Signaling method and apparatus based on multi-access point operation in wireless LAN system

Abstract

A method and an apparatus for operating in a wireless LAN system are disclosed. According to one embodiment of the present disclosure, a method performed by a first STA in a wireless LAN system comprises the steps of: receiving a first NDP null data physical protocol data unit (PPUD) advertisement frame from a first AP; receiving an NDP frame from the first AP based on the NDP advertisement frame; and transmitting a feedback frame for the NDP frame to the second AP, in which the NDP advertisement frame may be transmitted to the first STA based on the trigger information transmitted from the second AP.

Description

Technical Field

[0001] The present disclosure relates to communication operations in a wireless local area network (WLAN) system, and more particularly, to a signaling method and apparatus based on multi-access point operations in the WLAN system. Background Art

[0002] New technologies have been introduced for wireless LAN (WLAN) to increase transmission rates, increase bandwidth, improve reliability, reduce errors, and reduce latency. Among WLAN technologies, the Institute of Electrical and Electronics Engineers (IEEE) 802.11 series of standards may be referred to as Wi-Fi. For example, technologies recently introduced to WLAN include the Very High Throughput (VHT) enhancements of the 802.11ac standard and the High Efficiency (HE) enhancements of the IEEE 802.11ax standard.

[0003] In order to provide a more advanced wireless communication environment, improved technologies for extremely high throughput (EHT) are being discussed. For example, technologies for MIMO and multi-access point (AP) coordination that support increased bandwidth, efficient use of multiple frequency bands, and increased spatial streams are being studied, and specifically, various technologies are being studied to support low latency or real-time services. In addition, new technologies are being discussed to support ultra-high reliability (UHR), including improvements or extensions of EHT technologies. Summary of the invention

[0004] Technical issues

[0005] The technical problem of the present disclosure is to provide a signaling method and device based on multi-access point operation in a wireless LAN system.

[0006] A technical problem of the present disclosure is to provide a method and apparatus for performing an OBSS (Overlapping Basic Service Set) detection procedure in a wireless LAN system.

[0007] The technical objectives to be achieved by the present disclosure are not limited to the above-mentioned technical objectives, and those skilled in the art can clearly understand other technical objectives not described herein through the following description.

[0008] Technical Solution

[0009] According to one aspect of the present disclosure, a method for performing communication by a first station (STA) in a wireless LAN system may include receiving a null data physical protocol data unit (PPUD) (NDP) announcement frame from a first AP; receiving an NDP frame from the first AP based on the NDP announcement frame; and sending a feedback frame for the NDP frame to a second AP, and the NDP announcement frame may be sent to the first STA based on trigger information sent from the second AP.

[0010] According to additional aspects of the present disclosure, a method for performing communication by a first AP in a wireless LAN system may include receiving trigger information for sending a null data physical protocol data unit (PPUD) (NDP) announcement frame from a second AP; sending the NDP announcement frame to a first STA based on the trigger information; and sending an NDP frame based on the NDP announcement frame to the first STA, and a feedback frame for the NDP frame may be sent from the first STA to the second AP.

[0011] Technical Effects

[0012] According to various embodiments of the present disclosure, a method and apparatus for signaling based on multiple access point operations in a wireless LAN system may be provided.

[0013] According to various embodiments of the present disclosure, a method and apparatus for performing an overlapping basic service set (OBSS) detection procedure in a wireless LAN system may be provided.

[0014] According to various embodiments of the present disclosure, a measurement operation according to DL / UL transmission between a BSS and a neighboring OBSS may be performed, and thus a multi-access point operation may be efficiently operated.

[0015] Effects achievable by the present disclosure are not limited to the above-described effects, and other effects not described herein may be clearly understood by those skilled in the relevant art through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are included as a part of the detailed description for understanding the present disclosure, provide embodiments of the present disclosure and describe technical features of the present disclosure together with the detailed description.

[0017] Figure 1 A configuration block diagram of a wireless communication device according to an embodiment of the present disclosure is illustrated.

[0018] Figure 2 is a diagram illustrating an exemplary structure of a WLAN system to which the present disclosure can be applied.

[0019] Figure 3 It is a diagram for explaining a link establishment process to which the present disclosure can be applied.

[0020] Figure 4 This is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0021] Figure 5 It is a diagram for explaining a frame transmission operation based on CSMA / CA to which the present disclosure can be applied.

[0022] Figure 6 is a diagram for explaining an example of a frame structure used in a WLAN system to which the present disclosure can be applied.

[0023] Figure 7 is a diagram illustrating an example of a PPDU defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0024] Figure 8 A diagram showing an exemplary format of a trigger frame to which the present disclosure may be applied.

[0025] Fig. 9 It is a diagram for explaining various transmission and reception techniques in a MAP environment to which the present disclosure can be applied.

[0026] Fig.10 2 is a diagram for explaining a process of obtaining channel state information between BSS / OBSS AP / STA according to an embodiment of the present disclosure.

[0027] Fig.11 is a diagram for explaining an operation performed by a first STA according to an embodiment of the present disclosure.

[0028] Fig.12 is a diagram for explaining operations performed by a first AP according to an embodiment of the present disclosure.

[0029] Fig.13 is a diagram for explaining an OBSS detection process according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description disclosed by the accompanying drawings is intended to describe exemplary embodiments of the present disclosure, rather than to represent the only embodiment in which the present disclosure can be implemented. The following detailed description includes specific details to provide a complete understanding of the present disclosure. However, those skilled in the relevant art know that the present disclosure can be implemented without these specific details.

[0031] In some cases, well-known structures and devices may be omitted, or may be shown in the form of a block diagram based on the core functions of each structure and device in order to prevent ambiguity of the concepts of the present disclosure.

[0032] In the present disclosure, when an element is referred to as being "connected", "combined" or "linked" to another element, it may include an indirect connection relationship between another element and a direct connection relationship. In addition, in the present disclosure, the term "comprising" or "having" specifies the presence of the mentioned features, steps, operations, components and / or elements, but does not exclude the presence or addition of one or more other features, stages, operations, components, elements and / or groups thereof.

[0033] In the present disclosure, terms such as "first", "second", etc. are only used to distinguish one element from another element and are not used to limit the elements, and unless otherwise specified, they do not limit the order or importance between elements, etc. Therefore, within the scope of the present disclosure, the first element in an embodiment may be referred to as the second element in another embodiment, and similarly, the second element in an embodiment may be referred to as the first element in another embodiment.

[0034] The terms used in this disclosure are intended to describe specific embodiments, rather than to limit the claims. As used in the description of the embodiments and the appended claims, the singular form is intended to include the plural form, unless the context clearly indicates otherwise. The term "and / or" used in this disclosure may refer to one of the related enumerated items, or mean that it refers to and includes any and all possible combinations of two or more of them. In addition, unless otherwise stated, the " / " between words in this disclosure has the same meaning as "and / or".

[0035] Examples of the present disclosure can be applied to various wireless communication systems. For example, examples of the present disclosure can be applied to wireless LAN systems. For example, examples of the present disclosure can be applied to wireless LANs based on IEEE 802.11a / g / n / ac / ax standards. In addition, examples of the present disclosure can be applied to wireless LANs based on the newly proposed IEEE 802.11be (or EHT) standard. Examples of the present disclosure can be applied to wireless LANs based on the IEEE802.11be version 2 standard corresponding to the additional enhanced technology of the IEEE 802.11be version 1 standard. In addition, examples of the present disclosure can be applied to wireless LANs based on next-generation standards after IEEE 802.11be. In addition, examples of the present disclosure can be applied to cellular wireless communication systems. For example, it can be applied to cellular wireless communication systems based on long-term evolution (LTE) technology and 5G new radio (NR) technology based on the third generation partnership project (3GPP) standard.

[0036] Hereinafter, technical features of examples to which the present disclosure can be applied will be described.

[0037] Figure 1 A block diagram of a wireless communication device according to an embodiment of the present disclosure is illustrated.

[0038] Figure 1The first device 100 and the second device 200 illustrated in the figure may be replaced with various terms such as terminal, wireless device, wireless transmit / receive unit (WTRU), user equipment (UE), mobile station (MS), user terminal (UT), mobile subscriber station (MSS), mobile subscriber unit (MSU), subscriber station (SS), advanced mobile station (AMS), wireless terminal (WT) or simple user, etc. In addition, the first device 100 and the second device 200 include an access point (AP), a base station (BS), a fixed station, a node B, a base transceiver system (BTS), a network. It may be replaced with various terms such as an artificial intelligence (AI) system, a roadside unit (RSU), a repeater, a router, a relay and a gateway.

[0039] Figure 1 The devices 100 and 200 illustrated in the example may be referred to as stations (STAs). Figure 1 The devices 100 and 200 illustrated in the figure may be referred to by various terms such as a transmitting device, a receiving device, a transmitting STA, and a receiving STA. For example, the STAs 110 and 200 may perform an access point (AP) role or a non-AP role. That is, in the present disclosure, the STAs 110 and 200 may perform the functions of an AP and / or a non-AP. When the STAs 110 and 200 perform the AP function, they may be simply referred to as APs, and when the STAs 110 and 200 perform the non-AP function, they may be simply referred to as STAs. In addition, in the present disclosure, an AP may also be indicated as an AP STA.

[0040] Reference Figure 1 , the first device 100 and the second device 200 can send and receive radio signals through various wireless LAN technologies (e.g., IEEE802.11 series). The first device 100 and the second device 200 may include interfaces for a media access control (MAC) layer and a physical layer (PHY) that conform to the IEEE802.11 standard.

[0041] In addition, in addition to the wireless LAN technology, the first device 100 and the second device 200 may further support various communication standards (e.g., 3GPP LTE series, 5G NR series standards, etc.) technologies. In addition, the device of the present disclosure may be implemented in various devices such as mobile phones, vehicles, personal computers, augmented reality (AR) devices, and virtual reality (VR) devices. In addition, the STA of the present specification may support various communication services such as voice calls, video calls, data communications, autonomous driving, machine type communications (MTC), machine to machine (M2M), device to device (D2D), IoT (Internet of Things), etc.

[0042] The first device 100 may include one or more processors 102 and one or more memories 104, and may further include one or more transceivers 106 and / or one or more antennas 108. The processor 102 may control the memory 104 and / or the transceiver 106, and may be configured to implement the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts included in the present disclosure. For example, the processor 102 may send a wireless signal including the first information / signal through the transceiver 106 after generating the first information / signal by processing the information in the memory 104. In addition, the processor 102 may receive a wireless signal including the second information / signal through the transceiver 106, and then store the information obtained by the signal processing of the second information / signal in the memory 104. The memory 104 may be connected to the processor 102 and may store various information related to the operation of the processor 102. For example, the memory 104 may store software codes including instructions for executing all or part of the processing controlled by the processor 102 or for executing the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts included in the present disclosure. Here, the processor 102 and the memory 104 may be part of a communication modem / circuit / chip designed to implement wireless LAN technology (e.g., IEEE 802.11 series). The transceiver 106 may be connected to the processor 102 and may send and / or receive wireless signals through one or more antennas 108. The transceiver 106 may include a transmitter and / or a receiver. The transceiver 106 may be used in conjunction with an RF (radio frequency) unit. In the present disclosure, a wireless device may refer to a communication modem / circuit / chip.

[0043] The second device 200 may include one or more processors 202 and one or more memories 204, and may further include one or more transceivers 206 and / or one or more antennas 208. The processor 202 may control the memory 204 and / or the transceiver 206, and may be configured to implement the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts included in the present disclosure. For example, the processor 202 may generate third information / signals by processing the information in the memory 204, and then send a wireless signal including the third information / signal through the transceiver 206. In addition, the processor 202 may receive a wireless signal including fourth information / signals through the transceiver 206, and then store information obtained by signal processing of the fourth information / signal in the memory 204. The memory 204 may be connected to the processor 202 and may store various information related to the operation of the processor 202. For example, the memory 204 may store software codes including instructions for executing all or part of the processing controlled by the processor 202 or for executing the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts included in the present disclosure. Here, the processor 202 and the memory 204 may be part of a communication modem / circuit / chip designed to implement wireless LAN technology (e.g., IEEE 802.11 series). The transceiver 206 may be connected to the processor 202 and may send and / or receive wireless signals through one or more antennas 208. The transceiver 206 may include a transmitter and / or a receiver. The transceiver 206 may be used in conjunction with an RF unit. In the present disclosure, a device may refer to a communication modem / circuit / chip.

[0044] In the following, the hardware elements of the apparatus 100, 200 will be described in more detail. Without limitation thereto, one or more protocol layers may be implemented by one or more processors 102, 202. For example, one or more processors 102, 202 may implement one or more layers (e.g., functional layers such as PHY, MAC). One or more processors 102, 202 may generate one or more PDUs (protocol data units) and / or one or more SDUs (service data units) according to the description, function, process, suggestion, method, and / or operation flow chart disclosed in the present disclosure. One or more processors 102, 202 may generate messages, control information, data, or information according to the description, function, process, suggestion, method, and / or operation flow chart disclosed in the present disclosure. One or more processors 102, 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the functions, processes, suggestions, and / or methods disclosed in the present disclosure to provide them to one or more transceivers 106, 206. One or more processors 102, 202 may receive a signal (e.g., a baseband signal) from one or more transceivers 106, 206 according to the descriptions, functions, processes, suggestions, methods, and / or operational flow charts included in the present disclosure and obtain a PDU, SDU, message, control information, data, or information.

[0045] One or more processors 102, 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. One or more processors 102, 202 may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more ASICs (Application Specific Integrated Circuits), one or more DSPs (Digital Signal Processors), one or more DSPDs (Digital Signal Processing Devices), one or more PLDs (Programmable Logic Devices), or one or more FPGAs (Field Programmable Gate Arrays) may be included in one or more processors 102, 202. The descriptions, functions, processes, suggestions, methods, and / or operational flow charts included in the present disclosure may be implemented using firmware or software, and the firmware or software may be implemented to include modules, processes, functions, and the like. Firmware or software configured to execute the descriptions, functions, processes, suggestions, methods, and / or operational flow charts included in the present disclosure may be included in one or more processors 102, 202, or may be stored in one or more memories 104, 204 and driven by one or more processors 102, 202. The descriptions, functions, processes, suggestions, methods and / or operational flow charts included in the present disclosure may be implemented using firmware or software in the form of codes, instructions and / or instruction sets.

[0046] One or more memories 104, 204 may be connected to one or more processors 102, 202 and may store data, signals, messages, information, programs, codes, instructions, and / or commands in various forms. One or more memories 104, 204 may be configured with ROM, RAM, EPROM, flash memory, hard drive, registers, cache memory, computer-readable storage media, and / or combinations thereof. One or more memories 104, 204 may be located inside and / or outside one or more processors 102, 202. In addition, one or more memories 104, 204 may be connected to one or more processors 102, 202 via various technologies such as wired or wireless connections.

[0047] One or more transceivers 106, 206 may send user data, control information, wireless signals / channels, etc. mentioned in the method and / or operation flow chart of the present disclosure to one or more other devices. One or more transceivers 106, 206 may receive user data, control information, wireless signals / channels, etc. mentioned in the description, function, process, suggestion, method and / or operation flow chart, etc. included in the present disclosure from one or more other devices. For example, one or more transceivers 106, 206 may be connected to one or more processors 102, 202 and may send and receive wireless signals. For example, one or more processors 102, 202 may control one or more transceivers 106, 206 to send user data, control information or wireless signals to one or more other devices. In addition, one or more processors 102, 202 may control one or more transceivers 106, 206 to receive user data, control information or wireless signals from one or more other devices. In addition, one or more transceivers 106, 206 may be connected to one or more antennas 108, 208, and one or more transceivers 106, 206 may be configured to send and receive user data, control information, wireless signals / channels, etc. mentioned in the description, functions, processes, suggestions, methods and / or operation flow charts, etc. included in the present disclosure through one or more antennas 108, 208. In the present disclosure, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers 106, 206 may convert received wireless signals / channels, etc. from RF band signals into baseband signals to process received user data, control information, wireless signals / channels, etc. by using one or more processors 102, 202. One or more transceivers 106, 206 may convert user data, control information, wireless signals / channels, etc. processed by using one or more processors 102, 202 from baseband signals into RF band signals. Thus, one or more of the transceivers 106 , 206 may include (analog) oscillators and / or filters.

[0048] For example, one of the STAs 100 and 200 may perform the expected operation of an AP, and the other of the STAs 100 and 200 may perform the expected operation of a non-AP STA. Figure 1 The transceivers 106 and 206 of the present invention may perform transmission and reception operations of signals (e.g., packets or physical layer protocol data units (PPDUs) compliant with IEEE 802.11a / b / g / n / ac / ax / be / bn). In addition, in the present disclosure, operations of various STAs generating transmission / reception signals or performing data processing or calculations on transmission / reception signals in advance may be performed by Figure 1The processors 102 and 202 are executed. For example, examples of operations of generating a transmission / reception signal or performing data processing or calculation for the transmission / reception signal in advance may include: 1) determining / obtaining / configuring / calculating / decoding / encoding bit information of fields (signal (SIG), short training field (STF), long training field (LTF), data, etc.) included in the PPDU; 2) determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) for fields (SIG, STF, LTF, data, etc.) included in the PPDU; 3) determining / configuring / obtaining a specific sequence (e.g., pilot sequence, STF / LTF sequence, additional sequence applied to SIG) for fields (SIG, STF, LTF, data, etc.) included in the PPDU action; 4) power control operations and / or power saving operations applied to STAs; 5) operations related to ACK signal determination / obtaining / configuring / calculating / decoding / encoding, etc. In addition, in the following example, various information used by various STAs to determine / acquire / configure / calculate / decode / encode transmission signals and reception signals (e.g., information related to fields / subfields / control fields / parameters / power, etc.) may be stored in Figure 1 in the memories 104 and 204.

[0049] Hereinafter, a downlink (DL) may mean a link for communication from an AP STA to a non-AP STA, and a DL PPDU / packet / signal may be transmitted and received through the DL. In DL communication, a transmitter may be a part of an AP STA, and a receiver may be a part of a non-AP STA. An uplink (UL) may mean a link for communication from a non-AP STA to an AP STA, and a UL PPDU / packet / signal may be transmitted and received through the UL. In UL communication, a transmitter may be a part of a non-AP STA, and a receiver may be a part of an AP STA.

[0050] Figure 2 is a diagram illustrating an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0051] The structure of the wireless LAN system may be composed of a plurality of components. A wireless LAN supporting STA mobility transparent to an upper layer may be provided through the interaction of the plurality of components. A basic service set (BSS) corresponds to a basic building block of a wireless LAN. Figure 2 It is exemplarily shown that two BSSs (BSS1 and BSS2) exist, and two STAs (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2) are included as members of each BSS. Figure 2The ellipse representing the BSS in the figure can also be understood as representing the coverage area in which the STAs included in the corresponding BSS maintain communication. This area can be called a basic service area (BSA). When a STA moves outside the BSA, it cannot communicate directly with other STAs in the BSA.

[0052] If you don't consider Figure 2 , the most basic BSS type in the wireless LAN is an independent BSS (IBSS), if the DS is shown in FIG. 1 . For example, an IBSS may have a minimum form containing only two STAs. For example, assuming that other components are omitted, a BSS1 containing only STA1 and STA2 or a BSS2 containing only STA3 and STA4 may correspond to representative examples of IBSSs, respectively. This configuration is possible when STAs can communicate directly without an AP. In addition, in this type of wireless LAN, it is not pre-configured but can be configured when a LAN is needed, and this may be referred to as an ad-hoc network. Since the IBSS does not include an AP, there is no centralized management entity. That is, in the IBSS, STAs are managed in a distributed manner. In the IBSS, all STAs may be composed of mobile STAs, and access to the distributed system (DS) is not allowed, thereby forming a self-contained network.

[0053] The membership of a STA in a BSS can be changed dynamically by turning the STA on or off, entering or exiting a BSS region, etc. In order to become a member of a BSS, a STA can join the BSS using a synchronization process. In order to access all services of the BSS infrastructure, a STA should associate with the BSS. This association can be established dynamically and can include the use of a distributed system service (DSS).

[0054] The direct STA-to-STA distance in a wireless LAN may be limited by PHY performance. In some cases, this distance limitation may be sufficient, but in some cases, communication between STAs at longer distances may be required. A distributed system (DS) can be configured to support extended coverage.

[0055] DS refers to the structure of BSS interconnection. Specifically, Figure 2As shown, the BSS can exist as an extended form of a network composed of multiple BSSs. DS is a logical concept and can be specified by the characteristics of the distributed system medium (DSM). At this point, the wireless medium (WM) and the DSM can be logically separated. Each logical medium is used for different purposes and is used by different components. These media are not limited to being the same, nor are they limited to being different. In this way, the flexibility of the wireless LAN structure (DS structure or other network structure) can be interpreted as multiple media being logically different. That is, the wireless LAN structure can be implemented in various ways, and the corresponding wireless LAN structure can be independently specified by the physical characteristics of each implementation.

[0056] DS can support mobile devices by providing seamless integration of multiple BSSs and providing logical services necessary to address the address leading to the destination. In addition, DS can also include a component called a portal, which is used as a bridge for connection between wireless LAN and other networks (e.g., IEEE 802.X).

[0057] The AP enables access to the DS through the WM for associated non-AP STAs and means an entity that also has STA functionality. Data movement between the BSS and the DS can be performed through the AP. For example, Figure 2 STA2 and STA3 shown in the figure have the function of STA and provide the function of allowing the associated non-AP STA (STA1 and STA4) to access the DS. In addition, since all APs basically correspond to STAs, all APs are addressable entities. The address used by the AP to communicate on the WM is not necessarily the same as the address used by the AP to communicate on the DSM. A BSS composed of an AP and one or more STAs may be referred to as an infrastructure BSS.

[0058] Data sent from one of the STAs associated with the AP to the STA address of the corresponding AP can always be received at the uncontrolled port and can be processed by the IEEE 802.1X port access entity. In addition, when the controlled port is authenticated, the transmitted data (or frame) can be delivered to the DS.

[0059] In addition to the above-mentioned structure of the DS, an extended service set (ESS) may also be configured to provide wide coverage.

[0060] ESS means a network with arbitrary size and complexity consisting of DS and BSS. ESS may correspond to a set of BSSs connected to one DS. However, ESS does not include DS. The ESS network is characterized by being regarded as an IBSS in the logical link control (LLC) layer. The STAs included in the ESS can communicate with each other, and the mobile STA can move from one BSS to another (within the same ESS) transparently for LLC. The APs included in one ESS may have the same service set identifier (SSID). SSID is distinguished from BSSID, which is an identifier of BSS.

[0061] The wireless LAN system does not assume anything about the relative physical location of the BSS, and all of the following forms are possible. The BSS may partially overlap, which is a form commonly used to provide continuous coverage. In addition, the BSS may not be physically connected, and logically, there is no limit on the distance between the BSS. In addition, the BSS may be physically located in the same location, which can be used to provide redundancy. In addition, one (or more than one) IBSS or ESS network may physically exist in the same space as one (or more than one) ESS network. When an ad hoc network operates in a location where an ESS network exists, when physically overlapping wireless networks are configured by different organizations, or when two or more different access and security policies are required in the same location, this may correspond to the form of an ESS network, etc.

[0062] Figure 3 is a diagram for explaining a link establishment process to which the present disclosure can be applied.

[0063] In order for a STA to establish a link with respect to a network and send / receive data, it first discovers the network, performs authentication, establishes association, and needs to perform authentication processing for security. The link establishment processing may also be referred to as a session initiation processing or a session establishment processing. In addition, the discovery, authentication, association, and security establishment processing of the link establishment processing may be collectively referred to as an association processing.

[0064] In step S310, the STA may perform a network discovery operation. The network discovery operation may include a scanning operation of the STA. That is, in order for the STA to access a network, it needs to find a network that it can participate in. The STA should identify compatible networks before participating in a wireless network, and the process of identifying networks present in a specific area is called scanning.

[0065] Scanning schemes include active scanning and passive scanning. Figure 3The network discovery operation including active scanning processing is exemplarily illustrated. In active scanning, the STA performing the scan sends a probe request frame to discover which APs exist around it while the channel moves and waits for a response thereto. The responder sends a probe response frame as a response to the probe request frame to the STA that has sent the probe request frame. Here, the responder may be the STA that last sent a beacon frame in the BSS of the channel being scanned. In the BSS, since the AP sends a beacon frame, the AP becomes the responder, and in the IBSS, the STAs in the IBSS rotate to send beacon frames, so the responder is not constant. For example, a STA that sends a probe request frame on channel 1 and receives a probe response frame on channel 1 may store the BSS-related information included in the received probe response frame, and may move to the next channel (e.g., channel 2), and perform scanning in the same manner (i.e., sending and receiving probe requests / responses on channel 2).

[0066] Although not in Figure 3 , but the scanning operation can be performed in a passive scanning manner. In passive scanning, the STA performing the scan waits for a beacon frame while the channel moves. The beacon frame is one of the management frames defined in IEEE 802.11, and is periodically sent to notify the existence of a wireless network and allow the STA performing the scan to find the wireless network and participate in the wireless network. In the BSS, the AP is used to periodically send beacon frames, and in the IBSS, the STAs within the IBSS rotate to send beacon frames. When the STA performing the scan receives the beacon frame, the STA stores the information of the BSS included in the beacon frame, and records the beacon frame information in each channel while moving to another channel. The STA receiving the beacon frame can store the BSS-related information included in the received beacon frame, move to the next channel, and perform scanning in the next channel in the same manner. Comparing active scanning with passive scanning, the advantage of active scanning is that it has less delay and less power consumption than passive scanning.

[0067] After the STA discovers the network, an authentication process may be performed at step S320. In order to clearly distinguish from the security establishment operation of step S340 to be described later, this authentication process may be referred to as a first authentication process.

[0068] The authentication process includes the following process: the STA sends an authentication request frame to the AP, and in response thereto, the AP sends an authentication response frame to the STA. The authentication frame for authentication request / response corresponds to a management frame.

[0069] The authentication frame includes an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a robust security network (RSN), a limited cycle group, etc. This corresponds to some examples of information that can be included in the authentication request / response frame, and can be replaced with other information, or additional information can also be included.

[0070] The STA may send an authentication request frame to the AP. The AP may determine whether to allow authentication of the corresponding STA based on the information included in the received authentication request frame. The AP may provide the result of the authentication process to the STA via an authentication response frame.

[0071] After the STA is successfully authenticated, an association process may be performed at step S330. The association process includes the following processes: the STA sends an association request frame to the AP, and in response, the AP sends an association response frame to the STA.

[0072] For example, the association request frame may include information related to various capabilities, a beacon listening interval, a service set identifier (SSID), supported rates, supported channels, RSN, a mobile domain, supported operation categories, a traffic indication map broadcast request (TIM broadcast request), interworking service capabilities, etc. For example, the association response frame may include information related to various capabilities, a status code, an association ID (AID), supported rates, an enhanced distributed channel access (EDCA) parameter set, a received channel power indicator (RCPI), a received signal-to-noise ratio indicator (RSNI), a mobile domain, a timeout interval (e.g., an association recovery time), an overlapping BSS scan parameter, a TIM broadcast response, a quality of service (QoS) map, etc. This corresponds to some examples of information that may be included in an association request / response frame, and may be replaced with other information, or may also include additional information.

[0073] After the STA successfully associates with the network, a security establishment process may be performed at step S340. The security establishment process at step S340 may be referred to as an authentication process through a robust security network association (RSNA) request / response, the authentication process at step S320 may be referred to as a first authentication process, and the security establishment process at step S340 may also be referred to simply as an authentication process.

[0074] The security establishment process of step S340 may include, for example, a process of establishing a private key through an Extensible Authentication Protocol over LAN (EAPOL) frame using a four-way handshake. In addition, the security establishment process may be performed according to a security scheme not defined in the IEEE 802.11 standard.

[0075] Figure 4 It is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0076] In a wireless LAN system, the basic access mechanism of the medium access control (MAC) is a carrier sense multiple access with collision avoidance (CSMA / CA) mechanism. The CSMA / CA mechanism is also known as the distributed coordination function (DCF) of the IEEE 802.11 MAC, and basically adopts a "listen before talk" access mechanism. According to this type of access mechanism, before starting to send, the AP and / or STA may perform a clear channel assessment (CCA) of sensing the radio channel or medium during a predetermined time interval (e.g., DCF interframe space (DIFS)). As a result of the sensing, if it is determined that the medium is in an idle state, frame transmission is started through the corresponding medium. On the other hand, if it is detected that the medium is occupied or busy, the corresponding AP and / or STA does not start its own transmission, and a delay period (e.g., a random backoff period) for medium access may be set and frame transmission may be attempted after waiting. By applying a random backoff period, since multiple STAs are expected to attempt frame transmission after waiting for different time periods, conflicts can be minimized.

[0077] In addition, the IEEE 802.11 MAC protocol provides a hybrid coordination function (HCF). HCF is based on DCF and point coordination function (PCF). PCF is a synchronous access method based on polling, and refers to a method in which all receiving APs and / or STAs periodically poll to receive data frames. In addition, HCF has enhanced distributed channel access (EDCA) and HCF controlled channel access (HCCA). EDCA is a contention-based access method that provides data frames to multiple users in a direction, and HCCA uses a non-contention-based channel access method that utilizes a polling mechanism. In addition, HCF includes a medium access mechanism for improving the QoS (quality of service) of a wireless LAN, and QoS data can be sent during a contention period (CP) and a contention-free period (CFP).

[0078] Reference Figure 4, the operation based on the random backoff period will be described. When the occupied / busy medium becomes idle, multiple STAs may attempt to send data (or frames). As a method of minimizing conflicts, each of the STAs may select a random backoff count respectively and attempt to send after waiting for the corresponding time slot time. The random backoff count has a pseudo-random integer value and may be determined as one of the values ​​ranging from 0 to CW. Here, CW is a contention window parameter value. The CW parameter is assigned CWmin as an initial value, but may take a value twice as large in the event of a transmission failure (e.g., when an ACK for a transmitted frame is not received). When the CW parameter value reaches CWmax, data transmission may be attempted while maintaining the CWmax value until data transmission is successful, and when data transmission is successful, the CWmin value is reset. The values ​​of CW, CWmin, and CWmax are preferably set to 2n-1 (n=0, 1, 2, ...).

[0079] When the random backoff process starts, the STA continuously monitors the medium in the backoff slot countdown according to the determined backoff count value. When the medium is monitored for occupancy, it stops the countdown and waits, and restarts the remaining part of the countdown when the medium becomes idle.

[0080] exist Figure 4 In the example of , when the packet to be sent arrives at the MAC of STA 3, STA3 can send the frame immediately after confirming that the medium has been idle for up to DIFS. The remaining STAs monitor and wait for the medium to be occupied / busy. At the same time, the data to be sent can also occur in each of STA1, STA2 and STA5, and when the medium is monitored as idle, each STA waits for up to DIFS, and then the countdown of the backoff slot can be performed according to the random backoff count value selected by each STA. Assume that STA2 selects the minimum backoff count value and STA1 selects the maximum backoff count value. That is, the example illustrates the case where the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1 when STA2 completes the backoff count and starts frame transmission. STA1 and STA5 temporarily stop the countdown and wait when STA2 occupies the medium. When STA2's occupation ends and the medium becomes idle again, STA1 and STA5 wait for DIFS and restart the stopped backoff count. That is, frame transmission can start after counting down the remaining backoff slot for the remaining backoff time. Since the remaining backoff time of STA5 is shorter than that of STA1, STA5 starts frame transmission. The data to be transmitted may also occur in STA4 while STA2 occupies the medium. From the perspective of STA4, when the medium becomes idle, STA4 may wait for DIFS, and then may perform a countdown according to a random backoff count value selected by STA4, and start transmitting frames. Figure 4The example shows a case where the remaining backoff time of STA5 accidentally collides with the random backoff count value of STA4. In this case, a collision may occur between STA4 and STA5. When a collision occurs, neither STA4 nor STA5 receives an ACK, so data transmission fails. In this case, STA4 and STA5 can double the CW value, select a random backoff count value, and perform a countdown. While the medium is occupied due to the transmission of STA4 and STA5, STA1 waits, and when the medium becomes idle, STA1 waits DIFS, and then starts frame transmission after the remaining backoff time has passed.

[0081] As in Figure 4 In the example of , a data frame is a frame for sending data forwarded to a higher layer, and may be sent after a backoff performed after DIFS has passed since the medium became idle. In addition, a management frame is a frame for exchanging management information that is not forwarded to a higher layer, and is sent after a backoff is performed after an IFS such as DIFS or a point coordination function IFS (PIFS). As subtype frames of the management frame, there are beacons, association requests / responses, reassociation requests / responses, probe requests / responses, authentication requests / responses, and the like. A control frame is a frame for controlling access to a medium. As subtype frames of the control frame, there are request to send (RTS), clear to send (CTS), acknowledgement (ACK), power save poll (PS-Poll), block ACK (BlockAck), block ACK request (BlockACKReq), empty data packet announcement (NDP announcement), and trigger, and the like. If the control frame is not a response frame of the previous frame, it is sent after performing a backoff after DIFS has passed, and if it is a response frame of the previous frame, it is sent without performing a backoff after a short IFS (SIFS) has passed. The type and subtype of the frame can be identified by the type field and subtype field in the frame control (FC) field.

[0082] Quality of Service (QoS) STA can perform a backoff performed after arbitration IFS (AIFS) (i.e., AIFS (where i is a value determined by AC)) for the access category (AC) to which the frame belongs, and then can send the frame. Here, the frame that can use AIFS may be a data frame, a management frame, or a control frame instead of a response frame.

[0083] Figure 5 is a diagram for explaining a frame transmission operation based on CSMA / CA to which the present disclosure can be applied.

[0084] As described above, in addition to the physical carrier sensing in which the STA directly senses the medium, the CSMA / CA mechanism also includes virtual carrier sensing. Virtual carrier sensing is intended to compensate for problems such as hidden node problems that may occur in medium access. For virtual carrier sensing, the MAC of the STA can use a network allocation vector (NAV). NAV is a value that indicates to other STAs the remaining time until the medium is available for use by the STA that is currently using or has the right to use the medium. Therefore, the value set to NAV corresponds to the period during which the STA sending the frame plans to use the medium, and during the corresponding period, the STA receiving the NAV value is prohibited from accessing the medium. For example, the NAV can be configured based on the value of the "Duration" field of the MAC header of the frame.

[0085] exist Figure 5 In the example of FIG. 1 , it is assumed that STA1 intends to send data to STA2, and STA3 is in a position to be able to eavesdrop on some or all frames sent and received between STA1 and STA2.

[0086] In order to reduce the possibility of transmission conflicts among multiple STAs in the CSMA / CA-based frame transmission operation, a mechanism using RTS / CTS frames can be applied. Figure 5 In the example of , when STA1's transmission is being performed, as a result of STA3's carrier sensing, it can be determined that the medium is in an idle state. That is, STA1 may correspond to a hidden node with respect to STA3. Alternatively, in Figure 5 In the example of , it can be determined that the carrier sensing result medium of STA3 is in an idle state while the transmission of STA2 is being performed. That is, STA2 may correspond to a hidden node with respect to STA3. By exchanging RTS / CTS frames before performing data transmission and reception between STA1 and STA2, STAs outside the transmission range of one of STA1 or STA2 or STAs outside the carrier sensing range of the transmission from STA1 or STA3 may not attempt to occupy the channel during data transmission and reception between STA1 and STA2.

[0087] Specifically, STA1 can determine whether the channel is being used by carrier sensing. In terms of physical carrier sensing, STA1 can determine the channel occupancy idle state based on the energy level or signal correlation detected in the channel. In addition, in terms of virtual carrier sensing, STA1 can use the network allocation vector (NAV) timer to determine the channel occupancy state.

[0088] When the channel is in an idle state during DIFS, STA1 may send an RTS frame to STA2 after performing backoff. When STA2 receives the RTS frame, STA2 may send a CTS frame to STA1 as a response to the RTS frame after SIFS.

[0089] If STA3 cannot eavesdrop on the CTS frame from STA2 but can eavesdrop on the RTS frame from STA1, STA3 can set the NAV timer for the frame transmission period (e.g., SIFS+CTS frame+SIFS+data frame+SIFS+ACK frame) that is continuously transmitted thereafter using the duration information included in the RTS frame. Alternatively, if STA3 can eavesdrop on the CTS frame from STA2, STA3 can set the NAV timer for the frame transmission period (e.g., SIFS+data frame+SIFS+ACK frame) that is continuously transmitted thereafter using the duration information included in the CTS frame even though STA3 cannot eavesdrop on the RTS frame from STA1. That is, if STA3 can eavesdrop on one or more of the RTS frame or the CTS frame from one or more of STA1 or STA2, STA3 can set the NAV accordingly. When STA3 receives a new frame before the NAV timer expires, STA3 can update the NAV timer using the duration information included in the new frame. STA3 does not attempt channel access until the NAV timer expires.

[0090] When STA1 receives a CTS frame from STA2, STA1 may send a data frame to STA2 after SIFS, starting from the time point when reception of the CTS frame is completed. When STA2 successfully receives the data frame, STA2 may send an ACK frame to STA1 after SIFS as a response to the data frame. When the NAV timer expires, STA3 may determine whether the channel is being used by carrier sensing. When STA3 determines that the channel is not being used by other terminals during the DIFS period after the NAV timer expires, STA3 may attempt channel access after the contention window (CW) according to the random backoff has passed.

[0091] Figure 6 is a diagram for explaining an example of a frame structure used in a WLAN system to which the present disclosure can be applied.

[0092] With the help of instructions or primitives (meaning a set of instructions or parameters) from the MAC layer, the PHY layer can prepare a MAC PDU (MPDU) to be transmitted. For example, when a command requesting the PHY layer to start transmitting is received from the MAC layer, the PHY layer switches to a transmission mode, and configures information (e.g., data) provided from the MAC layer in the form of a frame and transmits it. In addition, when the PHY layer detects a valid preamble of a received frame, the PHY layer monitors the header of the preamble and transmits a command notifying the start of reception of the PHY layer to the MAC layer.

[0093] In this manner, information transmission / reception in the wireless LAN system is performed in the form of a frame, and for this purpose, a PHY layer protocol data unit (PPDU) format is defined.

[0094] The basic PPDU may include a short training field (STF), a long training field (LTF), a signal (SIG) field, and a data (Data) field. The most basic PPDU format (e.g., Figure 7 The non-HT (high throughput) shown in the figure may consist of only the legacy-STF (L-STF), the legacy-LTF (L-LTF), the legacy-SIG (L-SIG) field and the data field. In addition, depending on the type of PPDU format (e.g., HT mixed format PPDU, HT greenfield format PPDU, VHT (very high throughput) PPDU, etc.), additional (or different types of) RL-SIG, U-SIG, non-legacy SIG field, non-legacy STF, non-legacy LTF (i.e., xx-SIG, xx-STF, xx-LTF (e.g., xx is HT, VHT, HE, EHT, etc.)) and the like may be included between the L-SIG field and the data field.

[0095] STF is a signal used for signal detection, automatic gain control (AGC), diversity selection, precise time synchronization, etc., and LTF is a signal used for channel estimation and frequency error estimation. STF and LTF can be called signals for synchronization and channel estimation of the OFDM physical layer.

[0096] The SIG field may include various information related to the transmission and reception of the PPDU. For example, the L-SIG field consists of 24 bits, and the L-SIG field may include a 4-bit rate field, a 1-bit reserved bit, a 12-bit length field, a 1-bit parity field, and a 6-bit tail field. The RATE field may include information about the modulation and coding rate of the data. For example, the 12-bit length field may include information about the length or 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, for non-HT, HT, VHT, or EHT PPDUs, the value of the length field may be determined as a multiple of 3. For example, for HEPPDUs, the value of the length field may be determined as a multiple of 3+1 or a multiple of 3+2.

[0097] The data field may include a service (SERVICE) field, a physical layer service data unit (PSDU) and a PPDU tail bit, and may also include padding bits if necessary. Some bits of the service field may be used for synchronization of the descrambler at the receiving end. The PSDU corresponds to the MAC PDU defined in the MAC layer and may include data generated / used in the upper layer. The PPDU tail bit may be used to return the encoder to the 0 state. The padding bit may be used to adjust the length of the data field in predetermined units.

[0098] MAC PDU is defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a frame check sequence (FCS). A MAC frame may consist of a MAC PDU and be transmitted / received through a PSDU of a data portion of a PPDU format.

[0099] The MAC header includes a frame control field, a duration / ID field, an address field, etc. The frame control field may include control information required for frame transmission / reception. The duration / ID field may be set to the time for transmitting the corresponding frame, etc. For details of the sequence control, QoS control, and HT control subfields of the MAC header, refer to the IEEE 802.11 standard document.

[0100] The null data PPDU (NDP) format refers to a PPDU format that does not include a data field. In other words, NDP refers to a frame format that includes a PPDU preamble (i.e., L-STF, L-LTF, L-SIG fields and additional non-legacy SIG, non-legacy STF, non-legacy LTF (if present)) of a general PPDU format and does not include the remaining part (i.e., the data field).

[0101] Figure 7 is a diagram illustrating an example of a PPDU defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0102] In standards such as IEEE 802.11a / g / n / ac / ax, various types of PPDUs have been used. The basic PPDU format (IEEE 802.11a / g) includes L-LTF, L-STF, L-SIG, and data fields. The basic PPDU format may also be referred to as a non-HT PPDU format (such as Figure 7 (as shown in (a)).

[0103] Compared to the basic PPDU format, the HT PPDU format (IEEE 802.11n) additionally includes HT-SIG, HT-STF, and HT-LFT fields. Figure 7The HT PPDU format shown in (b) may be referred to as an HT mixed format. In addition, an HT greenfield format PPDU may be defined, and this corresponds to a format consisting of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTFs, and a data field, excluding L-STF, L-LTF, and L-SIG (not shown).

[0104] Compared to the basic PPDU format, an example of the VHT PPDU format (IEEE 802.11ac) additionally includes VHTSIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields (eg, Figure 7 (as shown in (c)).

[0105] Compared to the basic PPDU format, an example of the HE PPDU format (IEEE 802.11ax) additionally includes a repeated L-SIG (RL-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF, a packet extension (PE) field (such as Figure 7 (d) of the HE PPDU format). Some fields may be excluded or their lengths may vary according to the detailed example of the HE PPDU format. For example, the HE-SIG-B field is included in the HE PPDU format for multi-user (MU), and the HE-SIG-B is not included in the HE PPDU format for single user (SU). In addition, the HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may vary to 8μs. The extended range (HE ER) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may vary to 16μs. For example, the RL-SIG may be configured to be the same as the L-SIG. Based on the presence of the RL-SIG, the receiving STA may know that the received PPDU is a HE PPDU or an EHT PPDU, which will be described later.

[0106] The EHT PPDU format may include Figure 7 (e) EHT MU (multi-user) and Figure 7 The EHT TB (trigger-based) PPDU in (f) of FIG. The EHT PPDU format is similar to the HE PPDU format in that it includes the RL-SIG following the L-SIG, but may include the U (Universal)-SIG, the EHT-SIG, the EHT-STF, and the EHT-LTF following the RL-SIG.

[0107] Figure 7The EHT MU PPDU in (e) corresponds to a PPDU carrying one or more data (or PSDU) for one or more users. That is, the EHT MU PPDU can be used for both SU transmission and MU transmission. For example, the EHT MU PPDU can correspond to a PPDU for one receiving STA or multiple receiving STAs.

[0108] Compared with EHT MU PPDU, Figure 7 The EHT TB PPDU in (f) omits the EHT-SIG. A STA that receives a trigger for UL MU transmission (eg, a trigger frame or a triggered response schedule (TRS)) may perform UL transmission based on the EHT TB PPDU format.

[0109] The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal Signal), EHT-SIG fields may be coded and modulated so that even legacy STAs may attempt to demodulate and decode, and may be mapped based on a determined subcarrier frequency interval (e.g., 312.5kHz). These may be referred to as pre-EHT modulation fields. Next, the EHT-STF, EHT-LTF, data, PE fields may be coded and modulated so that they may be demodulated and decoded by a STA that successfully decodes a non-legacy SIG (e.g., U-SIG and / or EHT-SIG) and obtains the information included in the field, and may be mapped based on a determined subcarrier frequency interval (e.g., 78.125kHz). These may be referred to as EHT modulation fields.

[0110] Similarly, in the HE PPDU format, the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, and HE-SIG-B fields may be referred to as pre-HE modulation fields, and the HE-STF, HE-LTF, data, and PE fields may be referred to as HE modulation fields. In addition, in the VHT PPDU format, the L-STF, L-LTF, L-SIG, and VHT-SIG-A fields may be referred to as non-VHT modulation fields, and the VHT STF, VHT-LTF, VHT-SIG-B, and data fields may be referred to as VHT modulation fields.

[0111] Included in Figure 7The U-SIG in the EHT PPDU format may be configured based on, for example, two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., OFDM symbol) used for the U-SIG may have a duration of 4 μs, and the U-SIG may have a total duration of 8 μs. Each symbol of the U-SIG may be used to send 26 bits of information. For example, each symbol of the U-SIG may be sent and received based on 52 data tones and 4 pilot tones.

[0112] The U-SIG may be constructed in units of 20 MHz. For example, if an 80 MHz PPDU is constructed, the U-SIG may be duplicated. That is, the same 4 U-SIGs may be included in the 80 MHz PPDU. A PPDU with a bandwidth exceeding 80 MHz may include a different U-SIG.

[0113] For example, A uncoded bits may be sent via U-SIG, the first symbol of U-SIG (e.g., U-SIG-1 symbol) may send the first X bits of information out of a total of A bits of information, and the second symbol of U-SIG (e.g., U-SIG-2 symbol) may send the remaining Y bits of information out of a total of A bits of information. The A bits of information (e.g., 52 uncoded bits) may include a CRC field (e.g., a 4-bit long field) and a tail field (e.g., a 6-bit long field). For example, the tail field may be used to terminate the trellis structure of the convolutional decoder and may be set to 0.

[0114] The bit information sent through U-SIG can be divided into version-independent bits and version-dependent bits. For example, U-SIG can be included in Figure 7 In a new PPDU format not shown in the EHT PPDU format (e.g., UHR PPDU format), and may be included in the format of the U-SIG field included in the EHT PPDU format and the format of the U-SIG field included in the UHR PPDU format, the version-independent bits may be the same, and some or all of the version-related bits may be different.

[0115] For example, the size of the version-independent bit of the U-SIG may be fixed or variable. The version-independent bit may be assigned only to the U-SIG-1 symbol, or to both the U-SIG-1 symbol and the U-SIG-2 symbol. The version-independent bit and the version-dependent bit may be referred to by various names, such as a first control bit and a second control bit.

[0116] For example, the version-independent bits of the U-SIG may include a 3-bit physical layer version identifier (PHY version identifier), and this information may indicate the PHY version (e.g., EHT, UHR, etc.) of the transmitted / received PPDU. The version-independent bits of the U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field is related to UL communication, and the second value of the UL / DL flag field is related to DL communication. The version-independent bits of the U-SIG may include information about the length of a transmit opportunity (TXOP) and information about a BSS color ID.

[0117] For example, the version-related bits of the U-SIG may include information directly or indirectly indicating the type of the PPDU (eg, SU PPDU, MU PPDU, TB PPDU, etc.).

[0118] Information required for PPDU transmission and reception may be included in the U-SIG. For example, the U-SIG may also include information about bandwidth, information about an MCS technology applied to a non-legacy SIG (e.g., EHT-SIG or UHR-SIG, etc.), information indicating whether a DCM (dual carrier modulation) technology (e.g., a technology for achieving an effect similar to frequency diversity by reusing the same signal on two subcarriers) is applied to the non-legacy SIG, information about the number of symbols used for the non-legacy SIG, and information about whether the non-legacy SIG is generated across the entire frequency band.

[0119] Some of the information required for PPDU transmission and reception may be included in the U-SIG and / or the non-legacy SIG (e.g., EHT-SIG or UHR-SIG, etc.). For example, information about the type of non-legacy LTF / STF (e.g., EHT-LTF / EHT-STF or UHR-LTF / UHR-STF, etc.), information about the length of the non-legacy LTF and the CP (cyclic prefix) length, information about the GI (guard interval) applicable to the non-legacy LTF, information about preamble puncturing applicable to the PPDU, information about resource unit (RU) allocation, etc. may be included only in the U-SIG, only in the non-legacy SIG, or may be indicated by a combination of information included in the U-SIG and information included in the non-legacy SIG.

[0120] Preamble puncturing may indicate the transmission of a PPDU in which there is no signal in one or more frequency units in the bandwidth of the PPDU. For example, the size of the frequency unit (or the resolution of the preamble puncturing) may be defined as 20 MHz, 40 MHz, etc. For example, preamble puncturing may be applied to a PPDU bandwidth of a predetermined size or greater.

[0121] exist Figure 7In the example of , non-legacy SIGs such as HE-SIG-B and EHT-SIG may include control information for receiving STAs. The non-legacy SIG may be transmitted on at least one symbol, and one symbol may have a length of 4 μs. Information about the number of symbols used for the EHT-SIG may be included in a previous SIG (eg, HE-SIG-A, U-SIG, etc.).

[0122] Non-legacy SIGs such as HE-SIG-B and EHT-SIG may include a common field and a user-specific field. The common field and the user-specific field may be encoded separately.

[0123] In some cases, the common field may be omitted. For example, in a compressed mode that does not apply OFDMA (Orthogonal Frequency Division Multiple Access), the common field may be omitted, and multiple STAs may receive the PPDU (e.g., the data field of the PPDU) through the same frequency band. In a non-compressed mode that applies OFDMA, multiple users may receive the PPDU (e.g., the data field of the PPDU) through different frequency bands.

[0124] The number of user-specific fields may be determined based on the number of users. A user block field may include up to two user fields. Each user field may be associated with a MU-MIMO allocation or may be associated with a non-MU-MIMO allocation.

[0125] The common field may include a CRC bit and a tail bit, and the length of the CRC bit may be determined to be 4 bits, and the length of the tail bit may be determined to be 6 bits and set to 000000. The common field may include RU allocation information. The RU allocation information may include information about the positions of RUs to which multiple users (ie, multiple receiving STAs) are assigned.

[0126] RU can include multiple subcarriers (or tones). RU can be used when sending signals to multiple STAs based on OFDMA technology. In addition, RU can be defined even when sending signals to one STA. Resources can be allocated to non-traditional STF, non-traditional LTF and data fields in units of RU.

[0127] The RU of applicable size may be defined according to the PPDU bandwidth. The RU may be defined identically or differently for the applied PPDU format (e.g., HEPPDU, EHT PPDU, UHR PPDU, etc.). For example, in the case of an 80MHz PPDU, the RU layout of the HEPPDU and EHT PPDU may be different. The applicable RU size, the number of RUs and RU positions, the DC (direct current) subcarrier positions and numbers, the empty subcarrier positions and numbers, the guard subcarrier positions and numbers, etc. for each PPDU bandwidth may be referred to as a tone plan. For example, a tone plan for high bandwidth may be defined in the form of multiple iterations of a low bandwidth tone plan.

[0128] RUs of various sizes may be defined as 26-tone RUs, 52-tone RUs, 106-tone RUs, 242-tone RUs, 484-tone RUs, 996-tone RUs, 2×996-tone RUs, 3×996-tone RUs, etc. MRUs (multi-RUs) are different from multiple individual RUs and correspond to a group of subcarriers consisting of multiple RUs. For example, one MRU may be defined as 52+26 tones, 106+26 tones, 484+242 tones, 996+484 tones, 996+484+242 tones, 2×996+484 tones, 3×996 tones, or 3×996+484 tones. In addition, the multiple RUs constituting one MRU may or may not be continuous in the frequency domain.

[0129] The specific size of the RU may be reduced or expanded. Therefore, the specific size of each RU in the present disclosure (i.e., the number of corresponding tones) is not restrictive but illustrative. In addition, in the present disclosure, within a predetermined bandwidth (e.g., 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz ...), the number of RUs may vary according to the RU size.

[0130] Figure 7 The names of each field in the PPDU format are exemplary, and the scope of the present disclosure is not limited by these names. In addition, the examples of the present disclosure can be applied to Figure 7 The PPDU format shown in Figure 7 A new PPDU format that excludes some fields and / or adds some fields.

[0131] Figure 8 An example format of a trigger frame to which the present disclosure may be applied is shown.

[0132] The trigger frame may allocate resources for the transmission of one or more TB PPDUs and request the transmission of a TB PPDU. The trigger frame may also include other information required for the STA to send a TB PPDU in response. The trigger frame may include common information and user information list fields in the frame body.

[0133] The common information (info) field is information that is generally applied to the transmission of one or more TB PPDUs requested by a trigger frame, such as trigger type, UL length, presence or absence of subsequent trigger frames (e.g., more TFs), CS (channel sensing) request, UL BW (bandwidth), HE / EHT P160, special user information field flag, etc.

[0134] The 4-bit Trigger Type subfield may have a value from 0 to 15. Among them, the value 0, value 1, value 2, value 3, value 4, value 5, value 6, and value 7 of the Trigger Type subfield are defined to correspond to Basic, Beamforming Report Poll (BFRP), Multi-User Block Acknowledgement Request (MU-BAR), Multi-User Request to Send (MU-RTS), Buffer Status Report Poll (BSRP), Multicast with Retry (GCR), MU-BAR, Bandwidth Query Report Poll (BQRP), and NDP Feedback Report Poll (NFRP), respectively, and values ​​8 to 15 are defined as reserved.

[0135] Among the common information, the trigger-related common information subfield may include information that is optionally included based on the trigger type.

[0136] A special user information field may be included in the trigger frame. The special user information field does not include user-specific information but includes extended common information that is not provided in the common information field.

[0137] A user information list includes zero or more user information fields. Figure 8 An example of the EHT variant user information field format is shown.

[0138] The AID12 subfield basically indicates that it is a user information field of the STA with the corresponding AID. In addition, if the AID12 field has a specific predetermined value, it can be used for other purposes, such as allocating a random access (RA)-RU or being configured as a special user information field. The special user information field is a user information field that does not include user-specific information but includes extended public information that is not provided in the common information field. For example, the special user information field can be identified by the AID12 value 2007, and the special user information field flag subfield within the common information field can indicate whether the special user information field is included.

[0139] The RU Allocation subfield may indicate the size and location of the RU / MRU. For this purpose, the RU Allocation subfield may be interpreted together with the PS160 (Primary / Secondary 160 MHz) subfield of the User Information field and the UL BW subfield of the Common Information field.

[0140] Multiple Access Point (MAP) Operation

[0141] Hereinafter, examples of the present disclosure for multiple access point (MAP) operations are described.

[0142] MAP operation may be defined as an operation between a master AP (or an AP performing sharing) and a slave AP (or an AP being shared).

[0143] The master AP initiates and controls MAP operations for transmission and reception between multiple APs. The master AP groups slave APs and manages links with the slave APs so that information can be shared between the slave APs. The master AP manages information about the BSS configured by the slave APs and information about the STAs associated with the BSS.

[0144] The slave AP may be associated with the master AP and share control information, management information, and data traffic with each other. The slave AP performs the same basic function of an AP capable of establishing a BSS in a wireless LAN.

[0145] A STA in MAP operation may associate with a slave AP or a master AP to configure a BSS.

[0146] In a MAP environment, a master AP and a slave AP may perform direct transmission and reception with each other. A master AP and a STA may not perform direct transmission and reception with each other. A slave AP (e.g., a slave AP associated with a STA) may perform direct transmission and reception with a STA. One of the slave APs may become a master AP.

[0147] MAP operation is a technology in which one or more APs transmit and receive information with one or more STAs. For example, coordinated-time division multiple access (C-TDMA) that divides allocations between APs along the time axis, coordinated-orthogonal frequency division multiple access (C-OFDMA) that divides allocations between APs along the frequency axis, and coordinated-spatial multiplexing (C-SR) using spatial multiplexing can be applied to MAP operation. Alternatively, coordinated beamforming (C-BF) or joint beamforming technology that collaboratively performs simultaneous transmission and reception can also be applied to MAP operation.

[0148] Fig. 9 It is a diagram for explaining various transmission and reception techniques in a MAP environment to which the present disclosure can be applied.

[0149] As in the conventional method, when the BSS AP transmits to the BSS STA, it can be called STX (Single Transmission). In STX, there is a problem of reducing the performance of transmission and reception of users / STAs located at the edge of the cell due to interference with neighboring APs. Fig. 9 As shown in (a), when AP1 and AP2 transmit to STA1 and STA2 respectively, at the same time in the same frequency bandwidth, a conflict may occur with respect to the wireless medium.

[0150] In MAP technology, performance can be improved by reducing inter-symbol interference (ISI) through cooperation between neighboring APs or by performing joint transmission. Fig. 9 In the C-OFDMA method of (b), interference can be avoided by simultaneously allowing AP1 to transmit to STA1 in the first bandwidth and allowing AP2 to transmit to STA2 in the second bandwidth.

[0151] Fig. 9 The example of (c) illustrates a collaborative beamforming or nulling technique in which interference to AP2 and / or STA2 is nulled when AP1 transmits to STA1 and interference to AP1 and / or STA1 is nulled when AP2 transmits to STA2.

[0152] Fig. 9 (d) shows an AP selection method in which an AP having a good channel condition among neighboring APs performs transmission.

[0153] Can be applied as Fig. 9 As in the example of (e), multiple APs cooperate to simultaneously transmit or receive joint transmission (JTX) or joint reception (JRX), and further, joint MU-MIMO can be supported.

[0154] Coordinated Spatial Multiplexing (C-SR) Technology

[0155] When the SP technology is applied to the basic wireless LAN system, the state of the BSS AP can be sent (by the BSS AP) through a trigger frame or TB PPDU, etc. If the OBSS AP can send data while satisfying Equation 1, the C-SR technology can control the power of the BSS AP / STA and the power of the OBSS AP / STA.

[0156] [Formula 1]

[0157] TxPower PSRT，总 -10×log 10 N PSRT，nonpunc ≤PSR min -RPL PSRR，20MHz

[0158] In Formula 1, PSR is the SR value of the trigger frame and the SIG field of the TB PPDU, and RPL may represent received signal power.

[0159] In order to apply the C-SR technology, the interference situation of the BSS AP / STA and / or OBSS AP / STA must be confirmed.

[0160] The following describes the process of performing C-SR with OBSS AP / STA from the perspective of BSS AP / STA. Here, BSS AP is a sharing AP (Sharing AP) or a shared AP (Shared AP), and OBSS AP can be interpreted as a shared AP that performs C-SR together.

[0161] The C-SR process may include a pre-process, a shared AP candidate selection process, a C-SR establishment process, and a data transmission process.

[0162] The pre-process refers to a process for pre-reporting and collecting information to be exchanged for C-SR operation. The AP / STA can obtain the channel information of the BSS / OBSS AP / STA based on the direction of the frame (e.g., DL direction or UL direction) that is the target of the C-SR operation.

[0163] For example, the BSS STA may obtain channel information from a persistent packet or an NDP sounding frame of the OBSS AP and transmit the obtained channel information to the BSS AP.

[0164] In addition, in order to apply C-SR in RU units, it may be necessary to obtain channel information in RU units rather than in the full band. For example, the BSS STA can obtain channel information in RU units from the NDP detection frame of the OBSS AP and report the obtained channel information in RU units to the BSS AP.

[0165] In case of the shared AP candidate selection process, the shared AP may select shared AP candidates by collecting information about neighboring APs.

[0166] For example, assuming that zeroing is not required based on the distance between APs (e.g., the distance between APs is not too close). In this case, if the RSSI measurement value associated with the AP is within a specific value (e.g., -82dBM), the shared AP can select the shared AP from the APs with busy channel status.

[0167] The C-SR establishment process may include a process for selecting a shared AP to exchange C-SR data (before starting C-SR data transmission) and confirming whether C-SR data can be sent or received using the selected shared AP. The C-SR establishment process may be performed before the SIFS of the C-SR data transmission process.

[0168] Some parts of the C-SR establishment process may be omitted. For example, at least one of a process for checking whether the selected shared AP can send and receive C-SR data or a process for selecting a shared AP with which to exchange C-SR data may be omitted.

[0169] For example, when a trigger frame for C-SR establishment is sent to a shared AP (by a sharing AP), the shared AP that is capable of sending and receiving C-SR data may send a confirmation message to the sharing AP indicating whether C-SR data sending and receiving is possible. Thus, the sharing AP may confirm whether the shared AP is capable of sending and receiving C-SR data.

[0170] The data transmission process may include a process for sending a C-SR trigger frame (or a separate DL frame) for C-SR data transmission and a process for the OBSS / BSS AP to send and receive C-SR data based on the C-SR trigger frame. Figure 8 Configure the C-SR trigger frame according to the trigger frame shown in .

[0171] Here, the C-SR trigger frame (or a separate DL frame) may include basic information for performing a C-SR operation (i.e., C-SR data transmission and reception). For example, the basic information may include information such as the transmit power (Tx power) of the BSS AP (or shared AP), the Tx power limit value to be used by the shared AP, the acceptable interference level of the BSS AP (or shared AP), the TXOP duration, the DL frame length, the DL / UL type of the sharing / shared AP, and the like.

[0172] The shared AP receiving the trigger frame may transmit its own data based on the C-SR technology, or may include C-SR information in a trigger frame for data transmission of OBSS / BSS STA and transmit it.

[0173] Method for obtaining channel information in a pre-process during a C-SR process

[0174] Hereinafter, a method of acquiring channel information in a pre-process during a C-SR process is described. The AP / STA should acquire the channel information of the BSS / OBSS AP / STA based on the direction of the frame to which the C-SR technology is to be applied (i.e., DL direction or UL direction).

[0175] Here, a method in which the BSS AP / STA and the OBSS AP / STA adjust Tx power using a channel value (eg, interference value) of the BSS and a method for implementing C-SR may be implemented in various manners.

[0176] Method 1

[0177] like Fig.10 As illustrated in (a), method 1 relates to a method for obtaining channel information when performing DL transmission of a BSS AP and DL transmission of an OBSS AP (hereinafter, "DL / DL"). In order for the BSS AP to transmit a DL frame using the C-SR technology in the DL / DL situation, interference information of the OBSS AP to the BSS STA is required. Therefore, the BSS STA can measure the channel value of the DL frame of the OBSS AP and report it to the BSS AP.

[0178] For example, the BSS STA may measure the channel value of an ongoing packet (e.g., a beacon frame, etc.) of the OBSS AP. That is, the OBSS AP may send the ongoing packet to the BSS STA, and the BSS STA may obtain the channel value through the received ongoing packet. The operation of obtaining the channel value based on the ongoing packet may be performed by an instruction of the BSS AP or according to the decision of the BSS STA.

[0179] As another example, an NDP sounding process (hereinafter, "OBSS NDP sounding") may be performed between an OBSS AP and a BSS STA under the guidance of the BSS AP (or shared AP). That is, the BSS STA may obtain a channel value based on the NDP transmitted by the OBSS AP.

[0180] When describing the present disclosure, a “channel value” may include at least one of a received signal strength indication (RSSI), an Rx power indicator (RPI), an average noise power indicator (ANPI), an idle power indicator (IPI), an Rx channel power indicator (RCPI), or an Rx signal-to-noise ratio indicator (RSNI).

[0181] In addition, the channel value measured by the BSS / OBSS AP / STA in the present disclosure may include a total channel value for a frequency band indicated (by the BSS / OBSSAP), or a channel value for an indicated / allocated RU.

[0182] Method 2

[0183] like Fig.10As illustrated in (b) of FIG. 1 , method 2 relates to a method for obtaining channel information when performing UL reception of a BSS AP and DL transmission of an OBSS AP (hereinafter, “UL / DL”). In the UL / DL scenario, in order for a BSS STA to transmit an UL frame using a C-SR technique, interference information of an OBSS AP directed to the BSS AP may be required. That is, the BSS AP may measure a channel value of a DL frame from an OBSS AP.

[0184] For example, the BSS AP may measure the channel value of an ongoing packet (eg, beacon frame, etc.) of the OBSS AP. In this case, since the BSS AP directly measures / obtains the channel value, a separate reporting process for the channel value may not be required.

[0185] As another example, the BSS AP may obtain the channel value through the OBSS NDP sounding process. Since the measurement value feedback process of the OBSS NDP for C-SR is not required in the UL / DL case, the NDP sounding process may be completed through OBSS NDP transmission or ACK transmission of the BSS AP for OBSS NDP transmission.

[0186] As another example, when the OBSS sounding process is performed considering a DL / DL situation, the OBSS sounding process may include a process in which the BSS STA transmits feedback after the OBSS AP transmits the NDP.

[0187] Method 3

[0188] like Fig.10 As illustrated in (c), method 3 relates to a method for obtaining channel information when performing DL transmission of a BSS AP and UL reception of an OBSS AP (hereinafter, "DL / UL"). In the DL / UL scenario, the BSS AP may need interference information of the OBSS STA to the BSS STA to send a DL frame using the C-SR technology.

[0189] Therefore, the BSS STA can measure and report the channel values ​​for all OBSS STAs supporting the C-SR process. Here, the BSS STA can use the ongoing packet or OBSS NDP sounding process.

[0190] On the other hand, STAs may not be able to measure and report channel values ​​as smoothly as APs. Since there is no regular ongoing grouping and as many measurements as the number of OBSS STAs are required, the feedback overhead value of BSS STAs may increase in DL / UL situations. Therefore, C-SR technology may not be allowed in DL / UL situations.

[0191] Method 4

[0192] like Fig.10 As illustrated in (d), method 4 relates to a method for obtaining channel information when performing UL reception of a BSS AP and UL reception of an OBSS AP (hereinafter, "UL / UL"). In the UL / UL case, the BSS STA may need interference information of the OBSS AP to the BSS AP to send a UL frame using the C-SR technology.

[0193] In the "DL / DL" case, the BSS STA may report the interference channel measurement value from the OBSS AP to the BSS AP. Therefore, the OBSS AP may receive the channel measurement value from the BSS AP based on the OBSS STA. The OBSS AP may send the interference channel measurement value received from the OBSS STA to the BSS AP. For example, the OBSS AP may send the interference channel measurement value to the BSS AP via a control message over the air or on a backbone network.

[0194] Therefore, the BSS AP may instruct the BSS STA to adjust the Tx power for C-SR through a trigger frame. That is, in the UL / UL scenario, C-SR transmission may require a data sharing process between the BSS AP and the OBSS AP.

[0195] In the following, the above-mentioned OBSS NDP detection process will be described in detail. "OBSS NDP detection process" may mean but is not limited to C-SR NDP detection process. "OBSS NDP detection process" may be replaced by "multi-AP detection process" (i.e., detection process performed by multiple APs).

[0196] The NDP detection process of the basic wireless LAN system may include an operation in which the BSS STA reports a channel value obtained by measuring the NDP transmitted from the BSS AP. However, in the basic wireless LAN system, the OBSS detection process initiated by the BSS AP is not defined. That is, in the basic wireless LAN system, an operation for measuring and reporting interference caused by DL / UL transmission between the BSS and the adjacent OBSS is not defined.

[0197] The OBSS NDP detection process of one embodiment of the present disclosure may include an operation of measuring NDP frames sent by an OBSS AP (or a shared AP) under the guidance of a BSS AP and reporting them to the BSS AP. That is, the present disclosure relates to an operation of obtaining channel interference information for multi-AP operation according to the OBSS NDP detection process.

[0198] Additionally or alternatively, as described in method 2, the OBSS NDP detection process may include the following operations: when the OBSS AP sends an NDP frame under the guidance of the BSS AP (or shared AP), the BSS AP measures the corresponding NDP frame to obtain channel information.

[0199] In describing the present disclosure, it is assumed that the BSS AP is interpreted as a sharing AP and the OBSS AP is interpreted as a shared AP. However, this is not limited to the above, and each of the BSS AP and the OBSS AP may be interpreted as a sharing AP or a shared AP.

[0200] Fig.11 is a diagram for explaining an operation performed by a first STA according to an embodiment of the present disclosure. In the following, the first STA may be a BSS STA, the second STA may be an OBSS STA, the first AP may be an OBSS AP (or a shared AP), and the second AP may be a BSS AP (or a shared AP). That is, the first AP and the second AP may perform a multi-AP operation based on (C-)SR.

[0201] The first STA may receive an NDP announcement frame from the first AP ( S1110 ).

[0202] Here, the NDP announcement frame may be sent from the first AP to the first STA based on the trigger information sent from the second AP. That is, the second AP may instruct the first AP to send the NDP announcement frame and / or the NDP frame.

[0203] For example, the trigger information may include information about a transmission domain (eg, frequency domain) and a transmission method of at least one of the NDP announcement frame or the NDP frame.

[0204] The trigger information may be transmitted from the second AP to the first AP via a trigger frame or a separate control frame. If the trigger information is included in the trigger frame, the trigger frame may include a trigger type subfield indicating an Overlapping Basic Service Set (OBSS) NDP sounding procedure.

[0205] Here, the receiver address (RA) subfield included in the NDP announcement frame may be set to the BSSID (Basic Service Set Identifier) ​​of the second AP. Additionally or alternatively, the AID (Association Identifier) ​​12 subfield included in the STA information (info) field of the NDP announcement frame may be set to a specific AID. Thus, the NDP announcement frame may indicate that the NDP frame is sent from the first AP to the first STA.

[0206] The first STA may receive an NDP frame from the first AP based on the NDP announcement frame ( S1120 ).

[0207] That is, the first STA can receive the NDP frame and measure the corresponding NDP frame through the information included in the NDP announcement frame (for example, the area / method through which the NDP is sent, information about the part of the NDP to be measured, the reporting method, etc.).

[0208] For example, based on the NDP frame sent from the first AP to the first STA, indication information about the transmission area of ​​the feedback frame for the NDP frame can be sent from the second AP to the first STA. Then, an ACK frame for the NDP frame can be sent from the second AP to the first AP.

[0209] The first STA may transmit a feedback frame for the NDP frame to the second AP ( S1130 ).

[0210] For example, based on the indication information of the request feedback frame received from at least one of the first AP or the second AP (i.e., the sounding measurement results / channel information of the NDP frame, etc.), the first STA may send a feedback frame to the second AP based on at least one of the NDP announcement frame or instruction information.

[0211] The first STA may receive coordinated (C)-spatial reuse (SR) based data associated with the feedback frame from the second AP.

[0212] Specifically, the second AP may obtain channel information between the first STA and the first AP through the feedback frame in order to perform C-SR operation. The second AP may use the obtained channel information to generate C-SR-based data (i.e., C-SR-based data associated with the feedback frame). The first STA may receive C-SR-based data from the second AP.

[0213] exist Fig.11 The method performed by the first STA described in the example of Figure 1 The first device (100) performs. For example, Figure 1 One or more processors (102) of the first device (100) may be configured to receive an NDP announcement frame from a first AP via one or more transceivers (106). One or more processors (102) may be configured to receive an NDP frame from the first AP via one or more transceivers (106) based on the NDP announcement frame. One or more processors (102) may be configured to send a feedback frame for the NDP frame to a second AP via one or more transceivers (106).

[0214] In addition, one or more memories (104) of the first device (100) may store instructions for executing the operation when executed by one or more processors (102). Fig.11 Instructions for the methods described in the examples.

[0215] Fig.12 is a diagram for describing an operation performed by a first AP according to one embodiment of the present disclosure.

[0216] The first AP may receive trigger information for transmitting an NDP announcement frame from the second AP ( S1210 ).

[0217] That is, the first AP may receive trigger information for triggering the execution of the OBSS NDP detection process from the second AP. The first AP may identify the region and method for transmitting the NDP announcement frame and / or the NDP through the trigger information.

[0218] The first AP may send an NDP announcement frame to the first STA based on the trigger frame (S1220).

[0219] Here, the NDP announcement frame may include a field indicating that the NDP frame is sent from the first AP. For example, the RA subfield included in the NDP announcement frame may be set to the BSSID of the second AP. Additionally or alternatively, the AID12 subfield included in the STA information field of the NDP announcement frame may be set to a specific AID.

[0220] The first AP may transmit an NDP frame based on the NDP announcement frame to the first STA (S1230). A feedback frame for the NDP frame may be transmitted from the first STA to the second AP.

[0221] Depend on Fig.12 The method performed by the first AP described in the example may be performed by Figure 1 The second device (200) is executed. For example, Figure 1 One or more processors (202) of the second device (200) may be configured to receive a trigger frame for sending an NDP announcement frame from the second AP through one or more transceivers (206). One or more processors (202) may be configured to receive an NDP announcement frame based on the trigger frame through one or more transceivers (206). One or more processors (202) may be configured to send an NDP frame based on the NDP announcement frame to the first STA through one or more transceivers (206).

[0222] In addition, the one or more memories (204) of the second device (200) may store instructions for executing the operation when executed by the one or more processors (202). Fig.12 Instructions for the methods described in the examples.

[0223] Hereinafter, the OBSS NDP detection process performed based on the NDP transmitted by the OBSS AP is described in detail.

[0224] Implementation Method 1

[0225] The BSS AP (or shared AP) may send trigger information for OBSS NDP detection to the OBSS AP (or shared AP).

[0226] For example, the trigger information may include information about at least one OBSS AP that sends an NDP frame (or / and an NDP announcement frame), an area in which the NDP frame (or / and the NDP announcement frame) is sent, and a method of sending an NDP frame (or / and an NDP announcement frame).

[0227] For example, the trigger information may include coding information, such as the BSSID of the OBSS AP that will send the NDP frame (or / and NDP announcement frame), the BW of the NDP frame (or / and NDP announcement frame), RU allocation, MCS, coding type, number of streams, and LTF configuration.

[0228] Additionally or alternatively, when measurement and reporting of NDP is instructed to the BSS STA, the trigger information may include BSS STA information for the instruction and information of the NDP to be measured (eg, AID, BSSID or NDP area to be measured, etc.).

[0229] The trigger information may be sent via a separate control frame. As another example, the trigger information may be sent via a separate control frame. Figure 8 When the trigger information is sent via a trigger frame, the trigger frame may include i) information indicating that the trigger frame is a trigger frame for OBSS NDP sounding, ii) information indicating that the trigger frame is a trigger frame for instructing the AP to send (NDP frame or / and NDP announcement frame), or / and iii) information indicating that the trigger frame is a trigger frame for multi-AP / C-SR operation.

[0230] Here, a new trigger type may be defined to indicate information according to i), ii) or / and iii). That is, the trigger frame may include information indicating a trigger type related to information according to i), ii) or / and iii).

[0231] In addition, the OBSS AP may send NDP announcement information for OBSS NDP detection. For example, the OBSS AP may send NDP announcement information to the BSS AP / BSS STA.

[0232] Here, the NDP announcement information may include information about how to configure the NDP. For example, the NDP announcement information may include information about the OBSS that sends the NDP, the area in which the NDP is sent, the method for sending the NDP, and / or information about which BSS STA measures and reports which part of the NDP. That is, the NDP announcement information may include a reporting method and reporting information based on the NDP frame.

[0233] The NDP announcement information may be sent via new control information. However, this is only an example, and the NDP announcement information may be sent via an NDP announcement frame. When the NDP announcement information is sent via an NDP announcement frame, the NDP announcement frame may include a field indicating that the OBSS AP, rather than the BSS AP, sends the NDP.

[0234] For example, the RA subfield of the NDP announcement frame may be set to the BSSID of the BSS AP. Additionally or alternatively, the AID12 of the STA information (info) field of the NDP announcement frame may be set to a specific AID. Thus, the NDP announcement frame may instruct the OBSS AP to send the NDP instead of the BSS AP.

[0235] Additionally or alternatively, in order to instruct the BSS STA to provide feedback, the OBSS AP may send NDP announcement information including information on how to configure the NDP to the BSS STA. That is, the OBSS AP may request feedback from the BSS STA by directly configuring the STA information field. Alternatively, the BSS AP may request feedback from the BSS STA (i.e., send a frame requesting feedback) when sending a trigger frame or sending ACK information for NDP frame transmission.

[0236] The OBSS AP may send an NDP frame. For example, the OBSS AP may send an NDP frame to a BSS AP / BSS STA that sends an NDP announcement frame. The NDP frame may be based on the above-mentioned NDP frame format (e.g., Figure 7 The frame format in which the data field is removed from the PPDU format shown).

[0237] The BSS AP may send ACK information to the OBSS AP to confirm receipt of the NDP frame sent by the OBSS AP. Additionally or alternatively, the BSS AP may send a trigger frame to the BSS STA to indicate an area for sending feedback information to the BSS STA. At this time, the BSS STA may be a STA that has received the NDP frame. Here, the process for the BSS AP to send ACK information or trigger frame information may be omitted.

[0238] During the process of the BSS AP sending the ACK frame / trigger frame, if the BSS STA receives the indication information (related to feedback / measurement) of the BSS AP and / or the OBSS AP, the BSS STA can measure part or all of the NDP according to the indication information. In other words, the BSS STA can send feedback information based on the NDP to the BSS AP / OBSS AP in the indicated area and in the indicated form.

[0239] Here, the indication information of the BSS AP or / and the OBSS AP may include information included in a trigger frame sent from the BSS AP or / and an NDP announcement frame sent from the OBSS AP. Additionally or alternatively, the indication information of the BSS AP or / and the OBSS AP may include feedback request information sent from the BSS AP or / and the OBSS AP.

[0240] The BSS AP may send ACK information to the BSS STA to confirm reception of the feedback frame. Additionally or alternatively, if there is additional information to be fed back, the BSS AP may send a trigger frame indicating a region for sending feedback information to the BSS STA.

[0241] Here, the trigger frame may be in the form of, but not limited to, a BFRP frame, and may also be in the form of the above-mentioned trigger frame. Therefore, the BSS STA may perform an NDP measurement and / or feedback information transmission process.

[0242] Implementation Method 2

[0243] Fig.13 (a) is a diagram for explaining a process of performing an OBSS detection procedure between a BSS AP and an OBSS AP according to one embodiment of the present disclosure.

[0244] The BSS AP may send trigger information for triggering the OBSS detection process to the OBSS AP. Based on the received trigger information, the OBSS AP may send an NDP announcement frame and an NDP to the BSS AP. The BSS AP may obtain NDP-based channel information based on the NDP announcement frame.

[0245] Here, the BSS AP may send ACK information confirming reception of the NDP frame to the OBSS AP. However, the ACK information transmission operation of the BSS AP may be omitted.

[0246] Fig.13 (b) is a diagram for explaining a process of performing an OBSS detection procedure between a BSS AP / OBSS AP and a BSS STA according to one embodiment of the present disclosure.

[0247] The BSS AP may send trigger information for triggering the OBSS detection process to the OBSS AP. Based on receiving the trigger information, the OBSS AP may send an NDP announcement frame and an NDP to the BSS STAs (eg, BSS STA1 and BSS STA2).

[0248] Here, the BSS AP may send an ACK frame for NDP transmission or / and a trigger frame indicating a region in which the BSS STA sends feedback information to the OBSS AP / BSS STA.

[0249] The BSS STA may measure the NDP based on the NDP announcement frame and / or the trigger frame, and send feedback including the measurement result to the BSS AP / OBSS AP. Therefore, the BSS AP may send an ACK frame for the feedback.

[0250] Since the trigger information, NDP notification frame, and NDP configuration are described in Implementation 1, redundant descriptions are omitted.

[0251] The above-mentioned embodiments are to combine the elements and features of the present disclosure in a predetermined form. Unless otherwise explicitly mentioned, each element or feature should be regarded as optional. Each element or feature can be implemented in a form that is not combined with other elements or features. In addition, the embodiments of the present disclosure may include a combination of some elements and / or features. The order of the operations described in the embodiments of the present disclosure may be changed. Some elements or features of an embodiment may be included in other embodiments, or may be replaced by corresponding elements or features of other embodiments. Obviously, the embodiments may include claims that do not have a clear reference relationship in the combined claims, or may be included as new claims by modification after application.

[0252] It is clear to those skilled in the relevant art that the present disclosure can be implemented in other specific forms within the scope of the essential features of the present disclosure. Therefore, the above detailed description should not be interpreted restrictively in every aspect, but should be considered as illustrative. The scope of the present disclosure should be determined by the reasonable interpretation of the attached claims, and all changes within the equivalent scope of the present disclosure are included in the scope of the present disclosure.

[0253] The scope of the present disclosure includes software or machine executable commands (e.g., operating systems, applications, firmware, programs, etc.) that perform operations in a device or computer according to the methods of various embodiments, and non-transitory computer-readable media that enable software or commands, etc. to be stored and executable in a device or computer. Commands that can be used to program a processing system that performs the features described in the present disclosure can be stored in a storage medium or a computer-readable storage medium, and the features described in the present disclosure can be implemented by using a computer program product that includes such a storage medium. The storage medium may include a high-speed random access memory, such as, for example, DRAM, SRAM, DDR RAM, or other random access solid-state storage devices, but is not limited thereto, and it may include non-volatile memory, such as, for example, one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state storage devices. The memory optionally includes one or more storage devices located away from the processor. The memory, or alternatively, the non-volatile memory device in the memory includes a non-transitory computer-readable storage medium. The features described in this disclosure may be stored in any machine-readable medium to control the hardware of a processing system, and may be integrated into software and / or firmware that allows the processing system to interact with other mechanisms using the results from the embodiments of this disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0254] Industrial Applicability

[0255] The method proposed in the present disclosure is mainly described based on an example applied to a system based on IEEE 802.11, but may be applied to various WLAN or wireless communication systems other than the system based on IEEE 802.11.

Claims

1. A method performed by a first station STA in a wireless LAN system, the method comprising the following steps: receiving a null data physical protocol data unit (PPUD) NDP announcement frame from a first AP; receiving an NDP frame from the first AP based on the NDP announcement frame; as well as sending a feedback frame for the NDP frame to the second AP, Wherein, the NDP announcement frame is sent to the first STA based on the trigger information sent from the second AP.

2. The method according to claim 1, wherein: The trigger information includes information about a transmission area and a transmission method of at least one of the NDP announcement frame or the NDP frame.

3. The method according to claim 1, wherein: The trigger information is sent from the second AP to the first AP via a trigger frame, and The trigger frame includes a trigger type subfield indicating an overlapping basic service set (OBSS) NDP detection process.

4. The method according to claim 1, wherein: The receiver address RA subfield included in the NDP announcement frame is set to the basic service set identifier BSSID of the second AP.

5. The method according to claim 1, wherein: The association identifier AID12 subfield included in the STA information info field of the NDP announcement frame is set to a specific AID, and The AID12 subfield indicates that the NDP frame is sent by the first AP.

6. The method according to claim 1, wherein: Based on sending the NDP frame from the first AP to the first STA, indication information about a transmission area of ​​the feedback frame for the NDP frame is sent from the second AP to the first AP.

7. The method according to claim 6, wherein: Based on receiving information requesting the feedback frame from at least one of the first AP or the second AP, the feedback frame is sent to the second AP based on at least one of the NDP announcement frame or the indication information.

8. The method according to claim 1, wherein: An ACK frame for the NDP frame is sent from the second AP to the first AP.

9. The method according to claim 1, wherein: Coordinated C-space reuse (SR) based data associated with the feedback frame is received from the second AP.

10. The method according to claim 1, wherein: The first STA is a BSS STA, and the second STA is an OBSS STA.

11. A first station STA in a wireless local area network (WLAN) system, the first STA comprising: at least one transceiver; as well as at least one processor connected to the at least one transceiver, Wherein, the at least one processor is configured to: receiving, by the at least one transceiver, a null data physical protocol data unit (PPUD) NDP announcement frame from the first AP; receiving, by the at least one transceiver, an NDP frame from the first AP based on the NDP announcement frame; and sending a feedback frame for the NDP frame to the second AP through the at least one transceiver, Wherein, the NDP announcement frame is sent to the first STA based on the trigger information sent from the second AP.

12. A method performed by a first access point (AP) in a wireless LAN system, the method comprising the following steps: receiving trigger information for sending a null data physical protocol data unit (PPUD) NDP announcement frame from the second AP; Sending the NDP announcement frame to the first STA based on the trigger information; as well as Sending an NDP frame based on the NDP announcement frame to the first STA, Wherein, a feedback frame for the NDP frame is sent from the first STA to the second AP.

13. A first access point (AP) operating in a wireless LAN system, the first AP comprising: at least one transceiver; as well as at least one processor connected to the at least one transceiver, Wherein, the at least one processor is configured to: receiving, by the at least one transceiver, trigger information for sending a null data physical protocol data unit (PPUD) NDP announcement frame from a second AP; Sending the NDP announcement frame to the first STA based on the trigger information by the at least one transceiver; and Sending, by the at least one transceiver, an NDP frame based on the NDP announcement frame to the first STA, Wherein, a feedback frame for the NDP frame is sent from the first STA to the second AP.

14. A processing device, the processing device being configured to control a first station STA in a wireless LAN system, the processing device comprising: at least one processor; as well as At least one computer memory operatively connected to the at least one processor and storing instructions that upon execution by the at least one processor perform operations comprising: receiving a null data physical protocol data unit (PPUD) NDP announcement frame from a first AP; receiving an NDP frame from the first AP based on the NDP announcement frame; and sending a feedback frame for the NDP frame to the second AP, Wherein, the NDP announcement frame is sent to the first STA based on the trigger information sent from the second AP.

15. At least one non-transitory computer-readable medium storing at least one instruction, in, The at least one instruction is executable by at least one processor to control a device in a wireless LAN system to: receiving a null data physical protocol data unit (PPUD) NDP announcement frame from a first AP; receiving an NDP frame from the first AP based on the NDP announcement frame; as well as sending a feedback frame for the NDP frame to the second AP, Wherein, the NDP announcement frame is sent to the first STA based on the trigger information sent from the second AP.

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