METHOD AND APPARATUS FOR TARGET WAKE TIME SERVICE PERIOD RE-SCHEDULE IN WIRELESS LAN SYSTEM

Abstract

A method and apparatus for rescheduling a target wake time service period in a wireless LAN system are disclosed. The method performed by a station (STA) in a wireless LAN system according to an embodiment of the present disclosure includes: establishing an agreement related to a restricted target wake time (R-TWT); and transmitting a frame including a TWT information field to one or more other STAs, and based on the all TWT subfield of the TWT information field being set to a value of 1 and the TWT flow identifier subfield of the TWT information field being set to a specific value, a next TWT subfield of the TWT information field can indicate rescheduling related information for an R-TWT service period (SP) corresponding to the specific value.

Description

[Technical field]

[0001] The present disclosure relates to target wake time (TWT) operations in Wireless Local Area Network (WLAN) systems, and more particularly to methods and apparatus related to rescheduling of Restricted-TWT (R-TWT) service periods (SP) in next generation WLAN systems. [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 wireless LAN technologies, the IEEE (Institute of Electrical and Electronics Engineers) 802.11 series of standards can be called Wi-Fi. For example, technologies recently introduced to wireless LANs include enhancements for the 802.11ac standard for Very High-Throughput (VHT) and enhancements for the IEEE 802.11ax standard for High Efficiency (HE).

[0003] In order to provide a more improved wireless communication environment, improved technologies for EHT (Extremely High Throughput) are being discussed. For example, technologies for increased bandwidth, efficient use of multiple bands, multiple input multiple output (MIMO) supporting increased spatial streams, and multiple access point (AP) coordination are being studied, and in particular, various technologies for supporting traffic with low latency or real-time characteristics are being studied. 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 related to rescheduling of limited TWT service periods in a wireless LAN system.

[0005] A further technical object of the present disclosure is to provide a method and apparatus for indicating information related to rescheduling for an assigned service period after allocation of a limited TWT service period in a wireless LAN system.

[0006] The technical problems to be achieved 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] According to one embodiment of the present disclosure, a method performed by a station (STA) in a wireless LAN system includes a step of establishing an agreement associated with a restricted target wake time (R-TWT) and a step of transmitting a frame including a TWT information field to one or more other STAs, wherein based on the value of an all TWT subfield of the TWT information field being set to 1 and a TWT flow identifier subfield of the TWT information field being set to a specific value, a next TWT subfield of the TWT information field may indicate rescheduling related information for an R-TWT service period (SP) corresponding to the specific value. Effect of the Invention

[0008] According to the present disclosure, methods and apparatus related to rescheduling limited TWT service periods in a wireless LAN system may be provided.

[0009] According to the present disclosure, a method and apparatus can be provided for indicating information related to rescheduling for an assigned service period after allocation of a restricted 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 a person having ordinary skill in the art to which the present disclosure pertains from the following description. [Brief description 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] 1 is a block diagram illustrating a wireless communication device according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a diagram illustrating an exemplary structure of a wireless LAN system to which the present disclosure can be applied. [Diagram 3] FIG. 2 is a diagram illustrating a link setup process to which the present disclosure can be applied. [Figure 4] FIG. 13 is a diagram for explaining a backoff process to which the present disclosure can be applied. [Diagram 5] 1 is a diagram for explaining a CSMA / CA base frame transmission operation to which the present disclosure can be applied. [Figure 6] 1 is a diagram for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied. [Figure 7] FIG. 2 illustrates an example of a PPDU defined in the IEEE 802.11 standard to which the present disclosure can be applied. [Figure 8] FIG. 2 is a diagram for explaining an example of a resource unit of a wireless LAN system to which the present disclosure can be applied. [Figure 9]FIG. 2 is a diagram for explaining an example of a resource unit of a wireless LAN system to which the present disclosure can be applied. [Figure 10] FIG. 2 is a diagram for explaining an example of a resource unit of a wireless LAN system to which the present disclosure can be applied. [Figure 11] FIG. 2 illustrates an exemplary structure of an HE-SIG-B field. [Figure 12] FIG. 1 is a diagram for explaining a MU-MIMO scheme in which multiple users / STAs are assigned to one RU. [Figure 13] A figure showing an example of a PPDU format to which the present disclosure can be applied. [Figure 14] 1A to 1C are diagrams for explaining an example of individual TWT operation to which the present disclosure can be applied. [Figure 15] FIG. 1 is a diagram for explaining an example of a broadcast TWT operation to which the present disclosure can be applied. [Figure 16] FIG. 13 is a diagram for explaining an example of a TWT information field format. [Figure 17] FIG. 13 is a diagram illustrating an example of a TWT information element format. [Figure 18] A figure for explaining an example of an individual TWT parameter set field format. [Figure 19] A diagram for explaining an example of a broadcast TWT parameter set field format. [Figure 20] FIG. 13 is a diagram for explaining the operation of a STA that supports rescheduling of an R-TWT SP according to an embodiment of the present disclosure. [Figure 21] FIG. 13 is a diagram for explaining an example of the postponement and resumption of an R-TWT SP according to the present disclosure. [Figure 22] FIG. 13 is a diagram for explaining an example of a P2P-related R-TWT SP suspension and resumption according to the present disclosure. [Diagram 23] FIG. 13 is a diagram for explaining an example related to the extension of an R-TWT SP according to the present disclosure. [Figure 24]FIG. 13 is a diagram for explaining an example related to an extension of an R-TWT SP related to P2P according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description disclosed below together with the accompanying drawings is intended to describe exemplary embodiments of the present disclosure, and is not intended to show the only embodiment 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 is understood by those skilled in the art that the present disclosure can be implemented without such specific details.

[0014] In some cases, in order to avoid obscuring the concepts of the present disclosure, known structures and devices may be omitted or may be shown in the form of a block diagram focusing on the core functions of each structure and device.

[0015] 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 term "comprise" or "have" specifies the presence of a referenced feature, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0016] In this disclosure, the terms "first", "second", etc. are used only to distinguish one component from another component, 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.

[0017] 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 form is intended to include the plural form unless the context dictates otherwise. The term "and / or" used in this disclosure means that one of the associated listed items may be included, or any and all possible combinations of two or more of them. Also, in this disclosure, " / " between words has the same meaning as "and / or" unless otherwise specified.

[0018] 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. Also, the examples of the present disclosure may 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 New Radio (NR) series technology of the 3rd Generation Partnership Project (3GPP) standard.

[0019] Below, technical features to which the examples of the present disclosure can be applied are described.

[0020] FIG. 1 is a block diagram illustrating a wireless communication device according to an embodiment of the present disclosure.

[0021] The first device 100 and the second device 200 illustrated in Fig. 1 may be referred to as 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 as 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.

[0022] 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 as various terms such as a transmitting device, a receiving device, a transmitting STA, and a receiving STA. For example, the STAs 110 and 200 may play the role of an AP (access point) or a non-AP. That is, in the present disclosure, the STAs 110 and 200 may have the function of an AP and / or a non-AP. When the STAs 110 and 200 have the AP function, they may simply be referred to as an AP, and when the STAs 110 and 200 have the non-AP function, they may simply be referred to as an STA. Also, in the present disclosure, an AP may be indicated as an AP STA.

[0023] 1, the first device 100 and the second device 200 can transmit and receive wireless signals using various wireless LAN technologies (e.g., IEEE 802.11 series). The first device 100 and the second device 200 may include an interface to a medium access control (MAC) layer and a physical layer (PHY) in accordance with the provisions of the IEEE 802.11 standard.

[0024] 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 the WLAN technology. In addition, the device of the present disclosure may be embodied by various devices such as a mobile phone, a vehicle, a personal computer, an Augmented Reality (AR) device, and a Virtual Reality (VR) device. In addition, the STA of the present specification may support various communication services such as voice calls, image calls, data communications, autonomous driving, machine-type communication (MTC), machine-to-machine (M2M), device-to-device (D2D), and Internet-of-Things (IoT).

[0025] The first device 100 includes one or more processors 102 and one or more memories 104, and may further include one or more transceivers 106 and / or one or more antennas 108. The processor 102 may be configured to control the memory 104 and / or the transceiver 106 to embody the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams in the present disclosure. For example, the processor 102 may process information in the memory 104 to generate a first information / signal, and then transmit a wireless signal including the first information / signal via the transceiver 106. The processor 102 may also receive a wireless signal including a second information / signal via the transceiver 106, and then store information obtained from signal processing of the second information / signal 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 executing the descriptions, functions, procedures, suggestions, methods and / or operational flow diagrams in the present disclosure. Here, the processor 102 and the memory 104 may be part of a communication modem / circuit / chip designed to implement wireless LAN technology (e.g., 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 a radio frequency (RF) unit. In the present disclosure, a device may also refer to a communication modem / circuit / chip.

[0026] The second device 200 may include one or more processors 202, one or more memories 204, and may further include one or more transceivers 206 and / or one or more antennas 208. The processor 202 may be configured to control the memory 204 and / or the transceiver 206 to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in the present disclosure. For example, the processor 202 may process information in the memory 204 to generate a 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 a 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 executing the descriptions, functions, procedures, suggestions, methods and / or operational flow diagrams disclosed in the present disclosure. Here, the processor 202 and the memory 204 may be part of a communication modem / circuit / chip designed to implement wireless LAN technology (e.g., 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 the present disclosure, a device may also refer to a communication modem / circuit / chip.

[0027] The hardware elements of the devices 100, 200 are described in more detail below. Without being limited thereto, one or more protocol layers may be embodied by one or more processors 102, 202. For example, one or more processors 102, 202 may embody one or more layers (e.g., the same functional layers such as PHY, MAC). One or more processors 102, 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 the present disclosure. One or more processors 102, 202 may generate messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams in the present 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 in 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 flow diagrams in this disclosure.

[0028] The one or more processors 102, 202 may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. The one or more processors 102, 202 may be embodied in hardware, firmware, software, or a combination thereof. As an example, 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) may be included in the one or more processors 102, 202. The descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in the present disclosure may be embodied using firmware or software, and the firmware or software may be embodied to include modules, procedures, functions, etc. Firmware or software configured to execute the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present 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 flowcharts disclosed in the present disclosure may be embodied in firmware or software in the form of code, instructions and / or collections of instructions.

[0029] One or more memories 104, 204 may be coupled to one or more processors 102, 202 and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. 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. The one or more memories 104, 204 may be coupled to the one or more processors 102, 202 by various techniques, such as wired or wireless coupling.

[0030] The 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 flow diagrams of the present disclosure, to one or more other devices. The 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 flow diagrams of the present disclosure, from one or more other devices. For example, the 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, the one or more processors 102, 202 may control the one or more transceivers 106, 206 to transmit user data, control information, or wireless signals to one or more other devices. Also, the one or more processors 102, 202 may control the one or more transceivers 106, 206 to receive user data, control information, or wireless signals from one or more other devices. In addition, 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, radio signals / channels, etc., as described, functions, procedures, suggestions, methods, and / or operation flow diagrams disclosed in the present disclosure, via the one or more antennas 108, 208. In the present 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 radio signals / channels, etc., from RF band signals to baseband signals for processing the received user data, control information, radio signals / channels, etc., using one or more processors 102, 202. The one or more transceivers 106, 206 may convert the user data, control information, radio 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.

[0031] For example, one of the STAs 100 and 200 can perform operations intended for an AP, and the other of the STAs 100 and 200 can perform operations intended for a non-AP STA. For example, the transceivers 106 and 206 in FIG. 1 can perform operations of 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 of various STAs generating transmission and reception signals and performing data processing and calculations in advance for transmission and 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 (SIG (signal), STF (short training field), LTF (long training field), Data, etc.) included in the PPDU; 2) operations for determining / configuring / obtaining time resources and frequency resources (e.g., subcarrier resources) used for fields (SIG, STF, LTF, Data, etc.) included in the PPDU; 3) operations for determining / configuring / obtaining specific sequences (e.g., pilot sequences, STF / LTF sequences, extra sequences applied to SIGs) used for fields (SIG, STF, LTF, Data, etc.) included in the PPDU; 4) power control operations and / or power saving operations applied to STAs; and 5) operations related to determining / obtaining / configuring / calculating / decoding / encoding an ACK signal, etc. In addition, various information (e.g., information regarding fields / subfields / control fields / parameters / power, etc.) used by various STAs in the following example for determining / obtaining / configuring / calculating / decoding / encoding transmitted / received signals may be stored in memory 104, 204 of FIG. 1.

[0032] 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 through the downlink. In downlink communication, a transmitter may be part of an AP STA, and a receiver may be part of a 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 through the uplink. In uplink communication, a transmitter may be part of a non-AP STA, and a receiver may be part of an AP STA.

[0033] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0034] The structure of a wireless LAN system may be composed of a number of components. A wireless LAN supporting STA mobility that is transparent to higher layers may be provided by the interaction of a number of components. A basic service set (BSS) corresponds to a basic building block of a wireless LAN. FIG. 2 illustrates an example in which there are two BSSs (BSS1 and BSS2) and two STAs are included as members of each BSS (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2). In FIG. 2, an ellipse representing a BSS may be understood to represent a coverage area in which STAs included in the BSS maintain communication. This area may be referred to as a basic service area (BSA). When a STA moves outside a BSA, it cannot directly communicate with other STAs in the BSA.

[0035] Without considering the DS shown in FIG. 2, the most basic type of BSS in a wireless LAN is an independent BSS (IBSS). For example, an IBSS may have a minimal form consisting of only two STAs. For example, assuming that other components are omitted, a BSS1 consisting of only STA1 and STA2, or a BSS2 consisting of only STA3 and STA4, may correspond to representative examples of an IBSS. Such a configuration is possible when the STAs can communicate directly without an AP. In addition, in such a form of wireless LAN, the IBSS is not configured in advance, but may be configured when the LAN requires it, and this may also be called an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity that performs a management function. That is, in an IBSS, the STAs are managed in a distributed manner. In an IBSS, all STAs may be mobile STAs, and connection to a distributed system (DS) is not allowed, forming a self-contained network.

[0036] The membership of STAs in a BSS may change dynamically as STAs come on and go, enter and leave the BSS domain, 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 structure, a STA must be associated with the BSS. Such association may be configured dynamically and may include the use of a Distribution System Service (DSS).

[0037] In a wireless LAN, the direct STA-to-STA distance may be limited by the PHY performance. In some cases, such distance limits are sufficient, but in other cases, communication between STAs at greater distances may be required. A distributed system (DS) may be configured to support extended coverage.

[0038] DS means a structure in which BSSs are interconnected. Specifically, as shown in FIG. 2, a BSS may exist as a component of an expanded form of a network composed of multiple BSSs. 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 not limited to being the same or different. In this way, the flexibility of a WLAN structure (DS structure or other network structure) can be explained in that multiple media are logically different from each other. That is, the WLAN structure may be embodied in various ways, and the WLAN structure may be independently specified according to the physical characteristics of each embodiment.

[0039] The DS can support mobile devices by providing seamless integration of multiple BSSs and logical services necessary to address 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).

[0040] An AP means an entity that allows associated non-AP STAs to access a DS through a WM and also has the functionality of an STA. Data can be moved between a BSS and a DS via an AP. For example, STA2 and STA3 shown in FIG. 2 provide a function that allows associated non-AP STAs (STA1 and STA4) to access a DS while having the functionality of an STA. In addition, since all APs basically correspond to STAs, all APs are addressable entities. The address used by an AP for communication on a WM and the address used by an AP for communication on a DSM do not necessarily have to be the same. A BSS consisting of an AP and one or more STAs can be called an infrastructure BSS.

[0041] Data sent from one of the STAs coupled to the AP to the STA address of the AP is always received on an uncontrolled port and may be processed by the IEEE 802.1X port access entity, and the transmitted data (or frame) may be delivered to the DS if the controlled port is authenticated.

[0042] In the above-mentioned DS structure, an Extended Service Set (ESS) may be configured to provide wider coverage.

[0043] An ESS is a network of arbitrary size and complexity composed of a DS and a BSS. An ESS may 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). SSID is distinguished from BSSID, which is an identifier of a BSS.

[0044] In a wireless LAN system, no assumptions are made regarding the relative physical locations of the BSSs, and any of the following configurations are possible: The BSSs may overlap, which is a configuration commonly used to provide continuous coverage; The BSSs may not be physically connected, and there is no logical limit to the distance between the BSSs; The BSSs may be physically located in the same location, which may be used to provide redundancy; One (or more) IBSS or ESS network may physically exist in the same space as one (or more) ESS network. This may be the case when an ad-hoc network operates in the location where the ESS network exists, when physically overlapping wireless networks are configured by different organizations, or when two or more different access and security policies are required in the same location.

[0045] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0046] 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 be called a session initiation process or a session setup process. In addition, the discovery, authentication, association, and security setting processes of the link setup process can be collectively called an association process.

[0047] 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 network that it can join. Before joining a wireless network, the STA must identify a compatible network, and the process of identifying networks that exist in a particular area is called scanning.

[0048] There are two types of scanning methods: active scanning and passive scanning. FIG. 3 illustrates a network discovery operation including an active scanning process. In active scanning, a scanning STA transmits a probe request frame to search for APs in the vicinity while changing channels, and waits for a response to the probe request frame. A responder transmits a probe response frame to the STA that transmitted the probe request frame as a response to the probe request frame. Here, the responder may be the STA that transmitted a beacon frame last in the BSS of the channel being scanned. In the BSS, the AP transmits a beacon frame, so the AP becomes the responder, and in the IBSS, the STAs in the IBSS transmit beacon frames alternately, so the responder is not constant. For example, a 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 and move to the next channel (e.g., channel 2) and perform scanning in the same manner (i.e., sending and receiving a probe request / response on channel 2).

[0049] Although not shown in FIG. 3, the scanning operation may be performed in a passive scanning manner. In passive scanning, the scanning STA waits for a beacon frame while changing channels. A beacon frame is one of the management frames defined in IEEE 802.11, and is periodically transmitted to inform the existence of a wireless network and to allow the scanning STA to search for and join the wireless network. In a BSS, an AP is responsible for periodically transmitting a beacon frame, and in an IBSS, STAs in the IBSS transmit beacon frames in turn. When a scanning STA receives a beacon frame, it stores information about the BSS included in the beacon frame and records beacon frame information on each channel while moving to another channel. A STA that receives a beacon frame stores information about the BSS included in the received beacon frame, moves to the next channel, and can perform scanning on the next channel in the same manner. Comparing active scanning with passive scanning, active scanning has an advantage of having a smaller delay and power consumption than passive scanning.

[0050] 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 in order to clearly distinguish it from the security setup operation in step S340 described below.

[0051] The authentication process includes a process in which the STA transmits an authentication request frame to the AP, and in response, the AP transmits an authentication response frame to the STA. The authentication frame used in the authentication request / response corresponds to a management frame.

[0052] The authentication frame may include information regarding 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.

[0053] 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 result of the authentication process to the STA using an authentication response frame.

[0054] 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 sending an association response frame to the STA in response.

[0055] 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 a partial example of information that may be included in the association request / response frame, and other information may be substituted or additional information may be included.

[0056] 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 be referred to as an authentication process using a Robust Security Network Association (RSNA) request / response, 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.

[0057] The security setup process of step S340 may include a process of performing a private key setup using, for example, 4-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame, and may be performed by a security method not defined in the IEEE 802.11 standard.

[0058] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0059] 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. The CSMA / CA mechanism is also called the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC, and basically adopts a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or STA may perform a Clear Channel Assessment (CCA) to sense the wireless channel or medium at a predetermined time interval (e.g., DCF Inter-Frame Space (DIFS)) prior to starting transmission. If the medium is determined to be in an idle status as a result of the sensing, the AP and / or STA may start transmitting a frame through the medium. On the other hand, if the medium is detected to be occupied or busy, the AP and / or STA may not start its own transmission, but may set a delay period (e.g., a random backoff period) for medium access and wait before attempting to transmit a frame. By applying the random backoff period, multiple STAs are expected to wait for different times before attempting to transmit a frame, thereby minimizing collisions.

[0060] The IEEE 802.11 MAC protocol also provides a Hybrid Coordination Function (HCF). The HCF is based on the DCF and the Point Coordination Function (PCF). The PCF is a polling-based synchronous access method that periodically polls so that all receiving APs and / or STAs can receive data frames. The HCF also includes Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA). EDCA refers to a contention-based access method for a provider to provide data frames to multiple users, and HCCA refers to a non-contention-based channel access method using a polling mechanism. The HCF also includes a medium access mechanism for improving the Quality of Service (QoS) of a wireless LAN, and can transmit QoS data in both a contention period (CP) and a contention-free period (CFP).

[0061] An operation based on the random backoff period will be described with reference to FIG. 4. When an occupied / busy medium is changed 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 a slot time corresponding to the random backoff count. The random backoff count has a pseudo-random integer value and may be determined to any one of values ​​in the range of 0 to CW. Here, CW is a contention window parameter value. The CW parameter is given an initial value of CWmin, but can take a value twice as large in the case of a transmission failure (e.g., when an ACK for a transmitted frame cannot be received). When the CW parameter value becomes CWmax, data transmission can be attempted while maintaining the CWmax value until data transmission is successful, and when data transmission is successful, the CW parameter is reset to the CWmin value. The CW, CWmin, and CWmax values ​​are determined to be two times as large as the CWmin value. n It is preferably set to -1 (n=0,1,2,...).

[0062] 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 the countdown and waits, and resumes the remaining countdown when the medium becomes idle.

[0063] 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 state and wait. In the meantime, data to be transmitted may also occur in each of STA1, STA2, and STA5. When the medium is monitored as idle, each STA can count down the backoff slots according to the random backoff count value selected by each STA after waiting for DIFS. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. That is, the example shows a case where the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1 at the time when STA2 finishes the backoff count and starts frame transmission. STA1 and STA5 stop counting down for a while and wait while STA2 occupies the medium. When STA2 ends its occupation and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume the backoff count that they had stopped. That is, after counting down the remaining backoff slots by the remaining backoff time, STA5 can start frame transmission. Since the remaining backoff time of STA5 is shorter than that of STA1, STA5 starts frame transmission. While STA2 occupies the medium, STA4 may also have data to transmit. From STA4's perspective, when the medium becomes idle, it waits for DIFS and then counts down the random backoff count value it has selected, and can start frame transmission. The example of FIG. 4 shows a case where the remaining backoff time of STA5 coincidentally matches the random backoff count value of STA4, in which case a collision may occur between STA4 and STA5. When a collision occurs, neither STA4 nor STA5 can receive an ACK, and data transmission will fail. In this case, STA4 and STA5 can select a random backoff count value and count down after doubling the CW value.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 after the remaining backoff time has elapsed.

[0064] As shown in the example of FIG. 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 performed 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 performed after an IFS such as a DIFS or a PIFS (Point coordination function IFS). Subtype frames of the management frame 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, and Trigger. If a control frame is not a response frame of a previous frame, it is transmitted after a backoff that is performed after a DIFS has elapsed, and if a control frame is a response frame of 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 a type field and a subtype field in a frame control (FC) field.

[0065] 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), where the frame can be a data frame, a management frame, or a control frame that is not a response frame.

[0066] FIG. 5 is a diagram for explaining a CSMA / CA base frame transmission operation to which the present disclosure can be applied.

[0067] As described above, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, in which the STA directly senses the medium. 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 the 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 to the STA that is currently using or has the authority to use the medium. Therefore, the value set as the NAV corresponds to the period during which the STA that transmits the frame is scheduled to use the medium, and the STA that receives the NAV value is 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.

[0068] In the example of FIG. 5, assume that STA1 is attempting to transmit data to STA2, and that STA3 is in a position where it may overhear some or all of the frames transmitted between STA1 and STA2.

[0069] In order to reduce the possibility of collision of transmissions of 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, the carrier sensing of STA3 may determine that the medium is idle. That is, STA1 may correspond to a hidden node to STA3. Or, in the example of FIG. 5, while STA2 is transmitting, the carrier sensing of STA3 may determine that the medium is idle. That is, STA2 may correspond to a hidden node to STA3. By exchanging RTS / CTS frames before data transmission / reception between STA1 and STA2, a STA outside the transmission range of either STA1 or STA2, or a STA outside the carrier sensing range for transmissions from STA1 or STA3, may not attempt to occupy the channel during data transmission / reception between STA1 and STA2.

[0070] Specifically, STA1 can determine whether the channel is occupied or not using carrier sensing. In terms of physical carrier sensing, STA1 can determine the channel occupancy idle state based on the energy magnitude or signal correlation detected from the channel. In addition, in terms of virtual carrier sensing, STA1 can determine the channel occupancy state using a network allocation vector (NAV) timer.

[0071] 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, which is a response to the RTS frame, to STA1 after SIFS.

[0072] If STA3 cannot overhear a CTS frame from STA2 but can overhear an RTS frame from STA1, STA3 can set a NAV timer for a frame transmission period (e.g., SIFS+CTS frame+SIFS+data frame+SIFS+ACK frame) that will be transmitted subsequently using duration information included in the RTS frame. Alternatively, if STA3 cannot overhear an RTS frame from STA1 but can overhear a CTS frame from STA2, STA3 can set a NAV timer for a frame transmission period (e.g., SIFS+data frame+SIFS+ACK frame) that will be transmitted subsequently using duration information included in the CTS frame. That is, if STA3 can overhear one or more of the RTS or CTS frames from at least one of STA1 and STA2, it can set the 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 will not attempt channel access until the NAV timer expires.

[0073] When STA1 receives a CTS frame from STA2, it can transmit a data frame to STA2 after SIFS from the point when reception of the CTS frame is completed. When STA2 successfully receives a data frame, it can transmit an ACK frame, which is a response to the data frame, to STA1 after SIFS. When the NAV timer expires, STA3 can determine whether the channel is in use using carrier sensing. When STA3 determines that the channel is not in use by another terminal during the DIFS period after the expiration of the NAV timer, it can attempt channel access after the contention window (CW) with random backoff has passed.

[0074] FIG. 6 is a diagram for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0075] The PHY layer can prepare an MPDU (MAC PDU) to be transmitted according to an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer. For example, when a command requesting the PHY layer to start transmission is received from the MAC layer, the PHY layer switches to a transmission mode and transmits information (e.g., data) provided by the MAC layer in the form of a frame. Also, when the PHY layer detects a valid preamble of a received frame, it monitors the preamble header and sends a command to the MAC layer to inform the PHY layer of the start of reception.

[0076] Thus, information transmission / reception in a wireless LAN system is performed in the form of frames, for which a PHY layer protocol data unit (PPDU) frame format is defined.

[0077] 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 be composed of only Legacy-STF (L-STF), 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) 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).

[0078] 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.

[0079] The SIG field may include a RATE field and 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 parity bits, SIG TAIL bits, etc.

[0080] The data field may include a SERVICE field, a PSDU (Physical layer Service Data Unit), PPDU TAIL bits, 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 include data generated / used by a higher layer. The PPDU TAIL bits 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.

[0081] A 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). A MAC frame is composed of a MAC PDU and may be transmitted / received by a PSDU in the data portion of the PPDU frame format.

[0082] 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, refer to the IEEE 802.11 standard document.

[0083] 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.

[0084] FIG. 7 is a diagram illustrating an example of a PPDU defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0085] Various forms of PPDU are used in standards such as IEEE 802.11a / g / n / ac / ax. The basic PPDU format (IEEE 802.11a / g) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format can also be called non-HT PPDU format.

[0086] The HT PPDU format (IEEE 802.11n) further includes HT-SIG, HT-STF, and HT-LFT(s) fields in 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 be further defined, which corresponds to a format that does not include L-STF, L-LTF, and L-SIG, but is composed of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTFs, and a Data field (not shown).

[0087] 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.

[0088] An example of the HE PPDU format (IEEE 802.11ax) further includes a Repeated L-SIG (RL-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and Packet Extension (PE) field in the basic PPDU format. Depending on the detailed example of the HE PPDU format, some fields may be excluded or their length may change. For example, the HE-SIG-B field is included in the HE PPDU format for multiple users (MU), and the HE-SIG-B is not included in the HE PPDU format for single users (SU). In addition, the HE trigger-based (TB) PPDU format does not include HE-SIG-B, and the length of the HE-STF field may change to 8us. 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 change to 16us.

[0089] 8 to 10 are diagrams for explaining examples of resource units in a wireless LAN system to which the present disclosure can be applied.

[0090] With reference to Fig. 8 to Fig. 10, a resource unit (RU) defined in a wireless LAN system will be described. An RU may include a plurality of subcarriers (or tones). An RU may be used when transmitting signals to a plurality of STAs based on an 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.

[0091] 8 to 10, RUs corresponding to different numbers of tones (i.e., subcarriers) may be used to configure some fields of 20 MHz, 40 MHz, or 80 MHz X-PPDU (X is HE, EHT, etc.). For example, resources may be allocated in units of RUs shown for the X-STF, X-LTF, and Data fields.

[0092] FIG. 8 is a diagram illustrating an exemplary arrangement of resource units (RUs) used on a 20 MHz band.

[0093] As shown at the top of FIG. 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, and there may be 26 units corresponding to 13 tones on each side of the DC band. 26 units, 52 units, or 106 units may be allocated to other bands. Each unit may be allocated for a STA or a user.

[0094] The RU arrangement in Figure 8 can be utilized not only for multiple user (MU) situations, but also for single user (SU) situations, 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.

[0095] In the example of FIG. 8, RUs of various sizes, i.e., 26-RU, 52-RU, 106-RU, 242-RU, etc., are illustrated, but the specific size of such RUs may be reduced or expanded. Therefore, the specific size of each RU (i.e., the number of corresponding tones) is not limited in the present disclosure and is merely exemplary. Also, in the present disclosure, within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, ...), the number of RUs may vary depending on the size of the RU. The examples of FIG. 9 and / or FIG. 10 described below are the same as the examples of FIG. 8 in that the size and / or number of RUs may be changed.

[0096] FIG. 9 is a diagram illustrating an example arrangement of resource units (RUs) used on a 40 MHz band.

[0097] 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.

[0098] Also, as shown in the figure, when used for a single user, 484-RU may be used.

[0099] FIG. 10 is a diagram illustrating an example arrangement of resource units (RUs) used on an 80 MHz band.

[0100] 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. In addition, in the 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 the 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, 7 DC tones are inserted into the DC band, and there is one 26-RU corresponding to 13 tones on each side of the DC band. In the EHT PPDU, 23 DC tones are inserted into the DC band, and there is one 26-RU on the left and right side of the DC band. In the HE PPDU, there is one null subcarrier between the 242-RUs that are not in the center band, but there are five null subcarriers in the EHT PPDU. 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.

[0101] 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.

[0102] An EHT PPDU of 160 MHz or more may be configured with multiple 80 MHz sub-blocks in Fig. 10. The RU allocation for each 80 MHz sub-block may be the same as the RU allocation of the 80 MHz EHT PPDU in Fig. 10. When the 80 MHz sub-blocks of the 160 MHz or 320 MHz EHT PPDU are not punctured and the entire 80 MHz sub-block is used as a part of an RU or MRU (Multiple RU), the 80 MHz sub-block can use 996-RU in Fig. 10.

[0103] Here, the MRU corresponds to a group of subcarriers (or tones) composed of multiple RUs, and the multiple RUs constituting the MRU may be RUs of the same size or may be RUs of 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.). That is, one MRU including RUs of small size and RUs of large size may not be set / defined. In addition, the multiple RUs constituting one MRU may be contiguous or not contiguous in the frequency domain.

[0104] 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 the 996-tone RU.

[0105] The RU of the present disclosure may be used for uplink (UL) and / or downlink (DL) communication. For example, when trigger-based UL-MU communication is performed, a STA (e.g., an AP) that transmits a trigger may use trigger information (e.g., a trigger frame or TRS (triggered response scheduling)) 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. Then, the first STA may 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.

[0106] 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 and can transmit the HE-STF, HE-LTF, and Data fields for the second STA using the second RU in one MU PPDU.

[0107] Information regarding the location of the RU may be signaled in the HE-SIG-B in HE PPDU format.

[0108] FIG. 11 illustrates an example structure of an HE-SIG-B field.

[0109] As shown in the figure, the HE-SIG-B fields may include common fields and user-specific fields. If HE-SIG-B compression is applied (e.g., 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. If HE-SIG-B compression is not applied, the common fields may be included in the HE-SIG-B.

[0110] 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.).

[0111] The common field may include N*8 RU allocation subfields, where N is the number of subfields, and may have values ​​of N=1 for 20 or 40 MHz MU PPDU, N=2 for 80 MHz MU PPDU, N=4 for 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.

[0112] 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.

[0113] As an additional example, if the value of the 8-bit RU allocation subfield is 01000y2y1y0, it can indicate that one 106-RU and five 26-RUs are arranged in sequence 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 in the MU-MIMO manner. 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, when 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.

[0114] 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, ...), multiple users / STAs may be assigned to one RU, and the MU-MIMO scheme may be applied to the multiple users / STAs.

[0115] The set of user-specific fields contains information on how all users (STAs) of the PPDU decode their payload. 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 of HE-SIG-B, the number of symbols of HE-SIG-B, or the MU-MIMO users field of HE-SIG-A. The user-specific fields may be encoded separately or independently from the common fields.

[0116] FIG. 12 is a diagram for explaining the MU-MIMO scheme in which multiple users / STAs are assigned to one RU.

[0117] In the example of FIG. 12, it is assumed 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 it can be indicated 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.

[0118] 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. With reference to an example in 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 include bit information of the same length (e.g., 21 bits).

[0119] 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 (e.g., binary convolutional coding (BCC) or low-density parity check (LDPC)) information applied to the Data field of the PPDU.

[0120] 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 possible (or whether a beamforming steering matrix is ​​applicable), B15 to B18 may include information on modulation and coding scheme (MCS) applied to the Data field of the PPDU, B19 may include information indicating whether dual carrier modulation (DCM) is applicable, and B20 may include information on a coding type (e.g., BCC or LDPC) applied to the Data field of the PPDU.

[0121] The MCS, MCS information, MCS index, MCS field, etc. used in the present disclosure may be represented as a specific index value. For example, the MCS information may be represented as index 0 to index 11. The MCS information may include information about a constellation modulation type (e.g., BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM, 1024-QAM, etc.) and information about a coding rate (e.g., 1 / 2, 2 / 3, 3 / 4, 5 / 6, etc.). The MCS information may omit information about a channel coding type (e.g., BCC or LDPC).

[0122] FIG. 13 shows an example of a PPDU format to which the present disclosure can be applied.

[0123] The PPDU in Fig. 13 may be variously named, 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 variously named, such as transmit PPDU, receive PPDU, first type or Nth type PPDU, etc. Also, the EHT PPU can be used in an EHT system and / or a new wireless LAN system that improves the EHT system.

[0124] The EHT MU PPDU in Fig. 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.

[0125] The EHT-SIG is omitted in the EHT TB PPDU in Fig. 13, unlike the EHT MU PPDU. A STA that receives a trigger for UL MU transmission (e.g., a trigger frame or a TRS) can perform UL transmission based on the EHT TB PPDU format.

[0126] 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.

[0127] 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 determined to be 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 determined to be 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 displayed in units of 312.5 kHz, and the tone / subcarrier indexes of the EHT-STF, EHT-LTF, Data, and PE fields may be displayed in units of 78.125 kHz.

[0128] 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 FIG. 6 and FIG.

[0129] 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 a HE PPDU, the value of the Length field may be determined as a multiple of 3+1 or a multiple of 3+2.

[0130] For example, the transmitting STA may apply BCC encoding based on a coding rate of 1 / 2 to the 24-bit information of the L-SIG field. Then, the transmitting STA may 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 index -21, -7, +7, +21}) and DC subcarriers (e.g., {subcarrier index 0}). As a result, 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 the signal of {-1, -1, -1, 1} to subcarrier indexes {-28, -27, +27, +28}. This signal may be used for channel estimation for the frequency range corresponding to {-28, -27, +27, +28}.

[0131] The transmitting STA can generate a RL-SIG, which is generated identically to the L-SIG. BPSK modulation is applied to the RL-SIG. Based on the presence of the RL-SIG, the receiving STA can determine that the received PPDU is a HE PPDU or an EHT PPDU.

[0132] A U-SIG (Universal SIG) may be inserted after the RL-SIG in Fig. 13. The U-SIG may be variously named, such as a first SIG field, a first SIG, a first type SIG, a control signal, a control signal field, a first (type) control signal, etc.

[0133] The U-SIG may include N-bit 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 4us, and the U-SIG may have a total duration of 8us. Each symbol of the U-SIG may be used to transmit 26-bit information. For example, each symbol of the U-SIG may be transmitted and received based on 52 data tones and 4 pilot tones.

[0134] In the U-SIG (or U-SIG field), for example, A-bit information (e.g., 52 un-coded bits) may be transmitted, and the first symbol of the U-SIG (e.g., U-SIG-1) transmits the first X-bit information (e.g., 26 un-coded 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 un-coded bits) of the total A-bit information. For example, the transmitting STA can obtain the 26 un-coded bits included in each U-SIG symbol. The transmitting STA can perform convolution encoding (e.g., BCC encoding) based on a rate of R=1 / 2 to generate 52-coded bits and perform interleaving on the 52-coded bits. The transmitting STA can 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.

[0135] 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 long field) and a tail field (e.g., a 6-bit long field). The CRC field and the tail field may be transmitted in the second symbol of the U-SIG. The CRC field may be generated based on the 26 bits assigned 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.

[0136] The A-bit information (e.g., 52 un-coded bits) transmitted by the U-SIG (or U-SIG field) can be distinguished 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 the version-dependent bits may be referred to by various names, such as the first control bit and the second control bit.

[0137] For example, the version independent bits of the U-SIG may include a 3-bit physical layer 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 may indicate that the transmitted / received PPDU is an EHT PPDU. In other words, when the transmitting STA transmits an EHT PPDU, the transmitting STA may set the 3-bit physical layer version identifier to a first value. In other words, the receiving STA may determine that the received PPDU is an EHT PPDU based on the physical layer version identifier having the first value.

[0138] For example, the version independent bits of the U-SIG may include a one-bit UL / DL flag field, where a first value of the one-bit UL / DL flag field is associated with UL communications and a second value of the UL / DL flag field is associated with DL communications.

[0139] 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.

[0140] For example, when EHT PPDUs are classified 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.

[0141] For example, the U-SIG may include information regarding 1) a bandwidth field including information regarding the bandwidth, 2) a field including information regarding the MCS technique applied to the EHT-SIG, 3) an indication field including information regarding whether or not a DCM technique is applied to the EHT-SIG, 4) a field including information regarding the number of symbols used for the EHT-SIG, 5) a field including information regarding whether or not the EHT-SIG is generated across the entire band, 6) a field including information regarding the type of EHT-LTF / STF, and 7) a field indicating the length of the EHT-LTF and the CP length.

[0142] Preamble puncturing may be applied to the PPDU in FIG. 13. Preamble puncturing means applying puncturing to a portion of the entire band of the PPDU (e.g., the 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.

[0143] For example, the preamble puncturing pattern may be set in advance. For example, when the first puncturing pattern is applied, puncturing may be applied only to the secondary 20 MHz band in the 80 MHz band. For example, when the second puncturing pattern is applied, puncturing may be applied only to any one of the two secondary 20 MHz bands included in the secondary 40 MHz band in the 80 MHz band. For example, when the third puncturing pattern is applied, puncturing may be applied only to the secondary 20 MHz band included in the primary 80 MHz band in the 160 MHz band (or 80+80 MHz band). For example, when the fourth puncturing pattern is applied, the primary 40 MHz band included in the primary 80 MHz band in the 160 MHz band (or 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.

[0144] The information regarding the 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 regarding the contiguous bandwidth of the PPDU, and a second field of the U-SIG may include information regarding the preamble puncturing applied to the PPDU.

[0145] For example, the U-SIG and the EHT-SIG may include information on preamble puncturing based on the following method. When the bandwidth of the PPDU exceeds 80 MHz, the U-SIG may be configured in units of 80 MHz individually. For example, when the bandwidth of the 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 on the 160 MHz bandwidth, and the second field of the first U-SIG may include information on the preamble puncturing applied to the first 80 MHz band (i.e., information on the preamble puncturing pattern). Also, the first field of the second U-SIG may include information on the 160 MHz bandwidth, and the second field of the second U-SIG may include information on the preamble puncturing applied to the second 80 MHz band (i.e., information on 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).

[0146] Additionally or alternatively, the U-SIG and the EHT-SIG may include information regarding preamble puncturing based on the following method: The U-SIG may include information regarding preamble puncturing for the entire band (i.e., information regarding the preamble puncturing pattern). That is, the EHT-SIG may not include information regarding preamble puncturing, and only the U-SIG may include information regarding preamble puncturing (i.e., information regarding the preamble puncturing pattern).

[0147] The U-SIG may be configured in units of 20 MHz. For example, when an 80 MHz PPDU is configured, the 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.

[0148] The EHT-SIG in FIG. 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 4us. Information regarding the number of symbols used for the EHT-SIG may be included in the U-SIG.

[0149] 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, the same as 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.

[0150] 11, the common fields of the EHT-SIG and the user-specific fields of the EHT-SIG may be coded separately. A user block field included in the user-specific fields includes information for two user fields, but the last user block field included in the user-specific fields may include one or two user fields. That is, a user block field of the EHT-SIG may include up to two user fields. Similarly to the example of FIG. 12, each user field may be associated with a MU-MIMO allocation or a non-MU-MIMO allocation.

[0151] Consistent with 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.

[0152] As in the example of FIG. 11, the common field of the EHT-SIG may include RU allocation information. The RU allocation information may refer to information about the location 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.

[0153] 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.

[0154] The EHT-SIG may be configured based on various MCS schemes. As described above, information regarding 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, among N data tones (e.g., 52 data tones) allocated for the EHT-SIG, a first modulation scheme may be applied to consecutive half tones, and a second modulation scheme may be applied to the remaining consecutive half 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 the consecutive half 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 tones. As described above, information regarding whether the DCM scheme is applied to the EHT-SIG (e.g., a 1-bit field) may be included in the U-SIG. The EHT-STF in FIG. 13 may be used to improve automatic gain control (AGC) estimation in a MIMO environment or an OFDMA environment. The EHT-LTF of FIG. 13 may be used to estimate a channel in a MIMO or OFDMA environment.

[0155] Information regarding the type of STF and / or LTF (including information regarding the guard interval (GI) applied to the LTF) may be included in the U-SIG field and / or EHT-SIG field of FIG. 13, etc.

[0156] The PPDU in FIG. 13 (ie, the EHT PPDU) may be configured based on the example of the RU arrangement in FIGS.

[0157] For example, an EHT PPDU transmitted on a 20 MHz band, i.e., a 20 MHz EHT PPDU, may be configured based on the RU in Fig. 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 Fig. 8. An EHT PPDU transmitted on a 40 MHz band, i.e., a 40 MHz EHT PPDU, may be configured based on the RU in Fig. 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 Fig. 9.

[0158] 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 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.

[0159] The tone plan for 160 / 240 / 320 MHz may be configured to repeat the pattern of FIG. 9 or FIG. 10 multiple times.

[0160] The PPDU in FIG. 13 may be identified as an EHT PPDU based on the following method.

[0161] The receiving STA may determine the type of the received PPDU as 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 as EHT PPDU. If the received PPDU is determined as EHT PPDU, the receiving STA may 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 may determine the received PPDU as EHT PPDU based on 1) the first symbol after the L-LTF signal which is BSPK, 2) an RL-SIG which is consecutive to the L-SIG field and is the same as the L-SIG, and 3) an L-SIG including a Length field in which the result of applying modulo 3 is set to 0.

[0162] 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.

[0163] 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 as 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 as 0, the received PPDU may be determined as a non-HT, HT, or VHT PPDU.

[0164] 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 transmit and receive one or more (simultaneous) control frames, management frames, or data frames.

[0165] Below, we will explain TWT (target wake time).

[0166] TWT is a power saving (PS) technology that can improve the energy efficiency of non-AP STAs by defining a service period (SP) between an AP and non-AP STAs, sharing information about the SP, and reducing medium contention. An STA that makes a request / suggest / demand in the TWT setup phase can be called a TWT requesting STA. An AP that responds to the request by accepting / rejecting can be called a TWT responding STA. The setup phase may include a process of determining / defining a TWT request from an STA to an AP, the type of TWT operation to be performed, and the frame type to be transmitted and received. TWT operations can be divided into individual TWT and broadcast TWT.

[0167] FIG. 14 is a diagram for explaining an example of an individual TWT operation to which the present disclosure can be applied.

[0168] Individual TWT is a mechanism for data exchange after AP and non-AP STA negotiate the awake / doze status of non-AP STA by transmitting and receiving TWT request / response frames. In the example of FIG. 14, AP and STA1 can form a trigger-enabled TWT agreement by a TWT request frame and a TWT response frame. Here, the method used by STA1 is a solicited TWT method, in which STA1 transmits a TWT request frame to the AP and receives information for TWT operation from the AP using a TWT response frame. Meanwhile, STA2 using an unsolicited TWT method can receive information on the setting of a trigger-enabled TWT agreement 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 transmit 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 transmitting a PS-Poll frame. Also, STA2 can inform the AP of its awake state by transmitting a QoS Null frame. Here, the data frames transmitted by STA1 and STA2 can be frames in TB PPDU format. After checking the states of STA1 and STA2, the AP can transmit DL MU PPDU to the awake STAs. When the TWT SP expires, STA1 and STA2 can switch to a doze state.

[0169] FIG. 15 is a diagram for explaining an example of a broadcast TWT operation to which the present disclosure can be applied.

[0170] The broadcast TWT is a TWT in which a non-AP STA (or a TWT scheduling STA) obtains information on a target beacon transmission time (TBTT) and a listen interval by transmitting and receiving a TWT request / response frame with an AP (or a 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 may 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 process of an individual TWT. In the broadcast TWT, a trigger-enabled TWT SP including a beacon frame may be repeated multiple times at a certain period.

[0171] The TWT information may be conveyed by a TWT information frame and a TWT information element.

[0172] FIG. 16 is a diagram illustrating an example of a TWT information element format.

[0173] The TWT information frame is sent by a STA to request or deliver information about a TWT agreement and is sent by one of the STAs of 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.

[0174] The size of the TWT information field may vary depending on the size of the next TWT field. The TWT flow identifier subfield includes an 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.

[0175] The response requested subfield can indicate whether the STA transmitting the frame including the TWT information field requests that a TWT information frame be transmitted in response to the frame. When the response requested subfield is set to 0, the STA can be requested not to transmit a TWT information frame in response to the frame. When the response requested subfield is set to 1, the STA can be requested to transmit a TWT information frame in response to the frame.

[0176] The next TWT request subfield may be set to 1 to 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.

[0177] 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.

[0178] 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.

[0179] 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 a timing synchronization function (TSF) in the next TWT for the TWT identified by the TWT flow identifier subfield.

[0180] FIG. 17 is a diagram illustrating an example of a TWT information element format.

[0181] 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.

[0182] The control field of the TWT information element has the same format regardless of whether it is an individual TWT or a broadcast TWT.

[0183] The NDP paging indication subfield may have a value of 1 if the NDP paging field is present and may have a value of 0 if the NDP paging field is not present.

[0184] The responder PM mode subfield may indicate a Power Management (PM) mode.

[0185] The negotiation type subfield may indicate whether the information contained in the TWT element is for negotiation of parameters of a broadcast TWT or individual TWT(s), or for a wake TBTT interval.

[0186] For example, if the negotiation type subfield has a value of 0, the TWT subfield is for 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 the TWT requester STA and the TWT responder STA, or an individual TWT announcement by the TWT responder.

[0187] For example, when the negotiation type subfield has a value of 1, the TWT subfield is for the next TBTT time, and the TWT element includes 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.

[0188] 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.

[0189] 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 correspond to 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.

[0190] The TWT information frame disabled subfield may be set to 1 to indicate that reception of TWT information frames by the STA is disabled; otherwise, it may be set to 0.

[0191] The wake duration unit subfield indicates the units of the nominal minimum TWT wake duration field. The wake duration unit subfield may be set to 0 if the unit is 256us and set to 1 if the unit is TU. If not a HE / EHT STA, the wake duration unit subfield may be set to 0.

[0192] The most significant bit (MSB) of the negotiation type field may correspond to a broadcast field. If the broadcast field is 1, one or more broadcast TWT parameter sets may be included in the TWT element. If the broadcast field is 0, only one individual TWT parameter set may be included in the TWT element. A TWT element with the broadcast field set to 1 may be referred to as a broadcast TWT element.

[0193] 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.

[0194] 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.

[0195] If it is an individual TWT, the TWT parameter information field in the TWT element contains a single individual TWT parameter set field.

[0196] 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.

[0197] As shown in Figures 18 and 19, the individual TWT parameter set field and the broadcast TWT parameter set field include common subfields.

[0198] 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 described below.

[0199] The target wake time subfield indicates the start time of a later scheduled individual / broadcast TWT SP.

[0200] The nominal maximum TWT wake duration subfield indicates the minimum unit that the TWT requesting STA expects to have to wake up to complete a frame exchange associated with the TWT flow identifier in the TWT wake interval duration, where the TWT wake interval may refer to the average time between consecutive TWT SPs that the TWT requesting STA expects.

[0201] The TWT Wake Interval Mantissa subfield is the binary value of the TWT wake interval value, expressed in microseconds.

[0202] Referring to FIG. 18, the TWT group assignment subfield, the TWT channel, and the NDP paging subfields are only included in the individual TWT parameter set field.

[0203] The TWT group assignment subfield provides the TWT requesting STA with information about the TWT group to which the STA is assigned. The TWT value in the TWT group can be calculated using this information. The TWT value of the STA may be equal to the value of the zero offset and the value of the TWT offset multiplied by the value of the TWT unit.

[0204] The TWT Channel subfield indicates a bitmap indicating allowed channels. When sent by a TWT requesting STA, the TWT Channel subfield may include a bitmap indicating channels that the STA requests to use as temporary fundamental channels in the TWT SP. When sent by a TWT responding STA, the TWT Channel subfield may include a bitmap indicating channels on which the TWT request is allowed.

[0205] The NDP paging subfield is optional and may include an identifier of the STA being paged, information regarding the maximum number of TWT wake intervals between NDP paging frames, etc.

[0206] Referring to FIG. 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 for which a STA requests to join 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.

[0207] Next, the detailed structure of the request type subfield will be described.

[0208] First, the format of the request type subfield of the individual TWT parameter set field will be described with reference to FIG.

[0209] The TWT request subfield can indicate whether it is a requesting STA or a responding STA. If its value is 1, it indicates that it is a TWT requesting STA or a scheduled STA, and if its value is 0, it indicates that it is a TWT responding STA or a scheduling AP.

[0210] The TWT setup command subfield can indicate commands such as Request, Suggest, Demand, Accept, Alternate, Dictate, and Reject.

[0211] The trigger subfield indicates whether or not a trigger frame is used in the TWT SP. If the value is 1, the trigger is used, and if the value is 0, the trigger is not used.

[0212] The implicit subfield can indicate implicit or explicit TWT, with a value of 1 indicating implicit TWT and a value of 0 indicating explicit TWT.

[0213] 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 the value is 1, it can indicate announced TWT in which the STA transmits a PS-Poll or APSD (automatic power save delivery) trigger frame and sends a wake-up signal to the AP before a frame other than the trigger frame is transmitted from the AP to the STA. If the value is 0, it can indicate unknown TWT.

[0214] 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.

[0215] The TWT wake interval exponent subfield can set the TWT wake interval value in binary microseconds. In the case of an individual TWT, it can mean 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].

[0216] The TWT protection subfield can indicate whether to use a TWT protection mechanism. If its value is 1, the TXOP in the TWT SP may be initiated with a NAV protection mechanism such as a (MU)RTS / CTS or CTS-to-self frame, and if its value is 0, the NAV protection mechanism may not be applied.

[0217] 19, some of the subfields of the Request Type subfield of the Broadcast TWT Parameter Set field are common to the subfields of the Request Type subfield of the Individual TWT Parameter Set field, and therefore the description thereof will be omitted. The subfields included only in the Broadcast TWT Parameter Set field will be described below.

[0218] The Last Broadcast Parameter Set subfield indicates whether it is the last broadcast TWT parameter set. If the value is 1, it indicates that it is the last broadcast TWT parameter set, and if the value is 0, it indicates that there is a next broadcast TWT parameter set.

[0219] The broadcast TWT recommendation subfield may indicate a recommendation for the frame type to be transmitted by the AP in the broadcast TWT SP with a value from 1 to 7.

[0220] The last bit of the request type subfield of the broadcast TWT parameter set field may be reserved.

[0221] Restricted TWT related operation methods

[0222] Compared with a cellular wireless communication network system based on radio resource scheduling, a contention-based medium access scheme of a wireless LAN system may have a relatively difficult time supporting latency-sensitive traffic. Restricted TWT (R-TWT) may be one of various schemes considered for supporting transmission and reception of latency-sensitive traffic in a wireless LAN system.

[0223] The R-TWT may correspond to a special broadcast TWT that the AP sets for low latency STAs (i.e., STAs that support transmission of latency sensitive data). The R-TWT can be used to help ensure data transmission availability for low latency STAs with priority over other STAs. The STAs can establish membership to one or more R-TWT schedules with the AP. Here, the R-TWT agreement may be established by the same process as the broadcast TWT agreement, and the broadcast TWT element therefor 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 distinguished 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. The AP can also announce the R-TWT SP.

[0224] A STA supporting a broadcast TWT limited service period (SP), i.e., an 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 the R-TWT operation / mode, the AP can transmit a frame including scheduling information of the TWT requested by each STA to the low latency STA and other STAs. For example, to perform an operation on the R-TWT, 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 other undefined format (e.g., a broadcast, advertisement, or public use frame). Although a beacon frame is taken as a frame including the R-TWT-related information to be publicly announced, the R-TWT-related information may be publicly announced by various management frames as described above.

[0225] According to the R-TWT operation, a separate TXOP (i.e., a TXOP with restricted access for other STAs) can be reserved in the R-TWT SP using NAVs such as (MU)RTS / CTS or CTS-to-self, or a quiet interval, etc. Before the R-TWT SP is started, any TXOPs of other STAs (i.e., non-member STAs) other than the STAs having membership to the R-TWT schedule must be stopped. Then, the TXOPs of other STAs (i.e., non-member STAs) may be made after the R-TWT SP is over.

[0226] The following describes a method related to rescheduling of an R-TWT SP. In this disclosure, an R-TWT SP may also be referred to as an RSP. Rescheduling of an RSP may include, after the allocation for an RSP is completed, an indication of information related to rescheduling, such as suspension, extension, resume, and end, for the allocated RSP, and an RSP-related operation of the STA based on such information.

[0227] Referring again to Figure 16, the TWT information frame (i.e., a frame including the TWT information field) may be used for signaling to suspend or resume a TWT SP under an existing individual TWT or broadcast TWT agreement. For example, if the value of the All TWT subfield in the TWT information field in Figure 16 is 1, the value of the Next TWT subfield can indicate the time when the TWT SP is resumed. The existing TWT information field only indicates rescheduling related information for SP for individual TWT or broadcast TWT, and cannot indicate rescheduling related information for R-TWT SP.

[0228] This disclosure describes a new scheme for indicating that the TWT information field is for an R-TWT SP when signaling the TWT information field, and a new scheme for indicating whether data transmission / reception between an AP and a STA or data transmission / reception between STAs (i.e., P2P transmission / reception) is performed within the R-TWT SP. For example, in this disclosure, P2P transmission / reception may include a case where the R-TWT SP itself is defined or configured for P2P transmission / reception, or a case where a TXOP for P2P transmission / reception is identified by a TXOP sharing procedure triggered within the R-TWT SP, etc.

[0229] In the following description, a STA may correspond to an AP STA or a non-AP STA.

[0230] FIG. 20 is a diagram for explaining the operation of a STA that supports rescheduling of an R-TWT SP according to an embodiment of the present disclosure.

[0231] In step S2010, the STA may establish an R-TWT-related agreement.

[0232] An agreement for R-TWT may be established between an AP STA and a non-AP STA. The TWT agreement may be established based on an exchange of a TWT request and a TWT response.

[0233] When the STA is a non-AP STA, after establishing an agreement on R-TWT with the AP STA, the STA can receive first R-TWT SP allocation information based on the R-TWT agreement from the AP STA in a management frame such as a beacon frame.

[0234] When a STA is an AP STA, after establishing an agreement on R-TWT with a non-AP STA, the first R-TWT SP allocation information based on the R-TWT agreement can be transmitted to one or more non-AP STAs in a management frame such as a beacon frame.

[0235] In step S2020, the STA may transmit a frame including a TWT information field to one or more other STAs.

[0236] When a STA is a non-AP STA, one or more of the other STAs may be AP STAs.

[0237] When the STA is an AP STA, the one or more other STAs may be one or more non-AP STAs.

[0238] A frame including the TWT information field may be a TWT information frame. The TWT information field may include an all TWT subfield, a TWT flow identifier subfield, and a next TWT subfield.

[0239] The value of the all TWT subfield may be set to 1, and the TWT flow identifier subfield may be set to a specific value instead of being reserved. In this case, the next TWT subfield may indicate rescheduling related information for the R-TWT SP corresponding to the specific value of the TWT flow identifier.

[0240] For example, the rescheduling related information may include one or more of the following: presence or absence of a suspension for the R-TWT SP, a resume timing reference, or an extended end timing.

[0241] Specifically, a particular value of the TWT flow identifier subfield may be associated with an existing R-TWT SP or a rescheduled R-TWT SP. For example, a first value of the TWT flow identifier subfield may indicate an existing R-TWT SP, and a second value may indicate a rescheduled R-TWT SP. For example, a third value of the TWT flow identifier subfield may indicate an existing R-TWT SP, and a fourth value may indicate a rescheduled R-TWT SP.

[0242] Additionally or alternatively, a particular value of the TWT flow identifier subfield may be associated with a first or second type of R-TWT SP, where the first type may correspond to uplink or downlink transmission or reception between a non-AP STA and an AP STA, and the second type may correspond to peer-to-peer (P2P) transmission or reception between a non-AP STA and a non-AP STA. For example, a first value of the TWT flow identifier subfield may be associated with the first type, and a third value of the TWT flow identifier subfield may be associated with the second type. Also, a second value of the TWT flow identifier subfield may be associated with the first type, and a fourth value of the TWT flow identifier subfield may be associated with the second type.

[0243] Additionally or alternatively, a particular value of the TWT flow identifier subfield may be associated with a grace period or an extension of an existing R-TWT SP. For example, a first value of the TWT flow identifier subfield may indicate a grace period of an existing R-TWT SP, a second value may be associated with an extension of an existing R-TWT, a third value of the TWT flow identifier subfield may indicate a grace period of an existing R-TWT SP, and a fourth value may be associated with an extension of an existing R-TWT.

[0244] In addition, the TWT flow identifier subfield can be combined with the next TWT subfield to indicate information related to rescheduling of the R-TWT SP.

[0245] For example, for the same value of the TWT flow identifier subfield, the next TWT subfield may be set to a value of 0 to indicate a delay of the R-TWT SP, and the next TWT subfield may be set to a value greater than 0 to indicate a resumption timing reference. For example, when the TWT flow identifier subfield has a first value, the next TWT subfield may be set to a value of 0 to indicate a delay of the R-TWT SP, and the next TWT subfield may be set to a value greater than 0 to indicate a timing reference for resuming the R-TWT SP. Also, when the TWT flow identifier subfield has a third value, the next TWT subfield may be set to a value of 0 to indicate a delay of the R-TWT SP associated with P2P, and the next TWT subfield may be set to a value greater than 0 to indicate a timing reference for resuming the R-TWT SP associated with P2P. Here, the R-TWT SP resumption timing reference may correspond to the first R-TWT SP after the value of the next TWT subfield (e.g., a value greater than 0).

[0246] Additionally or alternatively, different values ​​of the TWT flow identifier subfield may indicate an R-TWT SP resume timing reference or an extended end time when the next TWT subfield is set to a value greater than 0. For example, when the next TWT subfield has a value greater than 0, the value of the next TWT subfield may indicate an R-TWT resume timing reference when the TWT flow identifier subfield is set to a first value, and may indicate an extended end time of the R-TWT SP when the TWT flow identifier subfield is set to a second value. Also, when the next TWT subfield has a value greater than 0, the value of the next TWT subfield may indicate a P2P related R-TWT resume timing reference when the TWT flow identifier subfield is set to a third value, and may indicate an extended end time of the P2P related R-TWT SP when the TWT flow identifier subfield is set to a second value.

[0247] When the STA is a non-AP STA, after transmitting a frame including a TWT information field, the STA may receive rescheduled second R-TWT SP allocation information (e.g., reflecting the grace / resume / extension of the R-TWT SP indicated in the TWT information field) from the AP STA in a management frame such as a beacon frame.

[0248] If the STA is an AP STA, after transmitting a frame including the TWT information field, it may transmit rescheduled second R-TWT SP allocation information (e.g., reflecting the grace / resume / extension of the R-TWT SP indicated in the TWT information field) to one or more non-AP STAs in a management frame, such as a beacon frame.

[0249] In the following, a specific example of the present disclosure for rescheduling R-TWT SP will be described.

[0250] As described above, according to the definition of the existing TWT information frame or TWT information field described with reference to Fig. 16, when the value of the All TWT subfield is 1, the value of the TWT flow identifier subfield is reserved. In the present disclosure, the definition of the existing TWT flow identifier subfield is modified, and a new case can be defined in which the TWT flow identifier subfield is set to a specific value (e.g., a value within a range of 1 to 7) when the value of the All TWT subfield is 1. The specific value of the TWT flow identifier subfield can indicate that the TWT SP is for an R-TWT SP, not an individual TWT SP or a broadcast TWT SP.

[0251] A specific example of the present disclosure for the use of the TWT information frame or TWT information field for the R-TWT is as follows:

[0252] [Table 1]

[0253] In Table 1, the first, second, third and fourth values ​​of the TWT flow identifier subfield may be 2, 3, 4 and 5, respectively. However, the scope of the present disclosure is not limited to the specific values ​​to which the TWT flow identifier subfield may be set, and the feature of the present disclosure is the rescheduling operation related to the R-TWT SP that the specific value of the TWT flow identifier subfield (or in combination with the Next TWT subfield) indicates. For example, when the value of the All TWT subfield is 1, the value of the TWT flow identifier subfield can indicate whether it is an R-TWT SP or a rescheduled R-TWT SP based on the value of Next TWT.

[0254] In the example of Table 1, T_resume may correspond to a resume timing reference, and T_end may correspond to an extended end point and may have a value based on the TSF.

[0255] FIG. 21 is a diagram illustrating an example of the postponement and resumption of an R-TWT SP according to the present disclosure.

[0256] 21 shows an example of a TWT information frame for an R-TWT SP (RSP) when the value of the TWT flow identifier subfield is 2. The AP can first use a management frame such as a beacon frame to provide RSP allocation information to one or more STAs (including RSP STA 1) that have been assigned an R-TWT SP.

[0257] To indicate that it will not utilize the allocated R-TWT SP, RSP STA 1 may transmit a TWT information frame with the All TWT subfield set to a value of 1, the TWT flow identifier subfield set to 2, and the next TWT subfields set to a value of 0.

[0258] When RSP STA1 receives an ACK for the TWT information frame as above, it does not transmit or receive data through the R-TWT SP (e.g., RSP #1 and RSP #2) until it resumes the R-TWT SP. In other words, the RSP may be postponed or temporarily suspended.

[0259] To indicate that the RSP STA 1 resumes the R-TWT SP, it may transmit a TWT information frame in which the All TWT subfield is set to a value of 1, the TWT flow identifier subfield is set to a value of 2, and the value of the Next TWT subfield is set to a value greater than 0. Here, it is assumed that the value of the Next TWT subfield is T_resume. T_resume may correspond to the resume timing reference.

[0260] RSP STA1, which receives an ACK for the above TWT information frame, can transmit and receive data from RSP #3, which is the first RSP after T_resume.

[0261] FIG. 22 is a diagram for explaining an example of the suspension and resumption of R-TWT SP related to P2P according to the present disclosure.

[0262] 22 shows an example of a TWT information frame for an R-TWT SP (RSP) when the value of the TWT flow identifier subfield is 4. The AP may first use a management frame such as a beacon frame to provide RSP allocation information to multiple STAs (including RSP STA 1 and RSP STA 2) that have been assigned the R-TWT SP. For example, the R-TWT SP may be configured for P2P transmission and reception, or P2P transmission and reception may be performed within a TXOP specified by separate signaling for P2P transmission and reception within the R-TWT SP (e.g., P2P assisted mode of a triggered TXOP sharing procedure).

[0263] To indicate that it will not utilize the allocated R-TWT SP, RSP STA 1 may transmit a TWT information frame with the All TWT subfield set to a value of 1, the TWT flow identifier subfield set to 4, and the next TWT subfields set to a value of 0.

[0264] The RSP STA 1 that receives the ACK for the TWT information frame as described above does not transmit or receive data (especially P2P transmission or reception) in the R-TWT SP (e.g., RSP #1 and RSP #2) until the R-TWT SP is resumed. In other words, the RSP related to P2P may be postponed or temporarily suspended.

[0265] The AP that receives the TWT information frame as described above can inform the RSP STAs having the same broadcast TWT ID that the RSP is suspended or paused. For example, the AP can inform the RSP STAs (including RSP STA 2) that have been assigned the R-TWT SP together with RSP STA 1, i.e., have the same broadcast TWT ID, by using a management frame such as a beacon frame that the P2P operation in the R-TWT SP performed by RSP STA 1 is suspended or paused until it is resumed.

[0266] Upon receiving such information, RSP STA 2 will not transmit or receive data (especially P2P) through the R-TWT SPs (e.g., RSP #1 and RSP #2) until the R-TWT SP is resumed. In other words, the RSPs related to P2P may be postponed or temporarily suspended.

[0267] Additionally or alternatively, since P2P transmission and reception is triggered from the AP, the AP does not need to inform other STAs that P2P-related RSPs are deferred.

[0268] To indicate that RSP STA 1 desires to resume the R-TWT SP associated with P2P, it may transmit a TWT information frame with the All TWT subfield value set to 1, the TWT flow identifier subfield value set to 4, and the Next TWT subfield value set to a value greater than 0. Here, it is assumed that the value of the Next TWT subfield is T_resume. T_resume may correspond to a resume timing reference.

[0269] RSP STA1, which has received an ACK for the TWT information frame as described above, can transmit and receive data from RSP #3, which is the first RSP after T_resume.

[0270] The AP that receives the TWT information frame can inform the RSP STAs having the same broadcast TWT ID that the RSP will be resumed. For example, the AP can inform the RSP STAs (including RSP STA 2) that are assigned the R-TWT SP together with RSP STA 1, i.e., have the same broadcast TWT ID, by using a management frame such as a beacon frame that the P2P operation in the R-TWT SP performed by RSP STA 1 will be resumed.

[0271] RSP STA2 that receives such information can perform data transmission / reception (particularly P2P transmission / reception) at that RSP (for example, RSP #3 that is the first RSP after T_resume).

[0272] Additionally or alternatively, the AP may provide information to the RSP STA 2 to trigger P2P transmission / reception without informing other STAs that the P2P-related RSP is resumed.

[0273] FIG. 23 is a diagram for explaining an example related to the extension of an R-TWT SP according to the present disclosure.

[0274] 23 shows an example of a TWT information frame for an R-TWT SP (RSP) when the value of the TWT flow identifier subfield is 3. The AP can first use a management frame such as a beacon frame to provide RSP allocation information to one or more STAs (including RSP STA 1) that have been assigned an R-TWT SP.

[0275] As mentioned above, the TXOP of a STA that does not belong to an R-TWT SP must be stopped before any R-TWT SP starts. For example, the TXOP of non-RSP STA 2 should be interrupted because it does not belong to an RSP. However, if STA 2's TXOP does not need to prioritize the R-TWT SP, such as for latency-sensitive traffic, the start point of the R-TWT SP may be delayed, and therefore the end point of the R-TWT SP may also be delayed. This can be called an extended R-TWT SP.

[0276] In the example of FIG. 23, an extended RSP occurs due to the TXOP of STA 2, and the AP can use the TWT information frame transmitted to indicate that the initially allocated RSP is extended. In such a TWT information frame, the value of the All TWT subfield may be set to 1, the TWT flow identifier subfield may be set to 3, and the value of the next TWT subfield may be set to a value greater than 0. Here, the value of the next TWT subfield is assumed to be T_end. That is, T_end can indicate the end point of the extended RSP.

[0277] If the R-TWT SP is assigned to multiple STAs based on a broadcast TWT, the Receiver Address (RA) field of the TWT information frame may be set to a broadcast address and transmitted in a broadcast manner.

[0278] An RSP STA (e.g., RSP STA 1) that receives an ACK for the above-mentioned TWT information frame can transmit and receive data within the RSP based on the fact that the end point of the R-TWT SP is extended to the T_end point.

[0279] FIG. 24 is a diagram for explaining an example related to an extension of an R-TWT SP related to P2P according to the present disclosure.

[0280] 24 shows an example of a TWT information frame for a P2P-related R-TWT SP (RSP) when the value of the TWT flow identifier subfield is 5. The AP may first use a management frame such as a beacon frame to provide RSP allocation information to one or more STAs (including RSP STA 1 and RSP STA 2) that have been assigned an R-TWT SP.

[0281] In the example of Figure 24, an extended RSP occurs due to a TXOP of a non-RSP STA3, and the AP can use a TWT information frame transmitted to indicate that the initially allocated P2P-related RSP is extended. Such a TWT information frame may have the All TWT subfield set to a value of 1, the TWT flow identifier subfield set to 5, and the next TWT subfield set to a value greater than 0. Here, the value of the next TWT subfield is assumed to be T_end. That is, T_end can indicate the end point of the extended P2P-related RSP.

[0282] If the R-TWT SP is assigned to multiple STAs based on a broadcast TWT, the receiver address (RA) field of the TWT information frame may be set to a broadcast address and transmitted in a broadcast manner.

[0283] An RSP STA (e.g., RSP STA 1) that receives an ACK for the above-mentioned TWT information frame can transmit and receive data within the RSP based on the fact that the end point of the R-TWT SP is extended to the T_end point.

[0284] The above-described embodiments are combinations of the components and features of the present disclosure in a predetermined form. Each component or feature should be considered as optional unless otherwise expressly stated. Each component or feature may be implemented in a form not combined with other components or features. It is also possible to combine some components and / or features to configure the embodiments of the present disclosure. The order of operations described in the embodiments of the present disclosure may be changed. Some configurations or features of one embodiment may be included in another embodiment, or may be replaced with corresponding configurations 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 configure an embodiment, or may be included as a new claim by amendment after filing.

[0285] 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 a reasonable interpretation of the attached claims, and any modifications within the equivalent scope of the present disclosure are included in the scope of the present disclosure.

[0286] 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 the various embodiments, and non-transitory computer-readable media on which such software or instructions or the like can be stored and executed on a device or computer. Instructions available for programming a processing system to perform features described in the present disclosure may be stored on / 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 the present disclosure. The storage medium may include high-speed random access memory, such as DRAM, SRAM, DDR RAM, or other random access solid-state memory devices, but is not limited thereto, and may include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state storage devices. The memory optionally includes one or more storage devices that are located remotely from the processor. The memory or alternatively the non-volatile memory devices in the memory include 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]

[0287] 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 a station (STA) in a wireless LAN system, the method comprising: establishing an agreement relating to a restricted target wake time (R-TWT); transmitting a frame including a TWT information field to one or more other STAs; The method further comprises: setting a value of an all TWT subfield of the TWT information field to 1 and setting a TWT flow identifier subfield of the TWT information field to a specific value, based on which a next TWT subfield of the TWT information field indicates rescheduling related information for an R-TWT service period (SP) corresponding to the specific value.

2. 2. The method of claim 1, wherein the rescheduling related information includes one or more of: presence or absence of a suspension, a resume timing reference, or an extended end timing.

3. The method of claim 1 , wherein the particular value of the TWT flow identifier subfield is associated with an existing R-TWT SP or a rescheduled R-TWT SP.

4. The particular value of the TWT flow identifier subfield is associated with a first or second type of R-TWT SP; The method of claim 1, wherein the types of the R-TWT SP include a first type for uplink or downlink transmission or reception between a non-access point (non-AP) STA and an AP STA, and a second type for peer-to-peer (P2P) transmission or reception between a non-AP STA and a non-AP STA.

5. The method of claim 1 , wherein the particular value of the TWT flow identifier subfield is associated with a grace or extension of an existing R-TWT SP.

6. For the same value of the TWT flow identifier subfield, The Next TWT subfield set to a value of 0 indicates a grace period; 2. The method of claim 1, wherein the next TWT subfield set to a value greater than zero indicates a restart timing reference.

7. 7. The method of claim 6, wherein the resume timing reference corresponds to a first R-TWT SP after the value of the next TWT subfield.

8. based on the next TWT subfield being set to a value greater than zero, The TWT flow identifier subfield set to a first value indicates that the TWT flow is resumed at the first R-TWT SP after the value of the next TWT subfield; The method of claim 1 , wherein the TWT flow identifier subfield set to a second value indicates that the value of the next TWT subfield indicates an extended end point.

9. The STA is a non-AP STA scheduled for R-TWT; The method of claim 1 , wherein the one or more other STAs are AP STAs.

10. receiving a management frame including a first R-TWT SP allocation information based on an agreement associated with the R-TWT from the AP STA before transmitting a frame including the TWT information field; 10. The method of claim 9, further comprising: receiving a management frame including rescheduled second R-TWT SP allocation information from the AP STA after transmitting the frame including the TWT information field.

11. The STA is an AP STA that performs R-TWT scheduling; The method of claim 1 , wherein the one or more other STAs are one or more non-AP STAs.

12. transmitting a management frame including a first R-TWT SP allocation information based on an agreement associated with the R-TWT to the one or more non-STAs before transmitting a frame including the TWT information field; 12. The method of claim 11, further comprising: transmitting a management frame including rescheduled second R-TWT SP allocation information to the one or more non-STAs after transmitting the frame including the TWT information field.

13. A station (STA) device of a wireless LAN system, the STA device comprising: one or more transceivers; one or more processors coupled to the one or more transceivers; The one or more processors: Establishing an agreement related to a restricted target wake time (R-TWT); configured to transmit a frame including a TWT information field to one or more other STAs through the one or more transceivers; The device, based on the value of the all TWT subfield of the TWT information field being set to 1 and the TWT flow identifier subfield of the TWT information field being set to a specific value, wherein the next TWT subfield of the TWT information field indicates rescheduling related information for an R-TWT service period (SP) corresponding to the specific value.

14. 1. A processing unit configured to control a station (STA) in a wireless LAN system, the processing unit comprising: one or more processors; and one or more computer memories operably coupled to the one or more processors and storing instructions for performing the method of any one of claims 1 to 12 when executed by the one or more processors.

15. One or more non-transitory computer-readable media storing one or more instructions, The one or more instructions are executed by one or more processors to provide a station (STA) device in a wireless LAN system. to perform the method according to any one of claims 1 to 12.

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