Method and device for negotiating TXOP sharing duration on basis of TXOP sharing between access points in wireless LAN network

Abstract

An embodiment of the present disclosure relates to a method for negotiating a transmission opportunity (TXOP) sharing duration in order to efficiently use frequency and spatial resources in the case of TXOP sharing between APs, the method comprising the steps of: transmitting, to a second electronic device, a first message including information indicating a first length of a TXOP duration to be shared; and receiving, from the second electronic device, a second message corresponding to a response to the first message, wherein the second message includes information indicating a second length of the TXOP duration proposed by the second electronic device.

Description

Method and device for negotiating a TXOP sharing interval 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 negotiating a shared TXOP duration based on TXOP sharing 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 and 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 WRAN 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 transmission opportunities to ensure quality of service (QoS) and improve channel utilization. It also introduced technology for sharing TXOPs between APs. This requires a method for negotiating the TXOP interval to be shared for effective resource allocation during TXOP sharing between APs.

[0006] The invention of the present disclosure for solving the above problems is a method performed by a first electronic device of a wireless LAN network, comprising the steps of: transmitting a first message including information indicating a first length of a transmission opportunity duration (TXOP) period to be shared with a second electronic device; and receiving a second message corresponding to a response to the first message from the second electronic device, wherein the second message includes information indicating a second length of the TXOP period proposed by the second electronic device.

[0007] Also, a method performed by a second electronic device of a wireless LAN network comprises the steps of: receiving a first message including information indicating a first length of a transmission opportunity duration (TXOP) period to be shared from a first electronic device; and transmitting a second message corresponding to a response to the first message from the first electronic device, wherein the second message includes information indicating a second length of the TXOP period proposed by the second electronic device.

[0008] In addition, in a first electronic device of a wireless LAN network, a transmitter and receiver are included; and a control unit for transmitting a first message including information indicating a first length of a TXOP period (transmission opportunity duration) to be shared with a second electronic device, and receiving a second message corresponding to a response to the first message from the second electronic device, wherein the second message includes information indicating a second length of the TXOP period proposed by the second electronic device.

[0009] In addition, in a second electronic device of a wireless LAN network, a transmitter and receiver are included; and a control unit for receiving a first message including information indicating a first length of a transmission opportunity duration (TXOP) period to be shared from a first electronic device, and controlling transmission of a second message corresponding to a response to the first message from the first electronic device, wherein the second message includes information indicating a second length of the TXOP period proposed by the second electronic device.

[0010] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present disclosure pertains from the description below.

[0011] According to a method according to at least one embodiment of the present disclosure, when TXOP sharing is performed between APs, carriers can be efficiently used and throughput can be increased through appropriate TXOP sharing. The effects obtained from the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art to which the present disclosure pertains from the description below.

[0012] Figure 1 is a diagram illustrating an example of a wireless communication network.

[0013] FIG. 2 is a diagram illustrating an example of the structure of an electronic device that performs WLAN connection.

[0014] Figure 3 is a diagram illustrating an example of a link setup process of a typical wireless LAN.

[0015] 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.

[0016] Figure 5 is a diagram illustrating an example of a frame structure used in an IEEE 802.11 system.

[0017] Figure 6 is a drawing showing an example of NAV settings.

[0018] Figure 7 is a diagram illustrating an example of TXOP.

[0019] FIG. 8 is a diagram illustrating an example of operation for Co-TDMA (coordinated time division multiple access).

[0020] Figure 9 is a diagram illustrating an example of TXOP sharing between multiple APs.

[0021] Figure 10 is a diagram illustrating an example of a problem that may occur in the case of TXOP sharing.

[0022] Figure 11 is a diagram illustrating an example in which a trigger frame is used for TXOP sharing.

[0023] Figure 12 is a diagram illustrating an example in which a control frame is used for TXOP sharing.

[0024] Figure 13 is a diagram illustrating an example of operation when a TXOP interval shorter than the TXOP interval proposed by the shared AP is shared.

[0025] FIG. 14 is a diagram illustrating an example of the operation of a sharing AP performing at least one embodiment of the present disclosure.

[0026] FIG. 15 is a diagram illustrating an example of the operation of a shared AP performing at least one embodiment of the present disclosure.

[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 ensure that the gist of the present disclosure is conveyed more clearly without obscuring it by omitting unnecessary explanations.

[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 AP (102) and a plurality of STAs (stations, 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 its associated STAs. 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 divided 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 6 is a drawing showing an example of NAV settings.

[0106] Referring to FIG. 6, a source STA (source STA, 600) transmits an RTS frame after DIFS, and a destination (destination) (610) transmits a CTS frame after 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. 6, 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 various other frames, such as a non-HT PPDU, HT PPDU, VHT PPDU, or an interval field of a HE PPDU (for example, an interval field in a 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 7 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 kind 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 duration 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. This 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.

[0116] Figure 8 is a diagram illustrating an example of an operation for Co-TDMA. Co-TDMA is a technology that cooperates with each other to enable connection by dividing time between APs. For example, this can be performed through TXOP sharing between APs. An AP occupying a TXOP can share its TXOP with an AP expected to process traffic. In this case, the AP sharing the TXOP can be referred to as a sharing AP, and the AP that has shared the TXOP can be referred to as a shared AP.

[0117] According to FIG. 8, in the step of setting Co-TDMA configuration, basic configuration information for Co-TDMA operation can be shared between APs (810). FIG. 8 illustrates an example of performing Co-TDMA configuration between AP1 and AP n. For example, information for Co-TDMA operation may include capability information of each AP and configuration information for Co-TDMA of each AP. The capability information of the AP may include at least one of information on QoS and / or traffic that the AP can support, security-related information that the AP can support, access methods that the AP can support, data transmission rates and NSS (number of spatial streams) that the AP supports, and configuration information for Co-TDMA may include at least one of information on whether TXOP return is supported for each AP and information necessary for processing its own traffic that is generated periodically.

[0118] Also, for example, for long-term Co-TDMA operation (800), information about periodic traffic can be shared between APs (820) in the step of setting Co-TDMA settings between APs. The information about the periodic traffic can include information about the nature or expected QoS of the periodic traffic. Specifically, the information can include information about a traffic identifier (TID) set to the AP or expected to be transmitted and received by the AP, the (nominal or maximum) size of traffic (e.g., MSDU (MAC service data unit)) for each TID, an interval, a data rate (e.g., maximum, average, minimum), a direction of uplink or downlink, etc. Each AP can share the information about the periodic traffic to predict the periodic traffic to be processed by each AP during the Co-TDMA process and perform Co-TDMA operation.

[0119] Additionally, for short-term operation (860), information about aperiodic traffic can be shared between APs (850). For example, such sharing can be performed through a Co-TDMA information exchange operation (840). 840 and 850 can be understood as a single operation. The Co-TDMA information exchange operation can be performed, for example, by transmitting and receiving a BSR (buffer state report). For example, the BSR can include information about the size of traffic stored in the buffer for each AC, the nature of the traffic, QoS, priority of the traffic, etc. The BSR can be transmitted in response to a request to receive a BSR, or when a specific condition is satisfied, such as when the size of the traffic stored in the buffer (or the size of the buffer can be used interchangeably) is set or exceeds a predetermined threshold, or it can be transmitted periodically.

[0120] Or / and the Co-TDMA information exchange operation can be performed, for example, through NFRP (NDP (null data PPDU) feedback report poll). When the transmitter transmits an NFRP trigger frame, the receiver can transmit an NDP feedback report response in response. The NDP feedback report response can include information indicating whether the size of the buffer is greater than or equal to a threshold. The transmitter can predict the buffer status of the receiver through the response.

[0121] Each AP can share information about the aperiodic traffic, share resources for aperiodic traffic during the Co-TDMA process, and perform Co-TDMA operations. The Co-TDMA information exchange operations described above are not limited by the messages described above.

[0122] Through the above information sharing, the sharing AP can predict the amount of TXOP to be shared with the shared AP before Co-TDMA operation and perform TXOP sharing. If the sharing AP can accurately predict the length of the TXOP section required by the shared AP through the above information sharing, the TXOP return, in which the shared AP returns the shared TXOP to the shared AP, may not be necessary. For this operation, whether or not to perform the TXOP return operation may be optional for the AP.

[0123] FIG. 9 is a diagram illustrating an example of TXOP sharing between multiple APs. According to FIG. 9, AP2 (920) formed a BSS (hereinafter referred to as BSS2) with STA3 (930) and STA4 (932), AP1 (900) formed a BSS (hereinafter referred to as BSS1) with STA1 (910) and STA2 (912), and AP3 (940) formed a BSS (hereinafter referred to as BSS3) with STA5 (950) and STA6 (952). In this case, when AP2 (920) shares its TXOP with AP3 (940), AP2 (920) corresponds to a sharing AP, and AP3 (940) corresponds to a shared AP. TXOP sharing between APs of the present disclosure is not limited by the example of FIG. 9.

[0124] FIG. 10 is a diagram illustrating an example of a problem that may occur in the case of TXOP sharing. According to FIG. 10, a sharing AP (1000) forms BSS1 with a HE (high efficiency) STA (1004), and a shared AP (1002) may belong to BSS2. The sharing AP (1000) that has acquired a TXOP (1010) may transmit a frame (e.g., a trigger frame, e.g., a MU-RTS TXS TF (multi-user RTS TXOP sharing trigger frame) 1020) that conveys an intention to share its TXOP, so that the TXOP may be shared with the shared AP (1002). At this time, the trigger frame (1020) may include, for example, a duration field to indicate the length of the shared TXOP duration. At this time, the TXOP occupied by the shared AP (1002) can be referred to as a shared TXOP (1012).

[0125] A shared AP (1002) that receives a frame such as 1020 transmits a CTS (1030) and performs frame transmission and reception (which may be referred to as a frame exchange sequence) with an STA associated with it. For example, the interval field of the CTS (1030) may be set to a limit value of the sum of the lengths of the SIFS and the frame duration of the CTS from the value indicated by the interval field of the trigger frame. In this case, if the time required for the shared AP (1002) to perform the frame exchange sequence is 1034, or the time according to the TXOP (1012) shared by the shared AP (1000) is not sufficient, the frame exchange sequence may be limited (1032).

[0126] In addition, the HE STA (1004) associated with the sharing AP (1000) is a terminal that supports the 802.11ax (or Wi-Fi 6) standard and receives a trigger frame (1020), but may not receive the CTS (1030) transmitted by the shared AP (1002) depending on the distance from the shared AP (1002). Even if the HE STA (1004) receives the trigger frame (1020), the HE STA (1004) does not confirm that the trigger frame is for TXOP sharing and may perform the NAVTimeout operation (1022) in the same manner as when a general MU-RTS is received. The NAVTimeout operation is an operation that suspends the NAV operation, and when the NAVTimeout operation is performed, the NAV is reset and the HE STA (1004) may attempt to occupy the medium. When HE STA (1004) successfully completes medium occupation and is performing data transmission and reception, the TXOP shared with the shared AP (1002) may be returned to the sharing AP (1000), and the sharing AP (1000) may not be able to use the channel again because of HE STA (1004) that is using the channel even though it has the channel usage right, or a problem may occur in which communication fails due to occupying the channel at the same time as HE STA (1004). In Fig. 10, HE STA is only an example, and the same problem may occur in an STA that does not understand the trigger frame (1020) for TXOP sharing. For example, such an STA may correspond to an STA that supports a version earlier than 802.11be.

[0127] As described above, if TXOP return is not allowed through accurate TXOP prediction according to Co-TDMA operation, the sharing AP that shares its TXOP may conservatively estimate the TXOP section to be shared with the shared AP, which may result in not sharing sufficient TXOP with the shared AP. In addition, there is a concern that an STA that does not understand the trigger frame for sharing TXOP, as in the example of FIG. 10, may perform inefficient operations.

[0128] To solve these problems, the present disclosure proposes a method and device for negotiating the length of a TXOP interval shared between a TXOP sharing AP and a shared AP in the case of TXOP sharing between APs.

[0129] If the shared AP requires a shorter or longer TXOP interval than the length of the shared TXOP interval indicated by the shared AP, the shared AP can transmit a CTS frame with the interval field set to indicate the value of the TXOP interval it requires. The shared AP, upon receiving the CTS frame, can respond to the shared AP's proposal via a control frame. Specifically, the shared AP can accept or reject the shared AP's TXOP interval proposal, or propose a new TXOP interval. After that, the shared AP can operate by accepting the response via the shared AP's control frame.

[0130] In this way, the shared AP can share an appropriate TXOP interval, and STAs associated with the shared AP that receive the control frame transmitted by the shared AP (which do not understand the trigger frame for sharing the TXOP) can perform more efficient operations by not resetting the NAV (i.e., not performing the NAVTimeout operation because the frame was received).

[0131] Figure 11 is a diagram illustrating an example in which a trigger frame is used for TXOP sharing.

[0132] According to FIG. 11, a sharing AP (1100) forms BSS1 with a HE STA (1104), and a shared AP (1102) may belong to BSS2. The sharing AP (1100) that has acquired a TXOP (1110) may share the TXOP with the shared AP (1102) by transmitting an MU-RTS TXS TF (1120) for sharing its TXOP. At this time, the MU-RTS TXS TF (1120) may include a duration field to indicate the length (1114) of the shared TXOP duration. The shared AP (1102) that has received a frame such as 1120 may transmit a CTS (1130) and set the duration field of the CTS (1130) to indicate the length of the TXOP duration as much as the shared AP (1102) requires.

[0133] The interval field of the above CTS can indicate the length of the shared TXOP interval required by the shared AP (1102) as an absolute value of time, and for example, can indicate the length of the TXOP interval in μs units or in predetermined time units, but is not limited thereto. Alternatively, it is also possible to indicate the difference value (Δ value) with the length of the TXOP interval indicated by the shared AP (1100) through the interval field of the MU-RTS TXS TF (1120). At this time, some bits of the interval field (for example, MSB (most significant bit) or LSB (least significant bit)) indicate which length is longer between the length of the TXOP interval indicated by the shared AP (1100) and the length of the TXOP interval suggested by the shared AP (1102), and some bits of the interval field (for example, the remaining bits excluding the MSB or LSB) may indicate the difference between the length of the TXOP interval indicated by the shared AP (1100) and the length of the TXOP interval suggested by the shared AP (1102).

[0134] If the length of the TXOP interval required by the shared AP (1102) is the same as the length of the TXOP interval indicated by the shared AP (1100) through the MU-RTS TXS TF (1120) (or if the difference in the lengths of the two TXOP intervals is less than or equal to a specific threshold), the shared AP (1102) may indicate the length of the TXOP interval indicated through the MU-RTS TXS TF (1120) through the CTS (1130), or may indicate a specific value indicating that there is no difference between the length of the TXOP interval indicated through the MU-RTS TXS TF (1120) and the length of the required TXOP interval, or may indicate that the difference between the length of the TXOP interval indicated through the MU-RTS TXS TF (1120) and the length of the required TXOP interval is 0. Also, in this case, transmission and reception of a control frame (1122) in response to CTS (1130) is omitted, and the length of the shared TXOP section indicated by the sharing AP (1100) through MU-RTS TXS TF (1120) can be applied.

[0135] The sharing AP (1100) that receives the CTS (1130) transmitted by the shared AP (1102) transmits a response to the CTS (1130) to the shared AP (1102) via a control frame (1122). The control frame corresponds to a frame that includes an interval field that is part of the MAC header or includes a specific field indicating a response to the CTS (1130).

[0136] The above response can be made in the following two ways, but is not limited thereto. In the first way, the sharing AP (1100) may indicate its intention to accept by setting the value of the interval field of the control frame (1122) to be the same as the value of the interval field of the CTS (1130), or may indicate its intention to reject by setting the value of the interval field to be the same as the value of the interval field of the MU-RTS TXS TF (1120), or may propose a new TXOP interval length by setting the value of the interval field to a value different from the values ​​of the CTS (1130) and the MU-RTS TXS TF (1120). Alternatively, the sharing AP (1100) may indicate its intention to accept or reject by setting the value of the interval field to a predetermined value, and may propose a new TXOP interval length by setting the value of the interval field to a value different from the values ​​of the CTS (1130) and the MU-RTS TXS TF (1120). The interval field suggesting the length of a new TXOP interval can be set in the same way as the interval field of the CTS (1130) described above.

[0137] In a second method, the sharing AP (1100) can accept, reject, or propose a new TXOP interval length through a separate field in the control frame (1122). Alternatively, the separate field may indicate the intent to accept or reject, and if the interval field value is set to a value different from the values ​​of the CTS (1130) and the MU-RTS TXS TF (1120), it may be understood that the sharing AP (1100) proposes a new TXOP interval length. In this case, the value of the separate field may be ignored.

[0138] The shared AP (1102) that received the above control frame (1122) interprets the control frame (1122) and, if the intention to accept is indicated, determines that the TXOP has been shared as long as the length (1112) of the TXOP interval that it proposed through the CTS (1130), and performs transmission and reception of the frame exchange sequence (1132). In this example, the shared AP (1102) requests a TXOP interval (1112) longer than the length (1114) of the TXOP that the sharing AP (1100) wanted to share through the CTS (1130). If the interpretation of the control frame (1122) indicates the intention to reject, the shared AP (1102) determines that the TXOP (1114) of the length indicated by the interval field of the MU-RTS TXS TF (1120) has been shared by the sharing AP (1100). If the length of a new TXOP is indicated as a result of interpretation of the control frame (1122), the shared AP (1102) determines that a TXOP of the length of the TXOP newly indicated by the control frame (1122) is shared.

[0139] Additionally, when a HE STA (1104) associated with a sharing AP (1100) receives a control frame (1122) transmitted by the sharing AP (1100), the NAV of the HE STA (1104) may not be reset (1124). As the NAV is not reset, the HE STA may not attempt to occupy the medium.

[0140] Figure 12 is a diagram illustrating an example in which a control frame is used for TXOP sharing.

[0141] According to FIG. 12, a sharing AP (1200) that has acquired a TXOP (1210) can share its TXOP with a shared AP (1202) by transmitting a first message (1220) for sharing its TXOP. The first message may be a control frame for sharing the TXOP. At this time, the first message (1220) may include an interval field to indicate the length (1214) of the TXOP interval to be shared. Alternatively, the length of the TXOP interval to be shared may be indicated through another field. A shared AP (1202) that has received a control frame such as 1220 may transmit a second message (1230) in response to the first message (1220), and may set a specific field of the second message (1230) to indicate the length of the TXOP interval as much as the shared AP (1202) requires. The second message (1230) corresponds to a frame that includes an interval field that is part of a MAC header or includes a specific field indicating a response to the first message (1220), and may correspond to a control frame, for example.

[0142] For example, the interval field of the second message (1230) may indicate the length of the TXOP interval required by the shared AP (1202) as an absolute value of time, and may indicate the length of the TXOP interval in units of μs or predetermined time units, but is not limited thereto. Alternatively, it is also possible to indicate the difference (Δ value) between the length of the TXOP interval indicated by the shared AP (1200) through the interval field of the first message (1220). At this time, some bits of the interval field (for example, MSB (most significant bit) or LSB (least significant bit)) may indicate which length is longer between the length of the TXOP interval indicated by the shared AP (1200) and the length of the TXOP interval suggested by the shared AP (1202), and some bits of the interval field (for example, bits other than the MSB or LSB) may indicate the difference between the length of the TXOP interval indicated by the shared AP (1200) and the length of the TXOP interval suggested by the shared AP (1202).

[0143] If the length of the TXOP interval required by the shared AP (1202) is the same as the length of the TXOP interval indicated by the shared AP (1200) through the first message (1220) (or if the difference in the lengths of the two TXOP intervals is less than or equal to a specific threshold), the shared AP (1202) may indicate the length of the TXOP interval indicated by the first message (1220) through the second message (1230), or may indicate a specific value meaning that there is no difference between the length of the TXOP interval indicated by the first message (1220) and the length of the required TXOP interval, or may indicate that the difference between the length of the TXOP interval indicated by the first message (1220) and the length of the required TXOP interval is 0. In addition, in this case, the transmission and reception of the third message (1222), which is a response to the second message (1230), may be omitted.

[0144] Alternatively, it is also possible that the length of the TXOP interval required by the shared AP (1102) is indicated by a field other than the interval field of the second message (1230). The method of indicating the length of the TXOP interval required by the shared AP (1102) by another field may also be similar to the method of setting the interval field of the second message (1230) described above.

[0145] When the length of the TXOP interval required by the shared AP (1202) is the same as the length of the TXOP interval indicated by the sharing AP (1200) through the first message (1220), the shared AP (1202) may indicate the length of the TXOP interval indicated by the first message (1220) through the second message (1230), or may indicate a specific value meaning that there is no difference between the length of the TXOP interval indicated by the first message (1220) and the length of the required TXOP interval, or may indicate that the difference between the length of the TXOP interval indicated by the first message (1220) and the length of the required TXOP interval is 0. In addition, in this case, the transmission and reception of the third message (1230) may be omitted, and the length of the shared TXOP interval indicated by the sharing AP (1202) through the first message (1220) may be applied.

[0146] The sharing AP (1200), which has received the second message (1230) transmitted by the shared AP (1202), transmits a response to the second message (1230) to the shared AP (1202) via a third message (1222). The third message may correspond to a control frame, and corresponds to a frame including a specific field indicating a response to the second message.

[0147] The above response is possible in the following two ways, but is not limited thereto. In the first way, the sharing AP (1200) may indicate acceptance by setting the value of the interval field of the third message (1222) to be equal to the value of the length of the TXOP interval indicated in the second message (1230), or may indicate rejection by setting the value of the interval field to be equal to the value of the length of the TXOP interval indicated in the first message (1220), or may propose a new TXOP interval length by setting the value of the interval field to a value different from the values ​​of the length of the TXOP interval indicated in the second message (1230) and the first message (1220). Alternatively, the sharing AP (1200) may indicate acceptance or rejection by setting the value of the interval field to a predetermined value, and may propose a new TXOP interval length by setting the value of the interval field to a value different from the length of the TXOP interval indicated in the second message (1230) and the first message (1220). The interval field proposing the length of the new TXOP interval may be set in the same manner as setting the interval field of the second message (1230) described above.

[0148] In a second method, the sharing AP (1200) can accept, reject, or propose a new TXOP interval length through a separate field of the third message (1222). Alternatively, the separate field may indicate the intent to accept or reject, and if the value of the interval field is set to a value different from the TXOP interval length values ​​indicated in the second message (1230) and the first message (1220), it is also possible to understand that the sharing AP (1200) proposes a new TXOP interval length. In this case, the value of the separate field may be ignored.

[0149] The shared AP (1202) that received the third message (1222) interprets the third message (1122) and, if the intention to accept is indicated, determines that the TXOP has been shared as long as the TXOP section that it proposed through the second message (1230) (1212) and performs a frame exchange sequence (1232). In this example, the shared AP (1202) requests a TXOP section longer than the length (1214) of the TXOP that the sharing AP (1200) wanted to share through the second message (1230). If the interpretation of the third message (1222) indicates the intention to reject, the shared AP (1202) determines that the TXOP (1214) of the length that the sharing AP (1200) indicated through the first message (1220) has been shared. If the length of a new TXOP is indicated as a result of interpretation of the third message (1222), the shared AP (1202) determines that a TXOP of the length of the TXOP newly indicated by the third message (1222) is shared.

[0150] The above first to third messages may correspond to control frames supported by the current standard, or may correspond to newly defined control frames.

[0151] Figure 13 is a diagram illustrating an example of operation when a TXOP interval shorter than the TXOP interval proposed by the shared AP is shared.

[0152] According to FIG. 13, a sharing AP (1300) that has acquired a TXOP (1310) can share the TXOP with a shared AP (1302) by transmitting a first message (1320) for sharing its own TXOP. The first message may be a control frame or MU-RTS TXS TF for sharing the TXOP. At this time, the first message (1320) may include an interval field to indicate the length (1316) of the shared TXOP interval. Alternatively, the length of the shared TXOP interval may be indicated through another field.

[0153] A shared AP (1302) that receives a first message such as 1320 may transmit a second message (1330) in response to the first message, and may set a specific field of the second message (1330) to indicate the length (1314) of a TXOP interval as required by the shared AP (1302). In FIG. 13, a case is illustrated where the length (1314) of a TXOP interval requested by the shared AP (1302) is longer than the length (1316) of a shared TXOP interval indicated in the first message (1320). A method for setting the second message (1330) to indicate the length of a TXOP interval as required by the shared AP (1302) may follow the method described with respect to FIG. 11 or FIG. 12.

[0154] The sharing AP (1300), which receives the second message (1330) transmitted by the shared AP (1302), transmits a response to the second message (1330) to the shared AP (1302) through a third message (1322). The third message may correspond to a control frame. At this time, the sharing AP (1300) may propose a new shared TXOP interval length such as 1312. 1312 may be shorter than the length (1314) of the TXOP interval requested by the shared AP (1302). The method for indicating the length of the shared TXOP interval may follow the method described in relation to FIG. 11 or FIG. 12. Alternatively, the sharing AP (1300) may reject the length of the shared TXOP interval requested by the shared AP (1302) through the third message (1322).

[0155] At this time, the shared AP (1302) that received the third message (1322) determines that the TXOP of the TXOP interval length (1312) newly indicated by the third message (1322) has been shared if the interpretation result of the third message (1322) indicates a new TXOP length. Alternatively, the shared AP (1302) determines that the TXOP (1316) of the TXOP interval length indicated by the sharing AP (1300) through the first message (1320) has been shared if the interpretation result of the third message (1322) indicates an intention to reject. At this time, the STAs (AP MLD, non-AP MLD) that have set NAVs after hearing the second message (1330) set NAVs based on the length of the TXOP interval indicated by the second message (1330), and thus can set NAVs for 1314 intervals. However, since TXOP sharing is actually performed during the 1312 interval (or 1316 interval in case of rejection), there is no need for NAV to be set during the difference between the 1314 interval and the 1312 interval (or 1316 interval), and setting NAV like the 1314 interval may be overprotection for STAs.

[0156] A shared AP (1302) that has shared a TXOP can transmit a CF (contention free)-end frame (1334) at the end of a frame exchange sequence (1332) according to the shared TXOP (1312 or 1316) to indicate the end of the frame exchange sequence. The CF-end frame can be used to indicate the end of contention free and to indicate the truncation of a TXOP interval. STAs that receive the CF-end frame (1334) can confirm the end of the frame exchange sequence and reset the NAV or / and attempt medium access. Through transmission of the CF-end frame (1334), efficient resource use based on the shared TXOP interval (1312) as a result of negotiation can be enabled.

[0157] The operations of FIGS. 11 to 13 described above may be performed in combination by at least one operation by the sharing AP or / and the shared AP.

[0158] FIG. 14 is a diagram illustrating an example of the operation of a sharing AP performing at least one embodiment of the present disclosure.

[0159] According to FIG. 14, a sharing AP transmits a first message for TXOP sharing (1400). The first message may be an MU-RTS TXS TF or a control frame, and the interval field or another field of the first message may indicate the length of the shared TXOP interval that the sharing AP wishes to share. The sharing AP receives a second message transmitted by the shared AP corresponding to a response to the first message (1410). The second message may correspond to a CTS or a control frame, and the interval field or another field (referred to as a request TXOP field in FIG. 14, but is not limited thereto) of the second message may indicate the length of the shared TXOP interval proposed by the shared AP. The method for indicating the length of the shared TXOP interval in the second message may follow the method described above.

[0160] The sharing AP, which receives the second message, checks the length of the shared TXOP interval suggested by the shared AP indicated in the second message, and checks whether the length of the suggested shared TXOP interval is acceptable (1420). The length of the shared TXOP interval may be indicated by the duration field or the requested TXOP field. If the sharing AP can accept the length of the suggested TXOP interval, the sharing AP transmits a third message indicating its intention to accept (1440). If the sharing AP cannot accept the length of the suggested TXOP interval, the sharing AP transmits a third message indicating its intention to reject (1450). If there is a proposal to replace the length of the suggested TXOP interval, the sharing AP transmits a third message indicating the length of the suggested TXOP interval (1430). The third message may correspond to a control frame, etc., and the method by which the third message indicates acceptance, rejection, or proposal may follow the method described above.

[0161] 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.

[0162] FIG. 15 is a diagram illustrating an example of the operation of a shared AP performing at least one embodiment of the present disclosure.

[0163] According to FIG. 15, the shared AP receives the first message transmitted by the sharing AP (1500). The first message may be an MU-RTS TXS TF or a control frame, and the interval field or another field of the first message may indicate the length of the shared TXOP interval that the sharing AP wishes to share. The shared AP interprets the first message, checks the length of the shared TXOP interval indicated by the interval field or another field (referred to as the TXOP field in FIG. 15, but is not limited thereto), and compares it with the length of the TXOP interval that it needs (1510).

[0164] If the length of the shared TXOP interval of the first message is equal to the length of the TXOP interval required by the shared AP (or if the difference between the length of the shared TXOP interval of the first message and the length of the TXOP interval required by the shared AP is less than or equal to a certain threshold), the shared AP transmits a second message indicating a value equal to the length of the shared TXOP interval of the first message (1530). Thereafter, the shared AP can exchange messages with its associated STAs within the shared TXOP (1560). Although FIG. 15 illustrates an example in which reception of the third message is omitted if the second message indicates a value equal to the length of the TXOP interval indicated in the first message, the shared AP can also receive a third message from the shared AP. In this case, the third message can indicate acceptance.

[0165] If the length of the shared TXOP interval of the first message is shorter than the length of the TXOP interval required by the shared AP, the shared AP transmits a second message indicating the length of the required TXOP interval (1520). At this time, the length of the shared TXOP interval indicated by the second message may be longer than the length of the TXOP interval indicated by the first message. Alternatively, if the length of the shared TXOP interval of the first message is longer than the length of the TXOP interval required by the shared AP, the shared AP transmits a second message indicating the length of the required TXOP interval (1540). At this time, the length of the shared TXOP interval indicated by the second message may be shorter than the length of the TXOP interval indicated by the first message.

[0166] The shared AP receives a third message as a response to the second message (1550), and determines the length of the shared TXOP interval according to the content of the third message. Specifically, if the third message indicates an intention to accept the length of the TXOP interval proposed by the shared AP, the shared AP confirms that the TXOP has been shared in the length of the TXOP interval proposed by the second message, and if the third message indicates an intention to reject the length of the TXOP interval proposed by the shared AP, the shared AP confirms that the TXOP has been shared in the length of the TXOP interval indicated by the first message. In addition, if the third message indicates a new TXOP interval length, the shared AP confirms that the TXOP has been shared in the length of the TXOP interval indicated by the third message.

[0167] Afterwards, the shared AP performs message exchange with the associated STA in the shared TXOP section (1560).

[0168] 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.

[0169] 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.

[0170] 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. A method performed by a first electronic device of a wireless LAN network, A step of transmitting a first message including information indicating a first length of a transmission opportunity duration (TXOP) period to be shared with a second electronic device; and A step of receiving a second message corresponding to a response to the first message from the second electronic device, A method characterized in that the second message includes information indicating a second length of the TXOP interval proposed by the second electronic device.

2. In the first paragraph, the information indicating the second length of the TXOP section corresponds to a duration field included in the second message or another field, A method characterized in that the second length is indicated as an absolute value of time or as a difference of the first length.

3. In paragraph 1, A method further comprising the step of transmitting a third message to the second electronic device, in response to the second message, the third message including information accepting the proposal for the second length of the TXOP interval, including information rejecting the proposal, or including information indicating a third length of the TXOP interval.

4. In paragraph 3, If the third message includes information accepting the proposal for the second length of the TXOP segment, the TXOP segment of the second length is shared, If the third message includes information rejecting the proposal, the TXOP segment of the first length is shared, A method characterized in that the TXOP section of the third length is shared when the third message includes information indicating the third length in response to the suggestion for the second length of the TXOP section.

5. In a method performed by a second electronic device of a wireless LAN network, A step of receiving a first message including information indicating a first length of a transmission opportunity duration (TXOP) to be shared from a first electronic device; and A step of transmitting a second message corresponding to a response to the first message from the first electronic device, A method characterized in that the second message includes information indicating a second length of the TXOP interval proposed by the second electronic device.

6. In paragraph 5, the information indicating the second length of the TXOP section corresponds to a duration field included in the second message or another field, A method characterized in that the second length is indicated as an absolute value of time or as a difference of the first length.

7. In paragraph 5, A method further comprising the step of receiving, in response to the second message from the first electronic device, a third message comprising information accepting the proposal for the second length of the TXOP interval, information rejecting the proposal, or information indicating a third length of the TXOP interval.

8. In paragraph 7, If the third message includes information accepting the proposal for the second length of the TXOP segment, the TXOP segment of the second length is shared, If the third message includes information rejecting the proposal, the TXOP segment of the first length is shared, A method characterized in that the TXOP section of the third length is shared when information indicating the third length is included in the third message in response to the proposal for the second length of the TXOP section.

9. In a first electronic device of a wireless LAN network, Transmitter and receiver; and Transmit a first message including information indicating a first length of a transmission opportunity duration (TXOP) period to be shared with a second electronic device, A control unit configured to control receiving a second message corresponding to a response to the first message from the second electronic device, A first electronic device, characterized in that the second message includes information indicating a second length of the TXOP interval proposed by the second electronic device.

10. In paragraph 9, the information indicating the second length of the TXOP section corresponds to a duration field included in the second message or another field, A first electronic device characterized in that the second length is indicated as an absolute value of time or as a difference of the first length.

11. In paragraph 9, The first electronic device characterized in that the control unit further controls to transmit a third message to the second electronic device in response to the second message, the third message including information for accepting the proposal for the second length of the TXOP interval, including information for rejecting the proposal, or including information for indicating a third length of the TXOP interval.

12. In paragraph 11, If the third message includes information accepting the proposal for the second length of the TXOP segment, the TXOP segment of the second length is shared, If the third message includes information rejecting the proposal, the TXOP segment of the first length is shared, A first electronic device, characterized in that the TXOP section of the third length is shared when the third message includes information indicating the third length in response to the suggestion for the second length of the TXOP section.

13. In a second electronic device of a wireless LAN network, Transmitter and receiver; and Receive a first message including information indicating a first length of a transmission opportunity duration (TXOP) to be shared from a first electronic device, A control unit configured to control the transmission of a second message corresponding to a response to the first message from the first electronic device, A second electronic device, characterized in that the second message includes information indicating a second length of the TXOP interval proposed by the second electronic device.

14. In paragraph 13, the information indicating the second length of the TXOP section is a duration field included in the second message or corresponds to another field, A second electronic device characterized in that the second length is indicated as an absolute value of time or as a difference of the first length.

15. In paragraph 13, The control unit further controls to receive a third message from the first electronic device in response to the second message, the third message including information for accepting the proposal for the second length of the TXOP interval, including information for rejecting the proposal, or including information for indicating a third length of the TXOP interval. If the third message includes information accepting the proposal for the second length of the TXOP segment, the TXOP segment of the second length is shared, If the third message includes information rejecting the proposal, the TXOP segment of the first length is shared, A second electronic device characterized in that the TXOP section of the third length is shared when information indicating the third length is included in the third message in response to the suggestion for the second length of the TXOP section.

Images