Method and apparatus for performing restricted target wake-time based communication in wireless LAN system

Abstract

To provide a method and apparatus for performing communication in a wireless LAN system.SOLUTION: A method for performing communication by a first 1STA in a wireless local area network (LAN) system, the method comprising: performing an r-TWT membership setup procedure with the first 2STA; and receiving r-TWT schedule information included in a broadcast TWT component from the first 2STA, wherein, based on that a specific part of the first 1TXOP in an r-TWTSP announced by the r-TWT schedule information is not used for delivering a DL frame corresponding to at least one r-TWTDLTID or requesting a UL frame corresponding to at least one r-TWTULTID, the first 1TXOP may end before the start time of the r-TWTSP.SELECTED DRAWING: Figure 20

Description

[Technical Field]

[0001] The present disclosure relates to a method and apparatus for performing communications in a wireless local area network (WLAN) system, and more particularly to a method and apparatus for performing restricted target wake time (TWT)-based communications in a next-generation WLAN system. [Background technology]

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

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

[0004] A technical problem of the present disclosure is to provide a method and apparatus for transmitting latency sensitive data / traffic in a wireless LAN system.

[0005] A further technical object of the present disclosure is to provide a method and apparatus for implementing conditional r-TWT SP (service period) TXOP rules in a wireless LAN system.

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

[0007] A method for communicating by a first STA in a WLAN system according to one embodiment of the present disclosure includes: performing a restricted target wake time (r-TWT) membership setup procedure with a second STA; and receiving r-TWT schedule information included in a broadcast TWT element from the second STA. The first TXOP may terminate before a start time of the r-TWT SP based on a specific portion of a first transmission opportunity (TXOP) within an r-TWT service period (SP) announced by the r-TWT schedule information being not used to transmit a DL frame corresponding to at least one r-TWT downlink (DL) traffic identifier (TID) or to request a UL frame corresponding to at least one r-TWT uplink (UL) TID.

[0008] A method for communicating by a second STA in a wireless LAN system according to one embodiment of the present disclosure includes: performing a restricted target wake time (r-TWT) membership setup procedure with a first STA; and transmitting r-TWT schedule information included in a broadcast TWT element to the first STA. The first TXOP may terminate before a start time of the r-TWT SP based on a specific portion of a first transmission opportunity (TXOP) within an r-TWT service period (SP) announced by the r-TWT schedule information being not used to transmit a DL frame corresponding to at least one r-TWT downlink (DL) traffic identifier (TID) or to request a UL frame corresponding to at least one r-TWT uplink (UL) TID. [Effects of the Invention]

[0009] According to the present disclosure, a method and apparatus can be provided for transmitting latency sensitive data / traffic in a wireless LAN system.

[0010] According to the present disclosure, a method and apparatus for implementing conditional r-TWT service period (SP) TXOP rules in a wireless LAN system can be provided.

[0011] According to the present disclosure, the TXOP rules of r-TWT SP can improve the efficiency of delay-sensitive data / traffic transmission in a manner that does not disrupt existing data transmission / reception flows, in addition to providing the desired predictable low-latency service.

[0012] The effects obtained from the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those having ordinary skill in the art to which the present disclosure pertains from the following description. [Brief explanation of the drawings]

[0013] 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.

[0014] [Figure 1] 1 is a block diagram illustrating a wireless communication device according to an embodiment of the present disclosure.

[0015] [Figure 2] FIG. 1 is a diagram illustrating an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0016] [Figure 3] FIG. 1 is a diagram illustrating a link setup process to which the present disclosure can be applied.

[0017] [Figure 4] FIG. 10 is a diagram illustrating a backoff process to which the present disclosure can be applied.

[0018] [Figure 5] 10A and 10B are diagrams for explaining a CSMA / CA base frame transmission operation to which the present disclosure can be applied.

[0019] [Figure 6] 1 is a diagram illustrating an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0020] [Figure 7] FIG. 1 illustrates an example of a PPDU defined in the IEEE 802.11 standard to which the present disclosure is applicable.

[0021] [Figure 8-10] FIG. 1 is a diagram illustrating an example of a resource unit of a wireless LAN system to which the present disclosure can be applied.

[0022] [Figure 11] FIG. 1 illustrates an exemplary structure of an HE-SIG-B field.

[0023] [Figure 12] FIG. 1 is a diagram illustrating a MU-MIMO scheme in which multiple users / STAs are assigned to one RU.

[0024] [Figure 13] FIG. 10 is a diagram illustrating an example of a PPDU format to which the present disclosure can be applied.

[0025] [Figure 14] 10A and 10B are diagrams for explaining an example of individual TWT operation to which the present disclosure can be applied.

[0026] [Figure 15] FIG. 10 is a diagram illustrating an example of a broadcast TWT operation to which the present disclosure can be applied.

[0027] [Figure 16] FIG. 10 is a diagram illustrating an example of a TWT information element format.

[0028] [Figure 17] FIG. 10 is a diagram illustrating an example of an individual TWT parameter set field format.

[0029] [Figure 18] FIG. 10 is a diagram illustrating an example of a broadcast TWT parameter set field format.

[0030] [Figure 19] FIG. 10 is a diagram illustrating limited TWT operation of a STA according to an example of the present disclosure.

[0031] [Figure 20] 10A and 10B are diagrams for explaining limited TWT operation of a first STA according to an example of the present disclosure.

[0032] [Figure 21] FIG. 10 is a diagram illustrating limited TWT operation of a second STA according to an example of the present disclosure.

[0033] [Figure 22-25] FIG. 10 illustrates a process in which a conditional TXOP rule of an r-TWT SP is applied according to an example of the present disclosure.

[0034] [Figure 26-28] 10 is a diagram illustrating a process in which an AP notifies other STAs of information related to r-TWT according to an example of the present disclosure. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0035] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The detailed description disclosed below together with the accompanying drawings is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure can be implemented. The detailed description below includes specific details to provide a complete understanding of the present disclosure. However, it will be understood by those skilled in the art that the present disclosure can be implemented without such specific details.

[0036] In some cases, in order to avoid obscuring the concepts of the present disclosure, known structures and devices may be omitted or shown in block diagram form, focusing on the core functions of each structure and device.

[0037] In this disclosure, when a component is "coupled," "coupled," or "connected" to another component, this may include a direct connection as well as an indirect connection where there is another component between them. Also, in this disclosure, the terms "comprise" or "have" specify the presence of stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0038] In this disclosure, terms such as "first" and "second" are used only to distinguish one component from another, and are not used to limit the components, and do not limit the order or importance of the components unless otherwise specified. Therefore, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0039] The terms used in this disclosure are for the purpose of describing particular embodiments and are not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular is intended to include the plural unless the context clearly dictates otherwise. The term "and / or" as used in this disclosure means that one of the associated listed items may be included, or that any and all possible combinations of two or more of them are included. Also, in this disclosure, " / " between words has the same meaning as "and / or" unless otherwise specified.

[0040] The examples of the present disclosure may be applied to various wireless communication systems. For example, the examples of the present disclosure may be applied to a wireless LAN system. For example, the examples of the present disclosure may be applied to an IEEE 802.11a / g / n / ac / ax standard-based wireless LAN. Note that the examples of the present disclosure may be applied to a newly proposed IEEE 802.11be (or EHT) standard-based wireless LAN. The examples of the present disclosure may be applied to an IEEE 802.11be Release-2 standard-based wireless LAN, which corresponds to a further improvement technology of the IEEE 802.11be Release-1 standard. Furthermore, the examples of the present disclosure may be applied to a next-generation standard-based wireless LAN after IEEE 802.11be. The examples of the present disclosure may also be applied to a cellular wireless communication system. For example, the examples of the present disclosure may be applied to a cellular wireless communication system based on the Long Term Evolution (LTE) series technology and the 5G New Radio (NR) series technology of the 3GPP (registered trademark) standard.

[0041] Below, technical features to which the examples of the present disclosure can be applied will be described.

[0042] FIG. 1 is a block diagram illustrating a wireless communication device according to an embodiment of the present disclosure.

[0043] 1 may be referred to by various terms such as a terminal, a wireless device, a wireless transmit receive unit (WTRU), a user equipment (UE), a mobile station (MS), a user terminal (UT), a mobile subscriber station (MSS), a mobile subscriber unit (MSS), a subscriber station (SS), an advanced mobile station (AMS), a wireless terminal (WT), or simply a user. In addition, the first device 100 and the second device 200 may be referred to by various terms such as an access point (AP), a base station (BS), a fixed station, a Node B, a base transceiver system (BTS), a network, an artificial intelligence (AI) system, a road side unit (RSU), a repeater, a router, a relay, a gateway, etc.

[0044] The devices 100 and 200 illustrated in FIG. 1 may also be referred to as stations (STAs). For example, the devices 100 and 200 illustrated in FIG. 1 may be referred to by various terms, such as a transmitting device, a receiving device, a transmitting STA, or a receiving STA. For example, the STAs 110 and 200 may serve as an access point (AP) or a non-AP. That is, in the present disclosure, the STAs 110 and 200 may have AP and / or non-AP functionality. When the STAs 110 and 200 have AP functionality, they may simply be referred to as APs, and when the STAs 110 and 200 have non-AP functionality, they may simply be referred to as STAs. Also, in the present disclosure, an AP may be referred to as an AP STA.

[0045] 1, a first device 100 and a second device 200 may transmit and receive wireless signals using various wireless LAN technologies (e.g., the IEEE 802.11 family). The first device 100 and the second device 200 may include interfaces for a medium access control (MAC) layer and a physical layer (PHY) in accordance with the IEEE 802.11 standard.

[0046] In addition, the first device 100 and the second device 200 may further support various communication standards (e.g., 3GPP LTE series, 5G NR series standards, etc.) other than WLAN technology. Furthermore, the devices of the present disclosure may be embodied as various devices such as mobile phones, vehicles, personal computers, augmented reality (AR) equipment, and virtual reality (VR) equipment. Furthermore, the STAs of the present disclosure may support various communication services such as voice calls, video calls, data communications, autonomous driving, machine-type communication (MTC), machine-to-machine (M2M), device-to-device (D2D), and Internet-of-Things (IoT).

[0047] The first device 100 includes one or more processors 102 and one or more memories 104, and may additionally include one or more transceivers 106 and / or one or more antennas 108. The processor 102 may be configured to control the memory 104 and / or the transceiver 106 to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts of the present disclosure. For example, the processor 102 may process information in the memory 104 to generate first information / signals, and then transmit a wireless signal including the first information / signals via the transceiver 106. The processor 102 may also receive a wireless signal including second information / signals via the transceiver 106, and then store information obtained from signal processing of the second information / signals in the memory 104. The memory 104 may be coupled to the processor 102 and may store various information related to the operation of the processor 102. For example, the memory 104 may store software code including instructions for executing some or all of the processes controlled by the processor 102 or for implementing the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts in this disclosure. Here, the processor 102 and the memory 104 may be part of a communications modem / circuit / chip designed to implement wireless LAN technology (e.g., the IEEE 802.11 series). The transceiver 106 may be coupled to the processor 102 and may transmit and / or receive wireless signals via one or more antennas 108. The transceiver 106 may include a transmitter and / or a receiver. The transceiver 106 may be used interchangeably with an RF (Radio Frequency) unit. In this disclosure, a device may also refer to a communications modem / circuit / chip.

[0048] The second device 200 includes one or more processors 202, one or more memories 204, and may additionally include one or more transceivers 206 and / or one or more antennas 208. The processor 202 may be configured to control the memory 204 and / or the transceiver 206 to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure. For example, the processor 202 may process information in the memory 204 to generate third information / signal, and then transmit a wireless signal including the third information / signal via the transceiver 206. The processor 202 may also receive a wireless signal including fourth information / signal via the transceiver 206, and then store information obtained from signal processing of the fourth information / signal in the memory 204. The memory 204 may be coupled to the processor 202 and may store various information related to the operation of the processor 202. For example, the memory 204 may store software code including instructions for executing some or all of the processes controlled by the processor 202 or for implementing the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure. Here, the processor 202 and the memory 204 may be part of a communications modem / circuit / chip designed to implement wireless LAN technology (e.g., the IEEE 802.11 series). The transceiver 206 may be coupled to the processor 202 and may transmit and / or receive wireless signals via one or more antennas 208. The transceiver 206 may include a transmitter and / or a receiver. The transceiver 206 may be used interchangeably with an RF unit. In this disclosure, a device may also refer to a communications modem / circuit / chip.

[0049] The hardware elements of the devices 100 and 200 are described in more detail below. Without limitation, one or more protocol layers may be implemented by one or more processors 102 and 202. For example, one or more processors 102 and 202 may implement one or more layers (e.g., the same functional layer, such as PHY or MAC). The one or more processors 102 and 202 may generate one or more protocol data units (PDUs) and / or one or more service data units (SDUs) according to the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams in this disclosure. The one or more processors 102 and 202 may generate messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams in this disclosure. The one or more processors 102, 202 can generate and provide signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the functions, procedures, suggestions, and / or methods of this disclosure to the one or more transceivers 106, 206. The one or more processors 102, 202 can receive signals (e.g., baseband signals) from the one or more transceivers 106, 206 and obtain the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts of this disclosure.

[0050] The one or more processors 102, 202 may be referred to as a controller, microcontroller, microprocessor, or microcomputer. The one or more processors 102, 202 may be implemented using hardware, firmware, software, or a combination thereof. As an example, the one or more processors 102, 202 may include one or more application-specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs). The descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to execute the descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in this disclosure may be included in one or more processors 102, 202 or stored in one or more memories 104, 204 and executed by one or more processors 102, 202. The descriptions, functions, procedures, suggestions, methods, and / or operational flow diagrams disclosed in this disclosure may be embodied by firmware or software in the form of code, instructions, and / or collections of instructions.

[0051] One or more memories 104, 204 may be coupled to one or more processors 102, 202 and may store various types of data, signals, messages, information, programs, code, instructions, and / or instructions. The one or more memories 104, 204 may be comprised of ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories 104, 204 may be located internal and / or external to the one or more processors 102, 202. Additionally, the one or more memories 104, 204 may be coupled to the one or more processors 102, 202 via various techniques, such as wired or wireless connections.

[0052] One or more transceivers 106, 206 may transmit user data, control information, wireless signals / channels, etc., as referred to in the methods and / or operational flowcharts of the present disclosure, to one or more other devices. One or more transceivers 106, 206 may receive user data, control information, wireless signals / channels, etc., as referred to in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts of the present disclosure, from one or more other devices. For example, one or more transceivers 106, 206 may be coupled to one or more processors 102, 202 and may transmit and receive wireless signals. For example, one or more processors 102, 202 may control one or more transceivers 106, 206 to transmit user data, control information, or wireless signals to one or more other devices. Also, one or more processors 102, 202 may control one or more transceivers 106, 206 to receive user data, control information, or wireless signals from one or more other devices. Furthermore, one or more transceivers 106, 206 may be coupled to one or more antennas 108, 208, and the one or more transceivers 106, 206 may be configured to transmit and receive user data, control information, wireless signals / channels, etc., referred to in the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure, via the one or more antennas 108, 208. In this disclosure, the one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). The one or more transceivers 106, 206 may convert the received user data, control information, wireless signals / channels, etc., from RF band signals to baseband signals for processing using one or more processors 102, 202. The one or more transceivers 106, 206 may convert the user data, control information, wireless signals / channels, etc., processed using one or more processors 102, 202, from baseband signals to RF band signals. To that end, one or more of the transceivers 106, 206 may include (analog) oscillators and / or filters.

[0053] For example, one of the STAs 100 and 200 may perform operations intended for an AP, and the other of the STAs 100 and 200 may perform operations intended for a non-AP STA. For example, the transceivers 106 and 206 in FIG. 1 may perform operations for transmitting and receiving signals (e.g., packets or PPDUs (Physical Layer Protocol Data Units) conforming to IEEE 802.11a / b / g / n / ac / ax / be, etc.). In addition, in the present disclosure, operations for various STAs to generate transmission / reception signals or to perform data processing or calculations in advance for transmission / reception signals may be performed by the processors 102 and 202 in FIG. 1. For example, examples of operations for generating transmission / reception signals or performing data processing or calculations in advance for transmission / reception signals may include: 1) operations for determining / obtaining / configuring / calculating / decoding / encoding bit information of fields included in a PPDU (SIG (signal), STF (short training field), LTF (long training field), Data, etc.); 2) operations for determining / configuring / obtaining time resources and frequency resources (e.g., subcarrier resources) to be used for fields included in a PPDU (SIG, STF, LTF, Data, etc.); 3) operations for determining / configuring / obtaining specific sequences (e.g., pilot sequences, STF / LTF sequences, extra sequences applied to SIG) to be used for fields included in a PPDU (SIG, STF, LTF, Data, etc.); 4) power control operations and / or power saving operations applied to STAs; and 5) operations related to determining / obtaining / configuring / calculating / decoding / encoding ACK signals, etc. In addition, in the example below, various information (e.g., information regarding fields / subfields / control fields / parameters / power, etc.) used by various STAs to determine / acquire / configure / calculate / decode / encode transmitted / receive signals may be stored in memories 104, 204 of FIG. 1.

[0054] Hereinafter, downlink (DL) refers to a link for communication from an AP STA to a non-AP STA, and downlink PPDUs / packets / signals, etc. may be transmitted and received via the downlink. In downlink communication, the transmitter may be part of the AP STA, and the receiver may be part of the non-AP STA. Uplink (UL) refers to a link for communication from a non-AP STA to an AP STA, and uplink PPDUs / packets / signals, etc. may be transmitted and received via the uplink. In uplink communication, the transmitter may be part of the non-AP STA, and the receiver may be part of the AP STA.

[0055] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0056] The structure of a WLAN system may be composed of multiple components. The interaction of these components may provide a WLAN that supports STA mobility transparent to higher layers. A Basic Service Set (BSS) is a basic building block of a WLAN. FIG. 2 illustrates two BSSs (BSS1 and BSS2), each including two STAs as members (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2). The ellipses representing BSSs in FIG. 2 may be understood to represent coverage areas where STAs included in the BSSs maintain communication. This area may be referred to as a Basic Service Area (BSA). If a STA moves outside a BSA, it will no longer be able to directly communicate with other STAs within the BSA.

[0057] Ignoring the DS shown in FIG. 2, the most basic type of BSS in a WLAN is the Independent BSS (IBSS). For example, an IBSS may have a minimal configuration consisting of only two STAs. For example, assuming that other components are omitted, BSS1 consisting of only STA1 and STA2, or BSS2 consisting of only STA3 and STA4, are representative examples of an IBSS. Such a configuration is possible when STAs can communicate directly without an AP. Furthermore, in such a WLAN, a BSS may be configured when needed by the LAN, rather than being configured in advance. This can also be called an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity. That is, in an IBSS, STAs are managed in a distributed manner. In an IBSS, all STAs may be mobile, and connection to a distributed system (DS) is not permitted, forming a self-contained network.

[0058] The membership of STAs in a BSS may change dynamically as STAs join and leave the BSS area, etc. To become a member of a BSS, a STA may join the BSS using a synchronization process. To access all the services of the BSS-based architecture, a STA must be associated with the BSS. Such association may be dynamically configured and may include the use of a Distribution System Service (DSS).

[0059] In a wireless LAN, direct STA-to-STA distance may be limited by PHY performance. While such distance limits are sufficient in some cases, other situations may require communication between STAs over longer distances. A distributed system (DS) may be configured to support extended coverage.

[0060] A DS refers to a structure in which BSSs are interconnected. Specifically, as shown in FIG. 2, a BSS may exist as a component of an expanded network composed of multiple BSSs. A DS is a logical concept and may be specified by the characteristics of a distributed system medium (DSM). In this regard, a wireless medium (WM) and a DSM may be logically distinguished. Each logical medium is used for different purposes and by different components. These media are neither limited to being the same nor limited to being different. The flexibility of a WLAN structure (DS structure or other network structure) can be explained by the fact that multiple media are logically distinct from one another. That is, a WLAN structure may be embodied in various ways, and the WLAN structure may be independently specified according to the physical characteristics of each implementation.

[0061] The DS can support mobile devices by providing seamless integration of multiple BSSs and logical services necessary for addressing destinations. The DS may also include a portal component that acts as a bridge between the wireless LAN and other networks (e.g., IEEE 802.X).

[0062] An AP is an entity that allows associated non-AP STAs to access the DS through the WM and also has the functionality of an STA. Data can be transferred between a BSS and a DS via the AP. For example, STA2 and STA3 shown in FIG. 2 have the functionality of an STA and provide the function of allowing associated non-AP STAs (STA1 and STA4) to access the DS. Furthermore, since all APs essentially correspond to STAs, all APs are addressable entities. The address used by an AP for communication on the WM does not necessarily have to be the same as the address used by the AP for communication on the DSM. A BSS consisting of an AP and one or more STAs can be called an infrastructure BSS.

[0063] Data transmitted from one of the STAs associated with an AP to the STA address of that AP is always received on the uncontrolled port and may be processed by the IEEE 802.1X port access entity, and once the controlled port is authenticated, the transmitted data (or frame) may be delivered to the DS.

[0064] In the above-described DS structure, an Extended Service Set (ESS) may be configured to provide wider coverage.

[0065] An ESS is a network of arbitrary size and complexity composed of a DS and a BSS. An ESS can be a collection of BSSs connected to one DS. However, an ESS does not include a DS. An ESS network is characterized by appearing as an IBSS at the Logical Link Control (LLC) layer. STAs included in an ESS can communicate with each other, and mobile STAs can move from one BSS to another (within the same ESS) transparently to the LLC. APs included in one ESS may have the same service set identification (SSID). An SSID is distinct from a BSSID, which is an identifier for a BSS.

[0066] A WLAN system does not make any assumptions about the relative physical locations of BSSs and can have any of the following configurations: BSSs may partially overlap, which is a configuration commonly used to provide continuous coverage; BSSs may not be physically connected, and there is no logical limit to the distance between BSSs; BSSs may be physically located in the same location, which may be used to provide redundancy; and one (or more) IBSS or ESS networks may physically exist in the same space as one (or more) ESS networks. This may apply to ESS network configurations when an ad-hoc network operates in the location where the ESS network exists, when physically overlapping wireless networks are formed by different organizations, or when two or more different access and security policies are required in the same location.

[0067] FIG. 3 is a diagram illustrating a link setup process to which the present disclosure can be applied.

[0068] In order for an STA to set up a link to a network and transmit and receive data, it must first discover the network, perform authentication, establish an association, and perform authentication procedures for security. The link setup process can also be called a session initiation process or a session setup process. In addition, the discovery, authentication, association, and security configuration processes of the link setup process can also be collectively called the association process.

[0069] In step S310, the STA may perform a network discovery operation. The network discovery operation may include a scanning operation of the STA. That is, in order for the STA to access a network, the STA must search for a joinable network. Before joining a wireless network, the STA must identify a compatible network. The process of identifying networks present in a specific area is called scanning.

[0070] Scanning methods include active scanning and passive scanning. FIG. 3 illustrates an example of a network discovery operation including an active scanning process. In active scanning, a scanning STA changes channels and transmits a probe request frame to search for nearby APs, and waits for a response. A responder transmits a probe response frame to the STA that transmitted the probe request frame in response to the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame in the BSS of the channel being scanned. In a BSS, the AP transmits beacon frames, so the AP is the responder. In an IBSS, the STAs in the IBSS transmit beacon frames alternately, so the responder is not constant. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store the BSS-related information contained in the received probe response frame, move to the next channel (e.g., channel 2), and perform scanning in the same manner (i.e., send and receive probe requests / responses on channel 2).

[0071] Although not shown in FIG. 3, the scanning operation may be performed in a passive scanning manner. In passive scanning, a scanning STA waits for a beacon frame while changing channels. A beacon frame is a management frame defined in IEEE 802.11 and is periodically transmitted to announce the existence of a wireless network and allow a scanning STA to search for and join the wireless network. In a BSS, an AP is responsible for periodically transmitting beacon frames, while in an IBSS, STAs within the IBSS transmit beacon frames in turn. When a scanning STA receives a beacon frame, it saves information about the BSS included in the beacon frame and records the beacon frame information on each channel as it moves to other channels. A STA that receives a beacon frame saves the BSS-related information included in the received beacon frame, moves to the next channel, and scans the next channel in the same manner. Comparing active scanning with passive scanning, active scanning has the advantage of having a smaller delay and power consumption than passive scanning.

[0072] After the STA discovers the network, an authentication process may be performed in step S320. This authentication process may be called a first authentication process to clearly distinguish it from the security setup operation in step S340, which will be described later.

[0073] The authentication process involves a STA sending an authentication request frame to an AP, and the AP responding by sending an authentication response frame to the STA. The authentication frame used for the authentication request / response corresponds to a management frame.

[0074] The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), a Finite Cyclic Group, etc. These are only examples of information that may be included in an authentication request / response frame, and other information may be substituted or additional information may be included.

[0075] The STA can send an authentication request frame to the AP. The AP can determine whether to allow authentication for the STA based on the information contained in the received authentication request frame. The AP can provide the STA with the result of the authentication process using an authentication response frame.

[0076] After the STA is successfully authenticated, an association process may be performed in step S330. The association process includes the STA sending an association request frame to the AP, and the AP responding by sending an association response frame to the STA.

[0077] 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 only 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.

[0078] After the STA is successfully connected to the network, a security setup process may be performed in step S340. The security setup process in step S340 may also be referred to as an authentication process using a Robust Security Network Association (RSNA) request / response, and the authentication process in step S320 may be referred to as a first authentication process, and the security setup process in step S340 may simply be referred to as an authentication process.

[0079] The security setup process of step S340 may include a process of performing private key setup using, for example, four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame, and may also be performed using a security method not defined in the IEEE 802.11 standard.

[0080] FIG. 4 is a diagram illustrating a backoff process to which the present disclosure can be applied.

[0081] In wireless LAN systems, the basic access mechanism of MAC (Medium Access Control) is the Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) mechanism, also known as the Distributed Coordination Function (DCF) of IEEE 802.11 MAC, which basically employs a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or STA can perform a Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time period (e.g., a DCF Inter-Frame Space (DIFS)) before starting transmission. If the sensing result indicates that the medium is in an idle status, the AP and / or STA can start transmitting a frame over the medium. On the other hand, if the medium is detected as occupied or busy, the AP and / or STA can wait for a delay period (e.g., a random backoff period) for medium access without starting its own transmission, and then attempt to transmit a frame. By applying the random backoff period, multiple STAs are expected to wait for different periods of time before attempting to transmit a frame, thereby minimizing collisions.

[0082] The IEEE 802.11 MAC protocol also provides a Hybrid Coordination Function (HCF). HCF is based on the DCF and Point Coordination Function (PCF). PCF is a polling-based synchronous access method that periodically polls all receiving APs and / or STAs to receive data frames. HCF also includes Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA). EDCA is a contention-based access method for a provider to provide data frames to multiple users, while HCCA is a non-contention-based channel access method using a polling mechanism. HCF also includes a medium access mechanism for improving the quality of service (QoS) of wireless LANs, and can transmit QoS data in both a contention period (CP) and a contention-free period (CFP).

[0083] The operation based on the random backoff period will be described with reference to FIG. 4. When an occupied / busy medium changes to an idle state, multiple STAs can attempt to transmit data (or frames). As a method for minimizing collisions, each STA can select a random backoff count and attempt transmission after waiting for the corresponding slot time. The random backoff count has a pseudo-random integer value and may be determined to be one of the values ​​in the range of 0 to CW. Here, CW is the contention window parameter value. The CW parameter is given a CWmin as its initial value, but can be doubled in the event of a transmission failure (e.g., if an ACK for a transmitted frame is not received). When the CW parameter value reaches CWmax, data transmission can be attempted while maintaining the CWmax value until data transmission is successful, and if data transmission is successful, it is reset to the CWmin value. The CW, CWmin, and CWmax values ​​are set to 2. n Preferably it is set to -1 (n=0,1,2,...).

[0084] When the random backoff process begins, the STA continuously monitors the medium while counting down the backoff slots according to the determined backoff count value. If the medium is monitored as occupied, the STA stops counting down and waits. If the medium becomes idle, the STA resumes the remaining countdown.

[0085] In the example of FIG. 4, when a packet to be transmitted arrives at the MAC of STA3, STA3 confirms that the medium is idle for DIFS and can immediately transmit a frame. The remaining STAs monitor the medium for occupied / busy status and wait. Meanwhile, STA1, STA2, and STA5 may each have data to transmit. If each STA monitors the medium as idle, it waits for DIFS and then counts down its backoff slots according to its random backoff count value. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. That is, this example illustrates a case where, at the time STA2 finishes its backoff count and begins frame transmission, STA5's remaining backoff time is shorter than STA1's remaining backoff time. STA1 and STA5 pause their countdowns and wait while STA2 occupies the medium. When STA2's occupation ends and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume their backoff counts. That is, STA5 can start frame transmission after counting down the remaining backoff slots equal to the remaining backoff time. Because STA5's remaining backoff time is shorter than STA1's, STA5 begins frame transmission. While STA2 is occupying the medium, STA4 may also have data to transmit. From STA4's perspective, when the medium becomes idle, it waits for DIFS, then counts down the random backoff count value it selected, and can begin frame transmission. The example in FIG. 4 shows a case where STA5's remaining backoff time happens to match STA4's random backoff count value, which may result in a collision between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 will receive an ACK, resulting in a failed data transmission. In this case, STA4 and STA5 can double their CW values, select a random backoff count value, and then count down.STA1 waits while the medium is occupied by transmissions from STA4 and STA5, but when the medium becomes idle, it waits for DIFS and can begin frame transmission once the remaining backoff time has elapsed.

[0086] As shown in the example of Figure 4, a data frame is a frame used for transmitting data to be forwarded to a higher layer, and may be transmitted after a backoff that occurs after a DIFS has elapsed since the medium became idle. Furthermore, a management frame is a frame used for exchanging management information that is not forwarded to a higher layer, and is transmitted after a backoff that occurs after an IFS, such as a DIFS or a PIFS (Point Coordination Function IFS). Subtype frames of management frames include a beacon, an association request / response, a re-association request / response, a probe request / response, and an authentication request / response. A control frame is a frame used to control access to a medium. Subtype frames of control frames include Request-To-Send (RTS), Clear-To-Send (CTS), Acknowledgment (ACK), Power Save-Poll (PS-Poll), BlockAck, BlockACKReq, NDP announcement (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. If a control frame is a response frame of a previous frame, it is transmitted without a backoff after a short IFS (SIFS) has elapsed. The type and subtype of a frame may be identified by the type field and subtype field in the Frame Control (FC) field.

[0087] A Quality of Service (QoS) STA can transmit a frame after backing off after the arbitration IFS (AIFS) for the access category (AC) to which the frame belongs, i.e., AIFS[i] (where i is a value determined by the AC), has elapsed. Here, a frame that can use AIFS[i] can be a data frame, a management frame, or a control frame that is not a response frame.

[0088] FIG. 5 is a diagram for explaining a CSMA / CA base frame transmission operation to which the present disclosure can be applied.

[0089] As mentioned above, the CSMA / CA mechanism includes not only physical carrier sensing, in which a STA directly senses the medium, but also virtual carrier sensing. Virtual carrier sensing is intended to compensate for problems that may occur in medium access, such as the hidden node problem. For virtual carrier sensing, the MAC of a STA can use a network allocation vector (NAV). The NAV is a value that indicates to other STAs the time remaining until the medium becomes available for use by a STA currently using or authorized to use the medium. Therefore, the value set as the NAV corresponds to the period during which the STA transmitting the frame plans to use the medium, and STAs receiving the NAV value are prohibited from accessing the medium during that period. For example, the NAV may be set based on the value of the "duration" field in the MAC header of the frame.

[0090] In the example of FIG. 5, it is assumed that STA1 is attempting to transmit data to STA2, and STA3 is in a position where it can overhear some or all of the frames transmitted between STA1 and STA2.

[0091] In order to reduce the possibility of collisions between transmissions from multiple STAs in a CSMA / CA-based frame transmission operation, a mechanism using RTS / CTS frames may be applied. In the example of FIG. 5, while STA1 is transmitting, STA3 may determine that the medium is idle as a result of carrier sensing. That is, STA1 may be a hidden node to STA3. Alternatively, in the example of FIG. 5, while STA2 is transmitting, STA3 may determine that the medium is idle as a result of carrier sensing. That is, STA2 may be a hidden node to STA3. By exchanging RTS / CTS frames before data transmission and reception between STA1 and STA2, STAs outside the transmission range of either STA1 or STA2, or outside the carrier sensing range for transmissions from STA1 or STA3, can be prevented from attempting to occupy the channel during data transmission and reception between STA1 and STA2.

[0092] Specifically, STA1 can determine whether a channel is occupied or not using carrier sensing. In terms of physical carrier sensing, STA1 can determine whether a channel is occupied or idle based on the energy magnitude or signal correlation detected from the channel. In terms of virtual carrier sensing, STA1 can determine whether a channel is occupied or idle using a network allocation vector (NAV) timer.

[0093] When the channel is idle in DIFS, STA1 can send an RTS frame to STA2 after backing off. When STA2 receives the RTS frame, it can send a CTS frame to STA1 as a response to the RTS frame after SIFS.

[0094] If STA3 cannot overhear the CTS frame from STA2 but can overhear the RTS frame from STA1, STA3 can use the duration information included in the RTS frame to set a NAV timer for the frame transmission period (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame) that will be transmitted subsequently. Alternatively, if STA3 cannot overhear the RTS frame from STA1 but can overhear the CTS frame from STA2, STA3 can use the duration information included in the CTS frame to set a NAV timer for the frame transmission period (e.g., SIFS + data frame + SIFS + ACK frame) that will be transmitted subsequently. That is, if STA3 can overhear one or more RTS or CTS frames from at least one of STA1 and STA2, it can set a NAV based thereon. If STA3 receives a new frame before the NAV timer expires, it can update the NAV timer using the duration information included in the new frame. STA3 does not attempt channel access until the NAV timer expires.

[0095] When STA1 receives a CTS frame from STA2, it can transmit a data frame to STA2 SIFS after the completion of reception of the CTS frame. When STA2 successfully receives a data frame, it can transmit an ACK frame, which is a response to the data frame, to STA1 SIFS after the completion of reception of the CTS frame. When STA3's NAV timer expires, it can use carrier sensing to determine whether the channel is in use. If STA3 determines that the channel is not in use by another terminal within DIFS after the expiration of the NAV timer, it can attempt channel access after the contention window (CW) with random backoff has elapsed.

[0096] FIG. 6 is a diagram illustrating an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0097] The PHY layer can prepare an MPDU (MAC PDU) to be transmitted based on an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer. For example, when the PHY layer receives a command from the MAC layer requesting the start of PHY layer transmission, the PHY layer switches to transmission mode and transmits information (e.g., data) provided by the MAC layer in the form of a frame. In addition, when the PHY layer detects a valid preamble in a received frame, it monitors the preamble header and sends a command to the MAC layer informing the start of PHY layer reception.

[0098] Thus, information transmission / reception in a wireless LAN system is performed in the form of frames, and for this purpose, a PHY layer protocol data unit (PPDU) frame format is defined.

[0099] A basic PPDU frame may include a Short Training Field (STF), a Long Training Field (LTF), a Signal (SIG) field, and a Data field. The most basic (e.g., non-High Throughput (HT)) PPDU frame format may consist of only a Legacy-STF (L-STF), a Legacy-LTF (L-LTF), a SIG field, and a Data field. Depending on the type of PPDU frame format (e.g., HT-mixed format PPDU, HT-greenfield format PPDU, Very High Throughput (VHT) PPDU, etc.), additional (or other types of) STF, LTF, and SIG fields may be included between the SIG field and the Data field (this will be described later with reference to FIG. 7).

[0100] 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.

[0101] The SIG field may include a RATE field, a LENGTH field, etc. The RATE field may include information about the modulation and coding rate of the data. The LENGTH field may include information about the length of the data. Furthermore, the SIG field may include a parity bit, a SIG TAIL bit, etc.

[0102] The data field may include a SERVICE field, a PSDU (Physical layer Service Data Unit), a PPDU TAIL bit, and, if necessary, padding bits. Some bits of the SERVICE field may be used for synchronization of a descrambler at the receiving end. The PSDU corresponds to a MAC PDU defined in the MAC layer and may contain data generated / used by a higher layer. The PPDU TAIL bit may be used to return the encoder to a 0 state. The padding bits may be used to adjust the length of the data field to a predetermined unit.

[0103] The MAC PDU is defined by various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a Frame Check Sequence (FCS). The MAC frame is composed of the MAC PDU and may be transmitted / received by the PSDU in the data portion of the PPDU frame format.

[0104] The MAC header includes a Frame Control field, a Duration / ID field, an Address field, etc. The Frame Control field may include control information required for frame transmission / reception. The Duration / ID field may be set to the time for transmitting the frame, etc. For specific contents of the Sequence Control, QoS Control, and HT Control subfields of the MAC header, please refer to the IEEE 802.11 standard document.

[0105] 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.

[0106] FIG. 7 is a diagram illustrating an example of a PPDU defined in the IEEE 802.11 standard to which the present disclosure is applicable.

[0107] Various types of PPDUs are used in standards such as IEEE 802.11a / g / n / ac / ax. The basic PPDU format (IEEE 802.11a / g) includes an L-LTF, an L-STF, an L-SIG, and a Data field. The basic PPDU format can also be called a non-HT PPDU format.

[0108] The HT PPDU format (IEEE 802.11n) further includes HT-SIG, HT-STF, and HT-LFT(s) fields in addition to the basic PPDU format. The HT PPDU format shown in Fig. 7 may be referred to as an HT-mixed format. An HT-greenfield format PPDU may also be defined, which corresponds to a format that does not include L-STF, L-LTF, or L-SIG, but is composed of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTFs, and a Data field (not shown).

[0109] 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.

[0110] An example of the HE PPDU format (IEEE 802.11ax) further includes the fields Repeated L-SIG (RL-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and Packet Extension (PE) in addition to the basic PPDU format. Depending on the detailed example of the HE PPDU format, some fields may be excluded or their lengths may vary. For example, the HE-SIG-B field is included in the HE PPDU format for multiple users (MU), but not in the HE PPDU format for single users (SU). Also, the HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may be 8 us. The HE Extended Range (ER) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may be 16 us.

[0111] 8 to 10 are diagrams illustrating examples of resource units in a wireless LAN system to which the present disclosure can be applied.

[0112] 8 to 10, a resource unit (RU) defined in a wireless LAN system will be described. An RU may include multiple subcarriers (or tones). An RU may be used when transmitting signals to multiple STAs based on the OFDMA technique. An RU may also be defined when transmitting a signal to one STA. An RU may be used for the STF, LTF, data field, etc. of a PPDU.

[0113] 8 to 10, RUs corresponding to different numbers of tones (i.e., subcarriers) may be used to configure some fields of a 20 MHz, 40 MHz, or 80 MHz X-PPDU (X is HE, EHT, etc.). For example, resources may be allocated in units of RUs indicated for the X-STF, X-LTF, and Data fields.

[0114] FIG. 8 is a diagram illustrating an exemplary arrangement of resource units (RUs) used on a 20 MHz band.

[0115] As shown at the top of Figure 8, 26 units (i.e., units corresponding to 26 tones) may be allocated. Six tones may be used as a guard band in the leftmost band of the 20 MHz band, and five tones may be used as a guard band in the rightmost band of the 20 MHz band. Seven DC tones may be inserted into the center band, i.e., the DC band, leaving 26 units corresponding to 13 tones on each side of the DC band. Other bands may be allocated 26 units, 52 units, or 106 units. Each unit may be allocated for a STA or a user.

[0116] The RU arrangement in Figure 8 can be utilized not only in a multiple user (MU) situation but also in a single user (SU) situation, in which case one 242 unit can be used as shown at the bottom of Figure 8. In this case, three DC tones may be inserted.

[0117] In the example of Figure 8, RUs of various sizes, i.e., 26-RU, 52-RU, 106-RU, 242-RU, etc., are illustrated, but the specific sizes of such RUs may be reduced or expanded. Therefore, the specific size of each RU (i.e., the corresponding number of tones) is not limited in the present disclosure and is merely exemplary. Also, in the present disclosure, the number of RUs within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, ...) may vary depending on the size of the RU. The examples of Figures 9 and / or 10 described below are the same as the example of Figure 8 in that the size and / or number of RUs may be changed.

[0118] FIG. 9 is a diagram illustrating an exemplary arrangement of resource units (RUs) used on a 40 MHz band.

[0119] 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.

[0120] Also, as shown in the figure, when used for a single user, 484-RU may be used.

[0121] FIG. 10 is a diagram illustrating an exemplary arrangement of resource units (RUs) used on an 80 MHz band.

[0122] Just as various sizes of RUs are used in the examples of Figures 8 and 9, 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, 996-RU, etc. may be used in the example of Figure 10. Furthermore, in an 80 MHz PPDU, the RU arrangements of the HE PPDU and the EHT PPDU may differ from each other, and the example of Figure 10 shows an example of the RU arrangement for an 80 MHz EHT PPDU. In the example of Figure 10, the HE PPDU and the EHT PPDU are the same in that 12 tones are used as a guard band in the leftmost band of the 80 MHz band and 11 tones are used as a guard band in the rightmost band of the 80 MHz band. In the HE PPDU, seven DC tones are inserted into the DC band, and there are two 26-RUs on each side of the DC band, corresponding to 13 tones. In the EHT PPDU, 23 DC tones are inserted into the DC band, and there are two 26-RUs on each side of the DC band. In the HE PPDU, there is one null subcarrier between the 242-RUs outside the center band. In the EHT PPDU, there are five null subcarriers. In the HE PPDU, one 484-RU does not contain a null subcarrier, but in the EHT PPDU, one 484-RU contains five null subcarriers.

[0123] 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.

[0124] An EHT PPDU of 160 MHz or more may be configured with multiple 80 MHz sub-blocks in Figure 10. The RU allocation for each 80 MHz sub-block may be the same as the RU allocation for the 80 MHz EHT PPDU in Figure 10. When the 80 MHz sub-blocks of a 160 MHz or 320 MHz EHT PPDU are not punctured and the entire 80 MHz sub-block is used as part of an RU or MRU (Multiple RU), the 80 MHz sub-block can use 996 RUs in Figure 10.

[0125] Here, an MRU corresponds to a group of subcarriers (or tones) composed of multiple RUs, and the multiple RUs constituting an MRU may be RUs of the same size or different sizes. For example, a single MRU may be defined as 52+26-tones, 106+26-tones, 484+242-tones, 996+484-tones, 996+484+242-tones, 2×996+484-tones, 3×996-tones, or 3×996+484-tones. Here, the multiple RUs constituting one MRU may correspond to RUs of small size (e.g., 26, 52, 106) or RUs of large size (e.g., 242, 484, 996, etc.). That is, one MRU including RUs of small size and RUs of large size does not need to be configured / defined. Furthermore, the multiple RUs constituting one MRU may or may not be contiguous in the frequency domain.

[0126] If an 80 MHz sub-block contains RUs with fewer than 996 tones or if portions of the 80 MHz sub-block are punctured, the 80 MHz sub-block may use an RU placement that excludes 996-tone RUs.

[0127] The RUs of the present disclosure may be used for uplink (UL) and / or downlink (DL) communications. For example, when trigger-based UL-MU communications are performed, a STA (e.g., an AP) transmitting a trigger may use trigger information (e.g., a trigger frame or triggered response scheduling (TRS)) to assign a first RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a first STA and a second RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a second STA. The first STA may then transmit a first trigger-based (TB) PPDU based on the first RU, and the second STA may transmit a second TB PPDU based on the second RU. The first and second TB PPDUs may be transmitted to the AP in the same time interval.

[0128] For example, when a DL MU PPDU is configured, a STA (e.g., an AP) transmitting the DL MU PPDU can assign a first RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a first STA and a second RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a second STA. That is, the transmitting STA (e.g., an AP) can transmit the HE-STF, HE-LTF, and Data fields for the first STA using the first RU within one MU PPDU, and can transmit the HE-STF, HE-LTF, and Data fields for the second STA using the second RU.

[0129] Information about the location of the RU may be signaled in the HE-SIG-B in HE PPDU format.

[0130] FIG. 11 shows an example structure of the HE-SIG-B field.

[0131] As shown in the figure, the HE-SIG-B fields may include common fields and user-specific fields. When HE-SIG-B compression is applied (e.g., in the case of full-bandwidth MU-MIMO transmission), the common fields may not be included in the HE-SIG-B, and the HE-SIG-B content channel may include only user-specific fields. When HE-SIG-B compression is not applied, the common fields may be included in the HE-SIG-B.

[0132] 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.).

[0133] The common field may include N*8 RU allocation subfields, where N is the number of subfields, and may have a value of 1 for a 20 or 40 MHz MU PPDU, 2 for an 80 MHz MU PPDU, 4 for a 160 MHz or 80+80 MHz MU PPDU, .... One 8-bit RU allocation subfield may indicate the size (26, 52, 106, etc.) and frequency location (or RU index) of the RUs included in the 20 MHz band.

[0134] 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.

[0135] As a further example, if the value of the 8-bit RU allocation subfield is 01000y2y1y0, it may indicate that one 106-RU and five 26-RUs are arranged in order from the leftmost to the rightmost in the example of FIG. 8. In this case, multiple users / STAs may be allocated to the 106-RU using the MU-MIMO scheme. Specifically, up to eight users / STAs may be allocated to the 106-RU, and the number of users / STAs allocated to the 106-RU is determined based on the 3-bit information (i.e., y2y1y0). For example, if the 3-bit information (y2y1y0) corresponds to a decimal value N, the number of users / STAs allocated to the 106-RU may be N+1.

[0136] Basically, one user / STA may be assigned to each of multiple RUs, and different users / STAs may be assigned to different RUs. For RUs of a certain size or larger (e.g., 106, 242, 484, 996-tone, etc.), multiple users / STAs may be assigned to one RU, and the MU-MIMO scheme may be applied to the multiple users / STAs.

[0137] The set of user-specific fields contains information on how all users (STAs) of the PPDU decode their payloads. The user-specific fields may contain zero or more user block fields. A non-final user block field contains two user fields (i.e., information used for decoding at two STAs). A final user block field contains one or two user fields. The number of user fields may be indicated by the RU allocation subfield in HE-SIG-B, the number of symbols in HE-SIG-B, or the MU-MIMO user field in HE-SIG-A. The user-specific fields may be encoded separately or independently from the common fields.

[0138] FIG. 12 is a diagram illustrating the MU-MIMO scheme in which multiple users / STAs are assigned to one RU.

[0139] 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 can indicate that 3 (=N+1) users are allocated to one RU. In this case, one 106-RU and five 26-RUs may be arranged in order from the leftmost to the rightmost of a specific 20 MHz band / channel. Three users / STAs may be allocated to the 106-RU in a MU-MIMO manner. As a result, a total of eight users / STAs are allocated to the 20 MHz band / channel, and the user-specific field of the HE-SIG-B may include eight user fields (i.e., four user block fields). The eight user fields may be assigned to RUs as shown in FIG. 12.

[0140] The user fields may be configured based on two formats. The user fields for MU-MIMO allocation may be configured in a first format, and the user fields for non-MU-MIMO allocation may be configured in a second format. Referring to the example of FIG. 12, user fields 1 to 3 may be based on the first format, and user fields 4 to 8 may be based on the second format. The first format and the second format may contain bit information of the same length (e.g., 21 bits).

[0141] The user field of the first format (i.e., a format for MU-MIMO allocation) may be configured as follows: For example, among the total 21 bits of one user field, B0 to B10 include identification information of the user (e.g., STA-ID, AID, partial AID, etc.), B11 to B14 include spatial configuration information such as the number of spatial streams for the user, B15 to B18 include modulation and coding scheme (MCS) information applied to the data field of the PPDU, B19 is defined as a reserved field, and B20 may include coding type information (e.g., binary convolutional coding (BCC) or low-density parity check (LDPC)) applied to the data field of the PPDU.

[0142] The user field of the second format (i.e., a format for non-MU-MIMO allocation) may be configured as follows: For example, among the total 21 bits of one user field, B0 to B10 may include identification information of the user (e.g., STA-ID, AID, partial AID, etc.), B11 to B13 may include information on the number of spatial streams (NSTS) applied to the RU, B14 may include information indicating whether beamforming is enabled (or whether a beamforming steering matrix is ​​applied), B15 to B18 may include information on modulation and coding scheme (MCS) applied to the Data field of the PPDU, B19 may include information on whether dual carrier modulation (DCM) is enabled, and B20 may include information on a coding type (e.g., BCC or LDPC) applied to the Data field of the PPDU.

[0143] The MCS, MCS information, MCS index, MCS field, etc. used in the present disclosure may be represented as specific index values. For example, the MCS information may be represented as index 0 to index 11. The MCS information may include information about the constellation modulation type (e.g., BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM, 1024-QAM, etc.) and information about the coding rate (e.g., 1 / 2, 2 / 3, 3 / 4, 5 / 6, etc.). The MCS information may omit information about the channel coding type (e.g., BCC or LDPC).

[0144] FIG. 13 shows an example of a PPDU format to which the present disclosure can be applied.

[0145] 13 may be referred to by various names such as EHT PPDU, transmit PPDU, receive PPDU, first type or Nth type PPDU, etc. For example, the PPDU or EHT PPDU of the present disclosure may be referred to by various names such as transmit PPDU, receive PPDU, first type or Nth type PPDU, etc. Furthermore, the EHT PPDU can be used in an EHT system and / or a new WLAN system that is an improvement over the EHT system.

[0146] The EHT MU PPDU in Figure 13 corresponds to a PPDU that carries one or more data (or PSDUs) for one or more users. That is, the EHT MU PPDU may be used for both SU transmission and MU transmission. For example, the EHT MU PPDU may correspond to a PPDU for one receiving STA or multiple receiving STAs.

[0147] The EHT TB PPDU in Figure 13 omits the EHT-SIG compared to the EHT MU PPDU. A STA that receives a trigger for UL MU transmission (e.g., a trigger frame or TRS) can perform UL transmission based on the EHT TB PPDU format.

[0148] 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.

[0149] The subcarrier frequency spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields (these are referred to as pre-EHT modulated fields) may be defined as 312.5 kHz. The subcarrier frequency spacing of the EHT-STF, EHT-LTF, Data, and PE fields (these are referred to as EHT modulated fields) may be defined as 78.125 kHz. That is, the tone / subcarrier indexes of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields may be represented in units of 312.5 kHz, and the tone / subcarrier indexes of the EHT-STF, EHT-LTF, Data, and PE fields may be represented in units of 78.125 kHz.

[0150] The L-LTF and L-STF in FIG. 13 may be configured in the same manner as the corresponding fields of the PPDU described in FIGS.

[0151] The L-SIG field in FIG. 13 may be composed of 24 bits and may be used to communicate rate and length information. For example, the L-SIG field may include a 4-bit Rate field, a 1-bit Reserved bit, a 12-bit Length field, a 1-bit Parity field, and a 6-bit Tail field. For example, the 12-bit Length field may include information regarding the length or time duration of the PPDU. For example, the value of the 12-bit Length field may be determined based on the type of PPDU. For example, for a non-HT, HT, VHT, or EHT PPDU, the value of the Length field may be determined as a multiple of 3. For example, for an HE PPDU, the value of the Length field may be determined as a multiple of 3 + 1 or a multiple of 3 + 2.

[0152] For example, the transmitting STA may apply BCC encoding based on a coding rate of 1 / 2 to the 24-bit information in the L-SIG field. The transmitting STA may then obtain 48 BCC-coded bits. BPSK modulation may be applied to the 48 coded bits to generate 48 BPSK symbols. The transmitting STA may map the 48 BPSK symbols to positions excluding pilot subcarriers (e.g., subcarrier indexes −21, −7, +7, +21) and DC subcarriers (e.g., subcarrier index 0). Consequently, the 48 BPSK symbols may be mapped to subcarrier indexes −26 to −22, −20 to −8, −6 to −1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA may further map signals of {−1, −1, −1, 1} to subcarrier indexes {−28, −27, +27, +28}. The signal may be used for channel estimation for the frequency range corresponding to {-28, -27, +27, +28}.

[0153] The transmitting STA can generate an RL-SIG, which is generated identically to the L-SIG. BPSK modulation is applied to the RL-SIG. The receiving STA can determine whether the received PPDU is an HE PPDU or an EHT PPDU based on the presence of the RL-SIG.

[0154] A Universal SIG (U-SIG) may be inserted after the RL-SIG in Fig. 13. The U-SIG may be called various names such as a first SIG field, a first SIG, a first type SIG, a control signal, a control signal field, or a first (type) control signal.

[0155] The U-SIG may include N bits of information and may include information for identifying the type of EHT PPDU. For example, the U-SIG may be configured based on two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., OFDM symbol) for the U-SIG may have a duration of 4 us, and the entire U-SIG may have a duration of 8 us. Each symbol of the U-SIG may be used to transmit 26 bits of information. For example, each symbol of the U-SIG may be transmitted and received based on 52 data tones and 4 pilot tones.

[0156] In the U-SIG (or U-SIG field), for example, A-bit information (e.g., 52 uncoded bits) may be transmitted. The first symbol of the U-SIG (e.g., U-SIG-1) transmits the first X-bit information (e.g., 26 uncoded bits) of the total A-bit information, and the second symbol of the U-SIG (e.g., U-SIG-2) transmits the remaining Y-bit information (e.g., 26 uncoded bits) of the total A-bit information. For example, the transmitting STA may obtain the 26 uncoded bits included in each U-SIG symbol. The transmitting STA may perform convolutional encoding (e.g., BCC encoding) based on a rate of R=½ to generate 52-coded bits and perform interleaving on the 52-coded bits. The transmitting STA may perform BPSK modulation on the interleaved 52-coded bits to generate 52 BPSK symbols assigned to each U-SIG symbol. One U-SIG symbol may be transmitted based on 56 tones (subcarriers) from subcarrier index -28 to subcarrier index +28, excluding DC index 0. The 52 BPSK symbols generated by the transmitting STA may be transmitted based on the remaining tones (subcarriers) excluding the pilot tones -21, -7, +7, and +21.

[0157] For example, the A-bit information (e.g., 52 un-coded bits) transmitted by the U-SIG may include a CRC field (e.g., a 4-bit field) and a tail field (e.g., a 6-bit field). The CRC field and tail field may be transmitted in the second symbol of the U-SIG. The CRC field may be generated based on the 26 bits allocated to the first symbol of the U-SIG and the remaining 16 bits in the second symbol excluding the CRC / tail field, and may be generated based on a conventional CRC calculation algorithm. The tail field may also be used to terminate the trellis of a convolutional decoder and may be set to 0, for example.

[0158] The A-bit information (e.g., 52 uncoded bits) transmitted by the U-SIG (or U-SIG field) can be divided into version-independent bits and version-dependent bits. For example, the size of the version-independent bits may be fixed or variable. For example, the version-independent bits may be assigned only to the first symbol of the U-SIG, or the version-independent bits may be assigned to both the first and second symbols of the U-SIG. For example, the version-independent bits and version-dependent bits may be referred to by various names, such as the first control bit and the second control bit.

[0159] For example, the version-independent bits of the U-SIG may include a 3-bit physical layer version identifier (PHY version identifier). For example, the 3-bit physical layer version identifier may include information about the physical layer version (PHY version) of the transmitted / received PPDU. For example, a first value of the 3-bit physical layer version identifier can indicate that the transmitted / received PPDU is an EHT PPDU. In other words, when transmitting an EHT PPDU, the transmitting STA can set the 3-bit physical layer version identifier to the first value. In other words, the receiving STA can determine that the received PPDU is an EHT PPDU based on the physical layer version identifier having the first value.

[0160] For example, the version independent bits of the U-SIG may include a 1-bit UL / DL flag field, where a first value of the 1-bit UL / DL flag field is associated with UL communication and a second value of the UL / DL flag field is associated with DL communication.

[0161] 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.

[0162] For example, when EHT PPDUs are divided into various types (e.g., EHT PPDUs associated with SU mode, EHT PPDUs associated with MU mode, EHT PPDUs associated with TB mode, EHT PPDUs associated with Extended Range transmission, etc.), information regarding the type of EHT PPDU may be included in the version-dependent bits of the U-SIG.

[0163] For example, the U-SIG may include information regarding 1) a bandwidth field containing information regarding the bandwidth, 2) a field containing information regarding the MCS technique applied to the EHT-SIG, 3) an indication field containing information regarding whether the DCM technique is applied to the EHT-SIG, 4) a field containing information regarding the number of symbols used for the EHT-SIG, 5) a field containing information regarding whether the EHT-SIG is generated across the entire band, 6) a field containing information regarding the type of EHT-LTF / STF, and 7) a field indicating the length of the EHT-LTF and the CP length.

[0164] Preamble puncturing may be applied to the PPDU in FIG. 13. Preamble puncturing may refer to the transmission of a PPDU in which no signal is present in one or more 20 MHz subchannels in the PPDU's bandwidth. Preamble puncturing may be applied to PPDUs transmitted to one or more users. For example, the resolution of preamble puncturing may be 20 MHz for EHT MU PPDUs in OFDMA transmissions with bandwidths greater than 40 MHz and in non-OFDMA transmissions with 80 MHz and 160 MHz bandwidths. In other words, puncturing of subchannels smaller than 242-tone RUs may not be allowed in the above cases. Also, the resolution of preamble puncturing may be 40 MHz for EHT MU PPDUs in non-OFDMA transmissions with a 320 MHz bandwidth. In other words, puncturing of subchannels smaller than 484-tone RUs may not be allowed in the 320 MHz bandwidth. Also, preamble puncturing may not be applied to the primary 20 MHz channel in the EHT MU PPDU.

[0165] For example, for an EHT MU PPDU, information about preamble puncturing may be included in the U-SIG and / or the EHT-SIG, e.g., a first field of the U-SIG may include information about the contiguous bandwidth of the PPDU, and a second field of the U-SIG may include information about preamble puncturing applied to the PPDU.

[0166] For example, the U-SIG and EHT-SIG may include information about preamble puncturing based on the following method: When the bandwidth of a PPDU exceeds 80 MHz, the U-SIGs may be individually configured in 80 MHz increments. For example, when the bandwidth of a PPDU is 160 MHz, the PPDU may include a first U-SIG for a first 80 MHz band and a second U-SIG for a second 80 MHz band. In this case, the first field of the first U-SIG may include information about the 160 MHz bandwidth, and the second field of the first U-SIG may include information about the preamble puncturing applied to the first 80 MHz band (i.e., information about the preamble puncturing pattern). Furthermore, the first field of the second U-SIG may include information about the 160 MHz bandwidth, and the second field of the second U-SIG may include information about the preamble puncturing applied to the second 80 MHz band (i.e., information about the preamble puncturing pattern). The EHT-SIG subsequent to the first U-SIG may include information regarding the preamble puncturing applied to the second 80 MHz band (i.e., information regarding the preamble puncturing pattern), and the EHT-SIG subsequent to the second U-SIG may include information regarding the preamble puncturing applied to the first 80 MHz band (i.e., information regarding the preamble puncturing pattern).

[0167] Additionally or alternatively, the U-SIG and the EHT-SIG may include information about preamble puncturing based on the following method: The U-SIG may include information about preamble puncturing for the entire band (i.e., information about the preamble puncturing pattern). That is, the EHT-SIG may not include information about preamble puncturing, and only the U-SIG may include information about preamble puncturing (i.e., information about the preamble puncturing pattern).

[0168] A U-SIG may be configured in 20 MHz units. For example, when an 80 MHz PPDU is configured, a U-SIG may be duplicated. That is, four identical U-SIGs may be included in the 80 MHz PPDU. PPDUs exceeding the 80 MHz bandwidth may contain different U-SIGs.

[0169] 13 may include control information for the receiving STA. The EHT-SIG may be transmitted in at least one symbol, and one symbol may have a length of 4 us. Information regarding the number of symbols used for the EHT-SIG may be included in the U-SIG.

[0170] The EHT-SIG may include the technical features of the HE-SIG-B described in Figures 11 and 12. For example, the EHT-SIG may include a common field and a user-specific field, similar to the example of Figure 8. The common field of the EHT-SIG may be omitted, and the number of user-specific fields may be determined based on the number of users.

[0171] 11, the common fields of the EHT-SIG and the user-specific fields of the EHT-SIG may be coded separately. One user block field included in the user-specific fields contains information for two user fields, but the last user block field included in the user-specific fields may contain one or two user fields. That is, one user block field of the EHT-SIG may contain up to two user fields. As in the example of FIG. 12, each user field may be associated with either a MU-MIMO allocation or a non-MU-MIMO allocation.

[0172] Similar to the example of FIG. 11, the common field of the EHT-SIG may include CRC bits and Tail bits, where the length of the CRC bits may be determined to be 4 bits, and the length of the Tail bits may be determined to be 6 bits and set to 000000.

[0173] 11, the common field of the EHT-SIG may include RU allocation information. The RU allocation information may refer to information about the locations of RUs to which multiple users (i.e., multiple receiving STAs) are assigned. The RU allocation information may be configured in units of 9 bits (or N bits).

[0174] 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.

[0175] The EHT-SIG may be configured based on various MCS schemes. As described above, information about the MCS scheme applied to the EHT-SIG may be included in the U-SIG. The EHT-SIG may be configured based on the DCM scheme. The DCM scheme reuses the same signal on two subcarriers to provide an effect similar to frequency diversity, thereby reducing interference and improving coverage. For example, modulation symbols using the same modulation scheme may be repeatedly mapped on available tones / subcarriers. For example, of the N data tones (e.g., 52 data tones) allocated for the EHT-SIG, modulation symbols using a specific modulation scheme (e.g., BPSK modulation symbols) may be mapped to the first consecutive half of the tones (e.g., the 1st to 26th tones), and modulation symbols using the same specific modulation scheme (e.g., BPSK modulation symbols) may be mapped to the remaining consecutive half of the tones (e.g., the 27th to 52nd tones). That is, the modulation symbol mapped to the 1st tone and the modulation symbol mapped to the 27th tone are the same. As described above, information (e.g., a 1-bit field) regarding whether the DCM technique is applied to the EHT-SIG may be included in the U-SIG. The EHT-STF of FIG. 13 may be used to improve automatic gain control (AGC) estimation in a MIMO environment or an OFDMA environment. The EHT-LTF of FIG. 13 may be used to estimate a channel in a MIMO environment or an OFDMA environment.

[0176] Information regarding the type of STF and / or LTF (including information regarding the GI (guard interval) applied to the LTF) may be included in the U-SIG field and / or EHT-SIG field of FIG. 13, for example.

[0177] The PPDU in FIG. 13 (ie, the EHT PPDU) may be configured based on the example of the RU arrangement in FIGS.

[0178] For example, an EHT PPDU transmitted on a 20 MHz band, i.e., a 20 MHz EHT PPDU, may be configured based on the RUs in Figure 8. That is, the RU locations of the EHT-STF, EHT-LTF, and data fields included in the EHT PPDU may be determined as shown in Figure 8. An EHT PPDU transmitted on a 40 MHz band, i.e., a 40 MHz EHT PPDU, may be configured based on the RUs in Figure 9. That is, the RU locations of the EHT-STF, EHT-LTF, and data fields included in the EHT PPDU may be determined as shown in Figure 9.

[0179] An EHT PPDU transmitted on the 80 MHz band, i.e., an 80 MHz EHT PPDU, may be configured based on the RU in Figure 10. That is, the RU locations of the EHT-STF, EHT-LTF, and data fields included in the EHT PPDU may be determined as shown in Figure 10. The tone-plan for 80 MHz in Figure 10 may correspond to two repetitions of the tone-plan for 40 MHz in Figure 9.

[0180] The tone plan for 160 / 240 / 320 MHz may be configured to repeat the pattern of FIG. 9 or FIG. 10 multiple times.

[0181] The PPDU in FIG. 13 may be identified as an EHT PPDU based on the following method.

[0182] A receiving STA can determine the type of a received PPDU as an EHT PPDU based on the following: 1) the first symbol after the L-LTF signal of the received PPDU is BPSK; 2) an RL-SIG in which the L-SIG of the received PPDU is repeated is detected; and 3) the result of applying modulo 3 arithmetic to the value of the Length field of the L-SIG of the received PPDU (i.e., the remainder when divided by 3) is detected as 0, the received PPDU may be determined to be an EHT PPDU. If the received PPDU is determined to be an EHT PPDU, the receiving STA can determine the type of EHT PPDU based on bit information included in the symbol after the RL-SIG in FIG. 13. In other words, the receiving STA can determine the type of a received PPDU as an EHT PPDU based on 1) the first symbol after the L-LTF signal, which is BSPK; 2) an RL-SIG that follows the L-SIG field and is identical to the L-SIG; and 3) an L-SIG including a Length field in which the result of applying modulo 3 arithmetic is set to 0.

[0183] 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.

[0184] For example, the receiving STA can determine the type of the received PPDU as non-HT, HT, or VHT PPDU based on the following: For example, if 1) the first symbol after the L-LTF signal is BPSK, and 2) an RL-SIG in which the L-SIG is repeated is not detected, the received PPDU may be determined to be a non-HT, HT, or VHT PPDU.

[0185] Furthermore, if the receiving STA detects an RL-SIG in which the L-SIG is repeated from the received PPDU, it can determine that the PPDU is an HE PPDU or EHT PPDU. In this case, if the rate (6Mbps) check fails, the received PPDU may be determined to be a non-HT, HT, or VHT PPDU. If the rate (6Mbps) check and parity check pass, if the result of applying modulo 3 to the L-SIG Length value is detected as 0, the received PPDU may be determined to be an EHT PPDU, and if the result of Length modulo 3 is not 0, the received PPDU may be determined to be an HE PPDU.

[0186] The PPDU in Figure 13 may be used to transmit and receive various types of frames, for example, the PPDU in Figure 13 may be used to (simultaneously) transmit and receive one or more of a control frame, a management frame, or a data frame.

[0187] The U-SIG included in the EHT PPDU will be described in more detail below.

[0188] For a 40 MHz EHT PPDU or ER (Extended Range) preamble, the U-SIG content is identical in the two 20 MHz subchannels. For an 80 MHz EHT PPDU or ER preamble, the U-SIG content is identical in all non-punctured 20 MHz subchannels. For a 160 / 320 MHz EHT PPDU or ER preamble, the U-SIG content is identical in all non-punctured 20 MHz subchannels within each 80 MHz subblock and may differ from the U-SIG content in other 80 MHz subblocks.

[0189] The U-SIG-1 part of the U-SIG of the EHT MU PPDU may include PHY version identifier (B0-B2), BW (B3-B5), UL / DL (B6), BSS color (B7-B12), and TXOP (B13-B19), and the U-SIG-2 part may include PPDU type and compression mode (B0-B1), validate (B2), punctured channel information (B3-B7), validate (B8), EHT-SIG MCS (B9-B10), number of EHT-SIG symbols (B11-B15), CRC (B16-B19), and tail (B20-B25).

[0190] Next, the U-SIG-1 part of the U-SIG of the EHT TB PPDU may include a version identifier (B0-B2), BW (B3-B5), UL / DL (B6), BSS color (B7-B12), TXOP (B13-B19), and disregard (B20-B25), and the U-SIG-2 part may include a PPDU type and compression mode (B0-B1), validate (B2), spatial reuse 1 (B3-B6), spatial reuse 2 (B7-B10), disregard (B11-B15), CRC (B16-B19), and tail (B20-B25).

[0191] As mentioned above, the U-SIG field of the EHT MU PPDU contains 5-bit punctured channel information, but the EHT TB PPDU does not contain punctured channel information because it is assumed that the EHT TB PPDU is configured according to the resource allocation indicated by the trigger frame or TRS control information, and therefore the STA does not need to inform the AP of the resource information of the EHT TB PPDU.

[0192] Furthermore, even if a STA receives the trigger frame or TRS control information as described above, it may not respond with an HE TB PPDU. For example, if a non-AP STA finds that one or more subfields of the common information field included in the trigger frame or the user field addressed to or selected by the non-AP STA have values ​​that it does not recognize, support, or satisfy, the non-AP STA may choose not to respond to the trigger frame. Similarly, if a non-AP STA finds that the TRS control subfield included in a frame addressed to the non-AP STA has a value that it does not recognize, support, or satisfy, the non-AP STA may choose not to respond to the TRS control subfield.

[0193] Target wake time (TWT)

[0194] TWT is a power saving (PS) technology that can improve the energy efficiency of non-AP STAs by defining a service period (SP) between the AP and non-AP STAs, sharing information about the SP, and reducing medium contention.

[0195] An STA that makes a request / suggest / demand during the TWT setup phase can be called a TWT requesting STA, and an AP that responds to the request with an accept / reject can be called a TWT responding STA.

[0196] The setup phase may include a process of determining / defining a TWT request from the STA to the 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.

[0197] FIG. 14 is a diagram for explaining an example of individual TWT operation to which the present disclosure can be applied.

[0198] Individual TWT is a mechanism in which an AP and a non-AP STA negotiate the awake / doze status of a non-AP STA by sending and receiving TWT request / response frames, and then exchange data.

[0199] In the example of FIG. 14, the AP and STA1 can form a trigger-enabled TWT agreement by a TWT request frame and a TWT response frame.

[0200] Here, the method used by STA1 is the solicited TWT method, in which STA1 sends a TWT request frame to the AP and receives information for TWT operation from the AP using a TWT response frame.

[0201] On the other hand, STA2 using the unsolicited TWT method can receive information about the trigger-enabled TWT agreement setting from the AP using an unsolicited TWT response.

[0202] Specifically, STA2 can calculate the next TWT by adding a specific number to the current TWT value. In a trigger-enabled TWT SP, the AP can send a trigger frame to the STA. The trigger frame can inform the STA that there is buffered data in the AP. In response, STA1 can inform the AP of its awake state by sending a PS-Poll frame. STA2 can inform the AP of its awake state by sending a QoS Null frame. Here, the data frames transmitted by STA1 and STA2 may be in the TB PPDU format. After checking the states of STA1 and STA2, the AP can transmit a DL MU PPDU to the awake STAs. When the TWT SP expires, STA1 and STA2 may switch to a doze state.

[0203] FIG. 15 is a diagram illustrating an example of a broadcast TWT operation to which the present disclosure can be applied.

[0204] Broadcast TWT is a TWT scheme in which a non-AP STA (or a TWT scheduling STA) obtains information about a target beacon transmission time (TBTT) and a listen interval by transmitting and receiving a TWT request / response frame to and from an AP (or a TWT scheduled STA). Here, a negotiation operation for the TBTT may be performed. Based on this, the AP can define a frame including TWT scheduling information using a beacon frame.

[0205] In Figure 15, STA1 performs solicited TWT operation, and STA2 performs unsolicited TWT operation. The AP can transmit a DL MU PPDU after confirming the awake state of the STA using the trigger it sent. This may be the same as the individual TWT process. In broadcast TWT, a trigger-enabled TWT SP including a beacon frame may be repeated multiple times at regular intervals.

[0206] TWT information may be conveyed by a TWT information frame and a TWT information element. A TWT information frame is transmitted by a STA to request or convey information about a TWT agreement and is transmitted by one of the STAs in an existing TWT agreement. The action field 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.

[0207] FIG. 16 is a diagram illustrating an example of a TWT information element format.

[0208] The TWT element may be transmitted and received within a beacon, a probe response, a (re)association response frame, etc. The TWT element may include an element ID field, a length field, a control field, and a TWT parameter information field.

[0209] The control field of the TWT element has the same format regardless of whether it is an individual TWT or a broadcast TWT.

[0210] The NDP paging indication subfield may have a value of 1 if the NDP paging field is present and a value of 0 if the NDP paging field is not present.

[0211] The responder PM mode subfield may indicate a Power Management (PM) mode.

[0212] The negotiation type subfield may indicate whether the information contained in the TWT element is for negotiating parameters of the broadcast TWT or individual TWT(s), or for the wake TBTT interval.

[0213] For example, if the negotiation type subfield has a value of 0, the TWT subfield relates to a future individual TWT SP start time, and the TWT element contains one individual TWT parameter set, which may correspond to an individual TWT negotiation between the TWT requesting STA and the TWT responding STA, or an individual TWT announcement by the TWT responder.

[0214] For example, if the negotiation type subfield has a value of 1, the TWT subfield relates to the next TBTT time, and the TWT element contains one individual TWT parameter set, which may correspond to wake TBTT and wake interval negotiation between a TWT-scheduled STA and a TWT-scheduling AP.

[0215] 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.

[0216] For example, if the negotiation type subfield has a value of 3, the TWT subfield is for a future broadcast TWT SP start time, and the TWT element includes one or more broadcast TWT parameter sets. This may involve managing membership in the broadcast TWT schedule by including the TWT element in an individually addressed management frame transmitted by either the TWT-scheduled STA or the TWT-scheduling AP.

[0217] The TWT information frame disabled subfield, when set to 1, indicates that reception of TWT information frames by the STA is disabled; otherwise, it may be set to 0.

[0218] The Wake Duration Unit subfield indicates the unit of the Nominal Minimum TWT Wake Duration field. The Wake Duration Unit subfield may be set to 0 if the unit is 256us and to 1 if the unit is TU. If the STA is not an HE / EHT STA, the Wake Duration Unit subfield may be set to 0.

[0219] The most significant bit (MSB) of the negotiation type field may correspond to a broadcast field. If the broadcast field is 1, the TWT element may include one or more broadcast TWT parameter sets. If the broadcast field is 0, the TWT element may include only one individual TWT parameter set. A TWT element with the broadcast field set to 1 may be referred to as a broadcast TWT element.

[0220] 16 shows a case where the reserved field is configured with two bits, but this is only one example. For example, a TWT element may include a Link ID bitmap present field (e.g., 1 bit) and a reserved field (e.g., 1 bit).

[0221] For example, when the link ID bitmap presence field is set to 1, the link ID bitmap subfield is set to be present in the individual TWT parameter set field format described below, and when the link ID bitmap presence field is set to 0, the link ID bitmap subfield is set not to be present in the individual TWT parameter set field format.

[0222] Fig. 17 is a diagram illustrating an example of an individual TWT parameter set field format, and Fig. 18 is a diagram illustrating an example of a broadcast TWT parameter set field format.

[0223] The TWT parameter information field included in the TWT element in FIG. 16 may have different configurations depending on whether the TWT is an individual TWT or a broadcast TWT.

[0224] If it is an individual TWT, the TWT parameter information field in the TWT element contains a single individual TWT parameter set field.

[0225] 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.

[0226] As shown in Figures 17 and 18, the individual TWT parameter set field and the broadcast TWT parameter set field include common subfields.

[0227] The request type subfield may have the same size in the individual TWT parameter set field and the broadcast TWT parameter set field, but may have different detailed configurations, as will be described later.

[0228] The target wake time subfield indicates the start time of a later scheduled individual / broadcast TWT SP.

[0229] The nominal maximum TWT wake duration subfield indicates the minimum unit that the TWT requesting STA expects to wake up to complete a frame exchange associated with the TWT flow identifier in the TWT wake interval duration. Here, the TWT wake interval may refer to the average time between consecutive TWT SPs that the TWT requesting STA expects.

[0230] The TWT Wake Interval Mantissa subfield is the binary value of the TWT wake interval value, which can be expressed in microseconds.

[0231] Referring to FIG. 17, the TWT group assignment subfield, the TWT channel, and the NDP paging subfield are included only in the individual TWT parameter set field.

[0232] The TWT Group Assignment subfield provides the TWT requesting STA with information about the TWT group to which the STA is assigned. This information can be used to calculate the TWT value within the TWT group. The TWT value of the STA may be equal to the value of the zero offset and the TWT offset multiplied by the TWT unit value.

[0233] The TWT Channel subfield indicates a bitmap indicating allowed channels. When transmitted by a TWT requesting STA, the TWT Channel subfield may contain a bitmap indicating channels that the STA requests to use as temporary fundamental channels in the TWT SP. When transmitted by a TWT responding STA, the TWT Channel subfield may contain a bitmap indicating channels on which the TWT request is allowed.

[0234] The NDP paging subfield is optional and may include an identifier for the STA being paged, information about the maximum number of TWT wake intervals between NDP paging frames, and the like.

[0235] Referring to Figure 18, the Broadcast TWT Info subfield is included only in the Broadcast TWT Parameter Set field. The Broadcast TWT Info subfield may include a 3-bit reserved bit, a 5-bit Broadcast TWT Identifier (ID) subfield, and an 8-bit Broadcast TWT Persistence subfield. The Broadcast TWT Identifier subfield indicates the broadcast ID of a specific Broadcast TWT to which a STA requests participation or provides TWT parameters, depending on the value of the TWT Setup Command subfield of the TWT element. The Broadcast TWT Persistence subfield indicates the number of TBTTs planned on the schedule of the Broadcast TWT.

[0236] Next, the detailed structure of the request type subfield will be described.

[0237] First, the format of the request type subfield of the individual TWT parameter set field will be described with reference to FIG.

[0238] The TWT request subfield can indicate whether it is a requesting STA or a responding STA. If its value is 1, it indicates a TWT requesting STA or a scheduled STA, and if its value is 0, it indicates a TWT responding STA or a scheduling AP.

[0239] The TWT setup command subfield can indicate commands such as Request, Suggest, Demand, Accept, Alternate, Dictate, and Reject.

[0240] The trigger subfield indicates whether a trigger frame is used in the TWT SP. If the value is 1, a trigger is used, and if the value is 0, a trigger is not used.

[0241] The implicit subfield can indicate implicit or explicit TWT, where a value of 1 indicates implicit TWT and a value of 0 indicates explicit TWT.

[0242] The flow type subfield can indicate the type of interaction between a TWT requesting STA (or a TWT-scheduled STA) and a TWT responding STA (or a TWT-scheduling AP). If its value is 1, it can indicate announced TWT, in which the STA transmits a PS-Poll or APSD (automatic power save delivery) trigger frame to send a wake-up signal to the AP before any frame other than the trigger frame is transmitted from the AP to the STA. If its value is 0, it can indicate unannounced TWT.

[0243] 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.

[0244] The TWT wake interval exponent subfield can be set to the TWT wake interval value in binary microseconds. In the case of an individual TWT, it can refer to the interval between individual TWT SPs. The TWT wake interval of the requesting STA may be defined as [TWT Wake Interval Mantissa * 2 * TWT Wake Interval Exponent].

[0245] The TWT protection subfield can indicate whether to use a TWT protection mechanism. If its value is 1, the TXOP in the TWT SP can be initiated with a NAV protection mechanism such as a (MU)RTS / CTS or CTS-to-self frame; if its value is 0, the NAV protection mechanism is not applied.

[0246] 18, some of the subfields of the Request Type subfield in the Broadcast TWT Parameter Set field are common to the subfields of the Request Type subfield in the Individual TWT Parameter Set field, and therefore, a description thereof will be omitted. The subfields included only in the Broadcast TWT Parameter Set field will be described below.

[0247] The Last Broadcast Parameter Set subfield indicates whether this is the last broadcast TWT parameter set. If the value is 1, it indicates that this is the last broadcast TWT parameter set, and if the value is 0, it indicates that there is a next broadcast TWT parameter set.

[0248] The Broadcast TWT recommendation subfield can indicate a recommendation for the frame type to be transmitted by the AP in the Broadcast TWT SP with a value of 1 to 7.

[0249] The last bit of the Request Type subfield of the Broadcast TWT Parameter Set field may be reserved.

[0250] The following describes a low latency transmission scheme according to the present disclosure to support latency sensitive traffic.

[0251] In recent years, with the rapid growth of wired and wireless traffic, latency-sensitive traffic has also increased significantly. Latency-sensitive traffic includes real-time audio / video transmission, and with the proliferation of multimedia devices, the need to support this traffic in wireless environments has increased. However, compared to wired environments, supporting latency-sensitive traffic in wireless environments requires more considerations. This is because the transmission speed in wireless environments is lower than that in wired environments, and interference issues from surrounding areas must also be taken into account. In particular, in WLAN systems, since a large number of STAs must compete equally for medium occupancy in the Industry-Science-Medical (ISM) band, supporting latency-sensitive traffic is relatively difficult compared to cellular communication networks based on radio resource scheduling by a central base station. This disclosure describes a novel scheme for supporting latency-sensitive traffic in WLAN systems.

[0252] In this disclosure, latency may refer to the latency defined in the IEEE 802.11 series of standards, for example, the time from when a frame to be transmitted enters a queue at the MAC layer of a transmitting STA, when the transmitting STA successfully completes transmission at the PHY layer, when the transmitting STA receives an ACK / block ACK from a receiving STA, and when the frame is deleted from the MAC layer queue of the transmitting STA.

[0253] In addition, in this disclosure, a non-AP STA that supports transmission of latency sensitive data may be referred to as a low latency STA, and data other than latency sensitive data may be referred to as regular data.

[0254] In the following, restricted TWT will be described with reference to FIG.

[0255] Restricted TWT (r-TWT) can help ensure data transmission availability for low-latency STAs by having the AP set up a special broadcast TWT for low-latency STAs transmitting latency-sensitive data. STAs can establish membership to one or more r-TWT schedules with the AP.

[0256] Here, the r-TWT agreement may be established by the same process as the broadcast TWT agreement, and therefore, the broadcast TWT element 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 be a special case of the broadcast TWT parameter set field. In addition, the AP may announce the r-TWT SP.

[0257] In this disclosure, as previously mentioned, non-AP STAs that support transmission of latency-sensitive data may be referred to as low latency STAs, and data that is not latency-sensitive may be referred to as regular data.

[0258] Additionally or alternatively, a low latency STA associated with a particular r-TWT is referred to as a member r-TWT scheduled STA, and other STAs are referred to as non-member STAs. A non-member STA may be a STA that has the capability to support r-TWT / TWT operations (e.g., individual TWT and / or broadcast TWT) but is not a member of any r-TWT, that supports r-TWT / TWT operations but is a member of another r-TWT, or that does not have the capability to support r-TWT / TWT operations.

[0259] A STA that supports broadcast TWT limited SP (or r-TWT SP) operation (e.g., a low-latency STA) can inform the AP that it must transmit latency-sensitive data based on the r-TWT operation. If the AP supports r-TWT operation / mode, the AP can transmit a frame containing scheduling information for the TWT requested by each STA to the low-latency STA and other STAs. For example, to perform r-TWT operation, a non-AP STA can obtain r-TWT-related information from the AP using a beacon frame, a probe response frame, a (re)association response frame, or other undefined format frame (e.g., a broadcast, advertisement, or public-use frame).

[0260] According to r-TWT operation, a separate TXOP (i.e., access by other STAs is restricted) may be reserved (or performed) within the r-TWT SP using a NAV such as (MU)RTS / CTS or CTS-to-self, or a quiet interval. Before a specific r-TWT SP begins, any TXOPs from STAs other than the STA having membership in the specific r-TWT schedule (i.e., non-member STAs) must be stopped. The TXOPs from the other STAs (i.e., non-member STAs) may then be performed after the specific r-TWT SP ends. This can be referred to as TXOP rule-based operation for r-TWT SPs for non-member STAs. Such r-TWT TXOP rules enable more predictable, low-latency service to be provided for latency-sensitive data.

[0261] Conditional execution method of r-TWT

[0262] According to the above-mentioned r-TWT TXOP rules, an EHT non-AP that supports a publicly announced r-TWT SP and is associated with the AP that announced the r-TWT SP must terminate its own TXOP before starting the r-TWT SP.

[0263] This disclosure describes additional execution conditions for the r-TWT SP TXOP rules described above, which enable the r-TWT SP TXOP rules described above to provide the desired predictable low latency service and improve the efficiency of delay-sensitive data / traffic transmission in a manner that does not disrupt existing data transmission / reception flows.

[0264] 20A and 20B are diagrams illustrating a limited TWT operation of a first STA according to an example of the present disclosure. In FIGS. 20A and 20B, the first STA is an EHT non-AP STA (associated with an AP), and the second STA is an AP, but the present disclosure is not limited thereto.

[0265] The first STA may perform a restricted target wake time (r-TWT) membership setup procedure with the second STA (S2010).

[0266] The r-TWT membership setup procedure may be established identically to the broadcast TWT membership procedure, except that in the r-TWT membership setup procedure, the broadcast TWT element transmitted on the TWT setup frame may include one or more r-TWT parameter set fields.

[0267] The second STA (e.g., the r-TWT scheduling AP) and the first STA (e.g., the R-TWT scheduled STA) can configure the r-TWT traffic information field to identify the TIDs carrying delay-sensitive traffic on the DL and UL for the established r-TWT membership. That is, at least one r-TWT DL TID or at least one r-TWT UL TID may be configured by the first and second STAs.

[0268] The TIDs designated as delay-sensitive traffic in the DL and UL in the r-TWT traffic information field may be collectively referred to as r-TWT TIDs. The TIDs designated as delay-sensitive traffic in the DL and UL in the r-TWT traffic information field may be within the TID sets mapped to the DL and UL, respectively.

[0269] Hereinafter, the TIDs specified in the r-TWT traffic information field of the TWT element of the TWT response frame indicating an Accept TWT are referred to as R-TWT DL TID(s) or R-TWT UL TID(s).

[0270] The first STA may receive r-TWT schedule information included in the broadcast TWT element from the second STA (S2020).

[0271] Specifically, when there is an established r-TWT membership, the second STA can announce the r-TWT schedule information by including an r-TWT parameter set field in the broadcast TWT element included in the transmitted management frame.

[0272] As an example, the first information may include receiving r-TWT schedule information in a beacon frame and / or a probe response frame.

[0273] As an example of the present disclosure, the first TXOP may end before the start time of the r-TWT SP based on the fact that a specific portion of the first TXOP in the r-TWT SP announced by the r-TWT schedule information is not used to deliver a DL frame corresponding to at least one r-TWT downlink (DL) TID or to solicit a UL frame corresponding to at least one r-TWT uplink (UL) TID.

[0274] Specifically, when a second STA that has announced the r-TWT SP is the holder of the first TXOP, if a specific portion of the first TXOP is not used to deliver a DL frame corresponding to at least one r-TWT DL TID or to solicit a UL frame corresponding to at least one r-TWT UL TID, the second STA can ensure that the first TXOP ends before the start time of the r-TWT SP.

[0275] That is, if a specific portion of the first TXOP is not used for frame transmission / reception corresponding to at least one r-TWT DL TID or at least one r-TWT UL TID, the second STA can ensure that the first TXOP ends before the start time of the r-TWT SP.

[0276] As yet another example, the first TXOP may not terminate even after the start time of the r-TWT SP, based on the fact that a specific portion of the first TXOP is used to transmit a DL frame corresponding to at least one r-TWT DL TID or to request a UL frame corresponding to at least one r-TWT UL TID.

[0277] The end time of the r-TWT SP may be postponed based on the fact that the first TXOP does not end after the start time of the r-TWT SP. As an example, the end time of the r-TWT SP may be postponed by the time of the delayed r-TWT SP because the first TXOP does not end after the start time of the r-TWT SP.

[0278] Additionally or alternatively, the maximum time that the end time of an r-TWT SP may be postponed may be set / indicated / defined as the (start) time value of the delayed r-TWT SP.

[0279] As yet another example of the present disclosure, based on the first STA being the holder of the second TXOP, the second TXOP may terminate before the start of the r-TWP SP announced by the second STA, i.e., the first STA can ensure that the second TXOP terminates before the start of the r-TWP SP announced by the second STA.

[0280] FIG. 21 is a diagram illustrating a limited TWT operation of a second STA according to an example of the present disclosure.

[0281] The second STA may perform a restricted target wake time (r-TWT) membership setup procedure with the first STA (S2110).

[0282] As an example, the second STA may set the trigger field value to 1 in the r-TWT parameter set field that it transmits.

[0283] The second STA may transmit the r-TWT schedule information included in the broadcast TWT element to the first STA (S2120).

[0284] Specifically, if there is an established r-TWT membership, the second STA may advertise the r-TWT schedule information by including an r-TWT parameter set field in the broadcast TWT element.

[0285] The operations and parameters associated with S2110 and S2120 may correspond to the operations and parameters associated with S2010 and S2020, and therefore, redundant explanations will be omitted.

[0286] The following describes in detail the conditional execution method of the r-TWT according to the present disclosure. That is, the conditional TXOP rule of the r-TWT SP, which reflects additional conditions to the TXOP rule of the r-TWT SP described above, will be described. One or more STAs can perform operations according to one or more of the following embodiments.

[0287] Example 1

[0288] The first embodiment relates to a method for implementing the conditional TXOP rule of r-TWT SP according to data priority.

[0289] A rule may be defined that an EHT non-AP STA that supports an r-TWT SP announced by an AP and is associated with the AP that announced the r-TWT SP should end its TXOP before starting the r-TWT SP. However, the rule may be executed / applied only when the data transmitted by the STA (e.g., the EHT non-AP STA and / or AP) in the TXOP is not data that should be transmitted more urgently than delay-sensitive data.

[0290] That is, the rule may be applied / executed when the data transmitted by the STA (e.g., the EHT non-AP STA or / and AP) in the TXOP is data that should be transmitted more urgently than delay-sensitive data.

[0291] Specifically, the rule may be applied / executed only if a specific condition is met, and the specific condition may be set / defined as one of the options described below.

[0292] Option 1

[0293] If the data transmitted in the TXOP is not data for one of the TIDs classified as latency traffic, the above-described TXOP rules may be applied / executed.

[0294] That is, if the data to be transmitted in the TXOP is not data for one of the TIDs classified as delayed traffic, the STA (e.g., the EHT non-AP STA and / or AP) may terminate the TXOP when the r-TWT SP begins.

[0295] Furthermore, if the data to be transmitted in the TXOP is data for one of the TIDs classified as delayed traffic, the STA (e.g., the EHT non-AP STA and / or AP) can continue transmitting the data without terminating the TXOP (even if the start point of the r-TWT SP has passed).

[0296] Option 2

[0297] If the data to be transmitted in the TXOP is traffic with a lower priority than the delay traffic specified in the r-TWT SP (i.e., if the data to be transmitted in the TXOP is not data that should be transmitted more urgently than the delay-sensitive data), the above-mentioned TXOP rules may be applied / executed.

[0298] That is, if the data to be transmitted in the TXOP is traffic with a lower priority than the delayed traffic specified in the r-TWT SP, the STA (e.g., the EHT non-AP STA and / or AP) may terminate the TXOP when the r-TWT SP begins.

[0299] Furthermore, if the data transmitted in the TXOP has a higher priority than or the same priority as the delayed traffic specified in the r-TWT SP, the STA (e.g., the EHT non-AP STA and / or AP) can continue transmitting the data without terminating the TXOP (even after the start of the r-TWT SP has passed).

[0300] Option 3

[0301] If the data transmitted in the TXOP belongs to a specific AC, the above-mentioned TXOP rules may be applied / executed.

[0302] That is, if the data transmitted in the TXOP is for a specific AC, the STA (e.g., the EHT non-AP STA and / or AP) may terminate the TXOP when the r-TWT SP begins. If the data transmitted in the TXOP is for another AC (e.g., AC_VO or AC_VI), the STA (e.g., the EHT non-AP STA and / or AP) may continue transmitting the data without terminating the TXOP (even after the start of the r-TWT SP has passed).

[0303] Here, the specific AC may be, but is not limited to, AC_BE or AC_BK. For example, even when the data transmitted in the TXOP is AC_VI, the above-mentioned TXOP rules may be applied / executed.

[0304] Example 2

[0305] The second embodiment relates to a method for executing the conditional TXOP rule of the r-TWT SP according to the importance of data transmitted and received by a STA that has negotiated the r-TWT SP.

[0306] While supporting an r-TWT SP announced by an AP, a TXOP rule may be defined so that an EHT non-AP STA associated with the AP that announced the r-TWT SP terminates the TXOP before the r-TWT SP starts.

[0307] However, at the time of r-TWT setup, the TXOP rule may be applied / executed only if the data transmitted in the TXOP is not data indicated as delay-sensitive data / traffic by the UL / DL TID negotiated by the STA (e.g., EHT non-AP STA and / or AP).

[0308] That is, if the data transmitted in the TXOP is data indicated as delay-sensitive data / traffic by the UL / DL TID negotiated by the STA (e.g., EHT non-AP STA and / or AP), the STA may not terminate the TXOP even after the start of the r-TWT SP.

[0309] Specifically, STAs supporting r-TWT and having the same broadcast TWT ID value may receive r-TWT SP information from the AP. The AP and the STA proceeding with r-TWT setup to be assigned an r-TWT SP can negotiate for delay-sensitive data / traffic using the UL / DL TID.

[0310] This allows the AP and the STA assigned with the r-TWT SP to share TID information that indicates / indicates delay-sensitive data / traffic in the r-TWT SP. Due to the above conditions, when the STA transmits data with a TID that is indicated / indicated as delay-sensitive data / traffic (by the scheduled r-TWT SP), it does not need to abort its TXOP before the start of the r-TWT SP.

[0311] 22 and 23 illustrate the process in which the conditional TXOP rule of the r-TWT SP according to the second embodiment is applied.

[0312] Any of the RSP STAs (STAs supporting r-TWT SP), RSP STA 1, RSP STA 2, and RSP STA 3, can perform the TWT setup procedure. However, Figures 22 and 23 illustrate the process in which RSP STA 2 performs the TWT setup procedure and the process in which the AP and RSP STA 2 establish membership.

[0313] That is, Figures 22 and 23 illustrate an operation in which, when an AP announces TWT information to one or more RSP STAs in a beacon frame, the RSP STAs that receive the TWT information send a TWT request based on the broadcast TWT ID corresponding to the desired TWT.

[0314] As a result, RSP STA 1, RSP STA 2, and RSP STA 3 may all have the same broadcast TWT ID. RSP STA 1 may classify data corresponding to TIDs 0, 1, and 2 as delay-sensitive data / traffic. RSP STA 2 and RSP STA 3 may classify data corresponding to TIDs 0, 4, and 5 as delay-sensitive data / traffic.

[0315] When the beacon frame transmitted by the AP includes information on the r-TWT SP assigned to the RSP STA3, the (DL / UL) data classified as delay-sensitive data / traffic in the r-TWT SP may be data corresponding to TIDs 0, 4, and 5. If the RSP STA2 transmits data corresponding to TIDs 0, 4, and 5 before the start of the r-TWT SP, the RSP STA2 can complete the transmission and reception of the data corresponding to TIDs 0, 4, and 5 without canceling its TXOP before the r-TWT SP.

[0316] Here, the r-TWT SP may be extended by the time interval from the start of the r-TWT SP to the completion of the TXOP. That is, the r-TWT SP may start from the completion of the TXOP, and the r-TWT SP may be extended by this time interval. Additionally or alternatively, the maximum time by which the end time of the r-TWT SP may be postponed may be set / indicated / defined as the (start) time value of the delayed r-TWT SP.

[0317] Example 3

[0318] The third embodiment relates to a method for conditionally implementing / applying the above TXOP rules by a TXOP holder.

[0319] While supporting an r-TWT SP announced by an AP, an EHT non-AP STA associated with the AP that announced the r-TWT SP must terminate its TXOP before starting the r-TWT SP. However, if the EHT non-AP STA is an EHT non-AP STA that has been assigned an r-TWT SP announced by the AP, it does not need to stop / terminate its TXOP.

[0320] The existing r-TWT TXOP rules define the behavior of unconditionally stopping a TXOP in progress before an r-TWT SP when the r-TWT SP begins. This is to ensure that the sending and receiving operations of delay-sensitive data / traffic are safely completed within the r-TWT SP.

[0321] However, if the holder of a TXOP that was in progress before the r-TWT SP is the same STA that has been assigned the r-TWT SP, the STA does not need to suspend its TXOP before the start of the r-TWT SP. That is, the STA can efficiently complete transmission and reception of delay-sensitive data / traffic within the r-TWT SP while maintaining its TXOP.

[0322] 24 and 25 illustrate the process in which the conditional TXOP rule of the r-TWT SP according to the third embodiment is applied.

[0323] 24 and 25 illustrate the process of establishing membership between an AP and an RSP STA 2. When the AP broadcasts TWT information in a beacon frame, a STA that receives the TWT information can send a TWT request to the AP based on the broadcast TWT ID corresponding to the desired TWT.

[0324] If the beacon frame transmitted by the AP includes information on the r-TWT SP (RSP) assigned to RSP STA 2, RSP STA 2 may be a TXOP holder that transmits data in its TXOP before the scheduled r-TWT SP.

[0325] In this case, when the conditional TXOP rule according to the third embodiment is applied, since the scheduled r-TWT SP is the r-TWT SP assigned to the RSP STA 2, the RSP STA 2 can transmit and receive (UL / DL) delay-sensitive traffic within the r-TWT SP without canceling its own TXOP.

[0326] Example 4

[0327] The TXOP rule of the r-TWT SP may be applied to at least one of the above-described Example 1, Example 2, or Example 3. Example 4 relates to a method in which an AP can notify other STAs of the TXOP rule of the r-TWT SP to which the above-described example is applied.

[0328] In the unsolicited method, the AP can use beacon frames, (broadcast) probe response frames, and other (or / and new) public (or / and broadcast) frames to inform other STAs of information regarding the above-mentioned embodiments.

[0329] 26 and 27 are diagrams illustrating a process in which an AP notifies other STAs of information relating to the above embodiment.

[0330] Specifically, Figure 26 illustrates an example of r-TWT operation execution when regular data is more urgent than delay-sensitive data (or / and regular data has higher priority than delay-sensitive data), and Figure 27 illustrates an example of r-TWT operation execution when regular data is more urgent than delay-sensitive data (or / and regular data has higher priority than delay-sensitive data).

[0331] Additionally or alternatively, as shown in Figure 28, the UE and AP may exchange information related to this embodiment through a negotiation procedure (e.g., a probe request procedure, a probe response procedure, an association request procedure, an association response procedure, a new request procedure, and a new response procedure, etc.). Here, the probe / association / new request / response procedure may refer to a procedure for transmitting and receiving probe / association / new request / response frames.

[0332] During the negotiation procedure, information regarding delay traffic (e.g., real-time gaming, cloud gaming, real-time video, robotics and industrial automation, etc.), whether each AP / STA supports r-TWT SP, etc. may be exchanged.

[0333] This allows the AP and the low-latency STA to set up an optimal environment for the delay-sensitive traffic to be transmitted. As an example, the above-mentioned information may be transmitted and received by at least one of the following methods.

[0334] Method 1: The AP and the low-latency STA can exchange the above information through a single request and response procedure in the negotiation procedure.

[0335] Method 2: The AP and the low-latency STA can transmit the above information over (or separately) i) the probe request procedure and probe response procedure, and ii) the association request procedure and association response procedure.

[0336] Method 3: The above information may be exchanged by another novel request procedure and novel response procedure for transmitting information about low-latency STAs.

[0337] The embodiments described above are combinations of the components and features of the present disclosure in a predetermined form. Each component or feature should be considered optional unless otherwise explicitly stated. Each component or feature may be implemented without being combined with other components or features. It is also possible to combine some components and / or features to form embodiments of the present disclosure. The order of operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is clear that claims that do not have an explicit reference relationship in the claims may be combined to form embodiments, or may be included as new claims by amendment after filing.

[0338] It is obvious to those skilled in the art that the present disclosure can be embodied in other specific forms without departing from the essential features of the present disclosure. Therefore, the above detailed description should not be interpreted as limiting in any respect, but should be considered as illustrative. The scope of the present disclosure should be determined by reasonable interpretation of the appended claims, and any modifications within the equivalent scope of the present disclosure are included in the scope of the present disclosure.

[0339] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that cause a device or computer to perform operations according to the methods of various embodiments, as well as non-transitory computer-readable media on which such software or instructions are stored and executable on a device or computer. Instructions usable for programming a processing system to perform features described in this disclosure may be stored on or in a storage medium or computer-readable storage medium, and computer program products including such storage media may be used to embody features described in this disclosure. Storage media may include high-speed random access memory such as DRAM, SRAM, DDR RAM, or other random access solid-state memory devices, but are not limited to, non-volatile memory such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state storage devices. Memory optionally includes one or more storage devices located remotely from the processor. Memory, or alternatively, non-volatile memory devices within memory, comprise non-transitory computer-readable storage media. The features described in this disclosure may be embodied in software and / or firmware stored on any one of a number of machine-readable media and capable of controlling the hardware of a processing system and allowing the processing system to interact with other mechanisms that utilize the results of embodiments of the present disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers. [Industrial Applicability]

[0340] 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 for communicating by a first station (STA) in a wireless LAN system, comprising: performing a restricted target wake time (r-TWT) membership setup procedure with a second STA; receiving r-TWT schedule information included in a broadcast TWT element from the second STA; The method includes: terminating the first transmission opportunity (TXOP) before a start time of the r-TWT SP based on the fact that a specific portion of the first TXOP (transmission opportunity) within the r-TWT SP (service period) announced by the r-TWT schedule information is not used to transmit a DL frame corresponding to at least one r-TWT downlink (DL) traffic identifier (TID) or to request a UL frame corresponding to at least one r-TWT uplink (UL) TID.

2. 2. The method of claim 1, wherein the first TXOP does not end even after a start time of the r-TWT SP based on the fact that a specific portion of the first TXOP is used to transmit a DL frame corresponding to the at least one r-TWT DL TID or to request a UL frame corresponding to the at least one r-TWT UL TID.

3. The method of claim 1 , wherein the at least one r-TWT DL TID or the at least one r-TWT UL TID is configured by the first STA and the second STA.

4. The method of claim 1 , wherein the second STA is a holder of the first TXOP.

5. The method of claim 1 , wherein the second TXOP ends before the start time of the r-TWT SP based on the first STA being a holder of the second TXOP.

6. The method of claim 1 , wherein the r-TWT schedule information is received from the second STA in a beacon frame or a probe response frame.

7. The method of claim 2 , wherein the end time of the r-TWT SP is postponed based on the first TXOP not ending after the start time of the r-TWT SP.

8. The method of claim 1 , wherein the first STA is a non-AP (access point) EHT (extremely high throughput) STA, and the second STA is an AP.

9. A first station (STA) that communicates in a wireless LAN system, the STA comprising: one or more transceivers; one or more processors coupled to the one or more transceivers; The one or more processors: performing a restricted target wake time (r-TWT) membership setup procedure with the second STA; configured to receive r-TWT schedule information included in a broadcast TWT element from the second STA via the one or more transceivers; A first STA, based on the fact that a specific portion of a first TXOP (transmission opportunity) within an r-TWT SP (service period) announced by the r-TWT schedule information is not used to transmit a DL frame corresponding to at least one r-TWT downlink (DL) traffic identifier (TID) or to request a UL frame corresponding to at least one r-TWT uplink (UL) TID, the first TXOP ends before the start time of the r-TWT SP.

10. 1. A method for communicating by a second station (STA) in a wireless LAN system, the method comprising: performing a restricted target wake time (r-TWT) membership setup procedure with the first STA; transmitting the r-TWT schedule information included in a broadcast TWT element to the first STA; The method includes: terminating the first transmission opportunity (TXOP) before a start time of the r-TWT SP based on the fact that a specific portion of the first TXOP (transmission opportunity) within the r-TWT SP (service period) announced by the r-TWT schedule information is not used to transmit a DL frame corresponding to at least one r-TWT downlink (DL) traffic identifier (TID) or to request a UL frame corresponding to at least one r-TWT uplink (UL) TID.

11. A second station (STA) that communicates in a wireless LAN system, the second STA comprising: one or more transceivers; one or more processors coupled to the one or more transceivers; The one or more processors: performing a restricted target wake time (r-TWT) membership setup procedure with the first STA; The r-TWT schedule information included in a broadcast TWT element is transmitted to a first STA via the one or more transceivers; A second STA, based on the fact that a specific portion of a first TXOP (transmission opportunity) within the r-TWT SP (service period) announced by the r-TWT schedule information is not used to transmit a DL frame corresponding to at least one r-TWT downlink (DL) traffic identifier (TID) or to request a UL frame corresponding to at least one r-TWT uplink (UL) TID, the first TXOP ends before the start time of the r-TWT SP.

12. 1. A processing device configured to control a first station (STA) for communication in a wireless LAN system, the processing device comprising: one or more processors; one or more computer memories operably coupled to the one or more processors and storing instructions that perform operations based on being executed by the one or more processors; The operation is performing a restricted target wake time (r-TWT) membership setup procedure with the second STA; receiving r-TWT schedule information included in a broadcast TWT element from a second STA; A processing device, in which the first TXOP (transmission opportunity) within the r-TWT SP (service period) announced by the r-TWT schedule information is terminated before the start time of the r-TWT SP based on the fact that a specific portion of the first TXOP (transmission opportunity) within the r-TWT SP (service period) announced by the r-TWT schedule information is not used to transmit a DL frame corresponding to at least one r-TWT downlink (DL) traffic identifier (TID) or to request a UL frame corresponding to at least one r-TWT uplink (UL) TID.

13. 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, and a first station (STA) that communicates in a wireless LAN system: performing a restricted target wake time (r-TWT) membership setup procedure with the second STA; The STA is configured to receive r-TWT schedule information included in a broadcast TWT element from a second STA; The computer-readable medium further includes: a first transmission opportunity (TXOP) within an r-TWT service period (SP) announced by the r-TWT schedule information, the first TXOP ending before a start time of the r-TWT SP based on the fact that a specific portion of the first TXOP within the r-TWT SP is not used to transmit a DL frame corresponding to at least one r-TWT downlink (DL) traffic identifier (TID) or to request a UL frame corresponding to at least one r-TWT uplink (UL) TID.

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