METHOD AND DEVICE FOR PERFORMING SENSING PROCEDURE IN WIRELESS LAN SYSTEM

Abstract

A method and a device for performing a sensing procedure in a WLAN system are disclosed. A method of performing a sensing procedure by a first STA in a wireless LAN system comprises the steps of: receiving, from an AP, a first polling frame including first information related to participation in a first type of measurement for the first STA; transmitting, to the AP, a first response frame for the first polling frame; and receiving, from the AP, a second polling frame including the first information, on the basis of a second response frame not being transmitted to the AP from a second STA from among a plurality of STAs including the first STA, wherein the first polling frame may include second information related to participation in a second type of measurement for the second STA, and the second polling frame may not include the second information.

Description

TECHNICAL FIELD

The present disclosure relates to a method and device for performing communication in a wireless local area network (WLAN) system, and more specifically, to a method and device for performing a sensing procedure in a next-generation wireless LAN system.

BACKGROUND

New technologies for improving transmission rates, increasing bandwidth, improving reliability, reducing errors, and reducing latency have been introduced for a wireless LAN (WLAN). Among WLAN technologies, an Institute of Electrical and Electronics Engineers (IEEE) 802.11 series standard may be referred to as Wi-Fi. For example, technologies recently introduced to WLAN include enhancements for Very High-Throughput (VHT) of the 802.11ac standard, and enhancements for High Efficiency (HE) of the IEEE 802.11ax standard.

Improvement technologies for providing sensing for devices using wireless LAN signals are being discussed. For example, in IEEE 802.11 task group (TG) bf, standard technology is being developed to perform sensing of objects (e.g., people, objects, etc.) based on channel estimation using wireless LAN signals between devices operating in the frequency band below 7 GHz. Object sensing based on wireless LAN signals has the advantage of utilizing existing frequency bands and has a lower possibility of privacy infringement compared to existing sensing technologies. As the frequency range used in wireless LAN technology increases, precise sensing information can be obtained, and technologies for reducing power consumption to efficiently support precise sensing procedures are also being researched.

SUMMARY

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

An additional technical problem of the present disclosure is to provide a method and device for performing sensing measurement by transmitting and receiving polling frames in a wireless LAN system.

An additional technical problem of the present disclosure is to provide a method and apparatus for performing a recovery mechanism when a failure issue occurs in the polling phase.

The technical objects to be achieved by the present disclosure are not limited to the above-described technical objects, and other technical objects which are not described herein will be clearly understood by those skilled in the pertinent art from the following description.

A method of performing a sensing procedure by a first station (STA) in a wireless LAN system according to an aspect of the present disclosure may include: receiving, from an access point (AP), a first polling frame including first information related to participation in a first type of measurement for the first STA; transmitting, to the AP, a first response frame for the first polling frame; and based on a second response frame for the first polling frame being not transmitted to the AP from a second STA among a plurality of STAs including the first STA, receiving a second polling frame including the first information from the AP, and the first polling frame may include second information related to participation in a second type of measurement for the second STA, and the second polling frame does not include the second information.

A method of performing a sensing procedure by an access point (AP) in a wireless LAN system according to an additional aspect of the present disclosure may include transmitting a first polling frame to a plurality of stations (STAs); receiving a first response frame for the first polling frame from a first STA among the plurality of STAs; and based on a second response frame for the first polling frame being not received from a second STA among the plurality of STAs, transmitting a second polling frame to at least one STA including the first STA, and the first polling frame may include second information related to participation in a second type of measurement for the second STA, and the second polling frame does not include the second information.

According to the present disclosure, a method and device for performing a sensing procedure in a wireless LAN system may be provided.

According to the present disclosure, a method and device for performing sensing measurement by transmitting and receiving a polling frame in a wireless LAN system may be provided.

According to the present disclosure, a method and apparatus may be provided for performing a recovery mechanism when a failure issue occurs in the polling phase.

Effects achievable by the present disclosure are not limited to the above-described effects, and other effects which are not described herein may be clearly understood by those skilled in the pertinent art from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Accompanying drawings included as part of detailed description for understanding the present disclosure provide embodiments of the present disclosure and describe technical features of the present disclosure with detailed description.

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

FIG. 2 is a diagram illustrating an exemplary structure of a WLAN system to which the present disclosure may be applied.

FIG. 3 is a diagram for describing a link setup process to which the present disclosure may be applied.

FIG. 4 is a diagram for describing a backoff process to which the present disclosure may be applied.

FIG. 5 is a diagram for describing a frame transmission operation based on CSMA/CA to which the present disclosure may be applied.

FIG. 6 is a diagram for describing an example of a frame structure used in a WLAN system to which the present disclosure may be applied.

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

FIGS. 8 to 10 are diagrams for describing examples of resource units of a WLAN system to which the present disclosure may be applied.

FIG. 11 illustrates an example structure of a HE-SIG-B field.

FIG. 12 is a diagram for describing a MU-MIMO method in which a plurality of users/STAs are allocated to one RU.

FIG. 13 illustrates an example of a PPDU format to which the present disclosure may be applied.

FIG. 14 illustrates an example format of a trigger frame to which the present disclosure may be applied.

FIG. 15 is a diagram for describing the HE Non-TB/TB sounding procedure to which the present disclosure may be applied.

FIG. 16 is a diagram for describing a wireless LAN sensing procedure to which the present disclosure can be applied.

FIG. 17 shows an example of a polling phase and a sounding phase to which the present disclosure may be applied.

FIG. 18 is a diagram illustrating a process in which a first STA performs a sensing procedure, according to an embodiment of the present disclosure.

FIG. 19 is a diagram illustrating a process in which a second STA performs a sensing procedure, according to an embodiment of the present disclosure.

FIG. 20 shows an example of a case where the participation field of DL/UL sounding and the order field of DL/UL sounding are combined.

FIG. 21 is a diagram to describe the process in which a failure issue occurs in the polling phase.

FIG. 22 is a diagram illustrating the operation of the AP/sensing STA when a failure issue occurs in the polling phase, according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, embodiments according to the present disclosure will be described in detail by referring to accompanying drawings. Detailed description to be disclosed with accompanying drawings is to describe exemplary embodiments of the present disclosure and is not to represent the only embodiment that the present disclosure may be implemented. The following detailed description includes specific details to provide complete understanding of the present disclosure. However, those skilled in the pertinent art knows that the present disclosure may be implemented without such specific details.

In some cases, known structures and devices may be omitted or may be shown in a form of a block diagram based on a core function of each structure and device in order to prevent a concept of the present disclosure from being ambiguous.

In the present disclosure, when an element is referred to as being “connected”, “combined” or “linked” to another element, it may include an indirect connection relation that yet another element presents therebetween as well as a direct connection relation. In addition, in the present disclosure, a term, “include” or “have”, specifies the presence of a mentioned feature, step, operation, component and/or element, but it does not exclude the presence or addition of one or more other features, stages, operations, components, elements and/or their groups.

In the present disclosure, a term such as “first”, “second”, etc. is used only to distinguish one element from other element and is not used to limit elements, and unless otherwise specified, it does not limit an order or importance, etc. between elements. Accordingly, within a scope of the present disclosure, a first element in an embodiment may be referred to as a second element in another embodiment and likewise, a second element in an embodiment may be referred to as a first element in another embodiment.

A term used in the present disclosure is to describe a specific embodiment, and is not to limit a claim. As used in a described and attached claim of an embodiment, a singular form is intended to include a plural form, unless the context clearly indicates otherwise. A term used in the present disclosure, “and/or”, may refer to one of related enumerated items or it means that it refers to and includes any and all possible combinations of two or more of them. In addition, “/” between words in the present disclosure has the same meaning as “and/or”, unless otherwise described.

Examples of the present disclosure may be applied to various wireless communication systems. For example, examples of the present disclosure may be applied to a wireless LAN system. For example, examples of the present disclosure may be applied to an IEEE 802.11a/g/n/ac/ax standards-based wireless LAN. Furthermore, examples of the present disclosure may be applied to a wireless LAN based on the newly proposed IEEE 802.11be (or EHT) standard. Examples of the present disclosure may be applied to an IEEE 802.11be Release-2 standard-based wireless LAN corresponding to an additional enhancement technology of the IEEE 802.11be Release-1 standard. Additionally, examples of the present disclosure may be applied to a next-generation standards-based wireless LAN after IEEE 802.11be. Further, examples of this disclosure may be applied to a cellular wireless communication system. For example, it may be applied to a cellular wireless communication system based on Long Term Evolution (LTE)-based technology and 5G New Radio (NR)-based technology of the 3rd Generation Partnership Project (3GPP) standard.

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

FIG. 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 may be replaced with various terms such as a terminal, a wireless device, a Wireless Transmit Receive Unit (WTRU), an User Equipment (UE), a Mobile Station (MS), an user terminal (UT), a Mobile Subscriber Station (MSS), a Mobile Subscriber Unit (MSU), a subscriber station (SS), an advanced mobile station (AMS), a wireless terminal (WT), or simply user, etc. In addition, the first device 100 and the second device 200 include an access point (AP), a base station (BS), a fixed station, a Node B, a base transceiver system (BTS), a network, It may be replaced with various terms such as an Artificial Intelligence (AI) system, a road side unit (RSU), a repeater, a router, a relay, and a gateway.

The devices 100 and 200 illustrated in FIG. 1 may be referred to as stations (STAs). 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 functions of an AP and/or a non-AP. When the STAs 110 and 200 perform an AP function, they may be simply referred to as APs, and when the STAs 110 and 200 perform non-AP functions, they may be simply referred to as STAs. In addition, in the present disclosure, an AP may also be indicated as an AP STA.

Referring to FIG. 1, the first device 100 and the second device 200 may transmit and receive radio signals through various wireless LAN technologies (e.g., IEEE 802.11 series). The first device 100 and the second device 200 may include an interface for a medium access control (MAC) layer and a physical layer (PHY) conforming to the IEEE 802.11 standard.

In addition, the first device 100 and the second device 200 may additionally support various communication standards (e.g., 3GPP LTE series, 5G NR series standards, etc.) technologies other than wireless LAN technology. In addition, the device of the present disclosure may be implemented in various devices such as a mobile phone, a vehicle, a personal computer, augmented reality (AR) equipment, and virtual reality (VR) equipment, etc. In addition, the STA of the present specification may support various communication services such as a voice call, a video call, data communication, autonomous-driving, machine-type communication (MTC), machine-to-machine (M2M), device-to-device (D2D), IoT (Internet-of-Things), etc.

A first device 100 may include one or more processors 102 and one or more memories 104 and may additionally include one or more transceivers 106 and/or one or more antennas 108. A processor 102 may control a memory 104 and/or a transceiver 106 and may be configured to implement description, functions, procedures, proposals, methods and/or operation flow charts disclosed in the present disclosure. For example, a processor 102 may transmit a wireless signal including first information/signal through a transceiver 106 after generating first information/signal by processing information in a memory 104. In addition, a processor 102 may receive a wireless signal including second information/signal through a transceiver 106 and then store information obtained by signal processing of second information/signal in a memory 104. A memory 104 may be connected to a processor 102 and may store a variety of information related to an operation of a processor 102. For example, a memory 104 may store a software code including instructions for performing all or part of processes controlled by a processor 102 or for performing description, functions, procedures, proposals, methods and/or operation flow charts disclosed in the present disclosure. Here, a processor 102 and a memory 104 may be part of a communication modem/circuit/chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series). A transceiver 106 may be connected to a processor 102 and may transmit and/or receive a wireless signal through one or more antennas 108. A transceiver 106 may include a transmitter and/or a receiver. A transceiver 106 may be used together with a RF (Radio Frequency) unit. In the present disclosure, a device may mean a communication modem/circuit/chip.

A second device 200 may include one or more processors 202 and one or more memories 204 and may additionally include one or more transceivers 206 and/or one or more antennas 208. A processor 202 may control a memory 204 and/or a transceiver 206 and may be configured to implement description, functions, procedures, proposals, methods and/or operation flows charts disclosed in the present disclosure. For example, a processor 202 may generate third information/signal by processing information in a memory 204, and then transmit a wireless signal including third information/signal through a transceiver 206. In addition, a processor 202 may receive a wireless signal including fourth information/signal through a transceiver 206, and then store information obtained by signal processing of fourth information/signal in a memory 204. A memory 204 may be connected to a processor 202 and may store a variety of information related to an operation of a processor 202. For example, a memory 204 may store a software code including instructions for performing all or part of processes controlled by a processor 202 or for performing description, functions, procedures, proposals, methods and/or operation flow charts disclosed in the present disclosure. Here, a processor 202 and a memory 204 may be part of a communication modem/circuit/chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series). A transceiver 206 may be connected to a processor 202 and may transmit and/or receive a wireless signal through one or more antennas 208. A transceiver 206 may include a transmitter and/or a receiver. A transceiver 206 may be used together with a RF unit. In the present disclosure, a device may mean a communication modem/circuit/chip.

Hereinafter, a hardware element of a device 100, 200 will be described in more detail. It is not limited thereto, but 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., a functional layer such as PHY, MAC). One or more processors 102, 202 may generate one or more PDUs (Protocol Data Unit) and/or one or more SDUs (Service Data Unit) according to description, functions, procedures, proposals, methods and/or operation flow charts disclosed in the present disclosure. One or more processors 102, 202 may generate a message, control information, data or information according to description, functions, procedures, proposals, methods and/or operation flow charts disclosed in the present disclosure. One or more processors 102, 202 may generate a signal (e.g., a baseband signal) including a PDU, a SDU, a message, control information, data or information according to functions, procedures, proposals and/or methods disclosed in the present disclosure to provide it to one or more transceivers 106, 206. One or more processors 102, 202 may receive a signal (e.g., a baseband signal) from one or more transceivers 106, 206 and obtain a PDU, a SDU, a message, control information, data or information according to description, functions, procedures, proposals, methods and/or operation flow charts disclosed in the present disclosure.

One or more processors 102, 202 may be referred to as a controller, a micro controller, a micro processor or a micro computer. One or more processors 102, 202 may be implemented by a hardware, a firmware, a software, or their combination. In an example, one or more ASICs (Application Specific Integrated Circuit), one or more DSPs (Digital Signal Processor), one or more DSPDs (Digital Signal Processing Device), one or more PLDs (Programmable Logic Device) or one or more FPGAs (Field Programmable Gate Arrays) may be included in one or more processors 102, 202. Description, functions, procedures, proposals, methods and/or operation flow charts disclosed in the present disclosure may be implemented by using a firmware or a software and a firmware or a software may be implemented to include a module, a procedure, a function, etc. A firmware or a software configured to perform description, functions, procedures, proposals, methods and/or operation flow charts disclosed in the present disclosure may be included in one or more processors 102, 202 or may be stored in one or more memories 104, 204 and driven by one or more processors 102, 202. Description, functions, procedures, proposals, methods and/or operation flow charts disclosed in the present disclosure may be implemented by using a firmware or a software in a form of a code, an instruction and/or a set of instructions.

One or more memories 104, 204 may be connected to one or more processors 102, 202 and may store data, a signal, a message, information, a program, a code, an indication and/or an instruction in various forms. One or more memories 104, 204 may be configured with ROM, RAM, EPROM, a flash memory, a hard drive, a register, a cash memory, a computer readable storage medium and/or their combination. One or more memories 104, 204 may be positioned inside and/or outside one or more processors 102, 202. In addition, one or more memories 104, 204 may be connected to one or more processors 102, 202 through a variety of technologies such as a wire or wireless connection.

One or more transceivers 106, 206 may transmit user data, control information, a wireless signal/channel, etc. mentioned in methods and/or operation flow charts, etc. of the present disclosure to one or more other devices. One or more transceivers 106, 206 may receiver user data, control information, a wireless signal/channel, etc. mentioned in description, functions, procedures, proposals, methods and/or operation flow charts, etc. disclosed in the present disclosure from one or more other devices. For example, one or more transceivers 106, 206 may be connected to one or more processors 102, 202 and may transmit and receive a wireless signal. For example, one or more processors 102, 202 may control one or more transceivers 106, 206 to transmit user data, control information or a wireless signal to one or more other devices. In addition, one or more processors 102, 202 may control one or more transceivers 106, 206 to receive user data, control information or a wireless signal 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 configured to transmit and receive user data, control information, a wireless signal/channel, etc. mentioned in description, functions, procedures, proposals, methods and/or operation flow charts, etc. disclosed in the present disclosure through one or more antennas 108, 208. In the present disclosure, one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., an antenna port). One or more transceivers 106, 206 may convert a received wireless signal/channel, etc. into a baseband signal from a RF band signal to process received user data, control information, wireless signal/channel, etc. by using one or more processors 102, 202. One or more transceivers 106, 206 may convert user data, control information, a wireless signal/channel, etc. which are processed by using one or more processors 102, 202 from a baseband signal to a RF band signal. Therefore, one or more transceivers 106, 206 may include an (analogue) oscillator and/or a filter.

For example, one of the STAs 100 and 200 may perform an intended operation of an AP, and the other of the STAs 100 and 200 may perform an intended operation of a non-AP STA. For example, the transceivers 106 and 206 of FIG. 1 may perform a transmission and reception operation of a signal (e.g., a packet or a physical layer protocol data unit (PPDU) conforming to IEEE 802.11a/b/g/n/ac/ax/be). In addition, in the present disclosure, an operation in which various STAs generate transmission/reception signals or perform data processing or calculation 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 of generating a transmission/reception signal or performing data processing or calculation in advance for the transmission/reception signal may include 1) determining/acquiring/configuring/calculating/decoding/encoding bit information of fields (signal (SIG), short training field (STF), long training field (LTF), Data, etc.) included in the PPDU, 2) determining/configuring/acquiring time resources or frequency resources (e.g., subcarrier resources) used for fields (SIG, STF, LTF, Data, etc.) included in the PPDU; 3) determining/configuring/acquiring a specific sequence (e.g., pilot sequence, STF/LTF sequence, extra sequence applied to SIG) used for fields (SIG, STF, LTF, Data, etc.) included in the PPDU action, 4) power control operation and/or power saving operation applied to the STA, 5) Operations related to ACK signal determination/acquisition/configuration/calculation/decoding/encoding, etc. In addition, in the following example, various information (e.g., information related to fields/subfields/control fields/parameters/power, etc.) used by various STAs to determine/acquire/configure/calculate/decode/encode transmission and reception signals may be stored in the memories 104 and 204 of FIG. 1.

Hereinafter, downlink (DL) may mean a link for communication from an AP STA to a non-AP STA, and a DL PPDU/packet/signal may be transmitted and received through the DL. In DL communication, a transmitter may be part of an AP STA, and a receiver may be part of a non-AP STA. Uplink (UL) may mean a link for communication from non-AP STAs to AP STAs, and a UL PPDU/packet/signal may be transmitted and received through the UL. In UL communication, a transmitter may be part of a non-AP STA, and a receiver may be part of an AP STA.

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

The structure of the wireless LAN system may consist of be composed of a plurality of components. A wireless LAN supporting STA mobility transparent to an upper layer may be provided by interaction of a plurality of components. A Basic Service Set (BSS) corresponds to a basic construction block of a wireless LAN. FIG. 2 exemplarily shows that two BSSs (BSS1 and BSS2) exist 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). An ellipse representing a BSS in FIG. 2 may also be understood as representing a coverage area in which STAs included in the corresponding BSS maintain communication. This area may be referred to as a Basic Service Area (BSA). When an STA moves out of the BSA, it may not directly communicate with other STAs within the BSA.

If the DS shown in FIG. 2 is not considered, the most basic type of BSS in a wireless LAN is an independent BSS (IBSS). For example, IBSS may have a minimal form containing only two STAs. For example, assuming that other components are omitted, BSS1 containing only STA1 and STA2 or BSS2 containing only STA3 and STA4 may respectively correspond to representative examples of IBSS. This configuration is possible when STAs may communicate directly without an AP. In addition, in this type of wireless LAN, it is not configured in advance, but may be configured when a LAN is required, and this may be referred to as an ad-hoc network. Since the 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 may be made up of mobile STAs, and access to the distributed system (DS) is not allowed, forming a self-contained network.

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

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

DS means a structure in which BSSs are interconnected. Specifically, as shown in FIG. 2, a BSS may exist as an extended form of a network composed of a plurality of BSSs. DS is a logical concept and may be specified by the characteristics of Distributed System Media (DSM). In this regard, a wireless medium (WM) and a DSM may be logically separated. Each logical medium is used for a different purpose and is used by different components. These medium are not limited to being the same, nor are they limited to being different. In this way, the flexibility of the wireless LAN structure (DS structure or other network structure) may be explained in that a plurality of media are logically different. That is, the wireless LAN structure may be implemented in various ways, and the corresponding wireless LAN structure may be independently specified by the physical characteristics of each embodiment.

A DS may support a mobile device by providing seamless integration of a plurality of BSSs and providing logical services necessary to address an address to a destination. In addition, the DS may further include a component called a portal that serves as a bridge for connection between the wireless LAN and other networks (e.g., IEEE 802.X).

The AP enables access to the DS through the WM for the associated non-AP STAs, and means an entity that also has the functionality of an STA. Data movement between the BSS and the DS may be performed through the AP. For example, STA2 and STA3 shown in FIG. 2 have the functionality of STAs, and provide a function allowing the associated non-AP STAs (STA1 and STA4) to access the DS. In addition, since all APs basically correspond to STAs, all APs are addressable entities. The address used by the AP for communication on the WM and the address used by the AP for communication on the DSM are not necessarily the same. A BSS composed 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 a STA address of the corresponding AP may be always received on an uncontrolled port and may be processed by an IEEE 802.1X port access entity. In addition, when a controlled port is authenticated, transmission data (or frames) may be delivered to the DS.

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

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

The wireless LAN system does not assume anything about the relative physical locations of BSSs, and all of the following forms are possible. BSSs may partially overlap, which is a form commonly used to provide continuous coverage. In addition, BSSs may not be physically connected, and logically there is no limit on the distance between BSSs. In addition, the BSSs may be physically located in the same location, which may be used to provide redundancy. In addition, one (or more than one) IBSS or ESS networks may physically exist in the same space as one (or more than one) ESS network. 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 in the same location, this may correspond to the form of an ESS network in the like.

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

In order for an STA to set up a link with respect to a network and transmit/receive data, it first discovers a network, performs authentication, establishes an association, and need to perform the authentication process for security. The link setup process may also be referred to as a session initiation process or a session setup process. In addition, the processes of discovery, authentication, association, and security setting of the link setup process may be collectively referred to as an association process.

In step S310, the STA may perform a network discovery operation. The network discovery operation may include a scanning operation of the STA. That is, in order for the STA to access the network, it needs to find a network in which it can participate. The STA shall identify a compatible network before participating in a wireless network, and the process of identifying a network existing in a specific area is called scanning.

Scanning schemes include active scanning and passive scanning. FIG. 3 exemplarily illustrates a network discovery operation including an active scanning process. In active scanning, an STA performing scanning transmits a probe request frame to discover which APs exist around it while moving channels and waits for a response thereto. A responder transmits a probe response frame as a response to the probe request frame to the STA that has transmitted the probe request frame. Here, the responder may be an STA that last transmitted a beacon frame in the BSS of the channel being scanned. In the BSS, since the AP transmits the beacon frame, the AP becomes a responder, and in the IBSS, the STAs in the IBSS rotate to transmit the beacon frame, so the responder is not constant. For example, a STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1, may store BSS-related information included in the received probe response frame and may move to the next channel (e.g., channel 2) and perform scanning (i.e., transmission/reception of a probe request/response on channel 2) in the same manner.

Although not shown in FIG. 3, the scanning operation may be performed in a passive scanning manner. In passive scanning, a STA performing scanning waits for a beacon frame while moving channels. The beacon frame is one of the management frames defined in IEEE 802.11, and is periodically transmitted to notify the existence of a wireless network and to allow the STA performing scanning to find a wireless network and participate in the wireless network. In the BSS, the AP serves to transmit beacon frames periodically, and in the IBSS, STAs within the IBSS rotate to transmit beacon frames. When the STA performing scanning receives a beacon frame, the STA stores information for the BSS included in the beacon frame and records beacon frame information in each channel while moving to another channel. The STA receiving the beacon frame may store BSS-related information included in the received beacon frame, move to the next channel, and perform scanning in the next channel in the same way. Comparing active scanning and passive scanning, active scanning has an advantage of having less delay and less 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 in order to be clearly distinguished from the security setup operation of step S340 to be described later.

The authentication process includes a process in which the STA transmits an authentication request frame to the AP, and in response to this, the AP transmits an authentication response frame to the STA. An authentication frame used for authentication request/response corresponds to a management frame.

The authentication frame includes an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a robust security network (RSN), and a Finite Cyclic Group, etc. This corresponds to some examples of information that may be included in the authentication request/response frame, and may be replaced with other information or additional information may be further included.

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

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

For example, the association request frame may include information related to various capabilities, a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, RSN, mobility domain, supported operating classes, Traffic Indication Map Broadcast request (TIM broadcast request), interworking service capability, etc. For example, the association response frame may include information related to various capabilities, status code, association ID (AID), supported rates, enhanced distributed channel access (EDCA) parameter set, received channel power indicator (RCPI), received signal to noise indicator (RSNI), mobility domain, timeout interval (e.g., association comeback time), overlapping BSS scan parameters, TIM broadcast response, Quality of Service (QoS) map, etc. This corresponds to some examples of information that may be included in the association request/response frame, and may be replaced with other information or additional information may be further included.

After the STA is successfully associated with 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 Robust Security Network Association (RSNA) request/response, and the authentication process of step S320 is referred to as a first authentication process, and the security setup process of step S340 may also simply be referred to as an authentication process.

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

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

In the wireless LAN system, a basic access mechanism of medium access control (MAC) is a carrier sense multiple access with collision avoidance (CSMA/CA) mechanism. The CSMA/CA mechanism is also called Distributed Coordination Function (DCF) of IEEE 802.11 MAC, and basically adopts a “listen before talk” access mechanism. According to this type of access mechanism, the AP and/or STA may perform Clear Channel Assessment (CCA) sensing a radio channel or medium during a predetermined time interval (e.g., DCF Inter-Frame Space (DIFS)), prior to starting transmission. As a result of the sensing, if it is determined that the medium is in an idle state, frame transmission is started through the corresponding medium. On the other hand, if it is detected that the medium is occupied or busy, the corresponding AP and/or STA does not start its own transmission and may set a delay period for medium access (e.g., a random backoff period) and attempt frame transmission after waiting. By applying the random backoff period, since it is expected that several STAs attempt frame transmission after waiting for different periods of time, collision may be minimized.

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

Referring to FIG. 4, an operation based on a random backoff period will be described. When the occupied/busy medium changes to an idle state, several STAs may attempt to transmit data (or frames). As a method for minimizing collisions, each of STAs may respectively select a random backoff count and attempt transmission after waiting for a corresponding slot time. The random backoff count has a pseudo-random integer value and may be determined as one of values ranging from 0 to CW. Here, CW is a contention window parameter value. The CW parameter is given CWmin as an initial value, but may take a value twice as large in case of transmission failure (e.g., when an ACK for the transmitted frame is not received). When the CW parameter value reaches CWmax, data transmission may be attempted while maintaining the CWmax value until data transmission is successful, and when data transmission is successful, the CWmin value is reset. The values of CW, CWmin and CWmax are preferably set to 2n−1 (n=0, 1, 2, . . . ).

When the random backoff process starts, the STA continuously monitors the medium while counting down the backoff slots according to the determined backoff count value. When the medium is monitored for occupancy, it stops counting down and waits, and resumes the rest of the countdown when the medium becomes idle.

In the example of FIG. 4, when a packet to be transmitted arrives at the MAC of STA3, STA3 may transmit the frame immediately after confirming that the medium is idle as much as DIFS. The remaining STAs monitor and wait for the medium to be occupied/busy. In the meantime, data to be transmitted may also occur in each of STAT, STA2, and STA5, and each STA waits as long as DIFS when the medium is monitored as idle, and then may perform a countdown of the backoff slot according to the random backoff count value selected by each STA. Assume that STA2 selects the smallest backoff count value and STAT selects the largest backoff count value. That is, the case where the remaining back-off time of STA5 is shorter than the remaining back-off time of STAT at the time when STA2 completes the back-off count and starts frame transmission is exemplified. STAT and STA5 temporarily stop counting down and wait while STA2 occupies the medium. When the occupation of STA2 ends and the medium becomes idle again, STAT and STA5 wait for DIFS and resume the stopped backoff count. That is, frame transmission may be started after counting down the remaining backoff slots for the remaining backoff time. Since the remaining backoff time of STA5 is shorter than that of STAT, STA5 starts frame transmission. While STA2 occupies the medium, data to be transmitted may also occur in STA4. From the standpoint of STA4, when the medium becomes idle, STA4 may wait for DIFS, and then may perform a countdown according to the random backoff count value selected by the STA4 and start transmitting frames. The example of FIG. 4 shows a case where the remaining backoff time of STA5 coincides with the random backoff count value of STA4 by chance. In this case, a collision may occur between STA4 and STA5. When a collision occurs, both STA4 and STA5 do not receive an ACK, so data transmission fails. In this case, STA4 and STA5 may double the CW value, select a random backoff count value, and perform a countdown. STAT waits while the medium is occupied due to transmission of STA4 and STA5, waits for DIFS when the medium becomes idle, and then starts frame transmission after 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 a higher layer, and may be transmitted after a backoff performed after DIFS elapses from when the medium becomes idle. Additionally, the management frame is a frame used for exchange of management information that is not forwarded to a higher layer, and is transmitted after a backoff performed after an IFS such as DIFS or Point Coordination Function IFS (PIFS). As a subtype frames of management frame, there are a Beacon, an association request/response, a re-association request/response, a probe request/response, an authentication request/response, etc. A control frame is a frame used to control access to a medium. As a subtype frames of control frame, there are Request-To-Send (RTS), Clear-To-Send (CTS), Acknowledgement (ACK), Power Save-Poll (PS-Poll), block ACK (BlockAck), block ACK request (BlockACKReq), null data packet announcement (NDP announcement), and trigger, etc. If the control frame is not a response frame of the previous frame, it is transmitted after backoff performed after DIFS elapses, and if it is a response frame of the previous frame, it is transmitted without performing backoff after short IFS (SIFS) elapses. The type and subtype of the frame may be identified by a type field and a subtype field in a frame control (FC) field.

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

FIG. 5 is a diagram for explaining a frame transmission operation based on CSMA/CA to which the present disclosure may be applied.

As described above, the CSMA/CA mechanism includes virtual carrier sensing in addition to physical carrier sensing in which a STA directly senses a medium. Virtual carrier sensing is intended to compensate for problems that may occur in medium access, such as a hidden node problem. For virtual carrier sensing, the MAC of the STA may use a Network Allocation Vector (NAV). The NAV is a value indicating, to other STAs, the remaining time until the medium is available for use by an STA currently using or having the right to use the medium. Therefore, the value set as NAV corresponds to a period in 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 corresponding period. For example, the NAV may be configured based on the value of the “duration” field of the MAC header of the frame.

In the example of FIG. 5, it is assumed that a STA1 intends to transmit data to a STA2, and a STA3 is in a position capable of overhearing some or all of frames transmitted and received between the STA1 and the 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 may be applied. In the example of FIG. 5, while transmission of the STA1 is being performed, as a result of carrier sensing of the STA3, it may be determined that the medium is in an idle state. That is, the STA1 may correspond to a hidden node to the STA3. Alternatively, in the example of FIG. 5, it may be determined that the carrier sensing result medium of the STA3 is in an idle state while transmission of the STA2 is being performed. That is, the STA2 may correspond to a hidden node to the STA3. Through the exchange of RTS/CTS frames before performing data transmission and reception between the STA1 and the STA2, a STA outside the transmission range of one of the STA1 or the STA2, or a STA outside the carrier sensing range for transmission from the STA1 or the STA3 may not attempt to occupy the channel during data transmission and reception between the STA1 and the STA2.

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

The STAT may transmit an RTS frame to the STA2 after performing a backoff when the channel is in an idle state during DIFS. When the STA2 receives the RTS frame, the STA2 may transmit a CTS frame as a response to the RTS frame to the STAT after SIFS.

If the STA3 cannot overhear the CTS frame from the STA2 but can overhear the RTS frame from the STAT, the STA3 may set a NAV timer for a frame transmission period (e.g., SIFS+CTS frame+SIFS+data frame+SIFS+ACK frame) that is continuously transmitted thereafter, using the duration information included in the RTS frame. Alternatively, if the STA3 can overhear a CTS frame from the STA2 although the STA3 cannot overhear an RTS frame from the STAT, the STA3 may set a NAV timer for a frame transmission period (e.g., SIFS+data frame+SIFS+ACK frame) that is continuously transmitted thereafter, using the duration information included in the CTS frame. That is, if the STA3 can overhear one or more of the RTS or CTS frames from one or more of the STAT or the STA2, the STA3 may set the NAV accordingly. When the STA3 receives a new frame before the NAV timer expires, the STA3 may update the NAV timer using duration information included in the new frame. The STA3 does not attempt channel access until the NAV timer expires.

When the STAT receives the CTS frame from the STA2, the STAT may transmit the data frame to the STA2 after SIFS from the time point when the reception of the CTS frame is completed. When the STA2 successfully receives the data frame, the STA2 may transmit an ACK frame as a response to the data frame to the STAT after SIFS. The STA3 may determine whether the channel is being used through carrier sensing when the NAV timer expires. When the STA3 determines that the channel is not used by other terminals during DIFS after expiration of the NAV timer, the STA3 may attempt channel access after a contention window (CW) according to a random backoff has passed.

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

By means of an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer, the PHY layer may prepare a MAC PDU (MPDU) to be transmitted. For example, when a command requesting transmission start of the PHY layer is received from the MAC layer, the PHY layer switches to the transmission mode and configures information (e.g., data) provided from the MAC layer in the form of a frame and transmits it. In addition, when the PHY layer detects a valid preamble of the received frame, the PHY layer 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 performed in the form of a frame, and for this purpose, a PHY layer protocol data unit (PPDU) frame format is defined.

A basic PPDU frame may include a Short Training Field (STF), a Long Training Field (LTF), a SIGNAL (SIG) field, and a Data field. The most basic (e.g., non-High Throughput (HT)) PPDU frame format may consist of only L-STF (Legacy-STF), L-LTF (Legacy-LTF), SIG field, and data field. In addition, depending on the type of PPDU frame format (e.g., HT-mixed format PPDU, HT-greenfield format PPDU, VHT (Very High Throughput) PPDU, etc.), an additional (or different type) STF, LTF, and SIG fields may be included between the SIG field and the data field (this will be described later with reference to FIG. 7).

The STF is a signal for signal detection, automatic gain control (AGC), diversity selection, precise time synchronization, and the like, and the LTF is a signal for channel estimation and frequency error estimation. The STF and LTF may be referred to as signals for synchronization and channel estimation of the OFDM physical layer.

The SIG field may include a RATE field and a LENGTH field. The RATE field may include information on modulation and coding rates of data. The LENGTH field may include information on the length of data. Additionally, the SIG field may include a parity bit, a SIG TAIL bit, and the like.

The data field may include a SERVICE field, a physical layer service data unit (PSDU), and a PPDU TAIL bit, and may also include padding bits if necessary. Some bits of the SERVICE field may 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 may be used to return the encoder to a 0 state. Padding bits may be used to adjust the length of a data field in a predetermined unit.

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

The MAC header includes a Frame Control field, a Duration/ID field, an Address field, and the like. The frame control field may include control information required for frame transmission/reception. The duration/ID field may be set to a time for transmitting a corresponding frame or the like. For details of the Sequence Control, QoS Control, and HT Control subfields of the MAC header, refer to the IEEE 802.11 standard document.

A null-data packet (NDP) frame format means a frame format that does not include a data packet. That is, the NDP frame refers to a frame format that includes a physical layer convergence procedure (PLCP) header part (i.e., STF, LTF, and SIG fields) in a general PPDU frame format and does not include the remaining parts (i.e., data field). A NDP frame may also be referred to as a short frame format.

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

In standards such as IEEE 802.11a/g/n/ac/ax, various types of PPDUs have been used. The basic PPDU format (IEEE 802.11a/g) includes L-LTF, L-STF, L-SIG and Data fields. The basic PPDU format may also be referred to as a non-HT PPDU format.

The HT PPDU format (IEEE 802.11n) additionally includes HT-SIG, HT-STF, and HT-LFT(s) fields to the basic PPDU format. The HT PPDU format shown in FIG. 7 may be referred to as an HT-mixed format. In addition, an HT-greenfield format PPDU may be defined, and this corresponds to a format consisting of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTF, and Data field, not including L-STF, L-LTF, and L-SIG (not shown).

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

An example of the HE PPDU format (IEEE 802.11ax) additionally includes Repeated L-SIG (RL-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), Packet Extension (PE) field to the basic PPDU format. Some fields may be excluded or their length may vary according to detailed examples of the HE PPDU format. For example, the HE-SIG-B field is included in the HE PPDU format for multi-user (MU), and the HE-SIG-B is not included in the HE PPDU format for single user (SU). In addition, the HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may vary to 8 us. The Extended Range (HE ER) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may vary to 16 us.

FIGS. 8 to 10 are diagrams for explaining examples of resource units of a WLAN system to which the present disclosure may be applied.

Referring to FIGS. 8 to 10, a resource unit (RU) defined in a wireless LAN system will be described. the RU may include a plurality of subcarriers (or tones). The RU may be used when transmitting signals to multiple STAs based on the OFDMA scheme. In addition, the RU may be defined even when a signal is transmitted to one STA. The RU may be used for STF, LTF, data field of the PPDU, etc.

As shown in FIGS. 8 to 10, RUs corresponding to different numbers of tones (i.e., subcarriers) are used to construct some fields of 20 MHz, 40 MHz, or 80 MHz X-PPDUs (X is HE, EHT, etc.). For example, resources may be allocated in RU units shown for the X-STF, X-LTF, and Data field.

FIG. 8 is a diagram illustrating an exemplary allocation of resource units (RUs) used on a 20 MHz band.

As shown at the top of FIG. 8, 26-units (i.e., units corresponding to 26 tones) may be allocated. 6 tones may be used as a guard band in the leftmost band of the 20 MHz band, and 5 tones may be used as a guard band in the rightmost band of the 20 MHz band. In addition, 7 DC tones are inserted in the center band, that is, the DC band, and 26-units corresponding to each of the 13 tones may exist on the left and right sides of the DC band. In addition, 26-unit, 52-unit, and 106-unit may be allocated to other bands. Each unit may be allocated for STAs or users.

The RU allocation of FIG. 8 is utilized not only in a situation for multiple users (MU) but also in a situation for a single user (SU), and in this case, it is possible to use one 242-unit as shown at the bottom of FIG. 8. In this case, three DC tones may be inserted.

In the example of FIG. 8, RUs of various sizes, that is, 26-RU, 52-RU, 106-RU, 242-RU, etc. are exemplified, but the specific size of these RUs may be reduced or expanded. Therefore, in the present disclosure, the specific size of each RU (i.e., the number of corresponding tones) is exemplary and not restrictive. In addition, within a predetermined bandwidth (e.g., 20, 40, 80, 160, 320 MHz, . . . ) in the present disclosure, the number of RUs may vary according to the size of the RU. In the examples of FIG. 9 and/or FIG. 10 to be described below, the fact that the size and/or number of RUs may be varied is the same as the example of FIG. 8.

FIG. 9 is a diagram illustrating an exemplary allocation of resource units (RUs) used on a 40 MHz band.

Just as RUs of various sizes are used in the example of FIG. 8, 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, and the like may be used in the example of FIG. 9 as well. In addition, 5 DC tones may be inserted at the center frequency, 12 tones may be used as a guard band in the leftmost band of the 40 MHz band, and 11 tones may be used as a guard band in the rightmost band of the 40 MHz band.

In addition, as shown, when used for a single user, a 484-RU may be used.

FIG. 10 is a diagram illustrating an exemplary allocation of resource units (RUs) used on an 80 MHz band.

Just as RUs of various sizes are used in the example of FIG. 8 and FIG. 9, 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, 996-RU and the like may be used in the example of FIG. 10 as well. In addition, in the case of an 80 MHz PPDU, RU allocation of HE PPDUs and EHT PPDUs may be different, and the example of FIG. 10 shows an example of RU allocation for 80 MHz EHT PPDUs. The scheme that 12 tones are used as a guard band in the leftmost band of the 80 MHz band and 11 tones are used as a guard band in the rightmost band of the 80 MHz band in the example of FIG. 10 is the same in HE PPDU and EHT PPDU. Unlike HE PPDU, where 7 DC tones are inserted in the DC band and there is one 26-RU corresponding to each of the 13 tones on the left and right sides of the DC band, in the EHT PPDU, 23 DC tones are inserted into the DC band, and one 26-RU exists on the left and right sides of the DC band. Unlike the HE PPDU, where one null subcarrier exists between 242-RUs rather than the center band, there are five null subcarriers in the EHT PPDU. In the HE PPDU, one 484-RU does not include null subcarriers, but in the EHT PPDU, one 484-RU includes 5 null subcarriers.

In addition, as shown, when used for a single user, 996-RU may be used, and in this case, 5 DC tones are inserted in common with HE PPDU and EHT PPDU.

EHT PPDUs over 160 MHz may be configured with a plurality of 80 MHz subblocks in FIG. 10. The RU allocation for each 80 MHz subblock may be the same as that of the 80 MHz EHT PPDU of FIG. 10. If the 80 MHz subblock of the 160 MHz or 320 MHz EHT PPDU is not punctured and the entire 80 MHz subblock is used as part of RU or multiple RU (MRU), the 80 MHz subblock may use 996-RU of FIG. 10.

Here, the MRU corresponds to a group of subcarriers (or tones) composed of a plurality of RUs, and the plurality of RUs constituting the MRU may be RUs having the same size or RUs having different sizes. For example, a single MRU may be defined as 52+26-tone, 106+26-tone, 484+242-tone, 996+484-tone, 996+484+242-tone, 2X996+484-tone, 3X996-tone, or 3X996+484-tone. Here, the plurality of RUs constituting one MRU may correspond to small size (e.g., 26, 52, or 106) RUs or large size (e.g., 242, 484, or 996) RUs. That is, one MRU including a small size RU and a large size RU may not be configured/defined. In addition, a plurality of RUs constituting one MRU may or may not be consecutive in the frequency domain.

When an 80 MHz subblock includes RUs smaller than 996 tones, or parts of the 80 MHz subblock are punctured, the 80 MHz subblock may use RU allocation other than the 996-tone RU.

The RU of the present disclosure may be used for uplink (UL) and/or downlink (DL) communication. For example, when trigger-based UL-MU communication is performed, the STA transmitting the trigger (e.g., AP) may allocate a first RU (e.g., 26/52/106/242-RU, etc.) to a first STA and allocate a second RU (e.g., 26/52/106/242-RU, etc.) to a second STA, through trigger information (e.g., trigger frame or triggered response scheduling (TRS)). Thereafter, the first STA may transmit a first trigger-based (TB) PPDU based on the first RU, and the second STA may transmit a second TB PPDU based on the second RU. The first/second TB PPDUs may be transmitted to the AP in the same time period.

For example, when a DL MU PPDU is configured, the STA transmitting the DL MU PPDU (e.g., AP) may allocate a first RU (e.g., 26/52/106/242-RU, etc.) to a first STA and allocate a second RU (e.g., 26/52/106/242-RU, etc.) to a second STA. That is, the transmitting STA (e.g., AP) may transmit the HE-STF, HE-LTF, and Data fields for the first STA through the first RU within one MU PPDU, and may transmit the HE-STF, HE-LTF, and Data fields for the second STA through the second RU.

Information on the allocation of RUs may be signaled through HE-SIG-B in the HE PPDU format.

FIG. 11 illustrates an example structure of a HE-SIG-B field.

As shown, the HE-SIG-B field may include a common field and a user-specific field. If HE-SIG-B compression is applied (e.g., full-bandwidth MU-MIMO transmission), the common field may not be included in HE-SIG-B, and the HE-SIG-B content channel may include only a user-specific field. If HE-SIG-B compression is not applied, the common field may be included in HE-SIG-B.

The common field may include information on RU allocation (e.g., RU assignment, RUs allocated for MU-MIMO, the number of MU-MIMO users (STAs), etc.)

The common field may include N*8 RU allocation subfields. Here, N is the number of subfields, N=1 in the case of 20 or 40 MHz MU PPDU, N=2 in the case of 80 MHz MU PPDU, N=4 in the case of 160 MHz or 80+80 MHz MU PPDU, etc. One 8-bit RU allocation subfield may indicate the size (26, 52, 106, etc.) and frequency location (or RU index) of RUs included in the 20 MHz band.

For example, if a value of the 8-bit RU allocation subfield is 00000000, it may indicate that nine 26-RUs are sequentially allocated in order from the leftmost to the rightmost in the example of FIG. 8, if the value is 00000001, it may indicate that seven 26-RUs and one 52-RU are sequentially allocated in order from leftmost to rightest, and if the value is 00000010, it may indicate that five 26-RUs, one 52-RU, and two 26-RUs are sequentially allocated from the leftmost side to the rightmost side.

As an additional example, if the value of the 8-bit RU allocation subfield is 01000y2y1y0, it may indicate that one 106-RU and five 26-RUs are sequentially allocated from the leftmost to the rightmost in the example of FIG. 8. In this case, multiple users/STAs may be allocated to the 106-RU in the MU-MIMO scheme. Specifically, up to 8 users/STAs may be allocated to the 106-RU, and the number of users/STAs allocated to the 106-RU is determined based on 3-bit information (i.e., y2y1y0). For example, when the 3-bit information (y2y1y0) corresponds to a decimal value N, the number of users/STAs allocated to the 106-RU may be N+1.

Basically, one user/STA may be allocated to each of a plurality of RUs, and different users/STAs may be allocated to different RUs. For RUs larger than a predetermined size (e.g., 106, 242, 484, 996-tones, . . . ), a plurality of users/STAs may be allocated to one RU, and MU-MIMO scheme may be applied for the plurality of users/STAs.

The set of user-specific fields includes information on how all users (STAs) of the corresponding PPDU decode their payloads. User-specific fields may contain zero or more user block fields. The non-final user block field includes two user fields (i.e., information to be used for decoding in two STAs). The final user block field contains one or two user fields. The number of user fields may be indicated by the RU allocation subfield of HE-SIG-B, the number of symbols of HE-SIG-B, or the MU-MIMO user field of HE-SIG-A. A User-specific field may be encoded separately from or independently of a common field.

FIG. 12 is a diagram for explaining a MU-MIMO method in which a plurality of users/STAs are allocated to one RU.

In the example of FIG. 12, it is assumed that the value of the RU allocation subfield is 01000010. This corresponds to the case where y2y1y0=010 in 01000y2y1y0. 010 corresponds to 2 in decimal (i.e., N=2) and may indicate that 3 (=N+1) users are allocated to one RU. In this case, one 106-RU and five 26-RUs may be sequentially allocated from the leftmost side to the rightmost side of a specific 20 MHz band/channel. Three users/STAs may be allocated to the 106-RU in a MU-MIMO manner. As a result, a total of 8 users/STAs are allocated to the 20 MHz band/channel, and the user-specific field of HE-SIG-B may include 8 user fields (i.e., 4 user block fields). Eight user fields may be assigned to RUs as shown in FIG. 12.

The user field may be constructed based on two formats. The user field for a MU-MIMO allocation may be constructed with a first format, and the user field for non-MU-MIMO allocation may be constructed with a second format. Referring to the example of FIG. 12, user fields 1 to 3 may be based on the first format, and user fields 4 to 8 may be based on the second format. The first format and the second format may contain bit information of the same length (e.g., 21 bits).

The user field of the first format (i.e., format for MU-MIMO allocation) may be constructed as follows. For example, out of all 21 bits of one user field, B0-B10 includes the user's identification information (e.g., STA-ID, AID, partial AID, etc.), B11-14 includes spatial configuration information such as the number of spatial streams for the corresponding user, B15-B18 includes Modulation and Coding Scheme (MCS) information applied to the Data field of the corresponding PPDU, B19 is defined as a reserved field, and B20 may include information on a coding type (e.g., binary convolutional coding (BCC) or low-density parity check (LDPC)) applied to the Data field of the corresponding PPDU.

The user field of the second format (i.e., the format for non-MU-MIMO allocation) may be constructed as follows. For example, out of all 21 bits of one user field, B0-B10 includes the user's identification information (e.g., STA-ID, AID, partial AID, etc.), B11-13 includes information on the number of spatial streams (NSTS) applied to the corresponding RU, B14 includes information indicating whether beamforming is performed (or whether a beamforming steering matrix is applied), B15-B18 includes Modulation and Coding Scheme (MCS) information applied to the Data field of the corresponding PPDU, B19 includes information indicating whether DCM (dual carrier modulation) is applied, and B20 may include information on a coding type (e.g., BCC or LDPC) applied to the Data field of the corresponding PPDU.

MCS, MCS information, MCS index, MCS field, and the like used in the present disclosure may be indicated by a specific index value. For example, MCS information may be indicated as index 0 to index 11. MCS information includes information on constellation modulation type (e.g., BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM, 1024-QAM, etc.), and coding rate (e.g., ½, ⅔, ¾, ⅚, etc.). Information on a channel coding type (e.g., BCC or LDPC) may be excluded from the MCS information.

FIG. 13 illustrates an example of a PPDU format to which the present disclosure may be applied.

The PPDU of FIG. 13 may be referred as various names such as an EHT PPDU, a transmitted PPDU, a received PPDU, a first type or an Nth type PPDU. For example, the PPDU or EHT PPDU of the present disclosure may be referred as various names such as a transmission PPDU, a reception PPDU, a first type or an Nth type PPDU. In addition, the EHT PPU may be used in an EHT system and/or a new wireless LAN system in which the EHT system is improved.

The EHT MU PPDU of FIG. 13 corresponds to a PPDU carrying one or more data (or PSDUs) for one or more users. That is, the EHT MU PPDU may 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 a plurality of receiving STAs.

In the EHT TB PPDU of FIG. 13, the EHT-SIG is omitted compared to the EHT MU PPDU. Upon receiving a trigger for UL MU transmission (e.g., a trigger frame or TRS), the STA may perform UL transmission based on the EHT TB PPDU format.

In the example of the EHT PPDU format of FIG. 13, L-STF to EHT-LTF correspond to a preamble or a physical preamble, and may be generated/transmitted/received/acquired/decoded in the physical layer.

A Subcarrier frequency spacing of L-STF, L-LTF, L-SIG, RL-SIG, Universal SIGNAL (U-SIG), EHT-SIG field (these are referred to as pre-EHT modulated fields) may be set to 312.5 kHz. A subcarrier frequency spacing of the EHT-STF, EHT-LTF, Data, and PE field (these are referred to as EHT modulated fields) may be set to 78.125 kHz. That is, the tone/subcarrier index of L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG field may be indicated in units of 312.5 kHz, and the tone/subcarrier index of EHT-STF, EHT-LTF, Data, and PE field may be indicated in units of 78.125 kHz.

The L-LTF and L-STF of FIG. 13 may be constructed identically to the corresponding fields of the PPDU described in FIGS. 6 to 7.

The L-SIG field of FIG. 13 may be constructed with 24 bits and may be used to communicate rate and length information. For example, the L-SIG field includes a 4-bit Rate field, a 1-bit Reserved bit, a 12-bit Length field, a 1-bit Parity field, and a 6-bit Tail field may be included. For example, the 12-bit Length field may include information on a time duration or a length of the PPDU. For example, a value of the 12-bit Length field may be determined based on the type of PPDU. For example, for a non-HT, HT, VHT, or EHT PPDU, the value of the Length field may be determined as a multiple of 3. For example, for the HE PPDU, the value of the Length field may be determined as a multiple of 3+1 or a multiple of 3+2.

For example, the transmitting STA may apply BCC encoding based on a coding rate of ½ to 24-bit information of the L-SIG field. Thereafter, the transmitting STA may obtain 48-bit BCC coded bits. BPSK modulation may be applied to 48-bit coded bits to generate 48 BPSK symbols. The transmitting STA may map 48 BPSK symbols to any location except for a pilot subcarrier (e.g., {subcarrier index −21, −7, +7, +21}) and a DC subcarrier (e.g., {subcarrier index 0}). As a result, 48 BPSK symbols may be mapped to subcarrier indices −26 to −22, −20 to −8, −6 to −1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA may additionally map the signals of {−1, −1, −1, 1} to the subcarrier index {−28, −27, +27, +28}. The above signal may be used for channel estimation in the frequency domain corresponding to {−28, −27, +27, +28}.

The transmitting STA may construct RL-SIG which is constructed identically to L-SIG. For RL-SIG, BPSK modulation is applied. The receiving STA may recognize that the received PPDU is a HE PPDU or an EHT PPDU based on the existence of the RL-SIG.

After the RL-SIG of FIG. 13, a Universal SIG (U-SIG) may be inserted. The U-SIG may be referred as various names such as a first SIG field, a first SIG, a first type SIG, a control signal, a control signal field, and a first (type) control signal, etc.

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

Through the U-SIG (or U-SIG field), for example, A bit information (e.g., 52 un-coded bits) may be transmitted, the first symbol of the U-SIG (e.g., U-SIG-1) may transmit the first X bit information (e.g., 26 un-coded bits) of the total A bit information, and the second symbol of the U-SIG (e.g., U-SIG-2) may transmit the remaining Y-bit information (e.g., 26 un-coded bits) of the total A-bit information. For example, the transmitting STA may obtain 26 un-coded bits included in each U-SIG symbol. The transmitting STA may generate 52-coded bits by performing convolutional encoding (e.g., BCC encoding) based on a rate of R=½, and perform interleaving on the 52-coded bits. The transmitting STA may generate 52 BPSK symbols allocated to each U-SIG symbol by performing BPSK modulation on the interleaved 52-coded bits. One U-SIG symbol may be transmitted based on 56 tones (subcarriers) from subcarrier index −28 to subcarrier index+28, except for DC index 0. The 52 BPSK symbols generated by the transmitting STA may be transmitted based on the remaining tones (subcarriers) excluding pilot tones −21, −7, +7, and +21 tones.

For example, the A bit information (e.g., 52 un-coded bits) transmitted by the U-SIG includes a CRC field (e.g., a 4-bit field) and a tail field (e.g., 6 bit-length field). The CRC field and the tail field may be transmitted through the second symbol of the U-SIG. The CRC field may be constructed based on 26 bits allocated to the first symbol of U-SIG and 16 bits remaining except for the CRC/tail field in the second symbol, and may be constructed based on a conventional CRC calculation algorithm. In addition, the tail field may be used to terminate the trellis of the convolution decoder, and for example, the tail field may be set to 0.

A bit information (e.g., 52 un-coded bits) transmitted by the U-SIG (or U-SIG field) may be divided into version-independent bits and version-independent bits. For example, a size of the version-independent bits may be fixed or variable. For example, the version-independent bits may be allocated only to the first symbol of U-SIG, or the version-independent bits may be allocated to both the first symbol and the second symbol of U-SIG. For example, the version-independent bits and the version-dependent bits may be referred as various names such as a first control bit and a second control bit, etc.

For example, the version-independent bits of the U-SIG may include a 3-bit physical layer version identifier (PHY version identifier). For example, the 3-bit PHY version identifier may include information related to the PHY version of the transmitted/received PPDU. For example, the first value of the 3-bit PHY version identifier may indicate that the transmission/reception PPDU is an EHT PPDU. In other words, when transmitting the EHT PPDU, the transmitting STA may set the 3-bit PHY version identifier to a first value. In other words, the receiving STA may determine that the received PPDU is an EHT PPDU based on the PHY version identifier having the first value.

For example, the version-independent bits of U-SIG may include a 1-bit UL/DL flag field. A first value of the 1-bit UL/DL flag field is related to UL communication, and a second value of the UL/DL flag field is related to DL communication.

For example, the version-independent bits of the U-SIG may include information on the length of a transmission opportunity (TXOP) and information on a BSS color ID.

For example, if the EHT PPDU is classified into various types (e.g., EHT PPDU related to SU mode, EHT PPDU related to MU mode, EHT PPDU related to TB mode, EHT PPDU related to Extended Range transmission, etc.), information on the type of EHT PPDU may be included in the version-dependent bits of the U-SIG.

For example, the U-SIG may include information on 1) a bandwidth field containing information on a bandwidth, 2) a field containing information on a MCS scheme applied to EHT-SIG, 3) an indication field containing information related to whether the DCM technique is applied to the EHT-SIG, 4) a field containing information on the number of symbols used for EHT-SIG, 5) a field containing information on whether EHT-SIG is constructed over all bands, 6) a field containing information on the type of EHT-LTF/STF, and 7) a field indicating the length of EHT-LTF and CP length.

Preamble puncturing may be applied to the PPDU of FIG. 13. Preamble puncturing means applying puncturing to some bands (e.g., secondary 20 MHz band) among the entire bands of the PPDU. For example, when an 80 MHz PPDU is transmitted, the STA may apply puncturing to the secondary 20 MHz band in the 80 MHz band and may transmit the PPDU only through the primary 20 MHz band and the secondary 40 MHz band.

For example, the pattern of preamble puncturing may be set in advance. For example, when the first puncturing pattern is applied, puncturing may be applied only to the secondary 20 MHz band within the 80 MHz band. For example, when the second puncturing pattern is applied, puncturing may be applied to only one of the two secondary 20 MHz bands included in the secondary 40 MHz band within the 80 MHz band. For example, when the third puncturing pattern is applied, puncturing may be applied only to the secondary 20 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band). For example, when the fourth puncturing pattern is applied, within the 160 MHz band (or 80+80 MHz band), the primary 40 MHz band included in the primary 80 MHz band exists, and puncturing may be applied to at least one 20 MHz channel that does not belong to the primary 40 MHz band.

Information about preamble puncturing applied to PPDU may be included in U-SIG and/or EHT-SIG. For example, the first field of U-SIG may include information about the contiguous bandwidth of the PPDU, and the second field of U-SIG may include information about preamble puncturing applied to the PPDU.

For example, the U-SIG and the EHT-SIG may include information on preamble puncturing based on the following method. If the bandwidth of the PPDU exceeds 80 MHz, the U-SIG may be individually constructed in units of 80 MHz. For example, if the bandwidth of the PPDU is 160 MHz, the PPDU may include a first U-SIG for a first 80 MHz band and a second U-SIG for a second 80 MHz band. In this case, the first field of the first U-SIG includes information on the 160 MHz bandwidth, and the second field of the first U-SIG includes information on preamble puncturing applied to the first 80 MHz band (i.e., information on a preamble puncturing pattern). In addition, the first field of the second U-SIG includes information on a 160 MHz bandwidth, and the second field of the second U-SIG includes information on preamble puncturing applied to a second 80 MHz band (i.e., information on a preamble puncturing pattern). The EHT-SIG following the first U-SIG may include information on preamble puncturing applied to the second 80 MHz band (i.e., information on a preamble puncturing pattern), and the EHT-SIG following the second U-SIG may include information on preamble puncturing applied to the first 80 MHz band (i.e., information on a preamble puncturing pattern).

Additionally or alternatively, the U-SIG and the EHT-SIG may include information on preamble puncturing based on the following method. The U-SIG may include information on preamble puncturing for all bands (i.e., information on a preamble puncturing pattern). That is, EHT-SIG does not include information on preamble puncturing, and only U-SIG may include information on preamble puncturing (i.e., information on a preamble puncturing pattern).

U-SIG may be constructed in units of 20 MHz. For example, if an 80 MHz PPDU is constructed, the U-SIG may be duplicated. That is, the same 4 U-SIGs may be included in the 80 MHz PPDU. PPDUs exceeding 80 MHz bandwidth may include different U-SIGs.

The EHT-SIG of FIG. 13 may include control information for the receiving STA. EHT-SIG may be transmitted through at least one symbol, and one symbol may have a length of 4 us. Information on the number of symbols used for EHT-SIG may be included in U-SIG.

The EHT-SIG may include technical features of HE-SIG-B described through FIGS. 11 and 12. For example, EHT-SIG, like the example of FIG. 8, may include a common field and a user-specific field. The Common field of the EHT-SIG may be omitted, and the number of user-specific fields may be determined based on the number of users.

As in the example of FIG. 11, the common field of the EHT-SIG and the user-specific field of the EHT-SIG may be coded separately. One user block field included in the user-specific field may contain information for two user fields, but the last user block field included in the user-specific field may contain one or two user fields. That is, one user block field of the EHT-SIG may contain up to two user fields. As in the example of FIG. 12, each user field may be related to MU-MIMO allocation or non-MU-MIMO allocation.

In the same way as in the example of FIG. 11, the common field of the EHT-SIG may include a CRC bit and a Tail bit, The length of the CRC bit may be determined as 4 bits, and the length of the tail bit is determined by 6 bits and may be set to 000000.

As in the example of FIG. 11, the common field of the EHT-SIG may include RU allocation information. RU allocation information may mean information on the location of an RU to which a plurality of users (i.e., a plurality of receiving STAs) are allocated. RU allocation information may be configured in units of 9 bits (or N bits).

A mode in which a common field of EHT-SIG is omitted may be supported. The mode in which the common field of the EHT-SIG is omitted may be referred as a compressed mode. When the compressed mode is used, a plurality of users (i.e., a plurality of receiving STAs) of the EHT PPDU may decode the PPDU (e.g., the data field of the PPDU) based on non-OFDMA. That is, a plurality of users of the EHT PPDU may decode a PPDU (e.g., a data field of the PPDU) received through the same frequency band. When a non-compressed mode is used, multiple users of the EHT PPDU may decode the PPDU (e.g., the data field of the PPDU) based on OFDMA. That is, a plurality of users of the EHT PPDU may receive the PPDU (e.g., the data field of the PPDU) through different frequency bands.

EHT-SIG may be constructed based on various MCS scheme. As described above, information related to the MCS scheme applied to the EHT-SIG may be included in the U-SIG. The EHT-SIG may be constructed based on the DCM scheme. The DCM scheme may reuse the same signal on two subcarriers to provide an effect similar to frequency diversity, reduce interference, and improve coverage. For example, modulation symbols to which the same modulation scheme is applied may be repeatedly mapped on available tones/subcarriers. For example, modulation symbols (e.g., BPSK modulation symbols) to which a specific modulation scheme is applied may be mapped to first contiguous half tones (e.g., 1st to 26th tones) among the N data tones (e.g., 52 data tones) allocated for EHT-SIG, and modulation symbols (e.g., BPSK modulation symbols) to which the same specific modulation scheme is applied may be mapped to the remaining contiguous half tones (e.g., 27th to 52nd tones). That is, a modulation symbol mapped to the 1st tone and a modulation symbol mapped to the 27th tone are the same. As described above, information related to whether the DCM scheme is applied to the EHT-SIG (e.g., a 1-bit field) may be included in the U-SIG. The EHT-STF of FIG. 13 may be used to enhance automatic gain control (AGC) estimation in a MIMO environment or an OFDMA environment. The EHT-LTF of FIG. 13 may be used to estimate a channel in a MIMO environment or an OFDMA environment.

Information on the type of STF and/or LTF (including information on a guard interval (GI) applied to LTF) may be included in the U-SIG field and/or the EHT-SIG field of FIG. 13.

The PPDU (i.e., EHT PPDU) of FIG. 13 may be constructed based on an example of RU allocation of FIGS. 8 to 10.

For example, a EHT PPDU transmitted on a 20 MHz band, that is, a 20 MHz EHT PPDU may be constructed based on the RU of FIG. 8. That is, a RU location of EHT-STF, EHT-LTF, and data field included in the EHT PPDU may be determined as shown in FIG. 8. A EHT PPDU transmitted on a 40 MHz band, that is, a 40 MHz EHT PPDU may be constructed based on the RU of FIG. 9. That is, a RU location of EHT-STF, EHT-LTF, and data field included in the EHT PPDU may be determined as shown in FIG. 9.

The EHT PPDU transmitted on the 80 MHz band, that is, the 80 MHz EHT PPDU may be constructed based on the RU of FIG. 10. That is, a RU location of EHT-STF, EHT-LTF, and data field included in the EHT PPDU may be determined as shown in FIG. 10. The tone-plan for 80 MHz in FIG. 10 may correspond to two repetitions of the tone-plan for 40 MHz in FIG. 9.

The tone-plan for 160/240/320 MHz may be configured in the form of repeating the pattern of FIG. 9 or 10 several times.

The PPDU of FIG. 13 may be identified as an EHT PPDU based on the following method.

The receiving STA may determine the type of the received PPDU as the EHT PPDU based on the following. For example, when 1) the first symbol after the L-LTF signal of the received PPDU is BPSK, 2) RL-SIG in which the L-SIG of the received PPDU is repeated is detected, and 3) the result of applying the modulo 3 calculation to the value of the Length field of the L-SIG of the received PPDU (i.e., the remainder after dividing by 3) is detected as 0, the received PPDU may be determined as a EHT PPDU. When the received PPDU is determined to be an EHT PPDU, the receiving STA may determine the type of the EHT PPDU based on bit information included in symbols subsequent to the RL-SIG of FIG. 13. In other words, the receiving STA may determine the received PPDU as a EHT PPDU, based on 1) the first symbol after the L-LTF signal, which is BSPK, 2) RL-SIG contiguous to the L-SIG field and identical to the L-SIG, and 3) L-SIG including a Length field in which the result of applying modulo 3 is set to 0.

For example, the receiving STA may determine the type of the received PPDU as the HE PPDU based on the following. For example, when 1) the first symbol after the L-LTF signal is BPSK, 2) RL-SIG in which L-SIG is repeated is detected, and 3) the result of applying modulo 3 to the length value of L-SIG is detected as 1 or 2, the received PPDU may be determined as a HE PPDU.

For example, the receiving STA may determine the type of the received PPDU as non-HT, HT, and VHT PPDU based on the following. For example, when 1) the first symbol after the L-LTF signal is BPSK and 2) RL-SIG in which L-SIG is repeated is not detected, the received PPDU may be determined as non-HT, HT, and VHT PPDU.

The PPDU of FIG. 13 may be used to transmit and receive various types of frames. For example, the PPDU of FIG. 13 may be used for (simultaneous) transmission and reception of one or more of a control frame, a management frame, or a data frame.

Trigger Frame

FIG. 14 is a diagram illustrating an example format of a trigger frame to which the present disclosure may 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.

FIG. 14 (a) exemplarily shows an HE variant trigger frame. The trigger frame may include a common information field and a user information list field in the frame body.

The common information field shown as an example in (b) of FIG. 14 may include information commonly applied to the transmission of one or more TB PPDUs requested by a trigger frame, such as trigger type, UL length, presence of a subsequent trigger frame (e.g., More TF), whether CS (channel sensing) is required, UL BW (bandwidth), etc.

For example, the encoding of the trigger type subfield indicating the trigger type may be implemented as shown in Table 1 below, but is not limited thereto.

TABLE 1
Trigger type
subfield value Trigger frame variant
0              Basic
1              Beamforming report poll (BFRQ)
2              MU-BAR (multi-user block ack request)
3              MU-RTS (multi-user request to send)
4              Buffer status report poll
5              GCR(groupcast with retries) MU-BAR
6              Bandwidth query report poll (BQRP)
7              NDP feedback report poll (NFRP)
8-15           Reserved

The user information list includes zero or more user information (user info) fields. FIG. 14(c) exemplarily shows the HE variant user information field format. For example, the user information field may include an AID12 subfield, RU allocation subfield, UL FEC coding type subfield, trigger dependent user field, etc. 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 160 MHz) subfield of the user information field and the UL BW subfield of the common information field.

FIG. 14(d) exemplarily shows a trigger-dependent user information field on a basic trigger frame. The MPDU MU spacing factor subfield may be used to calculate a value multiplied by the minimum MPDU start interval. The TID aggregation limit subfield may indicate the maximum number of TIDs that the STA may aggregate in the MPDU and A-MPDU allowed in the A-MPDU carried in the HE TB PPDU. The Preferred AC subfield may indicate the lowest AC recommended for MPDU merging of A-MPDUs included in a HE TB PPDU transmitted in response to a trigger frame.

Sounding Protocol Sequence

As shown in (a) of FIG. 15, HE non-trigger (non-TB) based sounding sequence is initiated by the HE beamformer with an individually addressed HE NDP announcement frame including one STA information field, and after SIFS, the HE sounding NDP may be transmitted to the (single) HE beamformer. The HE beamformer may receive the HE sounding NDP from the HE beamformer and, after SIFS, respond by transmitting a HE compressed beamforming/CQI frame to the HE beamformer.

If the STA identified by the RA (receiver address) field is a mesh STA, AP, or IBSS STA, the AID11 subfield of the STA information field may be set to 0 or the AID of the STA identified by the RA field of the HE NDP announcement frame.

Specifically, the HE beamformer that starts the HE non-TB sounding sequence must transmit a HE NDP announcement frame with a single STA information (Info) field, and if the STA identified by the RA field is a mesh STA, AP, or IBSS member STA, the AID11 field value of the corresponding STA information field may be set to 0 or the AID of the STA identified by the RA field, rather than 2047. The HE beamformer may initiate a HE non-TB sounding sequence with the HE beamformer to request SU feedback across the entire bandwidth. The HE beamformer may not start HE non-TB with a HE NDP announcement frame with a partial BW information subfield indicating less than the full bandwidth.

As shown in (b) of FIG. 15, the HE TB sounding sequence may be started by a HE beamformer, a HE sounding NDP after SIFS, and a BFRP trigger frame after SIFS using a broadcast HE NDP announcement frame with two or more STA information fields. One or more HE beamformers may receive a BFPR trigger frame and, after SIFS, respond with a HE compressed beamforming/CQI frame. Here, the BFRQ trigger frame may include one or more user information (user info) fields that identify the HE beamformer.

The HE beamformer that starts the HE TB sounding sequence may transmit a HE NDP announcement frame that includes two or more STA information fields and an RA field set as a broadcast address. The HE beamformer may initiate a HE TB sounding sequence to request MU feedback across the entire bandwidth.

The HE beamformer may initiate a HE TB sounding sequence to request a feedback variant only if the feedback variant is calculated based on parameters supported by the HE beamformer. Otherwise, the HE beamformer may not request a feedback variant calculated based on parameters that the HE beamformer does not support.

HE beamformer that transmits the HE NDP announcement frame to the HE beamformer that is an AP TDLS peer STA, mesh STA, or IBSS STA may include one STA information (info) field in the HE NDP announcement frame and set the AID11 field to 0 in the STA information field of the frame.

A HE beamformer that is an AP and transmits a HE NDP announcement frame to one or more HE beamformers may set the AID11 field of the STA information field identifying the non-AP STA to 11 LSB of the AID of the non-AP STA. The HE NDP announcement frame may not include multiple STA information fields with the same value in the AID11 subfield.

HE beamformer transmitting HE NDP announcement frame starting HE TB sounding sequence may include an STA information field with an AID11 subfield value of 2047 to indicate a disallowed subchannel during punctured channel operation. If the STA information field is present, the STA information field with an AID11 value of 2047 may be the first STA information field of the frame. The HE beamformer transmitting the HE NDP announcement frame may not include one or more STA information fields with an AID11 subfield value of 2047.

As shown in (b) of FIG. 15, the HE beamformer that started the HE TB sounding sequence may transmit another BFRP trigger frame on the same TXOP. The HE beamformer may use an additional BFRP trigger frame to request HE compressed beamforming/CQI reporting that was not processed in the previous BFRP trigger frame or to request retransmission of the HE compressed beamforming/CQI report. The HE beamformer may not transmit a BFRP trigger frame identifying the STA identified in the HE NDP Announcement frame of the HE TB sounding sequence unless it is in the same TXOP as the HE TB sounding sequence.

In the HE TB sounding sequence, STA information field in HE NDP announcement frame requesting SU or MU feedback may indicate the subcarrier grouping (Ng), codebook size, and number of columns (Nc) to be used by the HE beamformer identified by the STA information field for generation of SU or MU feedback. And, in the HE TB sounding sequence, the STA information field of the HE NDP announcement frame requesting CQI feedback may indicate the Nc to be used by the HE beamformer identified by the STA information field for generation of CQI feedback.

Additionally, a trigger dependent common information subfield may not exist in the BFRQ trigger frame. The trigger dependent user information subfield of the BFRQ trigger frame may indicate a feedback segment retransmission and the bitmap subfield may indicate a requested feedback segment of the HE compressed beamforming report.

If the bit at position n (n=0 for LSB, n=7 for MSB) in the subfield is 1, a feedback segment with n in the Remaining Feedback Segment subfield of the HE MIMO control field may be requested. If the bit at position n in the subfield is 0, the feedback segment whose remaining feedback segment subfield of the HE MIMO control field is n may be requested.

Wireless LAN (WLAN) Sensing Procedure

The WLAN sensing procedure (hereinafter referred to as sensing procedure) refers to a procedure for obtaining recognition information about the surrounding environment based on information about the channel environment (or state) included in the signal transmitted from the transmitting end to the receiving end. Each STA may provide additional services that can be applied in various forms in real life based on information about the surrounding environment obtained through sensing procedures.

Here, information about the surrounding environment may include, for example, gesture recognition information, fall detection information, intrusion detection information, user movement detection, health monitoring information, or pet movement detection.

FIG. 16 shows an example of a wireless LAN sensing procedure applicable to the present disclosure. The wireless LAN sensing procedure may consist of an association phase (or capability advertisement and negotiation phase), a setup phase, a sensing measurement phase, and a termination phase.

In the association phase, each STA may exchange capabilities related to sensing and be associated.

For example, a sensing initiator (e.g., AP) that initiates a wireless LAN sensing procedure may receive capabilities related to sensing from one or more sensing responders. The sensing initiator may determine whether one or more sensing responders are capable of sensing and have appropriate sensing capabilities based on the capabilities received from one or more sensing responders. Based on determining that one or more sensing responders are capable of sensing and have appropriate sensing capabilities, the one or more sensing responders may be coupled to the sensing responder.

Here, the sensing responder refers to an STA participating in a wireless LAN sensing session initiated by the sensing initiator.

In the setup phase (or negotiation phase, which is part of the setup phase), a sensing session between STAs may be set up. And, in the setup phase, negotiation may be performed regarding the role of the STA related to sensing and the parameters (or/and IDs related to the parameters) to be used during sensing. The negotiated role and parameters of each STA may be used in the sensing session until tear-down.

As an example, a sensing group may be formed in the negotiation phase. A sensing group refers to a group consisting of one or more sensing STAs that perform sensing measurements and feedback to each other. Here, sensing STA refers to an STA capable of sensing.

The role of the STA may be defined as a sensing initiator, sensing responder, sensing transmitter, and sensing receiver. Here, the sensing transmitter refers to the STA that transmits the PDDU used for sensing measurement in the sensing session. A sensing receiver refers to an STA that receives a PPDU from a sensing transmitter and performs sensing measurement.

In the sensing phase, the sensing STA may transmit a sensing signal to identify the target, and may receive and measure the sensing signal that has passed through the target. And, the sensing STA may report the measured results.

One cycle in which the sensing STA transmits a sensing signal and receives/measures the sensing signal that has passed through the target may be defined as a sensing session. A sensing session may consist of one or more sensing measurement instances. That is, the sensing phase may consist of sensing measurement and sensing feedback within a sensing session (or a sensing measurement instance constituting a sensing session).

As another example, the phase in which the sensing STA performs a measurement operation based on the sensing signal may be referred to as a sounding phase. That is, the sounding phase may be a component of the sensing phase.

Also, in the sensing phase, the sensing initiator may transmit a polling frame to at least one sensing responder to confirm/inquire whether to participate in sensing. That is, in order to confirm which STA will participate in the actual sensing measurement among at least one sensing responder which participated in the sensing procedure, the sensing initiator may transmit a polling frame to at least one sensing responder.

The phase of the sensing initiator transmitting a polling frame to at least one sensing responder may be referred to as a polling phase. The polling phase may be included in the sensing phase, but is not limited thereto and may be configured as an independent phase.

In the termination phase, the negotiated role of the STA and parameters related to sensing may be reset, and a negotiation process may be conducted to start the sensing session again.

Operation of Sensing Polling and Sounding Phases

As shown in FIG. 17, in the polling phase, the sensing initiator (e.g., AP) may transmit a polling frame to the sensing responder (e.g., sensing STA 1 to sensing STA 4) to confirm whether or not to participate in sensing measurement.

(In the sounding phase) the AP may perform sensing measurements with sensing STAs confirmed to participate in the sensing procedure (e.g., STAs that transmitted a response frame to the polling frame to the AP in the polling phase).

FIG. 17 shows an example of a sounding phase that proceeds after the polling phase. In FIG. 17, the phase where the sensing STA reports the measurement results is omitted. Reports on measurement results may be transmitted and received immediately after NDP transmission, or after a delay (for a certain period of time).

Specifically, the AP may determine/configure the type of sounding phase (e.g., downlink (DL) sounding stage and uplink (UL) sounding phase) in which each sensing STA will participate when transmitting a polling frame.

For example, as shown in FIG. 17, the AP may determine/configure sensing STA 1 and sensing STA 2 to participate in the UL sounding phase as sensing transmitters, and determine/configure sensing STA3 and sensing STA4 to participate in the DL sounding phase as sensing receivers.

In the UL sounding phase, the AP may transmit a trigger frame to sensing STA 1 and sensing STA 2. Sensing STA 1 and sensing STA 2 that received the trigger frame may transmit the NDP to the AP. In the DL sounding phase, the AP may transmit the NDP announcement frame and NDP to sensing STA 3 and sensing STA 4. Sensing STA 3 and sensing STA 4 may report NDP-based sensing measurement results to the AP.

Here, FIG. 17 only shows an example in which each sensing STA participates in either the DL sounding phase or the UL sounding phase, but the sensing STA may participate in both the DL sounding phase and the UL sounding phase. Meanwhile, the interval between the UL sounding phase and the DL sounding phase may be configured as SIFS.

In the present disclosure, the method by which each sensing STA participates in the DL sounding phase or/and the UL sounding phase (i.e., the signaling method of the polling frame) and the operation when a failure occurs in the polling phase will be described.

FIG. 18 is a diagram illustrating a process in which a first STA performs a sensing procedure, according to an embodiment of the present disclosure.

The first STA may receive a first polling frame including first information related to participation in a first type of measurement for the first STA from an access point (AP) (S1810). Here, the AP may be a sensing initiator, and the first STA and the second STA may be sensing responders.

Specifically, the first polling frame may include a common information field. The common information field may include subfields related to the order of at least one of the first type of measurement or the second type of measurement.

Here, one of the first type of measurement (action) or the second type of measurement (action) may be performed based on the NDP announcement frame (i.e. the DL sounding phase is performed), and the other one of the first type of measurement or the second type of measurement may be performed based on the trigger frame (i.e., the UL sounding phase is performed).

The subfield included in the common information field of the first polling frame may indicate the progress order of at least one of the first type of measurement or the second type of measurement. For example, the subfield may indicate that only the first type of measurement or the second type of measurement is performed, or may indicate the order of the first type of measurement and the second type of measurement.

And, the first polling frame may include at least one user information field. The first information may be indicated by a user information field for the first STA among at least one user information field. That is, the user information field for the first STA may indicate that the first STA will participate in the first type of measurement.

As another example, a user information field for a second STA among at least one user information field included in the first polling frame may include second information related to participation in a second type of measurement for the second STA.

The first STA may transmit the first response frame to the first polling frame to the AP (S1820).

As an example, the first response frame may include information that it accepts information about the first polling frame (e.g., a common information field and a user information field for the first user). As another example, the first response frame may include an ACK frame confirming reception of the first polling frame.

Based on the second response frame being not transmitted to the AP from the second STA among the plurality of STAs including the first STA, the first STA may receive a second polling frame including first information from the AP (S1830).

Specifically, the fact that the second STA does not transmit the second response frame to the AP may mean that the second STA does not participate in the second type of measurement. The AP may not perform recovery operations for the second type of measurement. Accordingly, the first STA can receive a second polling frame including only the first information from the AP.

Here, the second polling frame may not include the second information. And, a subfield included in the common information field of the second polling frame (i.e., a subfield related to the order of at least one of the first type of measurement or the second type of measurement) may include information indicating the first type of measurement.

That is, since the AP does not perform a recovery operation for the second type of measurement, the subfield included in the common information field of the second polling frame may indicate only the first type of measurement.

As an example, the second polling frame may include information indicating that the second polling frame is a retransmitted polling frame. And, the second polling frame may be transmitted from the AP to the first STA after the first response frame is transmitted and SIFS.

FIG. 19 is a diagram illustrating a process in which a second STA performs a sensing procedure, according to an embodiment of the present disclosure.

The AP may transmit the first polling frame to a plurality of stations (STAs) (S1910).

The first polling frame may include first information related to participation in a first type of measurement for a first STA among a plurality of STAs and second information related to participation in a second type of measurement for a second STA.

Since the configuration and related operations of the first polling frame have been described with reference to FIG. 18, redundant description will be omitted.

The AP may receive a first response frame for the first polling frame from the first STA among the plurality of STAs (S1920).

That is, the AP may receive the first response frame for the first polling frame from the first STA participating in the first type of measurement. However, this is only an example, and the AP may receive the first response frame for the first polling frame from another STA participating in the first type of measurement among the plurality of STAs.

Based on the second response frame for the first polling frame being not received from the second STA among the plurality of STAs, the AP may transmit the second polling frame to at least one STA including the first STA (S1930).

Here, the at least one STA refers to an STA participating in the first type of measurement and transmitting a response frame to the first polling frame. And, the second polling frame may include the first information but not the second information.

Since the configuration and related operations of the second polling frame refer to FIG. 18, redundant description will be omitted.

Hereinafter, the method by which each sensing STA participates in the DL sounding phase or/and the UL sounding phase and the operation of the sensing initiator/responder when a failure occurs in the polling phase are described in detail (e.g., when no response frame is sent for a polling frame, etc.).

Embodiment 1

Embodiment 1 relates to the configuration of a polling frame that a sensing initiator transmits to a plurality of sensing responders to inquire whether they will participate in the sensing procedure.

In order for each sensing responder to participate in the DL/UL sounding phase, the polling frame may include a common info field for commonly transmitting information to all sensing responders and a user (or STA) info field for independently transmitting information to each sensing responder.

As an example of this embodiment, the common info field of the polling frame may include information about the order of DL/UL sounding (or, DL/UL sounding order field). DL/UL sounding order may be commonly applied to all STAs participating in sensing measurement.

Specifically, information on the DL/UL sounding order may indicate the progress order of DL sounding and UL sounding based on 1) type of sounding phase each STA will perform/participate in (e.g., DL sounding only, UL sounding only, both of DL and UL sounding)) and 2) both DL sounding and UL sounding are selected/indicated/configured.

As an example, information on the DL/UL sounding order (or DL/UL sounding order field) may consist of 2 bits as shown in Table 2.

TABLE 2
Value Encoding
0     Downlink sounding only
1     Uplink sounding only
2     First DL sounding + Second UL sounding
3     First DL sounding + Second DL sounding

That is, if the index (or value) related to the DL/UL sounding order is set to 0 or 1, information on the DL/UL sounding order may indicate that only DL sounding or UL sounding is progressed/performed. And, if the index (or value) related to the DL/UL sounding order is set to 2 or 3, information on the DL/UL sounding order indicates that both DL sounding and UL sounding are progressed/performed, and may indicate the progress/performance order of each sounding.

As an example of this embodiment, the polling frame may include information related to participation in DL/UL sounding. Information related to participation in DL/UL sounding is included in each user (or STA) information field and may indicate information about which sounding phase each STA will participate in.

As an example, information related to participation in DL/UL sounding (or DL/UL sounding participation field) may be composed of 2 bits as shown in Table 3 below.

TABLE 3
Value Encoding
0     Downlink sounding only
1     Uplink sounding only
2     Both of Downlink sounding and Uplink sounding
3     Reserved

That is, if the index (or value) related to participation in DL/UL sounding included in a specific user info field is set to 0 or 1, information on the DL/UL sounding order may indicate the STA corresponding to a specific user info field to participate only in DL sounding or UL sounding. And, if the index (or value) related to participation in DL/UL sounding included in the specific user info field is set to 2, information on the DL/UL sounding order may indicate the STA corresponding to a specific user info field to participate in both DL sounding and UL sounding.

Here, the DL/UL sounding participation field in Table 3 may be required only when the value of the DL/UL sounding order field in Table 2 is 2 or 3 (i.e., when all DL/UL sounding stages are in progress). That is, when the value of the DL/UL order field in Table 2 is 0 or 1, each STA performs only the DL sounding phase or the UL sounding phase, so the DL/UL sounding participation field may not be needed. Accordingly, a combination rule of Tables 2 and 3 may be necessary.

As an example, assume that the participation field of DL/UL sounding always exists (option 1). If the value of the order field of DL/UL sounding is set to 0, the value of the participation field of DL/UL sounding may always be 0. If the value of the order field of DL/UL sounding is set to 1, the value of the participation field of DL/UL sounding may always be 1. From the STA's perspective, decoding can be performed within a fixed field without dynamic decoding.

As another example, assume that the size of the participation field of DL/UL sounding varies depending on the order field of DL/UL sounding (Option 2). If the value of the order field of DL/UL sounding is set to 0 or 1, the participation field of DL/UL sounding may not exist. If the value of the order field of DL/UL sounding is set to 2 or 3, the participation field of DL/UL sounding may exist. That is, as the presence or absence of a participation field in DL/UL sounding is determined according to the order field of DL/UL sounding, the overhead related to the field can be reduced.

FIG. 20 shows an example when the participation field of DL/UL sounding and the order field of DL/UL sounding are combined. Referring to FIG. 20, the AP may transmit a polling frame to sensing STA 1 to sensing STA 4 in the polling phase.

Here, common info field in polling frames may include information that both DL sounding and UL sounding are performed, and DL sounding is performed before UL sounding (i.e., the order field value of DL/UL sounding is set to 2).

In addition, the user info field related to sensing STA 1 included in the polling frame may include information indicating participation in both DL sounding and UL sounding (i.e., the participation field value of DL/UL sounding is set to 2). The user information field related to sensing STA 2 included in the polling frame may include information indicating participation in UL sounding (that is, the participation field value of DL/UL sounding is set to 1). The user info field related to sensing STA 3 and sensing STA 4 included in the polling frame may include information indicating participation in DL sounding (that is, the participation field value of DL/UL sounding is set to 0).

Accordingly, in the DL sounding phase, the AP may transmit the NDP announcement frame and NDP to sensing STAs 1, 3, and 4. At this time, sensing STAs 1, 3, and 4 may report measurement results based on NDP to the AP. And, in the UL sounding phase, the AP may transmit a trigger frame to sensing STAs 1 and 2. At this time, sensing STAs 1 and 2 may transmit NDP to the AP in response to the trigger frame.

Embodiment 2

Embodiment 2 relates to a recovery mechanism that is performed when a failure issue (e.g., a response frame to a polling frame is not transmitted, etc.) occurs in the polling phase.

In the polling phase that determines the order of DL/UL sounding and whether each STA will participate in sensing measurement (or sounding), an issue as shown in FIG. 21 may occur depending on whether the STA responds.

Specifically, as shown in FIG. 21, assume that a polling frame indicating sensing STA 1 to participate only in the DL sounding phase and sensing STAs 2 and 3 to participate only in the UL sounding phase is transmitted by the AP to sensing STA 1 to sensing STA 3.

Here, sensing STA 1 may not be able to use the channel (for sensing measurement) due to reasons such as overlapping basic service set (OBSS). As shown in FIG. 21, sensing STA 1 may not transmit a response frame to the polling frame to the AP or may transmit a response frame indicating that it cannot participate in the DL sounding phase to the AP.

Accordingly, since the DL sounding phase does not occur/proceed, a specific operation is not performed in the DL sounding time duration 2110 in a specific TXOP, and time may be wasted.

Additionally, since other sensing STAs may access the channel in the corresponding time duration 2110, the subsequent UL sounding phase may not proceed normally. Accordingly, confusion related to the sensing procedure may occur in sensing STA 2 and sensing STA 3, which know that the UL sounding phase proceeds after the DL sounding phase.

In order to solve the above-mentioned problems, the present disclosure describes the operation when no STA responds to a specific type of sounding phase when both the DL sounding phase and the UL sounding phase are indicated according to the order field of DL/UL sounding.

Embodiment 2-1

When both the DL sounding phase and the UL sounding phase are indicated according to the order field of DL/UL sounding, a recovery procedure may be performed for a specific type of sounding phase to which no STA responded.

When the PIFS (PCF inter-frame space) recovery procedure is performed on sensing STA 1 in FIG. 21, a collision may occur between the frame according to the recovery procedure and the response frame for sensing STA 2 and sensing STA 3. Accordingly, the recovery procedure for sensing STA 1 may be performed after sensing STA 2 and sensing STA 3 transmit response frames to the polling frames.

As an example, sensing STA 2 and sensing STA 3 may transmit a response frame to the polling frame, and after SIFS/PIFS, the AP may transmit the polling frame again to sensing STA 1 to sensing STA 3.

Here, the polling frame transmitted again by the AP may include the same information as the previously transmitted polling frame. As another example, the polling frame retransmitted by the AP may include only the user (or STA) information field for sensing STA 1 (i.e., the STA that did not transmit a response frame). Additionally, the polling frame including the user information field for sensing STA 1 may be transmitted only to sensing STA 1, but is not limited to this and may be transmitted to all sensing STAs.

As an example, the common info field of the polling frame retransmitted by the AP may include information (explicitly) indicating that the polling frame has been retransmitted. Additionally or alternatively, sensing STA 2 and sensing STA 3 (i.e., the STA that previously transmitted the response frame) may (implicitly) understand that the polling frame retransmitted from the AP is a retransmitted polling frame.

Additionally, sensing STA 2 and sensing STA 3 (i.e., the STA that previously transmitted a response frame) may not transmit a response frame for the retransmitted polling frame to the AP. That is, since sensing STA 2 and sensing STA 3 have already transmitted a response frame, they may not transmit a response frame for a subsequent polling frame composed of the same/similar information. Accordingly, frame overhead within TXOP can be reduced.

As an example, (a) of FIG. 22 illustrates a case where STA 1 fails to transmit a response frame to a polling frame indicating to participate in the DL sounding phase. Sensing STA 2 and sensing STA 3 transmit response frames, and after SIFS/PIFS, the AP may retransmit a polling frame to sensing STA 1. At this time, the polling frame may include a user (or STA) information field corresponding to sensing STA 1.

FIG. 22(a) shows a case where the polling frame is retransmitted only to sensing STA 1. However, this is only an example, and the polling frame may also be retransmitted to sensing STA 2 and/or sensing STA 3. When receiving a response frame from sensing STA 1, the AP may proceed with the DL sounding phase with sensing STA 1 according to the DL/UL sounding order field included in the common info field of the polling frame. That is, by restoring the DL sounding phase in the above-described manner, sensing measurement performance can be improved. Afterwards, the AP may proceed with the UL sounding phase with sensing STA 2 and sensing STA 3.

Embodiment 2-2

When both the DL sounding phase and the UL sounding phase are indicated according to the order field of DL/UL sounding, recovery procedures may not be performed for certain types of sounding phases to which no sensing STA responds. Afterwards, the AP may transmit a polling frame excluding information related to a specific type of sounding phase to each sensing STA.

Here, the polling frame excluding information related to a specific type of sounding phase may be transmitted only to the remaining STAs excluding STAs that were scheduled to participate in the specific type of sounding phase.

As an example, the common info field of the corresponding polling frame may include information indicating retransmission. As another example, STAs that transmitted a response frame may (implicitly) understand that the corresponding polling frame is a retransmitted polling frame.

Additionally, the sensing STAs that transmitted the response frame may not transmit the response frame for the retransmitted polling frame to the AP, and thus the frame overhead in TXOP can be reduced.

As another example, the retransmitted polling frame may only include IDs for the sensing STAs that transmitted the response frame and information indicating that the corresponding polling frame is a retransmitted polling frame. The AP may indicate that a specific type of sounding phase to which no sensing STA responds will not be performed by transmitting a retransmitted polling frame. Accordingly, the size of the polling frame can be reduced and there may be a benefit in terms of overhead.

As an example, (b) of FIG. 22 illustrates a case where sensing STA 1 fails to transmit a response frame to a polling frame indicating to participate in the DL sounding phase.

Here, the AP may retransmit the polling frame to sensing STA 2 and sensing STA 3 (that is, the STA that transmitted a response frame to the polling frame indicating participation in the UL sounding phase).

Information related to the DL sounding phase may be excluded from the retransmitted polling frame. For example, the order field of DL/UL sounding included in the common info field of a retransmitted polling frame may indicate only UL sounding. And, the retransmitted polling frame may include only user (or STA) fields for the remaining STAs (i.e., STA 2 and STA 3) except for STA 1. That is, the AP may indicate that the DL sounding phase is not in progress by retransmitting the corresponding polling frame.

Here, sensing STA 2 and sensing STA 3 may not transmit a response frame for the retransmitted polling frame. However, this is only an example, and sensing STA 2 and sensing STA 3 may transmit a response frame for the retransmitted polling frame. After the polling phase, the AP may perform the UL sounding phase by transmitting a trigger frame to sensing STA 2 and sensing STA 3.

Embodiments described above are that elements and features of the present disclosure are combined in a predetermined form. Each element or feature should be considered to be optional unless otherwise explicitly mentioned. Each element or feature may be implemented in a form that it is not combined with other element or feature. In addition, an embodiment of the present disclosure may include combining a part of elements and/or features. An order of operations described in embodiments of the present disclosure may be changed. Some elements or features of one embodiment may be included in other embodiment or may be substituted with a corresponding element or a feature of other embodiment. It is clear that an embodiment may include combining claims without an explicit dependency relationship in claims or may be included as a new claim by amendment after application.

It is clear to a person skilled in the pertinent art that the present disclosure may be implemented in other specific form in a scope not going beyond an essential feature of the present disclosure. Accordingly, the above-described detailed description should not be restrictively construed in every aspect and should be considered to be illustrative. A scope of the present disclosure should be determined by reasonable construction of an attached claim and all changes within an equivalent scope of the present disclosure are included in a scope of the present disclosure.

A scope of the present disclosure includes software or machine-executable commands (e.g., an operating system, an application, a firmware, a program, etc.) which execute an operation according to a method of various embodiments in a device or a computer and a non-transitory computer-readable medium that such a software or a command, etc. are stored and are executable in a device or a computer. A command which may be used to program a processing system performing a feature described in the present disclosure may be stored in a storage medium or a computer-readable storage medium and a feature described in the present disclosure may be implemented by using a computer program product including such a storage medium. A storage medium may include a high-speed random-access memory such as DRAM, SRAM, DDR RAM or other random-access solid state memory device, but it is not limited thereto, and it may include a nonvolatile memory such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices or other nonvolatile solid state storage devices. A memory optionally includes one or more storage devices positioned remotely from processor(s). A memory or alternatively, nonvolatile memory device(s) in a memory include a non-transitory computer-readable storage medium. A feature described in the present disclosure may be stored in any one of machine-readable mediums to control a hardware of a processing system and may be integrated into a software and/or a firmware which allows a processing system to interact with other mechanism utilizing a result from an embodiment of the present disclosure. Such a software or a firmware may include an application code, a device driver, an operating system and an execution environment/container, but it is not limited thereto.

A method proposed by the present disclosure is mainly described based on an example applied to an IEEE 802.11-based system, 5G system, but may be applied to various WLAN or wireless communication systems other than the IEEE 802.11-based system.

Claims

1. A method of performing a sensing procedure by a first station (STA) in a wireless LAN system, the method comprising: receiving, from an access point (AP), a first polling frame including first information related to participation in a first type of measurement for the first STA;transmitting, to the AP, a first response frame for the first polling frame; andbased on a second response frame for the first polling frame being not transmitted to the AP from a second STA among a plurality of STAs including the first STA, receiving a second polling frame including the first information from the AP,wherein the first polling frame includes second information related to participation in a second type of measurement for the second STA, andwherein the second polling frame does not include the second information.

2. The method of claim 1, wherein: each of the first polling frame and the second polling frame includes a common info field, andthe common info field includes a subfield related to an order of at least one of the first type of measurement or the second type of measurement.

3. The method of claim 2, wherein: the subfield included in the common info field of the first polling frame indicates information on the order of the first type of measurement and the second type of measurement, andthe subfield included in the common info field of the second polling frame includes information indicating the first type of measurement.

4. The method of claim 1, wherein: the first information is indicated by a user info field for the first STA included in each of the first polling frame and the second polling frame, andthe second information is indicated by a user info field for the second STA included in the first polling frame.

5. The method of claim 1, wherein: the second polling frame includes information indicating that the second polling frame is a retransmitted polling frame.

6. The method of claim 1, wherein: either the first type of measurement or the second type of measurement is performed based on a null data physical protocol data unit (PPDU) announcement frame, andthe other one of the first type of measurement or the second type of measurement is performed based on a trigger frame.

7. The method of claim 6, wherein: a response frame for the second polling frame is not transmitted from the first STA to the AP, andafter the second polling frame is received from the AP and a predefined time, the NDP announcement frame or the trigger frame is transmitted from the AP to the first STA.

8. The method of claim 1, wherein: the second polling frame is received from the AP after the first response frame is transmitted and SIFS (short inter-frame space).

9. The method of claim 1, wherein: the first STA and the second STA are sensing responders, andthe AP is a sensing initiator.

10. A first station (STA) for performing sensing procedure in a wireless LAN system, the first STA comprising: at least one transceiver; andat least one processor connected to the at least one transceiver,wherein the at least one processor is configured to:receive, from an access point (AP) through the at least one transceiver, a first polling frame including first information related to participation in a first type of measurement for the first STA;transmit, to the AP through the at least one transceiver, a first response frame for the first polling frame; andbased on a second response frame for the first polling frame being not transmitted to the AP from a second STA among a plurality of STAs including the first STA, receive a second polling frame including the first information from the AP through the at least one transceiver,wherein the first polling frame includes second information related to participation in a second type of measurement for the second STA, andwherein the second polling frame does not include the second information.

11. (canceled)

12. An access point (AP) for performing sensing procedure in a wireless LAN system, the AP comprising: at least one transceiver; andat least one processor connected to the at least one transceiver,wherein the at least one processor is configured to:transmit a first polling frame to a plurality of stations (STAs) through the at least one transceiver;receive a first response frame for the first polling frame from a first STA among the plurality of STAs through the at least one transceiver; andbased on a second response frame for the first polling frame being not received from a second STA among the plurality of STAs, transmit a second polling frame to at least one STA including the first STA through the at least one transceiver,wherein the first polling frame includes second information related to participation in a second type of measurement for the second STA, andwherein the second polling frame does not include the second information.

13-14. (canceled)