WO2025147024A1 - Method and device for millimeter wave band-based frame transmission and reception in wireless lan system - Google Patents

Abstract

Disclosed are a method and device for millimeter wave band-based frame transmission and reception in a wireless LAN system. The method according to one embodiment of the present disclosure may comprise the steps in which: a first station (STA) transmits, to a second station, one or more first frames for beamforming training on the basis of M (M < N) sectors among overall N (N > 1) sectors; and the first STA receives, from the second STA, a second frame including information about the best sector among the M sectors. Here, before the beamforming training, information about the M sectors can be exchanged between the first STA and the second STA.

Description

Method and device for performing frame transmission and reception based on millimeter wave band in wireless LAN system

The present disclosure relates to a method and device for transmitting and receiving frames based on a millimeter wave (mmWave) band in a wireless local area network (WLAN) system.

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

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

The technical problem of the present disclosure is to provide a method and device for transmitting and receiving a frame based on a millimeter wave (mmWave) band in a wireless local area network (WLAN) system.

In particular, the technical challenge of the present disclosure is to provide a method and device for performing a sector level sweep (SLS) on a millimeter wave (mmWave) band.

The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

A method according to one aspect of the present disclosure may include: transmitting, by a first station (STA), to a second STA, one or more first frames for beamforming training based on M (M<N) sectors out of a total of N (N>1) sectors; and receiving, by the first STA, a second frame from the second STA, a second frame including information about a best sector out of the M sectors. Here, prior to the beamforming training, information about the M sectors may be exchanged between the first STA and the second STA.

A method according to an additional aspect of the present disclosure may include: receiving, by a second station (STA), from a first STA, one or more first frames for beamforming training based on M (M<N) sectors out of a total of N (N>1) sectors; and transmitting, by the second STA, to the first STA, a second frame including information about a best sector out of the M sectors. Here, prior to the beamforming training, information about the M sectors may be exchanged between the first STA and the second STA.

According to the present disclosure, a method and device for transmitting and receiving a frame based on a millimeter wave (mmWave) band in a wireless local area network (WLAN) system can be provided.

According to the present disclosure, a method and device for performing a sector level sweep (SLS) on a millimeter wave (mmWave) band can be provided.

According to the present disclosure, there is an advantage in that a wireless LAN system can efficiently support the mmWave band, thereby achieving high data rate and low latency.

The effects obtainable from the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

The accompanying drawings, which are incorporated in and are incorporated in and are intended to aid in understanding the present disclosure, provide embodiments of the present disclosure and together with the detailed description, describe the technical features of the present disclosure.

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

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

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

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

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

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

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

Figure 8 illustrates a sector level sweep (SLS) step that may be applied to the present disclosure.

Figure 9 illustrates two types of sector sweeps that may be applied to the present disclosure.

Figure 10 illustrates a BRP transaction that can be applied to the present disclosure.

FIG. 11 is a diagram showing regional examples of channelization of millimeter wave (mmWave) bands to which the present disclosure can be applied.

FIG. 12 illustrates the operation of a first STA according to an embodiment of the present disclosure.

FIG. 13 illustrates the operation of a second STA according to an embodiment of the present disclosure.

FIG. 14 is a diagram for explaining a PPDU transmission and reception procedure between a transmitting STA and a receiving STA according to an embodiment of the present disclosure.

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

In some cases, to avoid obscuring the concepts of the present disclosure, well-known structures and devices may be omitted or illustrated in block diagram format focusing on the core functions of each structure and device.

In the present disclosure, when a component is said to be "connected", "coupled" or "connected" to another component, this may include not only a direct connection relationship, but also an indirect connection relationship in which another component exists between them. Also, the terms "comprises" or "has" in the present disclosure specify the presence of the mentioned features, steps, operations, elements and/or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and/or groups thereof.

In this disclosure, the terms “first,” “second,” etc. are used only to distinguish one component from other components and are not used to limit the components, and do not limit the order or importance among the components unless specifically stated otherwise. Accordingly, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "and/or" as used herein may refer to one of the associated enumerated items or is meant to refer to and encompass any and all possible combinations of two or more of them. Furthermore, the word "/" used between words in this disclosure has the same meaning as "and/or" unless otherwise stated.

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

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

FIG. 1 illustrates a block diagram of a wireless communication device according to one 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), a User Equipment (UE), a Mobile Station (MS), a user terminal (UT), a Mobile Subscriber Station (MSS), a Mobile Subscriber Unit (MSS), a Subscriber Station (SS), an Advanced Mobile Station (AMS), a Wireless terminal (WT), or simply a user. In addition, the first device (100) and the second device (200) may be replaced with various terms such as an access point (AP), a base station (BS), a fixed station, a Node B, a base transceiver system (BTS), a network, an Artificial Intelligence (AI) system, a road side unit (RSU), a repeater, a router, a relay, a gateway, etc.

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

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

In addition, the first device (100) and the second device (200) may additionally support various communication standards (for example, standards of 3GPP LTE series, 5G NR series, etc.) other than wireless LAN technology. In addition, the device of the present disclosure may be implemented as various devices such as a mobile phone, a vehicle, a personal computer, an Augmented Reality (AR) device, and a Virtual Reality (VR) device. In addition, the STA of the present specification may support various communication services such as a voice call, a video call, a data communication, autonomous driving, MTC (Machine-Type Communication), M2M (Machine-to-Machine), D2D (Device-to-Device), and IoT (Internet-of-Things).

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

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

Hereinafter, hardware elements of the device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this disclosure. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this disclosure. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, suggestions and/or methodologies disclosed in this disclosure, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in this disclosure.

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

One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and/or commands. The one or more memories (104, 204) may be comprised of ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer readable storage media, and/or combinations thereof. The one or more memories (104, 204) may be located internally and/or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

One or more transceivers (106, 206) can transmit user data, control information, wireless signals/channels, etc., as mentioned in the methods and/or flowcharts of the present disclosure, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals/channels, etc., as mentioned in the descriptions, functions, procedures, suggestions, methods and/or flowcharts of the present disclosure, from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals/channels, and the like, as described in the description, function, procedure, proposal, method, and/or operational flowchart, etc. disclosed in this disclosure, via one or more antennas (108, 208). In the present disclosure, one or more antennas may be multiple physical antennas, or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) may convert received user data, control information, wireless signals/channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals/channels, etc. using one or more processors (102, 202). One or more transceivers (106, 206) may convert processed user data, control information, wireless signals/channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and/or filter.

For example, one of the STAs (100, 200) may perform the intended operation of an AP, and the other of the STAs (100, 200) may perform the intended operation of a non-AP STA. For example, the transceivers (106, 206) of FIG. 1 may perform transmission and reception operations of signals (e.g., packets or PPDUs (Physical layer Protocol Data Units) according to IEEE 802.11a/b/g/n/ac/ax/be/bn, etc.). In addition, in the present disclosure, operations of various STAs generating transmission and reception signals or performing data processing or calculations in advance for transmission and reception signals may be performed in the processors (102, 202) of FIG. 1. For example, an example of an operation for generating a transmit/receive signal or performing data processing or calculation in advance for a transmit/receive signal may include: 1) an operation for determining/acquiring/configuring/computing/decoding/encoding bit information of a field (SIG (signal), STF (short training field), LTF (long training field), Data, etc.) included in a PPDU, 2) an operation for determining/configuring/acquiring time resources or frequency resources (e.g., subcarrier resources) used for the fields (SIG, STF, LTF, Data, etc.) included in a PPDU, 3) an operation for determining/configuring/acquiring specific sequences (e.g., pilot sequences, STF/LTF sequences, extra sequences applied to SIG) used for the fields (SIG, STF, LTF, Data, etc.) included in a PPDU, 4) a power control operation and/or a power saving operation applied to an STA, 5) an operation related to determining/acquiring/configuring/computing/decoding/encoding an ACK signal, etc. In addition, in the examples below, various information (e.g., information related to fields/subfields/control fields/parameters/power, etc.) used by various STAs for determining/acquiring/configuring/computing/decoding/encoding transmission/reception signals can be stored in the memory (104, 204) of FIG. 1.

Hereinafter, downlink (DL) means a link for communication from an AP STA to a non-AP STA, and downlink PPDU/packet/signal, etc. can be transmitted and received through the downlink. In downlink communication, a transmitter may be part of an AP STA, and a receiver may be part of a non-AP STA. Uplink (UL) means a link for communication from a non-AP STA to an AP STA, and uplink PPDU/packet/signal, etc. can be transmitted and received through the uplink. In uplink 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 showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

The structure of a wireless LAN system can be composed of multiple components. A wireless LAN supporting transparent STA mobility to a higher layer can be provided through the interaction of multiple components. A BSS (Basic Service Set) corresponds to a basic configuration block of a wireless LAN. FIG. 2 illustrates an example in which 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 can also be understood as representing a coverage area in which STAs included in the corresponding BSS maintain communication. This area can be referred to as a BSA (Basic Service Area). If an STA moves out of the BSA, it cannot directly communicate with other STAs within the corresponding BSA.

If we do not consider the DS illustrated in Fig. 2, the most basic type of BSS in a wireless LAN is an independent BSS (IBSS). For example, an IBSS can have a minimal form consisting of only two STAs. For example, assuming that other components are omitted, BSS1 consisting of only STA1 and STA2 or BSS2 consisting of only STA3 and STA4 can be representative examples of an IBSS, respectively. This configuration is possible when STAs can communicate directly without an AP. In addition, in this type of wireless LAN, a LAN can be configured when needed rather than being planned in advance, and this can be called an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity that performs management functions. That is, in an IBSS, STAs are managed in a distributed manner. In IBSS, all STAs can be mobile STAs, and access to distributed systems (DS) is not permitted, forming a self-contained network.

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

In wireless LANs, the direct STA-to-STA distance may be limited by the PHY performance. In some cases, this distance limitation may be sufficient, but in some cases, communication between STAs over longer distances may be required. To support extended coverage, a distributed system (DS) may be configured.

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

A DS can support mobile devices by providing seamless integration of multiple BSSs and providing logical services necessary to handle addresses to destinations. In addition, a DS can further include a component called a portal that acts as a bridge for connecting wireless LANs to other networks (e.g., IEEE 802.X).

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

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

In addition to the structure of the DS described above, an Extended Service Set (ESS) may be established to provide wider coverage.

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

In a wireless LAN system, no assumption is made about the relative physical locations of the BSSs, and all of the following configurations are possible: The BSSs can be partially overlapped, which is a common configuration used to provide continuous coverage. Also, the BSSs can be physically unconnected, and logically there is no limit to the distance between the BSSs. Also, the BSSs can be physically co-located, which can be used to provide redundancy. Also, one (or more) IBSS or ESS networks can physically co-exist in the same space as one (or more) ESS networks. This can correspond to ESS network configurations such as cases where ad-hoc networks operate at locations where ESS networks exist, cases where physically overlapping wireless networks are configured by different organizations, or cases where two or more different access and security policies are required at the same location.

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

In order for an STA to set up a link to a network and send and receive data, it must first discover the network, perform authentication, establish an association, and go through authentication procedures for security. The link setup process may also be referred to as a session initiation process or a session setup process. In addition, the discovery, authentication, association, and security setup processes of the link setup process may be collectively referred to as the 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 must find a network that it can participate in. The STA must identify a compatible network before participating in the wireless network, and the process of identifying networks existing in a specific area is called scanning.

There are two types of scanning methods: active scanning and passive scanning. FIG. 3 illustrates a network discovery operation including an active scanning process as an example. In active scanning, an STA performing scanning transmits a probe request frame to search for APs in the vicinity while moving between channels and waits for a response thereto. A responder transmits a probe response frame to the STA that transmitted the probe request frame as a response to 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, the AP transmits a beacon frame, so the AP becomes the responder, and in the IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not fixed. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning (i.e., transmitting and receiving probe request/response on channel 2) in the same manner.

Although not shown in FIG. 3, the scanning operation can also be performed in a passive scanning manner. In passive scanning, an STA performing scanning moves through channels and waits for a beacon frame. A 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 enable an STA performing scanning to find a wireless network and participate in the wireless network. In a BSS, an AP periodically transmits a beacon frame, and in an IBSS, STAs in the IBSS take turns transmitting beacon frames. When an STA performing scanning receives a beacon frame, it stores information about the BSS included in the beacon frame and moves to another channel, recording beacon frame information on each channel. An STA receiving a beacon frame stores information related to the BSS included in the received beacon frame, moves to the next channel, and performs scanning on the next channel in the same manner. Comparing active scanning and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.

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

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

The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), a Finite Cyclic Group, etc. These are just some examples of information that may be included in an authentication request/response frame, and may be replaced by other information or may include additional information.

The STA may transmit an authentication request frame to the AP. The AP may determine whether to allow authentication for the STA based on information included in the received authentication request frame. The AP may provide the result of the authentication processing 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 about various capabilities, a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, RSN, mobility domains, supported operating classes, a Traffic Indication Map Broadcast request, interworking service capabilities, etc. For example, the association response frame may include information about various capabilities, a status code, an Association ID (AID), supported rates, an Enhanced Distributed Channel Access (EDCA) parameter set, a Received Channel Power Indicator (RCPI), a Received Signal to Noise Indicator (RSNI), a mobility domain, a timeout interval (e.g., association comeback time), overlapping BSS scan parameters, a TIM broadcast response, a Quality of Service (QoS) map, etc. These are just a few examples of the information that may be included in a combined request/response frame, and may be replaced by other information or include additional information.

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

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

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

In wireless LAN systems, the basic access mechanism of MAC (Medium Access Control) is the CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism. The CSMA/CA mechanism is also called the Distributed Coordination Function (DCF) of IEEE 802.11 MAC, and basically adopts the "listen before talk" access mechanism. According to this type of access mechanism, the AP and/or STA may perform a Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time period (e.g., a DCF Inter-Frame Space (DIFS)) before starting transmission. If the sensing result determines that the medium is in an idle state, the AP and/or STA may start transmitting frames through the medium. On the other hand, if the medium is detected to be occupied or busy, the AP and/or STA may not start its own transmission, but may wait for a delay period (e.g., a random backoff period) for medium access and then attempt to transmit frames. By applying the random backoff period, it is expected that multiple STAs will attempt to transmit frames after waiting for different periods of time, thereby minimizing collisions.

In addition, the IEEE 802.11 MAC protocol provides a Hybrid Coordination Function (HCF). The HCF is based on the DCF and the Point Coordination Function (PCF). The PCF is a polling-based synchronous access method in which all receiving APs and/or STAs periodically poll to receive data frames. In addition, the HCF has EDCA (Enhanced Distributed Channel Access) and HCCA (HCF Controlled Channel Access). EDCA is a contention-based access method in which a provider provides 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 the QoS (Quality of Service) of a wireless LAN, and can 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 is described. When an occupied/busy medium changes to an idle state, multiple STAs may attempt to transmit data (or frames). As a measure to minimize collisions, each STA may select a random backoff count, wait for a corresponding slot time, and then attempt to transmit. The random backoff count has a pseudo-random integer value and may be determined as one of the values in the range of 0 to CW. Here, CW is a contention window parameter value. The CW parameter is initially given CWmin, but may take a double value in case of a transmission failure (e.g., when an ACK for a transmitted frame is not received). When the CW parameter value becomes CWmax, data transmission may be attempted while maintaining the CWmax value until data transmission is successful, and if data transmission is successful, it is reset to the CWmin value. It is desirable that the CW, CWmin and CWmax values be set to 2 ⁿ -1 (n=0, 1, 2, ...).

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

In the example of Fig. 4, when a packet to be transmitted reaches the MAC of STA3, STA3 can check that the medium is idle for DIFS and transmit the frame right away. The remaining STAs monitor whether the medium is occupied/busy and wait. In the meantime, data to be transmitted may also occur in each of STA1, STA2, and STA5, and each STA can perform a countdown of the backoff slot according to a random backoff count value selected by each STA after waiting for DIFS when the medium is monitored as idle. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. In other words, this example shows a case where the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1 when STA2 finishes the backoff count and starts frame transmission. STA1 and STA5 briefly stop the countdown and wait while STA2 occupies the medium. When STA2's occupation ends and the medium becomes idle again, STA1 and STA5 resume the stopped backoff count after waiting for DIFS. That is, they can start frame transmission after counting down the remaining backoff slots by the remaining backoff time. Since the remaining backoff time of STA5 is shorter than that of STA1, STA5 starts frame transmission. While STA2 occupies the medium, STA4 may also have data to transmit. From STA4's perspective, when the medium becomes idle, it waits for DIFS, performs a countdown according to the random backoff count value it selected, and starts frame transmission. In the example of Fig. 4, the remaining backoff time of STA5 coincidentally matches the random backoff count value of STA4, and in this case, a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 will receive an ACK, resulting in a failure in data transmission. In this case, STA4 and STA5 can select a random backoff count value and perform a countdown after doubling the CW value. STA1 waits while the medium is occupied by transmissions from STA4 and STA5, and when the medium becomes idle, it waits for DIFS, and then starts transmitting frames after the remaining backoff time has elapsed.

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

A QoS (Quality of Service) STA can transmit a frame after a backoff performed after the AIFS (arbitration IFS) for the access category (AC) to which the frame belongs, i.e., AIFS[i] (where i is a value determined by the AC), has elapsed. Here, the frames for which AIFS[i] can be used can be data frames, management frames, and also control frames that are not response frames.

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

As described above, the CSMA/CA mechanism includes virtual carrier sensing in addition to physical carrier sensing in which an STA directly senses the medium. Virtual carrier sensing is intended to complement problems that may occur in medium access, such as the hidden node problem. For virtual carrier sensing, the MAC of the STA may utilize a Network Allocation Vector (NAV). The NAV is a value that indicates to other STAs the remaining time until the medium becomes available, by an STA that is currently using or has the right to use the medium. Therefore, the value set as NAV corresponds to the period during which the medium is scheduled to be used by the STA transmitting the corresponding frame, and the STA that receives the NAV value is prohibited from accessing the medium during the corresponding period. For example, the NAV may be set 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 STA1 wants to transmit data to STA2, and STA3 is in a position to overhear part or all of the frames transmitted and received between STA1 and STA2.

In order to reduce the possibility of collision of transmissions of multiple STAs in a CSMA/CA-based frame transmission operation, a mechanism using RTS/CTS frames may be applied. In the example of FIG. 5, while STA1 is transmitting, STA3 may determine that the carrier sensing result of the medium is idle. That is, STA1 may correspond to a hidden node to STA3. Alternatively, while STA2 is transmitting, STA3 may determine that the carrier sensing result of the medium is idle. That is, STA2 may correspond to a hidden node to STA3. Before performing data transmission and reception between STA1 and STA2, by exchanging RTS/CTS frames, STAs outside the transmission range of either STA1 or STA2, or STAs outside the carrier sensing range for transmission from STA1 or STA3 may not attempt to occupy the channel during data transmission and reception between STA1 and STA2.

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

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

If STA3 cannot overhear the CTS frame from STA2 but can overhear the RTS frame from STA1, STA3 can set a NAV timer for the subsequently transmitted frame transmission period (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame) using the duration information included in the RTS frame. Alternatively, if STA3 cannot overhear the RTS frame from STA1 but can overhear the CTS frame from STA2, STA3 can set a NAV timer for the subsequently transmitted frame transmission period (e.g., SIFS + data frame + SIFS + ACK frame) using the duration information included in the CTS frame. That is, if STA3 can overhear one or more of the RTS or CTS frames from one or more of STA1 or STA2, it can set a NAV accordingly. STA3 can update the NAV timer using the duration information contained in the new frame if it receives a new frame before the NAV timer expires. STA3 does not attempt to access the channel until the NAV timer expires.

If STA1 receives a CTS frame from STA2, it can transmit a data frame to STA2 after SIFS from the time when reception of the CTS frame is completed. If STA2 successfully receives the data frame, it can transmit an ACK frame in response to the data frame to STA1 after SIFS. STA3 can determine whether the channel is in use through carrier sensing if the NAV timer expires. If STA3 determines that the channel is not in use by other terminals during DIFS after the expiration of the NAV timer, it can attempt channel access after a contention window (CW) following a random backoff has elapsed.

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

The PHY layer can prepare an MPDU (MAC PDU) to be transmitted by an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer. For example, when a command requesting the start of transmission of the PHY layer is received from the MAC layer, the PHY layer can switch to transmission mode and transmit information (e.g., data) provided from the MAC layer in the form of a frame. In addition, when the PHY layer detects a valid preamble of the received frame, it monitors the header of the preamble and sends a command to the MAC layer notifying the start of reception of the PHY layer.

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

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

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

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

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

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

The MAC header includes a Frame Control field, a Duration/ID field, an Address field, etc. The Frame Control field may include control information required for frame transmission/reception. The Duration/ID field may be set to a time for transmitting the corresponding frame, etc. The Address subfields may indicate a receiver address, a transmitter address, a destination address, and a source address of the frame, and some Address subfields may be omitted. For specific details of each subfield of the MAC header, including the Sequence Control, QoS Control, and HT Control subfields, refer to the IEEE 802.11 standard document.

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

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

Various forms of PPDUs are used in standards such as IEEE 802.11a/g/n/ac/ax. The basic PPDU format (IEEE 802.11a/g) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format can also be called a non-HT PPDU format (Fig. 7(a)).

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

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

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

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

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

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

The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated and mapped based on a predetermined subcarrier frequency interval (e.g., 312.5 kHz) so that even legacy STAs can attempt to demodulate and decode them. These can be referred to as pre-EHT modulated fields. Next, the EHT-STF, EHT-LTF, Data, and PE fields can be encoded and modulated and mapped based on a predetermined subcarrier frequency interval (e.g., 78.125 kHz) so that they can be demodulated and decoded by an STA that successfully decodes a non-legacy SIG (e.g., U-SIG and/or EHT-SIG) and obtains the information included in the corresponding fields. These can be referred to as EHT modulated fields.

Similarly, in the HE PPDU format, the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, and HE-SIG-B fields may be referred to as pre-HE modulation fields, and the HE-STF, HE-LTF, Data, and PE fields may be referred to as HE modulation fields. Additionally, in the VHT PPDU format, the L-STF, L-LTF, L-SIG, and VHT-SIG-A fields may be referred to as pre-VHT modulation fields, and the VHT STF, VHT-LTF, VHT-SIG-B, and Data fields may be referred to as VHT modulation fields.

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

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

Through U-SIG, for example, A uncoded bits can be transmitted, and a first symbol of U-SIG (e.g., U-SIG-1 symbol) can transmit the first X bits of information out of the total A bits of information, and a second symbol of U-SIG (e.g., U-SIG-2 symbol) can transmit the remaining Y bits of information out of the total A bits of information. The A bits of information (e.g., 52 uncoded bits) can include a CRC field (e.g., a field with a length of 4 bits) and a tail field (e.g., a field with a length of 6 bits). The tail field can be used to terminate the trellis of the convolutional decoder and can be set to 0, for example.

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

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

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

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

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

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

Preamble puncturing may mean transmission of a PPDU in which no signal is present in one or more frequency units within the bandwidth of the PPDU. For example, the size of the frequency unit (or the resolution of the preamble puncturing) may be defined as 20 MHz, 40 MHz, etc. For example, preamble puncturing may be applied to a PPDU bandwidth greater than a predetermined size.

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

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

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

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

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

An RU may include multiple subcarriers (or tones). An RU may be used when transmitting signals to multiple STAs based on the OFDMA technique. An RU may also be defined when transmitting signals to one STA. Resources may be allocated in RU units for non-legacy STFs, non-legacy LTFs, and Data fields.

According to the PPDU bandwidth, an applicable size of RU can be defined. The RU may be defined identically or differently for the applicable PPDU format (e.g., HE PPDU, EHT PPDU, UHR PPDU, etc.). For example, in case of 80MHz PPDU, the RU arrangements of HE PPDU and EHT PPDU may be different. The applicable RU size, RU number, RU position, DC (direct current) subcarrier position and number, null subcarrier position and number, guard subcarrier position and number, etc. for each PPDU bandwidth can be referred to as a tone plan. For example, a tone plan for a wide bandwidth can be defined in the form of multiple repetitions of a tone plan for a low bandwidth.

RUs of different sizes can be defined, such as 26-tone RU, 52-tone RU, 106-tone RU, 242-tone RU, 484-tone RU, 996-tone RU, 2Х996-tone RU, 4Х996-tone RU, etc. A multiple RU (MRU) is distinct from multiple individual RUs and corresponds to a group of subcarriers consisting of multiple RUs. For example, one MRU can be defined as 52+26-tones, 106+26-tones, 484+242-tones, 996+484-tones, 996+484+242-tones, 2Х996+484-tones, 3Х996-tones, or 3Х996+484-tones. Additionally, multiple RUs constituting one MRU may or may not be consecutive in the frequency domain.

The specific size of the RU may be reduced or expanded. Therefore, the specific size of each RU (i.e., the number of corresponding tones) in the present disclosure is not limited and is exemplary. In addition, within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, ...) in the present disclosure, the number of RUs may vary depending on the RU size.

The names of each field in the PPDU formats of FIG. 7 are exemplary, and the scope of the present disclosure is not limited by the names. In addition, the examples of the present disclosure can be applied not only to the PPDU format exemplified in FIG. 7, but also to a new PPDU format in which some fields are excluded and/or some fields are added based on the PPDU formats of FIG. 7.

Beamforming training

Beamforming training can determine appropriate receive and transmit antenna sectors for a pair of STAs. This can be achieved through the transmission of a bidirectional training frame sequence.

The beamforming phase is divided into two sub-phases. First, during the sector level sweep (SLS), an initial coarse-grain antenna sector configuration can be determined. This information is used in the subsequent optional beam refinement phase (BRP), where fine-tuning of the selected sectors can be performed.

First, we describe the operation in the SLS phase.

During SLS, two STAs can each train a transmit antenna sector or a receive antenna sector.

During SLS, a pair of stations can exchange a series of sector sweep (SSW) frames (or beacons in the case of sector training in a PCP/AP) across multiple antenna sectors to find the sector that provides the highest signal quality. For example, during SLS, each station can act once as the transmitter of the sweep and once as the receiver, as in Fig. 8.

Figure 8 illustrates a sector level sweep (SLS) step that may be applied to the present disclosure.

Referring to Figure 8, the STA that performs transmission first may correspond to an initiator, and the other STA that forms a pair may correspond to a responder.

The initiator's sweep and the responder's sweep can be utilized in two different ways, as shown in Fig. 9.

Figure 9 illustrates two types of sector sweeps that may be applied to the present disclosure.

Referring to FIG. 9, (a) of FIG. 9 represents a transmit sector sweep (TXSS), and (b) of FIG. 9 represents a receive sector sweep (RXSS).

During a transmit sector sweep (TXSS), frames are transmitted in different sectors while the pairing node can receive in a quasi-omnidirectional pattern. To identify the strongest transmitting sector, the transmitter can mark every frame with an identifier for the antenna and sector used.

Additionally, during a receive sector sweep (RXSS), transmissions in the same sector (the best known sector) can test the optimal receive sector at the pairing node. In general, there are four possible types of sweep combinations for SLS:

- Transmit sector sweep (TXSS) on both initiator and responder

- Receive sector sweep (RXSS) on both STAs

- Initiator RXSS and responder TXSS

- Initiator TXSS and responder RXSS

For the achieved optimal SNR and TXSS, the sector and antenna identifiers can be reported to the pairing node, and such SLS feedback can follow the structure illustrated in Fig. 7.

The feedback to the initiator is carried by every frame of the responder sector sweep, which can ensure reception under the yet unknown optimal antenna configuration. The feedback to the responder can be transmitted as a single SSW feedback PPDU/frame under the determined optimal antenna configuration. Finally, the SSW feedback PPDU/frame can be acknowledged by the responder with an SSW-ACK. The last PPDU/frame can be additionally used to negotiate the details of the subsequent BRP.

If the two STAs have sufficient transmit antenna gain, their SLS phase can be realized as pure transmit sector training, and the receive sector training can be postponed to a subsequent BRP. Additionally, the initiator can instruct/request the responder to perform a receive sector sweep by specifying the number of receive sectors to be trained during its sweep, i.e., the initiator's sweep. If the initiator sweep corresponds to receive sector training, additional signaling may be required before the SLS phase.

Next, we describe the operation in BRP.

BRP can refine the sectors discovered in the SLS phase. The sectors are determined using a non-uniform quasi-omni-directional antenna pattern and may have suboptimal signal quality. In addition, BRP can predict the optimization of antenna weight vectors regardless of the pre-defined sector pattern for the phased antenna array.

This allows us to increase the beam training search space while achieving additional throughput gains. Although the free variation of antenna weight vectors can lead to arbitrary antenna patterns, the directional characteristics can be preserved for antenna configurations that provide high throughput. Therefore, the training process for pre-defined directional sectors and antenna weight vector optimization can remain the same. Finally, if BRP is not part of the previous SLS, BRP can be used to train the receive antenna configuration.

A BRP transaction can evaluate a set of directional transmit or receive patterns for the best known directional configuration at the pairing node. Thus, incompleteness of quasi-omni-directional patterns can be avoided. Since BRP relies on the preceding SLS phase, reliable PPDU/frame exchange is ensured and different antenna configurations can be tested throughout the same PPDU/frame. This can significantly reduce transmission overhead, unlike SLS which requires the entire PPDU/frame to test a sector. In this regard, a Transmit and Receive Training field (TRN-T/R) can be added to the PPDU/frame exchanged during the BRP transaction to sweep the antenna configurations throughout the PPDU/frame. Each field can be transmitted or received with an antenna configuration to test signal quality. The remainder of the PPDU/frame can be transmitted and received with the best known antenna configuration.

BRP receive antenna training can be requested by specifying the number of configurations to be tested in the L-RX header field of a PPDU/frame. The pairing node can add that number of TRN-R fields to the next PPDU/frame. Transmit training can be requested by setting the TX-TRN-REQ header field and adding the TRN-T field to the same BRP PPDU/frame. Optionally, an acknowledgement PPDU/frame with no training fields added and the TX-TRN-OK field set can be transmitted by the receiver before the requester adds the TRN-T field to the next PPDU/frame. Similar to SLS, BRP feedback can be provided in the form of SNR for the best found configuration and, in case of transmit training, a best configuration ID.

Figure 10 illustrates a BRP transaction that can be applied to the present disclosure.

Referring to Figure 10, a BRP transaction can be configured to first train the receive configuration between two STAs and then perform additional transmit training refinement.

For example, STA B can combine the transmit and receive training requests into one PPDU/frame using the request variation described above. On the other hand, STA A can request two transmit directions using two PPDUs/frames.

The BRP phase may be initiated immediately following the SLS, using an SSW ACK frame for parameter exchange. Alternatively, the BRP phase may be initiated based on a special BRP setup sub-phase consisting of a BRP frame without a training field. In either case, the L-RX and TX-TRN-REQ fields may be used to exchange BRP parameters.

How to perform beamforming training for some sectors

In next-generation wireless LAN systems, mmWave bands including the 60 GHz band (i.e., not limited to the 60 GHz band) may be used to improve throughput and efficiency. In this case, beamforming may be essential due to the channel characteristics of the mmWave band.

However, since the beamforming training procedure for beamforming application may have a large overhead, the beamforming training procedure may need to be simplified to optimize efficiency. In this regard, a method of performing beam training only for certain sectors may be considered.

In this disclosure, a method for performing beam training only for certain sectors during beamforming training and a method for transmitting and receiving instruction information for the same are proposed through a detailed description.

FIG. 11 is a diagram showing regional examples of channelization of millimeter wave (mmWave) bands to which the present disclosure can be applied.

The example in Fig. 11 shows the mmWave bands used in the United States, the European Union, South Korea, Japan, Australia, and China, and shows the sizes and locations of channels defined in the bands. For example, the bandwidth of each of the six channels can correspond to 2.16 GHz. In addition, when bandwidth bonding is applied, up to four unit bandwidths can be bonded to support a bandwidth of up to 8.64 GHz.

Unlike conventional wireless LAN systems, technologies under discussion, such as UHR, are discussing using sub-7 GHz bands (e.g., 2.4 GHz, 5 GHz, or 6 GHz bands) and/or mmWave bands to achieve high data rates and low latency. For example, for specific use cases requiring high throughput, it may be difficult to satisfy the requirements with only the bandwidth of the currently defined channel, so transmitting/receiving specific PPDUs via the mmWave band may be considered.

In this regard, in the mmWave band, it is necessary to transmit PPDUs with beamforming applied due to channel characteristics, and for this purpose, the sector-level sweep (SLS) procedure and/or the beam refinement protocol (BRP) procedure may be essential. However, since the overhead of these procedures may be large, a method of simplifying the procedure(s) may be required to optimize efficiency.

To this end, as a method of performing beam training only for some sectors as described above, a method of instructing only some specific sectors during beamforming training is specifically described.

Control frames or elements for SLS procedures and/or BRP procedures in the mmWave band may be transmitted in the sub-7 GHz band.

For example, each STA(s) can exchange information about a transmit sector (TX sector) and/or a receive sector (RX sector) used for beam training in an SLS procedure and/or a BRP procedure, etc., by using the corresponding control frame or element. At this time, individual frames or elements can be defined for each of the SLS procedure and/or the BRP procedure, or the same frame or element can be used. When the same frame or element is used, necessary information can be transmitted by distinguishing between the SLS procedure and/or the BRP procedure, or the same information can be transmitted without distinguishing between them. As another example, before performing the SLS procedure and/or the BRP procedure, a frame for initiating the SLS procedure and/or the BRP procedure can be transmitted in the sub-7 GHz band. Each STA(s) can exchange information about a transmit sector and/or a receive sector used for beam training in the SLS procedure and/or the BRP procedure, etc., by using the corresponding frame.

In addition, the location of each STA(s) can be roughly identified through transmission/reception of specific frames and/or PPDUs in the sub-7 GHz band. Based on this, only some sectors, not all sectors, may be considered during beamforming training with a specific STA, and in this case, a signaling method for indicating the relevant some sectors needs to be defined.

The signaling may be additionally included in a control frame or element for the aforementioned SLS procedure and/or BRP procedure, or may be additionally included in a frame for the SLS procedure and/or BRP procedure. Various methods for the signaling are described below through embodiments.

Example 1

An STA transmitting a frame or element for an SLS procedure and/or a BRP procedure (or a frame for initiating an SLS procedure and/or a BRP procedure) may indicate a total number of transmit/receive sectors and a partial number of transmit/receive sectors in the frame or element. Here, the partial number of transmit/receive sectors may correspond to the number of shortlisted transmit/receive sectors for performing beam training for some sectors. In this case, a specific subfield may be defined for the indication, and a specific value may be defined using a certain bit to indicate a specific number.

In addition, in this regard, information about the lowest (or highest) sector ID (identifier) of some of the transmitting/receiving sectors may be indicated. Based on the indication, a specific subfield may be defined, and a specific value may be defined using a certain bit to indicate a specific sector ID. Based on this, it may be indicated that sector ID(s) corresponding to some of the transmitting/receiving sectors in sequence based on the sector ID will perform transmitting/receiving beamforming training in the SLS procedure and/or the BRP procedure. For example, consecutive sector IDs may be selected based on the indicated sector ID. When the lowest sector ID is indicated, sector ID(s) may be selected in sequence in an increasing order as many as the indicated number, and when the highest sector ID is indicated, sector ID(s) may be selected in sequence in a decreasing order as many as the indicated number.

In relation to the method, different subfields for the corresponding instructions may be defined for each transmitting sector and each receiving sector, or if both the transmitting sector and the receiving sector are the same, the instructions may be performed through a single subfield.

The method can be efficient in terms of reducing the overhead of the SLS procedure and/or the BRP procedure.

Additionally or alternatively, the instructions for some sectors may be performed based on a bitmap scheme. That is, in a bitmap scheme, the IDs of specific sectors to be selected for efficient beamforming training may be indicated. For example, each bit of the bitmap may be mapped sequentially to a low sector ID or a high sector ID, and 0 or 1 may indicate whether to select the corresponding beamforming training. This may increase overhead when the number of sectors increases, but has the technical effect of allowing non-continuous sector IDs to be selected. In this regard, different subfields for the instructions may be defined for each transmitting sector and each receiving sector, or when both the transmitting sector and the receiving sector are the same, the instructions may be performed through a single subfield.

Example 2

An STA transmitting a frame or element for an SLS procedure and/or a BRP procedure (or a frame for initiating an SLS procedure and/or a BRP procedure) may reset IDs of some transmit/receive sectors in the frame or element, where the number of some transmit/receive sectors may correspond to the number of shortlisted transmit/receive sectors for performing beam training for some sectors.

For example, rather than using the existing sector ID, the sector IDs can be reallocated in the order of the lowest or highest sector ID among the selected sectors (e.g., selected for beamforming training for some sectors). In this case, the sector IDs with a value of 0 can be allocated first.

Based on this, some number of transmit/receive sectors may be indicated without indicating the total number of transmit/receive sectors, and additional instructions may be unnecessary.

In relation to the method, different subfields for the corresponding instructions may be defined for each transmitting sector and each receiving sector, or if both the transmitting sector and the receiving sector are the same, the instructions may be performed through a single subfield.

This method has a technical effect of reducing overhead compared to the aforementioned methods (e.g., embodiment 1).

In connection with embodiments of the present disclosure, when transmitting a PPDU for an SLS procedure and/or a BRP procedure in a (real) mmWave band, information on a sector ID (e.g., a transmission sector ID) in which the corresponding PPDU is transmitted may be carried. For example, the information may be transmittable in a physical signaling (PHY signaling) field in the PPDU or a MAC frame. A receiving side (e.g., an STA that has received the corresponding PPDU) may feed back information on an optimal transmission sector ID (to the transmitting side) based on information received in a sub-7 GHz band. Additionally, when providing feedback, the receiving side may transmit the feedback by including a field (e.g., a training (TRN) field) for reception beamforming training of an STA receiving the feedback. In this case, the field may be configured using sector information used in reception beamforming training received in the sub-7 GHz band.

In addition, with respect to the embodiments of the present disclosure, unlike the manner of indicating information about some of the transmission/reception sectors of an STA transmitting a frame or element for an SLS procedure and/or a BRP procedure (or a frame for initiating an SLS procedure and/or a BRP procedure), a manner of indicating information about some of the transmission/reception sectors of an STA receiving the corresponding frame or element may also be considered. Here, the number of some of the transmission/reception sectors may correspond to the number of shortlisted transmission/reception sectors for performing beam training for some of the sectors. In this case, the indication may be performed in a manner identical/similar to the manner described above in the present disclosure. However, information about all of the sectors of the receiving STA may be required before transmitting the corresponding frame or element, and the information may be exchanged/obtained through capability negotiation, etc. Additionally, based on the information, when transmitting a PPDU for an SLS procedure and/or a BRP procedure in the (actual) mmWave band, a field (e.g., a training (TRN) field) for receiving beamforming training of an STA receiving the PPDU may be inserted. In this case, the field may be configured using sector information used in receiving beamforming training.

In addition, in connection with embodiments of the present disclosure, when scheduling an SLS procedure and/or a BRP procedure, a procedure for all transmit/receive sectors may be scheduled in specific time/frequency resources, and a procedure for some transmit/receive sectors may be scheduled in other time/frequency resources. In this regard, information (e.g., 1-bit information) for indicating a procedure for all transmit/receive sectors or a procedure for some transmit/receive sectors may be additionally transmitted/received/exchanged between STAs. As an example, the information may be conveyed in a frame for initiating an SLS procedure and/or a BRP procedure.

Hereinafter, the operation of the STA according to the embodiment of the present disclosure described above will be described with reference to FIGS. 12 and 13. That is, the examples of FIGS. 12 and 13 may correspond to some of the various examples of the present disclosure.

FIG. 12 illustrates the operation of a first STA according to an embodiment of the present disclosure.

Referring to FIG. 12, the first STA can transmit one or more first frames for beamforming training based on M (M<N) sectors out of the total N (N>1) sectors to the second STA (S1210). That is, beamforming training based on only some sectors out of the total sectors can be performed between the first STA and the second STA.

For example, the beamforming training may include one or more of a first procedure for a sector level sweep or a second procedure for a beam refinement protocol. Also, for example, for the beamforming training, the first STA may correspond to an initiator and the second STA may correspond to a responder. Also, for example, the first frame may be for beamforming training for a transmission sector of the first STA.

Thereafter, the first STA can receive a second frame (e.g., a feedback frame) including information about the best sector among the aforementioned M sectors from the second STA (S1220).

In this regard, prior to the beamforming training, information about some sectors, i.e., the M sectors described above, may be exchanged between the first STA and the second STA.

According to the present disclosure, the information about the M sectors may include at least one of the number of sectors (e.g., M) or a specific sector ID, wherein the specific sector ID may correspond to a highest sector ID or a lowest sector ID among the M sectors. For example, if the number of sectors and the highest sector ID are included in the information about the M sectors, the corresponding M sectors may correspond to sectors having IDs in descending order based on the highest sector ID. On the other hand, if the number of sectors and the lowest sector ID are included in the information about the M sectors, the corresponding M sectors may correspond to sectors having IDs in ascending order based on the lowest sector ID.

Additionally, according to the present disclosure, information about the M sectors may be based on a bitmap scheme where each bit is mapped to a sector ID. For example, a scheme may be applied in which M bits are set to specific values (e.g., 0 or 1) in a bitmap consisting of N bits based on a total of N sectors to indicate some of the M sectors.

In addition, according to the present disclosure, when the transmitting sector and the receiving sector are different from each other, the information about the aforementioned M sectors can be set individually (e.g., via individual (sub)fields) for the transmitting sector and the receiving sector. On the other hand, when the transmitting sector and the receiving sector are the same, the information about the aforementioned M sectors can be set via one (sub)field for the transmitting sector and the receiving sector.

Additionally, according to the present disclosure, information about the M sectors described above may be included in a control frame for beamforming training or may be included in a frame for initiating the beamforming training.

Additionally, according to the present disclosure, information about the above-mentioned M sectors may be exchanged in a first operating frequency band, and beamforming training may be performed in a second operating frequency band different from the first operating frequency band. For example, the first operating frequency band may correspond to one of a 2.4 GHz band, a 5 GHz band, or a 6 GHz band (e.g., a sub-7 GHz band), and the second operating frequency band may correspond to a millimeter wave (mmWave) band or a 60 GHz band.

Additionally, according to the present disclosure, the second frame transmitted by the second STA may further include a training field for receiving beamforming training by the first STA.

Additionally, according to the present disclosure, a first beamforming training type based on all N sectors in a specific time resource or a specific frequency resource may be scheduled, and a second beamforming training type based on some M sectors in another time resource or another frequency resource may be scheduled. In this regard, information indicating a beamforming training type (e.g., one of the first beamforming training type or the second beamforming training type) may be included in a frame for initiating beamforming training.

The method performed by the first STA described in the example of FIG. 12 may be performed by the first device (100) of FIG. 1. For example, one or more processors (102) of the first device (100) of FIG. 1 may be configured to transmit, through one or more transceivers (106), one or more first frames for beamforming training based on some M sectors out of the total N sectors, and receive a second frame including information about a best sector out of the M sectors. Furthermore, one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 12 or the examples described above when executed by one or more processors (102).

FIG. 13 illustrates the operation of a second STA according to an embodiment of the present disclosure.

Referring to FIG. 13, the second STA may receive one or more first frames for beamforming training based on M (M<N) sectors out of the total N (N>1) sectors from the first STA (S1310). That is, beamforming training based on only some sectors out of the total sectors may be performed between the first STA and the second STA.

For example, the beamforming training may include one or more of a first procedure for a sector level sweep or a second procedure for a beam refinement protocol. Also, for example, for the beamforming training, the first STA may correspond to an initiator and the second STA may correspond to a responder. Also, for example, the first frame may be for beamforming training for a transmission sector of the first STA.

Thereafter, the second STA can transmit a second frame (e.g., a feedback frame) including information about the best sector among the aforementioned M sectors to the first STA (S1320).

In this regard, prior to the beamforming training, information about some sectors, i.e., the M sectors described above, may be exchanged between the first STA and the second STA.

In the example of Fig. 13, the specific details of the configuration of information for the M sectors, the transmission method, the operating frequency band, the training field, the scheduling of beamforming training, etc. are the same as those described in the example of Fig. 12, so redundant descriptions are omitted.

The method performed by the second STA described in the example of FIG. 13 may be performed by the second device (200) of FIG. 1. For example, one or more processors (202) of the second device (200) of FIG. 1 may be configured to receive one or more first frames for beamforming training based on M sectors out of the total N sectors through one or more transceivers (206), and transmit a second frame including information about a best sector out of the M sectors. Furthermore, one or more memories (204) of the second device (200) may store commands for performing the method described in the example of FIG. 13 or the examples described above when executed by one or more processors (202).

FIG. 14 is a diagram for explaining a PPDU transmission and reception procedure between a transmitting STA and a receiving STA according to an embodiment of the present disclosure.

For example, with respect to the procedure in FIG. 14, a PPDU that can be used in the mmWave band of a UHR system may include UHR-STF, UHR-LTF, UHR-SIG, and data. All or part of each part (e.g., field) may be divided into one or more subparts (e.g., subfields).

In this regard, each field (and its subfields) can be transmitted in units of 4/N us * M (where N is an upclocking factor and M is an integer). UHR-STF can be transmitted in integer multiples of 0.8/N us. For example, UHR-STF can be transmitted in 0.8/N us * 10. In addition, a Guard Interval/N (or Short GI/N) of a conventional wireless LAN system (e.g., WiFi) standard can be included. A common subcarrier frequency spacing value (e.g., delta_f = 312.5 kHz * N/M, where N = integer) can be applied to all of the fields.

Also, some of the UHR-STF, UHR-LTF, UHR-SIG, and data may be omitted. For example, in a PPDU for a specific purpose (e.g., SLS), data or UHR-SIG may not be present. For another example, a training field (e.g., training field) may be present at the end of a PPDU for a specific purpose.

For example, UHR-STF may be configured with conventional L-STF or VHT-STF or HE-STF or EHT-STF, and may include fields for CFO estimation and AGC. In addition, UHR-LTF may be configured with conventional L-LTF or VHT-LTF or HE-LTF or EHT-LTF, and may include fields for CFO estimation and channel estimation. In addition, UHR SIG may include various control information for transmitted PPDU. For example, it may include control information for decoding data, control information for SLS, etc. In addition, data may include user data and packets for upper layers. That is, it may include MPDU (e.g., MAC frame). In particular, in case of PPDU for SLS, data may include information for SLS.

Some of the procedures described in FIG. 14 below may be omitted or changed.

The transmitting STA can obtain control information for transmitting the PPDU (S1410). For example, the transmitting STA can obtain channel information and bandwidth information of the mmWave band in which the PPDU will be transmitted. In addition, in the case of PPDU transmission for SLS, the transmitting STA can obtain information about each sector. In this regard, information about only some sectors, not all sectors, may be indicated.

The transmitting STA may configure/generate a PPDU based on the acquired control information (S1420). The step of configuring/generating the PPDU may include a step of configuring/generating each field of the PPDU. For example, the step of configuring/generating the PPDU may include a step of configuring UHR-STF/UHR-LTF applicable to a bandwidth. In addition, the step of configuring/generating the PPDU may include a step of configuring a UHR-SIG field including information such as a bandwidth. In addition, when transmitting a PPDU for SLS/BRP, the step of configuring/generating the PPDU may include a step of configuring a UHR-SIG field including control information regarding the SLS/BRP. In addition, the step of configuring/generating the PPDU may include a step of generating a data field (e.g., MPDU) transmitted in the bandwidth. In addition, the step of configuring/generating the PPDU may include a step of generating a Data part (e.g., MPDU) including information regarding the SLS/BRP when transmitting a PPDU for SLS/BRP.

The transmitting STA can transmit the PPDU configured as described above to the receiving STA. In the process of transmitting the PPDU, the transmitting STA can perform at least one of the following operations: upclocking, CSD, spatial mapping, IDFT/IFFT operation, GI insertion, etc.

The receiving STA may receive all or part of the PPDU (S1440). For example, the receiving STA may perform an operation to restore the results of operations such as upclocking, CSD, spatial mapping, IDFT/IFFT operation, and GI insertion applied during the transmission process of the PPDU.

A receiving STA can decode all or part of a PPDU, and obtain control information (e.g., information such as bandwidth) from the decoded PPDU (S1450). For example, the receiving STA can decode the UHR-SIG of the PPDU based on the UHR-STF / UHR-LTF, and obtain information included in the UHR-SIG field. Various information described in the present disclosure can be included in the UHR-SIG, and the receiving STA can obtain information about the PPDU through the UHR-SIG. In particular, when receiving a PPDU for SLS, the receiving STA can obtain control information about SLS, etc. through the corresponding PPDU.

The receiving STA can decode the data field of the PPDU based on the information acquired as described above and acquire the MPDU included in the data field (S1460). In addition, the receiving STA can perform a processing operation for transmitting the decoded data to a higher layer (e.g., MAC layer). In addition, if the generation of a signal is instructed from the higher layer to the PHY layer in response to the data transmitted to the higher layer, the receiving STA can perform a subsequent operation.

The proposed method in this disclosure is a method for performing beamforming training for some sectors in a mmWave band. According to the proposed method in this disclosure, a new effect can be achieved of improving throughput and/or efficiency in a newly defined operating band (e.g., mmWave band, etc.) and reducing overhead by performing beamforming training only for some sectors.

The embodiments described above are combinations of components and features of the present disclosure in a given form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, it is also possible to combine some components and/or features to form an embodiment of the present disclosure. The order of operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is obvious that claims that do not have an explicit citation relationship in the scope of the patent may be combined to form an embodiment or may be included as a new claim by post-application amendment.

It will be apparent to those skilled in the art that the present disclosure may be embodied in other specific forms without departing from the essential characteristics of the present disclosure. Accordingly, the above detailed description should not be construed as limiting in all respects but should be considered as illustrative. The scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present disclosure are intended to be included in the scope of the present disclosure.

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

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

Claims (18)

A step of transmitting, by a first station (STA), one or more first frames for beamforming training based on M (M<N) sectors out of a total of N (N>1) sectors to a second STA; and A step of receiving, by the first STA, a second frame including information about a best sector among the M sectors from the second STA, A method in which information about the M sectors is exchanged between the first STA and the second STA prior to the beamforming training. In the first paragraph, The information about the above M sectors includes at least one of the number of sectors or a specific sector ID, A method wherein the specific sector ID corresponds to the highest sector ID or the lowest sector ID among the M sectors. In the second paragraph, A method wherein, based on the number of sectors and the highest sector ID being included in the information about the M sectors, the M sectors correspond to sectors having IDs in descending order based on the highest sector ID. In the second paragraph, A method wherein, based on the number of sectors and the lowest sector ID being included in the information about the M sectors, the M sectors correspond to sectors having IDs in ascending order based on the lowest sector ID. In the first paragraph, A method in which information about the above M sectors is based on a bitmap method in which each bit is mapped to a sector ID. In the first paragraph, A method wherein information about the M sectors is individually set for the transmitting sector and the receiving sector based on differences between the transmitting sector and the receiving sector. In the first paragraph, A method wherein information about the M sectors is included in a control frame for the beamforming training or included in a frame for initiating the beamforming training. In the first paragraph, Information about the above M sectors is exchanged in the first operating frequency band, A method wherein the beamforming training is performed in a second operating frequency band different from the first operating frequency band. In Article 8, The above first operating frequency band corresponds to one of the 2.4 GHz band, the 5 GHz band, or the 6 GHz band, The above second operating frequency band corresponds to a millimeter wave (mmWave) band or a 60 GHz band. In the first paragraph, A method, wherein the second frame further includes a training field for receiving beamforming training by the first STA. In the first paragraph, A method wherein the beamforming training comprises at least one of a first procedure for a sector level sweep or a second procedure for a beam refinement protocol. In the first paragraph, A first beamforming training type based on the above N sectors in a specific time resource or a specific frequency resource is scheduled, A method wherein a second beamforming training type based on the M sectors is scheduled on different time resources or different frequency resources. In Article 12, A method wherein information indicating one of the first beamforming training type or the second beamforming training type is included in a frame for initiating beamforming training. one or more transmitters and receivers; and comprising one or more processors coupled to said one or more transceivers; One or more of the above processors: By a first station (STA), one or more first frames for beamforming training based on M (M<N) sectors out of a total of N (N>1) sectors are transmitted to a second STA; By the first STA, a second frame including information about the best sector among the M sectors is set to be received from the second STA, A device in which information about the M sectors is exchanged between the first STA and the second STA prior to the beamforming training. A step of receiving, by a second station (STA), one or more first frames for beamforming training based on M (M<N) sectors out of a total of N (N>1) sectors from a first STA; and A step of transmitting, by the second STA, a second frame including information about the best sector among the M sectors to the first STA, A method in which information about the M sectors is exchanged between the first STA and the second STA prior to the beamforming training. one or more transmitters and receivers; and comprising one or more processors coupled to said one or more transceivers; One or more of the above processors: By a second station (STA), one or more first frames for beamforming training based on M (M<N) sectors out of a total of N (N>1) sectors are received from the first STA; By the second STA, a second frame including information about the best sector among the M sectors is set to be transmitted to the first STA, A device in which information about the M sectors is exchanged between the first STA and the second STA prior to the beamforming training. one or more processors; and A processing device comprising one or more computer memories operatively connected to said one or more processors and storing instructions for performing a method according to any one of claims 1 to 13 based on execution by said one or more processors. One or more non-transitory computer-readable media storing one or more instructions that are executed by one or more processors to perform a method according to any one of claims 1 to 13.

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