Method and apparatus for secondary channel access in a wireless LAN system

Abstract

A method and apparatus for operating in a wireless LAN system are disclosed. A method performed by a first station (STA) in a wireless LAN system according to one embodiment of the present disclosure may include: receiving a first frame from a second STA, which contains information relating to channel access to at least one non-primary channel; performing a first backoff procedure on the first non-primary channel of the at least one non-primary channel based on the first frame; and transmitting a second frame to the second STA or receiving the second frame from the second STA on at least one channel, including the first non-primary channel, based on the first frame and the first backoff procedure.

Description

【Technical Field】 【0001】 The present disclosure relates to a secondary channel access method and apparatus in a Wireless Local Area Network (WLAN) system. 【Background Art】 【0002】 New technologies have been introduced for wireless LAN (WLAN) to improve transmission rate, increase bandwidth, improve reliability, reduce errors, and reduce latency. Among wireless LAN technologies, the IEEE (Institute of Electrical and Electronics Engineers) 802.11 series of standards can be referred to as Wi-Fi. For example, technologies recently introduced into wireless LANs include enhancements for Very High-Throughput (VHT) of the 802.11ac standard, enhancements for High Efficiency (HE) of the IEEE 802.11ax standard, and the like. 【0003】 To provide a more improved wireless communication environment, improvement technologies for Extremely High Throughput (EHT) are being discussed. For example, technologies such as increased bandwidth, efficient utilization of multiple bands, Multiple Input Multiple Output (MIMO) to support increased spatial streams, and technologies for multi-access point (AP) adjustment are being studied. In particular, various technologies for supporting traffic with low latency or real-time characteristics are being studied. In addition, new technologies for supporting ultra-high reliability (UHR), including improvement or expansion of EHT technology, are being discussed. 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 The technical problem addressed by this disclosure is to provide a method and apparatus for performing secondary channel access in a wireless LAN system. 【0005】 The technical problem addressed by this disclosure is to provide a method and apparatus for announcing information related to access to one or more secondary channels other than the primary channel in a wireless LAN system. 【0006】 The technical challenges addressed in this disclosure are not limited to those mentioned above, and other technical challenges not mentioned will be clearly understood by those with ordinary skill in the art to which this disclosure pertains from the following description. [Means for solving the problem] 【0007】 A method performed by a first station (STA) in a wireless LAN system according to one aspect of the present disclosure may include: receiving a first frame from a second STA that includes (composes; constructs; sets up; includes; incorporates; contains; has; comprises) information relating to channel access to at least one non-primary channel; performing a first backoff procedure on the first non-primary channel of the at least one non-primary channel based on the first frame; and transmitting a second frame to the second STA or receiving the second frame from the second STA on at least one channel including the first non-primary channel based on the first frame and the first backoff procedure. 【0008】 An embodiment of the present disclosure, a method performed by a second station (STA) in a wireless LAN system, includes the steps of: transmitting a first frame to the first STA containing information relating to channel access to at least one non-primary channel; and receiving a second frame from the first STA or transmitting the second frame to the first STA on at least one channel containing the first non-primary channel, based on the first frame, wherein the first backoff procedure may be performed while the primary channel is busy. [Effects of the Invention] 【0009】 Various embodiments of this disclosure provide a method and apparatus for performing secondary channel access in a wireless LAN system. 【0010】 Various embodiments of this disclosure provide a method and apparatus for disclosing information related to access to one or more secondary channels other than the primary channel in a wireless LAN system. 【0011】 Various embodiments of this disclosure enable more efficient communication using media and channels in a wireless LAN system. 【0012】 The effects derived from this disclosure are not limited to those mentioned above, and any other effects not mentioned above will be clearly understood by a person with ordinary skill in the art to which this disclosure pertains from the following description. [Brief explanation of the drawing] 【0013】 The accompanying drawings, included as part of the detailed description to aid in understanding this disclosure, provide examples of the disclosure and illustrate the technical features of the disclosure together with the detailed description. [Figure 1]This is a block diagram illustrating an example of a wireless communication device according to one embodiment of the present disclosure. [Figure 2] This figure shows an exemplary structure of a wireless LAN system to which this disclosure can be applied. [Figure 3] This diagram illustrates the link setup process to which this disclosure applies. [Figure 4] This diagram illustrates the backoff process to which this disclosure applies. [Figure 5] This diagram illustrates the CSMA / CA baseframe transmission operation to which this disclosure can be applied. [Figure 6] This figure illustrates an example of a frame structure used in a wireless LAN system to which this disclosure can be applied. [Figure 7] This figure shows an example of a PPDU as defined in the IEEE 802.11 standard to which this disclosure applies. [Figure 8] This diagram illustrates an example of primary channel-based channel access to which this disclosure may apply. [Figure 9] This is a flowchart illustrating a method by which the first STA performs channel access according to one embodiment of the present disclosure. [Figure 10] This is a flowchart illustrating how a second STA performs channel access according to one embodiment of the present disclosure. [Figure 11] This diagram illustrates an example of secondary channel access related to this disclosure. [Figure 12] This diagram illustrates a case in which BSS channels between APs overlap, according to one embodiment of the present disclosure. [Figure 13] This is a diagram illustrating the process by which an AP transmits publicly known information related to SCA, according to one embodiment of the present disclosure. [Figure 14] This figure illustrates an embodiment of the present disclosure in which the bandwidth of the BSS operating channel is 160 MHz. [Figure 15]This is a diagram for explaining the case where the bandwidth of the BSS operation channel is 320 MHz according to an embodiment of the present disclosure. 【Embodiments for Carrying out the Invention】 【0014】 Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description disclosed below together with the accompanying drawings is for explaining exemplary embodiments of the present disclosure, and is not for showing the only embodiments in which the present disclosure can be implemented. The following detailed description includes specific details for providing a complete understanding of the present disclosure. However, it is understood by those skilled in the art that the present disclosure can be implemented without such specific details. 【0015】 In some cases, in order to avoid obscuring the concept of the present disclosure, known structures and devices may be omitted, or they may be shown in the form of a block diagram centered on the core functions of each structure and device. 【0016】 In the present disclosure, when a certain component is "connected", "coupled" or "connected" to another component, this may include not only a direct connection relationship but also an indirect connection relationship in which there are further other components between them. Also, in the present disclosure, the terms "comprising" or "having" identify the presence of the recited features, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or groups thereof. 【0017】 In the present disclosure, terms such as "first", "second", etc. are only used for the purpose of distinguishing one component from another component, and are not used to limit the components. Unless otherwise specifically mentioned, they do not limit the order or importance, etc. between the components. Therefore, within the scope of the present disclosure, the first component in one embodiment can also be referred to as the second component in another embodiment, and similarly, the second component in one embodiment can also be referred to as the first component in another embodiment. 【0018】 The terms used in this disclosure are for illustrative purposes relating to specific embodiments and are not intended to limit the scope of the claims. As used in the description of the embodiments and in the attached claims, singular forms are intended to include plural forms unless otherwise specified in the context. The terms "and / or" used in this disclosure may refer to one of the related enumerated items, or to any and all possible combinations of two or more of them. In this disclosure, a " / " between words has the same meaning as "and / or" unless otherwise specified. 【0019】 The examples in this disclosure may be applied to various wireless communication systems. For example, the examples in this disclosure may be applied to wireless LAN systems. For example, the examples in this disclosure may be applied to IEEE 802.11a / g / n / ac / ax standard-based wireless LANs. Furthermore, the examples in this disclosure may be applied to newly proposed IEEE 802.11bn (or UHR) standard-based wireless LANs. In addition, the examples in this disclosure may be applied to next-generation standard-based wireless LANs following IEEE 802.11bn. Moreover, the examples in this disclosure may be applied to cellular wireless communication systems. For example, they may be applied to cellular wireless communication systems based on 3GPP (3rd Generation Partnership Project: registered trademark: hereinafter the same) standard LTE (Long Term Evolution) series technologies and 5G NR (New Radio) series technologies. 【0020】 The following describes the technical features to which the examples in this disclosure may apply. 【0021】 Figure 1 is a block diagram illustrating an example of a wireless communication device according to one embodiment of the present disclosure. 【0022】 The first device 100 and the second device 200 illustrated in Figure 1 may be replaced with various terms such as terminal, wireless device, WTRU (Wireless Transmit Receive Unit), UE (User Equipment), MS (Mobile Station), UT (user terminal), MSS (Mobile Subscriber Station), MSS (Mobile Subscriber Unit), SS (Subscriber Station), AMS (Advanced Mobile Station), WT (Wireless terminal), or simply user. Furthermore, the first device 100 and the second device 200 may be replaced with various terms such as access point (AP), BS (Base Station), fixed station, Node B, BTS (base transceiver system), network, AI (Artificial Intelligence) system, RSU (roadside unit), repeater, router, relay, gateway, etc. 【0023】 The devices 100 and 200 illustrated in Figure 1 can also be referred to as stations (STA). For example, the devices 100 and 200 illustrated in Figure 1 can be referred to by various terms such as transmitting device, receiving device, transmitting STA, and receiving STA. For example, STA 110 and 200 can play the role of an AP (access point) or a non-AP. That is, in this disclosure, STA 110 and 200 may have AP and / or non-AP functions. When STA 110 and 200 have AP functions, they can simply be called APs, and when STA 110 and 200 have non-AP functions, they can simply be called STAs. In addition, in this disclosure, AP may be represented as AP STA. 【0024】 Referring to Figure 1, the first device 100 and the second device 200 can send and receive wireless signals using various wireless LAN technologies (e.g., the IEEE 802.11 series). The first device 100 and the second device 200 may include interfaces to the medium access control (MAC) layer and the physical layer (PHY) in accordance with the IEEE 802.11 standard. 【0025】 Furthermore, the first device 100 and the second device 200 can also further support various communication standards other than Wi-Fi technology (e.g., 3GPP LTE series, 5G NR series standards, etc.). The devices of this disclosure may also be embodied in various devices such as mobile phones, vehicles, personal computers, Augmented Reality (AR) equipment, and Virtual Reality (VR) equipment. In addition, the STA of this specification can support various communication services such as voice calls, video calls, data communication, autonomous driving, Machine-Type Communication (MTC), Machine-to-Machine (M2M), Device-to-Device (D2D), and Internet of Things (IoT). 【0026】 The first device 100 includes 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 memories 104 and / or the transceivers 106 and be configured to embody the descriptions, functions, procedures, suggestions, methods and / or operation diagrams of this disclosure. For example, the processor 102 may process information in the memory 104 to generate first information / signals and then transmit a radio signal containing the first information / signals via the transceiver 106. Alternatively, the processor 102 may receive a radio signal containing second information / signals via the transceiver 106 and then store information obtained from signal processing of the second information / signals in the memory 104. The memory 104 may be linked to the processor 102 and can store various information relating to the operation of the processor 102. For example, memory 104 may store software code that executes some or all of a process controlled by processor 102, or that contains instructions for executing the descriptions, functions, procedures, suggestions, methods and / or operation sequence diagrams in this disclosure. Here, processor 102 and memory 104 may be part of a communication modem / circuit / chip designed to embody wireless LAN technology (e.g., IEEE 802.11 series). Transceiver 106 may be coupled with processor 102 and can transmit and / or receive radio signals via one or more antennas 108. Transceiver 106 may include a transmitter and / or receiver. Transceiver 106 may be used synonymously with RF (Radio Frequency) unit. In this disclosure, device may also mean communication modem / circuit / chip. 【0027】 The second device 200 includes one or more processors 202, 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 memories 204 and / or the transceivers 206 and be configured to embody the descriptions, functions, procedures, suggestions, methods and / or operation sequence diagrams disclosed herein. For example, the processor 202 may process information in the memory 204 to generate third information / signals and then transmit a radio signal containing the third information / signals via the transceiver 206. Alternatively, the processor 202 may receive a radio signal containing fourth information / signals via the transceiver 206 and then store information obtained from signal processing of the fourth information / signals in the memory 204. The memory 204 may be linked to the processor 202 and can store various information related to the operation of the processor 202. For example, memory 204 may store software code that executes some or all of the processes controlled by processor 202, or that contains instructions for executing the descriptions, functions, procedures, suggestions, methods and / or operation sequence diagrams disclosed in this disclosure. Here, processor 202 and memory 204 may be part of a communication modem / circuit / chip designed to embody wireless LAN technology (e.g., IEEE 802.11 series). Transceiver 206 may be coupled with processor 202 and may transmit and / or receive radio signals via one or more antennas 208. Transceiver 206 may include a transmitter and / or receiver. Transceiver 206 may be used synonymously with RF unit. In this disclosure, device may also mean communication modem / circuit / chip. 【0028】 The hardware elements of devices 100,200 are described in more detail below. However, one or more protocol layers may be embodied by one or more processors 102,202. For example, one or more processors 102,202 can embodied one or more layers (e.g., functional layers such as PHY and MAC). One or more processors 102,202 can generate one or more PDUs (Protocol Data Units) and / or one or more SDUs (Service Data Units) by means of the descriptions, functions, procedures, proposals, methods and / or operation sequence diagrams in this disclosure. One or more processors 102,202 can generate messages, control information, data, or information by means of the descriptions, functions, procedures, proposals, methods and / or operation sequence diagrams in this disclosure. One or more processors 102,202 can generate signals (e.g., baseband signals) containing PDUs, SDUs, messages, control information, data, or information by the functions, procedures, proposals and / or methods of this disclosure and provide them to one or more transceivers 106,206. One or more processors 102,202 can receive signals (e.g., baseband signals) from one or more transceivers 106,206 and obtain PDUs, SDUs, messages, control information, data, or information by the descriptions, functions, procedures, proposals, methods and / or operation sequence diagrams of this disclosure. 【0029】 One or more processors 102,202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. One or more processors 102,202 may be embodied 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, procedures, proposals, methods and / or operation sequence diagrams disclosed in this disclosure may be embodied using firmware or software, and the firmware or software may be embodied to include modules, procedures, functions, etc. Firmware or software configured to perform the descriptions, functions, procedures, suggestions, methods and / or sequence diagrams disclosed in this disclosure may be contained in one or more processors 102,202 or stored in one or more memories 104,204 and driven by one or more processors 102,202. The descriptions, functions, procedures, suggestions, methods and / or sequence diagrams disclosed in this disclosure may be embodied by firmware or software in the form of code, instructions and / or sets of instructions. 【0030】 One or more memories 104,204 may be connected to one or more processors 102,202 and can store various forms of data, signals, messages, information, programs, code, instructions and / or commands. One or more memories 104,204 may consist of ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media and / or combinations thereof. One or more memories 104,204 may be located inside and / or outside of one or more processors 102,202. Furthermore, one or more memories 104,204 may be connected to one or more processors 102,202 by various technologies such as wired or wireless connections. 【0031】 One or more transceivers 106,206 can transmit user data, control information, radio signals / channels, etc., as referred to in the methods and / or operation sequence diagrams of this disclosure, to one or more other devices. One or more transceivers 106,206 can receive user data, control information, radio signals / channels, etc., as referred to in the descriptions, functions, procedures, proposals, methods and / or operation sequence diagrams disclosed in this disclosure, from one or more other devices. For example, one or more transceivers 106,206 may be coupled with one or more processors 102,202 to transmit and receive radio signals. For example, one or more processors 102,202 can control one or more transceivers 106,206 to transmit user data, control information, or radio signals to one or more other devices. Also, one or more processors 102,202 can control one or more transceivers 106,206 to receive user data, control information, or radio signals from one or more other devices. Furthermore, 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 transmit and receive user data, control information, radio signals / channels, etc., as referred to in the descriptions, functions, procedures, proposals, methods and / or operation sequence diagrams disclosed in this disclosure, via one or more antennas 108,208. In this 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 the received user data, control information, radio signals / channels, etc., from RF band signals to baseband signals for processing using one or more processors 102,202. One or more transceivers 106,206 may convert the user data, control information, radio signals / channels, etc., processed by one or more processors 102,202, from baseband signals to RF band signals. To this end, one or more transceivers 106,206 may include (analog) oscillators and / or filters. 【0032】 For example, either STA100 or STA200 can perform the intended operation of an AP, and the other STA100 or STA200 can perform the intended operation of a non-AP STA. For example, the transceivers 106 and 206 in Figure 1 can perform the transmission and reception of signals (e.g., packets or PPDUs (Physical Layer Protocol Data Units) conforming to IEEE 802.11a / b / g / n / ac / ax / be / bn, etc.). Furthermore, in this disclosure, the operation of various STAs generating transmission and reception signals or performing data processing and calculations in advance for transmission and reception signals may be performed by the processors 102 and 202 in Figure 1. For example, an example of an operation that generates transmit / receive signals or performs data processing or calculations in advance for transmit / receive signals may include: 1) an operation to determine / acquire / construct / calculate / decode / encode bit information of fields contained within the PPDU (SIG (signal), STF (short training field), LTF (long training field), Data, etc.); 2) an operation to determine / construct / acquire time resources and frequency resources (e.g., subcarrier resources) used for fields contained within the PPDU (SIG, STF, LTF, Data, etc.); 3) an operation to determine / construct / acquire specific sequences (e.g., pilot sequence, STF / LTF sequence, extra sequence applied to SIG) used for fields contained within the PPDU (SIG, STF, LTF, Data, etc.); 4) power control operations and / or power saving operations applied to the STA; and 5) operations related to determining / acquiring / constructing / calculating / decoding / encoding the ACK signal. Furthermore, in the following example, various pieces of information used by various STAs for determining / acquiring / composing / calculating / decoding / encoding the transmit / receive signals (e.g., information about fields / subfields / control fields / parameters / power, etc.) may be stored in memories 104,204 of Figure 1. 【0033】 In the following, downlink (DL) refers to the link for communication from AP STA to non-AP STA, and downlink PPDU / packets / signals, etc., may be transmitted and received through the downlink. In downlink communication, the transmitter may be part of AP STA, and the receiver may be part of non-AP STA. Uplink (UL) refers to the link for communication from non-AP STA to AP STA, and uplink PPDU / packets / signals, etc., may be transmitted and received through the uplink. In uplink communication, the transmitter may be part of non-AP STA, and the receiver may be part of AP STA. 【0034】 Figure 2 shows an exemplary structure of a wireless LAN system to which this disclosure can be applied. 【0035】 The structure of a wireless LAN system may consist of multiple components. A wireless LAN may be provided that supports transparent STA mobility to higher layers through the interaction of multiple components. A BSS (Basic Service Set) corresponds to the basic structural block of a wireless LAN. Figure 2 illustrates the existence of two BSSs (BSS1 and BSS2), with each BSS containing two STAs as members (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2). In Figure 2, the ellipses representing the BSSs may be understood as representing the coverage area where the STAs included in that BSS maintain communication. This area can be called a BSA (Basic Service Area). When an STA moves outside a BSA, it can no longer communicate directly with other STAs within that BSA. 【0036】 Ignoring the DS shown in Figure 2, the most basic type of BSS in a wireless LAN is the Independent BSS (IBSS). For example, an IBSS can have a minimal form consisting of only two STAs. For instance, assuming other components are omitted, BSS1 consisting only of STA1 and STA2, or BSS2 consisting only of STA3 and STA4, can each be considered a typical example of an IBSS. Such a configuration is possible when STAs can communicate directly without APs. Furthermore, this type of wireless LAN is not pre-planned and configured, but can be configured when the LAN requires it, and can be called an ad-hoc network. Since an IBSS does not include APs, there is no centralized management entity. That is, in an IBSS, STAs are managed in a distributed manner. In an IBSS, all STAs may be mobile STAs, and connection to a distributed system (DS) is not permitted, forming a self-contained network. 【0037】 STA membership in the BSS can change dynamically due to actions such as STAs being added or removed, or STAs entering or leaving the BSS area. To become a member of the BSS, an STA can join the BSS using a synchronization process. To access all services of the BSS-based structure, an STA must be associated with the BSS. Such associations may be configured dynamically and may include the use of Distribution System Services (DSS). 【0038】 In a wireless LAN, the direct distance between STAs may be limited by the PHY performance. While this distance limit may be sufficient in some cases, there may be situations requiring communication between STAs over longer distances. Distributed systems (DS) may be configured to support extended coverage. 【0039】 DS refers to a structure in which BSSs are interconnected. Specifically, as shown in Figure 2, BSSs may exist as components of an extended form of a network composed of multiple BSSs. DS is a logical concept and may be identified by the characteristics of the Distributed System Medium (DSM). In this regard, Wireless Medium (WM) and DSM may be logically distinct. Each logical medium is used for a different purpose and by different components. These mediums are neither limited to being the same nor limited to being different. The flexibility of wireless LAN structures (DS structures or other network structures) can be explained by the fact that multiple mediums are logically distinct from each other in this way. That is, wireless LAN structures can be embodied in various ways, and each wireless LAN structure may be identified independently by the physical characteristics of its respective embodiment. 【0040】 DS can support mobile devices by providing seamless integration of multiple BSSs and offering the necessary logical services for handling destination addresses. DS may also include a portal component that acts as a bridge for connecting wireless LANs with other networks (e.g., IEEE 802.X). 【0041】 An AP (Application Programming Object) is an entity that enables a coupled non-AP STA (Systematization System) to access the DS (Data Storage System) via the WM (Web Module) and also possesses the functionality of an STA. Data can be moved between the BSS (Base System Storage) and the DS via the AP. For example, STA2 and STA3, shown in Figure 2, possess the functionality of an STA while also providing the ability for coupled non-AP STAs (STA1 and STA4) to access the DS. Furthermore, since all APs are essentially STAs, all APs are addressable entities. The address used by the AP for communication on the WM and the address used by the AP for communication on the DSM (Data Storage System) do not necessarily have to be the same. A BSS consisting of an AP and one or more STAs can be called an infrastructure BSS. 【0042】 Data transmitted from one of the STAs connected to an AP to the AP's STA address is always received on an uncontrolled port and may be processed by an IEEE 802.1X port access entity. Alternatively, once a controlled port is authenticated, the transmitted data (or frame) may be forwarded to a DS. 【0043】 An Extended Service Set (ESS) may be added to the aforementioned DS structure to provide even broader coverage. 【0044】 An ESS (Service Set Network) refers to a network of arbitrary size and complexity composed of DSs (Distributed Service Sets) and BSSs (Blockchain Service Sets). An ESS can be a collection of BSSs connected to a single DS. However, an ESS cannot contain a DS. A key feature of an ESS network is that it appears as an IBSS (Internet Link Control Service Set) at the LLC (Logical Link Control) layer. STAs (Stage Attacks) within an ESS can communicate with each other, and mobile STAs can move transparently to the LLC from one BSS to another (within the same ESS). APs (Access Points) within an ESS may have the same SSID (Service Set Identification). An SSID is distinct from a BSSID, which is the identifier for a BSS. 【0045】 In wireless LAN systems, no assumptions are made regarding the relative physical location of BSSs, and any of the following forms are possible: BSSs may partially overlap, which is a commonly used form to provide continuous coverage. BSSs do not have to be physically connected, and logically there is no limit to the distance between BSSs. BSSs may also be located in the same physical location, which may be used to provide redundancy. One (or more) IBSS or ESS networks may physically exist in the same space as one (or more) ESS networks. This may include ESS network configurations when an ad hoc network operates in the 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 at the same location. 【0046】 Figure 3 is a diagram illustrating the link setup process to which this disclosure can be applied. 【0047】 For an STA to set up a link to a network and send and receive data, it must first discover the network, perform authentication, establish an association, and carry out security authentication procedures. The link setup process can be called the session initiation process or session setup process. Alternatively, the discovery, authentication, association, and security setting processes of the link setup process can be collectively referred to as the association process. 【0048】 In step S310, the STA can perform a network discovery operation. The network discovery operation may include the STA's scanning operation. That is, in order for the STA to access a network, it must find a network that it can join. Before joining a wireless network, the STA must identify a compatible network, and the process of identifying networks in a specific area is called scanning. 【0049】 There are two scanning methods: active scanning and passive scanning. Figure 3 illustrates a network discovery operation that includes the active scanning process. In active scanning, the STA performing the scanning sends a probe request frame to search for nearby APs while moving between channels, and waits for a response. The responder sends a probe response frame to the STA that 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 BSS, APs send beacon frames, so APs become the responders, while in IBSS, STAs within IBSS alternately send beacon frames, so the responders are not constant. For example, an STA that sends a probe request frame on channel 1 and receives a probe response frame on channel 1 can save the BSS-related information contained in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning in the same way (i.e., send and receive probe requests / responses on channel 2). 【0050】 Although not shown in Figure 3, scanning may also be performed using a passive scanning method. In passive scanning, the STA performing the scanning waits for beacon frames while switching channels. A beacon frame is one of the management frames defined in IEEE 802.11, and is transmitted periodically to announce the presence of a wireless network, allowing the scanning STA to find and join the wireless network. In BSS, APs are responsible for periodically transmitting beacon frames, while in IBSS, STAs within IBSS transmit beacon frames alternately. When the scanning STA receives a beacon frame, it stores the BSS information contained in the beacon frame and records the beacon frame information on each channel while moving to other channels. An STA that has received a beacon frame can store the BSS-related information contained in the received beacon frame and move to the next channel to perform scanning on the next channel in the same way. Comparing active scanning and passive scanning, active scanning has the advantage of less delay and power consumption compared to passive scanning. 【0051】 After the STA discovers the network, an authentication process may be performed in step S320. This authentication process can be called the first authentication process to clearly distinguish it from the security setup operation in step S340, which will be described later. 【0052】 The authentication process involves the STA sending an authentication request frame to the AP, and the AP responding by sending an authentication response frame to the STA. The authentication frame used in the authentication request / response corresponds to the management frame. 【0053】 The authentication frame may include information such as the authentication algorithm number, authentication transaction sequence number, status code, challenge text, Robust Security Network (RSN), and Finite Cyclic Group. This is just an example of some of the information that may be included in the authentication request / response frame, and may be replaced by other information or may contain additional information. 【0054】 The STA can send an authentication request frame to the AP. Based on the information contained in the received authentication request frame, the AP can decide whether or not to allow authentication to the STA. The AP can provide the STA with the result of the authentication process using an authentication response frame. 【0055】 After the STA has been successfully authenticated, the association process may take place in step S330. The association process includes the STA sending an association request frame to the AP, and the AP sending an association response frame to the STA in response. 【0056】 For example, an association request frame may include information about various capacities, such as the beacon listening interval, SSID (service set identifier), supported rates, supported channels, RSN, mobility domain, supported operating classes, TIM broadcast request (Traffic Indication Map Broadcast request), and interworking service capacity. For example, an association response frame may include information about various capacities, such as the status code, AID (Association ID), supported rates, EDCA (Enhanced Distributed Channel Access) parameter set, RCPI (Received Channel Power Indicator), RSNI (Received Signal to Noise Indicator), mobility domain, timeout interval (e.g., association comeback time), overlapping BSS scan parameters, TIM broadcast response, and QoS (Quality of Service) map. This is an example of some of the information that may be included in a join request / response frame, and may be replaced by other information or may include additional information. 【0057】 After the STA is successfully connected to the network, the security setup process may be performed in step S340. The security setup process in step S340 can also be described as an authentication process using RSNA (Robust Security Network Association) requests / responses, and the authentication process in step S320 can be called the first authentication process, while the security setup process in step S340 can simply be called the authentication process. 【0058】 The security setup process in stage S340 may include, for example, a process of private key setup using a four-way handshake with an EAPOL (Extensible Authentication Protocol over LAN) frame. Furthermore, the security setup process may be performed using a security method not defined in the IEEE 802.11 standard. 【0059】 Figure 4 is a diagram illustrating the backoff process to which this disclosure can be applied. 【0060】 In wireless LAN systems, the basic access mechanism of MAC (Medium Access Control) is the CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism. The CSMA / CA mechanism is also called the Distributed Coordination Function (DCF) of IEEE 802.11 MAC, and basically employs a "listen before talk" access mechanism. With this type of access mechanism, an AP and / or STA can perform a Clear Channel Assessment (CCA) to sense the radio channel or medium within a predetermined time interval (e.g., DIFS Inter-Frame Space) before initiating transmission. If the sensing determines that the medium is idle, the AP and / or STA will begin transmitting a frame through that medium. On the other hand, if the medium is perceived as occupied or busy, the AP and / or STA will not begin transmitting itself, but will wait for a delay period (e.g., a random backoff period) for medium access before attempting to transmit a frame. By applying a random backoff period, multiple STAs are expected to attempt to transmit frames after waiting for different periods of time from each other, thus minimizing collisions. 【0061】 Furthermore, the IEEE 802.11 MAC protocol provides HCF (Hybrid Coordination Function). HCF is based on the aforementioned DCF and PCF (Point Coordination Function). PCF is a polling-based synchronous access method that periodically polls so that all receiving APs and / or STAs can receive data frames. HCF also has EDCA (Enhanced Distributed Channel Access) and HCCA (HCF Controlled Channel Access). EDCA is a competition-based access method for a provider to provide data frames to multiple users, while HCCA uses a non-competition-based channel access method with a polling mechanism. In addition, HCF includes a media access mechanism to improve the QoS (Quality of Service) of wireless LANs and can transmit QoS data during both the Contention Period (CP) and the Contention Free Period (CFP). 【0062】 Refer to Figure 4 to explain the operation based on the random backoff period. When a medium that was occupied / busy changes to an idle state, multiple STAs can attempt to transmit data (or frames). As a way to minimize collisions, each STA can select a random backoff count and wait for the corresponding slot time before attempting to transmit. The random backoff count has a pseudo-random integer value and may be determined to any one of the values ​​in the range of 0 to CW. Here, CW is the Contention Window parameter value. The CW parameter is initially given as CWmin, but can take twice the value in case of transmission failure (for example, if an ACK for a transmitted frame is not received). When the CW parameter value becomes CWmax, the STA can attempt to transmit data while maintaining the CWmax value until successful data transmission occurs, at which point it is reset to the CWmin value. The CW, CWmin, and CWmax values ​​are 2 n It is preferable to set it to -1 (n=0,1,2,...). 【0063】 Once the random backoff process begins, the STA continues to monitor the media while counting down the backoff slots according to the determined backoff count value. When the media is monitored as occupied, the countdown stops and it waits; when the media becomes idle, the remaining countdown resumes. 【0064】 In the example in Figure 4, when a packet to be transmitted reaches the MAC of STA3, STA3 can immediately transmit the frame after confirming that the medium is idle for DIFS only. The remaining STAs monitor the occupied / busy state of the medium and wait. Meanwhile, STA1, STA2, and STA5 may each generate data to transmit, and when each STA monitors the medium as idle, after waiting for DIFS only, they can count down the backoff slot using a random backoff count value they have selected. Assume that STA2 selects the minimum backoff count value and STA1 selects the maximum backoff count value. That is, this example illustrates a case where the remaining backoff time for STA5 is shorter than the remaining backoff time for STA1 when STA2 finishes its backoff count and begins transmitting a frame. STA1 and STA5 pause their countdown and wait for a while while STA2 occupies the medium. When STA2's occupation ends and the medium becomes idle again, STA1 and STA5 wait for DIFS only before resuming the paused backoff count. In other words, frame transmission can begin after counting down the remaining backoff slots equal to the remaining backoff time. Since STA5's remaining backoff time was shorter than STA1's, STA5 begins frame transmission. Data to transmit may also occur in STA4 while STA2 is occupying the medium. From STA4's perspective, when the medium becomes idle, it can wait for DIFS, then count down using a random backoff count value of its choosing, and begin frame transmission. The example in Figure 4 shows a case where STA5's remaining backoff time coincidentally matches STA4's random backoff count value, in which case a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 will receive an ACK, and data transmission will fail. In this case, STA4 and STA5 can double their CW value, select a random backoff count value, and then perform the countdown.STA1 waits while the medium is occupied by transmissions from STA4 and STA5. When the medium becomes idle, STA1 waits only for DIFS, and can begin transmitting frames after the remaining backoff time has elapsed. 【0065】 As illustrated in Figure 4, data frames are used to transmit data forwarded to higher layers and may be transmitted after a backoff that occurs after DIFS has elapsed, from the time the medium becomes idle. Furthermore, management frames are used to exchange management information that is not forwarded to higher layers and are transmitted after a backoff that occurs after an IFS such as DIFS or PIFS (Point Coordination Function IFS) has elapsed. Subtypes of management frames include beacons, association request / response, re-association request / response, probe request / response, and authentication request / response. Control frames are used to control access to the medium. Control frames can be subtypes of frames such as RTS (Request-To-Send), CTS (Clear-To-Send), ACK (Acknowledgment), PS-Poll (Power Save-Poll), Block ACK (BlockAck), Block ACK Request (BlockACKReq), NDP Announcement (null data packet announcement), and Trigger. Control frames are sent after a backoff that occurs after DIFS if they are not a response frame to a previous frame, and without a backoff after SIFS (short IFS) if they are a response frame to a previous frame. The type and subtype of a frame may be identified by the type field and subtype field in the frame control (FC) field. 【0066】 A Quality of Service (QoS) STA can transmit a frame after an arbitration IFS (AIFS) for the access category (AC) to which the frame belongs, i.e., after a backoff that occurs after AIFS[i] (where i is a value determined by the AC). Frames for which AIFS[i] is available can be data frames, management frames, or control frames that are not response frames. 【0067】 Figure 5 is a diagram illustrating the CSMA / CA baseframe transmission operation to which this disclosure can be applied. 【0068】 As mentioned earlier, the CSMA / CA mechanism includes not only physical carrier sensing, where the STA directly senses the medium, but also virtual carrier sensing. Virtual carrier sensing is intended to compensate for problems that can occur in medium access, such as the hidden node problem. For virtual carrier sensing, the STA's MAC can utilize the Network Allocation Vector (NAV). The NAV is a value that indicates to other STAs the time remaining until the medium becomes available, used by an STA that is currently using or authorized to use the medium. Therefore, the value set as the NAV corresponds to the period during which the STA sending the frame is scheduled to use the medium, and STAs receiving the NAV value are prohibited from accessing the medium during that period. For example, the NAV may be set based on the value of the "duration" field in the frame's MAC header. 【0069】 In the example shown in Figure 5, we assume that STA1 is attempting to transmit data to STA2, and STA3 is in a position where it can overhear some or all of the frames transmitted and received between STA1 and STA2. 【0070】 In CSMA / CA baseframe transmission operation, a mechanism utilizing RTS / CTS frames may be applied to reduce the possibility of collisions between transmissions from multiple STAs. In the example in Figure 5, while STA1 is transmitting, carrier sensing by STA3 may determine that the medium is idle. That is, STA1 may be a hidden node for STA3. Alternatively, in the example in Figure 5, while STA2 is transmitting, carrier sensing by STA3 may determine that the medium is idle. That is, STA2 may be a hidden node for STA3. By exchanging RTS / CTS frames before data transmission and reception between STA1 and STA2, it is possible to prevent STAs outside the transmission range of either STA1 or STA2, or STAs outside the carrier sensing range for transmissions from STA1 or STA3, from attempting to occupy the channel during data transmission and reception between STA1 and STA2. 【0071】 Specifically, STA1 can determine whether a channel is in use or not using carrier sensing. In terms of physical carrier sensing, STA1 can determine the channel's occupied or idle state based on the energy magnitude or signal correlation detected from the channel. In terms of virtual carrier sensing, STA1 can determine the channel's occupied state using a network allocation vector (NAV) timer. 【0072】 STA1 can send an RTS frame to STA2 after backoff if the channel is idle during DIFS. STA2, upon receiving an RTS frame, can send a CTS frame, which is a response to the RTS frame, to STA1 after SIFS. 【0073】 If STA3 cannot overhear CTS frames from STA2 but can overhear RTS frames from STA1, STA3 can use the duration information contained in the RTS frames to set the NAV timer for subsequent consecutive frame transmission periods (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame). Alternatively, if STA3 cannot overhear RTS frames from STA1 but can overhear CTS frames from STA2, STA3 can use the duration information contained in the CTS frames to set the NAV timer for subsequent consecutive frame transmission periods (e.g., SIFS + data frame + SIFS + ACK frame). In other words, STA3 can set NAV based on overhearing one or more RTS or CTS frames from at least one of STA1 or STA2. If STA3 receives a new frame before the NAV timer expires, it can update the NAV timer using the duration information contained in the new frame. STA3 will not attempt to access the channel until the NAV timer expires. 【0074】 When STA1 receives a CTS frame from STA2, it can send a data frame to STA2 after SIFS from the time the CTS frame reception is complete. If STA2 successfully receives the data frame, it can send an ACK frame, which is a response to the data frame, to STA1 after SIFS. When the NAV timer expires, STA3 can use carrier sensing to determine whether the channel is in use or not. If STA3 determines that the channel is not being used by another terminal between the expiration of the NAV timer and DIFS, it can attempt to access the channel after the random backoff conflict window (CW) has passed. 【0075】 Figure 6 is a diagram illustrating an example of a frame structure used in a wireless LAN system to which this disclosure can be applied. 【0076】 The PHY layer can prepare the MPDU (MAC PDU) to be transmitted based on instructions or primitives (meaning a set of instructions or parameters) from the MAC layer. For example, when the PHY layer receives an instruction from the MAC layer requesting it to start transmitting, it switches to transmit mode and can assemble the information provided by the MAC layer (e.g., data) into a frame and transmit it. Also, when the PHY layer detects a valid preamble in the frame it is receiving, it monitors the preamble header and sends an instruction to the MAC layer to signal that the PHY layer has started receiving. 【0077】 Thus, information transmission and reception in wireless LAN systems are performed in the form of frames, and for this purpose, the Physical Layer Protocol Data Unit (PPDU) frame format is defined. 【0078】 A basic PPDU may include an STF (Short Training Field), an LTF (Long Training Field), a SIG (SIGNAL) field, and a Data field. The most basic (e.g., non-HT (High Throughput) PPDU format shown in Figure 7) may consist only of an L-STF (Legacy-STF), an L-LTF (Legacy-LTF), an L-SIG (Legacy-SIG) field, and a Data field. 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 other types of) RL-SIG, U-SIG, non-legacy SIG fields, non-legacy STF, non-legacy LTF (i.e., xx-SIG, xx-STF, xx-LTF (e.g., xx is HT, VHT, HE, EHT, etc.)) may be included between the L-SIG field and the Data field. More specific details will be discussed later, referring to Figure 7. 【0079】 STF is a signal used for signal detection, AGC (Automatic Gain Control), diversity selection, and precise time synchronization, while LTF is a signal used for channel estimation and frequency error estimation. In essence, STF and LTF are signals for synchronizing the OFDM physical layer and for channel estimation. 【0080】 The SIG field may contain various information related to PPDU transmission and reception. For example, the L-SIG field consists of 24 bits and 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 contain information about the data modulation and coding rate. For example, the 12-bit Length field may contain information about the length or time duration of the PPDU. For example, the value of the 12-bit Length field may be determined based on the type of PPDU. For example, for non-HT, HT, VHT, or EHT PPDUs, the value of the Length field may be determined to be a multiple of 3. For example, for HE PPDUs, the value of the Length field may be determined to be a multiple of 3 + 1 or a multiple of 3 + 2. 【0081】 The data field may include a SERVICE field, a PSDU (Physical Layer Service Data Unit), and PPDU TAIL bits, and may also include padding bits if necessary. Some bits of the SERVICE field may be used for synchronizing the descramble at the receiving end. The PSDU corresponds to the MAC PDU defined in the MAC layer and may contain data generated / used in higher layers. The PPDU TAIL bits may be used to return the encoder to a 0 state. Padding bits may be used to adjust the length of the data field to a predetermined unit. 【0082】 MAC PDUs are defined by various MAC frame formats, and a basic MAC frame consists of a MAC header, frame body, and FCS (Frame Check Sequence). MAC frames are composed of MAC PDUs and may be transmitted / received by a PSDU, which is the data portion of the PPDU format. 【0083】 The MAC header includes fields such as Frame Control, Duration / ID, and Address. The Frame Control field may contain control information necessary for transmitting / receiving frames. The Duration / ID field may be set to the time required to transmit the frame. The Address subfield can indicate the receiver address, transmitter address, destination address, and source address of the frame, and some Address subfields may be omitted. Sequence Control, QoS Control, and HT Control subfields are also included, and the specific contents of each subfield of the MAC header can be found in the IEEE 802.11 standard document. 【0084】 The null data PPDU (NDP) format refers to a form of PPDU format that does not include data fields. In other words, NDP is a frame format that includes the PPDU preamble (i.e., L-STF, L-LTF, L-SIG fields, and if present, also non-legacy SIG, non-legacy STF, and non-legacy LTF fields) in a general PPDU format, but does not include the rest (i.e., data fields). 【0085】 Figure 7 shows an example of a PPDU as defined in the IEEE 802.11 standard to which this disclosure applies. 【0086】 Standards such as IEEE 802.11a / g / n / ac / ax use various forms of PPDU. The basic PPDU format (IEEE 802.11a / g) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format can also be referred to as the non-HT PPDU format (Figure 7(a)). 【0087】 The HT PPDU format (IEEE 802.11n) further includes the HT-SIG, HT-STF, and HT-LFT(s) fields in addition to the basic PPDU format. The HT PPDU format shown in Figure 7(b) can be referred to as the HT-mixed format. The HT-greenfield format PPDU may be further defined, which does not include L-STF, L-LTF, and L-SIG, and consists of the HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTF, and Data fields (not shown). 【0088】 An example of the VHT PPDU format (IEEE 802.11ac) further includes the VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format (Figure 7(c)). 【0089】 An example of the HE PPDU format (IEEE 802.11ax) further includes the RL-SIG (Repeated L-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and PE (Packet Extension) fields in addition to the basic PPDU format (Figure 7(d)). Depending on the specific example of the HE PPDU format, some fields may be omitted or their lengths may change. For example, the HE-SIG-B field is included in the HE PPDU format for multiple users (MU), but not in the HE PPDU format for single users (SU). Also, the HE trigger-based (TB) PPDU format does not include HE-SIG-B, and the length of the HE-STF field may be changed to 8us. The HE ER (Extended Range) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may be changed to 16us. For example, RL-SIG may be configured identically to L-SIG. Based on the presence of RL-SIG, the receiving STA can determine that the received PPDU is either an HE PPDU or an EHT PPDU, as described later. 【0090】 The EHT PPDU format may include the EHT MU (multi-user) format shown in Figure 7(e) and the EHT TB (trigger-based) PPDU format shown in Figure 7(f). The EHT PPDU format is similar to the HE PPDU format in that it includes an RL-SIG following the L-SIG, but it may also include a U (universal)-SIG, EHT-SIG, EHT-STF, and EHT-LTF following the RL-SIG. 【0091】 The EHT MU PPDU in Figure 7(e) corresponds to a carry PPDU that carries one or more data (or PSDUs) for one or more users. In other words, the EHT MU PPDU may be used for either SU transmission or MU transmission. For example, the EHT MU PPDU may correspond to a PPDU for one receiving STA or multiple receiving STAs. 【0092】 The EHT TB PPDU in Figure 7(f) omits the EHT-SIG compared to the EHT MU PPDU. An STA that receives a trigger for UL MU transmission (e.g., a trigger frame or TRS (triggered response scheduling)) can perform UL transmission based on the EHT TB PPDU format. 【0093】 The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields may be encoded and modulated so that they can be attempted to be demodulated and decoded even by legacy STAs, and may be mapped based on a defined subcarrier frequency interval (e.g., 312.5 kHz). These may be referred to as pre-EHT modulated fields. Next, the EHT-STF, EHT-LTF, Data, and PE fields may be encoded and modulated so that they can be demodulated and decoded by STAs that have successfully decoded non-legacy SIGs (e.g., U-SIG and / or EHT-SIG) and obtained the information contained in those fields, and may be mapped based on a defined subcarrier frequency interval (e.g., 78.125 kHz). These may be referred to as EHT modulated fields. 【0094】 Similarly, in the HE PPDU format, the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, and HE-SIG-B fields can be referred to as pre-HE modulated fields, while the HE-STF, HE-LTF, Data, and PE fields can be referred to as HE modulated fields. Furthermore, in the VHT PPDU format, the L-STF, L-LTF, L-SIG, and VHT-SIG-A fields can be referred to as pre-VHT modulated fields, while the VHT STF, VHT-LTF, VHT-SIG-B, and Data fields can be referred to as VHT modulated fields. 【0095】 The U-SIG included in the EHT PPDU format in Figure 7 may be composed of, for example, two symbols (e.g., two consecutive OFDM symbols). Each symbol for the U-SIG (e.g., an OFDM symbol) may have a duration of 4us, and the U-SIG may have a total duration of 8us. Each symbol of the U-SIG may be used to transmit 26 bits of information. For example, each symbol of the U-SIG may be transmitted and received based on 52 data tones and 4 pilot tones. 【0096】 U-SIGs may be configured in 20MHz units. For example, when an 80MHz PPDU is configured, identical U-SIGs may be duplicated in 20MHz units. That is, an 80MHz PPDU may contain four identical U-SIGs. When the bandwidth exceeds 80MHz, for example, for a 160MHz PPDU, the first 80MHz U-SIG and the second 80MHz U-SIG may be different from each other. 【0097】 In a U-SIG, for example, A uncoded bits may be transmitted, and the first U-SIG symbol (e.g., U-SIG-1 symbol) may transmit the first X bits of the total A bits, while the second U-SIG symbol (e.g., U-SIG-2 symbol) may transmit the remaining Y bits of the total A bits. The A bits (e.g., 52 uncoded bits) may include a CRC field (e.g., a 4-bit field) and a tail field (e.g., a 6-bit field). The tail field may be used to terminate the trellis of the convolution decoder and may be set to 0, for example. 【0098】 The A bit information transmitted by U-SIG can be distinguished into version-independent bits and version-dependent bits. For example, a new PPDU format not shown in Figure 7 (e.g., UHR PPDU format) may include U-SIG, and the format of the U-SIG field in the EHT PPDU format and the format of the U-SIG field in the UHR PPDU format may be the same, while the version-independent bits may differ in some or all respects. 【0099】 For example, the size of the version-independent bits of a U-SIG may be fixed or variable. The version-independent bits may be assigned only to U-SIG-1 symbols, or to both U-SIG-1 and U-SIG-2 symbols. Version-independent and version-dependent bits may be referred to by various names, such as the first control bit and the second control bit. 【0100】 For example, the version-independent bits of the U-SIG may include a 3-bit physical layer version identifier (PHY version identifier), which can indicate the PHY version of the transmitted and received PPDUs (e.g., EHT, UHR, etc.). 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 relates to UL communication, and the second value relates to DL communication. The version-independent bits of the U-SIG may also include information about the length of the TXOP (transmission opportunity) and information about the BSS color ID. 【0101】 For example, the version-dependent bits of the U-SIG may include information that directly or indirectly indicates the type of PPDU (e.g., SU PPDU, MU PPDU, TB PPDU, etc.). 【0102】 The U-SIG may include information necessary for transmitting and receiving PPDUs. For example, the U-SIG may further include information about bandwidth, information about the MCS technique applied to non-legacy SIGs (e.g., EHT-SIG or UHR-SIG), information indicating whether a dual carrier modulation (DCM) technique (e.g., a technique for reusing the same signal on two subcarriers to achieve an effect similar to frequency diversity) 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 bandwidth. 【0103】 Some of the information necessary for sending and receiving PPDUs may be included in the U-SIG and / or non-legacy SIGs (e.g., EHT-SIG or UHR-SIG). For example, information regarding the type of non-legacy LTF / STF (e.g., EHT-LTF / EHT-STF or UHR-LTF / UHR-STF), information regarding the length and cyclic prefix (CP) length of non-legacy LTFs, information regarding the guard interval (GI) applicable to non-legacy LTFs, information regarding preamble puncturing applicable to PPDUs, and information regarding resource unit (RU) allocation may be included only in the U-SIG, only in the non-legacy SIG, or indicated by a combination of information included in the U-SIG and information included in the non-legacy SIG. 【0104】 Preamble puncturing can mean the transmission of a PPDU in which one or more frequency units within the PPDU's bandwidth are not present. For example, the size of the frequency units (or the resolution of preamble puncturing) may be defined as 20 MHz, 40 MHz, etc. For example, preamble puncturing may be applied to PPDU bandwidths of a certain size or larger. 【0105】 In the example shown in Figure 7, non-legacy SIGs such as HE-SIG-B and EHT-SIG may contain control information for the receiving STA. Non-legacy SIGs may be transmitted with at least one symbol, which may have a length of 4us. Information regarding the number of symbols used for the EHT-SIG may be included in a previous SIG (e.g., HE-SIG-A, U-SIG, etc.). 【0106】 Non-legacy SIGs such as HE-SIG-B and EHT-SIG may include common fields and user-specific fields. Common fields and user-specific fields may be coded separately. 【0107】 In some cases, the common field may be omitted. For example, in a compressed mode where non-OFDMA (orthogonal frequency multiple access) is applied, the common field may be omitted, and multiple STAs can receive the PPDU (e.g., the data field of the PPDU) in the same frequency band. In an uncompressed mode where OFDMA is applied, multiple users can receive the PPDU (e.g., the data field of the PPDU) in separate frequency bands. 【0108】 The number of user-specific fields may be determined based on the number of users. A single user block field may contain a maximum of two user fields. Each user field may be associated with either MU-MIMO or non-MU-MIMO assignments. 【0109】 The common field may include a CRC bit and a Tail bit, 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 location of RUs to which multiple users (i.e., multiple receiving STAs) are assigned. 【0110】 A RU may contain multiple subcarriers (or tones). RUs may be used when transmitting signals to multiple STAs based on the OFDMA method. Alternatively, a RU may be defined when transmitting a signal to a single STA. Resources may be allocated on a RU basis for non-legacy STFs, non-legacy LTFs, and Data fields. 【0111】 The applicable size of RUs may be defined by the PPDU bandwidth. RUs may be defined to be identical or different for the applicable PPDU format (e.g., HE PPDU, EHT PPDU, UHR PPDU, etc.). For example, for an 80MHz PPDU, the RU arrangement for HE PPDU and EHT PPDU may differ from each other. The applicable RU size, number of RUs, RU locations, DC (direct current) subcarrier locations and number, null subcarrier locations and number, guard subcarrier locations and number, etc., for each PPDU bandwidth can be called a tone plan. For example, a tone plan for a wide bandwidth may be defined as multiple iterations of a low-bandwidth tone plan. 【0112】 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, 4×996-tone RUs, etc. An MRU (multiple RU) is distinct from multiple individual RUs and corresponds to a group of subcarriers composed 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. Furthermore, the multiple RUs that make up a single MRU may or may not be consecutive in the frequency domain. 【0113】 The specific size of a RU may be reduced or expanded. Therefore, the specific size of each RU (i.e., the number of corresponding tones) in this disclosure is illustrative and not restrictive. Also, in this disclosure, the number of RUs within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, ...) may vary depending on the size of the RU. 【0114】 In the PPDU format shown in Figure 7, the names of the fields are illustrative and do not limit the scope of this disclosure. Furthermore, the examples in this disclosure may apply not only to the PPDU format illustrated in Figure 7, but also to new PPDU formats that are based on the PPDU format in Figure 7 but with some fields excluded and / or some fields added. 【0115】 Primary channel-based channel access 【0116】 Channel access in a wireless LAN system is based on the primary channel. For example, if the primary channel is idle and the backoff counter (BC) has expired, an STA can transmit frames on a channel that includes the primary channel and any idle secondary channels. To this end, all STAs perform a priority Check Cancellation (CCA) on the primary channel. Additionally, APs make information about the primary channel of the BSS public, and the primary channel is always included in the channels on which management frames (e.g., beacon frames, probe response frames, etc.) are transmitted. 【0117】 Figure 8 illustrates an example of primary channel-based channel access to which this disclosure may apply. 【0118】 The example in Figure 8 illustrates primary channel-based channel access in an 80 MHz bandwidth. Referring to Figure 8, a channel in an 80 MHz bandwidth can be described as follows: 【0119】 P20: Primary 20MHz channel 【0120】 S20: Secondary 20MHz channel (If the bandwidth is 40MHz, this corresponds to the remaining 20MHz secondary channel excluding P20) 【0121】 S40: Secondary 40MHz channel (If the bandwidth is 80MHz, this corresponds to the remaining 40MHz secondary channel excluding P20 and S20) 【0122】 Similarly, channels with bandwidths exceeding 80 MHz can be described as follows: 【0123】 S80: Secondary 80MHz channel (If the bandwidth is 160MHz, this corresponds to the remaining 80MHz secondary channel excluding P20, S20, and S40) 【0124】 S160: Secondary 160MHz channel (When the bandwidth is 320MHz, this corresponds to the remaining 160MHz secondary channel excluding P20, S20, S40, and S80) 【0125】 S320: Secondary 320MHz channel (When the bandwidth is 640MHz, this corresponds to the remaining 320MHz secondary channels, excluding P20, S20, S40, S80, and S160) 【0126】 In existing wireless LAN systems, the backoff counter is set for the primary channel. For example, an STA can perform a Control Check (e.g., physical CS and virtual CS) to determine whether the medium on the primary channel is idle or busy. For example, in the example in Figure 8, if a CCA for P20 (e.g., physical CS and / or virtual CS (NAV)) determines that the medium on P20 is busy, the STA does not decrement the backoff counter (BC). If the medium on P20 is determined to be idle, the STA may decrement the BC. Once the BC has expired through this backoff process (i.e., the value of BC becomes 0), the STA can check the medium status on S20 and S40 (e.g., perform a CCA). On the idle channel among S20 and S40, and on the primary channel, the STA can transmit PPDUs (or frames). (In the example in Figure 8, when the BC for P20 expires, S40 is busy and S20 is idle, so a 40MHz PPDU may be transmitted on both P20 and S20.) 【0127】 Secondary channel-based channel access 【0128】 The primary channel-based channel access operation described above can prevent interference and protect PPDU transmission because all frame exchanges between STAs and APs are performed according to the state of the primary channel. On the other hand, if only the primary channel is busy and the secondary channels are idle, channel access cannot be performed only on the secondary channels excluding the primary channel, which is inefficient from a media usage standpoint. For example, in the example in Figure 8, if P20 is busy and both S20 and S40 are idle, a bandwidth portion corresponding to 60 MHz is wasted. 【0129】 To improve wireless LAN systems, a new approach is needed that allows access to the secondary channel based on the secondary channel even when the primary channel is not idle. 【0130】 The following sections describe various examples of secondary channel access provided in this disclosure. 【0131】 In describing this disclosure, SCA (secondary channel access) means that an STA accesses a secondary channel (i.e., a medium on the secondary channel) when the primary channel (i.e., a medium on the primary channel) is busy (for example, by OBSS traffic or other circumstances). Here, an AP or non-AP STA can determine that the primary channel is busy based on physical carrier sensing and / or virtual carrier sensing and / or NAV settings, etc. 【0132】 In this disclosure, for the sake of clarity, the term "secondary channel" is used to refer collectively to one or more channels that are not the primary channel. However, this disclosure is not limited to this, and they may also be referred to as "non-primary channels." Secondary channel access may also be referred to as non-primary channel access (NPCA). 【0133】 Figure 9 is a flowchart illustrating how a first STA performs channel access according to one embodiment of the present disclosure. When describing Figures 9 and 10, the first STA and the second STA may each be embodied by one of a non-AP STA and an AP, respectively. A non-primary channel can refer collectively to channels other than the primary channel (e.g., secondary channels). 【0134】 The first STA can receive a first frame from the second STA that contains information related to channel access to at least one non-primary channel (S910). 【0135】 Specifically, the first STA may receive from the second STA a first frame that makes public information relating to channel access to at least one non-primary channel. Here, the first frame may, but is not limited to, a management frame (e.g., a beacon frame or a probe response frame). 【0136】 As an example of this disclosure, information relating to access to at least one nonprimary channel may include at least one of the following: information indicating whether or not channel access to the nonprimary channel is permitted; the maximum bandwidth on which a second frame (i.e., a frame that can be transmitted by channel access to the nonprimary channel) can be transmitted or received; a clear channel assessment (CCA) threshold for determining whether or not the state of a nonprimary channel (e.g., a first nonprimary channel and / or a second nonprimary channel) is idle; a bitmap indicating the first nonprimary channel on which a first backoff procedure (i.e., a backoff procedure performed on a nonprimary channel) is performed; and information indicating the size of the bitmap; or information relating to unit bandwidth for dividing the total bandwidth of a basic service set (BSS) operating channel into one or more subsets. 【0137】 As an example, each bit constituting the bitmap may be associated with information indicating whether or not each of the unit bandwidth channels (e.g., 20 MHz) is a channel on which the first backoff procedure is performed. That is, a specific bit in the bitmap can indicate whether or not the unit bandwidth channel corresponding to that specific bit is a channel on which the first backoff procedure is performed. 【0138】 Furthermore, the order of each bit in the bitmap may be related to the order of the respective unit bandwidth channels. That is, the order of the unit bandwidth channels corresponding to each bit in the bitmap may be sorted in ascending or descending order. For example, the first bit of the bitmap may correspond to the unit bandwidth channel with the highest frequency or the unit bandwidth channel with the lowest frequency, and the last bit of the bitmap may correspond to the unit bandwidth channel with the lowest frequency or the unit bandwidth channel with the highest frequency. 【0139】 For example, if the first STA receives information from the second STA indicating that channel access to a non-primary channel is not permitted, and the primary state is busy, the first STA does not need to access the idle non-primary channel. Below, we assume that the first STA receives information from the second STA indicating that channel access to a non-primary channel is permitted. 【0140】 The first STA may perform the first backoff procedure on the first nonprimary channel, of which at least one nonprimary channel, based on the first frame (S920). That is, if the primary channel is busy, the first STA may perform a channel access procedure on a nonprimary channel based on the first frame received from the second STA. In this case, the first nonprimary channel on which the first STA performs the first backoff procedure (i.e., the reference nonprimary channel) may be indicated by the first frame. 【0141】 For example, based on the backoff count value becoming 0 due to the first backoff procedure, the first STA can determine whether the state of the second non-primary channel adjacent to the first non-primary channel is idle or not. That is, the first STA can determine whether the state of the second non-primary channel is idle or busy by performing a first type and / or second type CCA. 【0142】 Based on the first frame and the first backoff procedure, the first STA can transmit the second frame / PPDU to the second STA or receive the second frame / PPDU from the second STA on at least one channel, including the first non-primary channel (S930). 【0143】 For example, based on the state of the second non-primary channel being idle, the first STA may transmit a second frame / PPDU to the second STA or receive a second frame / PPDU from the second STA on at least one channel that includes the first non-primary channel and the second non-primary channel. Here, the bandwidth of at least one channel on which the second frame is transmitted or received may be set / determined to be less than or equal to the maximum bandwidth indicated / set by the first frame. 【0144】 Based on the primary channel status being busy, the first STA can either transmit a second frame, indicating the primary channel has been punctured, to the second STA, or receive a second frame from the second STA. The transmission opportunity (TXOP) for transmitting or receiving the second frame may end before the network allocation vector (NAV) set for the primary channel expires. 【0145】 The method illustrated in Figure 9 may be performed by the first device 100 in Figure 1. For example, one or more processors 102 of the first device 100 in Figure 1 can receive a first frame containing channel access information for at least one non-primary channel from the second STA via one or more transceivers 106. Based on the first frame, one or more processors 102 can perform a first backoff procedure on the first non-primary channel among the at least one non-primary channel. Based on the first frame and the first backoff procedure, one or more processors 102 can transmit a second frame to the second STA via one or more transceivers 106 on at least one channel including the first non-primary channel, or receive a second frame from the second STA via one or more transceivers 106. 【0146】 Furthermore, one or more memories 104 of the first device 100 can store instructions for performing the method described in the example in Figure 9 or in the examples described later, when executed by one or more processors 102. 【0147】 Figure 10 is a flowchart illustrating a method by which a second STA performs channel access according to one embodiment of the present disclosure. 【0148】 The second STA can receive a first frame from the first STA containing information related to channel access to at least one non-primary channel (S1010). That is, when the primary channel is busy, the second STA can send a first frame to the first STA containing information related to the access procedure to the non-primary channel. Information related to channel access to at least one non-primary channel is explained with reference to Figure 9, and redundant explanations are omitted here. 【0149】 Based on the first frame, the first backoff procedure is performed on the first nonprimary channel, which is one of at least one nonprimary channels. Based on this, the second STA can receive the second frame from the first STA or transmit the second frame to the first STA on at least one channel that includes the first nonprimary channel (S1020). Here, the first backoff procedure may be performed while the primary channel is busy. 【0150】 The method illustrated in Figure 10 may be performed by the second device 200 in Figure 1. For example, one or more processors 202 of the second device 200 in Figure 1 can transmit a first frame containing channel access information for at least one non-primary channel to the first STA via one or more transceivers 206. Based on the first frame, a first backoff procedure is performed on the first non-primary channel among at least one non-primary channel, and based on this, one or more processors 202 can receive a second frame to the first STA via one or more transceivers 206 on at least one channel containing the first non-primary channel, or transmit a second frame to the first STA via one or more transceivers 206. 【0151】 Furthermore, one or more memories 204 of the second device 200 can store instructions for performing the method described in the example in Figure 10 or the examples described later, when executed by one or more processors 202. 【0152】 The examples in Figures 9 and 10 may correspond to some of the various examples in this disclosure. The various examples in this disclosure, including those in Figures 9 and 10, will be described in more detail below. 【0153】 Example 1 【0154】 This embodiment relates to the STA's capacity for secondary channel access. 【0155】 Unlike existing primary channel-based channel access, which is primarily supported by STAs, secondary channel access (SCA) may be provided by STAs that have the capability for SCA (e.g., AP STAs and / or non-AP STAs). For example, AP STAs and non-AP STAs can communicate with each other whether they support SCA capability and / or whether SCA capability is enabled. 【0156】 Capability for SCA may be defined by whether a first-type CCA can be performed on the secondary channel based on whether or not a wireless LAN frame is decoded / identified on the secondary channel (i.e., whether a preamble defined in the wireless LAN system is detected (PD) from the received PPDU frame). For a first-type CCA on a secondary channel, a set / reset of the NAV (i.e., a NAV update based on the duration information of the detected preamble) may be applied to the secondary channel based on the duration information of the preamble detected by the first-type CCA on the secondary channel, similar to how a PD-based CCA performed on the existing primary channel applies a set / reset of the NAV (i.e., a NAV update based on the duration information of the detected preamble). 【0157】 Furthermore, the capability for SCA may be defined by whether a second type CCA based on guard interval detection (GID) or energy detection (ED) can be performed on the secondary channel. GID may include determining whether a guard interval symbol as defined in the wireless LAN system is detected, and ED may include determining whether a signal of a certain intensity or greater is detected, without considering whether it is a signal / packet as defined in the wireless LAN system. In addition, different or independent detection thresholds (e.g., thresholds for received signal intensity) may be defined for the first type CCA and the second type CCA. 【0158】 Based on these various types of CCAs, different levels of SCA capacity may be defined. 【0159】 SCA capacity level 0 may correspond to a capacity where no backoff is performed on the secondary channel. In other words, like existing primary channel-based channel access, a second type of CCA (e.g., GID-based CCA and / or ED-based CCA) may be performed on the secondary channel. 【0160】 SCA capacity level 1 may correspond to the capacity to perform backoff on one secondary channel simultaneously. When there is one or more secondary channels within the operating channel, a first-type CCA (e.g., PD-based CCA) may be performed on one secondary channel at a given time, and support for first-type CCA / backoff on multiple secondary channels at a given time is not required. 【0161】 SCA capacity level 2 may correspond to the capacity to perform backoff on multiple secondary channels simultaneously. If there is one or more secondary channels within the operating channel, a first-type CCA (e.g., PD-based CCA) may be performed on one or more of those secondary channels. 【0162】 Such SCA capacity may be included in capacity information elements for a specific version / generation of wireless LAN system (e.g., UHR capability IE). For example, an AP may transmit a capacity IE in beacon frames, probe response frames, coupling request frames, reconnection request frames, etc., that includes information indicating whether or not it supports SCA capacity. For example, an STA may transmit a capacity IE in probe request frames, coupling request frames, reconnection request frames, etc., that includes information indicating whether or not it supports SCA capacity. 【0163】 Example 2 【0164】 This embodiment relates to the operation process of secondary channel access. 【0165】 For STA, basic NAV and intra-BSS NAV may be configured. Basic NAV may be updated based on PPDUs identified as inter-BSS, or based on PPDUs that are neither identified as inter-BSS nor intra-BSS. Intra-BSS NAV may be updated based on PPDUs identified as intra-BSS. 【0166】 Specifically, when the NAV for the primary channel is running (i.e., the NAV is set / reset and has not yet expired), the STA operation can be assumed as follows: 【0167】 For example, when an AP exchanges frames with a first STA coupled to a BSS within a TXOP it has obtained, the BSS-internal NAV for the primary channel may be set / reset for the second STA within the BSS. Furthermore, it can be assumed that the second STA, whose BSS-internal NAV for the primary channel is active, accesses the secondary channel (for example, on a secondary channel confirmed to be idle) and sends a frame to the AP. In this case, while the AP is transmitting within the TXOP (for example, sending downlink data on the primary channel, sending ACKs for uplink data, etc.), the AP may not receive frames sent by the second STA on the secondary channel. 【0168】 Considering this, STA can expect to successfully perform frame exchange over SCA if the base NAV is set / reset on the primary channel by a PPDU associated with another BSS (e.g., OBSS) rather than its own BSS (i.e., an inter-BSS PPDU), or by a PPDU that is not classified / identified as being from its own BSS or another BSS, and SCA is performed while the base NAV for the primary channel is operating. In other words, STA can perform SCA if the base NAV for the primary channel is set (or operating). 【0169】 Example 2-1 【0170】 This embodiment relates to frame transmission on a secondary channel. 【0171】 Figure 11 is a diagram illustrating an example of secondary channel access related to this disclosure. 【0172】 In the case of existing primary channel-based channel access as explained with reference to Figure 8, when backoff occurs on P20 and the backoff counter expires (i.e., the BC value becomes 0), the idle / busy status of one or more secondary channels allows frames to be transmitted on P20 and one or more idle secondary channels. 【0173】 First, if P20 is busy, STA can perform the backoff process on one or more secondary channels that can perform backoff (referred to as the "first one or more secondary channels"). 【0174】 In contrast, if we assume that a randomly selected backoff counter-based backoff process is not performed on the secondary channel, then if multiple adjacent STAs with similar operating channels directly transmit frames on an idle channel based on the CCA result in a short time interval (e.g., one slot) on the channel containing (or overlapping) the secondary channel (without performing the backoff process), a situation may arise where multiple STAs transmit frames simultaneously, and such collision possibilities may actually waste the channel. Therefore, to improve channel utilization, a backoff process may be performed on the secondary channel. 【0175】 Furthermore, if the remaining length of the NAV timer for the primary channel is less than a predetermined threshold, the STA does not need to access the secondary channel (or perform backoff on the secondary channel). In other words, secondary channel access (or backoff on the secondary channel) may be performed only if the remaining length of the NAV timer for the primary channel is greater than or equal to a predetermined threshold. 【0176】 For example, such a predetermined threshold may be associated with the TXOP length on the secondary channel. For instance, if the remaining NAV timer for the primary channel is not long enough to obtain a TXOP on the secondary channel, the STA may not perform a backoff on the secondary channel. 【0177】 Next, when the backoff counter on one or more of the first secondary channels expires (i.e., the BC value becomes 0), the STA may perform a second-type CCA on one or more additional secondary channels in addition to the first one or more secondary channels on which the backoff process was performed. For example, the STA can determine whether the results of the second-type CCA on other secondary channels (i.e., additional secondary channels) are idle or busy during a predetermined length of time (e.g., PIFS) prior to the point when the backoff counter on the first secondary channel on which the backoff was performed became 0. 【0178】 This allows the STA to transmit PPDU / frames on one or more secondary channels that correspond to the first one or more secondary channels where backoff has been performed and the backoff counter has expired, and additional secondary channels that have been determined to be idle by the second type CCA. If all secondary channels other than the first one or more secondary channels where backoff has been performed (i.e., secondary channels where the second type CCA is performed) are busy, the second one or more secondary channels do not need to include any secondary channels other than the secondary channels whose backoff counters have expired. 【0179】 For example, in the example in Figure 11, S20 is a secondary channel where a backoff process based on the first type CCA is performed, while no backoff is performed on S40, and a second type CCA may be performed. If the backoff counter on S20 has expired, and as a result of the second type CCA in the preceding predetermined time interval, both 20MHz channels of S40 are idle, then a PPDU corresponding to the remaining 60MHz of the 80MHz bandwidth of S20 and S40, excluding P20, may be transmitted (i.e., the second one or more secondary channels include S20 and S40). In this case, the PPDU transmitted on the second one or more secondary channels may be an 80MHz bandwidth PPDU containing information indicating that P20 is punctured, and such a punctured PPDU may include a MAC frame transmitted by the STA that accessed the secondary channel. 【0180】 If the backoff counter for S20 expires and S40 is busy as a result of a second type CCA in a predetermined time interval prior thereto, a PPDU corresponding to 20 MHz of S20 may be transmitted (i.e., one or more second secondary channels include S20). In this case, the PPDU transmitted on one or more second secondary channels may be an 80 MHz bandwidth PPDU containing information indicating that P20 and S40 are punctured, and such punctured PPDU may include a MAC frame transmitted by the STA that accessed the secondary channel. 【0181】 Furthermore, PPDU / frames transmitted by the STA on one or more second secondary channels may be sent to the AP or to other STAs. 【0182】 In the example shown in Figure 11, the STA can set / reset the basic NAV based on frames received during the backoff process on the primary channel. While the basic NAV is operating on the primary channel, the STA can perform the backoff process on S20. The backoff on S20 may be performed by a PD-based CCA, and there may be a time delay due to switching operations between the termination of the PD-based CCA or backoff on the primary channel and the start of the PD-based CCA or backoff on the secondary channel. The CCA on S20 is not limited to a PD-based CCA (i.e., first-type CCA), but may also be a GID-based or ED-based CCA (i.e., second-type CCA). 【0183】 Example 2-2 【0184】 This embodiment relates to TXOP on a secondary channel. 【0185】 Once the basic NAV for the primary channel expires, a CCA must be performed on P20. Therefore, the termination of the TXOP on the secondary channel may occur before the basic NAV for the primary channel expires. Consequently, the TXOP for the secondary channel may be acquired / configured to terminate before the basic NAV for the primary channel expires. 【0186】 If an STA acquires / configures a TXOP for a secondary channel to terminate after the basic NAV for the primary channel expires, other STAs that do not support secondary channel access (e.g., legacy STAs) may be able to transmit frames on the channel containing the primary channel (i.e., primary and secondary channels) after the basic NAV for the primary channel expires, and STAs that access the secondary channel may not be able to receive frames transmitted by other STAs on the channel containing the primary channel. Also, if the TBTT (target beacon transmission time) is set to the time during basic NAV operation, the AP must prepare to transmit a beacon on the channel containing the primary channel immediately after the basic NAV expires, but the TXOP on the secondary channel may prevent the beacon from being transmitted in a timely manner, and other STAs may not be able to receive the beacon transmitted by the AP at the expected time and may have to wait for the beacon for a longer period of time. Therefore, by configuring the TXOP for the secondary channel to terminate before the basic NAV expires, frame exchange can be ensured to proceed normally on the channel containing the primary channel. 【0187】 Furthermore, if there is not enough time to set up / acquire a TXOP on the secondary channel, the STA does not have to transmit a frame on the secondary channel or perform a backoff on the secondary channel (for example, if the expiration of the basic NAV for the primary channel is below a predetermined threshold (related to the TXOP length)). For example, if the length of the time interval between the expiration of the backoff counter for the secondary channel and the end of the basic NAV for the primary channel is insufficient for frame exchange (or insufficient to set up / acquire a TXOP), the STA does not have to transmit a frame on the secondary channel. 【0188】 Referring to the example in Figure 11, an STA that attempts to acquire a TXOP as the backoff counter expires through the backoff process on S20 can set / acquire a TXOP of a length shorter than the remaining time of the basic NAV for the primary channel (i.e., so that the TXOP ends before the end of the basic NAV). 【0189】 Example 3 【0190】 This embodiment relates to the transmission or reception operation of an STA performing secondary channel access. 【0191】 An STA performing secondary channel access can transmit frames / PPDUs on the secondary channel for the duration that NAV is operating on the primary channel. For example, based on the backoff process performed on one or more first secondary channels and the CCA results on one or more additional secondary channels where backoff does not occur, the STA can transmit frames / PPDUs on one or more second secondary channels that are idle, excluding / puncturing some channels (e.g., the primary channel and any busy secondary channels). 【0192】 As an addition or alternative, a TXOP for a secondary channel, initiated by the transmission of a frame / PPDU on the secondary channel, may be configured to terminate before the NAV on the primary channel terminates. The TXOP length may be set / indicated by the duration information of the frame transmitted or received by the STA accessing the secondary channel (e.g., the value of the duration / ID field). For example, the value of the duration / ID field may be set to include the time required to exchange the frame / PPDU with a subsequent frame / PPDU (e.g., the length of the frame / PPDU and the interval between frames (IFS)). 【0193】 As an addition or alternative, the EDCA parameter set for each (first) secondary channel on which backoff occurs at the transmitting STA may be set as the EDCA parameter set for the primary channel, the MU EDCA parameter set, or a new EDCA parameter set. Such EDCA parameter sets may be applied identically to all (first) secondary channels, or they may be applied differently to one another. 【0194】 In this disclosure, an STA receiving frames transmitted via secondary channel access can perform frame detection on the secondary channel for the duration that the NAV is operating on the primary channel. For example, the STA may have frames to transmit and perform backoff on the secondary channel, receive frames during backoff on the secondary channel, or even if there are no frames to transmit, attempt to receive frames addressed to it on the secondary channel. The STA can also set / reset the NAV for the secondary channel based on the duration information of frames detected on the secondary channel. 【0195】 As an addition or alternative, the EDCA parameter set for each (first) secondary channel on which backoff occurs at the receiving STA may be set as the EDCA parameter set for the primary channel, the MU EDCA parameter set, or a new EDCA parameter set. Such EDCA parameter sets may be applied identically to all (first) secondary channels, or they may be applied differently to each other. 【0196】 Example 4 【0197】 Example 4 relates to a procedure for an AP to make information related to secondary channel access public, and to information related to secondary access. 【0198】 When an AP's (or AP MLD's) BSS operating channel overlaps with a neighboring AP's (i.e., adjacent AP's) BSS (i.e., OBSS) operating channel, the SCA within the AP's BSS and the SCA within the neighboring AP's BSS may mutually affect each other. For example, if an AP successfully performs an SCA within its BSS, using all secondary channels to send and receive PPDU / frames, and the secondary channel from which the AP sends PPDU / frames overlaps with the primary channel of another AP, the other AP's channel access opportunities may be reduced. 【0199】 For example, let's assume that STA in Figure 11 is AP1 in Figure 12. Since S20 of AP1 in Figure 12 corresponds to P20 of AP2 (i.e., S20 of AP1 and P20 of AP2 overlap with each other), if AP1 transmits PPDU / frames using all secondary channels, AP2 may not be able to use P20 and S20. In other words, if AP1 performs SCA, AP2 may not have the opportunity to perform PCH-based channel access, which can be a problem. 【0200】 Furthermore, while an AP has capacity for SCA access, if other APs do not have capacity for SCA access, there is a problem in that the longer an AP with SCA capacity occupies a channel, the fewer opportunities other APs may have to access the channel. 【0201】 Therefore, the AP can make information related to SCA operation available to the STA so that the STA can use SCH while taking into account the surrounding circumstances (e.g., whether other STAs have the capability to operate SCA, the operating channel of the BSS to which the STA is connected, channel status information related to the STA, OBSS-related information, etc.). 【0202】 Example 4-1 【0203】 Example 4-1 relates to information related to SCA operation that the AP transmits to the STA. 【0204】 The AP can transmit various types of information related to SCA operations to the STA using management frames (e.g., beacon frames, probe response frames, etc.). For example, a management frame may include a UHR operation IE or an IE related to SCA operations, and the UHR operation IE or SCA operation IE may include various types of information related to SCA operations. The STA can perform SCA-related operations in response to the various types of information related to SCA operations received from the AP. 【0205】 As an example of this disclosure, information relating to SCA operation may include information on whether SCA is permitted, the maximum bandwidth on the SCH that can transmit frames / PPDUs when SCA is performed, information on one or more secondary channels that serve as the basis for SCA (i.e., channels that perform backoff), and / or CCA threshold information related to the secondary channels. 【0206】 Specifically, information regarding whether or not SCA is allowed may be indicated in a field related to whether or not SCA is allowed (for example, an SCA-allowed field), but the name of the field may be changed. As an example, let's assume that the SCA-allowed field consists of 1 bit. In this case, if the SCA-allowed field value is 1 (or 0), this means that SCA is allowed, and if the SCA-allowed field value is 0 (or 1), this means that SCA is not allowed. 【0207】 Additionally or alternatively, one of the following bandwidths may be specified as the maximum bandwidth on the SCH that can transmit frames / PPDUs when an SCA is performed: 20, 40, 80, 160, 320, or 640 MHz. The maximum bandwidth on the SCH that an STA can transmit frames / PPDUs may not be greater than the operating bandwidth (or bandwidth of the BSS operating channel) of the BSS to which the STA is coupled. The operating bandwidth (or bandwidth of the BSS operating channel) can refer collectively to the bandwidth operated by the BSS. As described above, an AP may transmit information regarding the maximum bandwidth on the SCH that can transmit frames / PPDUs to the STA using a management frame (e.g., a beacon frame and / or probe response frame). Information regarding the maximum bandwidth on the SCH that can transmit frames / PPDUs may be specified in the SCA bandwidth field, although the name of this field may be changed. 【0208】 As an example, suppose the BSS operating bandwidth is 160 MHz and one or more SCHs of S80 are idle. In this case, if the AP's known maximum bandwidth (i.e., the maximum bandwidth on which frames / PPDUs can be transmitted on an SCH) is 80 MHz, then S80 may transmit and receive frames in 80 MHz PPDU format via the STA on the excluded channels. 【0209】 As an addition or alternative, information regarding one or more secondary channels that serve as the basis for the SCA (i.e., channels on which backoff occurs) can indicate which channels will perform backoff based on the BSS operating bandwidth or the maximum bandwidth on which the frame / PPDU can be transmitted. As an example, information regarding one or more secondary channels that serve as the basis for the SCA may consist of a bitmap. 【0210】 As an example, as shown in Figure 11, if the total bandwidth (e.g., the bandwidth of the BSS operating channel) is 80 MHz and backoff is performed based on the first secondary channel, then one or more secondary channels that serve as the reference for the SCA may be represented by a 3-bit bitmap. Each bit in the 3-bit bitmap may correspond to each 20 MHz secondary channel. For example, the bitmap may be configured as "100" (i.e., the bitmap is configured to indicate that backoff is performed on the first 20 MHz secondary channel). However, this is only one embodiment, and the bitmap may include bits corresponding to the PCH. In this case, the information indicating one or more secondary channels that serve as the reference for the SCA may be represented by a 4-bit bitmap. 【0211】 As described above, the first bit of the bitmap may correspond to the highest frequency 20MHz channel, and the last bit of the bitmap may correspond to the lowest frequency 20MHz channel. However, this is only one embodiment, and the first bit of the bitmap may correspond to the lowest frequency 20MHz channel, and the last bit of the bitmap may correspond to the highest frequency 20MHz channel. Furthermore, the reference bandwidth of the bitmap is not limited to 20MHz, but may be 40, 80, or 160MHz, etc. 【0212】 As an addition or alternative, CCA threshold information related to secondary channels may include information about thresholds that serve as criteria for determining the channel state by CCA in one or more SCHs where SCA is performed (e.g., criteria for determining whether the channel state is idle or busy). The lower the threshold used to determine the channel state by CCA (i.e., the threshold compared to the channel measurement), the more likely it is that the channel state will be determined to be busy even if the channel measurement (e.g., RSSI (received signal strength indicator)) is low. In this case, the CCA may include first-type CCA and / or second-type CCA. 【0213】 As an example, the threshold used to determine the channel state may be determined / set to a fixed / predefined value (e.g., -82 dBM or -72 dBM). Additionally or alternatively, the threshold used to determine the channel state may be determined / set to a value obtained by adding / subtracting a value (e.g., 4 dBM, 8 dBM) to / from the fixed / predefined value. In this case, the AP can send only the value to / from the threshold to the STA. 【0214】 As an example of this disclosure, Figure 13 illustrates the procedure for performing an SCA based on SCA-related information made public by the AP. As shown in Figure 13, the AP can make public to the STA information regarding the BSS operating bandwidth set to 160 MHz, information indicating that an SCA is permitted, information regarding the maximum bandwidth of the PPDU that can be transmitted by the SCA set to 40 MHz, and information regarding the secondary channel that serves as the basis for the SCA (i.e., the channel on which backoff occurs). The AP can transmit / make public the above information to the STA using a beacon frame. 【0215】 In this case, the information regarding the channel on which backoff occurs may be in bitmap format. For example, as shown in Figure 13, if the information regarding the channel on which backoff occurs is set to an 8-bit bitmap (e.g., "00100000"), this can indicate that the first 20MHz of S40 (i.e., the second SCH) is the channel on which backoff occurs. Here, we assume that the first bit of the bitmap corresponds to the lowest frequency 20MHz channel, and the last bit of the bitmap corresponds to the highest frequency 20MHz channel (i.e., in ascending order). 【0216】 If information related to SCA is made public from the AP, the STA can perform a backoff based on the first SCH of S40, according to the publicly available information. When the backoff count becomes 0 and the second SCH of S40 is idle, the STA can transmit a frame on S40 (to another STA (e.g., AP)). Furthermore, even if the channel state of S80 is idle, the STA does not need to perform a CCA on a specific SCH of S80, as the maximum bandwidth of the PPDU that can be transmitted via SCA is 40 MHz. 【0217】 As illustrated above, the STA can transmit frames using the SCH even when the PCH is busy, which can increase the efficiency of channel usage. 【0218】 Example 5 【0219】 Example 5 relates to the operation of STA in relation to SCA. 【0220】 In one embodiment of the present disclosure, during the time that NAV is set on the PCH, an STA can transmit frames / PPDUs on the SCH by performing an SCA. For example, an STA can identify / determine the channel state of one or more SCHs based on backoffs performed on one or more SCHs and the CCA results of one or more SCHs that do not undergo backoffs. If the channel state of one or more SCHs is idle, the STA can transmit frames / PPDUs that exclude / puncture the PCH on those one or more SCHs (to other STAs (e.g., APs)). 【0221】 As an addition or alternative, a TXOP set by an SCA performed on one or more SCHs (i.e., a backoff performed on one or more SCHs) may be set to terminate before the NAV on the PCH ends. That is, the termination time of a TXOP that starts with frame / PPDU transmission on an SCH may be set / determined before the NAV on the PCH ends. 【0222】 Here, the length of the TXOP set on the SCH may be set / indicated by the duration / ID field of the frame transmitted by that TXOP. For example, the value of the duration / ID field may be set to the time (including the inter-frame interval (IFS)) required to exchange the frame / PPDU that follows that frame / PPDU. 【0223】 As an addition or alternative, an STA may obtain information about one or more SCHs to be backed off from a management frame (e.g., a beacon frame) transmitted from an AP. In this case, the information about one or more SCHs may include information about whether or not frame / PPDU transmission is possible on one or more SCHs. For example, if the STA performing the SCA is an AP, that STA can use the aforementioned information it has transmitted (e.g., information about whether or not frame / PPDU transmission is possible on an SCH and / or information about one or more SCHs to be backed off). 【0224】 As an addition or alternative, an STA can obtain information on the maximum bandwidth that can be used to transmit frames / PPDUs on the SCH from an AP via a management frame (e.g., a beacon frame). If the STA performing the SCA is an AP, that STA can use the information on the maximum bandwidth that can be used to transmit frames / PPDUs on the SCH that it has transmitted. 【0225】 As an addition or alternative, the STA can obtain thresholds for Type 1 or Type 2 CCAs from management frames (e.g., beacon frames) to determine the channel status on the SCH (i.e., whether the channel is busy or idle). That is, if the numerical value measured by the STA on the SCH (e.g., RSSI or power associated with the channel) exceeds the threshold, the channel status of that SCH can be determined to be busy. 【0226】 As an addition or alternative, the EDCA parameter set for each SCH under backoff may be set to the EDCA parameter set for the PCH, the MU EDCA parameter set, or a new EDCA parameter set. This EDCA parameter set may be applied identically or differently to all SCHs. 【0227】 As an example of this disclosure, an STA receiving a frame transmitted by an SCA can perform frame detection on the SCH even when NAV is set on the PCH. For example, the STA can perform backoff on the SCH for a frame to transmit. As another example, if there is no frame to transmit, the STA can attempt to receive a frame addressed to it on the SCA. The STA can also set / reconfigure NAV based on the value of the interval / ID field of a frame detected on the SCH. 【0228】 As an addition or alternative, an STA may obtain information about one or more SCHs to be backed off by a management frame (e.g., a beacon frame) transmitted from an AP. In this case, the information about one or more SCHs may include information on whether or not frame / PPDU transmission is possible on one or more SCHs. For example, if the STA performing the SCA is an AP, that STA can use the aforementioned information it has transmitted (e.g., information on whether or not frame / PPDU transmission is possible on an SCH and / or information on one or more SCHs to be backed off). 【0229】 As an addition or alternative, the STA can obtain a threshold for a first-type or second-type CCA from a management frame (e.g., a beacon frame) to determine the channel state on the SCH (i.e., whether the channel is busy or idle). That is, if the value measured by the STA on the SCH (e.g., RSSI or power associated with the channel) exceeds the threshold, the channel state of that SCH can be determined to be busy. 【0230】 As an addition or alternative, the EDCA parameter set for each SCH under backoff may be set to the EDCA parameter set for the PCH, the MU EDCA parameter set, or a new EDCA parameter set. This EDCA parameter set may be applied identically or differently to all SCHs. 【0231】 Example 5-1 【0232】 Example 5-1 relates to a method for performing backoff by dividing a channel, including a BSS operating channel, into multiple sets for efficient SCA. In this case, in addition to the information made public for SCA by the AP described in Example 4, Example 4-1, and Example 5, further information described later (e.g., channel subset unit information, SCA channel bitmap size information, etc.) may be made public / transmitted. 【0233】 As an example of this disclosure, AP may disclose information (i.e., channel subset unit information) for SCA regarding bandwidth criteria (or units) for dividing the bandwidth of the overall BSS operating channels into one or more channel subsets. 【0234】 As an example, let's assume that the (sub)field size indicating channel subset unit information is 2 bits. If the (sub)field value indicating channel subset unit information is 0 (i.e., the (sub)field indicates no subset), this means that the BSS operating channel will not be divided into one or more subsets. If the (sub)field value is 1, this means that the bandwidth criterion / unit value for dividing the BSS operating channel into one or more subsets is 40 MHz. If the (sub)field value is 2, this means that the bandwidth criterion / unit value for dividing the BSS operating channel into one or more subsets is 80 MHz. If the (sub)field value is 3, this means that the bandwidth criterion / unit value for dividing the BSS operating channel into one or more subsets is 160 MHz. 【0235】 However, this is only one embodiment, and the (sub)field size indicating channel subset unit information may be set to 3 bits. In this case, the (sub)field may indicate the bandwidth reference / unit value as 320 MHz. 【0236】 Furthermore, the AP can make known to the STA the size of the bitmaps that indicate one or more SCHs that serve as the basis for performing SCA (i.e., SCHs on which backoff occurs) (i.e., SCA channel bitmap size information). 【0237】 As an example, let's assume that the (sub)field size indicating the SCA channel bitmap size information is 2 bits. If the (sub)field value indicating the SCA channel bitmap size information is 0, this can mean that the SCA channel bitmap size is 4 bits. If the (sub)field value indicating the SCA channel bitmap size information is 1, this can mean that the SCA channel bitmap size is 8 bits. If the (sub)field value indicating the SCA channel bitmap size information is 2, this can mean that the SCA channel bitmap size is 16 bits. If the (sub)field value indicating the SCA channel bitmap size information is 3, this can mean that the SCA channel bitmap size is 32 bits. Here, if P20 is not indicated by the SCA channel bitmap, the SCA channel bitmap size may be reduced by 1. 【0238】 Here, the (sub)field size indicating the SCA channel bitmap size information may vary depending on the BSS operating channel. For example, if the BSS operating channel size is 320 MHz, the SCA channel bitmap size may be set / determined to a maximum of 16 bits. 【0239】 For example, if the information indicating one or more reference channels (SCHs) when performing an SCA is configured as a bitmap, then information for configuring / indicating / description of channel subsets is not necessary. In other words, it is not necessary to configure a separate bitmap for each subset. If the information indicating one or more reference channels when performing an SCA is configured as a bitmap, then setting a bit in that bitmap corresponding to a specific channel to 1 can mean that a backoff will occur on that channel. Additionally or alternatively, there does not need to be an SCH on which a backoff occurs within a single channel subset. 【0240】 As an example of this disclosure, Figure 14 shows the case where the bandwidth of the BSS operating channel is 160 MHz. In Figure 14, the shaded portion, excluding P20, can be interpreted as the reference SCH for the SCA (i.e., the SCH on which backoff can be performed). 【0241】 As an example, Figure 14(a) shows the case where the channel subset unit is 40 MHz. When information indicating one or more reference channels (SCH) to be used when performing P20 and SCA is configured as a bitmap, the bitmap may be set to "01101001". In this case, if P20 is not indicated by the bitmap, the bitmap may be set to "01101001". In other words, when performing SCA for all channel subsets, one or more reference channels (SCH) may be represented / set by a single bitmap. 【0242】 As an example, Figure 14(b) shows the case where the channel subset unit is 80 MHz. When information indicating one or more reference channels (SCH) to be used when performing P20 and SCA is configured as a bitmap, the bitmap may be set to "01001000". In this case, if P20 is not indicated by the bitmap, the bitmap may be set to "1001000". In other words, when performing SCA for all channel subsets, one or more reference channels (SCH) may be represented / set by a single bitmap. 【0243】 As yet another example of this disclosure, Figure 15 is a diagram illustrating the SCA channel bitmap when the bandwidth of the BSS operating channel is 320 MHz. That is, assume that the bandwidth of the BSS operating channel is 320 MHz and the channel subset unit is 80 MHz. In Figure 15, the shaded portion, except for P20, can be interpreted as the reference channel of the SCA (i.e., the SCH on which backoff can be performed). 【0244】 For example, if information indicating one or more SCHs to be used as a reference when performing P20 and SCA is configured as a bitmap, the bitmap may be set to "0100100001001000". In this case, if P20 is not indicated by the bitmap, the bitmap may be set to "100100001001000". In other words, one or more SCHs to be used as a reference when performing SCA for all channel subsets may be represented / set by a single bitmap. In other words, one or more SCHs to be used as a reference when performing SCA for all channel subsets may be represented / set by a single bitmap. 【0245】 Unlike existing wireless LAN systems where channel access is based on the state of the primary channel, secondary channel access, as illustrated in the various examples of this disclosure, allows for efficient transmission and reception of frames / PPDUs on one or more secondary channels, even when the primary channel is busy, thereby increasing the utilization of channel resources. 【0246】 The embodiments described above are combinations of the components and features of the present disclosure in a predetermined form. Each component or feature should be considered optional unless otherwise explicitly mentioned. Each component or feature may be implemented in a form that does not combine with other components or features. It is also possible to combine some components and / or features to constitute embodiments of the present disclosure. The order of operations described in embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in other embodiments, or replaced by corresponding components or features of other embodiments. It is clear that claims that do not have an explicit reference relationship in the claims may be combined to constitute embodiments, or may be included as new claims by amendment after filing. 【0247】 It will be obvious to those skilled in the art that this disclosure can be embodied in other specific forms, provided that the essential features of this disclosure are not deviated from. Therefore, the above-mentioned detailed description should not be constrained in any way and should be considered illustrative. The scope of this disclosure should be determined by a reasonable interpretation of the attached claims, and any modifications within the equivalent scope of this disclosure are included within the scope of this disclosure. 【0248】 The scope of this disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that cause an apparatus or computer to perform operations according to the methods of various embodiments, and non-transitory computer-readable medium on which such software or instructions are stored and executable on the apparatus or computer. Instructions available for programming a processing system that performs the features described in this disclosure may be stored on / in a storage medium or computer-readable storage medium, and the features described in this disclosure may be embodied using a computer program product including such storage medium. The storage medium may include, but is not limited to, high-speed random-access memory such as DRAM, SRAM, DDR RAM, or other random-access solid-state memory devices, and may include non-volatile memory such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state storage devices. Memory optionally includes one or more storage devices located remotely from the processor. Memory, or alternatively, non-volatile memory devices within memory, includes non-transitory computer-readable storage medium. The features described in this disclosure may be stored on any one of the machine-readable media and integrated into software and / or firmware that can control the hardware of the processing system and cause the processing system to interact with other mechanisms that utilize the results relating to 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. 【0249】 [Industrial applicability] Although the method proposed in this disclosure has been described primarily in the context of its application to IEEE 802.11-based systems, it can be applied to a variety of other wireless LAN or wireless communication systems. 【0250】 [Claims when filing an international application] [Claim 1] A method performed by a first station (STA) in a wireless LAN system, The second STA receives a first frame containing information related to channel access to at least one non-primary channel, A step of performing a first backoff procedure on the first nonprimary channel among the at least one nonprimary channel based on the first frame, A method comprising the steps of: transmitting a second frame to the second STA on at least one channel, including the first non-primary channel, based on the first frame and the first backoff procedure; or receiving the second frame from the second STA. [Claim 2] The information relating to channel access for the aforementioned at least one non-primary channel is: Information indicating whether or not to allow channel access to non-primary channels, or The method according to claim 1, comprising at least one of the maximum bandwidths capable of transmitting or receiving the second frame. [Claim 3] The method according to claim 2, wherein the bandwidth of the at least one channel on which the second frame is transmitted or received is set to be less than or equal to the maximum bandwidth. [Claim 4] The method according to claim 1, wherein the first STA determines whether the state of the second non-primary channel adjacent to the first non-primary channel is idle, based on the backoff count value of the first backoff procedure becoming 0. [Claim 5] The method according to claim 4, wherein, based on the state of the second nonprimary channel being idle, the at least one channel includes the first nonprimary channel and the second nonprimary channel. [Claim 6] The information relating to channel access for the aforementioned at least one non-primary channel is: The method according to claim 4, further comprising a CCA (clear channel assessment) threshold for determining whether the state of at least one of the first nonprimary channel or the second nonprimary channel is idle. [Claim 7] The information relating to channel access for the aforementioned at least one non-primary channel is: The method according to claim 1, comprising at least one of a bitmap indicating the first non-primary channel on which the first backoff procedure is performed, and information indicating the size of the bitmap. [Claim 8] Each bit in the bitmap is associated with information indicating whether or not each channel of a unit bandwidth is a channel on which the first backoff procedure is performed. The method according to claim 7, wherein the order of each bit in the bitmap is related to the order of each unit bandwidth channel. [Claim 9] The first bit of the bitmap corresponds to the unit bandwidth channel having the highest frequency or the unit bandwidth channel having the lowest frequency, The method according to claim 8, wherein the last bit of the bitmap corresponds to the unit bandwidth channel having the lowest frequency or the unit bandwidth channel having the highest frequency. [Claim 10] The information relating to channel access for the aforementioned at least one non-primary channel is: The method according to claim 1, comprising information regarding unit bandwidth for dividing the total bandwidth of a BSS (basic service set) operating channel into one or more subsets. [Claim 11] The method according to claim 1, wherein the transmission opportunity (TXOP) for transmitting or receiving the second frame ends before the network allocation vector (NAV) set on the primary channel expires. [Claim 12] Based on the fact that the primary channel state is busy, The method according to claim 11, wherein the second frame in which the primary channel is punctured is transmitted to the second STA, or the second frame is received from the second STA. [Claim 13] The method according to claim 1, wherein the first frame includes a beacon frame or a probe response frame. [Claim 14] A first station (STA:station) operating in a wireless LAN system, One or more transceivers; The system comprises one or more processors connected to the one or more transceivers; The one or more processors described above are: The second STA receives a first frame via one or more transceivers that contains information related to channel access to at least one non-primary channel. Based on the first frame, the first backoff procedure is performed on the first nonprimary channel among the at least one nonprimary channel. A first STA is configured to transmit a second frame to the second STA or receive a second frame from the second STA on at least one channel, including the first non-primary channel, based on the first frame and the first backoff procedure, via one or more transceivers. [Claim 15] A method performed by a second station (STA) in a wireless LAN system, The steps include sending a first frame to the first STA containing information related to channel access for at least one non-primary channel, The process includes the step of receiving a second frame from the first STA or transmitting the second frame to the first STA in at least one channel containing the first nonprimary channel, based on the first frame, based on the first backoff procedure being performed in the first nonprimary channel among the at least one nonprimary channel, The first backoff procedure is performed while the primary channel is busy. [Claim 16] A second station (STA:station) operating in a wireless LAN system, One or more transceivers; The system comprises one or more processors connected to the one or more transceivers; The one or more processors described above are: A first frame containing information related to channel access for at least one non-primary channel is transmitted to the first STA via one or more transceivers. Based on the first frame, and based on the first backoff procedure being performed on the first nonprimary channel among the at least one nonprimary channel, the transceiver is configured to receive the second frame from the first STA or transmit the second frame to the first STA on at least one channel that includes the first nonprimary channel via the one or more transceivers. The aforementioned first backoff procedure is performed while the primary channel is in a busy state, followed by a second STA. [Claim 17] A processing device configured to control a first station (STA) operating in a wireless LAN system, One or more processors, The system comprises one or more computer memories that are operably connected to one or more processors and store instructions for performing operations based on execution by the one or more processors, The aforementioned operation is, The operation involves receiving a first frame from the second STA containing information related to channel access for at least one non-primary channel, Based on the first frame, the operation of performing a first backoff procedure on the first nonprimary channel among the at least one nonprimary channel, A processing device that includes, based on the first frame and the first backoff procedure, an operation to transmit a second frame to the second STA on at least one channel including the first non-primary channel, or an operation to receive the second frame from the second STA. [Claim 18] One or more non-transitory computer-readable media for storing one or more instructions, The aforementioned one or more instructions are executed by one or more processors, and the device operating in the wireless LAN system is, The second STA receives a first frame containing information related to channel access to at least one non-primary channel. Based on the first frame, the first backoff procedure is performed on the first nonprimary channel among the at least one nonprimary channel. A computer-readable medium controlled to transmit a second frame to the second STA or receive a second frame from the second STA on at least one channel, including the first non-primary channel, based on the first frame and the first backoff procedure.

Claims

[Claim 1] A method performed by a first station (STA) in a wireless LAN system, The steps include receiving a first frame from the second STA that contains information related to channel access to at least one non-primary channel, A step of performing a first backoff procedure on the first nonprimary channel among the at least one nonprimary channel based on the first frame, A method comprising the steps of: transmitting a second frame to the second STA on at least one channel including the first non-primary channel, based on the first frame and the first backoff procedure; or receiving the second frame from the second STA. [Claim 2] The information relating to channel access for the aforementioned at least one non-primary channel is: Information indicating whether or not to allow channel access to non-primary channels, or The method according to claim 1, comprising at least one of the maximum bandwidths capable of transmitting or receiving the second frame. [Claim 3] The method according to claim 2, wherein the bandwidth of the at least one channel on which the second frame is transmitted or received is set to be less than or equal to the maximum bandwidth. [Claim 4] The method according to claim 1, wherein the first STA determines whether the state of the second non-primary channel adjacent to the first non-primary channel is idle, based on the backoff count value of the first backoff procedure becoming 0. [Claim 5] The method according to claim 4, wherein, based on the state of the second nonprimary channel being idle, the at least one channel includes the first nonprimary channel and the second nonprimary channel. [Claim 6] The information relating to channel access for the aforementioned at least one non-primary channel is: The method according to claim 4, comprising a CCA (clear channel assessment) threshold for determining whether the state of at least one of the first nonprimary channel or the second nonprimary channel is idle. [Claim 7] The information relating to channel access for the aforementioned at least one non-primary channel is: The method according to claim 1, comprising at least one of a bitmap indicating the first non-primary channel on which the first backoff procedure is performed, and information indicating the size of the bitmap. [Claim 8] Each bit in the bitmap is associated with information indicating whether or not each channel of a unit bandwidth is a channel on which the first backoff procedure is performed. The method according to claim 7, wherein the order of each bit in the bitmap is related to the order of each unit bandwidth channel. [Claim 9] The first bit of the bitmap corresponds to the unit bandwidth channel having the highest frequency or the unit bandwidth channel having the lowest frequency, The method according to claim 8, wherein the last bit of the bitmap corresponds to the unit bandwidth channel having the lowest frequency or the unit bandwidth channel having the highest frequency. [Claim 10] The information relating to channel access for the aforementioned at least one non-primary channel is: The method according to claim 1, comprising information relating to unit bandwidth for dividing the total bandwidth of a BSS (basic service set) operating channel into one or more subsets. [Claim 11] The method according to claim 1, wherein the TXOP (transmission opportunity) for transmitting or receiving the second frame is terminated before the time when the NAV (network allocation vector) set on the primary channel expires. [Claim 12] Based on the fact that the primary channel state is busy, The method according to claim 11, wherein the second frame in which the primary channel is punctured is transmitted to the second STA, or the second frame is received from the second STA. [Claim 13] The method according to claim 1, wherein the first frame includes a beacon frame or a probe response frame. [Claim 14] A first station (STA) operating in a wireless LAN system, One or more transceivers; The system comprises: one or more processors connected to one or more transceivers; The one or more processors described above are: From the second STA, a first frame is received via one or more transceivers, which contains information related to channel access to at least one non-primary channel. Based on the first frame, the first backoff procedure is performed on the first nonprimary channel among the at least one nonprimary channel. A first STA is configured to transmit a second frame to the second STA or receive a second frame from the second STA on at least one channel, including the first non-primary channel, based on the first frame and the first backoff procedure, via one or more transceivers. [Claim 15] A method performed by a second station (STA) in a wireless LAN system, The steps include sending a first frame to the first STA containing information related to channel access for at least one non-primary channel, Based on the first frame, a first backoff procedure is performed on the first nonprimary channel among the at least one nonprimary channel, and the step of receiving a second frame from the first STA or transmitting the second frame to the first STA in at least one channel that includes the first nonprimary channel, The first backoff procedure is performed while the primary channel is busy. [Claim 16] A second station (STA) operating in a wireless LAN system, One or more transceivers; The system comprises: one or more processors connected to one or more transceivers; The one or more processors described above are: A first frame containing information related to channel access to at least one non-primary channel is transmitted to the first STA via one or more transceivers. Based on the first frame, and based on the first backoff procedure being performed on the first nonprimary channel among the at least one nonprimary channel, the transceiver is configured to receive the second frame from the first STA or transmit the second frame to the first STA on at least one channel containing the first nonprimary channel via the one or more transceivers. The first backoff procedure is performed while the primary channel is busy, followed by a second STA. [Claim 17] A processing device configured to control a first station (STA) operating in a wireless LAN system, One or more processors, The system comprises one or more computer memories that are operably connected to one or more processors and store instructions for performing operations based on execution by the one or more processors, The aforementioned operation is, The operation involves receiving a first frame from the second STA that contains information related to channel access to at least one non-primary channel, Based on the first frame, the operation of performing a first backoff procedure on the first nonprimary channel among the at least one nonprimary channel, A processing device that includes, based on the first frame and the first backoff procedure, an operation to transmit a second frame to the second STA on at least one channel including the first non-primary channel, or an operation to receive the second frame from the second STA. [Claim 18] One or more non-transitory computer-readable media for storing one or more instructions, The aforementioned one or more instructions are executed by one or more processors, and the device operating in the wireless LAN system is, The second STA receives a first frame containing information related to channel access to at least one non-primary channel. Based on the first frame, the first backoff procedure is performed on the first nonprimary channel among the at least one nonprimary channel. A computer-readable medium controlled to transmit a second frame to the second STA or receive a second frame from the second STA in at least one channel, including the first non-primary channel, based on the first frame and the first backoff procedure.

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