Method and device for discovering multi-link device in wireless LAN system

Abstract

Disclosed are a method and device for discovering a multi-link device in a wireless LAN system. The method according to an embodiment of the present disclosure may comprise the steps in which: a first STA belonging to a first MLD receives a first frame through a first link from a first AP that belongs to a second MLD and operates in a first band, wherein the first frame includes information related to a second AP that belongs to the second MLD and operates in a second band different from the first band; and the first STA performs a multi-link setup procedure for setting up the first link between the first STA and the first AP and a second link between the second AP and a second STA belonging to the first MLD.

Description

Method and device for discovering multi-link devices in a wireless LAN system

[0001] The present disclosure relates to a method and device for discovering a multi-link device (MLD) in a wireless local area network (WLAN) system.

[0002] New technologies have been introduced for wireless local area networks (WLANs) to improve transmission rates, increase bandwidth, enhance reliability, reduce errors, and reduce latency. Among WLAN technologies, the IEEE (Institute of Electrical and Electronics Engineers) 802.11 series of standards can be referred to as Wi-Fi. For example, recently introduced technologies for WLANs include enhancements for Very High Throughput (VHT) in the 802.11ac standard and enhancements for High Efficiency (HE) in the IEEE 802.11ax standard.

[0003] To provide a more advanced wireless communication environment, improved technologies for Extremely High Throughput (EHT) are being discussed. For example, technologies for Multiple Input Multiple Output (MIMO), which supports increased bandwidth, efficient utilization of multiple bands, and increased spatial streams, and for coordination of multiple access points (APs), are being studied. In particular, various technologies are being studied to support low latency or real-time traffic. Furthermore, new technologies are being discussed to support ultra-high reliability (UHR), including improvements or extensions of EHT technology.

[0004] The technical problem of the present disclosure is to provide a method and device for discovering a multi-link device (MLD).

[0005] In addition, an additional technical problem of the present disclosure is to provide a method and a device for transmitting and receiving information for discovering an access point or non-access point station operating in a different band (e.g., millimeter wave (mmWave) band) while belonging to the same MLD.

[0006] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0007] A method according to one aspect of the present disclosure may include: receiving, by a first station (STA) belonging to a first multi-link device (MLD), a first frame via a first link from a first access point (AP) belonging to a second MLD and operating in a first band, the first frame including information related to a second AP belonging to the second MLD and operating in a second band different from the first band; and performing, by the first STA, a multi-link setup procedure for setting up the first link between the first STA and the first AP and the second link between a second STA belonging to the first MLD and the second AP.

[0008] A method according to an additional aspect of the present disclosure may include: transmitting, by a first access point (AP) belonging to a second multi-link device (MLD) and operating in a first band, a first frame to a first station (STA) belonging to a first MLD via a first link, the first frame including information related to a second AP belonging to the second MLD and operating in a second band different from the first band; and performing, by the first AP, a multi-link setup procedure for setting up the first link between the first STA and the first AP and the second link between a second STA belonging to the first MLD and the second AP.

[0009] According to the present disclosure, it is possible to discover access points or non-access point stations that belong to the same MLD but operate in different bands (e.g., millimeter wave (mmWave) bands).

[0010] In addition, according to the present disclosure, wireless transmission and reception efficiency can be improved because association (i.e., multi-link setup) and frame exchange can be performed with an access point or non-access point station operating in a different band (e.g., millimeter wave (mmWave) band).

[0011] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the description below.

[0012] The accompanying drawings, which are incorporated in and are part of the detailed description to aid in understanding the present disclosure, provide embodiments of the present disclosure and, together with the detailed description, describe the technical features of the present disclosure.

[0013] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0014] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0015] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0016] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0017] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0018] FIG. 6 is a drawing for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0019] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0020] Figure 8 exemplarily shows the structure of an ML element to which the present disclosure can be applied.

[0021] FIG. 9 illustrates an AP MLD and a non-AP MLD supporting the mmWave band according to one embodiment of the present disclosure.

[0022] FIG. 10 illustrates a reduced neighbor report element format in a wireless communication system to which the present disclosure may be applied.

[0023] FIG. 11 illustrates the format of a per-STA profile subelement within a multi-link element in a wireless communication system to which the present disclosure may be applied.

[0024] FIG. 12 is a diagram illustrating channelization in a wireless communication system to which the present disclosure can be applied.

[0025] FIG. 13 illustrates the operation of a multi-link device for a method of discovering a multi-link device according to one embodiment of the present disclosure.

[0026] FIG. 14 illustrates the operation of a multi-link device for a method of discovering a multi-link device according to one embodiment of the present disclosure.

[0027] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description set forth below, together with the accompanying drawings, is intended to explain exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure may be practiced. The following detailed description includes specific details to provide a thorough understanding of the present disclosure. However, one of ordinary skill in the art will appreciate that the present disclosure may be practiced without these specific details.

[0028] In some cases, to avoid obscuring the concepts of the present disclosure, known structures and devices may be omitted or illustrated in block diagram form focusing on the core functions of each structure and device.

[0029] In the present disclosure, when a component is said to be "connected," "coupled," or "connected" to another component, this may include not only a direct connection but also an indirect connection in which another component exists between them. Furthermore, the terms "comprises" or "has" in the present disclosure specify the presence of the mentioned features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0030] In this disclosure, terms such as "first," "second," etc. are used only to distinguish one component from another, are not used to limit the components, and do not limit the order or importance of components unless specifically stated otherwise. Accordingly, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0031] The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "and / or" as used herein may refer to any one of the associated enumerated items, or is meant to refer to and encompass any and all possible combinations of two or more of them. Furthermore, the use of " / " between words in this disclosure has the same meaning as "and / or" unless otherwise stated.

[0032] The examples of the present disclosure can be applied to various wireless communication systems. For example, the examples of the present disclosure can be applied to a wireless LAN system. For example, the examples of the present disclosure can be applied to a wireless LAN based on the IEEE 802.11a / g / n / ac / ax / be standards. Furthermore, the examples of the present disclosure can be applied to a wireless LAN based on the newly proposed IEEE 802.11bn (or UHR) standard. Additionally, the examples of the present disclosure can be applied to a wireless LAN based on the next-generation standard after IEEE 802.11bn. Furthermore, the examples of the present disclosure can be applied to a cellular wireless communication system. For example, the examples of the present disclosure can be applied to a cellular wireless communication system based on the LTE (Long Term Evolution) series of technologies and the 5G NR (New Radio) series of technologies of the 3rd Generation Partnership Project (3GPP) standard.

[0033] Below, technical features to which examples of the present disclosure can be applied are described.

[0034] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0035] The first device (100) and the second device (200) illustrated in FIG. 1 may be replaced with various terms such as a terminal, a wireless device, a WTRU (Wireless Transmit Receive Unit), a UE (User Equipment), an MS (Mobile Station), a UT (user terminal), an MSS (Mobile Subscriber Station), an MSS (Mobile Subscriber Unit), an SS (Subscriber Station), an AMS (Advanced Mobile Station), a WT (Wireless terminal), or simply a user. In addition, the first device (100) and the second device (200) may be replaced with various terms such as an access point (AP), a BS (Base Station), a fixed station, a Node B, a BTS (Base Transceiver System), a network, an AI (Artificial Intelligence) system, an RSU (road side unit), a repeater, a router, a relay, a gateway, etc.

[0036] The devices (100, 200) illustrated in FIG. 1 may also be referred to as stations (STAs). For example, the devices (100, 200) illustrated in FIG. 1 may be referred to by various terms such as transmitting device, receiving device, transmitting STA, and receiving STA. For example, the STAs (110, 200) may perform an AP (access point) role or a non-AP role. That is, in the present disclosure, the STAs (110, 200) may perform the functions of an AP and / or a non-AP. When the STAs (110, 200) perform an AP function, they may simply be referred to as APs, and when the STAs (110, 200) perform a non-AP function, they may simply be referred to as STAs. In addition, in the present disclosure, the APs may also be referred to as AP STAs.

[0037] Referring to FIG. 1, the first device (100) and the second device (200) can transmit and receive wireless signals through various wireless LAN technologies (e.g., IEEE 802.11 series). The first device (100) and the second device (200) can include interfaces for a medium access control (MAC) layer and a physical layer (PHY) that follow the provisions of the IEEE 802.11 standard.

[0038] In addition, the first device (100) and the second device (200) may additionally support various communication standards (e.g., 3GPP LTE series, 5G NR series standards, etc.) other than wireless LAN technology. In addition, the device of the present disclosure may be implemented as various devices such as a mobile phone, a vehicle, a personal computer, an AR (Augmented Reality) device, a VR (Virtual Reality) device, etc. In addition, the STA of the present specification may support various communication services such as voice calls, video calls, data communications, autonomous driving, MTC (Machine-Type Communication), M2M (Machine-to-Machine), D2D (Device-to-Device), and IoT (Internet-of-Things).

[0039] A first device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memories (104) and / or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (102) may process information in the memory (104) to generate first information / signal, and then transmit a wireless signal including the first information / signal via the transceiver (106). In addition, 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 code including instructions for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (102) and the memory (104) may be part of a communication modem / circuit / chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series). The transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In the present disclosure, a device may also mean a communication modem / circuit / chip.

[0040] The second device (200) includes one or more processors (202), one or more memories (204), and may further include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memories (204) and / or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (202) may process information in the memory (204) to generate third information / signals, and then transmit a wireless signal including the third information / signals via the transceivers (206). In addition, the processor (202) may receive a wireless signal including fourth information / signals via the transceivers (206), and then store information obtained from signal processing of the fourth information / signals in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software code including instructions for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present disclosure, a device may also mean a communication modem / circuit / chip.

[0041] Hereinafter, the hardware elements of the device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed in the present disclosure, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed in the present disclosure.

[0042] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. The descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed in this disclosure may be implemented using firmware or software configured to perform one or more processors (102, 202) or stored in one or more memories (104, 204) and driven by one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed in this disclosure may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions.

[0043] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0044] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or flowcharts of the present disclosure, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or flowcharts of the present disclosure, from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, or the like, as referred to in the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure, via one or more antennas (108, 208). In the present disclosure, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202).One or more transceivers (106, 206) may convert user data, control information, wireless signals / channels, etc. processed by one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or filter.

[0045] For example, one of the STAs (100, 200) may perform the intended operation of an AP, and the other of the STAs (100, 200) may perform the intended operation of a non-AP STA. For example, the transceivers (106, 206) of FIG. 1 may perform transmission and reception operations of signals (e.g., packets or PPDUs (Physical layer Protocol Data Units) according to IEEE 802.11a / b / g / n / ac / ax / be / bn, etc.). In addition, in the present disclosure, operations in which various STAs generate transmission and reception signals or perform data processing or calculations in advance for transmission and reception signals may be performed in the processors (102, 202) of FIG. 1. For example, an example of an operation for generating a transmission / reception signal or performing data processing or operation in advance for a transmission / reception signal may include 1) an operation for determining / obtaining / configuring / computing / decoding / encoding bit information of a field (SIG (signal), STF (short training field), LTF (long training field), Data, etc.) included in a PPDU, 2) an operation for determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) used for a field (SIG, STF, LTF, Data, etc.) included in a PPDU, 3) an operation for determining / configuring / obtaining a specific sequence (e.g., a pilot sequence, an STF / LTF sequence, an extra sequence applied to SIG) used for a field (SIG, STF, LTF, Data, etc.) included in a PPDU, 4) a power control operation and / or a power saving operation applied to an STA, 5) an operation related to determining / obtaining / configuring / computing / decoding / encoding an ACK signal, etc. Additionally, in the examples below, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs for determining / acquiring / configuring / computing / decoding / encoding transmission / reception signals can be stored in the memory (104, 204) of FIG. 1.

[0046] Hereinafter, downlink (DL) refers to a link for communication from an AP STA to a non-AP STA, and downlink PPDUs / packets / signals, etc. can be transmitted and received through the downlink. In downlink communication, the transmitter may be part of an AP STA, and the receiver may be part of a non-AP STA. Uplink (UL) refers to a link for communication from a non-AP STA to an AP STA, and uplink PPDUs / packets / signals, etc. can be transmitted and received through the uplink. In uplink communication, the transmitter may be part of a non-AP STA, and the receiver may be part of an AP STA.

[0047] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0048] The structure of a wireless LAN system can be composed of multiple components. Through the interaction of multiple components, a wireless LAN that supports transparent STA mobility to the upper layer can be provided. A Basic Service Set (BSS) corresponds to a basic building block of a wireless LAN. FIG. 2 illustrates, by way of example, the existence of two BSSs (BSS1 and BSS2) and the inclusion of two STAs as members of each BSS (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2). The oval representing a BSS in FIG. 2 can also be understood as representing a coverage area in which STAs included in the corresponding BSS maintain communication. This area can be referred to as a Basic Service Area (BSA). When an STA moves outside of a BSA, it cannot directly communicate with other STAs within the BSA.

[0049] If we do not consider the DS illustrated in Figure 2, the most basic type of BSS in a wireless LAN is an Independent BSS (IBSS). For example, an IBSS can have a minimal form consisting of only two STAs. For example, assuming other components are omitted, BSS1 consisting of only STA1 and STA2, or BSS2 consisting of only STA3 and STA4, can be representative examples of an IBSS, respectively. Such a configuration is possible when the STAs can communicate directly without an AP. Furthermore, in this type of WLAN, a LAN can be configured when needed rather than being planned in advance, and this can be called an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity. That is, in an IBSS, STAs are managed in a distributed manner. In IBSS, all STAs can be mobile STAs, and access to distributed systems (DS) is not permitted, forming a self-contained network.

[0050] An STA's membership in a BSS can dynamically change, for example, when an STA is turned on or off, or when an STA enters or leaves a BSS area. To become a member of a BSS, an STA can join the BSS using a synchronization process. To access all services in the BSS infrastructure, an STA must be associated with the BSS. This association can be dynamically established and may involve the use of a Distribution System Service (DSS).

[0051] In a wireless LAN, the direct STA-to-STA distance can be limited by PHY performance. While this distance limit may be sufficient in some cases, communication between STAs over longer distances may be required in other cases. To support extended coverage, a distributed system (DS) can be configured.

[0052] DS refers to a structure in which BSSs are interconnected. Specifically, a BSS may exist as an extended component of a network composed of multiple BSSs, as illustrated in Figure 2. DS is a logical concept and can be specified by the characteristics of a distributed system medium (DSM). In this regard, the Wireless Medium (WM) and DSM can be logically distinguished. Each logical medium is used for a different purpose and by different components. These media are neither limited to being identical nor limited to being different. This logical difference between multiple media explains the flexibility of the WLAN architecture (DS architecture or other network architectures). In other words, the WLAN architecture can be implemented in various ways, and the physical characteristics of each implementation can independently specify the WLAN architecture.

[0053] A DS can support mobile devices by providing seamless integration of multiple BSSs and the logical services necessary to handle addresses to destinations. Additionally, a DS may further include a component called a portal, which acts as a bridge for connecting wireless LANs to other networks (e.g., IEEE 802.X).

[0054] An AP is an entity that enables access to a DS through a WM for associated non-AP STAs and also has the functionality of an STA. Data movement between a BSS and a DS can be performed through an AP. For example, STA2 and STA3 illustrated in FIG. 2 have the functionality of an STA and provide the function of allowing associated non-AP STAs (STA1 and STA4) to access the DS. In addition, since all APs are basically STAs, all APs are addressable entities. The address used by an AP for communication on a WM and the address used by an AP for communication on a DSM do not necessarily have to be the same. A BSS consisting of an AP and one or more STAs can be referred to as an infrastructure BSS.

[0055] Data transmitted from one of the STA(s) associated with an AP to the STA address of that AP may always be received on an uncontrolled port and processed by an IEEE 802.1X port access entity. In addition, if the controlled port is authenticated, the transmitted data (or frame) may be forwarded to the DS.

[0056] In addition to the structure of the DS described above, an extended service set (ESS) may be established to provide wider coverage.

[0057] An ESS is a network of arbitrary size and complexity, consisting of DSs and BSSs. An ESS may correspond to a set of BSSs connected to a DS. However, an ESS does not include a DS. An ESS network is characterized by appearing as an IBSS at the Logical Link Control (LLC) layer. STAs within an ESS can communicate with each other, and mobile STAs can move from one BSS to another (within the same ESS) transparently to the LLC. APs within an ESS may have the same SSID (service set identification). The SSID is distinct from the BSSID, which is the identifier of the BSS.

[0058] In a wireless LAN system, no assumptions are made about the relative physical locations of BSSs, and all of the following configurations are possible: BSSs can be partially overlapping, which is commonly used to provide continuous coverage. BSSs can also be physically disconnected, and there is no logical distance limit between them. BSSs can also be physically co-located, which can be used to provide redundancy. Furthermore, one (or more) IBSS or ESS networks can physically co-exist with one (or more) ESS networks. This can occur in cases where an ad-hoc network operates at the same location as an ESS network, where physically overlapping wireless networks are configured by different organizations, or where two or more different access and security policies are required at the same location.

[0059] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0060] For an STA to set up a link and transmit and receive data on a network, it must first discover the network, perform authentication, establish an association, and complete security authentication procedures. The link setup process can also be referred to as the session initiation process or session setup process. Furthermore, the discovery, authentication, association, and security setup processes of the link setup process can be collectively referred to as the association process.

[0061] In step S310, the STA may perform a network discovery operation. This network discovery operation may include scanning operations by the STA. That is, for the STA to access a network, it must search for available networks. Before joining a wireless network, the STA must identify compatible networks. The process of identifying networks in a specific area is called scanning.

[0062] Scanning methods include active scanning and passive scanning. Figure 3 illustrates a network discovery operation including an active scanning process as an example. In active scanning, an STA performing scanning transmits a probe request frame to discover any APs in the vicinity while moving between channels and waits for a response. The responder transmits a probe response frame in response to the STA that transmitted the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame in the BSS of the channel being scanned. In the BSS, the AP transmits the beacon frame, so the AP becomes the responder. In the IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not fixed. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning (i.e., transmitting and receiving probe requests / responses on channel 2) in the same manner.

[0063] Although not shown in Figure 3, the scanning operation can also be performed in a passive scanning manner. In passive scanning, the STA performing the scanning moves between channels and waits for a beacon frame. A beacon frame is one of the management frames defined in IEEE 802.11. It announces the existence of a wireless network and is periodically transmitted so that the STA performing the scanning can find the wireless network and participate in the wireless network. In the BSS, the AP performs the role of periodically transmitting the beacon frame, and in the IBSS, the STAs within the IBSS take turns transmitting the beacon frame. When the STA performing the scanning receives a beacon frame, it stores the information about the BSS included in the beacon frame and moves to another channel, recording the beacon frame information on each channel. The STA receiving the beacon frame stores the BSS-related information included in the received beacon frame and moves to the next channel to perform scanning on the next channel in the same manner. Comparing active scanning and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.

[0064] After the STA discovers the network, an authentication process may be performed in step S320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation of step S340 described below.

[0065] The authentication process involves the STA sending an authentication request frame to the AP, and the AP responding by sending an authentication response frame to the STA. The authentication frame used for the authentication request / response corresponds to a management frame.

[0066] The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), and a Finite Cyclic Group. These are just some examples of information that may be included in an authentication request / response frame, and may be replaced with other information or include additional information.

[0067] An STA can send an authentication request frame to an AP. The AP can determine whether to grant authentication to the STA based on the information contained in the received authentication request frame. The AP can provide the result of the authentication process to the STA via an authentication response frame.

[0068] 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.

[0069] 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, an RSN, a mobility domain, supported operating classes, a Traffic Indication Map Broadcast request, interworking service capabilities, etc. For example, the association response frame may include information about various capabilities, a status code, an Association ID (AID), supported rates, an Enhanced Distributed Channel Access (EDCA) parameter set, a Received Channel Power Indicator (RCPI), a Received Signal to Noise Indicator (RSNI), a mobility domain, a timeout interval (e.g., an association comeback time), overlapping BSS scan parameters, a TIM broadcast response, a Quality of Service (QoS) map, etc. These are just some examples of information that may be included in a combined request / response frame, and may be replaced by other information or include additional information.

[0070] After the STA successfully joins the network, a security setup process may be performed in step S340. The security setup process in step S340 may be referred to as an authentication process through a Robust Security Network Association (RSNA) request / response, the authentication process in step S320 may be referred to as a first authentication process, and the security setup process in step S340 may also be referred to simply as an authentication process.

[0071] The security setup process of step S340 may include, for example, a process of establishing a private key through a four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame. Furthermore, the security setup process may be performed according to a security method not defined in the IEEE 802.11 standard.

[0072] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0073] In wireless LAN systems, the basic access mechanism of MAC (Medium Access Control) is Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). The CSMA / CA mechanism, also known as the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC, essentially employs a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or STA may perform a Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time period (e.g., a DCF Inter-Frame Space (DIFS)) before starting transmission. If the sensing result determines that the medium is in an idle state, the AP and / or STA may start transmitting frames through the medium. On the other hand, if the medium is detected to be occupied or busy, the AP and / or STA may not start its own transmission, but may wait for a delay period (e.g., a random backoff period) for medium access before attempting to transmit frames. By applying a random backoff period, multiple STAs are expected to attempt to transmit frames after waiting for different periods of time, thereby minimizing collisions.

[0074] In addition, the IEEE 802.11 MAC protocol provides the Hybrid Coordination Function (HCF). The HCF is based on the DCF and the Point Coordination Function (PCF). The PCF is a polling-based synchronous access method that periodically polls all receiving APs and / or STAs to ensure that they receive data frames. In addition, the HCF has the Enhanced Distributed Channel Access (EDCA) and the HCF Controlled Channel Access (HCCA). The EDCA is a contention-based access method for a provider to provide data frames to multiple users, while the HCCA uses a non-contention-based channel access method that utilizes a polling mechanism. In addition, the HCF includes a medium access mechanism to improve the Quality of Service (QoS) of the wireless LAN, and can transmit QoS data in both the Contention Period (CP) and the Contention Free Period (CFP).

[0075] Referring to Fig. 4, an operation based on a random backoff period is described. When a medium that was occupied / busy changes to an idle state, multiple STAs can attempt to transmit data (or frames). To minimize collisions, each STA can select a random backoff count, wait for the corresponding slot time, and then attempt transmission. The random backoff count has a pseudo-random integer value and can be determined as one of the values ​​in the range of 0 to CW. Here, CW is a contention window parameter value. The CW parameter is given an initial value of CWmin, but can take a value doubled in case of transmission failure (e.g., when an ACK for a transmitted frame is not received). When the CW parameter value becomes CWmax, data transmission can be attempted while maintaining the CWmax value until data transmission is successful, and if data transmission is successful, it is reset to the CWmin value. The CW, CWmin, and CWmax values ​​are 2. n It is desirable to set it to -1 (n=0, 1, 2, ...).

[0076] Once the random backoff process begins, the STA continues to monitor the medium while counting down the backoff slots according to the determined backoff count value. If the medium is monitored as occupied, the countdown stops and waits. When the medium becomes idle, the remaining countdown resumes.

[0077] In the example of FIG. 4, when a packet to be transmitted reaches the MAC of STA3, STA3 can immediately transmit a frame if it confirms that the medium is idle for DIFS. The remaining STAs monitor the medium for occupied / busy states and wait. In the meantime, data to be transmitted may also occur in each of STA1, STA2, and STA5, and each STA can count down the backoff slot according to a random backoff count value selected by each STA after waiting for DIFS if the medium is monitored as idle. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. In other words, this example shows a case where the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1 when STA2 finishes the backoff count and starts frame transmission. STA1 and STA5 briefly stop counting down and wait while STA2 occupies the medium. When STA2's occupation ends and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume the backoff count that they had stopped. That is, they can start transmitting frames after counting down the remaining backoff slots equal to the remaining backoff time. Since STA5's remaining backoff time is shorter than STA1's, STA5 starts transmitting frames. While STA2 occupies the medium, STA4 may also have data to transmit. From STA4's perspective, when the medium becomes idle, it waits for DIFS, counts down according to its selected random backoff count value, and then starts transmitting frames. In the example of Figure 4, the remaining backoff time of STA5 coincidentally matches the random backoff count value of STA4, in which case a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 will receive an ACK, resulting in a failure in data transmission.In this case, STA4 and STA5 can select a random backoff count value and perform a countdown after doubling the CW value. STA1 waits while the medium is occupied by transmissions from STA4 and STA5, and when the medium becomes idle, it waits for DIFS and can start transmitting frames after the remaining backoff time elapses.

[0078] As in the example of Fig. 4, a data frame is a frame used for transmitting data forwarded to a higher layer, and can be transmitted after a backoff performed after DIFS elapses from when the medium becomes idle. Additionally, a management frame is a frame used for exchanging management information that is not forwarded to a higher layer, and is transmitted after a backoff performed after an IFS elapses, such as DIFS or PIFS (Point coordination function IFS). Subtype frames of a management frame include a beacon, an association request / response, a re-association request / response, a probe request / response, and an authentication request / response. A control frame is a frame used to control access to the medium. The subtype frames of the control frame include Request-To-Send (RTS), Clear-To-Send (CTS), Acknowledgment (ACK), Power Save-Poll (PS-Poll), Block ACK (BlockAck), Block ACK Request (BlockACKReq), Null Data Packet Announcement (NDP), and Trigger. If the control frame is not a response frame to the previous frame, it is transmitted after a backoff performed after the DIFS (Direct Inverse Frame Stop) has elapsed, and if it is a response frame to the previous frame, it is transmitted without a backoff performed after the SIFS (short IFS). The type and subtype of the frame can be identified by the type field and subtype field in the Frame Control (FC) field.

[0079] 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.

[0080] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0081] As mentioned above, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, in which STAs directly sense the medium. Virtual carrier sensing is intended to address potential issues in medium access, such as the hidden node problem. For virtual carrier sensing, the MAC of an STA can utilize a Network Allocation Vector (NAV). The NAV is a value that an STA that is currently using or has the right to use the medium indicates to other STAs the remaining time until the medium becomes available. Therefore, the value set as NAV corresponds to the period during which the STA transmitting the frame is scheduled to use the medium, and an STA receiving the NAV value is prohibited from accessing the medium during that period. For example, the NAV can be set based on the value of the "duration" field in the MAC header of the frame.

[0082] In the example of FIG. 5, it is assumed that STA1 wants to transmit data to STA2, and STA3 is in a position to overhear some or all of the frames transmitted and received between STA1 and STA2.

[0083] In order to reduce the possibility of collisions in transmissions of multiple STAs in a CSMA / CA-based frame transmission operation, a mechanism using RTS / CTS frames may be applied. In the example of FIG. 5, while STA1 is transmitting, STA3 may determine that the medium is idle based on carrier sensing results. That is, STA1 may correspond to a hidden node for STA3. Alternatively, in the example of FIG. 5, while STA2 is transmitting, STA3 may determine that the medium is idle based on carrier sensing results. That is, STA2 may correspond to a hidden node for STA3. By exchanging RTS / CTS frames before performing data transmission and reception between STA1 and STA2, STAs outside the transmission range of either STA1 or STA2, or STAs outside the carrier sensing range for transmissions from STA1 or STA3, may not attempt to occupy the channel during data transmission and reception between STA1 and STA2.

[0084] Specifically, STA1 can determine whether a channel is occupied through carrier sensing. In terms of physical carrier sensing, STA1 can determine channel occupancy idleness based on the energy level or signal correlation detected in the channel. Furthermore, in terms of virtual carrier sensing, STA1 can determine the channel occupancy status using a network allocation vector (NAV) timer.

[0085] STA1 can transmit an RTS frame to STA2 after performing a backoff if the channel is idle during the DIFS. STA2 can transmit a CTS frame, which is a response to the RTS frame, to STA1 after an SIFS if it receives the RTS frame.

[0086] If STA3 cannot overhear a CTS frame from STA2 but can overhear an RTS frame from STA1, STA3 can use the duration information contained in the RTS frame to set a NAV timer for the subsequent consecutively transmitted frame transmission period (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame). Alternatively, if STA3 cannot overhear an RTS frame from STA1 but can overhear a CTS frame from STA2, STA3 can use the duration information contained in the CTS frame to set a NAV timer for the subsequent consecutively transmitted frame transmission period (e.g., SIFS + data frame + SIFS + ACK frame). That is, if STA3 can overhear one or more of the RTS or CTS frames from one or more of STA1 or STA2, it can set a NAV accordingly. If STA3 receives a new frame before the NAV timer expires, it can update the NAV timer using the duration information contained in the new frame. STA3 does not attempt channel access until the NAV timer expires.

[0087] If STA1 receives a CTS frame from STA2, it can transmit a data frame to STA2 after SIFS from the time when the CTS frame is completely received. If STA2 successfully receives the data frame, it can transmit an ACK frame in response to the data frame to STA1 after SIFS. STA3 can determine whether the channel is in use through carrier sensing if the NAV timer expires. If STA3 determines that the channel is not in use by another terminal during the DIFS after the NAV timer expires, it can attempt channel access after a contention window (CW) based on a random backoff has elapsed.

[0088] 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.

[0089] The PHY layer can prepare an MPDU (MAC PDU) to be transmitted based on an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer. For example, when a command requesting the start of transmission of the PHY layer is received from the MAC layer, the PHY layer can switch to transmission mode and transmit the information (e.g., data) provided by the MAC layer in the form of a frame. In addition, when the PHY layer detects a valid preamble of the received frame, it monitors the header of the preamble and sends a command to the MAC layer notifying the start of reception of the PHY layer.

[0090] 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.

[0091] A basic PPDU may include a Short Training Field (STF), a Long Training Field (LTF), a SIGNAL (SIG) field, and a Data field. The most basic (e.g., non-HT (High Throughput) as illustrated in FIG. 7) PPDU format may consist of only the Legacy-STF (L-STF), Legacy-LTF (L-LTF), Legacy-SIG (L-SIG) fields, and a Data field. Additionally, depending on the type of PPDU format (e.g., HT-mixed format PPDU, HT-greenfield format PPDU, VHT (Very High Throughput) PPDU, etc.), additional (or different types of) RL-SIG, U-SIG, non-legacy SIG field, non-legacy STF, non-legacy LTF, (i.e., xx-SIG, xx-STF, xx-LTF (e.g., xx is HT, VHT, HE, EHT, etc.)) may be included between the L-SIG field and the data field. More specific details will be described later with reference to FIG. 7.

[0092] STF is a signal for signal detection, AGC (Automatic Gain Control), diversity selection, and precise time synchronization, while LTF is a signal for channel estimation, frequency error estimation, etc. STF and LTF can be said to be signals for synchronization and channel estimation of the OFDM physical layer.

[0093] The SIG field may include various information related to PPDU transmission and reception. For example, the L-SIG field may consist of 24 bits and may include a 4-bit Rate field, a 1-bit Reserved bit, a 12-bit Length field, a 1-bit Parity field, and a 6-bit Tail field. The RATE field may include information about the modulation and coding rate of data. For example, the 12-bit Length field may include information about the length or time duration of the PPDU. For example, the value of the 12-bit Length field may be determined based on the type of the PPDU. For example, for a non-HT, HT, VHT, or EHT PPDU, the value of the Length field may be determined as a multiple of 3. For example, for HE PPDU, the value of the Length field can be determined as a multiple of 3 + 1 or a multiple of 3 + 2.

[0094] The data field may include a SERVICE field, a Physical layer Service Data Unit (PSDU), a PPDU TAIL bit, and, if necessary, padding bits. Some bits of the SERVICE field may be used to synchronize the descrambler at the receiving end. The PSDU corresponds to a MAC PDU defined at the MAC layer and may contain data generated / used by upper layers. The PPDU TAIL bit may be used to return the encoder to a 0 state. The padding bit may be used to adjust the length of the data field to a predetermined unit.

[0095] MAC PDUs are defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a Frame Check Sequence (FCS). A MAC frame is composed of MAC PDUs and can be transmitted / received through the PSDU in the data portion of the PPDU format.

[0096] The MAC header includes a Frame Control field, a Duration / ID field, an Address field, etc. The Frame Control field may include control information required for frame transmission / reception. The Duration / ID field may be set to a time for transmitting the corresponding frame, etc. The Address subfields may indicate the receiver address, transmitter address, destination address, and source address of the frame, and some Address subfields may be omitted. For specific details of each subfield of the MAC header, including the Sequence Control, QoS Control, and HT Control subfields, refer to the IEEE 802.11 standard document.

[0097] The Null-Data PPDU (NDP) format refers to a PPDU format that does not include a data field. In other words, NDP refers to a frame format that includes a PPDU preamble (i.e., L-STF, L-LTF, L-SIG fields, and, if additionally present, non-legacy SIG, non-legacy STF, and non-legacy LTF) in the general PPDU format, and does not include the remaining part (i.e., data field).

[0098] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0099] Standards such as IEEE 802.11a / g / n / ac / ax use various PPDU formats. The basic PPDU format (IEEE 802.11a / g) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format can also be referred to as the non-HT PPDU format (Fig. 7(a)).

[0100] The HT PPDU format (IEEE 802.11n) additionally includes HT-SIG, HT-STF, and HT-LFT(s) fields in addition to the basic PPDU format. The HT PPDU format illustrated in Fig. 7(b) may be referred to as an HT-mixed format. Additionally, an HT-greenfield format PPDU may be defined, which corresponds to a format that does not include L-STF, L-LTF, and L-SIG, but consists of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTF, and Data fields (not illustrated).

[0101] An example of the VHT PPDU format (IEEE 802.11ac) includes VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format (Fig. 7(c)).

[0102] An example of a HE PPDU format (IEEE 802.11ax) additionally includes RL-SIG (Repeated L-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and PE (Packet Extension) fields in addition to the basic PPDU format (Fig. 7(d)). Depending on specific examples of the HE PPDU format, some fields may be excluded or their lengths may vary. For example, the HE-SIG-B field is included in the HE PPDU format for multi-users (MUs), but the HE PPDU format for single users (SUs) does not include the HE-SIG-B. In addition, the HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may vary to 8us. The HE ER (Extended Range) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may vary to 16us. For example, RL-SIG can be configured identically to L-SIG. The receiving STA can determine that the received PPDU is a HE PPDU or an EHT PPDU, described later, based on the presence of RL-SIG.

[0103] The EHT PPDU format may include the EHT MU (multi-user) PPDU of FIG. 7(e) and the EHT TB (trigger-based) PPDU of FIG. 7(f). The EHT PPDU format is similar to the HE PPDU format in that it includes an RL-SIG following an L-SIG, but may include a U (universal)-SIG, an EHT-SIG, an EHT-STF, and an EHT-LTF following the RL-SIG.

[0104] The EHT MU PPDU in FIG. 7(e) corresponds to a PPDU that carries one or more data (or PSDUs) for one or more users. That is, the EHT MU PPDU can be used for both SU transmission and MU transmission. For example, the EHT MU PPDU can correspond to a PPDU for one receiving STA or multiple receiving STAs.

[0105] The EHT TB PPDU of Fig. 7(f) omits the EHT-SIG compared to the EHT MU PPDU. An STA that has received a trigger for UL MU transmission (e.g., a trigger frame or TRS (triggered response scheduling)) can perform UL transmission based on the EHT TB PPDU format.

[0106] The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated to allow legacy STAs to attempt demodulation and decoding, and mapped based on a predetermined subcarrier frequency interval (e.g., 312.5 kHz). These can be referred to as pre-EHT modulated fields. Next, the EHT-STF, EHT-LTF, Data, and PE fields can be encoded and modulated to allow STAs that have successfully decoded non-legacy SIGs (e.g., U-SIG and / or EHT-SIG) and obtained the information contained in the fields, and mapped based on a predetermined subcarrier frequency interval (e.g., 78.125 kHz). These can be referred to as EHT modulated fields.

[0107] 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.

[0108] The U-SIG included in the EHT PPDU format of FIG. 7 can be configured based on, for example, two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., OFDM symbol) for the U-SIG can have a duration of 4 us, and the U-SIG can have a total duration of 8 us. Each symbol of the U-SIG can be used to transmit 26 bits of information. For example, each symbol of the U-SIG can be transmitted and received based on 52 data tones and 4 pilot tones.

[0109] U-SIGs can be configured in 20MHz units. For example, when an 80MHz PPDU is configured, the same U-SIG can be duplicated in 20MHz units. That is, four identical U-SIGs can be included in an 80MHz PPDU. When the bandwidth exceeds 80MHz, for example, for a 160MHz PPDU, the U-SIGs in the first 80MHz unit and the U-SIGs in the second 80MHz unit can be different.

[0110] For example, A uncoded bits may be transmitted via U-SIG, and a first symbol of U-SIG (e.g., a U-SIG-1 symbol) may transmit the first X bits of information out of a total A bits of information, and a second symbol of U-SIG (e.g., a U-SIG-2 symbol) may transmit the remaining Y bits of information out of a total A bits of information. The A bits of information (e.g., 52 uncoded bits) may include a CRC field (e.g., a field of 4 bits in length) and a tail field (e.g., a field of 6 bits in length). The tail field may be used to terminate the trellis of the convolutional decoder and may be set to 0, for example.

[0111] The A bit information transmitted by U-SIG can be divided into version-independent bits and version-dependent bits. For example, U-SIG can be included in a new PPDU format (e.g., UHR PPDU format) not shown in FIG. 7, and in the format of the U-SIG field included in the EHT PPDU format and the format of the U-SIG field included in the UHR PPDU format, the version-independent bits can be the same, and some or all of the version-dependent bits can be different.

[0112] 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.

[0113] For example, the version-independent bits of the U-SIG may include a 3-bit PHY version identifier, which may indicate the PHY version (e.g., EHT, UHR, etc.) of the transmitted and received PPDUs. The version-independent bits of the U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication. The version-independent bits of the U-SIG may include information about the length of a transmission opportunity (TXOP) and information about a BSS color ID.

[0114] For example, the version-dependent bits of the U-SIG may contain information that directly or indirectly indicates the type of PPDU (e.g., SU PPDU, MU PPDU, TB PPDU, etc.).

[0115] Information required for PPDU transmission and reception may be included in the U-SIG. For example, the U-SIG may further include information about bandwidth, information about the MCS technique applied to the non-legacy SIG (e.g., EHT-SIG or UHR-SIG), information indicating whether a dual carrier modulation (DCM) technique (e.g., a technique to achieve an effect similar to frequency diversity by reusing the same signal on two subcarriers) is applied to the non-legacy SIG, information about the number of symbols used for the non-legacy SIG, information about whether the non-legacy SIG is generated across the entire band, etc.

[0116] Some of the information required for transmitting and receiving a PPDU may be included in the U-SIG and / or the non-legacy SIG (e.g., EHT-SIG or UHR-SIG, etc.). For example, information about the type of the non-legacy LTF / STF (e.g., EHT-LTF / EHT-STF or UHR-LTF / UHR-STF, etc.), information about the length of the non-legacy LTF and the cyclic prefix (CP) length, information about the guard interval (GI) applicable to the non-legacy LTF, information about preamble puncturing applicable to the PPDU, information about resource unit (RU) allocation, etc. may be included only in the U-SIG, may be included only in the non-legacy SIG, or may be indicated by a combination of the information included in the U-SIG and the information included in the non-legacy SIG.

[0117] Preamble puncturing may refer to the transmission of a PPDU in which no signal is present in one or more frequency units within the PPDU's bandwidth. For example, the size of the frequency unit (or the resolution of the preamble puncturing) may be defined as 20 MHz, 40 MHz, etc. For example, preamble puncturing may be applied to a PPDU bandwidth greater than a certain size.

[0118] In the example of FIG. 7, non-legacy SIGs such as HE-SIG-B and EHT-SIG may include control information for the receiving STA. The non-legacy SIG may be transmitted over at least one symbol, and each symbol may have a length of 4 us. Information regarding the number of symbols used for the EHT-SIG may be included in a previous SIG (e.g., HE-SIG-A, U-SIG, etc.).

[0119] Non-legacy SIGs, such as HE-SIG-B and EHT-SIG, may contain common fields and user-specific fields. Common and user-specific fields may be coded separately.

[0120] In some cases, common fields may be omitted. For example, in a compressed mode where non-OFDMA (orthogonal frequency multiple access) is applied, common fields may be omitted, and multiple STAs may receive PPDUs (e.g., data fields of PPDUs) over the same frequency band. In a non-compressed mode where OFDMA is applied, multiple users may receive PPDUs (e.g., data fields of PPDUs) over different frequency bands.

[0121] The number of user-specific fields can be determined based on the number of users. A single user block field can contain up to two user fields. Each user field can be associated with either MU-MIMO allocation or non-MU-MIMO allocation.

[0122] The common field may include CRC bits and Tail bits, the length of the CRC bits may be determined as 4 bits, and the length of the Tail bits may be determined as 6 bits and set to 000000. The common field may include RU allocation information. The RU allocation information may include information about the location of RUs to which multiple users (i.e., multiple receiving STAs) are allocated.

[0123] An RU can contain multiple subcarriers (or tones). RUs can be used when transmitting signals to multiple STAs based on OFDMA techniques. RUs can also be defined when transmitting signals to a single STA. Resources can be allocated on an RU basis for non-legacy STFs, non-legacy LTFs, and data fields.

[0124] Depending on the PPDU bandwidth, an applicable RU size can be defined. The RU may be defined identically or differently for the applicable PPDU format (e.g., HE PPDU, EHT PPDU, UHR PPDU, etc.). For example, in the case of an 80MHz PPDU, the RU arrangements of HE PPDU and EHT PPDU may be different. The applicable RU size, RU number, RU position, DC (direct current) subcarrier position and number, null subcarrier position and number, guard subcarrier position and number, etc. for each PPDU bandwidth can be referred to as a tone plan. For example, a tone plan for a wide bandwidth can be defined in the form of multiple repetitions of a low bandwidth tone plan.

[0125] RUs of different sizes can be defined, such as 26-ton RU, 52-ton RU, 106-ton RU, 242-ton RU, 484-ton RU, 996-ton RU, 2X996-ton RU, 3X996-ton RU, etc. A multiple RU (MRU) is distinguished from multiple individual RUs and corresponds to a group of subcarriers consisting of multiple RUs. For example, one MRU can be defined as 52+26-tons, 106+26-tons, 484+242-tons, 996+484-tons, 996+484+242-tons, 2X996+484-tons, 3X996-tons, or 3X996+484-tons. Additionally, multiple RUs constituting one MRU may or may not be consecutive in the frequency domain.

[0126] The specific size of an RU may be reduced or expanded. Therefore, the specific size of each RU (i.e., the number of corresponding tones) in the present disclosure is not limited and is exemplary. Furthermore, within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, etc.) in the present disclosure, the number of RUs may vary depending on the RU size.

[0127] The names of each field in the PPDU formats of FIG. 7 are exemplary and the scope of the present disclosure is not limited by those names. Furthermore, the examples of the present disclosure can be applied not only to the PPDU format exemplified in FIG. 7, but also to a new PPDU format in which some fields are excluded and / or some fields are added based on the PPDU formats of FIG. 7.

[0128] multi-link operation (MLO)

[0129] Below, the multi-link (ML) operation supported by the STA according to the present disclosure is described.

[0130] The STA (AP STA and / or non-AP STA) described in the present disclosure can support multi-link (ML) communication. ML communication may refer to communication that supports multiple links. Links related to ML communication may include channels (e.g., 20 / 40 / 80 / 160 / 240 / 320MHz channels) of a frequency band (e.g., 2.4GHz band, 5GHz band, 6GHz band, etc.) in which the STA operates. The multiple links used for ML communication may be configured in various ways. For example, the multiple links supported for one STA for ML communication may belong to the same frequency band or may belong to different frequency bands. In addition, each link may correspond to a frequency unit of a predetermined size (e.g., a channel, a subchannel, an RU, etc.). In addition, some or all of the multiple links may be frequency units of the same size or may be frequency units of different sizes.

[0131] When one STA supports multiple links, the transmitting and receiving devices supporting each link can operate as one logical STA. That is, a multi-link device (MLD) is a device that has one or more affiliated STAs as a logical entity and a single MAC service access point (SAP) for one MAC data service and logical link control (LLC). A non-AP MLD refers to an MLD in which each STA affiliated with the MLD is a non-AP STA. A multi-radio non-AP MLD refers to a non-AP MLD that supports receiving or exchanging frames on more than one link at a time. An AP MLD refers to an MLD in which each STA affiliated with the MLD is an AP STA.

[0132] Multi-link operation (MLO) can enable a non-AP MLD to discover, authenticate, associate, and set up multiple links with an AP MLD. Based on the supported capabilities exchanged during the association procedure, each link can enable channel access and frame exchange between the non-AP MLD and the AP MLD. An STA affiliated with an MLD can select and manage its capabilities and operating parameters independently from other STA(s) affiliated with the same MLD.

[0133] Through the multi-link setup process, the AP MLD and / or the non-AP MLD can transmit and receive link-related information that the MLD can support. The link-related information may include one or more of information about whether the MLD supports simultaneous transmit and receive (STR) operation or non-simultaneous transmit and receive (NSTR) operation on multiple links, information about the number / upper limit of UL / DL links, information about the location / bandwidth / resource of UL / DL links, information about frame types (e.g., management, control, data, etc.) that are available or preferred on at least one UL / DL link, information about an ACK policy that is available or preferred on at least one UL / DL link, or information about a traffic identifier (TID) that is available on at least one UL / DL link.

[0134] An AP MLD (e.g., NSTR mobile AP MLD) can set one of the multiple links as the primary link. The AP MLD may transmit beacon frames, probe response frames, and group-addressed data frames only on the primary link. The remaining link(s) of the multiple links may be referred to as non-primary links. An AP MLD operating on a non-primary link may operate so as not to transmit beacon frames or probe response frames. In addition, a non-AP MLD may perform frame exchanges during authentication, (re)association, and 4-way handshaking only on the primary link.

[0135] A setup link is defined as enabled if at least one traffic identifier (TID) is mapped to the link through the multi-link setup process, and a setup link can be defined as disabled if no TID is mapped to the link. A TID must always be mapped to at least one setup link unless admission control is used. By default, a TID is mapped to all setup links, so all setup links can be enabled.

[0136] When a link is activated, it can be used for frame exchange, depending on the power state of the non-AP STAs operating on that link. Only MSDUs or A-MSDUs with TIDs mapped to the activated link can be transmitted on that link. Management frames and control frames can only be transmitted on the activated link.

[0137] When a link is disabled, that link may not be used for frame exchange, including management frames for both DL and UL.

[0138] During a multi-link setup, activation / deactivation of individual links can be directed through TID-to-Link mapping. TID-to-Link mapping can be performed in default mapping mode or / and negotiation mapping mode.

[0139] Among the STAs belonging to the MLD, one STA may provide information about one or more links other than the link on which it is located, for multi-link discovery (e.g., obtaining information about multiple links including the corresponding link on one link) or multi-link setup (e.g., simultaneously associating on multiple links by exchanging association request / response frames on one link). A multi-link (ML) element may be defined to provide such information.

[0140] Figure 8 exemplarily shows the structure of an ML element to which the present disclosure can be applied.

[0141] In an ML element, the element ID field and the element ID extension field may have specific values ​​(e.g., 255 and 107) indicating that it is an ML element, and the length field may have a value indicating the length (e.g., in octet units) of the remaining fields excluding the element ID field and the length field.

[0142] The multi-link control field is defined as 2 octets in size and may include a 3-bit type subfield, a 1-bit reserved bit, and a 12-bit presence bitmap subfield. The type subfield may have a value indicating one of the following types: basic, probe request, reconfiguration, tunneled direct-link setup (TDLS), and priority access. The presence bitmap subfield indicates the presence or absence of various subfield(s) within the common info field, and may be defined in different formats depending on the various variants (or types) of the ML element.

[0143] The common info field is defined to be of variable size and may include a 6-octet MLD MAC address subfield, which may have a value specifying the MAC address of the MLD to which the STA transmitting the basic ML element belongs. In addition, a link ID info subfield, a BSS parameter change count subfield, a medium synchronization delay information subfield, an enhanced multi-link (EML) capability subfield, and an MLD capability subfield may or may not be included in the common info field.

[0144] The link info field is defined as having a variable size, can contain link-specific information, and can be optionally present. If the link info field exists, it can contain one or more subelements. The format and order of the subelements can be defined in various ways. As an example of optional subelement IDs for the basic variant ML element, the value 0 of the subelement ID corresponds to the name of the per-STA profile and is extensible, the value 221 corresponds to the name of the vendor-specific name and the extensibility can be determined by the vendor, and the remaining values ​​1-220 and 222-255 can be reserved.

[0145] The STA-per-profile subfield may include a 1-octet subelement ID subfield, a 1-octet length subfield, a 2-octet STA control subfield, a variable-size STA info subfield, and a variable-size STA profile subfield. The STA control subfield may include information such as a link ID, whether a complete profile is included, whether an STA MAC address exists, etc. The STA info subfield may include information such as an STA MAC address. The STA profile subfield may include information included in a probe response or probe request frame body, information included in a (re)association response or (re)association request frame body, etc., depending on whether the reported STA is an AP STA or a non-AP STA.

[0146] The format of the ML elements in FIG. 8 is exemplary, and the order, names, sizes, etc. of the fields / subfields may be changed, additional fields / subfields may be further defined, and some fields / subfields may be excluded. In short, the common information field includes common information between STAs in the MLD, and the link information field may include specific information for each STA / link (e.g., in a per-STA profile subelement including a link ID corresponding to the STA).

[0147] MLD discovery method in the millimeter wave (mmWave) band

[0148] A multi-link device (MLD) defined in 802.11be consists of affiliated APs (or non-AP STAs) that operate on one or more different channels, and has fundamentally achieved significant improvements in terms of (aggregated / average) throughput / latency. In particular, while the existing MLD has primarily targeted the 2.4 to 7.25 GHz (sub-7 GHz) band, recently, with the growing need for millimeter wave (mmWave) that offers relatively limited coverage but powerful throughput / latency improvements, research is being conducted to enable MLD affiliated APs (or non-AP STAs) to operate in the mmWave band (i.e., unlicensed bands between 42 and 71 GHz). Therefore, the issues that arise as affiliated APs (or non-AP STAs) of MLDs operating in the mmWave band are included need to be resolved.

[0149] FIG. 9 illustrates an AP MLD and a non-AP MLD supporting the mmWave band according to one embodiment of the present disclosure.

[0150] Figure 9 illustrates an MLD supporting the mmWave band. AP 1 of the AP MLD operates a channel in the sub-7 GHz band, AP 3 operates a channel in the mmWave band, STA 1 of the non-AP MLD supports the sub-7 GHz band, and STA 2 supports the mmWave band. Therefore, the non-AP MLD can request a multi-link setup from the AP MLD so that STA 1 can associate with AP 1 (link 1) and STA 2 can associate with AP 3 (link 2).

[0151] To achieve this, a non-AP MLD supporting the mmWave band fundamentally needs to be aware of the presence of an AP operating in the mmWave band and of information about this AP MLD. A non-AP MLD that recognizes this information can successfully complete multi-link setup with the AP MLD, depending on its capabilities. Therefore, this disclosure proposes a method for a discoverable MLD to transmit or announce information related to an STA operating in the mmWave band.

[0152] The names and other designations used in this disclosure are for convenience of explanation and may be replaced with equivalent names. Furthermore, unless otherwise specified in this disclosure, an STA may include an AP STA or a non-AP STA.

[0153] In addition, in the description of the present disclosure, for the convenience of explanation, a case in which an AP operating in a sub-7GHz band and an AP operating in a mmWave band are included within an AP MLD is mainly described. Here, an AP that announces information about an AP operating in a mmWave band is referred to as an rAP (reporting AP) (i.e., an AP operating in a sub-7GHz band), and an AP operating in a mmWave band related to the announced information is referred to as a (target) mAP.

[0154] However, the present disclosure is not limited thereto, and the proposed method of the present disclosure can be equally applied in a situation where multiple APs / non-STAs are included in an MLD and one AP / non-STA in the MLD notifies / transmits information about another AP / non-STA in the same MLD.

[0155] FIG. 10 illustrates a reduced neighbor report element format in a wireless communication system to which the present disclosure may be applied.

[0156] Referring to FIG. 10, the RNR element includes channel and other information related to neighboring APs, and is configured to include an element identifier (ID) field, a length field, and one or more neighbor AP information field(s).

[0157] The neighbor AP information field specifies the target beacon transmission time (TBTT) and other information related to a group of neighbor APs on a single channel, and is composed of a TBTT information header field, an operating class field, a channel number field, and a TBTT information set field.

[0158] The operating class field, together with the channel number field, indicates the channel start frequency, which represents the default channel of the AP BSS in this neighboring AP information field.

[0159] The channel number field indicates the last known primary channel of the AP in this neighboring AP information field.

[0160] The TBTT information header field is composed of a TBTT information field type subfield, a filtered neighbor AP subfield, a reserved bit, a TBTT information count subfield, and a TBTT information length subfield.

[0161] The TBTT information field type subfield, together with the TBTT information length subfield, identifies the format of the TBTT information field. The TBTT information field type subfield can be set to values ​​0 or 1, with values ​​2 and 3 being reserved.

[0162] The TBTT information set field contains one or more TBTT information (TBTT ifnormation) fields.

[0163] The TBTT information length subfield indicates the length of each TBTT information field included in the TBTT information field set field. When the TBTT information field type subfield is 0, the TBTT information length subfield indicates the length in octets of each TBTT information field included in the TBTT information field set. That is, when the TBTT information length subfield indicates 3, the length of each TBTT information field corresponds to 3 octets.

[0164] Table 1 illustrates the contents of the TBTT information field according to the value of the TBTT information length subfield when the TBTT information field type subfield is 0.

[0165]

[0166]

[0167]

[0168] Table 2 illustrates the contents of the TBTT information field according to the TBTT information length subfield value when the TBTT information field type subfield is 1.

[0169]

[0170] When the TBTT information field type subfield in Table 2 is 1 and the TBTT information length subfield in Table 2 is set to 3 (i.e., not a reserved value), the TBTT information field is configured to include an MLD parameters subfield as shown in FIG. 10. That is, the TBTT information (TBTT ifnormation) field may be configured to include a neighbor AP TBTT offset subfield, a BSSID subfield, a short SSID subfield, a BSS parameters subfield, a 20MHz power spectral density (PSD) subfield, and an MLD parameters subfield.

[0171] The neighbor AP TBTT offset subfield indicates the offset in time units (TU), rounded to the nearest TU, as follows:

[0172] ― If the reporting / target AP is not part of a multi-BSSID set or is the transmitting BSSID of a multi-BSSID set, the next TBTT of the reporting / target AP from the immediately previous TBTT of the AP transmitting this element.

[0173] - If the reporting / target AP is part of a multi-BSSID set and is a non-transmitted BSSID, the next TBTT of the transmitted BSSID in the multi-BSSID set of the reporting / target AP from the immediately previous TBTT of the AP transmitting this element.

[0174] When the TBTT information field type subfield is set to 1 and the TBTT information length subfield is set to 3, the TBTT information (TBTT ifnormation) field carries the MLD parameters subfield.

[0175] The MLD parameters subfield may consist of an AP MLD ID subfield, a link ID subfield, a BSS parameters change count subfield, an all updates included subfield, a disabled link indication subfield, and reserved bits.

[0176] The AP MLD ID subfield indicates the identifier of the AP MLD to which the reporting / target AP belongs.

[0177] The link ID subfield indicates the link identifier of the reporting / target AP within the AP MLD to which the reporting / target AP belongs.

[0178] FIG. 11 illustrates the format of a per-STA profile subelement within a multi-link element in a wireless communication system to which the present disclosure may be applied.

[0179] Referring to FIG. 11, a format within a multi-link element is illustrated, and may be configured to include an element ID field, a length field, an element ID extension field, a multi-link control field, a common info field, and a link info field.

[0180] Depending on the variant of this element, certain field(s) or subfield(s) within a field may not be included, and the type subfield within the multi-link control field is used to distinguish variants of the multi-link element.

[0181] Table 3 illustrates the encoding of values ​​in the type subfield.

[0182] Type Subfield Value Multi-Link Element Variant Name 0 Basic 1 Probe Request 2 Reconfiguration 3 TDLS 4 Priority Access 5-7 Reserved

[0183] The link info field conveys specific information about one or more links and may be optionally present. If present, the link info field may contain one or more per-STA profile subelements.

[0184] A per-STA profile subelement may be composed of a subelement identifier (subelement ID) subfield, a length subfield, a STA control subfield, a STA info subfield, and a STA profile subfield.

[0185] The STA control subfield may be configured to include a link identifier (link ID) subfield, a complete profile subfield, an STA MAC address present subfield, a beacond interval present subfield, a timing synchronization function (TSF) offset present subfield, a delivery traffic indication map (DTIM) information present subfield, an NSTR link pair present subfield, an NSTR bitmap size subfield, a BSS parameters change count present subfield, and reserved bits.

[0186] The link identifier (link ID) subfield specifies a value that uniquely identifies the link on which the reporting / target STA is operating.

[0187] The TSF offset present subfield is set to 1 if the TSF offset subfield is present in the STA Info field, otherwise it is set to 0. Non-AP STAs set the TSF offset present subfield to 0 in the transmitted basic multi-link element.

[0188] Example 1: Information about an AP (mAP) operating in the mmWave band

[0189] Some essential information about affiliated APs belonging to the AP MLD may be announced in a reduced neighbor report (RNR) element (i.e., RNR information element (IE)) (see FIG. 10) or a basic multi-link element (see FIG. 11) included in a beacon frame or a probe response frame.

[0190] However, since the mmWave band is not a band that operates in the sub-7GHz band, the essential information configuration can be considered by taking into account at least one of the following:

[0191] i) Since the range / coverage in the mmWave band is relatively small, management frames such as beacon / probe response frames may not be transmitted. Therefore, an AP operating in sub-7 GHz (i.e., rAP) can announce information about an AP operating in the mmWave band (i.e., mAP), and existing information related to this may be changed and transmitted.

[0192] ii) Not all essential information present in the RNR IE may be required and / or additional information not currently present in the RNR IE may be required.

[0193] Such information may be composed of at least one of the following pieces of information. Hereinafter, for the convenience of explanation, information about an AP operating in the mmWave band announced by an AP operating in the sub-7GHz band within the AP MLD will be described from the perspective of information existing in the existing RNR IE (by way of example of fields / subfields within the RNR IE), but the present disclosure is not limited thereto. That is, the information about an AP operating in the mmWave band described below may be transmitted using a format of an information element different from the RNR IE, and in this case, even if the content is the same, it may be announced by being composed of different fields / subfields.

[0194] As described above, referring again to FIG. 10, a method for indicating information about an AP operating in the mmWave band from the perspective of information present in the RNR IE (i.e., information that can be configured from the contents of the TBTT information field) is described.

[0195] - The MLD parameters subfield (e.g., 3 octets) of the RNR IE can be structured as follows:

[0196] Here, the Link ID subfield in the MLD parameters subfield can basically have a value of 0 to 15.

[0197] Additionally or alternatively, if there is a maximum number of links that an affiliated AP operating in sub-7GHz that constitutes the AP MLD can have (e.g., 15, 16) (i.e., if it is already set up), then the Link ID for the mAP cannot be indicated as 0 to 15, so the interpretation of the Link ID can be determined as follows. For an affiliated mAP of an AP MLD that operates a channel in the mmWave band (i.e., a band between 42 and 71 GHz), the value of the Link ID subfield can be interpreted as 'the current maximum possible number of links (e.g., 15 or 16) + the value indicated in the Link ID subfield'. For example, if the current maximum possible number of links is 15 and the value of the Link ID subfield is 2, the Link ID of the corresponding mAP can be 17.

[0198] Additionally or alternatively, one or more reserved bits or other subfields of the MLD Parameters subfield may be used to indicate additional Link ID values. For example, if the value of the Link ID subfield is 15 or 16, and the additional Link ID value (indicated using one or more reserved bits or other subfields) is 2, the Link ID may be 17 or 18. That is, the final Link ID of the affiliated mAP may be determined by adding the additionally indicated Link ID value to the value of the Link ID subfield.

[0199] Additionally or alternatively, when a 1-bit additional link ID subfield is defined and its value is 1, the Link ID may be determined as 14 (or 15) + the value of the Link ID subfield. That is, when the additional link ID subfield is set to 1, the final Link ID of the affiliated mAP may be determined by adding 14 (or 15) to the value indicated in the Link ID subfield. For example, if the value of the additional link ID subfield is 1 and the value of the link ID subfield is 1, the link ID may be 15 (or 16).

[0200] - Referring again to FIG. 10, the neighbor AP TBTT offset field (e.g., 1 octet) of the RNR IE may be configured as follows.

[0201] The offset indicated by the neighbor AP TBTT offset field of the RNR IE is defined as follows: That is, the offset between the first TBTT and the second TBTT is indicated by the neighbor AP TBTT offset field:

[0202] If the reporting / target AP is not part of a multi-BSSID set or is the transmitting BSSID of a multi-BSSID set, the next TBTT (second TBTT) of the reporting / target AP from the immediately previous TBTT (first TBTT) of the AP transmitting this element (i.e., RNR IE).

[0203] If the reporting / target AP is part of a multi-BSSID set and is a non-transmitted BSSID, the next TBTT (second TBTT) of the transmitted BSSID of the multi-BSSID set of the reporting / target AP in the immediately preceding TBTT (first TBTT) of the AP transmitting this element (i.e., RNR IE).

[0204] In this disclosure, the reported / target AP may correspond to an mAP, and the AP transmitting this element (i.e., RNR IE) may correspond to an rAP.

[0205] Additionally, as described above, since the mAP may not transmit management frames, if the mAP does not transmit a beacon frame, the TBTT of the mAP may mean that it operates as if the beacon frame was transmitted at that point in time, rather than the time when the actual beacon frame is transmitted. Additionally, it may be interpreted as a virtual TBTT, so that it may operate as if the beacon frame was transmitted at that point in time, even though the actual beacon frame was not transmitted. Since there is a MAC operation performed based on the TBTT, even if the beacon frame is not transmitted, it can be interpreted / operated as if it is transmitted so that the MAC operation can be properly performed based on the virtual TBTT.

[0206] Additionally or alternatively, the TBTT of the mAP may be set to the TBTT of at least one AP operating in the sub-7GHz band of the MLD to which the mAP belongs.

[0207] Additionally or alternatively, the neighbor AP TBTT offset may be replaced / modified with the TSF offset. For example, the neighbor AP TBTT offset field may be replaced / modified with the TSF offset field. The TSF offset may be indicated as a 2's complement signed integer in units of Xμs. In addition, the size may vary depending on Xμs. For example, if X = 2, the TSF offset may be 8 octets.

[0208] - The BSSID subfield (e.g., 6 octets) of the RNR IE can indicate the BSSID of the mAP.

[0209] - The 20MHz PSD subfield of the RNR IE may be replaced by an XMHz PSD subfield (e.g., 1 or more octets), which may indicate the maximum transmit power for the primary channel of XMHz of the mAP (e.g., in unit interpretation of PSD EIRP (effective isotropic radiated power) in dBm / MHz).

[0210] By default, the bandwidth size of the primary channel of a Sub-7HGz AP can be 20MHz, but in mAPs, the bandwidth size of the primary channel can be different. For example, it can be 40 / 80 / 160 MHz.

[0211] The maximum transmit power indicated by this X MHz PSD subfield may help non-AP STAs supporting mmWave band in Non-AP MLD to determine whether the mAP is reachable.

[0212] Alternatively or additionally, channelization based on 802.11ad / 11ay may be used as an example to provide channel-related information for mAP.

[0213] FIG. 12 is a diagram illustrating channelization in a wireless communication system to which the present disclosure can be applied.

[0214] However, in the MLD to which mAP and rAP belong, frame exchange can be performed using a bandwidth such as 320MHz, similar to the sub-7GHz band, on the mAP's link. In other words, the actual channel on which the mAP operates may not match the channel indicated in the RNR IE, etc. Therefore, at least one or more channel-related information may be additionally included for this purpose. The following information may be applied based on FIG. 12 or based on other channelization criteria.

[0215] A) Bandwidth (BW): The bandwidth at which the mAP operates can be indicated. Additionally, the maximum possible bandwidth can be indicated with X bits. For example, with 2 bits, 320MHz, 640Mhz, 1280MHz, 2560MHz, etc. can be indicated.

[0216] B) Channel Index: The index of the channel corresponding to the bandwidth can be indicated. Additionally, it can be indicated with X bits considering the maximum possible channel index. For example, if there are 8 channels capable of 320 MHz in one 2.16 GHz channel, 3 bits can be used to indicate which 320 MHz channel it is.

[0217] Additionally or alternatively, A) and B) can be simultaneously indicated in bitmap form. That is, if the number of configurable channels for the bandwidth X MHz of the reference channel (e.g., X = 320, 640) is N, a bitmap having N bits can be used. For example, if the number of channels that can be set to 320 MHz in one 2.16 GHz channel is 8, 8 bits can be used in order. That is, the part where the bit is 1 can indicate that the 320 MHz channel is being used. For example, in the case of 320 MHz, 10000000 can indicate that the first channel is being used, and 01000000 can indicate that the second channel is being used. Another example is 640 MHz, 11000000 can indicate that the first and second 320 MHz channels are being used. Additionally, 320 MHz + 320 MHz can be defined as 010100000.

[0218] C) Primary Channel: The primary channel can be indicated among the channels on which the mAP operates. If the bandwidth is X MHz (e.g., X = 320 / 640 / 1280,...) and the primary channel is based on Y MHz (e.g., Y = 320 / 640), the location of Y MHz among X MHz can be indicated. For example, in the case of 640 MHz in the example presented above (i.e., bitmap = 11000000), when the primary channel is based on 320 MHz and the first 320 MHz is the primary channel, it can be indicated as 10000000 in a bitmap similarly to the above, or the channel index can be indicated (for example, a value of 0 meaning the first 320 MHz can be indicated using 3 bits. If the second 320 MHz channel in the above example is the primary channel, a value of 1 can be indicated).

[0219] Meanwhile, a method is needed to indicate one or more of the information presented above, and at least one of the following methods can be utilized.

[0220] Example 1: Method for indicating information about an AP (mAP) operating in the mmWave band

[0221] 1) When directed by RNR IE

[0222] Referring to FIG. 10, in RNR, a TBTT information field type subfield (indicated by 0 to 3) and a TBTT information length subfield (indicated in octet units) according to the amount of information can be determined to indicate information.

[0223] Therefore, a combination of the TBTT information field type subfield and the TBTT information length subfield needs to be considered for one or more information indications for mAP.

[0224] Basically, at least one of the following may be considered. In particular, since the length of the information may vary depending on one or more combinations of the information presented above, at least one of the following may be considered:

[0225] Reserved bits in the TBTT information length subfield may be used for each TBTT information field type subfield (e.g., 0 or 1) (see Table 1 and / or Table 2).

[0226] Additionally, when the TBTT information field type subfield = 0, if the length of each TBTT information field is already in use (e.g., 1, 2, 5, 6, 7, 8, 9, 11, 12, or 13 in Table 1), the length for other values ​​of the TBTT information field type subfield may be used.

[0227] Additionally or alternatively, when there is no additional / separately defined rule to inform the Non-AP MLD that the AP is operating in the mmWave band, the length excluding 3 octets in the TBTT information field type subfield = 1 may be utilized as the length of each TBTT information field. If 3 octets are used without an additional / separate rule, it cannot be distinguished from an AP operating in a non-primary link of the NSTR AP MLD.

[0228] Additionally, a new TBTT information field type subfield value (i.e., 2 or 3) may be used. This can also be used to indicate that the AP is operating in the mmWave band. In particular, legacy STAs or non-AP MLDs that do not have STAs supporting the mmWave band do not need to unnecessarily check information about APs operating in the mmWave band.

[0229] As an example of the contents of the TBTT information field, it can be set as a combination of the MLD Parameters subfield and the neighbor AP TBTT offset subfield. That is, information about an AP operating in the mmWave band can be conveyed by a combination of the MLD Parameters subfield and the neighbor AP TBTT offset subfield.

[0230] In this case, it can be assumed that the BSSID and reachability related information (e.g. X MHz PSD) should be obtained using Multi-link Probe Request / Response.

[0231] The length of the combination of the MLD Parameters subfield and the neighbor AP TBTT offset subfield may be 4 octets or more.

[0232] Additionally, for any value of the TBTT information field type subfield, in the case of 4 octets, the TBTT Information Length subfield = 4 octets is reserved, so that a combination of the MLD Parameters subfield and the neighbor AP TBTT offset subfield can be indicated as shown in Table 4 below.

[0233] TBTT Information Length subfield valueTBTT Information field contents......4The Neighbor AP TBTT Offset subfield and the MLD Parameters subfield......

[0234] That is, when the TBTT Information Length subfield = 4, the TBTT information field can have a neighbor AP TBTT offset subfield and an MLD Parameters subfield. When the TBTT information field type subfield = 1 is used, legacy STAs do not need to unnecessarily check the TBTT information field, and when the TBTT information field type subfields = 2,3 are used, legacy STAs or non-AP MLDs that do not have STAs supporting the mmWave band do not need to unnecessarily check the TBTT information field.

[0235] Additionally or alternatively, if any other subfields are added other than the neighbor AP TBTT offset subfield and the MLD Parameters subfield, the value of the TBTT Information Length subfield becomes greater than 4, and therefore it is necessary to check whether the value of the TBTT Information Length subfield according to the current TBTT information field type subfield value is being used. For example, in the proposed method described above, the additional link ID information may not be included in the MLD parameters subfield but may be configured as a separate field. In this case, if the additional link ID information is included in a subfield having a size of 1 octet, the TBTT Information Length subfield becomes 5, and thus can be indicated when the TBTT information field type subfield = 1.

[0236] Additionally or alternatively, if it is assumed that the timestamps (i.e., TSFs) of mAP and rAP are always the same, then only the MLD parameters subfield may be indicated as information about the mAP, since the neighbor AP TBTT offset subfield may not be needed. In this case, the TBTT information field type subfield = 2 or 3 may be used. If there are additional subfields as information about the mAP as above, a larger length may be indicated as a reserved value of the TBTT Information Length subfield according to the TBTT information field type subfield. Additionally or alternatively, if the Non-AP MLD recognizes that the operating channel is in the mmWave band and the AP MLD ID = 0, the TBTT Information Length subfield = 3 for the TBTT information field type subfield = 1 may be used (see Table 2). That is, these additional rules may result in different interpretations of previously used length values.

[0237] As another example, a combination of the neighbor AP TBTT offset subfield and the MLD Parameters subfield is considered, and the combination of these pieces of information may have a value of the TBTT Information Length subfield of at least 5 octets or more, provided that at least 1 octet is used / required for indicating channel information.

[0238] 2) When indicated in the basic multi-link element (basic ML IE: basic Multi-Link element)

[0239] By default, AP MLD announces the MLD MAC address, essential MLD capabilities, etc. in the Basic ML IE, which is always transmitted by each affiliated AP. Therefore, rAPs can always include one or more pieces of information about mAPs in the Basic ML IE. For this purpose, at least one of the following methods can be considered.

[0240] Information about each mAP may be included in the Per-STA Profile subelement of the Link Info field present in the Basic ML IE.

[0241] In this case, the Link ID subfield of the Per-STA Profile subelement may indicate a link ID for each mAP. Here, as described above, i) the Link ID subfield may be interpreted differently to determine the link ID for the mAP, or ii) an additional Link ID value may be indicated using one or more reserved bits or other subfields to indicate the link ID for the mAP, or iii) an additional link identifier (additional link ID) subfield may be defined to indicate the link ID for the mAP (e.g., in the STA control subfield, the STA info subfield). Alternatively, if the same additional Link ID value is applied to all mAPs, the additional link identifier (additional link ID) subfield may be included in the Common Info field.

[0242] The STA Profile field of the Per-STA Profile subelement may include information about each mAP. Additionally, whether the STA Profile field includes information about each mAP may be indicated in the STA Control field.

[0243] The Common Info field of the Basic ML IE may indicate whether the TSF between the rAP and mAP is the same. If the TSF between the rAP and mAP is the same, the Neighbor TBTT offset (or TSF offset) may not be indicated in the Per-STA Profile subelement.

[0244] Additionally or alternatively, a new type of ML IE (e.g., a new type of Multi-Link Control) may be defined instead of the Basic ML IE, or a new per-STA profile sub-element (e.g., an Integrated mmWave (IMMW) Per-STA Profile sub-element) may be defined instead of the existing Per-STA Profile sub-element. For example, as shown in Table 5, a non-zero reserve value (e.g., 1) for subelement ID may be used to indicate that this Per-STA Profile is a profile for APs operating in the mmWAVE band.

[0245] In such cases, for example, in the case of a link ID, only an additional link ID may be indicated or the size of the existing link ID may be adjusted. This may be determined based on the method of interpreting / indicating the link ID described in the RNR IE described above. As another example, one or more pieces of information about the mAP may be indicated in the STA information subfield or the STA profile subfield. Additionally, one or more pieces of information present in the STA information subfield of the existing Per-STA Profile may be included.

[0246] Table 5 illustrates optional sub-element IDs for the link information field of the ML IE.

[0247] Subelement IDName0Per-STA Profile1IMMW Per-STA Profile2-220Vendor Specific222-253Reserved254Fragement255Reserved

[0248] 3) When indicated in a new information element (IE)

[0249] A separate new IE is defined to announce / deliver information about APs (mAPs) operating in the mmWave band, which can contain one or more pieces of information about each mAP.

[0250] Here, additionally, each mAP can be distinguished by a link ID.

[0251] Meanwhile, along with the above-described embodiments 1 and / or 2, the rAP can notify the non-AP MLD(s) in advance that an mAP exists within the AP MLD to which it belongs. Using this, the non-AP MLD can check the RNR IE, ML IE, or new IE, etc., which contain information about the mAP described above in advance. The presence of an mAP within the AP MLD to which it belongs can be indicated basically using a reserved bit of the Capability Information And Status Indication field transmitted in a beacon frame or a probe response frame, or a reserved bit of the Extended Capabilities element.

[0252] FIG. 13 illustrates the operation of a multi-link device for a method of discovering a multi-link device according to one embodiment of the present disclosure.

[0253] Figure 13 illustrates the operation of a multi-link device based on the previously proposed methods. The example in Figure 13 is provided for convenience of explanation and does not limit the scope of the present disclosure. Some of the steps illustrated in Figure 13 may be omitted depending on the circumstances and / or settings.

[0254] Here, a multi-link device may refer to a device capable of multi-link operation. In addition, the multi-link device may be a non-AP MLD (hereinafter, a first MLD) in which each STA belonging to the multi-link device is a non-AP STA, or an AP MLD (hereinafter, a second MLD) in which each STA belonging to the multi-link device is an AP.

[0255] Additionally, it is assumed that the first non-AP STA and the second non-AP STA belong to the first MLD, and the first AP and the second AP belong to the second MLD.

[0256] FIG. 13 illustrates operations related to receiving STA (including AP or non-AP STA) information of a multi-link device. In particular, for convenience of explanation, FIG. 13 assumes that a first MLD, which is a non-AP MLD, receives AP information from a second MLD, which is an AP MLD. However, conversely, a second MLD, which is an AP MLD, may also receive non-AP STA information from a first MLD, which is a non-AP MLD.

[0257] Referring to FIG. 13, a first STA belonging to a first MLD receives a first frame from a first AP belonging to a second MLD and operating in a first band through a first link (S1301).

[0258] Here, the first frame may include information related to a second AP belonging to the second MLD and operating in a second band different from the first band.

[0259] For example, the first band may be a sub-7 GHz band (e.g., 2.4 to 7.25 GHz) and the second band may be a millimeter wave (mmWave) band (e.g., 42 to 71 GHz).

[0260] Here, the information related to the second AP may include a link identifier (ID), a target beacon transmission time (TBTT) or timing synchronization function (TSF) offset between the first AP and the second AP. Here, the TBTT offset includes information about an offset between the TBTT of the first AP and the TBTT of the second AP, and the TBTT of the second AP may be the same TBTT as the TBTT of at least one other AP belonging to the same MLD as the second AP, or may be a virtual TBTT in which no actual beacon is transmitted from the second AP.

[0261] Additionally, the information related to the second AP may further include at least one of a basic service set ID (BSSID) of the second AP, a maximum transmission power for a bandwidth of a primary channel of the second AP, and information about a channel on which the second AP operates.

[0262] For example, the first frame may include a Reduced Neighbor Reporting (RNR) element, and information related to the second AP may be included in a TBTT information field within the RNR element.

[0263] Here, the length and / or subfield configuration of the TBTT information field may be set differently based on what information related to the second AP is included.

[0264] In this case, to indicate that the information related to the second AP is included in the TBTT information field, i) the value of the TBTT information field type subfield may be set to 0, and the value of the TBTT information length subfield may be set to one of the existing reserved values ​​(e.g., 0, 3, 4, 10, 14, 15, 17-255), or ii) the value of the TBTT information field type subfield may be set to 1, and the value of the TBTT information length subfield may be set to one of the existing reserved values ​​(e.g., 0 to 2, 4 to 255).

[0265] Alternatively, to indicate that information related to the second AP is included in the TBTT information field, the value of the TBTT information field type subfield may be set to 2 or 3.

[0266] Additionally, the TBTT information field may be composed of an MLD Parameters subfield and a Neighbor TBTT offset subfield to include information related to the second AP.

[0267] Additionally, the value of the TBTT information field type subfield may be set to 0 or 1, and the value of the TBTT information length subfield may be set to 4.

[0268] In addition, in order to include information related to the second AP, the TBTT information field may be composed of a MLD Parameters subfield, a Neighbor TBTT offset subfield, and a subfield for channel information. Here, the subfield for the channel information is composed of a bitmap composed of bits of the number of available channels based on a channel of a specific size within a bandwidth in which the second AP operates, and one or more channels used by the second AP may be indicated by the bitmap.

[0269] As another example, the first frame may include a multi-link element, and information related to the second AP may be included in a Per-STA Profile subelement within the multi-link element.

[0270] The first STA performs a multi-link setup procedure to set up a first link between the first STA and the first AP and a second link between the second STA belonging to the first MLD and the second AP (S1302).

[0271] As described above, a first STA can receive a frame containing one or more information about one or more second APs supporting the mmWave band within an MLD to which the one or more first APs belong, and can perform frame detection. The first STA can obtain information about one or more second APs through frame detection. The first STA can use the obtained information to determine whether the MLD to which it belongs can operate with the second STAs supporting the mmWave band. For example, it can determine whether multi-link setup is successful.

[0272] At step S1301, the first MLD receiving the first frame from the second MLD means receiving a PPDU including the first frame.

[0273] Here, the PPDU may be configured to include a legacy part, a SIG part (e.g., U-SIG, UHR-SIG, etc.), an STF part (e.g., UHR-STF), an LTF part (e.g., UHR-LTF), and a data part.

[0274] All or part of any part (i.e., field) may be divided into multiple sub-parts / sub-fields. Each field (and its sub-fields) may be transmitted in units of 4us * N (where N is an integer). Additionally, a guard interval (GI) may be included. A common subcarrier frequency spacing value (delta_f=312.5 kHz / N or 312.5 kHz * N, where N=integer) may be applied to all of the fields, or a first delta_f may be applied to the first part (e.g., all legacy part, all / part of SIG part), and a second delta_f (e.g., a value smaller than the first delta_f) may be applied to all / part of the remaining parts.

[0275] Some of the fields described above may be omitted, and the order of the fields may be changed in various ways. For example, the subfields of the signal part may be placed before the STF part, and the remaining subfields of the SIG part may be placed after the STF part.

[0276] The legacy portion described above may include at least one of a conventional L-STF (Non-HT Short Training Field), L-LTF (Non-HT Long Training Field), and L-SIG (Non-HT Signal Field).

[0277] The SIG portion described above (e.g., including the U-SIG field, UHR-SIG field, etc.) may include various control information for the transmitted PPDU. For example, it may include the STF portion, the LTF portion, and control information for decoding data.

[0278] The above-described STF-part (e.g., the U-STF field) may contain an STF sequence.

[0279] The above-described LTF-part (e.g., U-LTF field) may include a training field (i.e., LTF sequence) for channel estimation.

[0280] The data-part described above may include user data and may include packets for upper layers (e.g., MPDUs) (i.e., first frames).

[0281] The method described in the example of FIG. 13 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 receive the first frame (or the PPDU including the first frame) via the transceiver(s) (106). Furthermore, one or more memories (104) of the first device (100) 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 (102).

[0282] FIG. 14 illustrates the operation of a multi-link device for a method of discovering a multi-link device according to one embodiment of the present disclosure.

[0283] Figure 14 illustrates the operation of a multi-link device based on the previously proposed methods. The example in Figure 14 is provided for convenience of explanation and does not limit the scope of the present disclosure. Some of the steps illustrated in Figure 14 may be omitted depending on the circumstances and / or settings.

[0284] Here, a multi-link device may refer to a device capable of multi-link operation. In addition, the multi-link device may be a non-AP MLD (hereinafter, a first MLD) in which each STA belonging to the multi-link device is a non-AP STA, or an AP MLD (hereinafter, a second MLD) in which each STA belonging to the multi-link device is an AP.

[0285] Additionally, it is assumed that the first non-AP STA and the second non-AP STA belong to the first MLD, and the first AP and the second AP belong to the second MLD.

[0286] FIG. 14 illustrates operations related to transmission of STA (including AP or non-AP STA) information of a multi-link device. In particular, for convenience of explanation, FIG. 14 assumes that a second MLD, which is an AP MLD, transmits AP information to a first MLD, which is a non-AP MLD. However, conversely, a first MLD, which is a non-AP MLD, may transmit non-AP STA information to a second MLD, which is an AP MLD.

[0287] Referring to FIG. 14, a first AP belonging to a second MLD and operating in a first band transmits a first frame to a first STA belonging to a first MLD through a first link (S1401).

[0288] Here, the first frame may include information related to a second AP belonging to the second MLD and operating in a second band different from the first band.

[0289] For example, the first band may be a sub-7 GHz band (e.g., 2.4 to 7.25 GHz) and the second band may be a millimeter wave (mmWave) band (e.g., 42 to 71 GHz).

[0290] Here, the information related to the second AP may include a link identifier (ID), a target beacon transmission time (TBTT) or timing synchronization function (TSF) offset between the first AP and the second AP. Here, the TBTT offset includes information about an offset between the TBTT of the first AP and the TBTT of the second AP, and the TBTT of the second AP may be the same TBTT as the TBTT of at least one other AP belonging to the same MLD as the second AP, or may be a virtual TBTT in which no actual beacon is transmitted from the second AP.

[0291] Additionally, the information related to the second AP may further include at least one of a basic service set ID (BSSID) of the second AP, a maximum transmission power for a bandwidth of a primary channel of the second AP, and information about a channel on which the second AP operates.

[0292] For example, the first frame may include a Reduced Neighbor Reporting (RNR) element, and information related to the second AP may be included in a TBTT information field within the RNR element.

[0293] Here, the length and / or subfield configuration of the TBTT information field may be set differently based on what information related to the second AP is included.

[0294] In this case, to indicate that the information related to the second AP is included in the TBTT information field, i) the value of the TBTT information field type subfield is set to 0, and the value of the TBTT information length subfield is set to one of the existing reserved values ​​(e.g., 0, 3, 4, 10, 14, 15, 17-255), or ii) the value of the TBTT information field type subfield is set to 1, and the value of the TBTT information length subfield may be set to one of the existing reserved values ​​(e.g., 0 to 2, 4 to 255).

[0295] Alternatively, to indicate that information related to the second AP is included in the TBTT information field, the value of the TBTT information field type subfield may be set to 2 or 3.

[0296] Additionally, the TBTT information field may be composed of an MLD Parameters subfield and a Neighbor TBTT offset subfield to include information related to the second AP.

[0297] Additionally, the value of the TBTT information field type subfield may be set to 0 or 1, and the value of the TBTT information length subfield may be set to 4.

[0298] In addition, in order to include information related to the second AP, the TBTT information field may be composed of a MLD Parameters subfield, a Neighbor TBTT offset subfield, and a subfield for channel information. Here, the subfield for the channel information is composed of a bitmap composed of bits of the number of available channels based on a channel of a specific size within a bandwidth in which the second AP operates, and one or more channels used by the second AP may be indicated by the bitmap.

[0299] As another example, the first frame may include a multi-link element, and information related to the second AP may be included in a Per-STA Profile subelement within the multi-link element.

[0300] The first AP performs a multi-link setup procedure to set up a first link between the first STA and the first AP and a second link between the second STA and the second AP belonging to the first MLD (S1402).

[0301] As described above, the first AP may transmit one or more pieces of information about one or more second APs supporting the mmWave band within the MLD to which the first AP belongs via one or more PPDUs. Here, the one or more PPDUs may include a beacon frame and a probe response frame. Additionally or alternatively, the one or more PPDUs may include a bit indicating that an STA supporting the mmWave band exists.

[0302] At step S1401, the second MLD receiving the first frame from the first MLD means transmitting a PPDU including the first frame.

[0303] Here, the PPDU may be configured to include a legacy part, a SIG part (e.g., U-SIG, UHR-SIG, etc.), an STF part (e.g., UHR-STF), an LTF part (e.g., UHR-LTF), and a data part.

[0304] All or part of any part (i.e., field) may be divided into multiple sub-parts / sub-fields. Each field (and its sub-fields) may be transmitted in units of 4us * N (where N is an integer). Additionally, a guard interval (GI) may be included. A common subcarrier frequency spacing value (delta_f=312.5 kHz / N or 312.5 kHz * N, where N=integer) may be applied to all of the fields, or a first delta_f may be applied to the first part (e.g., all legacy part, all / part of SIG part), and a second delta_f (e.g., a value smaller than the first delta_f) may be applied to all / part of the remaining parts.

[0305] Some of the fields described above may be omitted, and the order of the fields may be changed in various ways. For example, the subfields of the signal part may be placed before the STF part, and the remaining subfields of the SIG part may be placed after the STF part.

[0306] The legacy portion described above may include at least one of a conventional L-STF (Non-HT Short Training Field), L-LTF (Non-HT Long Training Field), and L-SIG (Non-HT Signal Field).

[0307] The SIG portion described above (e.g., including the U-SIG field, UHR-SIG field, etc.) may include various control information for the transmitted PPDU. For example, it may include the STF portion, the LTF portion, and control information for decoding data.

[0308] The above-described STF-part (e.g., the U-STF field) may contain an STF sequence.

[0309] The above-described LTF-part (e.g., U-LTF field) may include a training field (i.e., LTF sequence) for channel estimation.

[0310] The data-part described above may include user data and may include packets for upper layers (e.g., MPDUs) (i.e., first frames).

[0311] The method described in the example of FIG. 14 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 transmit the first frame (or the PPDU including the first frame) via the transceiver(s) (206). Furthermore, one or more memories (204) of the second device (200) may store commands for performing the method described in the example of FIG. 14 or the examples described above when executed by one or more processors (202).

[0312] While MLD operation in existing wireless LAN systems only supports operation in the sub-7 GHz band, the MLD operation according to the examples of the present disclosure, in contrast, can discover APs or non-AP STAs operating in the mmWave band. Furthermore, since association (i.e., multi-link setup) and frame exchange can be performed with APs or non-AP STAs operating in the mmWave band, wireless transmission and reception efficiency can be improved.

[0313] The embodiments described above are combinations of components and features of the present disclosure in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented without being combined with other components or features. Furthermore, it is also possible to form embodiments of the present disclosure by combining some components and / or features. The order of operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is self-evident that claims that do not have an explicit citation relationship in the patent claims may be combined to form embodiments or incorporated as new claims through post-application amendments.

[0314] 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 thereof. Therefore, the above detailed description should not be construed as limiting in any respect, but rather as illustrative. The scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents of the present disclosure are intended to be included within the scope of the present disclosure.

[0315] The scope of the present disclosure includes software or machine-executable instructions (e.g., an operating system, an application, firmware, a program, etc.) that cause operations according to the methods of various embodiments to be executed on a device or a computer, and a non-transitory computer-readable medium having such software or instructions stored thereon and executable on the device or computer. Instructions that can be used to program a processing system to perform the features described in the present disclosure can be stored on / in a storage medium or a computer-readable storage medium, and a computer program product including such a storage medium can be used to implement the features described in the present disclosure. The storage medium can include, but is not limited to, high-speed random access memory, such as DRAM, SRAM, DDR RAM, or other random access solid state memory devices, and can include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices. The memory optionally includes one or more storage devices remotely located from the processor(s). The memory or, alternatively, the non-volatile memory device(s) within the memory comprise a non-transitory computer-readable storage medium. The features described in this disclosure may be incorporated into software and / or firmware stored on any of the machine-readable media, which may control the hardware of the processing system and allow the processing system to interact with other mechanisms that utilize results according to embodiments of the present disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0316] The method proposed in this disclosure has been described with a focus on examples applied to IEEE 802.11-based systems, but can be applied to various wireless LANs or wireless communication systems in addition to IEEE 802.11-based systems.

Claims

1. A step of receiving a first frame through a first link from a first access point (AP) belonging to a second MLD and operating in a first band by a first station (STA) belonging to a first multi-link device (MLD), wherein the first frame includes information related to a second AP belonging to the second MLD and operating in a second band different from the first band; and A method comprising the step of performing a multi-link setup procedure for setting up, by the first STA, the first link between the first STA and the first AP and the second link between the second STA belonging to the first MLD and the second AP.

2. In paragraph 1, A method wherein the information related to the second AP includes a link identifier (ID), a target beacon transmission time (TBTT) or a timing synchronization function (TSF) offset for the second AP.

3. In paragraph 2, The above TBTT offset includes information about the offset between the TBTT of the first AP and the TBTT of the second AP, A method wherein the TBTT of the second AP is the same as the TBTT of at least one other AP belonging to the same MLD as the second AP, or is a virtual TBTT in which no actual beacon is transmitted from the second AP.

4. In paragraph 2, A method wherein the information related to the second AP further includes at least one of a basic service set ID (BSSID) of the second AP, a maximum transmission power for a bandwidth of a primary channel of the second AP, and information about a channel on which the second AP operates.

5. In paragraph 1, The first frame includes a reduced neighbor report (RNR) element, A method wherein information related to the second AP is included in a TBTT information field within the RNR element.

6. In paragraph 5, A method in which the length and / or configuration of the subfields of the TBTT information field are set differently based on what information is included in relation to the second AP.

7. In paragraph 6, A method in which, to indicate that information related to the second AP is included in the TBTT information field, i) the value of the TBTT information field type subfield is set to 0, and the value of the TBTT information length subfield is set to one of 0, 3, 4, 10, 14, 15, 17-255, or ii) the value of the TBTT information field type subfield is set to 1, and the value of the TBTT information length subfield is set to one of 0 to 2, 4 to 255.

8. In paragraph 6, A method in which the value of the TBTT information field type subfield is set to 2 or 3 to indicate that information related to the second AP is included in the TBTT information field.

9. In paragraph 6, A method in which the TBTT information field is composed of an MLD Parameters subfield and a Neighbor TBTT offset subfield to include information related to the second AP.

10. In paragraph 9, A method in which the value of the TBTT Information Field Type subfield is set to 0 or 1, and the value of the TBTT Information Length subfield is set to 4.

11. In paragraph 6, A method in which the TBTT information field is composed of an MLD Parameters subfield, a Neighbor TBTT offset subfield, and a subfield for channel information to include information related to the second AP.

12. In paragraph 11, The subfield for the above channel information is composed of a bitmap composed of bits of the number of available channels based on a channel of a specific size within the bandwidth in which the second AP operates, A method in which one or more channels used by the second AP are indicated by the bitmap.

13. In paragraph 1, The first frame above includes a multi-link element, A method wherein information related to the second AP is included in a Per-STA Profile subelement within the multi-link element.

14. In paragraph 1, A method wherein the first band is a sub-7 GHz band and the second band is a millimeter wave (mmWave) band.

15. The first multi-link device (MLD) is: one or more transmitters and receivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: A first frame is received through a first link from a first access point (AP) belonging to a second MLD and operating in a first band by a first station (STA) belonging to the first MLD, wherein the first frame includes information related to a second AP belonging to the second MLD and operating in a second band different from the first band, and A device configured to perform a multi-link setup procedure for setting up a first link between the first STA and the first AP and a second link between a second STA belonging to the first MLD and the second AP, by the first STA.

16. A step of transmitting a first frame to a first station (STA) belonging to a first MLD via a first link by a first access point (AP) belonging to a second multi-link device (MLD) and operating in a first band, wherein the first frame includes information related to a second AP belonging to the second MLD and operating in a second band different from the first band; and A method comprising the step of performing a multi-link setup procedure for setting up, by the first AP, the first link between the first STA and the first AP and the second link between the second STA belonging to the first MLD and the second AP.

17. The second multi-link device (MLD) is: one or more transmitters and receivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: A first frame is transmitted to a first station (STA) belonging to the first MLD via a first link by a first access point (AP) belonging to the second MLD and operating in a first band, wherein the first frame includes information related to a second AP belonging to the second MLD and operating in a second band different from the first band, and A device configured to perform a multi-link setup procedure for setting up a first link between the first STA and the first AP and a second link between a second STA belonging to the first MLD and the second AP, by the first AP.

18. In a processing device configured to control a multi-link device (MLD) in a wireless LAN system, the processing device: one or more processors; and A processing device comprising one or more computer memories operatively connected to said one or more processors and storing instructions that, when executed by said one or more processors, perform a method according to any one of claims 1 to 11.

19. One or more non-transitory computer-readable media storing one or more instructions, A computer-readable medium, wherein the one or more commands are executed by one or more processors to control a device in a wireless LAN system to perform a method according to any one of claims 1 to 11.

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