Method and device for performing signal transmission and reception on basis of TXOP sharing between access points in wireless LAN network

Abstract

The present disclosure is for a wireless LAN system. An embodiment of the present disclosure describes a method and a device for efficiently using frequency and spatial resources for TXOP between APs.

Description

Method and device for transmitting and receiving signals based on TXOP sharing between access points in a wireless LAN network

[0001] The present disclosure relates to a method and device for transmitting a signal in a wireless LAN network system, and more particularly, to a method and device for performing signal transmission and reception based on sharing of transmission opportunities (TXOPs) between access points.

[0002] A wireless local area network (WLAN), also known as Wireless Fidelity (Wi-Fi), is a network that allows users to access the Internet via mobile devices or laptops within a certain distance from an access point (AP). WLAN technology continues to evolve with the rise of the Internet and the expansion of the smartphone market, and WLAN is used to provide high-speed data services to entire cities, including 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 standards. IEEE 802.11a and b, published in 1997 and 1999 respectively, are standards that utilize the unlicensed bands at 2.4 GHz and 5 GHz, with IEEE 802.11b providing a transmission rate of 11 Mbps and IEEE 802.11a providing a transmission rate of 54 Mbps. IEEE 802.11g applies orthogonal frequency-division multiplexing (OFDM) at 2.4 GHz to provide a transmission rate of 54 Mbps. IEEE 802.11n uses multiple input multiple output OFDM (MIMO-OFDM) to provide a transmission rate of 300 Mbps using four spatial streams. IEEE 802.11n supports channel bandwidths up to 40 MHz, in which case it provides a transmission rate of 600 Mbps.

[0004] Afterwards, the IEEE 802.11ac standard was introduced, which supports up to 160 MHz bandwidth, 8 spatial streams, and a speed of up to 1 Gbit / s, and IEEE 802.11ax, which provides multi-user MIMO (MU-MIMO) in both uplink and downlink and supports spatial frequency reuse, dynamic fragmentation, etc. Afterwards, 802.11be is being studied, which supports up to 320 ultra-wide channels, multi-link operation, 4kQAM, etc., and aims to theoretically implement a speed of 46 Gbps.

[0005] 802.11 introduced transmission opportunity (TXOP), which guarantees quality of service (QoS) and increases channel utilization. Furthermore, technology for sharing TXOPs between APs was introduced. This necessitates a method to improve transmission efficiency through spatial reuse during TXOP sharing between APs.

[0006] The invention of the present disclosure for solving the above problems is characterized by a method performed by an electronic device of a wireless LAN network, comprising: receiving a frame; checking whether an address field included in the frame is an identifier of a basic service set (BSS) capable of performing M-AP (multi-access point) operation with the electronic device; setting a network allocation vector (NAV) for M-AP operation when the address field is the identifier of the BSS capable of performing M-AP operation with the electronic device; and setting a basic NAV when the address field is not the identifier of the BSS capable of performing M-AP operation with the electronic device.

[0007] In addition, in an electronic device of a wireless LAN network, the present invention is characterized by including a transmitter / receiver; and a control unit configured to receive a frame, determine whether an address field included in the frame is an identifier of a basic service set (BSS) capable of performing an M-AP (multi-access point) operation with the electronic device, and, if the address field is the identifier of the BSS capable of performing the M-AP operation with the electronic device, set a network allocation vector (NAV) for the M-AP operation, and if the address field is not the identifier of the BSS capable of performing the M-AP operation with the electronic device, set a basic NAV.

[0008] According to a method according to at least one embodiment of the present disclosure, in the case of TXOP sharing between APs, at least one AP can transmit a signal through spatial reuse even in the case of TXOP sharing between APs, thereby efficiently using a carrier and increasing throughput.

[0009] Figure 1 is a diagram illustrating an example of a wireless communication network.

[0010] FIG. 2 is a diagram illustrating an example of the structure of an electronic device that performs WLAN connection.

[0011] Figure 3 is a diagram illustrating an example of a link setup process of a typical wireless LAN.

[0012] FIG. 4 is a diagram illustrating an example of a hidden node and an exposed node and an example of an RTS and a CTS for solving the problem of a hidden node and an exposed node.

[0013] Figure 5 is a diagram illustrating an example of a frame structure used in an IEEE 802.11 system.

[0014] Figure 6a is a diagram illustrating an example of NAV settings.

[0015] Figure 6b is a diagram illustrating an example of TXOP.

[0016] Figure 7 is a diagram illustrating an example of TXOP sharing between multiple APs.

[0017] Figure 8 is a diagram illustrating an example of a problem that may occur in the case of M-AP TXOP sharing.

[0018] FIG. 9 is a diagram illustrating an example of M-AP NAV settings when sharing M-AP TXOP according to one embodiment of the present disclosure.

[0019] FIG. 10 is a diagram illustrating an example in which NAV is set by another BSS when sharing M-AP TXOP according to one embodiment of the present disclosure.

[0020] FIG. 11 is a diagram illustrating an example of how transmission to an STA of a shared AP is affected when sharing an M-AP TXOP according to one embodiment of the present disclosure.

[0021] FIG. 12 is a diagram illustrating an example of a first method for indicating whether TXOP return is supported using a MAC capabilities information field.

[0022] FIG. 13 is a diagram illustrating an example of a third method of indicating whether TXOP return is supported using the EHT variant common information field.

[0023] FIG. 14 is a diagram illustrating an example of a fourth method for indicating whether TXOP return is supported using the HE variant user information field.

[0024] FIG. 15 is a diagram illustrating an example of a fifth method for indicating whether TXOP return is supported using the EHT variant user information field.

[0025] Figure 16 is a diagram illustrating an example of an operation for selecting a NAV to be set by an AP in the case of M-AP TXOP sharing.

[0026] Figure 17 is a diagram illustrating an example of an operation for frame transmission of an AP in the case of M-AP TXOP sharing.

[0027] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings.

[0028] In describing the embodiments, descriptions of technical details that are well known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to avoid obscuring the gist of the present disclosure by omitting unnecessary explanations and to convey the gist more clearly.

[0029] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0030] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. The embodiments of the present disclosure are provided only to ensure that the present disclosure is 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. Like reference numerals refer to like elements throughout the specification.

[0031] At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s).

[0032] Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, so that the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also be able to provide steps for performing the functions described in the flowchart block(s).

[0033] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0034] Here, the term '~ unit' used in this embodiment means software or hardware components such as FPGA (field programmable gate array) or ASIC (application specific integrated circuit), and the '~ unit' performs certain roles. However, the '~ unit' is not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Accordingly, according to some embodiments, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, 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 '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. Additionally, the components and '~parts' may be implemented to activate one or more CPUs within the device or secure multimedia card. Furthermore, according to some embodiments, the '~parts' may include one or more processors.

[0035] The exemplary embodiments are described below solely for simplicity with respect to wireless LAN systems. It should be understood that the exemplary embodiments are equally applicable to other wireless networks (e.g., cellular networks, pico-networks, femto-networks, satellite networks), as well as systems that utilize signals of one or more wired standards or protocols (e.g., Ethernet and / or HomePlug, PLC standards). As used herein, the terms WLAN and Wi-Fi® may include communications governed by the IEEE 802.11 family of standards, BLUETOOTH®, HiperLAN (a set of wireless standards primarily used in Europe and comparable to the IEEE 802.11 standards), and other technologies with relatively short radio ranges. Accordingly, the terms WLAN and WiFi may be used interchangeably herein. Additionally, while described below with respect to an infrastructure WLAN system including one or more APs and a plurality of wireless stations (STAs), the 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.

[0036] Additionally, while the present disclosure describes the exchange of data frames between wireless devices, the exemplary embodiments may be applied to the exchange of any data unit, packet, and / or frame between wireless devices. Thus, the term frame may include any frame, packet, or data unit, such as, for example, protocol data units (PDUs), media access control (MAC) protocol data units (MPDUs), and physical layer convergence procedure (PLCP) protocol data units (PPDUs). The term A-MPDU may mean aggregated MPDUs. A wireless local area network, or WLAN network, below may be a network implementing at least one of the IEEE 802.11 family of wireless communication protocol standards, such as those defined by the IEEE 802.11-2016 standard or amendments thereto (including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be).

[0037] In the following description, numerous specific details are set forth, such as examples of specific components, circuits, and processes, to provide a thorough understanding of the present disclosure. The term "connected," as used herein, means directly connected or connected via one or more intervening components or circuits. The term "connected AP" refers to an access point with which a given wireless station is currently associated and / or connected (e.g., there is an established communications channel or link between the access point and the given wireless station). Furthermore, in the following description and for purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the exemplary embodiments. However, it will be apparent to one skilled in the art that such specific details may not be necessary to practice the exemplary embodiments. In other instances, well-known circuits and devices are shown in block diagram form to avoid obscuring the present disclosure.

[0038] The operating principles of the present disclosure are described in detail below with reference to the attached drawings. In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, the terms described below are defined based on the functions of the present disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

[0039] 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 local area network (LAN), such as a Wi-Fi network. The wireless communication network (100) may include a plurality of wireless communication devices, such as an access point (AP) 102 and a plurality of stations (STAs) 104. While only one AP (102) is illustrated, the wireless communication network (100) may also include a plurality of APs (102).

[0040] An STA is a logical entity that includes a MAC and a physical layer interface to a wireless medium, and includes an AP and a non-AP STA (Non-AP station). Among the STAs, a portable terminal operated by a user is a Non-AP STA, and when simply referred to as an STA, it also refers to a Non-AP STA. Hereinafter, an STA may refer to a non-AP STA. Each of the STAs (104) may be referred to as a terminal or a device. The term '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 a cellular telephone, a smart phone having wireless communication capabilities, a personal digital assistant (PDA) having wireless communication capabilities, a wireless modem, a portable computer having wireless communication capabilities, a photographic device such as a digital camera having wireless communication capabilities, a gaming device having wireless communication capabilities, a music storage and playback appliance having wireless communication capabilities, an Internet appliance capable of wireless Internet access and browsing, as well as portable units or terminals incorporating combinations of such functions. In addition, the terminal may include, but is not limited to, a machine-to-machine (M2M) terminal, a machine type communication (MTC) terminal / device. In the present specification, the terminal may also be referred to as an electronic device or simply a device.

[0041] An AP (102) is an entity that provides access to a distribution system (DS) via a wireless medium to an associated station (STA) associated with it. An AP may also be called a centralized controller, a base station (BS), a Node-B, a base transceiver system (BTS), or a site controller.

[0042] An exemplary coverage area (106) of an AP (102) that may represent a basic service area (BSA) of a wireless communication network (100) is illustrated. The AP (102) periodically broadcasts beacon frames (beacon frames may be used interchangeably with beacon) containing a basic service set identifier (BSSID) to enable any STAs (104) within the wireless range of the AP (102) to associate or re-associate with the AP (102) and establish or maintain a separate communication link (108) (or may be referred to as a Wi-Fi link) with the AP (102). The AP (102) may provide access to external networks for various STAs (104) within the WLAN via the separate communication links (108).

[0043] 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 the BSSID, which may be the MAC address of the AP (102).

[0044] BSS can be categorized into infrastructure BSS and independent BSS (IBSS). The BSS illustrated in Figure 1 is an IBSS, but an infrastructure BSS (not shown) can also be established. An infrastructure BSS includes one or more STAs and an AP. In principle, communication between non-AP STAs in an infrastructure BSS occurs via the AP. However, if a direct link is established between non-AP STAs, direct communication between non-AP STAs is also possible.

[0045] Multiple infrastructure BSSs can be interconnected via a DS. Multiple BSSs connected via a DS are called an extended service set (ESS). STAs within an ESS can communicate with each other, and within the same ESS, STAs can seamlessly move from one BSS to another while maintaining seamless communication.

[0046] A DS is a mechanism that connects multiple APs. It doesn't necessarily have to be a network, and there are no restrictions on its form as long as it can provide a certain distribution service. For example, a DS could be a wireless network, such as a mesh network, or a physical structure that connects APs.

[0047] Additionally, the AP (102) and the STA (104) may be referred to as AP-MLD (access point multi-link device) and STA-MDL, respectively. This may mean that the AP and the STA can support multi-link operation.

[0048] Below is an example of a hierarchical structure according to the 802.11 standard.

[0049] The 802.11 standard document is developing the 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, and receives packets from the upper layer, 802.1X Port Filtering, through the MAC_SAP interface, and configures 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, and the PLCP sublayer is responsible for configuring the IEEE 802.11 MAC frame configured in the MAC sublayer into a PLCP frame. The PLCP frame is then transmitted to the opposite terminal through the PMD sublayer.

[0050] Various management frames that manage Wi-Fi wireless access are not transmitted at the upper layer of 802.1X. These management frames are transmitted as requests and responses between the SMEs (station management entities) located within each terminal. The SME is a layer-independent entity that may exist in a separate management plane or may appear to be off to the side. For example, if an AP wants to form a BSS, the AP instructs the transmission of a beacon through the MLME_SAP interface, namely, the MLME-START.reques and MLME-START.confirm primitives. If an STA wants to associate with the AP, the STA instructs the transmission of an association Request / Response frame through the MLME-ASSOCIATE.request, MLME-ASSOCIATE.response, MLME-ASSOCIATE.confirm, and MLME-ASSOCIATE.indication primitives. Meanwhile, if SME wants to set operating parameter values ​​related to the physical layer, it can set various physical layer parameter values ​​through the PLCP_SAP interface.

[0051] FIG. 2 is a diagram illustrating an example of the structure of an electronic device performing WLAN access. Referring to FIG. 2, an 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.

[0052] 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 (for example, IEEE Std 802.11TM). For example, the communication module (220) can operate based on IEEE 802.11ac, 802.11ax, 802.11be, or 802.11bn among Wi-Fi communication methods, and in particular, IEEE 802.11be or 802.11bn has improved performance by supporting a wider bandwidth, higher data throughput, and shorter delay time compared to IEEE 802.11ax.

[0053] 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)). According to various embodiments, the communication module (220) may further include a memory.

[0054] According to various embodiments, the transceiver (224) may convert a baseband transmit signal into a wireless signal or may convert a received wireless signal into a baseband receive signal.

[0055] 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), for example, a modulator, a digital-analog converter (D / A converter), a frequency converter, an A / D converter, an amplifier, and / or a demodulator.

[0056] Although not shown, according to various embodiments, the electronic device (200) may include at least one antenna module that is electrically connected to the communication module of the AP (210) and supports a communication protocol and / or frequency band supported by the communication module of the AP (210).

[0057] The communication processor (222) may 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) may control the transceiver (224) to form a wireless connection with the AP (200) using a 2.4 GHz, 5 GHz, or 6 GHz band WLAN standard such as IEEE 802.11ac, 802.11ax, 802.11be, or 802.11bn. Alternatively, the communication processor (222) may control the transceiver (191) to form a wireless connection with the AP (210) using a 60 GHz band WLAN standard such as IEEE 802.11ad or 802.11ay. Additionally, a method of communicating between an electronic device (200) and an AP (210) using the WLAN standard may be referred to as a communication method based on the STA mode.

[0058] 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.

[0059] According to various embodiments, the AP (210) may support an operation of transmitting packets to an external network and / or an operation of the plurality of electronic devices receiving packets from an external network based on a connection between a plurality of electronic devices (e.g., the electronic device (200)) and an external network (e.g., the Internet, an external LAN, or a cellular network).

[0060] For example, the AP (210) may be a wireless router. The AP (210) may be a dedicated wireless router or a general-purpose device supporting mobile hotspot functionality, and there are no limitations on its implementation. For example, the AP (210) may include the same components as the electronic device (200), such as a processor and / or a communication module. Furthermore, the AP (210) may transmit and receive data to and from an external device, such as a server. For example, the AP (210) may transmit at least a portion of the data received from the server to the electronic device (200).

[0061] 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 the processor (230) or by a separate processor. The separate communication module may include a transceiver and a processor, and may also include memory. In addition, the electronic device (200) may include a separate antenna module or wired connection device for connection with an external network.

[0062] Figure 3 is a diagram illustrating an example of a link setup process of a typical wireless LAN.

[0063] 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 complete security authentication procedures. The link setup process can also be referred to as the session initiation process or session setup process. Furthermore, the discovery, authentication, association, and security setup processes of the link setup process can be collectively referred to as the association process.

[0064] Referring to FIG. 3, an 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 search for a network it can participate in. Before joining a wireless network, the STA (300) must identify a compatible network. The process of identifying networks existing in a specific area is called scanning.

[0065] There are two types of scanning methods: active scanning and passive scanning. In active scanning, an STA (300) performing scanning transmits a probe request frame (322) to search for APs in the vicinity while moving between channels and waits for a response. A responder transmits a probe response frame (324) to the STA that transmitted the probe request frame in response to the probe request frame. Here, the responder may be an AP or STA that last transmitted a beacon frame in the BSS of the channel being scanned. In FIG. 3, an example of a BSS that becomes a responder is shown because an AP (310) transmits a beacon frame (320), and in an IBSS, STAs within the IBSS take turns transmitting beacon frames, so the responder is not constant. 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 BSS-related information included in the received probe response frame and move to the next channel to perform scanning in the same manner.

[0066] The scanning operation can also be performed in a passive scanning manner. In passive scanning, the STA performing the scanning moves through channels and detects beacon frames. A beacon frame is one of the management frames in IEEE 802.11, and is periodically transmitted to announce the presence of a wireless network and to enable the STA performing the scanning to find the wireless network and participate in the wireless network. FIG. 3 illustrates an example of a BSS in which an AP (310) periodically transmits a beacon frame (320) to an STA (300), and in an IBSS, STAs within the IBSS take turns transmitting beacon frames. When the STA performing the scanning receives a beacon frame, it stores information about the BSS included in the beacon frame and moves to another channel, recording the beacon frame information on each channel. Comparing active and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.

[0067] 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 below. The authentication process includes a process in which the STA (300) transmits an authentication request frame (330) to the AP (310), and in response, the AP (310) transmits an authentication response frame (332) to the STA (300). The authentication frame used for the authentication request / response corresponds to a management frame.

[0068] The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), and a Finite Cyclic Group. These are just some examples of information that may be included in an authentication request / response frame, and may be replaced with other information or include additional information.

[0069] The AP (310) may determine whether to allow authentication for the STA based on information included in the received authentication request frame. The AP (310) may provide the result of the authentication process to the STA (300) via an authentication response frame.

[0070] After the STA is successfully authenticated, an association process can be performed. The association process includes a process in which the STA (300) transmits an association request frame (340) to the AP (310), and in response, the AP (310) transmits an association response frame (342) to the STA (300).

[0071] For example, the association request frame may include information related to various capabilities, such as beacon listen interval, SSID, supported rates, supported channels, robust security network (RSN), mobility domain, supported operating classes, traffic indication map broadcast request, and interworking service capabilities.

[0072] For example, the association response frame may include information related to various capabilities, status codes, association ID (AID), supported rates, enhanced distributed channel access (EDCA) parameter sets, received channel power indicator (RCPI), received signal to noise indicator (RSNI), mobility domains, timeout interval (association comeback time), overlapping BSS scan parameters, TIM broadcast response, QoS maps, etc.

[0073] These are just some examples of information that may be included in a request / response frame, and may be replaced by other information or include additional information.

[0074] Although not shown, after the STA successfully associates with the network, a security setup process may be performed. The security setup process may be referred to as an authentication process via a robust security network association (RSNA) request / response, the authentication process (330) may be referred to as a first authentication process, and the security setup process may also be referred to as an authentication process.

[0075] The security setup process may include, for example, a private key setup process through a four-way handshaking using an extensible authentication protocol over LAN (EAPOL) frame, or may be performed according to a security method not defined in the IEEE 802.11 standard.

[0076] Below we describe the media access control protocol provided by 802.11.

[0077] In wireless LAN systems based on IEEE 802.11, the basic access mechanism of MAC is based on the distributed coordination function (DCF) that utilizes 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. Physical carrier sense is a method in which the physical layer detects the channel status and notifies the MAC layer, and virtual carrier sense is a method in which the channel occupancy time is broadcast to neighboring stations to reserve the channel in advance. An STA or AP that has secured a transmission channel records and transmits this channel occupancy time within the RTS or / and CTS or data frame. Other STAs that receive this determine that the channel is busy during this time and do not compete for the channel, thereby avoiding collisions.

[0078] The physical carrier sensing method basically adopts 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 or carrier or medium for a predetermined time period before starting transmission. The predetermined time period is called an inter frame space (IFS) and can vary depending on the priority of the traffic to be transmitted. That is, the priority can be determined by the length of the time period, and the higher the priority packet, the shorter the time period can be.

[0079] The above IFS may include SIFS (short IFS), PIFS (PCF IFS), DIFS (DCF IFS), AIFS (arbitration IFS), etc. The SIFS is the shortest time interval and may be mainly used as a waiting time for control information. The PIFS is a time interval of medium length and may be for packets with medium priority (PIFS = SIFS + 1 slot time). The DIFS is the longest time interval compared to the SIFS and PIFS, has a low priority, and may be mainly used as a waiting time for checking whether a channel is in use (DIFS = SIFS + 2 slot time). That is, for example, an STA that wishes to perform transmission may listen to whether a channel is in use (or detect the channel) during the DIFS period.

[0080] As a result of sensing, if the medium is determined to be in an idle state, the AP and / or STA start transmitting frames through the medium. On the other hand, if the medium is detected to be in an occupied state, the AP and / or STA may not start its own transmission, but may wait for a delay period (e.g., a random backoff period) for medium access before attempting to transmit frames. For example, the AP and / or STA may randomly select a timer value within the range of a contention window (CW), wait until the timer expires, and then sense the channel again. At this time, if the medium is in an idle state, the AP and / or STA may start transmitting frames, and if the medium is in an occupied state, the AP and / or STA may select a timer value again by doubling the size of the contention window. The size of the initially applied contention window may be set to the minimum window size (contention window minimum, CW). min ) and the maximum size of the contention window that can be applied is called the maximum window size (contention window maximum, CW). max ) is called. By applying a random backoff period, multiple STAs are expected to wait for different periods of time before attempting to transmit a frame, thus minimizing collisions.

[0081] However, since this DCF method does not consider the priority between STAs, it has a problem in that it is difficult to support various types of data transmission and QoS (quality of service), so the hybrid coordination function (HCF) was introduced. HCF is based on the DCF and the point coordination function (PCF). PCF is 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), which is a contention-based channel access method, and HCCA (HCF controlled channel access), which is a contention-free method using a polling mechanism. In addition, HCF includes a medium access mechanism to improve the QoS of WLAN, and can transmit QoS data in both a contention period (CP) and a contention-free period (CFP).

[0082] According to EDCA, data has a priority from 0 to 7 depending on the traffic type, and data arriving at the MAC layer is mapped to four ACs (access categories) according to the priority. The higher the priority, the higher the priority, and each AC has different AC parameters, and backoff is performed using AC parameter values ​​that are set differently, so data has different channel access priorities depending on the AC. 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 shorter the channel access delay, so that data can use more bandwidth in a given traffic environment. If a collision occurs between STAs during frame transmission, the EDCA backoff process, which generates a new backoff counter, is similar to the existing DCF, and transmission according to traffic priority is guaranteed through EDCA parameters that include priorities for each AC.

[0083] FIG. 4 is a diagram illustrating an example of a hidden node and an exposed node and an example of an RTS and a CTS for solving the problem of a hidden node and an exposed node.

[0084] 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 may determine that the medium is idle when performing carrier sensing before STA C sends data to STA B, even though STA A is transmitting the information to STA B. This is because STA A's transmission (i.e., medium occupancy) may not be sensed at STA C's location. In this case, STA B receives information from STA A and STA C simultaneously, resulting in a collision. In this case, STA A can be said to be a hidden node of STA C.

[0085] (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 may determine that the medium is occupied due to the transmission of 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, STA A is outside the transmission range of STA C, so the transmission from STA C and the transmission from STA B may not collide from the perspective of STA A, and thus STA C unnecessarily waits until STA B stops transmitting. In this case, STA C can be called an exposed node of STA B.

[0086] In order to effectively utilize the collision avoidance mechanism in the above situation, short signaling packets such as RTS (request to send) and CTS (clear to send) can be utilized. An STA that wishes to transmit data transmits an RTS to an STA that will receive the data, and the receiving STA that receives the RTS responds to the transmitting STA with a CTS frame. The RTS and / or CTS between two STAs can be overheard by surrounding STA(s), allowing the surrounding STA(s) to consider whether information should be transmitted between the two STAs.

[0087] (c)(420) is an example of a method for solving the hidden node problem. Assume that both STA A and STA C want 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 medium access until STA A and STA B finish transmitting data, thereby avoiding collisions.

[0088] (d)(430) is an example of a method for solving the exposed node problem. STA B, which wants to transmit data to STA A, transmits an RTS, and STA A, which is to receive the data, can respond to the RTS by transmitting a CTS. In this case, if STA C receives only the RTS transmitted by STA B and does not receive the CTS transmitted by STA A, STA C can know that STA A is outside the carrier sensing area of ​​STA C. In this case, STA C can determine that no collision will occur even if it transmits data to another STA (e.g., STA D), and can transmit the data.

[0089] Figure 5 is a diagram illustrating an example of a frame structure used in an IEEE 802.11 system.

[0090] The PPDU (physical layer protocol data unit) format can be composed of a short training field (STF), a long training field (LTF), a SIGNAL (SIG) field, and a data field. The most basic (e.g., non-HT (high throughput)) PPDU frame format can be composed of only the legacy-STF (L-STF), legacy-LTF (L-LTF), a SIG field, and a data field.

[0091] 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. The STF and LTF can be collectively called the PLCP preamble, which is a signal for OFDM physical layer synchronization and channel estimation.

[0092] The SIG field can be used to transmit control information for demodulation and decoding of the data field. The SIG field can include information about the data rate and data length. Additionally, the SIG field can include a parity bit, a SIG TAIL bit, etc.

[0093] The data field may include a SERVICE field, a physical layer service data unit (PSDU), a PPDU TAIL bit, and, if necessary, padding bits. Some bits of the SERVICE field may be used for a descrambler at the receiver. The PSDU corresponds to an MPDU (MAC protocol data unit) defined at the MAC layer and may contain data generated / used by upper layers. The PPDU TAIL bit may be used to return the encoder to a 0 state. The padding bit may be used to adjust the length of the data field to a predetermined unit.

[0094] MPDU is defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, frame body, and FCS (frame check sequence). MAC frame is composed of MPDU and can be transmitted / received through PSDU of the data part of PPDU format.

[0095] The MAC header is defined as an area that includes a frame control field, a duration / ID field, an address 1 field, an address 2 field, an address 3 field, a sequence control field, an address 4 field, a QoS control field, and an HT control field.

[0096] The Frame Control field contains information about the characteristics of the corresponding MAC frame. The Segment / Identifier field may be implemented to have different values ​​depending on the type and subtype of the corresponding MAC frame.

[0097] The Address 1 field to the Address 4 field are used to indicate the BSSID, source address (SA), destination address (DA), transmitting address (TA) indicating the transmitting STA address, and receiving address (RA) indicating the receiving STA address.

[0098] The sequence control field is set to include a sequence number and a fragment number. The sequence number can indicate the sequence number assigned to the corresponding MAC frame. The fragment number can indicate the number of each fragment of the corresponding MAC frame.

[0099] The QoS Control field contains information related to QoS. The QoS Control field may be included when 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.

[0100] 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 is 11,454 octets, and the maximum PPDU size can be 5.484 ms.

[0101] FCS is defined as a MAC footer and is used to detect errors in MAC frames.

[0102] The first three fields (Frame Control, Segment / Identifier, and Address 1) and the last field (FCS) constitute the minimum frame format and are present in all frames. The other fields may only be present in certain frame types.

[0103] Below is a description of the network allocation vector (NAV) used in wireless LAN networks.

[0104] As mentioned above, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, in which the AP and / or STA directly sense the medium. Virtual carrier sensing is intended to address potential issues in medium access, such as the hidden node problem. For virtual carrier sensing, the MAC of the wireless LAN system can utilize NAV. NAV is a value that indicates to other APs and / or STAs the remaining time until the medium becomes available, by the AP and / or STA currently using or authorized to use 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 the period. NAV can be set, for example, according to the value of the duration field of the MAC header of the frame.

[0105] Figure 6a is a diagram illustrating an example of NAV settings.

[0106] Referring to FIG. 6a, a source STA (source STA, 600) transmits an RTS frame after a DIFS, and a destination (destination) (610) transmits a CTS frame after an SIFS. The destination STA designated as the receiver through the RTS frame does not set an NAV. Some of the remaining STAs (620) may receive the RTS frame and set an NAV (630), and some may receive the CTS frame and set an NAV (640).

[0107] If a CTS frame (e.g., PHY-RXSTART.indication primitive) is not received within a certain period of time from the time when the RTS frame is received (e.g., the time when the MAC receives the PHY-RXEND.indication primitive corresponding to the RTS frame), STAs that have set or updated the NAV through the RTS frame may reset the NAV (e.g., to 0) (or this case may be referred to as NAVtimeout). The certain period of time may be (2*aSIFSTime + CTS_Time + aRxPHYStartDelay + 2*aSlotTime), and this may be referred to as NAVtimeout period. CTS_Time may be calculated based on the length of the CTS frame and the data rate indicated by the RTS frame.

[0108] In Fig. 6a, for convenience, setting or updating NAV through an RTS frame or a CTS frame is illustrated, but NAV setting / resetting / updating may also be performed based on the interval field of various other frames, such as a non-HT PPDU, an HT PPDU, a VHT PPDU, or a HE PPDU (for example, an interval field in the MAC header of a MAC frame).

[0109] 802.11ax also introduces basic NAV and intra-BSS NAV. Basic NAV is always set by frames transmitted by APs or STAs other than itself (mandatory), and intra-BSS NAV can be optionally set by frames transmitted from the BSS to which the AP or STA belongs. An AP or STA can access the medium when both NAV timers have expired (or after all NAV time intervals have elapsed).

[0110] Below, we describe TXOP (transmission opportunity). TXOP is a new feature introduced in the 802.11e MAC to ensure QoS and improve channel utilization. To ensure QoS, TXOP can be used to assign priority transmission opportunities when two or more packets fall into the same access category (AC).

[0111] Figure 6b is a diagram illustrating an example of a TXOP. An STA participating in QoS transmission can obtain a TXOP, which allows it to transmit traffic for a certain period of time, using two channel access methods: EDCA and HCCA. Acquiring a TXOP is possible by either successfully competing in EDCA or receiving a QoS CF-Poll frame from the AP. The former is called an EDCA TXOP, and the latter is called a Polled TXOP. In this way, the concept of TXOP can be used to grant a certain amount of time for a random STA to transmit a frame, or to forcibly limit the transmission time.

[0112] The transmission start time and maximum transmission time of TXOP are determined by the AP, which is notified to the STA by a beacon frame for EDCA TXOP and by a QoS CF-Poll frame for Polled TXOP.

[0113] NAV can be understood as a type of timer to protect the TXOP of a transmitting STA (e.g., a TXOP holder). An STA can protect the TXOP of another STA by not performing channel access while the NAV set for itself is valid. In the current wireless LAN system, the TXOP duration is set through the duration / ID field of the MAC header. That is, the TXOP holder and the TXOP responder (e.g., the Rx STA) transmit the entire TXOP information required for transmitting and receiving frames by including it in the duration field of the frames they transmit and receive. Third-party STAs that are not the TXOP holder or the TXOP responder (e.g., third-party STAs) check the Duration field of the frames exchanged between the TXOP holder and the TXOP responder, and postpone channel use until the NAV period by setting / updating the NAV.

[0114] Below we describe the 802.11be standard. 802.11be, also known as EHT (extremely high throughput), operates in the 2.4, 5, and 6 GHz bands and is being developed to provide speeds up to 46 Gbps, which is 4.8 times faster than WiFi 6, by introducing 320 MHz of bandwidth, 4096QAM, multiple resource units (RUs), and multi-link operation (MLO), while providing low latency and high network throughput. Specifically, 802.11be provides a wide bandwidth of 320 MHz in the 6 GHz band, and can transmit data via MU-MIMO with 16 spatial streams in both the uplink and downlink, and adopts 4096QAM to achieve high transmission efficiency. In addition, it has the characteristics of increasing spectrum efficiency by flexibly performing spectrum resource scheduling through multiple RUs, and simultaneously transmitting and receiving data in various frequency bands and channels through multi-link operation.

[0115] Below, we describe TXOP sharing. In order to improve the efficiency of the wireless channel in 802.11ac, MU-MIMO MAC technology was introduced to simultaneously transmit different frames from an AP to multiple STAs using spatially divided multiple channels. At this time, the AP determines the destination STA and the frame to be transmitted for each channel during the TXOP period based on the AC (access category, or priority) of the frame to be transmitted, and transmits the determined multiple frames to multiple STAs. Recently, TXOP sharing between APs has been studied. Through TXOP sharing between APs, an AP with a TXOP can share its TXOP with other APs, thereby efficiently using frequency and spatial resources, increasing network throughput and reducing latency.

[0116] FIG. 7 is a diagram illustrating an example of TXOP sharing between multiple APs. The operation of performing TXOP sharing between multiple APs may be referred to as M-AP TXOP sharing or Co-TDMA (coordinated time division multiple access) operation as part of the multi-AP coordination (M-AP coordination (MAPC)) operation that is performed through coordination / negotiation between APs to improve the performance of the entire network. According to FIG. 7, AP2 (720) formed a BSS (hereinafter referred to as BSS2) with STA3 (730) and STA4 (732), AP1 (700) formed a BSS (hereinafter referred to as BSS1) with STA1 (710) and STA2 (712), and AP3 (740) formed a BSS (hereinafter referred to as BSS3) with STA5 (750) and STA6 (752). At this time, if AP2 (720) shares its TXOP with AP3 (752), AP2 (720) may be referred to as a sharing AP, and AP3 (740) may be referred to as a shared AP. The TXOP sharing between APs of the present disclosure is not limited to the example of FIG. 7.

[0117] FIG. 8 is a diagram illustrating an example of a problem that may occur in the case of M-AP TXOP sharing. According to FIG. 8, AP2 (720) that has acquired TXOP (810) may share the TXOP with AP3 (740) by transmitting a frame (e.g., a trigger frame, e.g., MU-RTS TXS TF (multi-user RTS TXOP sharing trigger frame) 830) that conveys an intention to share its TXOP. At this time, the TXOP occupied by AP3 (740) may be referred to as a shared TXOP (812). AP3 (740), which has received a frame such as 830, may transmit a CTS (840) and a trigger (844, which may be omitted) for transmitting data, and may transmit a data frame (846) to its associated STA.

[0118] At this time, even though AP1 (700) and AP3 (740) are hidden nodes from each other (i.e., transmissions of AP1 (700) and AP3 (740) do not affect each other), AP1 (700) can receive a trigger frame (830) transmitted by AP2 (720) or set a basic NAV (850) due to BSS2, which is the BSS of AP2 (720). At this time, the basic NAV is due to the TXOP (810) occupied by AP2 (720), and AP1 (700) cannot access the channel during the basic NAV (or until the basic NAV timer expires) even if AP2 (720) shares the TXOP with AP3 (740). Since the transmission of AP3 (740) does not affect AP1 (700), AP1 (700) can use the medium, but AP1 (700) does not access the medium, which may result in inefficiency in space or medium utilization. In addition, in this case, the basic NAV (850) is not interrupted by NAVtimeout.

[0119] To address these issues, the present disclosure proposes an M-AP NAV applicable to TXOP sharing between APs and a NAVtimeout applicable to the M-AP NAV. Furthermore, it proposes limiting spatial reuse using the M-AP NAV to cases where TXOP return is not possible, and proposes various methods for indicating that TXOP return is not possible.

[0120] Specifically, an AP can set and maintain a basic NAV and an M-AP NAV. The name M-AP NAV is only an example, and a different name may be used if it is a NAV used in TXOP sharing. The M-AP NAV can be set (or updated) by at least one known surrounding BSS. The known surrounding BSS (or AP) can be an AP that can share TXOP with the AP or a BSS of the AP, and a connection between BSSs (or between APs) can be established in advance before TXOP sharing. APs connected in this way can be called M-APs, and M-AP operations can include, for example, increasing the throughput of the entire network or performing cooperative operations to satisfy a time constraint that occurs within the BSS of a specific AP. Such operations are possible by utilizing previously shared settings or exchanging real-time control messages. Based on information shared in advance or exchanged in real time, M-AP can perform various actions, such as securing transmission opportunities for a specific BSS through exchange of r-TWT (restricted target wakeup time) information.

[0121] M-AP NAV can only be configured for APs that are configured as M-APs or that support inter-AP TXOP sharing. Alternatively, it can only be configured for APs that support a specific version (e.g., IEEE 802.11be or an 802.11 version including later versions). Alternatively, it can only be configured for APs that support inter-AP TXOP sharing and have notified the terminal of this support using capability information.

[0122] If the AP receives a frame for TXOP sharing, the AP can set (or update) the M-AP NAV, and if the AP does not receive a frame during the NAVtimeout corresponding to the M-AP NAV (or for TXOP sharing), the AP can access the medium to transmit its own frame. At this time, the NAVtimeout can be set to a time during which the AP can confirm that the frame transmission and reception of the AP with which the TXOP has been shared (the shared AP) does not affect the AP. In other words, it can be a time during which it can confirm whether the frame transmission and reception of the shared AP and the destination STA affect the AP. For example, NAVtimeout may be determined as the time to transmit and receive 3SIFS + CTS + trigger + ACK (acknowledgment response to trigger) (or the time to transmit and receive CTS, trigger, and ACK (acknowledgment response to trigger) and the sum of 3SIFS), or may be determined as the time to perform SIFS + CTS (or the time to transmit and receive CTS and the sum of SIFS) considering that the trigger and ACK may be omitted. It is also possible to use an IFS other than SIFS to determine NAVtimeout. The above NAVtimeout may be determined in the standard, or according to the settings of the AP or / and STA.

[0123] If the AP receives, for example, a CTS or / and trigger frame of the shared AP, an ACK of a destination STA to which the shared AP wishes to transmit a packet, before the NAVtimeout time has elapsed after the M-AP NAV timer has been started (or during the M-AP NAV during the NAVtimeout), the frame transmission and reception of the shared AP affects the AP, so the AP does not attempt to occupy the medium. In this specification, medium occupation includes actions such as confirming that the medium has not been occupied for a specific time and immediately transmitting its own data frame or transmitting a control frame. In addition, if the basic NAV is set for the AP by another AP or BSS, the AP does not attempt to occupy the medium.

[0124] Additionally, the configuration of M-AP NAV and / or application of NAVtimeout may be restricted in cases where TXOP return (the action of the shared AP returning the shared TXOP to the shared AP) of the shared AP is not allowed or supported. This is because if TXOP return is allowed, the AP may collide with the frame transmission / reception of the shared AP that received the TXOP even if the AP does not collide with the shared AP.

[0125] The NAVtimeout proposed in this disclosure can be applied to the M-AP NAV or to another NAV (e.g., basic NAV).

[0126] FIG. 9 is a diagram illustrating an example of M-AP NAV settings when sharing an M-AP TXOP according to one embodiment of the present disclosure. According to FIG. 9, AP2 (720, sharing AP) occupying a TXOP (900) can share the TXOP with AP3 (740, shared AP) via a trigger frame (910) (902). At this time, AP1 (700) receiving the trigger frame (910) sets, updates, or resets the M-AP NAV (930) and checks whether a frame is received during the NAV timeout (or detects a frame).

[0127] AP3 (740), a shared AP, transmits a CTS (920) in response to a trigger frame (910) and transmits a trigger (922, or trigger frame) for transmitting data to STA6 (752), an STA associated with itself. STA6 (752) transmits an ACK (940) in response to the trigger (922), and AP3 (740), upon receiving the ACK (940), can transmit data (924, or data frame) to STA6 (752). The transmission and reception of the trigger (922) and ACK (940) may also be omitted.

[0128] At this time, if AP1 (700) does not receive (or detect) CTS (920), trigger (922) and ACK (940) during NAVtimeout, AP1 (700) may transmit RTS (932) to transmit a data frame to the STA associated with it. For example, if AP1 (700) transmits data to STA1 (710), STA1 (710) transmits CTS (950) to AP1 (700). Afterwards, AP1 (700) may transmit a data frame (934) to STA1 (710). In addition, AP1 (700) may skip RTS (932) transmission and directly transmit the data frame (934), and in this case, CTS (950) transmission of STA1 (710) may also be skipped.

[0129] Afterwards, STA6 (752) can transmit ACK (942) to AP3 (740) in response to data (924), and STA1 (710) can also transmit ACK (952) in response to data (934), and such transmission may also be omitted.

[0130] As described above, even if AP3 (740) shares the TXOP of AP2 (720), AP1 (700) can transmit its own data packet to its associated STA, thereby enabling efficient use of frequency and space resources.

[0131] Although not shown, if AP1 (700) receives (or detects) CTS (920), trigger (922) and ACK (940) during NAVtimeout, AP1 (700) does not attempt to access the medium. In addition, the basic NAV can be set based on the received or detected frame.

[0132] FIG. 10 is a diagram illustrating an example in which a NAV is set by another BSS when sharing an M-AP TXOP according to an embodiment of the present disclosure. According to FIG. 10, AP2 (720, sharing AP) occupying a TXOP (1000) can share the TXOP with AP3 (740, shared AP) via a trigger frame (1010) (1002). However, in this case, consider a case in which a basic NAV (1032) has already been set by another BSS (not shown) for AP1 (700). In this case, AP1 (700) receiving the trigger frame (1010) does not set, update, or reset the M-AP NAV (1030) because the basic NAV (1032) has already been set. Alternatively, even if the M-AP NAV (1030) is set, it is also possible not to apply the NAVtimeout.

[0133] AP3 (740), a shared AP, transmits a CTS (1020) in response to a trigger frame (1010) and transmits a trigger (1022, or trigger frame) for transmitting data to STA5 (750), an STA associated with it. STA5 (750) transmits an ACK (1040) in response to the trigger (1022), and upon receiving the ACK (1040), AP3 (740) can transmit data (1024, or data frame) to STA5 (750). The transmission and reception of the trigger (922) and ACK (940) may also be omitted.

[0134] At this time, since basic NAV (1032) is set for AP1 (700), AP1 (700) does not attempt to occupy the medium. In other words, even if it is an AP that is not affected by the shared AP, if the basic NAV is set by another BSS (i.e., if the frame transmission and reception of the AP may conflict with the frame transmission and reception of the other BSS), the AP may not attempt to occupy the medium and transmit frames.

[0135] FIG. 11 is a diagram illustrating an example of how transmission to an STA of a shared AP is affected when sharing an M-AP TXOP according to an embodiment of the present disclosure. According to FIG. 11, AP2 (720, sharing AP) occupying a TXOP (1100) can share the TXOP with AP3 (740, shared AP) via a trigger frame (1110) (1102). At this time, AP1 (700) receiving the trigger frame (1110) sets, updates, or resets the M-AP NAV (1130) and checks whether a frame is received during the NAV timeout (or detects a frame).

[0136] AP3 (740), which is a shared AP, transmits a CTS (1120) in response to a trigger frame (1110) and transmits a trigger (1122, or trigger frame) for transmitting data to STA6 (752), which is an STA associated with itself. STA6 (752) transmits an ACK (1140) in response to the trigger (1122), and AP3 (740), which has received the ACK (1140), can transmit data (1124, or data frame) to STA6 (752). The transmission and reception of the trigger (1122) and ACK (1140) may be omitted. STA6 (752), which has received the data (1124), can transmit an ACK (1142) to AP3 (740) in response.

[0137] At this time, if AP1 (700) does not receive (or detect) CTS (1120), trigger (1122) and ACK (1140) during NAVtimeout, AP1 (700) can transmit RTS (1132) to transmit a data frame to its associated STA (e.g., STA2 (712)). However, if STA2 (712) is close to AP3 (740) and receives the trigger (1122) transmitted by AP3 (740), basic NAV (1152) is set for STA2 (712). At this time, even if STA2 (712) detects RTS (1132) transmitted by AP1 (700), STA2 (712) does not transmit CTS (1150). In other words, frame transmission and reception between AP1 (700) and STA2 (712) is not performed.

[0138] The difference between the example of FIG. 9 and the example of FIG. 11 is that the frame transmission and reception of AP1 (700) and STA1 (710) according to the example of FIG. 9 does not collide with AP3 (740), but the frame transmission and reception of AP1 (700) and STA2 (712) according to the example of FIG. 11 may collide with AP3 (740). As described above, spatial reuse can only be possible between STAs associated with APs that are not affected by frame transmission and reception between STAs associated with the shared AP.

[0139] The M-AP NAV and NAVtimeout described above may be limited to cases where TXOP returns from the shared AP are not permitted or supported. Below, various methods are described for the shared AP (or / and the shared AP, hereinafter referred to as AP) to indicate that TXOP returns are not permitted or supported. At least one of the methods described above may be used in combination.

[0140] FIG. 12 is a diagram illustrating an example of a first method for indicating whether TXOP return is supported using a MAC capabilities information field. An AP may transmit information indicating whether TXOP return is allowed or supported in information indicating its capabilities. The information indicating whether TXOP return is allowed or supported by the AP may be a capability element. An example of FIG. 12 is an EHT MAC capabilities information field, and whether TXOP return is allowed or supported may be indicated using 2 or 1 bit of a reserved field of the EHT MAC capabilities information field. The EHT MAC capabilities information field may be included in an EHT capabilities element. The element may be included in a management frame, and the management frame may be at least one of a beacon frame, an association request or association response frame, a reassociation request or reassociation response frame, a probe request or response frame. Since the action of indicating whether a single TXOP return is supported is performed between APs, it can be included in a beacon frame or a management frame used to perform inter-AP setup for M-AP operation.

[0141] Alternatively, instead of EHT-related capability information, UHR (ultra high reliability)-related capabilities information may include information indicating whether TXOP returns are allowed or supported. In this case, the information may also be included in the management frame described above.

[0142] Alternatively, the second method is to indicate whether TXOP return is allowed or supported by using the value corresponding to reserved in the triggered TXOP sharing mode subfield. Table 1 below shows the interpretation of the triggered TXOP sharing mode subfield.

[0143] Triggered TXOP SharingMode subfield valueDescription0MU-RTS that does not initiate TXS procedure.1MU-RTS that initiates TXS procedure wherein a scheduled STA can only transmit MPDU(s) addressed to its associated AP.2MU-RTS that initiates TXS procedure wherein a scheduled STA can transmit MPDU(s) addressed to its associated AP or addressed to another STA.3Reserved.

[0144] As shown in Table 1 above, when the value of the triggered TXOP sharing mode subfield is 3, which corresponds to reserved, it may be indicated that TXOP return is not allowed or not supported. The subfield may be included in, for example, a HE variant common information field or an EHT variant common information field, or may be included in a field indicating the operation of the trigger frame according to the version supported by the AP (or AP MLD), STA (or STA MLD or non-AP MLD) device. For example, the supported version may be 802.11ax (or W-Fi 6) or 802.11be (or Wi-Fi 7). The subfield may be included in an MU-RTS frame, and for example, the frame may be an MU-RTS TXS trigger frame. FIG. 13 is a diagram illustrating an example of a third method for indicating whether TXOP return is supported using an EHT variant common information field. The EHT variant common information field is a field for indicating the operation of the trigger frame according to the version supported by the AP (or AP MLD), STA (or STA MLD or non-AP MLD) device, and the third method is not limited to the use of the EHT variant common information field as long as it is a field for indicating the operation of the trigger frame. For example, according to FIG. 13, the EHT variant common information field included in the header of the MU-RTS frame includes three reserved fields, and one or more of these reserved fields can be used to indicate that TXOP return is not permitted or not supported.Additionally, a similar information field to support UHR (e.g., the UHR variant common information field) may be used to indicate that TXOP returns are not allowed or supported, in which case, for example, a field indicating whether TXOP returns are allowed or supported may be included in the UHR variant common information field.

[0145] FIG. 14 is a diagram illustrating an example of a fourth method for indicating whether TXOP return is supported using the HE variant user information field. The HE variant user information field is a field for indicating the target and the configuration of the target of the trigger frame according to the version supported by the AP (or AP MLD), STA (or STA MLD or non-AP MLD) device, and the fourth method is not limited to the use of the HE variant user information field as long as it is a field for indicating the target and the configuration of the target of the trigger frame. For example, according to FIG. 14, the HE variant user information field of the MU-RTS frame includes a reserved field, one or more bits of which can be used to indicate, for example, whether TXOP return is allowed or supported. In addition, a similar information field for supporting UHR (for example, the UHR variant user information field) can be used to indicate that TXOP return is not allowed or not supported, and in this case, for example, a field indicating whether TXOP return is allowed or supported can be included in the UHR variant user information field.

[0146] FIG. 15 is a diagram illustrating an example of a fifth method for indicating whether TXOP return is supported using an EHT variant user information field. The EHT variant user information field is a field for indicating a target and configuration of a trigger frame according to a version supported by an AP (or AP MLD), STA (or STA MLD or non-AP MLD) device, and the fifth method is not limited to the use of the EHT variant user information field as long as it is a field for indicating a target and configuration of the target of a trigger frame. For example, according to FIG. 15, the EHT variant user information field of an MU-RTS frame includes a reserved field, one or more bits of which can be used to indicate, for example, whether TXOP return is allowed or supported.

[0147] The information fields proposed in the second to fifth methods may be included in an MU-RTS frame. The MU-RTS frame is a type of trigger frame, and the information fields proposed in the second to fifth methods may be included in such a frame.

[0148] An AP can receive a frame described in the first to fifth methods (e.g., an MU-RTS frame) and determine whether the AP that transmitted the frame allows or supports TXOP return. For example, in the case of the first method, the AP can check information indicating whether TXOP return is included in an EHT MAC capabilities information field included in a beacon frame, and determine whether the AP that transmitted the beacon frame allows or supports TXOP return or not. In addition, the AP can store whether a specific AP allows TXOP return, and can set an M-AP NAV when the specific AP becomes a sharing AP (or shared AP).

[0149] FIG. 16 is a diagram illustrating an example of an operation for selecting a NAV to be set by an AP in case of M-AP TXOP sharing. According to FIG. 16, the AP receives a frame (1600) and checks whether the receiver address or the transmitter address or the specific address field included in the received frame is the identifier (BSS ID) of the BSS of the M-AP known to the AP (1610). If the receiver address or the transmitter address or the specific address field of the frame is the BSS ID of the M-AP known to the AP, this is for M-AP operation and the AP can set, update or reset the M-AP NAV (1630). If the receiver address or the transmitter address of the frame is not the BSS ID of the M-AP known to the AP, the AP can set, update or reset the basic NAV (1620). Here, the received frame may be, for example, a received frame capable of decoding a duration field included in the MAC header.

[0150] Also, although FIG. 16 illustrates an example in which either M-AP NAV or basic NAV is set, it is also possible that basic NAV is always set, M-AP NAV is optionally set, and M-AP NAV is given priority. Alternatively, it is also possible to determine whether NAVtimeout is set for basic NAV through the same judgment.

[0151] The above flowchart illustrates exemplary methods that can be implemented according to the principles of the present disclosure, and various modifications may be made to the methods depicted in the flowcharts herein. For example, although depicted as a series of steps, various steps in each drawing may overlap, occur in parallel, occur in different orders, or occur multiple times. In other instances, steps may be omitted or replaced with other steps. The values ​​described above are merely examples, and it is entirely possible for other values ​​to be applied.

[0152] Fig. 17 is a diagram illustrating an example of an operation for frame transmission of an AP in case of M-AP TXOP sharing. According to Fig. 17, an AP receives a frame for TXOP sharing (1700). For example, the frame may be an MU-RTS TXS trigger frame or an M-AP TXS trigger frame. The received frame may include information indicating that TXOP return is not allowed or not supported. The AP receiving the frame determines whether only the M-AP NAV or the basic NAV is set (1710). The determination may be replaced with a determination as to whether the M-AP NAV is set in addition to the basic NAV, or whether a NAV timeout is applied to the basic NAV. The determination may be based on the result of Fig. 16. If it is determined that the basic NAV is set, the AP may perform a conventional operation (1750).

[0153] When the AP determines that the M-AP NAV is set, the AP determines whether frame transmission is detected during the NAV timeout period. Frames that may be detected include, for example, CTS, trigger, ACK, and data frames of the shared AP and STAs associated with the shared AP. If transmission is detected, the AP can optionally set the basic NAV according to the received frame and perform conventional operations (1750).

[0154] If no transmission is detected, the AP attempts to seize the medium and transmit a frame (1730). If the AP succeeds in seizing the channel, the AP transmits a frame (1740). The frame may be, for example, a data frame. If the channel seize fails (i.e., the transmission attempt is unsuccessful), the AP may perform conventional operations (1750). The operations of FIG. 17 may be performed when the AP receives information indicating that the sharing AP (or shared AP) performing TXOP sharing does not allow or support TXOP returns.

[0155] The above flowchart illustrates exemplary methods that can be implemented according to the principles of the present disclosure, and various modifications may be made to the methods depicted in the flowcharts herein. For example, although depicted as a series of steps, various steps in each drawing may overlap, occur in parallel, occur in different orders, or occur multiple times. In other instances, steps may be omitted or replaced with other steps. The values ​​described above are merely examples, and it is entirely possible for other values ​​to be applied.

[0156] Meanwhile, the embodiments of the present disclosure disclosed in this specification and drawings are merely specific examples to easily explain the technical content of the present disclosure and help understand the present disclosure, and are not intended to limit the scope of the present disclosure. In other words, it will be apparent to those skilled in the art to which the present disclosure pertains that other modifications based on the technical idea of ​​the present disclosure are possible. In addition, the above-described embodiments can be combined and operated as needed. For example, parts of one embodiment of the present disclosure and parts of another embodiment can be combined to operate an AP and a STA.

[0157] Meanwhile, the order of description in the drawings illustrating 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 illustrating the method of the present invention may omit some components and include only some components, as long as it does not harm the essence of the present invention.

Claims

1. In a method performed by an electronic device of a wireless LAN network, Step of receiving a frame; A step of checking whether the address field included in the above frame is an identifier of a basic service set (BSS) capable of performing M-AP (multi-access point) operation with the electronic device; A step of setting a network allocation vector (NAV) for M-AP operation, when the address field is the identifier of the BSS capable of performing the M-AP operation with the electronic device; and A method characterized in that it comprises the step of setting a basic NAV if the address field is not the identifier of the BSS capable of performing the M-AP operation with the electronic device.

2. In paragraph 1, A step of receiving a frame for sharing a TXOP (transmission opportunity); and A method characterized in that, when the NAV for the above M-AP operation is set, the method further comprises a step of determining whether a frame is detected during a predetermined time period after receiving a frame for the above TXOP sharing.

3. A method according to claim 2, characterized in that the predetermined time interval is determined based on the sum of the time during which CTS (clear to send), trigger frame, and reception confirmation information for the trigger frame can be transmitted and received and 3 SIFS (short inter frame space).

4. A method according to claim 2, characterized in that the predetermined time interval is determined based on the sum of the time during which CTS (clear to send) can be transmitted and received and SIFS.

5. In paragraph 2, A method characterized by comprising a step of attempting to occupy the medium if no frame is detected during the predetermined time period.

6. In paragraph 2, A method characterized in that it further includes a step of setting a basic NAV based on the detected frame and not attempting to occupy the medium when a frame is detected during the predetermined time period.

7. In paragraph 1, A method characterized by further comprising the step of receiving information indicating that an action of returning a shared TXOP from another AP is not permitted.

8. A method according to claim 7, characterized in that the information is included in a frame for TXOP sharing.

9. In electronic devices of a wireless LAN network, Transmitter and receiver; and Receive the frame, Verify that the address field included in the above frame is an identifier of a basic service set (BSS) capable of performing M-AP (multi-access point) operations with the electronic device, If the address field is the identifier of the BSS capable of performing the M-AP operation with the electronic device, set a network allocation vector (NAV) for the M-AP operation, and An electronic device characterized in that it includes a control unit configured to set a basic NAV when the address field is not the identifier of the BSS capable of performing the M-AP operation with the electronic device.

10. In paragraph 9, the control unit, Receive frames for sharing TXOP (transmission opportunity), and An electronic device characterized in that, when a NAV for the above M-AP operation is set, it is set to determine whether a frame is detected during a predetermined time period after receiving a frame for the above TXOP sharing.

11. An electronic device according to claim 10, wherein the predetermined time interval is determined based on the sum of a time during which a CTS (clear to send), a trigger frame, and a reception confirmation information for the trigger frame can be transmitted and received, and 3 SIFS (short inter frame space).

12. An electronic device according to claim 10, wherein the predetermined time interval is determined based on the sum of the time during which CTS (clear to send) can be transmitted and received and SIFS.

13. In paragraph 10, the control unit, An electronic device characterized in that it is set to attempt to occupy the medium if no frame is detected during the above-described time period.

14. In paragraph 10, the control unit, An electronic device characterized in that, when a frame is detected during the above-described time period, a basic NAV is set based on the detected frame and the medium is not attempted to be occupied.

15. In paragraph 9, the control unit, It is set to receive information indicating that the action of returning a shared TXOP from another AP is not permitted, An electronic device characterized in that the above information is included in a frame for TXOP sharing.

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