WO2024151130A1 - Method and device for performing relay transmission in wireless lan system - Google Patents

Abstract

A method and a device operating in a wireless LAN system are disclosed. The method performed by means of a first station (STA) in a wireless LAN system, according to one embodiment of the present disclosure, comprises the steps of: transmitting, to an access point (AP), a first feedback frame based on a first null data physical layer protocol data unit (NDP) received from the AP; receiving, from the AP, a request frame for a first channel measurement between the first STA and one or more second STAs; and receiving a second feedback frame from each of the one or more second STAs, wherein the second feedback frame can be based on a second NDP transmitted from the first STA to the one or more second STAs.

Description

Method and device for performing relay transmission in a wireless LAN system

This disclosure relates to communication operations in a wireless local area network (WLAN) system, and more specifically, to a method and device for performing relay transmission in a next-generation wireless LAN system.

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

In order to provide a more improved wireless communication environment, improvement technology for EHT (Extremely High Throughput) is being discussed. For example, technologies are being researched for increased bandwidth, efficient use of multiple bands, Multiple Input Multiple Output (MIMO) to support increased spatial streams, and multiple access point (AP) coordination, especially low latency. ) or real-time characteristics, various technologies are being studied to support traffic. Furthermore, new technologies are being discussed to support ultra-high reliability (UHR), including improvements or expansions of EHT technology.

The technical problem of the present disclosure is to provide a method and device for performing relay transmission in a wireless LAN system.

The technical task of the present disclosure is to provide a method and device for performing a channel measurement procedure for performing relay transmission.

The technical problems to be achieved by this disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below. You will be able to.

In one embodiment of the present disclosure, a method performed by a first station (STA) in a wireless LAN system includes a first null data physical layer protocol data unit received from an access point (AP). , transmitting a first feedback frame based on NDP) to the AP; Receiving a request frame for first channel measurement between the first STA and one or more second STAs from the AP; and receiving a second feedback frame from each of the one or more second STAs, wherein the second feedback frame may be based on a second NDP transmitted from the first STA to the one or more second STAs.

As another example of the present disclosure, a method performed by an access point (AP) in a wireless LAN system is based on a first null data physical layer protocol data unit (NDP) transmitted by the AP. Receiving a first feedback frame from a first station (STA); Transmitting a request frame for first channel measurement between the first STA and one or more second STAs to the first STA; And receiving channel information between each of the first STA and the one or more second STAs from the first STA, and providing second feedback including channel information between the first STA and each of the one or more second STAs. The frame may be based on a second NDP transmitted from the first STA to the one or more second STAs.

By various embodiments of the present disclosure, a method and device for performing relay transmission in a wireless LAN system can be provided.

By various embodiments of the present disclosure, a method and apparatus for performing a channel measurement procedure for performing relay transmission of the present disclosure can be provided.

According to various embodiments of the present disclosure, the influence of range and obstacles can be reduced through a relay transmission procedure, and the reception SNR of the STA can be improved to reduce delay for signal transmission and improve output amount.

The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. .

The accompanying drawings, which are included as part of the detailed description to aid understanding of the present disclosure, provide embodiments of the present disclosure and explain technical features of the present disclosure together with the detailed description.

1 illustrates a block diagram of a wireless communication device according to an embodiment of the present disclosure.

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

Figure 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

Figure 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

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

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

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

8 shows an example format of a trigger frame to which this disclosure may be applied.

Figure 9 is a flowchart for explaining a method performed by a first STA, according to an embodiment of the present disclosure.

Figure 10 is a flowchart for explaining a method performed by an AP, according to an embodiment of the present disclosure.

FIG. 11 is a diagram for explaining a relay operation procedure according to an embodiment of the present disclosure.

Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the attached drawings. The detailed description set forth below in conjunction with the accompanying drawings is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure may be practiced. The following detailed description includes specific details to provide a thorough understanding of the disclosure. However, one skilled in the art will understand that the present disclosure may be practiced without these specific details.

In some cases, in order to avoid ambiguity in the concept of the present disclosure, well-known structures and devices may be omitted or may be shown in block diagram form focusing on the core functions of each structure and device.

In the present disclosure, when a component is said to be “connected,” “coupled,” or “connected” to another component, this is not only a direct connection relationship, but also an indirect connection relationship where another component exists between them. It may also be included. Additionally, in this disclosure, the terms "comprise" or "having" specify the presence of a referenced feature, step, operation, element, and/or component, but may also specify the presence of one or more other features, steps, operations, elements, components, and/or components. It does not rule out the existence or addition of these groups.

In the present disclosure, terms such as “first”, “second”, etc. are used only for the purpose of distinguishing one component from another component and are not used to limit the components, and unless specifically mentioned, the terms There is no limitation on the order or importance between them. Accordingly, within the scope of the present disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, the second component in one embodiment may be referred to as a first component in another embodiment. It may also be called.

The terminology used in this disclosure is for description of specific 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, unless the context clearly dictates otherwise. As used in this disclosure, the term “and/or” is meant to refer to and include any one of the associated listed items, or any and all possible combinations of two or more thereof. Additionally, in this disclosure, “/” between words has the same meaning as “and/or” unless otherwise explained.

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

Hereinafter, technical features to which examples of the present disclosure can be applied will be described.

1 illustrates a block diagram of a wireless communication device according to an embodiment of the present disclosure.

The first device 100 and the second device 200 illustrated in FIG. 1 are a terminal, a wireless device, a wireless transmit receive unit (WTRU), a user equipment (UE), and a mobile station (MS). ), a user terminal (UT), a Mobile Subscriber Station (MSS), a Mobile Subscriber Unit (MSS), a Subscriber Station (SS), an Advanced Mobile Station (AMS), a Wireless terminal (WT), or simply a user. It can be replaced by the term In addition, the first device 100 and the second device 200 include an access point (AP), a base station (BS), a fixed station, Node B, a base transceiver system (BTS), a network, It can be replaced by various terms such as AI (Artificial Intelligence) system, RSU (road side unit), repeater, router, relay, gateway, etc.

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

Referring to FIG. 1, the first device 100 and the second device 200 may transmit and receive wireless signals through various wireless LAN technologies (eg, IEEE 802.11 series). The first device 100 and the second device 200 may include interfaces to a medium access control (MAC) layer and a physical layer (PHY) that comply with the provisions of the IEEE 802.11 standard.

Additionally, the first device 100 and the second device 200 may additionally support various communication standards (e.g., 3GPP LTE series, 5G NR series standards, etc.) technologies other than wireless LAN technology. Additionally, the device of the present disclosure may be implemented in various devices such as mobile phones, vehicles, personal computers, AR (Augmented Reality) equipment, and VR (Virtual Reality) equipment. In addition, the STA of this specification includes voice calls, video calls, data communications, autonomous driving (Autonomous-Driving), Machine-Type Communication (MTC), Machine-to-Machine (M2M), Device-to-Device (D2D), It can support various communication services such as IoT (Internet-of-Things).

The first device 100 includes one or more processors 102 and one or more memories 104, and may further include one or more transceivers 106 and/or one or more antennas 108. Processor 102 controls memory 104 and/or transceiver 106 and may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in this disclosure. For example, the processor 102 may process information in the memory 104 to generate first information/signal and then transmit a wireless signal including the first information/signal through the transceiver 106. Additionally, the processor 102 may receive a wireless signal including the second information/signal through the transceiver 106 and then store information obtained from signal processing of the second information/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, memory 104 may perform some or all of the processes controlled by processor 102, or instructions for performing the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in this disclosure. Software code including instructions can be stored. Here, the processor 102 and the memory 104 may be part of a communication modem/circuit/chip designed to implement wireless LAN technology (eg, IEEE 802.11 series). Transceiver 106 may be coupled to processor 102 and may transmit and/or receive wireless signals via one or more antennas 108. Transceiver 106 may include a transmitter and/or receiver. The transceiver 106 can be used interchangeably with an RF (Radio Frequency) unit. In this disclosure, a device may mean a communication modem/circuit/chip.

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

Hereinafter, the hardware elements of the devices 100 and 200 will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors 102, 202. For example, one or more processors 102, 202 may implement one or more layers (e.g., functional layers such as PHY and 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, suggestions, methods, and/or operational flowcharts disclosed in this disclosure. can be created. One or more processors 102, 202 may generate messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in this disclosure. One or more processors 102, 202 may process signals (e.g., baseband signals) containing PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and/or methods disclosed in this disclosure. It can be generated and provided to one or more transceivers (106, 206). One or more processors 102, 202 may receive signals (e.g., baseband signals) from one or more transceivers 106, 206 and may use the descriptions, functions, procedures, suggestions, methods, and/or methods disclosed in this disclosure. PDU, SDU, message, control information, data or information can be obtained according to the operation flow charts.

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

One or more memories 104, 204 may be connected to one or more processors 102, 202 and may store various types of data, signals, messages, information, programs, codes, instructions, and/or instructions. One or more memories 104, 204 may consist of ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer readable storage media, and/or combinations thereof. One or more memories 104, 204 may be located internal to and/or external to one or more processors 102, 202. Additionally, one or more memories 104, 204 may be connected to one or more processors 102, 202 through various technologies, such as wired or wireless connections.

One or more transceivers 106, 206 may transmit user data, control information, wireless signals/channels, etc. mentioned in the methods and/or operation flowcharts of the present disclosure to one or more other devices. One or more transceivers 106, 206 may receive user data, control information, wireless signals/channels, etc. referred to in the descriptions, functions, procedures, suggestions, methods and/or operational flow charts, etc. disclosed in this disclosure from one or more other devices. there is. For example, one or more transceivers 106 and 206 may be connected to one or more processors 102 and 202 and may transmit and receive wireless signals. For example, one or more processors 102, 202 may control one or more transceivers 106, 206 to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors 102, 202 may control one or more transceivers 106, 206 to receive user data, control information, or wireless signals from one or more other devices. In addition, one or more transceivers (106, 206) may be connected to one or more antennas (108, 208), and one or more transceivers (106, 206) may be connected to the one or more antennas (108, 208) according to the description and functions disclosed in the present disclosure. , may be set to transmit and receive user data, control information, wireless signals/channels, etc. mentioned in procedures, proposals, methods and/or operation flow charts, etc. In the present disclosure, the one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (eg, antenna ports). One or more transceivers (106, 206) process the received user data, control information, wireless signals/channels, etc. using one or more processors (102, 202), and convert the received wireless signals/channels, etc. from the RF band signal. It can be converted to a baseband signal. One or more transceivers (106, 206) may convert user data, control information, wireless signals/channels, etc. processed using one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers 106, 206 may comprise (analog) oscillators and/or filters.

For example, one of the STAs (100, 200) may perform the intended operation of the AP, and the other STA (100, 200) may perform the intended operation of the non-AP STA. For example, the transceivers 106 and 206 of FIG. 1 may transmit signals (e.g., packets or PPDU (Physical layer Protocol Data Unit) compliant with IEEE 802.11a/b/g/n/ac/ax/be/bn, etc.) Transmission and reception operations can be performed. Additionally, in the present disclosure, operations in which various STAs generate transmission/reception signals or perform data processing or computation in advance for transmission/reception signals may be performed by the processors 102 and 202 of FIG. 1 . For example, an example of an operation that generates a transmission/reception signal or performs data processing or calculation in advance for the transmission/reception signal is 1) fields included in the PPDU (signal (SIG), short training field (STF), long training field (LTF)) 2) Time resources or frequencies used for fields (SIG, STF, LTF, Data, etc.) included in the PPDU An operation to determine/configure/acquire resources (e.g., subcarrier resources), etc., 3) a specific sequence (e.g., pilot sequence) used for fields (SIG, STF, LTF, Data, etc.) included in the PPDU , STF/LTF sequence, extra sequence applied to SIG), etc., 4) power control operation and/or power saving operation applied to STA, 5) determining/obtaining/configuring ACK signal. /May include operations related to operations/decoding/encoding, etc. In addition, in the examples below, various information (e.g., information related to fields/subfields/control fields/parameters/power, etc.) used by various STAs to determine/acquire/configure/operate/decode/encode transmission/reception signals is It may be stored in memories 104 and 204 of FIG. 1 .

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.

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

The structure of a wireless LAN system may be composed of a plurality of components. A wireless LAN supporting STA mobility that is transparent to the upper layer can be provided through the interaction of a plurality of components. BSS (Basic Service Set) corresponds to the basic building block of wireless LAN. In Figure 2, there are two BSSs (BSS1 and BSS2), and two STAs are included as members of each BSS (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2). It shows. In FIG. 2, the oval representing the BSS can also be understood as representing the coverage area in which STAs included in the BSS maintain communication. This area may be referred to as BSA (Basic Service Area). If an STA moves outside the BSA, it will no longer be able to communicate directly with other STAs within the BSA.

Unless the DS shown in FIG. 2 is considered, the most basic type of BSS in a wireless LAN is an independent BSS (Independent BSS, IBSS). For example, IBSS may have a minimal form consisting of only two STAs. For example, assuming that other components are omitted, BSS1 consisting of only STA1 and STA2 or BSS2 consisting of only STA3 and STA4 may each correspond to a representative example of an IBSS. This configuration is possible when STAs can communicate directly without an AP. Additionally, in this type of wireless LAN, a LAN may be configured when necessary rather than planned in advance, and this may be referred to as an ad-hoc network. Because IBSS does not include an AP, there is no centralized management entity. That is, in IBSS, STAs are managed in a distributed manner. In IBSS, all STAs can be mobile STAs, and access to the distributed system (DS) is not allowed, forming a self-contained network.

The STA's membership in the BSS may be dynamically changed by turning the STA on or off, entering or exiting the BSS area, etc. To become a member of a BSS, an STA can join the BSS using a synchronization process. In order to access all services of the BSS infrastructure, the STA must be associated with the BSS. This association may be set dynamically and may include the use of a Distribution System Service (DSS).

In a wireless LAN, direct STA-to-STA distance may be limited by PHY performance. In some cases, this distance limit may be sufficient, but in other cases, communication between STAs over a longer distance may be necessary. A distributed system (DS) may be configured to support expanded coverage.

DS refers to the structure in which BSSs are interconnected. Specifically, as shown in FIG. 2, a BSS may exist as an expanded component of a network composed of a plurality of BSSs. DS is a logical concept and can be specified by the characteristics of distributed system media (DSM). In this regard, Wireless Medium (WM) and DSM can be logically distinguished. Each logical medium serves a different purpose and is used by different components. These media are neither limited to being the same nor different. In this way, the flexibility of the wireless LAN structure (DS structure or other network structure) can be explained in that the plurality of media are logically different. That is, the wireless LAN structure can be implemented in various ways, and the wireless LAN structure can be independently specified depending on the physical characteristics of each implementation.

DS can support mobile devices by providing seamless integration of multiple BSSs and providing logical services necessary to handle addresses to destinations. Additionally, the DS may further include a component called a portal that acts as a bridge for connecting the wireless LAN to another network (eg, IEEE 802.X).

AP refers to an entity that enables access to DS through WM for combined non-AP STAs and also has STA functionality. Data movement between BSS and DS can be performed through AP. For example, STA2 and STA3 shown in FIG. 2 have the functionality of STAs and provide a function that allows combined non-AP STAs (STA1 and STA4) to access the DS. Additionally, since all APs basically correspond to STAs, all APs are addressable entities. The address used by the AP for communication on WM and the address used by the AP for communication on DSM are not necessarily the same. A BSS consisting of an AP and one or more STAs may be referred to as an infrastructure BSS.

Data transmitted from one of the STA(s) associated with an AP to that AP's STA address is always received on an uncontrolled port and may be processed by the IEEE 802.1X port access entity. Additionally, if the controlled port is authenticated, the transmission data (or frame) can be delivered to the DS.

In addition to the structure of the DS described above, an extended service set (ESS) may be set to provide wide coverage.

ESS means a network of arbitrary size and complexity composed of DS and BSS. ESS may correspond to a set of BSSs connected to one DS. However, ESS does not include DS. The ESS network is characterized by being seen as an IBSS in the LLC (Logical Link Control) layer. STAs included in the ESS can communicate with each other, and mobile STAs can move from one BSS to another BSS (within the same ESS) transparently to the LLC. APs included in one ESS may have the same SSID (service set identification). SSID is distinguished from BSSID, which is the identifier of the BSS.

In a wireless LAN system, nothing is assumed about the relative physical locations of BSSs, and all of the following forms are possible. BSSs can partially overlap, which is a commonly used form to provide continuous coverage. Additionally, BSSs may not be physically connected, and logically there is no limit to the distance between BSSs. Additionally, BSSs can be physically located in the same location, which can be used to provide redundancy. Additionally, one (or more than one) IBSS or ESS networks may physically exist in the same space as one (or more than one) ESS network. This is when an ad-hoc network operates in a location where an ESS network exists, when physically overlapping wireless networks are configured by different organizations, or when two or more different access and security policies are required at the same location. It may correspond to the ESS network type in, etc.

Figure 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

In order for an STA to set up a link to a network and transmit and receive data, first discover the network, perform authentication, establish association, and perform an authentication procedure for security. You have to go through etc. The link setup process can also be referred to as a session initiation process or session setup process. Additionally, the process of discovery, authentication, combination, and security setting in the link setup process may be collectively referred to as the combination process.

In step S310, the STA may perform a network discovery operation. The network discovery operation may include scanning of the STA. In other words, in order for an STA to access the network, it must find a network that it can participate in. STA must identify a compatible network before participating in a wireless network, and the process of identifying networks that exist in a specific area is called scanning.

Scanning methods include active scanning and passive scanning. Figure 3 exemplarily illustrates a network discovery operation including an active scanning process. In active scanning, the STA performing scanning transmits a probe request frame to discover which APs exist nearby while moving channels and waits for a response. The responder transmits a probe response frame in response to the probe request frame 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 BSS, the AP transmits a beacon frame, so the AP becomes a responder. In IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the number of responders is not constant. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 stores the BSS-related information included in the received probe response frame and sends it to the next channel (e.g., channel 2). You can move to the channel and perform scanning (i.e., sending and receiving probe request/response on channel 2) in the same way.

Although not shown in FIG. 3, the scanning operation may be performed in a passive scanning manner. In passive scanning, the STA performing scanning waits for a beacon frame while moving channels. A beacon frame is one of the management frames defined in IEEE 802.11, and is transmitted periodically to notify the existence of a wireless network and enable the STA performing scanning to find the wireless network and participate in the wireless network. In BSS, the AP performs the role of periodically transmitting beacon frames, and in IBSS, STAs within the IBSS take turns transmitting beacon frames. When the STA performing scanning receives a beacon frame, it stores information about the BSS included in the beacon frame and records the beacon frame information in each channel while moving to another channel. The STA that received the beacon frame may store the BSS-related information included in the received beacon frame, move to the next channel, and 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.

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

The authentication process includes the STA sending an authentication request frame to the AP, and in response, the AP sending an authentication response frame to the STA. The authentication frame used for authentication request/response corresponds to the management frame.

The authentication frame includes authentication algorithm number, authentication transaction sequence number, status code, challenge text, RSN (Robust Security Network), and finite cyclic group. Group), etc. may be included. This corresponds to some examples of information that can be included in the authentication request/response frame, and may be replaced with other information or additional information may be included.

The STA may transmit an authentication request frame to the AP. The AP may decide whether to allow authentication for the corresponding STA based on the information included in the received authentication request frame. The AP can provide the result of the authentication process to the STA through an authentication response frame.

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

For example, the binding request frame contains information related to various capabilities, beacon listen interval, service set identifier (SSID), supported rates, supported channels, RSN, and mobility. It may include information about domains, supported operating classes, TIM broadcast requests (Traffic Indication Map Broadcast requests), interworking service capabilities, etc. For example, the association response frame contains information related to various capabilities, status code, Association ID (AID), supported rate, Enhanced Distributed Channel Access (EDCA) parameter set, Received Channel Power Indicator (RCPI), and Received Signal to RSNI (Received Channel Power Indicator). Noise Indicator), mobility domain, timeout interval (e.g. association comeback time), overlapping BSS scan parameters, TIM broadcast response, Quality of Service (QoS) map, etc. can do. This corresponds to some examples of information that can be included in the combined request/response frame, and may be replaced with other information or additional information may be included.

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

The security setup process of step S340 may include the process of setting up a private key, for example, through 4-way handshaking through an Extensible Authentication Protocol over LAN (EAPOL) frame. . Additionally, the security setup process may be performed according to a security method not defined in the IEEE 802.11 standard.

Figure 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

In a wireless LAN system, the basic access mechanism of MAC (Medium Access Control) is the CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism. The CSMA/CA mechanism, also called the Distributed Coordination Function (DCF) of IEEE 802.11 MAC, basically adopts a “listen before talk” access mechanism. According to this type of access mechanism, the AP and/or STA senses the wireless channel or medium during a predetermined time period (e.g., DCF Inter-Frame Space (DIFS)) before starting transmission. As a result of sensing, CCA (Clear Channel Assessment) can be performed, and if the medium is determined to be in an idle state, frame transmission is started through the medium. When detected to be in a busy state, the AP and/or STA does not initiate its own transmission and waits by setting a delay period (e.g., a random backoff period) for medium access. By applying a random backoff period, multiple STAs are expected to attempt frame transmission after waiting for different periods of time, so collisions can be minimized.

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

An operation based on a random backoff cycle will be described with reference to FIG. 4. When a medium that was in an occupied/busy state changes to an idle state, several STAs may attempt to transmit data (or frames). As a way to minimize collisions, STAs can each select a random backoff count, wait for the corresponding slot time, and then attempt transmission. The random backoff count has a pseudo-random integer value and can be determined as one of the values ranging from 0 to CW. Here, CW is the contention window parameter value. The CW parameter is given an initial value of CWmin, but in case of transmission failure (for example, when an ACK for a transmitted frame is not received), the value can be doubled. When the CW parameter value becomes CWmax, data transmission can be attempted while maintaining the CWmax value until data transmission is successful. If data transmission is successful, it is reset to the CWmin value. The CW, CWmin and CWmax values are preferably set to 2 ⁿ -1 (n=0, 1, 2, ...).

When the random backoff process starts, the STA continues to monitor the medium while counting down backoff slots according to the determined backoff count value. When the medium is monitored as occupied, it stops counting down and waits, and when the medium becomes idle, it resumes the remaining countdown.

In the example of FIG. 4, when a packet to be transmitted arrives at the MAC of STA3, STA3 can confirm that the medium is in an idle state as much as DIFS and immediately transmit the frame. The remaining STAs monitor whether the medium is occupied/busy and wait. In the meantime, data to be transmitted may be generated in each of STA1, STA2, and STA5, and each STA waits for DIFS when the medium is monitored in an idle state, and then counts the backoff slot according to the random backoff count value selected by each STA. Download can be performed. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. That is, at the point when STA2 finishes counting the backoff and starts transmitting the frame, the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1. 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 stopped backoff count. That is, frame transmission can begin after counting down the remaining backoff slots equal to the remaining backoff time. Since the remaining backoff time of STA5 was shorter than that of STA1, STA5 starts transmitting the frame. While STA2 occupies the medium, data to be transmitted may also be generated in STA4. From the STA4's perspective, when the medium becomes idle, it can wait for DIFS, then perform a countdown according to the random backoff count value selected by the STA4, and then start transmitting the frame. The example of FIG. 4 shows a case where the remaining backoff time of STA5 coincidentally coincides with the random backoff count value of STA4, and in this case, a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 receives an ACK, and data transmission fails. In this case, STA4 and STA5 can double the CW value, then select a random backoff count value and perform a countdown. STA1 waits while the medium is occupied due to the transmission of STA4 and STA5, and when the medium becomes idle, it waits for DIFS and then starts transmitting the frame when the remaining backoff time has elapsed.

As in the example of FIG. 4, the data frame is a frame used for transmission of data forwarded to the upper layer, and can be transmitted after backoff performed after DIFS from when the medium becomes idle. Additionally, the management frame is a frame used to exchange management information that is not forwarded to the upper layer, and is transmitted after a backoff performed after an IFS such as DIFS or PIFS (Point coordination function IFS). Subtype frames of management frames include Beacon, Association request/response, re-association request/response, probe request/response, and authentication request/response. request/response), etc. A control frame is a frame used to control access to media. Subtype frames of control frames include Request-To-Send (RTS), Clear-To-Send (CTS), Acknowledgment (ACK), Power Save-Poll (PS-Poll), Block ACK (BlockAck), and Block ACK Request ( BlockACKReq), NDP announcement (null data packet announcement), trigger, etc. If the control frame is not a response frame of the previous frame, it is transmitted after backoff performed after DIFS. If it is a response frame of the previous frame, it is transmitted without backoff after SIFS (short IFS). The type and subtype of the frame can be identified by the type field and subtype field in the frame control (FC) field.

QoS (Quality of Service) STA is a backoff performed after AIFS (arbitration IFS) for the access category (AC) to which the frame belongs, that is, AIFS[i] (where i is a value determined by AC). After that, the frame can be transmitted. Here, the frame in which AIFS[i] can be used can be a data frame, a management frame, or a control frame rather than a response frame.

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

As described above, the CSMA/CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, in which the STA directly senses the medium. Virtual carrier sensing is intended to compensate for problems that may occur in medium access, such as hidden node problems. For virtual carrier sensing, the STA's MAC can use a Network Allocation Vector (NAV). NAV is a value by which an STA that is currently using the medium or has the authority to use it indicates to other STAs the time remaining until the medium becomes available. Therefore, the value set as NAV corresponds to the period during which the medium is scheduled to be used by the STA transmitting the frame, and the STA receiving the NAV value is prohibited from accessing the medium during the period. For example, the NAV can be set based on the value of the “duration” field in the MAC header of the frame.

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

In order to reduce the possibility of collision of transmissions of multiple STAs in CSMA/CA-based frame transmission operation, a mechanism using RTS/CTS frames can be applied. In the example of FIG. 5, while STA1 is transmitting, STA3 may determine that the medium is in an idle state as a result of carrier sensing. That is, STA1 may correspond to a hidden node for STA3. Alternatively, in the example of FIG. 5, it may be determined that the medium is in an idle state as a result of carrier sensing of STA3 while STA2 is transmitting. That is, STA2 may correspond to a hidden node for STA3. Before performing data transmission and reception between STA1 and STA2, through the exchange of RTS/CTS frames, an STA outside the transmission range of either STA1 or STA2, or an STA outside the carrier sensing range for transmission from STA1 or STA3, transmits data between STA1 and STA2. You can prevent attempts to occupy a channel while transmitting or receiving data.

Specifically, STA1 can determine whether a channel is being used through carrier sensing. In terms of physical carrier sensing, STA1 can determine the channel occupancy idle state based on the energy level or signal correlation detected in the channel. Additionally, in terms of virtual carrier sensing, STA1 can determine the channel occupancy status using a network allocation vector (NAV) timer.

If the channel is idle during DIFS, STA1 may transmit an RTS frame to STA2 after performing backoff. When STA2 receives an RTS frame, STA2 may transmit a CTS frame, which is a response to the RTS frame, to STA1 after SIFS.

If STA3 cannot overhear the CTS frame from STA2, but can overhear the RTS frame from STA1, STA3 uses the duration information included in the RTS frame to determine the transmission period of frames that are subsequently transmitted continuously. You can set the NAV timer for (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame). Alternatively, if STA3 cannot overhear the RTS frame from STA1 but can overhear the CTS frame from STA2, STA3 uses the duration information included in the CTS frame to transmit frames that are subsequently transmitted continuously. You can set a NAV timer for a 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 the NAV accordingly. If a new frame is received before the NAV timer expires, STA3 can update the NAV timer using the duration information included in the new frame. STA3 does not attempt channel access until the NAV timer expires.

When STA1 receives a CTS frame from STA2, STA1 can transmit a data frame to STA2 after SIFS from the time reception of the CTS frame is completed. When STA2 successfully receives a data frame, STA2 can transmit an ACK frame, which is a response to the data frame, to STA1 after SIFS. STA3 can determine whether the channel is being used through carrier sensing when the NAV timer expires. STA3 may attempt to access the channel after expiration of the NAV timer and after the contention window (CW) according to random backoff if it determines that the channel is not used by another terminal during DIFS.

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

By means of 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. For example, when a command requesting the start of transmission of the PHY layer is received from the MAC layer, the PHY layer switches to the transmission mode and configures and transmits the information (e.g., data) provided from the MAC layer in the form of a frame. there is. Additionally, when the PHY layer detects a valid preamble of a received frame, it monitors the header of the preamble and sends a command notifying the start of reception of the PHY layer to the MAC layer.

In this way, information transmission/reception in a wireless LAN system is done in the form of a frame, and for this purpose, the PHY layer protocol data unit (Physical layer Protocol Data Unit, PPDU) format is defined.

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

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

The SIG field may include various information related to PPDU transmission and reception. For example, the L-SIG field consists of 24 bits, and the L-SIG field includes a 4-bit Rate field, a 1-bit Reserved bit, a 12-bit Length field, and 1-bit parity. (Parity) field and a 6-bit Tail field. The RATE field may include information about the modulation and coding rate of data. For example, the 12-bit Length field may contain information about the length or time duration of the PPDU. For example, the value of the 12-bit Length field may be determined based on the type of PPDU. For example, for non-HT, HT, VHT, or EHT PPDU, the value of the Length field may be determined to be a multiple of 3. For example, for HE PPDU, the value of the Length field may be determined as a multiple of 3 + 1 or a multiple of 3 + 2.

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

MAC PDU is defined according to various MAC frame formats, and the basic MAC frame consists of a MAC header, frame body, and FCS (Frame Check Sequence). The MAC frame consists of a MAC PDU and can be transmitted/received through the PSDU of the data portion of the PPDU format.

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 can be set to the time for transmitting the corresponding frame, etc. Address subfields may indicate the receiver address, transmitter address, destination address, and source address of the frame, and some address subfields may be omitted. For detailed information on each subfield of the MAC header, including Sequence Control, QoS Control, and HT Control subfields, refer to the IEEE 802.11 standard document.

The null-data PPDU (NDP) format refers to a PPDU format that does not include a data field. That is, the NDP includes a PPDU preamble (i.e., L-STF, L-LTF, L-SIG field, and additionally non-legacy SIG, non-legacy STF, non-legacy LTF) in the general PPDU format, This refers to a frame format that does not include the remaining parts (i.e. data fields).

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

Various types of PPDUs were used in standards such as IEEE 802.11a/g/n/ac/ax. The basic PPDU format (IEEE 802.11a/g) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format may be referred to as the non-HT PPDU format (FIG. 7(a)).

The HT PPDU format (IEEE 802.11n) additionally includes the HT-SIG, HT-STF, and HT-LFT(s) fields to the basic PPDU format. The HT PPDU format shown in FIG. 7(b) may be referred to as an HT-mixed format. Additionally, an HT-greenfield format PPDU may be defined, which does not include L-STF, L-LTF, and L-SIG, but includes HT-GF-STF, HT-LTF1, HT-SIG, and one or more HT-LTF, Data Corresponds to a format composed of fields (not shown).

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

Examples of HE PPDU formats (IEEE 802.11ax) include Repeated L-SIG (RL-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and Packet Extension (PE) fields. is additionally included in the basic PPDU format (Figure 7(d)). Depending on detailed examples of the HE PPDU format, some fields may be excluded or their length may vary. For example, the HE-SIG-B field is included in the HE PPDU format for multiple users (MU), and the HE PPDU format for a single user (SU) does not include HE-SIG-B. Additionally, the HE trigger-based (TB) PPDU format does not include HE-SIG-B, and the length of the HE-STF field may vary to 8us. The HE ER (Extended Range) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may vary to 16us. For example, RL-SIG may be configured the same as L-SIG. The receiving STA can know that the received PPDU is a HE PPDU or an EHT PPDU, which will be described later, based on the presence of the RL-SIG.

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

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

The EHT TB PPDU in Figure 7(f) omits the EHT-SIG compared to the EHT MU PPDU. An STA that receives a trigger (e.g., trigger frame or triggered response scheduling (TRS)) for UL MU transmission may perform UL transmission based on the EHT TB PPDU format.

The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields are encoded and modulated to enable demodulation and decoding even in legacy STAs, and are stored at a fixed subcarrier frequency interval. (e.g., 312.5kHz). These may be referred to as pre-EHT modulated fields. Next, the EHT-STF, EHT-LTF, Data, and PE fields are obtained by successfully decoding the non-legacy SIG (e.g., U-SIG and/or EHT-SIG) to obtain the information contained in those fields. It may be encoded and modulated to be demodulated and decoded by the STA and mapped based on a determined subcarrier frequency interval (e.g., 78.125 kHz). These may be referred to as EHT modulated fields.

Similarly, in the HE PPDU format, the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, and HE-SIG-B fields are called pre-HE modulation fields, and HE-STF, HE -LTF, Data, and PE fields can be referred to as HE modulation fields. Additionally, in the VHT PPDU format, the L-STF, L-LTF, L-SIG, and VHT-SIG-A fields are called free VHT modulation fields, and the VHT STF, VHT-LTF, VHT-SIG-B, and Data fields are called VHT modulation fields. It can be called a field.

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

U-SIG can be configured in 20MHz units. For example, when an 80MHz PPDU is configured, the same U-SIG may be replicated in units of 20MHz. That is, the same four U-SIGs may be included within an 80MHz PPDU. When exceeding the 80 MHz bandwidth, for example, for a 160 MHz PPDU, the U-SIG of the first 80 MHz unit and the U-SIG of the second 80 MHz unit may be different.

For example, A number of uncoded bits may be transmitted through U-SIG, and the first symbol of U-SIG (e.g., U-SIG-1 symbol) is a total of A bits. Among the information, the first A-bit information (eg, 52 uncoded bits) may include a CRC field (eg, a 4-bit long field) and a tail field (eg, a 6-bit long field). The tail field can be used to terminate the trellis of the convolutional decoder and can be set to 0, for example.

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

For example, the size of the version-independent bits of U-SIG may be fixed or variable. Version-independent bits can be assigned only to the U-SIG-1 symbol, or to both the U-SIG-1 symbol and the U-SIG-2 symbol. Version-independent bits and version-dependent bits may be called various names, such as first control bit and second control bit.

For example, the version-independent bits of U-SIG may include a 3-bit physical layer version identifier (PHY version identifier), and this information identifies the PHY version (e.g., EHT, UHR, etc.) of the transmitted/received PPDU. You can instruct. The version-independent bits of U-SIG may include a 1-bit UL/DL flag field. The first value of the 1-bit UL/DL flag field is related to UL communication, and the second value of the UL/DL flag field is related to DL communication. The version-independent bits of U-SIG may include information about the length of transmission opportunity (TXOP) and information about the BSS color ID.

For example, the version-dependent bits of U-SIG may include information directly or indirectly indicating the type of PPDU (e.g., SU PPDU, MU PPDU, TB PPDU, etc.).

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

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

Preamble puncturing may mean transmission of a PPDU in which a signal does not exist in one or more frequency units among the bandwidth of the PPDU. For example, the size of the frequency unit (or resolution of preamble puncturing) may be defined as 20MHz, 40MHz, etc. For example, preamble puncturing can be applied to a PPDU bandwidth of a predetermined size or more.

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

Non-legacy SIGs such as HE-SIG-B and EHT-SIG may include common fields and user-specific fields. Common fields and user-specific fields may be coded separately.

In some cases, common fields may be omitted. For example, in a compression mode where non-OFDMA (orthogonal frequency multiple access) is applied, the common field may be omitted, and multiple STAs may receive a PPDU (e.g., the data field of the PPDU) through the same frequency band. You can. In a non-compressed mode where OFDMA is applied, multiple users may receive a PPDU (eg, a data field of the PPDU) through different frequency bands.

The number of user-specific fields may be determined based on the number of users. One user block field can include up to two user fields. Each user field may be associated with a MU-MIMO allocation or may be associated with a non-MU-MIMO allocation.

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

RU may include multiple subcarriers (or tones). RU can be used when transmitting signals to multiple STAs based on OFDMA technique. Additionally, RU may be defined even when transmitting a signal to one STA. Resources may be allocated in RU units for non-legacy STF, non-legacy LTF, and Data fields.

An RU of applicable size may be defined according to the PPDU bandwidth. RU may be defined identically or differently for the applied PPDU format (e.g., HE PPDU, EHT PPDU, UHR PPDU, etc.). For example, in the case of 80MHz PPDU, the RU placement of HE PPDU and EHT PPDU may be different. Tone-plan for RU size, number of RUs, RU location, DC (direct current) subcarrier location and number, null subcarrier location and number, guard subcarrier location and number, etc. applicable to each PPDU bandwidth. It can be called a plan. For example, a tone-plan for high bandwidth may be defined in the form of multiple iterations of a low-bandwidth tone-plan.

RUs of various sizes can be defined as 26-ton RU, 52-ton RU, 106-ton RU, 242-ton RU, 484-ton RU, 996-ton RU, 2Х996-ton RU, 3Х996-ton RU, etc. . MRU (multiple RU) is distinguished from a plurality of individual RUs and corresponds to a group of subcarriers composed of a plurality of RUs. For example, one MRU has 52+26-ton, 106+26-ton, 484+242-ton, 996+484-ton, 996+484+242-ton, 2Х996+484-ton, 3Х996-ton. , or can be defined as 3Х996+484-ton. Additionally, a plurality of RUs constituting one MRU may or may not be continuous in the frequency domain.

The specific size of the RU may be reduced or expanded. Accordingly, the specific size of each RU (i.e., the number of corresponding tones) in the present disclosure is not limiting and is illustrative. Additionally, in the present disclosure, within a predetermined bandwidth (e.g., 20, 40, 80, 160, 320 MHz, ...), the number of RUs may vary depending on the RU size.

The names of each field in the PPDU formats of FIG. 7 are exemplary, and the scope of the present disclosure is not limited by the names. Additionally, examples of the present disclosure may be applied to the PPDU format illustrated in FIG. 7 as well as to a new PPDU format in which some fields are excluded and/or some fields are added based on the PPDU formats of FIG. 7.

8 is a diagram illustrating an example format of a trigger frame to which the present disclosure can be applied.

The trigger frame may allocate resources for transmission of one or more TB PPDUs and request transmission of TB PPDUs. The trigger frame may also include other information required by the STA, which transmits the TB PPDU in response. The trigger frame may include common information and user information list fields in the frame body.

The common information field includes information commonly applied to the transmission of one or more TB PPDUs requested by a trigger frame, such as trigger type, UL length, presence or absence of a subsequent trigger frame (e.g., More TF), CS (channel It may include whether sensing is required, UL BW (bandwidth), etc. Figure 8 exemplarily shows the EHT variant common information field format.

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

Among the common information, the trigger dependent common information subfield may include information that is selectively included based on the trigger type.

A special user info field may be included within the trigger frame. The special user information field does not contain user-specific information, but includes extended common information that is not provided in the common information field.

The user information list includes zero or more user information fields. Figure 8 shows an EHT variant user information field format as an example.

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

The RU allocation subfield may indicate the size and location of the RU/MRU. To this end, the RU allocation subfield may be interpreted together with the PS160 (primary/secondary 160MHz) subfield of the user information field and the UL BW subfield of the common information field.

Relay transmission procedure

In the next-generation wireless LAN system, extremely high reliability (UHR) can be supported when transmitting signals to the STA. To support UHR, various technologies for high throughput, low latency, and extended range latency can be applied.

The present disclosure can expand wireless LAN coverage/range for reliable transmission of various IoT devices as well as outdoors, and to expand wireless LAN coverage/range, the AP can receive signals transmitted from STAs through a relay transmission procedure. You can.

Hereinafter, in order to transmit and receive signals to one or more non-AP STAs using a relay STA (i.e., to perform a relay operation), a channel measurement operation between an AP and a relay STA and/or a channel measurement operation between a relay STA and a non-AP STA Let us explain the channel measurement operation.

Figure 9 is a flowchart for explaining a method performed by a first STA, according to an embodiment of the present disclosure. In FIGS. 9 and 10, the first STA may be a non-AP STA. As an example, the first STA may be a non-AP STA operating as a relay STA, but is not limited thereto. And, the second STA may mean a non-AP STA.

The first STA may transmit a first feedback frame based on the first null data physical layer protocol data unit (NDP) received from the access point (AP) to the AP (S910).

Specifically, the first STA may receive an NDP announcement frame from the AP. The first STA may receive the NDP announcement frame and receive the first NDP based on the NDP announcement frame from the AP after SIFS. The first STA may measure/determine the channel between the AP and the first STA based on the first NDP. The first STA may transmit a first feedback frame (i.e., a first report frame) containing channel measurement/estimate information between the AP and the first STA to the AP.

The first STA may receive a request frame for measuring the first channel between the first STA and at least one second STA from the AP (S920).

Here, the request frame for first channel measurement received from the AP includes a first subfield indicating that the first channel measurement is a channel measurement for a relay operation, a second subfield indicating the bandwidth at which the first channel measurement is performed, and a first subfield indicating that the first channel measurement is a channel measurement for a relay operation. A third subfield indicating puncturing information on the bandwidth in which channel measurement is performed, a fourth subfield indicating the number of at least one second STA, and at least one containing information about each of the at least one second STA. May include user information fields.

And, each user information field corresponding to each of the first STA and the at least one second STA to perform channel measurement includes i) ID (identity) information of each of the at least one second STA, ii) at least one second STA partial bandwidth information at which each performs channel measurements, iii) subcarrier grouping and codebook size associated with the feedback generated by each of the at least one second STA, and iv) a spatial stream allocated for each of the at least one second STA. May include number and link ID.

As an example of the present disclosure, a first STA may transmit an NDP announcement frame based on a request frame received from the AP to one or more second STAs. As an example, the first STA may transmit the NDP announcement frame to one or more second STAs in a broadcast manner, but is not limited thereto.

The NDP announcement frame transmitted by the first STA may include an ID for a measurement procedure between each of the first STA and at least one second STA. The first STA may transmit an NDP announcement frame and transmit the second NDP to at least one second STA after SIFS.

As another example of the present disclosure, the first STA may transmit a response frame in response to a request frame received from the AP to the AP through the bandwidth through which the request frame was transmitted. At this time, the response frame may include a clear-to-send (CTS) frame.

The first STA may receive a second feedback frame from each of at least one second STA (S930).

Here, the second feedback frame may be based on the second NDP transmitted from the first STA to one or more second STAs. For example, the first STA may transmit the second NDP to one or more second STAs in a broadcasting manner, but is not limited thereto.

Specifically, each of the at least one second STA may perform second channel measurement between each of the first STA and the at least one second STA based on the second NDP.

The first STA may transmit a first feedback request frame to each of at least one second STA, and each of the at least one second STA may transmit a second channel measurement result (i.e., the first STA and at least one second channel measurement result) according to the first feedback request frame. A second feedback frame containing (channel information between the second STAs) may be transmitted to the first STA.

As an example, the second feedback frame transmitted by a specific STA among the at least one second STA includes at least one of the ID of the specific STA, the ID of the first STA, and an ID and link ID related to measurement between the specific STA and the first STA. It can be included.

The first STA may transmit channel information between the first STA and the at least one second STA included in the second feedback frame to the AP based on the second feedback request frame received from the AP.

Based on the first feedback frame and ii) channel information between the first STA and at least one second STA, parameters related to relay operation may be set by the AP.

The method performed by the first STA described in the example of FIG. 9 may be performed by the first device 100 of FIG. 1. For example, one or more processors 102 of the first device 100 of FIG. 1 may transmit a first feedback frame based on the first NDP received from the AP to the AP through one or more transceivers 106. One or more processors 102 may receive a request frame for first channel measurement between the first STA and at least one second STA from the AP through one or more transceivers 160. One or more processors 102 may receive a second feedback frame from each of at least one second STA through one or more transceivers 106.

Furthermore, one or more memories 104 of the first device 100 may store instructions for performing the method described in the example of FIG. 9 when executed by one or more processors 102.

Figure 10 is a flowchart for explaining a method performed by an AP, according to an embodiment of the present disclosure.

The AP may receive the first feedback frame based on the first NDP transmitted by the AP from the first STA (S1010). That is, the AP can perform a channel estimation procedure (i.e., sounding procedure) through transmission and reception of an NDP announcement frame and an NDP frame between the first STA.

The AP may transmit a request frame for measuring the first channel between the first STA and at least one second STA to the first STA (S1020).

That is, after completing the sounding procedure between the first STAs, the AP may transmit a request frame requesting to perform channel measurement between the first STA and at least one second STA to the first STA.

The AP may receive channel information between each of the first STA and at least one second STA from the first STA (S1030).

The second feedback frame containing channel information between each of the first STA and at least one second STA may be based on the second NDP transmitted from the first STA to one or more second STAs.

That is, each of the at least one second STA acquires channel information (i.e., measurement result) between the first STA and each of the at least one second STA through the second NDP, and transmits the obtained channel information to the first STA. You can. The AP may transmit a second feedback request frame requesting the channel information to the first STA. The AP may receive channel information between the first STA and each of the at least one second STA from the first STA based on the second feedback request frame.

The AP may set parameters related to relay operation based on i) the first feedback frame and ii) channel information between the first STA and at least one second STA. The AP may perform a relay operation based on parameters related to the relay operation.

The method performed by the second STA described in the example of FIG. 10 may be performed by the second device 200 of FIG. 1. For example, one or more processors 202 of the second device 200 of FIG. 1 receive a first feedback frame based on the first NDP transmitted by the AP from the first station (STA) through one or more transceivers 206. You can receive it. One or more processors 102 may transmit a request frame for first channel measurement between the first STA and at least one second STA to the first STA through one or more transceivers 206. One or more processors 102 may receive channel information between each of the first STA and at least one second STA from the first STA through one or more transceivers 206.

Furthermore, one or more memories 204 of the second device 200 may store instructions for performing the method described in the example of FIG. 10 when executed by one or more processors 202.

Hereinafter, channel measurement operations related to relay operations and frame configurations related thereto will be described in detail.

Regardless of the location of the STA within the BSS, the next-generation wireless LAN system uses a relay transmission procedure to transmit stable signals (i.e., reliable signals), increase coverage for signal transmission, and eliminate holes where signals cannot reach. Signal transmission and reception can be supported/applied.

In order to reduce the complexity of implementing the relay transmission procedure, the relay transmission procedure controlled by the AP in the next generation wireless LAN system is described. However, this is only an example, and the description of the present disclosure described below can be applied to all relay transmission procedures as well as the relay transmission procedure controlled by the AP.

In this disclosure, a relay STA controlled by an AP is referred to as an AP controlled relay STA (hereinafter ACRS).

ACRS can perform relay transmission of data received from AP within the BSS. At this time, control of ACRS for the relay transmission procedure may be performed by the AP.

That is, ACRS can transmit signals received from the AP to an end-user/STA based on control information received from the AP, or transmit signals received from multiple non-AP STAs to the AP.

ACRS may refer to an independent relay device that only performs the relay transmission procedure and/or a non-AP STA that supports the relay transmission procedure.

In the next-generation wireless LAN system, as shown in FIG. 11, a signal can be transmitted to one or more non-AP STAs located within an extended range or a signal can be received from a non-AP STA through a relay operation.

As shown in FIG. 11, relay operation may be performed using two links (eg, a link between an AP and a relay STA and a link between a relay STA and a non-AP STA). At this time, since the two links have different channel states, it is necessary to determine channel information for the two links in order to efficiently perform a relay operation using the two links.

Therefore, in this disclosure, in order to efficiently perform relay transmission using two links, a procedure for channel estimation for two links and signaling related thereto are proposed.

Hereinafter, the link between the AP and the relay STA will be named ATRL (AP to Relay STA link), and the link between the relay STA and the non-AP STA will be named RTNASL (Relay STA to non-AP STA link).

Example 1

For relay operation, the AP can initiate channel measurement for ATRL and RTNASL, and Example 1 relates to channel measurement for both links.

The AP may transmit an NDP announcement frame to perform channel measurements for ATRL and RTNASL. As an example of the present disclosure, as shown in FIG. 12, the STA information field format of the NDP announcement frame may be configured.

As shown in FIG. 12, the NDP announcement frame may include indication information to indicate measurement for relay operation. As an example, the indication information may be set in the 20th bit (B19) of the STA information field of the NDP announcement frame. For example, B19 of the STA information field of the NDP announcement frame may be set as a relay measurement subfield. If the relay measurement subfield value is set to 1, this may indicate channel measurement for relay operation.

The STA information field for the relay STA may be placed at the front of the STA information list field of the NDP announcement frame, but is not limited to this.

Among the STA information list fields of the NDP announcement frame, the STA information field for the relay STA (i.e., the STA information field whose AID is set to the STA ID of the relay STA) may include the number of STAs for which the relay STA will perform channel measurement. The number of STAs for which the relay STA will perform channel measurement is determined through at least one of the 30th bit (B29) to the 32nd bit (B31) of the STA information field for the relay STA (i.e., the number of STAs for relay subfield). can be instructed.

As an example, when the number of STAs for which a relay STA will perform channel measurement (i.e., the number of STAs subfield for relay) is set to 3 bits, whether to measure channels between up to 8 STAs may be indicated, and the relay STA may If the number of STAs to perform channel measurement is set to 2 bits, whether to measure channels between up to 4 STAs may be indicated.

The relay STA can check the number of STAs that need to perform channel measurement/estimation for relay operation through the number of STAs subfield. Additionally, the relay STA can check the number of STA information fields following the STA information field for the relay STA through the number of STAs subfield for relay.

In the STA information field of the NDP announcement frame, the remaining subfields, excluding the relay measurement subfield and the number of STAs for relay subfield, may be set differently or the same when channel estimation for ATRL and RTNASL.

When the STA information field includes an ID for a non-AP STA performing a relay operation, the 30th bit (B29) to the 32nd bit (B31) of the STA information field may be reserved.

The relay STA that has received the NDP announcement frame shown in FIG. 12 can confirm that channel measurement is performed through the relay measurement subfield included in the NDP announcement frame.

Example 1-1

Example 1-1 relates to a channel estimation/measurement procedure for ATRL and RTNASL using an NDP announcement frame configured as described in Example 1. Figure 13 (a) shows a channel measurement procedure for ATRL and NRNASL, according to an embodiment of the present disclosure.

First, as shown in (a) of FIG. 13, the AP may transmit an NDP announcement frame configured as described in Embodiment 1 to the relay STA for channel measurement for both ATRL and RTNASL.

The relay STA can confirm that a channel measurement operation for relay operation is performed by receiving the NDP announcement frame. Additionally, the relay STA can confirm information about the STA(s) that need to perform channel estimation/measurement through an NDP announcement frame.

The sounding dialog token number included in the NDP announcement frame can be used as identification information (eg, measurement ID (MID)) for the measurement performed based on the NDP announcement frame. For example, MID can be used as identification information for channel measurement between AP and relay STA.

The AP may transmit an NDP announcement frame and transmit the NDP frame to the relay STA after SIFS. The relay STA that received the NDP from the AP can configure the NDP announcement frame using the information about the non-AP STA included in the NDP announcement frame received from the AP.

The relay STA may transmit the configured NDP announcement frame to the corresponding STA(s) (i.e., STA(s) related to the relay operation indicated/set through the NDP announcement frame transmitted by the AP).

The sounding dialog token included in the NDP announcement frame transmitted by the relay STA can be used as identification information (i.e., measurement identifier (MID)) for the measurement performed based on the NDP announcement frame. The MID can be used as identification information for channel measurement between relay STAs and non-AP STAs.

The relay STA may transmit an NDP announcement frame and transmit the NDP frame to the non-AP STA(s) after SIFS.

Non-AP STA(s) that have received the NDP frame transmitted by the relay STA can form/generate channel measurement information using the channel measurement parameters identified through the received NDP announcement frame.

The relay STA may transmit a feedback request frame to the non-AP STA(s) to request transmission of channel information estimated by the non-AP STA(s). At this time, the feedback request frame may be transmitted from the relay STA to the non-AP STA(s) after a SIFS or specific IFS (eg, AIFS, DIFS, etc.) interval after transmission of the NDP frame. Here, the feedback request frame may be configured as a trigger frame.

A non-AP STA that receives a feedback request frame from a relay STA can report/transmit the measured channel information to the relay STA through a measurement report frame. The measurement report frame may include a report field, and the report field includes TX ID, RX ID, and measurement information to distinguish channel information for each non-AP STA that measured the channel when estimating channels between multiple non-AP STAs and relay STAs. May include ID, etc.

Here, the TX ID may be set to the STA that transmitted the NDP (i.e., the STA ID or AID of the relay STA). The RX ID may be set to the STA that received the NDP (i.e., the STA ID or AID for the non-AP STA that performed channel measurement). However, this is only one embodiment, and each of the TX ID and RX ID may be set opposite to each other. The measurement ID can be set to the sounding dialog token number transmitted through the NDP announcement frame.

Additionally or alternatively, for link identification, the reporting field may include a link ID, which may be assigned by the AP.

In Figure 13 (a), an embodiment is shown in which a relay STA transmits a single request frame to a non-AP STA(s), and the non-AP STA(s) transmits feedback accordingly to the relay STA. However, this is only one embodiment, and the request frame transmitted by the relay STA and the feedback frame transmitted by the non-AP STA may be paired with each other and transmitted and received sequentially.

A relay STA that receives a feedback frame from a non-AP STA(s) through a feedback request frame may receive a feedback request frame from the AP. The relay STA may transmit measured channel information to the AP according to the feedback request frame transmitted by the AP.

Here, the measured channel information transmitted by the relay STA may include ATRL channel measurement information and RTNASL channel measurement information (eg, channel information received from one or more non-AP STAs).

Each of the ATRL channel measurement information and/or RTNASL channel measurement information may include TX ID, RX ID, measurement ID, link ID, etc. The AP can determine which link or channel information between which non-AP STA and relay STA each channel information is through TX ID, RX ID, measurement ID, and link ID.

Additionally, each of the ATRL channel measurement information and/or RTNASL channel measurement information may include received signal-to-ratio (SNR) information. The received SNR information may be set to an average value per link or NSS (number of spatial stream).

The AP can evaluate channel information for ATRL and RTNASL through feedback information received from the relay STA, and can set parameters for each link for efficient transmission on each link. That is, during relay operation, the AP can transmit signals by applying different MCS, NSSS, etc. for each link related to each non-AP STA.

Example 1-2

Examples 1-2 relate to different approaches to channel estimation/measurement procedures for ATRL and RTNASL. Figure 13(b) shows a channel measurement procedure for ATRL and NRNASL, according to an embodiment of the present disclosure.

Channel measurement for ATRL can be performed through a sounding procedure in a basic wireless LAN system. That is, there is no need for additional signaling design for channel measurement for ATRL, and signaling overhead can be reduced.

As shown in (b) of FIG. 13, the AP can perform channel measurement for RTNASL by requesting channel measurement for RTNASL to the relay STA.

Specifically, as channel estimation between the AP and the relay STA is completed, the AP receives channel information from the relay STA, and after SIFS, RTNASL may be performed by the AP transmitting a channel measurement request frame/trigger frame to the relay STA.

As an example of the present disclosure, the RTNASL measurement request frame transmitted from the AP to the relay STA may include a channel measurement request field, a BW field, a puncturing information field, a number of user/non-AP STA field, and a user information field.

The channel measurement request field may include information indicating a request for channel estimation with a non-AP STA for relay operation. The channel measurement request field may consist of 1 bit. If the channel measurement request field value is set to 1, this may indicate a channel measurement request.

The BW field may indicate the bandwidth used for channel measurement. As an example, the BW field may consist of 3 bits and may represent one of 20, 40, 80, 160, or 320 MHz. The puncturing information field may indicate information about the channel being punctured within the bandwidth.

The Number of Non-AP STAs/Users field may indicate the number of non-AP STAs that need to perform channel estimation. As an example, the number of non-AP STAs/users field may consist of 3 bits and can support up to 8 non-AP STAs/users.

The user information field may include information about the non-AP STA for which the relay STA must perform channel measurement. As an example, the user information field may be configured based on the STA information field of the NDP announcement frame.

For example, the user information field may include AID information, partial BW information, Ng (i.e., subcarrier grouping), codebook size, NSS, and link ID. Here, the AID information may include the STA ID of the non-AP STA. Partial BW information may include information about the partial bandwidth over which measurements must be performed. Ng represents the subcarrier grouping used for feedback and can indicate one of 1, 4, 8, 16, etc. The codebook size may include information about the size of the matrix constituting the feedback. NSS may indicate the number of spatial streams allocated to a non-AP STA. A link ID (e.g., 3 bits) may be assigned by the AP as an ID to distinguish channel measurement.

The relay STA that has received the request frame transmitted by the AP i) transmits a response frame to the request frame to the AP and/or ii) sends an NDP announcement frame constructed based on information obtained through the request frame to the non-AP STA. It can be sent to (s).

As an example of the present disclosure, a response frame to the request frame transmitted by a relay STA may include a CTS frame, and the response frame may be transmitted through the bandwidth through which the request frame is received.

The procedure for transmitting and receiving various frames for channel estimation between relay STAs and non-AP STAs is the same as the channel measurement/estimation procedure between relay STAs and non-AP STAs described in Example 1-1, so redundant description will be omitted. .

A relay STA that has identified channel information for each link through channel estimation between non-AP STA(s) can receive a feedback request frame from the AP requesting transmission of channel information for each link. After this, the relay STA can transmit the information received from the non-AP STA(s) to the AP through a feedback frame.

Example 1-3

Example 1-3 is a procedure for performing channel estimation using channel reciprocity between relay STAs and non-AP STAs in order to reduce signaling overhead and delay for channel measurement (i.e., (a in FIG. 14) ) relates to the procedure shown in ).

As shown in (a) of FIG. 14, channel measurement between relay STAs and non-AP STAs can be performed continuously in each of the DL and UL directions. That is, in order to obtain all information about the transmission and reception channels, a bi-directional channel measurement operation can be performed.

The AP may transmit a request frame requesting RTNASL channel measurement to the relay STA for channel estimation for RTNASL. The configuration of the request frame transmitted by the AP may be the same as the configuration of the request frame transmitted by the AP described in Embodiment 1-2, so redundant description will be omitted.

The relay STA that received the request frame i) transmits a response frame to the request frame to the AP and/or ii) triggers to request NDP transmission from non-AP STAs through information included in the request frame. A frame transmission operation can be performed. The STA information field of the trigger frame transmitted by the relay STA may be configured using information received through the request frame.

A non-AP STA(s) that has received a trigger frame transmitted by a relay STA can check the allocated subchannel or RU using the information in the trigger frame. Non-AP STA(s) may transmit NDP to the relay STA through the allocated subchannel or RU.

Channel measurement operations between relay STAs and non-AP STA(s) may be performed simultaneously or sequentially. That is, the relay STA may request NDP transmission (simultaneously) to a plurality of STAs through a trigger frame, or may request NDP transmission by transmitting a trigger frame to an individual STA.

A relay STA that receives an NDP frame transmitted by a non-AP STA can estimate the channel between the STAs using the NDP frame. At this time, the relay STA can configure feedback information based on channel estimation between the corresponding STAs using information in the request frame received from the AP.

The relay STA may receive a feedback request frame from the AP. The relay STA may report the measured channel information to the AP based on the NDP received from each non-AP STA(s). At this time, the feedback frame transmitted by the relay STA may include an STA ID, TX ID, or link ID for each channel information to indicate which STA the measured channel information is. That is, the relay STA can configure feedback information by setting the ID of the STA associated with the channel for each channel.

Example 1-4

Examples 1-4 relate to a procedure for performing channel estimation through directional measurement (i.e., the procedure shown in (b) of FIG. 14).

As shown in (b) of FIG. 14, channel measurement between relay STAs and non-AP STAs can be performed continuously for each of the DL and UL directions. That is, a channel measurement operation can be performed in both directions to obtain information about the transmission and reception channels.

For channel estimation for RTNASL, the AP may transmit a request frame requesting RNTASL channel estimation to the relay STA. Since the configuration of the request frame transmitted by the AP to the relay STA is the same as the configuration of the request frame transmitted by the AP to the relay STA in Embodiment 1-2, redundant description will be omitted. The relay STA may transmit a response frame to the AP in response to the request frame transmitted from the AP.

The relay STA may transmit an NDP announcement frame to the STA(s) in order to perform channel estimation with the STA(s) using the received request information. And, the relay STA may transmit an NDP frame to the STA(s).

The NDP announcement frame may include a special STA information field for transmitting common information. Special user information fields may be defined using one of the reserved AIDs. As an example, the special user information field may include Ng (ie, information about subcarrier grouping).

The NDP announcement frame may include information about the NDP transmitted by the relay STA to the non-AP STA(s) and information about the NDP transmitted by the non-AP STA. As an example, the STA information field included in the NDP announcement frame includes AID (e.g., AID or STA-ID of a non-AP STA), RTNASL channel measurement indication information, partial BW information, Ng information, codebook size information, and RTNAS NSTS (i.e. , NSTS (number of space-time streams) value for transmission from a relay STA to a non-AP STA), and NASTR NSTA information (i.e., NSTS value for transmission from a non-AP STA to a relay STA). .

Here, the RTNASL channel indication information may indicate that channel estimation for RTNASL channel measurement is performed in both directions and may consist of 1 bit.

The NDP announcement frame transmitted by the relay STA and the non-AP STA(s) that received the NDP frame may transmit the NDP to the relay STA using the received announcement frame information.

The relay STA that receives the NDP from the non-AP STA may transmit a feedback request frame to the non-AP STA. Non-AP STA may receive a feedback request and transmit the measured channel information after SIFS to the relay STA.

The relay STA can perform a channel measurement procedure for RTNASL for each non-AP STA (i.e., one-to-one).

As described above, a non-AP STA that performs two-way channel measurement may mean an STA that has the capability for two-way channel measurement. A Non-AP STA may indicate that it has the capability for two-way channel measurement when performing an association procedure with an AP.

The embodiments described above are those in which the components and features of the present disclosure are combined in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features. Additionally, it is also possible to configure an embodiment of the present disclosure by combining some components and/or features. The order of operations described in embodiments of the present disclosure may be changed. Some features or features of one embodiment may be included in other embodiments or may be replaced with corresponding features or features of other embodiments. It is obvious that claims that do not have an explicit reference relationship in the patent claims can be combined to form an embodiment or included as a new claim through amendment after filing.

It is obvious to those skilled in the art that the present disclosure can be embodied in other specific forms without departing from the essential features of the present disclosure. Accordingly, the above detailed description should not be construed as restrictive in all respects and should be considered illustrative. The scope of this disclosure should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of this disclosure are included in the scope of this disclosure.

The scope of the present disclosure is software or machine-executable instructions (e.g., operating system, application, firmware, program, etc.) that cause operations according to the methods of various embodiments to be executed on a device or computer, and such software or It includes non-transitory computer-readable medium in which instructions, etc. are stored and can be executed on a device or computer. Instructions that may be used to program a processing system to perform the features described in this disclosure may be stored on/in a storage medium or computer-readable storage medium and may be viewed using a computer program product including such storage medium. Features described in the disclosure may be implemented. Storage media may include, but are not limited to, high-speed random access memory such as DRAM, SRAM, DDR RAM, or other random access solid state memory devices, one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or It may include non-volatile memory, such as other non-volatile solid state storage devices. Memory optionally includes one or more storage devices located remotely from the processor(s). The memory, or alternatively the non-volatile memory device(s) within the memory, includes a non-transitory computer readable storage medium. Features described in this disclosure may be stored on any one of a machine-readable medium to control the hardware of a processing system and to enable the processing system to interact with other mechanisms utilizing results according to embodiments of the present disclosure. May be integrated into software and/or firmware. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments/containers.

The method proposed in this disclosure has been described focusing on examples applied to an IEEE 802.11-based system, but it can be applied to various wireless LAN or wireless communication systems in addition to the IEEE 802.11-based system.

Claims (15)

In a method performed by a first station (STA) in a wireless LAN system, the method includes: Transmitting a first feedback frame based on a first null data physical layer protocol data unit (NDP) received from an access point (AP) to the AP; Receiving a request frame for first channel measurement between the first STA and one or more second STAs from the AP; and Receiving a second feedback frame from each of the one or more second STAs, The second feedback frame is based on a second NDP transmitted from the first STA to the one or more second STAs. According to paragraph 1, The request frame includes a first subfield indicating that the first channel measurement is a channel measurement for a relay operation, a second subfield indicating a bandwidth over which the first channel measurement is performed, and a bandwidth over which the first channel measurement is performed. A third subfield indicating puncturing information, a fourth subfield indicating the number of the one or more second STAs, and at least one user information field containing information about each of the one or more second STAs. , method. According to paragraph 2, Each of the at least one user information field includes identity (ID) information of each of the one or more second STAs, partial bandwidth information on which each of the one or more second STAs performs channel measurement, and information generated by each of the one or more second STAs. Subcarrier grouping and codebook size associated with feedback, and a link ID and number of spatial streams allocated for each of the one or more second STAs. According to paragraph 2, An NDP announcement frame based on the request frame is transmitted from the first STA to the one or more second STAs, The NDP announcement frame is transmitted and the second NDP is transmitted from the first STA to the one or more second STAs after a short inter frame space (SIFS). According to paragraph 2, A response frame to the request frame is transmitted from the first STA to the AP through the bandwidth through which the request frame was transmitted, The response frame is a clear-to-send (CTS) frame. According to paragraph 1, The second feedback frame is transmitted based on a first feedback request frame transmitted from the first STA to each of the one or more second STAs. According to paragraph 1, The second feedback frame transmitted by a specific STA among the one or more second STAs includes at least an ID of the specific STA, an ID of the first STA, and an ID and link ID related to measurement between the specific STA and the first STA. Containing one, method. According to paragraph 1, Channel information between the first STA and the one or more second STAs included in the second feedback frame is transmitted from the first STA to the AP based on a second feedback request frame received from the AP. According to clause 4, The NDP announcement frame transmitted by the first STA includes an ID for a measurement procedure between each of the first STA and the one or more second STAs. According to clause 8, Based on i) the first feedback frame and ii) channel information between the first STA and the one or more second STAs, parameters related to relay operation are set by the AP. In a first station (STA) operating in a wireless LAN system, the first STA: One or more transceivers; and Comprising one or more processors connected to the one or more transceivers, The one or more processors: transmitting a first feedback frame based on a first null data physical layer protocol data unit (NDP) received from an access point (AP) to the AP through the one or more transceivers; Receive a request frame for first channel measurement between the first STA and one or more second STAs from the AP through the one or more transceivers; and Configured to receive a second feedback frame from each of the one or more second STAs through the one or more transceivers, The second feedback frame is based on a second NDP transmitted from the first STA to the one or more second STAs. In a method performed by an access point (AP) in a wireless LAN system, the method includes: Receiving a first feedback frame based on a first null data physical layer protocol data unit (NDP) transmitted by the AP from a first station (STA); Transmitting a request frame for first channel measurement between the first STA and one or more second STAs to the first STA; and Receiving channel information between the first STA and each of the one or more second STAs from the first STA, A second feedback frame containing channel information between each of the first STA and the one or more second STAs is based on a second NDP transmitted from the first STA to the one or more second STAs. In an access point (AP) operating in a wireless LAN system, the AP: One or more transceivers; and Comprising one or more processors connected to the one or more transceivers, The one or more processors: Receive a first feedback frame based on a first null data physical layer protocol data unit (NDP) transmitted by the AP from a first station (STA) through the one or more transceivers; transmitting a request frame for first channel measurement between the first STA and one or more second STAs to the first STA through the one or more transceivers; and Configured to receive channel information between each of the first STA and the one or more second STAs from the first STA through the one or more transceivers, The second feedback frame containing channel information between each of the first STA and the one or more second STAs is based on a second NDP transmitted from the first STA to the one or more second STAs. In a processing device configured to control a first station (STA) operating in a wireless LAN system, the processing device: One or more processors; and one or more computer memories operably coupled to the one or more processors and storing instructions that, upon execution by the one or more processors, perform operations; The above operations are: Transmitting a first feedback frame based on a first null data physical layer protocol data unit (NDP) received from an access point (AP) to the AP; Receiving a request frame for measuring a first channel between the first STA and one or more second STAs from the AP; and Comprising the operation of receiving a second feedback frame from each of the one or more second STAs, The second feedback frame is based on a second NDP transmitted from the first STA to the one or more second STAs. One or more non-transitory computer readable media storing one or more instructions, The one or more instructions are executed by one or more processors, so that a device operating in a wireless LAN system: transmit a first feedback frame based on a first null data physical layer protocol data unit (NDP) received from an access point (AP) to the AP; Receive a request frame for first channel measurement between the first STA and one or more second STAs from the AP; and Controlled to receive a second feedback frame from each of the one or more second STAs, The second feedback frame is based on a second NDP transmitted from the first STA to the one or more second STAs.

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