Method and apparatus for transmitting or receiving in-device coexistence-related information in wireless LAN system

Abstract

Disclosed are a method and apparatus for transmitting or receiving in-device coexistence-related information in a wireless LAN system. The method according to an embodiment of the present disclosure comprises the steps of: receiving, by a first STA from a second STA, a first TWT element comprising at least one broadcast TWT parameter set field, wherein on the basis that an external time of at least one broadcast TWT SP related to the at least one broadcast TWT parameter set field does not belong within another TWT SP, a first NDP paging indicator / unavailable mode subfield value included in the TWT element is set to 0; and on the basis that the external time of the at least one TWT SP belongs within a specific TWT SP, receiving, by the first STA from the second STA, a first frame comprising a second TWT element, wherein a second NDP indicator / unavailable mode subfield value of the second TWT element may be set to 1, and the first frame may comprise information related to an update of an NDP paging / indicator unavailable mode subfield.

Description

Method and device for transmitting or receiving information related to internal coexistence of a terminal in a wireless LAN system

[0001] The present disclosure relates to a method and apparatus for transmitting or receiving information related to in-device coexistence (IDC) in a Wireless Local Area Network (WLAN) system.

[0002] New technologies have been introduced for wireless LANs (WLANs) to improve transmission rates, increase bandwidth, enhance reliability, reduce errors, and reduce latency. Among wireless LAN technologies, the IEEE (Institute of Electrical and Electronics Engineers) 802.11 series of standards can be referred to as Wi-Fi. For example, technologies recently introduced to wireless LANs 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 an improved wireless communication environment, advanced technologies for Extremely High Throughput (EHT) are being discussed. For example, technologies for Multiple Input Multiple Output (MIMO) supporting increased bandwidth, efficient utilization of multiple bands, and increased spatial streams, as well as technologies for multiple access points (AP) coordination, are being researched. In particular, various technologies are being studied to support traffic with low latency or real-time characteristics. Furthermore, new technologies to support ultra-high reliability (UHR), including improvements or extensions of EHT technology, are being discussed.

[0004] The technical problem of the present disclosure is to provide a method and apparatus for transmitting or receiving information related to in-device coexistence (IDC) in a wireless LAN system.

[0005] The technical problem of the present disclosure is to provide a method and apparatus for using a broadcast target wake time (TWT) for periodic unavailability operation (PUO) and scheduled AP power save operation due to an IDC.

[0006] The technical problems to be solved in this disclosure are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this disclosure belongs from the description below.

[0007] A method according to one embodiment of the present disclosure comprises the step of receiving a first TWT element including at least one broadcast target wake time (TWT) parameter set field from a second STA by a first station (STA), wherein, based on the fact that the outside time of at least one broadcast TWT service period (SP) associated with the at least one broadcast TWT parameter set field does not fall within another TWT SP, the value of a first null data physical layer protocol data unit (NDP) paging indicator / unavailability mode subfield included in the first TWT element is set to 0; and based on the fact that the external time of at least one TWT SP belongs within a specific TWT SP, the method includes the step of receiving a first frame containing a second TWT element from the second STA by the first STA, wherein the second NDP indicator / unavailable mode subfield value of the second TWT element is set to 1, and the first frame may include information related to the update of the NDP paging / indicator unavailable mode subfield.

[0008] A method according to another embodiment of the present disclosure comprises the step of transmitting a first TWT element, comprising at least one broadcast target wake time (TWT) parameter set field, to a first STA by a second station (STA), wherein, based on the fact that the outside time of at least one broadcast TWT service period (SP) associated with the at least one broadcast TWT parameter set field does not fall within another TWT SP, the value of a first null data physical layer protocol data unit (NDP) paging indicator / unavailability mode subfield included in the first TWT element is set to 0; and based on the fact that the external time of at least one TWT SP belongs within a specific TWT SP, the method includes the step of transmitting a first frame containing a second TWT element to the first STA by the second STA, wherein the second NDP indicator / unavailable mode subfield value of the second TWT element is set to 1, and the first frame may include information related to the update of the NDP paging / indicator unavailable mode subfield.

[0009] By various embodiments of the present disclosure, a method and apparatus for transmitting or receiving IDC-related information in a wireless LAN system may be provided.

[0010] By various embodiments of the present disclosure, a method and apparatus utilizing a broadcast TWT for PUO and scheduled AP power saving operations caused by an IDC may be provided.

[0011] By various embodiments of the present disclosure, problems that occur when time intervals according to a PUO schedule and time intervals other than other broadcast schedules overlap can be resolved.

[0012] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below.

[0013] The accompanying drawings, which are included as part of the detailed description to aid in understanding the present disclosure, provide embodiments of the present disclosure and explain the technical features of the present disclosure together with the detailed description.

[0014] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0015] FIG. 2 is a drawing showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0016] FIG. 3 is a diagram illustrating a link setup process to which the present disclosure can be applied.

[0017] FIG. 4 is a drawing illustrating a backoff process to which the present disclosure may be applied.

[0018] FIG. 5 is a diagram illustrating a CSMA / CA-based frame transmission operation to which the present disclosure may be applied.

[0019] FIG. 6 is a drawing for illustrating an example of a frame structure used in a wireless LAN system to which the present disclosure may be applied.

[0020] FIG. 7 is a drawing illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure may be applied.

[0021] FIG. 8 is a drawing illustrating an example of an individual TWT operation to which the present disclosure may be applied.

[0022] FIG. 9 is a drawing illustrating an example of a broadcast TWT operation to which the present disclosure may be applied.

[0023] Figure 10 is a diagram illustrating an example of a TWT information element format.

[0024] Figure 11 is a diagram illustrating examples of individual TWT parameter set field formats.

[0025] Figure 12 is a diagram illustrating examples of broadcast TWT parameter set field formats.

[0026] FIG. 13 is a drawing illustrating an example of a collision caused by an IDC to which the present disclosure may be applied.

[0027] FIG. 14 illustrates an IDC event notification signaling procedure using an IDC broadcast TWT to which the present disclosure may be applied.

[0028] FIG. 15 is a diagram illustrating a method for scheduling awake and water sections to which the present disclosure can be applied.

[0029] FIG. 16 is a diagram illustrating the operation when the schedule for a scheduled PS overlaps with another periodic IDC SP.

[0030] FIG. 17 is a flowchart for explaining the operation of a first STA according to one embodiment of the present disclosure.

[0031] FIG. 18 is a flowchart for explaining the operation of a second STA according to one embodiment of the present disclosure.

[0032] FIG. 19 is a diagram illustrating a method for updating an NDP paging indicator / unavailable mode subfield through a DTIM beacon cycle according to one embodiment of the present disclosure.

[0033] FIGS. 20, FIGS. 21 and FIGS. 22 are drawings for illustrating a method for updating an NDP paging indicator / unavailable mode subfield according to one embodiment of the present disclosure.

[0034] FIG. 23 is a drawing for explaining a method of using a PUO ID according to one embodiment of the present disclosure.

[0035] Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description disclosed below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiment in which the present disclosure may be practiced. The following detailed description includes specific details to provide a complete understanding of the present disclosure. However, those skilled in the art will know that the present disclosure may be practiced without such specific details.

[0036] In some cases, to avoid obscuring the concept of the present disclosure, known structures and devices may be omitted or illustrated in the form of a block diagram focusing on the core functions of each structure and device.

[0037] In the present disclosure, when a component is described as being “connected,” “combined,” or “joined” with another component, this may include not only a direct connection but also an indirect connection in which another component exists between them. Furthermore, in the present disclosure, the terms “comprising” or “having” specify the presence of the mentioned features, steps, actions, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, actions, elements, components, and / or groups thereof.

[0038] In the present disclosure, terms such as "first," "second," etc. are used solely for the purpose of distinguishing one component from another and are not used to limit the components, nor do they limit the order or importance of the components unless specifically stated otherwise. Accordingly, within the scope of the present disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and likewise, a second component in one embodiment may be referred to as a first component in another embodiment.

[0039] The terms used in this disclosure are for the description of specific embodiments and are not intended to limit the claims. As used in the description of embodiments and in the appended claims, the singular form is intended to include the plural form unless the context clearly indicates otherwise. The term "and / or" as used in this disclosure may refer to any one of the related enumerated items, or refers to and includes any and all possible combinations of two or more of them. Additionally, the " / " between words in this disclosure has the same meaning as "and / or" unless otherwise noted.

[0040] The embodiments of the present disclosure may be applied to various wireless communication systems. For example, the embodiments of the present disclosure may be applied to wireless LAN systems. For example, the embodiments of the present disclosure may be applied to wireless LANs based on IEEE 802.11a / g / n / ac / ax / be standards. Furthermore, the embodiments of the present disclosure may be applied to wireless LANs based on newly proposed IEEE 802.11bn (or UHR) standards. Additionally, the embodiments of the present disclosure may be applied to wireless LANs based on next-generation standards following IEEE 802.11bn. Furthermore, the embodiments of the present disclosure may be applied to cellular wireless communication systems. For example, they may be applied to cellular wireless communication systems based on LTE (Long Term Evolution) series technologies and 5G NR (New Radio) series technologies of 3GPP (3rd Generation Partnership Project) standards.

[0041] The following describes the technical features to which the examples of the present disclosure may be applied.

[0042] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0043] The first device (100) and the second device (200) exemplified in FIG. 1 may be replaced with various terms such as terminal, wireless device, WTRU (Wireless Transmit Receive Unit), UE (User Equipment), MS (Mobile Station), UT (user terminal), MSS (Mobile Subscriber Station), MSS (Mobile Subscriber Unit), SS (Subscriber Station), AMS (Advanced Mobile Station), WT (Wireless terminal), or simply user. Additionally, the first device (100) and the second device (200) may be replaced with various terms such as access point (AP), base station (BS), fixed station, Node B, base transceiver system (BTS), network, artificial intelligence (AI) system, road side unit (RSU), repeater, router, relay, gateway, etc.

[0044] The device (100, 200) exemplified in FIG. 1 may be referred to as a station (STA). For example, the device (100, 200) exemplified in FIG. 1 may be referred to by various terms such as a transmitting device, a receiving device, a transmitting STA, or a receiving STA. For example, the STA (110, 200) may perform the role of an access point (AP) or a non-AP. That is, in the present disclosure, the STA (110, 200) may perform the functions of an AP and / or a non-AP. If the STA (110, 200) performs the AP function, it may simply be referred to as an AP, and if the STA (110, 200) performs the non-AP function, it may simply be referred to as a STA. Additionally, in the present disclosure, the AP may also be indicated as an AP STA.

[0045] 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) may include interfaces for the medium access control (MAC) layer and the physical layer (PHY) that comply with the specifications of the IEEE 802.11 standard.

[0046] In addition, the first device (100) and the second device (200) may additionally support various communication standards other than wireless LAN technology (e.g., 3GPP LTE series, 5G NR series standards, etc.). In addition, the device of the present disclosure may be implemented as various devices such as mobile phones, vehicles, personal computers, AR (Augmented Reality) equipment, VR (Virtual Reality) equipment, etc. Furthermore, the STA of the present specification may support various communication services such as voice calls, video calls, data communication, autonomous driving, MTC (Machine-Type Communication), M2M (Machine-to-Machine), D2D (Device-to-Device), and IoT (Internet-of-Things).

[0047] The first device (100) includes one or more processors (102) and one or more memories (104), and may additionally include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memory (104) and / or transceivers (106) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or sequences of operation disclosed in this disclosure. For example, the processor (102) may process information within the memory (104) to generate a first information / signal and then transmit a wireless signal containing the first information / signal through the transceiver (106). Additionally, the processor (102) may receive a wireless signal containing a second information / signal through the transceiver (106) and then store information obtained from the signal processing of the second information / signal in the memory (104). Memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, memory (104) may store software code including instructions for performing some or all of the processes controlled by the processor (102) or for performing the descriptions, functions, procedures, proposals, methods, and / or sequences of operation disclosed in this disclosure. Here, the processor (102) and memory (104) may be part of a communication modem / circuit / chip designed to implement wireless LAN technology (e.g., IEEE 802.11 series). A transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals through one or more antennas (108). The transceiver (106) may include a transmitter and / or receiver. The transceiver (106) may be combined with an RF (Radio Frequency) unit. In the present disclosure, the device may refer to a communication modem / circuit / chip.

[0048] The second device (200) includes one or more processors (202) and one or more memories (204), and may additionally include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memory (204) and / or transceivers (206) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or sequences of operation disclosed in this disclosure. For example, the processor (202) may process information within the memory (204) to generate a third information / signal and then transmit a wireless signal containing the third information / signal through the transceiver (206). Additionally, the processor (202) may receive a wireless signal containing a fourth information / signal through the transceiver (206) and then store information obtained from the signal processing of the fourth information / signal in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may store software code containing instructions for performing some or all of the processes controlled by the processor (202) or for performing the descriptions, functions, procedures, proposals, methods, and / or sequences of operation disclosed in this disclosure. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement 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 through one or more antennas (208). The transceiver (206) may include a transmitter and / or receiver. The transceiver (206) may be used in combination with an RF unit. In the present disclosure, the device may refer to a communication modem / circuit / chip.

[0049] Hereinafter, hardware elements of the device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this disclosure. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this disclosure. One or more processors (102, 202) may generate a signal (e.g., a baseband signal) including a PDU, SDU, message, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed in this disclosure and provide it to one or more transceivers (106, 206). One or more processors (102, 202) may receive a signal (e.g., a baseband signal) from one or more transceivers (106, 206) and may obtain a PDU, SDU, message, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this disclosure.

[0050] One or more processors (102, 202) may be referred to as a controller, microcontroller, microprocessor, or microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. 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 flowcharts disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this disclosure may be included in 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 sequences disclosed in this disclosure may be implemented using firmware or software in the form of code, instructions, and / or sets of instructions.

[0051] One or more memories (104, 204) may be connected to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. One or more memories (104, 204) may be composed of ROM, RAM, EPROM, flash memory, hard drive, registers, cache memory, computer read storage media, and / or combinations thereof. One or more memories (104, 204) may be located inside and / or outside of one or more processors (102, 202). Additionally, one or more memories (104, 204) may be connected to one or more processors (102, 202) through various technologies such as wired or wireless connections.

[0052] One or more transceivers (106, 206) may transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or operation flowcharts, etc., of the present disclosure to one or more other devices. One or more transceivers (106, 206) may receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or operation flowcharts, etc., disclosed in the present disclosure from one or more other devices. For example, one or more transceivers (106, 206) may be connected to one or more processors (102, 202) and may transmit and receive wireless signals. For example, one or more processors (102, 202) may control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be connected to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this disclosure through one or more antennas (108, 208). In this disclosure, one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can convert the received wireless signal / channel, etc. from an RF band signal to a baseband signal in order to process the received user data, control information, wireless signal / channel, etc. using one or more processors (102, 202).One or more transceivers (106, 206) can convert user data, control information, wireless signals / channels, etc. processed using one or more processors (102, 202) from baseband signals to RF band signals. To this end, one or more transceivers (106, 206) may include (analog) oscillators and / or filters.

[0053] 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 transceiver (106, 206) of FIG. 1 may perform the operation of transmitting and receiving signals (e.g., packets or PPDU (Physical Layer Protocol Data Unit) according to IEEE 802.11a / b / g / n / ac / ax / be / bn, etc.). Additionally, the operation of generating transmission and reception signals or performing data processing or calculations in advance for transmission and reception signals by various STAs in the present disclosure may be performed by the processor (102, 202) of FIG. 1. For example, an example of an operation to generate a transmission and reception signal or to perform data processing or operations in advance for a transmission and reception signal may include: 1) an operation to determine / acquire / configure / operate / decode / encode bit information of fields (SIG (signal), STF (short training field), LTF (long training field), Data, etc.) included in the PPDU; 2) an operation to determine / configure / acquire time resources or frequency resources (e.g., subcarrier resources) used for fields (SIG, STF, LTF, Data, etc.) included in the PPDU; 3) an operation to determine / configure / acquire specific sequences (e.g., pilot sequence, STF / LTF sequence, extra sequence applied to SIG) used for fields (SIG, STF, LTF, Data, etc.) included in the PPDU; 4) power control operations and / or power saving operations applied to the STA; and 5) operations related to determining / acquiring / configuring / operating / decoding / encoding of an ACK signal. In addition, various information (e.g., information related to fields, subfields, control fields, parameters, power, etc.) used by various STAs for determining / acquiring / configuring / calculating / decoding / encoding transmission and reception signals in the following example can be stored in the memory (104, 204) of FIG. 1.

[0054] In the following, the 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 the AP STA, and the receiver may be part of the non-AP STA. The 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 the non-AP STA, and the receiver may be part of the AP STA.

[0055] FIG. 2 is a drawing showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0056] The structure of a wireless LAN system can be composed of multiple components. Through the interaction of multiple components, a wireless LAN that supports STA mobility transparent to the upper layer can be provided. A Basic Service Set (BSS) corresponds to the basic building block of a wireless LAN. Figure 2 exemplarily illustrates 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). In Figure 2, the ellipse representing the BSS can also be understood as representing the coverage area where the STAs included in the corresponding BSS maintain communication. This area can be referred to as a Basic Service Area (BSA). If a STA moves outside the BSA, it becomes unable to communicate directly with other STAs within that BSA.

[0057] Excluding the DS illustrated in Fig. 2, the most basic type of BSS in a wireless LAN is the Independent BSS (IBSS). For example, an IBSS can have a minimal form consisting of only two STAs. For instance, assuming other components are omitted, a BSS1 composed of only STA1 and STA2, or a BSS2 composed of only STA3 and STA4, can each be considered a representative example of an IBSS. Such a configuration is possible when the STAs can communicate directly without an AP. Furthermore, this type of wireless LAN is not configured through pre-planning but can be configured when a LAN is needed, and this can be referred to as an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity. In other words, in an IBSS, STAs are managed in a distributed manner. In IBSS, all STAs can be mobile STAs, and since connections to distributed systems (DS) are not allowed, they form a self-contained network.

[0058] The membership of an STA in a BSS can be dynamically changed by the STA being turned on or off, or by the STA entering or leaving the BSS area. To become a member of a BSS, an STA can join the BSS using a synchronization process. To access all services of the BSS infrastructure, an STA must be associated with the BSS. This association can be configured dynamically and may include the use of a Distribution System Service (DSS).

[0059] In a wireless LAN, the direct STA-to-STA distance may be limited by PHY performance. In some cases, this distance limit may be sufficient, but in others, communication between STAs over longer distances may be required. To support extended coverage, a distributed system (DS) may be configured.

[0060] DS refers to a structure in which BSSs are interconnected. Specifically, as shown in FIG. 2, a BSS may exist as a component in an extended form of a network composed of multiple BSSs. DS is a logical concept and can be specified by the characteristics of the Distributed System Medium (DSM). In this regard, the Wireless Medium (WM) and the DSM can be logically distinguished. Each logical medium is used for a different purpose and is utilized by different components. These media are not limited to being identical or different. The flexibility of the wireless LAN structure (DS structure or other network structure) can be explained by the fact that multiple media are logically distinct in this way. That is, the wireless LAN structure can be implemented in various ways, and the corresponding wireless LAN structure can be specified independently by the physical characteristics of each implementation.

[0061] DS can support mobile devices by providing seamless integration of multiple BSSs and providing logical services necessary for handling addresses to destinations. Additionally, DS may include a component called a portal that acts as a bridge for connecting the wireless LAN with another network (e.g., IEEE 802.X).

[0062] An AP refers to an entity that enables access to the DS via the WM for combined non-AP STAs and also possesses the functionality of an STA. Data movement between the BSS and the DS can be performed through the AP. For example, STA2 and STA3 shown in FIG. 2 possess the functionality of an STA and provide the ability for combined non-AP STAs (STA1 and STA4) to access the DS. Furthermore, since all APs fundamentally correspond to STAs, all APs are addressable entities. The address used by the AP for communication on the WM and the address used by the AP for communication on the DSM do not necessarily have to be the same. A BSS composed of an AP and one or more STAs can be referred to as an infrastructure BSS.

[0063] Data transmitted from one of the STA(s) coupled to the AP to the STA address of the AP can always be received at an uncontrolled port and processed by an IEEE 802.1X port access entity. Additionally, if the controlled port is authenticated, the transmitted data (or frame) can be forwarded to the DS.

[0064] In addition to the structure of the aforementioned DS, an Extended Service Set (ESS) may be configured to provide wider coverage.

[0065] An ESS refers to a network of arbitrary size and complexity composed of DSs and BSSs. An ESS can correspond to a set of BSSs connected to a single DS. However, an ESS does not contain a DS. An ESS network is characterized by appearing as an IBSS at the Logical Link Control (LLC) layer. STAs included in 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 included in a single ESS can have the same Service Set Identification (SSID). The SSID is distinct from the BSSID, which is the identifier for the BSS.

[0066] In wireless LAN systems, no assumptions are made regarding the relative physical locations of BSSs, and all of the following forms are possible. BSSs may partially overlap, which is a form commonly used to provide continuous coverage. Additionally, BSSs may not be physically connected, and logically, there is no limit to the distance between BSSs. Furthermore, BSSs may be located in the same physical location, which can be used to provide redundancy. Also, one (or more) IBSS or ESS networks may physically exist in the same space as one (or more) ESS networks. This may apply to ESS network forms such as when an ad-hoc network operates at a location where an ESS network exists, when wireless networks that physically overlap are configured by different organizations, or when two or more different access and security policies are required at the same location.

[0067] FIG. 3 is a diagram illustrating a link setup process to which the present disclosure can be applied.

[0068] In order 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 go through authentication procedures for security. The link setup process can also be referred to as the session initiation process or the session setup process. Additionally, the processes of discovery, authentication, association, and security setup in the link setup process can be collectively referred to as the association process.

[0069] In step S310, the STA may perform a network discovery operation. The network discovery operation may include the STA's scanning operation. That is, in order for the STA to access a network, it must find a network it can join. Before joining a wireless network, the STA must identify a compatible network, and the process of identifying networks existing in a specific area is called scanning.

[0070] Scanning methods include active scanning and passive scanning. Figure 3 illustrates a network discovery operation that includes an active scanning process as an example. In active scanning, the STA performing the scanning moves between channels to search for nearby APs, transmits a probe request frame, and waits for a response. The responder transmits a probe response frame as a response to the probe request frame to the STA that transmitted the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame from the BSS of the channel being scanned. In a BSS, the AP becomes the responder because it transmits the beacon frame; however, in an IBSS, the responder is not constant because STAs within the IBSS take turns transmitting the beacon frame. 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 in the same way (i.e., transmit and receive probe request / response on channel 2).

[0071] Although not illustrated in FIG. 3, the scanning operation may be performed using a passive scanning method. In passive scanning, the STA performing the scanning waits for a beacon frame while switching between channels. A beacon frame is one of the management frames defined in IEEE 802.11, which is periodically transmitted to announce the presence of a wireless network and to allow the scanning STA to find the wireless network and join it. In a BSS, the AP performs the role of periodically transmitting beacon frames, and in an IBSS, the STAs within the IBSS take turns transmitting beacon frames. When the scanning STA receives a beacon frame, it stores the information about the BSS included in the beacon frame and records the beacon frame information in each channel while moving to another channel. The STA that receives the beacon frame stores the BSS-related information included in the received beacon frame and moves to the next channel, and can perform scanning in the next channel in the same way. When comparing active scanning and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.

[0072] 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 in step S340 described later.

[0073] The authentication process involves the STA sending an authentication request frame to the AP, and the AP sending an authentication response frame to the STA in response. The authentication frame used in the authentication request / response corresponds to a management frame.

[0074] The authentication frame may include information regarding the authentication algorithm number, authentication transaction sequence number, status code, challenge text, Robust Security Network (RSN), Finite Cyclic Group, etc. These are some examples of information that may be included in the authentication request / response frame, and they may be replaced with other information or additional information may be included.

[0075] The STA can send an authentication request frame to the AP. Based on the information contained in the received authentication request frame, the AP can determine whether to allow authentication for the STA. The AP can provide the result of the authentication process to the STA through an authentication response frame.

[0076] After the STA is successfully authenticated, the association process can be performed in step S330. The association process includes the STA transmitting an association request frame to the AP, and in response, the AP transmitting an association response frame to the STA.

[0077] For example, the association request frame may include information regarding various capabilities, beacon listen interval, service set identifier (SSID), supported rates, supported channels, RSN, mobility domain, supported operating classes, Traffic Indication Map Broadcast request, interworking service capabilities, etc. For example, the association response frame may include information regarding various capabilities, status code, Association ID (AID), supported rates, Enhanced Distributed Channel Access (EDCA) parameter set, Received Channel Power Indicator (RCPI), Received Signal to Noise Indicator (RSNI), mobility domain, timeout interval (e.g., association comeback time), overlapping BSS scan parameters, TIM broadcast response, Quality of Service (QoS) map, etc. This is a partial example of the information that may be included in a combined request / response frame, and it may be replaced with other information or additional information may be included.

[0078] After the STA is successfully joined to the network, a security setup process can be performed in step S340. The security setup process in step S340 may be described as an authentication process through RSNA (Robust Security Network Association) requests / responses, and the authentication process in step S320 may be referred to as the first authentication process, and the security setup process in step S340 may simply be referred to as the authentication process.

[0079] The security setup process of step S340 may include, for example, a private key setup process through a 4-way handshake via an EAPOL (Extensible Authentication Protocol over LAN) frame. Additionally, the security setup process may be performed according to a security method not defined in the IEEE 802.11 standard.

[0080] FIG. 4 is a drawing illustrating a backoff process to which the present disclosure may be applied.

[0081] In wireless LAN systems, the basic access mechanism for MAC (Medium Access Control) is the CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism. The CSMA / CA mechanism is also known as the Distributed Coordination Function (DCF) of IEEE 802.11 MAC, and it basically employs a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or STA may perform Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time interval (e.g., DIFS (DCF Inter-Frame Space)) before starting transmission. If the sensing result determines that the medium is in an idle status, it starts transmitting a frame through that 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 wait by setting a delay period for medium access (e.g., a random backoff period) before attempting to transmit a frame. 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.

[0082] In addition, the IEEE 802.11 MAC protocol provides a Hybrid Coordination Function (HCF). The HCF is based on the aforementioned Point Coordination Function (PCF). The PCF is a polling-based synchronous access method that periodically polls to ensure all receiving APs and / or STAs can receive data frames. Furthermore, the HCF includes Enhanced Distributed Channel Access (EDCA) and Controlled Channel Access (HCCA). EDCA is a contention-based access method for a provider to offer data frames to multiple users, while HCCA uses a non-contention-based channel access method utilizing a polling mechanism. Additionally, the HCF includes a media access mechanism to improve the Quality of Service (QoS) of the wireless LAN and can transmit QoS data during both the Contention Period (CP) and the Contention-Free Period (CFP).

[0083] Referring to FIG. 4, the operation based on the random backoff period is described. When a medium in an occupied / busy state changes to an idle state, multiple STAs may attempt to transmit data (or frames). As a measure to minimize collisions, each STA may select a random backoff count and attempt transmission after waiting for the corresponding slot time. The random backoff count has a pseudo-random integer value and can be determined as one of the values ​​in the range from 0 to CW. Here, CW is the Contention Window parameter value. The CW parameter is given an initial value of CWmin, but in the case of transmission failure (e.g., failure to receive an ACK for a transmitted frame), it may take a value twice that amount. When the CW parameter value becomes CWmax, data transmission may be attempted while maintaining the CWmax value until data transmission is successful; if data transmission is successful, it is reset to the CWmin value. The values ​​of CW, CWmin, and CWmax are 2 n It is desirable to set it to -1 (n=0, 1, 2, ...).

[0084] When the random backoff process begins, the STA continues to monitor the media while counting down the backoff slots according to the determined backoff count value. When the media is monitored as occupied, it stops the countdown and waits, and when the media becomes idle, it resumes the remaining countdown.

[0085] In the example of Fig. 4, when a packet to be transmitted arrives at the MAC of STA3, STA3 confirms that the medium is idle for DIFS and can immediately transmit the frame. The remaining STAs monitor whether the medium is occupied or busy and wait. Meanwhile, data to be transmitted may also arise from each of STA1, STA2, and STA5, and each STA can perform a countdown of the backoff slot according to a random backoff count value selected by each after waiting for DIFS when the medium is monitored to be idle. Assume the case where STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. That is, this exemplifies a case where, at the point when STA2 finishes the backoff count and starts transmitting the frame, the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1. STA1 and STA5 pause the countdown briefly and wait while STA2 occupies the medium. When STA2's possession ends and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume the paused backoff count. That is, they can start transmitting a frame after counting down the remaining backoff slots corresponding to the remaining backoff time. Since STA5's remaining backoff time was shorter than STA1's, STA5 starts transmitting the frame. While STA2 is occupying the medium, data to be transmitted may also be generated by STA4. From STA4's perspective, when the medium becomes idle, it waits for DIFS, performs a countdown based on a random backoff count value selected by itself, and can start transmitting a frame. The example in Figure 4 illustrates a case where STA5's remaining backoff time happens to match STA4's random backoff count value; in this case, a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 receives an ACK, resulting in a failure to transmit data.In this case, STA4 and STA5 can double the CW value, select a random backoff count value, and perform a countdown. STA1 waits while the medium is occupied due to transmission by STA4 and STA5, and when the medium becomes idle, it waits for DIFS, and then can start transmitting frames after the remaining backoff time has passed.

[0086] As shown in the example in Fig. 4, a data frame is a frame used for transmitting data that is forwarded to an upper layer, and can be transmitted after a backoff performed after the elapsed time of DIFS from when the medium becomes idle. Additionally, a management frame is a frame used for exchanging management information that is not forwarded to an upper layer, and is transmitted after a backoff performed after the elapsed time of an IFS such as DIFS or PIFS (Point coordination function IFS). Subtypes of management frames include Beacon, Association request / response, re-association request / response, probe request / response, and authentication request / response. A control frame is a frame used to control access to the medium. Subtype frames of control frames include RTS (Request-To-Send), CTS (Clear-To-Send), ACK (Acknowledgment), PS-Poll (Power Save-Poll), Block ACK (BlockAck), Block ACK Request (BlockACKReq), NDP Announcement (null data packet announcement), and Trigger. If a control frame is not an acknowledgment frame of a previous frame, it is transmitted after a backoff performed after the elapsed DIFS; if it is an acknowledgment frame of a previous frame, it is transmitted after the elapsed SIFS (short IFS) without a backoff. The type and subtype of a frame can be identified by the type field and subtype field within the Frame Control (FC) field.

[0087] A QoS (Quality of Service) STA can transmit a frame after backoff, which is performed after the passage of the arbitration IFS (AIFS) for the access category (AC) to which the frame belongs, i.e., AIFS[i] (where i is a value determined by the AC). Here, the frame for which AIFS[i] can be used can be a data frame or a management frame, and can also be a control frame rather than a response frame.

[0088] FIG. 5 is a diagram illustrating a CSMA / CA-based frame transmission operation to which the present disclosure may be applied.

[0089] As previously mentioned, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, where the STA directly senses the medium. Virtual carrier sensing is intended to mitigate problems that may occur in medium access, such as the hidden node problem. For virtual carrier sensing, the STA's MAC can utilize the Network Allocation Vector (NAV). The NAV is a value that indicates to other STAs the time remaining until the medium becomes available, provided that the STA currently using or authorized to use the medium is using it. Therefore, the value set as the NAV corresponds to the period during which the medium is scheduled to be used by the STA transmitting the frame, and the STA receiving the NAV value is prohibited from accessing the medium during that period. For example, the NAV can be set based on the value of the "duration" field in the frame's MAC header.

[0090] In the example of FIG. 5, it is assumed that STA1 intends to transmit data to STA2, and STA3 is located in a position where it can overhear part or all of the frames transmitted and received between STA1 and STA2.

[0091] In order to reduce the possibility of collisions between multiple STAs in a CSMA / CA-based frame transmission operation, a mechanism utilizing RTS / CTS frames may be applied. In the example of FIG. 5, while STA1 is transmitting, the medium may be determined to be idle based on the carrier sensing result of STA3. That is, STA1 may be a hidden node to STA3. Alternatively, in the example of FIG. 5, while STA2 is transmitting, the medium may be determined to be idle based on the carrier sensing result of STA3. That is, STA2 may be a hidden node to STA3. By exchanging RTS / CTS frames before performing data transmission and reception between STA1 and STA2, it is possible to prevent a STA outside the transmission range of either STA1 or STA2, or a STA outside the carrier sensing range for transmission from STA1 or STA3, from attempting to occupy the channel during data transmission and reception between STA1 and STA2.

[0092] Specifically, STA1 can determine whether the channel is in use through carrier sensing. In terms of physical carrier sensing, STA1 can determine the channel occupancy idle state based on the energy magnitude or signal correlation detected in the channel. Additionally, in terms of virtual carrier sensing, STA1 can determine the channel occupancy state using a NAV (network allocation vector) timer.

[0093] If the channel is idle during DIFS, STA1 can send an RTS frame to STA2 after performing backoff. If STA2 receives the RTS frame, it can send a CTS frame to STA1 as a response to the RTS frame after SIFS.

[0094] If STA3 cannot overhear a CTS frame from STA2 but can overhear an RTS frame from STA1, STA3 can set a NAV timer for the duration of subsequently transmitted frames (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame) using the duration information included in the RTS frame. Alternatively, if STA3 cannot overhear an RTS frame from STA1 but can overhear a CTS frame from STA2, STA3 can set a NAV timer for the duration of subsequently transmitted frames (e.g., SIFS + data frame + SIFS + ACK frame) using the duration information included in the CTS frame. That is, if STA3 can overhear one or more of the RTS or CTS frames from one or more of STA1 or STA2, it can set a NAV accordingly. 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.

[0095] If STA1 receives a CTS frame from STA2, it may transmit a data frame to STA2 after SIFS from the time the reception of the CTS frame is completed. If STA2 successfully receives the data frame, it may transmit an ACK frame to STA1 as an acknowledgment to the data frame after SIFS. STA3 may determine whether the channel is in use through carrier sensing when the NAV timer expires. If STA3 determines that the channel is not in use by another terminal during DIFS from the time the NAV timer expires, it may attempt channel access after a contention window (CW) based on random backoff has passed.

[0096] FIG. 6 is a drawing for illustrating an example of a frame structure used in a wireless LAN system to which the present disclosure may be applied.

[0097] Based on instructions or primitives (meaning a set of instructions or parameters) from the MAC layer, the PHY layer can prepare the MPDU (MAC PDU) to be transmitted. For example, upon receiving an instruction from the MAC layer requesting the start of transmission, the PHY layer switches to transmit mode and can construct the information provided by the MAC layer (e.g., data) into a frame for transmission. Additionally, if the PHY layer detects a valid preamble of a received frame, it monitors the preamble header and sends an instruction to the MAC layer indicating the start of reception.

[0098] As such, information transmission and reception in wireless LAN systems are carried out in the form of frames, and for this purpose, the Physical Layer Protocol Data Unit (PPDU) format is defined.

[0099] A basic PPDU may include a Short Training Field (STF), a Long Training Field (LTF), a Signal (SIGNAL) field, and a Data field. The most basic (e.g., the non-HT (High Throughput)) PPDU format illustrated in FIG. 7 may consist only of Legacy-STF (Legacy-STF), Legacy-LTF (Legacy-LTF), Legacy-SIG (Legacy-SIG) fields and a Data field. In addition, 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 other types of) RL-SIG, U-SIG, non-legacy SIG fields, non-legacy STF, non-legacy LTF, (i.e., xx-SIG, xx-STF, xx-LTF (e.g., xx is HT, VHT, HE, EHT, etc.)) may be included between the L-SIG field and the data field. More specific details will be described later with reference to FIG. 7.

[0100] 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 and frequency error estimation. STF and LTF can be considered signals for synchronization and channel estimation in the OFDM physical layer.

[0101] The SIG field may contain various information related to the transmission and reception of the PPDU. For example, the L-SIG field consists 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 contain information regarding the modulation and coding rates of the data. For example, the 12-bit Length field may contain information regarding 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 non-HT, HT, VHT, or EHT PPDUs, the value of the Length field may be determined as a multiple of 3. For example, for HE PPDUs, the value of the Length field may be determined as a multiple of 3 + 1 or a multiple of 3 + 2.

[0102] The data field may include a SERVICE field, a PSDU (Physical layer Service Data Unit), and PPDU TAIL bits, and may also include padding bits if necessary. Some bits of the SERVICE field may be used for synchronization of the descrambler at the receiver. The PSDU corresponds to a MAC PDU defined at the MAC layer and may contain data generated or used by the upper layer. The PPDU TAIL bits may be used to return the encoder to a 0 state. Padding bits may be used to adjust the length of the data field to a predetermined unit.

[0103] A MAC PDU is defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a Frame Check Sequence (FCS). A MAC frame is composed of a MAC PDU and can be transmitted or received through the PSDU of the data portion in the PPDU format.

[0104] The MAC header includes a Frame Control field, a Duration / ID field, an Address field, etc. The Frame Control field may contain control information necessary for transmitting or receiving frames. The Duration / ID field may be set as the time for transmitting the corresponding frame. Address subfields may indicate the frame's receiver address, transmitter address, destination address, and source address, and some address subfields may be omitted. Specific details regarding each subfield of the MAC header, including Sequence Control, QoS Control, and HT Control subfields, can be found in the IEEE 802.11 standard document.

[0105] The Null-Data PPDU (NDP) format refers to a PPDU format that does not include a data field. In other words, NDP is a frame format that includes the PPDU preamble (i.e., L-STF, L-LTF, L-SIG fields, and additionally, non-legacy SIG, non-legacy STF, and non-legacy LTF if present) from a standard PPDU format, but excludes the remaining parts (i.e., the data field).

[0106] FIG. 7 is a drawing illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure may be applied.

[0107] Various forms of PPDU have been used in standards such as IEEE 802.11a / g / n / ac / ax. The basic PPDU format (IEEE 802.11a / g) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format may also be referred to as the non-HT PPDU format (Fig. 7(a)).

[0108] 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 the HT-mixed format. Additionally, an HT-greenfield format PPDU may be defined, which corresponds to a format consisting of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTFs, and a Data field, without including L-STF, L-LTF, and L-SIG (not shown).

[0109] An example of the VHT PPDU format (IEEE 802.11ac) includes the VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format (Fig. 7(c)).

[0110] An example of the HE PPDU format (IEEE 802.11ax) includes the 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 the 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 multiple users (MU), but is not included in the HE PPDU format for single users (SU). Additionally, the HE trigger-based (TB) PPDU format does not include HE-SIG-B, and the length of the HE-STF field may vary to 8 µs. 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 16 µs. For example, RL-SIG can be configured identically to L-SIG. Based on the presence of RL-SIG, the receiving STA can determine that the received PPDU is a HE PPDU or the EHT PPDU described later.

[0111] The EHT PPDU format may include the EHT MU (multi-user) 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 RL-SIG following L-SIG, but it may include U (universal)-SIG, EHT-SIG, EHT-STF, and EHT-LTF following RL-SIG.

[0112] The EHT MU PPDU of FIG. 7(e) corresponds to a PPDU that carries one or more data (or PSDU) for one or more users. That is, the EHT MU PPDU can be used for both SU transmission and MU transmission. For example, the EHT MU PPDU can correspond to a PPDU for one receiving STA or multiple receiving STAs.

[0113] The EHT-SIG is omitted in the EHT TB PPDU of FIG. 7(f) compared to the EHT MU PPDU. A STA that receives 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.

[0114] The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated so that demodulation and decoding can be attempted even on legacy STAs, and mapped based on a defined 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 so that they can be demodulated and decoded by a STA that has successfully decoded a non-legacy SIG (e.g., U-SIG and / or EHT-SIG) to obtain the information contained in the corresponding fields, and mapped based on a defined subcarrier frequency interval (e.g., 78.125 kHz). These can be referred to as EHT modulated fields.

[0115] Similarly, in the HE PPDU format, the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, and HE-SIG-B fields can be referred to as pre-HE modulation fields, and the HE-STF, HE-LTF, Data, and PE fields can be referred to as HE modulation fields. Also, in the VHT PPDU format, the L-STF, L-LTF, L-SIG, and VHT-SIG-A fields can be referred to as pre-VHT modulation fields, and the VHT STF, VHT-LTF, VHT-SIG-B, and Data fields can be referred to as VHT modulation fields.

[0116] The U-SIG included in the EHT PPDU format of FIG. 7 can be constructed based on, for example, two symbols (e.g., two consecutive OFDM symbols). Each symbol for the U-SIG (e.g., OFDM symbol) can have a duration of 4 µs, and the U-SIG can have a total duration of 8 µs. 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.

[0117] U-SIGs can be configured in 20 MHz units. For example, if an 80 MHz PPDU is configured, the same U-SIG can be duplicated in 20 MHz units. That is, four identical U-SIGs can be included within an 80 MHz PPDU. If the bandwidth exceeds 80 MHz, for example, for a 160 MHz PPDU, the U-SIG of the first 80 MHz unit and the U-SIG of the second 80 MHz unit may be different.

[0118] For example, A number of uncoded bits may be transmitted through U-SIG, and the first symbol of U-SIG (e.g., U-SIG-1 symbol) transmits the first X bits of the total A bit information, and the second symbol of U-SIG (e.g., U-SIG-2 symbol) transmits the remaining Y bits of the total A bit information. The A bit information (e.g., 52 uncoded bits) may include a CRC field (e.g., a field of 4 bits) and a tail field (e.g., a field of 6 bits). The tail field may be used to terminate the trellis of the convolution decoder and may be set to, for example, 0.

[0119] A bit information transmitted by U-SIG can be divided into version-independent bits and version-dependent bits. For example, U-SIG may be included in a new PPDU format not shown in FIG. 7 (e.g., UHR PPDU format), and in the format of the U-SIG field included in the EHT PPDU format and the format of the U-SIG field included in the UHR PPDU format, the version-independent bits may be the same, and some or all of the version-dependent bits may be different.

[0120] For example, the size of the version-independent bits of U-SIG may be fixed or variable. The version-independent bits may be assigned only to U-SIG-1 symbols or to both U-SIG-1 and U-SIG-2 symbols. The version-independent bits and version-dependent bits may be referred to by various names, such as the first control bit and the second control bit.

[0121] For example, the version-independent bits of U-SIG may include a 3-bit physical layer version identifier (PHY version identifier), and this information may indicate the PHY version of the transmitted / received PPDU (e.g., EHT, UHR, etc.). The version-independent bits of U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication. The version-independent bits of U-SIG may include information regarding the length of the TXOP (transmission opportunity) and information regarding the BSS color ID.

[0122] For example, the version-dependent bits of U-SIG may contain information that directly or indirectly indicates the type of PPDU (e.g., SU PPDU, MU PPDU, TB PPDU, etc.).

[0123] Information necessary for PPDU transmission and reception may be included in the U-SIG. For example, the U-SIG may further include information regarding bandwidth, information regarding MCS techniques applied to non-legacy SIGs (e.g., EHT-SIG or UHR-SIG, etc.), information indicating whether DCM (dual carrier modulation) techniques (e.g., techniques to achieve an effect similar to frequency diversity by reusing the same signal on two subcarriers) are applied to non-legacy SIGs, information regarding the number of symbols used for non-legacy SIGs, and information regarding whether non-legacy SIGs are generated across the entire band.

[0124] Some of the information required for PPDU transmission and reception may be included in U-SIG and / or non-legacy SIGs (e.g., EHT-SIG or UHR-SIG, etc.). For example, information regarding the type of non-legacy LTF / STF (e.g., EHT-LTF / EHT-STF or UHR-LTF / UHR-STF, etc.), information regarding the length of non-legacy LTF and cyclic prefix (CP) length, information regarding guard interval (GI) applied to non-legacy LTF, information regarding preamble puncturing applicable to PPDU, information regarding resource unit (RU) allocation, etc., may be included only in U-SIG, may be included only in non-legacy SIG, or may be indicated by a combination of information included in U-SIG and information included in non-legacy SIG.

[0125] Preamble puncturing may refer to the transmission of a PPDU in which a signal is not present in one or more frequency units within the PPDU bandwidth. For example, the size of the frequency unit (or the resolution of preamble puncturing) may be defined as 20 MHz, 40 MHz, etc. For example, preamble puncturing may be applied to a PPDU bandwidth of a predetermined size or larger.

[0126] In the example of FIG. 7, non-legacy SIGs such as HE-SIG-B and EHT-SIG may include control information for the receiving STA. A non-legacy SIG may be transmitted through at least one symbol, and one symbol may have a length of 4 µs. Information regarding the number of symbols used for EHT-SIG may be included in the previous SIG (e.g., HE-SIG-A, U-SIG, etc.).

[0127] Non-legacy SIGs, such as HE-SIG-B and EHT-SIG, may include common fields and user-specific fields. Common fields and user-specific fields may be coded individually.

[0128] In some cases, the common field may be omitted. For example, in a compression mode where non-OFDMA (orthogonal frequency multiple access) is applied, the common field may be omitted, and multiple STAs may receive PPDUs (e.g., the data field of the PPDU) over the same frequency band. In a non-compression mode where OFDMA is applied, multiple users may receive PPDUs (e.g., the data field of the PPDU) over different frequency bands.

[0129] 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 may be related to MU-MIMO allocation or non-MU-MIMO allocation.

[0130] The common field may include CRC bits and Tail bits, the length of the CRC bits may be determined to be 4 bits, and the length of the Tail bits may be determined to be 6 bits and set to 000000. The common field may include RU allocation information. The RU allocation information may include information regarding the location of the RU to which a plurality of users (i.e., a plurality of receiving STAs) are allocated.

[0131] An RU may include multiple subcarriers (or tones). An RU may be used when transmitting signals to multiple STAs based on the OFDMA technique. Additionally, an RU may be defined when transmitting signals to a single STA. Resources may be allocated on an RU basis for non-legacy STF, non-legacy LTF, and Data fields.

[0132] Applicable RU sizes can be defined according to the PPDU bandwidth. RUs 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 80 MHz PPDU, the RU placement for HE PPDU and EHT PPDU may differ. The applicable RU sizes, number of RUs, RU locations, DC (direct current) subcarrier locations and numbers, null subcarrier locations and numbers, and guard subcarrier locations and numbers for each PPDU bandwidth can be referred to as a tone-plan. For example, a tone-plan for a wide bandwidth may be defined as a multiple repetition of a tone-plan for a low bandwidth.

[0133] RUs of various sizes can be defined as 26-ton RUs, 52-ton RUs, 106-ton RUs, 242-ton RUs, 484-ton RUs, 996-ton RUs, 2x996-ton RUs, 4x996-ton RUs, etc. An MRU (multiple RU) is distinguished from multiple individual RUs and corresponds to a group of subcarriers composed 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. In addition, multiple RUs constituting a single MRU may be continuous or non-continuous in the frequency domain.

[0134] The specific size of the RU may be reduced or expanded. Accordingly, the specific size of each RU (i.e., the number of corresponding tones) in this disclosure is not limited and is exemplary. Additionally, within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, ...) in this disclosure, the number of RUs may vary depending on the RU size.

[0135] The names of the respective fields in the PPDU formats of FIG. 7 are exemplary and the scope of the present disclosure is not limited by such names. Furthermore, the examples of the present disclosure may be applied not only to the PPDU formats exemplified in FIG. 7, but also to new PPDU formats based on the PPDU formats of FIG. 7 in which some fields are excluded and / or some fields are added.

[0136] Target Wake Time (TWT)

[0137] The following explains TWT (target wake time).

[0138] TWT is a Power Saving (PS) technology that can improve the energy efficiency of non-AP STAs by defining the Service Period (SP) between APs and non-AP STAs and sharing information about SPs to reduce contention. In the TWT Setup phase, an STA that performs requests, suggestions, or demands can be referred to as a Requesting STA. Additionally, an AP that responds to such requests by accepting or rejecting them can be referred to as a Responding STA. The Setup phase may include the process of determining or defining the STA's TWT request to the AP, the type of TWT operation to be performed, and the frame types to be transmitted and received. TWT operations can be classified into Individual TWT and Broadcast TWT.

[0139] FIG. 8 is a drawing illustrating an example of an individual TWT operation to which the present disclosure may be applied.

[0140] Individual TWT is a mechanism for AP and non-AP STA to perform data exchange after negotiating the awake / doze status of the non-AP STA through the transmission and reception of TWT request / response frames. In the example of Fig. 8, AP and STA1 can form a trigger-enabled TWT agreement through TWT request frames and TWT response frames. Here, the method used by STA1 is a solicited TWT method, in which STA1 transmits a TWT request frame to AP, and STA1 receives information for TWT operation from AP through a TWT response frame. On the other hand, STA2, which performs the unsolicited TWT method, can receive information regarding the setup of the trigger-enabled TWT agreement from the AP via an unsolicited TWT response. Specifically, STA2 can calculate the next TWT by adding a specific number to the current TWT value. During the trigger-enabled TWT SP, the AP can transmit a trigger frame to the STAs. The trigger frame can inform the STAs that there is buffered data in the AP. In this regard, STA1 can notify the AP of its awake state by transmitting a PS-Poll frame. Additionally, STA2 can notify the AP of its awake state by transmitting a QoS Null frame. Here, the data frames transmitted by STA1 and STA2 may be frames in the TB PPDU format. The AP that checks the status of STA1 and STA2 can send DL MU PPDU to the active STAs.When the TWT SP expires, STA1 and STA2 can transition to a doze state.

[0141] FIG. 9 is a drawing illustrating an example of a broadcast TWT operation to which the present disclosure may be applied.

[0142] Broadcast TWT is a type of TWT in which a non-AP STA (or TWT scheduling STA) obtains information regarding the target beacon transmission time (TBTT) and listen interval, etc., by transmitting and receiving TWT request / response frames with an AP (or TWT scheduled STA). Here, negotiation operations regarding the TBTT may also be performed. Based on this, the AP can define a frame containing the TWT scheduling information through a beacon frame. In FIG. 9, STA1 performs a request-type TWT operation, and STA2 performs an un-request-type TWT operation. The AP can transmit a DL MU PPDU after checking the awake status of the STAs through the trigger it transmitted. This may be identical to the process of an individual TWT. In a broadcast TWT, a trigger-enabled TWT SP containing a beacon frame can be repeated multiple times at a regular interval.

[0143] The transmission of TWT information can be achieved through TWT information frames and TWT information elements.

[0144] A TWT information frame is transmitted by an STA to request or transmit information about a TWT consensus, and is transmitted by one of the STAs of the existing TWT consensus. The action frame of the TWT information frame includes a TWT information field. The TWT Information field may include a 3-bit TWT flow identifier subfield, a 1-bit response requested subfield, a 1-bit next TWT request subfield, a 2-bit next TWT subfield size subfield, a 1-bit all TWT subfield, and a 0 / 32 / 48 / 64-bit next TWT subfield.

[0145] Figure 10 is a diagram illustrating an example of a TWT information element format.

[0146] TWT information elements may be transmitted or received by being included in beacons, probe responses, (re)combined response frames, etc. TWT information elements may include an element ID field, a length field, a control field, and a TWT parameter information field.

[0147] The control field of a TWT information element has the same format regardless of whether it is an individual TWT or a broadcast TWT.

[0148] The NDP paging indicator subfield can have a value of 1 if the NDP paging field exists, and a value of 0 if the NDP paging field does not exist.

[0149] The responder PM mode subfield can represent Power Management (PM) mode.

[0150] The negotiation type subfield may indicate whether the information contained in the TWT element is for negotiation of parameters of a broadcast TWT or individual TWT(s), or for a wake TBTT interval.

[0151] For example, if the value of the negotiation type subfield is 0, the TWT subfield is for a future individual TWT SP start time, and the TWT element contains a set of individual TWT parameters. This may correspond to an individual TWT negotiation between a TWT requesting STA and a TWT response STA, or to an individual TWT announcement by a TWT responder.

[0152] For example, if the value of the consultation type subfield is 1, the TWT subfield is for the next TBTT time, and the TWT element contains a single set of TWT parameters. This may correspond to the wake TBTT and wake interval consultation between the TWT-scheduled STA and the TWT-scheduling AP.

[0153] For example, if the value of the consultation type subfield is 2, the TWT subfield is for a future broadcast TWT SP start time, and the TWT element contains one or more sets of broadcast TWT parameters. This may correspond to providing a broadcast TWT schedule to a TWT-scheduled STA by including the TWT element in a broadcast management frame transmitted by the TWT scheduling AP.

[0154] For example, if the value of the consultation type subfield is 3, the TWT subfield is for a future broadcast TWT SP start time, and the TWT element contains one or more sets of broadcast TWT parameters. This may correspond to managing membership in a broadcast TWT schedule by including the TWT element in an individually addressed management frame transmitted by either the TWT-scheduled STA or the TWT-scheduled AP.

[0155] If the TWT information frame disabled subfield is set to 1, it indicates that reception of TWT information frames by the STA is disabled, otherwise it can be set to 0.

[0156] The wake duration unit subfield indicates the unit of the nominal minimum TWT wake duration field. The wake duration unit subfield can be set to 0 when the unit is 256us, and to 1 when the unit is TU. If it is not HE / EHT STA, the wake duration unit subfield can be set to 0.

[0157] The MSB (most significant bit) of the consultation type field may correspond to the broadcast field. If the broadcast field is 1, the TWT element may contain one or more sets of broadcast TWT parameters. If the broadcast field is 0, only one set of individual TWT parameters may be contained in the TWT element. A TWT element in which the broadcast field is set to 1 may be referred to as a broadcast TWT element.

[0158] Figure 11 is a diagram illustrating examples of individual TWT parameter set field formats.

[0159] Figure 12 is a diagram illustrating examples of broadcast TWT parameter set field formats.

[0160] The TWT parameter information field included in the TWT element of Fig. 10 may have different configurations depending on the individual TWT or broadcast TWT.

[0161] In the case of an individual TWT, the TWT parameter information field within the TWT element contains a single individual TWT parameter set field.

[0162] In the case of a broadcast TWT, the TWT parameter information field within the TWT element includes one or more broadcast TWT parameter set fields. Each broadcast TWT parameter set may include specific information for a single broadcast TWT.

[0163] As illustrated in FIGS. 11 and 12, the individual TWT parameter set field and the broadcast TWT parameter set field include common subfields.

[0164] The request type subfield has the same size as the individual TWT parameter set field and the broadcast TWT parameter set field, but its detailed configuration may differ. This will be discussed later.

[0165] The target wake time subfield indicates the start time of an upcoming individual / broadcast TWT SP.

[0166] The nominal maximum TWT wake duration subfield represents the minimum unit that a TWT requesting STA expects to be woken up to complete frame exchanges associated with the TWT flow identifier during the TWT wake interval duration. Here, the TWT wake interval may refer to the average time between consecutive TWT SPs expected by the TWT requesting STA.

[0167] The TWT Wake Interval Mantissa subfield can be expressed in microseconds as the binary value of the TWT Wake Interval.

[0168] Referring to Fig. 11, the TWT group assignment subfield, TWT channel, and NDP paging subfield are included only in the individual TWT parameter set fields.

[0169] The TWT group assignment subfield contains information about the TWT group to which the STA is assigned and provides it to the TWT requesting STA. This information can be used to calculate the TWT value within the TWT group. The STA's TWT value may be equal to the zero offset value and the TWT offset value multiplied by the TWT unit value.

[0170] The TWT channel subfield represents a bitmap indicating an allowed channel. When transmitted by a TWT request STA, the TWT channel subfield may contain a bitmap indicating a channel that the STA requests to use as a temporary default channel during the TWT SP. When transmitted by a TWT response STA, the TWT channel subfield may contain a bitmap indicating a channel that the TWT request allows.

[0171] The NDP paging subfield is optional and may include information such as the identifier of the STA being paged and the maximum number of TWT wake intervals between NDP paging frames.

[0172] Referring to FIG. 12, the broadcast TWT info subfield is included only in the broadcast TWT parameter set field. The broadcast TWT info subfield may include a 3-bit reserve bit, a 5-bit broadcast TWT identifier (ID) subfield, and an 8-bit broadcast TWT persistence subfield. The broadcast TWT identifier subfield indicates the broadcast ID of a specific broadcast TWT that the STA requests to join or provides TWT parameters for, depending on the value of the TWT setup command subfield of the TWT element. The broadcast TWT persistence subfield indicates the number of TBTTs planned on the broadcast TWT schedule.

[0173] Next, the detailed configuration of the request type subfield is explained.

[0174] First, referring to Fig. 11, the format of the request type subfield of the individual TWT parameter set field will be explained.

[0175] The TWT request subfield can indicate whether it is a request STA or a response STA. If the value is 1, it indicates that it is a TWT request STA or a scheduled STA, and if it is 0, it indicates that it is a TWT response STA or a scheduling AP.

[0176] The TWT setup command subfield can represent commands such as Request, Suggest, Demand, Accept, Alternate, Dictate, and Reject.

[0177] The trigger subfield indicates whether to use trigger frames in the TWT SP. If the value is 1, the trigger is used, and if it is 0, the trigger may not be used.

[0178] The implicit subfield can indicate whether it is an implicit TWT or an explicit TWT. If the value is 1, it indicates an implicit TWT, and if it is 0, it indicates an explicit TWT.

[0179] The flow type subfield may indicate the type of interaction between the TWT requesting STA (or the STA being scheduled for TWT) and the TWT responding STA (or the AP scheduling for TWT). If the value is 1, it may indicate an announced TWT, where the STA sends a wake-up signal to the AP by transmitting a PS-Poll or APSD (automatic power save delivery) trigger frame before a non-trigger frame is transmitted from the AP to the STA. If the value is 0, it may indicate an unannounced TWT.

[0180] The TWT flow identifier subfield may include a 3-bit value that uniquely identifies specific information about the TWT request in other requests made between the same TWT request STA and TWT response STA pair.

[0181] The TWT wake interval exponent subfield allows setting the TWT wake interval value in binary microseconds. For individual TWTs, it may refer to the interval between individual TWT SPs. The TWT wake interval of a request STA can be defined as [TWT Wake Interval Mantissa * 2 * TWT Wake Interval Exponent].

[0182] The TWT protection subfield may indicate whether a TWT protection mechanism is used. If the value is 1, the TXOP within the TWT SP may be initiated by a NAV protection mechanism such as (MU)RTS / CTS or CTS-to-self frames, and if it is 0, the NAV protection mechanism may not be applied.

[0183] Referring to Fig. 12, some of the sub-fields of the request type sub-field of the broadcast TWT parameter set field are common to the sub-fields of the request type sub-field of the individual TWT parameter set field, so a description thereof is omitted. The sub-fields included only in the broadcast TWT parameter set are described below.

[0184] The Last Broadcast Parameter Set subfield indicates whether it is the last broadcast TWT parameter set. If the value is 1, it indicates that it is the last broadcast TWT parameter set, and if it is 0, it indicates that the next broadcast TWT parameter set exists.

[0185] The broadcast TWT recommendation subfield can represent recommendations for frame types transmitted by the AP during the broadcast TWT SP with values ​​from 1 to 7.

[0186] The last bit of the request type subfield of the broadcast TWT parameter set field can be reserved.

[0187] With the recent surge in wired and wireless traffic, latency-sensitive traffic has also increased significantly. Latency-sensitive traffic includes real-time audio and video transmission, and the need to support this in wireless environments has grown with the proliferation of multimedia devices. However, compared to wired environments, there are many factors to consider when supporting latency-sensitive traffic in wireless environments. This is because wireless environments have lower transmission speeds than wired environments, and issues regarding interference from the surroundings must also be taken into account. In particular, in wireless LAN systems, since multiple STAs must compete equally for media occupancy in the ISM (Industry-Science-Medical) band, it is relatively more difficult to support latency-sensitive traffic compared to cellular communication networks based on wireless resource scheduling by a central base station. This disclosure describes a new method for supporting latency-sensitive traffic in wireless LAN systems.

[0188] In the present disclosure, latency may refer to latency as defined in IEEE 802.11 series standards. For example, it may refer to the time from when a frame to be transmitted enters the queue of the MAC layer of a transmitting STA, until the transmission by the transmitting STA is successfully completed at the PHY layer, and until the transmitting STA receives an ACK / block ACK, etc. from a receiving STA and the corresponding frame is deleted from the queue of the transmitting STA's MAC layer. Additionally, in the present disclosure, a non-AP STA that supports the transmission of latency-sensitive data may be referred to as a Low Latency STA. Furthermore, data other than latency-sensitive data may be referred to as regular data.

[0189] Restricted TWT (r-TWT) can support the AP in securing priority data transmission possibilities for low-latency STAs over other STAs by establishing a special broadcast TWT for low-latency STAs transmitting latency-sensitive data. An STA can establish membership for one or more r-TWT schedules with respect to the AP. Here, r-TWT consensus can be established through the same process as broadcast TWT consensus, and for this purpose, broadcast TWT elements can be defined to include an r-TWT parameter set field. For example, the r-TWT parameter set may refer to a specific broadcast TWT parameter set field that is distinct from other broadcast TWT parameter set fields. That is, the r-TWT parameter set field may correspond to a special case of the broadcast TWT parameter set field. Additionally, the AP can announce the r-TWT SP.

[0190] Basically, if another STA that supports r-TWT operation is a TXOP holder, the TXOP must be ended before the start time of the r-TWT SP advertised by the combined AP. Accordingly, the STA associated with the r-TWT (i.e., the low-latency STA) can perform traffic transmission and reception preferentially over the other STA within the r-TWT SP.

[0191] In the present disclosure, as described above, a low-latency STA associated with a specific r-TWT is referred to as a member r-TWT scheduled STA, and other STAs are referred to as non-member STAs. A non-member STA may be a STA that has the capability to support r-TWT operation but is not a member of any r-TWT, a STA that supports r-TWT operation and is a member of another r-TWT, or a STA that does not have the capability to support r-TWT operation.

[0192] A STA that supports the limited SP (or r-TWT SP) operation of a broadcast TWT (e.g., a low-latency STA) may notify the AP that it needs to transmit latency-sensitive data based on the r-TWT operation. If the AP supports the r-TWT operation / mode, the AP may transmit a frame containing scheduling information for the TWTs requested by each STA to the low-latency STA and other STA(s). For example, to perform an operation for an r-TWT, non-AP STAs may obtain r-TWT related information from the AP via a beacon frame, a probe response frame, a (re)join response frame, or other frames in an as-yet-undefined format (e.g., a broadcast, advertisement, or announcement frame).

[0193] According to restricted TWT operations, a separate TXOP (i.e., access by other STAs is restricted) can be secured within an r-TWT SP using a NAV such as (MU) RTS / CTS or CTS-to-self, or a quiet interval. Before a specific r-TWT SP starts, if there is a TXOP of a STA other than the STA that has membership in the specific r-TWT schedule (i.e., a non-member STA), it must be stopped. The TXOP of the other STA (i.e., a non-member STA) may be additionally executed after the specific r-TWT SP ends.

[0194] Device-In-Device Coexistence (IDC) Operation

[0195] Wi-Fi wireless communication technology can be used in conjunction with non-Wi-Fi wireless communication technology in similar frequency bands (e.g., 2.4 GHz, 5 GHz, 6 GHz, etc.). For example, non-Wi-Fi wireless communication technology may include various wireless communication technologies such as Bluetooth, Zigbee, and UWB (ultra wide band). A single device (e.g., a smartphone, smartwatch, AR / VR device, etc.) may support non-Wi-Fi wireless communication technology along with Wi-Fi wireless communication technology. When transmission and reception according to different wireless communication technologies coexist simultaneously on the same or adjacent frequency bands, problems such as reduced transmission throughput and increased latency may occur due to mutual interference, packet loss, and rate degradation.

[0196] In addition, even when smart devices such as smartphones support mobile AP or soft AP functions, an IDC problem may occur where Wi-Fi transmission and reception and non-Wi-Fi transmission and reception coexist simultaneously. In this case, unnecessary actions (e.g., attempts to exchange data over a Wi-Fi channel and failure) may occur repeatedly and frequently on other smart devices connected to the AP, and consequently, power consumption issues may arise.

[0197] FIG. 13 is a drawing illustrating an example of a collision caused by an IDC to which the present disclosure may be applied.

[0198] The example in Fig. 13 illustrates how media access by STAs is affected when IDC events occur periodically at the AP. For instance, the AP may periodically perform data exchange with a non-Wi-Fi device. While the AP is performing non-Wi-Fi transmission (or reception), an Initial Control Frame (ICF), such as an RTS, which STA1 and / or STA2 within the BSS transmit first to send data, may collide with a non-Wi-Fi transmission sent by the AP or the non-Wi-Fi device. Consequently, a situation may arise where the AP fails to hear the RTS frame from STA1 / STA2. In this case, the STAs within the BSS may continuously attempt to transmit RTS due to data transmission failures. Consequently, STA1 / STA2 may continuously consume power in the active state without successfully performing Wi-Fi data exchange.

[0199] To solve these problems, a method of scheduling unavailable time (e.g., time when STA 1 / 2 cannot send or receive data) through broadcast TWT operation may be applied.

[0200] FIG. 14 illustrates an IDC event notification signaling procedure using an IDC broadcast TWT to which the present disclosure may be applied.

[0201] As an example of the present disclosure, as illustrated in FIG. 14, an AP may transmit a beacon frame containing a broadcast TWT element to STA 1 / 2. That is, the AP may announce a period of non-availability caused by an IDC to a non-AP STA (e.g., STA 1 / 2) through the broadcast TWT element. The non-AP STA may identify the period of non-availability caused by an IDC through the broadcast TWT element and may not perform or attempt to perform data transmission and reception operations with the AP within the identified period of non-availability. FIG. 14 illustrates a case where the AP announces a period of non-availability caused by an IDC to a non-AP STA, but is not limited thereto. The operation of FIG. 14 may be replaced by an operation where the AP announces a period of non-availability to another AP, an operation where the non-AP STA announces a period of non-availability to the AP, or an operation where the non-AP STA announces a period of non-availability to another non-AP STA.

[0202] As an example of the present disclosure, for power saving, a Wi-Fi device can schedule awake and doze periods by announcing a broadcast TWT to other Wi-Fi devices.

[0203] FIG. 15 is a diagram illustrating a method for scheduling awake and water sections to which the present disclosure can be applied.

[0204] As an example of the present disclosure, as illustrated in FIG. 15, an AP can schedule awake and sleep periods by transmitting a beacon frame containing a broadcast TWT element to non-AP STA(s). The operation of FIG. 15 illustrates the case where the AP notifies a non-AP STA of an unavailable period due to an IDC, but is not limited thereto. Similar to the operation of FIG. 14, the operation illustrated in FIG. 15 can be replaced not only with the operation between the AP and the non-AP STA but also with other STAs (e.g., the operation between non-AP STAs, the operation of a non-AP STA transmitting a beacon frame to the AP, the operation between APs, etc.).

[0205] As an example of the present disclosure, a service period (TWT SP) scheduled based on a broadcast TWT element may be scheduled as an awake period, and time outside the TWT SP may be scheduled as a sleep period or / and an unavailable period due to IDC. For example, as the value of the broadcast TWT ID (identifier or identity) subfield of the (broadcast) TWT element is set to 0 and the value of the responder PM (power management) mode subfield is set to 1, the TWT SP (or / and awake period) and the sleep period (or / and unavailable period) may be scheduled as described above.

[0206] Here, depending on the setting of the NDP paging indicator / unavailable mode subfield value within the (broadcast) TWT element, it can be determined whether a STA (e.g., a non-AP STA or / and AP) can perform transmit / receive operations at a time outside the broadcast TWT SP.

[0207] For example, if the NDP paging indicator / unavailable mode subfield value is set to 0, the STA may be unavailable outside of that broadcast TWT SP, except for other TWT SPs that are set as APs or advertised by APs. If the NDP paging indicator / unavailable mode subfield value is set to 1, the STA may be unavailable outside of these broadcast TWT SPs, even if it corresponds to a time set on another TWT SP or a time advertised by an AP.

[0208] Additionally or alternatively, rules for the outer intervals of one or more broadcast TWT SPs may be determined differently depending on the value of the NDP paging indicator / unavailable mode subfield within the (broadcast) TWT element. Meanwhile, if there are broadcast TWT schedules for scheduled power saving (PS) (e.g., broadcast TWT SPs for SPs) and one or more periodic IDC SPs (e.g., periodic IDC schedules due to IDC with BT and / or UWB), the time intervals outside each schedule (or / and SP) may not be set as unavailable intervals or sleep intervals.

[0209] FIG. 16 is a diagram illustrating the operation when the schedule for a scheduled PS overlaps with another periodic IDC SP.

[0210] As an example of the present disclosure, as illustrated in FIG. 16, PUO scheduling intervals resulting from the SP and BT / UWB IDCs for the scheduled AP PS may be individually set. In this case, if the sleep interval (or / and unavailable interval) of a specific schedule overlaps with the awake interval of other schedule(s), operation according to the sleep interval (or / and unavailable interval) of the specific schedule may not be guaranteed.

[0211] For example, time intervals other than the SP for scheduled AP PS (e.g., sleep intervals) and PUO scheduling intervals caused by the respective BT / UWB IDCs may overlap, which may result in the operation of the sleep interval for scheduled AP PS not being guaranteed. Consequently, power consumption may increase, and attempts to exchange data frames may occur during unnecessary unavailable intervals.

[0212] Additionally, while it may be necessary to update schedules for scheduled PS or PUO, it may be difficult to perform schedule-specific updates for scheduled PS or PUO because there is no unique identifier for each schedule.

[0213] Specifically, when the value of the broadcast TWT ID subfield is set to 0, one or more broadcast TWT parameter set fields may be included on the broadcast TWT element. In this case, an update procedure for one or more broadcast TWT parameter set fields is required to update the schedule for a scheduled PS or PUO, but it may be difficult to perform the update procedure because there is no unique identifier for each schedule.

[0214] The following describes how to maintain an unavailable state outside of a broadcast TWT SP without being affected by other broadcast TWT schedules, and how to update the NDP paging indicator / unavailable mode subfield according to the broadcast TWT schedule situation.

[0215] FIG. 17 is a flowchart for explaining the operation of a first STA according to one embodiment of the present disclosure. FIG. 17 and FIG. 18 describe the case where the first STA is a non-AP STA and the second STA is an AP, but are not limited thereto.

[0216] The first STA can receive a first TWT element from the second STA that includes at least one broadcast TWT parameter set field (S1710).

[0217] For example, the control field of the first TWT element may include a first NDP paging indicator / unavailable mode subfield and a responder PM mode subfield. Additionally, the first TWT element may include at least one broadcast TWT parameter set field. The first TWT element may be transmitted to the first STA via a beacon frame, a probe response frame, or / and a (re)combined response frame.

[0218] Here, at least one broadcast TWT parameter set field may include broadcast TWT parameter set field(s) for power save (PS) and broadcast TWT parameter set field(s) for periodic unavailability operation (PUO).

[0219] For example, a broadcast TWT parameter set field for PS may include a PUO ID subfield set to a first value, and a broadcast TWT parameter set field for PUO may include a PUO ID subfield set to a second value. That is, a PUO ID subfield with a specific value set for each broadcast TWT parameter set may be included.

[0220] In the following, it is assumed that the responder PM mode subfield value included in the control field of the first TWT element is set to 1, and the broadcast TWT ID subfield value of at least one broadcast TWT parameter set field is set to 0.

[0221] For example, based on the fact that the outside time of at least one broadcast TWT SP associated with at least one broadcast TWT parameter set field does not belong within another TWT SP, the value of the first null data physical layer protocol data unit (NDP) paging indicator / unavailability mode subfield included in the first TWT element may be set to 0.

[0222] However, this is merely one embodiment, and if the external time of at least one broadcast TWT SP associated with at least one broadcast TWT parameter set field does not fall within another TWT SP(s), the first NDP paging indicator / unavailable mode subfield value may be allowed to be set to 0 or 1. In this case, the other TWT SP(s) may be TWT SP(s) advertised or set up by the second STA (e.g., AP). Additionally or alternatively, the other TWT SP(s) may be separate broadcast TWT SP(s) for power saving or PUO.

[0223] And, the time outside of at least one broadcast TWT SP may be unavailable regardless of other SP(s). That is, the first STA and / or the second STA may be unavailable during the time outside of at least one broadcast TWT SP.

[0224] Additionally or alternatively, the first STA may receive capability information related to the PUO (or IDC) (e.g., information regarding whether it supports PUO-related operations) from the second STA before, after, or simultaneously with step S1710. Additionally, the first STA may transmit capability information related to the PUO (or IDC) to the second STA before, after, or simultaneously with step S1710.

[0225] Based on the fact that the external time of at least one TWT SP belongs within a specific TWT SP, the first STA can receive a first frame containing a second TWT element from the second STA (S1720).

[0226] As described above, it is assumed that the external time of at least one broadcast TWT SP associated with at least one broadcast TWT parameter set field did not belong within another TWT SP, but subsequently the external time of said at least one broadcast TWT SP belongs to a specific TWT SP (e.g., a newly advertised / set-up TWT SP, etc.). In this case, the first STA can receive information related to the update of the NDP paging indicator / unavailable mode subfield (e.g., the first / second indicator / unavailable mode subfield, etc.) from the second STA.

[0227] Here, specific TWT SP(s) may be advertised or set up by a second STA. Additionally, specific TWT SP(s) may be separate broadcast TWT SPs for power saving or PUO.

[0228] For example, information related to the update of an NDP paging indicator / unavailable mode subfield may include at least one of information indicating that the value of the second NDP paging indicator / unavailable mode subfield (e.g., the NDP paging indicator / unavailable mode subfield included in the second TWT element) is set / changed to 1, or the time when the value of the second NDP paging indicator / unavailable mode subfield is set / changed to 1.

[0229] And, information regarding the update of the NDP paging indicator / unavailable mode subfield may be based on i) the broadcast TWT persistence subfield included in the TWT element of the first frame, ii) the basic service set (BSS) parameter change count subfield included in the first frame, or iii) the critical update flag subfield included in the capability information of the first frame.

[0230] For example, the update time of the NDP paging indicator / unavailable mode subfield (e.g., the time when the value of the second NDP paging indicator / unavailable mode subfield changes to 1) may be indicated through i) the broadcast TWT persistence subfield included in the second TWT element of the first frame and / or ii) the basic service set (BSS) parameter change count subfield included in the first frame.

[0231] For example, the first frame may include at least one of a beacon frame, a probe response frame, or a (re)combination response frame. However, this is merely one embodiment, and the first frame may be any form of an advertisement (and / or broadcasting) frame or a unicast frame (e.g., an action frame). If the first frame is a beacon frame, the first frame may be transmitted to the first STA according to the delivered traffic indication map (DTIM) beacon cycle.

[0232] For example, the NDP paging indicator / unavailable mode subfield value of the first frame or / and the third frame transmitted after the first frame may be set to 1. The first STA may determine that the external time of at least one broadcast TWT SP is unavailable regardless of the specific TWT SP, based on the NDP paging indicator / unavailable mode subfield value (e.g., 1) received through the first frame and / or the second frame.

[0233] As described above, information related to the update of the NDP paging / indicator unavailable mode subfield may be transmitted through the first frame containing the second TWT element, but is not limited thereto. Information related to the update of the NDP paging / indicator unavailable mode subfield may also be transmitted and received through a separate frame (e.g., the second frame) other than the first frame.

[0234] In another example of the present disclosure, the value of the first NDP paging indicator / unavailable mode subfield included in the first TWT element may be set to 1 based on the fact that the external time of at least one broadcast TWT SP associated with at least one broadcast TWT parameter set field in step S1710 and / or step S1720 belongs within another TWT SP. That is, when the value of the responder PM mode subfield included in the control field of the first TWT element is set to 1 and the value of the broadcast TWT ID subfield of at least one broadcast TWT parameter set field is set to 0, the value of the first NDP paging indicator / unavailable mode subfield included in the first TWT element may be set to 1 if the external time of at least one broadcast TWT SP associated with at least one broadcast TWT parameter set field belongs within another TWT SP.

[0235] Subsequently, if the external time of at least one broadcast TWT SP associated with at least one broadcast TWT parameter set field belongs within another TWT SP, but subsequently the external time of said at least one broadcast TWT SP does not belong to a specific TWT SP, the first STA may receive information from the second STA through a separate frame regarding the NDP paging indicator / unavailable mode subfield value set to 0 and / or the update of said NDP paging indicator / unavailable mode subfield.

[0236] The method described in the example of FIG. 17 can 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 TWT element containing at least one broadcast TWT parameter set field from a second STA through one or more transceivers (106). Based on the fact that the external time of at least one TWT SP falls within a specific TWT SP, one or more processors (102) may receive a first frame containing a second TWT element from the second STA through one or more transceivers (106).

[0237] Furthermore, one or more memories (104) of the first device (100) may store instructions for performing the method described in the example of FIG. 17 or the examples described below when executed by one or more processors (102).

[0238] FIG. 18 is a flowchart for explaining the operation of a second STA according to one embodiment of the present disclosure.

[0239] The second STA can transmit a first TWT element containing at least one broadcast TWT parameter set field to the first STA (S1810).

[0240] That is, the second STA may announce a (broadcast) TWT element (e.g., the first TWT element) for a scheduled PS and / or PUO to the first STA. Here, the SP indicated / set by the (broadcast) TWT element (e.g., the broadcast TWT SP for the PS and / or the broadcast TWT SP for the PUO) may mean an available and / or awake state. And, the time interval outside the SP indicated / set by the (broadcast) TWT element may mean an unavailable and / or doze state.

[0241] Based on the fact that the external time of at least one broadcast TWT SP associated with at least one broadcast TWT parameter set field does not belong within another TWT SP, the NDP paging indicator / unavailable mode subfield value included in the first TWT element may be set to 0 (or, 1).

[0242] Based on the fact that the external time of at least one TWT SP belongs within a specific TWT SP, the second STA can transmit a first frame containing the second TWT element to the first STA (S1820).

[0243] For example, if the out-time of at least one TWT SP falls within a specific TWT SP (e.g., a new TWT SP), the second STA may transmit information related to the update of the NDP paging indicator / unavailable mode subfield value to the first STA (via the first frame). For example, if the second STA detects that the out-time of at least one TWT SP falls within a specific TWT SP, it may transmit the corresponding first frame to the first STA.

[0244] And, the second STA can transmit the first frame and / or the second frame to the first STA, in which the value of the NDP paging indicator / unavailable mode subfield (e.g., the second NDP paging indicator / unavailable mode subfield) is set to 1.

[0245] Additionally or alternatively, to ensure that the outside of the SP directed / set / scheduled by the (broadcast) TWT element becomes unavailable and / or sleep, the second NDP paging indicator / unavailable mode subfield value included in the (broadcast) TWT element (e.g., the second TWT element) may be set to 1, and the responder PM mode subfield value may be set to 1.

[0246] The method described in the example of FIG. 18 can 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 can transmit a TWT element containing at least one broadcast TWT parameter set field to the first STA through one or more transceivers (206). Based on the fact that the external time of at least one TWT SP falls within a specific TWT SP, one or more processors (202) can transmit a first frame containing the second TWT element through one or more transceivers (206).

[0247] Furthermore, one or more memories (204) of the second device (200) may store instructions for performing the method described in the example of FIG. 18 or the examples described below when executed by one or more processors (202).

[0248] The examples of FIGS. 17 and 18 may correspond to some of the various examples of the present disclosure. Hereinafter, various examples of the present disclosure including the examples of FIGS. 17 and 18 will be described in more detail.

[0249] Example 1

[0250] Example 1 relates to basic procedures for IDC operation and rules for TWT scheduling APs.

[0251] Generally, IDC situations may occur in smart devices such as smartphones, smartwatches, and AR / VR devices that can utilize both Wi-Fi and non-Wi-Fi technologies. Additionally, IDC situations may occur in multi-link devices (MLDs) that support non-simultaneous transmit and receive (NSTR) operations. IDC events in such devices may occur periodically, as shown in the example of FIG. 13. A device (e.g., STA) experiencing an IDC situation may notify other Wi-Fi devices (e.g., APs) of periodic IDC events. To this end, the aforementioned TWT procedure or other request / response procedures may be used.

[0252] For example, the rules for a TWT scheduling AP can be defined as follows:

[0253] - If a TWT scheduling AP advertises a TWT element carrying one or more broadcast TWT parameter set fields where the responder PM Mode subfield is 1 and the broadcast TWT ID subfield value is 0:

[0254] If the NDP paging indicator / unavailable mode subfield is set to 0, the AP may be unavailable during times other than the corresponding broadcast TWT SPs (except within other TWT SPs configured with or advertised by the AP);

[0255] -― If the NDP paging indicator / unavailable mode subfield is set to 1, the AP may be unavailable during times other than the broadcasted TWT SPs, even if those times are set with the AP or fall within other TWT SPs advertised by the AP.

[0256] The TWT scheduling AP may include a unique value in the Broadcast TWT ID subfield for each Broadcast TWT to identify each Broadcast TWT, except when the TWT setup command field is an Alternate TWT or the Broadcast TWT ID subfield is 0.

[0257] For example, if the TWT setup command field indicates an alternative TWT in one of the broadcast TWT parameter set fields, the broadcast TWT element may include two broadcast TWT parameter set fields having the same broadcast TWT ID subfield value. The broadcast TWT element may include multiple broadcast TWT parameter set fields where the broadcast TWT ID subfield is 0. That is, if the broadcast TWT ID subfield value is set to 0 and the responder PM mode subfield value is set to 1, the availability of time outside the broadcast TWT SP(s) may be determined depending on whether the NDP paging indicator / unavailable mode subfield value is set to 0 or 1. It may be possible to set up scheduled PS or / and PUO schedules according to the method described above.

[0258] Additionally or alternatively, if one or more PS schedules and / or PUO schedules exist or are configured, the outside of the SP according to each schedule can be ensured to be in an unavailable state. Accordingly, a reduction in power consumption through the PS can be achieved, and unnecessary frame exchanges during the unavailable periods of the PUO can be prevented.

[0259] In one example of the present disclosure, a segment of the broadcast TWT SP(s) may correspond to an available segment and / or awake state (or segment) for a scheduled PSM (power save mode) and / or PUO, and an outer segment of the broadcast TWT SP(s) may correspond to an unavailable segment and / or sleep state. However, this is merely one embodiment, and a segment of the broadcast TWT SP(s) may correspond to an unavailable segment and / or sleep state (or segment) for a scheduled PSM and / or PUO, and an outer segment of the broadcast TWT SP(s) may correspond to an available segment and / or awake state.

[0260] As an example of the present disclosure, as illustrated in FIG. 16, the sleep time of a scheduled AP PS may overlap with the available time of a PUO SP related to BT (hereinafter PUO(BT) SP) and a PUO SP related to UWB (hereinafter PUO(UWB) SP). In this case, if the NDP paging indicator / unavailable mode subfield value of a broadcast TWT element is 0, the sleep state of the scheduled AP PS may be affected by the available schedule of other broadcast TWTs (e.g., PUO(BT) SP and PUO(UWB) SP), and thus the sleep state of the scheduled AP PS may not be maintained. Accordingly, the power consumption improvement effect according to the scheduled AP PS may be reduced.

[0261] Additionally or alternatively, the period of non-availability of PUO(BT) SP(s) may be affected by other broadcast schedules (e.g., the awake (and / or availability) period of SP(s) of PUO(UWB) according to scheduled AP PS), and the non-availability of PUO(BT) SP(s) may not be maintained.

[0262] Accordingly, the peer device may attempt frame exchange by determining that the AP is available within the unavailable interval of the PUO(BT) SP(s). However, since this interval is unavailable due to the IDC, the AP may not be able to receive frames transmitted by the peer device. Consequently, unnecessary attempts at frame exchange may result in media waste, packet loss, and data degradation (e.g., data degradation due to rate selection).

[0263] Example 1-1

[0264] Example 1-1 relates to an example of a rule for solving the problem described above.

[0265] As an example of the present disclosure, the following rules may be defined to ensure availability and / or non-availability in the overlapping interval between (broadcast) TWT SP(s) and / or PUO SP(s) for PS:

[0266] - If a TWT scheduling AP advertises a TWT element carrying one or more broadcast TWT parameter set fields where the responder PM mode subfield is 1 and the broadcast TWT ID subfield is 0:

[0267] -- If the NDP paging indicator / unavailability mode subfield is set to 1, the AP may be considered unavailable during times other than the broadcast TWT SPs, even if those times correspond to other TWT SPs configured with the AP or other TWT SPs advertised by the AP. This is intended to ensure that the AP remains unavailable during times other than the broadcast TWT SPs when the STA is running the scheduled AP PSM schedule and AP PUO schedule simultaneously.

[0268] As described above, when the NDP paging indicator / unavailable mode subfield value is 1, the unavailable state may be maintained during the time outside the broadcast TWT SPs, even if there are other TWT SPs scheduled by the AP. That is, when the NDP paging indicator / unavailable mode subfield value is set to 1, the broadcast TWT SPs may not be affected by other schedule(s). Through this, the sleep and / or unavailable periods according to the aforementioned schedule (e.g., schedule for PS and / or PUO) may not be affected by the awake and / or available periods of other schedule(s).

[0269] Examples 1-2

[0270] Example 1-2 relates to an example of a rule for solving the problem described above.

[0271] As an example of the present disclosure, the following rules may be defined to ensure availability and / or non-availability in the overlapping interval between (broadcast) TWT SP(s) and / or PUO SP(s) for PS:

[0272] - If a TWT scheduling AP advertises a TWT element carrying one or more broadcast TWT parameter set fields where the responder PM Mode subfield is 1 and the broadcast TWT ID subfield is 0, the following conditions may apply for the scheduled AP PSM and / or AP PUO:

[0273] ―- If these broadcast TWT SPs are not established with the AP or included within another TWT SP advertised by the AP, the value of the NDP paging indicator / unavailable mode subfield may be 0 or 1;

[0274] — If these broadcast TWT SPs are in a time zone that corresponds to another TWT SP advertised by the AP or configured with the AP for a scheduled AP PSM and / or AP PUO, the value of the NDP paging indicator / unavailable mode subfield may be 1 only. In this case, the UHR AP may be considered unavailable at times other than those broadcast TWT SPs.

[0275] The above rule allows the NDP paging indicator / unavailable mode subfield value to be set to 0 and / or 1 if the broadcast TWT SPs by the TWT elements advertised by the TWT scheduling AP do not overlap with other TWT SPs set up or advertised by the AP. If the broadcast TWT SPs by the TWT elements advertised by the TWT scheduling AP overlap with other TWT SPs set up or advertised by the AP, the NDP paging indicator / unavailable mode subfield value may be set to 1.

[0276] In a basic wireless LAN system, it is defined that when the broadcast TWT ID is 0 and the responder PM mode is 1, if the unavailability mode subfield is 1, the outside of the broadcast TWT SPs may be exceptionally unavailable. In next-generation wireless LAN systems, for AP PUO caused by scheduled AP PS and / or IDC, a rule may be defined in which the NDP paging indicator / unavailability mode subfield value is set to 1 if the broadcast TWT SPs by the TWT elements advertised by the TWT scheduling AP overlap with other TWT SPs set up or advertised by the AP.

[0277] Through this, the sleep period and / or unavailable period of each schedule shown in FIG. 16 may not be affected by the awake period and / or available period of other schedules.

[0278] Examples 1-3

[0279] Examples 1-3 relate to one example of a rule for solving the problem described above.

[0280] As an example of the present disclosure, the following rules may be defined to ensure availability and / or non-availability in the overlapping interval between (broadcast) TWT SP(s) and / or PUO SP(s) for PS:

[0281] - If a TWT-scheduled UHR AP advertises a TWT element carrying one or more broadcast TWT parameter set fields where the responder PM mode subfield is 1 and the broadcast TWT ID subfield is 0, the following conditions may apply to the scheduled AP PSM and / or AP PUO:

[0282] If the time outside of such broadcast TWT SP does not belong to another TWT SP established with the UHR AP or advertised by the UHR AP, the value of the NDP paging indicator / unavailable mode subfield may be either 0 or 1;

[0283] — If a time outside of such broadcast TWT SP is set with the UHR AP or belongs to another TWT SP advertised by the UHR AP, the value of the NDP paging indicator / unavailable mode subfield may be 1 only. In this case, the UHR AP may be considered unavailable at times outside of the corresponding broadcast TWT SP.

[0284] The above rule allows the value of the NDP paging indicator / unavailable mode subfield to be set to 0 and / or 1 if the area outside the broadcast SPs by the TWT element advertised by the TWT scheduling AP does not overlap with other TWT SPs set up or advertised by the AP. And, if the area outside the broadcast TWT SPs by the TWT element advertised by the TWT scheduling AP overlaps with other TWT SPs set up or advertised by the AP, the value of the NDP paging indicator / unavailable mode subfield may be set to 1 only.

[0285] In a basic wireless LAN system, it is defined that when the broadcast TWT ID is 0 and the responder PM mode is 1, if the unavailability mode subfield is 1, the outside of the broadcast TWT SPs may be exceptionally unavailable. In next-generation wireless LAN systems, for AP PUO caused by scheduled AP PS and / or IDC, a rule may be defined in which the NDP paging indicator / unavailability mode subfield value is set to 1 if the broadcast TWT SPs by the TWT elements advertised by the TWT scheduling AP overlap with other TWT SPs set up or advertised by the AP.

[0286] Through this, the sleep period and / or unavailable period of each schedule shown in FIG. 16 may not be affected by the awake period and / or available period of other schedules.

[0287] Examples 1-4

[0288] Examples 1-4 relate to one example of a rule for solving the problem described above.

[0289] As an example of the present disclosure, the following rules may be defined to ensure availability and / or non-availability in the overlapping interval between (broadcast) TWT SP(s) and / or PUO SP(s) for PS:

[0290] - If a TWT scheduling UHR AP advertises a TWT element carrying one or more broadcast TWT parameter set fields where the responder PM mode subfield is 1 and the broadcast TWT ID subfield is 0, the following conditions may apply to the scheduled AP PSM and / or AP PUO:

[0291] -- If a time outside of such broadcast TWT SP is set on a UHR AP or does not belong to another TWT SP advertised by the UHR AP, the NDP paging indicator / unavailable mode subfield value may be set to 0 or 1;

[0292] -- If a time outside of these broadcast TWT SPs is set on the UHR AP or belongs to another TWT SP advertised by the UHR AP, the value of the NDP paging indicator / unavailable mode subfield may be set to 1. In this case, the UHR AP may be considered unavailable outside of these broadcast TWT SPs.

[0293] Additionally or alternatively, the following rules may be defined to ensure availability and / or non-availability in the overlap interval between (broadcast) TWT SP(s) and / or PUO SP(s) for PS:

[0294] - If a TWT scheduling UHR AP advertises a TWT element carrying one or more broadcast TWT parameter set fields where the responder PM mode subfield is 1 and the broadcast TWT ID subfield is 0, the following conditions may apply to the scheduled AP PSM and / or AP PUO:

[0295] -- If a time outside of such broadcast TWT SP is set on a UHR AP or does not belong to another TWT SP advertised by the UHR AP, the value of the NDP paging indicator / unavailable mode subfield may be set to 0 or 1;

[0296] ― If a time outside of these broadcast TWT SPs is set on the UHR AP or belongs to another TWT SP advertised by the UHR AP, the value of the NDP paging indicator / unavailable mode subfield may be set to 1. In this case, the UHR AP may be considered unavailable outside of these broadcast TWT SPs.

[0297] Additionally or alternatively, the following rules may be defined to ensure availability and / or non-availability in the overlap interval between (broadcast) TWT SP(s) and / or PUO SP(s) for PS:

[0298] - If a TWT scheduling UHR AP advertises a TWT element carrying one or more broadcast TWT parameter set fields where the responder PM mode subfield is 1 and the broadcast TWT ID subfield is 0, the following conditions may apply to the scheduled AP PSM and / or AP PUO:

[0299] -- If a time outside of such broadcast TWT SP is set on a UHR AP or does not belong to another TWT SP advertised by the UHR AP, the value of the NDP paging indicator / unavailable mode subfield may be set to 0 or 1;

[0300] -- If a time outside of these broadcast TWT SPs is set on the UHR AP or belongs to another TWT SP advertised by the UHR AP, the value of the NDP paging indicator / unavailable mode subfield may be set to 1. In this case, the UHR AP may be considered unavailable outside of these broadcast TWT SPs.

[0301] Example 2

[0302] Example 2 relates to a method for updating an NDP paging indicator / unavailable mode subfield according to a broadcast TWT schedule situation.

[0303] As described in Example 1 and / or Detailed Example, to satisfy the out-of-service availability of broadcast TWT SPs for AP PUO due to scheduled AP PS and / or IDC or TWTs for other uses, the NDP paging indicator / out-of-service mode subfield value may be set to 1.

[0304] Additionally or alternatively, when only the broadcast TWT for the scheduled AP PS is running (e.g., when only the TWT SP for the PS is configured) and / or when the broadcast TWT SPs for the AP PUO caused by the scheduled AP PS and IDC are running / configured and the exterior of each SP does not overlap with the activation periods of other TWT SP(s), the NDP Paging Indicator / Unavailable Mode subfield value may be set to 0. Subsequently, if TWT SP(s) that overlap with the exterior of the broadcast TWT SP for the AP PUO caused by the scheduled AP PS and IDC are set up by the AP, the NDP Paging Indicator / Unavailable Mode subfield value may be updated to 1.

[0305] Below, we will describe one or more methods to update the NDP paging indicator / unavailable mode subfield value to 1.

[0306] Example 2-1

[0307] Example 2-1 relates to a method for updating the NDP paging indicator / unavailable mode subfield value of the control field of a TWT element according to the DTIM (Delivered Traffic Indication Map) beacon cycle.

[0308] DTIM beacons may include beacons that non-AP STA(s) must be able to listen to in order to check the buffered data status. In describing this disclosure, "beacon" may be replaced / represented as "beacon frame." To maintain a sleep duty cycle, non-AP STA(s) may receive DTIM beacons to receive buffered data from the AP even if they do not listen to all beacons. That is, the probability of receiving DTIM beacons may be high.

[0309] Accordingly, non-AP STA(s) can obtain the updated TWT element by updating the NDP paging indicator / unavailable mode subfield included in the control field of the TWT element according to the DTIM beacon period. Here, the DTIM beacon period can be determined based on "DTIM count=0" and the DTIM period (Period) of the TIM element of the beacon frame.

[0310] FIG. 19 is a diagram illustrating a method for updating an NDP paging indicator / unavailable mode subfield through a DTIM beacon cycle according to one embodiment of the present disclosure.

[0311] In one example of the present disclosure, for broadcast TWT SP(s) for PUO due to scheduled AP PS and / or IDC to be set / operated (e.g., when the awake period of other TWT SP(s) does not overlap with the outside of said broadcast TWT SP(s),) the NDP paging indicator / unavailable mode subfield value within the TWT element may be set to 0. For example, as illustrated in FIG. 19, broadcast TWT SP(s) for PS may be set, and said TWT SP(s) may correspond to the awake period(s).

[0312] Subsequently, if the exterior of the broadcast TWT SP(s) overlaps with other TWT SP(s) (e.g., TWT SP(s) set by a PUO schedule according to BT), the NDP paging indicator / unavailable mode subfield value included in the control field of the TWT element can be updated to 1 using the DTIM period.

[0313] For example, if the AP detects / identifies that the exterior of the broadcast TWT SP(s) overlaps with other TWT SP(s), the AP may generate a (DTIM) beacon frame with the NDP paging indicator / unavailable mode subfield value set to 1. Then, the AP may transmit the (DTIM) beacon frame to non-AP STA(s) at a DTIM period (or time) after the point in time when the overlap between the exterior of the broadcast TWT SP(s) and other TWT SP(s) was detected / identified. Accordingly, the non-AP STA(s) can confirm that the exterior of the broadcast TWT SP(s) is subsequently unavailable by obtaining the TWT element updated at the DTIM beacon period.

[0314] Example 2-2

[0315] Example 2-2 relates to a method for updating the NDP paging indicator / unavailable mode subfield value using the broadcast TWT persistence subfield of the broadcast TWT information subfield.

[0316] That is, the NDP paging indicator / unavailable mode subfield within the control field of a TWT element can be updated using the broadcast TWT persistence subfield of the broadcast TWT parameter set field.

[0317] FIG. 20 is a diagram illustrating a method for updating an NDP paging indicator / unavailable mode subfield through a broadcast TWT persistence subfield according to one embodiment of the present disclosure.

[0318] In one example of the present disclosure, for broadcast TWT SP(s) for PUO due to scheduled AP PS and / or IDC to be set / operated (e.g., when the awake period of other TWT SP(s) does not overlap with the outside of said broadcast TWT SP(s),) the NDP paging indicator / unavailable mode subfield value within the TWT element may be set to 0. For example, as illustrated in FIG. 19, broadcast TWT SP(s) for PS may be set, and said TWT SP(s) may correspond to the awake period(s).

[0319] Subsequently, if the exterior of the broadcast TWT SP(s) overlaps with other TWT SP(s) (e.g., TWT SP(s) set by a PUO schedule based on a BT), the value of the broadcast TWT persistence subfield within the broadcast TWT information of the TWT element may be adjusted (e.g., 5). Non-AP STA(s) that receive the TWT element containing the broadcast TWT persistence subfield can check the number of TBTTs until the TWT element is updated. The number of TBTTs may be the number of TBTTs from the current point in time (e.g., when the broadcast TWT persistence subfield is received) until the exterior of the broadcast TWT SP(s) overlaps with other TWT SP(s).

[0320] For example, if the number of TBTTs until the TWT element is updated becomes 0 (or / and the broadcast TWT persistence subfield value becomes 0), the NDP paging indicator / unavailable mode subfield value within the control field of the TWT element may be set to 1. That is, if the number of TBTTs until the TWT element is updated becomes 0 (or / and the broadcast TWT persistence subfield value becomes 0), non-AP STA(s) may receive a TWT element from the AP with the NDP paging indicator / unavailable mode subfield value set to 1. Accordingly, non-AP STA(s) may determine that the outside of the corresponding broadcast TWT SP(s) is unavailable.

[0321] Examples 2-3

[0322] Examples 2-3 relate to a method for updating an NDP paging indicator / unavailable mode subfield based on a BSS parameters change count subfield and a broadcast TWT persistence subfield, according to one embodiment of the present disclosure.

[0323] Here, the probe response frame and / or (re)combination response frame includes a reduced neighbor report (RNR) element, the RNR element includes neighbor AP information fields, and the neighbor AP information fields may include TBTT information fields. And, the multi-link device (MLD) parameter subfield within the TBTT information field may include a BSS parameter change count subfield.

[0324] For basic wireless LAN systems, the BSS parameter change count subfield of the RNR element included in the beacon (and / or probe response) frame may be used for critical updates of MLD devices. For example, when network conditions, interference, traffic load, or policy changes occur within the BSS, the AP may detect the need to update specific BSS parameters and increment the BSS parameter change count value.

[0325] A non-AP STA(s) that receives a frame containing the BSS parameter change counter value from the AP can verify and apply the updated parameter(s) through the frame. At this time, the non-AP STA(s) can send an ACK for the frame (or / and an ACK for the application of the updated parameter(s)) to the AP (if necessary). Through the method described above, the NDP paging indicator / unavailable mode subfield within the control field of the TWT element can be updated.

[0326] FIG. 21 is a diagram illustrating a method for updating an NDP paging indicator / unavailable mode subfield based on a BSS parameter change count subfield and a broadcast TWT persistence subfield according to one embodiment of the present disclosure.

[0327] In one example of the present disclosure, for broadcast TWT SP(s) for PUO due to scheduled AP PS and / or IDC to be set / operated (e.g., when the awake period of other TWT SP(s) does not overlap with the outside of said broadcast TWT SP(s),) the NDP paging indicator / unavailable mode subfield value within the TWT element may be set to 0. For example, as illustrated in FIG. 21, broadcast TWT SP(s) for PS may be set, and said TWT SP(s) may correspond to the awake period(s).

[0328] Subsequently, if the exterior of the broadcast TWT SP(s) overlaps with other TWT SP(s) (e.g., TWT SP(s) set by a PUO schedule based on a BT), the AP may instruct (non-AP STA(s)) that the NDP paging indicator / unavailable mode subfield value within the TWT element be updated to 1 by increasing the BSS parameter change count subfield value.

[0329] For example, as illustrated in FIG. 21, if the exterior of the broadcast TWT SP(s) is detected / identified as overlapping with other TWT SP(s), the AP may increase the BSS parameter change count subfield value from 0 to 1 and set the broadcast TWT persistence subfield value to a specific value (e.g., 3). A non-AP STA(s) that receives a beacon frame containing the BSS parameter change count subfield set to 1 and the broadcast TWT persistence subfield set to a specific value may check whether and / or when the NDP paging indicator / unavailable mode subfield value is updated.

[0330] For example, the NDP paging indicator / unavailable mode subfield value can be updated to 1 through a beacon frame containing a BSS parameter change count subfield set to 1 and a broadcast TWT persistence subfield set to 0. That is, non-AP STA(s) can receive a beacon frame from the AP containing a TWT element with the NDP paging indicator / unavailable mode subfield value set to 1. Accordingly, the non-AP STA(s) can confirm that the outside of the corresponding broadcast TWT SP(s) is unavailable.

[0331] Examples 2-4

[0332] Examples 2-4 relate to a method for updating an NDP paging indicator / unavailable mode subfield using a critical update flag subfield included in capability information within a beacon frame and / or probe response frame.

[0333] FIG. 22 is a diagram illustrating a method for updating an NDP paging indicator / unavailable mode subfield using an important update flag according to one embodiment of the present disclosure.

[0334] For basic wireless LAN systems, the BSS parameter change count subfield of the RNR element included in the beacon (and / or probe response) frame may be used for critical updates of MLD devices. For example, when network conditions, interference, traffic load, or policy changes occur within the BSS, the AP may detect the need to update specific BSS parameters and then increment the BSS parameter change count value. Non-AP STA(s) that receive a frame containing the BSS parameter change counter value from the AP may verify and apply the updated parameter(s) through the frame. At this time, the non-AP STA(s) may send an ACK for the frame (or / and an ACK for the application of the updated parameter(s)) to the AP (if necessary). Through the method described above, the NDP paging indicator / unavailable mode subfield within the control field of the TWT element may be updated.

[0335] In one example of the present disclosure, in order for broadcast TWT SP(s) for PUO due to scheduled AP PS and / or IDC to be set / operated (e.g., when the awake period of other TWT SP(s) does not overlap with the outside of said broadcast TWT SP(s),) the NDP paging indicator / unavailable mode subfield value within the TWT element may be set to 0. For example, as illustrated in FIG. 22, broadcast TWT SP(s) for PS may be set, and said TWT SP(s) may correspond to the awake period(s).

[0336] Subsequently, if the exterior of the broadcast TWT SP(s) overlaps with other TWT SP(s) (e.g., TWT SP(s) set by a PUO schedule based on a BT), it may be indicated that the NDP paging indicator / unavailable mode subfield of the TWT element should be updated to 1 as the value of the key update flag subfield included in the capability information changes. The change in the NDP paging indicator / unavailable mode subfield value may be retained until the next DTIM.

[0337] That is, as illustrated in FIG. 22, when a beacon frame is received in which the value of the key update flag subfield included in the capability information has changed from 0 to 1, the non-AP STA can interpret / decode the key update flag subfield when receiving the next DIM and / or previous beacon frame to determine whether the NDP paging indicator / unavailable mode subfield of the TWT element has been updated to 1.

[0338] Non-AP STA(s) can confirm that the outside of the corresponding broadcast TWT SP(s) is unavailable by confirming that the NDP paging indicator / unavailable mode subfield value is updated to 1.

[0339] Example 3

[0340] Example 3 relates to a method for assigning an ID to distinguish between the broadcast TWT schedules of PUO and AP PS.

[0341] It is assumed that the outside of the Broadcast TWT SP is scheduled to be unavailable based on the responder PM mode subfield value being set to 1, the Broadcast TWT ID subfield value being set to 0, and the NDP paging indicator / unavailable mode subfield value being set to 1, as described above in each embodiment (e.g., Embodiment 1 and / or Embodiment 2). In this case, if one or more Broadcast TWT schedules (e.g., Broadcast TWT SPs) coexist through one or more Broadcast TWT parameter(s), unique identifier information may be included / mapped for each Broadcast TWT schedule. Here, one or more Broadcast TWT schedules may include scheduled PSM(s) and PUO schedule(s).

[0342] In basic wireless LAN systems, when the broadcast TWT ID subfield value is 0, one or more broadcast TWT parameters may be included in a frame (e.g., a beacon frame), but there was a problem in that there was no way to distinguish the schedule, information, and procedures associated with each TWT parameter. For example, in basic wireless LAN systems, since there is no information to indicate or distinguish whether the external broadcast TWT SP (e.g., broadcast TWT, AP PS mode, broadcast TWT SP according to PUO) is unavailable, it may be difficult to update each broadcast TWT parameter.

[0343] In the following, to resolve the above problem, we will explain a method for assigning IDs to distinguish between the broadcast TWT schedules of PUO and AP PS.

[0344] As an example of the present disclosure, the broadcast TWT recommendation subfield of the request type field within the broadcast TWT parameter set may be defined as shown in Table 1 below. That is, the outer area of ​​the broadcast TWT SP(s) instruction (e.g., unavailable period) may be defined / indicated according to the value of the broadcast TWT recommendation subfield below. However, the value of the broadcast TWT recommendation field below may be set to one of 6 to 7, not just 5, or set to another value.

[0345] Broadcast TWT Recommended Field Value Description when transmitted within the Broadcast TWT element 5 The corresponding Broadcast TWT SP is represented as an SP that cannot use time outside the Broadcast SP.

[0346] Additionally or alternatively, a new PUO ID may be defined to distinguish one or more schedules for which the broadcast TWT ID subfield value is 0. For example, the broadcast TWT information subfield may be defined as shown in Table 2.

[0347] Bits : B0-B2 Bits : B3-B7 Bits : B8-B15 PUO ID Broadcast TWT ID Broadcast TWT Duration

[0348] In one example of the present disclosure, when the outside of a broadcast TWT SP is defined as unavailable as described above (e.g., when the broadcast TWT recommendation field value is 5 or another value as in Table 1), the PUO ID may be used as a unique identifier to identify one or more broadcast TWTs (or broadcast TWT SPs) that can be scheduled for AP PSMs, PUOs, etc. When the broadcast TWT recommendation field value is set to 5 or another value as in Table 1, the PUO ID value may be defined / used. Additionally or alternatively, the PUO ID may be defined / used based on the broadcast TWT recommendation field value. In one example of the present disclosure, when the broadcast TWT ID subfield value is set to 0, the PUO ID value may be set / assigned to one of 0 to 7. The broadcast TWT ID subfield value may be reserved. For example, if there is one or more broadcast TWT parameter set fields with a broadcast TWT ID value of 0, the PUO ID can be used to distinguish each broadcast TWT parameter set.

[0349] FIG. 23 is a drawing for explaining a method of using a PUO ID according to one embodiment of the present disclosure.

[0350] As an example of the present disclosure, as illustrated in FIG. 23, a PUO ID value (e.g., 0) may be set / associated with a broadcast TWT SP for a scheduled AP PS (or a broadcast TWT parameter set corresponding to the broadcast TWT SP). A PUO ID value (e.g., 1) may be set / associated with a broadcast TWT SP for an AP PUO schedule (e.g., PUO due to BT) (or a broadcast TWT parameter set corresponding to the broadcast TWT SP). And, a PUO ID value (e.g., 2) may be set / associated with a broadcast TWT SP for an AP PUO schedule (e.g., PUO due to UWB) (or a broadcast TWT parameter set corresponding to the broadcast TWT SP).

[0351] As described above, when a TWT SP is indicated by including a PUO ID in each broadcast TWT parameter set field, the rule for modifying the broadcast TWT parameter set(s) may be extended or applied.

[0352] As an example of the present disclosure, the TWT setup command subfield of the broadcast TWT parameter set field may be set to an alternate TWT, and the broadcast TWT persistence subfield value remaining until the broadcast TWT parameter is modified may be set separately. If the broadcast TWT persistence subfield value becomes 0, the broadcast TWT persistence subfield value may be changed in subsequent TBTTs. For example, the current broadcast TWT parameter set field and the future broadcast TWT parameter set field may be included in the TWT element.

[0353] In one example of the present disclosure, if the value of the broadcast TWT ID subfield is 1 or greater, <broadcast TWT ID, MAC address> may be uniquely identified / set in the form of a tuple. Also, if the TWT setup command field is an alternative TWT, two broadcast TWT parameter set fields may be allowed.

[0354] In addition, when the broadcast TWT ID field value is 0, multiple broadcast TWT parameter set fields may be allowed. In this case, since each broadcast TWT parameter set may not be uniquely distinguished, each broadcast TWT parameter set may be identified through a PUO ID. In addition, the current broadcast TWT parameter set(s) and future broadcast TWT parameter set(s) may be sequentially placed / configured.

[0355] That is, when the value of the broadcast TWT ID subfield is 0, two sets of broadcast TWT parameters with the same PUO ID may be placed consecutively, and the TWT setup command subfield may be set to an alternative TWT. And, when the value of the broadcast TWT persistence subfield becomes 0, the TWT setup command field is set to an accept TWT, and the broadcast TWT may be changed.

[0356] As an example of the present disclosure, Table 3 illustrates the configuration of a plurality of broadcast TWT parameter sets for changing a broadcast TWT.

[0357] Octet: 1111 Element ID Length Control TWT Parameter Information Current Broadcast TWT Parameter Set (PUO ID = 0) Future Broadcast TWT Parameter Set (PUO ID = 0) Broadcast TWT Parameter Set (PUO ID = 1) Broadcast TWT Parameter Set (PUO ID = 2)

[0358] As disclosed in Table 3, the NDP paging indicator / unavailable mode subfield and the responder PM mode subfield within the control field are each set to 1, and two sets of TWT parameters for PUO ID 0 are included, the first set of TWT parameters can be interpreted as the current broadcast TWT parameter set, and the second set of TWT parameters can be interpreted as the future broadcast TWT parameter set. For example, the TWT setup command in the request type field of the broadcast TWT parameter sets corresponding to "PUO ID = 0" can be indicated as an alternative TWT. Also, the PUO ID within the broadcast TWT information field can be uniquely identified / set to 0, 1, or 2, and the value of the broadcast TWT ID subfield can be set to 0.

[0359] For example, if the value of the broadcast TWT persistence subfield in the broadcast TWT information field of the broadcast TWT parameter set corresponding to PUO ID 0 becomes 0, the TWT setup command can be switched to the acknowledgment TWT in the next TBTT.

[0360] By various embodiments of the present disclosure, problems related to the operation of unavailable sections that occur when the exteriors of one or more PUO schedules (e.g., TWT SP according to one or more PUOs) and other broadcast TWT schedules (e.g., one or more broadcast TWT SPs) defined in a next-generation wireless LAN system overlap with each other can be efficiently resolved.

[0361] The embodiments described above are combinations of the components and features of the present disclosure in a specific form. Each component or feature should be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, it is possible to construct 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 obvious that embodiments may be constructed by combining claims that are not explicitly related in the claims, or that they may be included as new claims by amendment after filing.

[0362] It is obvious to those skilled in the art that the present disclosure may be embodied in other specific forms without departing from the essential features of the present disclosure. Accordingly, the detailed description set forth above should not be interpreted restrictively in all respects and should be considered exemplary. The scope of the present disclosure shall be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present disclosure are included within the scope of the present disclosure.

[0363] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that enable operations according to the methods of various embodiments to be executed on a device or computer, and a non-transitory computer-readable medium on which such software or instructions, etc. are stored and executable on a device or computer. Instructions that may be used to program a processing system to perform the features described in the present disclosure may be stored on or within a storage medium or a computer-readable storage medium, and the features described in the present disclosure may be implemented using a computer program product comprising such a storage medium. The storage medium may 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 may 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 may optionally include one or more storage devices located remotely from the processor(s). Memory or alternatively, non-volatile memory device(s) within memory comprises a non-transient computer-readable storage medium. The features described in this disclosure may be stored in any one of the machine-readable media and integrated into software and / or firmware that can control the hardware of a processing system and allow the processing system to interact with other mechanisms utilizing results according to the embodiments of this disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0364] Although the method proposed in this disclosure has been described with an example applied to an IEEE 802.11-based system, it can be applied to various wireless LANs or wireless communication systems in addition to IEEE 802.11-based systems.

Claims

1. A first TWT element including at least one broadcast target wake time (TWT) parameter set field is received by the first station (STA) from the second STA, A step of setting the value of the first null data physical layer protocol data unit (NDP) paging indicator / unavailability mode subfield included in the first TWT element to 0, based on the fact that the outside time of at least one broadcast TWT service period (SP) associated with at least one broadcast TWT parameter set field does not belong within another TWT SP; and Based on the fact that the external time of at least one TWT SP belongs within a specific TWT SP, the method includes the step of receiving a first frame containing a second TWT element from the second STA by the first STA. The value of the second NDP indicator / unavailable mode subfield of the above second TWT element is set to 1, and The above first frame is a method comprising information related to the update of an NDP paging / indicator unavailable mode subfield.

2. In Paragraph 1, A method in which the value of the first NDP paging indicator / unavailable mode subfield included in the first TWT element is set to 1, based on the fact that the external time of at least one broadcast TWT SP associated with the at least one broadcast TWT parameter set field belongs within the other TWT SP.

3. In Paragraph 1, The above other TWT SP and the above specific TWT SP are a method advertised or set up by the above second STA.

4. In Paragraph 1, A method in which the first NDP paging indicator / unavailable mode subfield value is allowed to be set to 0 or 1 based on the fact that the external time of at least one broadcast TWT SP associated with at least one broadcast TWT parameter set field does not belong within another TWT SP.

5. In Paragraph 1, The value of the responder power management (PM) mode subfield included in the control field of the first TWT element is set to 1, and A method in which the value of the broadcast TWT identifier (ID) subfield of at least one broadcast TWT parameter set field is set to 0.

6. In Paragraph 1, A method in which the external time of at least one broadcast TWT SP is unavailable regardless of the specific TWT SP.

7. In Paragraph 1, A method wherein at least one broadcast TWT parameter set field comprises a broadcast TWT parameter set field for power save (PS) and a broadcast TWT parameter set field for periodic unavailability operation (PUO).

8. In Paragraph 7, The broadcast TWT parameter set field for the above PS includes a PUO ID subfield set to a first value, and A method in which a broadcast TWT parameter set field for the above PUO includes a PUO ID subfield set to a second value.

9. In Paragraph 1, A method in which at least one of the other TWT SPs or the specific TWT SPs is a separate broadcast TWT SP for power saving or PUO.

10. In Paragraph 1, A method in which information regarding the update of the above NDP paging indicator / unavailable mode subfield is based on the broadcast TWT persistence subfield included in the second TWT element of the first frame, the basic service set (BSS) parameter change count subfield included in the first frame, or the critical update flag subfield included in the capability information of the first frame.

11. In Paragraph 1, A method comprising at least one of the following: information related to the update of the above NDP paging indicator / unavailable mode subfield, which includes information indicating that the value of the second NDP paging indicator / unavailable mode subfield is set to 1, or the time when the value of the second NDP paging indicator / unavailable mode subfield is changed to 1.

12. In Paragraph 1, A method in which the value of the third NDP paging indicator / unavailable mode subfield of the second frame transmitted after the first frame is set to 1.

13. In Paragraph 1, The above-mentioned first STA is a non-access point (AP) STA, and The above second STA is a method that is an access point (AP).

14. In Paragraph 1, A method in which the first frame comprises at least one of a beacon frame, a probe response frame, or a combined response frame.

15. In Paragraph 12, A method in which the above first frame is transmitted to the above first STA according to the DTIM (delivered traffic indication map) beacon period.

16. In the first STA, the first STA is: One or more transceivers; and It includes one or more processors connected to the above one or more transmitters and receivers, and The above one or more processors are: A first TWT element including at least one broadcast target wake time (TWT) parameter set field is received from the second STA through the one or more transceivers, A step of setting the value of the first null data physical layer protocol data unit (NDP) paging indicator / unavailability mode subfield included in the first TWT element to 0, based on the fact that the outside time of at least one broadcast TWT service period (SP) associated with at least one broadcast TWT parameter set field does not belong within another TWT SP; and Based on the fact that the external time of at least one TWT SP belongs within a specific TWT SP, a first frame including a second TWT element is configured to be received from the second STA through the one or more transceivers, and The value of the second NDP indicator / unavailable mode subfield of the above second TWT element is set to 1, and The above first frame is a first STA containing information related to the update of an NDP paging / indicator unavailable mode subfield.

17. A first TWT element including at least one broadcast target wake time (TWT) parameter set field is transmitted by the second station (STA) to the first STA, wherein A step of setting the value of the first null data physical layer protocol data unit (NDP) paging indicator / unavailability mode subfield included in the first TWT element to 0, based on the fact that the outside time of at least one broadcast TWT service period (SP) associated with at least one broadcast TWT parameter set field does not belong within another TWT SP; and Based on the fact that the external time of at least one TWT SP belongs within a specific TWT SP, the method includes the step of transmitting a first frame containing a second TWT element to the first STA by the second STA. The value of the second NDP indicator / unavailable mode subfield of the above second TWT element is set to 1, and The above first frame is a method comprising information related to the update of an NDP paging / indicator unavailable mode subfield.

18. In the second station (STA), the second STA is: One or more transceivers; and It includes one or more processors connected to the above one or more transmitters and receivers, and The above one or more processors are: Transmit a TWT element including at least one broadcast target wake time (TWT) parameter set field to the first STA through the one or more transceivers, A step of setting the value of the null data physical layer protocol data unit (NDP) paging indicator / unavailability mode subfield included in the TWT element to 0 based on the fact that the outside time of at least one broadcast TWT service period (SP) associated with at least one broadcast TWT parameter set field does not belong within another TWT SP; and Based on the fact that the external time of at least one TWT SP belongs within a specific TWT SP, a first frame including a second TWT element is configured to be transmitted to the first STA through the one or more transceivers, and The value of the second NDP indicator / unavailable mode subfield of the above second TWT element is set to 1, and The first frame above is a second STA containing information related to the update of the NDP paging / indicator unavailable mode subfield.

19. A processing device configured to control a first station (STA) in a wireless local area network (WLAN) system, wherein the processing device: One or more processors; and A processing device comprising one or more computer memories that are operably connected to one or more processors and store instructions for performing a method according to any one of claims 1 to 15 based on execution by one or more processors.

20. One or more non-transitory computer-readable media storing one or more instructions, A computer-readable medium in which one or more of the above commands are executed by one or more processors to control a device in a wireless LAN system to perform a method according to any one of claims 1 to 15.

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