the first AP includes at least one of: channel information about a channel between the first AP and the one or more neighboring STAs; or channel information about a channel between the first AP and the one or more STAs connected to the first AP.

15. In claim 1, the channel information includes the result of channel measurement performed based on the channel measurement signal, A method wherein the result of the channel measurement includes at least one of a feedback matrix, a channel quality indicator (CQI), a received signal strength indicator (RSSI), a signal to interference plus noise ratio (SINR), transmission power, path loss, or compressed beamforming information.

16. In claim 1, the first AP further includes a step of transmitting a frame for requesting the channel information to one or more neighboring STAs, A method in which the channel information is received from one or more neighboring STAs in response to a frame requesting the channel information.

17. A method according to claim 16, wherein the frame for requesting the channel information includes a BFRP (beamforming report poll) trigger frame.

18. In claim 1, the step of performing transmission related to the multi-AP cooperation comprises: A step in which the first AP performs interference nulling on the one or more neighboring STAs based on at least one of channel information on a channel between the first AP and the one or more neighboring STAs or channel information on a channel between the first AP and the one or more STAs connected to the first AP; and A method comprising a step of the first AP performing a transmission related to the multi-AP cooperation by applying the interference cancellation.

19. A method according to claim 1, wherein the step of performing transmission related to the multi-AP cooperation includes a step in which the first AP performs the transmission based on a coordination scheme for the multi-AP cooperation.

20. A method according to claim 1, wherein the cooperative method includes at least one of Co-BF (coordinated beamforming) or Co-SR (coordinated spatial reuse).

21. In the first AP (access point), Transmitter and receiver; memory; and At least one processor functionally coupled with the transceiver and the memory, The memory stores instructions for performing operations based on being executed by the at least one processor, the operations being: Action to initiate negotiation procedures for multi-AP cooperation with the second AP; In the above negotiation procedure, an operation of obtaining information about one or more neighboring STAs connected to the second AP; An operation of transmitting a channel measurement signal to one or more neighboring STAs based on information about the one or more neighboring STAs; After transmitting the channel measurement signal, an operation of obtaining channel information about a channel between the first AP and the one or more neighboring STAs; and A first AP including an operation of performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information.

22. In the device, at least one processor; and At least one memory functionally coupled with at least one processor, The at least one memory stores instructions that perform operations based on being executed by the at least one processor, the operations being: An action to initiate a negotiation procedure for multi-AP cooperation with a second AP (access point); In the above negotiation procedure, an operation of obtaining information about one or more neighboring STAs connected to the second AP; An operation of transmitting a channel measurement signal to one or more neighboring STAs based on information about the one or more neighboring STAs; After transmitting the channel measurement signal, an operation of obtaining channel information about a channel between the first AP and the one or more neighboring STAs; and A device including an operation for performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information.

23. A non-transitory computer readable medium (CRM) storing program code that implements instructions that perform operations based on being executed by at least one processor, wherein the operations are: An action to initiate a negotiation procedure for multi-AP cooperation with a second AP (access point); In the above negotiation procedure, an operation of obtaining information about one or more neighboring STAs connected to the second AP; An operation of transmitting a channel measurement signal to one or more neighboring STAs based on information about the one or more neighboring STAs; After transmitting the channel measurement signal, an operation of obtaining channel information about a channel between the first AP and the one or more neighboring STAs; and A CRM including an operation of performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information.

24. A step in which a STA (station) connected to a second AP (access point) receives a channel measurement signal from a first AP; A step in which the STA performs channel measurement on a channel between the first AP and the STA based on the channel measurement signal; and The step of the STA transmitting channel information including the result of the channel measurement to the first AP, The above first AP: An action for initiating a negotiation procedure for multi-AP cooperation with the second AP; In the above negotiation procedure, an action of obtaining information about the STA; An operation of transmitting the channel measurement signal to the STA based on information about the STA; and An operation of performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information. A method configured to perform actions including:

25. In a STA (station) connected to a second AP (access point), Transmitter and receiver; memory; and At least one processor functionally coupled with the transceiver and the memory, The memory stores instructions for performing operations based on being executed by the at least one processor, the operations being: An operation of receiving a channel measurement signal from a first AP; An operation of performing channel measurement on a channel between the first AP and the STA based on the channel measurement signal; and Including an operation of transmitting channel information including the result of the channel measurement to the first AP, The above first AP: An action for initiating a negotiation procedure for multi-AP cooperation with the second AP; In the above negotiation procedure, an action of obtaining information about the STA; An operation of transmitting the channel measurement signal to the STA based on information about the STA; and An operation of performing transmission related to the multi-AP cooperation to one or more STAs connected to the first AP based on the channel information. An STA configured to perform actions including:

Images