Method and apparatus for uplink transmission and reception to which coverage extension is applied in wireless LAN system

Abstract

The present disclosure relates to an improved wireless LAN system. The present disclosure proposes a process for transmitting and receiving an uplink packet to which coverage extension is applied in order to improve the reliability of traffic in an improved wireless LAN system. Specifically, the present disclosure proposes signaling for uplink packet transmission and reception to which coverage extension is applied, and related parameters and format structures.

Description

Uplink transmission and reception method and device applying coverage expansion in a wireless LAN system

[0001] The present disclosure relates to a wireless local area network (WLAN) system. Specifically, the present disclosure relates to a method and device for performing uplink transmission and reception with coverage extension in a WLAN system.

[0002] Wireless LAN (WLAN) systems are evolving for various purposes, such as improving transmission rates, increasing bandwidth, enhancing reliability, reducing errors, and reducing latency. The Institute of Electrical and Electronics Engineers (IEEE) publishes the 802.11 standard specification for WLAN systems, and the technology described in the 802.11 standard specification can be called WiFi (or Wi-Fi, Wireless Fidelity).

[0003] Wi-Fi technology has evolved over several generations of the 802.11 standard. For example, the 802.11ac standard addresses improvements for very high throughput (VHT), the 802.11ax standard addresses improvements for high efficiency (HE), and the 802.11be standard addresses improvements for extreme high throughput (EHT).

[0004] Meanwhile, technologies are being discussed to provide an improved wireless communication environment in wireless LAN systems, and various technologies are being proposed and researched to meet the demand for further enhancing the reliability of wireless LAN systems. These technologies address improvements aimed at achieving ultra-high reliability (UHR).

[0005] The present disclosure proposes a packet transmission and reception method and device for a device that applies coverage extension in a wireless LAN system. In particular, the present disclosure proposes various embodiments for a device to transmit a physical layer protocol data unit (PPDU) with coverage extension or perform uplink OFDMA (orthogonal frequency division multiple access) based random access (UORA) with coverage extension. The present disclosure also proposes a frame or element structure for applying such coverage extension.

[0006] The technical objectives to be achieved in the present disclosure are not limited to those mentioned above, and other technical tasks not mentioned can be considered by a person having ordinary skill in the art to which the present invention pertains from the embodiments of the present invention described below.

[0007] A method performed by a station (STA) according to one embodiment of the present disclosure may include: receiving, from an access point (AP), a trigger frame for uplink OFDMA (orthogonal frequency division multiple access) based random access (UORA) to which an enhanced long range (ELR) physical layer protocol data unit (PPDU)-based coverage extension is applied, wherein the UORA to which the coverage extension is applied is indicated by at least one of a user information field and a common information field of the trigger frame; determining a random access resource unit (RA-RU) based on the trigger frame; and transmitting, to the AP, the ELR PPDU using the RA-RU.

[0008] A method performed by an access point (AP) according to one embodiment of the present disclosure comprises the steps of: transmitting, to a station (STA), a trigger frame for uplink OFDMA (orthogonal frequency division multiple access) based random access (UORA) to which coverage extension based on an enhanced long range (ELR) physical layer protocol data unit (PPDU) is applied, wherein the UORA to which the coverage extension is applied is indicated by at least one of a user information field and a common information field of the trigger frame; and receiving, from the STA, the ELR PPDU using a random access resource unit (RA-RU) based on the trigger frame.

[0009] According to one embodiment of the present disclosure, an STA includes a transceiver; and at least one processor connected to the transceiver, wherein the at least one processor is configured to: receive a trigger frame for uplink OFDMA (orthogonal frequency division multiple access) based random access (UORA) to which coverage extension based on an enhanced long range (ELR) physical layer protocol data unit (PPDU) is applied from an access point (AP), wherein the UORA to which the coverage extension is applied is indicated by at least one of a user information field and a common information field of the trigger frame, determine a random access resource unit (RA-RU) based on the trigger frame, and transmit the ELR PPDU to the AP using the RA-RU.

[0010] According to one embodiment of the present disclosure, an AP includes a transceiver; and at least one processor connected to the transceiver, wherein the at least one processor is configured to transmit a trigger frame for uplink OFDMA (orthogonal frequency division multiple access) based random access (UORA) with coverage extension based on an enhanced long range (ELR) physical layer protocol data unit (PPDU) to a station (STA), wherein the UORA with the coverage extension is indicated by at least one of a user information field and a common information field of the trigger frame, and receive the ELR PPDU from the STA using a random access resource unit (RA-RU) based on the trigger frame.

[0011] According to the various embodiments proposed in this disclosure, the reliability of traffic transmission and reception in a wireless LAN system can be improved. Furthermore, the coverage of devices in the wireless LAN system can be expanded. Furthermore, by simplifying the process for enabling packet transmission and reception with coverage expansion applied in the wireless LAN system, the efficiency of device operation can be improved.

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

[0013] FIG. 2 illustrates an exemplary structure of a wireless LAN system related to the present disclosure.

[0014] Figure 3 illustrates a link setup process related to the present disclosure.

[0015] Figure 4 illustrates a backoff operation related to the present disclosure.

[0016] FIG. 5 illustrates a frame transmission operation based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) in connection with the present disclosure.

[0017] FIG. 6 illustrates an exemplary format of a frame used in a wireless LAN system related to the present disclosure.

[0018] FIG. 7 illustrates an exemplary format of a physical layer protocol data unit (PPDU) of a wireless LAN system related to the present disclosure.

[0019] FIG. 8 illustrates another exemplary format of a PPDU of a wireless LAN system related to the present disclosure.

[0020] FIG. 9 is a diagram explaining UORA (uplink OFDMA (orthogonal frequency division multiple access) based random access) related to the present disclosure.

[0021] FIG. 10 is a drawing explaining UORA related to the present disclosure.

[0022] FIG. 11 is a diagram illustrating an exemplary format of a trigger frame related to the present disclosure.

[0023] FIG. 12 is a diagram illustrating an exemplary format of a UORA parameter set element related to the present disclosure.

[0024] FIG. 13 is a diagram illustrating exemplary values ​​of a trigger type field related to the present disclosure.

[0025] FIG. 14 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0026] FIG. 15 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0027] FIG. 16 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0028] FIG. 17 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0029] FIG. 18 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to one embodiment of the present disclosure.

[0030] FIG. 19 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to one embodiment of the present disclosure.

[0031] FIG. 20 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to one embodiment of the present disclosure.

[0032] FIG. 21 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0033] FIG. 22 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0034] FIG. 23 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to one embodiment of the present disclosure.

[0035] FIG. 24 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to one embodiment of the present disclosure.

[0036] FIG. 25 illustrates a flowchart of the operation of a non-AP STA applying coverage expansion according to an embodiment of the present disclosure.

[0037] FIG. 26 illustrates a flowchart of the operation of an AP applying coverage expansion according to one embodiment of the present disclosure.

[0038] FIG. 27 illustrates a flowchart of the operation of a non-AP STA applying coverage expansion according to an embodiment of the present disclosure.

[0039] FIG. 28 illustrates a flowchart of the operation of an AP applying coverage expansion according to an embodiment of the present disclosure.

[0040] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the attached drawings. It should be noted that, where possible, identical components are represented by identical reference numerals throughout the attached drawings. Furthermore, detailed descriptions of well-known functions and configurations that may obscure the gist of the present disclosure will be omitted.

[0041] In describing the embodiments in this specification, descriptions of technical details that are well known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to avoid obscuring the gist of the present disclosure by omitting unnecessary explanations and to convey the gist more clearly.

[0042] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size.

[0043] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined solely by the scope of the claims.

[0044] At this time, it will be understood that each block of the flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0045] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0046] Here, the term '~ unit' used in the present embodiment means a software or hardware component such as an FPGA or ASIC, and the '~ unit' performs certain roles. However, the '~ unit' is not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Accordingly, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. Additionally, components and '~parts' may be implemented to regenerate one or more CPUs within a device or secure multimedia card.

[0047] 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.

[0048] In this disclosure, terms such as "first," "second," etc. are used only to distinguish one component from another, are not used to limit the components, and do not limit the order or importance of 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.

[0049] 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.

[0050] 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 system 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 system based on the newly discussed IEEE 802.11bn (or UHR (ultra high reliability)) standards. Furthermore, the examples of the present disclosure can be applied to a next-generation wireless LAN system based on a new standards document that improves upon the IEEE 802.11bn.

[0051] Additionally, examples of the present disclosure may be applied to cellular wireless communication systems. For example, examples of the present disclosure may be applied to cellular wireless communication systems based on Long Term Evolution (LTE), LTE-Advanced (LTE-A), and New Radio (NR) technologies based on 3rd Generation Partnership Project (3GPP) standard documents.

[0052] FIG. 1 illustrates a configuration of a device for wireless communication according to one embodiment of the present disclosure.

[0053] The first device (100) and the second device (200) of FIG. 1 may be replaced with various terms such as terminal, wireless device, WTRU (Wireless Transmit and Receive Unit), UE (User Equipment), MS (Mobile Station), UT (user terminal), MSS (Mobile Subscriber Station), MSS (Mobile Subscriber Unit), SS (Subscriber Station), AMS (Advanced Mobile Station), WT (Wireless terminal), client terminal, or simply user.

[0054] In addition, the first device (100) and the second device (200) may be replaced with various terms such as access point (AP), base station (BS), fixed station, Node B, base transceiver system (BTS), network, artificial intelligence (AI) system, road side unit (RSU), repeater, router, relay, gateway, etc.

[0055] 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.

[0056] Referring to FIG. 1, the first device (100) and the second device (200) can transmit and / or receive wireless signals through various wireless LAN technologies (e.g., technologies based on the IEEE 802.11 standard document). The first device (100) and the second device (200) can include interfaces for a medium access control (MAC) layer and a physical (PHY) layer that follow the regulations of the IEEE 802.11 standard document.

[0057] In addition, the first device (100) and the second device (200) may additionally support various wireless communication technologies other than wireless LAN technology (for example, technologies based on 3GPP LTE, LTE-A, or NR standard documents). In addition, the devices of the present disclosure may be implemented as various devices such as mobile phones, vehicles, personal computers, AR (Augmented Reality) equipment, VR (Virtual Reality) equipment, 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).

[0058] A first device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (or 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 and / or a first signal, and then transmit a wireless signal including the first information and / or the first signal via the transceivers (106). In addition, the processor (102) may receive a wireless signal including second information and / or a second signal through the transceiver (106), and then store information obtained through signal processing of the second information and / or the second signal 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., a technology based on the IEEE 802.11 document). A 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.

[0059] The second device (200) includes one or more processors (202) and one or more memories (204), and may further include one or more transceivers (or transceiver units) (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 memories (204) to generate third information and / or a third signal, and then transmit a wireless signal including the third information and / or the third signal via the transceivers (206). In addition, the processor (202) may receive a wireless signal including the fourth information and / or the fourth signal through the transceiver (206), and then store information obtained through signal processing of the fourth information and / or the fourth signal 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 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., a technology based on the IEEE 802.11 document). A 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.

[0060] Hereinafter, hardware elements of the device (100, 200) will be described in more detail. Although not limited to the following, operations of 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 operations of 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 operation 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 operation 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, traffic or information according to the functions, procedures, proposals and / or methods disclosed in this 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, traffic or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed in this disclosure.

[0061] 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 read only memory (ROM), random access memory (RAM), erasable programmable ROM (EPROM), electronically EPROM (EEPROM), 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.

[0062] One or more transceivers (106, 206) can transmit user data, control information, data, traffic, wireless signals, and / or channels, etc., as described 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, data, traffic, wireless signals, and / or channels, etc., as described 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, traffic, wireless signals, and / or channels, etc., 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, traffic, wireless signals, and / or channels 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, traffic, wireless signals, and / or channels, etc., as described 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 (108, 208) may be multiple physical antennas or multiple logical antennas (e.g., antenna ports).One or more transceivers (106, 206) may 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 processed user data, control information, wireless signals / channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or a filter.

[0063] In one example, one of the devices (100, 200) may perform the intended operation of an AP, and the other of the devices (100, 200) may perform the intended operation of a non-AP STA. In another example, the transceiver (106, 206) of FIG. 1 may perform transmission and / or 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.).

[0064] Additionally, in the present disclosure, the operations of various STAs generating transmission / reception signals or performing data processing or calculations in advance for transmission / reception signals can be performed in the processor (102, 202) of FIG. 1. For example, an example of an operation of generating a transmission / reception signal or performing data processing or operation in advance for a transmission / reception signal is an operation of determining / obtaining / configuring / computing / decoding / encoding bit information of a field included in a PPDU (e.g., SIG (signal), STF (short training field), LTF (long training field), Data, etc.), 2) determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) used for a field included in a PPDU (e.g., SIG, STF, LTF, Data, etc.), 3) determining / configuring / obtaining a specific sequence (e.g., pilot sequence, STF / LTF sequence, extra sequence applied to SIG) used for a field included in a PPDU (e.g., SIG, STF, LTF, Data, etc.), 4) power control operation and / or power saving operation applied to an STA, 5) ACK (acknowledgement) signal It may include operations related to decision / acquisition / configuration / computation / decoding / encoding, etc. In addition, in the example below, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs for decision / acquisition / configuration / computation / decoding / encoding of transmission / reception signals may be stored in the memory (104, 204) of FIG. 1.

[0065] 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.

[0066] An exemplary structure of a wireless LAN system related to the present disclosure is illustrated.

[0067] A wireless LAN system may have a structure composed of multiple components. The wireless LAN system can support transparent STA mobility to the upper layer through the interaction of the multiple components. 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 (BSS 1 and BSS 2), and the inclusion of two STAs as members of each BSS (STA 1 and STA 2 are included in BSS 1, and STA 3 and STA 4 are included in BSS 2). 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 the BSA, it cannot directly communicate with other STAs within the BSA.

[0068] If we do not consider the distributed system (DS) illustrated in Fig. 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, BSS 1 consisting of only STA 1 and STA 2, or BSS 2 consisting of only STA 3 and STA 4, can be representative examples of an IBSS, respectively. Such a configuration is possible when the STAs can communicate directly without an AP. Furthermore, this type of WLAN is not planned in advance but can be configured when a local area network (LAN) is required, and can also be called an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity. That is, in an IBSS, STAs are managed in a distributed manner. In IBSS, all STAs can be mobile STAs, and access to the DS is not permitted, forming a self-contained network.

[0069] 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).

[0070] In a wireless LAN, the direct STA-to-STA distance may 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 DS can be configured.

[0071] 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 the distributed system medium (DSM, DS medium). 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.

[0072] 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).

[0073] An AP enables non-AP STAs associated with it to access the DS through the WM. An AP may refer to an entity that also has the functionality of an STA, and data movement between the BSS and the DS may be performed through the AP. For example, STA 2 and STA 3 illustrated in FIG. 2 have the functionality of an STA and provide the function of allowing associated non-AP STAs (STA 1 and STA 4) 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 the WM and the address used by an AP for communication on the DSM do not necessarily have to be the same. A BSS consisting of an AP and one or more STAs may be referred to as an infrastructure BSS.

[0074] Data transmitted from one of the STA(s) associated with an AP to the STA address of that AP is always received on an uncontrolled port and can be processed by an IEEE 802.1X port access entity. In addition, if the controlled port is authenticated, the transmitted data (or frame) can be forwarded to the DS.

[0075] In addition to the structure of the DS described above, an extended service set (ESS) may be established to provide wider coverage.

[0076] An ESS is a network of arbitrary size and complexity, and 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 LLC (Logical Link Control) layer. STAs included in an ESS can communicate with each other, and mobile STAs can move from one BSS to another (i.e., within the same ESS) transparently to the LLC. APs included in an ESS may have the same SSID (service set identifier). The SSID is distinct from the BSS ID (BSS SSID), which is the identifier of the BSS.

[0077] 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 restriction 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 in the same space as one (or more) ESS networks. This can occur in cases where an ad-hoc network operates in 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.

[0078] Figure 3 illustrates a link setup process related to the present disclosure.

[0079] For an STA to set up a link and transmit and receive data on a network, it must discover the network via an AP, perform authentication, establish an association, and establish security. 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.

[0080] At step 310, 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.

[0081] Scanning methods include active scanning and passive scanning. Figure 3 illustrates a network discovery operation that includes 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.

[0082] 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 to enable the STA performing the scanning to 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.

[0083] After the STA discovers the network, an authentication process may be performed at step 320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation of step 340 described below.

[0084] 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 request frame and the authorization response frame used in the authentication process belong to management frames.

[0085] 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.

[0086] An STA can transmit 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.

[0087] After the STA is successfully authenticated, an association process may be performed at step 330. 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.

[0088] The association request frame may include information about various capabilities, a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, a robust security network (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 the combined request / response frame may further include additional information.

[0089] After the STA successfully joins the network via the AP, a security setup process may be performed at step 340. The security setup process of step 340 may include an authentication process via a Robust Security Network Association (RSNA) request / response. Furthermore, if the authentication process of step 320 is referred to as the first authentication process, the security setup process of step 340 may also be referred to simply as the authentication process.

[0090] The security setup process of step 340 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.

[0091] Figure 4 illustrates a backoff operation related to the present disclosure.

[0092] In wireless LAN systems, the basic MAC access mechanism is Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). CSMA / CA, 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 performs Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time period (e.g., DIFS (DCF Inter-Frame Space)) before starting transmission. If the sensing result determines that the medium is in an idle state, the AP and / or STA starts 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 predetermined delay period (e.g., a random backoff period) for medium access before attempting to transmit frames. By applying the random backoff period, multiple STAs may attempt to transmit frames after waiting for different periods of time, thereby minimizing collisions.

[0093] Additionally, the IEEE 802.11 MAC protocol provides a Hybrid Coordination Function (HCF). HCF is based on the DCF and Point Coordination Function (PCF). PCF is a polling-based synchronous access method, which refers to a method in which all receiving APs and / or STAs periodically poll to ensure that they can receive data frames. HCF also includes Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA). EDCA is a contention-based access method in which a provider provides data frames to multiple users, while HCCA is a contention-free channel access method that utilizes a polling mechanism. In addition, HCF includes a medium access mechanism to improve the Quality of Service (QoS) of a wireless LAN, and can transmit QoS data in both a Contention Period (CP) and a Contention Free Period (CFP).

[0094] Referring to Fig. 4, an operation based on a random backoff period is described. When an occupied / busy medium changes to an idle state, multiple STAs may attempt to transmit data (or frames). To minimize collisions, each STA may 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 may 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 initially given a value of CWmin, but in case of a transmission failure (e.g., if an ACK for a transmitted frame is not received), the STA may increase the CW by a factor of two. When the CW parameter value reaches CWmax, the STA may attempt data transmission while maintaining the CWmax value until the data transmission is successful, and if the data transmission is successful, the CW is reset to the CWmin value. The values ​​of CW, CWmin and CWmax can be set to 2n-1 (n=0, 1, 2, ...).

[0095] 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.

[0096] In the example of FIG. 4, when a packet to be transmitted reaches the MAC of STA3, STA3 can immediately transmit the 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 the random backoff count value selected by each STA after waiting for DIFS if it confirms that the medium is 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 was stopped. That is, STA1 and STA5 can start frame transmission 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 frame transmission. While STA2 occupies the medium, STA4 may also have data to transmit. When the medium becomes idle, STA4 waits for DIFS, counts down according to a random backoff count value selected by it, and then starts frame transmission. In the example of FIG. 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.

[0097] As shown in the example of Fig. 4, a data frame is a frame used for transmitting data to an upper 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 without being transmitted to an upper layer, and is transmitted after a backoff performed after an IFS such as DIFS or PIFS (Point coordination function IFS) elapses. A management frame may include a beacon, an association request / response, a re-association request / response, a probe request / response, an authentication request / response, etc. as a subtype frame. A control frame is a frame used to control access to the medium. Control frames can include RTS (Request-To-Send), CTS (Clear-To-Send), ACK (Acknowledgment), PS-Poll (Power Save-Poll), Block ACK (B-ACK or BlockAck), Block ACK Request (BlockACKReq), NDP announcement (null data packet announcement), Trigger, etc. as subtype frames. 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) has elapsed. The type and subtype of a frame can be identified by the type field and subtype field in the frame control (FC) field.

[0098] 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.

[0099] FIG. 5 illustrates a frame transmission operation based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) in connection with the present disclosure.

[0100] 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 that receives 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.

[0101] In the example of FIG. 5, STA1 wants to transmit data to STA2, and STA3 is in a position to overhear part or all of the frames transmitted and received between STA1 and STA2.

[0102] 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. 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. 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.

[0103] 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 the NAV timer.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] FIG. 6 illustrates an exemplary format of a frame used in a wireless LAN system related to the present disclosure.

[0108] Based on an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer, the PHY layer can prepare an MPDU (MAC PDU) to be transmitted. When the PHY layer receives a command requesting the start of transmission 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 can monitor the header of the preamble and send a command to the MAC layer notifying the start of reception by the PHY layer.

[0109] 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) frame format is defined.

[0110] A basic PPDU frame may include a short training field (STF), a long training field (LTF), a SIGNAL (SIG) field, and a data field. The most basic (e.g., non-HT (high throughput)) PPDU frame format may consist of only L-STF (Legacy-STF), L-LTF (Legacy-LTF), a SIG field, and a data field. In addition, depending on the type of PPDU frame format (e.g., HT-mixed format PPDU, HT-greenfield format PPDU, VHT (very high throughput) PPDU, etc.), additional (or different types of) STF, LTF, and SIG fields may be included between the SIG field and the data field. Specific types of frame formats are described later in FIG. 7.

[0111] STF is a signal for signal detection, AGC (automatic gain control), diversity selection, precise time synchronization, etc., and LTF is a signal for channel estimation, frequency error estimation, etc. STF and LTF are signals for synchronization and channel estimation of the OFDM (orthogonal frequency division multiplexing) physical layer.

[0112] The SIG field may include a RATE field and a LENGTH field, among others. The RATE field may include information about the modulation and coding rate of the data. The LENGTH field may include information about the length of the data. Additionally, the SIG field may include a parity bit, a SIG TAIL bit, among others.

[0113] 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.

[0114] 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 frame format.

[0115] The MAC header includes a frame control field, a duration / ID field, an address field, etc. The frame control field may include control information necessary for frame transmission / reception. The duration / ID field may be set to the time for transmitting the corresponding frame, etc. The specific contents of the Sequence Control, QoS Control, and HT Control subfields of the MAC header are omitted.

[0116] Although not shown in FIG. 6, the null data packet (NDP) frame format refers to a frame format that does not include a data packet. That is, the NDP frame refers to a frame format that includes the PLCP (physical layer convergence procedure) header portion (i.e., STF, LTF, and SIG fields) of the general PPDU frame format, but does not include the remaining portion (i.e., data field). The NDP frame may also be referred to as a short frame format.

[0117] FIG. 7 illustrates an exemplary format of a physical layer protocol data unit (PPDU) of a wireless LAN system related to the present disclosure.

[0118] Standards such as IEEE 802.11a / g / n / ac / ax / be use various PPDU formats. The basic PPDU format (IEEE 802.11a / g format) 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.

[0119] The HT PPDU format (IEEE 802.11n format) 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 may be referred to as an HT-mixed format. Although not illustrated, an HT-greenfield format PPDU may be defined, which corresponds to a format that does not include L-STF, L-LTF, and L-SIG, and is composed of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTF, and Data fields.

[0120] The VHT PPDU format (IEEE 802.11ac format) includes VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format.

[0121] The HE PPDU format (IEEE 802.11ax format) 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. 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 8 μs. The HE ER (Extended Range) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field can vary up to 16 μs.

[0122] FIG. 8 illustrates another exemplary format of a PPDU of a wireless LAN system related to the present disclosure.

[0123] The EHT PPDU format (IEEE 802.11be format) of FIG. 8 may include an EHT MU PPDU format and an EHT TB PPDU format. The EHT MU PPDU format corresponds to a PPDU that carries one or more data (or PSDU) for one or more users. The EHT MU PPDU can be used for both SU transmission and MU transmission, and the EHT MU PPDU may correspond to a PPDU for one receiving STA or multiple receiving STAs. The EHT TB PPDU omits the EHT-SIG compared to the EHT MU PPDU. An STA that receives a trigger for UL MU transmission (e.g., a trigger frame or an RTS frame) can perform UL transmission based on the EHT TB PPDU format.

[0124] The EHT PPDU format includes RL-SIG, U-SIG (Universal SIG), EHT-SIG, EHT-STF, EHT-LTF(s), and PE fields in addition to the basic PPDU format. Depending on the specific examples of the EHT PPDU format, some fields may be excluded or their lengths may vary. For example, depending on the EHT MU PPDU format and EHT TB PPDU format described above, some fields of the EHT PPDU format may or may not be included, or the lengths of specific fields may vary.

[0125] FIG. 9 is a diagram explaining UORA (uplink OFDMA (orthogonal frequency division multiple access) based random access) related to the present disclosure.

[0126] The 802.11ax standard introduced UORA, a mechanism for randomly selecting RA-RUs (random access resource units) allocated by APs via trigger frames. In other words, channel access using the existing CSMA / CA method suffers from reduced throughput due to collisions and interference as the number of STAs increases. To improve this, UORA was introduced, which divides the entire bandwidth into multiple channels and assigns each channel to an STA.

[0127] An embodiment illustrated in FIG. 9 is described. Before the AP transmits trigger frame 1, the initial OBO (OFDMA backoff) values ​​of STA1, STA2, STA3, and STA4 may be 3, 5, 4, and 2, respectively (FIG. 9 (b)). Upon receiving trigger frame 1, RU6, which is a dedicated RU, is allocated to STA4, which is an associated STA with the AP and has a pending frame for the AP. STA4 does not contend for the RA-RU, and instead can transmit the pending frame on RU6 (FIG. 9 (a)). Upon receiving trigger frame 1, STA1 and STA2, which are STAs associated with the AP and have pending frames for the AP, decrement their respective OBO counters by the number of eligible RA-RUs indicated in the trigger frame (i.e., 3 RA-RUs for the associated STAs in the example illustrated in FIG. 9(a)). Since STA1's OBO counter decrements to 0, STA1 transmits the pending frame to the AP on RU2 randomly selected from the set of eligible RUs (RU1, RU2, and RU3) (FIGS. 9(a) and (b)). Since STA2's OBO counter decrements to a non-zero value, STA2 maintains the new OBO value (i.e., 2) until it receives a later trigger frame for forwarding RA-RUs for the associated STAs (FIGS. 9(a) and (b)). STA3, which is not associated with the AP but has a pending frame for the AP, decrements the OBO counter by the number of eligible RA-RUs indicated in the trigger frame (i.e., 2 RA-RUs for the non-associated (or, unassociated) STAs in the example shown in Fig. 9(a)).Since the OBO counter of STA3 is decremented to a non-zero value, STA3 maintains the new OBO value (i.e., 2) until it receives a subsequent trigger frame for transmitting RA-RU to non-associated STAs ((a) and (b) of FIG. 9).

[0128] FIG. 10 is a diagram illustrating UORA related to the present disclosure. FIG. 10 describes the situation after transmission of a PPDU in response to trigger frame 1 in FIG. 9.

[0129] Since STA4 has an additional pending frame for the AP, it maintains the initial OBO value (i.e., 2) in Figure 9 until it receives a subsequent trigger frame to forward RA-RUs to the associated STAs. STA1 has an additional pending frame for the AP and randomly selects a new OBO value (i.e., 4).

[0130] Upon receiving the trigger frame 2 illustrated in FIG. 10 (which carries RA-RUs for associated STAs and RA-RUs for unassociated STAs), STA1, STA2, and STA4 decrement their respective OBO counters by the number of eligible RA-RUs (two RA-RUs for associated STAs in the example illustrated in (a) of FIG. 10). Since the OBO counters of STA2 and STA4 are each decremented to 0, STA2 and STA4 transmit pending frames to the AP on randomly selected RUs (RU2 for STA2 and RU1 for STA4 in the example illustrated in (a) of FIG. 10) from the set of eligible RUs. If either STA has an additional pending frame for the AP, each STA randomly selects a new OBO value. Upon receiving trigger frame 2, STA1's OBO is decremented to a non-zero value, so STA1 maintains the new OBO value (i.e., 2) until it receives a subsequent trigger frame for forwarding RA-RUs to the associated STA ((a) and (b) of FIG. 10). Upon receiving trigger frame 2, STA3, which is not associated, decrements its OBO counter by the number of eligible RA-RUs (two of RU3 and RU4 in the example of FIG. 10). Since STA3's OBO counter is decremented to 0, STA3 transmits a pending frame to the AP on a randomly selected RU (RU4 in the example of FIG. 10) from the eligible RU set (RU3, RU4).

[0131] FIG. 11 is a diagram illustrating an exemplary format of a trigger frame related to the present disclosure.

[0132] For the UORA procedure described in FIGS. 9 and 10, the AP transmits a trigger frame to allocate a channel for random access within a transmission opportunity (TXOP). Non-AP STAs that receive the trigger frame can participate in uplink contention to transmit uplink data on the RA-RU allocated by the trigger frame.

[0133] A trigger frame transmitted by an AP to a non-AP STA may have an exemplary format as illustrated in (a) of FIG. 11. A trigger frame for UORA may include any one of a basic trigger frame including one or more RUs (i.e., RA-RUs) for random access, a bandwidth query report poll (BQRP) trigger frame, or a buffer status report poll (BSRP) trigger frame, and various other types of trigger frames may be used as trigger frames for UORA. Eligible RA-RUs indicated by an RU allocation subfield (FIG. 11 (c)) of a user information field (FIG. 11 (b)) included in the trigger frame may indicate a starting RU of an RU set.

[0134] Hereinafter, various fields and / or subfields included in the trigger frame of Fig. 11 will be described. It is to be understood that general contents of the technical field may be applied even if specific descriptions of specific fields or subfields are omitted below. The trigger frame may include a frame control field, a duration field, a receiver address (RA) field, a transmitter address (TA) field, a common information field, a user information list field, a padding field, and a frame check sequence (FCS) field.

[0135] The common information field indicates information commonly required for at least one STA to transmit a response to a trigger frame. The user information list field indicates information individually required for at least one STA to transmit a response to a trigger frame. The user information list field may include multiple user information fields.

[0136] If the value of the AID (association identifier) ​​12 subfield included in the user information field is 0, it may indicate that the user information field allocates one or more contiguous RA-RUs for the associated STAs, and if the value of the AID12 subfield is 2045, it may indicate that the user information field allocates one or more contiguous RA-RUs for the non-associated (or, non-associated) STAs.

[0137] The RA-RU information subfield (or, spatial stream allocation / RA-RU information subfield) of the user information field may include a number of RA-RU subfield and a more RA-RU subfield. The number of RA-RU subfield may indicate the number of consecutive RUs allocated for UORA, and the value of the more RA-RU subfield may be equal to the number of consecutive RA-RAs minus 1. When the value of the more RA-RU subfield is 1, it indicates that RA-RUs of the type indicated in the AID12 subfield are allocated to subsequent trigger frames transmitted until the end of the target wakeup time (TWT) service period (SP) in which the corresponding trigger frame is transmitted; otherwise, the value of the more RA-RU subfield is 0.

[0138] FIG. 12 is a diagram illustrating an exemplary format of a UORA parameter set element related to the present disclosure.

[0139] The process of using the OBO value for UORA operation has been described in detail in FIGS. 9 and 10 above. Meanwhile, the OBO value (or OBO counter value) may be any integer value within the OCW (OFDMA contention window) range, which is defined as the OCW minimum value (OCWmin) to the OCW maximum value (OCWmax). Based on the OBO value selected within the OCW range, the STA may perform the RA-RU decision process for UORA described above.

[0140] The UORA parameter set element illustrated in FIG. 12 may include a plurality of fields related to parameters for UORA operation, and the UORA parameter set element may be transmitted or announced by being included in a management frame (e.g., a beacon frame, a probe response frame, or a (re)association response frame). The UORA parameter set element may include an element ID field, a length field, an element ID extension field, and an OCW range field, and the OCW range field may include an EOCWmin subfield, an EOCWmax subfield, and reserved subfields. The OCW minimum value (OCWmin) may be set to 2^(the value indicated by the EOCWmin subfield)-1, and the OCW maximum value (OCWmax) may be set to 2^(the value indicated by the EOCWmax subfield)-1.

[0141] FIG. 13 is a diagram illustrating exemplary values ​​of the trigger type field related to the present disclosure. The trigger type subfield illustrated in FIG. 13 may be included in the common information field included in the trigger frame of FIG. 11. As illustrated in FIG. 13, each value of the trigger type subfield may indicate the type of the corresponding trigger frame.

[0142] Meanwhile, with the recent multifaceted development of WLAN, research and discussions are being conducted, particularly for coverage extension. For example, research is being conducted on a coverage extension or range extension mechanism that includes an enhanced long range (ELR) PPDU. For another example, research is also being conducted on a coverage extension or range extension mechanism that includes distributed tone RU (DRU) transmission. Since both ELR PPDU and DRU transmission are discussed for the common purpose of coverage extension, the term "coverage extension" hereinafter may be understood to include at least one of ELR PPDU transmission and DRU transmission. In addition, transmission with coverage extension applied may refer to either ELR PPDU transmission or DRU transmission. In addition, the coverage extension mode may refer to a mode for ELR PPDU transmission or a DRU transmission mode, and may be understood as a mode different from a normal mode or a regular RU (RRU) transmission mode.

[0143] Hereinafter, various embodiments for the aforementioned coverage extension will be described. For example, if a non-AP STA can receive a downlink trigger frame but fails to transmit an uplink PPDU (or UORA) due to a difference in transmission power between the AP and the non-AP STA, the embodiments for coverage extension proposed in the present disclosure can be an efficient improvement method. In addition, since always applying the coverage extension mode may be disadvantageous in terms of wireless resource utilization, procedures for efficiently coordinating the timing or conditions for applying coverage extension between the non-AP STA and the AP are also proposed. For example, the present disclosure also proposes an efficient coverage extension mode application process that takes into account conditions related to the association of non-AP STAs, the strength of the wireless signal, or whether the STA is at the center / edge of the BSS.

[0144] FIG. 14 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0145] In the embodiment illustrated in FIG. 14, the AP transmits a trigger frame (1410). The AP may allocate RU1 for PPDU transmission of STA1 and RU2 for PPDU transmission of STA3 through the trigger frame. For example, the AP may determine that coverage extension needs to be applied to uplink packet transmission of STA1 and STA3, and may allocate RUs for STA1 and STA3 accordingly through the trigger frame. The trigger frame transmitted by the AP may indicate that the allocated RUs are for uplink transmission with coverage extension applied, and for example, the trigger frame may allocate RUs for at least one of ELR PPDU transmission and / or DRU transmission. In the embodiment of FIG. 14, the AP may allocate RU1 and RU2 to STA1 and STA3, respectively, for at least one of ELR PPDU transmission and / or DRU transmission through the trigger frame.

[0146] According to one embodiment, the AP may transmit a trigger frame including information for instructing at least one non-AP STA to transmit ELR PPDU and / or DRU (or information for allocating an RU for ELR PPDU transmission and / or DRU transmission, or information indicating that the allocated RU is for ELR PPDU transmission and / or DRU transmission). For example, the AP may indicate ELR PPDU transmission and / or DRU transmission through any one of the reserved values ​​for the AID subfield of the user information field included in the trigger frame (e.g., 2041, etc.). Alternatively, the AP may indicate ELR PPDU transmission and / or DRU transmission through any one of the reserved values ​​for the UL HE-MCS subfield of the user information field included in the trigger frame (e.g., 15, etc.). Alternatively, the AP may allocate one or more additional bits to the common information field included in the trigger frame, or may utilize one or more of the reserved bits included in the common information field to indicate ELR PPDU transmission and / or DRU transmission. It goes without saying that the process of the AP indicating ELR PPDU transmission and / or DRU transmission may be performed through various fields, subfields, or bits included in the trigger frame in addition to the examples described above.

[0147] STA1, which has received a trigger frame, transmits an ELR PPDU to the AP using RU1 allocated to it (1420), and STA3, which has received a trigger frame, can transmit an ELR PPDU to the AP using RU2 allocated to it (1430). That is, at least one STA that has received a trigger frame from the AP can check information related to ELR PPDU transmission and / or DRU transmission included in the trigger frame, and each STA can transmit an uplink PPDU to the AP according to the coverage extension mode on the RU allocated to it (or, perform ELR PPDU transmission and / or DRU transmission).

[0148] FIG. 15 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0149] In the embodiment illustrated in FIG. 15, the AP transmits a trigger frame (1510). The AP may allocate RU1 for PPDU transmission of STA2 and RU2 for PPDU transmission of STA3 through the trigger frame. For example, the AP may determine that coverage extension does not need to be applied to uplink packet transmission of STA2 and STA3, and may allocate RUs for STA2 and STA3 accordingly through the trigger frame. The trigger frame transmitted by the AP may indicate that the allocated RUs are for uplink transmission without coverage extension applied, for example, the trigger frame may allocate RUs for normal PPDU transmission, that is, without ELR PPDU transmission or DRU transmission applied. In the embodiment of FIG. 15, the AP may allocate RU1 and RU2 to STA2 and STA3, respectively, for normal PPDU transmission that is not during ELR PPDU transmission or DRU transmission through the trigger frame.

[0150] According to one embodiment, the AP may not include in the trigger frame information for indicating ELR PPDU transmission and / or DRU transmission (or information for allocating an RU for ELR PPDU transmission and / or DRU transmission, or information indicating that the allocated RU is for ELR PPDU transmission and / or DRU transmission) for normal PPDU transmission of at least one non-AP STA. Alternatively, the AP may indicate normal PPDU transmission (transmission other than ELR PPDU transmission or DRU transmission) through any one of the reserved values ​​for the AID subfield of the user information field included in the trigger frame (e.g., a value other than 2041) different from the embodiment of FIG. 14. Alternatively, the AP may indicate normal PPDU transmission (non-ELR PPDU transmission and / or non-DRU transmission) through any one of the reserved values ​​for the UL HE-MCS subfield of the user information field included in the trigger frame other than the embodiment of FIG. 14 (for example, a value other than 15). Alternatively, the AP may indicate normal PPDU transmission (non-ELR PPDU transmission and / or non-DRU transmission) by allocating one or more additional bits to the common information field included in the trigger frame, or by utilizing one or more of the reserved bits included in the common information field. It goes without saying that the process by which the AP indicates normal PPDU transmission (non-ELR PPDU transmission and / or non-DRU transmission) may be performed through various fields, subfields, or bits included in the trigger frame in addition to the examples described above.

[0151] STA2, which has received a trigger frame, transmits a normal PPDU to the AP using RU1 allocated to it (1520), and STA3, which has received a trigger frame, can transmit a normal PPDU to the AP using RU2 allocated to it (1530). That is, at least one STA that has received a trigger frame from the AP can check information related to normal PPDU transmission included in the trigger frame (i.e., transmission other than ELR PPDU transmission or DRU transmission), and each STA can transmit an uplink PPDU to the AP without applying the coverage extension mode (or according to the normal mode) on the RU allocated to it.

[0152] FIG. 16 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0153] In the embodiment illustrated in FIG. 16, the AP transmits a trigger frame for UORA (1610). According to one embodiment, the trigger frame transmitted by the AP may include information for allocating one or more RA-RUs for the UORA with coverage extension applied. For example, the trigger frame according to the embodiment of FIG. 16 may indicate that the RA-RU allocated for the UORA is for transmission with coverage extension applied (e.g., ELR PPDU transmission and / or DRU transmission).

[0154] According to one embodiment, the AP may transmit a trigger frame including information for indicating ELR PPDU transmission and / or DRU transmission (or information for allocating RA-RU for ELR PPDU transmission and / or DRU transmission, or information indicating that the allocated RA-RU is for ELR PPDU transmission and / or DRU transmission) to indicate a UORA with coverage extension applied. For example, the AP may indicate a UORA with coverage extension applied through one of the reserved values ​​for the AID subfield of the user information field included in the trigger frame (e.g., 2041, etc.). Alternatively, the AP may indicate a UORA with coverage extension applied through one of the reserved values ​​for the UL HE-MCS subfield of the user information field included in the trigger frame (e.g., 15, etc.). Alternatively, the AP may indicate a UORA with coverage extension by allocating one or more additional bits to the common information field included in the trigger frame, or by utilizing one or more of the reserved bits included in the common information field. It should be noted that the process by which the AP indicates a UORA with coverage extension may be performed through various fields, subfields, or bits included in the trigger frame, in addition to the examples described above.

[0155] STA1, which has received a trigger frame, can transmit an ELR PPDU to the AP through RU1 selected from among the RA-RUs allocated for the UORA to which coverage extension is applied (1620). That is, STA1, which has received a trigger frame from the AP, can confirm that an RA-RU has been allocated for the UORA to which coverage extension is applied included in the trigger frame, and can select the RA-RU by decreasing the OBO value according to the UORA procedure described above. STA1 can transmit an uplink PPDU to the AP according to the coverage extension mode on the selected RA-RU (or, perform ELR PPDU transmission and / or DRU transmission).

[0156] FIG. 17 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0157] In the embodiment illustrated in FIG. 17, the AP transmits a trigger frame (1710). The AP can indicate or set one or more conditions for transmission with coverage extension applied through the trigger frame. For example, the AP can transmit the trigger frame by including conditions for an STA to perform transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission), and the STA that receives the trigger frame can perform transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) based on the identified conditions. In addition, the AP can also allocate an RU to be used when performing transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) when the above-described conditions are satisfied, through the trigger frame.

[0158] In the illustrated embodiment, the AP may instruct STA1 on conditions for transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) by allocating RU1 to STA1 through a trigger frame. Furthermore, the AP may instruct STA3 on conditions for transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) by allocating RU2 to STA3 through a trigger frame. The conditions for transmission by the AP through the trigger frame may be the same or different for each of at least one STAs to which an RU is allocated.

[0159] According to one embodiment, the condition for transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) transmitted through the trigger frame may include a condition related to the physical layer (PHY layer). For example, the condition for transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) may include at least one of a received signal strength indication (RSSI) of the trigger frame, a path loss based on the transmission power of the AP, or a UL target receive power. For this condition, the trigger frame may include at least one of a threshold value of the RSSI of the trigger frame, a threshold value for the path loss, the transmission power of the AP, a threshold value for the UL target receive power, the UL target RSSI, or a signal to noise ratio (SNR).

[0160] According to one embodiment, information on conditions for transmission (ELR PPDU transmission and / or DRU transmission) to which the above-described coverage extension is applied may be included in a trigger dependent user information subfield of a user information field included in a trigger frame. Alternatively, information on conditions for transmission (ELR PPDU transmission and / or DRU transmission) to which the above-described coverage extension is applied may be included in a trigger dependent common information subfield of a common information field included in the trigger frame. It goes without saying that information on conditions for transmission (ELR PPDU transmission and / or DRU transmission) to which the coverage extension is applied may be included in various fields or subfields included in the trigger frame in addition to the above-described fields / subfields.

[0161] STA1, which has received a trigger frame, determines whether the condition confirmed through the trigger frame is satisfied, and if the condition is satisfied, performs transmission (ELR PPDU transmission and / or DRU transmission) with coverage extension applied through RU1 assigned to it (i.e., STA1 transmits ELR PPDU to AP through RU1) (1720). STA3, which has received a trigger frame, determines whether the condition confirmed through the trigger frame is satisfied, and if the condition is satisfied, performs transmission (ELR PPDU transmission and / or DRU transmission) with coverage extension applied through RU2 assigned to it (i.e., STA3 transmits ELR PPDU or DRU PPDU to AP through RU2) (1730).

[0162] Unlike the illustrated embodiment, if the condition included in the trigger frame is not satisfied, STA1 or STA3 may not perform transmission with coverage extension applied. Not performing transmission with coverage extension applied may mean that STA1 or STA3 performs normal transmission without applying coverage extension. Alternatively, not performing transmission with coverage extension applied may mean that STA1 or STA3 does not transmit PPDU.

[0163] FIG. 18 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to one embodiment of the present disclosure.

[0164] In the embodiment illustrated in FIG. 18, the AP transmits a trigger frame (1810). The AP can indicate or set one or more conditions for transmission (or, normal transmission) to which coverage extension is not applied through the trigger frame. For example, the AP can transmit the trigger frame including conditions for an STA to perform transmission (normal transmission) to which coverage extension is not applied, and the STA that receives the trigger frame can perform transmission (normal transmission) to which coverage extension is not applied based on the identified conditions. In addition, the AP can also allocate an RU to be used when performing transmission (normal transmission) to which coverage extension is not applied when the above-described conditions are satisfied through the trigger frame.

[0165] In the illustrated embodiment, the AP may instruct STA2 on the conditions for transmission (normal transmission) to which coverage extension is not applied while allocating RU1 to STA2 via a trigger frame. Furthermore, the AP may instruct STA3 on the conditions for transmission (normal transmission) to which coverage extension is not applied while allocating RU2 to STA3 via a trigger frame. The conditions for transmission by the AP via the trigger frame may be the same or different for each of at least one STAs to which an RU is allocated.

[0166] According to one embodiment, the condition for transmission (normal transmission) to which coverage extension is not applied transmitted through a trigger frame may include a condition related to the physical layer (PHY layer). For example, the condition for transmission (normal transmission) to which coverage extension is not applied may include at least one of a received signal strength indication (RSSI) of the trigger frame, a path loss based on the transmission power of the AP, or a UL target receive power. For this condition, the trigger frame may include at least one of a threshold value of the RSSI of the trigger frame, a threshold value for the path loss, the transmission power of the AP, a threshold value for the UL target receive power, the UL target RSSI, or a signal to noise ratio (SNR).

[0167] According to one embodiment, information on conditions for transmission to which the above-described coverage extension is not applied (normal transmission) may be included in a trigger dependent user information subfield of a user information field included in a trigger frame. Alternatively, information on conditions for transmission to which the coverage extension is not applied (normal transmission) may be included in a trigger dependent common information subfield of a common information field included in the trigger frame. Of course, information on conditions for transmission to which the coverage extension is not applied (normal transmission) may be included in various fields or subfields included in the trigger frame in addition to the above-described fields / subfields.

[0168] STA2, which has received the trigger frame, determines whether the condition confirmed through the trigger frame is satisfied, and if the condition is satisfied, performs transmission (normal transmission) to which coverage extension is not applied through RU1 assigned to it (i.e., STA1 transmits a normal PPDU to the AP through RU1) (1820). STA3, which has received the trigger frame, determines whether the condition confirmed through the trigger frame is satisfied, and if the condition is satisfied, performs transmission (normal transmission) to which coverage extension is not applied through RU2 assigned to it (i.e., STA3 transmits a normal PPDU to the AP through RU2) (1830).

[0169] Unlike the illustrated embodiment, if the condition included in the trigger frame is not satisfied, STA2 or STA3 may perform transmission to which coverage extension is applied. Alternatively, if the condition included in the trigger frame is not satisfied, STA2 or STA3 may not perform PPDU transmission.

[0170] Meanwhile, the above described embodiment in which the AP transmits conditions for transmission to which coverage extension is not applied (normal transmission) through a trigger frame. According to one embodiment, the AP transmits conditions for transmission to which coverage extension is applied as described in FIG. 17 through a trigger frame, and if these conditions are not satisfied, transmission to which coverage extension is not applied (normal transmission) may be performed. According to this embodiment, the conditions under which the AP transmits through a trigger frame for transmission to which coverage extension is applied in FIG. 17 and the conditions under which the AP transmits through a trigger frame for transmission to which coverage extension is not applied in FIG. 18 may be the same.

[0171] FIG. 19 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to one embodiment of the present disclosure.

[0172] In the embodiment illustrated in FIG. 19, the AP transmits a trigger frame for UORA (1910). According to one embodiment, the trigger frame transmitted by the AP may include information for allocating one or more RA-RUs for the UORA with coverage extension applied. For example, the trigger frame according to the embodiment of FIG. 19 may indicate that the RA-RU allocated for the UORA is for transmission with coverage extension applied (e.g., ELR PPDU transmission and / or DRU transmission).

[0173] According to one embodiment, the AP may indicate or set one or more conditions for UORA with coverage extension through a trigger frame. For example, the AP may transmit a trigger frame including conditions for an STA to perform UORA with coverage extension, and the STA receiving the trigger frame may perform UORA with coverage extension based on the identified conditions. In addition, the AP may also allocate RA-RUs to be used when performing UORA with coverage extension through the trigger frame when the above-described conditions are satisfied.

[0174] In the illustrated embodiment, the AP can indicate conditions for UORA with coverage extension applied together with allocating RA-RU for UORA through a trigger frame. According to one embodiment, the conditions for UORA with coverage extension applied transmitted through the trigger frame can include conditions related to the physical layer (PHY layer). For example, the conditions for UORA with coverage extension applied can include at least one of a received signal strength indication (RSSI) of the trigger frame, a path loss based on the transmit power of the AP, or a UL target receive power. For these conditions, the trigger frame can include at least one of a threshold value of the RSSI of the trigger frame, a threshold value for the path loss, the transmit power of the AP, a threshold value for the UL target receive power, the UL target RSSI, or a signal to noise ratio (SNR).

[0175] According to one embodiment, information on conditions for a UORA to which the above-described coverage extension is applied may be included in a trigger dependent user information subfield of a user information field included in a trigger frame. Alternatively, information on conditions for a UORA to which the above-described coverage extension is applied may be included in a trigger dependent common information subfield of a common information field included in the trigger frame. Of course, information on conditions for a UORA to which the coverage extension is applied may be included in various fields or subfields included in the trigger frame in addition to the above-described fields / subfields.

[0176] STA1, which receives a trigger frame, determines whether the condition confirmed through the trigger frame is satisfied, and if the condition is satisfied, can transmit an ELR PPDU to the AP through RU1 selected from among the RA-RUs allocated for the UORA to which coverage extension is applied (1920). That is, STA1, which receives a trigger frame from the AP, can confirm that an RA-RU is allocated for the UORA to which coverage extension is applied included in the trigger frame, and can select one of the RA-RUs (RU1) by decreasing the OBO value according to the UORA procedure described above. STA1 can transmit an uplink PPDU to the AP according to the coverage extension mode on the selected RA-RU (RU1) (or, perform ELR PPDU transmission and / or DRU transmission).

[0177] Unlike the illustrated embodiment, if the condition included in the trigger frame is not satisfied, STA1 may not perform UORA with coverage extension applied. Not performing UORA with coverage extension applied may mean that STA1 performs UORA according to the normal transmission mode without coverage extension applied. Alternatively, not performing transmission with coverage extension applied may mean that STA1 does not perform PPDU transmission according to UORA.

[0178] FIG. 20 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to one embodiment of the present disclosure.

[0179] In the embodiment illustrated in FIG. 20, the AP transmits a trigger frame (2010). The AP can indicate or set one or more conditions for transmission (or, normal transmission) to which coverage extension is not applied through the trigger frame. For example, the AP can transmit the trigger frame including conditions for an STA to perform transmission (normal transmission) to which coverage extension is not applied, and the STA that receives the trigger frame can perform transmission (normal transmission) to which coverage extension is not applied based on the identified conditions. In addition, the AP can also allocate an RU to be used when performing transmission (normal transmission) to which coverage extension is not applied when the above-described conditions are satisfied through the trigger frame.

[0180] In the illustrated embodiment, the AP may instruct STA1 on the conditions for transmission (normal transmission) to which coverage extension is not applied while allocating RU1 to STA1 via a trigger frame. Furthermore, the AP may instruct STA3 on the conditions for transmission (normal transmission) to which coverage extension is not applied while allocating RU2 to STA3 via a trigger frame. The conditions for transmission by the AP via the trigger frame may be the same or different for each of at least one STAs to which an RU is allocated.

[0181] According to one embodiment, the conditions for transmission (normal transmission) to which coverage extension is not applied through a trigger frame may include conditions related to the MAC layer. For example, the conditions for transmission (normal transmission) to which coverage extension is not applied may include at least one of whether the STA is associated with a BSS, the elapsed time since the STA was associated with the BSS, the number of beacon frames received since the STA was associated with the BSS, whether the STA and the AP exchanged data frames, whether the STA's previous transmission failed, or whether the pending frame is related to low latency traffic. For these conditions, the trigger frame may include at least one of information for indicating whether the STA has joined the BSS, a threshold value for the time elapsed since the STA has joined the BSS, a threshold value for the number of beacon frames received since the STA has joined the BSS, whether the STA's previous transmission has failed, a threshold value for the number of times the STA's previous transmission has failed, or information for indicating whether the pending frame is related to low-latency traffic.

[0182] According to one embodiment, information on conditions for transmission to which the above-described coverage extension is not applied (normal transmission) may be included in a trigger dependent user information subfield of a user information field included in a trigger frame. Alternatively, information on conditions for transmission to which the coverage extension is not applied (normal transmission) may be included in a trigger dependent common information subfield of a common information field included in the trigger frame. Of course, information on conditions for transmission to which the coverage extension is not applied (normal transmission) may be included in various fields or subfields included in the trigger frame in addition to the above-described fields / subfields.

[0183] STA1, which has received a trigger frame, determines whether the condition confirmed through the trigger frame is satisfied, and if the condition is satisfied, performs transmission (normal transmission) to which coverage extension is not applied through RU1 assigned to it (i.e., STA1 transmits a normal PPDU to the AP through RU1) (2020). STA3, which has received a trigger frame, determines whether the condition confirmed through the trigger frame is satisfied, and if the condition is satisfied, performs transmission (normal transmission) to which coverage extension is not applied through RU2 assigned to it (i.e., STA3 transmits a normal PPDU to the AP through RU2) (2030).

[0184] Unlike the illustrated embodiment, if the condition included in the trigger frame is not satisfied, STA2 or STA3 may perform transmission to which coverage extension is applied. Alternatively, if the condition included in the trigger frame is not satisfied, STA2 or STA3 may not perform PPDU transmission.

[0185] FIG. 21 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0186] In the embodiment illustrated in FIG. 21, the AP transmits a trigger frame (2110). The AP can indicate or set one or more conditions for transmission with coverage extension applied through the trigger frame. For example, the AP can transmit the trigger frame by including conditions for an STA to perform transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission), and the STA that receives the trigger frame can perform transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) based on the identified conditions. In addition, the AP can also allocate an RU to be used when performing transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) when the above-described conditions are satisfied through the trigger frame.

[0187] In the illustrated embodiment, the AP may instruct STA2 on conditions for transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) while allocating RU1 to STA2 via a trigger frame. Furthermore, the AP may instruct STA3 on conditions for transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) while allocating RU2 to STA3 via a trigger frame. The conditions for transmission by the AP via the trigger frame may be the same or different for each of at least one STAs to which an RU is allocated.

[0188] According to one embodiment, the conditions for transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) transmitted through the trigger frame may include conditions related to the MAC layer. For example, the conditions for transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) may include at least one of whether the STA is associated with a BSS, the elapsed time since the STA is associated with the BSS, the number of beacon frames received since the STA is associated with the BSS, whether the STA and the AP exchange data frames, whether the STA's previous transmission failed, or whether the pending frame is related to low latency traffic. For these conditions, the trigger frame may include at least one of information for indicating whether the STA has joined the BSS, a threshold value for the time elapsed since the STA has joined the BSS, a threshold value for the number of beacon frames received since the STA has joined the BSS, whether the STA's previous transmission has failed, a threshold value for the number of times the STA's previous transmission has failed, or information for indicating whether the pending frame is related to low-latency traffic.

[0189] According to one embodiment, information on conditions for transmission (ELR PPDU transmission and / or DRU transmission) to which the above-described coverage extension is applied may be included in a trigger dependent user information subfield of a user information field included in a trigger frame. Alternatively, information on conditions for transmission (ELR PPDU transmission and / or DRU transmission) to which the above-described coverage extension is applied may be included in a trigger dependent common information subfield of a common information field included in the trigger frame. It goes without saying that information on conditions for transmission (ELR PPDU transmission and / or DRU transmission) to which the coverage extension is applied may be included in various fields or subfields included in the trigger frame in addition to the above-described fields / subfields.

[0190] STA2, which has received a trigger frame, determines whether the condition confirmed through the trigger frame is satisfied, and if the condition is satisfied, performs transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) through RU1 allocated to it (i.e., STA1 transmits ELR PPDU to AP through RU1) (2120). In the embodiment of FIG. 21, an embodiment is shown in which the presence of low-latency traffic is indicated as a condition for transmission with coverage extension applied through the trigger frame, and STA2 performs transmission with coverage extension applied when the condition is satisfied because the pending frame of STA2 is due to the occurrence of low-latency traffic. STA3, which has received a trigger frame, determines whether the condition confirmed through the trigger frame is satisfied, and if the condition is satisfied, performs transmission with coverage extension applied (ELR PPDU transmission and / or DRU transmission) through RU2 allocated to it (i.e., STA3 transmits ELR PPDU or DRU PPDU to AP through RU2) (2130).

[0191] Unlike the illustrated embodiment, if the condition included in the trigger frame is not satisfied, STA2 or STA3 may not perform transmission with coverage extension applied. Not performing transmission with coverage extension applied may mean that STA2 or STA3 performs normal transmission without applying coverage extension. Alternatively, not performing transmission with coverage extension applied may mean that STA2 or STA3 does not transmit PPDU.

[0192] Meanwhile, the above has described an embodiment in which the AP transmits conditions for transmission to which coverage extension is applied via a trigger frame. According to one embodiment, the AP transmits conditions for transmission to which coverage extension is applied via a trigger frame, and if these conditions are not met, transmission to which coverage extension is not applied (normal transmission) may be performed. According to this embodiment, the conditions under which the AP transmits via a trigger frame for transmission to which coverage extension is not applied in FIG. 20 may be the same as the conditions under which the AP transmits via a trigger frame for transmission to which coverage extension is applied in FIG. 21.

[0193] FIG. 22 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to an embodiment of the present disclosure.

[0194] In the embodiment illustrated in FIG. 22, the AP transmits a trigger frame for UORA (2210). According to one embodiment, the trigger frame transmitted by the AP may include information for allocating one or more RA-RUs for the UORA with coverage extension applied. For example, the trigger frame according to the embodiment of FIG. 22 may indicate that the RA-RU allocated for the UORA is for transmission with coverage extension applied (e.g., ELR PPDU transmission and / or DRU transmission).

[0195] According to one embodiment, the AP may indicate or set one or more conditions for UORA with coverage extension through a trigger frame. For example, the AP may transmit a trigger frame including conditions for an STA to perform UORA with coverage extension, and the STA receiving the trigger frame may perform UORA with coverage extension based on the identified conditions. In addition, the AP may also allocate RA-RUs to be used when performing UORA with coverage extension through the trigger frame when the above-described conditions are satisfied.

[0196] In the illustrated embodiment, the AP may indicate conditions for UORA with coverage extension applied together with allocating RA-RU for UORA through a trigger frame. According to one embodiment, the conditions for UORA with coverage extension applied transmitted through the trigger frame may include conditions related to the MAC layer. For example, the conditions for UORA with coverage extension applied may include at least one of whether the STA is associated with a BSS, the elapsed time since the STA is associated with the BSS, the number of beacon frames received since the STA is associated with the BSS, whether the STA and the AP exchange data frames, whether the STA's previous transmission failed, or whether the pending frame is related to low latency traffic. For these conditions, the trigger frame may include at least one of information for indicating whether the STA has joined the BSS, a threshold value for the time elapsed since the STA has joined the BSS, a threshold value for the number of beacon frames received since the STA has joined the BSS, whether the STA's previous transmission has failed, a threshold value for the number of times the STA's previous transmission has failed, or information for indicating whether the pending frame is related to low-latency traffic.

[0197] According to one embodiment, information on conditions for a UORA to which the above-described coverage extension is applied may be included in a trigger dependent user information subfield of a user information field included in a trigger frame. Alternatively, information on conditions for a UORA to which the above-described coverage extension is applied may be included in a trigger dependent common information subfield of a common information field included in the trigger frame. Of course, information on conditions for a UORA to which the coverage extension is applied may be included in various fields or subfields included in the trigger frame in addition to the above-described fields / subfields.

[0198] STA1, which receives a trigger frame, determines whether the condition confirmed through the trigger frame is satisfied, and if the condition is satisfied, can transmit an ELR PPDU to the AP through RU1 selected from among the RA-RUs allocated for the UORA to which coverage extension is applied (2220). That is, STA1, which receives a trigger frame from the AP, can confirm that an RA-RU is allocated for the UORA to which coverage extension is applied included in the trigger frame, and can select one of the RA-RUs (RU1) by decreasing the OBO value according to the UORA procedure described above. STA1 can transmit an uplink PPDU to the AP according to the coverage extension mode on the selected RA-RU (RU1) (or, perform ELR PPDU transmission and / or DRU transmission).

[0199] Unlike the illustrated embodiment, if the condition included in the trigger frame is not satisfied, STA1 may not perform UORA with coverage extension applied. Not performing UORA with coverage extension applied may mean that STA1 performs UORA according to the normal transmission mode without coverage extension applied. Alternatively, not performing transmission with coverage extension applied may mean that STA1 does not perform PPDU transmission according to UORA.

[0200] In the above FIGS. 17 to 19, embodiments in which conditions related to the PHY layer are indicated for transmission or UORA with coverage extension applied (or transmission or UORA without coverage extension applied) are described, and in FIGS. 20 to 22, embodiments in which conditions related to the MAC layer are indicated for transmission or UORA with coverage extension applied (or transmission or UORA without coverage extension applied) are described. Meanwhile, according to one embodiment, a combination of at least one of a condition related to the PHY layer and a condition related to the MAC layer may be indicated for transmission or UORA with coverage extension applied (or transmission or UORA without coverage extension applied). According to this embodiment, the AP may indicate a combination of a condition related to the PHY layer and a condition related to the MAC layer through a trigger frame, and when the combination of these conditions is satisfied, transmission or UORA with coverage extension applied (or transmission or UORA without coverage extension applied) may be performed. According to another embodiment, the AP may indicate a plurality of conditions related to the PHY layer and a plurality of conditions related to the MAC layer through a trigger frame, and the STA may perform transmission or UORA with coverage extension applied (or transmission or UORA without coverage extension applied) when a preset (or indicated) number of conditions among the indicated plurality of conditions are satisfied. According to this embodiment, a threshold value or related parameter for the number of conditions to be satisfied for transmission or UORA with coverage extension applied (or transmission or UORA without coverage extension applied) may also be indicated to the STA through the trigger frame.

[0201] FIG. 23 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to one embodiment of the present disclosure.

[0202] In the embodiment illustrated in FIG. 23, the AP transmits a trigger frame for UORA (2310). The trigger frame transmitted by the AP may include information for allocating one or more RA-RUs for UORA. According to one embodiment, the trigger frame transmitted by the AP may indicate that at least some of the RA-RUs allocated for UORA are for STAs located at the BSS edge. For example, in FIG. 23, the trigger frame for UORA transmitted by the AP may indicate that RA-RU1 is for an STA located at the BSS center (i.e., a normal STA) or an STA associated with the AP (i.e., an associated STA), and that RA-RU2 is for an STA located at the BSS edge (i.e., an edge STA).

[0203] According to one embodiment, the trigger frame for UORA may further include conditions for determining whether an STA is located at the BSS center or the BSS boundary. According to one embodiment, the AP may indicate or set one or more conditions for UORA of a BSS boundary STA through the trigger frame. An STA that receives the trigger frame may transmit a PPDU through an RA-RU allocated for a BSS boundary STA, as the STA determines that it is a BSS boundary STA based on the identified conditions.

[0204] According to one embodiment, the conditions for determining a normal STA (or combined STA) and a border STA transmitted through a trigger frame may include combinations of at least one or more of the physical layer-related conditions described in FIGS. 17 to 19 and the MAC layer-related conditions described in FIGS. 20 to 22. For example, the conditions for determining a normal STA (or combined STA) and a border STA may include at least one of the PHY layer-related conditions, such as the received signal strength indication (RSSI) of the trigger frame, path loss based on the transmission power of the AP, or UL target receive power. In addition, the conditions for determining a general STA (or, associated STA) and a border STA may include at least one of whether the STA is associated with a BSS, the time elapsed since the STA was associated with the BSS, the number of beacon frames received since the STA was associated with the BSS, whether data frames were exchanged between the STA and the AP, whether the previous transmission of the STA failed, or whether the pending frame is related to low latency traffic.For these conditions, the trigger frame may include at least one of a threshold value of RSSI of the trigger frame, a threshold value for path loss, a threshold value for transmit power of the AP, a threshold value for UL target receive power, a UL target RSSI, or a signal to noise ratio (SNR), and the trigger frame may include at least one of information for indicating as a condition whether the STA has joined a BSS, a threshold value for an elapsed time since the STA has joined a BSS, a threshold value for a number of beacon frames received since the STA has joined a BSS, whether a previous transmission of the STA has failed, a threshold value for the number of times the STA has failed a previous transmission, or information for indicating as a condition whether a pending frame is related to low-latency traffic.

[0205] Similar to the above description, the trigger frame includes multiple conditions related to the PHY layer and multiple conditions related to the MAC layer, and the STA may determine whether it is a normal STA (or a combined STA) or a border STA based on whether a preset (or indicated) number of conditions among the indicated multiple conditions are satisfied.

[0206] According to one embodiment, information on conditions for determining a general STA (or a combined STA) and a border STA may be included in a trigger dependent user information subfield of a user information field included in a trigger frame. Alternatively, information on conditions for determining a general STA (or a combined STA) and a border STA may be included in a trigger dependent common information subfield of a common information field included in the trigger frame. It goes without saying that information on conditions for determining a general STA (or a combined STA) and a border STA may be included in various fields or subfields included in the trigger frame in addition to the above-described fields / subfields.

[0207] STA1, which has received the trigger frame, can determine whether the condition confirmed through the trigger frame is satisfied, and can determine whether it is a normal STA (or a combined STA) based on whether the condition is satisfied. Accordingly, STA1 can transmit a PPDU to the AP through RU1 selected from among the RA-RUs allocated for the UORA of the normal STA (or the combined STA) (2320). STA3, which has received the trigger frame, can determine whether the condition confirmed through the trigger frame is satisfied, and can determine whether it is a border STA based on whether the condition is satisfied. Accordingly, STA3 can transmit a PPDU to the AP through RU2 selected from among the RA-RUs allocated for the UORA of the border STA (2330).

[0208] FIG. 24 is a flowchart illustrating a transmission and reception operation applying coverage expansion according to one embodiment of the present disclosure.

[0209] In the embodiment illustrated in FIG. 24, the AP transmits a trigger frame for UORA (2410). The trigger frame transmitted by the AP may include information for allocating one or more RA-RUs for the UORA. According to one embodiment, the trigger frame transmitted by the AP may indicate that at least some of the RA-RUs allocated for the UORA are for STAs located at the BSS edge. For example, in FIG. 24, the trigger frame for UORA transmitted by the AP may indicate that RA-RU1 is for STAs that are not associated with the AP (i.e., non-associated STAs), and that RA-RU2 is for STAs located at the BSS edge (i.e., edge STAs).

[0210] According to one embodiment, the trigger frame for UORA may further include conditions for determining whether an STA is located at the BSS center or the BSS boundary. According to one embodiment, the AP may indicate or set one or more conditions for UORA of a BSS boundary STA through the trigger frame. An STA that receives the trigger frame may transmit a PPDU through an RA-RU allocated for a BSS boundary STA, as the STA determines that it is a BSS boundary STA based on the identified conditions.

[0211] According to one embodiment, the conditions for determining non-associated STAs and border STAs transmitted through a trigger frame may include combinations of at least one or more of the physical layer-related conditions described in FIGS. 17 to 19 and the MAC layer-related conditions described in FIGS. 20 to 22. For example, the conditions for determining non-associated STAs and border STAs may include at least one of the PHY layer-related conditions, such as the received signal strength indication (RSSI) of the trigger frame, path loss based on the transmission power of the AP, or UL target receive power. In addition, the conditions for determining a non-association STA and a border STA may include at least one of whether the STA is associated with a BSS, the time elapsed since the STA was associated with the BSS, the number of beacon frames received since the STA was associated with the BSS, whether the STA and the AP exchanged data frames, whether the STA's previous transmission failed, or whether the pending frame is related to low latency traffic. For these conditions, the trigger frame may include at least one of a threshold value of RSSI of the trigger frame, a threshold value for path loss, a threshold value for transmit power of the AP, a threshold value for UL target receive power, a UL target RSSI, or a signal to noise ratio (SNR), and the trigger frame may include at least one of information for indicating as a condition whether the STA has joined a BSS, a threshold value for an elapsed time since the STA has joined a BSS, a threshold value for a number of beacon frames received since the STA has joined a BSS, whether a previous transmission of the STA has failed, a threshold value for the number of times the STA has failed a previous transmission, or information for indicating as a condition whether a pending frame is related to low-latency traffic.

[0212] Similar to the above, the trigger frame includes multiple conditions related to the PHY layer and multiple conditions related to the MAC layer, and the STA may determine whether it is a non-associative STA or a border STA based on whether a preset (or indicated) number of conditions among the indicated multiple conditions are satisfied.

[0213] According to one embodiment, information on conditions for determining whether a non-associated STA is a boundary STA may be included in a trigger dependent user information subfield of a user information field included in a trigger frame. Alternatively, information on conditions for determining whether a non-associated STA is a boundary STA may be included in a trigger dependent common information subfield of a common information field included in the trigger frame. Of course, information on conditions for determining whether a non-associated STA is a boundary STA may be included in various fields or subfields included in the trigger frame in addition to the above-described fields / subfields.

[0214] STA2, which has received the trigger frame, can determine whether the condition confirmed through the trigger frame is satisfied, and based on whether the condition is satisfied, can determine that it is a non-association STA. Accordingly, STA2 can transmit a PPDU to the AP through RU1 selected from among the RA-RUs allocated for the UORA of the non-association STA (2420). STA3, which has received the trigger frame, can determine whether the condition confirmed through the trigger frame is satisfied, and based on whether the condition is satisfied, can determine that it is a border STA. Accordingly, STA3 can transmit a PPDU to the AP through RU2 selected from among the RA-RUs allocated for the UORA of the border STA (2430).

[0215] According to the embodiments described above, an STA can perform UORA with coverage extension based on various conditions included in the trigger frame transmitted by the AP. Meanwhile, according to one embodiment, a parameter set for UORA with coverage extension may be configured separately from a parameter set for UORA without coverage extension. This is because adjusting the OCW range may be necessary for UORA with coverage extension.

[0216] According to one embodiment, some of the UORA parameter set elements described in FIG. 12 may be changed or new elements may be defined to set parameters for a UORA with coverage extension applied. For example, one or more of the reserved bits illustrated in (b) of FIG. 12 may be utilized for a UORA with coverage extension applied. According to this example, one or more of the reserved bits may indicate a scaling factor, a multiplication factor, or a division factor for the values ​​indicated by the EOCWmin subfield and the EOCWmax subfield. That is, the value indicated by one or more of the reserved bits may be applied to the values ​​indicated by the EOCWmin subfield and the values ​​indicated by the EOCWmax subfield, respectively, so that the OCW range may be adjusted. According to another example, a parameter set element for a UORA with coverage extension applied may be newly defined separately from the UORA parameter set element illustrated in (a) of FIG. 12. According to this example, the parameter set element for a UORA with coverage extension applied may have a value of at least one of the element ID field or the element ID extension field that is different from the value of the UORA parameter set element described in (a) of FIG. 12.

[0217] When parameters for UORA with coverage extension applied according to the above-described embodiment are separately set, the STA can determine the OCW range based on the received parameters and select the OBO value to perform UORA.

[0218] FIG. 25 illustrates a flowchart of the operation of a non-AP STA applying coverage extension according to an embodiment of the present disclosure. The embodiments described for performing transmission with coverage extension applied by a non-AP STA can be applied to the operation of the non-AP STA of FIG. 25, and of course, the operation of the non-AP STA of FIG. 25 can vary depending on the embodiments described above.

[0219] According to one embodiment, a non-AP STA receives a frame for a UORA with coverage extension applied (or a transmission with coverage extension applied) from an AP (2510). The UORA with coverage extension applied or the transmission with coverage extension applied may include at least one of the ELR PPDU transmission and / or DRU transmission described above, and the operation according to such transmission with coverage extension applied may be referred to as a coverage extension mode, as described above.

[0220] The frame received by the non-AP STA may include a trigger frame for indicating the application of coverage extension. Additionally, the frame received by the non-AP STA may include information for allocating an RA-RU for a UORA with coverage extension applied or an RU for a transmission with coverage extension applied.

[0221] A non-AP STA determines an RU based on a frame received from an AP (2520) and transmits an uplink PPDU in the determined RU (2530). The non-AP STA may transmit a PPDU in the determined RU according to a coverage extension mode, and such transmission may include transmission of an ELR PPDU and / or transmission of a DRU.

[0222] Figure 26 illustrates a flowchart illustrating the operation of an AP applying coverage extension according to one embodiment of the present disclosure. The embodiments described for allowing an AP to receive transmissions applying coverage extension from non-AP STAs can be applied to the operation of the AP of Figure 26, and it should be understood that the operation of the AP of Figure 26 may vary depending on the embodiments described above.

[0223] According to one embodiment, an AP transmits a frame for UORA (or transmission with coverage extension) with coverage extension applied to a non-AP STA (2610). The UORA with coverage extension applied or the transmission with coverage extension applied may include at least one of the ELR PPDU transmission and / or DRU transmission described above, and the operation according to such transmission with coverage extension applied may be referred to as a coverage extension mode, as described above.

[0224] The frame transmitted by the AP may include a trigger frame to indicate the application of coverage extension. Additionally, the frame transmitted by the AP may include information for allocating an RA-RU for a UORA with coverage extension applied or an RU for a transmission with coverage extension applied.

[0225] The AP receives an uplink PPDU from a non-AP STA on an RU determined according to the transmitted frame (2620). The uplink PPDU received by the AP may be transmitted from a non-AP STA according to a coverage extension mode, and such transmission may include transmission of an ELR PPDU and / or transmission of a DRU.

[0226] FIG. 27 illustrates a flowchart of the operation of a non-AP STA applying coverage extension according to an embodiment of the present disclosure. The embodiments described for performing transmission with coverage extension applied by a non-AP STA can be applied to the operation of the non-AP STA of FIG. 27, and of course, the operation of the non-AP STA of FIG. 27 can vary depending on the embodiments described above.

[0227] According to one embodiment, a non-AP STA receives a frame for a UORA with coverage extension applied (or a transmission with coverage extension applied) from an AP (2710). The UORA with coverage extension applied or the transmission with coverage extension applied may include at least one of the ELR PPDU transmission and / or DRU transmission described above, and the operation according to such transmission with coverage extension applied may be referred to as a coverage extension mode, as described above.

[0228] A frame received by a non-AP STA may include a trigger frame for indicating application of coverage extension. In addition, the frame received by the non-AP STA may include information for allocating an RA-RU for a UORA with coverage extension applied or an RU for a transmission with coverage extension applied. In addition, the frame received by the non-AP STA may include one or more conditions or a combination of conditions for a UORA with coverage extension applied or a transmission with coverage extension applied. For example, a frame received by a non-AP STA may include one or more of a condition related to a PHY layer or a condition related to a MAC layer. Conversely, a frame received by a non-AP STA may include one or more conditions or a combination of conditions for a UORA without coverage extension applied or a transmission without coverage extension applied. These conditions may include one or more of a condition related to a PHY layer or a condition related to a MAC layer.

[0229] A non-AP STA determines whether to apply coverage extension based on the received frame (2720). That is, a non-AP STA can determine whether conditions included in the frame received from the AP are satisfied, and based on whether these conditions are satisfied, determine whether to perform a UORA with coverage extension applied or a transmission with coverage extension applied.

[0230] When a non-AP STA decides to perform UORA with coverage extension applied or transmission with coverage extension applied, the non-AP STA determines an RU based on a frame received from the AP (2730) and transmits an uplink PPDU in the determined RU (2740). The non-AP STA may transmit a PPDU in the determined RU according to the coverage extension mode, and such transmission may include transmission of an ELR PPDU and / or transmission of a DRU.

[0231] Figure 28 illustrates a flowchart illustrating the operation of an AP applying coverage extension according to one embodiment of the present disclosure. The embodiments described for allowing an AP to receive transmissions applying coverage extension from non-AP STAs can be applied to the operation of the AP of Figure 28, and it is to be understood that the operation of the AP of Figure 28 may vary depending on the embodiments described above.

[0232] According to one embodiment, the AP determines non-AP STAs to which coverage extension is to be applied and / or conditions to which coverage extension is to be applied (2810). The AP determining non-AP STAs to which coverage extension is to be applied may include a process of determining non-AP STAs to which coverage extension is to be applied, such as performing a UORA with coverage extension applied or performing a transmission with coverage extension applied. The AP determining conditions to which coverage extension is to be applied may include a process of determining one or more conditions for performing a UORA with coverage extension applied or a transmission with coverage extension applied.

[0233] The AP transmits a frame for UORA (or transmission with coverage extension applied) to a non-AP STA (2820). The UORA with coverage extension applied or transmission with coverage extension applied may include at least one of the ELR PPDU transmission and / or DRU transmission described above, and the operation according to such transmission with coverage extension applied may be referred to as coverage extension mode, as described above.

[0234] The frame transmitted by the AP may include a trigger frame for indicating application of coverage extension. In addition, the frame transmitted by the AP may include information for allocating an RA-RU for a UORA with coverage extension applied or an RU for a transmission with coverage extension applied. In addition, the frame transmitted by the AP may include one or more conditions or a combination of conditions previously determined for a UORA with coverage extension applied or a transmission with coverage extension applied. For example, the frame transmitted by the AP may include one or more of a condition related to the PHY layer or a condition related to the MAC layer. Conversely, the frame transmitted by the AP may include one or more conditions or a combination of conditions for a UORA without coverage extension applied or a transmission without coverage extension applied. These conditions may include one or more of a condition related to the PHY layer or a condition related to the MAC layer.

[0235] The AP receives an uplink PPDU from a non-AP STA on an RU determined according to the transmitted frame (2830). The uplink PPDU received by the AP may be transmitted from a non-AP STA according to a coverage extension mode, and such transmission may include transmission of an ELR PPDU and / or transmission of a DRU.

[0236] Meanwhile, the present specification and drawings disclose preferred embodiments of the present disclosure, and although specific terms are used, they are used only in a general sense to easily explain the technical contents of the present disclosure and to help understand the disclosure, and are not intended to limit the scope of the present disclosure.

[0237] Furthermore, it will be apparent to those skilled in the art that, in addition to the embodiments described in this disclosure, other modifications based on the technical concepts of this disclosure are possible. For example, some or all of the contents of one embodiment described above may be combined with some or all of one or more other embodiments, and such combinations are also included in the embodiments proposed in this disclosure.

Claims

1. A method performed by a STA (station) of a wireless local area network (WLAN) system, A step of receiving a trigger frame for uplink OFDMA (orthogonal frequency division multiple access) based random access (UORA) to which coverage extension based on an enhanced long range (ELR) physical layer protocol data unit (PPDU) is applied from an access point (AP), wherein the UORA to which the coverage extension is applied is indicated by at least one of a user information field or a common information field of the trigger frame; A step of determining a random access resource unit (RA-RU) based on the trigger frame; and A method comprising the step of transmitting the ELR PPDU using the RA-RU to the AP.

2. In paragraph 1, A method characterized in that the trigger frame indicates a UORA to which the coverage extension is applied based on at least one of an AID12 (association identifier 12) subfield included in the user information field, a UL (uplink) HE (high efficiency)-MCS (modulation and coding scheme) subfield included in the user information field, or a bit included in the common information field.

3. In paragraph 1, A method characterized in that the trigger frame indicates at least one of a threshold value for a received signal strength indication (RSSI) of the trigger frame, a path loss based on the transmission power of the AP, or a UL target receive power for UORA to which the coverage extension is applied.

4. In paragraph 1, A method characterized in that the trigger frame indicates at least one of whether or not to associate with a basic service set (BSS), the time elapsed since association with the BSS, whether or not to exchange data frames, whether or not previous transmission failed, or low latency traffic for the UORA to which the coverage extension is applied.

5. In a method performed by an AP (access point) of a wireless local area network (WLAN) system, A step of transmitting a trigger frame for uplink OFDMA (orthogonal frequency division multiple access) based random access (UORA) to which an enhanced long range (ELR) physical layer protocol data unit (PPDU)-based coverage extension is applied to an STA (station), wherein the UORA to which the coverage extension is applied is indicated by at least one of a user information field or a common information field of the trigger frame; and A method comprising the step of receiving the ELR PPDU from the STA using a random access resource unit (RA-RU) based on the trigger frame.

6. In paragraph 5, A method characterized in that the trigger frame indicates a UORA to which the coverage extension is applied based on at least one of an AID12 (association identifier 12) subfield included in the user information field, a UL (uplink) HE (high efficiency)-MCS (modulation and coding scheme) subfield included in the user information field, or a bit included in the common information field.

7. In paragraph 5, A method characterized in that the trigger frame indicates at least one of a threshold for a received signal strength indication (RSSI) of the trigger frame, a path loss based on the transmission power of the AP, a UL target receive power, whether or not to associate with a basic service set (BSS), a time elapsed since association with the BSS, whether or not to exchange data frames, whether or not previous transmission failed, or low latency traffic, for UORA to which the coverage extension is applied.

8. In the STA (station) of a wireless local area network (WLAN) system, At least one transceiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions, The above instructions are executed individually or in any combination by the at least one processor, so that the STA: A trigger frame for uplink OFDMA (orthogonal frequency division multiple access) based random access (UORA) with coverage extension based on ELR (enhanced long range) PPDU (physical layer protocol data unit) is received from an access point (AP), wherein the UORA with the coverage extension applied is indicated by at least one of a user information field or a common information field of the trigger frame, Determine the RA-RU (random access resource unit) based on the above trigger frame, An STA that transmits the ELR PPDU to the AP using the RA-RU.

9. In paragraph 8, An STA characterized in that the trigger frame indicates a UORA to which the coverage extension is applied based on at least one of an AID12 (association identifier 12) subfield included in the user information field, a UL (uplink) HE (high efficiency)-MCS (modulation and coding scheme) subfield included in the user information field, or a bit included in the common information field.

10. In paragraph 8, An STA characterized in that the trigger frame indicates at least one of a threshold value for a received signal strength indication (RSSI) of the trigger frame, a path loss based on the transmission power of the AP, or a UL target receive power for UORA to which the coverage extension is applied.

11. In paragraph 8, An STA characterized in that the trigger frame indicates at least one of whether or not to associate with a basic service set (BSS), the time elapsed since association with the BSS, whether or not to exchange data frames, whether or not previous transmission failed, or low latency traffic for the UORA to which the coverage extension is applied.

12. In the AP (access point) of a wireless local area network (WLAN) system, At least one transceiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions, The above instructions are executed individually or in any combination by the at least one processor, so that the AP: Transmitting a trigger frame for uplink OFDMA (orthogonal frequency division multiple access) based random access (UORA) with coverage extension based on ELR (enhanced long range) PPDU (physical layer protocol data unit) to an STA (station), wherein the UORA with the coverage extension applied is indicated by at least one of a user information field or a common information field of the trigger frame, An AP that receives the ELR PPDU from the STA using a random access resource unit (RA-RU) based on the trigger frame.

13. In paragraph 12, An AP characterized in that the trigger frame indicates a UORA to which the coverage extension is applied based on at least one of an AID12 (association identifier 12) subfield included in the user information field, a UL (uplink) HE (high efficiency)-MCS (modulation and coding scheme) subfield included in the user information field, or a bit included in the common information field.

14. In paragraph 12, An AP characterized in that the trigger frame indicates at least one of a threshold value for a received signal strength indication (RSSI) of the trigger frame, a path loss based on the transmission power of the AP, or a UL target receive power for UORA to which the coverage extension is applied.

15. In paragraph 12, An AP characterized in that the trigger frame indicates at least one of whether or not an association with a basic service set (BSS) has occurred, the time elapsed since association with the BSS, whether or not a data frame has been exchanged, whether or not a previous transmission has failed, or low latency traffic, for the UORA to which the coverage extension has been applied.

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