Method and device for transmitting or receiving preemption request in wireless LAN system

Abstract

Disclosed are a method and device for transmitting or receiving a preemption request in a wireless LAN system. A method performed by a first station (STA) in a wireless local area network (WLAN) system, according to one embodiment of the present disclosure, may comprise the steps of: receiving, from a second STA, a first physical layer protocol data unit (PPDU) including information related to preemption, wherein the first PPDU is transmitted on a first bandwidth; and on the basis of availability of a second bandwidth that is based on one or more of the first bandwidth, a first operation bandwidth of the first STA, and a specific bandwidth, transmitting a second PPDU including a preemption request to the second STA on the second bandwidth.

Description

Method and device for transmitting or receiving a preemption request in a wireless LAN system

[0001] The present disclosure relates to a method and device for transmitting or receiving a preemption request in a wireless local area network (WLAN) 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 transmitting or receiving a preemption request in a wireless LAN system.

[0005] An additional technical problem of the present disclosure is to provide a method and device for transmitting or receiving a preemption request based on transmission bandwidth and / or preamble puncturing in a wireless LAN system.

[0006] 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.

[0007] A method performed by a first station (STA) in a wireless local area network (WLAN) system according to one aspect of the present disclosure may include receiving a first physical layer protocol data unit (PPDU) including information related to preemption from a second STA, the first PPDU being transmitted on a first bandwidth; and transmitting a second PPDU including a preemption request to the second STA on the second bandwidth based on availability of a second bandwidth based on at least one of the first bandwidth, a first operating bandwidth of the first STA, or a specific bandwidth.

[0008] A method performed by a second station (STA) in a wireless local area network (WLAN) system according to an additional aspect of the present disclosure may include transmitting a first physical layer protocol data unit (PPDU) including information related to preemption to one or more STAs including the first STA, the first PPDU being transmitted on a first bandwidth; and receiving a second PPDU including a preemption request transmitted from the first STA on the second bandwidth based on availability of a second bandwidth based on one or more of the first bandwidth, a first operating bandwidth of the first STA, or a specific bandwidth.

[0009] According to the present disclosure, a method and device for transmitting or receiving a preemption request in a wireless LAN system can be provided.

[0010] According to the present disclosure, a method and device for transmitting or receiving a preemption request based on transmission bandwidth and / or preamble puncturing in a wireless LAN system can be provided.

[0011] 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.

[0012] 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.

[0013] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0014] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0015] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0016] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0017] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0018] 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.

[0019] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0020] FIG. 8 is a diagram illustrating an example of a TXOP supporting preemption to which the present disclosure can be applied.

[0021] FIG. 9 is a diagram illustrating an example of a preemption request and LL traffic transmission to which the present disclosure can be applied.

[0022] FIG. 10 is a drawing for explaining an example of a method performed by a first STA according to the present disclosure.

[0023] FIG. 11 is a drawing for explaining an example of a method performed by a second STA according to the present disclosure.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] Below, technical features to which examples of the present disclosure can be applied are described.

[0031] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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).

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0045] 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.

[0046] 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.

[0047] 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).

[0048] 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.

[0049] 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.

[0050] 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).

[0051] 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.

[0052] 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.

[0053] In addition to the structure of the DS described above, an extended service set (ESS) may be established to provide wider coverage.

[0054] 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.

[0055] 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.

[0056] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0070] 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.

[0071] 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).

[0072] 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 value doubled 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, ...).

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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).

[0095] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0096] 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)).

[0097] 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).

[0098] 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)).

[0099] 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-SIG-B is not included in the HE PPDU format for single users (SUs). 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 8 microseconds (us). 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 can vary to 16us. For example, the RL-SIG can be configured identically to the 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 the RL-SIG.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated to allow legacy STAs to attempt demodulation and decoding, and 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 to allow STAs that have successfully decoded non-legacy SIGs (e.g., U-SIG and / or EHT-SIG) and obtained the information contained in the fields, and mapped based on a predetermined subcarrier frequency interval (e.g., 78.125 kHz). These can be referred to as EHT modulated fields.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.).

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.).

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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, 4X996-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.

[0123] 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.

[0124] 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.

[0125] Preemption-based data transmission

[0126] In wireless LAN systems, preemption can be applied to data transmission by STAs that have not acquired a TXOP. For example, data transmitted based on preemption may correspond to low latency (LL) traffic. LL traffic is difficult to predict, has a relatively small size, and must be transmitted quickly. However, in existing wireless LAN systems, during a TXOP acquired by an STA, other STAs must wait until the TXOP ends before attempting medium access. Therefore, a preemption technique can be applied to support STAs that do not hold a TXOP to transmit LL traffic during a TXOP. However, the application of preemption-based data transmission is not limited to LL traffic and can also be applied to traffic for other purposes.

[0127] FIG. 8 is a diagram illustrating an example of a TXOP supporting preemption to which the present disclosure can be applied.

[0128] To ensure smooth preemption, an STA having data to transmit (e.g., LL traffic) can transmit a preemption request frame to the AP at a specific timing. For example, it can be assumed that the AP holds a TXOP and transmits a DL PPDU to STA1 within the TXOP duration. Although not illustrated in FIG. 8, the TXOP can begin when the AP performs a backoff and transmits an RTS frame to STA1, and in response, STA1 transmits a CTS to the AP, after which DL PPDU transmission from the AP to STA1 can be performed. The examples of the present disclosure can also be applied to cases where the TXOP is acquired in other ways.

[0129] A DL PPDU transmitted from the AP to STA1 may include small-sized PPDUs transmitted at intervals of xIFS (e.g., PIFS). A specific bit in the PHY header of each DL PPDU may be defined as a preemption bit indicating whether transmission of a preemption request (PR) is permitted. For example, a value of the preemption bit of 1 may indicate that PR transmission is permitted, and a value of 0 may indicate that PR transmission is not permitted.

[0130] For example, an STA with LL data can transmit a PR frame in the xIFS gap. For example, assume that another STA (e.g., STA2, STA3, ...) overhearing a DL PPDU transmitted to STA1 has LL traffic. If the preemption bit of the PHY header of the DL PPDU has a value of 1, the STA with LL traffic can transmit a PR frame within the xIFS gap, for example, after the end of the DL PPDU. p After a time (where T pThe AP may transmit a PR frame to the AP during the xIFS gap (shorter than xIFS). If there is no STA with LL traffic, there may be no STA transmitting a PR frame even if the preemption bit of the DL PPDU has a value of 1. That is, the AP may attempt to detect a PR frame during the xIFS gap. In the example of Fig. 8, if a PR frame is not received after transmitting a DL PPDU with the preemption bit set to a value of 1, the AP may transmit subsequent DL PPDUs, receive a block ACK (BA) from STA1, and terminate the TXOP.

[0131] FIG. 9 is a diagram illustrating an example of a preemption request and LL traffic transmission to which the present disclosure can be applied.

[0132] For example, assume that LL traffic to be transmitted to the AP occurs in STA2 and STA3. This may correspond to a situation where data corresponding to the LL traffic is piled up in the transmission queue of STA2 and STA3 while the AP is transmitting a DL PPDU to STA1 in TXOP. If the value of the preemption bit in the DL PPDU is set to 1, STA2 and STA3 may transmit the LL traffic within the gap of xIFS (e.g., SIFS or T at the time when the DL PPDU ends). p Afterwards, a preemption request (PR) frame may be transmitted to the AP. For example, the PR frame may be transmitted in a format similar to the CTS. For example, the PR frame may be transmitted using a non-HT or non-HT duplicated (DUP) PPDU.

[0133] The AP can know that the STA(s) have LL traffic to transmit through the PR frame. Here, the AP may not be able to specify / identify which STA has the LL traffic. Upon receiving the PR frame, the AP can transmit an NFRP (NDP feedback report poll) frame to determine which STA(s) have the LL traffic. In response, STA2 and STA3 can each transmit an NFR (NDP feedback report) frame. When transmitting the NFR frame, each STA can use a pre-assigned LTF tone index, through which the AP can identify the STA that transmitted the NFR frame.

[0134] The AP can transmit a trigger frame to STA2 and STA3, and receive LL traffic data from STA2 and STA3 via a TB PPDU. For example, the trigger frame can include information about frequency resources (e.g., RUs) allocated to each of STA2 and STA3, and each of STA2 and STA3 can transmit a PPDU (i.e., an LL PPDU) containing LL data on the frequency resources allocated to each of them. The AP, which receives the LL PPDU, can transmit a BA to STA2 and STA3.

[0135] PPDU carrying preemption request frame

[0136] This disclosure describes various examples of bandwidth for a PPDU carrying a Preemption Request (PR) frame. Additionally, various examples of preamble puncturing applied to a PPDU carrying a PR frame are also described.

[0137] In the following description, it can be assumed that the PR frame has a format similar to the CTS frame as described above, is transmitted by STAs with LL data within the xIFS gap between DL PPDUs in a TXOP, and the PPDU carrying the PR is a non-HT PPDU or a non-HT DUP PPDU. However, the examples of the present disclosure are not limited thereto, and can be applied to, for example, PR frames in other formats, PR frames for transmitting data for purposes other than LL traffic, and PPDU formats other than non-HT / non-HT DUP.

[0138] Unlike the CTS frame solicited by the existing MU-RTS trigger frame, which is transmitted using the channel allocated by the MU-RTS trigger frame, the PR frame is transmitted at a specific time (e.g., SIFS or T) after the DL PPDU transmission is terminated without a frame requesting / triggering it. p ) is transmitted later, it is necessary to define the channel, bandwidth, preamble puncturing, etc. for transmitting the PR frame.

[0139] FIG. 10 is a drawing for explaining an example of a method performed by a first STA according to the present disclosure.

[0140] In step S1010, the first STA may receive a first PPDU including information related to preemption from the second STA. For example, the first PPDU may be transmitted on a first bandwidth.

[0141] Information related to preemption may correspond to 1-bit information indicating whether preemption is permitted. For example, information related to preemption may correspond to the preemption bit in the examples of FIGS. 8 and 9.

[0142] In step S1020, the first STA may transmit a second PPDU including a preemption request to the second STA on the second bandwidth based on availability of a second bandwidth based on one or more of the first bandwidth, the operating bandwidth of the first STA, or a specific bandwidth.

[0143] The availability of the second bandwidth may be the case where a primary channel included in the second bandwidth is available (or idle) before the transmission of the second PPDU, and one or more secondary channels included in the second bandwidth are available (or idle).

[0144] For example, the secondary bandwidth may be the primary 20MHz. In this case, preamble puncturing may not be applied.

[0145] For example, the second bandwidth may be equal to the first operating bandwidth of the first STA. In this case, preamble puncturing may be applied if necessary.

[0146] For example, the second bandwidth may be equal to the first bandwidth. If the first operating bandwidth is greater than or equal to the first bandwidth, the second bandwidth of the second PPDU may be equal to the first bandwidth. If the first operating bandwidth is less than the first bandwidth, the second bandwidth may be equal to the first operating bandwidth. Alternatively, if the first operating bandwidth is less than the first bandwidth, the second PPDU may not be transmitted (or the second bandwidth may be determined to be unavailable). In this case, preamble puncturing may be applied if necessary.

[0147] For example, the second bandwidth may be a bandwidth greater than or equal to a specific bandwidth. The specific bandwidth may correspond to a bandwidth indicated by information included in the first PPDU. If the first operating bandwidth is greater than or equal to the specific bandwidth, the second bandwidth may be a bandwidth greater than or equal to the specific bandwidth. If the first operating bandwidth is less than or equal to the specific bandwidth, the second bandwidth may be equal to the first operating bandwidth. Alternatively, if the first operating bandwidth is less than or equal to the specific bandwidth, the second PPDU may not be transmitted (or the second bandwidth may be determined to be unavailable). In this case, preamble puncturing may be applied if necessary.

[0148] The specific bandwidth may be indicated by one of the specific bandwidth candidates (e.g., 20 MHz, 40 MHz, 80 MHz, 160 MHz, and 320 MHz) by 3-bit information included in the first PPDU. Alternatively, the specific bandwidth may be indicated by one of the first bandwidth, 1 / 2 of the second bandwidth, 1 / 4 of the first bandwidth, or 1 / 8 of the first bandwidth by 2-bit information included in the first PPDU. Alternatively, the specific bandwidth may be indicated by one of the first bandwidth, or 1 / 2 of the first bandwidth by 1-bit information included in the first PPDU.

[0149] For example, when the first operating bandwidth is less than the first bandwidth, or when the first operating bandwidth is less than a specific bandwidth, a second PPDU including a preemption request may be transmitted on a second bandwidth that is the same as the first operating bandwidth. Thereafter, a trigger frame for the first STA and one or more third STAs may be transmitted from the second STA. Between the PR frame transmission of the first STA and the trigger frame transmission of the second STA, an NFRP frame and an NFR frame, such as the example of FIG. 9, may be transmitted and received. Here, one or more of the third STAs may correspond to STAs that have not transmitted a preemption request (and further, have not performed NFRP reception and NFR transmission). In addition, the operating bandwidth of the corresponding third STA may be an STA set to be the same as the second bandwidth or to be the same as the specific bandwidth or more. Among these STAs, one or more STAs may be determined / selected by the second STA and instructed through a trigger frame as one or more third STAs that perform uplink transmission together with the first STA.

[0150] Based on this trigger frame, LL data from the first STA may be transmitted to the second STA through a third PPDU, and together with this, dummy signals or user data from each of one or more third STAs may be transmitted to the second STA. In this regard, information indicating whether each of the one or more third STAs transmits the dummy signal or user data may be included in the third PPDU. Alternatively, the trigger frame may include information about uplink OFDMA-based random access (UORA) from one or more other STAs (i.e., any STA).

[0151] In the examples described above, the operating bandwidth of an STA can be determined by the AP during the STA association process. The bandwidth of a BSS corresponds to the bandwidth of the operating channel included in the beacon, which may correspond to the maximum bandwidth supported by the BSS. The bandwidth of a PPDU may correspond to the bandwidth corresponding to the available (i.e., idle) channel(s) based on whether the STA wishing to transmit the PPDU determines whether the primary channel and secondary channel are busy or idle.

[0152] The method described in the example of FIG. 10 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 be configured to receive a first PPDU including information related to preemption from a second STA through one or more transceivers (106) on a first bandwidth; and transmit a second PPDU including a preemption request to the second STA through one or more transceivers (106) on the second bandwidth based on availability of a second bandwidth based on one or more of the first bandwidth, the first operating bandwidth of the first STA, or a specific bandwidth. Furthermore, one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 10 or the examples described below when executed by one or more processors (102).

[0153] FIG. 11 is a drawing for explaining an example of a method performed by a second STA according to the present disclosure.

[0154] In step S1110, the second STA may transmit a first PPDU containing information related to preemption over the first bandwidth. The first PPDU may be a PPDU containing a frame transmitted to a specific STA, but may also be received or overheard by one or more other STAs, including the first STA.

[0155] In step S1120, the second STA may receive a second PPDU including a preemption request transmitted from the first STA on the second bandwidth based on availability of a second bandwidth based on one or more of the first bandwidth, the first operating bandwidth of the first STA, or a specific bandwidth.

[0156] Information related to preemption, the first bandwidth, the second bandwidth, the specific bandwidth, and the description related to the second PPDU are the same as those described in the example of FIG. 10, so redundant descriptions are omitted.

[0157] The method described in the example of FIG. 11 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 be configured to transmit a first PPDU including information related to preemption through one or more transceivers on a first bandwidth; and receive a second PPDU including a preemption request transmitted from the first STA through one or more transceivers on the second bandwidth based on availability of a second bandwidth based on one or more of the first bandwidth, the first operating bandwidth of the first STA, or a specific bandwidth. Furthermore, one or more memories (204) of the second device (200) may store instructions for performing the method described in the example of FIG. 11 or the examples described below when executed by one or more processors (202).

[0158] In the examples of FIGS. 10 and 11, the first STA may be a non-access point (non-AP) STA, and the second STA may be an AP STA.

[0159] The examples of FIGS. 10 and 11 may correspond to some of the various examples of the present disclosure. Below, various examples of the present disclosure, including the examples of FIGS. 10 and 11, will be described in more detail.

[0160] Example 1

[0161] In this embodiment, the PPDU containing the PR frame (e.g., the second PPDU) may only be transmitted on the primary 20 MHz. In this case, preamble puncturing may not be applied.

[0162] When the primary 20MHz channel is idle (e.g., the primary channel may be busy when the NAV is set for an STA that wants to transmit a PR frame due to a transmission from an STA other than the AP), a PPDU containing a PR frame may be transmitted. For example, when the primary 20MHz channel is not idle for a certain time (e.g., SIFS) after a DL PPDU (e.g., first PPDU) ends and before transmission of a PPDU containing a PR frame (e.g., second PPDU), the PPDU containing a PR frame (e.g., second PPDU) may not be transmitted.

[0163] According to this embodiment, the operation of determining the transmission bandwidth of a PPDU including a PR frame can be simply implemented.

[0164] Example 2

[0165] In this embodiment, a PPDU containing a PR frame may be transmitted over a bandwidth based on the operating bandwidth of the STA attempting to transmit it. For example, a PPDU containing a PR frame may be transmitted over a bandwidth equal to (or lower than) the operating bandwidth of the STA.

[0166] When the primary 20MHz channel is idle (e.g., the primary channel may be busy if the NAV is set for an STA attempting to transmit a PR frame due to a transmission from another STA other than the AP), a PPDU containing the PR frame may be transmitted on a bandwidth that includes the primary 20MHz channel and one or more secondary channels that are idle (if any).

[0167] If the STA's operating bandwidth is greater than the BSS bandwidth, a PPDU containing a PR frame may be transmitted according to the BSS bandwidth.

[0168] In the case where the bandwidth of a PPDU including a PR frame is determined based on the operating bandwidth of the STA as above, preamble puncturing may be applied in the PPDU including the PR frame based on a punctured channel in a DL PPDU (e.g., a first PPDU) or a disabled subchannel indicated by a beacon frame, etc. (e.g., a subchannel indicated as disabled in a disabled subchannel bitmap subfield in an EHT operating element). Preamble puncturing may be applied to a channel (e.g., a secondary channel) that is not idle for a specific time (e.g., SIFS) before transmission of a PPDU including a PR frame (e.g., a second PPDU) after the end of a DL PPDU (e.g., a first PPDU). If the primary 20 MHz channel is not idle for a certain period of time (e.g., SIFS) prior to transmission of the PPDU containing the PR frame (e.g., the second PPDU), the PPDU containing the PR frame (e.g., the second PPDU) may not be transmitted.

[0169] According to the present embodiment, when the AP triggers / solicits a TB PPDU for transmission of data (e.g., LL data) from an STA that has requested preemption, the settings of the channel and bandwidth of the TB PPDU can be advantageously applied.

[0170] Example 3

[0171] In this embodiment, a PPDU including a PR frame (e.g., a second PPDU) may be transmitted on a bandwidth based on a bandwidth (e.g., a first bandwidth) of a DL PPDU (e.g., a first PPDU). For example, a PPDU including a PR frame may be transmitted on a bandwidth equal to (or less than) the bandwidth of a DL PPDU.

[0172] When the primary 20MHz channel is idle (e.g., the primary channel may be busy if the NAV is set for an STA attempting to transmit a PR frame due to a transmission from another STA other than the AP), a PPDU containing the PR frame may be transmitted on a bandwidth that includes the primary 20MHz channel and one or more secondary channels that are idle (if any).

[0173] If the bandwidth of the DL PPDU (e.g., the first bandwidth of the first PPDU) is larger than the operating bandwidth of the STA that is to transmit the PR frame, the PPDU (e.g., the second PPDU) including the PR frame may be transmitted at a bandwidth equal to (or less than) the operating bandwidth. Alternatively, if the operating bandwidth of the STA that is to transmit the PR frame is smaller than the bandwidth of the DL PPDU (e.g., the first bandwidth of the first PPDU) and thus transmission cannot be performed on the same bandwidth as the DL PPDU, the PPDU (e.g., the second PPDU) including the PR frame may not be transmitted.

[0174] In the case where the bandwidth of a PPDU including a PR frame is determined based on the bandwidth of a DL PPDU as above, preamble puncturing may be applied in the PPDU including the PR frame based on a punctured channel in the DL PPDU (e.g., the first PPDU) or a disabled subchannel indicated by a beacon frame or the like (e.g., a subchannel indicated as disabled in a disabled subchannel bitmap subfield in an EHT operating element). Preamble puncturing may be applied to a channel (e.g., a secondary channel) that is not idle for a specific time (e.g., SIFS) before transmission of a PPDU including a PR frame (e.g., a second PPDU) after the end of the DL PPDU (e.g., the first PPDU). If the primary 20 MHz channel is not idle for a certain period of time (e.g., SIFS) prior to transmission of the PPDU containing the PR frame (e.g., the second PPDU), the PPDU containing the PR frame (e.g., the second PPDU) may not be transmitted.

[0175] According to the present embodiment, a PPDU including a PR frame can be transmitted while minimizing interference, taking into account a situation in which a channel other than the channel used by a DL PPDU may be used by an OBSS.

[0176] Example 4

[0177] In this embodiment, a PPDU containing a PR frame (e.g., a second PPDU) may be transmitted on a bandwidth based on a specific bandwidth indicated by information contained in a DL PPDU (e.g., a first PPDU). For example, a PPDU containing a PR frame may be transmitted on a bandwidth equal to (or greater than) the specific bandwidth.

[0178] If the bandwidth of a PPDU (e.g., the second bandwidth) containing a PR frame or data of an STA (e.g., LL traffic) is smaller than the bandwidth of a DL PPDU (e.g., the first bandwidth), a channel that is not included in the second bandwidth among the first bandwidths and is not used for transmission may be determined to be idle in the OBSS, etc. and used. In this case, problems such as throughput reduction or collision may occur when DL PPDU transmission is resumed after the PR and subsequent data transmission are completed. To prevent this, in addition to the preemption bit in the DL PPDU, a minimum bandwidth that must be guaranteed or desired to be used for transmission when transmitting the PR or data (e.g., LL traffic) when the preemption bit is 1 (i.e., preemption is allowed) may be indicated. This minimum bandwidth may correspond to the specific bandwidth described above.

[0179] A specific bandwidth may also be indicated through a specific field, such as a PHY header. For example, information indicating a specific bandwidth may be defined as a 3-bit field, identical to the existing bandwidth field, and may be set to the same content as before (e.g., indicating one of the candidate bandwidths of 20, 40, 80, 160, 320 MHz, etc.).

[0180] As another example, information indicating a specific bandwidth may be defined as 1-bit in size, and a first value (e.g., 0) may indicate a bandwidth equal to the bandwidth of the DL PPDU, and a second value (e.g., 1) may indicate a bandwidth one step smaller (e.g., half) than the bandwidth of the DL PPDU. The bandwidth steps correspond to 20, 40, 80, 160, 320 MHz, ..., and for example, if the DL PPDU bandwidth is 80 MHz, a bandwidth one step smaller than that may correspond to 40 MHz.

[0181] As another example, information indicating a specific bandwidth may be defined as a 2-bit size, where a first value (e.g., 0) indicates a bandwidth equal to the bandwidth of the DL PPDU, a second value (e.g., 1) indicates a bandwidth that is two steps smaller (e.g., 1 / 4) than the bandwidth of the DL PPDU, a third value (e.g., 2) indicates a bandwidth that is one step smaller (e.g., 1 / 2) than the bandwidth of the DL PPDU, and a fourth value (e.g., 3) may indicate a bandwidth that is three steps smaller (e.g., 1 / 8) than the bandwidth of the DL PPDU.

[0182] When the primary 20MHz channel is idle (e.g., the primary channel may be busy if the NAV is set for an STA attempting to transmit a PR frame due to a transmission from another STA other than the AP), a PPDU containing the PR frame may be transmitted on a bandwidth that includes the primary 20MHz channel and one or more secondary channels that are idle (if any).

[0183] If a specific bandwidth is greater than the operating bandwidth of an STA attempting to transmit a PPDU containing a PR frame, the PPDU containing the PR frame may be transmitted on a bandwidth equal to (or less than) its operating bandwidth. Alternatively, if a specific bandwidth greater than its operating bandwidth is indicated, the STA may not transmit a PPDU containing a PR frame.

[0184] When the bandwidth of a PPDU containing a PR frame is determined based on a specific bandwidth indicated by a DL PPDU as above, preamble puncturing may be applied in the PPDU containing the PR frame based on a punctured channel in the DL PPDU (e.g., the first PPDU) or a disabled subchannel indicated by a beacon frame or the like (e.g., a subchannel indicated as disabled in a disabled subchannel bitmap subfield in an EHT operating element). Preamble puncturing may be applied to a channel (e.g., a secondary channel) that is not idle during a specific time (e.g., SIFS) before transmission of a PPDU containing a PR frame (e.g., a second PPDU) after the end of the DL PPDU (e.g., the first PPDU). If the primary 20 MHz channel is not idle for a certain period of time (e.g., SIFS) prior to transmission of the PPDU containing the PR frame (e.g., the second PPDU), the PPDU containing the PR frame (e.g., the second PPDU) may not be transmitted.

[0185] According to this embodiment, it is possible to prevent a portion of a channel used in DL PPDU transmission from being occupied by OBSS, etc. during PR transmission and subsequent data (e.g., LL traffic) transmission.

[0186] Example 5

[0187] In the present embodiment, as in the aforementioned embodiment 3, a PPDU (e.g., a second PPDU) including a PR frame is transmitted on a bandwidth based on the bandwidth of a DL PPDU (e.g., a first bandwidth of the first PPDU) as in the aforementioned embodiment 3, and if the operating bandwidth of an STA attempting to transmit a PPDU including a PR frame is smaller than the bandwidth of the DL PPDU, the PPDU may be transmitted based on a specific bandwidth indicated by information included in the DL PPDU as in the aforementioned embodiment 4. That is, the bandwidth of the PPDU including a PR frame (e.g., a second bandwidth of the second PPDU) may be greater than or equal to the specific bandwidth indicated by the information included in the DL PPDU and less than or equal to the bandwidth of the DL PPDU (i.e., the first bandwidth of the first PPDU).

[0188] If the operating bandwidth of an STA attempting to transmit a PPDU including a PR frame is less than a specific bandwidth indicated by information included in the DL PPDU, the PPDU including the PR frame may not be transmitted.

[0189] When the primary 20MHz channel is idle (e.g., the primary channel may be busy if the NAV is set for an STA attempting to transmit a PR frame due to a transmission from another STA other than the AP), a PPDU containing the PR frame may be transmitted on a bandwidth that includes the primary 20MHz channel and one or more secondary channels that are idle (if any).

[0190] In the case where the bandwidth of a PPDU including a PR frame is determined based on a specific bandwidth indicated by a DL PPDU as above and the bandwidth of the DL PPDU, preamble puncturing may be applied in the PPDU including the PR frame based on a punctured channel in the DL PPDU (e.g., the first PPDU) or a disabled subchannel indicated by a beacon frame or the like (e.g., a subchannel indicated as being disabled in a disabled subchannel bitmap subfield in an EHT operating element). Preamble puncturing may be applied to a channel (e.g., a secondary channel) that is not idle for a specific time (e.g., SIFS) before transmission of a PPDU including a PR frame (e.g., a second PPDU) after the end of the DL PPDU (e.g., the first PPDU). If the primary 20 MHz channel is not idle for a certain period of time (e.g., SIFS) prior to transmission of the PPDU containing the PR frame (e.g., the second PPDU), the PPDU containing the PR frame (e.g., the second PPDU) may not be transmitted.

[0191] Example 6

[0192] In the present embodiment, when preamble puncturing is applied in the aforementioned embodiments 2 to 5, a PPDU including a PR frame can be transmitted on the largest primary channel that is not subject to preamble puncturing.

[0193] For example, it can be assumed that the bandwidth of a PPDU including a PR frame is determined to be 80 MHz, and one 20 MHz within a secondary 40 MHz is punctured. In this case, according to embodiments 2 to 5, a PPDU including a PR frame can be transmitted on the primary 40 MHz and the unpunctured 20 MHz within the secondary 40 MHz. According to this embodiment, a PPDU including a PR frame can be transmitted on the primary 40 MHz.

[0194] Since the present embodiment can transmit a PPDU including a PR on a primary channel of the largest available size that does not include a punctured channel, it can be expected to have the same effect as not considering puncturing in a PPDU including a CTS during the existing HE MU-RTS / CTS exchange operation. On the other hand, similar to the existing EHT MU-RTS / CTS exchange operation in which puncturing is allowed in a PPDU including a CTS, a PPDU including a PR can be transmitted on a primary channel without restriction as in the above-described embodiments 2 to 5.

[0195] Example 7

[0196] In the above-described embodiments 3 to 5, examples are included of restricting a PPDU including a PR from being transmitted when the operating bandwidth of the STA is smaller than the bandwidth of the DL PPDU or smaller than a specific bandwidth. These examples correspond to examples that take into account preventing throughput degradation of DL PPDU transmission that is resumed after the end of the preemption procedure. Specifically, when the bandwidth used in transmission of a PR frame or subsequent data (e.g., LL traffic) transmission is smaller than the bandwidth / specific bandwidth of the DL PPDU, a channel corresponding to the difference may be occupied by an OBSS, etc., and problems such as throughput degradation may occur in which the channel occupied by the OBSS cannot be used in DL PPDU transmission that is resumed after the end of the preemption procedure.

[0197] As in the examples above, limiting PR frame transmissions defeats the original purpose of the preemption procedure, which is to expedite transmission of LL traffic and the like. Therefore, a method for preventing OBSS and other traffic from occupying remaining channels without limiting PR frame transmissions is described below.

[0198] This embodiment assumes a situation where only STA(s) with an operating bandwidth less than or equal to the bandwidth of a DL PPDU or less than a specific bandwidth recognize the presence of data (e.g., LL traffic) and participate in the preemption procedure (i.e., transmit PR frames). In this case, in order to guarantee the bandwidth of the DL PPDU or a specific bandwidth, one or more third-party STAs may participate in the preemption-based transmission.

[0199] Here, a third-party STA may correspond to an STA that has not transmitted a PR frame (and an NFR frame), and is referred to as a non-PR STA to distinguish it from an STA that has transmitted a PR frame (and an NFR frame) (hereinafter referred to as a PR STA).

[0200] When PR STA(s) have an operating bandwidth less than the bandwidth / specific bandwidth of the DL PPDU, information for allocating specific RU / MRU of the TB PPDU to non-PR STA(s) may be added to a trigger frame including information for transmission of a TB PPDU containing data (e.g., LL traffic) of the PR STA(s) (e.g., information for RU / MRU allocated to each PR STA(s)). Here, the RU / MRU for the non-PR STA(s) may be allocated to a channel having a size corresponding to the difference between the bandwidth / specific bandwidth of the DL PPDU and the operating bandwidth of the PR STA(s). Accordingly, TB PPDUs from PR STA(s) and non-PR STA(s) may be transmitted on a bandwidth equal to the bandwidth / specific bandwidth of the DL PPDU.

[0201] For example, the user info field of the trigger frame may include information about RUs / MRUs allocated to each of the PR STA(s) and non-PR STA(s). Accordingly, each of the non-PR STA(s) may transmit a TB PPDU including a dummy signal or user data (e.g., non-LL traffic) in the RU / MRU allocated to it. A specific bit in the trigger frame may be set to 0 or 1 to indicate whether to transmit a dummy signal. In addition, each of the PR STA(s) may transmit a TB PPDU including data (e.g., LL traffic) in the RU / MRU allocated to it. That is, based on the trigger frame, the PR STA(s) and the non-PR STA(s) may transmit a TB PPDU together.

[0202] Here, although a non-PR STA is instructed to send a dummy signal in the allocated RU / MRU, if it has user data to transmit to the AP (e.g., non-LL traffic or LL traffic), it may include information indicating that it is not a dummy signal in the PHY header of the TB PPDU and transmit a TB PPDU including the user data in the allocated RU / MRU. The field indicating that it is not transmitting a dummy signal may be included in the U-SIG of the TB PPDU, etc. In this case, although the content of the U-SIG of the TB PPDU transmitted by the non-PR STA may be different from the content of the U-SIG of the TB PPDU transmitted by other STAs, the 20MHz channel overlapping with the RU / MRU allocated to the non-PR STA is transmitted only by the non-PR STA, and therefore the AP can successfully decode different U-SIGs in different 20MHz channels.

[0203] Additionally or alternatively, random access by any third-party STA may be allowed on the remaining channels / RUs / MRUs other than those allocated to PR STA(s) in a TB PPDU of the same bandwidth / specific bandwidth as that of the DL PPDU. For this purpose, information on uplink OFDMA-based random access (UORA) may be included in the trigger frame. Alternatively, information allowing random access in a method other than the conventional UORA method may be included in the trigger frame.

[0204] To support preemption not defined in existing wireless LAN systems, accurate and efficient preemption requests and subsequent preemption operations can be performed based on various examples of the present disclosure for transmission bandwidth and / or preamble puncturing applied to preemption requests.

[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 is 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 method performed by a first station (STA) in a wireless local area network (WLAN) system, the method comprising: A step of receiving a first physical layer protocol data unit (PPDU) including information related to preemption from a second STA, wherein the first PPDU is transmitted on a first bandwidth; and A method comprising the step of transmitting a second PPDU including a preemption request to the second STA on the second bandwidth based on availability of a second bandwidth based on at least one of the first bandwidth, the first operating bandwidth of the first STA, or a specific bandwidth.

2. In paragraph 1, A method in which information related to the above preemption is 1-bit information indicating whether preemption is permitted.

3. In paragraph 1, Based on the first operating bandwidth being greater than or equal to the first bandwidth, the second bandwidth is equal to the first bandwidth, or Based on the first operating bandwidth being less than the first bandwidth, the second bandwidth is equal to the first operating bandwidth, or A method in which the second PPDU is not transmitted based on the first operating bandwidth being less than the first bandwidth.

4. In paragraph 1, Based on the first operating bandwidth being greater than or equal to the specific bandwidth, the second bandwidth is greater than or equal to the specific bandwidth, or Based on the first operating bandwidth being less than the specific bandwidth, the second bandwidth is equal to the first operating bandwidth, or A method wherein the second PPDU is not transmitted based on the first operating bandwidth being less than the specific bandwidth.

5. In paragraph 1, The specific bandwidth is indicated by 3-bit information included in the first PPDU, and the 3-bit information indicates one of bandwidth candidates including 20 MHz, 40 MHz, 80 MHz, 160 MHz, and 320 MHz, or The specific bandwidth is indicated by 2-bit information included in the first PPDU, a first value of the 2-bit information indicates the first bandwidth, a second value of the 2-bit information indicates a bandwidth of 1 / 2 of the first bandwidth, a third value of the 2-bit information indicates a bandwidth of 1 / 4 of the first bandwidth, and a fourth value of the 2-bit information indicates a bandwidth of 1 / 8 of the first bandwidth, or A method wherein the specific bandwidth is indicated by 1-bit information included in the first PPDU, a first value of the 1-bit information indicates the first bandwidth, and a second value of the 1-bit information indicates a bandwidth of half of the first bandwidth.

6. In paragraph 1, Based on the first operating bandwidth being less than the first bandwidth, or the first operating bandwidth being less than the specific bandwidth: The second PPDU including the preemption request is transmitted from the first STA on the second bandwidth which is the same as the first operating bandwidth, A method wherein a trigger frame for the first STA and one or more third STAs is transmitted from the second STA.

7. In paragraph 6, A method wherein the at least one third STA is one or more STAs selected by the second STA from among STAs for which an operating bandwidth equal to or greater than the specific bandwidth is set without transmitting a preemption request.

8. In paragraph 6, A method in which low latency data from the first STA is transmitted to the second STA through a third PPDU transmitted based on the trigger frame, and dummy data or user data from each of the one or more third STAs is transmitted to the second STA.

9. In paragraph 8, A method wherein information indicating whether each of the one or more third STAs transmits dummy data or user data is included in the third PPDU.

10. In paragraph 6, A method wherein the trigger frame includes information about uplink orthogonal frequency division multiple access (OFDMA)-based random access (UORA) from one or more other STAs.

11. In paragraph 1, The above first STA is a non-access point (non-AP) STA, A method wherein the above second STA is an AP STA.

12. In a first station (STA) device in a wireless local area network (WLAN) system, the device: 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 PPDU (physical layer protocol data unit) including information related to preemption from a second STA through the one or more transceivers, wherein the first PPDU is transmitted on a first bandwidth; and A device configured to transmit a second PPDU including a preemption request to the second STA through the one or more transceivers on the second bandwidth based on availability of a second bandwidth based on at least one of the first bandwidth, the first operating bandwidth of the first STA, or a specific bandwidth.

13. A method performed by a second station (STA) in a wireless local area network (WLAN) system, the method comprising: A step of transmitting a first PPDU (physical layer protocol data unit) including information related to preemption on a first bandwidth; and A method comprising: receiving a second PPDU including a preemption request transmitted from the first STA on the second bandwidth based on availability of a second bandwidth based on at least one of the first bandwidth, the first operating bandwidth of the first STA, or a specific bandwidth.

14. In a second station (STA) device in a wireless local area network (WLAN) system, the device: 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 PPDU (physical layer protocol data unit) including information related to preemption through the one or more transceivers on the first bandwidth; and A device configured to receive a second PPDU including a preemption request transmitted from the first STA on the second bandwidth through the one or more transceivers based on availability of the second bandwidth based on one or more of the first bandwidth, the first operating bandwidth of the first STA, or a specific bandwidth.

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 that, when executed by said one or more processors, perform a method according to any one of claims 1 to 11.

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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