Method and device for performing mode change and notification operation in wireless LAN system

Abstract

A method performed by a non-access point (AP) multi-link device (MLD) is disclosed. The method according to one embodiment of the present disclosure comprises the steps of: receiving, by a first station (STA) affiliated to a non-AP MLD, a first frame from an AP MLD, the first frame including first information related to a current mode of a first AP affiliated to the AP MLD and second information related to a state of the first AP; and decoding the first frame by the first STA, wherein a listen interval between the non-AP MLD and the AP MLD is based on at least one beacon interval of at least one AP among a plurality of APs included in the AP MLD, and wherein a mode of the at least one AP may be at least one of an active mode and a dynamic power saving (PS) mode.

Description

Method and device for performing mode change and notification operation in a wireless LAN system

[0001] The present disclosure relates to a method and device for performing a mode change and notification operation 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 performing a mode change and notification operation in a wireless LAN system.

[0005] An additional technical problem of the present disclosure is to provide a method and device for setting a listen interval between an access point (AP) multi-link device (MLD) and a non-AP 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 performed by a non-access point (AP) multi-link device (MLD) according to one embodiment of the present disclosure comprises the steps of: receiving, by a first station (STA) affiliated with the non-AP MLD, from an AP MLD a first frame including first information related to a current mode of a first AP affiliated with the AP MLD and second information related to a status of the first AP; and decoding, by the first STA, the first frame, wherein a listen interval between the non-AP MLD and the AP MLD is based on at least one beacon interval of at least one AP among a plurality of APs included in the AP MLD, and a mode of the at least one AP may be at least one of an active mode and a dynamic power saving (PS) mode.

[0008] A method performed by an access point (AP) multi-link device (MLD) according to one embodiment of the present disclosure comprises the steps of: generating a first frame including first information related to a current mode of a first AP affiliated with an AP MLD and second information related to a status of the first AP; and transmitting the first frame to a non-AP MLD by the first access point (AP) affiliated with the AP MLD, wherein a listen interval between the non-AP MLD and the AP MLD is based on at least one beacon interval of at least one AP among a plurality of APs included in the AP MLD, and a mode of the at least one AP may be at least one of an active mode and a dynamic power saving (PS) mode.

[0009] According to the present disclosure, a method and device for performing a mode change and notification operation in a wireless LAN system can be provided.

[0010] According to the present disclosure, a method and device for setting a listen interval between an AP MLD and a non-AP MLD can be provided.

[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] FIG. 8 is a diagram illustrating an example of a high-level structure for an AP MLD to which the present disclosure can be applied.

[0021] FIG. 9 is a flowchart for explaining the operation of the first STA according to one embodiment of the present disclosure.

[0022] FIG. 10 is a flowchart for explaining the operation of the first AP according to one embodiment of the present disclosure.

[0023] FIG. 11 and FIG. 12 are diagrams for explaining the configuration of fields and frames related to the current mode and state of an AP according to one embodiment of the present disclosure.

[0024] FIG. 13 is a diagram illustrating a procedure for setting a listen interval according to one embodiment of the present disclosure.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] In this disclosure, terms such as “first,” “second,” etc. are used only to distinguish one component from another and are not used to limit the components, and do not limit the order or importance between the components unless specifically stated otherwise. Accordingly, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0029] 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.

[0030] 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.

[0031] Below, technical features to which examples of the present disclosure can be applied are described.

[0032] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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).

[0037] 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 memories (104) to generate first information / signals, and then transmit a wireless signal including the first information / signals via the transceivers (106). Furthermore, the processor (102) may receive a wireless signal including second information / signals via the transceivers (106), and then store information obtained from signal processing of the second information / signals 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.

[0038] 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). Furthermore, 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0046] 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.

[0047] 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.

[0048] 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).

[0049] 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.

[0050] 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.

[0051] 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).

[0052] 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.

[0053] 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.

[0054] In addition to the structure of the DS described above, an extended service set (ESS) may be established to provide wider coverage.

[0055] 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.

[0056] 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.

[0057] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] For example, the association request frame may include information about various capabilities, a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, RSN, 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.

[0068] 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.

[0069] 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.

[0070] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0071] 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.

[0072] 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).

[0073] 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 doubled value 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, ...).

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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 are described below with reference to FIG. 7.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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).

[0096] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0097] 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)).

[0098] 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).

[0099] 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)).

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.).

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.).

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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, 4X996-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.

[0124] 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.

[0125] 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.

[0126] Multi-link operation

[0127] Below, the multi-link (ML) operation supported by the STA according to the present disclosure is described.

[0128] 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.

[0129] When one STA supports multiple links, the transmitting and receiving devices supporting each link can operate as one logical STA. That is, an 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] When a link is disabled, that link may not be used for frame exchange, including management frames for both DL and UL.

[0136] 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.

[0137] 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.

[0138] FIG. 8 is a diagram illustrating an example of a high-level structure for an AP MLD to which the present disclosure can be applied.

[0139] An AP MLD may include one or more APs. An AP MLD may have a high-level architecture, as illustrated in FIG. 8. For example, the MLD may utilize the upper MAC sublayer to control various procedures / parameters common to multiple APs. For example, authentication, association, sequence number (SN) / packet number (PN) allocation, and power-saving buffering for individually addressed frames may be controlled in common among APs belonging to an AP MLD.

[0140] Each affiliated AP (e.g., AP 1, ..., AP n) can provide upper MAC sublayer functionality for non-MLD data frames (e.g., traffic transmitted and received with non-MLD STAs, group-addressed MLD traffic, etc.). The AP MLD can provide upper MAC sublayer functionality for MLD data frames (e.g., traffic transmitted and received with MLD STAs) and provide MLD data to the lower MAC sublayer of each affiliated AP. Each affiliated AP can provide PHY functionality (e.g., PHY 1, ..., PHY n). Both ML operations (MLO) and non-MLO can be performed on the links corresponding to each PHY (e.g., link 1, ..., link n).

[0141] How to change and notify AP modes and set listen intervals

[0142] In a basic wireless LAN system, an AP is always active to provide services requiring high throughput and / or low latency to associated STA(s), and can perform frame exchange using the highest possible bandwidth and a large number of spatial streams. In addition, the AP is constantly supplied with power while being fixedly located in one location to provide the same service, so the power consumption of the AP can be considerable. Accordingly, the maintenance cost of the network is increasing, and the problem of shortened battery life of battery-operated APs (e.g., mobile APs) is emerging.

[0143] Additionally, considering the introduction of multi-link operation and multi-AP cooperative networks, the number of links and STAs operated by each MLD may increase, which may further increase the power consumption of the AP.

[0144] Below, a method for supporting power saving of an AP is described to address the aforementioned issues. While this disclosure describes a method for reducing power consumption on the AP side, the methods described below can be applied not only to the AP but also to all STAs. That is, various embodiments of this disclosure relate to a unified framework applicable to all APs and / or non-AP STAs. The positions / names of the values / names / (sub)fields described in this disclosure may be modified, and STAs may include non-AP STAs and AP STAs.

[0145] FIG. 9 is a flowchart illustrating the operation of a first STA according to an embodiment of the present disclosure. In one example of the present disclosure, the first STA is an STA affiliated with a non-AP MLD, and the first AP may be affiliated with an AP MLD. Furthermore, the first STA may be associated with the first AP, but is not limited thereto. The operation of the first STA may correspond to the operation of the non-AP MLD, and the operation of the first AP may correspond to the operation of the AP MLD.

[0146] The first STA can receive a first frame including first information related to the current mode of the first access point (AP) and second information related to the status of the first AP from the AP MLD (S910).

[0147] And, the first STA can decode the first frame (S920).

[0148] For example, a first frame (e.g., a management frame, a control frame, or a data frame, etc.) may include at least one of a link identifier (ID) field associated with a first AP, an AP current mode field, an AP PS mode field, or an AP status field. The link ID field associated with the first AP may include an ID of a link associated with the first AP.

[0149] As an example of the present disclosure, the first information may be related to at least one of an active mode, a scheduled PS mode, an unscheduled PS mode, or a dynamic PS mode. In addition, the first information may be set by at least one of an AP current mode field or an AP PS mode field.

[0150] For example, at least one of the active mode, the scheduled PS mode, the unscheduled PS mode, or the dynamic PS mode may be indicated by the AP current mode field. As another example, the active mode or the PS mode may be indicated by the AP current mode field, and when the PS mode is indicated by the AP current mode field, the AP PS mode field may indicate one of the scheduled PS mode, the unscheduled PS mode, or the dynamic PS mode.

[0151] And, the second information may be related to one of an awake state, a doze state, or a listening state. The second information may be set by the AP status field of the first frame.

[0152] For example, if the first information relates to the active mode, the second information may relate to the awake state. That is, based on the active mode being indicated by the AP current mode field, the awake state may be indicated by the AP status field. When the first AP is in the awake state, the first STA may perform data transmission and reception operations with the first AP.

[0153] For example, based on the first information being related to a scheduled PS mode, the state of the first AP may be periodically transitioned from an awake state to a sleep state or from a sleep state to an awake state. When the first AP transitions from an awake state (or a sleep state) to a sleep state (e.g., an awake state), the first STA may receive a frame including an AP state field in which the current state of the AP is set from an AP MLD (e.g., a first AP belonging to an AP MLD or another AP belonging to the same AP MLD (e.g., an AP MLD to which the first AP belongs)).

[0154] As another example, assume that the first information is related to an unscheduled PS mode. The first STA can request the AP MLD (e.g., the first AP belonging to the AP MLD or another AP belonging to the same AP MLD) to transition the state of the first AP to an awake state. For example, the first STA can transmit a frame for transitioning the current state (e.g., a polling frame) to the AP MLD (e.g., the first AP belonging to the AP MLD or another AP belonging to the same AP MLD). In response, the state of the first AP can transition from a sleep state to an awake state. In addition, the first STA can receive a frame including an AP state field in which the awake state is set from the first AP. In this case, if the first AP is in a sleep state, the first STA can transmit the above-described frame to another AP belonging to the AP MLD. As another example, if the first AP is not in a sleeping state (e.g., awake state), the first STA may transmit the frame described above to the first AP belonging to the AP MLD.

[0155] As another example, if the first information relates to the dynamic PS mode, the second information may relate to the listening state or the awake state. For example, the first STA may transmit an initial control frame (ICF) to the AP MLD (e.g., the first AP). In response, the state of the first AP may transition from the sleep state to the listening state or the awake state. In addition, the first STA may receive a frame from the first AP that includes an AP state field in which the listening state or the awake state is set.

[0156] For example, based on the state of the first AP being in a listening state, data may be transmitted to the first AP from at least one STA associated with the first AP. That is, an AP in a listening state may receive data from the STA(s) associated with it. At this time, the at least one STA may include, but is not limited to, the first STA.

[0157] Prior to step S910, the first STA may transmit a second frame containing capability information indicating that the first STA supports operations related to AP power saving to the AP MLD (e.g., the first AP). The AP MLD (e.g., the first AP) may transmit the first frame to the first STA after confirming that the first STA supports operations related to AP power saving.

[0158] As an example of the present disclosure, based on the second information being related to a sleep state (e.g., based on the first AP being in a sleep state), the first STA may receive the first frame from a second AP belonging to an AP MLD (e.g., an AP supporting AP power saving). The second AP may forward the first frame (or at least one type of information included in the first frame) received from the first STA to the first AP. Based on the second information not being related to a sleep state (e.g., in an awake state or a listening state), the first STA may receive the first frame directly from the first AP.

[0159] As an example of the present disclosure, a listen interval between a non-AP MLD and an AP MLD may be based on at least one beacon interval of at least one AP among a plurality of APs included in the AP MLD, and a mode of the at least one AP may be at least one of an active mode or a dynamic PS mode. That is, a beacon interval of an AP that is at least one of a scheduled PS mode or an unscheduled PS mode among a plurality of APs included in the AP MLD may be excluded when determining a listen interval between a non-AP MLD and an AP MLD.

[0160] The method described in the example of FIG. 9 may be performed by the first device (100) of FIG. 1. For example, one or more processors (102) of the first device (100) of FIG. 1 may receive a first frame, which includes first information related to a current mode of a first AP belonging to the AP MLD and second information related to a status of the first AP, from the AP MLD via one or more transceivers (106). The one or more processors (102) may decode the first frame.

[0161] Furthermore, one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 9 or the examples described below when executed by one or more processors (102).

[0162] FIG. 10 is a flowchart for explaining the operation of the first AP according to one embodiment of the present disclosure.

[0163] The first AP can generate a first frame including first information related to the current mode and second information related to the status of the first AP (S1010).

[0164] And, the first AP can transmit the first frame to the non-AP MLD (S1020).

[0165] Prior to step S1010, the first AP may determine whether a non-AP MLD (e.g., a first STA belonging to a non-AP MLD) supports an AP power saving mode / operation. For example, the first AP may receive a second frame from the first STA that includes capability information indicating that the first AP supports an operation related to AP power saving.

[0166] If a non-AP MLD (e.g., a first STA belonging to a non-AP MLD) identifies that it supports the AP power saving mode / operation, the first AP may transmit a first frame to the non-AP MLD.

[0167] At this time, the first AP may not be in a sleeping state. If the first AP is in a sleeping state, a second AP belonging to the AP MLD may transmit the first frame to a non-AP MLD, but this is not limited thereto.

[0168] The configuration of the first frame and the setting of the listen interval between the non-AP MLD and the AP MLD have been described with reference to Fig. 9, so any redundant description will be omitted.

[0169] The method described in the example of FIG. 10 may be performed by the second device (200) of FIG. 1. For example, one or more processors (202) of the second device (200) of FIG. 1 may generate a first frame including first information related to a current mode and second information related to a state of a first AP. The one or more processors (202) may transmit the first frame as a non-AP MLD via one or more transceivers (206).

[0170] Furthermore, one or more memories (204) of the second device (200) may store instructions for performing the method described in the example of FIG. 10 or the examples described below when executed by one or more processors (202).

[0171] Below, we will specifically describe the state of an AP with power save mode applied, how the AP saves power, how it notifies when the AP's mode changes, and how to set the listen interval between the AP MLD and non-AP MLD.

[0172] Example 1

[0173] Example 1 relates to the state of an AP to which power saving mode is applied.

[0174] In describing the present disclosure, an AP may transition / change from an awake state to a doze state when operating in a power-saving mode. For example, when the AP operates in power-saving mode, the AP may operate in an awake state capable of transmitting and receiving data with STA(s), or may operate in a doze state in which it cannot transmit and receive data with STA(s) and operates with low power. When the AP is in active mode, it may always operate in an awake state.

[0175] Additionally or alternatively, when the AP operates in power saving mode or active mode, the state / mode in which the AP does not transmit data to the STA(s) but only receives data from the STA(s) is expressed as a listening state / mode. In this case, the AP can perform low-power operation (e.g., operation on the primary 20 MHz).

[0176] Example 2

[0177] Embodiment 2 relates to a method for an AP to save power. In the present disclosure, the method / mode for the AP to save power may include, but is not limited to, a scheduled power save mode, an unscheduled power save mode, and / or a dynamic power save mode. The AP may support various types of power modes in addition to the three modes described above.

[0178] Scheduled power saving mode

[0179] An AP supporting scheduled power saving mode can periodically transition between an awake state and a sleep state. At this time, the AP can schedule a period of transition from a sleep state to an awake state based on a target wake time (TWT) scheme and / or a link disablement / enablement scheme. Furthermore, the AP can notify associated STA(s) of information regarding the scheduled period. The AP can remain awake within the announced scheduled period, but can remain in a sleep state outside of the scheduled period.

[0180] Here, TWT is a PS (Power Saving) technology that can improve the energy efficiency of non-AP STAs by defining a Service Period (SP) between APs and non-AP STAs and sharing information about the SP to reduce contention of the medium. The operation of scheduling and announcing the interval for transitioning from a sleep state to an awake state using the TWT method may include an operation of scheduling and announcing the interval through parameters / elements / frames related to TWT.

[0181] And, the operation of scheduling and notifying the interval for transitioning from the sleep state to the awake state in a link activation / deactivation manner may include the operation of scheduling and notifying the interval through a parameter / element frame transmitted to perform link activation / deactivation with the combined STA(s).

[0182] Additionally, an AP supporting scheduled power saving mode can schedule the time to enter / transition to the awake state using the responder power management (PM) mode based on the TWT. The AP can then notify the associated STA(s) of the scheduled time.

[0183] Here, the responder PM mode refers to a mode that allows an AP or a TWT responder (e.g., a non-AP STA) to enter a sleep state during times other than the TWT SP. For example, if the responder PM mode subfield value included in the TWT element transmitted by the AP to the STA is set to 1, this may mean that the AP operates in a sleep state during times other than the SP. Here, not only UHR STAs but also HE / EHT STA(s) supporting individual / broadcast TWT can determine that the AP is in a sleep state outside of the corresponding SP.

[0184] However, STAs of pre-HE versions (e.g., VHT STAs, etc.) may not understand the above-described operation based on the responder PM mode subfield. For example, assume that the AP power saving mode cannot be operated on 2.4 GHz or 5 GHz where pre-HE STA(s) exist. In this case, a scheduled power saving mode using the TWT-based responder PM mode may be operated for STA(s) supporting individual and broadcast TWT on 6 GHz where HE STA(s) and later versions of STAs (e.g., EHT STAs, UHR STAs) can operate.

[0185] Unscheduled power saving mode

[0186] An AP supporting unscheduled power-saving mode transitions from a sleep state to an awake state only upon request from an STA. For example, if an STA transmits a power-saving mode-related request signal (e.g., a polling signal) to the AP, the AP may transition from a sleep state to an awake state in response to the request signal, but is not limited thereto.

[0187] For example, an STA can transmit a polling request signal to an AP that is awake within the AP MLD. The AP within the AP MLD that receives the polling request signal can notify other AP(s) that are asleep within the same AP MLD of whether or not the polling request signal has been received. Through this, the other AP(s) that are asleep within the AP MLD can transition / change from the asleep state to the awake state and then perform transmission and reception operations with the associated STA(s).

[0188] Dynamic Power Saving Mode

[0189] An AP supporting dynamic power saving mode may transition from a sleep state to an awake state upon receiving an initial control frame (ICF) from an STA, and transmit an initial control response (ICR) frame to the STA from the awake state. At this time, the AP may transition from a sleep state in which data transmission and reception are impossible to an awake state and / or operate in a listening mode in which data can be received from the associated STA(s).

[0190] Additionally, the dynamic power saving mode can operate in conjunction with other power saving (PS) modes and active modes. For example, an AP can enter a listening mode / state based on the dynamic PS mode from an awake state in the active mode or scheduled / unscheduled PS mode, thereby reducing power consumption.

[0191] Example 3

[0192] Embodiment 3 relates to a method for notifying associated STA(s) when an AP changes its mode. The operation of the AP changing its mode may include an operation of switching / changing the PS mode of the AP from a specific PS mode to another PS mode and an operation of switching / changing the mode of the AP between an active mode and a PS mode.

[0193] The AP may transmit / announce information about whether a mode has been changed to the associated STA(s) through at least one of the methods described below. The information about whether a mode has been changed may be transmitted to the associated STA(s) through a beacon frame. Additionally, the information about the mode change may be transmitted / announced through a management frame, a control frame, a data frame (or / and elements) on the basic wireless LAN system and / or a new management frame, a control frame, a data frame (or / and elements).

[0194] Additionally, the notification / transmission of information about a mode change according to the present disclosure may include i) an operation of an AP supporting PS mode notifying / transmitting information about a mode change and ii) an operation of another AP in an active state within the same AP MLD notifying / transmitting information about an AP within the AP MLD supporting PS mode.

[0195] Additionally or alternatively, in describing the present disclosure, an AP status field containing information related to the status of the AP may be configured as described in one of Embodiments 3-1 to 3-3 described below.

[0196] For example, assume that the AP announces / transmits information related to whether or not to change modes in one of the methods of Embodiments 3-1 to 3-3. In this case, if the status of the AP is separately indicated according to the method / procedure related to each PS mode(s), the AP status field indicating its own status information may not exist in at least one of Embodiments 3-1 to 3-3.

[0197] Example 3-1

[0198] Example 3-1 relates to a method of notifying the mode of an AP through a mode / status related field.

[0199] As an example of the present disclosure, the AP may notify information related to the mode / state of the AP by transmitting a frame / element related to the mode of the AP to the STA(s) as illustrated in (a) of FIG. 11. As an example, the frame / element related to the mode of the AP may include a link ID field, an AP current mode field, an AP PS mode field, and / or an AP state field.

[0200] The Link ID field may contain information about the AP to which the information following the Link ID field applies (e.g., the ID of the AP, the ID of the link connected to the AP, etc.).

[0201] The AP Current Mode field may include information indicating whether the current mode of the AP indicated by the Link ID field is the active mode or the PS mode. For example, the AP Current Mode field may include a bit indicating whether the AP is in the active mode and / or a bit indicating whether the AP is in the PS mode.

[0202] When the AP operates in PS mode (e.g., when the AP Current Mode field indicates that the current mode of the AP is the PS mode), the AP PS Mode field may include information indicating the type of PS mode of the AP (e.g., scheduled PS mode, unscheduled PS mode, dynamic PS mode, etc.). That is, when the AP Current Mode field is set to a value (e.g., 1) indicating that the current mode of the AP is the PS mode, the AP PS Mode field may include information indicating the type of PS mode of the AP. When the AP Current Mode field is not set to a value indicating that the current mode of the AP is the PS mode, the AP PS Mode field may be reserved.

[0203] For example, the AP PS mode field may include, but is not limited to, a scheduled PS mode subfield (e.g., a subfield indicating whether the AP is in a scheduled PS mode field), an unscheduled PS mode subfield (e.g., a subfield indicating whether the AP is in a unscheduled PS mode field), and a dynamic PS mode subfield (e.g., a subfield indicating whether the AP is in a dynamic PS mode field).

[0204] The AP status field can indicate the status of the AP, and the type of information that can be indicated by the AP status field can vary based on the value of the AP current mode field. As illustrated in (a) of FIG. 11, the AP status field can include, but is not limited to, an awake status subfield (e.g., a subfield indicating whether the AP is in an awake state), a sleep status subfield (e.g., a subfield indicating whether the AP is in a sleep state), and a listening mode / status subfield (e.g., a subfield indicating whether the AP is in a listening mode / status).

[0205] For example, based on the AP current mode field indicating that the AP is in active mode, only the awake state subfield of the AP status field may be set to a value (e.g., 1) indicating that the AP is in awake state. At this time, the remaining subfields of the AP status field (e.g., the sleep state subfield and the listening state / mode subfield) may be reserved or set to a value (e.g., 0) indicating that the AP is not in sleep state and not in listening state / mode.

[0206] As another example, based on the AP Current Mode field indicating that the AP is in PS mode, each of the Awake State subfield and the Sleep State subfield within the AP Status subfield may be set to a value (e.g., 1) indicating that the AP is in the Awake State or Sleep State.

[0207] As another example, if the AP Current Mode field indicates that the AP is in PS mode and the AP PS Mode field indicates that the AP is operating in dynamic PS mode, only the Awake State subfield and the Listening Mode / Status subfield within the AP Status field may be set to values ​​(e.g., 1) indicating the Awake State or Listening State / Mode. In this case, if the Dynamic PS Mode is not defined, the Listening subfield within the AP Status field may not be present.

[0208] Example 3-2

[0209] Example 3-2 relates to a method for notifying AP mode information in bitmap format.

[0210] As an example of the present disclosure, the AP may notify information related to the mode / status of the AP by transmitting a frame / element related to the mode of the AP to the STA(s), as illustrated in (b) of FIG. 11. As an example, the frame / element related to the mode of the AP may include a link ID field, an AP current mode field, and / or an AP status field.

[0211] The Link ID field may contain information about the AP to which the information following the Link ID field applies (e.g., the ID of the AP, the ID of the link connected to the AP, etc.).

[0212] The AP Current Mode field may include / set a bitmap indicating i) whether the current mode of the AP indicated by the Link ID field is the Active mode or the PS mode, and ii) if the AP is in the PS mode, the type of the PS mode. For example, if the size of the AP Current Mode field (e.g., bitmap) is 4 bits, each of the 4 bits may mean the Active mode, the Scheduled PS mode, the Unscheduled PS mode, and the Dynamic PS mode (in order or regardless of the order). For example, if a specific bit value among the 4 bits is set to 1, this may mean that the AP operates in the mode corresponding to the specific bit.

[0213] For example, the bitmap set in the AP current mode field and the mode corresponding to the value of the bitmap can be configured as in Table 1, but is not limited thereto.

[0214] AP Current Mode Field Value Meaning 1000 Activated Mode 0100 Scheduled PS Mode 0010 Unscheduled PS Mode 0001 Dynamic PS Mode 1001 Activated Mode and Dynamic PS Mode 0101 Scheduled PS Mode and Dynamic PS Mode 0011 Unscheduled PS Mode and Dynamic Mode

[0215] The AP status field can indicate the status of the AP, and the value that the AP status field can have can be determined depending on the value of the AP current mode field.

[0216] As illustrated in (b) of FIG. 11, the AP status field may include, but is not limited to, an awake status subfield (e.g., a subfield indicating whether the AP is in an awake state), a sleep status subfield (e.g., a subfield indicating whether the AP is in a sleep state), and a listening mode / status subfield (e.g., a subfield indicating whether the AP is in a listening mode / status).

[0217] For example, based on the AP current mode field indicating that the AP is in active mode, only the awake state subfield of the AP status field may be set to a value (e.g., 1) indicating that the AP is in awake state. At this time, the remaining subfields of the AP status field (e.g., the sleep state subfield and the listening state / mode subfield) may be reserved or set to a value (e.g., 0) indicating that the AP is not in sleep state and not in listening state / mode.

[0218] As another example, based on the AP Current Mode field indicating that the AP is in PS mode, each of the Awake State subfield and the Sleep State subfield within the AP Status subfield may be set to a value (e.g., 1) indicating that the AP is in the Awake State or Sleep State.

[0219] As another example, if the AP Current Mode field indicates that the AP is operating in dynamic PS mode, only the Awake State subfield and the Listening Mode / Status subfield within the AP Status field may be set to values ​​indicating the Awake State or Listening State / Mode (e.g., 1).

[0220] Additionally, when the AP current mode field indicates dynamic mode and other modes (e.g., active mode, scheduled PS mode, and / or unscheduled PS mode, etc.), the awake state subfield, the sleep state subfield, and the listening mode / state subfield within the AP status field may indicate that the AP is in the awake state, the sleep state, or the listening mode / state, respectively. That is, the sleep state subfield and the listening mode / state subfield may each be set to a value (e.g., 1 or 0) indicating that the AP is in the awake state, the sleep state, or the listening mode / state. In this case, if the dynamic PS mode is not defined, the listening subfield within the AP status field may not exist.

[0221] Example 3-3

[0222] Example 3-3 relates to a method of notifying AP mode information in an index format.

[0223] As an example of the present disclosure, the AP may notify information related to the mode / status of the AP by transmitting a frame / element related to the mode of the AP to the STA(s), as illustrated in FIG. 12. As an example, the frame / element related to the mode of the AP may include a link ID field, an AP current mode field, and / or an AP status field.

[0224] The Link ID field may contain information about the AP to which the information following the Link ID field applies (e.g., the ID of the AP, the ID of the link connected to the AP, etc.).

[0225] The AP Current Mode field may include / set an index indicating i) whether the current mode of the AP indicated by the Link ID field is the active mode or the PS mode, and ii) the type of the PS mode if the AP is in the PS mode. For example, as illustrated in FIG. 12, each index value set in the AP Current Mode field may indicate at least one of the active mode, the scheduled PS mode, the unscheduled PS mode, and the dynamic PS mode. However, this is merely an embodiment, and the type of the mode corresponding to the index value set in the AP Current Mode field may be set differently from FIG. 12.

[0226] The AP status field is the same as the AP status field described in Example 3-2, so any duplicate description will be omitted.

[0227] Example 4

[0228] Embodiment 4 relates to a method for setting a listen interval between an AP MLD and a non-AP MLD that support AP power saving. That is, Embodiment 4 relates to a method for setting a listen interval between an AP MLD and a non-AP MLD that support AP power saving based on a method in which an AP transmits / announces information related to a mode change to associated STA(s) when its mode is changed.

[0229] The listen interval on the MLD can be set by negotiation based on the ML (multi-link) setup request and ML setup response. The ML setup request and ML setup response can be transmitted and received through a (re)association request frame and a (re)association response frame, respectively. An STA can transmit a (re)association request frame including a listen interval field to another STA (e.g., an AP). The STA can wake up at each time corresponding to the listen interval value and receive a beacon frame and / or other messages from the AP.

[0230] At this time, the value of the listen interval field can be requested / determined based on the longest value among the beacon intervals of the AP(s) requested within the AP MLD for ML setup through the (re)association request frame.

[0231] For example, although each AP(s) within the AP MLD may have a different beacon interval (e.g., the time interval at which each AP periodically broadcasts a beacon frame), the listen interval at the MLD level may be determined / set based on the beacon interval of one AP. For example, as illustrated in FIG. 13, if the request frame transmitted by the STA is approved by the AP MLD, the listen interval at the MLD level may be set to a multiple of the beacon interval value of a specific AP (e.g., the AP(s) within the AP MLD having the longest beacon interval). After the listen interval at the MLD level is set, the AP(s) within the AP MLD may buffer DL data and / or UL data for a period corresponding to the listen interval value.

[0232] For example, if a beacon interval of a specific AP supporting AP power saving among the APs in the AP MLD has the largest value, the AP MLD and non-AP MLD(s) can set the listen interval based on the beacon interval of the AP supporting AP power saving. The AP in the AP MLD supporting AP power saving can set the beacon interval to a long value in order to reduce the number of times it transitions to the awake state to transmit / receive beacon frames (taking into account the time it is in the sleeping state). For the AP(s) in the AP MLD that do not support AP power saving, the set beacon interval may correspond to a relatively long time for storing and retaining buffered DL data frames.

[0233] Therefore, when a non-AP MLD performs negotiation with an AP MLD through ML setup request (e.g., (re)association request frame) and ML setup response (e.g., (re)association response frame), the non-AP MLD may exclude beacon interval(s) of AP(s) indicating that it operates / supports AP power saving operation according to the present disclosure when determining the listen interval.

[0234] Here, referring to (a) of FIG. 11, the case instructing to operate / support AP power saving operation may include all cases except the case where the activation mode subfield of the AP current mode field is set to 1 (e.g., a value indicating that the AP is in activation mode) and the power saving subfield value of the AP current mode field is set to 0 (e.g., a value indicating that the AP is not in PS mode).

[0235] As another example, referring to (b) of FIG. 11 and FIG. 12, the value indicating that the AP power saving operation is to be operated / supported may mean the remaining value(s) except for the value indicating the active mode of the AP current mode field.

[0236] Additionally or alternatively, referring to (a) of FIG. 11, the case of indicating that AP power saving is being operated / supported may include all cases except for the cases where i) the activation mode subfield value in the AP current mode field is set to 1 (e.g., a value indicating that the AP is in activation mode) and the power saving subfield value in the AP current mode field is set to 0 (e.g., a value indicating that the AP is not in PS mode) and ii) the activation mode subfield value is set to 0 (e.g., a value indicating that the AP is not in activation mode), the power saving subfield value is set to 1 (e.g., a value indicating that the AP is in PS mode), and the dynamic PS mode subfield value in the AP PS mode field is set to 1 (e.g., a value indicating that the AP operates in dynamic PS mode). At this time, the scheduled PS mode subfield within the AP PS mode field may be set to 0 (e.g., a value indicating that the AP does not operate in the scheduled PS mode), and the unscheduled PS mode subfield within the AP PS mode field may be set to 0 (e.g., a value indicating that the AP does not operate in the unscheduled PS mode).

[0237] As another example, referring to (b) of FIG. 11 and FIG. 12, the values ​​indicating to operate / support AP power saving operation may include all values ​​except the values ​​indicating the activation mode within the AP current mode field and the values ​​indicating to operate dynamic PS mode.

[0238] Additionally or alternatively, referring to (b) of FIG. 11 and FIG. 12, the cases indicating that AP power saving is being operated / supported may include all cases except for i) the case where the activation mode subfield value in the AP current mode field is set to 1 and the power saving subfield value in the AP current mode field is set to 0, ii) the case where the activation mode subfield value is set to 0, the power saving subfield value is set to 1, and the dynamic PS mode subfield value in the AP PS mode field is set to 1 (in which case, the scheduled PS mode subfield in the AP PS mode field is set to 0, and the unscheduled PS mode subfield in the AP PS mode field is set to 0), and iii) the case where the activation mode subfield value is set to 1, the AP PS mode field value is set to 1, and the dynamic PS mode subfield value is set to 1 (in which case, the scheduled PS mode subfield is set to 0, and the unscheduled PS mode subfield is set to 0).

[0239] As another example, referring to (b) of FIG. 11 and FIG. 12, the values ​​indicating to operate / support AP power saving operation may include all values ​​except the values ​​indicating the activation mode within the AP current mode field, the values ​​indicating to operate dynamic PS mode, and the values ​​indicating to operate activation mode / dynamic PS mode together.

[0240] Example 5

[0241] Example 5 relates to the operations of each of an AP and an STA that support AP power saving. Example 5-1 relates to the operations of a transmitting STA (e.g., an AP, etc.), and Example 5-2 relates to the operations of a receiving STA (e.g., a non-AP STA, etc.).

[0242] Example 5-1

[0243] As an example of the present disclosure, if a transmitting STA supports the AP power saving mode, the transmitting STA can determine whether the receiving STA recognizes and / or supports the power saving operation of the AP. If the receiving STA supports the strategic saving operation of the AP, the transmitting STA can enter the power saving mode and operate in an awake state or a sleep state / listening state (mode). For example, whenever the transmitting STA switches between the aforementioned states / modes, the transmitting STA can notify the receiving STA of information(s) regarding the switched state / mode.

[0244] For example, if the transmitting STA is an AP that has an awake state within the AP MLD, the transmitting STA may also notify the receiving STA of information about a mode change of another AP within the same AP MLD (e.g., another AP that supports the AP power saving mode).

[0245] Example 5-2

[0246] As an example of the present disclosure, if a receiving STA recognizes and supports a power saving operation of an AP, the receiving STA may receive a notification from the transmitting STA regarding power saving-related information of the AP corresponding to a link ID indicated by the transmitting STA. Based on the notification received from the transmitting STA, the receiving STA may recognize a current mode of the transmitting STA that operates the power saving operation and / or information related to the current mode (e.g., a current status). For example, if the transmitting STA is in an awake state, the receiving STA may attempt to transmit and receive data with the transmitting STA.

[0247] At least one of the above-described embodiments of the present disclosure (e.g., Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 3-1, Embodiment 3-2, Embodiment 3-3, Embodiment 4, Embodiment 5, Embodiment 5-1, Embodiment 5-2) may be applied, and a combination between the embodiments may also be applied.

[0248] 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.

[0249] 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.

[0250] 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.

[0251] The method proposed in this disclosure is 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 method performed by a non-access point (AP) multi-link device (MLD), the method comprising: A step of receiving a first frame including first information related to a current mode of a first AP affiliated with the AP MLD and second information related to a status of the first AP from the AP MLD by a first station (STA) affiliated with the non-AP MLD; and A step of decoding the first frame by the first STA, The listen interval between the non-AP MLD and the AP MLD is based on at least one beacon interval of at least one AP among the plurality of APs included in the AP MLD, A method wherein the mode of at least one AP is at least one of an active mode or a dynamic power saving (PS) mode.

2. In paragraph 1, The first information relates to at least one of the activation mode, scheduled PS mode, unscheduled PS mode or dynamic PS mode, The second information is one of an awake state, a doze state, or a listening state.

3. In paragraph 2, A method wherein the second information is related to the awake state, based on the first information being related to the activation mode.

4. In paragraph 2, A method in which the state of the first AP is periodically switched from the awake state to the sleep state based on the first information being related to the scheduled PS mode.

5. In paragraph 2, Based on the above first information being related to the unscheduled PS mode: A method in which the state of the first AP is switched from the sleep state to the awake state based on a polling frame being transmitted from the first STA to the second AP belonging to the AP MLD.

6. In paragraph 2, Based on the above first information being related to the dynamic PS mode: The second information is related to the listening state or the awake state, A method in which the state of the first AP is switched from the sleep state to the listening state or the awake state based on an initial control frame (ICF) being transmitted from the first STA to the first AP.

7. In paragraph 6, Based on the state of the first AP being the listening state, data is transmitted to the first AP from at least one STA associated with the first AP, A method wherein the first STA is included in at least one STA.

8. In paragraph 2, A method wherein the first frame is received from a second AP belonging to the AP MLD, based on the second information being related to the sleep state.

9. In paragraph 1, The first frame includes at least one of a link identifier field, an AP current mode field, an AP PS mode field, or an AP status field related to the first AP, The first information is set by at least one of the AP current mode field or the AP PS mode field, The above second information is set by the AP status field.

10. In paragraph 1, A method wherein a second frame containing capability information indicating that an operation related to AP power saving is supported by the first STA is transmitted from the first STA to the AP MLD.

11. In paragraph 1, The method wherein the first frame is one of a management frame, a control frame or a data frame.

12. In a first station (STA) device belonging to a non-access point (AP) multi-link device (MLD), the first STA: 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: Receiving a first frame including first information related to a current mode of a first AP belonging to an AP MLD and second information related to a status of the first AP from the AP MLD through the one or more transceivers; and A step of decoding the first frame by the first STA, The listen interval between the non-AP MLD and the AP MLD is based on at least one beacon interval of at least one AP among the plurality of APs included in the AP MLD, The mode of the at least one AP is at least one of an active mode or a dynamic power saving (PS) mode, the first STA.

13. A method performed by an access point (AP) multi-link device (MLD), the method comprising: A step of generating a first frame including first information related to a current mode of a first AP affiliated with an AP MLD and second information related to a status of the first AP; and A step of transmitting the first frame to a non-AP MLD by a first access point (AP) belonging to the AP MLD, The listen interval between the non-AP MLD and the AP MLD is based on at least one beacon interval of at least one AP among the plurality of APs included in the AP MLD, A method wherein the mode of at least one AP is at least one of an active mode or a dynamic power saving (PS) mode.

14. In a first AP belonging to an access point (AP) multi-link device (MLD), the first AP: 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: Generating a first frame including first information related to a current mode of a first AP belonging to an AP MLD and second information related to a status of the first AP; and The first frame is set to be transmitted via the one or more transceivers as a non-AP MLD, The listen interval between the non-AP MLD and the AP MLD is based on at least one beacon interval of at least one AP among the plurality of APs included in the AP MLD, The mode of at least one AP is at least one of an active mode or a dynamic power saving (PS) mode, the first AP.

15. In a processing device configured to control a first station (STA) 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 for performing the method according to claim 1 based on execution by said one or more processors.

16. 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 first STA in a wireless LAN system to perform the method according to claim 1.

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