Method and device for transmitting / receiving traffic in wireless LAN system

Abstract

Disclosed are a method and a device for operating in a wireless LAN system. A method performed by a first station (STA) in a wireless LAN system, according to one embodiment of the present disclosure, comprises the steps of: transmitting, to a second STA, a first physical layer protocol data unit (PPDU) including first information for triggering the transmission of information related to first low latency traffic (LLT); performing a first clear channel assessment (CCA) during a first inter-frame space; and transmitting, to the second STA, a second PPDU including the first information after performing a recovery procedure, on the basis that the result of the first CCA is BUSY, wherein the second PPDU may be transmitted to the second STA by the first STA on the basis that the result of the first CCA is IDLE.

Description

Method and device for transmitting and receiving traffic in a wireless LAN system

[0001] The present disclosure relates to a method and device for transmitting and receiving traffic and information related to traffic 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 relates to a method and device for transmitting and receiving traffic in a wireless LAN system.

[0005] The technical problem of the present disclosure relates to a method and device for transmitting information for preemption operation related to low-latency traffic 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] In one embodiment of the present disclosure, a method performed by a first station (STA) includes the steps of: transmitting a first physical layer protocol data unit (PPDU) to a second STA, the first PPDU including first information for triggering transmission of information related to first low latency traffic (LLT); performing a first clear channel assessment (CCA) during a first inter-frame space; and transmitting a second PPDU including the first information to the second STA after performing a recovery procedure based on a result of the first CCA being BUSY, wherein the second PPDU can be transmitted by the first STA to the second STA based on a result of the first CCA being IDLE.

[0008] In one embodiment of the present disclosure, a method performed by a second STA includes the steps of: receiving, from the first STA, a first physical layer protocol data unit (PPDU) including first information for triggering transmission of information related to first low latency traffic (LLT); and transmitting, to the first STA, information related to the first LLT based on a second PPDU including the first information being received from the first STA and the second STA having the first LLT, wherein the second PPDU transmission may be performed based on a first clear channel assessment (CCA) result of the first STA.

[0009] According to various embodiments of the present disclosure, a method and device for transmitting and receiving traffic in a wireless LAN system can be provided.

[0010] The technical problem of the present disclosure relates to a method and device for transmitting information for low-latency traffic preemption operation in a wireless LAN system.

[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 drawing showing an exemplary format of a trigger frame to which the present disclosure can be applied.

[0021] Figure 9 is a diagram for explaining issues related to LLT transmission in DL (downlink) TXOP.

[0022] Figure 10 is a diagram for explaining issues related to LLT transmission in UL (uplink) TXOP.

[0023] FIG. 11 is a flowchart for explaining the operation of a first STA according to one embodiment of the present disclosure.

[0024] FIG. 12 is a flowchart for explaining the operation of a second STA according to one embodiment of the present disclosure.

[0025] FIG. 13 is a diagram for explaining a method for an STA and an AP to transmit and receive LLT according to one embodiment of the present disclosure.

[0026] FIG. 14 is a diagram illustrating a method for transmitting LLT information using an HT control field according to one embodiment of the present disclosure.

[0027] FIG. 15 is a diagram for explaining the configuration of a BA frame including LLT information according to one embodiment of the present disclosure.

[0028] FIG. 16 is a diagram for explaining a procedure for transmitting and receiving a BA frame including LLT information according to one embodiment of the present disclosure.

[0029] FIG. 17 is a diagram for explaining the configuration of an LLT BA frame and a procedure for transmitting and receiving an LLT BA frame according to one embodiment of the present disclosure.

[0030] FIG. 18 is a diagram for explaining the configuration of an LLT BA frame for multi-TID and the transmission and reception procedure of LLT BA according to one embodiment of the present disclosure.

[0031] FIG. 19 is a diagram for explaining a method of transmitting LLT information using a MAC header according to one embodiment of the present disclosure.

[0032] FIG. 20 is a diagram for explaining the configuration of a TRS control field according to one embodiment of the present disclosure.

[0033] FIG. 21 is a diagram illustrating a method of triggering LLT information through a control field according to one embodiment of the present disclosure.

[0034] FIG. 22 is a diagram illustrating a method of triggering LLT information using an LLT poll trigger frame according to one embodiment of the present disclosure.

[0035] FIG. 23 is a diagram illustrating a method for triggering transmission of LLT information through a user information field of a trigger frame according to one embodiment of the present disclosure.

[0036] FIG. 24 is a diagram for explaining a procedure for transmitting LLTI using an LLT poll frame according to one embodiment of the present disclosure.

[0037] FIG. 25 is a diagram illustrating a method for transmitting LLTI through an LLT poll frame according to one embodiment of the present disclosure.

[0038] FIG. 26 is a diagram for explaining a method of transmitting LLTI using a PHY header according to one embodiment of the present disclosure.

[0039] FIG. 27 is a diagram for explaining a method of transmitting LLTI using a PHY header according to one embodiment of the present disclosure.

[0040] FIG. 28 is a diagram for explaining a method of transmitting LLTI using a PHY header according to one embodiment of the present disclosure.

[0041] FIG. 29 is a diagram illustrating a method for transmitting LLT information using an HT control field (e.g., LLT information control of A-control) according to one embodiment of the present disclosure.

[0042] FIG. 30 is a diagram for explaining a procedure for transmitting and receiving a BA frame including LLT information, according to one embodiment of the present disclosure.

[0043] FIG. 31 is a diagram for explaining the configuration of an LLT BA frame and a procedure for transmitting and receiving an LLT BA frame according to one embodiment of the present disclosure.

[0044] FIG. 32 is a diagram for explaining the configuration of an LLT BA frame for multi-TID and the transmission and reception procedure of LLT BA as an embodiment of the present disclosure.

[0045] FIG. 33 is a diagram for explaining a method of transmitting LLT information using a MAC header according to one embodiment of the present disclosure.

[0046] FIG. 34 is a method for transmitting and receiving LLT information through an existing or new frame according to one embodiment of the present disclosure.

[0047] FIG. 35 is a diagram illustrating a method for triggering LLT information transmission using a control field according to one embodiment of the present disclosure.

[0048] FIG. 36 is a diagram for explaining a method for triggering LLT information transmission using a PHY header according to one embodiment of the present disclosure.

[0049] FIG. 37 is a diagram illustrating a method for triggering LLT to a TXOP responder according to one embodiment of the present disclosure.

[0050] FIG. 38 is a diagram illustrating a method for triggering LLT to a TXOP responder according to one embodiment of the present disclosure.

[0051] FIG. 39 is a diagram for explaining an LLT transmission trigger method using a triggering frame according to one embodiment of the present disclosure.

[0052] FIG. 40 is a diagram for explaining an LLT transmission trigger method using a triggering frame according to one embodiment of the present disclosure.

[0053] FIG. 41 is a diagram illustrating a method for triggering LLT to a TXOP responder according to one embodiment of the present disclosure.

[0054] FIG. 42 is a diagram for explaining a procedure when LLT information is not transmitted according to one embodiment of the present disclosure.

[0055] FIG. 43 is a diagram illustrating a method for handling failures related to LLT information according to one embodiment of the present disclosure.

[0056] Figure 44 is a diagram illustrating a case where a failure related to LLT information occurs.

[0057] FIG. 45 is a diagram illustrating a method for handling failures related to LLT information according to one embodiment of the present disclosure.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] Below, technical features to which examples of the present disclosure can be applied are described.

[0065] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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).

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0079] 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.

[0080] 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.

[0081] 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).

[0082] 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.

[0083] 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.

[0084] 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).

[0085] 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.

[0086] 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.

[0087] In addition to the structure of the DS described above, an extended service set (ESS) may be established to provide wider coverage.

[0088] 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.

[0089] 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.

[0090] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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, 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.

[0101] 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.

[0102] 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.

[0103] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0104] 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.

[0105] 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).

[0106] Referring to Fig. 4, an operation based on a random backoff period is described. When a medium that was occupied / busy changes to an idle state, multiple STAs can attempt to transmit data (or frames). To minimize collisions, each STA can select a random backoff count, wait for the corresponding slot time, and then attempt transmission. The random backoff count has a pseudo-random integer value and can be determined as one of the values ​​in the range of 0 to CW. Here, CW is a contention window parameter value. The CW parameter is given an initial value of CWmin, but can take a doubled value in case of transmission failure (e.g., when an ACK for a transmitted frame is not received). When the CW parameter value becomes CWmax, data transmission can be attempted while maintaining the CWmax value until data transmission is successful, and if data transmission is successful, it is reset to the CWmin value. The CW, CWmin, and CWmax values ​​are 2. n It is desirable to set it to -1 (n=0, 1, 2, ...).

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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).

[0129] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0130] 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)).

[0131] 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).

[0132] 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)).

[0133] An example of a HE PPDU format (IEEE 802.11ax) additionally includes RL-SIG (Repeated L-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and PE (Packet Extension) fields in addition to the basic PPDU format (Fig. 7(d)). Depending on specific examples of the HE PPDU format, some fields may be excluded or their lengths may vary. For example, the HE-SIG-B field is included in the HE PPDU format for multi-users (MUs), but the HE PPDU format for single users (SUs) does not include the HE-SIG-B. In addition, the HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may vary to 8us. The HE ER (Extended Range) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may vary to 16us. For example, RL-SIG can be configured identically to L-SIG. The receiving STA can determine that the received PPDU is a HE PPDU or an EHT PPDU, described later, based on the presence of RL-SIG.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.).

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.).

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] RUs of different sizes can be defined, such as 26-ton RU, 52-ton RU, 106-ton RU, 242-ton RU, 484-ton RU, 996-ton RU, 2X996-ton RU, 3X996-ton RU, etc. A multiple RU (MRU) is distinguished from multiple individual RUs and corresponds to a group of subcarriers consisting of multiple RUs. For example, one MRU can be defined as 52+26-tons, 106+26-tons, 484+242-tons, 996+484-tons, 996+484+242-tons, 2X996+484-tons, 3X996-tons, or 3X996+484-tons. Additionally, multiple RUs constituting one MRU may or may not be consecutive in the frequency domain.

[0157] 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.

[0158] 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.

[0159] FIG. 8 is a drawing showing an exemplary format of a trigger frame to which the present disclosure can be applied.

[0160] A trigger frame may allocate resources for the transmission of one or more TB PPDUs and request the transmission of TB PPDUs. The trigger frame may also include other information required by the STA transmitting the TB PPDU in response. The trigger frame may include common information and a user information list field in the frame body.

[0161] The common information field may include information that is common to one or more TB PPDU transmissions requested by a trigger frame, such as trigger type, UL length, presence of a subsequent trigger frame (e.g., More TF), whether CS (channel sensing) is required, UL BW (bandwidth), etc. Fig. 8 illustrates an example of an EHT variant common information field format.

[0162] The 4-bit trigger type subfield can have values ​​from 0 to 15. Among them, the values ​​0, 1, 2, 3, 4, 5, 6, and 7 of the trigger type subfield are defined to correspond to basic, Beamforming Report Poll (BFRP), multi user-block acknowledgement request (MU-BAR), multi user-request to send (MU-RTS), Buffer Status Report Poll (BSRP), groupcast with retries (GCR), MU-BAR, Bandwidth Query Report Poll (BQRP), and NDP Feedback Report Poll (NFRP), respectively, and the values ​​8 to 15 are defined as reserved.

[0163] Among the common information, the trigger dependent common info subfield may include information that is optionally included based on the trigger type.

[0164] A special user info field may be included within the trigger frame. The special user info field does not contain user-specific information, but rather extended common information not provided in the common information field.

[0165] A user information list contains zero or more user information fields. Figure 8 illustrates an example of an EHT variant user information field format.

[0166] The AID12 subfield basically indicates that it is a user information field for an STA with the corresponding AID. In addition, if the AID12 field has a predetermined specific value, it may be utilized for other purposes, such as allocating a random access (RA)-RU, or being configured in the form of a special user information field. The special user information field is a user information field that does not contain user-specific information, but contains extended common information not provided in the common information field. For example, the special user information field can be identified by the AID12 value of 2007, and the special user information field flag subfield within the common information field can indicate whether the special user information field is included.

[0167] The RU allocation subfield can indicate the size and location of an RU / MRU. For this purpose, the RU allocation subfield can be interpreted together with the PS160 (primary / secondary 160MHz) subfield of the user information field, the UL BW subfield of the common information field, etc.

[0168] HT control field

[0169] Below, the HT control field included in the MAC header described with reference to FIG. 6 will be described in more detail.

[0170] The HT Control field may be present in a control wrapper frame, and may be present in QoS data, QoS Null, and management frames determined by the +HTC subfield of the frame control field.

[0171] An STA that supports the HT control field receiving a Control Wrapper frame may treat it as if it had received a frame of a subtype of a Wrapped frame. A HE STA may not transmit a Control Wrapper frame to another HE STA.

[0172] The HT control field may have a format as shown in Table 1 below.

[0173]

[0174] As disclosed in Table 1, the HT Control field may include three variants (e.g., HT variant, VHT variant, and HE variant). The variant formats may be distinguished by the values ​​of the first bit (B0) and second bit (B1) of the HT Control field.

[0175] The HT variant HT control field may include an HT control middle subfield, and the VHT variant HT control field may include a VHT control middle subfield. The VHT control middle subfield may include an MRQ subfield, an MSI / STBC subfield, an MFSI / GID-L subfield, an MFB subfield, a GID-H subfield, a coding type subfield, an FB Tx type subfield, and an unsolicited MFB subfield.

[0176] The HE variant HT control field may include an aggregated control subfield. The A-control subfield may include a control list subfield of variable length and zero or more padding subfields. The control list may include one or more control subfields. A control subfield may include a 4-bit control ID subfield and a control information subfield of variable length.

[0177] The Control ID subfield can indicate the type of information conveyed in the Control Information subfield. The length of the Control Information subfield can be fixed for each value of the Control ID subfield that is not reserved. The values ​​of the Control ID subfield and the associated lengths of the Control Information subfield can be defined as shown in Table 2 below.

[0178] Control ID Value Meaning Length of Control Information Subfield (bits) 0 Triggered Response Scheduling (TRS) 261 Operating Mode (OM) 122 HE Link Adaptation (HLA) 263 Buffer Status Report (BSR) 264 UL Power Headroom (UPH) 85 Bandwidth Query Report (BQR) 106 Command and Status (CAS) 87 EHT OM 68 Single Response Scheduling (SRS) 109 AP Assistance Request (ARR) 2010-14 Reserved - 15 ONES (ones need expansion surely) 26

[0179] Information corresponding to control ID values ​​0 to 6 may be defined in the A-control subfield of the HE variant HT control field. Information corresponding to control ID values ​​7 to 9 may be newly defined information for the EHT STA. In addition, information corresponding to control ID value 10 (i.e., AAR) may correspond to control 1D value 9. In addition, when a padding subfield exists in the A-control subfield of the HE variant HT control field, the padding subfield follows the last control subfield and may be set to a sequence of zeros so that the length of the A-control subfield carried in the HT control field becomes 30 bits.

[0180] Information transmission procedure for low-latency traffic preemption

[0181] In a basic wireless LAN system, STAs (e.g., non-AP STAs and / or APs) can perform channel access operations to transmit frames containing traffic. For example, the AP and / or non-AP STAs can acquire a transmission opportunity (TXOP) via Enhanced Distributed Channel Access (EDCA) and transmit frames within the acquired TXOP. As another example, a non-AP STA can transmit a frame in response to a trigger frame received from the AP.

[0182] That is, when specific traffic is input / generated into the transmission queue of an STA, the STA must perform channel access to transmit the specific traffic, thereby occupying the channel and / or obtaining a TXOP. At this time, it is assumed that traffic requiring a significantly low delay (i.e., low-latency traffic) is input / generated into the transmission queue of the STA. In order for the STA to transmit the low-latency traffic, contention for channel access with other STAs is inevitable, and there is a problem that if another STA has already obtained a TXOP, rapid transmission of the low-latency traffic is not guaranteed.

[0183] In describing the present disclosure, traffic requiring low latency (e.g., traffic that must be successfully transmitted within X ms) is referred to as low latency traffic (LLT).

[0184] Figure 9 is a diagram for explaining issues related to LLT transmission in DL (downlink) TXOP.

[0185] Specifically, as illustrated in FIG. 9, when an AP (i.e., a TXOP holder) acquires a (DL) TXOP through channel access and then performs frame exchange with STA 1 (i.e., a TXOP responder), the LLT to be transmitted to STA 2 from the AP may arrive at time T_1. STA 2 may set NAV due to the TXOP of the AP, or determine the channel status as BUSY due to the frame exchange between the AP and STA 1.

[0186] Therefore, STA 2 can transmit LLT after performing a backoff process again after the AP's TXOP. At this time, the length of the AP's TXOP may be long, and there is a possibility that another STA will acquire the TXOP depending on the competition result when STA 2 performs a backoff after the AP's TXOP. Accordingly, STA 2's LLT transmission may be significantly delayed, and there is a possibility that the LLT requirement may not be satisfied.

[0187] Figure 10 is a diagram for explaining issues related to LLT transmission in UL (uplink) TXOP.

[0188] Specifically, as illustrated in FIG. 10, when STA 1 (i.e., TXOP holder) acquires (UL) TXOP through channel access and then performs frame exchange with AP (i.e., TXOP responder), LLT to be transmitted to STA 2 may arrive at AP at time T_1. Since AP is performing frame exchange within STA 1's TXOP, it cannot transmit LLT to STA 2. Therefore, AP can transmit LLT to STA 2 after performing back-off process again after STA 1's TXOP.

[0189] At this time, the length of STA 1's TXOP may be long, and when the AP performs backoff after STA 1's TXOP, there is a possibility that another STA may acquire the TXOP based on the competition results. Accordingly, the AP's LLT transmission may be significantly delayed, and there is a possibility that the LLT requirements may not be met.

[0190] As in the examples described with reference to FIGS. 9 and 10, when an LLT that an STA needs to transmit quickly (i.e., an LLT with transmission-related requirements) arrives, there is a possibility that the STA may not be able to satisfy the requirements and transmit the LLT due to a TXOP length already acquired by another STA or a channel access delay caused by competition with other STAs. The present disclosure describes a method for resolving the above-described problems.

[0191] The names of the procedures and / or parameters described in this disclosure may be changed, and an STA may include a non-AP STA or an AP STA. In addition, in describing this disclosure, a RU (resource unit) may mean an RU or M (multiple) RU.

[0192] FIG. 11 is a flowchart illustrating the operation of a first STA according to one embodiment of the present disclosure. In FIGS. 11 and 12 , the first STA may be an AP and the second STA may be a non-AP STA. However, this is merely an example, and the first STA may be a non-AP STA and the second STA may be an AP. In other words, the first STA and the second STA may be either an AP or a non-AP STA.

[0193] The first STA may transmit a first PPDU containing first information for triggering transmission of information related to the first LLT to the second STA (S1110).

[0194] For example, a first STA may transmit first information to a second STA for triggering transmission of information related to a first LLT within its TXOP (i.e., the first STA is a TXOP holder). The first information may include at least one of information about a bandwidth of a fourth PPDU including information related to the first LLT, a PPDU type of the fourth PPDU, data or a modulation and coding scheme (MCS) of the fourth PPDU, or a trigger mode for triggering transmission of information related to the first LLT. That is, the first STA may transmit first information for configuring the fourth PPDU used when transmitting information related to the first LLT to the second STA.

[0195] Here, the information related to the first LLT may include at least one of information on the existence of the first LLT, identification information of the first LLT, information on the time at which the first LLT should be completed for transmission, and information on the amount of the first LLT.

[0196] The first STA can perform a first clear channel assessment (CCA) during the first inter-frame space (S1120).

[0197] Here, the first inter-frame space may include one of a short inter-frame space (SIFS) or a point coordination function inter-frame space (PIFS). And, the first CCA may include at least one of an energy detection (ED) operation for detecting a signal above a certain intensity or a guard interval (GI) detection operation for detecting a wireless signal.

[0198] For example, if information related to the first LLT is received from the second STA during the first inter-frame interval, the first STA may transmit a third PPDU to the second STA to trigger the first LLT transmission. That is, if information related to the first LLT is received during the first CCA, the first STA may trigger the first LLT transmission.

[0199] As another example, based on the fact that information related to the first LLT is not received from the second STA during the first inter-frame interval, the first STA may transmit the second PPDU to the second STA based on the first CCA result. That is, the first STA may determine how to transmit the second PPDU based on the first CCA result.

[0200] For example, based on the first CCA result being BUSY, the first STA may perform a recovery procedure and then transmit a second PPDU including the first information to the second STA (S1130). That is, if the first CCA result is BUSY, the first STA may determine that the transmission of the first PPDU has failed. The first STA may perform a recovery operation to resolve the PPDU transmission failure within its TXOP. Then, the first STA may transmit a second PPDU including the first information that triggers the transmission of information related to the first LLT to the second STA again.

[0201] For example, after the recovery procedure is performed, the first STA may perform a second CCA. Based on the second CCA result being idle, the first STA may transmit a second PPDU to the second STA.

[0202] As an example of the present disclosure, based on the first CCA result being IDLE, the first STA can immediately transmit the second PPDU to the second STA.

[0203] If information related to the first LLT is received from the second STA based on the second PPDU, the first STA may transmit a third PPDU to the second STA, which triggers transmission of the first LLT based on the information related to the first LLT. Then, the first STA may receive the first LLT from the second STA.

[0204] Each of the operations of the first STA and the second STA described above may be performed within the TXOP of the first STA. That is, at least one of the first PPDU, the second PPDU, information related to the first LLT, or the first LLT may be transmitted and received within the TXOP of the first STA.

[0205] The method described in the example of FIG. 11 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 transmit a first PPDU including first information for triggering transmission of information related to a first LLT to a second STA via one or more transceivers (106). The one or more processors (102) may perform a first CCA during the first inter-frame interval. Based on the first CCA result being BUSY, the one or more processors (102) may perform a recovery procedure and then transmit a second PPDU including the first information to the second STA via one or more transceivers (106).

[0206] Furthermore, one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 11 or the examples described below when executed by one or more processors (102).

[0207] FIG. 12 is a flowchart for explaining the operation of a second STA according to one embodiment of the present disclosure.

[0208] The second STA may receive a first PPDU including first information for triggering transmission of information related to the first LLT from the first STA (S1210).

[0209] Based on not possessing the first LLT, the second STA may not transmit information related to the first LLT to the first STA during the first inter-frame interval. That is, if the first information for triggering transmission of information related to the first LLT is received in a state where the first LLT has not occurred, the second STA may not transmit information related to the first LLT.

[0210] Based on the second PPDU including the first information being received from the first STA and the existence of the first LLT, the second STA can transmit information related to the first LLT to the first STA (S1220).

[0211] At this time, the second PPDU can be transmitted to the second STA based on the first CCA result of the first STA. That is, if the first LLT occurs during the first frame interval after step S1210, the second STA can receive the second PPDU from the first STA based on the first CCA result.

[0212] The method described in the example of FIG. 12 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 receive a first PPDU including first information for triggering transmission of information related to a first LLT from a first STA via one or more transceivers (106). Based on the second PPDU including the first information being received from the first STA and the presence of the first LLT, the one or more processors (202) may receive information related to the first LLT from the first STA via one or more transceivers (206).

[0213] Furthermore, one or more memories (204) of the second device (200) may store commands for performing the method described in the example of FIG. 13 or the examples described below when executed by one or more processors (202).

[0214] Below, we will specifically describe the information transmission method for preempting low-latency traffic.

[0215] Example 1

[0216] Example 1 relates to a procedure for reporting LLT information.

[0217] FIG. 13 is a diagram illustrating a method for an STA to report LLT information to an AP according to one embodiment of the present disclosure. In FIG. 13 , "LLT TX need" means that an LLT that the STA must transmit quickly exists / occurs. For example, "LLT TX need" may mean that an LLT has been input / occurred in the STA or that an LLT that must be transmitted quickly according to a requirement exists.

[0218] Here, the operations of the AP and the STA in FIG. 13 can be replaced with the operations of the STA and the AP, respectively. That is, the operation of the AP in FIG. 12 can be replaced with the operation of another STA, and the operation of the STA in FIG. 13 can be replaced with the operation of the AP.

[0219] As illustrated in FIG. 13, an AP may transmit trigger information to one or more STAs to enable transmission of LLT information via a PPDU. That is, the PPDU may include a trigger frame for requesting / triggering transmission of LLT information. Additionally, the PPDU may include frames addressed to one or more STAs (e.g., QoS data frames, etc.).

[0220] An STA that receives a PPDU / frame that triggers LLT information may transmit a frame / PPDU containing LLT information. A predefined time (e.g., SIFS, PIFS) may exist between the PPDU / frame that triggers LLT information and the frame containing LLT information.

[0221] An AP that receives LLT information from one or more STAs can transmit a frame (e.g., a trigger frame) that enables LLT transmission to one or more STAs. One or more STAs that receive the frame can transmit a frame / PPDU containing LLT to the AP.

[0222] Additionally or alternatively, one or more STAs may transmit LLT information to the AP even if they do not receive a PPDU / frame that triggers LLT information. For example, in FIG. 13, LLT information may be included in a frame / PPDU containing LLT transmitted by one STA.

[0223] Example 1-1

[0224] Example 1-1 relates to one or more types of information included in LLT information transmitted by an STA.

[0225] LLT information may include LLT presence information, LLT identification information, delay information, and / or amount of LLT information.

[0226] For example, the LLT presence information may indicate that an STA currently has an LLT to transmit. Additionally or alternatively, the LLT presence information may indicate within a TXOP of a specific STA whether the STA requests / desires to transmit an LLT.

[0227] The LLT presence information may be supported by a field having 1 bit (e.g., an LLT presence information field). For example, when the LLT presence information field value is set to 1 (or 0), this may indicate that an LLT that the STA should currently transmit exists or that the STA requests / wants to transmit LLT within the TXOP of the specific STA. For example, when the LLT presence information field value is set to 0 (or 1) or the field is reserved, this may indicate that an LLT that the STA should currently transmit does not exist or that the STA does not request / wants to transmit LLT within the TXOP of the specific STA.

[0228] As another example, the LLT identification information may include one or more ID information about the LLT to be transmitted. That is, the LLT identification information may include information about the LLT that needs to be transmitted. As an example, the LLT identification information may utilize a traffic identifier (TID). If the LLT corresponds to at least one of TIDs 0 to 7, the field indicating the LLT identification information may be set to 3 bits, and if the LLT corresponds to at least one of TIDs 8 to 15, the field indicating the LLT identification information may be set to 4 bits.

[0229] As another example of the present disclosure, a new LLT ID may be defined to indicate the identification information of the LLT. For example, the LLT ID may be defined as an ID to distinguish the LLT for each TID. For example, the LLT may be a 2-tuple. <TID, LL ID)로 분류될 수 있다. 예로, TID 6에 대해 LL ID 0 내지 3이 할당되는 경우, TID 6에 대응하는 LL 트래픽은 <TID 6, LL ID 0>can be classified into.

[0230] Additionally or alternatively, a bitmap may be defined to accommodate LLTs for one or more IDs. That is, the LLT identification information may consist of a bitmap representing LLT IDs. For example, if a total of X LLT IDs are defined, the bitmap may be configured to indicate at most X LLT IDs.

[0231] For example, the delay information may include information about when the LLT should be transmitted.

[0232] For example, the delay information may include the time from the time the LLT information is transmitted or the time at which the transmission is completed until the time at which the LLT should be successfully transmitted. In this case, the delay information may indicate the time in μs.

[0233] Additionally or alternatively, the delay information may indicate the point in time at which the LLT is expected to be successfully transmitted. For example, the delay information may indicate the point in time at which the LLT is expected to be successfully transmitted based on an absolute time, a timestamp (TSF).

[0234] Additionally or alternatively, assume that there is an LLT for more than one ID. That is, if there is an LLT for each of multiple IDs, the ID whose transmission should be completed earlier among the multiple IDs is identified, and the delay information may include the time at which the transmission should be completed for that ID.

[0235] Additionally or alternatively, if there is an LLT for each of the plurality of IDs, the delay information may include the point in time at which each of the plurality of IDs should complete transmission.

[0236] For example, the amount of LLT information may include information about the amount of LLT currently to be transmitted. For example, the amount of LLT information may be configured in bytes.

[0237] Additionally or alternatively, if there is an LLT for more than one ID, the LLT quantity information may indicate the LLT quantity for all IDs. For example, the LLT quantity information may be the sum of the LLT quantities for each of all IDs.

[0238] Additionally or alternatively, if LLT exists for more than one ID, the amount information of LLT may indicate the amount of LLT for each ID.

[0239] Additionally or alternatively, assume that TID is utilized for LLT. In this case, the amount information of LLT may indicate the amount of LLT for each AC (access category) to which the TID belongs. For example, if TID X and TID Y belong to AC 1, the amount information of LLT may indicate the sum of the LLT amounts of TID X and TID Y respectively as the amount of LLT for AC 1.

[0240] Example 1-2

[0241] Embodiment 1-2 relates to a method for indicating / signaling LLT information. Specifically, LLT information can be indicated / signaled via an HT control field (Embodiment 1-2-1), a BA (black ack) frame (Embodiment 1-2-2), and a MAC header (Embodiment 1-2-3).

[0242] Example 1-2-1

[0243] In one embodiment of the present disclosure, LLT information may be transmitted and received via an HT control field (e.g., an A-control field). For example, LLT information may be included in a field defined as a new control type of the A-control field. The present disclosure refers to the control field for transmitting and receiving LLT information as an LLT information control field.

[0244] FIG. 14 illustrates a method for transmitting LLT information using an HT control field (e.g., LLT information control of A-control) according to an embodiment of the present disclosure. As illustrated in FIG. 14, an AP may first obtain a TXOP through an RTS / CTS exchange and then transmit a PPDU to STA 1. In this example, an A (aggregated)-MPDU containing QoS data frame(s) on the PPDU may be transmitted to STA 1.

[0245] The PPDU may include information that triggers STA 1 to transmit LLT information. STA 1, upon receiving the PPDU, may respond / transmit an LLT information control field including LLT information to the AP using an A-MPDU. The LLT information control field may be included in at least one of a BA frame, an additional QoS data frame, and a QoS null frame and may be responded / transmitted to the AP.

[0246] For example, if a HT control field is included in a BA frame, the HT control field (or BA frame) may be defined as a new control frame type or the +HTC field value of the MAC header may be set to 1. Accordingly, STA 1 may transmit LLT information to the AP simultaneously with ACK information for the data frame using the BA frame.

[0247] For example, if the ACK policy for MPDUs in a PPDU transmitted by the AP is a policy requiring an immediate response to a BA frame (e.g., implicit BAR), a BA frame (or BA information) may be present in the A-MPDU transmitted by STA 1. As another example, if the ACK policy for MPDUs in a PPDU transmitted by the AP is a policy not requiring an immediate response to a BA frame (e.g., ACK policy = BA), a BA frame (or BA information) may not be present in the A-MPDU transmitted by STA 1.

[0248] An AP that receives a PPDU / frame including LLT information from STA 1 can enable STA 1 to transmit LLT by transmitting a trigger frame to STA 1. At this time, STA 1 can include the LLT information in a response frame (e.g., A-MPDU) to the trigger frame. As an example of the present disclosure, STA 1 can transmit the LLT information to the AP together with a BA frame and / or a data frame.

[0249] Example 1-2-2

[0250] In one embodiment of the present disclosure, it is assumed that LLT information is triggered simultaneously with the transmission of a (QoS) data frame to a specific STA. If LLT exists on the specific STA, the specific STA can transmit the LLT information to the AP along with the BA frame. That is, instead of including the LLT information in another frame, the specific STA can include the LLT information in the BA frame.

[0251] As an example of the present disclosure, FIG. 15 is a diagram for explaining the configuration of a BA frame including LLT information.

[0252] As illustrated in (a) and (b) of FIG. 15, LLT information can be set / indicated through the reserved field of the BA control field regardless of the BA type of the BA frame. As another example, LLT information can be set on the 10th bit (B9) (i.e., no memory kept), the 11th bit (B10) (i.e., memory set on tag), and the 12th bit (B11) (i.e., management ACK) of the BA control field.

[0253] For example, as illustrated in (a) of FIG. 15, an LLT presence field may be set on the first bit (B0) of the BA control field.

[0254] As another example, as illustrated in (b) of FIG. 15, an LLT presence field may be set on the first bit (B0) of the BA control field, and LLT identification information may be set on at least one of the sixth bit (B5) to the ninth bit (B10) of the BA control field. At this time, the LLT identification information may include a TID for the LLT that currently requires transmission, and the TID_INFO field may include information about which TID the BA frame is transmitted for (i.e., information acknowledging the success or failure of one or more MPDUs of one TID).

[0255] FIG. 16 is a diagram for explaining a procedure for transmitting and receiving a BA frame including LLT information, according to one embodiment of the present disclosure.

[0256] The AP can first obtain a TXOP through a CTS / RTS exchange and then transmit a PPDU to STA 1. For example, the PPDU may include an A-MPDU containing a QoS data frame. STA 1 can then transmit a BA frame containing LLT information to the AP in response to the PPDU.

[0257] The BA frame may include BA information for ACKing the QoS data frame included in the A-MPDU. Additionally, LLT information may be included in the BA control field of the BA frame. For example, as illustrated in FIG. 15, the LLT information may be included in the BA control field. Accordingly, STA 1 may transmit ACK information and LLT information for the data frame together to the AP via the BA frame.

[0258] An AP that receives a BA frame containing LLT information from STA 1 can transmit a trigger frame to STA 1. STA 1 can transmit LLT to the AP based on the trigger frame. In the present disclosure, LLT information can be included in a BA frame regardless of the BA type.

[0259] Additionally or alternatively, a new type of BA frame may be defined or an existing type of BA frame may be utilized to include LLT information. In this disclosure, a BA frame defined to transmit LLT information is referred to as an LLT BA frame.

[0260] An LLT BA frame may additionally include an LLT information field in addition to the basic BA frame (e.g., a frame containing ACK information for a data frame). The LLT information field refers to a field containing one or more types of LLT information described above.

[0261] The LLT BA frame can satisfy at least one of the conditions described below.

[0262] - The BA type associated with the BA frame (or BA control field) can be defined as a new type.

[0263] - The BA type in the BA control field may be a compressed BA frame variant.

[0264] - The BA information field of the LLT BA frame may be identical to the BA information field of the compressed BA frame variant.

[0265] - If the BA type of the LLT BA frame is a new type, the LLT information field may exist after the BA information field.

[0266] Additionally or alternatively, the LLT information field may utilize the Block ACK Starting Sequence Control subfield of the BA information field in at least one of the following manners.

[0267] - The fragment number subfield of the block ACK start sequence control subfield can be set to a specific value. When the fragment number subfield value is set to 4 bits (B3B2B1B0), the fragment number subfield value of the block ACK start sequence control subfield can be set to "1111".

[0268] For example, as described above, the LLT information field may be included / placed on the BA frame according to the fragment number subfield to which a specific value is set. For example, the LLT information field may be placed following the fragment number subfield to which a specific value is set. Additionally or alternatively, the start sequence control subfield or / and the block ACK bitmap subfield may not be present according to the fragment number subfield to which a specific value is set.

[0269] FIG. 17 is a diagram for explaining the configuration of an LLT BA frame and a procedure for transmitting and receiving an LLT BA frame according to one embodiment of the present disclosure.

[0270] The AP can first obtain a TXOP through a CTS / RTS exchange and then transmit a PPDU to STA 1. For example, the PPDU can include an A-MPDU containing a QoS data frame. The PPDU can include information for STA 1 to trigger LLT information. STA 1 can transmit a BA frame containing LLT information (i.e., an LLT BA frame) to the AP in response to the PPDU.

[0271] As illustrated in FIG. 17, the LLT BA frame may include ACK information for the QoS data frame(s) included in the A-MPDU, and the ACK information may be included in the BA information field. Additionally, a fragment number field set to a specific value may be present to indicate the presence of LLT information on the LLT BA frame. In this case, the fragment number field may be positioned subsequent to the BA information field containing the ACK information, but is not limited thereto.

[0272] A fragment number field set to a specific value may indicate that LLT information exists after the fragment number field. Therefore, STA 1 may transmit LLT information to the AP simultaneously with ACK information for the data frame using the LLT BA frame.

[0273] An AP that receives an LLT BA frame including LLT information from STA 1 can transmit a trigger frame to STA 1. STA 1 can transmit LLT to the AP based on the trigger frame. According to various embodiments of the present disclosure, LLT information may be included in the BA frame. For example, the BA frame may include LLT information equal to or longer than the length of the BA information field.

[0274] In one embodiment of the present disclosure, an LLT BA frame may satisfy at least one of the conditions described below when including information related to a multi-TID.

[0275] - The BA type in the BA control field can be defined as a new type.

[0276] - The BA type in the BA control field can be a multi-STA BA variant.

[0277] - The BA information field of the LLT BA frame is the same as the BA information field of the multi-STA BA frame, but the format of the Per AID TID Info subfield for LLT of the LLT BA frame may be different.

[0278] Specifically, the AID TID information field of the AID TID-specific information subfield of the LLT BA frame may be applied to at least one of the following items.

[0279] - When a non-AP STA transmits an LLT BA frame, the AID 11 subfield value of the AID TID-specific information subfield (for LLT) may be set to 0 or a specific value. For example, when a non-AP STA transmits an LLT BA frame to an AP, the AID 11 subfield value may be set to a value other than 0 (e.g., 1 or 2008). Additionally or alternatively, at this time, the ACK type subfield and the TID subfield of the AID TID-specific information subfield for LLT may be set to any value. Since a non-AP STA transmits a multi-STA BA frame only to an AP, the AP can determine the presence or absence of the LLT information field through the specific AID value.

[0280] - When an AP transmits a PPDU to one STA, the value of the AID 11 subfield of the AID TID-specific information subfield (for LLT) may be set to the 11 LSB of the AID of that STA. Additionally or alternatively, when an AP transmits a PPDU to one or more non-AP STAs, the value of the AID 11 subfield of the AID TID-specific information subfield (for LLT) may be set to a specific value (e.g., 0 or one of 2008 to 2044).

[0281] - The ACK type subfield of the AID TID-specific information subfield (for LLT) can be set to a specific value (e.g., 0 or 1).

[0282] - The TID subfield of the AID TID-specific information subfield (for LLT) may be set to a specific value (e.g., one of 8 to 15), except when the ACK type subfield value is set to 1 and the TID subfield value is set to 15.

[0283] - The LLT information field may be present following the AID 11 subfield, the ACK type subfield, and the TID subfield that satisfy the conditions described above. For example, if there is an AID TID information field that satisfies the conditions described above (e.g., an AID TID information field including an AID 11 subfield, an ACK type subfield, and a TID subfield), the LLT information field may be present on the AID TID-specific information subfield (for LLT).

[0284] - Additionally or alternatively, if an AID TID information field that satisfies the conditions described above (e.g., an AID TID information field including an AID 11 subfield, an ACK type subfield, and a TID subfield) is present, the Block ACK Start Sequence Control field or / and the Block ACK Bitmap field may not be present on the LLT BA frame.

[0285] Additionally or alternatively, if a specific value is set to match the conditions described above for the AID TID information field, the LLT information field may be present or included (on the LLT BA frame) instead of the Block ACK Start Sequence Control field and the Block ACK Bitmap field.

[0286] Additionally or alternatively, if a specific value is set to match the conditions described above for the AID TID information field, the LLT information field may be included instead of the Block ACK Start Sequence Control field and the Block ACK Bitmap field. Additionally or alternatively, the size of the LLT information field may be the length of the LLT information itself. Additionally or alternatively, the Block ACK Start Sequence Control field length and / or the Block ACK Bitmap field length may be included on the LLT information field.

[0287] FIG. 18 is a diagram for explaining the configuration of an LLT BA frame for multi-TID and the transmission and reception procedure of LLT BA as an embodiment of the present disclosure.

[0288] The AP may first obtain a TXOP through a CTS / RTS exchange and then transmit a PPDU to STA 1. In this example, the PPDU may include a multi-TID A-MPDU containing QoS data frame(s) for each of TID 1 and TID 2. The PPDU may include information for triggering LLT information transmission by STA 1.

[0289] STA 1, which receives the corresponding PPDU, may respond to the AP with an LLT BA frame (i.e., a multi-STA BA frame including LLT information or a new type of LLT BA frame). As illustrated in FIG. 18, the corresponding LLT BA frame may include an AID TID info subfield for ACK information for the QoS data frames included in the A-MPDU (i.e., QoS data frames for TID 1 and TID 2).

[0290] Additionally, the AID TID-specific information subfield containing LLT information may indicate the presence of LLT information subsequent to the AID TID-specific information subfield using a specific ACK type (e.g., 0) and TID (e.g., 14) value. Accordingly, STA 1 may transmit LLT information to the AP simultaneously with the ACK information for the data frame using the LLT BA frame.

[0291] An AP that receives an LLT BA frame including LLT information from STA 1 can transmit a trigger frame to STA 1, and STA 1 can transmit LLT to the AP based on the trigger frame. As described above, the LLT BA frame can include LLT information. In addition, the LLT BA frame can include LLT information equal to or longer than the length of the BA information field, and can be applied to multi-TID.

[0292] Example 1-2-3

[0293] In one embodiment of the present disclosure, a field of the MAC header may be utilized to transmit LLT information.

[0294] As an example of the present disclosure, an STA may transmit a PPDU (e.g., an A-MPDU) containing a more data field to an AP. The more data field may include LLT presence information indicating the presence of LLT information. For example, if an STA transmits a PPDU with the more data field value set to 1, this may indicate the presence of LLT information to be transmitted by the STA to the AP.

[0295] Additionally or alternatively, the STA may transmit a PPDU (e.g., A-MPDU) including a QoS control field to the AP. When bit 4 of the QoS control field is set to 0 or 1, bit 7 of the QoS control field may indicate the presence or absence of LLT information and / or LLT presence. In this case, bit 7 of the QoS control field may be set to 0 or 1. As described above, when bit 4 of the QoS control field is set to 0 or 1 and bit 7 of the QoS control field is set to indicate the presence or absence of LLT information, LLT information may be set via at least one of bits 8 to 15 of the QoS control field.

[0296] FIG. 19 is a diagram for explaining a method of transmitting LLT information using a MAC header according to one embodiment of the present disclosure.

[0297] As illustrated in FIG. 19, the AP may first obtain a TXOP through an RTS / CTS exchange and then transmit a PPDU to STA 1. In this example, an A-MPDU containing QoS data frame(s) on the PPDU may be transmitted to STA 1.

[0298] The PPDU may include information that triggers STA 1 to transmit LLT information. STA 1, upon receiving the PPDU, may transmit the more data field and / or QoS control field containing the LLT information to the AP using the A-MPDU. At this time, the more data field and / or QoS control field may be included in the BA frame, QoS data frame, or / and QoS null frame of the A-MPDU.

[0299] As an example of the present disclosure, if a BA frame includes a QoS control field, the BA frame may be defined as a new control frame or BA type. Accordingly, STA 1 may transmit LLT information to the AP simultaneously with ACK information for the data frame using the BA frame.

[0300] For example, if the ACK policy is set to a policy requiring immediate response to BA frames (e.g., implicit BAR), the PPDU transmitted by the AP on the BA frame may include BA information (for QoS data) for the MPDU(s). As another example, if the ACK policy is set to a policy not requiring immediate response to BA frames (e.g., the ACK policy is set to BA), the PPDU transmitted by the AP on the BA frame may not include BA information (for QoS data) for the MPDU(s).

[0301] An AP that receives an LLT BA frame containing LLT information from STA 1 may transmit a trigger frame to STA 1. STA 1 may include the LLT information in the MAC header of a response (e.g., an A-MPDU) to the trigger frame. In the present disclosure, STA 1 may transmit LLT information to the AP simultaneously with multiple frames (e.g., a BA frame, a data frame, etc.).

[0302] Example 2

[0303] Embodiment 2 relates to a process for triggering LLT information and transmitting and receiving LLT information. That is, Embodiment 2 specifies the LLT information triggering procedure and LLT information transmitting and receiving procedure in Embodiment 1 and its sub-embodiments. As described above, the STA may be a non-AP STA or an AP.

[0304] In describing the present disclosure, an STA (e.g., an AP, etc.) may acquire / initiate a TXOP by transmitting a frame / PPDU. Other STAs (e.g., non-AP STAs) may receive one or more PPDUs from the STA (e.g., the AP) within the TXOP, the PPDUs including frames that trigger low-latency traffic (LLT) information. Here, the one or more PPDUs may include frames addressed to one or more STAs (e.g., QoS data frames).

[0305] Additionally or alternatively, there may be a predefined time (e.g., SIFS, PIFS) between a PPDU / frame that triggers LLT information and a frame containing LLT information responding to that PPDU / frame.

[0306] An STA (e.g., an AP) that receives one or more frames / PPDUs containing LLT information may transmit a frame / PPDU that triggers LLT based on the LLT information to another STA (e.g., a non-AP STA).

[0307] An STA that receives one or more frames including LLT information can perform a frame detection operation and obtain LLT information for each STA through the frame detection operation. One or more STAs can prepare for PPDU / frame transmission that can trigger LLT through the obtained LLT information. The configuration of LLT information has been described in Example 1-1, so a redundant description will be omitted. An STA that receives a PPDU / frame that triggers LLT can perform frame detection and prepare for LLT transmission through the frame detection.

[0308] As an example of the present disclosure, within a TXOP established by STA 1, STA 2 may transmit a frame containing LLT information to STA 1 or / and one or more other STAs. The LLT information may be transmitted to STA 1 via a response frame to the frame triggering the LLT information or via another frame.

[0309] LLT information can be transmitted and received through at least one of an HT control field (e.g., an A-control field), a BA (block ACK) frame (e.g., a BA control field of a BA frame), or a MAC header. For example, if LLT information is included in a BA frame, the BA frame can be defined as a new BA type.

[0310] Additionally or alternatively, a field including LLT information may be present after the BA information field of the BA frame or on the BA information field. Additionally or alternatively, when the BA frame is a compressed BA, the fragment number subfield of the block ACK start sequence control field may be set to a specific value to indicate that LLT information is included in the BA frame. Additionally or alternatively, when the BA frame is a multi-STA BA frame, the AID TID information field of the Per AID TID Info subfield may be set to a specific value to indicate that LLT information is included in the BA frame.

[0311] Example 3

[0312] Embodiment 3 relates to a procedure and related parameters for triggering LLT information. That is, as described in Embodiment 1 (and / or detailed embodiments of Embodiment 1) and Embodiment 2, LLT information may be indicated by one or more frames, and thus a procedure for triggering LLT information may be required. Triggering of LLT information may be performed via an HT control field and / or a trigger frame.

[0313] Example 3-1

[0314] In one embodiment of the present disclosure, triggering of LLT information may be performed via an HT control field. That is, information for transmitting LLT information may be included in an HT control field (e.g., an A-control field).

[0315] For example, information for triggering LLT information may be transmitted and received via a triggered response scheduling (TRS) control field, which is a control type of the A-control field. As another example, information for triggering LLT information may be transmitted and received via a new control field.

[0316] Additionally or alternatively, LLT information may be triggered via the control field described above, but LLT may be triggered. In describing the present disclosure, the action of triggering LLT information may be replaced with the action of triggering LLT.

[0317] Example 3-1-1

[0318] In one embodiment of the present disclosure, triggering of LLT information may be performed via the TRS control field illustrated in (a) of FIG. 20. The TRS control field illustrated in (a) of FIG. 20 is applied to STAs that have received the TRS control field, and thus, each STA must be able to decode the TRS control field in order to transmit LLT information. Accordingly, as illustrated in (b) of FIG. 20, triggering of LLT information may be indicated using a reserved field of the TRS control field.

[0319] For example, as illustrated in (b) of FIG. 20, the TRS control field (e.g., the 26th bit (B25) of the TRS control field) may include LLT information or information for LLT transmission (e.g., LLT information or information for triggering LLT transmission, etc.).

[0320] For example, the TRS control field may include an RU allocation subfield indicating LLT information or an RU for transmitting LLT, and an LLT random access RU (RA-RU) subfield indicating an RU that can be accessed using UL OFDMA random access (UORA). As an example, as illustrated in (b) of FIG. 20, the LLT RA-RU subfield may be set on the 26th bit, but is not limited thereto.

[0321] Example 3-1-2

[0322] As an example of the present disclosure, a new control field may be defined to trigger LLT information or LLT. That is, the number of bits in the TRS control field may be insufficient to include / set information for transmitting LLT information or LLT. Accordingly, a control field with a new ID set for transmitting LLT information or LLT (i.e., a new LLT TRS control field for transmitting LLT information or LLT) may be defined.

[0323] For example, as illustrated in (c) of FIG. 20, the LLT TRS control field may include an LLT TX subfield, an RA-RU subfield, and / or an association subfield. The names of each of the LLT TX subfield, the RA-RU subfield, and / or the association field may be changed.

[0324] The LLT TX subfield may indicate that the RU indicated in the RU allocation subfield is an RU for transmitting LLT information or LLT.

[0325] The RA-RU subfield (e.g., 1 bit) may indicate that the RU indicated in the RU Assignment subfield is an RU that can be accessed using UORA. For example, if the RA-RU subfield value is 1 (or 0), this may mean that the RU indicated by the RU Assignment subfield is an RU that uses UORA.

[0326] The combining subfield may indicate whether the frame can be transmitted by associated STAs or unassociated STAs in the RU indicated by the RU assignment subfield. For example, if the combining subfield value is 1 (or 0), this may indicate that only associated STAs can access the RU indicated by the RU assignment subfield.

[0327] FIG. 21 is a diagram illustrating a method of triggering LLT information via a control field according to one embodiment of the present disclosure. That is, FIG. 21 relates to a method of triggering LLT information via a control field in addition to FIG. 13.

[0328] The AP may first obtain a TXOP through an RTS / CTS exchange and then transmit one or more frames to one or more STAs through a PPDU. At this time, the PPDU may include one or more A-MPDUs. The AP may transmit a data frame to STA 1 using the A-MPDU and at the same time indicate an RU (e.g., RU 1) in which a BA frame is to be transmitted through a TRS control field. Additionally, the AP may indicate RU information (e.g., RU 2) for transmitting LLT information to at least one STA, which may include STA 1 and / or STA 2, and information that an RA-RU should be utilized through a modified TRS control field or an LLT TRS control field.

[0329] The above-described control field(s) may be transmitted to at least one STA via a QoS null frame or a QoS data frame. The receiver address (RA) of the QoS null frame or QoS data frame may be set to a broadcast address or a MAC address for a specific STA.

[0330] In the present disclosure, STA 2 may access RU 2 via UORA to transmit LLT information to the AP. STA 1 may also contention in RU 2 via UORA and / or transmit LLT information to the AP via BA frames in RU 1.

[0331] For example, if the ACK policy for the MPDU(s) transmitted by the AP is set to a policy requiring an immediate response to the BA frame (e.g., HETP ACK), BA information may be included in the BA frame transmitted from STA 1. However, if the ACK policy is set to a policy that does not require an immediate response to the BA frame (e.g., the ACK policy is set to BA), BA information for the MPDU(s) may not be included in the BA frame transmitted by the AP in the PPDU.

[0332] Example 3-2

[0333] In one embodiment of the present disclosure, a trigger frame may be used to allocate an RU for transmitting LLT information or LLT. The trigger frame may allocate an RU for frame transmission, and a combination of the trigger frame and the RU allocation method may trigger transmission of LLT information or LLT.

[0334] Additionally or alternatively, LLT information may be triggered via the control field described above, but LLT may be triggered. In describing the present disclosure, the action of triggering LLT information may be replaced with the action of triggering LLT.

[0335] Example 3-2-1

[0336] In one embodiment of the present disclosure, the LLT information or the trigger frame capable of triggering the LLT may be referred to as, but is not limited to, an LLT poll trigger frame.

[0337] As an example of the present disclosure, the LLT pole trigger frame can be set to a new trigger frame variant.

[0338] Additionally or alternatively, the LLT poll trigger frame may utilize the format of a basic or existing trigger frame variant. In this case, LLT information or a bit / subfield indicating LLT triggering may be included / set on a reserved bit of the common information field of the LLT poll trigger (e.g., a reserved bit on the common information field illustrated in FIG. 8 (e.g., an EHT reserved bit, etc.)).

[0339] For example, when transmitting a BSRP (buffer status report poll) trigger frame or a basic trigger frame, a bit / subfield indicating that LLT information or LLT is triggered may be included / set in the common information field of the trigger frame. In this case, an STA that receives the trigger frame may transmit LLT information or LLT to the AP instead of BSR in response to the trigger frame.

[0340] An LLT poll trigger frame can allocate an RU to a specific STA. Additionally or alternatively, the LLT poll trigger frame can allocate one or more RA-RUs that one or more STAs can access using UORA. An STA that receives an LLT poll trigger frame can transmit LLT information or LLT (to the AP) after winning contention for the allocated RU or / and RA-RU.

[0341] Additionally or alternatively, the user information field that allocates an RU or RA-RU may include bits / fields / information indicating LLT information or LLT triggering. The bits / fields / information indicating LLT information or LLT transmission triggering may be set via reserved bits in the user information field. This allows the purpose of the RU(s) to be distinguished within a single trigger frame.

[0342] FIG. 22 is a diagram illustrating a method of triggering LLT information using an LLT poll trigger frame according to one embodiment of the present disclosure.

[0343] The AP first obtains a TXOP through an RTS / CTS exchange, and then transmits one or more frames to one or more STAs via a PPDU. The PPDU may include one or more MU PPDUs. For example, the AP may transmit an LLT poll trigger frame in RU 3, and may transmit an A-MPDU containing one or more QoS data frames to be transmitted to STA 1 in RU 4.

[0344] Here, RU 3 can be set as a broadcast RU, so that one or more STAs can receive and decode the LLT poll trigger frame from the AP via RU 3. The LLT poll trigger frame can indicate that LLT information (or / and LLT) can be transmitted via RU 2, and RU 2 can be set as an RA-RU via "AID = 0". Therefore, in this example, STA 1, 2, and 3 can attempt to transmit LLT information (or / and LLT) via UORA in RU 2. FIG. 22 illustrates that STA 2 accesses RU 2 via UORA to transmit LLT information.

[0345] For example, in RU 4, one or more QoS data frame(s) can be transmitted / received to STA 1. Therefore, according to the ACK policy of the QoS data frame(s), STA 1 can transmit / respond to the AP with a BA frame (for the QoS data frame).

[0346] For example, if the ACK policy for the MPDU(s) transmitted by the AP is set to a policy requiring an immediate response to the BA frame (e.g., HETP ACK), BA information may be included in the BA frame transmitted from STA 1. However, if the ACK policy is set to a policy that does not require an immediate response to the BA frame (e.g., the ACK policy is set to BA), BA information for the MPDU(s) may not be included in the BA frame transmitted by the AP in the PPDU.

[0347] For example, if STA 1 can access RU 2 allocated in the LLT Poll trigger frame, STA 1 may transmit LLT information (or / and LLT) to the AP via RU 2. Additionally or alternatively, an RU (e.g., RU 1) may be allocated for transmission of LLT information (or LLT) of STA 1 via the LLT Poll trigger frame.

[0348] Additionally or alternatively, STA 3 may access the assigned RA-RU via an LLT poll trigger frame to transmit LLT information (or / and LLT) to the AP.

[0349] For example, an AP that receives LLT information from STAs 1, 2, and 3 can transmit a trigger frame for triggering LLT to STAs 1, 2, and 3. STAs 1, 2, and 3 can transmit LLT to the AP based on the received trigger frame.

[0350] Example 3-2-2

[0351] In one embodiment of the present disclosure, at least one field (including a reserved field) of a user information field of a trigger frame may be used to indicate that the trigger frame is a trigger frame that triggers LLT information or LLT. In this case, variants of the trigger frame may not be limited to specific variants.

[0352] As an example of the present disclosure, if the AID12 field included in the user information field of the trigger frame is set to a specific value (e.g., 2044, 2047, etc.), this may mean that the RU allocated by the trigger frame is an RU for transmitting LLT information (or / and LLT). Here, the specific value may be set / defined as one or more of 1 to 2007 or reserved values ​​used for a combined STA with a specific AID.

[0353] As an example of the present disclosure, the RU indicated by the special AID12 field and the RU allocation subfield may be an RA-RU that multiple STAs can access via UORA.

[0354] Additionally or alternatively, a specific AID value (e.g., 2006, 2008, 2047) included in a trigger frame (e.g., in the user information field) may indicate that the trigger frame is a trigger frame for triggering LLT information or LLT. As another example, a specific AID value included in a trigger frame and a specific bit (in the user information field) may indicate that the trigger frame is a trigger frame for triggering LLT information or LLT.

[0355] Additionally, a specific AID value included in the trigger frame may indicate that the allocated RU (e.g., by the user information field) is to be used as an RA-RU. As another example, the trigger frame (or the user information field included therein) may include a field (or a specific bit) that indicates that the allocated RU (e.g., by the RU allocation subfield) is to be used as an RA-RU.

[0356] Additionally or alternatively, information (or specific bits) indicating that the trigger frame is a trigger frame for triggering LLT information or LLT, or / and information (or specific bits) indicating that the RU allocated by the trigger frame is used as an RA-RU may be included in the padding bits of the trigger frame.

[0357] As an example of the present disclosure, when the AID12 field indicates the AID of a specific STA, whether LLT information or LLT transmission is required in an RU allocated (by the trigger frame) may be indicated via one or more reserved bits in the user information field of the trigger frame. That is, whether transmission of LLT information (or / and LLT) is required or / and whether transmission of LLT information (or / and LLT) is possible may be indicated via at least one bit included in the user information field of the trigger frame (e.g., a reserved bit included in the user field, etc.).

[0358] As an example of the present disclosure, when an AID12 field having a specific value (e.g., 0, 2045, etc.) set indicates allocation of one or more RA-RU(s), whether LLT information or LLT transmission is required in the allocated RU (by the trigger frame) may be indicated via one or more reserved bits in the user information field of the trigger frame. That is, whether transmission of LLT information (or / and LLT) is required or / and whether transmission of LLT information (or / and LLT) is possible may be indicated via at least one bit included in the user information field of the trigger frame (e.g., a reserved bit included in the user field, etc.).

[0359] FIG. 23 is a diagram illustrating a method for triggering transmission of LLT information through a user information field of a trigger frame according to one embodiment of the present disclosure.

[0360] The AP first obtains a TXOP through an RTS / CTS exchange, and then transmits one or more frames to one or more STAs through a PPDU. At this time, the PPDU may include one or more MU PPDUs. As illustrated in FIG. 23, the AP transmits a basic trigger frame through RU 3, and transmits an A-MPDU containing one or more QoS data frames to STA 1 through RU 4. As described above, the basic trigger frame may be replaced with a trigger frame of another variant (e.g., a BSRP trigger frame).

[0361] RU 3 can be set as a broadcast RU, and one or more STAs can receive / decode a basic trigger frame from the AP via RU 3. The basic trigger frame allows LLT information (or / and LLT) to be transmitted via RU 2 (i.e., allows LLT information (or / and LLT) to be triggered). In addition, an RU (e.g., RU 2) for transmitting LLT information (or / and LLT) can be set as the AID value is set to a specific value (e.g., 2006, etc.). One or more STAs can contend for the RU via UORA, and the RU can be set as an RA-RU.

[0362] Additionally or alternatively, the AID value may be set to 0 or 2045, thereby setting the RU to RA-RU. In addition, whether or not LLT information (or LLT) needs to be transmitted in the allocated RU may be indicated through one or more reserved bits in the user information field of the trigger frame.

[0363] Accordingly, STA 1, 2, and 3 may attempt to transmit LLT information (or LLT) to RU 2 via UORA. As an example of the present disclosure, as illustrated in FIG. 24, STA 2 may access RU 2 via UORA to transmit LLT information (or LLT) to the AP.

[0364] The AP may transmit one or more QoS data frame(s) to STA 1 via RU 4. Therefore, STA 1 may transmit / respond to the AP with a BA frame for the QoS data frame(s) according to the ACK policy of the QoS data frame(s).

[0365] For example, if the ACK policy for MPDU(s) transmitted by the AP is set to a policy requiring an immediate response to the BA frame (e.g., HETP ACK), BA information may be included in the BA frame transmitted from STA 1. However, if the ACK policy is set to a policy that does not require an immediate response to the BA frame (e.g., the ACK policy is set to BA), BA information for MPDU(s) may not be included in the PPDU transmitted by the AP in the BA frame. Additionally or alternatively, when transmitting BA information and LLT information (or LLT), a method in which LLT information (or LLT) is included in a compressed BA frame or a multi-STA BA frame as described above may be applied.

[0366] Additionally or alternatively, if STA 1 has access to RU 2 allocated by the basic trigger frame, STA 1 may transmit LLT information (or / and LLT) to the AP via RU 2.

[0367] Additionally or alternatively, the basic trigger frame may allocate an RU (e.g., RU 1) for transmitting LLT information of STA 1. At this time, whether or not transmission of LLT information (or / and LLT) is required in the allocated RU (by the trigger frame) may be indicated via one or more reserved bits of the user information field for STA 1.

[0368] As an example of the present disclosure, as illustrated in FIG. 23, STA 3 can access RA-RU (e.g., RU 5) allocated by a basic trigger frame to transmit LLT information (or LLT) to the AP. The AP, which has received LLT information from STA 1 and STA 2, can allocate RU 6 and RU 7 to STA 1 and STA 2 via the basic trigger frame for LLT transmission of STA 1 and STA 2.

[0369] Additionally or alternatively to Embodiments 3-2-1 and 3-2-2, one or more method(s) by which one or more STAs can transmit LLT information (or / and LLT) in the preamble / PHY header are as follows.

[0370] - A broadcast RU may be defined for transmitting LLT information (or / and LLT). Based on the STA ID field of the PHY header being set to a specific value (e.g., 2006), only one or more STAs that will perform LLT information (or / and LLT) transmission may access the broadcast RU. For example, in FIGS. 22 and 23, at least one STA associated with a specific STA ID value may utilize RU 3 allocated as the broadcast RU.

[0371] - A field that triggers transmission of LLT information (or / and LLT) (e.g., whether LLT information (or / and LLT) transmission is required) may be included in the PHY header. For example, in FIGS. 22 and 23, if the field is included in the PHY header of the PPDU and the value of the field is set to a specific value (e.g., 1), only STAs that must transmit LLT information (or / and LLT) can access RU 3 allocated as a broadcast RU.

[0372] Example 4

[0373] Example 4 relates to a procedure for utilizing a specific frame to trigger LLT information. Here, the frame that triggers LLT information is named an LLT poll frame, but is not limited thereto, and the name of the frame may be changed.

[0374] As an example of the present disclosure, the LLT Poll frame may be defined as a new control or management frame (e.g., an action frame). Additionally or alternatively, the LLT Poll frame may be defined as a trigger frame (e.g., an LLT Poll Trigger Frame), and the trigger variant of the LLT Poll frame may be defined as a new trigger frame variant for LLT information triggering.

[0375] Additionally or alternatively, if the LLT poll frame defines a trigger frame, the LLT poll trigger frame may utilize the format of the existing trigger frame variant as is. Additionally, the common information field of the LLT poll trigger frame may include information indicating that LLT information is triggered, and the information may be mapped onto reserved bits of the common information field (e.g., a reserved bit field, an EHT reserved bit field, etc.).

[0376] For example, when a BSRP (buffer status report poll) trigger frame or a basic trigger frame is transmitted, if the common information field includes information indicating that LLT information is triggered, the STA may transmit LLT information instead of BSR in response to the trigger frame to another STA that transmitted the trigger frame.

[0377] For example, an LLT poll trigger frame may allocate an RU to a specific STA, and one or more STAs may allocate one or more RA (random access)-RUs that can be accessed using uplink OFDMA-based random access (UORA).

[0378] Additionally or alternatively, the user information field that allocates RU / bandwidth or RA-RU may include information indicating that LLT information is triggered. In this case, the information indicating that LLT information is triggered may be mapped to reserved bits in the user information field. This allows the purpose of RUs to be distinguished through a single trigger frame.

[0379] Example 4-1

[0380] Example 4-1 relates to rules related to responses to LLT poll frames when an LLT poll frame is transmitted to trigger LLT information. At least one of the rules related to responses to LLT poll frames described below may be utilized / applied, and in the present disclosure, a response frame / PPDU transmitted by an STA responding to an LLT poll frame is referred to as an LLT indication.

[0381] As an example of the present disclosure, an LLT instruction may include at least one type of LLT information described above.

[0382] Additionally or alternatively, the LLT indication (i.e., the frame containing the LLT indication) may itself include LLT presence information (i.e., indicating that the STA currently has LLT to transmit). Furthermore, the LLT indication itself may be interpreted as a request from one STA in a TXOP that another STA wants to transmit LLT.

[0383] At this time, if the STA has no LLT to transmit or does not wish to transmit LLT, the STA may not transmit an LLTI (LLT indication). For example, the LLT indication may be a control frame such as a conventional ACK, CTS / CTS-to-Self, or a PPDU that does not have an NDP or MPDU.

[0384] Additionally or alternatively, a PPDU containing an LLT indication may be a non-HT PPDU or a non-HT duplicate PPDU.

[0385] Additionally or alternatively, one or more types of LLT information may be indicated via the A-control frame of the QoS null frame to include more LLT information.

[0386] As an example of the present disclosure, an STA transmitting an LLT instruction may transmit the LLT instruction using a channel having a bandwidth size smaller than or equal to the bandwidth supported by the STA, including a primary channel.

[0387] Additionally or alternatively, the bandwidth over which the LLT indication is transmitted may be smaller than the bandwidth of the PPDU containing the LLT poll frame. Additionally or alternatively, the bandwidth over which the LLT indication is transmitted may be fixed to a specific value (e.g., 20 MHz, 40 MHz, etc.).

[0388] As an example of the present disclosure, CCA may be performed when an LLT indication is transmitted. For example, an energy detection operation may be performed during an interval (e.g., SIFS) after receiving an LLT poll frame and before transmitting the LLT indication.

[0389] Additionally or alternatively, an LLT indication may be transmitted by excluding (e.g., puncturing) one or more 20 MHz channels whose channel status is BUSY due to CCA.

[0390] Additionally or alternatively, the following rules for LLT instruction transmission may apply due to CCA:

[0391] - If the secondary 20MHz channel status is BUSY, the LLT indication may not be transmitted on the secondary 20MHz channel. For example, the LLT indication may be transmitted only on the primary 20MHz channel.

[0392] - If the status of one or more 20MHz channels among the secondary 40MHz channels is BUSY, the LLT instruction may not be transmitted on the secondary 40MHz channel.

[0393] - If the status of one or more 20MHz channels among the secondary 80MHz channels is BUSY, the LLT instruction may not be transmitted on the secondary 80MHz channel.

[0394] - If the status of one or more 20MHz channels among the secondary 160MHz channels is BUSY, the LLT instruction may not be transmitted on the secondary 160MHz channel.

[0395] As an example of the present disclosure, the LLT indication may be transmitted based on information indicated in an LLT poll frame. As an example, the LLT poll frame may include information regarding a maximum bandwidth (e.g., a maximum bandwidth over which the LLT indication may be transmitted (e.g., 20, 40, 80, 160, 320 MHz)) and / or whether the channel over which the LLT indication is transmitted should include a primary channel.

[0396] Here, the LLT indication may be transmitted at least through a secondary 20 MHz channel, based on the LLT poll frame indicating that the channel through which the LLT indication is transmitted does not include a primary channel. Additionally or alternatively, if the transmittable bandwidth is X MHz, the LLT indication may be transmitted only through Y MHz out of X MHz, excluding the primary channel. For example, if the transmittable bandwidth is 40 MHz, the LLT indication may be transmitted only through a secondary 20 MHz out of 40 MHz, excluding the primary channel.

[0397] As an example of the present disclosure, when one or more other frames (e.g., QoS data frames) are transmitted simultaneously with an LLT poll frame, one or more STAs (i.e., TXOP responders) that are receivers of the one or more other frames may transmit an ACK frame or an LLTI.

[0398] For example, assume that one or more STAs, which are recipients of one or more other frames, transmit an ACK frame. When a QoS data frame is transmitted together with an LLT poll frame, an ACK policy indicated in the QoS data frame may be newly defined. Here, the ACK policy may mean an ACK policy (referred to as an LLT ACK policy in this disclosure) that requests an ACK frame for the QoS data frame and allows the BA to respond later. For example, the LLT ACK policy may be indicated when the ACK policy indication subfield value is set to a specific value (e.g., "01").

[0399] Additionally, an A-MPDU containing an MDPU with an LLT ACK policy may be included in a UHR PPDU or a PPDU of a later UHR version. Additionally, one or more frames with an LLT ACK policy and an LLT poll frame may be transmitted and received together.

[0400] Additionally or alternatively, if there is no need to transmit LLTI, an Ack frame may be transmitted mandatorily upon successfully receiving an LLT Poll frame or one or more frames addressed to itself. This case can be used to address cases where LLTI is not transmitted or failure issues.

[0401] FIG. 24 is a diagram illustrating a procedure for transmitting LLTI using an LLT poll frame according to one embodiment of the present disclosure. As illustrated in FIG. 24, an AP may first obtain a TXOP through an RTS / CTS exchange, and then transmit one or more frames to one or more STA(s) through a PPDU.

[0402] Here, the PPDU can be an MU PPDU, an LLT Poll frame can be transmitted in RU 3, and an A-MPDU containing one or more QoS data frames can be transmitted to STA 1 in RU 4.

[0403] Additionally, RU 3 can be set as a broadcast RU, and one or more STAs can receive and confirm the LLT poll frame in RU 3. Each STA that receives the LLT poll frame can transmit the LLTI using the bandwidth it supports.

[0404] As an example of the present disclosure, assume that all STAs desire to transmit LLT. In this case, STA 1 and STA 3 support 80MHz of bandwidth of PPDU containing LLT poll frame and can transmit LLTI using this. STA 2 supports 40MHz of bandwidth of 80MHz of PPDU containing LLT poll frame and can transmit LLTI using this. Additionally or alternatively, STA 1 can transmit ACK frame even if LLTI transmission is not required.

[0405] Additionally, the AP may perform a verification procedure for the STA that transmitted the LLTI. For example, the AP may transmit an NFRP (NDP Feedback Report Poll) trigger frame to at least one STA, and the STA(s) that transmitted the LLTI may transmit an NFR in response to the trigger frame.

[0406] And, the AP that confirms that it has received LLTI from STA 1, 2, and 3 can transmit a trigger frame to STA 1, 2, and 3, and STA 1, 2, and 3 can transmit LLT to the AP based on the trigger frame.

[0407] FIG. 25 is a diagram illustrating a method for transmitting LLTI through an LLT poll frame according to one embodiment of the present disclosure.

[0408] FIG. 25 is a diagram illustrating a procedure for transmitting LLTI using an LLT poll frame according to one embodiment of the present disclosure. As illustrated in FIG. 25, an AP may first obtain a TXOP through an RTS / CTS exchange, and then transmit one or more frames to one or more STA(s) through a PPDU.

[0409] Here, the PPDU can be an MU PPDU, an LLT poll frame can be transmitted in RU 3, and an A-MPDU containing one or more QoS data frames can be transmitted to STA 1 in RU 4.

[0410] Additionally, RU 3 can be set as a broadcast RU, and one or more STAs can receive and confirm the LLT poll frame in RU 3. Each STA that receives the LLT poll frame can transmit the LLTI using the bandwidth it supports.

[0411] As illustrated in FIG. 25, if LLTI transmission is not required, STA 1 can transmit an ACK frame (e.g., BA, Ack) via the primary channel. This allows the AP to transmit the next frame after maintaining an interval according to SIFS, even if STA 2 and STA 3 do not transmit LLTI.

[0412] For example, STA 2 can support a 40 MHz bandwidth and use it to transmit LLTI to the AP. STA 3 can support an 80 MHz bandwidth and use it to transmit LLTI to the AP. In this case, if the primary channel is not used for LLTI transmission, STA 2 can transmit LLTI through a secondary 20 MHz channel or a 40 MHz channel that includes a secondary 20 MHz channel, excluding the PCH. If the primary channel is not used for LLTI transmission, STA 3 can also transmit LLTI through a 60 MHz or 80 MHz channel that includes at least one 20 MHz channel, excluding the primary channel.

[0413] Additionally, the AP may perform a verification procedure for the STA that transmitted the LLTI. For example, the AP may transmit an NFRP (NDP Feedback Report Poll) trigger frame to at least one STA, and the STA(s) that transmitted the LLTI may transmit an NFR in response to the trigger frame.

[0414] And, the AP that confirms that it has received LLTI from STA 1, 2, and 3 can transmit a trigger frame to STA 1, 2, and 3, and STA 1, 2, and 3 can transmit LLT to the AP based on the trigger frame.

[0415] Example 5

[0416] Example 5 relates to a method in which a PHY header is utilized to trigger LLT information. At least one of the methods described below may be utilized.

[0417] As an example of the present disclosure, a PHY header for triggering LLT information may include a field for triggering transmission of LLT information (i.e., an LLT information trigger field). The LLT information trigger field may indicate whether LLT information needs to be transmitted. As an example, the LLT information trigger field may be included in a SIG field (e.g., a U-SIG field, a UHR-SIG field, etc.) of the PHY header.

[0418] If information for triggering LLT information is included in the PHY header, a response from the STA to the PHY header is required, and therefore, a rule related to the response is required. At least one of the rules related to the response described below may be utilized / applied, and in this disclosure, the response frame / PPDU transmitted by the STA responding to the PHY header is referred to as an LLT indication.

[0419] As an example of the present disclosure, an LLT instruction may include at least one type of LLT information described above.

[0420] Additionally or alternatively, the LLT indication (i.e., the frame containing the LLT indication) may itself include LLT presence information (i.e., indicating that the STA currently has LLT to transmit). Furthermore, the LLT indication itself may be interpreted as a request from one STA in a TXOP that another STA wants to transmit LLT.

[0421] At this time, if the STA has no LLT to transmit or does not wish to transmit LLT, the STA may not transmit an LLTI (LLT indication). For example, the LLT indication may be a control frame such as a conventional ACK, CTS / CTS-to-Self, or a PPDU that does not have an NDP or MPDU.

[0422] Additionally or alternatively, one or more types of LLT information may be indicated via the A-control frame of the QoS null frame to include more LLT information.

[0423] As an example of the present disclosure, an STA transmitting an LLT instruction may transmit the LLT instruction using a channel having a bandwidth size smaller than or equal to the bandwidth supported by the STA, including a primary channel.

[0424] Additionally or alternatively, the bandwidth over which the LLT indication is transmitted may be smaller than the bandwidth of the PPDU that triggers the LLT information. Additionally or alternatively, the bandwidth over which the LLT indication is transmitted may be fixed to a specific value (e.g., 20 MHz, 40 MHz, etc.).

[0425] As an example of the present disclosure, CCA may be performed when an LLT indication is transmitted. For example, an energy detection operation may be performed during an interval (e.g., SIFS) after receiving an LLT poll frame and before transmitting the LLT indication.

[0426] Additionally or alternatively, an LLT indication may be transmitted by excluding (e.g., puncturing) one or more 20 MHz channels whose channel status is BUSY due to CCA.

[0427] Additionally or alternatively, the following rules for LLT instruction transmission may apply due to CCA:

[0428] - If the secondary 20MHz channel status is BUSY, the LLT indication may not be transmitted on the secondary 20MHz channel. For example, the LLT indication may be transmitted only on the primary 20MHz channel.

[0429] - If the status of one or more 20MHz channels among the secondary 40MHz channels is BUSY, the LLT instruction may not be transmitted on the secondary 40MHz channel.

[0430] - If the status of one or more 20MHz channels among the secondary 80MHz channels is BUSY, the LLT instruction may not be transmitted on the secondary 80MHz channel.

[0431] - If the status of one or more 20MHz channels among the secondary 160MHz channels is BUSY, the LLT instruction may not be transmitted on the secondary 160MHz channel.

[0432] As an example of the present disclosure, the LLT indication may be transmitted based on information indicated in the LLT (or information included in the PHY header). As an example, the PHY header may include information regarding a maximum bandwidth (e.g., a maximum bandwidth over which the LLT indication may be transmitted (e.g., 20, 40, 80, 160, 320 MHz)) and / or whether the channel over which the LLT indication is transmitted should include a primary channel.

[0433] Here, the LLT indication may be transmitted at least through a secondary 20 MHz channel, based on the LLT poll frame indicating that the channel through which the LLT indication is transmitted does not include a primary channel. Additionally or alternatively, if the transmittable bandwidth is X MHz, the LLT indication may be transmitted only through Y MHz out of X MHz, excluding the primary channel. For example, if the transmittable bandwidth is 40 MHz, the LLT indication may be transmitted only through a secondary 20 MHz out of 40 MHz, excluding the primary channel.

[0434] As an example of the present disclosure, when one or more other frames (e.g., QoS data frames) are transmitted simultaneously with an LLT poll frame, one or more STAs (i.e., TXOP responders) that are receivers of the one or more other frames may transmit an ACK frame or an LLTI.

[0435] For example, assume that one or more STAs, which are recipients of one or more other frames, transmit an ACK frame. When a QoS data frame is transmitted together with an LLT poll frame, an ACK policy indicated in the QoS data frame may be newly defined. Here, the ACK policy may mean an ACK policy (referred to as an LLT ACK policy in this disclosure) that requests an ACK frame for the QoS data frame and allows the BA to respond later. For example, the LLT ACK policy may be indicated when the ACK policy indication subfield value is set to a specific value (e.g., "01").

[0436] Additionally, an A-MPDU containing an MDPU with an LLT ACK policy may be included in a UHR PPDU or a PPDU of a later version of UHR. Additionally, one or more frames containing an LLT ACK policy and instructions triggering LLT information in the PHY header may be transmitted and received together.

[0437] Additionally or alternatively, if there is no need to transmit LLTI, an Ack frame may be transmitted mandatorily upon successfully receiving instruction information that triggers LLT information or one or more frames addressed to itself. This case can be addressed in cases where LLTI is not transmitted or in cases of failure.

[0438] FIG. 26 is a diagram for explaining a method of transmitting LLTI using a PHY header according to one embodiment of the present disclosure.

[0439] As illustrated in FIG. 26, the AP may first obtain a TXOP through an RTS / CTS exchange, and then transmit one or more frames to one or more STAs through a PPDU. In this example, the PHY header of the PPDU may include an LLT information trigger field. Furthermore, an A-MPDU containing one or more QoS data frames may be transmitted to one or more STAs.

[0440] Each STA that receives the LLT information trigger field can transmit LLTI to the AP using the bandwidth it supports.

[0441] As an example of the present disclosure, it is assumed that all STAs desire LLT transmission. STA 1 and STA 3 support an 80 MHz channel, which is the bandwidth of the PPDU, and can transmit the LLTI using it. STA 2 supports a 40 MHz bandwidth based on the 80 MHz bandwidth of the PPDU, and can transmit the LLTI using it. Additionally or alternatively, STA 1 can transmit an ACK frame even if LLTI transmission is not required.

[0442] Additionally, the AP may perform a verification procedure for the STA that transmitted the LLTI. For example, the AP may transmit an NFRP (NDP Feedback Report Poll) trigger frame to at least one STA, and the STA(s) that transmitted the LLTI may transmit an NFR in response to the trigger frame.

[0443] And, the AP that confirms that it has received LLTI from STA 1, 2, and 3 can transmit a trigger frame to STA 1, 2, and 3, and STA 1, 2, and 3 can transmit LLT to the AP based on the trigger frame.

[0444] FIG. 27 is a diagram for explaining a method of transmitting LLTI using a PHY header according to one embodiment of the present disclosure.

[0445] As illustrated in FIG. 27, the AP first obtains a TXOP through an RTS / CTS exchange, and then transmits one or more frames to one or more STAs through a PPDU. In this example, the PPDU is an MU PPDU, and the PHY header of the PPDU may include an LLT information trigger field. In addition, an A-MPDU containing one or more QoS data frames may be transmitted to one or more STAs.

[0446] Each STA that receives the LLT information trigger field can transmit an LTI using the bandwidth it supports. STA 1 can transmit an ACK frame on the primary channel even if it does not require LLTI transmission. This allows the AP to transmit the next frame after maintaining an interval based on SIFS, even if STA 2 and STA 3 do not transmit LLTI.

[0447] STA 2 supports a 40MHz bandwidth and can use it to transmit LLTI to the AP. STA 3 supports an 80MHz bandwidth and can use it to transmit LLTI to the AP. In this case, if the primary channel is not used for LLTI transmission, STA 2 can transmit LLTI through a secondary 20MHz channel or a 40MHz channel that includes a secondary 20MHz channel, excluding the PCH. In addition, if the primary channel is not used for LLTI transmission, STA 3 can also transmit LLTI through a 60MHz or 80MHz channel that includes at least one 20MHz channel, excluding the primary channel.

[0448] Additionally, the AP may perform a verification procedure for the STA that transmitted the LLTI. For example, the AP may transmit an NFRP (NDP Feedback Report Poll) trigger frame to at least one STA, and the STA(s) that transmitted the LLTI may transmit an NFR in response to the trigger frame.

[0449] And, the AP that confirms that it has received LLTI from STA 1, 2, and 3 can transmit a trigger frame to STA 1, 2, and 3, and STA 1, 2, and 3 can transmit LLT to the AP based on the trigger frame.

[0450] FIG. 28 is a diagram for explaining a method of transmitting LLTI using a PHY header according to one embodiment of the present disclosure.

[0451] As illustrated in FIG. 28, the AP may first obtain a TXOP through an RTS / CTS exchange, and then transmit a trigger frame to STA 1 and STA 2. The AP may receive data based on the trigger frame from STA 1 and STA 2, and transmit a PPDU including a multi-STA block ACK frame to STA 1 and STA 2. In the present disclosure, the PPDU may include a PHY header and an LLT information trigger field.

[0452] Each STA that receives the LLT information trigger field can transmit the LLTI to the AP using the bandwidth it supports. If STA 3 and STA 4 wish to transmit LLT, the PPDU bandwidth of 80 MHz can be the standard. STA 4 supports the 80 MHz bandwidth and can use it to transmit the LLTI to the AP. STA 3 supports the 40 MHz bandwidth out of the 80 MHz PPDU bandwidth and can use it to transmit the LLTI to the AP.

[0453] Additionally or alternatively, STA 1 and STA 2 may transmit ACK frames even if LLTI transmission is not required.

[0454] Additionally, the AP may perform a verification procedure for the STA that transmitted the LLTI. For example, the AP may transmit an NFRP (NDP Feedback Report Poll) trigger frame to at least one STA, and the STA(s) that transmitted the LLTI may transmit an NFR in response to the trigger frame.

[0455] And, the AP that confirms that it has received LLTI from STA 3 and STA 4 can transmit a trigger frame to STA 3 and 4, and STA 3 and 4 can transmit LLT to the AP based on the trigger frame.

[0456] Example 6

[0457] Embodiment 6 relates to a method for indicating / signaling LLT information in a UL TXOP environment. Specifically, LLT information can be indicated / signaled via an HT control field (Embodiment 6-1), a BA (black ack) frame (Embodiment 6-2), and a MAC header (Embodiment 6-3).

[0458] Example 6-1

[0459] In one embodiment of the present disclosure, LLT information may be transmitted and received via an HT control field (e.g., an A-control field). For example, LLT information may be included in a field defined as a new control type of the A-control field. The present disclosure refers to the control field for transmitting and receiving LLT information as an LLT information control field.

[0460] FIG. 29 illustrates a method for transmitting LLT information using an HT control field (e.g., LLT information control of A-control) according to an embodiment of the present disclosure. As illustrated in FIG. 29, STA 1 may first obtain a TXOP through an RTS / CTS exchange and then transmit a PPDU to the AP. In this example, an A (aggregated)-MPDU containing QoS data frame(s) on the PPDU may be transmitted to the AP.

[0461] The PPDU may include information that triggers the AP to transmit LLT information. The AP receiving the PPDU may respond / transmit an LLT information control field including LLT information to the AP using an A-MPDU. The LLT information control field may be included in at least one of a BA frame, an additional QoS data frame, and a QoS null frame and may be responded to / transmitted (to STA 1).

[0462] For example, if a HT control field is included in a BA frame, the HT control field (or BA frame) may be defined as a new control frame type or the +HTC field value of the MAC header may be set to 1. Accordingly, the AP may transmit LLT information to STA 1 simultaneously with ACK information for the data frame using the BA frame.

[0463] For example, if the ACK policy for MPDUs in the PPDU transmitted by STA 1 is a policy requiring an immediate response to the BA frame (e.g., implicit BAR), a BA frame (or BA information) may be present in the A-MPDU transmitted by the AP. As another example, if the ACK policy for MPDUs in the PPDU transmitted by STA 1 is a policy not requiring an immediate response to the BA frame (e.g., ACK policy = BA), a BA frame (or BA information) may not be present in the A-MPDU transmitted by the AP.

[0464] Additionally or alternatively, an STA (e.g., STA 1) that has received LLT information from an AP may transmit an ACK to the AP in response to the LLT information. Here, the ACK may mean that the STA that has received the LLT information allows LLT transmission from the AP or another STA within its TXOP. The ACK transmitted by the STA may include LLT Tx permission information and / or LLT Tx interval information, as described above.

[0465] Example 6-2

[0466] In one embodiment of the present disclosure, it is assumed that LLT information is triggered at the same time that a (QoS) data frame is transmitted to a specific STA. If LLT exists on the AP, the AP may transmit the LLT information (or / and LLT) together with the BA frame to STA 1 (e.g., the STA that triggered the LLT / LLT information). That is, instead of including the LLT information in another frame, the AP may include the LLT information (or / and LLT) in the BA frame.

[0467] The configuration of the BA frame containing LLT information has been described above, so redundant description will be omitted.

[0468] FIG. 30 is a diagram for explaining a procedure for transmitting and receiving a BA frame including LLT information, according to one embodiment of the present disclosure.

[0469] STA 1 can first acquire a TXOP through a CTS / RTS exchange and then transmit a PPDU to the AP. For example, the PPDU may include an A-MPDU containing a QoS data frame. In response to the PPDU, the AP can transmit a BA frame containing LLT information to STA 1.

[0470] The BA frame may include BA information for ACKing the QoS data frame included in the A-MPDU. Additionally, LLT information may be included in the BA control field of the BA frame. For example, as illustrated in FIG. 30, the LLT information may be included in the BA control field. Accordingly, the AP may transmit ACK information and LLT information for the data frame together to STA 1 via the BA frame.

[0471] Additionally or alternatively, STA 1, which has received LLT information from AP, may transmit ACK information to AP in response to the LLT information. Here, ACK may mean that STA, which has received LLT information, allows LLT transmission of AP or another STA within its TXOP. The ACK transmitted by STA may include LLT Tx permission information and / or LLT Tx interval information, as described above. AP, which has transmitted LLT information to STA 1 or received ACK for LLT information from STA 1, may transmit LLT to STA 2.

[0472] In the present disclosure, LLT information may be included on a BA frame regardless of the BA type.

[0473] Additionally or alternatively, a new type of BA frame may be defined or an existing type of BA frame may be utilized to include LLT information. In this disclosure, a BA frame defined to transmit LLT information is referred to as an LLT BA frame.

[0474] An LLT BA frame may additionally include an LLT information field in addition to the basic BA frame (e.g., a frame containing ACK information for a data frame). The LLT information field refers to a field containing one or more types of LLT information described above.

[0475] The LLT BA frame can satisfy at least one of the conditions described below.

[0476] - The BA type associated with the BA frame (or BA control field) can be defined as a new type.

[0477] - The BA type in the BA control field may be a compressed BA frame variant.

[0478] - The BA information field of the LLT BA frame may be identical to the BA information field of the compressed BA frame variant.

[0479] - If the BA type of the LLT BA frame is a new type, the LLT information field may exist after the BA information field.

[0480] Additionally or alternatively, the LLT information field may utilize the Block ACK Starting Sequence Control subfield of the BA information field in at least one of the following manners.

[0481] - The fragment number subfield of the block ACK start sequence control subfield can be set to a specific value. When the fragment number subfield value is set to 4 bits (B3B2B1B0), the fragment number subfield value of the block ACK start sequence control subfield can be set to "1111".

[0482] For example, as described above, the LLT information field may be included / placed on the BA frame according to the fragment number subfield to which a specific value is set. For example, the LLT information field may be placed following the fragment number subfield to which a specific value is set. Additionally or alternatively, the start sequence control subfield or / and the block ACK bitmap subfield may not be present according to the fragment number subfield to which a specific value is set.

[0483] FIG. 31 is a diagram for explaining the configuration of an LLT BA frame and a procedure for transmitting and receiving an LLT BA frame according to one embodiment of the present disclosure.

[0484] STA 1 can first obtain a TXOP through a CTS / RTS exchange and then transmit a PPDU to the AP. For example, the PPDU may include an A-MPDU containing a QoS data frame. The PPDU may include information for the AP to trigger LLT information. In response to the PPDU, the AP can transmit a BA frame containing LLT information (i.e., an LLT BA frame) to STA 1.

[0485] As illustrated in FIG. 31, the LLT BA frame may include ACK information for the QoS data frame(s) included in the A-MPDU, and the ACK information may be included in the BA information field. Additionally, a fragment number field set to a specific value may be present to indicate the presence of LLT information on the LLT BA frame. In this case, the fragment number field may be positioned subsequent to the BA information field containing the ACK information, but is not limited thereto.

[0486] A fragment number field set to a specific value may indicate that LLT information exists after the fragment number field. Therefore, the AP may transmit LLT information to STA 1 simultaneously with ACK information for the data frame using the LLT BA frame.

[0487] Additionally or alternatively, STA 1, which has received LLT information from AP, may transmit ACK information to AP in response to the LLT information. Here, ACK may mean that STA, which has received LLT information, allows LLT transmission of AP or another STA within its TXOP. The ACK transmitted by STA may include LLT Tx permission information and / or LLT Tx interval information, as described above. AP, which has transmitted LLT information to STA 1 or received ACK for LLT information from STA 1, may transmit LLT to STA 2.

[0488] According to the present disclosure, a BA frame may be transmitted including LLT information, and LLT information equal to or greater than the length of the BA information field may be included in the BA frame.

[0489] In one embodiment of the present disclosure, an LLT BA frame may satisfy at least one of the conditions described below when including information related to a multi-TID.

[0490] - The BA type in the BA control field can be defined as a new type.

[0491] - The BA type in the BA control field can be a multi-STA BA variant.

[0492] - The BA information field of the LLT BA frame is the same as the BA information field of the multi-STA BA frame, but the format of the Per AID TID Info subfield for LLT of the LLT BA frame may be different.

[0493] Specifically, the AID TID information field of the AID TID-specific information subfield of the LLT BA frame may be applied to at least one of the following items.

[0494] - When a non-AP STA or / and an AP transmits an LLT BA frame, the AID 11 subfield value of the AID TID-specific information subfield (for LLT) may be set to 0 or a specific value. For example, when a non-AP STA or / and an AP transmits an LLT BA frame, the AID 11 subfield value may be set to a value other than 0 (e.g., 1 or 2008, etc.). Additionally or alternatively, at this time, the ACK type subfield and the TID subfield of the AID TID-specific information subfield for LLT may be set to any value. For example, since a non-AP STA or AP transmits a multi-STA BA frame only to an AP or other STAs, the other STAs or APs can determine the presence or absence of the LLT information field through the specific AID value.

[0495] - When a non-AP STA or AP transmits a PPDU to one STA, the value of the AID 11 subfield of the AID TID-specific information subfield (for LLT) may be set to the 11 LSB of the AID of that STA or AP. Additionally or alternatively, when a non-AP STA or AP transmits a PPDU to one or more non-AP STAs, the value of the AID 11 subfield of the AID TID-specific information subfield (for LLT) may be set to a specific value (e.g., 0 or one of 2008 to 2044).

[0496] - The ACK type subfield of the AID TID-specific information subfield (for LLT) can be set to a specific value (e.g., 0 or 1).

[0497] - The TID subfield of the AID TID-specific information subfield (for LLT) may be set to a specific value (e.g., one of 8 to 15), except when the ACK type subfield value is set to 1 and the TID subfield value is set to 15.

[0498] - The LLT information field may be present following the AID 11 subfield, the ACK type subfield, and the TID subfield that satisfy the conditions described above. For example, if there is an AID TID information field that satisfies the conditions described above (e.g., an AID TID information field including an AID 11 subfield, an ACK type subfield, and a TID subfield), the LLT information field may be present on the AID TID-specific information subfield (for LLT).

[0499] - Additionally or alternatively, if an AID TID information field that satisfies the conditions described above (e.g., an AID TID information field including an AID 11 subfield, an ACK type subfield, and a TID subfield) is present, the Block ACK Start Sequence Control field or / and the Block ACK Bitmap field may not be present on the LLT BA frame.

[0500] Additionally or alternatively, if a specific value is set to match the conditions described above for the AID TID information field, the LLT information field may be present or included (on the LLT BA frame) instead of the Block ACK Start Sequence Control field and the Block ACK Bitmap field.

[0501] Additionally or alternatively, if a specific value is set to match the conditions described above for the AID TID information field, the LLT information field may be included instead of the Block ACK Start Sequence Control field and the Block ACK Bitmap field. Additionally or alternatively, the size of the LLT information field may be the length of the LLT information itself. Additionally or alternatively, the Block ACK Start Sequence Control field length and / or the Block ACK Bitmap field length may be included on the LLT information field.

[0502] FIG. 32 is a diagram for explaining the configuration of an LLT BA frame for multi-TID and the transmission and reception procedure of LLT BA as an embodiment of the present disclosure.

[0503] The AP may first obtain a TXOP through a CTS / RTS exchange and then transmit a PPDU to STA 1. In this example, the PPDU may include a multi-TID A-MPDU containing QoS data frame(s) for each of TID 1 and TID 2. The PPDU may include information to trigger the AP to transmit LLT information.

[0504] The AP receiving the corresponding PPDU may respond by transmitting an LLT BA frame (i.e., a multi-STA BA frame including LLT information or a new type of LLT BA frame) to STA 1. As illustrated in FIG. 32, the corresponding LLT BA frame may include a Per AID TID info subfield for ACK information for the QoS data frames included in the A-MPDU (i.e., QoS data frames for TID 1 and TID 2).

[0505] Additionally, the AID TID-specific information subfield containing LLT information may indicate the presence of LLT information subsequent to the AID TID-specific information subfield using a specific ACK type (e.g., 0) and TID (e.g., 14) value. Accordingly, the AP may transmit the LLT information to STA 1 simultaneously with the ACK information for the data frame using the LLT BA frame.

[0506] Additionally or alternatively, STA 1, which has received LLT information from AP, may transmit ACK information to AP in response to the LLT information. Here, ACK may mean that STA, which has received LLT information, allows LLT transmission of AP or another STA within its TXOP. The ACK transmitted by STA may include LLT Tx permission information and / or LLT Tx interval information, as described above. AP, which has transmitted LLT information to STA 1 or received ACK for LLT information from STA 1, may transmit LLT to STA 2.

[0507] According to the present disclosure, a BA frame can be transmitted including LLT information, and LLT information equal to or greater than the length of the BA information field can be included in the BA frame. In addition, the BA frame can also be applied to multi-TID based transmission.

[0508] Example 6-3

[0509] In one embodiment of the present disclosure, a field of the MAC header may be utilized to transmit LLT information.

[0510] As an example of the present disclosure, an AP may transmit a PPDU (e.g., an A-MPDU) including a more data field to STA 1. The more data field may include LLT presence information indicating the presence of LLT information. For example, if a PPDU with a more data field value set to 1 is transmitted to the AP, this may indicate that LLT information to be transmitted by the AP exists.

[0511] Additionally or alternatively, the STA may transmit a PPDU (e.g., A-MPDU) including a QoS control field to the AP. When bit 4 of the QoS control field is set to 0 or 1, bit 7 of the QoS control field may indicate the presence or absence of LLT information and / or LLT presence. In this case, bit 7 of the QoS control field may be set to 0 or 1. As described above, when bit 4 of the QoS control field is set to 0 or 1 and bit 7 of the QoS control field is set to indicate the presence or absence of LLT information, LLT information may be set via at least one of bits 8 to 15 of the QoS control field.

[0512] FIG. 33 is a diagram for explaining a method of transmitting LLT information using a MAC header according to one embodiment of the present disclosure.

[0513] As illustrated in FIG. 33, STA 1 may first obtain a TXOP through an RTS / CTS exchange and then transmit a PPDU to the AP. In this example, an A-MPDU containing QoS data frame(s) on the PPDU may be transmitted to the AP.

[0514] The PPDU may include information that triggers the AP to transmit LLT information. The AP receiving the PPDU may transmit the more data field and / or the QoS control field containing the LLT information to STA 1 using the A-MPDU. At this time, the more data field and / or the QoS control field may be included in the BA frame, the QoS data frame, or / and the QoS null frame of the A-MPDU.

[0515] As an example of the present disclosure, if a BA frame includes a QoS control field, the BA frame may be defined as a new control frame or BA type. Accordingly, the AP may transmit LLT information to STA 1 simultaneously with ACK information for the data frame using the BA frame.

[0516] For example, if the ACK policy is set to a policy requiring immediate response to BA frames (e.g., implicit BAR), the PPDU transmitted by the AP on the BA frame may include BA information (for QoS data) for the MPDU(s). As another example, if the ACK policy is set to a policy not requiring immediate response to BA frames (e.g., the ACK policy is set to BA), the PPDU transmitted by the AP on the BA frame may not include BA information (for QoS data) for the MPDU(s).

[0517] Additionally or alternatively, STA 1, which has received LLT information from AP, may transmit ACK information to AP in response to the LLT information. Here, ACK may mean that STA, which has received LLT information, allows LLT transmission of AP or another STA within its TXOP. The ACK transmitted by STA may include LLT Tx permission information and / or LLT Tx interval information, as described above. AP, which has transmitted LLT information to STA 1 or received ACK for LLT information from STA 1, may transmit LLT to STA 2.

[0518] In the present disclosure, the AP can transmit LLT information to STA 1 simultaneously with multiple frames such as BA frames and data frames.

[0519] Example 6-4

[0520] In one embodiment of the present disclosure, a previously defined frame (e.g., a CTS frame, a CTS-to-self frame, an ACK frame) or a new type of frame (e.g., an LLT Tx request frame, etc.) may be utilized based on a predefined frame transmission condition or a condition indicated in a PPDU / frame that triggers transmission of LLT information (or / and LLT). The PPDU / frame that triggers transmission of LLT information (or / and LLT) may satisfy at least one of the conditions described below.

[0521] - The above PPDU / frame may include LLT information. Additionally or alternatively, the PPDU / frame itself may mean LLT information. For example, when an AP / non-AP STA transmits the PPDU / frame, it may mean that there is an LLT that the AP / non-AP STA currently needs to transmit. Additionally or alternatively, when an AP / non-AP STA transmits the PPDU / frame, it may mean that the AP / non-AP STA wants to transmit LLT to another STA within the TXOP of the specific STA.

[0522] - The above PPDU / frame may include information indicating the duration length of the PPDU / frame. That is, the information indicating the duration length may refer to the length of the PPDU / frame that must be satisfied when the LLT Tx request frame is transmitted. Additionally or alternatively, when an existing frame (e.g., a CTS frame, a CTS-to-self frame, an ACK frame) is used, the information indicating the duration length may refer to the length of the PPDU / frame included in the existing frame.

[0523] - The PPDU / frame may include information about the bandwidth over which the PPDU / frame is to be transmitted. For example, if the condition of the PPDU / frame or the condition for triggering transmission of LLT information (or / and LLT) is a dynamic bandwidth, this may mean that the bandwidth is a channel that can be transmitted / used via CCA. As another example, if the condition is 20 MHz, when the PPDU / frame is transmitted, the primary 20 MHz channel or the 20 MHz channel among the secondary channels may be utilized when transmitting the PPDU / frame.

[0524] - The PPDU / frame may include information about the PPDU type associated with the PPDU / frame. For example, if the condition of the PPDU / frame or the condition for triggering transmission of LLT information (or / and LLT) is a non-HT PPDU, this may mean that the PPDU / frame should be transmitted as a non-HT or non-HT duplicate PPDU.

[0525] - The PPDU / frame may include information about the data rate / MCS at which the PPDU / frame is transmitted. For example, if the condition for triggering transmission of the PPDU / frame or LLT information (or / and LLT) is 6 Mbps, this may mean that the PPDU / frame should be transmitted at 6 Mbps.

[0526] FIG. 34 is a method for transmitting and receiving LLT information through an existing or new frame according to one embodiment of the present disclosure.

[0527] As illustrated in FIG. 34, STA 1 may first obtain a TXOP through an RTS / CTS exchange and then transmit a PPDU to the AP. In this example, an A-MPDU containing QoS data frame(s) on the PPDU may be transmitted to the AP.

[0528] The PPDU may include information that triggers the AP to transmit LLT information. The AP, upon receiving the PPDU, may transmit the LLT information to STA 1 using an LLT Tx request frame. As illustrated in FIG. 21, the frame / PPDU including the LLT Tx request frame may be transmitted to STA 1 under the condition that the length of the frame / PPDU using a non-HT duplicate PPDU is 50 us and the data rate is 6 Mbps.

[0529] Additionally or alternatively, the LLT Tx Request frame itself may imply LLT information. For example, when an AP transmits a PPDU / frame containing an LLT Tx Request frame, it may mean that the AP currently has LLT to transmit, or / and that the AP wants to transmit LLT within a TXOP of another STA.

[0530] Additionally or alternatively, the LLT TX request frame may be transmitted to STA 1 while satisfying the conditions described above. Additionally or alternatively, the LLT TX request frame may be replaced with a previously defined frame (e.g., a CTS frame, a CTS-to-self frame, an ACK frame). If the LLT TX request frame is replaced with a previously defined frame, the frame may also satisfy the conditions described above (e.g., a condition that the type of the PPDU / frame is a non-HT duplicate PPDU, a condition that the transmission rate is 6 Mbps, etc.).

[0531] Additionally or alternatively, the transmission conditions of the LLT TX request frame may be included in a PPDU containing information that triggers STA 1 to transmit LLT information to the AP (i.e., a PPDU transmitted by STA 1 to the AP).

[0532] Additionally or alternatively, STA 1, which has received LLT information from AP, may transmit ACK information to AP in response to the LLT information. Here, ACK may mean that STA, which has received LLT information, allows LLT transmission of AP or another STA within its TXOP. The ACK transmitted by STA may include LLT Tx permission information and / or LLT Tx interval information, as described above. AP, which has transmitted LLT information to STA 1 or received ACK for LLT information from STA 1, may transmit LLT to STA 2.

[0533] According to the present disclosure, LLT transmission may be requested using a frame based on minimum PPDU / frame conditions.

[0534] Example 7

[0535] Embodiment 7 relates to a procedure and related parameters for triggering LLT information. As described above, LLT information may be indicated by one or more frames, and thus a procedure for triggering LLT information may be required. Triggering of LLT information may be performed via the HT control field (Embodiment 7-1) and / or the PHY preamble / header (Embodiment 7-2).

[0536] Example 7-1

[0537] In one embodiment of the present disclosure, triggering of LLT information (or / and LLT) may be performed via an HT control field. That is, information for transmitting LLT information (or / and LLT) may be included in an HT control field (e.g., an A-control field), and a new control field having a control type of the A-control field may be configured for LLT information (or / and LLT).

[0538] The above control field may include information on one or more conditions for transmitting LLT information (or / and LLT). The one or more conditions for transmitting LLT information (or / and LLT) may include conditions related to LLT Tx poll, frame type, PPDU / frame duration (e.g., X us), bandwidth, PPDU type, and data rate / MCS, respectively.

[0539] The LLT Tx Poll information / condition may indicate whether to trigger / request LLT information (or / and LLT) transmission. For example, the LLT Tx Poll information / condition may consist of a 1-bit field. If the value of the field is set to 0 (or 1), this may mean to trigger / request LLT information (or / and LLT) transmission. Additionally or alternatively, if information indicating whether to trigger / request LLT information (or / and LLT) transmission is included in the control field, the control field may be interpreted as indicating an LLT Tx poll.

[0540] Information / conditions related to the frame type may include information / conditions regarding which frame the LLT information (or / and LLT) should be transmitted in. For example, as described above, the LLT information (or / and LLT) may be transmitted and received via an LLT Tx request frame, a CTS frame, a CTS-to-Self frame, or an ACK frame.

[0541] Information / conditions related to the duration of a PPDU / frame may include information / conditions indicating the length of a PPDU / frame including LLT information (or / and LLT). That is, the information indicating the length of the duration may refer to the length of a PPDU / frame that must be satisfied when an LLT Tx request frame is transmitted. Additionally or alternatively, when a conventional frame (e.g., a CTS frame, a CTS-to-self frame, an ACK frame) is used, the information indicating the length of the duration may refer to the length of a PPDU / frame included in the conventional frame.

[0542] Information / conditions related to bandwidth may include information about the bandwidth over which a PPDU / frame containing LLT information (or / and LLT) is to be transmitted. For example, if the condition of the PPDU / frame or the condition for triggering transmission of the LLT information (or / and LLT) is a dynamic bandwidth, this may mean that the bandwidth is a channel that can be transmitted / available via CCA. As another example, if the condition is 20 MHz, when the PPDU / frame is transmitted, a primary 20 MHz channel or a secondary channel among the 20 MHz channels may be utilized when transmitting the PPDU / frame.

[0543] Information / conditions related to the PPDU type may include information / conditions on the PPDU type in which the PPDU / frame containing the LLT information (or / and LLT) must be transmitted. For example, if the condition of the PPDU / frame or the condition for triggering transmission of the LLT information (or / and LLT) is a non-HT PPDU, this may mean that the PPDU / frame must be transmitted as a non-HT or non-HT duplicate PPDU.

[0544] Information / conditions related to data rate / MCS may include information / conditions regarding the data rate / MCS when a PPDU / frame containing LLT information (or / and LLT) is transmitted. For example, if the condition of the PPDU / frame or the condition for triggering transmission of LLT information (or / and LLT) is 6 Mbps, this may mean that the PPDU / frame should be transmitted at 6 Mbps.

[0545] FIG. 35 is a diagram illustrating a method for triggering LLT information transmission using a control field according to one embodiment of the present disclosure.

[0546] STA 1 can first obtain a TXOP through an RTS / CTS frame exchange and then transmit a PPDU to the AP. Here, the PPDU can include an A-MPDU containing QoS data frame(s). In addition, information that triggers the AP to transmit LLT information can be included in the HT control field (e.g., the A-control field) of the PPDU.

[0547] In Fig. 35, the PPDU may include various types of information / conditions (e.g., PPDU / frame duration, bandwidth, PPDU type, data rate, MCS, etc.) for transmission of LLT information (or / and LLT). For example, the PPDU / frame duration may be 50 us, the bandwidth may be set dynamically (i.e., set to the available bandwidth via CCA), the PPDU type may be a non-HT replicated PPDU, and the data rate may be 6 Mbps. Accordingly, the LLT Tx request frame may be transmitted and received based on the various types of information / conditions described above.

[0548] Additionally or alternatively, the LLT Tx Request frame itself may imply LLT information. For example, when an AP transmits an LLT Tx Request frame, it may mean that there is an LLT that the AP currently needs to transmit, or / and that the AP wants to transmit an LLT within the TXOP of a specific STA (e.g., STA 1).

[0549] Additionally or alternatively, the LLT Tx request frame may not include information that triggers LLT information. In this case, the AP may transmit LLT information (or / and LLT) that satisfies the conditions as in FIG. 35 (i.e., various types of conditions for transmitting LLT information (or / and LLT)).

[0550] Additionally or alternatively, the LLT Tx request frame may be replaced with an existing frame (e.g., a CTS frame, a CTS-to-Self frame, an ACK frame, etc.). For example, if the LLT Tx request frame is replaced with an existing frame, the existing frame may also satisfy various types of conditions for transmission of the LLT information (or / and LLT) described above.

[0551] Additionally or alternatively, STA 1, which has received LLT information from AP, may transmit ACK information to AP in response to the LLT information. Here, ACK may mean that STA, which has received LLT information, allows LLT transmission of AP or another STA within its TXOP. The ACK transmitted by STA may include LLT Tx permission information and / or LLT Tx interval information, as described above. AP, which has transmitted LLT information to STA 1 or received ACK for LLT information from STA 1, may transmit LLT to STA 2.

[0552] By the present disclosure, transmission of LLT information can be requested after setting conditions related to the HT control field appropriately.

[0553] Example 7-2

[0554] In one embodiment of the present disclosure, triggering of LLT information (or / and LLT) may be performed via a PHY preamble / header. In this case, the PHY preamble / header may refer to the PHY preamble / header of a PPDU for triggering transmission of LLT information (or / and LLT). For example, the PHY preamble / header may include one or more pieces of information for transmitting LLT information (or / and LLT).

[0555] As an example of the present disclosure, a field that triggers transmission of LLT information (or / and LLT) (e.g., a field indicating whether LLT information / LLT transmission is required, etc.) may be included in the PHY header. That is, whether or not LLT telegram transmission is allowed may be indicated through the field.

[0556] Additionally or alternatively, one or more conditions / information for transmitting LLT information (or / and LLT) as described in Embodiment 3-1 may be included in a PPDU (e.g., PHY header / preamble of a PPDU) that includes / does not include information that triggers LLT information (or / and LLT).

[0557] Additionally or alternatively, a PHY header / preamble containing fields that trigger LLT information (or / and LLT) transmission is included in the PPDU / frame transmitted to the AP, and a response to that PPDU / frame may be an existing frame (e.g., CTS frame, CTS-to-Self frame, ACK frame, etc.) or a new type of frame (e.g., LLT Tx Request frame).

[0558] Additionally or alternatively, CCA may be performed when an LLT Tx request frame is transmitted. For example, an AP / non-AP STA may perform an energy detection operation during an interval (e.g., SIFS) after receiving an LLT poll frame (e.g., a PPDU that triggers transmission of LLT information (or / and LLT)) and before an LLT indication transmission (e.g., transmission of an LLT Tx request frame or LLT information (or / and LLT)).

[0559] Additionally or alternatively, the LLT Tx request frame may be transmitted with one or more 20 MHz channels excluded (e.g., punctured) for which the channel state is identified as "BUSY" based on the CCA results.

[0560] Additionally or alternatively, the rules described below may apply to transmission of LLT Tx request frames according to CCA.

[0561] - If the status of the secondary 20 MHz channel is "BUSY", the LLT Tx request frame may not be transmitted on the secondary 20 MHz channel. That is, the LLT Tx request frame may be transmitted only on the primary 20 MHz channel.

[0562] - If the status of one or more 20 MHz channels among the secondary 40 MHz channels is “BUSY”, the LLT Tx request frame may not be transmitted on the secondary 40 MHz channel.

[0563] - If the status of one or more 20 MHz channels among the secondary 80 MHz channels is “BUSY”, the LLT Tx request frame may not be transmitted on the secondary 80 MHz channel.

[0564] - If the status of one or more 20 MHz channels among the secondary 160 MHz channels is “BUSY”, the LLT Tx request frame may not be transmitted on the secondary 160 MHz channel.

[0565] FIG. 36 is a diagram for explaining a method for triggering LLT information transmission using a PHY header according to one embodiment of the present disclosure.

[0566] STA 1 can first obtain a TXOP through an RTS / CTS frame exchange and then transmit a PPDU to the AP. Here, the PPDU can include an A-MPDU containing QoS data frame(s). In addition, information that triggers the AP to transmit LLT information (or / and LLT) can be included in the PHY preamble / header of the PPDU. Specifically, the PHY header can include a field (e.g., an LLT information Tx field, etc.) indicating whether the LLT information (or / and LLT) needs to be transmitted.

[0567] In Fig. 36, the PPDU may include various types of information / conditions (e.g., PPDU / frame duration, bandwidth, PPDU type, data rate, MCS, etc.) for transmission of LLT information (or / and LLT). For example, the PPDU / frame duration may be 50 us, the bandwidth may be set dynamically (i.e., set to the available bandwidth via CCA), the PPDU type may be a non-HT replicated PPDU, and the data rate may be 6 Mbps. Accordingly, the LLT Tx request frame may be transmitted and received based on the various types of information / conditions mentioned above.

[0568] Additionally or alternatively, the LLT Tx Request frame itself may imply LLT information. For example, when an AP transmits an LLT Tx Request frame, it may mean that there is an LLT that the AP currently needs to transmit, or / and that the AP wants to transmit an LLT within the TXOP of a specific STA (e.g., STA 1).

[0569] Additionally or alternatively, the LLT Tx request frame may not include information that triggers LLT information. In this case, the AP may transmit LLT information (or / and LLT) that satisfies the conditions as in FIG. 23 (i.e., various types of conditions for transmitting LLT information (or / and LLT)).

[0570] Additionally or alternatively, the LLT Tx request frame may be replaced with an existing frame (e.g., a CTS frame, a CTS-to-Self frame, an ACK frame, etc.). For example, if the LLT Tx request frame is replaced with an existing frame, the existing frame may also satisfy various types of conditions for transmission of the LLT information (or / and LLT) described above.

[0571] Additionally or alternatively, the transmission conditions of the LLT Tx request frame may be included in the PPDU that STA 1 uses to trigger the AP to transmit LLT information (or / and LLT).

[0572] Additionally or alternatively, STA 1, which has received LLT information from AP, may transmit ACK information to AP in response to the LLT information. Here, ACK may mean that STA, which has received LLT information, allows LLT transmission of AP or another STA within its TXOP. The ACK transmitted by STA may include LLT Tx permission information and / or LLT Tx interval information, as described above. AP, which has transmitted LLT information to STA 1 or received ACK for LLT information from STA 1, may transmit LLT to STA 2.

[0573] The above-described examples of the present disclosure enable transmission and reception of LLT information (or / and LLT) with minimal overhead.

[0574] Example 7-3

[0575] In one embodiment of the present disclosure, a method of triggering LLT transmission may be applied in addition to the method of triggering transmission of LLT information described in Embodiments 7-1 and 7-2.

[0576] For example, there may be a case where an AP (i.e., a TXOP responder) needs to quickly transmit an LLT for STA 1 (i.e., a TXOP holder) to STA 1. That is, a method of triggering an LLT transmission directly to the TXOP responder may be applied.

[0577] As an example of the present disclosure, STA 1 (e.g., TXOP holder) can transmit information related to whether to trigger transmission of a certain frame / information (i.e., LLT triggering mode information) to another STA (e.g., TXOP responder).

[0578] For example, as described above, the LLT triggering mode can be divided into a first mode that triggers a frame containing LLT information (e.g., an LLT Tx request frame), a second mode that enables transmission of LLT (e.g., a QoS data frame), and a third mode that allows both the first mode and the second mode.

[0579] Additionally or alternatively, a triggering frame may be defined as a frame itself that allows transmission of LLT (e.g., QoS data frames) without an LLT triggering mode.

[0580] Additionally or alternatively, a STA that receives a triggering frame without setting the LLT triggering mode can determine at least one of the LLT information or LLT to be transmitted by the STA.

[0581] FIG. 37 is a diagram illustrating a method for triggering LLT to a TXOP responder according to one embodiment of the present disclosure. That is, FIG. 37 relates to a method for triggering LLT transmission using a control field.

[0582] STA 1 can first obtain a TXOP through an RTS / CTS frame exchange and then transmit a PPDU to the AP. Here, the PPDU can include QoS data frame(s), a QoS null frame, and an A-MPDU containing a control field for LLT transmission in each frame. At this time, the AP can perform an immediate response operation for the QoS data frame by including a BA frame in the A-MPDU, and at the same time, perform a response operation for the control field (i.e., LLT transmission operation).

[0583] Additionally or alternatively, the control field may include information on an LLT triggering mode that enables LLT transmission. Additionally or alternatively, one or more conditions / information for LLT transmission described in Embodiment 7-1 may be included in the PPDU. Additionally or alternatively, LLT for STA 1 may not exist. Additionally or alternatively, an STA (e.g., an AP) that receives the control field without an LLT triggering mode may determine which data the STA will transmit among the LLT and / or LLT information. For example, in FIG. 24, the AP may transmit a frame (e.g., an LLT Tx request frame) containing LLT information for another STA (e.g., STA 2) instead of LLT.

[0584] FIG. 38 is a diagram illustrating a method for triggering LLT to a TXOP responder according to one embodiment of the present disclosure. That is, FIG. 38 relates to a method for triggering LLT transmission using a PHY header / preamble.

[0585] STA 1 can first obtain a TXOP through an RTS / CTS frame exchange and then transmit a PPDU to the AP. Here, the PPDU can include QoS data frame(s), a QoS null frame, and a PHY header / preamble for LLT transmission in each frame. At this time, the AP can perform an immediate response operation for the QoS data frame, including the BA frame, and at the same time, perform a response operation for the PHY header / preamble (i.e., LLT transmission operation).

[0586] Additionally or alternatively, the PHY header / preamble may include information on an LLT triggering mode that enables LLT transmission. Additionally or alternatively, one or more conditions / information for LLT transmission described in Embodiment 7-2 may be included in the PPDU. Additionally or alternatively, LLT for STA 1 may not exist. Additionally or alternatively, an STA (e.g., an AP) that receives a PHY header / preamble without an LLT triggering mode may determine which data the STA will transmit among the LLT and / or LLT information. For example, in FIG. 37, the AP may transmit a frame (e.g., an LLT Tx request frame) containing LLT information for another STA (e.g., STA 2) instead of LLT.

[0587] According to the above-described embodiment, the AP may receive one or more PPDUs / frames from the STA that trigger transmission of LLT information (or / and LLT), and the information for transmitting the LLT information (or / and LLT) may be transmitted and received via the HT control field (e.g., the A-control field) or the PHY preamble / header.

[0588] As described above, the HT control field may include information for LLT information / LLT transmission (e.g., at least one of LLT Tx poll information, frame type, PPDU / frame duration (e.g., X us), bandwidth, PPDU type, data rate / MCS and / or LLT triggering mode). Each type of information for LLT information / LLT transmission has been described above, so a redundant description will be omitted.

[0589] Here, the LLT triggering mode may be defined as a first mode that triggers a frame containing LLT information / LLT (e.g., an LLT Tx request frame), a second mode that enables transmission of LLT (e.g., a QoS data frame), and a third mode that allows both the first mode and the second mode. Additionally or alternatively, an STA that receives a control field without an LLT triggering mode may determine which data the STA will transmit among the LLT or / and the LLT information.

[0590] As another example of the present disclosure, when one or more PPDUs / frames that trigger LLT information (or / and LLT) transmission are included in the PHY header / preamble, a field that triggers LLT information (or / and LLT) transmission may be included in the PHY header / preamble. Additionally or alternatively, the PHY header / preamble may include information on an LLT triggering mode for transmitting LLT. For example, the LLT information Tx field and the field indicating the LLT triggering mode may be separated / combined. When the LLT information Tx field and the field indicating the LLT triggering mode are separated, each of the LLT information Tx field and the field indicating the LLT triggering mode may indicate whether LLT information transmission is required and whether LLT transmission is required.

[0591] Example 8

[0592] Embodiment 8 relates to the above-described LLT information and / or a method for triggering LLT. As an example of the present disclosure, a triggering frame including information for transmitting LLT information may be used to trigger LLT information and / or LLT.

[0593] Additionally or alternatively, the triggering frame itself may imply that LLT information is transmitted.

[0594] Additionally or alternatively, the triggering frame may be a variant of the triggering frame. The variant may be an existing variant (e.g., MU-RTS (TXS), BSRP) or a newly defined variant. For example, the MU-RTS TXS triggering frame may be used (for LLT information triggering), and a new triggered TXOP sharing mode related to LLT information transmission may be defined. Accordingly, the AP / STA may respond to the triggering frame.

[0595] Additionally or alternatively, the triggering frame may use the format of the basic trigger frame variant, but may indicate the triggering of LLT information through a reserved bit (e.g., a reserved bit or an EHT reserved bit) in the common information field. For example, when a BSRP trigger frame or a basic trigger frame is transmitted, the common information field of the trigger frame may include information indicating that LLT information is triggered. Accordingly, the STA may transmit LLT information instead of BSR in response to the trigger frame.

[0596] A triggering frame can allocate an RU to a specific STA, and can also allocate one or more RA (random access)-RUs that one or more STAs can access using uplink OFDMA-based random access (UORA). An STA that receives a triggering frame can transmit LLT information in the allocated RU or, if it wins contention in the RA-RU.

[0597] Additionally or alternatively, the user information field that allocates RU / bandwidth or RA-RU may include information (or bits) indicating that LLT information is triggered. This allows the purpose of an RU to be distinguished through a single trigger frame. For example, information indicating that LLT information is triggered may be indicated through a reserved bit in the user information field of the trigger frame. In one example of the present disclosure, the triggering frame may be a management frame (e.g., an action frame).

[0598] Additionally or alternatively, the triggering frame may additionally include the information / conditions described below for transmitting LLT information:

[0599] - Frame Type: This indicates the type of frame in which LLT information will be transmitted. That is, frame type information may include information regarding which frame the LLT information should be transmitted in. For example, frame type information may be transmitted through the LLT Tx request frame described in the LLT information transmission method and other frames (e.g., CTS, CTS-to-self, Ack frames).

[0600] - PPDU / Frame Duration (e.g., X us): This indicates the length of the PPDU / frame in which the LLT information is transmitted. For example, the PPDU / Frame Duration information may indicate the length of the frame / PPDU that must be satisfied when the LLT Tx request frame is transmitted.

[0601] Additionally or alternatively, when existing frames (e.g., CTS, CTS-to-self, Ack frames, etc.) are used, the PPDU / frame duration information may be indicated through PPDU / length information included in the existing frame.

[0602] - Bandwidth: This indicates the bandwidth of the PPDU / frame containing LLT information transmitted. For example, if the condition is dynamic bandwidth, when the frame is transmitted, the bandwidth information may indicate the available / transmittable channels via CCA. Another example is if the bandwidth condition is 20MHz, when the frame is transmitted, either the primary 20MHz channel or the secondary 20MHz channel may be utilized.

[0603] - PPDU Type: This may indicate the PPDU type that the PPDU / frame containing LLT information must be transmitted. For example, if the condition related to the PPDU type is non-HT PPDU, this may indicate that the PPDU / frame is a non-HT or non-HT duplicate PPDU.

[0604] - Data rate / MCS: This can refer to the data rate / MCS at which the PPDU / frame containing LLT information should be transmitted. For example, if the data rate condition is 6 Mbps, this could mean that the frame should be transmitted at 6 Mbps.

[0605] FIG. 39 is a diagram for explaining an LLT transmission trigger method using a triggering frame according to one embodiment of the present disclosure.

[0606] As an example of the present disclosure, STA 1 may first obtain a TXOP through an RTS / CTS exchange and then transmit a PPDU to the AP. Here, the PPDU may include an A-MPDU containing QoS data frame(s) and a triggering frame. Additionally or alternatively, the A-MPDU may only include a triggering frame.

[0607] In Fig. 39, the ACK policy of one or more QoS data frames transmitted as a triggering frame may be set to Block ACK or No ACK. In this case, the AP may not transmit BA as an immediate response. Alternatively, if a triggering frame that triggers the transmission of one or more QoS data frames and LLT information is included in an A-MPDU, the ACK policy for the BA for the QoS data frames may be defined as an ACK policy that allows for a later response (hereinafter, LLT ACK policy).

[0608] Additionally or alternatively, an A-PPDU containing an MPDU with an LLT ACK policy may be included in a UHR PPDU or a later version PPDU. Additionally or alternatively, the ACK information of a BA to respond in the future may include the BA responding to a BAR (BlockACK Request) frame or the BA for a QoS data frame to be transmitted in the future.

[0609] The AP may transmit an LLT Tx Request frame containing LLT information in response to the triggering frame. Additionally or alternatively, the LLT Tx Request frame itself may imply LLT information. For example, if the AP transmits the corresponding PPDU / frame (e.g., an LLT Tx Request frame), it may indicate that the AP currently has LLT to transmit. Furthermore, the LLT Tx Request frame may also be interpreted as a request by the AP to transmit LLT in the TXOP of an STA.

[0610] Additionally or alternatively, a condition such as in FIG. 20 may be predetermined, and when the condition is satisfied, the LLT Tx request frame may be transmitted without information that triggers LLT information. Additionally or alternatively, the LLT Tx request frame may be replaced with an existing frame (e.g., a CTS, CTS-to-Self, ACK frame, etc.). For example, when the LLT Tx request frame is replaced with an existing frame, the existing frame may also satisfy conditions such as non-HT duplicate PPDU, 6 Mbps, etc.

[0611] An AP that transmits an LLT Tx request frame may transmit LLT to a target STA (e.g., STA 2). Additionally or alternatively, an STA that receives LLT information from an AP may transmit an ACK in response to the LLT information. For example, the ACK may mean that the STA that received the LLT information allows LLT transmission from the AP or another STA in the TXOP. Here, the ACK may be the ACK in FIG. 14. An AP that transmits LLT information or receives an ACK for LLT information from STA 1 may transmit LLT to STA 2.

[0612] In the present disclosure, a triggering frame can be transmitted by adjusting whether or not a QoS data frame is included and an ACK policy, etc., according to the situation using A-MPDU.

[0613] FIG. 40 is a diagram for explaining an LLT transmission trigger method using a triggering frame according to one embodiment of the present disclosure.

[0614] As an example of the present disclosure, STA 1 may first obtain a TXOP through an RTS / CTS exchange and then transmit a PPDU to the AP. Here, the PPDU may include an A-MPDU containing QoS data frame(s) and a triggering frame. Additionally or alternatively, the A-MPDU may only include a triggering frame.

[0615] In Fig. 40, the ACK policy of one or more QoS data frames transmitted with the triggering frame may be set to implicit BAR ACK. In this case, the A-MPDU transmitted by the AP may include a BA (i.e., immediate response) and an LLT Tx request frame, which is a response to the triggering frame.

[0616] The AP may transmit an LLT Tx Request frame containing LLT information in response to the triggering frame. Additionally or alternatively, the LLT Tx Request frame itself may imply LLT information. For example, if the AP transmits the corresponding PPDU / frame (e.g., an LLT Tx Request frame), it may indicate that the AP currently has LLT to transmit. Furthermore, the LLT Tx Request frame may also be interpreted as a request by the AP to transmit LLT in the TXOP of an STA.

[0617] Additionally or alternatively, a condition such as in FIG. 20 may be predetermined, and when the condition is satisfied, the LLT Tx request frame may be transmitted without information that triggers LLT information. Additionally or alternatively, the LLT Tx request frame may be replaced with an existing frame (e.g., a CTS, CTS-to-Self, ACK frame, etc.). For example, when the LLT Tx request frame is replaced with an existing frame, the existing frame may also satisfy conditions such as non-HT duplicate PPDU, 6 Mbps, etc.

[0618] An AP that transmits an LLT Tx request frame may transmit LLT to a target STA (e.g., STA 2). Additionally or alternatively, an STA that receives LLT information from an AP may transmit an ACK in response to the LLT information. For example, the ACK may mean that the STA that received the LLT information allows LLT transmission from the AP or another STA in the TXOP. Here, the ACK may be the ACK in FIG. 13. An AP that transmits LLT information or receives an ACK for LLT information from STA 1 may transmit LLT to STA 2.

[0619] That is, in the present disclosure, a response to a triggering frame can be transmitted simultaneously with a BA using an A-MPDU.

[0620] Additionally, the triggering frame described above can trigger a Tx request frame for transmitting LLT information. Here, in FIG. 13, there may be a situation where the AP (i.e., TXOP responder) needs to quickly transmit the LLT for STA 1 (i.e., TXOP holder) to STA 1. The triggering frame can also be used in the above-described situation. For example, the triggering frame can include information about the LLT triggering mode (i.e., information indicating the mode associated with the frame / information to be triggered).

[0621] For example, information about the LLT triggering mode may indicate one of a mode that triggers a frame containing LLT information (e.g., an LLT Tx request frame), as in FIG. 20 and FIG. 12, a mode that allows transmission of LLT (e.g., a QoS data frame) (e.g., as a TXOP holder), or a mode that allows both of the above modes.

[0622] Additionally or alternatively, an STA that receives a triggering frame without an LLT triggering mode may decide whether to transmit LLT information, LLT only, or both LLT information and LLT.

[0623] FIG. 41 is a diagram illustrating a method for triggering LLT to a TXOP responder according to one embodiment of the present disclosure.

[0624] Figure 41 illustrates an example of triggering LLT transmission using a triggering frame. As an example of the present disclosure, STA 1 may first obtain a TXOP through an RTS / CTS exchange and then transmit a PPDU to the AP. Here, the PPDU may include an A-MPDU containing QoS data frame(s) and a triggering frame. Additionally or alternatively, the A-MPDU may only include the triggering frame.

[0625] In Fig. 41, the ACK policy of one or more QoS data frames transmitted with the triggering frame may be set to implicit BAR ACK. In this case, the A-MPDU transmitted by the AP may include BA (i.e., immediate response) and LLT, which is a response to the triggering frame.

[0626] Additionally or alternatively, the triggering frame may include the aforementioned mode information that enables LLT transmission. Additionally or alternatively, there may be no LLT for STA 1. Additionally or alternatively, an STA that receives a triggering frame without LLT triggering mode information may determine whether to transmit LLT information, LLT, or both LLT information and LLT. For example, in FIG. 23, a frame (e.g., LLT Tx Request) containing LLT information for another STA (e.g., STA 2) may be transmitted instead of LLT.

[0627] Example 9

[0628] Example 9 relates to a method of responding to failure and a case in which LLT information is not transmitted.

[0629] When receiving information triggering LLT information and there is no LLT to transmit, the STA may notify other STAs (e.g., APs, etc.) that there is no LLT. Additionally or alternatively, if there is no LLT to transmit, LLT information may not be transmitted or received. That is, the STA (e.g., APs, etc.) that transmitted the information triggering LLT information may not receive LLT information from a specific STA. In this case, at least one of the methods described below may be used.

[0630] - Assume that an STA (e.g., an AP) transmits a PPDU containing information that triggers LLT information, and then LLT information is not received from other STA(s) after a specified period of time (e.g., SIFS). The STA may transmit a PPDU containing information that triggers LLT information after PIFS without receiving LLT information from other STA(s).

[0631] FIG. 42(a) is a diagram for explaining a procedure when LLT information is not transmitted according to an embodiment of the present disclosure. As illustrated in FIG. 42(a), when an AP transmits a first PPDU including triggering information (e.g., information (e.g., frame / field) for triggering LLT information), if other STA(s) do not have LLT to transmit, the AP may transmit the first PPDU and, after a PIFS, transmit a second PPDU including the triggering information. Additionally or alternatively, the second PPDU or / and any PPDU transmitted thereafter may not include triggering information.

[0632] As illustrated in (a) of FIG. 42, when the AP transmits the second PPDU, it is assumed that STA 1 and STA 2 have LLT. STA 1 and STA 2 can transmit LLT information to the AP according to the second PPDU. The AP transmits a trigger frame to STA 1 and / or STA 2 according to the LLT information, and STA 1 and / or STA 2 can transmit LLT based on the trigger frame to the AP.

[0633] Additionally, in order to support a method in which at least one STA transmits and receives response or ACK information related to the presence of LLT, a PPDU transmitted by an AP may include information on an interval (e.g., SIFS, PIFS) after transmission of a PPDU including triggering information. For example, when the interval is SIFS, at least one STA may transmit a response related to the presence of LLT to the AP. When the interval is PIFS, at least one STA may not transmit a response if it does not have LLT. Information on an interval after transmission of a PPDU including triggering information may be included in a PHY header (e.g., U-SIG field) of the PPDU or / and a frame / field that triggers LLT information.

[0634] Meanwhile, (a) of FIG. 42 is an operation in a DL TXOP (i.e., when the AP is the TXOP holder) environment, and (b) of FIG. 42 is an operation in a UL TXOP (i.e., when STA 1 (e.g., a non-AP STA) is the TXOP holder) environment. That is, the operation described above with reference to (a) of FIG. 42 may correspond to the operation according to (b) of FIG. 42. For example, the operation of each of the AP and other STAs in (a) of FIG. 42 may correspond to the operation of STA 1 and the AP in (b) of FIG.

[0635] Example 9-1

[0636] Example 9-1 relates to a procedure when the interval between PPDUs containing triggering information is PIFS.

[0637] As an example of the present disclosure, referring to (a) of FIG. 43 and (a) of FIG. 44, it is assumed that a failure occurs in the first PPDU transmitted by the AP.

[0638] Here, failure may include all cases where the AP transmits a PPDU containing LLT information triggering information to other STA(s), but the other STA(s) do not receive the PPDU and / or fail to successfully transmit LLT information to the AP. For example, failure may occur due to a collision caused by an OBSS STA transmission and / or channel congestion.

[0639] For example, as illustrated in (a) of FIG. 43, failure may occur because other STA(s) do not receive triggering information. As another example, as illustrated in (b) of FIG. 43, the AP may transmit the first PPDU containing triggering information to other STA(s), and the other STA(s) may transmit LLT information to the AP according to the first PPDU. However, failure may occur because the AP does not receive the LLT information transmitted by the other STA(s).

[0640] At this time, the AP may not be able to clearly distinguish whether the transmission of the PPDU containing the triggering information failed or whether the other STA(s) did not transmit the LLT information because they do not have the LLT. In particular, if the LLT information transmitted by the TXOP responder failed (e.g., the LLT information was not transmitted successfully), the TXOP responder may not receive the second PPDU because the second PPDU transmitted by the AP and the LLT information transmitted by the TXOP responder may overlap.

[0641] Here, (a) of FIG. 43 and FIG. 44 is an operation in a DL TXOP (i.e., when the AP is a TXOP holder) environment, and (b) of FIG. 43 and FIG. 44 is an operation in a UL TXOP (i.e., when STA 1 (e.g., a non-AP STA) is a TXOP holder) environment. For example, the operations of the AP and each of the other STAs in (a) of FIG. 43 and FIG. 44 may correspond to the operations of STA 1 and the AP in (b) of FIG. 43 and FIG. 44. Accordingly, the operations of the AP and the other STAs in (a) of FIG. 43 and FIG. 44 described above may be replaced with the operations of STA 1 and the AP in (b) of FIG. 43 and FIG. 44.

[0642] To address the above-described issues, CCA may be performed (by the TXOP holder) during the PIFS interval after the first PPDU containing triggering information is transmitted. Here, CCA may use energy detection (ED) and / or guard interval (GI) detection methods.

[0643] Based on the CCA result, the STA (e.g., the TXOP holder AP or STA 1) that transmitted the first PPDU (e.g., the PPDU transmitted before performing the CCA) can act as described below:

[0644] 1) If the CCA result is "IDLE", the STA (e.g., AP or STA 1, which is the TXOP holder) can transmit a PPDU (containing triggering information) to other STA(s).

[0645] 2) If the CCA result is "BUSY", the STA may not transmit the PPDU (containing the triggering information) to other STA(s). Additionally or alternatively, if the CCA result is "BUSY", the STA may determine that a failure has occurred in the transmission or reception of the PPDU transmitted before the PIFS (e.g., the first PPDU) and perform recovery actions. For example, after a timeout (e.g., "aSIFSTime + aSlotTime + aRxPHYStartDelay" used in EDCA back-off), the STA may transmit the second PPDU containing the triggering information to other STA(s) or perform back-off again if the result during the PIFS is "IDLE".

[0646] Additionally or alternatively, if LLT information is received as a result of the CCA of the AP, the AP may trigger LLT in the manner described above.

[0647] FIG. 45 is a diagram illustrating a method for performing CCA according to an embodiment of the present disclosure. For example, as illustrated in (a) of FIG. 45, an AP may perform CCA during a PIFS after transmitting a first PPDU. If the CCA result is determined to be BUSY (e.g., based on a PPDU transmitted by an STA of an OBSS), the AP may perform a recovery procedure in a TXOP. If it is determined that the PPDU can be transmitted after performing the recovery procedure, the AP may transmit the next PPDU containing triggering information to another STA(s).

[0648] Meanwhile, (a) of FIG. 45 is an operation in a DL TXOP (i.e., when the AP is the TXOP holder) environment, and (b) of FIG. 45 is an operation in a UL TXOP (i.e., when STA 1 (e.g., a non-AP STA) is the TXOP holder) environment. That is, the operation described above with reference to (a) of FIG. 45 may correspond to the operation according to (b) of FIG. 45. For example, the operation of each of the AP and other STAs in (a) of FIG. 45 may correspond to the operation of STA 1 and the AP in (b) of FIG. 45.

[0649] According to various embodiments of the present disclosure, a TXOP holder can transmit LLT on demand by receiving LLT information from one or more STAs, thereby reducing delay and overhead associated with LLT transmission.

[0650] 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.

[0651] 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 of the present disclosure. 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.

[0652] 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.

[0653] The method proposed in this disclosure has been described with a focus on examples applied to IEEE 802.11-based systems, but can be applied to various wireless LANs or wireless communication systems in addition to IEEE 802.11-based systems.

Claims

1. A step of transmitting, by a first station (STA) to a second STA, a first physical layer protocol data unit (PPDU) including first information for triggering transmission of information related to first low latency traffic (LLT); A step of performing a first clear channel assessment (CCA) by the first STA during the first inter-frame space; and A step of transmitting a second PPDU including the first information to the second STA after performing a recovery procedure based on the first CCA result being BUSY, A method wherein the second PPDU is transmitted by the first STA to the second STA based on the first CCA result being IDLE.

2. In paragraph 1, A method wherein a third PPDU for triggering the first LLT transmission is transmitted from the first STA to the second STA based on information related to the first LLT being received from the second STA during the first inter-frame interval.

3. In paragraph 1, A method wherein the second PPDU is transmitted from the first STA to the second STA based on the result of the first CCA, based on the fact that information related to the first LLT is not received from the second STA during the first inter-frame interval.

4. In paragraph 1, A method wherein the first CCA comprises at least one of an energy detection (ED) operation for detecting a signal above a certain intensity or a guard interval (GI) detection operation for detecting a wireless signal.

5. In paragraph 1, After the above recovery procedure is performed, the second CCA is performed by the first STA, A method wherein the second PPDU is transmitted from the first STA to the second STA based on the second CCA result being idle.

6. In paragraph 1, A method wherein the information related to the first LLT includes at least one of information on whether the first LLT exists, identification information of the first LLT, information on a time when the first LLT should be completed for transmission, and information on the amount of the first LLT.

7. In paragraph 1, At least one of the first PPDU and the second PPDU is transmitted to the second STA within a transmission opportunity (TXOP) of the first STA, A method wherein information related to said first LLT or at least one of said first LLTs is received from said second STA within a TXOP of said first STA.

8. In paragraph 1, A method according to claim 1, wherein the first information includes at least one of information about a bandwidth of a fourth PPDU including information related to the first LLT, a PPDU type of the fourth PPDU, data or a modulation and coding scheme (MCS) of the fourth PPDU, or a trigger mode that triggers transmission of information related to the first LLT.

9. In paragraph 1, The above first STA is either an access point (AP) or a non-AP STA, A method wherein the second STA is another one of the AP or the non-AP STA.

10. In paragraph 1, A method according to claim 1, wherein the first inter-frame space comprises one of a short inter frame space (SIFS) or a point coordination function inter frame space (PIFS).

11. In the first station (STA), the first STA: one or more transmitters and receivers; and comprising one or more processors coupled to said one or more transceivers; One or more of the above processors: Transmitting a first physical layer protocol data unit (PPDU) including first information for triggering transmission of information related to first low latency traffic (LLT) to a second STA via the one or more transceivers; performing a first clear channel assessment (CCA) by the first STA during the first inter-frame space; and Based on the above first CCA result being BUSY, the first STA performs a recovery procedure and then transmits a second PPDU including the first information to the second STA through the one or more transceivers. A first STA, wherein the second PPDU is transmitted to the second STA by the first STA based on the first CCA result being IDLE.

12. A step of receiving, by a second station (STA), from a first STA a first physical layer protocol data unit (PPDU) including first information for triggering transmission of information related to first low latency traffic (LLT); and A step of transmitting, by the second STA, information related to the first LLT to the first STA based on the second PPDU including the first information being received from the first STA and the second STA having the first LLT, A method wherein the second PPDU transmission is performed based on the first clear channel assessment (CCA) result of the first STA.

13. In the second station (STA), the second STA: one or more transmitters and receivers; and comprising one or more processors coupled to said one or more transceivers; One or more of the above processors: Receiving a first physical layer protocol data unit (PPDU) from a first STA via one or more transceivers, the first information including first information for triggering transmission of information related to first low latency traffic (LLT); and A second PPDU including the first information is received from the first STA, and based on the second STA having the first LLT, information related to the first LLT is set to be transmitted to the first STA through the one or more transceivers, The second PPDU transmission is performed based on the first clear channel assessment (CCA) result of the first STA.

14. A processing device configured to control a station (STA) in a wireless local area network (WLAN) system, wherein 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 10.

15. One or more non-transitory computer-readable media storing one or more instructions, A computer-readable medium, wherein said 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 10.

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