Method and device for performing channel access operation in wireless LAN system

Abstract

Disclosed are a method and a device for operation in a wireless LAN system. The method according to an embodiment of the present disclosure may comprise the steps of: receiving, by a first station (STA) from a second STA, a first frame including at least one first parameter related to latency-sensitive traffic transmission; transmitting, by the first STA, a first signal related to first latency-sensitive traffic to the second STA in a first unit time among a plurality of unit times on the basis of the at least one first parameter, wherein an AIFS is divided into the plurality of unit times; and on the basis that a second signal of a third STA is transmitted to the second STA in the first unit time, performing, by the first STA, a first back-off procedure after the AIFS.

Description

Method and device for performing channel access operation in a wireless LAN system

[0001] The present disclosure relates to channel access operations in a wireless local area network (WLAN) system, and more particularly, to a method and device for performing channel access operations for low-latency traffic in a next-generation wireless LAN system.

[0002] New technologies have been introduced for wireless local area networks (WLANs) to improve transmission rates, increase bandwidth, enhance 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. For example, recently introduced technologies for 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 advanced wireless communication environment, improved technologies for Extremely High Throughput (EHT) are being discussed. For example, technologies for Multiple Input Multiple Output (MIMO), which supports increased bandwidth, efficient utilization of multiple bands, and increased spatial streams, and for coordination of multiple access points (APs), are being studied. In particular, various technologies are being studied to support low latency or real-time traffic. Furthermore, new technologies are being discussed to support ultra-high reliability (UHR), including improvements or extensions of EHT technology.

[0004] The technical problem of the present disclosure is to provide a method and device for performing channel access operation for low-latency traffic in a wireless LAN system.

[0005] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0006] A method according to one embodiment of the present disclosure may include: receiving, by a first station (STA), from a second STA, a first frame including at least one first parameter related to transmission of delay-sensitive traffic; transmitting, by the first STA, a first signal related to first delay-sensitive traffic to the second STA at a first unit of time among a plurality of unit times based on the at least one first parameter, wherein an arbitration inter-frame space (AIFS) is divided into the plurality of unit times; and performing, by the first STA, a first back-off procedure after the AIFS based on a second signal of a third STA being transmitted to the second STA at the first unit of time.

[0007] According to another embodiment of the present disclosure, a method comprises the steps of: transmitting, by a second station (STA), to a first STA, a first frame including at least one first parameter related to transmission of delay-sensitive traffic; and receiving, by the second STA, from the first STA, a first signal related to the first delay-sensitive traffic at a first unit of time among a plurality of unit times based on the at least one first parameter, wherein an arbitration inter-frame space (AIFS) is divided into the plurality of unit times, and a first back-off procedure can be performed after the AIFS based on the reception of a second signal of a third STA at the first unit of time.

[0008] According to various embodiments of the present disclosure, a method and device for performing channel access operation for low-latency traffic in a wireless LAN system can be provided.

[0009] According to various embodiments of the present disclosure, resources and / or channel access opportunities can be efficiently distributed to each of the STAs requiring low-latency traffic transmission.

[0010] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the description below.

[0011] The accompanying drawings, which are incorporated in and are part of the detailed description to aid in understanding the present disclosure, provide embodiments of the present disclosure and, together with the detailed description, describe the technical features of the present disclosure.

[0012] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

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

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

[0015] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0016] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0017] FIG. 6 is a drawing for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0018] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0019] FIG. 8 is a flowchart illustrating a method performed by a first STA according to one embodiment of the present disclosure.

[0020] FIG. 9 is a flowchart illustrating a method performed by a second STA according to one embodiment of the present disclosure.

[0021] FIG. 10 is a diagram for explaining a short signal transmission procedure according to one embodiment of the present disclosure.

[0022] FIG. 11 is a diagram illustrating a method for performing a channel access procedure according to one embodiment of the present disclosure.

[0023] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description set forth below, together with the accompanying drawings, is intended to explain exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure may be practiced. The following detailed description includes specific details to provide a thorough understanding of the present disclosure. However, one of ordinary skill in the art will appreciate that the present disclosure may be practiced without these specific details.

[0024] In some cases, to avoid obscuring the concepts of the present disclosure, known structures and devices may be omitted or illustrated in block diagram form focusing on the core functions of each structure and device.

[0025] In the present disclosure, when a component is said to be "connected," "coupled," or "connected" to another component, this may include not only a direct connection but also an indirect connection in which another component exists between them. Furthermore, the terms "comprises" or "has" in the present disclosure specify the presence of the mentioned 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.

[0026] In this disclosure, terms such as “first,” “second,” etc. 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 between the components unless specifically stated otherwise. Accordingly, 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.

[0027] The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "and / or" as used herein may refer to any one of the associated enumerated items, or is meant to refer to and encompass any and all possible combinations of two or more of them. Furthermore, the use of " / " between words in this disclosure has the same meaning as "and / or" unless otherwise stated.

[0028] The examples of the present disclosure can be applied to various wireless communication systems. For example, the examples of the present disclosure can be applied to a wireless LAN system. For example, the examples of the present disclosure can be applied to a wireless LAN based on the IEEE 802.11a / g / n / ac / ax / be standards. Furthermore, the examples of the present disclosure can be applied to a wireless LAN based on the newly proposed IEEE 802.11bn (or UHR) standard. Additionally, the examples of the present disclosure can be applied to a wireless LAN based on the next-generation standard after IEEE 802.11bn. Furthermore, the examples of the present disclosure can be applied to a cellular wireless communication system. For example, the examples of the present disclosure can be applied to a cellular wireless communication system based on the LTE (Long Term Evolution) series of technologies and the 5G NR (New Radio) series of technologies of the 3rd Generation Partnership Project (3GPP) standard.

[0029] Below, technical features to which examples of the present disclosure can be applied are described.

[0030] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0031] The first device (100) and the second device (200) illustrated in FIG. 1 may be replaced with various terms such as a terminal, a wireless device, a WTRU (Wireless Transmit Receive Unit), a UE (User Equipment), an MS (Mobile Station), a UT (user terminal), an MSS (Mobile Subscriber Station), an MSS (Mobile Subscriber Unit), an SS (Subscriber Station), an AMS (Advanced Mobile Station), a WT (Wireless terminal), or simply a user. In addition, the first device (100) and the second device (200) may be replaced with various terms such as an access point (AP), a BS (Base Station), a fixed station, a Node B, a BTS (Base Transceiver System), a network, an AI (Artificial Intelligence) system, an RSU (road side unit), a repeater, a router, a relay, a gateway, etc.

[0032] The devices (100, 200) illustrated in FIG. 1 may also be referred to as stations (STAs). For example, the devices (100, 200) illustrated in FIG. 1 may be referred to by various terms such as transmitting device, receiving device, transmitting STA, and receiving STA. For example, the STAs (110, 200) may perform an AP (access point) role or a non-AP role. That is, in the present disclosure, the STAs (110, 200) may perform the functions of an AP and / or a non-AP. When the STAs (110, 200) perform an AP function, they may simply be referred to as APs, and when the STAs (110, 200) perform a non-AP function, they may simply be referred to as STAs. In addition, in the present disclosure, the APs may also be referred to as AP STAs.

[0033] Referring to FIG. 1, the first device (100) and the second device (200) can transmit and receive wireless signals through various wireless LAN technologies (e.g., IEEE 802.11 series). The first device (100) and the second device (200) can include interfaces for a medium access control (MAC) layer and a physical layer (PHY) that follow the provisions of the IEEE 802.11 standard.

[0034] In addition, the first device (100) and the second device (200) may additionally support various communication standards (e.g., 3GPP LTE series, 5G NR series standards, etc.) other than wireless LAN technology. In addition, the device of the present disclosure may be implemented as various devices such as a mobile phone, a vehicle, a personal computer, an AR (Augmented Reality) device, a VR (Virtual Reality) device, etc. In addition, the STA of the present specification may support various communication services such as voice calls, video calls, data communications, autonomous driving, MTC (Machine-Type Communication), M2M (Machine-to-Machine), D2D (Device-to-Device), and IoT (Internet-of-Things).

[0035] A first device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memories (104) and / or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (102) may process information in the memories (104) to generate first information / signals, and then transmit a wireless signal including the first information / signals via the transceivers (106). Furthermore, the processor (102) may receive a wireless signal including second information / signals via the transceivers (106), and then store information obtained from signal processing of the second information / signals in the memory (104). The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software code including instructions for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (102) and the memory (104) may be part of a communication modem / circuit / chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series). The transceiver (106) may be connected 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 the present disclosure, a device may also mean a communication modem / circuit / chip.

[0036] The second device (200) includes one or more processors (202), one or more memories (204), and may further include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memories (204) and / or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (202) may process information in the memory (204) to generate third information / signals, and then transmit a wireless signal including the third information / signals via the transceivers (206). Furthermore, the processor (202) may receive a wireless signal including fourth information / signals via the transceivers (206), and then store information obtained from signal processing of the fourth information / signals in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software code including instructions for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present disclosure, a device may also mean a communication modem / circuit / chip.

[0037] Hereinafter, the hardware elements of the device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed in the present disclosure, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed in the present disclosure.

[0038] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The descriptions, functions, procedures, proposals, 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. The descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed in this disclosure may be implemented using firmware or software configured to perform one or more processors (102, 202) or stored in one or more memories (104, 204) and driven by one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed in this disclosure may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions.

[0039] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as 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 internally and / or externally 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 technologies, such as wired or wireless connections.

[0040] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or flowcharts of the present disclosure, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or flowcharts of the present disclosure, from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, 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. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, or the like, as referred to in the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure, via one or more antennas (108, 208). In the present disclosure, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202).One or more transceivers (106, 206) may convert user data, control information, wireless signals / channels, etc. processed by one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or filter.

[0041] For example, one of the STAs (100, 200) may perform the intended operation of an AP, and the other of the STAs (100, 200) may perform the intended operation of a non-AP STA. For example, the transceivers (106, 206) of FIG. 1 may perform transmission and reception operations of signals (e.g., packets or PPDUs (Physical layer Protocol Data Units) according to IEEE 802.11a / b / g / n / ac / ax / be / bn, etc.). In addition, in the present disclosure, operations in which various STAs generate transmission and reception signals or perform data processing or calculations in advance for transmission and reception signals may be performed in the processors (102, 202) of FIG. 1. For example, an example of an operation for generating a transmission / reception signal or performing data processing or operation in advance for a transmission / reception signal may include 1) an operation for determining / obtaining / configuring / computing / decoding / encoding bit information of a field (SIG (signal), STF (short training field), LTF (long training field), Data, etc.) included in a PPDU, 2) an operation for determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) used for a field (SIG, STF, LTF, Data, etc.) included in a PPDU, 3) an operation for determining / configuring / obtaining a specific sequence (e.g., a pilot sequence, an STF / LTF sequence, an extra sequence applied to SIG) used for a field (SIG, STF, LTF, Data, etc.) included in a PPDU, 4) a power control operation and / or a power saving operation applied to an STA, 5) an operation related to determining / obtaining / configuring / computing / decoding / encoding an ACK signal, etc. Additionally, in the examples below, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs for determining / acquiring / configuring / computing / decoding / encoding transmission / reception signals can be stored in the memory (104, 204) of FIG. 1.

[0042] Hereinafter, downlink (DL) refers to a link for communication from an AP STA to a non-AP STA, and downlink PPDUs / packets / signals, etc. can be transmitted and received through the downlink. In downlink communication, the transmitter may be part of an AP STA, and the receiver may be part of a non-AP STA. Uplink (UL) refers to a link for communication from a non-AP STA to an AP STA, and uplink PPDUs / packets / signals, etc. can be transmitted and received through the uplink. In uplink communication, the transmitter may be part of a non-AP STA, and the receiver may be part of an AP STA.

[0043] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0044] The structure of a wireless LAN system can be composed of multiple components. Through the interaction of multiple components, a wireless LAN that supports transparent STA mobility to the upper layer can be provided. A Basic Service Set (BSS) corresponds to a basic building block of a wireless LAN. FIG. 2 illustrates, by way of example, the existence of two BSSs (BSS1 and BSS2) and the inclusion of two STAs as members of each BSS (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2). The oval representing a BSS in FIG. 2 can also be understood as representing a coverage area in which STAs included in the corresponding BSS maintain communication. This area can be referred to as a Basic Service Area (BSA). When an STA moves outside of a BSA, it cannot directly communicate with other STAs within the BSA.

[0045] If we do not consider the DS illustrated in Figure 2, the most basic type of BSS in a wireless LAN is an Independent BSS (IBSS). For example, an IBSS can have a minimal form consisting of only two STAs. For example, assuming other components are omitted, BSS1 consisting of only STA1 and STA2, or BSS2 consisting of only STA3 and STA4, can be representative examples of an IBSS, respectively. Such a configuration is possible when the STAs can communicate directly without an AP. Furthermore, in this type of WLAN, a LAN can be configured when needed rather than being planned in advance, and this can 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 IBSS, all STAs can be mobile STAs, and access to distributed systems (DS) is not permitted, forming a self-contained network.

[0046] An STA's membership in a BSS can dynamically change, for example, when an STA is turned on or off, or when an STA enters or leaves a BSS area. To become a member of a BSS, an STA can join the BSS using a synchronization process. To access all services in the BSS infrastructure, an STA must be associated with the BSS. This association can be dynamically established and may involve the use of a Distribution System Service (DSS).

[0047] In a wireless LAN, the direct STA-to-STA distance can be limited by PHY performance. While this distance limit may be sufficient in some cases, communication between STAs over longer distances may be required in other cases. To support extended coverage, a distributed system (DS) can be configured.

[0048] DS refers to a structure in which BSSs are interconnected. Specifically, a BSS may exist as an extended component of a network composed of multiple BSSs, as illustrated in Figure 2. DS is a logical concept and can be specified by the characteristics of a distributed system medium (DSM). In this regard, the Wireless Medium (WM) and DSM can be logically distinguished. Each logical medium is used for a different purpose and by different components. These media are neither limited to being identical nor limited to being different. This logical difference between multiple media explains the flexibility of the WLAN architecture (DS architecture or other network architectures). In other words, the WLAN architecture can be implemented in various ways, and the physical characteristics of each implementation can independently specify the WLAN architecture.

[0049] A DS can support mobile devices by providing seamless integration of multiple BSSs and the logical services necessary to handle addresses to destinations. Additionally, a DS may further include a component called a portal, which acts as a bridge for connecting wireless LANs to other networks (e.g., IEEE 802.X).

[0050] An AP is an entity that enables access to a DS through a WM for associated non-AP STAs and also has the functionality of an STA. Data movement between a BSS and a DS can be performed through an AP. For example, STA2 and STA3 illustrated 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. In addition, since all APs are basically STAs, all APs are addressable entities. The address used by an AP for communication on a WM and the address used by an AP for communication on a DSM do not necessarily have to be the same. A BSS consisting of an AP and one or more STAs can be referred to as an infrastructure BSS.

[0051] Data transmitted from one of the STA(s) associated with an AP to the STA address of that AP may always be received on an uncontrolled port and processed by an IEEE 802.1X port access entity. In addition, if the controlled port is authenticated, the transmitted data (or frame) may be forwarded to the DS.

[0052] In addition to the structure of the DS described above, an extended service set (ESS) may be established to provide wider coverage.

[0053] An ESS is a network of arbitrary size and complexity, consisting of DSs and BSSs. An ESS may correspond to a set of BSSs connected to a 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 within 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 within an ESS may have the same SSID (service set identification). The SSID is distinct from the BSSID, which is the identifier of the BSS.

[0054] In a wireless LAN system, no assumptions are made about the relative physical locations of BSSs, and all of the following configurations are possible: BSSs can be partially overlapping, which is commonly used to provide continuous coverage. BSSs can also be physically disconnected, and there is no logical distance limit between them. BSSs can also be physically co-located, which can be used to provide redundancy. Furthermore, one (or more) IBSS or ESS networks can physically co-exist with one (or more) ESS networks. This can occur in cases where an ad-hoc network operates at the same location as an ESS network, where physically overlapping wireless networks are configured by different organizations, or where two or more different access and security policies are required at the same location.

[0055] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0056] For an STA to set up a link and transmit and receive data on a network, it must first discover the network, perform authentication, establish an association, and complete security authentication procedures. The link setup process can also be referred to as the session initiation process or session setup process. Furthermore, the discovery, authentication, association, and security setup processes of the link setup process can be collectively referred to as the association process.

[0057] In step S310, the STA may perform a network discovery operation. This network discovery operation may include scanning operations by the STA. That is, for the STA to access a network, it must search for available networks. Before joining a wireless network, the STA must identify compatible networks. The process of identifying networks in a specific area is called scanning.

[0058] Scanning methods include active scanning and passive scanning. Figure 3 illustrates a network discovery operation including an active scanning process as an example. In active scanning, an STA performing scanning transmits a probe request frame to discover any APs in the vicinity while moving between channels and waits for a response. The responder transmits a probe response frame in response to the STA that transmitted 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 the BSS, the AP transmits the beacon frame, so the AP becomes the responder. In the IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not fixed. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning (i.e., transmitting and receiving probe requests / responses on channel 2) in the same manner.

[0059] Although not shown in Figure 3, the scanning operation can also be performed in a passive scanning manner. In passive scanning, the STA performing the scanning moves between channels and waits for a beacon frame. A beacon frame is one of the management frames defined in IEEE 802.11. It announces the existence of a wireless network and is periodically transmitted so that the STA performing the scanning can find the wireless network and participate in the wireless network. In the BSS, the AP performs the role of periodically transmitting the beacon frame, and in the IBSS, the STAs within the IBSS take turns transmitting the beacon frame. When the STA performing the scanning receives a beacon frame, it stores the information about the BSS included in the beacon frame and moves to another channel, recording the beacon frame information on each channel. The STA receiving the beacon frame stores the BSS-related information included in the received beacon frame and moves to the next channel to perform scanning on the next channel in the same manner. Comparing active scanning and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.

[0060] After the STA discovers the network, an authentication process may be performed in step S320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation of step S340 described below.

[0061] The authentication process involves the STA sending an authentication request frame to the 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.

[0062] The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), and a Finite Cyclic Group. These are just some examples of information that may be included in an authentication request / response frame, and may be replaced with other information or include additional information.

[0063] An STA can send an authentication request frame to an AP. The AP can determine whether to grant authentication to the STA based on the information contained in the received authentication request frame. The AP can provide the result of the authentication process to the STA via an authentication response frame.

[0064] After the STA is successfully authenticated, an association process may be performed in step S330. The association process includes a process in which the STA transmits an association request frame to the AP, and in response, the AP transmits an association response frame to the STA.

[0065] For example, the association request frame may include information about 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 about 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. These are just some examples of information that may be included in a combined request / response frame, and may be replaced by other information or include additional information.

[0066] After the STA successfully joins the network, a security setup process may be performed in step S340. The security setup process in step S340 may be referred to as an authentication process through a Robust Security Network Association (RSNA) request / response, the authentication process in step S320 may be referred to as a first authentication process, and the security setup process in step S340 may also be referred to simply as an authentication process.

[0067] The security setup process of step S340 may include, for example, a process of establishing a private key through a four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame. Furthermore, the security setup process may be performed according to a security method not defined in the IEEE 802.11 standard.

[0068] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0069] In wireless LAN systems, the basic access mechanism of MAC (Medium Access Control) is Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). The CSMA / CA mechanism, also known as the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC, essentially employs a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or STA may perform a Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time period (e.g., a DCF Inter-Frame Space (DIFS)) before starting transmission. If the sensing result determines that the medium is in an idle state, the AP and / or STA may start transmitting frames through the medium. On the other hand, if the medium is detected to be occupied or busy, the AP and / or STA may not start its own transmission, but may wait for a delay period (e.g., a random backoff period) for medium access before attempting to transmit frames. By applying a random backoff period, multiple STAs are expected to attempt to transmit frames after waiting for different periods of time, thereby minimizing collisions.

[0070] In addition, the IEEE 802.11 MAC protocol provides the Hybrid Coordination Function (HCF). The HCF is based on the DCF and the Point Coordination Function (PCF). The PCF is a polling-based synchronous access method that periodically polls all receiving APs and / or STAs to ensure that they receive data frames. In addition, the HCF has the Enhanced Distributed Channel Access (EDCA) and the HCF Controlled Channel Access (HCCA). The EDCA is a contention-based access method for a provider to provide data frames to multiple users, while the HCCA uses a non-contention-based channel access method that utilizes a polling mechanism. In addition, the HCF includes a medium access mechanism to improve the Quality of Service (QoS) of the wireless LAN, and can transmit QoS data in both the Contention Period (CP) and the Contention Free Period (CFP).

[0071] Referring to Fig. 4, an operation based on a random backoff period is described. When a medium that was occupied / busy changes to an idle state, multiple STAs can attempt to transmit data (or frames). To minimize collisions, each STA can select a random backoff count, wait for the corresponding slot time, and then attempt transmission. The random backoff count has a pseudo-random integer value and can be determined as one of the values ​​in the range of 0 to CW. Here, CW is a contention window parameter value. The CW parameter is given an initial value of CWmin, but can take a doubled value in case of transmission failure (e.g., when an ACK for a transmitted frame is not received). When the CW parameter value becomes 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 2. n It is desirable to set it to -1 (n=0, 1, 2, ...).

[0072] Once the random backoff process begins, the STA continues to monitor the medium while counting down the backoff slots according to the determined backoff count value. If the medium is monitored as occupied, the countdown stops and waits. When the medium becomes idle, the remaining countdown resumes.

[0073] In the example of FIG. 4, when a packet to be transmitted reaches the MAC of STA3, STA3 can immediately transmit a frame if it confirms that the medium is idle for DIFS. The remaining STAs monitor the medium for occupied / busy states and wait. In the meantime, data to be transmitted may also occur in each of STA1, STA2, and STA5, and each STA can count down the backoff slot according to a random backoff count value selected by each STA after waiting for DIFS if the medium is monitored as idle. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. In other words, this example shows a case where the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1 when STA2 finishes the backoff count and starts frame transmission. STA1 and STA5 briefly stop counting down 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 the backoff count that they had stopped. That is, they can start transmitting frames after counting down the remaining backoff slots equal to the remaining backoff time. Since STA5's remaining backoff time is shorter than STA1's, STA5 starts transmitting frames. While STA2 occupies the medium, STA4 may also have data to transmit. From STA4's perspective, when the medium becomes idle, it waits for DIFS, counts down according to its selected random backoff count value, and then starts transmitting frames. In the example of Figure 4, the remaining backoff time of STA5 coincidentally matches the random backoff count value of STA4, in which case a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 will receive an ACK, resulting in a failure in data transmission.In this case, STA4 and STA5 can select a random backoff count value and perform a countdown after doubling the CW value. STA1 waits while the medium is occupied by transmissions from STA4 and STA5, and when the medium becomes idle, it waits for DIFS and can start transmitting frames after the remaining backoff time elapses.

[0074] As in the example of Fig. 4, a data frame is a frame used for transmitting data forwarded to a higher layer, and can be transmitted after a backoff performed after DIFS elapses from when the medium becomes idle. Additionally, a management frame is a frame used for exchanging management information that is not forwarded to a higher layer, and is transmitted after a backoff performed after an IFS elapses, such as DIFS or PIFS (Point coordination function IFS). Subtype frames of a management frame include a beacon, an association request / response, a re-association request / response, a probe request / response, and an authentication request / response. A control frame is a frame used to control access to the medium. The subtype frames of the control frame include Request-To-Send (RTS), Clear-To-Send (CTS), Acknowledgment (ACK), Power Save-Poll (PS-Poll), Block ACK (BlockAck), Block ACK Request (BlockACKReq), Null Data Packet Announcement (NDP), and Trigger. If the control frame is not a response frame to the previous frame, it is transmitted after a backoff performed after the DIFS (Direct Inverse Frame Stop) has elapsed, and if it is a response frame to the previous frame, it is transmitted without a backoff performed after the SIFS (short IFS). The type and subtype of the frame can be identified by the type field and subtype field in the Frame Control (FC) field.

[0075] A QoS (Quality of Service) STA can transmit a frame after a backoff performed after the AIFS (arbitration IFS) 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, the frames for which AIFS[i] can be used can be data frames, management frames, and also control frames that are not response frames.

[0076] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0077] As mentioned above, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, in which STAs directly sense the medium. Virtual carrier sensing is intended to address potential issues in medium access, such as the hidden node problem. For virtual carrier sensing, the MAC of an STA can utilize a Network Allocation Vector (NAV). The NAV is a value that an STA that is currently using or has the right to use the medium indicates to other STAs the remaining time until the medium becomes available. Therefore, the value set as NAV corresponds to the period during which the STA transmitting the frame is scheduled to use the medium, and an STA receiving the NAV value is prohibited from accessing the medium during that period. For example, the NAV can be set based on the value of the "duration" field in the MAC header of the frame.

[0078] In the example of FIG. 5, it is assumed that STA1 wants to transmit data to STA2, and STA3 is in a position to overhear some or all of the frames transmitted and received between STA1 and STA2.

[0079] In order to reduce the possibility of collisions in transmissions of multiple STAs in a CSMA / CA-based frame transmission operation, a mechanism using RTS / CTS frames may be applied. In the example of FIG. 5, while STA1 is transmitting, STA3 may determine that the medium is idle based on carrier sensing results. That is, STA1 may correspond to a hidden node for STA3. Alternatively, in the example of FIG. 5, while STA2 is transmitting, STA3 may determine that the medium is idle based on carrier sensing results. That is, STA2 may correspond to a hidden node for STA3. By exchanging RTS / CTS frames before performing data transmission and reception between STA1 and STA2, STAs outside the transmission range of either STA1 or STA2, or STAs outside the carrier sensing range for transmissions from STA1 or STA3, may not attempt to occupy the channel during data transmission and reception between STA1 and STA2.

[0080] Specifically, STA1 can determine whether a channel is occupied through carrier sensing. In terms of physical carrier sensing, STA1 can determine channel occupancy idleness based on the energy level or signal correlation detected in the channel. Furthermore, in terms of virtual carrier sensing, STA1 can determine the channel occupancy status using a network allocation vector (NAV) timer.

[0081] STA1 can transmit an RTS frame to STA2 after performing a backoff if the channel is idle during the DIFS. STA2 can transmit a CTS frame, which is a response to the RTS frame, to STA1 after an SIFS if it receives the RTS frame.

[0082] If STA3 cannot overhear a CTS frame from STA2 but can overhear an RTS frame from STA1, STA3 can use the duration information contained in the RTS frame to set a NAV timer for the subsequent consecutively transmitted frame transmission period (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame). Alternatively, if STA3 cannot overhear an RTS frame from STA1 but can overhear a CTS frame from STA2, STA3 can use the duration information contained in the CTS frame to set a NAV timer for the subsequent consecutively transmitted frame transmission period (e.g., SIFS + data frame + SIFS + ACK frame). That is, if STA3 can overhear one or more of the RTS or CTS frames from one or more of STA1 or STA2, it can set a NAV accordingly. If STA3 receives a new frame before the NAV timer expires, it can update the NAV timer using the duration information contained in the new frame. STA3 does not attempt channel access until the NAV timer expires.

[0083] If STA1 receives a CTS frame from STA2, it can transmit a data frame to STA2 after SIFS from the time when the CTS frame is completely received. If STA2 successfully receives the data frame, it can transmit an ACK frame in response to the data frame to STA1 after SIFS. STA3 can determine whether the channel is in use through carrier sensing if the NAV timer expires. If STA3 determines that the channel is not in use by another terminal during the DIFS after the NAV timer expires, it can attempt channel access after a contention window (CW) based on a random backoff has elapsed.

[0084] FIG. 6 is a drawing for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0085] 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 a command requesting the start of transmission of the PHY layer is received from the MAC layer, the PHY layer can switch to transmission mode and transmit the 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 of the received frame, it monitors the header of the preamble and sends a command to the MAC layer notifying the start of reception of the PHY layer.

[0086] In this way, information transmission / reception in a wireless LAN system is done in the form of frames, and for this purpose, the PHY layer Protocol Data Unit (PPDU) format is defined.

[0087] A basic PPDU 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-HT (High Throughput) as illustrated in FIG. 7) PPDU format may consist of only the Legacy-STF (L-STF), Legacy-LTF (L-LTF), Legacy-SIG (L-SIG) fields, and a Data field. Additionally, depending on the type of PPDU format (e.g., HT-mixed format PPDU, HT-greenfield format PPDU, VHT (Very High Throughput) PPDU, etc.), additional (or different types of) RL-SIG, U-SIG, non-legacy SIG field, non-legacy STF, non-legacy LTF, (i.e., xx-SIG, xx-STF, xx-LTF (e.g., xx is HT, VHT, HE, EHT, etc.)) may be included between the L-SIG field and the data field. More specific details will be described later with reference to FIG. 7.

[0088] STF is a signal for signal detection, AGC (Automatic Gain Control), diversity selection, and precise time synchronization, while LTF is a signal for channel estimation, frequency error estimation, etc. STF and LTF can be said to be signals for synchronization and channel estimation of the OFDM physical layer.

[0089] The SIG field may include various information related to PPDU transmission and reception. For example, the L-SIG field may consist of 24 bits and 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. The RATE field may include information about the modulation and coding rate of data. For example, the 12-bit Length field may include information about 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 the 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 HE PPDU, the value of the Length field can be determined as a multiple of 3 + 1 or a multiple of 3 + 2.

[0090] The data field may include a SERVICE field, a Physical layer Service Data Unit (PSDU), a PPDU TAIL bit, and, if necessary, padding bits. Some bits of the SERVICE field may be used to synchronize the descrambler at the receiving end. The PSDU corresponds to a MAC PDU defined at the MAC layer and may contain data generated / used by upper layers. The PPDU TAIL bit may be used to return the encoder to a 0 state. The padding bit may be used to adjust the length of the data field to a predetermined unit.

[0091] MAC PDUs are defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a Frame Check Sequence (FCS). A MAC frame is composed of MAC PDUs and can be transmitted / received through the PSDU in the data portion of the PPDU format.

[0092] 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 a time for transmitting the corresponding frame, etc. The Address subfields may indicate the receiver address, transmitter address, destination address, and source address of the frame, and some Address subfields may be omitted. For specific details of each subfield of the MAC header, including the Sequence Control, QoS Control, and HT Control subfields, refer to the IEEE 802.11 standard document.

[0093] The Null-Data PPDU (NDP) format refers to a PPDU format that does not include a data field. In other words, NDP refers to a frame format that includes a PPDU preamble (i.e., L-STF, L-LTF, L-SIG fields, and, if additionally present, non-legacy SIG, non-legacy STF, and non-legacy LTF) in the general PPDU format, and does not include the remaining part (i.e., data field).

[0094] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0095] Standards such as IEEE 802.11a / g / n / ac / ax use various PPDU formats. The basic PPDU format (IEEE 802.11a / g) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format can also be referred to as the non-HT PPDU format (Fig. 7(a)).

[0096] The HT PPDU format (IEEE 802.11n) additionally includes HT-SIG, HT-STF, and HT-LFT(s) fields in addition to the basic PPDU format. The HT PPDU format illustrated in Fig. 7(b) may be referred to as an HT-mixed format. Additionally, an HT-greenfield format PPDU may be defined, which corresponds to a format that does not include L-STF, L-LTF, and L-SIG, but consists of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTF, and Data fields (not illustrated).

[0097] An example of the VHT PPDU format (IEEE 802.11ac) includes VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format (Fig. 7(c)).

[0098] An example of a HE PPDU format (IEEE 802.11ax) additionally includes RL-SIG (Repeated L-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and PE (Packet Extension) fields in addition to the basic PPDU format (Fig. 7(d)). Depending on specific examples 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 multi-users (MUs), but the HE PPDU format for single users (SUs) does not include the HE-SIG-B. In addition, the HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may vary to 8us. The HE ER (Extended Range) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may vary to 16us. For example, RL-SIG can be configured identically to L-SIG. The receiving STA can determine that the received PPDU is a HE PPDU or an EHT PPDU, described later, based on the presence of RL-SIG.

[0099] The EHT PPDU format may include the EHT MU (multi-user) PPDU of FIG. 7(e) and the EHT TB (trigger-based) PPDU of FIG. 7(f). The EHT PPDU format is similar to the HE PPDU format in that it includes an RL-SIG following an L-SIG, but may include a U (universal)-SIG, an EHT-SIG, an EHT-STF, and an EHT-LTF following the RL-SIG.

[0100] The EHT MU PPDU in FIG. 7(e) corresponds to a PPDU that carries one or more data (or PSDUs) for one or more users. That is, the EHT MU PPDU can be used for both SU transmission and MU transmission. For example, the EHT MU PPDU can correspond to a PPDU for one receiving STA or multiple receiving STAs.

[0101] The EHT TB PPDU of Fig. 7(f) omits the EHT-SIG compared to the EHT MU PPDU. An STA that has received a trigger for UL MU transmission (e.g., a trigger frame or TRS (triggered response scheduling)) can perform UL transmission based on the EHT TB PPDU format.

[0102] The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated so that even legacy STAs can attempt demodulation and decoding, and can be mapped based on a predetermined subcarrier frequency interval (e.g., 312.5 kHz). These can be referred to as pre-EHT modulated fields. Next, the EHT-STF, EHT-LTF, Data, and PE fields can be encoded and modulated so that they can be demodulated and decoded by an STA that has successfully decoded a non-legacy SIG (e.g., U-SIG and / or EHT-SIG) and obtained the information contained in the corresponding field, and can be mapped based on a predetermined subcarrier frequency interval (e.g., 78.125 kHz). These can be referred to as EHT modulated fields.

[0103] Similarly, in the HE PPDU format, the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, and HE-SIG-B fields may be referred to as pre-HE modulation fields, and the HE-STF, HE-LTF, Data, and PE fields may be referred to as HE modulation fields. Additionally, in the VHT PPDU format, the L-STF, L-LTF, L-SIG, and VHT-SIG-A fields may be referred to as pre-VHT modulation fields, and the VHT STF, VHT-LTF, VHT-SIG-B, and Data fields may be referred to as VHT modulation fields.

[0104] The U-SIG included in the EHT PPDU format of FIG. 7 can be configured based on, for example, two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., OFDM symbol) for the U-SIG can have a duration of 4 us, and the U-SIG can have a total duration of 8 us. Each symbol of the U-SIG can be used to transmit 26 bits of information. For example, each symbol of the U-SIG can be transmitted and received based on 52 data tones and 4 pilot tones.

[0105] U-SIGs can be configured in 20MHz units. For example, when an 80MHz PPDU is configured, the same U-SIG can be duplicated in 20MHz units. That is, four identical U-SIGs can be included in an 80MHz PPDU. When the bandwidth exceeds 80MHz, for example, for a 160MHz PPDU, the U-SIGs in the first 80MHz unit and the U-SIGs in the second 80MHz unit can be different.

[0106] For example, A uncoded bits may be transmitted via U-SIG, and a first symbol of U-SIG (e.g., a U-SIG-1 symbol) may transmit the first X bits of information out of a total A bits of information, and a second symbol of U-SIG (e.g., a U-SIG-2 symbol) may transmit the remaining Y bits of information out of a total A bits of information. The A bits of information (e.g., 52 uncoded bits) may include a CRC field (e.g., a field of 4 bits in length) and a tail field (e.g., a field of 6 bits in length). The tail field may be used to terminate the trellis of the convolutional decoder and may be set to 0, for example.

[0107] The A bit information transmitted by U-SIG can be divided into version-independent bits and version-dependent bits. For example, U-SIG can be included in a new PPDU format (e.g., UHR PPDU format) not shown in FIG. 7, and in the format of the U-SIG field included in the EHT PPDU format and the format of the U-SIG field included in the UHR PPDU format, the version-independent bits can be the same, and some or all of the version-dependent bits can be different.

[0108] For example, the size of the version-independent bits of U-SIG can be fixed or variable. The version-independent bits can be assigned only to U-SIG-1 symbols, or to both U-SIG-1 symbols and U-SIG-2 symbols. The version-independent bits and the version-dependent bits can be called by various names, such as the first control bit and the second control bit.

[0109] For example, the version-independent bits of the U-SIG may include a 3-bit PHY version identifier, which may indicate the PHY version (e.g., EHT, UHR, etc.) of the transmitted and received PPDUs. The version-independent bits of the U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication. The version-independent bits of the U-SIG may include information about the length of a transmission opportunity (TXOP) and information about a BSS color ID.

[0110] For example, the version-dependent bits of the U-SIG may contain information that directly or indirectly indicates the type of PPDU (e.g., SU PPDU, MU PPDU, TB PPDU, etc.).

[0111] Information required for PPDU transmission and reception may be included in the U-SIG. For example, the U-SIG may further include information about bandwidth, information about the MCS technique applied to the non-legacy SIG (e.g., EHT-SIG or UHR-SIG), information indicating whether a dual carrier modulation (DCM) technique (e.g., a technique to achieve an effect similar to frequency diversity by reusing the same signal on two subcarriers) is applied to the non-legacy SIG, information about the number of symbols used for the non-legacy SIG, information about whether the non-legacy SIG is generated across the entire band, etc.

[0112] Some of the information required for transmitting and receiving a PPDU may be included in the U-SIG and / or the non-legacy SIG (e.g., EHT-SIG or UHR-SIG, etc.). For example, information about the type of the non-legacy LTF / STF (e.g., EHT-LTF / EHT-STF or UHR-LTF / UHR-STF, etc.), information about the length of the non-legacy LTF and the cyclic prefix (CP) length, information about the guard interval (GI) applicable to the non-legacy LTF, information about preamble puncturing applicable to the PPDU, information about resource unit (RU) allocation, etc. may be included only in the U-SIG, may be included only in the non-legacy SIG, or may be indicated by a combination of the information included in the U-SIG and the information included in the non-legacy SIG.

[0113] Preamble puncturing may refer to the transmission of a PPDU in which no signal is present in one or more frequency units within the PPDU's bandwidth. For example, the size of the frequency unit (or the resolution of the preamble puncturing) may be defined as 20 MHz, 40 MHz, etc. For example, preamble puncturing may be applied to a PPDU bandwidth greater than a certain size.

[0114] In the example of FIG. 7, non-legacy SIGs such as HE-SIG-B and EHT-SIG may include control information for the receiving STA. The non-legacy SIG may be transmitted over at least one symbol, and each symbol may have a length of 4 us. Information regarding the number of symbols used for the EHT-SIG may be included in a previous SIG (e.g., HE-SIG-A, U-SIG, etc.).

[0115] Non-legacy SIGs, such as HE-SIG-B and EHT-SIG, may contain common fields and user-specific fields. Common and user-specific fields may be coded separately.

[0116] In some cases, common fields may be omitted. For example, in a compressed mode where non-OFDMA (orthogonal frequency multiple access) is applied, common fields may be omitted, and multiple STAs may receive PPDUs (e.g., data fields of PPDUs) over the same frequency band. In a non-compressed mode where OFDMA is applied, multiple users may receive PPDUs (e.g., data fields of PPDUs) over different frequency bands.

[0117] The number of user-specific fields can be determined based on the number of users. A single user block field can contain up to two user fields. Each user field can be associated with either MU-MIMO allocation or non-MU-MIMO allocation.

[0118] The common field may include CRC bits and Tail bits, the length of the CRC bits may be determined as 4 bits, and the length of the Tail bits may be determined as 6 bits and set to 000000. The common field may include RU allocation information. The RU allocation information may include information about the location of RUs to which multiple users (i.e., multiple receiving STAs) are allocated.

[0119] An RU can contain multiple subcarriers (or tones). RUs can be used when transmitting signals to multiple STAs based on OFDMA techniques. RUs can also be defined when transmitting signals to a single STA. Resources can be allocated on an RU basis for non-legacy STFs, non-legacy LTFs, and data fields.

[0120] Depending on the PPDU bandwidth, an applicable RU size can be defined. The RU may be defined identically or differently for the applicable PPDU format (e.g., HE PPDU, EHT PPDU, UHR PPDU, etc.). For example, in the case of an 80MHz PPDU, the RU arrangements of HE PPDU and EHT PPDU may be different. The applicable RU size, RU number, RU position, DC (direct current) subcarrier position and number, null subcarrier position and number, guard subcarrier position and number, etc. for each PPDU bandwidth can be referred to as a tone plan. For example, a tone plan for a wide bandwidth can be defined in the form of multiple repetitions of a low bandwidth tone plan.

[0121] RUs of different sizes can be defined, such as 26-ton RU, 52-ton RU, 106-ton RU, 242-ton RU, 484-ton RU, 996-ton RU, 2X996-ton RU, 3X996-ton RU, etc. A multiple RU (MRU) is distinguished from multiple individual RUs and corresponds to a group of subcarriers consisting of multiple RUs. For example, one MRU can be defined as 52+26-tons, 106+26-tons, 484+242-tons, 996+484-tons, 996+484+242-tons, 2X996+484-tons, 3X996-tons, or 3X996+484-tons. Additionally, multiple RUs constituting one MRU may or may not be consecutive in the frequency domain.

[0122] The specific size of an RU may be reduced or expanded. Therefore, the specific size of each RU (i.e., the number of corresponding tones) in the present disclosure is not limited and is exemplary. Furthermore, within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, etc.) in the present disclosure, the number of RUs may vary depending on the RU size.

[0123] The names of each field in the PPDU formats of FIG. 7 are exemplary and the scope of the present disclosure is not limited by those names. Furthermore, the examples of the present disclosure can be applied not only to the PPDU format exemplified in FIG. 7, but also to a new PPDU format in which some fields are excluded and / or some fields are added based on the PPDU formats of FIG. 7.

[0124] Improved channel access methods

[0125] As broad frequency allocation and associated transmission technologies advance, support for services and applications requiring low-latency communications is expanding. For example, improved low-latency communications may be needed to implement augmented reality features using eXtended Reality (XR) devices.

[0126] As mentioned above, the Wi-Fi system uses unlicensed bands, so any user who meets certain requirements can use the Wi-Fi system. The Wi-Fi system can support channel access operations via the EDCA method.

[0127] The EDCA method (e.g., the EDCA method of a basic wireless LAN system) is a MAC protocol-based method introduced to support QoS, and can provide differentiated services according to the priority of traffic.

[0128] Specifically, EDCA classifies traffic by access category (AC) and supports the delay QoS required by each AC by providing differential channel access opportunities for each AC. For example, eight user priorities (UP) can be mapped to four ACs (Background (BK), Best Effort (BE), Video (VI), and Voice (VO)). In this case, the priorities for each AC can be in the order of AC_VO, AC_VI, AC_BE, and AC_BK.

[0129] Each AC may have an independent transmission queue and at least one type of parameter (e.g., AIFS[AC] and CWmin[AC] / CWmax[AC]). AIFS[AC] may correspond to a waiting time for checking the channel idle state per AC, and a lower value thereof may indicate a higher priority for the AC. CWmin[AC] / CWmax[AC] indicate a range of sizes of a contention window (e.g., a minimum length / maximum length of a contention window), and a smaller value of CWmin[AC] / CWmax[AC] may indicate an increased channel access probability for the AC. For example, when multiple ACs attempt channel access simultaneously within the same STA, an AC with a higher priority may obtain a transmission opportunity.

[0130] STA(s) may perform carrier sensing operations to determine whether the channel status is busy or idle. STA(s) that determine the channel status is idle may postpone transmission operations (or perform back-off operations) for a certain period of time before transmitting data frames. In this case, the transmission postponement period (or / and the length of the period) may be "AIFS[AC] + random back-off."

[0131] Here, AIFS[AC] can be "AIFSN[AC] * Slot Time (ST) + SIFS" time. AIFSN (Arbitration Inter-Frame Space Number) refers to a slot counter defined for each AC in EDCA. The smaller the AIFSN value, the shorter the AIFS can be, and thus the AC can access the channel faster.

[0132] And, the random back-off can be an exponential back-off. The back-off (or contention) window, from which a random number can be selected whenever a collision occurs, can increase by a power of 2. If the channel is busy, the back-off counter can be paused, and if the channel becomes idle, the back-off count can be resumed. When the back-off counter value becomes 0, the STA can acquire a TXOP and perform traffic transmission related to the corresponding AC within the TXOP. If the traffic transmission is completed, the STA can reset the length of the contention window of the corresponding AC to CWmin. If the traffic transmission fails (or a collision occurs), the STA can increase the length of the contention window of the corresponding AC by a factor of 2 up to a maximum of CWmax.

[0133] As an example of the present disclosure, traffic types by AC, CWmin, CWmax, AIFSN and AIFS(usec) can be defined as in Table 1, but are not limited thereto.

[0134] AC Traffic Type CW min CW max AIFS NAIFS [us] AC_BK Background 151023779 AC_BE Best Effort 151023343 AC_BI Video 715234 AC_VO Voice 37234

[0135] Meanwhile, STAs seeking to transmit and receive low-latency traffic (or / and applications), such as voice and video, can be provided with frequent channel access opportunities, thereby supporting their latency requirements. However, traffic requiring low latency (e.g., latency-sensitive private traffic) continues to grow, and the EDCA method to support this demand provides a limited contention window size. Consequently, frequent channel access increases the likelihood of collisions and can have adverse effects on latency.

[0136] The present disclosure relates to a method for reducing the possibility of collisions by utilizing a small contention window size in situations where a large number of STAs require low-latency traffic transmission (e.g., uplink (UL) transmission situations), in order to address the aforementioned problems. The method according to the present disclosure may be applied when an STA performs an initial transmission operation to another STA, but is not limited thereto. The method according to the present disclosure may also be applied when a retransmission operation is performed due to a collision involving an STA.

[0137] In describing this disclosure, the contention period refers to the period from the point when the channel becomes idle to the point of "AIFS + back-off." The length of the contention period may vary for each AC. Furthermore, a legacy STA may collectively refer to an STA that accesses the channel according to the EDCA method in a basic wireless LAN system.

[0138] FIG. 8 is a diagram illustrating a method performed by a first STA according to an embodiment of the present disclosure. In FIG. 8 and FIG. 9 , it is assumed that each of the first STA and the third STA is a non-access point (AP) STA, and the second STA is an AP (MLD), but the present invention is not limited thereto. Each of the first STA, the second STA, and the third STA may be either a non-AP STA (MLD) or an AP (MLD).

[0139] A first STA can receive a first frame including at least one first parameter related to delay-sensitive traffic transmission from a second STA (S810).

[0140] In describing the present disclosure, delay-sensitive traffic may mean traffic requiring low-latency transmission (or low-latency traffic). At least one first parameter related to transmission of delay-sensitive traffic may include parameter(s) related to channel access for transmission of delay-sensitive traffic. For example, the at least one first parameter may include at least one of information regarding at least one of a length of a duration of a first signal (e.g., a short signal), a contention window size value (X) for a first back-off procedure, a channel access procedure according to the number of retransmissions, or a channel access procedure according to the number of STAs in a basic service set (BSS) of a second STA.

[0141] For example, the first frame may be, but is not limited to, at least one of a beacon frame, a probe response frame, or a combination frame.

[0142] A first STA may transmit a first signal related to a first delay-sensitive traffic to a second STA at a first unit time among a plurality of unit times based on at least one first parameter (S820). Here, an arbitration inter-frame space (AIFS) may be divided into a plurality of unit times.

[0143] Specifically, the first STA may perform a channel access procedure for transmitting the first delay-sensitive traffic. As described above, when the AIFS is divided into a plurality of unit times, the first STA may select a first unit time from the plurality of unit times. Then, the first STA may transmit a first signal in the first unit time. At this time, the first signal may be a signal for notifying that the first STA has the first delay-sensitive traffic (or / and will transmit the first delay-sensitive traffic). For example, the first STA may determine the length of the section of the first signal according to at least one parameter.

[0144] Additionally, the first STA may perform a channel access procedure based on the type of channel access procedure included in at least one first parameter. In the present disclosure, the channel access procedure may include a channel access procedure based on at least one first parameter and a channel access procedure based on at least one second parameter related to enhanced distributed channel access (EDCA) (e.g., an EDCA-based channel access procedure of a basic wireless LAN system, etc.).

[0145] Here, at least one second parameter may include at least one of an AIFS number (AIFSN) or a minimum value and a maximum value of a contention window.

[0146] For example, based on the number of STAs within the BSS of the second STA exceeding a predefined value, the first frame may include information about a channel access procedure based on at least one first parameter. That is, if the number of STAs within the BSS of the second STA exceeds the predefined value, the first STA may confirm to perform a channel access procedure based on at least one first parameter through the first frame.

[0147] However, this is only one embodiment, and at least one first parameter may include information on the type of channel access procedure based on the number of retransmissions of the first STA and / or the number of STAs within the BSS of the second STA, respectively. For example, if at least one first parameter includes information on the type of channel access procedure based on the number of retransmissions of the first STA, the first STA may perform a specific type of channel access procedure depending on the number of retransmissions.

[0148] As an example of the present disclosure, step S820 assumes that the first STA performs a channel access procedure based on at least one first parameter.

[0149] Based on the second signal of the third STA being transmitted to the second STA at the first unit time, the first STA may perform the first back-off procedure after the AIFS (S830). Here, it is assumed, but not limited to, that the third STA is an STA included in the BSS of the second STA (e.g., an STA associated with the second STA).

[0150] For example, if a third STA transmits a second signal related to transmission of second delay-sensitive traffic at a first unit time among multiple unit times, the transmissions of the first STA and the third STA may collide. In this case, the first STA may perform the first back-off procedure after the AIFS.

[0151] For example, the first STA may randomly select a back-off counter value for the first back-off procedure from [0, X], where each of 0 to X has an equal probability of being selected by the first STA, and X may be a natural number greater than or equal to 1.

[0152] As described above, the contention window size value X for the first back-off procedure may be set / indicated based on at least one first parameter, but may also be predefined. Additionally or alternatively, the size of X may be determined based on the number of retransmissions of the first delay-sensitive traffic of the first STA. The value of X may decrease as the number of retransmissions increases. Additionally, when the number of retransmissions exceeds a certain value, the value of X may not decrease further and may be maintained.

[0153] After the AIFS, based on the back-off value selected by the first STA being smaller than the back-off value selected by the third STA, the first STA may obtain a transmission opportunity (TXOP) (for the channel). The first STA may transmit the first delay-sensitive traffic to the second STA within the TXOP.

[0154] As an example of the present disclosure, based on the fact that only the first signal is transmitted to the second STA in the first unit time, the first STA can transmit the first delay-sensitive traffic after the AIFS. That is, if only the first STA transmits the first signal within the first unit time among multiple unit times, the first STA can transmit the first delay-sensitive traffic to the second STA after the AIFS.

[0155] The method described in the example of FIG. 8 may be performed by the first device (100) of FIG. 1. For example, one or more processors (102) of the first device (100) of FIG. 1 may receive a first frame including at least one first parameter related to delay-sensitive traffic transmission from a second STA through one or more transceivers (106). The one or more processors (102) may transmit a first signal related to the first delay-sensitive traffic to the second STA through the one or more transceivers (106) at a first unit of time among a plurality of unit times based on the at least one first parameter. The one or more processors (102) may transmit a second signal of a third STA to the second STA through the one or more transceivers (106) at the first unit of time.

[0156] Furthermore, one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 8 or the examples described below when executed by one or more processors (102).

[0157] FIG. 9 is a diagram for explaining a method performed by a second STA according to one embodiment of the present disclosure.

[0158] The second STA may transmit a first frame including at least one first parameter related to delay-sensitive traffic transmission to the first STA (S910).

[0159] As an example of the present disclosure, a second STA may determine the type of channel access procedure based on the number of (associated) STAs within a BSS and generate a first frame containing information about the determined channel access procedure. As an example, the configuration of the first frame has been described with reference to FIG. 8, and thus, a redundant description thereof will be omitted.

[0160] The first frame may be at least one of a beacon frame, a probe response frame, or a joining frame, and the second STA may transmit the first frame to at least one STA including the first STA (e.g., STA(s) within the BSS of the second STA).

[0161] The second STA may receive a first signal related to first delay-sensitive traffic from the first STA at a first unit time among a plurality of unit times based on at least one first parameter (S920). Through this, the second STA may confirm that the first STA has delay-sensitive traffic.

[0162] The method described in the example of FIG. 9 may be performed by the second device (200) of FIG. 1. For example, one or more processors (202) of the second device (200) of FIG. 1 may transmit a first frame including at least one first parameter related to delay-sensitive traffic transmission to a first STA through one or more transceivers (206). The one or more processors (202) may receive a first signal related to the first delay-sensitive traffic from the first STA through one or more transceivers (206) at a first unit time among a plurality of unit times based on the at least one first parameter.

[0163] Furthermore, one or more memories (204) of the second device (200) may store commands for performing the method described in the example of FIG. 9 or the examples described below when executed by one or more processors (202).

[0164] The following is a diagram specifically explaining an improved channel access method for transmitting and receiving low-latency traffic.

[0165] Example 1

[0166] Example 1 relates to a procedure for transmitting a short signal and parameters related thereto.

[0167] In a basic wireless LAN system, when an STA transmits a signal longer than a certain length (e.g., 4 us), the physical layer of another STA can detect the signal with a probability of more than 90%. In the present disclosure, a short signal may be a general term for a signal transmitted by an STA to indicate that it has traffic requiring low latency (or delay-sensitive traffic). A short signal may be a newly defined signal or a signal corresponding to the L-STF of a PPDU. For example, a short signal may have a length and / or configuration corresponding to the L-STF.

[0168] STAs requiring low-latency traffic transmission can divide the AIFS into multiple time units and transmit short signals during one of the multiple time units. In this case, the unit time may correspond to the short signal transmission time. In other words, the AIFS can be divided / identified as a multiple of the short transmission time.

[0169] Additionally or alternatively, if the number of STAs requesting low-latency transmission is less than a predefined value, each STA(s) may not perform short signal transmission. In this case, AIFS may be utilized according to the EDCA method of the basic wireless LAN system.

[0170] AIFS is divided into multiple time units (e.g., short signal transmission times), and by having STAs transmit short signals within one of the multiple time units, the effect of dispersing collisions between low-latency STAs (e.g., STAs requiring low-latency transmission) can be achieved. Furthermore, resource efficiency can be improved by transmitting and receiving separate signals (e.g., (short) signals for channel access) within AIFS.

[0171] For example, if a collision occurs because multiple STAs select the same unit time to transmit a short signal, the collision can be distributed by performing a back-off process after AIFS.

[0172] FIG. 10 is a diagram for explaining a short signal transmission procedure according to one embodiment of the present disclosure.

[0173] For example, as illustrated in FIG. 10, after STA 1 transmits a PPDU, competition between STA 2 and STA 3 may begin. At this time, STA 2 and STA 3 may be STAs that require low-latency transmission. As described above, AIFS may be divided into multiple unit times, and STA 2 and STA 3 may each select one of the multiple unit times and then perform short signal transmission.

[0174] For example, as illustrated in FIG. 10, assume that STA 2 and STA 3 select the same unit time and transmit a short signal within the selected unit time. Through each transmission by STA 2 and STA 3, other low-latency STAs or / and legacy STAs can detect that the current channel state is busy. If a collision occurs due to the simultaneous transmission of short signals, STA 2 and STA 3 can perform a random back-off operation after AIFS. If STA 2 selects 1 as the random back-off value and STA 3 selects 2 as the random back-off value, STA 2 can first obtain the right to use the channel (e.g., TXOP). Accordingly, STA 2 can perform a data transmission operation within the TXOP.

[0175] Here, the time unit selected for back-off may be, but is not limited to, slot time.

[0176] Additionally, the transmission of a short signal during an AIFS may occur once or more. That is, STA 2 and / or STA 3 may transmit a short signal for one or more time units. For example, STA 2 may transmit a short signal in each of two or more time units.

[0177] Example 2

[0178] Example 2 relates to a back-off procedure for improved channel access.

[0179] In a basic wireless LAN system, the back-off value to support low-latency transmission can be increased by a power of 2 when a collision occurs, but collisions may occur frequently due to the small contention window size. In addition, the exponential increase in the window size due to collisions may not meet the time requirement of low-latency transmission. To solve this problem, a contention window site (X) of a certain size can be predefined or set / indicated by the STA. The STA can uniformly select one of the integers between [0, X].

[0180] Here, the fact that STA uniformly selects one of the integers between [0, X] (e.g., rand(0, 7)) can mean that each integer between [0, X] has an equal probability of being selected. That is, all integers between [0, X] can be selected by STA with equal probability.

[0181] And, in order to match the delay budget of low-latency traffic, X can be changed per AC and / or per retransmission number. For example, as the number of retransmissions increases, the value of X can decrease and / or when the number of retransmissions exceeds a certain value, the value of X can be maintained. For example, when the first retransmission is performed, X can be defined / set to 7, when the second retransmission is performed, X can be defined / set to 5, and when the third or more retransmissions are performed, X can be defined / set to 3. However, this is only one embodiment, and the value of X per retransmission can be set / defined to various values.

[0182] For low-latency traffic requiring more rigorous delay tolerance, a smaller value of X may be defined / set / selected than for traffic requiring less rigorous delay tolerance. For example, for low-latency traffic requiring more rigorous delay tolerance (e.g., low-latency traffic 1), the value of X (e.g., X_1) may be set / defined / selected to 5, and for low-latency traffic requiring less rigorous delay tolerance (e.g., low-latency traffic 2), the value of X (e.g., X_2) may be set / defined / selected to 7.

[0183] As an example of the present disclosure, STA(s) belonging to the same AC may use the same back-off value. Additionally or alternatively, all ACs may use the same back-off value.

[0184] As another example of the present disclosure, different rand ranges may be specified for each AC depending on low latency requirements. The rand ranges may partially overlap. For example, if rand(0, X2) is set / defined for AC 1 and rand(X1, X3) is set / defined for AC2, X1 may be less than or equal to X2, and X2 may be less than X3. In this case, the delay tolerance of AC1 may be stricter than the delay tolerance of AC2 (e.g., the delay tolerance of AC1 may be less than the delay tolerance of AC2).

[0185] The selection unit of the above-described back-off can be based on a short signal duration unit or a slot time unit.

[0186] Example 3

[0187] Embodiment 3 relates to the operation of an STA based on Embodiment 1 and / or Embodiment 2.

[0188] After a specific STA completes a transmission operation during a TXOP, STA(s) desiring data transmission may attempt to access the channel through contention. At this time, it is assumed that at least one STA among the STA(s) attempting channel access desires low-latency traffic transmission.

[0189] For example, when performing the first transmission, at least one STA desiring low-latency traffic transmission may perform a channel access procedure based on EDCA parameter(s). As another example, at least one STA desiring low-latency traffic transmission may perform a channel access procedure based on parameter(s) supporting low-latency transmission, starting from the first transmission.

[0190] Here, the channel access procedure based on EDCA parameter(s) may include a procedure for performing channel access through parameters for performing / applying the EDCA method in a basic wireless LAN system. In addition, the channel access procedure based on parameter(s) supporting low-latency transmission may include a channel access procedure according to Embodiment 1 and / or Embodiment 2.

[0191] The parameter(s) supporting low-latency transmission may include information about the duration length of a short signal, X value(s) to support uniform back-off, conditions under which the parameter(s) supporting low-latency transmission are applied, and X value(s) that change / decrease depending on the number of retransmissions. The conditions under which the parameter(s) supporting low-latency transmission are applied may include the number of retransmissions for applying the parameter(s) supporting low-latency transmission.

[0192] For example, parameter(s) supporting low-latency transmission may be transmitted and received via a Picon frame, a probe response frame, and / or a (re)assembly frame. In addition, parameter(s) supporting low-latency transmission may be transmitted and received via elements, fields, subfields, etc. of the above-described frame or / and a new frame. When parameter(s) supporting low-latency transmission are transmitted and received via the above-described frame, parameter(s) supporting low-latency transmission may be set in the form of an extension of predefined elements, fields, and subfields.

[0193] FIG. 11 is a diagram illustrating a method for performing a channel access procedure according to one embodiment of the present disclosure.

[0194] For example, for the first transmission, the STA may perform an EDCA-based channel access procedure of the basic wireless LAN system (e.g., a channel access procedure based on EDCA parameter(s) of the basic wireless LAN system). From the second transmission onwards, the STA may perform a channel access procedure based on parameter(s) that support low-latency transmission.

[0195] As illustrated in Fig. 11, as the number of transmissions increases, the value of X in rand(0, X) may decrease. And, if the number of retransmissions exceeds a predefined / set value (e.g., 4), the value of X in rand(0, X) may be maintained.

[0196] As an example of the present disclosure, when the number of STAs requiring low-latency transmission increases and the number of STAs that cannot meet the delay tolerance increases accordingly, the AP (or / and AP MLD) may inform the STAs of the time point of application of parameter(s) supporting low-latency transmission through broadcast, multicast, or / and unicast methods.

[0197] For example, if the number of STAs requesting low-latency transmission exceeds a first threshold and / or the number of STAs that cannot tolerate delay exceeds a second threshold, the AP (or / and AP MLD) may transmit a frame containing the application time of parameter(s) supporting low-latency transmission to the STAs in a broadcast, multicast, or / and unicast manner.

[0198] Additionally or alternatively, if collisions need to be distributed (e.g., if congestion becomes severe), additional back-off opportunities may be provided after the random back-off. For example, if the number of STAs requesting low-latency transmission exceeds a first threshold, the number of STAs that cannot tolerate delay exceeds a second threshold, and / or the number of collisions exceeds a third threshold, additional back-off opportunities may be provided / defined after the random back-off.

[0199] The selection unit for the corresponding back-off may be based on a short signal interval or a slot time. The number of units selectable for the corresponding back-off may be less than the number of short signal-based units during an AIFS or the number of units in a slot time during a random back-off.

[0200] Additionally or alternatively, the AP (or / and AP MLD) may selectively apply short signal-based collision distribution, random back-off-based collision distribution, or collision distribution after random back-off during AIFS, depending on the number of associated STAs within the BSS, the number of STAs requiring low-latency transmission, the number of STAs per low-latency class, and / or the degree of OBSS interference.

[0201] That is, whether to perform each of the operations according to each of Embodiment 1 and Embodiment 2 (e.g., short signal transmission / reception operation during AIFS, random back-off operation, collision distribution operation after random back-off) may be determined / selected based on the number of combined STAs within the BSS, the number of STAs requesting low-latency transmission, the number of STAs per low-latency class, and / or the degree of OBSS interference.

[0202] For example, the AP (or / and AP MLD) may transmit to the STA whether to perform at least one of the operations according to each of Embodiments 1 and 2 in a broadcast, multicast, or / and unicast manner.

[0203] The operations according to Embodiments 1, 2, and 3 may be performed selectively or in combination as a whole. According to the embodiments described above, channel contention among legacy STAs can be prevented through transmission of short signals, and early transmission opportunities can be provided to STAs requiring low-latency transmission.

[0204] Additionally, as the number of STAs requiring low-latency transmission increases, channel access can be efficiently distributed, and active opportunities can be provided to STAs approaching their delay tolerance. Furthermore, services can be differentially provided to STAs requiring low latency based on their delay requirements.

[0205] The embodiments described above are combinations of components and features of the present disclosure in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented without being combined with other components or features. Furthermore, it is also possible to form embodiments of the present disclosure by combining some components and / or features. 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 self-evident that claims that do not have an explicit citation relationship in the patent claims may be combined to form embodiments or incorporated as new claims through post-application amendments.

[0206] It will be apparent to those skilled in the art that the present disclosure may be embodied in other specific forms without departing from the essential characteristics thereof. Therefore, the above detailed description should not be construed as limiting in any respect, but rather as illustrative. The scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents of the present disclosure are intended to be included within the scope of the present disclosure.

[0207] The scope of the present disclosure includes software or machine-executable instructions (e.g., an operating system, an application, firmware, a program, etc.) that cause operations according to the methods of various embodiments to be executed on a device or a computer, and a non-transitory computer-readable medium having such software or instructions stored thereon and executable on the device or computer. Instructions that can be used to program a processing system to perform the features described in the present disclosure can be stored on / in a storage medium or a computer-readable storage medium, and a computer program product including such a storage medium can be used to implement the features described in the present disclosure. The storage medium can include, but is not limited to, high-speed random access memory, such as DRAM, SRAM, DDR RAM, or other random access solid state memory devices, and can include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices. The memory optionally includes one or more storage devices remotely located from the processor(s). The memory or, alternatively, the non-volatile memory device(s) within the memory comprise a non-transitory computer-readable storage medium. The features described in this disclosure may be incorporated into software and / or firmware stored on any of the machine-readable media, which may control the hardware of the processing system and allow the processing system to interact with other mechanisms that utilize results according to 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.

[0208] The method proposed in this disclosure has been described with a focus on examples applied to IEEE 802.11-based systems, but can be applied to various wireless LANs or wireless communication systems in addition to IEEE 802.11-based systems.

Claims

1. A step of receiving, by a first station (STA), a first frame including at least one first parameter related to transmission of delay-sensitive traffic from a second STA; A step of transmitting a first signal related to a first delay-sensitive traffic from the first STA to the second STA at a first unit time among a plurality of unit times based on at least one first parameter, wherein an arbitration inter-frame space (AIFS) is divided into the plurality of unit times; and A method comprising: performing a first back-off procedure by the first STA after the AIFS based on the second signal of the third STA being transmitted to the second STA at the first unit time.

2. In paragraph 1, A transmission opportunity (TXOP) is acquired by the first STA based on the back-off value selected by the first STA after the AIFS being less than the back-off value selected by the third STA, A method in which the first delay-sensitive traffic is transmitted to the second STA by the first STA within the TXOP.

3. In paragraph 1, A method according to claim 1, wherein the at least one first parameter includes at least one of information about at least one of a length of a duration of the first signal, a contention window size value (X) for the first back-off procedure, a channel access procedure by the number of retransmissions, or a channel access procedure by the number of STAs in a basic service set (BSS) of the second STA.

4. In paragraph 1, A method in which the first delay-sensitive traffic is transmitted from the first STA to the second STA after the AIFS based on the first signal being transmitted to the second STA in the first unit time.

5. In paragraph 3, The back-off counter value for the first back-off procedure is randomly selected by the first STA from among [0, X], The probability that each of the above 0 to X is selected by the first STA is the same, The above X is one or more natural persons, method.

6. In paragraph 5, A method in which the size of X is determined based on the number of retransmissions of the first delay-sensitive traffic of the first STA.

7. In paragraph 3, A method wherein the channel access procedure comprises a channel access procedure based on at least one first parameter and a channel access procedure based on at least one second parameter related to enhanced distributed channel access (EDCA).

8. In paragraph 7, A method wherein the first frame includes information on a channel access procedure based on the at least one first parameter, based on the number of STAs within the BSS of the second STA exceeding a predefined value.

9. In paragraph 7, A method wherein said at least one second parameter comprises at least one of an AIFS number (AIFSN) or a minimum value and a maximum value of a contention window.

10. In paragraph 1, A method wherein the first frame is at least one of a beacon frame, a probe response frame, or a combination frame.

11. In paragraph 1, Each of the first STA and the third STA is a non-access point (AP) STA, The above second STA is an AP.

12. In the first station (STA), the first STA: one or more transmitters and receivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: Receiving a first frame including at least one first parameter related to delay sensitive traffic transmission from a second STA through the one or more transceivers; A step of transmitting a first signal related to a first delay-sensitive traffic to the second STA through the one or more transceivers at a first unit time among a plurality of unit times based on the at least one first parameter, wherein an arbitration inter-frame space (AIFS) is divided into the plurality of unit times; and A first STA configured to perform a first back-off procedure after the AIFS based on the second signal of the third STA being transmitted to the second STA at the first unit time.

13. A step of transmitting a first frame including at least one first parameter related to delay-sensitive traffic transmission by a second station (STA) to a first STA; and A method comprising: receiving, by the second STA, a first signal related to first delay-sensitive traffic from the first STA at a first unit time among a plurality of unit times based on at least one first parameter, wherein an arbitration inter-frame space (AIFS) is divided into the plurality of unit times; A method wherein a first back-off procedure is performed after the AIFS based on the second signal of the third STA being received at the first unit time.

14. In the second station (STA), the second STA: one or more transmitters and receivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: Transmitting a first frame including at least one first parameter related to delay-sensitive traffic transmission to a first STA via the one or more transceivers; and A method comprising: receiving a first signal related to a first delay-sensitive traffic from the first STA through the one or more transceivers at a first unit time among a plurality of unit times based on at least one first parameter, wherein an arbitration inter-frame space (AIFS) is divided into the plurality of unit times; A second STA, where the first back-off procedure is performed after the AIFS based on the second signal of the third STA being received at the first unit time.

15. In a processing device configured to control a station (STA) in a wireless local area network (WLAN) system, the processing device: one or more processors; and A processing device comprising one or more computer memories operatively connected to said one or more processors and storing instructions for performing a method according to any one of claims 1 to 11 based on execution by said one or more processors.

16. One or more non-transitory computer-readable media storing one or more instructions, A computer-readable medium, wherein the one or more commands are executed by one or more processors to control a device in a wireless LAN system to perform a method according to any one of claims 1 to 11.

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