Channel access method and device in wireless LAN system

Abstract

A channel access method and device for a wireless LAN system. According to an embodiment of the present disclosure, a method performed by a station (STA) in a wireless LAN system may include receiving information about a restricted-target wake time (R-TWT) service period (SP) from an access point (AP), and configuring at least one R-TWT traffic identifier (TID) for the R-TWT SP, wherein whether to perform a backoff operation for an access category (AC) within the R-TWT SP may be determined based on a mapping relationship between the at least one R-TWT TID and the AC.

Description

[Technical Field]

[0001] The present disclosure relates to a channel access method and apparatus in a wireless local area network (WLAN) system, and more particularly to a channel access method and apparatus that takes into account a limited target wake time (TWT) service period in a next-generation WLAN system. [Background technology]

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

[0003] To provide a more improved wireless communication environment, improved technologies for Extremely High Throughput (EHT) are being discussed. For example, technologies for increased bandwidth, efficient use of multiple bands, Multiple Input Multiple Output (MIMO) that supports increased spatial streams, and multiple access point (AP) coordination are being researched. In particular, various technologies for supporting traffic with low latency or real-time characteristics are being researched. Furthermore, new technologies for supporting ultra high reliability (UHR), including improvements or extensions to EHT technology, are being discussed. Summary of the Invention [Problem to be solved by the invention]

[0004] A technical problem of the present disclosure is to provide a method and apparatus for performing channel access in a wireless LAN system.

[0005] A further technical problem of the present disclosure is to provide a method and apparatus relating to channel access that takes into account a limited target wake time (TWT) service period in a wireless LAN system.

[0006] The technical problems to be solved by the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the following description. [Means for solving the problem]

[0007] A method performed by a station (STA) in a wireless LAN system according to one embodiment of the present disclosure may include receiving information about a restricted-target wake time (R-TWT) service period (SP) from an access point (AP), and configuring at least one R-TWT traffic identifier (TID) for the R-TWT SP, wherein whether to perform a backoff operation for an access category (AC) in the R-TWT SP may be determined based on a mapping relationship between the at least one R-TWT TID and the AC. [Effects of the Invention]

[0008] According to the present disclosure, a method and apparatus for performing channel access in a wireless LAN system can be provided.

[0009] According to the present disclosure, it is possible to provide a method and apparatus relating to channel access that takes into account a limited target wake time (TWT) service period in a wireless LAN system.

[0010] 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 having ordinary skill in the art to which the present disclosure pertains from the following description. [Brief explanation of the drawings]

[0011] The accompanying drawings, which are included as part of the detailed description to aid in understanding the present disclosure, provide examples for the present disclosure and, together with the detailed description, explain the technical features of the present disclosure.

[0012] [Figure 1] FIG. 1 is a block diagram illustrating a wireless communication device according to an embodiment of the present disclosure.

[0013] [Figure 2] FIG. 1 is a diagram illustrating an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0014] [Figure 3] FIG. 1 is a diagram illustrating a link setup process to which the present disclosure can be applied.

[0015] [Figure 4] FIG. 10 is a diagram illustrating a backoff process to which the present disclosure can be applied.

[0016] [Figure 5] 10A and 10B are diagrams for explaining a CSMA / CA base frame transmission operation to which the present disclosure can be applied.

[0017] [Figure 6]1 is a diagram illustrating an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0018] [Figure 7] FIG. 1 illustrates an example of a PPDU defined in the IEEE 802.11 standard to which the present disclosure is applicable.

[0019] [Figure 8] FIG. 1 is a diagram illustrating an example of a resource unit of a wireless LAN system to which the present disclosure can be applied. [Figure 9] FIG. 1 is a diagram illustrating an example of a resource unit of a wireless LAN system to which the present disclosure can be applied. [Figure 10] FIG. 1 is a diagram illustrating an example of a resource unit of a wireless LAN system to which the present disclosure can be applied.

[0020] [Figure 11] FIG. 1 illustrates an exemplary structure of an HE-SIG-B field.

[0021] [Figure 12] FIG. 1 is a diagram illustrating a MU-MIMO scheme in which multiple users / STAs are assigned to one RU.

[0022] [Figure 13] FIG. 10 is a diagram illustrating an example of a PPDU format to which the present disclosure can be applied.

[0023] [Figure 14] 10A and 10B are diagrams for explaining an example of individual TWT operation to which the present disclosure can be applied.

[0024] [Figure 15] FIG. 10 is a diagram illustrating an example of a broadcast TWT operation to which the present disclosure can be applied.

[0025] [Figure 16]FIG. 10 is a diagram illustrating an example of a TWT information field format.

[0026] [Figure 17] FIG. 10 is a diagram illustrating an example of a TWT information element format.

[0027] [Figure 18] FIG. 10 is a diagram illustrating an example of an individual TWT parameter set field format.

[0028] [Figure 19] FIG. 10 is a diagram illustrating an example of a broadcast TWT parameter set field format.

[0029] [Figure 20] FIG. 1 illustrates a constrained TWT operation to which the present disclosure is applicable.

[0030] [Figure 21] FIG. 10 illustrates a channel access operation in a restricted TWT SP according to an embodiment of the present disclosure.

[0031] [Figure 22] FIG. 10 is a diagram illustrating an operation of a STA that supports a backoff operation in an R-TWT SP according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0032] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The detailed description disclosed below together with the accompanying drawings is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure can be implemented. The detailed description below includes specific details to provide a complete understanding of the present disclosure. However, it will be understood by those skilled in the art that the present disclosure can be implemented without such specific details.

[0033] In some cases, in order to avoid obscuring the concepts of the present disclosure, known structures and devices may be omitted or shown in block diagram form, focusing on the core functions of each structure and device.

[0034] In this disclosure, when a component is "coupled," "coupled," or "connected" to another component, this may include a direct connection as well as an indirect connection where there is another component between them. Also, in this disclosure, the terms "comprise" or "have" specify the presence of stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0035] In this disclosure, terms such as "first" and "second" are used only to distinguish one component from another, and are not used to limit the components, and do not limit the order or importance of the components unless otherwise specified. Therefore, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0036] The terms used in this disclosure are for the purpose of describing particular embodiments and are not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular is intended to include the plural unless the context clearly dictates otherwise. The term "and / or" as used in this disclosure means that one of the associated listed items may be included, or that any and all possible combinations of two or more of them are included. Also, in this disclosure, " / " between words has the same meaning as "and / or" unless otherwise specified.

[0037] The examples of the present disclosure may be applied to various wireless communication systems. For example, the examples of the present disclosure may be applied to a wireless LAN system. For example, the examples of the present disclosure may be applied to an IEEE 802.11a / g / n / ac / ax standard-based wireless LAN. Note that the examples of the present disclosure may be applied to a newly proposed IEEE 802.11be (or EHT) standard-based wireless LAN. The examples of the present disclosure may be applied to an IEEE 802.11be Release-2 standard-based wireless LAN, which corresponds to a further improvement technology of the IEEE 802.11be Release-1 standard. Furthermore, the examples of the present disclosure may be applied to a next-generation standard-based wireless LAN after IEEE 802.11be. The examples of the present disclosure may also be applied to a cellular wireless communication system. For example, the examples of the present disclosure may be applied to a cellular wireless communication system based on the Long Term Evolution (LTE) series technology and the 5G New Radio (NR) series technology of the 3GPP (registered trademark) standard.

[0038] Below, technical features to which the examples of the present disclosure can be applied will be described.

[0039] FIG. 1 is a block diagram illustrating a wireless communication device according to an embodiment of the present disclosure.

[0040] 1 may be referred to by various terms such as a terminal, a wireless device, a wireless transmit receive unit (WTRU), a user equipment (UE), a mobile station (MS), a user terminal (UT), a mobile subscriber station (MSS), a mobile subscriber unit (MSS), a subscriber station (SS), an advanced mobile station (AMS), a wireless terminal (WT), or simply a user. In addition, the first device 100 and the second device 200 may be referred to by various terms such as an access point (AP), a base station (BS), a fixed station, a Node B, a base transceiver system (BTS), a network, an artificial intelligence (AI) system, a road side unit (RSU), a repeater, a router, a relay, a gateway, etc.

[0041] The devices 100 and 200 illustrated in FIG. 1 may also be referred to as stations (STAs). For example, the devices 100 and 200 illustrated in FIG. 1 may be referred to by various terms, such as a transmitting device, a receiving device, a transmitting STA, or a receiving STA. For example, the STAs 110 and 200 may serve as an access point (AP) or a non-AP. That is, in the present disclosure, the STAs 110 and 200 may have AP and / or non-AP functionality. When the STAs 110 and 200 have AP functionality, they may simply be referred to as APs, and when the STAs 110 and 200 have non-AP functionality, they may simply be referred to as STAs. Also, in the present disclosure, an AP may be referred to as an AP STA.

[0042] 1, a first device 100 and a second device 200 may transmit and receive wireless signals using various wireless LAN technologies (e.g., the IEEE 802.11 family). The first device 100 and the second device 200 may include interfaces for a medium access control (MAC) layer and a physical layer (PHY) in accordance with the IEEE 802.11 standard.

[0043] In addition, the first device 100 and the second device 200 may further support various communication standards (e.g., 3GPP LTE series, 5G NR series standards, etc.) other than WLAN technology. Furthermore, the devices of the present disclosure may be embodied as various devices such as mobile phones, vehicles, personal computers, augmented reality (AR) equipment, and virtual reality (VR) equipment. Furthermore, the STAs of the present disclosure may support various communication services such as voice calls, video calls, data communications, autonomous driving, machine-type communication (MTC), machine-to-machine (M2M), device-to-device (D2D), and Internet-of-Things (IoT).

[0044] The first device 100 includes one or more processors 102 and one or more memories 104, and may additionally include one or more transceivers 106 and / or one or more antennas 108. The processor 102 may be configured to control the memory 104 and / or the transceiver 106 to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts of the present disclosure. For example, the processor 102 may process information in the memory 104 to generate first information / signals, and then transmit a wireless signal including the first information / signals via the transceiver 106. The processor 102 may also receive a wireless signal including second information / signals via the transceiver 106, and then store information obtained from signal processing of the second information / signals in the memory 104. The memory 104 may be coupled to the processor 102 and may store various information related to the operation of the processor 102. For example, the memory 104 may store software code including instructions for executing some or all of the processes controlled by the processor 102 or for implementing the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts in this disclosure. Here, the processor 102 and the memory 104 may be part of a communications modem / circuit / chip designed to implement wireless LAN technology (e.g., the IEEE 802.11 series). The transceiver 106 may be coupled to the processor 102 and may transmit and / or receive wireless signals via one or more antennas 108. The transceiver 106 may include a transmitter and / or a receiver. The transceiver 106 may be used interchangeably with an RF (Radio Frequency) unit. In this disclosure, a device may also refer to a communications modem / circuit / chip.

[0045] The second device 200 includes one or more processors 202, one or more memories 204, and may additionally include one or more transceivers 206 and / or one or more antennas 208. The processor 202 may be configured to control the memory 204 and / or the transceiver 206 to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure. For example, the processor 202 may process information in the memory 204 to generate third information / signal, and then transmit a wireless signal including the third information / signal via the transceiver 206. The processor 202 may also receive a wireless signal including fourth information / signal via the transceiver 206, and then store information obtained from signal processing of the fourth information / signal in the memory 204. The memory 204 may be coupled to the processor 202 and may store various information related to the operation of the processor 202. For example, the memory 204 may store software code including instructions for executing some or all of the processes controlled by the processor 202 or for implementing the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure. Here, the processor 202 and the memory 204 may be part of a communications modem / circuit / chip designed to implement wireless LAN technology (e.g., the IEEE 802.11 series). The transceiver 206 may be coupled to the processor 202 and may transmit and / or receive wireless signals via one or more antennas 208. The transceiver 206 may include a transmitter and / or a receiver. The transceiver 206 may be used interchangeably with an RF unit. In this disclosure, a device may also refer to a communications modem / circuit / chip.

[0046] The hardware elements of the devices 100 and 200 are described in more detail below. Without limitation, one or more protocol layers may be implemented by one or more processors 102 and 202. For example, one or more processors 102 and 202 may implement one or more layers (e.g., the same functional layer, such as PHY or MAC). The one or more processors 102 and 202 may generate one or more protocol data units (PDUs) and / or one or more service data units (SDUs) according to the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams in this disclosure. The one or more processors 102 and 202 may generate messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams in this disclosure. The one or more processors 102, 202 can generate and provide signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the functions, procedures, suggestions, and / or methods of this disclosure to the one or more transceivers 106, 206. The one or more processors 102, 202 can receive signals (e.g., baseband signals) from the one or more transceivers 106, 206 and obtain the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts of this disclosure.

[0047] The one or more processors 102, 202 may be referred to as a controller, microcontroller, microprocessor, or microcomputer. The one or more processors 102, 202 may be implemented using hardware, firmware, software, or a combination thereof. As an example, the one or more processors 102, 202 may include one or more application-specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs). The descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to execute the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in this disclosure may be included in one or more processors 102, 202 or stored in one or more memories 104, 204 and executed by one or more processors 102, 202. The descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in this disclosure may be embodied by firmware or software in the form of code, instructions, and / or collections of instructions.

[0048] One or more memories 104, 204 may be coupled to one or more processors 102, 202 and may store various types of data, signals, messages, information, programs, code, instructions, and / or instructions. The one or more memories 104, 204 may be comprised of ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories 104, 204 may be located internal and / or external to the one or more processors 102, 202. Additionally, the one or more memories 104, 204 may be coupled to the one or more processors 102, 202 via various techniques, such as wired or wireless connections.

[0049] One or more transceivers 106, 206 may transmit user data, control information, wireless signals / channels, etc., as referred to in the methods and / or operational flowcharts of the present disclosure, to one or more other devices. One or more transceivers 106, 206 may receive user data, control information, wireless signals / channels, etc., as referred to in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts of the present disclosure, from one or more other devices. For example, one or more transceivers 106, 206 may be coupled to one or more processors 102, 202 and may transmit and receive wireless signals. For example, one or more processors 102, 202 may control one or more transceivers 106, 206 to transmit user data, control information, or wireless signals to one or more other devices. Also, one or more processors 102, 202 may control one or more transceivers 106, 206 to receive user data, control information, or wireless signals from one or more other devices. Furthermore, one or more transceivers 106, 206 may be coupled to one or more antennas 108, 208, and the one or more transceivers 106, 206 may be configured to transmit and receive user data, control information, wireless signals / channels, etc., referred to in the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure, via the one or more antennas 108, 208. In this disclosure, the one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). The one or more transceivers 106, 206 may convert the received user data, control information, wireless signals / channels, etc., from RF band signals to baseband signals for processing using one or more processors 102, 202. The one or more transceivers 106, 206 may convert the user data, control information, wireless signals / channels, etc., processed using one or more processors 102, 202, from baseband signals to RF band signals. To that end, one or more of the transceivers 106, 206 may include (analog) oscillators and / or filters.

[0050] For example, one of the STAs 100 and 200 may perform operations intended for an AP, and the other of the STAs 100 and 200 may perform operations intended for a non-AP STA. For example, the transceivers 106 and 206 in FIG. 1 may perform operations for transmitting and receiving signals (e.g., packets or PPDUs (Physical Layer Protocol Data Units) conforming to IEEE 802.11a / b / g / n / ac / ax / be, etc.). In addition, in the present disclosure, operations for various STAs to generate transmission / reception signals or to perform data processing or calculations in advance for transmission / reception signals may be performed by the processors 102 and 202 in FIG. 1. For example, examples of operations for generating transmission / reception signals or performing data processing or calculations in advance for transmission / reception signals may include: 1) operations for determining / obtaining / configuring / calculating / decoding / encoding bit information of fields included in a PPDU (SIG (signal), STF (short training field), LTF (long training field), Data, etc.); 2) operations for determining / configuring / obtaining time resources and frequency resources (e.g., subcarrier resources) to be used for fields included in a PPDU (SIG, STF, LTF, Data, etc.); 3) operations for determining / configuring / obtaining specific sequences (e.g., pilot sequences, STF / LTF sequences, extra sequences applied to SIG) to be used for fields included in a PPDU (SIG, STF, LTF, Data, etc.); 4) power control operations and / or power saving operations applied to STAs; and 5) operations related to determining / obtaining / configuring / calculating / decoding / encoding ACK signals, etc. In addition, in the example below, various information (e.g., information regarding fields / subfields / control fields / parameters / power, etc.) used by various STAs to determine / acquire / configure / calculate / decode / encode transmitted / receive signals may be stored in memories 104, 204 of FIG. 1.

[0051] Hereinafter, downlink (DL) refers to a link for communication from an AP STA to a non-AP STA, and downlink PPDUs / packets / signals, etc. may be transmitted and received via the downlink. In downlink communication, the transmitter may be part of the AP STA, and the receiver may be part of the non-AP STA. Uplink (UL) refers to a link for communication from a non-AP STA to an AP STA, and uplink PPDUs / packets / signals, etc. may be transmitted and received via the uplink. In uplink communication, the transmitter may be part of the non-AP STA, and the receiver may be part of the AP STA.

[0052] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0053] The structure of a WLAN system may be composed of multiple components. The interaction of these components may provide a WLAN that supports STA mobility transparent to higher layers. A Basic Service Set (BSS) is a basic building block of a WLAN. FIG. 2 illustrates two BSSs (BSS1 and BSS2), each including two STAs as members (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2). The ellipses representing BSSs in FIG. 2 may be understood to represent coverage areas where STAs included in the BSSs maintain communication. This area may be referred to as a Basic Service Area (BSA). If a STA moves outside a BSA, it will no longer be able to directly communicate with other STAs within the BSA.

[0054] Ignoring the DS shown in FIG. 2, the most basic type of BSS in a WLAN is the Independent BSS (IBSS). For example, an IBSS may have a minimal configuration consisting of only two STAs. For example, assuming that other components are omitted, BSS1 consisting of only STA1 and STA2, or BSS2 consisting of only STA3 and STA4, are representative examples of an IBSS. Such a configuration is possible when STAs can communicate directly without an AP. Furthermore, in such a WLAN, a BSS may be configured when needed by the LAN, rather than being configured in advance. This can also be called an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity. That is, in an IBSS, STAs are managed in a distributed manner. In an IBSS, all STAs may be mobile, and connection to a distributed system (DS) is not permitted, forming a self-contained network.

[0055] The membership of STAs in a BSS may change dynamically as STAs join and leave the BSS area, etc. To become a member of a BSS, a STA may join the BSS using a synchronization process. To access all the services of the BSS-based architecture, a STA must be associated with the BSS. Such association may be dynamically configured and may include the use of a Distribution System Service (DSS).

[0056] In a wireless LAN, direct STA-to-STA distance may be limited by PHY performance. While such distance limits are sufficient in some cases, other situations may require communication between STAs over longer distances. To support extended coverage, a distributed system (DS) may be configured.

[0057] A DS refers to a structure in which BSSs are interconnected. Specifically, as shown in FIG. 2, a BSS may exist as a component of an expanded network composed of multiple BSSs. A DS is a logical concept and may be specified by the characteristics of a distributed system medium (DSM). In this regard, a wireless medium (WM) and a DSM may be logically distinguished. Each logical medium is used for different purposes and by different components. These media are neither limited to being the same nor limited to being different. The flexibility of a WLAN structure (DS structure or other network structure) can be explained by the fact that multiple media are logically distinct from one another. That is, a WLAN structure may be embodied in various ways, and the WLAN structure may be independently specified according to the physical characteristics of each implementation.

[0058] The DS can support mobile devices by providing seamless integration of multiple BSSs and logical services necessary for addressing destinations. The DS may also include a portal component that acts as a bridge between the wireless LAN and other networks (e.g., IEEE 802.X).

[0059] An AP is an entity that allows associated non-AP STAs to access the DS through the WM and also has the functionality of an STA. Data can be transferred between a BSS and a DS via the AP. For example, STA2 and STA3 shown in FIG. 2 have the functionality of an STA and provide the function of allowing associated non-AP STAs (STA1 and STA4) to access the DS. Furthermore, since all APs essentially correspond to STAs, all APs are addressable entities. The address used by an AP for communication on the WM does not necessarily have to be the same as the address used by the AP for communication on the DSM. A BSS consisting of an AP and one or more STAs can be called an infrastructure BSS.

[0060] Data transmitted from one of the STAs associated with an AP to the STA address of that AP is always received on the uncontrolled port and may be processed by the IEEE 802.1X port access entity, and once the controlled port is authenticated, the transmitted data (or frame) may be delivered to the DS.

[0061] In the above-described DS structure, an Extended Service Set (ESS) may be configured to provide wider coverage.

[0062] An ESS is a network of arbitrary size and complexity composed of a DS and a BSS. An ESS can be a collection of BSSs connected to one DS. However, an ESS does not include a DS. An ESS network is characterized by appearing as an IBSS at the Logical Link Control (LLC) layer. STAs included in an ESS can communicate with each other, and mobile STAs can move from one BSS to another (within the same ESS) transparently to the LLC. APs included in one ESS may have the same service set identification (SSID). An SSID is distinct from a BSSID, which is an identifier for a BSS.

[0063] A WLAN system does not make any assumptions about the relative physical locations of BSSs and can have any of the following configurations: BSSs may partially overlap, which is a configuration commonly used to provide continuous coverage; BSSs may not be physically connected, and there is no logical limit to the distance between BSSs; BSSs may be physically located in the same location, which may be used to provide redundancy; and one (or more) IBSS or ESS networks may physically exist in the same space as one (or more) ESS networks. This may apply to ESS network configurations when an ad-hoc network operates in the location where the ESS network exists, when physically overlapping wireless networks are formed by different organizations, or when two or more different access and security policies are required in the same location.

[0064] FIG. 3 is a diagram illustrating a link setup process to which the present disclosure can be applied.

[0065] In order for an STA to set up a link to a network and transmit and receive data, it must first discover the network, perform authentication, establish an association, and perform authentication procedures for security. The link setup process can also be called a session initiation process or a session setup process. In addition, the discovery, authentication, association, and security configuration processes of the link setup process can also be collectively called the association process.

[0066] In step S310, the STA may perform a network discovery operation. The network discovery operation may include a scanning operation of the STA. That is, in order for the STA to access a network, the STA must search for a joinable network. Before joining a wireless network, the STA must identify a compatible network. The process of identifying networks present in a specific area is called scanning.

[0067] Scanning methods include active scanning and passive scanning. FIG. 3 illustrates an example of a network discovery operation including an active scanning process. In active scanning, a scanning STA changes channels and transmits a probe request frame to search for nearby APs, and waits for a response. A responder transmits a probe response frame to the STA that transmitted the probe request frame in response to the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame in the BSS of the channel being scanned. In a BSS, the AP transmits beacon frames, so the AP is the responder. In an IBSS, the STAs in the IBSS transmit beacon frames alternately, so the responder is not constant. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store the BSS-related information contained in the received probe response frame, move to the next channel (e.g., channel 2), and perform scanning in the same manner (i.e., send and receive probe requests / responses on channel 2).

[0068] Although not shown in FIG. 3, the scanning operation may be performed in a passive scanning manner. In passive scanning, a scanning STA waits for a beacon frame while changing channels. A beacon frame is a management frame defined in IEEE 802.11 and is periodically transmitted to announce the existence of a wireless network and allow a scanning STA to search for and join the wireless network. In a BSS, the AP is responsible for periodically transmitting beacon frames, while in an IBSS, STAs within the IBSS transmit beacon frames in turn. When a scanning STA receives a beacon frame, it saves the BSS-related information included in the beacon frame and records the beacon frame information on each channel as it moves to other channels. A STA that receives a beacon frame saves the BSS-related information included in the received beacon frame, moves to the next channel, and scans the next channel in the same manner. Comparing active scanning with passive scanning, active scanning has the advantage of having a smaller delay and power consumption than passive scanning.

[0069] After the STA discovers the network, an authentication process may be performed in step S320. This authentication process may be called a first authentication process to clearly distinguish it from the security setup operation in step S340, which will be described later.

[0070] The authentication process involves a STA sending an authentication request frame to an AP, and the AP responding by sending an authentication response frame to the STA. The authentication frame used for the authentication request / response corresponds to a management frame.

[0071] 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), a Finite Cyclic Group, etc. These are only examples of information that may be included in an authentication request / response frame, and other information may be substituted or additional information may be included.

[0072] The STA can send an authentication request frame to the AP. The AP can determine whether to allow authentication for the STA based on the information contained in the received authentication request frame. The AP can provide the STA with the result of the authentication process using an authentication response frame.

[0073] After the STA is successfully authenticated, an association process may be performed in step S330. The association process includes the STA sending an association request frame to the AP, and the AP responding by sending an association response frame to the STA.

[0074] For example, the association request frame may include information on various capabilities, a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, an RSN, a mobility domain, supported operating classes, a Traffic Indication Map Broadcast request, interworking service capabilities, etc. For example, the association response frame may include information on various capabilities, a status code, an association ID (AID), supported rates, an Enhanced Distributed Channel Access (EDCA) parameter set, a Received Channel Power Indicator (RCPI), a Received Signal to Noise Indicator (RSNI), a mobility domain, a timeout interval (e.g., an association comeback time), overlapping BSS scan parameters, a TIM broadcast response, a Quality of Service (QoS) map, etc. This corresponds to an example of some of the information that may be included in the association request / response frame, and other information may be substituted or additional information may be included.

[0075] After the STA is successfully connected to the network, a security setup process may be performed in step S340. The security setup process in step S340 may also be referred to as an authentication process using a Robust Security Network Association (RSNA) request / response, and the authentication process in step S320 may be referred to as a first authentication process, and the security setup process in step S340 may simply be referred to as an authentication process.

[0076] The security setup process of step S340 may include a process of performing private key setup using, for example, four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame, and may also be performed using a security method not defined in the IEEE 802.11 standard.

[0077] FIG. 4 is a diagram illustrating a backoff process to which the present disclosure can be applied.

[0078] In wireless LAN systems, the basic access mechanism of MAC (Medium Access Control) is the Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) mechanism, also known as the Distributed Coordination Function (DCF) of IEEE 802.11 MAC, which basically employs a "listen before talk" access mechanism. 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 medium for a predetermined time period (e.g., a DCF Inter-Frame Space (DIFS)) before starting transmission. If the sensing result indicates that the medium is in an idle status, the AP and / or STA can start transmitting a frame over the medium. On the other hand, if the medium is detected as occupied or busy, the AP and / or STA can wait for a delay period (e.g., a random backoff period) for medium access without starting its own transmission, and then attempt to transmit a frame. By applying the random backoff period, multiple STAs are expected to wait for different periods of time before attempting to transmit a frame, thereby minimizing collisions.

[0079] The IEEE 802.11 MAC protocol also provides a Hybrid Coordination Function (HCF). HCF is based on the DCF and Point Coordination Function (PCF). PCF is a polling-based synchronous access method that periodically polls all receiving APs and / or STAs to receive data frames. HCF also includes Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA). EDCA is a contention-based access method for a provider to provide data frames to multiple users, while HCCA is a non-contention-based channel access method using a polling mechanism. HCF also includes a medium access mechanism for improving the quality of service (QoS) of wireless LANs, and can transmit QoS data in both a contention period (CP) and a contention-free period (CFP).

[0080] The operation based on the random backoff period will be described with reference to FIG. 4. When an occupied / busy medium changes to an idle state, multiple STAs can attempt to transmit data (or frames). As a method for minimizing collisions, each STA can select a random backoff count and attempt transmission after waiting for the corresponding slot time. The random backoff count has a pseudo-random integer value and may be determined to be one of the values ​​in the range of 0 to CW. Here, CW is the contention window parameter value. The CW parameter is given a CWmin as its initial value, but can be doubled in the event of a transmission failure (e.g., if an ACK for a transmitted frame is not received). When the CW parameter value reaches CWmax, data transmission can be attempted while maintaining the CWmax value until data transmission is successful, and if data transmission is successful, it is reset to the CWmin value. The CW, CWmin, and CWmax values ​​are set to 2. n Preferably it is set to -1 (n=0,1,2,...).

[0081] When the random backoff process begins, the STA continuously monitors the medium while counting down the backoff slots according to the determined backoff count value. If the medium is monitored as occupied, the STA stops counting down and waits. If the medium becomes idle, the STA resumes the remaining countdown.

[0082] In the example of FIG. 4, when a packet to be transmitted arrives at the MAC of STA3, STA3 confirms that the medium is idle for DIFS and can immediately transmit a frame. The remaining STAs monitor the medium for occupied / busy status and wait. Meanwhile, STA1, STA2, and STA5 may each have data to transmit. If each STA monitors the medium as idle, it waits for DIFS and then counts down its backoff slots according to its random backoff count value. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. That is, this example illustrates a case where, at the time STA2 finishes its backoff count and begins frame transmission, STA5's remaining backoff time is shorter than STA1's remaining backoff time. STA1 and STA5 pause their countdowns and wait while STA2 occupies the medium. When STA2's occupation ends and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume their backoff counts. That is, STA5 can start frame transmission after counting down the remaining backoff slots equal to the remaining backoff time. Because STA5's remaining backoff time is shorter than STA1's, STA5 begins frame transmission. While STA2 is occupying the medium, STA4 may also have data to transmit. From STA4's perspective, when the medium becomes idle, it waits for DIFS, then counts down the random backoff count value it selected, and can begin frame transmission. The example in FIG. 4 shows a case where STA5's remaining backoff time happens to match STA4's random backoff count value, which may result in a collision between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 will receive an ACK, resulting in a failed data transmission. In this case, STA4 and STA5 can double their CW values, select a random backoff count value, and then count down.STA1 waits while the medium is occupied by transmissions from STA4 and STA5, but when the medium becomes idle, it waits for DIFS and can begin frame transmission once the remaining backoff time has elapsed.

[0083] As shown in the example of Figure 4, a data frame is a frame used for transmitting data to be forwarded to a higher layer, and may be transmitted after a backoff that occurs after a DIFS has elapsed since the medium became idle. Furthermore, a management frame is a frame used for exchanging management information that is not forwarded to a higher layer, and is transmitted after a backoff that occurs after an IFS, such as a DIFS or a PIFS (Point Coordination Function IFS). Subtype frames of management frames include a beacon, an association request / response, a re-association request / response, a probe request / response, and an authentication request / response. A control frame is a frame used to control access to a medium. Subtype frames of control frames include Request-To-Send (RTS), Clear-To-Send (CTS), Acknowledgment (ACK), Power Save-Poll (PS-Poll), BlockAck, BlockACKReq, null data packet announcement (NDP), and Trigger. If a control frame is not a response frame to a previous frame, it is transmitted after a backoff that occurs after a DIFS has elapsed. If a control frame is a response frame to a previous frame, it is transmitted without a backoff after a short IFS (SIFS). The type and subtype of a frame may be identified by the type field and subtype field in the Frame Control (FC) field.

[0084] A Quality of Service (QoS) STA can transmit a frame after backing off after the arbitration IFS (AIFS) for the access category (AC) to which the frame belongs, i.e., AIFS[i] (where i is a value determined by the AC), has elapsed. Here, a frame that can use AIFS[i] can be a data frame, a management frame, or a control frame that is not a response frame.

[0085] FIG. 5 is a diagram for explaining a CSMA / CA base frame transmission operation to which the present disclosure can be applied.

[0086] As mentioned above, the CSMA / CA mechanism includes not only physical carrier sensing, in which a STA directly senses the medium, but also virtual carrier sensing. Virtual carrier sensing is intended to compensate for problems that may occur in medium access, such as the hidden node problem. For virtual carrier sensing, the MAC of a STA can use a network allocation vector (NAV). The NAV is a value that indicates to other STAs the time remaining until the medium becomes available for use by a STA currently using or authorized to use the medium. Therefore, the value set as the NAV corresponds to the period during which the STA transmitting the frame plans to use the medium, and STAs receiving the NAV value are prohibited from accessing the medium during that period. For example, the NAV may be set based on the value of the "duration" field in the MAC header of the frame.

[0087] In the example of FIG. 5, it is assumed that STA1 is attempting to transmit data to STA2, and STA3 is in a position where it can overhear some or all of the frames transmitted between STA1 and STA2.

[0088] In order to reduce the possibility of collisions between transmissions from multiple STAs in a CSMA / CA-based frame transmission operation, a mechanism using RTS / CTS frames may be applied. In the example of FIG. 5, while STA1 is transmitting, STA3 may determine that the medium is idle as a result of carrier sensing. That is, STA1 may be a hidden node to STA3. Alternatively, in the example of FIG. 5, while STA2 is transmitting, STA3 may determine that the medium is idle as a result of carrier sensing. That is, STA2 may be a hidden node to STA3. By exchanging RTS / CTS frames before data transmission and reception between STA1 and STA2, STAs outside the transmission range of either STA1 or STA2, or outside the carrier sensing range for transmissions from STA1 or STA3, can be prevented from attempting to occupy the channel during data transmission and reception between STA1 and STA2.

[0089] Specifically, STA1 can determine whether a channel is occupied or not using carrier sensing. In terms of physical carrier sensing, STA1 can determine whether a channel is occupied or idle based on the energy magnitude or signal correlation detected from the channel. In terms of virtual carrier sensing, STA1 can determine whether a channel is occupied or idle using a network allocation vector (NAV) timer.

[0090] When the channel is idle in DIFS, STA1 can send an RTS frame to STA2 after backing off. When STA2 receives the RTS frame, it can send a CTS frame to STA1 as a response to the RTS frame after SIFS.

[0091] If STA3 cannot overhear the CTS frame from STA2 but can overhear the RTS frame from STA1, STA3 can use the duration information included in the RTS frame to set a NAV timer for the frame transmission period (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame) that will be transmitted subsequently. Alternatively, if STA3 cannot overhear the RTS frame from STA1 but can overhear the CTS frame from STA2, STA3 can use the duration information included in the CTS frame to set a NAV timer for the frame transmission period (e.g., SIFS + data frame + SIFS + ACK frame) that will be transmitted subsequently. That is, if STA3 can overhear one or more RTS or CTS frames from at least one of STA1 and STA2, it can set a NAV based thereon. If STA3 receives a new frame before the NAV timer expires, it can update the NAV timer using the duration information included in the new frame. STA3 does not attempt channel access until the NAV timer expires.

[0092] When STA1 receives a CTS frame from STA2, it can transmit a data frame to STA2 SIFS after the completion of reception of the CTS frame. When STA2 successfully receives a data frame, it can transmit an ACK frame, which is a response to the data frame, to STA1 SIFS after the completion of reception of the CTS frame. When STA3's NAV timer expires, it can use carrier sensing to determine whether the channel is in use. If STA3 determines that the channel is not in use by another terminal within DIFS after the expiration of the NAV timer, it can attempt channel access after the contention window (CW) with random backoff has elapsed.

[0093] FIG. 6 is a diagram illustrating an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0094] The PHY layer can prepare an MPDU (MAC PDU) to be transmitted based on an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer. For example, when the PHY layer receives a command from the MAC layer requesting the start of PHY layer transmission, the PHY layer switches to transmission mode and transmits information (e.g., data) provided by the MAC layer in the form of a frame. In addition, when the PHY layer detects a valid preamble in a received frame, it monitors the preamble header and sends a command to the MAC layer informing the start of PHY layer reception.

[0095] Thus, information transmission / reception in a wireless LAN system is performed in the form of frames, and for this purpose, a PHY layer protocol data unit (PPDU) frame format is defined.

[0096] A basic PPDU frame may include a Short Training Field (STF), a Long Training Field (LTF), a Signal (SIG) field, and a Data field. The most basic (e.g., non-High Throughput (HT)) PPDU frame format may consist of only a Legacy-STF (L-STF), a Legacy-LTF (L-LTF), a SIG field, and a Data field. Depending on the type of PPDU frame format (e.g., HT-mixed format PPDU, HT-greenfield format PPDU, Very High Throughput (VHT) PPDU, etc.), additional (or other types of) STF, LTF, and SIG fields may be included between the SIG field and the Data field (this will be described later with reference to FIG. 7).

[0097] The STF is a signal for signal detection, AGC (Automatic Gain Control), diversity selection, precise time synchronization, etc., and the LTF is a signal for channel estimation, frequency error estimation, etc. The STF and LTF can be said to be signals for synchronization and channel estimation of the OFDM physical layer.

[0098] The SIG field may include a RATE field, a LENGTH field, etc. The RATE field may include information about the modulation and coding rate of the data. The LENGTH field may include information about the length of the data. Furthermore, the SIG field may include a parity bit, a SIG TAIL bit, etc.

[0099] The data field may include a SERVICE field, a PSDU (Physical layer Service Data Unit), a PPDU TAIL bit, and, if necessary, padding bits. Some bits of the SERVICE field may be used for synchronization of a descrambler at the receiving end. The PSDU corresponds to a MAC PDU defined in the MAC layer and may contain data generated / used by a higher layer. The PPDU TAIL bit may be used to return the encoder to a 0 state. The padding bits may be used to adjust the length of the data field to a predetermined unit.

[0100] The MAC PDU is defined by various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a Frame Check Sequence (FCS). The MAC frame is composed of the MAC PDU and may be transmitted / received by the PSDU in the data portion of the PPDU frame format.

[0101] The MAC header includes a Frame Control field, a Duration / ID field, an Address field, etc. The Frame Control field may include control information required for frame transmission / reception. The Duration / ID field may be set to the time for transmitting the frame, etc. For specific contents of the Sequence Control, QoS Control, and HT Control subfields of the MAC header, please refer to the IEEE 802.11 standard document.

[0102] The null data packet (NDP) frame format refers to a frame format that does not include a data packet. That is, the NDP frame refers to a frame format that includes a PLCP (physical layer convergence procedure) header portion (i.e., STF, LTF, and SIG fields) in a general PPDU frame format, but does not include the remaining portion (i.e., data field). The NDP frame can also be referred to as a short frame format.

[0103] FIG. 7 is a diagram illustrating an example of a PPDU defined in the IEEE 802.11 standard to which the present disclosure is applicable.

[0104] Various types of PPDUs are used in standards such as IEEE 802.11a / g / n / ac / ax. The basic PPDU format (IEEE 802.11a / g) includes an L-LTF, an L-STF, an L-SIG, and a Data field. The basic PPDU format can also be called a non-HT PPDU format.

[0105] The HT PPDU format (IEEE 802.11n) further includes HT-SIG, HT-STF, and HT-LFT(s) fields in addition to the basic PPDU format. The HT PPDU format shown in Fig. 7 may be referred to as an HT-mixed format. An HT-greenfield format PPDU may also be defined, which corresponds to a format that does not include L-STF, L-LTF, or L-SIG, but is composed of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTFs, and a Data field (not shown).

[0106] An example of a VHT PPDU format (IEEE 802.11ac) further includes VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format.

[0107] An example of the HE PPDU format (IEEE 802.11ax) further includes the fields Repeated L-SIG (RL-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and Packet Extension (PE) in addition to the basic PPDU format. Depending on the detailed example of the HE PPDU format, some fields may be excluded or their lengths may vary. For example, the HE-SIG-B field is included in the HE PPDU format for multiple users (MU), but not in the HE PPDU format for single users (SU). Also, the HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may be 8 us. The HE Extended Range (ER) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may be 16 us.

[0108] 8 to 10 are diagrams illustrating examples of resource units in a wireless LAN system to which the present disclosure can be applied.

[0109] 8 to 10, a resource unit (RU) defined in a wireless LAN system will be described. An RU may include multiple subcarriers (or tones). An RU may be used when transmitting signals to multiple STAs based on the OFDMA technique. An RU may also be defined when transmitting a signal to one STA. An RU may be used for the STF, LTF, data field, etc. of a PPDU.

[0110] 8 to 10, RUs corresponding to different numbers of tones (i.e., subcarriers) may be used to configure some fields of a 20 MHz, 40 MHz, or 80 MHz X-PPDU (X is HE, EHT, etc.). For example, resources may be allocated in units of RUs indicated for the X-STF, X-LTF, and Data fields.

[0111] FIG. 8 is a diagram illustrating an exemplary arrangement of resource units (RUs) used on a 20 MHz band.

[0112] As shown at the top of Figure 8, 26 units (i.e., units corresponding to 26 tones) may be allocated. Six tones may be used as a guard band in the leftmost band of the 20 MHz band, and five tones may be used as a guard band in the rightmost band of the 20 MHz band. Seven DC tones may be inserted into the center band, i.e., the DC band, leaving 26 units corresponding to 13 tones on each side of the DC band. Other bands may be allocated 26 units, 52 units, or 106 units. Each unit may be allocated for a STA or a user.

[0113] The RU arrangement in Figure 8 can be utilized not only in a multiple user (MU) situation but also in a single user (SU) situation, in which case one 242 unit can be used as shown at the bottom of Figure 8. In this case, three DC tones may be inserted.

[0114] In the example of Figure 8, RUs of various sizes, i.e., 26-RU, 52-RU, 106-RU, 242-RU, etc., are illustrated, but the specific sizes of such RUs may be reduced or expanded. Therefore, the specific size of each RU (i.e., the corresponding number of tones) is not limited in the present disclosure and is merely exemplary. Also, in the present disclosure, the number of RUs within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, ...) may vary depending on the size of the RU. The examples of Figures 9 and / or 10 described below are the same as the example of Figure 8 in that the size and / or number of RUs may be changed.

[0115] FIG. 9 is a diagram illustrating an exemplary arrangement of resource units (RUs) used on a 40 MHz band.

[0116] Just as various sizes of RUs are used in the example of Figure 8, 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, etc. may be used in the example of Figure 9. In addition, five DC tones may be inserted at the center frequency, 12 tones may be used as a guard band in the leftmost band of the 40 MHz band, and 11 tones may be used as a guard band in the rightmost band of the 40 MHz band.

[0117] Also, as shown in the figure, when used for a single user, 484-RU may be used.

[0118] FIG. 10 is a diagram illustrating an exemplary arrangement of resource units (RUs) used on an 80 MHz band.

[0119] Just as various sizes of RUs are used in the examples of Figures 8 and 9, 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, 996-RU, etc. may be used in the example of Figure 10. Furthermore, in an 80 MHz PPDU, the RU arrangements of the HE PPDU and the EHT PPDU may differ from each other, and the example of Figure 10 shows an example of the RU arrangement for an 80 MHz EHT PPDU. In the example of Figure 10, the HE PPDU and the EHT PPDU are the same in that 12 tones are used as a guard band in the leftmost band of the 80 MHz band and 11 tones are used as a guard band in the rightmost band of the 80 MHz band. In the HE PPDU, seven DC tones are inserted into the DC band, and there are two 26-RUs on each side of the DC band, corresponding to 13 tones. In the EHT PPDU, 23 DC tones are inserted into the DC band, and there are two 26-RUs on each side of the DC band. In the HE PPDU, there is one null subcarrier between the 242-RUs outside the center band. In the EHT PPDU, there are five null subcarriers. In the HE PPDU, one 484-RU does not contain a null subcarrier, but in the EHT PPDU, one 484-RU contains five null subcarriers.

[0120] Also, as shown in the figure, when used for a single user, 996-RU may be used, and in this case, five DC tones are inserted, which is common to both the HE PPDU and the EHT PPDU.

[0121] An EHT PPDU of 160 MHz or more may be configured with multiple 80 MHz sub-blocks in Figure 10. The RU allocation for each 80 MHz sub-block may be the same as the RU allocation for the 80 MHz EHT PPDU in Figure 10. When the 80 MHz sub-blocks of a 160 MHz or 320 MHz EHT PPDU are not punctured and the entire 80 MHz sub-block is used as part of an RU or MRU (Multiple RU), the 80 MHz sub-block can use 996 RUs in Figure 10.

[0122] Here, an MRU corresponds to a group of subcarriers (or tones) composed of multiple RUs, and the multiple RUs constituting an MRU may be RUs of the same size or different sizes. For example, a single MRU may be defined as 52+26-tones, 106+26-tones, 484+242-tones, 996+484-tones, 996+484+242-tones, 2×996+484-tones, 3×996-tones, or 3×996+484-tones. Here, the multiple RUs constituting one MRU may correspond to RUs of small size (e.g., 26, 52, 106) or RUs of large size (e.g., 242, 484, 996, etc.). In other words, one MRU including RUs of small size and RUs of large size need not be configured / defined. Furthermore, the multiple RUs constituting one MRU may or may not be contiguous in the frequency domain.

[0123] If an 80 MHz sub-block contains RUs with fewer than 996 tones or if portions of the 80 MHz sub-block are punctured, the 80 MHz sub-block may use an RU placement that excludes 996-tone RUs.

[0124] The RUs of the present disclosure may be used for uplink (UL) and / or downlink (DL) communications. For example, when trigger-based UL-MU communications are performed, a STA (e.g., an AP) transmitting a trigger may use trigger information (e.g., a trigger frame or triggered response scheduling (TRS)) to assign a first RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a first STA and a second RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a second STA. The first STA may then transmit a first trigger-based (TB) PPDU based on the first RU, and the second STA may transmit a second TB PPDU based on the second RU. The first and second TB PPDUs may be transmitted to the AP in the same time interval.

[0125] For example, when a DL MU PPDU is configured, a STA (e.g., an AP) transmitting the DL MU PPDU can assign a first RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a first STA and a second RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a second STA. That is, the transmitting STA (e.g., an AP) can transmit the HE-STF, HE-LTF, and Data fields for the first STA using the first RU within one MU PPDU, and can transmit the HE-STF, HE-LTF, and Data fields for the second STA using the second RU.

[0126] Information about the location of the RU may be signaled in the HE-SIG-B in HE PPDU format.

[0127] FIG. 11 shows an example structure of the HE-SIG-B field.

[0128] As shown in the figure, the HE-SIG-B fields may include common fields and user-specific fields. When HE-SIG-B compression is applied (e.g., in the case of full-bandwidth MU-MIMO transmission), the common fields may not be included in the HE-SIG-B, and the HE-SIG-B content channel may include only user-specific fields. When HE-SIG-B compression is not applied, the common fields may be included in the HE-SIG-B.

[0129] The common field may include information regarding RU allocation (e.g., RU assignment, RUs allocated for MU-MIMO, number of MU-MIMO users (STAs), etc.).

[0130] The common field may include N*8 RU allocation subfields, where N is the number of subfields, and may have a value of 1 for a 20 or 40 MHz MU PPDU, 2 for an 80 MHz MU PPDU, 4 for a 160 MHz or 80+80 MHz MU PPDU, .... One 8-bit RU allocation subfield may indicate the size (26, 52, 106, etc.) and frequency location (or RU index) of the RUs included in the 20 MHz band.

[0131] For example, if the value of the 8-bit RU allocation subfield is 00000000, nine 26-RUs are arranged in order from the leftmost to the rightmost in the example of Figure 8; if the value is 00000001, seven 26-RUs and one 52-RU are arranged in order from the leftmost to the rightmost; and if the value is 00000010, five 26-RUs, one 52-RU, and two 26-RUs are arranged in order from the leftmost to the rightmost.

[0132] As a further example, if the value of the 8-bit RU allocation subfield is 01000y2y1y0, it may indicate that one 106-RU and five 26-RUs are arranged in order from the leftmost to the rightmost in the example of FIG. 8. In this case, multiple users / STAs may be allocated to the 106-RU using the MU-MIMO scheme. Specifically, up to eight users / STAs may be allocated to the 106-RU, and the number of users / STAs allocated to the 106-RU is determined based on the 3-bit information (i.e., y2y1y0). For example, if the 3-bit information (y2y1y0) corresponds to a decimal value N, the number of users / STAs allocated to the 106-RU may be N+1.

[0133] Basically, one user / STA may be assigned to each of multiple RUs, and different users / STAs may be assigned to different RUs. For RUs of a certain size or larger (e.g., 106, 242, 484, 996-tone, etc.), multiple users / STAs may be assigned to one RU, and the MU-MIMO scheme may be applied to the multiple users / STAs.

[0134] The set of user-specific fields contains information on how all users (STAs) of the PPDU decode their payloads. The user-specific fields may contain zero or more user block fields. A non-final user block field contains two user fields (i.e., information used for decoding at two STAs). A final user block field contains one or two user fields. The number of user fields may be indicated by the RU allocation subfield in HE-SIG-B, the number of symbols in HE-SIG-B, or the MU-MIMO user field in HE-SIG-A. The user-specific fields may be encoded separately or independently from the common fields.

[0135] FIG. 12 is a diagram illustrating the MU-MIMO scheme in which multiple users / STAs are assigned to one RU.

[0136] In the example of FIG. 12, assume that the value of the RU allocation subfield is 01000010. This corresponds to the case where y2y1y0=010 in 01000y2y1y0. 010 corresponds to 2 in decimal (i.e., N=2), and can indicate that 3 (=N+1) users are allocated to one RU. In this case, one 106-RU and five 26-RUs may be arranged in order from the leftmost to the rightmost of a specific 20 MHz band / channel. Three users / STAs may be allocated to the 106-RU in a MU-MIMO manner. As a result, a total of eight users / STAs are allocated to the 20 MHz band / channel, and the user-specific field of the HE-SIG-B may include eight user fields (i.e., four user block fields). The eight user fields may be assigned to RUs as shown in FIG. 12.

[0137] The user fields may be configured based on two formats. The user fields for MU-MIMO allocation may be configured in a first format, and the user fields for non-MU-MIMO allocation may be configured in a second format. Referring to the example of FIG. 12, user fields 1 to 3 may be based on the first format, and user fields 4 to 8 may be based on the second format. The first format and the second format may contain bit information of the same length (e.g., 21 bits).

[0138] The user field of the first format (i.e., a format for MU-MIMO allocation) may be configured as follows: For example, among the total 21 bits of one user field, B0 to B10 include identification information of the user (e.g., STA-ID, AID, partial AID, etc.), B11 to B14 include spatial configuration information such as the number of spatial streams for the user, B15 to B18 include modulation and coding scheme (MCS) information applied to the data field of the PPDU, B19 is defined as a reserved field, and B20 may include coding type information (e.g., binary convolutional coding (BCC) or low-density parity check (LDPC)) applied to the data field of the PPDU.

[0139] The user field of the second format (i.e., a format for non-MU-MIMO allocation) may be configured as follows: For example, among the total 21 bits of one user field, B0 to B10 may include identification information of the user (e.g., STA-ID, AID, partial AID, etc.), B11 to B13 may include information on the number of spatial streams (NSTS) applied to the RU, B14 may include information indicating whether beamforming is enabled (or whether a beamforming steering matrix is ​​applied), B15 to B18 may include information on modulation and coding scheme (MCS) applied to the Data field of the PPDU, B19 may include information on whether dual carrier modulation (DCM) is enabled, and B20 may include information on a coding type (e.g., BCC or LDPC) applied to the Data field of the PPDU.

[0140] The MCS, MCS information, MCS index, MCS field, etc. used in the present disclosure may be represented as specific index values. For example, the MCS information may be represented as index 0 to index 11. The MCS information may include information about the constellation modulation type (e.g., BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM, 1024-QAM, etc.) and information about the coding rate (e.g., 1 / 2, 2 / 3, 3 / 4, 5 / 6, etc.). The MCS information may omit information about the channel coding type (e.g., BCC or LDPC).

[0141] FIG. 13 shows an example of a PPDU format to which the present disclosure can be applied.

[0142] 13 may be referred to by various names such as EHT PPDU, transmit PPDU, receive PPDU, first type or Nth type PPDU, etc. For example, the PPDU or EHT PPDU of the present disclosure may be referred to by various names such as transmit PPDU, receive PPDU, first type or Nth type PPDU, etc. Furthermore, the EHT PPDU can be used in an EHT system and / or a new WLAN system that is an improvement over the EHT system.

[0143] The EHT MU PPDU in Figure 13 corresponds to a PPDU that carries one or more data (or PSDUs) for one or more users. That is, the EHT MU PPDU may be used for both SU transmission and MU transmission. For example, the EHT MU PPDU may correspond to a PPDU for one receiving STA or multiple receiving STAs.

[0144] The EHT TB PPDU in Figure 13 omits the EHT-SIG compared to the EHT MU PPDU. A STA that receives a trigger for UL MU transmission (e.g., a trigger frame or TRS) can perform UL transmission based on the EHT TB PPDU format.

[0145] In the example of the EHT PPDU format in FIG. 13, L-STF to EHT-LTF correspond to a preamble or a physical preamble, and may be generated / transmitted / received / acquired / decoded in the physical layer.

[0146] The subcarrier frequency spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields (these are referred to as pre-EHT modulated fields) may be defined as 312.5 kHz. The subcarrier frequency spacing of the EHT-STF, EHT-LTF, Data, and PE fields (these are referred to as EHT modulated fields) may be defined as 78.125 kHz. That is, the tone / subcarrier indexes of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields may be represented in units of 312.5 kHz, and the tone / subcarrier indexes of the EHT-STF, EHT-LTF, Data, and PE fields may be represented in units of 78.125 kHz.

[0147] The L-LTF and L-STF in FIG. 13 may be configured in the same manner as the corresponding fields of the PPDU described in FIGS.

[0148] The L-SIG field in FIG. 13 may be composed of 24 bits and may be used to communicate rate and length information. For example, the L-SIG field may include a 4-bit Rate field, a 1-bit Reserved bit, a 12-bit Length field, a 1-bit Parity field, and a 6-bit Tail field. For example, the 12-bit Length field may include information regarding the length or time duration of the PPDU. For example, the value of the 12-bit Length field may be determined based on the type of PPDU. For example, for a non-HT, HT, VHT, or EHT PPDU, the value of the Length field may be determined as a multiple of 3. For example, for an HE PPDU, the value of the Length field may be determined as a multiple of 3 + 1 or a multiple of 3 + 2.

[0149] For example, the transmitting STA may apply BCC encoding based on a coding rate of 1 / 2 to the 24-bit information in the L-SIG field. The transmitting STA may then obtain 48 BCC-coded bits. BPSK modulation may be applied to the 48 coded bits to generate 48 BPSK symbols. The transmitting STA may map the 48 BPSK symbols to positions excluding pilot subcarriers (e.g., subcarrier indexes −21, −7, +7, +21) and DC subcarriers (e.g., subcarrier index 0). Consequently, the 48 BPSK symbols may be mapped to subcarrier indexes −26 to −22, −20 to −8, −6 to −1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA may further map signals of {−1, −1, −1, 1} to subcarrier indexes {−28, −27, +27, +28}. The signal may be used for channel estimation for the frequency range corresponding to {-28, -27, +27, +28}.

[0150] The transmitting STA can generate an RL-SIG, which is generated identically to the L-SIG. BPSK modulation is applied to the RL-SIG. The receiving STA can determine whether the received PPDU is an HE PPDU or an EHT PPDU based on the presence of the RL-SIG.

[0151] A Universal SIG (U-SIG) may be inserted after the RL-SIG in Fig. 13. The U-SIG may be called various names such as a first SIG field, a first SIG, a first type SIG, a control signal, a control signal field, or a first (type) control signal.

[0152] The U-SIG may include N bits of information and may include information for identifying the type of EHT PPDU. For example, the U-SIG may be configured based on two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., OFDM symbol) for the U-SIG may have a duration of 4 us, and the entire U-SIG may have a duration of 8 us. Each symbol of the U-SIG may be used to transmit 26 bits of information. For example, each symbol of the U-SIG may be transmitted and received based on 52 data tones and 4 pilot tones.

[0153] In the U-SIG (or U-SIG field), for example, A-bit information (e.g., 52 uncoded bits) may be transmitted. The first symbol of the U-SIG (e.g., U-SIG-1) transmits the first X-bit information (e.g., 26 uncoded bits) of the total A-bit information, and the second symbol of the U-SIG (e.g., U-SIG-2) transmits the remaining Y-bit information (e.g., 26 uncoded bits) of the total A-bit information. For example, the transmitting STA may obtain the 26 uncoded bits included in each U-SIG symbol. The transmitting STA may perform convolutional encoding (e.g., BCC encoding) based on a rate of R=½ to generate 52-coded bits and perform interleaving on the 52-coded bits. The transmitting STA may perform BPSK modulation on the interleaved 52-coded bits to generate 52 BPSK symbols assigned to each U-SIG symbol. One U-SIG symbol may be transmitted based on 56 tones (subcarriers) from subcarrier index -28 to subcarrier index +28, excluding DC index 0. The 52 BPSK symbols generated by the transmitting STA may be transmitted based on the remaining tones (subcarriers) excluding the pilot tones -21, -7, +7, and +21.

[0154] For example, the A-bit information (e.g., 52 un-coded bits) transmitted by the U-SIG may include a CRC field (e.g., a 4-bit field) and a tail field (e.g., a 6-bit field). The CRC field and tail field may be transmitted in the second symbol of the U-SIG. The CRC field may be generated based on the 26 bits allocated to the first symbol of the U-SIG and the remaining 16 bits in the second symbol excluding the CRC / tail field, and may be generated based on a conventional CRC calculation algorithm. The tail field may also be used to terminate the trellis of a convolutional decoder and may be set to 0, for example.

[0155] The A-bit information (e.g., 52 uncoded bits) transmitted by the U-SIG (or U-SIG field) can be divided into version-independent bits and version-dependent bits. For example, the size of the version-independent bits may be fixed or variable. For example, the version-independent bits may be assigned only to the first symbol of the U-SIG, or the version-independent bits may be assigned to both the first and second symbols of the U-SIG. For example, the version-independent bits and version-dependent bits may be referred to by various names, such as the first control bit and the second control bit.

[0156] For example, the version-independent bits of the U-SIG may include a 3-bit physical layer version identifier (PHY version identifier). For example, the 3-bit physical layer version identifier may include information about the physical layer version (PHY version) of the transmitted / received PPDU. For example, a first value of the 3-bit physical layer version identifier can indicate that the transmitted / received PPDU is an EHT PPDU. In other words, when transmitting an EHT PPDU, the transmitting STA can set the 3-bit physical layer version identifier to the first value. In other words, the receiving STA can determine that the received PPDU is an EHT PPDU based on the physical layer version identifier having the first value.

[0157] For example, the version independent bits of the U-SIG may include a 1-bit UL / DL flag field, where a first value of the 1-bit UL / DL flag field is associated with UL communication and a second value of the UL / DL flag field is associated with DL communication.

[0158] For example, the version-independent bits of the U-SIG may include information regarding the length of a transmission opportunity (TXOP) and information regarding a BSS color ID.

[0159] For example, when EHT PPDUs are divided into various types (e.g., EHT PPDUs associated with SU mode, EHT PPDUs associated with MU mode, EHT PPDUs associated with TB mode, EHT PPDUs associated with Extended Range transmission, etc.), information regarding the type of EHT PPDU may be included in the version-dependent bits of the U-SIG.

[0160] For example, the U-SIG may include information regarding 1) a bandwidth field containing information regarding the bandwidth, 2) a field containing information regarding the MCS technique applied to the EHT-SIG, 3) an indication field containing information regarding whether the DCM technique is applied to the EHT-SIG, 4) a field containing information regarding the number of symbols used for the EHT-SIG, 5) a field containing information regarding whether the EHT-SIG is generated across the entire band, 6) a field containing information regarding the type of EHT-LTF / STF, and 7) a field indicating the length of the EHT-LTF and the CP length.

[0161] Preamble puncturing may be applied to the PPDU in Figure 13. Preamble puncturing refers to applying puncturing to a portion of the entire bandwidth of the PPDU (e.g., a secondary 20 MHz band). For example, when an 80 MHz PPDU is transmitted, the STA applies puncturing to the secondary 20 MHz band of the 80 MHz band, and can transmit the PPDU only in the primary 20 MHz band and the secondary 40 MHz band.

[0162] For example, the preamble puncturing pattern may be preset. For example, when a first puncturing pattern is applied, puncturing may be applied only to a secondary 20 MHz band within an 80 MHz band. For example, when a second puncturing pattern is applied, puncturing may be applied only to one of two secondary 20 MHz bands included in a secondary 40 MHz band within an 80 MHz band. For example, when a third puncturing pattern is applied, puncturing may be applied only to a secondary 20 MHz band included in a primary 80 MHz band within a 160 MHz band (or an 80+80 MHz band). For example, when a fourth puncturing pattern is applied, a primary 40 MHz band included in a primary 80 MHz band within a 160 MHz band (or an 80+80 MHz band) is present, and puncturing may be applied to at least one 20 MHz channel that does not belong to the primary 40 MHz band.

[0163] Information about preamble puncturing applied to the PPDU may be included in the U-SIG and / or the EHT-SIG, for example, a first field of the U-SIG may include information about the contiguous bandwidth of the PPDU, and a second field of the U-SIG may include information about preamble puncturing applied to the PPDU.

[0164] For example, the U-SIG and EHT-SIG may include information about preamble puncturing based on the following method: When the bandwidth of a PPDU exceeds 80 MHz, the U-SIGs may be individually configured in 80 MHz increments. For example, when the bandwidth of a PPDU is 160 MHz, the PPDU may include a first U-SIG for a first 80 MHz band and a second U-SIG for a second 80 MHz band. In this case, the first field of the first U-SIG may include information about the 160 MHz bandwidth, and the second field of the first U-SIG may include information about the preamble puncturing applied to the first 80 MHz band (i.e., information about the preamble puncturing pattern). Furthermore, the first field of the second U-SIG may include information about the 160 MHz bandwidth, and the second field of the second U-SIG may include information about the preamble puncturing applied to the second 80 MHz band (i.e., information about the preamble puncturing pattern). The EHT-SIG subsequent to the first U-SIG may include information regarding the preamble puncturing applied to the second 80 MHz band (i.e., information regarding the preamble puncturing pattern), and the EHT-SIG subsequent to the second U-SIG may include information regarding the preamble puncturing applied to the first 80 MHz band (i.e., information regarding the preamble puncturing pattern).

[0165] Additionally or alternatively, the U-SIG and the EHT-SIG may include information about preamble puncturing based on the following method: The U-SIG may include information about preamble puncturing for the entire band (i.e., information about the preamble puncturing pattern). That is, the EHT-SIG may not include information about preamble puncturing, and only the U-SIG may include information about preamble puncturing (i.e., information about the preamble puncturing pattern).

[0166] A U-SIG may be configured in 20 MHz units. For example, when an 80 MHz PPDU is configured, a U-SIG may be duplicated. That is, four identical U-SIGs may be included in the 80 MHz PPDU. PPDUs exceeding the 80 MHz bandwidth may contain different U-SIGs.

[0167] 13 may include control information for the receiving STA. The EHT-SIG may be transmitted in at least one symbol, and one symbol may have a length of 4 us. Information regarding the number of symbols used for the EHT-SIG may be included in the U-SIG.

[0168] The EHT-SIG may include the technical features of the HE-SIG-B described in Figures 11 and 12. For example, the EHT-SIG may include a common field and a user-specific field, similar to the example of Figure 8. The common field of the EHT-SIG may be omitted, and the number of user-specific fields may be determined based on the number of users.

[0169] 11, the common fields of the EHT-SIG and the user-specific fields of the EHT-SIG may be coded separately. One user block field included in the user-specific fields contains information for two user fields, but the last user block field included in the user-specific fields may contain one or two user fields. That is, one user block field of the EHT-SIG may contain up to two user fields. As in the example of FIG. 12, each user field may be associated with either a MU-MIMO allocation or a non-MU-MIMO allocation.

[0170] Similar to the example of FIG. 11, the common field of the EHT-SIG may include CRC bits and Tail bits, where the length of the CRC bits may be determined to be 4 bits, and the length of the Tail bits may be determined to be 6 bits and set to 000000.

[0171] 11, the common field of the EHT-SIG may include RU allocation information. The RU allocation information may refer to information about the locations of RUs to which multiple users (i.e., multiple receiving STAs) are assigned. The RU allocation information may be configured in 8-bit (or N-bit) units.

[0172] A mode in which the common field of the EHT-SIG is omitted may be supported. The mode in which the common field of the EHT-SIG is omitted may be called a compressed mode. When the compressed mode is used, multiple users of the EHT PPDU (i.e., multiple receiving STAs) can decode the PPDU (e.g., the data field of the PPDU) based on non-OFDMA. That is, multiple users of the EHT PPDU can decode the PPDU (e.g., the data field of the PPDU) received in the same frequency band. When the non-compressed mode is used, multiple users of the EHT PPDU can decode the PPDU (e.g., the data field of the PPDU) based on OFDMA. That is, multiple users of the EHT PPDU can receive the PPDU (e.g., the data field of the PPDU) in different frequency bands from each other.

[0173] The EHT-SIG may be configured based on various MCS schemes. As described above, information about the MCS scheme applied to the EHT-SIG may be included in the U-SIG. The EHT-SIG may be configured based on the DCM scheme. For example, of N data tones (e.g., 52 data tones) allocated for the EHT-SIG, a first modulation scheme may be applied to consecutive half of the tones, and a second modulation scheme may be applied to the remaining consecutive half of the tones. That is, the transmitting STA may modulate specific control information onto a first symbol based on a first modulation scheme and allocate it to consecutive half of the tones, and modulate the same control information onto a second symbol based on a second modulation scheme and allocate it to the remaining consecutive half of the tones. As described above, information (e.g., a 1-bit field) about whether the DCM scheme is applied to the EHT-SIG may be included in the U-SIG. The EHT-STF of FIG. 13 may be used to improve automatic gain control (AGC) estimation in a MIMO or OFDMA environment. The EHT-LTF of FIG. 13 may be used to estimate a channel in a MIMO environment or an OFDMA environment.

[0174] Information regarding the type of STF and / or LTF (including information regarding the GI (guard interval) applied to the LTF) may be included in the U-SIG field and / or EHT-SIG field of FIG. 13, for example.

[0175] The PPDU in FIG. 13 (ie, the EHT PPDU) may be configured based on the example of the RU arrangement in FIGS.

[0176] For example, an EHT PPDU transmitted on a 20 MHz band, i.e., a 20 MHz EHT PPDU, may be configured based on the RUs in Figure 8. That is, the RU locations of the EHT-STF, EHT-LTF, and data fields included in the EHT PPDU may be determined as shown in Figure 8. An EHT PPDU transmitted on a 40 MHz band, i.e., a 40 MHz EHT PPDU, may be configured based on the RUs in Figure 9. That is, the RU locations of the EHT-STF, EHT-LTF, and data fields included in the EHT PPDU may be determined as shown in Figure 9.

[0177] An EHT PPDU transmitted on the 80 MHz band, i.e., an 80 MHz EHT PPDU, may be configured based on the RU in Figure 10. That is, the RU locations of the EHT-STF, EHT-LTF, and data fields included in the EHT PPDU may be determined as shown in Figure 10. The tone-plan for 80 MHz in Figure 10 may correspond to two repetitions of the tone-plan for 40 MHz in Figure 9.

[0178] The tone plan for 160 / 240 / 320 MHz may be configured to repeat the pattern of FIG. 9 or FIG. 10 multiple times.

[0179] The PPDU in FIG. 13 may be identified as an EHT PPDU based on the following method.

[0180] A receiving STA can determine the type of a received PPDU as an EHT PPDU based on the following: 1) the first symbol after the L-LTF signal of the received PPDU is BPSK; 2) an RL-SIG in which the L-SIG of the received PPDU is repeated is detected; and 3) the result of applying modulo 3 arithmetic to the value of the Length field of the L-SIG of the received PPDU (i.e., the remainder when divided by 3) is detected as 0, the received PPDU may be determined to be an EHT PPDU. If the received PPDU is determined to be an EHT PPDU, the receiving STA can determine the type of EHT PPDU based on bit information included in the symbol after the RL-SIG in FIG. 13. In other words, the receiving STA can determine the type of a received PPDU as an EHT PPDU based on 1) the first symbol after the L-LTF signal, which is BSPK; 2) an RL-SIG that follows the L-SIG field and is identical to the L-SIG; and 3) an L-SIG including a Length field in which the result of applying modulo 3 arithmetic is set to 0.

[0181] For example, the receiving STA may determine that the type of the received PPDU is an HE PPDU based on the following: 1) the first symbol after the L-LTF signal is BPSK, 2) an RL-SIG in which the L-SIG is repeated is detected, and 3) the result of applying modulo 3 to the Length value of the L-SIG is detected as 1 or 2, the received PPDU may be determined to be an HE PPDU.

[0182] For example, the receiving STA can determine the type of the received PPDU as non-HT, HT, or VHT PPDU based on the following: For example, if 1) the first symbol after the L-LTF signal is BPSK, and 2) an RL-SIG in which the L-SIG is repeated is not detected, the received PPDU may be determined to be a non-HT, HT, or VHT PPDU. Also, even if the receiving STA detects a repetition of the RL-SIG, if the result of applying modulo 3 to the length value of the L-SIG is detected to be 0, the received PPDU may be determined to be a non-HT, HT, or VHT PPDU.

[0183] The PPDU in Figure 13 may be used to transmit and receive various types of frames, for example, the PPDU in Figure 13 may be used to (simultaneously) transmit and receive one or more of a control frame, a management frame, or a data frame.

[0184] Below, we will explain TWT (target wake time).

[0185] TWT is a power saving (PS) technology that improves the energy efficiency of non-AP STAs by defining a service period (SP) between the AP and non-AP STAs, sharing information about the SP, and reducing medium contention. A STA that makes a request, suggestion, or demand during the TWT setup phase can be called a TWT requesting STA. An AP that responds to the request with an accept or reject can be called a TWT responding STA. The setup phase may include a process in which the STA requests TWT from the AP, determines the type of TWT operation to be performed, and determines the frame type to be transmitted and received. TWT operations can be divided into individual TWT and broadcast TWT.

[0186] FIG. 14 is a diagram for explaining an example of individual TWT operation to which the present disclosure can be applied.

[0187] Individual TWT is a mechanism for data exchange between an AP and a non-AP STA after negotiation of the non-AP STA's awake / doze status by sending and receiving TWT request / response frames. In the example of FIG. 14, the AP and STA1 can form a trigger-enabled TWT agreement using a TWT request frame and a TWT response frame. Here, the method used by STA1 is the solicited TWT method, in which STA1 sends a TWT request frame to the AP and receives information for TWT operation from the AP using a TWT response frame. Meanwhile, STA2, which uses the unsolicited TWT method, can receive information on the trigger-enabled TWT agreement setting from the AP using an unsolicited TWT response. Specifically, STA2 can calculate the next TWT by adding a specific number to the current TWT value. In a trigger-enabled TWT SP, the AP can send a trigger frame to the STA. The trigger frame can inform the STA that there is buffered data in the AP. In response, STA1 can inform the AP of its awake state by sending a PS-Poll frame. STA2 can inform the AP of its awake state by sending a QoS Null frame. Here, the data frames transmitted by STA1 and STA2 may be in the TB PPDU format. After checking the states of STA1 and STA2, the AP can send a DL MU PPDU to the awake STAs. When the TWT SP expires, STA1 and STA2 may switch to a doze state.

[0188] FIG. 15 is a diagram illustrating an example of a broadcast TWT operation to which the present disclosure can be applied.

[0189] Broadcast TWT is a type of TWT in which a non-AP STA (or TWT scheduling STA) obtains information such as a target beacon transmission time (TBTT) and a listen interval by transmitting and receiving TWT request / response frames to and from an AP (or TWT scheduled STA). Here, a negotiation operation for the TBTT may be performed. Based on this, the AP may define a frame including TWT scheduling information using a beacon frame. In FIG. 15, STA1 performs a solicited TWT operation, and STA2 performs an unsolicited TWT operation. The AP can transmit a DL MU PPDU after confirming the awake state of the STA using a trigger transmitted by itself. This may be the same as the individual TWT process. In broadcast TWT, a trigger-enabled TWT SP including a beacon frame may be repeated multiple times at regular intervals.

[0190] The TWT information may be conveyed by a TWT information frame and a TWT information element.

[0191] FIG. 16 is a diagram illustrating an example of a TWT information element format.

[0192] The TWT information frame is transmitted by a STA to request or deliver information about a TWT agreement and is transmitted by one of the STAs in an existing TWT agreement. The action frame of the TWT information frame includes a TWT information field. The TWT information field may include a 3-bit TWT flow identifier subfield, a 1-bit response requested subfield, a 1-bit next TWT request subfield, a 2-bit next TWT subfield size subfield, a 1-bit all TWT subfield, and a 0 / 32 / 48 / 64-bit next TWT subfield.

[0193] The size of the TWT information field may vary depending on the size of the next TWT field. The TWT flow identifier subfield contains the identifier of the TWT flow for which TWT information is requested or provided. The TWT flow identifier subfield may be reserved if the value of the all TWT subfield is 1.

[0194] The response requested subfield indicates whether the STA transmitting a frame including the TWT information field requests that a TWT information frame be transmitted in response to the frame. If the response requested subfield is set to 0, the STA is requested not to transmit a TWT information frame in response to the frame. If the response requested subfield is set to 1, the STA is requested to transmit a TWT information frame in response to the frame.

[0195] If the next TWT request subfield is set to 1, it may indicate that the TWT information frame is a request for transmission of a TWT information frame containing a next TWT field with a length other than 0. Otherwise, the next TWT request subfield may be set to 0.

[0196] The values ​​of the next TWT subfield size subfield are 0, 1, 2, and 3, which indicate that the size of the next TWT subfield is 0, 32, 48, and 64, respectively.

[0197] The all TWT subfield may be set to 1 to indicate that the TWT information frame reschedules all TWTs. Otherwise, the all TWT subfield may be set to 0.

[0198] The next TWT subfield may have a variable length depending on the value of the next TWT subfield size. The value included in the next TWT subfield may have a value corresponding to the least significant portion of the timing synchronization function (TSF) in the next TWT for the TWT identified by the TWT flow identifier subfield.

[0199] FIG. 17 is a diagram illustrating an example of a TWT information element format.

[0200] The TWT information element may be transmitted and received in a beacon, a probe response, a (re)association response frame, etc. The TWT information element may include an element ID field, a length field, a control field, and a TWT parameter information field.

[0201] The control field of the TWT information element has the same format regardless of whether it is an individual TWT or a broadcast TWT.

[0202] The NDP paging indication subfield may have a value of 1 if the NDP paging field is present and a value of 0 if the NDP paging field is not present.

[0203] The responder PM mode subfield may indicate a Power Management (PM) mode.

[0204] The negotiation type subfield may indicate whether the information contained in the TWT element is for negotiating parameters of the broadcast TWT or individual TWT(s), or for the wake TBTT interval.

[0205] For example, if the negotiation type subfield has a value of 0, the TWT subfield relates to a future individual TWT SP start time, and the TWT element contains one individual TWT parameter set, which may correspond to an individual TWT negotiation between a TWT requesting STA and a TWT responding STA, or an individual TWT announcement by a TWT responder.

[0206] For example, if the negotiation type subfield has a value of 1, the TWT subfield relates to the next TBTT time, and the TWT element contains one individual TWT parameter set, which may correspond to wake TBTT and wake interval negotiation between a TWT-scheduled STA and a TWT-scheduling AP.

[0207] For example, if the negotiation type subfield has a value of 2, the TWT subfield is for a future broadcast TWT SP start time, and the TWT element includes one or more broadcast TWT parameter sets, which may correspond to providing a broadcast TWT schedule to TWT-scheduled STAs by including the TWT element in a broadcast management frame transmitted by the TWT scheduling AP.

[0208] For example, if the negotiation type subfield has a value of 3, the TWT subfield is for a future broadcast TWT SP start time, and the TWT element includes one or more broadcast TWT parameter sets. This may involve managing membership in the broadcast TWT schedule by including the TWT element in an individually addressed management frame transmitted by either the TWT-scheduled STA or the TWT-scheduling AP.

[0209] The TWT information frame disabled subfield, when set to 1, indicates that reception of TWT information frames by the STA is disabled; otherwise, it may be set to 0.

[0210] The Wake Duration Unit subfield indicates the unit of the Nominal Minimum TWT Wake Duration field. The Wake Duration Unit subfield may be set to 0 if the unit is 256us and to 1 if the unit is TU. If the STA is not an HE / EHT STA, the Wake Duration Unit subfield may be set to 0.

[0211] The most significant bit (MSB) of the negotiation type field may correspond to a broadcast field. If the broadcast field is 1, the TWT element may include one or more broadcast TWT parameter sets. If the broadcast field is 0, the TWT element may include only one individual TWT parameter set. A TWT element with the broadcast field set to 1 may be referred to as a broadcast TWT element.

[0212] Fig. 18 is a diagram illustrating an example of an individual TWT parameter set field format, and Fig. 19 is a diagram illustrating an example of a broadcast TWT parameter set field format.

[0213] The TWT parameter information field included in the TWT element in FIG. 17 may have different configurations depending on whether the TWT is an individual TWT or a broadcast TWT.

[0214] If it is an individual TWT, the TWT parameter information field in the TWT element contains a single individual TWT parameter set field.

[0215] For a broadcast TWT, the TWT parameter information field in the TWT element includes one or more broadcast TWT parameter set fields, each of which may include specific information about one broadcast TWT.

[0216] As shown in Figures 18 and 19, the individual TWT parameter set field and the broadcast TWT parameter set field include common subfields.

[0217] The request type subfield may have the same size in the individual TWT parameter set field and the broadcast TWT parameter set field, but may have different detailed configurations, as will be described later.

[0218] The target wake time subfield indicates the start time of a later scheduled individual / broadcast TWT SP.

[0219] The nominal maximum TWT wake duration subfield indicates the minimum unit that the TWT requesting STA expects to wake up to complete a frame exchange associated with the TWT flow identifier in the TWT wake interval duration. Here, the TWT wake interval may refer to the average time between consecutive TWT SPs that the TWT requesting STA expects.

[0220] The TWT Wake Interval Mantissa subfield is the binary value of the TWT wake interval value, which can be expressed in microseconds.

[0221] Referring to FIG. 18, the TWT group assignment subfield, the TWT channel, and the NDP paging subfield are included only in the individual TWT parameter set field.

[0222] The TWT Group Assignment subfield provides the TWT requesting STA with information about the TWT group to which the STA is assigned. This information can be used to calculate the TWT value within the TWT group. The TWT value of the STA may be equal to the value of the zero offset and the TWT offset multiplied by the TWT unit value.

[0223] The TWT Channel subfield indicates a bitmap indicating allowed channels. When transmitted by a TWT requesting STA, the TWT Channel subfield may contain a bitmap indicating channels that the STA requests to use as temporary fundamental channels in the TWT SP. When transmitted by a TWT responding STA, the TWT Channel subfield may contain a bitmap indicating channels on which the TWT request is allowed.

[0224] The NDP paging subfield is optional and may include an identifier for the STA being paged, information about the maximum number of TWT wake intervals between NDP paging frames, and the like.

[0225] Referring to Figure 19, the Broadcast TWT Info subfield is included only in the Broadcast TWT Parameter Set field. The Broadcast TWT Info subfield may include a 3-bit reserved bit, a 5-bit Broadcast TWT Identifier (ID) subfield, and an 8-bit Broadcast TWT Persistence subfield. The Broadcast TWT Identifier subfield indicates the broadcast ID of a specific Broadcast TWT to which a STA requests participation or provides TWT parameters, depending on the value of the TWT Setup Command subfield of the TWT element. The Broadcast TWT Persistence subfield indicates the number of TBTTs planned on the schedule of the Broadcast TWT.

[0226] Next, the detailed structure of the request type subfield will be described.

[0227] First, the format of the request type subfield of the individual TWT parameter set field will be described with reference to FIG.

[0228] The TWT request subfield can indicate whether it is a requesting STA or a responding STA. If its value is 1, it indicates a TWT requesting STA or a scheduled STA, and if its value is 0, it indicates a TWT responding STA or a scheduling AP.

[0229] The TWT setup command subfield can indicate commands such as Request, Suggest, Demand, Accept, Alternate, Dictate, and Reject.

[0230] The trigger subfield indicates whether a trigger frame is used in the TWT SP. If the value is 1, a trigger is used, and if the value is 0, a trigger is not used.

[0231] The implicit subfield can indicate implicit or explicit TWT, where a value of 1 indicates implicit TWT and a value of 0 indicates explicit TWT.

[0232] The flow type subfield can indicate the type of interaction between a TWT requesting STA (or a TWT-scheduled STA) and a TWT responding STA (or a TWT-scheduling AP). If its value is 1, it can indicate announced TWT, in which the STA transmits a PS-Poll or APSD (automatic power save delivery) trigger frame to send a wake-up signal to the AP before any frame other than the trigger frame is transmitted from the AP to the STA. If its value is 0, it can indicate non-announced TWT.

[0233] The TWT flow identifier subfield may contain a 3-bit value that uniquely identifies the specific information for this TWT request from other requests made between the same TWT requesting STA and TWT responding STA pair.

[0234] The TWT wake interval exponent subfield can be set to the TWT wake interval value in binary microseconds. In the case of an individual TWT, it can refer to the interval between individual TWT SPs. The TWT wake interval of the requesting STA may be defined as [TWT Wake Interval Mantissa * 2 * TWT Wake Interval Exponent].

[0235] The TWT protection subfield can indicate whether to use a TWT protection mechanism. If its value is 1, the TXOP in the TWT SP can be initiated with a NAV protection mechanism such as a (MU)RTS / CTS or CTS-to-self frame; if its value is 0, the NAV protection mechanism is not applied.

[0236] 19, some of the subfields of the Request Type subfield in the Broadcast TWT Parameter Set field are common to the subfields of the Request Type subfield in the Individual TWT Parameter Set field, and therefore will not be described here. The subfields included only in the Broadcast TWT Parameter Set field will be described below.

[0237] The Last Broadcast Parameter Set subfield indicates whether this is the last broadcast TWT parameter set. If the value is 1, it indicates that this is the last broadcast TWT parameter set, and if the value is 0, it indicates that there is a next broadcast TWT parameter set.

[0238] The Broadcast TWT recommendation subfield can indicate a recommendation for the frame type to be transmitted by the AP in the Broadcast TWT SP with a value of 1 to 7.

[0239] The last bit of the Request Type subfield of the Broadcast TWT Parameter Set field may be reserved.

[0240] Restricted TWT-related operation methods

[0241] Compared with a cellular wireless communication network system based on radio resource scheduling, a contention-based medium access scheme in a wireless LAN system may have difficulty supporting latency-sensitive traffic. Restricted TWT (R-TWT) may be one of various schemes being considered to support transmission and reception of latency-sensitive traffic in a wireless LAN system.

[0242] R-TWT may correspond to a special broadcast TWT configured by an AP for low-latency STAs (i.e., STAs that support the transmission of latency-sensitive data). R-TWT can be used to help ensure data transmission availability for low-latency STAs preferentially over other STAs. STAs can establish membership for one or more R-TWT schedules with an AP. Here, R-TWT agreement may be established through the same process as broadcast TWT agreement, and the broadcast TWT element for this purpose may be defined to include an R-TWT parameter set field. For example, the R-TWT parameter set may refer to a specific broadcast TWT parameter set field that is distinct from other broadcast TWT parameter set fields. That is, the R-TWT parameter set field may correspond to a special case of the broadcast TWT parameter set field.

[0243] As a specific example, for R-TWT related operations, an R-TWT Traffic Info subfield may be added to the Broadcast TWT Parameter Set field in FIG. 19 described above.

[0244] Specifically, the R-TWT Traffic Information field may include a Traffic Info Control subfield, an R-TWT DL TID Bitmap subfield, and an R-TWT UL TID Bitmap subfield.

[0245] Here, the R-TWT DL TID Bitmap subfield and the R-TWT UL TID Bitmap subfield may specify TID(s) identified as latency-sensitive traffic streams in the downlink / uplink directions by an R-TWT scheduling AP (R-TWT scheduling AP) or an R-TWT scheduled STA, respectively. For example, setting the k-th bit position of the bitmap to 1 may indicate that the k-th TID is classified as a latency-sensitive traffic stream. Conversely, setting the k-th bit position of the bitmap to 0 may indicate that the k-th TID is not classified as a latency-sensitive traffic stream.

[0246] While establishing membership to the R-TWT schedule based on the fields / subfields described above, the AP and STA can negotiate the TID for LL (low latency) traffic, i.e., traffic related to R-TWT, to be transmitted to each other.

[0247] The AP may also announce an R-TWT SP, which may also be referred to as an RSP in this disclosure.

[0248] A STA supporting a broadcast TWT limited service period (SP), i.e., R-TWT SP operation (e.g., a low-latency STA), can inform the AP that it must transmit latency-sensitive data based on the R-TWT operation. If the AP supports R-TWT operation / mode, the AP can transmit a frame containing scheduling information for the TWT requested by each STA to the low-latency STA and other STAs. For example, to perform an R-TWT operation, a non-AP STA can obtain R-TWT-related information from the AP using a beacon frame, a probe response frame, a (re)association response frame, or a frame of another undefined format (e.g., a frame for broadcast, advertisement, or announcement). Although a beacon frame is used as a frame containing R-TWT-related information to be announced, R-TWT-related information may also be announced using various management frames as described above.

[0249] According to the R-TWT operation, a separate TXOP (i.e., a TXOP with restricted access for other STAs) can be reserved within the R-TWT SP using NAVs such as (MU)RTS / CTS or CTS-to-self, or a quiet interval. Before the R-TWT SP starts, any TXOPs of STAs other than the STA having membership to the R-TWT schedule (i.e., non-member STAs) must be stopped. Then, TXOPs of other STAs (i.e., non-member STAs) may be made after the R-TWT SP ends.

[0250] FIG. 20 illustrates a limited TWT operation to which the present disclosure can be applied.

[0251] Referring to FIG. 20, STA1 is a STA that recognizes / supports RSP and corresponds to an RSP STA, and STA2 is a STA that does not recognize / support RSP and corresponds to a Non-RSP STA (or Regular STA).

[0252] As described above, the AP can announce R-TWT-related information (e.g., RSP-related information) using the TWT information. Generally, the RSP may be allocated for STAs with low latency traffic. Here, the STAs may include AP STAs or non-AP STAs.

[0253] The AP and the STA can establish membership to the embodied RSP based on TWT-related parameters. For example, the AP and the STA can negotiate membership to the RSP by exchanging TWT setup-related information (e.g., traffic information, SP assignment, etc.).

[0254] Although FIG. 20 shows that the RSP announcement procedure by the AP occurs before the membership negotiation procedure, the RSP announcement procedure may occur after any R-TWT memberships are set up by membership negotiation.

[0255] At this time, STA2 that does not support RSP (for example, a non-member STA) must stop its own TXOP if it exists before the start of the RSP.

[0256] In connection with the R-TWT operations described above, ensuring priority for low latency traffic transmission within the RSP can be very important.

[0257] Therefore, this disclosure proposes a method for setting / defining channel access rules to ensure priority for low latency traffic transmission within an RSP.

[0258] During the establishment of the R-TWT association membership, the AP and the STA can negotiate the TID for the low latency traffic they transmit to each other, which can mean that the traffic for the TID they transmit and receive at the RSP is considered to be low latency traffic.

[0259] Here, the TID may include an R-TWT DL TID associated with DL traffic that the AP transmits to the STA in the RSP, and / or an R-TWT UL TID associated with UL traffic that the STA transmits to the AP in the RSP. Hereinafter, for clarity, the TID will be referred to as an R-TWT TID.

[0260] In this case, transmitting a TID that does not correspond to the R-TWT TID allows transmission of traffic that does not correspond to low latency traffic, which may make the role of the RSP unclear.

[0261] Here, the TID may be associated with an access category (AC) in terms of channel access for frame transmission.

[0262] Table 1 illustrates the mapping relationship between access categories (AC) and user priorities (UP).

[0263] [Table 1]

[0264] Referring to Table 1, user priority (UP) is mapped to each access category (AC), and a priority for each UP may be defined. In Table 1, the Designation column indicates general use / guidance.

[0265] In this regard, the value of the TID associated with the priority may be interpreted as a user priority (UP). As an example, TID values ​​0 to 7 may be interpreted as UP values ​​0 to 7. That is, the UP information / values ​​in Table 1 may be considered as the TID information / values ​​described above.

[0266] Therefore, we propose a method to define / apply new rules from the perspective of channel access to prevent the above-mentioned ambiguity using the relationship between AC and TID.

[0267] Hereinafter, the embodiments are divided only for clarity of explanation, and each embodiment may be applied independently, or the embodiments may be applied in combination / combination with each other.

[0268] Hereinafter, the embodiment will be described assuming that a back-off counter exists for each AC.

[0269] Example 1

[0270] If the TIDs mapped to an Access Category (AC) do not include any R-TWT TIDs, then no contention, i.e., no backoff, is required for that AC. If there is an existing backoff, that backoff may be stopped.

[0271] In the present disclosure, performing backoff can mean performing an operation of decrementing a backoff counter.

[0272] That is, for an R-TWT TID transmitted in an RSP, a STA that has established / has membership to that RSP can suspend the operation of decrementing the backoff counter of an AC to which no R-TWT TID is mapped, i.e., backoff operations for ACs that are not associated with the R-TWT TID may need to be suspended within that RSP.

[0273] Additionally or alternatively, to improve efficiency outside the RSP, a method may be considered in which contention for the AC, i.e., backoff, is performed, but data for the TID of the AC is not transmitted once the backoff counter reaches 0. In this case, backoff can be resumed, or data transmission can be deferred while maintaining the backoff counter.

[0274] Example 2

[0275] If at least one R-TWT TID is included among the TIDs mapped to an Access Category (AC), contention, i.e., back-off, can be performed for that AC.

[0276] At this time, when the value of the backoff counter becomes 0, only data for the TID corresponding to the R-TWT TID among the TIDs of the AC can be transmitted in a frame.

[0277] FIG. 21 illustrates a channel access operation in a restricted TWT SP according to an embodiment of the present disclosure.

[0278] Referring to FIG. 21, STA1 is a STA that recognizes / supports the RSP and may correspond to an RSP STA.

[0279] For example, through the membership negotiation procedure, the AP and STA1 can negotiate TID4, TID5, and TID6 for the R-TWT UL TID as low latency (LL) traffic within the assigned RSP.

[0280] In this case, referring to the mapping relationship between AC and UP and the relationship between UP and TID in Table 1, both TID4 and TID5 associated with AC_VI may correspond to the R-TWT UL TID in the RSP. Furthermore, of TID6 and TID7 associated with AC_VO, only TID6 may correspond to the R-TWT UL TID in the RSP.

[0281] Therefore, STA1 can perform a backoff operation for AC_VI of ACs. When the time for transmitting a frame arrives, STA1 can transmit data for TID4 and TID5 in a frame.

[0282] Furthermore, STA1 can perform a backoff operation for AC_VO in AC. When the frame transmission time arrives, STA1 can transmit only data for TID6 in the frame. That is, since TID7 related to AC_VO does not correspond to / is not included in the R-TWT UL TID, even if data for TID7 exists in the queue, it does not need to be transmitted (i.e., it does not need to be included in the frame).

[0283] Meanwhile, within the allocated RSP, STA1 does not need to perform backoff operations for AC_BK and AC_BE that do not include / are not associated with any R-TWT UL TID.

[0284] FIG. 22 is a diagram illustrating an operation of a STA supporting a backoff operation in an R-TWT SP according to an embodiment of the present disclosure.

[0285] FIG. 22 illustrates the operation of the STA based on the previously proposed method (for example, any one of the above-described first and second embodiments and their detailed embodiments, or a combination of one or more (detailed) embodiments).

[0286] In step S2210, the STA may receive R-TWT SP-related information from the AP.

[0287] Here, the R-TWT SP related information may include information regarding RSP allocation / scheduling.

[0288] For example, the R-TWT SP-related information may be advertised / announced to STAs by a management frame such as a beacon frame.

[0289] In step S2220, the STA may set at least one R-TWT traffic identifier (TID) for the R-TWT SP, and based on the set at least one R-TWT TID, the STA may transmit / receive data / traffic using frames within the RSP.

[0290] Here, whether to perform a backoff operation for an access category (AC) in the R-TWT SP may be determined based on a mapping relationship between the at least one R-TWT TID and the AC.

[0291] For example, if the at least one R-TWT TID is not mapped to the AC, no backoff operation may be performed for the AC in the R-TWT SP, i.e., the STA may not perform a backoff operation (i.e., an operation of decrementing the backoff counter value) for an AC to which no R-TWT TID is mapped / included.

[0292] This prevents traffic / data that does not correspond to the R-TWT TID from being transmitted within the RSP.

[0293] For example, the at least one R-TWT TID may correspond to at least one TID for latency-related traffic in the uplink or downlink within the R-TWT SP. In this regard, the AC may be mapped to at least one user priority (UP), and each of the at least one UP may be interpreted as a TID.

[0294] For example, the at least one R-TWT TID may be set by a membership setup procedure between the STA and the AP. In this regard, the membership setup procedure may be performed by a TWT setup frame exchanged between the STA and the AP. Additionally or alternatively, the at least one R-TWT TID may be determined based on traffic information (e.g., a Traffic Info field) in the membership setup procedure.

[0295] For example, if any one of the at least one R-TWT TID is mapped to the AC, a backoff operation for the AC may be performed within the R-TWT SP, and in this case, only data corresponding to the R-TWT TID mapped to the AC may be included in a frame transmitted or received within the R-TWT SP.

[0296] The embodiments described above are combinations of the components and features of the present disclosure in a predetermined form. Each component or feature should be considered optional unless otherwise explicitly stated. Each component or feature may be implemented without being combined with other components or features. It is also possible to combine some components and / or features to form embodiments of the present disclosure. The order of operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is clear that claims that do not have an explicit reference relationship in the claims may be combined to form embodiments, or may be included as new claims by amendment after filing.

[0297] It is obvious to those skilled in the art that the present disclosure can be embodied in other specific forms without departing from the essential features of the present disclosure. Therefore, the above detailed description should not be interpreted as limiting in any respect, but should be considered as illustrative. The scope of the present disclosure should be determined by reasonable interpretation of the appended claims, and any modifications within the equivalent scope of the present disclosure are included in the scope of the present disclosure.

[0298] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that cause a device or computer to perform operations according to the methods of various embodiments, as well as non-transitory computer-readable media on which such software or instructions are stored and executable on a device or computer. Instructions usable for programming a processing system to perform features described in this disclosure may be stored on or in a storage medium or computer-readable storage medium, and computer program products including such storage media may be used to embody features described in this disclosure. Storage media may include high-speed random access memory such as DRAM, SRAM, DDR RAM, or other random access solid-state memory devices, but are not limited to, non-volatile memory such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state storage devices. Memory optionally includes one or more storage devices located remotely from the processor. Memory, or alternatively, non-volatile memory devices within memory, comprise non-transitory computer-readable storage media. The features described in this disclosure may be embodied in software and / or firmware stored on any one of a number of machine-readable media and capable of controlling the hardware of a processing system and allowing the processing system to interact with other mechanisms that utilize the results of embodiments of the present disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers. [Industrial Applicability]

[0299] The method proposed in this disclosure has been described mainly as being applied to an IEEE 802.11-based system, but it can also be applied to various wireless LANs or wireless communication systems other than the IEEE 802.11-based system.

Claims

1. A method performed by an access point (AP), The stage of transmitting information related to the R-TWT (restricted target wake time) schedule to the STA (station), The steps include setting up at least one R-TWT TID (traffic identifier) ​​associated with the R-TWT schedule based on the membership setup between the AP and the STA, The step includes performing a frame exchange with the STA during the R-TWT SP (service period) of the R-TWT schedule based on the at least one R-TWT TID, A method in which the operation of reducing the backoff counter of an access category (AC) to which none of the at least one R-TWT TID belongs is interrupted during the R-TWT SP, based on a predefined channel access rule.

2. The method according to claim 1, wherein the at least one R-TWT TID corresponds to at least one TID for latency-related traffic in the uplink or downlink between the R-TWT SPs.

3. The AC is mapped to at least one UP (user priority), The method according to claim 2, wherein each of the at least one UP is interpreted as a TID.

4. The method according to claim 1, wherein the membership setup is performed using a TWT setup frame exchanged between the STA and the AP.

5. The method according to claim 1, wherein the at least one R-TWT TID is determined based on the traffic information in the membership setup.

6. The method according to claim 1, wherein the frame replacement is performed by reducing the backoff counter of the AC mapped to any one of the at least one R-TWT TIDs to zero.

7. The method according to claim 6, wherein the frame exchange between the R-TWT SPs comprises only latency-related traffic exchanges that correspond to any one of the at least one R-TWT TIDs.

8. The method according to claim 1, wherein the information related to the R-TWT SP is announced by a beacon frame.

9. A device for an access point (AP), One or more transceivers, The system comprises one or more processors operably connected to one or more transceivers, The one or more processors described above are: Information related to the R-TWT (restricted target wake time) schedule is sent to the STA (station). Based on the membership setup between the AP and the STA, at least one R-TWT TID (traffic identifier) ​​associated with the R-TWT schedule is set. Based on the at least one R-TWT TID, the system is configured to perform a frame exchange with the STA during the R-TWT SP (service period) of the R-TWT schedule, An apparatus in which, based on a predefined channel access rule, the operation of reducing the backoff counter of an access category (AC) to which none of the at least one R-TWT TID belongs is interrupted during the R-TWT SP.

10. A method performed by STA (station), The stage of receiving information related to the R-TWT (restricted target wake time) schedule from the AP (access point), The steps include setting up at least one R-TWT TID (traffic identifier) ​​associated with the R-TWT schedule based on the membership setup between the AP and the STA, The step includes performing a frame exchange with the AP during the R-TWT SP (service period) of the R-TWT schedule based on the at least one R-TWT TID, A method in which, based on a predefined channel access rule, the reduction of the backoff counter for access categories (ACs) to which none of the at least one R-TWT TIDs belong is interrupted during the R-TWT SP.

11. A device for STA (station), One or more transceivers, The system comprises one or more processors operably connected to one or more transceivers, The one or more processors described above are: Information related to the R-TWT (restricted target wake time) schedule is received from the AP (access point). Based on the membership setup between the AP and the STA, at least one R-TWT TID (traffic identifier) ​​associated with the R-TWT schedule is set. Based on the aforementioned at least one R-TWT TID, the system is configured to perform frame exchange with the AP during the R-TWT SP (service period) of the R-TWT schedule, An apparatus in which, based on a predefined channel access rule, the reduction of the backoff counter for ACs (access category) to which none of the at least one R-TWT TIDs belong is interrupted during the R-TWT SP.

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