Method and apparatus for performing NPCA within txop in which multi-AP operation is performed in wireless LAN system

Abstract

The present disclosure relates to a wireless LAN system. At least one embodiment of the present disclosure describes a method and an apparatus for indicating that a terminal capable of performing non-primary channel access (NPCA) is capable of performing multi-AP (MAP) coordination operations in order to efficiently perform the MAP coordination operations.

Description

Method and device for NPCA operation within a TXOP where MULTI-AP operation is performed in a wireless LAN system

[0001] The present disclosure relates to a method and apparatus for transmitting a signal in a wireless LAN network system, and more specifically, to a method and apparatus for setting the operation of APs and STAs capable of performing NPCA within a TXOP in which multi-AP operation is performed.

[0002] A Wireless Local Area Network (WLAN), also known as Wi-Fi, is a network that enables internet access via mobile devices or laptops within a certain distance from an access point (AP). WLAN technology continues to evolve in line with the rise of the internet and the expansion of the smartphone market, and is being utilized to provide high-speed data services throughout the city, including in schools, airports, hotels, and offices.

[0003] The WiFi Alliance defines WiFi as a Wireless Local Area Network (WLAN) product based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. IEEE 802.11a and b, published in 1997 and 1999 respectively, are standards utilizing unlicensed bands at 2.4 GHz or 5 GHz; IEEE 802.11b (also known as Wi-Fi 2) provides a transmission speed of 11 Mbps, while IEEE 802.11a (also known as Wi-Fi 1) provides a transmission speed of 54 Mbps. IEEE 802.11g (also known as Wi-Fi 3) provides a transmission speed of 54 Mbps by applying Orthogonal Frequency-Division Multiplexing (OFDM) at 2.4 GHz. IEEE 802.11n (also known as Wi-Fi 4 or High Throughput, HT) utilizes multiple input multiple output OFDM (MIMO-OFDM) to provide a transmission speed of 300 Mbps using four spatial streams. IEEE 802.11n supports channel bandwidths up to 40 MHz, in which case it provides a transmission speed of 600 Mbps.

[0004] Subsequently, the IEEE 802.11ac standard (also called Wi-Fi 5 or Very High Throughput, VHT), which uses a maximum bandwidth of 160 MHz and supports 8 spatial streams to support speeds of up to 1 Gbit / s, and the IEEE 802.11ax standard (also called Wi-Fi 6 or High Efficiency, HE), which provides multi-user MIMO (MU-MIMO) in the uplink and downlink and supports spatial frequency reuse, dynamic fragmentation, etc., were introduced. Subsequently, 802.11be (also known as Wi-Fi 7 or Extremely High Throughput, EHT) was introduced to theoretically achieve a speed of 46Gbps by supporting up to 320 ultra-wide channels, multi-link operation, and 4kQAM, and 802.11bn (also known as Wi-Fi 8, Ultra High Reliability, UHR) is being researched to introduce technologies that optimize spectrum usage and reduce interference by strengthening collaboration among multiple APs, power management technologies to reduce energy consumption, and technologies to optimize spectrum allocation.

[0005] In 802.11, secondary channels cannot be used when the primary channel is busy. In such cases, techniques to increase channel utilization through channel access on non-primary channels (or secondary channels) are being researched, and this is referred to as NPCA (non-primary channel access). Additionally, transmission and reception methods involving multiple APs, such as TXOP (transmission opportunity) sharing to share time resources for effective resource utilization, are being researched. When an AP capable of performing NPCA has the opportunity to perform multi-AP operation, it is necessary to communicate whether multi-AP operation and / or NPCA operation are possible for the efficient operation of the AP and STAs.

[0006] The present invention for solving the above-mentioned problems is characterized by a method performed by an electronic device corresponding to a first AP (access point) of a wireless LAN network, comprising: a step of acquiring a TXOP (transmission opportunity); a step of transmitting a frame including information indicating whether the TXOP corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation; and a step of performing frame exchange with STAs (stations) associated with the TXOP.

[0007] In addition, a method performed by an electronic device corresponding to a second AP (access point) of a wireless LAN network comprises: receiving a frame from an OBSS (overlapping basic service set) AP; determining whether the TXOP occupied by the OBSS AP included in the frame corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation based on information indicating whether the TXOP corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation; and performing an operation to switch to a non-primary channel access (NPCA) PCH (primary channel) or not based on the determination.

[0008] In addition, a method performed by an electronic device corresponding to a STA (station) of a wireless LAN network comprises: receiving a frame from an OBSS (overlapping basic service set) AP; determining whether the TXOP occupied by the OBSS AP included in the frame corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation based on information indicating whether the TXOP corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation; and performing an operation to switch to a non-primary channel access (NPCA) PCH (primary channel) or not based on the determination.

[0009] In addition, an electronic device corresponding to a first AP (access point) of a wireless LAN network is characterized by comprising: a transceiver; and a control unit configured to acquire a TXOP (transmission opportunity), transmit a frame containing information indicating whether the TXOP corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation, and perform frame exchange with associated STAs (stations) at the TXOP.

[0010] In addition, an electronic device corresponding to a second AP (access point) of a wireless LAN network comprises: a transceiver; and a control unit configured to receive a frame from an OBSS (overlapping basic service set) AP, determine whether the TXOP occupied by the OBSS AP included in the frame corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation based on information indicating whether the TXOP corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation, and perform an operation to switch to a non-primary channel access (NPCA) PCH (primary channel) or not based on the determination.

[0011] In addition, an electronic device corresponding to a STA (station) of a wireless LAN network comprises: a transceiver; and a control unit configured to receive a frame from an OBSS (overlapping basic service set) AP, determine whether the TXOP occupied by the OBSS AP included in the frame corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation based on information indicating whether the TXOP corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation, and perform an operation to switch to a non-primary channel access (NPCA) PCH (primary channel) or not based on the determination.

[0012] According to a method according to at least one embodiment of the present disclosure, by instructing APs and STAs capable of performing NPCA whether to perform multi-AP operations, the APs capable of performing NPCA can perform NPCA or multi-AP operations depending on the situation, thereby efficiently using resources and increasing throughput.

[0013] Figure 1 is a diagram illustrating an example of a wireless communication network.

[0014] Figure 2 is a diagram illustrating an example of the structure of an electronic device that performs WLAN connection.

[0015] Figure 3 is a diagram illustrating an example of a link setup process for a typical wireless LAN.

[0016] Figure 4 is a diagram illustrating an example of a hidden node and an exposed node, and an example of an RTS and CTS for solving the problem of a hidden node and an exposed node.

[0017] Figure 5 is a diagram illustrating an example of a frame structure used in an IEEE 802.11 system.

[0018] Figure 6 is a diagram illustrating an example of a NAV setting.

[0019] Figure 7 is a diagram illustrating an example of TXOP.

[0020] Figure 8 is a diagram illustrating NPCA (non-primary channel access).

[0021] FIG. 9 is a diagram illustrating an example of the operation of an AP capable of performing both NPCA and C-TDMA operations.

[0022] FIG. 10 is a diagram illustrating an example of the operation of an AP capable of performing both NPCA and C-BF operations.

[0023] FIG. 11a is a drawing illustrating an example of a trigger frame format.

[0024] Figure 11b is a diagram illustrating an example of an EHT variant common info field format.

[0025] FIG. 11c is a diagram illustrating an example of a special user info field format.

[0026] Figure 12 is a diagram illustrating an example of the operation of an AP when the MAP TXOP field is included in the ICF.

[0027] FIG. 13 is a diagram illustrating an example of operation when an AP and STA capable of performing NPCA receive an ICF.

[0028] FIG. 14 is a diagram illustrating an example of operation when an AP and a STA capable of performing NPCA receive a PPDU.

[0029] FIG. 15 is a drawing illustrating an example of the operation of an AP performing an embodiment of the present disclosure.

[0030] FIG. 16 is a diagram illustrating an example of the operation of an AP that can share TXOP.

[0031] FIG. 17 is a diagram illustrating an example of the operation of an AP that can receive an indication from the OBSS AP whether a TXOP is a MAP TXOP.

[0032] FIG. 18 is a diagram illustrating an example of the operation of a STA that can receive an indication from the OBSS AP whether a TXOP is a MAP TXOP.

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings.

[0034] In describing the embodiments, technical details that are well known in the art to which this disclosure belongs and are not directly related to this disclosure are omitted. This is intended to convey the essence of this disclosure more clearly without obscuring it by omitting unnecessary explanations.

[0035] For the same reason, some components in the attached drawings have been exaggerated, omitted, or schematically depicted. Additionally, the size of each component does not entirely reflect its actual dimensions. Identical or corresponding components in each drawing have been assigned the same reference number.

[0036] The advantages and features of the present disclosure and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms. The embodiments of the present disclosure are provided merely to make the present disclosure complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Throughout the specification, like reference numerals refer to like components.

[0037] At this point, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Since these computer program instructions can be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in the flow diagram block(s). Since these computer program instructions can also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in computer-available or computer-readable memory can also produce a manufactured item containing means of instruction to perform the function described in the flow diagram block(s).

[0038] Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that execute a computer or other programmable data processing equipment by performing a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer may also provide steps for executing the functions described in the flowchart block(s).

[0039] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specific logical function(s). It should also be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For instance, two blocks described in succession may actually be executed substantially simultaneously, or the blocks may be executed in reverse order depending on the corresponding function.

[0040] In this embodiment, the term "part" as used refers to a software or hardware component such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), and the "part" performs certain roles. However, the meaning of "part" is not limited to software or hardware. The "part" may be configured to reside in an addressable storage medium or may be configured to run one or more processors. Accordingly, according to some embodiments, the "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts." In addition, the components and 'parts' may be implemented to utilize one or more CPUs within the device or secure multimedia card. Also, according to some embodiments, the 'parts' may include one or more processors.

[0041] Exemplary embodiments are described below in relation to wireless LAN systems solely for the sake of simplicity. It should be understood that the exemplary embodiments are equally applicable to systems using signals of one or more wired standards or protocols (e.g., Ethernet and / or HomePlug, PLC standards), as well as other wireless networks (e.g., cellular networks, pico networks, femto networks, satellite networks). As used herein, the terms WLAN and Wi-Fi® may include communications controlled by the IEEE 802.11 family of standards, BLUETOOTH®, HiperLAN (a set of wireless standards comparable to IEEE 802.11 standards, mainly used in Europe), and other technologies having a relatively short wireless propagation range. Accordingly, the terms WLAN and Wi-Fi may be used interchangeably herein. Additionally, although the following describes an infrastructure WLAN system including one or more APs and multiple wireless stations (STAs), exemplary embodiments are equally applicable to other WLAN systems including, for example, multiple WLANs, peer-to-peer (or independent basic service set) systems, Wi-Fi Direct systems and / or hotspots.

[0042] Additionally, while this specification describes the exchange of data frames between wireless devices, exemplary embodiments may be applied to the exchange of any data unit, packet, and / or frame between wireless devices. Accordingly, the term "frame" may include any frame, packet, or data unit such as, for example, protocol data units (PDUs), MAC (media access control) protocol data units (MPDUs), and PHY protocol data units (PPDUs). The term "A-MPDU" may mean aggregated MPDUs. In the following, a wireless LAN, or WLAN network, may be a network implementing at least one of the IEEE 802.11 wireless communication protocol standard family, such as as defined by the IEEE 802.11-2016 standard or its amendments (including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be).

[0043] In the following description, many specific details, such as examples of specific components, circuits, and processes, are presented to provide a thorough understanding of the present disclosure. As used herein, the term “connected” means being directly connected or being connected through one or more intervening components or circuits. The term “connected AP” means an access point to which a given wireless station is currently associated and / or connected (e.g., there exists a communication channel or link established between the access point and the given wireless station). Additionally, in the following description and for illustrative purposes, specific nomenclature is presented to provide a thorough understanding of exemplary embodiments. However, it will be apparent to those skilled in the art that these specific details may not be necessary to carry out the exemplary embodiments. In other cases, well-known circuits and devices are depicted in block diagram form to avoid obscuring the present disclosure. Also, the description of A / B means A or / and B, or at least one of A or B.

[0044] The operating principles of the present disclosure will be described in detail below with reference to the attached drawings. In describing the present disclosure below, specific descriptions of related known functions or configurations will be omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the present disclosure. Furthermore, the terms described below are defined in consideration of their functions in the present disclosure, and these may vary depending on the intentions or practices of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0045] FIG. 1 is a diagram illustrating an example of a wireless communication network. The wireless communication network (100) may be an example of a wireless LAN, such as a Wi-Fi network. The wireless communication network (100) may include a number of wireless communication devices, such as an access point (AP, t102) and a number of stations (STA, 104). Although only one AP (102) is illustrated, the wireless communication network (100) may also include a number of APs (102).

[0046] A STA is a logical entity that includes a physical layer interface for a MAC and a wireless medium, and includes APs and non-AP STAs (Non-AP stations). Among the STAs, a portable terminal operated by a user is a Non-AP STA, and when simply referred to as STA, it may also refer to a Non-AP STA. Hereinafter, STA may refer to a non-AP STA. Each of the STAs (104) may be referred to as a terminal or a device. The terms 'terminal' or 'device' used in this specification may be referred to as a mobile station (MS), user equipment (UE), user terminal (UT), wireless terminal, access terminal (AT), terminal, subscriber unit, subscriber station (SS), wireless device, wireless communication device, wireless transmit / receive unit (WTRU), mobile node, mobile, or other terms. Various embodiments of the terminal may include cellular telephones, smartphones with wireless communication capabilities, personal handheld terminals (PDAs) with wireless communication capabilities, wireless modems, portable computers with wireless communication capabilities, imaging devices such as digital cameras with wireless communication capabilities, gaming devices with wireless communication capabilities, music storage and playback appliances with wireless communication capabilities, internet appliances capable of wireless internet access and browsing, as well as portable units or terminals integrating combinations of such functions. Additionally, the terminal may include machine-to-machine (M2M) terminals and machine-type communication (MTC) terminals / devices, but is not limited thereto. In this specification, the terminal may be referred to as an electronic device or simply a device.

[0047] An AP (102) is an entity that provides access to a distribution system (DS) via a wireless medium to an associated STA (STA) connected to it. The AP may also be called a central controller, a base station (BS), a Node-B, a base transceiver system (BTS), or a site controller.

[0048] An exemplary coverage area (106) of an AP (102) capable of representing the basic service area (BSA) of a wireless communication network (100) is illustrated. The AP (102) periodically broadcasts beacon frames (beacon frames may be interchangeable with beacons) containing a basic service set identifier (BSSID) to enable any STA (104) within the wireless range of the AP (102) to be associated with or re-associated with the AP (102) to establish or maintain individual communication links (108) (or may be referred to as Wi-Fi links) with the AP (102). The AP (102) can provide access to external networks for various STAs (104) within the WLAN through individual communication links (108).

[0049] A single AP (102) and an associated set of STAs (104) may be referred to as a basic service set (BSS) managed by the individual AP (102). The BSS may be identified to users by a service set identifier (SSID), as well as to other devices by a BSSID, which may be the MAC address of the AP (102).

[0050] BSS can be classified into infrastructure BSS and independent BSS (IBSS). The BSS shown in Fig. 1 is an IBSS, and it is also possible to establish an infrastructure BSS (not shown). An infrastructure BSS includes one or more STAs and APs, and in principle, communication between non-AP STAs in an infrastructure BSS is carried out via an AP, but if a direct link is established between non-AP STAs, direct communication between non-AP STAs is also possible.

[0051] Multiple infrastructure BSSs can be interconnected via DS. Multiple BSSs connected via DS are called an extended service set (ESS). STAs included in an ESS can communicate with each other, and within the same ESS, STAs can move from one BSS to another while communicating seamlessly.

[0052] A DS is a mechanism that connects multiple APs; it does not necessarily have to be a network, and there are no restrictions on its form as long as it can provide a specified distribution service. For example, a DS can be a wireless network such as a mesh network, or it can be a physical structure that connects APs to each other.

[0053] Additionally, AP (102) and STA (104) may be referred to as AP-MLD (access point multi-link device) and STA-MDL, respectively. This may mean that AP and STA can support multi-link operation.

[0054] Below, an example of a hierarchical structure according to the 802.11 standard is described.

[0055] The 802.11 standard document develops MAC and PHY protocols corresponding to Wi-Fi wireless access technology. The Data Link Layer (DLL) includes the MAC sublayer, which is responsible for media access control. It receives packets from the upper layer, 802.1X Port Filtering, via the MAC_SAP interface, constructs them into IEEE 802.11 MAC frames, and transmits them to the physical layer. The physical layer includes the PLCP (Physical Layer Convergence Procedure) sublayer and the PDM (Physical Medium Dependent) sublayer. The PLCP sublayer is responsible for converting the IEEE 802.11 MAC frames constructed by the MAC sublayer into PLCP frames. The PLCP frames are then transmitted to the target terminal through the PMD sublayer.

[0056] Various management frames that manage Wi-Fi wireless access are not transmitted at the upper layers of 802.1X. Instead, these management frames are transmitted as requests and responses between Station Management Entities (SMEs) located within each terminal. An SME is a layer-independent entity that may exist within a separate management plane or appear to be off-the-side. For example, if an AP wants to configure a BSS, it instructs the transmission of beacons via the MLME_SAP interface, specifically the MLME-START.request and MLME-START.confirm primitives. If an STA wants to establish an association with the corresponding AP, it instructs the transmission of association Request / Response frames via the MLME-ASSOCIATE.request, MLME-ASSOCIATE.response, MLME-ASSOCIATE.confirm, and MLME-ASSOCIATE.indication primitives. Meanwhile, if you wish to set operational parameter values ​​related to the physical layer, the SME can set various physical layer parameter values ​​through the PLCP_SAP interface.

[0057] FIG. 2 is a diagram illustrating an example of the structure of an electronic device performing a WLAN connection. Referring to FIG. 2, the electronic device (200) may be connected to an AP (210), and the electronic device (200) may include a processor (230) and a communication module (220). The electronic device (200) may be the STA (104) of FIG. 1, in which case the electronic device (200) may be connected to the AP (210) as illustrated. Alternatively, the electronic device (200) may be the AP (102) of FIG. 1, in which case the electronic device may be connected to the STA (104) and / or another AP as illustrated in FIG. 1.

[0058] The communication module (220) can receive a communication signal from the outside or transmit a communication signal to the outside based on a Wi-Fi communication method (e.g., IEEE Std 802.11™). For example, the communication module (220) can operate based on Wi-Fi communication methods such as IEEE 802.11ac, 802.11ax, 802.11be, or 802.11bn, and in particular, IEEE 802.11be or 802.11bn supports a wider bandwidth, higher data throughput, and shorter latency compared to IEEE 802.11ax, thereby improving performance.

[0059] The communication module (220) may include a transceiver (224) for transmitting and receiving data with an external device and a communication processor (222) (e.g., a communication processor (not shown), or a short-range wireless communication module (e.g., a Wi-Fi chipset)). Depending on various embodiments, the communication module (220) may further include memory.

[0060] According to various embodiments, the transceiver (224) can convert a baseband transmission signal into a wireless signal or convert a received wireless signal into a baseband reception signal.

[0061] According to various embodiments, the communication module (220) may further include, in addition to the transceiver (224) and the communication processor (222), components for OFDM or OFDMA (orthogonal frequency division multiple access), such as a modulator, a digital-analog converter, a frequency converter, an A / D converter, an amplifier, and / or a demodulator.

[0062] According to various embodiments not shown, the electronic device (200) may be electrically connected to a communication module of the AP (210) and may include at least one antenna module that supports a communication protocol and / or frequency band supported by the communication module of the AP (210).

[0063] The communication processor (222) can control the transceiver (224) to form a communication connection with the AP (210). For example, the communication connection may include a Wi-Fi network. For example, the communication processor (222) can control the transceiver (224) to form a wireless connection with the AP (200) using a WLAN standard in the 2.4 GHz, 5 GHz, or 6 GHz band such as IEEE 802.11ac, 802.11ax, 802.11be, or 802.11bn. Alternatively, the communication processor (222) can control the transceiver (191) to form a wireless connection with the AP (210) using a WLAN standard in the 60 GHz band such as IEEE 802.11ad or 802.11ay. In addition, the method of communicating between the electronic device (200) and the AP (210) using a WLAN standard can be referred to as a communication method based on STA mode.

[0064] According to various embodiments, the processor (230) may include an application processor. The processor (230) may perform a specified operation of the electronic device (200) or control other hardware (e.g., a communication module (220)) to perform a specified operation.

[0065] According to various embodiments, the AP (210) may support the operation of transmitting packets to an external network and / or the operation of receiving packets from an external network based on a connection between a plurality of electronic devices (e.g., electronic device (200)) and an external network (e.g., the Internet, an external LAN, or a cellular network).

[0066] For example, the AP (210) may be a wireless router. The AP (210) may be a dedicated wireless router or a general-purpose device that supports mobile hotspot functions, and there are no limitations on its implementation. For example, the AP (210) may include the same components (e.g., a processor and / or a communication module) as the electronic device (200). Additionally, the AP (210) may transmit and receive data with an external device, such as a server. For example, the AP (210) may transmit at least some of the data received from the server to the electronic device (200).

[0067] If the electronic device (200) of FIG. 2 corresponds to the AP (102), the electronic device (200) may include a separate communication module for connection with an external network, although not shown. This communication module may be controlled by a processor (230) or by a separate processor. The separate communication module may include a transceiver and a processor, and may also include memory. Additionally, the electronic device (200) may include a separate antenna module or a wired connection device for connection with an external network.

[0068] Figure 3 is a diagram illustrating an example of a link setup process for a typical wireless LAN.

[0069] In order for an STA to set up a link and transmit and receive data on a network, it must first discover the network, perform authentication, establish an association, and go through authentication procedures for security. The link setup process can also be referred to as the session initiation process or the session setup process. Additionally, the discovery, authentication, association, and security setup processes of the link setup process can be collectively referred to as the association process.

[0070] Referring to FIG. 3, the STA (300) can perform a network discovery operation. The network discovery operation may include a scanning operation of the STA (300). That is, in order for the STA (300) to access a network, it must find a network that it can join. Before joining a wireless network, the STA (300) must identify a compatible network, and the process of identifying networks existing in a specific area is called scanning.

[0071] Scanning methods include active scanning and passive scanning. In active scanning, the STA (300) performing the scanning moves between channels and sends a probe request frame (322) to search for nearby APs and waits for a response. The responder sends a probe response frame (324) as a response to the probe request frame to the STA that sent the probe request frame. Here, the responder may be the AP or STA that last sent a beacon frame from the BSS of the channel being scanned. FIG. 3 illustrates an example of a BSS that becomes the responder because the AP (310) sends a beacon frame (320). In an IBSS, the responder is not constant because the STAs within the IBSS take turns sending beacon frames. For example, if an STA transmits a probe request frame on channel 1 and receives a probe response frame on channel 1, the STA can store the BSS-related information included in the received probe response frame and move to the next channel to perform scanning in the same way.

[0072] Scanning operations may be performed using a passive scanning method. In passive scanning, the STA performing the scanning detects beacon frames while switching between channels. A beacon frame is one of the management frames in IEEE 802.11, which announces the presence of a wireless network and is periodically transmitted to allow the scanning STA to find the wireless network and join it. Figure 3 illustrates an example of a BSS in which an AP (310) periodically transmits beacon frames (320) to an STA (300), and in an IBSS, STAs within the IBSS take turns transmitting beacon frames. When the scanning STA receives a beacon frame, it stores information about the BSS included in the beacon frame and records the beacon frame information in each channel while moving to another channel. When comparing active scanning and passive scanning, active scanning has the advantage of having less delay and power consumption than passive scanning.

[0073] After the STA (300) discovers the network, an authentication process may be performed. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation (350) described later. The authentication process includes the STA (300) sending an authentication request frame (330) to the AP (310), and in response, the AP (310) sending an authentication response frame (332) to the STA (300). The authentication frame used in the authentication request / response corresponds to a management frame.

[0074] The authentication frame may include information such as the authentication algorithm number, authentication transaction sequence number, status code, challenge text, RSN (robust security network), finite cyclic group, etc. These are some examples of information that may be included in the authentication request / response frame, and may be replaced with other information or additional information may be included.

[0075] AP (310) can determine whether to allow authentication for the STA based on the information included in the received authentication request frame. AP (310) can provide the result of the authentication processing to the STA (300) through an authentication response frame.

[0076] After the STA is successfully authenticated, an association process may be performed. The association process includes the STA (300) sending an association request frame (340) to the AP (310), and in response, the AP (310) sending an association response frame (342) to the STA (300).

[0077] For example, the associated request frame may include information regarding various capabilities, beacon listen interval, SSID, supported rates, supported channels, RSN (robust security network), mobility domain, supported operating classes, traffic indication map broadcast request, interworking service capabilities, etc.

[0078] For example, an association response frame may include information related to various capabilities, status code, association ID (AID), support rate, enhanced distributed channel access (EDCA) parameter set, received channel power indicator (RCPI), received signal to noise indicator (RSNI), mobility domain, timeout interval (association comeback time), overlapping BSS scan parameters, TIM broadcast response, QoS map, etc.

[0079] This is a partial example of the information that may be included in the associated request / response frame, and it may be replaced with other information or additional information may be included.

[0080] Although not yet described, a security setup process can be performed after the STA is successfully associated with the network. The security setup process may be described as an authentication process through RSNA (robust security network association) requests / responses, and the authentication process (330) may be called the first authentication process, and the security setup process may also be called the authentication process.

[0081] The security setup process may include, for example, a process of setting up a private key through a 4-way handshake via an EAPOL (extensible authentication protocol over LAN) frame, or it may be performed according to a security method not defined in the IEEE 802.11 standard.

[0082] The following describes the Media Access Control Protocol provided by 802.11.

[0083] In wireless LAN systems based on IEEE 802.11, the basic access mechanism of a MAC is based on a distributed coordination function (DCF) utilizing the carrier sense multiple access with collision avoidance (CSMA / CA) method. There are two methods for detecting carriers in DCF: physical carrier sense and virtual carrier sense. The physical carrier sense method detects channel conditions at the physical layer and informs the MAC layer, while the virtual carrier sense method reserves a channel in advance by broadcasting the channel occupancy time to surrounding stations. An STA or AP that has secured a transmission channel records and transmits this channel occupancy time within an RTS and / or CTS or data frame; other STAs receiving this information determine that the channel is in use during this time and avoid channel occupancy contention, thereby avoiding collisions.

[0084] The physical carrier sensing method basically employs a listen before talk access mechanism, and according to this type of access mechanism, the AP and / or STA can perform a clear channel assessment (CCA) to sense the wireless channel, carrier, or medium for a predetermined time interval before starting transmission. The predetermined time interval is referred to as the inter-frame space (IFS) and may vary depending on the priority of the traffic to be transmitted. That is, priority can be determined by the length of the time interval, and packets with higher priority may have shorter time intervals.

[0085] The above IFS may include SIFS (short IFS), PIFS (PCF IFS), DIFS (DCF IFS), AIFS (arbitration IFS), etc. SIFS is the shortest time interval and can be used primarily as a waiting time for control information. PIFS is a medium-length time interval and can be for packets of medium priority (PIFS = SIFS + 1 slot time). DIFS is the longest time interval compared to SIFS and PIFS, has a low priority, and can be used primarily as a waiting time to check channel usage (DIFS = SIFS + 2 slot time). That is, for example, an STA intending to perform transmission can listen to (or detect channel) the channel usage during the DIFS period.

[0086] If sensing results determine that the medium is in an idle status, the AP and / or STA initiate frame transmission through the medium. Conversely, if the medium is detected to be in an occupied status, the AP and / or STA may not initiate their own transmission but wait for a delay period for medium access (e.g., a random backoff period) before attempting frame transmission. By applying a random backoff period, multiple STAs are expected to attempt frame transmission after waiting for different durations, thereby minimizing collisions. For example, the AP and / or STA randomly select a timer value within the contention window (CW) range, wait until the timer expires, and then sense the channel again. At this point, if the medium is idle, the AP and / or STA may initiate frame transmission; if the medium is occupied, the AP and / or STA doubles the size of the contention window and selects a timer value again. The size of the initially applied contention window is the minimum window size (contention window minimum, CW min It is referred to as the maximum window size (contention window maximum, CW), and the maximum size of the contention window that can be applied is called the maximum window size (contention window maximum, CW max It is called ).

[0087] However, since this DCF method does not consider the priority between STAs, it has the problem of being difficult to support various forms of data transmission and QoS (quality of service); therefore, HCF (hybrid coordination function) was introduced. HCF is based on the aforementioned DCF and PCF (point coordination function). PCF refers to a polling-based synchronous access method that periodically polls all receiving APs and / or STAs so that they can receive data frames. HCF includes EDCA (enhanced distributed channel access), a contention-based channel access method, and HCCA (HCF controlled channel access), a contention-based method utilizing a polling mechanism. Furthermore, HCF includes a media access mechanism to enhance the QoS of a WLAN and can transmit QoS data during both the contention period (CP) and the contention-free period (CFP).

[0088] According to EDCA, data has priorities ranging from 0 to 7 based on traffic type, and data arriving at the MAC layer is mapped to four access categories (ACs) according to these priorities. Higher priorities correspond to higher priority, and since each AC has its own parameters and backoff is performed using differently configured AC parameter values, data has different channel access priorities depending on the AC. The AC parameters include AIFS and CW. min , CW max , TXOP limits, etc. may exist. AIFS and CW minThe smaller the value, the higher the priority, and accordingly, the channel access delay is shortened, allowing data to use more bandwidth in a given traffic environment. The backoff process of EDCA, which generates a new backoff counter when a collision occurs between STAs during frame transmission, is similar to the existing DCF, and transmission based on traffic priority is guaranteed through EDCA parameters that include priority per AC.

[0089] Figure 4 is a diagram illustrating an example of a hidden node and an exposed node, and an example of an RTS and CTS for solving the problem of a hidden node and an exposed node.

[0090] Figure 4 (a) (400) is an example of a hidden node. When STA A and STA B are communicating and STA C has information to transmit, STA A is transmitting information to STA B, but when STA C performs carrier sensing before sending data to STA B, it can be determined that the medium is idle. This is because STA C may not be able to sense STA A's transmission (i.e., medium occupancy) at its location. In this case, a collision occurs because STA B receives information from STA A and STA C simultaneously. At this time, STA A can be considered a hidden node of STA C.

[0091] (b)(410) is an example of an exposed node. In a situation where STA B is transmitting data to STA A, STA C may have information to transmit to STA D. In this case, if STA C performs carrier sensing, it can determine that the medium is occupied due to the transmission by STA B. Accordingly, STA C must wait until the medium becomes idle, even if it has information to transmit to STA D. However, in reality, since STA A is outside the transmission range of STA C, the transmission from STA C and the transmission from STA B may not conflict from STA A's perspective, so STA C ends up waiting unnecessarily until STA B stops transmitting. In this case, STA C can be referred to as the exposed node of STA B.

[0092] In order to efficiently utilize the collision avoidance mechanism in the above situation, short signaling packets such as RTS (request to send) and CTS (clear to send) may be used. An STA intending to transmit data transmits an RTS to a STA intending to receive data, and the receiving STA that receives the RTS responds to the transmitting STA with a CTS frame. The RTS and / or CTS between the two STAs may cause surrounding STA(s) to overhear, thereby causing the surrounding STA(s) to consider whether to transmit information between the two STAs.

[0093] (c)(420) is an example of how to solve the hidden node problem. Assume that both STA A and STA C intend to transmit data to STA B. When STA A transmits an RTS to STA B, STA B transmits a CTS to STA A. STA C, which overhears the RTS and CTS, delays its media access until the data transmission of STA A and STA B is finished, thereby avoiding collisions.

[0094] (d)(430) is an example of a method for solving the exposed node problem. STA B, which intends to send data to STA A, sends an RTS, and STA A, which is to receive the data, sends a CTS to respond to the RTS. In this case, if STA C receives only the RTS sent by STA B and does not receive the CTS sent by STA A, STA C can determine that STA A is outside the carrier sensing area of ​​STC C. In this case, STA C can determine that no collision will occur even if it sends data to another STA (e.g., STA D) and can send the data.

[0095] Figure 5 is a diagram illustrating an example of a frame structure used in an IEEE 802.11 system.

[0096] The PPDU (physical layer protocol data unit) format can be configured to include the STF (short training field), LTF (long training field), SIG (signal) field, and data field. The most basic (e.g., non-HT (high throughput)) PPDU frame format can be configured to include only the L-STF (legacy-STF), L-LTF (legacy-LTF), SIG field, and data field.

[0097] STF can be used for frame timing acquisition, automatic gain control (AGC), diversity detection, and coarse frequency / time synchronization. LTF can be used for fine frequency / time synchronization and channel estimation. STF and LTF together can be referred to as the PHY preamble, and the PHY preamble is a signal for synchronization and channel estimation in the OFDM physical layer.

[0098] The SIG field can be used to transmit control information for demodulation and decoding of the data field. The SIG field may include information regarding the data rate and data length. Additionally, the SIG field may include a parity bit, a SIG TAIL bit, etc.

[0099] 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 the descrambler at the receiver. The PSDU corresponds to the MPDU (MAC protocol data unit) defined at the MAC layer and may contain data generated or used by the upper layer. The PPDU TAIL bits may be used to return the encoder to a state of 0. Padding bits may be used to adjust the length of the data field to a predetermined unit.

[0100] MPDUs are defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a frame check sequence (FCS). A MAC frame is composed of an MPDU and can be transmitted or received through the PSDU of the data portion in the PPDU format.

[0101] The MAC header is defined as an area containing the frame control field, duration / ID field, address 1 field, address 2 field, address 3 field, sequence control field, address 4 field, QoS control field, and HT control field.

[0102] The frame control field contains information about the corresponding MAC frame characteristics. The interval / identifier field can be implemented to have different values ​​depending on the type and subtype of the corresponding MAC frame.

[0103] Fields 1 through 4 of the address are used to indicate the BSSID, source address (SA), destination address (DA), transmitting address (TA) representing the transmitting STA address, and receiving address (RA) representing the receiving STA address.

[0104] The sequence control field is configured to include a sequence number and a fragment number. The sequence number may indicate the sequence number assigned to the corresponding MAC frame. The fragment number may indicate the number of each fragment of the corresponding MAC frame.

[0105] The QoS control field contains information related to QoS. The QoS control field may be included if the Subtype subfield indicates a QoS data frame. The HT control field contains control information related to HT and / or VHT transmission and reception techniques.

[0106] The frame body is defined as the MAC payload, contains the data to be transmitted from the upper layer, and has a variable size. For example, the maximum MPDU size can be 11,454 octets, and the maximum PPDU size can be 5.484 ms.

[0107] FCS is defined as the MAC footer and is used for error detection in MAC frames.

[0108] The first three fields (frame control field, interval / identifier field, and address 1 field) and the very last field (FCS field) constitute the minimum frame format and are present in all frames. Other fields may exist only in specific frame types.

[0109] The following describes the network allocation vector (NAV) used in wireless LAN networks.

[0110] As previously mentioned, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, where the AP and / or STA directly senses the medium. Virtual carrier sensing is intended to compensate for problems that may occur in medium access, such as hidden node issues. For virtual carrier sensing, the MAC of a wireless LAN system may utilize NAV. NAV is a value that indicates to other APs and / or STAs the time remaining until the medium becomes available, provided that the AP and / or STA currently using or authorized to use the medium is using the medium. Therefore, the value set as NAV corresponds to the period during which the medium is scheduled to be used by the AP and / or STA transmitting the frame, and the STA receiving the NAV value is prohibited from accessing the medium during that period. NAV can be set, for example, based on the value of the duration field in the MAC header of the frame.

[0111] Figure 6 is a diagram illustrating an example of a NAV setting.

[0112] Referring to FIG. 6, the source STA (source STA, 600) transmits an RTS frame after DIFS, and the destination (610) transmits a CTS frame after SIFS. The destination STA designated as the recipient via the RTS frame does not set the NAV. Some of the remaining STAs (620) receive the RTS frame and set the NAV (630), while others receive the CTS frame and set the NAV (640).

[0113] If a CTS frame (e.g., PHY-RXSTART.indication primitive) is not received within a certain period from the time an RTS frame is received (e.g., when a MAC receives the PHY-RXEND.indication primitive corresponding to the RTS frame), STAs that set or updated the NAV via the RTS frame may reset the NAV (e.g., to 0) (or this case may be referred to as NAVtimeout). The certain period may be (2*aSIFSTime + CTS_Time + aRxPHYStartDelay + 2*aSlotTime), which may be referred to as the NAVtimeout period. CTS_Time may be calculated based on the length and data rate of the CTS frame indicated by the RTS frame.

[0114] In FIG. 6, for convenience, NAV setting or updating is exemplified through an RTS frame or a CTS frame, but NAV setting / resetting / updating may also be performed based on the interval field of various other frames, such as non-HT PPDU, HT PPDU, VHT PPDU, or HE PPDU (for example, the interval field within the MAC header of a MAC frame).

[0115] In addition, 802.11ax introduced basic NAV and intra-BSS NAV. Basic NAV is always set (mandatory) to NAV based on frames transmitted by APs or STAs other than itself, while intra-BSS NAV can be optionally set to NAV based on frames transmitted by the BSS to which it belongs. An AP or STA can access the medium when both NAV timers have expired (or after the NAV time interval has elapsed).

[0116] The following describes TXOP. TXOP (transmission opportunity) was newly introduced in 802.11e MACs to guarantee QoS and increase channel utilization. To guarantee QoS, TXOP can be used to allocate an opportunity for priority transmission when two or more packets belong to the same AC (access category).

[0117] Figure 7 illustrates an example of a TXOP. An STA participating in QoS transmission can obtain a TXOP that allows it to transmit traffic for a certain period using two channel access methods, such as EDCA and HCCA. TXOP acquisition is possible by succeeding in EDCA contention or by receiving a QoS CF-Poll frame from an AP; the former is referred to as an EDCA TXOP, and the latter as a Polled TXOP. In this way, the concept of a TXOP can be used to grant a certain amount of time to any STA to transmit a frame, or to forcibly limit the transmission time.

[0118] The transmission start time and maximum transmission time of a TXOP are determined by the AP, and this is notified to the STA by a beacon frame in the case of an EDCA TXOP, and by a QoS CF-Poll frame in the case of a Polled TXOP.

[0119] NAV can be understood as a type of timer designed to protect the TXOP of a transmitting STA (e.g., a TXOP holder). An STA can protect the TXOPs of other STAs by not performing channel access during the period when the NAV set for it is valid. In current wireless LAN systems, the TXOP duration is set via the duration field of the MAC header. That is, the TXOP holder and the TXOP responder (e.g., an Rx STA) include all the TXOP information necessary for transmitting and receiving frames in the duration field of the frames being exchanged between them. Third-party STAs that are not the TXOP holder or TXOP responder (e.g., third-party STAs) check the duration field of the frames exchanged between the TXOP holder and the TXOP responder, and delay channel usage until the NAV period expires by setting or updating the NAV.

[0120] The primary channel and secondary channel are described below. The primary channel is a common channel operated by all STAs that are members of the BSS. For example, in a 20 MHz, 40 MHz, 80 MHz, 160 MHz, or 80 + 80 MHz BSS, the primary channel may be the primary 20 MHz channel. In this case, the 40 and 80 MHz channels containing the primary 20 MHz channel may be referred to as the primary 40 and 80 MHz channels, respectively, and the primary channel may generally be referred to as the primary 20 MHz channel.

[0121] A secondary channel is a channel associated with a primary channel and is used to create a channel wider than the primary channel. For example, in a 40 MHz, 80 MHz, and 160 MHz BSS, the 40 MHz channel may be the sum of the primary 20 MHz channel and the secondary 20 MHz channel, the 80 MHz channel may be the sum of the primary 40 MHz channel and the secondary 40 MHz channel, and the 160 MHz channel may be the sum of the primary 80 MHz channel and the secondary 80 MHz channel.

[0122] The 802.11be standard is described below. Also known as EHT (extremely high throughput), 802.11be operates across the 2.4, 5, and 6 GHz bands. It is being developed to provide low latency and high network throughput by introducing a 320 MHz wide bandwidth, 4096QAM, multiple resource units (RUs), and multi-link operation (MLO), offering speeds up to 46 Gbps—4.8 times faster than WiFi 6. Specifically, 802.11be provides a 320 MHz wide bandwidth in the 6 GHz band and can transmit data via MU-MIMO, which offers 16 spatial streams in both uplink and downlink. It also achieves high transmission efficiency by adopting 4096QAM. Furthermore, it features enhanced spectrum efficiency by flexibly performing spectrum resource scheduling through multiple RUs, and the ability to simultaneously transmit and receive data across various frequency bands and channels through multi-link operation.

[0123] The following describes TXOP sharing. TXOP sharing is a technology defined in 802.11be, based on the concept of an AP transferring remaining TXOP resources to a STA within a BSS after using the TXOPs it has acquired. An AP can transfer TXOPs to a STA using a multi-user RTS (MU-RTS) TXOP sharing (TXS) trigger frame (TF), specifically the MU-RTS TXS TF, and the STA receiving the TXOP is indicated within the MU-RTS TXS TF. Recently, TXOP sharing between APs has been under research. Through TXOP sharing between APs, an AP holding TXOPs can share the remaining TXOPs with an adjacent AP after using them for traffic processing within its BSS, thereby efficiently utilizing frequency and space resources to increase network throughput and reduce latency. TXOP sharing between APs can be referred to as AP TXOP sharing or Coordinated TDMA (C-TDMA or Co-TDMA).

[0124] In addition to C-TDMA, transmission methods that enhance efficiency and / or reliability through multiple AP (multi-AP, MAP) coordination are being studied. Examples of such multi-AP coordination schemes include C-JT (coordinated joint transmission), C-BF (coordinated beamforming or Co-BF), C-SR (coordinated spatial reuse or Co-SR), C-OFDMA (coordinated orthogonal frequency division multiple access), and CR-TWT (coordinated restricted target wake time or Co-RTWT). Furthermore, a set of APs capable of performing such MAP coordination operations can be referred to as a MAP set.

[0125] Next, we will describe the overlapping basic service set (OBSS). As the number of users increases, the performance of existing wireless LAN networks, such as transmission rates, decreases significantly. This is because wireless LAN systems fundamentally utilize the CSMA / CA method, which corresponds to time division access control; therefore, when an adjacent network is detected, the frequency resources of the same band are shared for the duration of the adjacent network's activity.

[0126] Currently, it is common for multiple APs to operate in specific areas, and in such cases, wireless LAN network performance degradation occurs due to coverage overlap between APs. This is because the APs of each BSS and the STAs connected to them are affected by signals from adjacent BSSs, leading to interference and a reduction in transmission rates caused by collisions between signals transmitted simultaneously. BSSs that can affect signal transmission in this way (or have overlapping coverage) can be referred to as overlapping BSSs (OBSS). To address this problem, interference avoidance techniques are being researched, such as dividing the bandwidth available to each user so that it does not overlap or performing channel switching to unused channels, as well as interference alignment techniques that minimize the impact of interference even when using the same bandwidth.

[0127] FIG. 8 is a diagram illustrating NPCA (non-primary channel access). FIG. 8 illustrates an example in which a wideband channel is configured with a 20 MHz primary channel and a plurality of 20 MHz secondary channels. This is for convenience of explanation and the present disclosure is not limited thereto.

[0128] According to the current 802.11 standard, for any transmission (e.g., transmission on 20, 40, 80, 160, or 320 MHz channels), the primary channel (primary 20 MHz channel) must be idle to access a wideband channel wider than 20 MHz. Therefore, if the primary channel is busy (or occupied), the AP / STA cannot perform transmission on any idle secondary channel. In other words, if the primary channel is busy, transmission cannot be performed on that secondary channel even if it is idle.

[0129] For example, referring to FIG. 8(a) (800), transmission cannot be performed if the primary channel (802) is busy, even if the secondary 20 MHz channel (802) and the secondary 40 MHz channel (806) are available. For example, the primary channel may be busy due to interference by the 20 MHz PPDU (810) corresponding to the OBSS (overlapping BSS), in which case transmission cannot be performed even if the 60 MHz secondary channels (804, 806) are available. Also, for example, the primary channel may be busy due to interference by the 40 MHz PPDU (820) corresponding to the OBSS, in which case transmission cannot be performed even if the 40 MHz secondary channels (806) are available.

[0130] In other words, according to the current 802.11 standard, when the primary channel is idle, the STA can transmit packets. That is, when the primary channel is idle, the STA can perform transmission (e.g., transmission of an 80MHz PPDU) using both the primary and secondary channels. This applies equally to the STA's UL (uplink) transmission as well as the AP's DL (downlink) transmission.

[0131] Therefore, current secondary channel access mechanisms (or schemes) are inefficient for wideband channels (e.g., 160 MHz channels, 320 MHz channels) or large bandwidths, and thus a better secondary channel access mechanism (or scheme) is needed to fully utilize wideband channels.

[0132] NPCA (non-primary channel access) is being discussed as a solution to the aforementioned problem. NPCA can be triggered based on OBSS PPDU and / or OBSS TXOP. According to NPCA, if the primary channel is busy and a secondary channel is available, the AP / STA can transmit frames on the available secondary channel. Hereinafter, NPCA may refer to channel access and / or frame exchange on the secondary channel (when the primary channel is busy).

[0133] Among the secondary channels (or within the secondary channels), an NPCA primary channel (hereinafter interchangeably referred to as NPCA PCH) may be defined. The NPCA primary channel may be a channel where channel access (e.g., EDCA) is performed while the primary channel is busy. That is, the NPCA primary channel may be a 20 MHz channel within the secondary channels where channel access is performed while the primary channel is busy. The NPCA primary channel may be named an anchor channel, but the present disclosure is not limited to this specific designation.

[0134] For example, referring to FIG. 8(b) (850), when the primary channel is busy, transmission can be performed on available secondary channels. For example, when the primary channel (852) is busy due to interference by a 20 MHz PPDU (860) associated with OBSS, the STA can transmit packets (e.g., 60 MHz PPDU, 862) on available secondary channels (854, 856) while the primary channel is busy. Channel access can be performed on an anchor channel within the secondary channels, and accordingly, when the anchor channel is idle, packets can be transmitted on the secondary channels. This applies equally to UL transmission of the STA as well as DL transmission of the AP.

[0135] For example, if the primary channel is busy due to interference by a 40 MHz PPDU (870) associated with OBSS, the STA can transmit packets (e.g., 40 MHz PPDU, 872) on available secondary channels (856) while the primary channel is busy. Channel access can be performed on an anchor channel within the secondary channels, and accordingly, packets can be transmitted on the secondary channels when the anchor channel is idle. This applies equally to UL transmission of the STA as well as DL transmission of the AP.

[0136] In the description of one embodiment of the present disclosure, NPCA AP may mean an AP having the capability to perform NPCA (or an AP capable of performing / performing an action related to NPCA), and NPCA STA may mean an STA associated with NPCA AP that has the capability to perform NPCA (or a STA capable of performing / performing an action related to NPCA). Unless specifically stated otherwise, AP, NPCA AP, STA, and NPCA STA may be used interchangeably in the present disclosure.

[0137] Between the NPCA APs and / or NPCA STAs within the BSS, secondary channels on which NPCA operates and anchor channels (e.g., 20 MHz anchor channels) for performing channel access (e.g., EDCA) procedures within the secondary channels may be pre-configured / pre-agreed upon. The secondary channels on which NPCA operates may be named NPCHs (non-primary channels), but the present disclosure is not limited to these specific names.

[0138] Certain APs and STAs may have the ability to perform both NPCA and MAP operations (for example, C-TDMA is described primarily below, but the MAP operations of the present disclosure are not limited to C-TDMA).

[0139] FIG. 9 is a diagram illustrating an example of the operation of an AP capable of performing both NPCA and C-TDMA operations.

[0140] According to FIG. 9, a sharing AP (or coordinating AP) (900) may initiate its own TXOP by, for example, transmitting a MAP ICF (multi-AP initial control frame, 910). In the example of FIG. 9, it is assumed that the PCH of the sharing AP and the shared AP (or coordinated AP) are the same, but the present disclosure is not limited by this example. If the first frame transmitted in the TXOP is a control frame, that frame may be an ICF. The shared AP that receives the MAP ICF may respond to the ICF via an ICR (initial control frame response, 912). At this time, the sharing AP may perform frame exchange with the associated STAs in the TXOP it occupies (914) and transmit a TXS TF (916) that triggers TXOP sharing. The shared AP that receives the above TXS TF responds to the TXS TF via an IR (immediate response, transmits a frame after a predetermined time (e.g., SIFS), 920), and can then perform frame exchange with the STAs associated with the shared AP in the shared TXOP (918) (922).

[0141] In this case, if the shared AP and the STAs associated with the shared AP can perform NPCA, the shared AP and the STAs associated with the shared AP can perform NPCA for the efficient use of resources during the sharing AP's TXOP. The shared AP and the STAs associated with the shared AP can move to the NPCA PCH to perform NPCA, and in this case, even if the sharing AP shares the TXOP, the shared AP and the STAs associated with the shared AP cannot use the shared TXOP, so inefficiency in resource usage may occur.

[0142] In this regard, where C-TDMA can be used, a method may be required to notify the shared AP and the STAs associated with the shared AP that TXOP sharing may be performed. For example, in the case of FIG. 9, the MAP ICF (910) may include information indicating that the sharing AP intends to share the sharing AP's TXOP with the shared AP. The shared AP that receives the MAP ICF may respond to the intention to share the sharing AP's TXOP via the ICR (912). For example, the shared AP may transmit information including an intention to receive the shared TXOP to the ICR.

[0143] Additionally, the MAP ICF (910) may contain information about a shared AP capable of receiving a shared TXOP, and the information about the shared AP may be included in the user info field or / and the RA (receiver address) field. For example, the AID field of the user info field may be set to the AID information assigned by the sharing AP to the shared AP, or the RA field may be set to the MAC address of the shared AP. The shared AP can check the RA field and confirm that if the RA field is set to its own MAC address, the MAP ICF indicates that the sharing AP intends to share the TXOP with it. In this case, the shared AP may not check the AID of the user info field. Alternatively, if the RA field is set to broadcast, the shared AP can check the user info field and confirm that if the AID of the user info field is set to the AID assigned to it, the MAP ICF indicates that the sharing AP intends to share the TXOP with it. Alternatively, the shared AP may check both fields or perform an action of checking one of the two fields.

[0144] For example, a BSRP (buffer status report poll) trigger frame may be used as the MAP ICF, and a multi-STA block ack (M-BA) may be used as the ICR responding to the MAP ICF. The MAP ICF may further include information about the TXOP to be shared, such as at least one piece of information including the time when the sharing AP transfers the TXOP or the length of the TXOP to be transferred.

[0145] In this case, the shared AP and the STAs associated with the shared AP may choose not to perform NPCA for the sake of TXOP sharing, even if NPCA is possible. Alternatively, the shared AP and the STAs associated with the shared AP may choose to forgo TXOP sharing and perform NPCA if they deem that performing NPCA is more effective. In other words, the shared AP's intention to share TXOPs may not restrict the actions of the shared AP and the associated STAs.

[0146] FIG. 10 is a diagram illustrating an example of the operation of an AP capable of performing both NPCA and C-BF operations. C-BF is a technology that allows multiple APs to form a beam to concentrate power in a specific direction and transmit to one or more STAs, thereby reducing the impact of interference on adjacent APs and STAs and enabling more effective transmission. For example, if a sharing AP and a shared AP perform C-BF, each AP can transmit frames to the STAs associated with it, and each AP can transmit frames using a beam that minimizes the impact on each other.

[0147] According to FIG. 10, the sharing AP (1000) transmits a MAP-ICF (1010) and occupies a TXOP. The shared AP (1002) can respond to the MAP-ICF by transmitting an ICR (1012). At this time, the sharing AP and the shared AP can simultaneously transmit DL PPDU (1014, 1016) respectively within the TXOP occupied by the sharing AP. At this time, the sharing AP and the shared AP can transmit PPDUs to each other through beamforming, for example, to increase the reliability of transmission by transmitting the same PPDU to the same STA, or to minimize interference to different STAs.

[0148] In this case, if the shared AP and the STAs associated with the shared AP can perform NPCA, the shared AP and the STAs associated with the shared AP can perform NPCA for the efficient use of resources during the shared AP's TXOP. The shared AP and the STAs associated with the shared AP can move to the NPCA PCH to perform NPCA, and in this case, since the shared AP cannot perform C-BF, inefficiency in resource usage may occur.

[0149] In this regard, when C-BF can be used, a method may be required to notify the shared AP and the STAs associated with the shared AP that C-BF can be performed. For example, in the case of FIG. 10, the MAP ICF (1010) may include information indicating that the sharing AP intends to the shared AP that the sharing AP's C-BF can be performed. The shared AP that receives the MAP ICF may respond to the intention to perform the sharing AP's C-BF via the ICR (1012). For example, the shared AP may transmit information including an intention to perform C-BF to the ICR.

[0150] In this case, the shared AP and the STAs associated with the shared AP may choose not to perform the NPCA in order to perform the C-BF, even if performing the NPCA is possible. Alternatively, the shared AP and the STAs associated with the shared AP may choose to forgo performing the C-BF and perform the NPCA if they deem that performing the NPCA is more effective. In other words, the shared AP's intention to perform the C-BF may not restrict the actions of the shared AP and the associated STAs.

[0151] In Figures 9 and 10 above, C-TDMA and C-BF were cited as examples of MAP coordination schemes, but the content of the present disclosure is not limited by the above examples and can be applied to various MAP coordination schemes.

[0152] Below, various methods are described, including an example illustrated in FIGS. 9 and 10, that indicate that a sharing AP can perform MAP coordination operations. Below, a method is described that indicates that a sharing AP can perform MAP coordination operations, using the case of C-TDMA as an example. As shown in FIGS. 9 and 10, the TXOP of a sharing AP capable of MAP coordination operations is referred to as a MAP TXOP.

[0153] For example, consider the case where a MAP TXOP is initiated by a non-MAP ICF. In this case, the MAP TXOP may be initiated by a trigger frame (TF), and the non-MAP ICF or TF may not contain information about the shared AP. This trigger frame may be one of the existing trigger frames or a newly defined trigger frame. In this case, the sharing AP may include information in the trigger frame indicating that the TXOP is a MAP TXOP. Below, an example is described in which information indicating that the TXOP is a MAP TXOP is included in the trigger frame.

[0154] FIG. 11a is a drawing illustrating an example of a trigger frame format. According to FIG. 11a, the trigger frame format may include a common info field (1100) of 8 octets or more and a user info list (1102) of adjustable length.

[0155] FIG. 11b illustrates an example of an EHT variant common info field format. According to FIG. 11b, the EHT variant common info field includes three 1-bit reserved fields (1120). A shared AP may indicate that a TXOP is a MAP TXOP using at least one of the three 1-bit reserved fields, and additionally, it may indicate that a TXOP is a MAP TXOP using at least one of the reserved fields added according to the type of TF. For example, the field may be referred to as a MAP TXOP field, and if set to 1, it indicates that the TXOP of the sharing AP is a MAP TXOP, and if set to 0, it indicates that it is not a MAP TXOP. Alternatively, the reverse is also possible, and the present disclosure is not limited by such an example. Furthermore, even if it is not an EHT variant common info field, a reserved field of another common info field format may be used in this manner.

[0156] For example, the reserved field of the common info field may be used for other purposes. In this case, one or more bits of the reserved field of the special user info field format may be used as a MAP TXOP field. FIG. 11c is a diagram illustrating an example of the special user info field format. According to FIG. 11c, the special user info field format includes a 3-bit reserved field (1140), and if one or more of the reserved field is used as a MAP TXOP field and is set to 1, it indicates that the TXOP of the sharing AP is a MAP TXOP, and if it is 0, it indicates that it is not a MAP TXOP. Alternatively, the reverse is also possible, and the present disclosure is not limited by such an example. The special user info field is a user info field in which the AID12 field is set to 2007, and may correspond to a field for multiple users. In addition to the special user info field, the reserved field of a field for multiple users may be used as a MAP TXOP field.

[0157] Alternatively, the MAP TXOP field may be included in the special user info field format even if the reserved field exists in the common info field format. Alternatively, it is possible for both the common info field format and the special user info field format to include the MAP TXOP field.

[0158] For example, consider the case where the MAP TXOP starts with ICF rather than TF. The said ICF may have a corresponding ICR, for example, the ICF may be RTS and the ICR may be CTS. The sharing AP may use one or more unused bits of the frame control field of the ICF as the MAP TXOP field. For example, the ICF may have a MAC frame format such as FIG. 5, where the frame control field may have various formats. In this case, for example, if at least one of the more fragments, retry, and power management subfields is unused, it may be used as the MAP TXOP field, but the present disclosure is not limited by such examples. If the said unused field is used as the MAP TXOP field and is set to 1, it indicates that the TXOP of the sharing AP is a MAP TXOP, and if it is 0, it indicates that it is not a MAP TXOP.

[0159] If the responder who received the above TF supports 802.11bn or 802.11 UHR (ultra high reliability), when the responder transmits an ICR, the same field can also be used as the MAP TXOP field to indicate that the MAP TXOP of the ICF has been verified.

[0160] FIG. 12 illustrates an example of the operation of an AP when the MAP TXOP field is included in the ICF. FIG. 12 illustrates an example where 1 bit of the power management (PM) field is used as the MAP TXOP field. According to FIG. 12, in (a) (1200), the OBSS AP transmits the ICF by setting the PM field of the ICF (1210) to 0 in the PCH of the corresponding AP, and the corresponding AP receives the ICF. At this time, the response ICR of the ICF may also have the PM field set to 0 (1212). The ICR may be transmitted by the STA associated with the OBSS AP. At this time, the PM field 0 may indicate that the TXOP of the OBSS is not a MAP TXOP. Since the TXOP is not shared and is used by the OBSS AP, the OBSS AP performs PPDU transmission and reception with the associated STAs in its own TXOP (1214). Subsequently, BA (block acknowledgment, block ACK, 1216), which is acknowledgment information corresponding to the above PPDU, can be transmitted and received. That is, the TXOP of the OBSS AP is not shared, and at this time, an AP that receives an ICF indicating that it is not a MAP TXOP (though not shown) can perform NPCA and transmit and receive frames with the STAs associated with it in the NPCA PCH.

[0161] (b)(1250) illustrates an example where the PM field is set to 1. In the PCH of the corresponding AP, the OBSS AP (i.e., the sharing AP) transmits an ICF with the PM field set to 1 (1260). The PM field may indicate that the TXOP starting with the ICF is a MAP TXOP. Subsequently, the ICR, which is the response to the ICF, may also have the PM field set to 1 (1262). The ICR may be transmitted by the STA associated with the OBSS AP. Subsequently, the OBSS AP performs PPDU transmission and reception with the associated STAs in its TXOP (1264). Subsequently, a BA (1266), which is acknowledgment information corresponding to the PPDU, may be transmitted and received. Subsequently, the OBSS AP transmits a control frame indicating C-TDMA (1268), and the corresponding AP receives the control frame. The above control frame may be, for example, a multi-user RTS (MU-RTS) TXOP sharing (TXS) trigger frame (TF), but the present disclosure is not limited thereto. The control frame indicates the sharing of a TXOP of a sharing AP, and the shared AP responds by transmitting an IR to the control frame (1270). Subsequently, the AP can perform frame exchange with the STAs associated with it at the shared TXOP (1272).

[0162] For example, consider the case where a MAP TXOP is initiated by a HE, EHT, or UHR PPDU. Since the NPCA operation is triggered by a frame exchange of the OBSS or by a HE, EHT, or UHR PPDU, the PPDU in the above case is considered in this disclosure. Here, the PPDU may refer to a frame for transmitting a packet. In this case, whether the TXOP is a MAP TXOP or not must be indicated by the PHY header. The SIG (or signal) field (or HE-SIG-A or U-SIG field) included in the PHY header of FIG. 5 includes a plurality of fields, and through at least one of the plurality of fields, it may be indicated that the TXOP transmitted by the corresponding PPDU is a MAP TXOP. For example, if the TXOP field included in HE-SIG-A or U-SIG is set to 127, the duration of the TXOP is defined as not being indicated. In this case, for example, the sharing AP may use a specific value of the TXOP field (e.g., 127) to indicate that the TXOP (starting with the PPDU) is a MAP TXOP. This technique is merely an example, and the present disclosure is not limited by this technique. As described above, an unused value of one of the multiple fields included in the SIG field may indicate that the TXOP is a MAP TXOP.

[0163] Alternatively, the sharing AP may use at least one of the unused bits of the U-SIG field included in the EHT PPDU or UHR PPDU as a MAP TXOP field. For example, the five bits from B20 to B24 of the U-SIG field format are designated as disregard bits and can all be set to 1. The sharing AP may indicate that the TXOP is a MAP TXOP by using at least one of the bits as a MAP TXOP field and setting it, for example, to 1 or 0. Such techniques are merely examples, and the present disclosure is not limited by such techniques.

[0164] The following describes the operation when an AP and STA capable of performing NPCA receive information indicating that they can perform MAP coordination operations. Using the case of C-TDMA as an example, the method of announcing that a sharing AP can perform MAP coordination operations is described below. As shown in Figures 9 and 10, the TXOP of a sharing AP capable of MAP coordination operations is referred to as a MAP TXOP.

[0165] For example, consider the case where an AP and a STA capable of performing NPCA receive a MAP ICF. The sharing AP transmits a MAP ICF that initiates a TXOP, and the MAP ICF may include information indicating that the TXOP occupied by the sharing AP is a MAP TXOP. Additionally, the MAP ICF may include information about a shared AP capable of receiving the TXOP.

[0166] The AP that receives the above MAP ICF checks whether the TA field of the MAC header of the MAP ICF is set to the MAC address of the sharing AP. If so, it checks whether the RA field is set to the MAC address that the sharing AP identifies itself, or whether the information in the user info field (e.g., AID12) is set to the AID or information that the sharing AP identifies itself. In other words, this process can be understood as a process of verifying whether the MAP ICF has been received from the sharing AP and whether the sharing AP has set the corresponding AP as an AP capable of sharing TXOPs. At this time, a set of APs capable of performing a MAP coordination scheme (MAP set) may be pre-configured, and through the MAP set configuration process, the MAC addresses of the APs and which AID each AP has set for neighboring APs can be shared among the APs included in the MAP set. If the TA of the MAP ICF is set to the MAC address of the sharing AP and the AID in user info corresponds to the AP that received the MAP ICF, the AP that received the MAP ICF can wait for a MAP control frame (e.g., MU-RTS TXS TF) to share a TXOP without performing NPCA (i.e., without moving to the NPCA PCH). If the TA of the MAP ICF is not set to the MAC address of the sharing AP, or if the AID in user info or the RA of the MAP ICF does not correspond to the AP that received the MAP ICF, the AP that received the MAP ICF can perform NPCA.

[0167] The STA that receives the above MAP ICF checks whether the TA field of the MAC header of the MAP ICF is set to the MAC address of the sharing AP. If so, it checks whether the RA field is set to the MAC address indicating the AP associated with the sharing AP, or whether the information in the user info field (e.g., AID12) is set to the AID or information indicating the AP associated with the sharing AP. In other words, this process can be understood as a process of checking whether the MAP ICF was received from the sharing AP and whether the sharing AP has set the AP associated with it as an AP capable of sharing TXOPs. At this time, a set of APs capable of performing a MAP coordination scheme (MAP set) may be pre-configured, and through the MAP set configuration process, the MAC addresses of the APs and the AID to which each AP has set the surrounding AP can be shared among the APs included in the MAP set and shared with the STAs associated with the said APs. If the TA of the MAP ICF is set to the MAC address of the sharing AP and the AID or RA field in the user info corresponds to the AP associated with the STA, the STA that received the MAP ICF may not perform NPCA (i.e., may not move to the NPCA PCH). If the TA of the MAP ICF is not set to the MAC address of the sharing AP or the AID or RA field in the user info does not correspond to the AP that received the MAP ICF, the STA that received the MAP ICF may perform NPCA.

[0168] For example, consider the case where a MAP TXOP is initiated by a non-MAP ICF, and an AP and STA capable of performing NPCA receive the non-MAP ICF. In this case, the MAP TXOP may be initiated by a TF, and the non-MAP ICF or TF may not contain information about the shared AP. In this case, the sharing AP may include information in the trigger frame indicating that the TXOP is a MAP TXOP, as described above. Alternatively, consider the case where the MAP TXOP is initiated by an ICF other than a TF. The ICF may contain a corresponding ICR; for example, the ICF may be an RTS and the ICR may be a CTS. In this case, the sharing AP may include information in the frame control field of the ICF indicating that the TXOP is a MAP TXOP, as described above.

[0169] The AP and STA that receive the above ICF check whether the TA field of the ICF's MAC header is set to the MAC address of the AP included in the MAP set. In other words, this process may correspond to a procedure to verify whether the ICF has been received from an AP included in the MAP set. If so, the AP and STA determine whether the TXOP corresponds to a MAP TXOP according to the method described above. This method can be performed based on the MAP TXOP field described above. If it is determined that the TXOP corresponds to a MAP TXOP, the AP that received the ICF may wait for a MAP control frame (e.g., MU-RTS TXS TF) to share the TXOP without performing NPCA (i.e., without moving to the NPCA PCH). Likewise, if it is determined that the TXOP corresponds to a MAP TXOP, the STA that received the ICF does not perform NPCA (i.e., does not move to the NPCA PCH). If the above conditions are not satisfied, AP and STA can perform NPCA.

[0170] FIG. 13 illustrates an example of operation when an AP and a STA capable of performing NPCA receive an ICF. An example is shown in which 1 bit of the power management (PM) field is used in the MAP TXOP field of the ICF. According to FIG. 13, in (a) (1300), the OBSS AP transmits the ICF by setting the PM field of the ICF (1310) to 0 in the PCH of the corresponding AP, and the corresponding AP receives the ICF. At this time, the response ICR of the ICF may also have the PM field set to 0 (1312). The ICR may be transmitted by the STA associated with the OBSS AP. At this time, the PM field 0 may indicate that the TXOP of the OBSS is not a MAP TXOP. Since the TXOP is not shared and is used by the OBSS AP, the OBSS AP performs PPDU transmission and reception with the associated STAs in its own TXOP (1314). Afterwards, BA (1318), which is acknowledgment information corresponding to the above PPDU, can be transmitted and received.

[0171] At this time, since the AP can perform NPCA, it can perform the channel connection procedure after t1 from the start of ICR (1312) transmission (for example, t1 may be aRxPHYStartDelay + channel switching time. aRxPHYStartDelay is the delay for the physical layer to transmit that reception has started to the upper layer, and may vary depending on the AP's configuration. Channel switching time is the time for the AP to move to the NPCA PCH) and occupy the NPCA TXOP in the NPCA PCH (1316). The NPCA TXOP must be terminated before t2, when the OBSS TXOP is terminated (for example, t2 may be the channel switchback time. This is the time for the AP to return to the PCH). That is, the AP can transmit and receive frames with the STAs associated with it in the NPCA TXOP.

[0172] (b)(1350) illustrates an example where the PM field is set to 1. In the PCH of the corresponding AP, the OBSS AP (i.e., the sharing AP) transmits an ICF with the PM field set to 1 (1360). The PM field may indicate that the TXOP starting with the ICF is a MAP TXOP. Subsequently, the ICR, which is the response to the ICF, may also have the PM field set to 1 (1362). The ICR may be transmitted by the STA associated with the OBSS AP and / or the corresponding AP. Subsequently, the OBSS AP performs PPDU transmission and reception with the associated STAs in its TXOP (1364). Subsequently, a BA (1366), which is acknowledgment information corresponding to the PPDU, may be transmitted and received. Subsequently, the OBSS AP transmits a control frame indicating C-TDMA (1368), and the corresponding AP receives the control frame. The above control frame may be, for example, a multi-user RTS (MU-RTS) TXOP sharing (TXS) trigger frame (TF), but the present disclosure is not limited thereto. The control frame indicates the sharing of a TXOP of a sharing AP, and the AP responds by transmitting an IR to the control frame (1370). Subsequently, the AP may perform frame exchange with STAs associated with itself on the shared TXOP (1372).

[0173] For example, consider the case where a MAP TXOP is initiated by an HE, EHT, or UHR PPDU, and an NPCA-capable AP and STA receive the PPDU. In this case, whether the TXOP is a MAP TXOP or not is indicated in the PHY header by the method described above.

[0174] The AP and STA that receive the above PPDU check whether the BSS color field of the PPDU is set to the BSS color of an AP included in the MAP set. At this time, a set of APs capable of performing a MAP coordination scheme (MAP set) may be pre-configured, and through the MAP set configuration process, the BSS colors of the APs may be shared among the APs included in the MAP set and shared with the STAs associated with said APs. If the BSS color of the PPDU is set to the BSS color of an AP included in the MAP set, the AP and STA that receive the above PPDU can determine whether the TXOP corresponds to a MAP TXOP using the method described above. If the TXOP is a MAP TXOP, the AP that receives the above PPDU may wait for a MAP control frame (e.g., MU-RTS TXS TF) to share the TXOP without performing NPCA (i.e., without moving to the NPCA PCH). If the above condition is not satisfied, the AP and STA may perform NPCA.

[0175] FIG. 14 illustrates an example of operation when an AP and a STA capable of performing NPCA receive a PPDU. According to FIG. 14, in (a) (1400), the OBSS AP at the PCH of the corresponding AP sets a specific PHY field of the OBSS PPDU (1410) to indicate that the TXOP is not a MAP TXOP according to the method described above and transmits it. Upon receiving the PPDU, the corresponding AP determines whether the OBSS TXOP is a MAP TXOP according to the method described above, and if the OBSS TXOP is not a MAP TXOP, it moves to the NPCA PCH and can perform NPCA. If the corresponding AP succeeds in the channel connection procedure, the AP occupies the NPCA TXOP (1412). The OBSS AP transmits and receives PPDUs and BAs corresponding to the transmission and reception of PPDUs with the associated STAs at its TXOP (1414, 1416, 1418).

[0176] (b)(1450) At the PCH of the corresponding AP, the OBSS AP transmits the OBSS PPDU (1460) by setting a specific PHY field to indicate that the TXOP corresponds to a MAP TXOP according to the method described above. Upon receiving the PPDU, the corresponding AP determines whether the OBSS TXOP is a MAP TXOP according to the method described above, and if the OBSS TXOP corresponds to a MAP TXOP, it does not perform NPCA and waits for a C-TDMA control frame. Upon receiving a C-TDMA control frame (1464) from the OBSS AP indicating that the TXOP is shared, the corresponding AP transmits an IR in response (1466) and can perform frame exchange with the STAs associated with itself on the shared TXOP (1468).

[0177] Before the method performed in the present disclosure is executed, a MAP set, which is a set of APs capable of performing a MAP coordination scheme, may be set or established. Through the process of setting the MAP set or / and subsequently transmitting and receiving information, the MAP coordination schemes supported by the APs included in the MAP set, the operating bandwidths of the APs, the MAC addresses of the APs, information on which AID the APs have set to neighboring APs, and the BSS colors of the APs may be shared among the APs included in the MAP set. Additionally, whether the APs support NPCA and DSO (dynamic subband operation), etc., may also be shared. Furthermore, at least one of the above information may be shared with STAs associated with the APs.

[0178] FIG. 15 is a diagram illustrating an example of the operation of an AP performing an embodiment of the present disclosure. The AP of FIG. 15 may be an AP that receives a frame transmitted from the TXOP of an OBSS AP.

[0179] The AP receives an OBSS frame (or OBSS PPDU) (1500). The AP checks whether the received PPDU corresponds to an ICF (1505). If the received PPDU corresponds to an ICF, the AP determines whether the PPDU was received from an AP included in the MAP set based on the TA field of the PPDU (1515). If the PPDU was received from an AP included in the MAP set, the AP determines whether the PPDU corresponds to a trigger frame (1520). If the PPDU was not received from an AP included in the MAP set, the AP can perform NPCA (1545).

[0180] If the PPDU corresponds to a trigger frame, the AP determines whether the PPDU corresponds to a MAP ICF (1525). If so, the AP checks the user info field or RA field of the MAP ICF to determine whether the user info or RA is for the AP (1530). If the user info or RA is not for the AP, the AP can perform NPCA (1580). If the user info or RA is for the AP, the AP can determine whether to perform a MAP operation or an NPCA operation, or to determine whether to prefer a MAP operation (1590). If the AP prefers a MAP operation, the AP waits for a MAP control frame, which may be, for example, a MU-RTS TXS TF. Afterward, the AP can perform a MAP operation (1585). If the AP does not prefer a MAP operation, the AP can perform NPCA (1580).

[0181] If, at step 1525, the AP determines that the PPDU does not correspond to a MAP ICF, the AP can determine whether the TXOP of the OBSS is a MAP TXOP based on the MAP TXOP field included, for example, in the common info field or the special user info field (1555). Also, if, at step 1520, the AP determines that the PPDU is not a trigger frame, the AP can determine whether the TXOP of the OBSS is a MAP TXOP based on the MAP TXOP field of the frame control field, for example (1550). In this case, if the OBSS TXOP is not a MAP TXOP, the AP can perform NPCA (1580). If the OBSS TXOP corresponds to a MAP TXOP, the AP can determine whether to perform a MAP operation or an NPCA operation. Or it can determine whether to prefer a MAP operation (1590). If the AP prefers a MAP operation, the AP waits for a MAP control frame, which may be, for example, a MU-RTS TXS TF. Afterwards, the AP can perform a MAP operation (1585). If the AP does not prefer a MAP operation, the AP can perform an NPCA (1580).

[0182] If the AP determines in step 1505 that the PPDU is not an ICF, the AP determines whether the PPDU is an HE, EHT, or UHR PPDU (1535). If the PPDU is not an HE, EHT, or UHR PPDU, the AP performs NPCA (1580). If the PPDU is an HE, EHT, or UHR PPDU, the AP checks the BSS color of the received PPDU (1540) and, based on the BSS color, determines whether the PPDU was received from an AP belonging to the MAP set (1565). If so, the AP checks the TXOP information included in the PHY header (e.g., the SIG or U-SIG field) or a separately defined MAP TXOP bit (1570) to determine whether the OBSS TXOP is a MAP TXOP (1575). If the OBSS TXOP is a MAP TXOP, the AP can determine whether to perform a MAP operation or an NPCA operation. Alternatively, it can determine whether it prefers a MAP operation (1590). If the AP prefers a MAP operation, the AP waits for a MAP control frame, which may be, for example, a MU-RTS TXS TF. Afterward, the AP can perform a MAP operation (1585). If the AP does not prefer a MAP operation, the AP can perform an NPCA (1580). If the PPDU is not received from an AP belonging to the MAP set, the AP can perform an NPCA (1580).

[0183] The flowcharts described above illustrate exemplary methods that may be implemented in accordance with the principles of the present disclosure, and various modifications may be made to the methods illustrated in the flowcharts of this specification. For example, although they are illustrated as a series of steps, the various steps in each figure may overlap, occur in parallel, occur in a different order, or occur multiple times. In other examples, steps may be omitted or replaced with other steps. The values ​​described above are merely examples, and it is fully possible to apply other values.

[0184] FIG. 16 illustrates an example of the operation of an AP capable of sharing a TXOP. According to FIG. 16, the AP acquires a TXOP through a channel access procedure (1600). If the AP performs a MAP operation on the acquired TXOP (1610), the AP indicates that the acquired TXOP is a MAP TXOP (1620). The indication may be performed through the method described in the present disclosure. If the AP does not perform a MAP operation on the acquired TXOP (1610), the AP indicates that the acquired TXOP is not a MAP TXOP (1630). The indication may be performed through the method described in the present disclosure.

[0185] The flowcharts described above illustrate exemplary methods that may be implemented in accordance with the principles of the present disclosure, and various modifications may be made to the methods illustrated in the flowcharts of this specification. For example, although they are illustrated as a series of steps, the various steps in each figure may overlap, occur in parallel, occur in a different order, or occur multiple times. In other examples, steps may be omitted or replaced with other steps. The values ​​described above are merely examples, and it is fully possible to apply other values.

[0186] FIG. 17 illustrates an example of the operation of an AP that can receive an instruction from an OBSS AP as to whether a TXOP is a MAP TXOP. According to FIG. 17, the OBSS AP acquires a TXOP (1700) and can transmit a frame indicating whether a MAP operation will be performed on the TXOP (i.e., whether the TXOP is a MAP TXOP) (1710). The method of indicating whether a MAP operation will be performed on the TXOP (i.e., whether the TXOP is a MAP TXOP) may follow the method described above. The AP that receives the frame determines whether it can become a shared AP based on the frame (1720). The determination method may follow the method described above. For example, the AP determines that it can become a shared AP if the frame transmitted by the OBSS AP includes an instruction to share the TXOP with it.

[0187] If the AP determines that it is a candidate for a shared AP, the AP determines whether it prefers a MAP operation over an NPCA (1730). If so, the AP waits for a MAP control frame (without performing an NPCA operation) and performs a MAP operation upon receiving a MAP control frame (1740). If the AP determines that it is not a candidate for a shared AP, the AP may perform an NPCA operation (1750). Also, if a MAP operation is not performed on a TXOP (i.e., if it is indicated that the TXOP is not a MAP TXOP, 1710), the AP may perform an NPCA operation (1750).

[0188] The flowcharts described above illustrate exemplary methods that may be implemented in accordance with the principles of the present disclosure, and various modifications may be made to the methods illustrated in the flowcharts of this specification. For example, although they are illustrated as a series of steps, the various steps in each figure may overlap, occur in parallel, occur in a different order, or occur multiple times. In other examples, steps may be omitted or replaced with other steps. The values ​​described above are merely examples, and it is fully possible to apply other values.

[0189] FIG. 18 illustrates an example of the operation of an STA that can receive an instruction from an OBSS AP regarding whether a TXOP is a MAP TXOP. According to FIG. 18, the OBSS AP acquires a TXOP (1800) and can transmit a frame indicating whether a MAP operation will be performed on the TXOP (i.e., whether the TXOP is a MAP TXOP) (1810). The method of indicating whether a MAP operation will be performed on the TXOP (i.e., whether the TXOP is a MAP TXOP) may follow the method described above. The STA that receives the frame determines whether the AP associated with it can become a shared AP based on the frame (1820). The determination method may follow the method described above. For example, the STA determines that the AP associated with it can become a shared AP if the frame transmitted by the OBSS AP includes an instruction to share the TXOP with the AP associated with it.

[0190] If the STA determines that the AP it is associated with is a shared AP candidate, the STA determines whether it prefers a MAP operation over NPCA (1830). If so, the STA remains in the PCH (without performing the NPCA operation, i.e., without moving to the NPCA PCH) (1840). If the STA determines that the AP it is associated with is not a shared AP candidate, the STA may perform the NPCA operation (1850). That is, the STA may move to the NPCA PCH and prepare for the NPCA operation. Also, if the MAP operation is not performed on the TXOP (i.e., if it is indicated that the TXOP is not a MAP TXOP, 1810), the STA may perform the NPCA operation (1850).

[0191] The flowcharts described above illustrate exemplary methods that may be implemented in accordance with the principles of the present disclosure, and various modifications may be made to the methods illustrated in the flowcharts of this specification. For example, although they are illustrated as a series of steps, the various steps in each figure may overlap, occur in parallel, occur in a different order, or occur multiple times. In other examples, steps may be omitted or replaced with other steps. The values ​​described above are merely examples, and it is fully possible to apply other values.

[0192] Meanwhile, the embodiments of the present disclosure disclosed in this specification and drawings are merely specific examples provided to facilitate the explanation of the technical content of the present disclosure and to aid in understanding the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it is obvious to those skilled in the art that other variations based on the technical concept of the present disclosure are possible. Furthermore, each of the above embodiments may be combined and operated together as needed. For example, parts of one embodiment of the present disclosure and another embodiment may be combined to operate AP and STA.

[0193] Meanwhile, the order of description in the drawings explaining the method of the present invention does not necessarily correspond to the order of execution, and the order of precedence may be changed or executed in parallel. Alternatively, the drawings explaining the method of the present invention may omit some components and include only some components to the extent that the essence of the present invention is not compromised.

Claims

1. A method performed by an electronic device corresponding to a first AP (access point) of a wireless LAN network, Step of acquiring a TXOP (transmission opportunity); A step of transmitting a frame including information indicating whether the above TXOP corresponds to a MAP TXOP capable of performing a MAP (multi-AP) coordination operation; and A method characterized by including the step of performing frame exchange with associated STAs (stations) in the above TXOP.

2. In Paragraph 1, If the above frame corresponds to a MAP ICF (initial control frame), the MAP ICF includes information that the TXOP corresponds to the MAP TXOP and information about a second AP that will share the TXOP, and A method characterized in that, when the above frame is not the MAP ICF but corresponds to a trigger frame, at least one bit of the reserved field of the common info field or special user info field of the trigger frame indicates whether the TXOP corresponds to the MAP TXOP.

3. In Paragraph 1, A method characterized in that, when the above frame corresponds to an ICF that is not a trigger frame, a specific value of a specific field of the frame control field of the above ICF indicates whether the above TXOP corresponds to the above MAP TXOP.

4. In Paragraph 1, A method characterized by, when the above frame corresponds to a PPDU (physical layer protocol data unit) for packet transmission, a specific value of a specific field of the PHY header of the above PPDU indicating whether the above TXOP corresponds to the above MAP TXOP.

5. A method performed by an electronic device corresponding to a second AP (access point) of a wireless LAN network, Step of receiving a frame from an OBSS (overlapping basic service set) AP; A step of determining whether the TXOP occupied by the OBSS AP included in the frame corresponds to the MAP TXOP based on information indicating whether the TXOP corresponds to the MAP TXOP capable of performing a MAP (multi-AP) coordination operation; and A method characterized by including a step of performing an operation to switch to or not switch to NPCA (non-primary channel access) PCH (primary channel) based on the above judgment.

6. In Paragraph 5, If the above frame corresponds to a MAP ICF, a step of determining whether the TA (transmitter address) field of the MAP ICF is the MAC (media access control) address of an AP included in a MAP set, which is a set of APs capable of performing the MAP coordination operation; If the above TA field corresponds to the MAC address of an AP included in the above MAP set, a step of determining whether the MAC address in the AID (association ID) or RA (receiver address) field within the user info field of the above MAP ICF corresponds to the above second AP; and A method characterized by performing an operation to wait for the reception of a MAP control frame transmitted by the OBSS AP without switching to the NPCA PCH if the above AID corresponds to the above 2 AP.

7. In Paragraph 5, If the above frame corresponds to a trigger frame that is not a MAP ICF or an ICF that is not a trigger frame, a step of determining whether the TA field of the above frame is the MAC address of an AP included in a MAP set, which is a set of APs capable of performing the MAP coordination operation; If the above TA field corresponds to the MAC address of the AP included in the above MAP set, a step of determining whether the above TXOP corresponds to the above MAP TXOP based on the information included in the above frame; and A method characterized by performing an operation to wait for reception of a MAP control frame transmitted by the OBSS AP without switching to the NPCA PCH if the above TXOP corresponds to the above MAP TXOP.

8. In Paragraph 5, If the above frame corresponds to a PPDU (physical layer protocol data unit) for packet transmission, a step of determining whether the BSS color field included in the PPDU is set to the BSS color of an AP included in a MAP set, which is a set of APs capable of performing the MAP coordination operation; A step of determining whether the TXOP corresponds to the MAP TXOP based on the information included in the PPDU when the BSS color field included in the PPDU is set to the BSS color of the AP included in the MAP set; and A method characterized by performing an operation to wait for reception of a MAP control frame transmitted by the OBSS AP without switching to the NPCA PCH if the above TXOP corresponds to the above MAP TXOP.

9. A method performed by an electronic device corresponding to a STA (station) of a wireless LAN network, Step of receiving a frame from an OBSS (overlapping basic service set) AP; A step of determining whether the TXOP occupied by the OBSS AP included in the frame corresponds to the MAP TXOP based on information indicating whether the TXOP corresponds to the MAP TXOP capable of performing a MAP (multi-AP) coordination operation; and A method characterized by including a step of performing an operation to switch to or not switch to NPCA (non-primary channel access) PCH (primary channel) based on the above judgment.

10. In Paragraph 9, If the above frame corresponds to a MAP ICF, a step of determining whether the TA (transmitter address) field of the MAP ICF is the MAC (media access control) address of an AP included in a MAP set, which is a set of APs capable of performing the MAP coordination operation with the AP associated with the STA; If the above TA field corresponds to the MAC address of the AP included in the above MAP set, a step of determining whether the MAC address in the AID (association ID) or RA (receiver address) field within the user info field of the above MAP ICF corresponds to the AP associated with the above STA; and A method characterized by performing an operation that does not switch to the NPCA PCH if the above AID corresponds to the above AP associated with the above STA.

11. In Paragraph 9, If the above frame corresponds to a trigger frame that is not a MAP ICF or an ICF that is not a trigger frame, a step of determining whether the TA field of the above frame is the MAC address of an AP included in a MAP set, which is a set of APs capable of performing the MAP coordination operation with the AP associated with the STA; If the above TA field corresponds to the MAC address of the AP included in the above MAP set, a step of determining whether the above TXOP corresponds to the above MAP TXOP based on the information included in the frame; and A method characterized by performing an operation that does not switch to the NPCA PCH if the above TXOP corresponds to the above MAP TXOP.

12. In Paragraph 9, If the above frame corresponds to a PPDU (physical layer protocol data unit) for packet transmission, a step of determining whether the BSS color field included in the PPDU is set to the BSS color of an AP included in a MAP set, which is a set of APs capable of performing the MAP coordination operation with the AP associated with the STA; A step of determining whether the TXOP corresponds to the MAP TXOP based on the information included in the PPDU when the BSS color field included in the PPDU is set to the BSS color of the AP included in the MAP set; and A method characterized by performing an operation that does not switch to the NPCA PCH if the above TXOP corresponds to the above MAP TXOP.

13. In an electronic device corresponding to the first AP (access point) of a wireless LAN network, Transmitter / receiver; and Acquire a TXOP (transmission opportunity), and Transmitting a frame containing information indicating whether the above TXOP corresponds to a MAP TXOP capable of performing MAP (multi-AP) coordination operations, and An electronic device characterized by including a control unit configured to perform frame exchange with associated STAs (stations) in the above TXOP.

14. In an electronic device corresponding to a second AP (access point) of a wireless LAN network, Transmitter / receiver; and Receives a frame from an OBSS (overlapping basic service set) AP, and Determining whether the TXOP occupied by the OBSS AP included in the above frame corresponds to the MAP TXOP based on information indicating whether the TXOP corresponds to the MAP TXOP capable of performing MAP (multi-AP) coordination operations, and An electronic device characterized by including a control unit configured to perform an operation of switching to or not switching to an NPCA (non-primary channel access) PCH (primary channel) based on the above judgment.

15. In an electronic device corresponding to a STA (station) of a wireless LAN network, Transmitter / receiver; and Receives a frame from an OBSS (overlapping basic service set) AP, and Determining whether the TXOP occupied by the OBSS AP included in the above frame corresponds to the MAP TXOP based on information indicating whether the TXOP corresponds to the MAP TXOP capable of performing MAP (multi-AP) coordination operations, and An electronic device characterized by including a control unit configured to perform an operation of switching to or not switching to an NPCA (non-primary channel access) PCH (primary channel) based on the above judgment.

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