Method and device for performing r-TWT related notification in multi-BSS environment in wireless LAN system

Abstract

Disclosed are a method and a device for performing an R-TWT related notification in a multi-BSS environment in a wireless LAN system. A method performed by a station (STA) in a wireless LAN system according to an embodiment of the present disclosure may comprise the steps of: receiving a frame including a notification related to a restricted TWT (R-TWT) service period (SP) from a first access point (AP) associated with the STA; and performing a related operation for the R-TWT SP. Here, on the basis that a first R-TWT SP scheduled by the first AP and a second R-TWT SP scheduled by a second AP not associated with the STA do not overlap in the time domain, the notification may include both information related to the first R-TWT SP and information related to the second R-TWT SP.

Description

Method and device for performing R-TWT related notification in a multi-BSS environment in a wireless LAN system

[0001] The present disclosure relates to a method and apparatus for performing notification related to restricted-target wake time (R-TWT) in a multi-BSS (basic service set) environment in a Wireless Local Area Network (WLAN) system.

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

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

[0004] The technical problem of the present disclosure is to provide a method and device for performing notification related to restricted-target wake time (R-TWT) in a multi-BSS (basic service set) environment in a wireless local area network (WLAN) system.

[0005] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0006] A method performed by a station (STA) in a wireless LAN system according to one aspect of the present disclosure may include: receiving, by the STA associated with a first access point (AP) of a first basic service set (BSS), a frame transmitted from a second access point (AP) of a second basic service set (BSS); transmitting, to the first AP, information about one or more time periods that do not overlap with a restricted-target wake time (R-TWT) service period (SP) scheduled by the second AP, based on information about a restricted-target wake time (R-TWT) service period (SP) scheduled by the second AP being included in the frame; and receiving, from the first AP, scheduling information for the STA based on the information about the one or more time periods.

[0007] A method performed by a first access point (AP) in a wireless LAN system according to an additional aspect of the present disclosure may include: receiving, from a STA associated with the first AP of a first BSS, information about one or more time intervals that do not overlap with an R-TWT SP scheduled by a second AP of a second BSS; and allocating and notifying scheduling information for the STA based on the information about the one or more time intervals.

[0008] A method performed by a station (STA) in a wireless LAN system according to an additional aspect of the present disclosure may include: receiving, from a first access point (AP) to which the STA is associated, a frame including an announcement related to a restricted-TWT (R-TWT) service period (SP); and performing a related operation for the R-TWT SP. Here, based on a first R-TWT SP scheduled by the first AP and a second R-TWT SP scheduled by a second AP to which the STA is not associated, not overlapping in the time domain, the announcement may include both information related to the first R-TWT SP and information related to the second R-TWT SP.

[0009] In accordance with an additional aspect of the present disclosure, a method performed by a first access point (AP) in a wireless LAN system may include: obtaining information about a restricted-TWT (R-TWT) service period (SP) scheduled by a second AP belonging to a second BSS different from a first BSS to which the first AP belongs; determining whether an R-TWT SP by the second AP overlaps with an R-TWT SP scheduled by the first AP; and transmitting a frame for notifying both information related to an R-TWT SP scheduled by the first AP and information related to an R-TWT SP scheduled by the second AP based on the R-TWT SP scheduled by the first AP and the R-TWT SP scheduled by the second AP not overlapping in the time domain.

[0010] According to the present disclosure, a method and device for performing notification related to restricted-target wake time (R-TWT) in a multi-BSS (basic service set) environment in a wireless local area network (WLAN) system can be provided.

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

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

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

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

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

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

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

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

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

[0020] FIG. 8 is a diagram for explaining various transmission and reception techniques in a MAP environment to which the present disclosure can be applied.

[0021] FIG. 9 is a diagram illustrating an example of an individual TWT operation to which the present disclosure can be applied.

[0022] FIG. 10 is a diagram illustrating an example of a broadcast TWT operation to which the present disclosure can be applied.

[0023] FIG. 11 is a diagram exemplarily showing APs and STAs in an OBSS to which the present disclosure can be applied.

[0024] FIG. 12 illustrates an example of STA operation according to the present disclosure.

[0025] FIG. 13 illustrates another example of the first AP operation according to the present disclosure.

[0026] FIG. 14 illustrates STA operation for an overlapping cooperative R-TWT SP according to the present disclosure.

[0027] Figure 15 illustrates the configuration of cooperative R-TWT information according to the present disclosure.

[0028] FIG. 16 illustrates an example of STA operation for a non-overlapping cooperative R-TWT SP according to the present disclosure.

[0029] FIG. 17 illustrates another example of STA operation for a non-overlapping cooperative R-TWT SP according to the present disclosure.

[0030] FIG. 18 illustrates the operation of an AP performing an announcement to a cooperative R-TWT SP and / or a cooperative OBSS R-TWT SP according to the present disclosure.

[0031] FIG. 19 illustrates the operation of an STA for a known R-TWT SP according to the present disclosure.

[0032] FIG. 20 illustrates another example of STA operation according to the present disclosure.

[0033] FIG. 21 illustrates another example of the first AP operation according to the present disclosure.

[0034] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description set forth below, together with the accompanying drawings, is intended to explain exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure may be practiced. The following detailed description includes specific details to provide a thorough understanding of the present disclosure. However, one of ordinary skill in the art will appreciate that the present disclosure may be practiced without these specific details.

[0035] In some cases, to avoid obscuring the concepts of the present disclosure, known structures and devices may be omitted or illustrated in block diagram form focusing on the core functions of each structure and device.

[0036] In the present disclosure, when a component is said to be "connected," "coupled," or "connected" to another component, this may include not only a direct connection but also an indirect connection in which another component exists between them. Furthermore, the terms "comprises" or "has" in the present disclosure specify the presence of the mentioned features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0037] In this disclosure, terms such as “first,” “second,” etc. are used only to distinguish one component from another and are not used to limit the components, and do not limit the order or importance between the components unless specifically stated otherwise. Accordingly, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0038] The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "and / or" as used herein may refer to any one of the associated enumerated items, or is meant to refer to and encompass any and all possible combinations of two or more of them. Furthermore, the use of " / " between words in this disclosure has the same meaning as "and / or" unless otherwise stated.

[0039] The examples of the present disclosure can be applied to various wireless communication systems. For example, the examples of the present disclosure can be applied to a wireless LAN system. For example, the examples of the present disclosure can be applied to a wireless LAN based on the IEEE 802.11a / g / n / ac / ax / be standards. Furthermore, the examples of the present disclosure can be applied to a wireless LAN based on the newly proposed IEEE 802.11bn (or UHR) standard. Additionally, the examples of the present disclosure can be applied to a wireless LAN based on the next-generation standard after IEEE 802.11bn. Furthermore, the examples of the present disclosure can be applied to a cellular wireless communication system. For example, the examples of the present disclosure can be applied to a cellular wireless communication system based on the LTE (Long Term Evolution) series of technologies and the 5G NR (New Radio) series of technologies of the 3rd Generation Partnership Project (3GPP) standard.

[0040] Below, technical features to which examples of the present disclosure can be applied are described.

[0041] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0042] The first device (100) and the second device (200) illustrated in FIG. 1 may be replaced with various terms such as a terminal, a wireless device, a WTRU (Wireless Transmit Receive Unit), a UE (User Equipment), an MS (Mobile Station), a UT (user terminal), an MSS (Mobile Subscriber Station), an MSS (Mobile Subscriber Unit), an SS (Subscriber Station), an AMS (Advanced Mobile Station), a WT (Wireless terminal), or simply a user. In addition, the first device (100) and the second device (200) may be replaced with various terms such as an access point (AP), a BS (Base Station), a fixed station, a Node B, a BTS (Base Transceiver System), a network, an AI (Artificial Intelligence) system, an RSU (road side unit), a repeater, a router, a relay, a gateway, etc.

[0043] The devices (100, 200) illustrated in FIG. 1 may also be referred to as stations (STAs). For example, the devices (100, 200) illustrated in FIG. 1 may be referred to by various terms such as transmitting device, receiving device, transmitting STA, and receiving STA. For example, the STAs (110, 200) may perform an AP (access point) role or a non-AP role. That is, in the present disclosure, the STAs (110, 200) may perform the functions of an AP and / or a non-AP. When the STAs (110, 200) perform an AP function, they may simply be referred to as APs, and when the STAs (110, 200) perform a non-AP function, they may simply be referred to as STAs. In addition, in the present disclosure, the APs may also be referred to as AP STAs.

[0044] Referring to FIG. 1, the first device (100) and the second device (200) can transmit and receive wireless signals through various wireless LAN technologies (e.g., IEEE 802.11 series). The first device (100) and the second device (200) can include interfaces for a medium access control (MAC) layer and a physical layer (PHY) that follow the provisions of the IEEE 802.11 standard.

[0045] In addition, the first device (100) and the second device (200) may additionally support various communication standards (e.g., 3GPP LTE series, 5G NR series standards, etc.) other than wireless LAN technology. In addition, the device of the present disclosure may be implemented as various devices such as a mobile phone, a vehicle, a personal computer, an AR (Augmented Reality) device, a VR (Virtual Reality) device, etc. In addition, the STA of the present specification may support various communication services such as voice calls, video calls, data communications, autonomous driving, MTC (Machine-Type Communication), M2M (Machine-to-Machine), D2D (Device-to-Device), and IoT (Internet-of-Things).

[0046] A first device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memories (104) and / or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (102) may process information in the memories (104) to generate first information / signals, and then transmit a wireless signal including the first information / signals via the transceivers (106). Furthermore, the processor (102) may receive a wireless signal including second information / signals via the transceivers (106), and then store information obtained from signal processing of the second information / signals in the memory (104). The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software code including instructions for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (102) and the memory (104) may be part of a communication modem / circuit / chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series). The transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In the present disclosure, a device may also mean a communication modem / circuit / chip.

[0047] The second device (200) includes one or more processors (202), one or more memories (204), and may further include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memories (204) and / or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (202) may process information in the memory (204) to generate third information / signals, and then transmit a wireless signal including the third information / signals via the transceivers (206). Furthermore, the processor (202) may receive a wireless signal including fourth information / signals via the transceivers (206), and then store information obtained from signal processing of the fourth information / signals in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software code including instructions for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present disclosure, a device may also mean a communication modem / circuit / chip.

[0048] Hereinafter, the hardware elements of the device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed in the present disclosure, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed in the present disclosure.

[0049] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. The descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed in this disclosure may be implemented using firmware or software configured to perform one or more processors (102, 202) or stored in one or more memories (104, 204) and driven by one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed in this disclosure may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions.

[0050] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0051] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or flowcharts of the present disclosure, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or flowcharts of the present disclosure, from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, or the like, as referred to in the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure, via one or more antennas (108, 208). In the present disclosure, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202).One or more transceivers (106, 206) may convert user data, control information, wireless signals / channels, etc. processed by one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or filter.

[0052] For example, one of the STAs (100, 200) may perform the intended operation of an AP, and the other of the STAs (100, 200) may perform the intended operation of a non-AP STA. For example, the transceivers (106, 206) of FIG. 1 may perform transmission and reception operations of signals (e.g., packets or PPDUs (Physical layer Protocol Data Units) according to IEEE 802.11a / b / g / n / ac / ax / be / bn, etc.). In addition, in the present disclosure, operations in which various STAs generate transmission and reception signals or perform data processing or calculations in advance for transmission and reception signals may be performed in the processors (102, 202) of FIG. 1. For example, an example of an operation for generating a transmission / reception signal or performing data processing or operation in advance for a transmission / reception signal may include 1) an operation for determining / obtaining / configuring / computing / decoding / encoding bit information of a field (SIG (signal), STF (short training field), LTF (long training field), Data, etc.) included in a PPDU, 2) an operation for determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) used for a field (SIG, STF, LTF, Data, etc.) included in a PPDU, 3) an operation for determining / configuring / obtaining a specific sequence (e.g., a pilot sequence, an STF / LTF sequence, an extra sequence applied to SIG) used for a field (SIG, STF, LTF, Data, etc.) included in a PPDU, 4) a power control operation and / or a power saving operation applied to an STA, 5) an operation related to determining / obtaining / configuring / computing / decoding / encoding an ACK signal, etc. Additionally, in the examples below, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs for determining / acquiring / configuring / computing / decoding / encoding transmission / reception signals can be stored in the memory (104, 204) of FIG. 1.

[0053] Hereinafter, downlink (DL) refers to a link for communication from an AP STA to a non-AP STA, and downlink PPDUs / packets / signals, etc. can be transmitted and received through the downlink. In downlink communication, the transmitter may be part of an AP STA, and the receiver may be part of a non-AP STA. Uplink (UL) refers to a link for communication from a non-AP STA to an AP STA, and uplink PPDUs / packets / signals, etc. can be transmitted and received through the uplink. In uplink communication, the transmitter may be part of a non-AP STA, and the receiver may be part of an AP STA.

[0054] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0055] The structure of a wireless LAN system can be composed of multiple components. Through the interaction of multiple components, a wireless LAN that supports transparent STA mobility to the upper layer can be provided. A Basic Service Set (BSS) corresponds to a basic building block of a wireless LAN. FIG. 2 illustrates, by way of example, the existence of two BSSs (BSS1 and BSS2) and the inclusion of two STAs as members of each BSS (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2). The oval representing a BSS in FIG. 2 can also be understood as representing a coverage area in which STAs included in the corresponding BSS maintain communication. This area can be referred to as a Basic Service Area (BSA). When an STA moves outside of a BSA, it cannot directly communicate with other STAs within the BSA.

[0056] If we do not consider the DS illustrated in Figure 2, the most basic type of BSS in a wireless LAN is an Independent BSS (IBSS). For example, an IBSS can have a minimal form consisting of only two STAs. For example, assuming other components are omitted, BSS1 consisting of only STA1 and STA2, or BSS2 consisting of only STA3 and STA4, can be representative examples of an IBSS, respectively. Such a configuration is possible when the STAs can communicate directly without an AP. Furthermore, in this type of WLAN, a LAN can be configured when needed rather than being planned in advance, and this can be called an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity. That is, in an IBSS, STAs are managed in a distributed manner. In IBSS, all STAs can be mobile STAs, and access to distributed systems (DS) is not permitted, forming a self-contained network.

[0057] An STA's membership in a BSS can dynamically change, for example, when an STA is turned on or off, or when an STA enters or leaves a BSS area. To become a member of a BSS, an STA can join the BSS using a synchronization process. To access all services in the BSS infrastructure, an STA must be associated with the BSS. This association can be dynamically established and may involve the use of a Distribution System Service (DSS).

[0058] In a wireless LAN, the direct STA-to-STA distance can be limited by PHY performance. While this distance limit may be sufficient in some cases, communication between STAs over longer distances may be required in other cases. To support extended coverage, a distributed system (DS) can be configured.

[0059] DS refers to a structure in which BSSs are interconnected. Specifically, a BSS may exist as an extended component of a network composed of multiple BSSs, as illustrated in Figure 2. DS is a logical concept and can be specified by the characteristics of a distributed system medium (DSM). In this regard, the Wireless Medium (WM) and DSM can be logically distinguished. Each logical medium is used for a different purpose and by different components. These media are neither limited to being identical nor limited to being different. This logical difference between multiple media explains the flexibility of the WLAN architecture (DS architecture or other network architectures). In other words, the WLAN architecture can be implemented in various ways, and the physical characteristics of each implementation can independently specify the WLAN architecture.

[0060] A DS can support mobile devices by providing seamless integration of multiple BSSs and the logical services necessary to handle addresses to destinations. Additionally, a DS may further include a component called a portal, which acts as a bridge for connecting wireless LANs to other networks (e.g., IEEE 802.X).

[0061] An AP is an entity that enables access to a DS through a WM for associated non-AP STAs and also has the functionality of an STA. Data movement between a BSS and a DS can be performed through an AP. For example, STA2 and STA3 illustrated in FIG. 2 have the functionality of an STA and provide the function of allowing associated non-AP STAs (STA1 and STA4) to access the DS. In addition, since all APs are basically STAs, all APs are addressable entities. The address used by an AP for communication on a WM and the address used by an AP for communication on a DSM do not necessarily have to be the same. A BSS consisting of an AP and one or more STAs can be referred to as an infrastructure BSS.

[0062] Data transmitted from one of the STA(s) associated with an AP to the STA address of that AP is always received on an uncontrolled port and can be processed by an IEEE 802.1X port access entity. In addition, if the controlled port is authenticated, the transmitted data (or frame) can be forwarded to the DS.

[0063] In addition to the structure of the DS described above, an extended service set (ESS) may be established to provide wider coverage.

[0064] An ESS is a network of arbitrary size and complexity, consisting of DSs and BSSs. An ESS may correspond to a set of BSSs connected to a DS. However, an ESS does not include a DS. An ESS network is characterized by appearing as an IBSS at the Logical Link Control (LLC) layer. STAs within an ESS can communicate with each other, and mobile STAs can move from one BSS to another (within the same ESS) transparently to the LLC. APs within an ESS may have the same SSID (service set identification). The SSID is distinct from the BSSID, which is the identifier of the BSS.

[0065] In a wireless LAN system, no assumptions are made about the relative physical locations of BSSs, and all of the following configurations are possible: BSSs can be partially overlapping, which is commonly used to provide continuous coverage. BSSs can also be physically disconnected, and there is no logical distance limit between them. BSSs can also be physically co-located, which can be used to provide redundancy. Furthermore, one (or more) IBSS or ESS networks can physically co-exist with one (or more) ESS networks. This can occur in cases where an ad-hoc network operates at the same location as an ESS network, where physically overlapping wireless networks are configured by different organizations, or where two or more different access and security policies are required at the same location.

[0066] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0067] For an STA to set up a link and transmit and receive data on a network, it must first discover the network, perform authentication, establish an association, and complete security authentication procedures. The link setup process can also be referred to as the session initiation process or session setup process. Furthermore, the discovery, authentication, association, and security setup processes of the link setup process can be collectively referred to as the association process.

[0068] In step S310, the STA may perform a network discovery operation. This network discovery operation may include scanning operations by the STA. That is, for the STA to access a network, it must search for available networks. Before joining a wireless network, the STA must identify compatible networks. The process of identifying networks in a specific area is called scanning.

[0069] Scanning methods include active scanning and passive scanning. Figure 3 illustrates a network discovery operation including an active scanning process as an example. In active scanning, an STA performing scanning transmits a probe request frame to discover any APs in the vicinity while moving between channels and waits for a response. The responder transmits a probe response frame in response to the STA that transmitted the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame in the BSS of the channel being scanned. In the BSS, the AP transmits the beacon frame, so the AP becomes the responder. In the IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not fixed. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning (i.e., transmitting and receiving probe requests / responses on channel 2) in the same manner.

[0070] Although not shown in Figure 3, the scanning operation can also be performed in a passive scanning manner. In passive scanning, the STA performing the scanning moves between channels and waits for a beacon frame. A beacon frame is one of the management frames defined in IEEE 802.11. It announces the existence of a wireless network and is periodically transmitted so that the STA performing the scanning can find the wireless network and participate in the wireless network. In the BSS, the AP performs the role of periodically transmitting the beacon frame, and in the IBSS, the STAs within the IBSS take turns transmitting the beacon frame. When the STA performing the scanning receives a beacon frame, it stores the information about the BSS included in the beacon frame and moves to another channel, recording the beacon frame information on each channel. The STA receiving the beacon frame stores the BSS-related information included in the received beacon frame and moves to the next channel to perform scanning on the next channel in the same manner. Comparing active scanning and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.

[0071] After the STA discovers the network, an authentication process may be performed in step S320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation of step S340 described below.

[0072] The authentication process involves the STA sending an authentication request frame to the AP, and the AP responding by sending an authentication response frame to the STA. The authentication frame used for the authentication request / response corresponds to a management frame.

[0073] The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), and a Finite Cyclic Group. These are just some examples of information that may be included in an authentication request / response frame, and may be replaced with other information or include additional information.

[0074] An STA can send an authentication request frame to an AP. The AP can determine whether to grant authentication to the STA based on the information contained in the received authentication request frame. The AP can provide the result of the authentication process to the STA via an authentication response frame.

[0075] After the STA is successfully authenticated, an association process may be performed in step S330. The association process includes a process in which the STA transmits an association request frame to the AP, and in response, the AP transmits an association response frame to the STA.

[0076] For example, the association request frame may include information about various capabilities, a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, RSN, a mobility domain, supported operating classes, a Traffic Indication Map Broadcast request, interworking service capabilities, etc. For example, the association response frame may include information about various capabilities, a status code, an Association ID (AID), supported rates, an Enhanced Distributed Channel Access (EDCA) parameter set, a Received Channel Power Indicator (RCPI), a Received Signal to Noise Indicator (RSNI), a mobility domain, a timeout interval (e.g., an association comeback time), overlapping BSS scan parameters, a TIM broadcast response, a Quality of Service (QoS) map, etc. These are just some examples of information that may be included in a combined request / response frame, and may be replaced by other information or include additional information.

[0077] After the STA successfully joins the network, a security setup process may be performed in step S340. The security setup process in step S340 may be referred to as an authentication process through a Robust Security Network Association (RSNA) request / response, the authentication process in step S320 may be referred to as a first authentication process, and the security setup process in step S340 may also be referred to simply as an authentication process.

[0078] The security setup process of step S340 may include, for example, a process of establishing a private key through a four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame. Furthermore, the security setup process may be performed according to a security method not defined in the IEEE 802.11 standard.

[0079] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0080] In wireless LAN systems, the basic access mechanism of MAC (Medium Access Control) is Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). The CSMA / CA mechanism, also known as the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC, essentially employs a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or STA may perform a Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time period (e.g., a DCF Inter-Frame Space (DIFS)) before starting transmission. If the sensing result determines that the medium is in an idle state, the AP and / or STA may start transmitting frames through the medium. On the other hand, if the medium is detected to be occupied or busy, the AP and / or STA may not start its own transmission, but may wait for a delay period (e.g., a random backoff period) for medium access before attempting to transmit frames. By applying a random backoff period, multiple STAs are expected to attempt to transmit frames after waiting for different periods of time, thereby minimizing collisions.

[0081] In addition, the IEEE 802.11 MAC protocol provides the Hybrid Coordination Function (HCF). The HCF is based on the DCF and the Point Coordination Function (PCF). The PCF is a polling-based synchronous access method that periodically polls all receiving APs and / or STAs to ensure that they receive data frames. In addition, the HCF has the Enhanced Distributed Channel Access (EDCA) and the HCF Controlled Channel Access (HCCA). The EDCA is a contention-based access method for a provider to provide data frames to multiple users, while the HCCA uses a non-contention-based channel access method that utilizes a polling mechanism. In addition, the HCF includes a medium access mechanism to improve the Quality of Service (QoS) of the wireless LAN, and can transmit QoS data in both the Contention Period (CP) and the Contention Free Period (CFP).

[0082] Referring to Fig. 4, an operation based on a random backoff period is described. When a medium that was occupied / busy changes to an idle state, multiple STAs can attempt to transmit data (or frames). To minimize collisions, each STA can select a random backoff count, wait for the corresponding slot time, and then attempt transmission. The random backoff count has a pseudo-random integer value and can be determined as one of the values ​​in the range of 0 to CW. Here, CW is a contention window parameter value. The CW parameter is given an initial value of CWmin, but can take a doubled value in case of transmission failure (e.g., when an ACK for a transmitted frame is not received). When the CW parameter value becomes CWmax, data transmission can be attempted while maintaining the CWmax value until data transmission is successful, and if data transmission is successful, it is reset to the CWmin value. The CW, CWmin, and CWmax values ​​are 2. n It is desirable to set it to -1 (n=0, 1, 2, ...).

[0083] Once the random backoff process begins, the STA continues to monitor the medium while counting down the backoff slots according to the determined backoff count value. If the medium is monitored as occupied, the countdown stops and waits. When the medium becomes idle, the remaining countdown resumes.

[0084] In the example of FIG. 4, when a packet to be transmitted reaches the MAC of STA3, STA3 can immediately transmit a frame if it confirms that the medium is idle for DIFS. The remaining STAs monitor the medium for occupied / busy states and wait. In the meantime, data to be transmitted may also occur in each of STA1, STA2, and STA5, and each STA can count down the backoff slot according to a random backoff count value selected by each STA after waiting for DIFS if the medium is monitored as idle. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. In other words, this example shows a case where the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1 when STA2 finishes the backoff count and starts frame transmission. STA1 and STA5 briefly stop counting down and wait while STA2 occupies the medium. When STA2's occupation ends and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume the backoff count that they had stopped. That is, they can start transmitting frames after counting down the remaining backoff slots equal to the remaining backoff time. Since STA5's remaining backoff time is shorter than STA1's, STA5 starts transmitting frames. While STA2 occupies the medium, STA4 may also have data to transmit. From STA4's perspective, when the medium becomes idle, it waits for DIFS, counts down according to its selected random backoff count value, and then starts transmitting frames. In the example of Figure 4, the remaining backoff time of STA5 coincidentally matches the random backoff count value of STA4, in which case a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 will receive an ACK, resulting in a failure in data transmission.In this case, STA4 and STA5 can select a random backoff count value and perform a countdown after doubling the CW value. STA1 waits while the medium is occupied by transmissions from STA4 and STA5, and when the medium becomes idle, it waits for DIFS and can start transmitting frames after the remaining backoff time elapses.

[0085] As in the example of Fig. 4, a data frame is a frame used for transmitting data forwarded to a higher layer, and can be transmitted after a backoff performed after DIFS elapses from when the medium becomes idle. Additionally, a management frame is a frame used for exchanging management information that is not forwarded to a higher layer, and is transmitted after a backoff performed after an IFS elapses, such as DIFS or PIFS (Point coordination function IFS). Subtype frames of a management frame include a beacon, an association request / response, a re-association request / response, a probe request / response, and an authentication request / response. A control frame is a frame used to control access to the medium. The subtype frames of the control frame include Request-To-Send (RTS), Clear-To-Send (CTS), Acknowledgment (ACK), Power Save-Poll (PS-Poll), Block ACK (BlockAck), Block ACK Request (BlockACKReq), Null Data Packet Announcement (NDP), and Trigger. If the control frame is not a response frame to the previous frame, it is transmitted after a backoff performed after the DIFS (Direct Inverse Frame Stop) has elapsed, and if it is a response frame to the previous frame, it is transmitted without a backoff performed after the SIFS (short IFS). The type and subtype of the frame can be identified by the type field and subtype field in the Frame Control (FC) field.

[0086] A QoS (Quality of Service) STA can transmit a frame after a backoff performed after the AIFS (arbitration IFS) for the access category (AC) to which the frame belongs, i.e., AIFS[i] (where i is a value determined by the AC), has elapsed. Here, the frames for which AIFS[i] can be used can be data frames, management frames, and also control frames that are not response frames.

[0087] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0088] As mentioned above, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, in which STAs directly sense the medium. Virtual carrier sensing is intended to address potential issues in medium access, such as the hidden node problem. For virtual carrier sensing, the MAC of an STA can utilize a Network Allocation Vector (NAV). The NAV is a value that an STA that is currently using or has the right to use the medium indicates to other STAs the remaining time until the medium becomes available. Therefore, the value set as NAV corresponds to the period during which the STA transmitting the frame is scheduled to use the medium, and an STA receiving the NAV value is prohibited from accessing the medium during that period. For example, the NAV can be set based on the value of the "duration" field in the MAC header of the frame.

[0089] In the example of FIG. 5, it is assumed that STA1 wants to transmit data to STA2, and STA3 is in a position to overhear some or all of the frames transmitted and received between STA1 and STA2.

[0090] In order to reduce the possibility of collisions in transmissions of multiple STAs in a CSMA / CA-based frame transmission operation, a mechanism using RTS / CTS frames may be applied. In the example of FIG. 5, while STA1 is transmitting, STA3 may determine that the medium is idle based on carrier sensing results. That is, STA1 may correspond to a hidden node for STA3. Alternatively, in the example of FIG. 5, while STA2 is transmitting, STA3 may determine that the medium is idle based on carrier sensing results. That is, STA2 may correspond to a hidden node for STA3. By exchanging RTS / CTS frames before performing data transmission and reception between STA1 and STA2, STAs outside the transmission range of either STA1 or STA2, or STAs outside the carrier sensing range for transmissions from STA1 or STA3, may not attempt to occupy the channel during data transmission and reception between STA1 and STA2.

[0091] Specifically, STA1 can determine whether a channel is occupied through carrier sensing. In terms of physical carrier sensing, STA1 can determine channel occupancy idleness based on the energy level or signal correlation detected in the channel. Furthermore, in terms of virtual carrier sensing, STA1 can determine the channel occupancy status using a network allocation vector (NAV) timer.

[0092] STA1 can transmit an RTS frame to STA2 after performing a backoff if the channel is idle during the DIFS. STA2 can transmit a CTS frame, which is a response to the RTS frame, to STA1 after an SIFS if it receives the RTS frame.

[0093] If STA3 cannot overhear a CTS frame from STA2 but can overhear an RTS frame from STA1, STA3 can use the duration information contained in the RTS frame to set a NAV timer for the subsequent consecutively transmitted frame transmission period (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame). Alternatively, if STA3 cannot overhear an RTS frame from STA1 but can overhear a CTS frame from STA2, STA3 can use the duration information contained in the CTS frame to set a NAV timer for the subsequent consecutively transmitted frame transmission period (e.g., SIFS + data frame + SIFS + ACK frame). That is, if STA3 can overhear one or more of the RTS or CTS frames from one or more of STA1 or STA2, it can set a NAV accordingly. If STA3 receives a new frame before the NAV timer expires, it can update the NAV timer using the duration information contained in the new frame. STA3 does not attempt channel access until the NAV timer expires.

[0094] If STA1 receives a CTS frame from STA2, it can transmit a data frame to STA2 after SIFS from the time when the CTS frame is completely received. If STA2 successfully receives the data frame, it can transmit an ACK frame in response to the data frame to STA1 after SIFS. STA3 can determine whether the channel is in use through carrier sensing if the NAV timer expires. If STA3 determines that the channel is not in use by another terminal during the DIFS after the NAV timer expires, it can attempt channel access after a contention window (CW) based on a random backoff has elapsed.

[0095] FIG. 6 is a drawing for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0096] The PHY layer can prepare an MPDU (MAC PDU) to be transmitted based on an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer. For example, when a command requesting the start of transmission of the PHY layer is received from the MAC layer, the PHY layer can switch to transmission mode and transmit the information (e.g., data) provided by the MAC layer in the form of a frame. In addition, when the PHY layer detects a valid preamble of the received frame, it monitors the header of the preamble and sends a command to the MAC layer notifying the start of reception of the PHY layer.

[0097] In this way, information transmission / reception in a wireless LAN system is done in the form of frames, and for this purpose, the PHY layer Protocol Data Unit (PPDU) format is defined.

[0098] A basic PPDU may include a Short Training Field (STF), a Long Training Field (LTF), a SIGNAL (SIG) field, and a Data field. The most basic (e.g., non-HT (High Throughput) as illustrated in FIG. 7) PPDU format may consist of only the Legacy-STF (L-STF), Legacy-LTF (L-LTF), Legacy-SIG (L-SIG) fields, and a Data field. Additionally, depending on the type of PPDU format (e.g., HT-mixed format PPDU, HT-greenfield format PPDU, VHT (Very High Throughput) PPDU, etc.), additional (or different types of) RL-SIG, U-SIG, non-legacy SIG field, non-legacy STF, non-legacy LTF, (i.e., xx-SIG, xx-STF, xx-LTF (e.g., xx is HT, VHT, HE, EHT, etc.)) may be included between the L-SIG field and the data field. More specific details are described below with reference to FIG. 7.

[0099] STF is a signal for signal detection, AGC (Automatic Gain Control), diversity selection, and precise time synchronization, while LTF is a signal for channel estimation, frequency error estimation, etc. STF and LTF can be said to be signals for synchronization and channel estimation of the OFDM physical layer.

[0100] The SIG field may include various information related to PPDU transmission and reception. For example, the L-SIG field may consist of 24 bits and may include a 4-bit Rate field, a 1-bit Reserved bit, a 12-bit Length field, a 1-bit Parity field, and a 6-bit Tail field. The RATE field may include information about the modulation and coding rate of data. For example, the 12-bit Length field may include information about the length or time duration of the PPDU. For example, the value of the 12-bit Length field may be determined based on the type of the PPDU. For example, for a non-HT, HT, VHT, or EHT PPDU, the value of the Length field may be determined as a multiple of 3. For example, for HE PPDU, the value of the Length field can be determined as a multiple of 3 + 1 or a multiple of 3 + 2.

[0101] The data field may include a SERVICE field, a Physical layer Service Data Unit (PSDU), a PPDU TAIL bit, and, if necessary, padding bits. Some bits of the SERVICE field may be used to synchronize the descrambler at the receiving end. The PSDU corresponds to a MAC PDU defined at the MAC layer and may contain data generated / used by upper layers. The PPDU TAIL bit may be used to return the encoder to a 0 state. The padding bit may be used to adjust the length of the data field to a predetermined unit.

[0102] MAC PDUs are defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a Frame Check Sequence (FCS). A MAC frame is composed of MAC PDUs and can be transmitted / received through the PSDU in the data portion of the PPDU format.

[0103] The MAC header includes a Frame Control field, a Duration / ID field, an Address field, etc. The Frame Control field may include control information required for frame transmission / reception. The Duration / ID field may be set to a time for transmitting the corresponding frame, etc. The Address subfields may indicate the receiver address, transmitter address, destination address, and source address of the frame, and some Address subfields may be omitted. For specific details of each subfield of the MAC header, including the Sequence Control, QoS Control, and HT Control subfields, refer to the IEEE 802.11 standard document.

[0104] The Null-Data PPDU (NDP) format refers to a PPDU format that does not include a data field. In other words, NDP refers to a frame format that includes a PPDU preamble (i.e., L-STF, L-LTF, L-SIG fields, and, if additionally present, non-legacy SIG, non-legacy STF, and non-legacy LTF) in the general PPDU format, and does not include the remaining part (i.e., data field).

[0105] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0106] Standards such as IEEE 802.11a / g / n / ac / ax use various PPDU formats. The basic PPDU format (IEEE 802.11a / g) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format can also be referred to as the non-HT PPDU format (Fig. 7(a)).

[0107] The HT PPDU format (IEEE 802.11n) additionally includes HT-SIG, HT-STF, and HT-LFT(s) fields in addition to the basic PPDU format. The HT PPDU format illustrated in Fig. 7(b) may be referred to as an HT-mixed format. Additionally, an HT-greenfield format PPDU may be defined, which corresponds to a format that does not include L-STF, L-LTF, and L-SIG, but consists of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTF, and Data fields (not illustrated).

[0108] An example of the VHT PPDU format (IEEE 802.11ac) includes VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format (Fig. 7(c)).

[0109] An example of a HE PPDU format (IEEE 802.11ax) additionally includes RL-SIG (Repeated L-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and PE (Packet Extension) fields in addition to the basic PPDU format (Fig. 7(d)). Depending on specific examples of the HE PPDU format, some fields may be excluded or their lengths may vary. For example, the HE-SIG-B field is included in the HE PPDU format for multi-users (MUs), but the HE PPDU format for single users (SUs) does not include the HE-SIG-B. In addition, the HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may vary to 8us. The HE ER (Extended Range) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may vary to 16us. For example, RL-SIG can be configured identically to L-SIG. The receiving STA can determine that the received PPDU is a HE PPDU or an EHT PPDU, described later, based on the presence of RL-SIG.

[0110] The EHT PPDU format may include the EHT MU (multi-user) PPDU of FIG. 7(e) and the EHT TB (trigger-based) PPDU of FIG. 7(f). The EHT PPDU format is similar to the HE PPDU format in that it includes an RL-SIG following an L-SIG, but may include a U (universal)-SIG, an EHT-SIG, an EHT-STF, and an EHT-LTF following the RL-SIG.

[0111] The EHT MU PPDU in FIG. 7(e) corresponds to a PPDU that carries one or more data (or PSDUs) for one or more users. That is, the EHT MU PPDU can be used for both SU transmission and MU transmission. For example, the EHT MU PPDU can correspond to a PPDU for one receiving STA or multiple receiving STAs.

[0112] The EHT TB PPDU of Fig. 7(f) omits the EHT-SIG compared to the EHT MU PPDU. An STA that has received a trigger for UL MU transmission (e.g., a trigger frame or TRS (triggered response scheduling)) can perform UL transmission based on the EHT TB PPDU format.

[0113] The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated so that even legacy STAs can attempt demodulation and decoding, and can be mapped based on a predetermined subcarrier frequency interval (e.g., 312.5 kHz). These can be referred to as pre-EHT modulated fields. Next, the EHT-STF, EHT-LTF, Data, and PE fields can be encoded and modulated so that they can be demodulated and decoded by an STA that has successfully decoded a non-legacy SIG (e.g., U-SIG and / or EHT-SIG) and obtained the information contained in the corresponding field, and can be mapped based on a predetermined subcarrier frequency interval (e.g., 78.125 kHz). These can be referred to as EHT modulated fields.

[0114] Similarly, in the HE PPDU format, the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, and HE-SIG-B fields may be referred to as pre-HE modulation fields, and the HE-STF, HE-LTF, Data, and PE fields may be referred to as HE modulation fields. Additionally, in the VHT PPDU format, the L-STF, L-LTF, L-SIG, and VHT-SIG-A fields may be referred to as pre-VHT modulation fields, and the VHT STF, VHT-LTF, VHT-SIG-B, and Data fields may be referred to as VHT modulation fields.

[0115] The U-SIG included in the EHT PPDU format of FIG. 7 can be configured based on, for example, two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., OFDM symbol) for the U-SIG can have a duration of 4 us, and the U-SIG can have a total duration of 8 us. Each symbol of the U-SIG can be used to transmit 26 bits of information. For example, each symbol of the U-SIG can be transmitted and received based on 52 data tones and 4 pilot tones.

[0116] U-SIGs can be configured in 20MHz units. For example, when an 80MHz PPDU is configured, the same U-SIG can be duplicated in 20MHz units. That is, four identical U-SIGs can be included in an 80MHz PPDU. When the bandwidth exceeds 80MHz, for example, for a 160MHz PPDU, the U-SIGs in the first 80MHz unit and the U-SIGs in the second 80MHz unit can be different.

[0117] For example, A uncoded bits may be transmitted via U-SIG, and a first symbol of U-SIG (e.g., a U-SIG-1 symbol) may transmit the first X bits of information out of a total A bits of information, and a second symbol of U-SIG (e.g., a U-SIG-2 symbol) may transmit the remaining Y bits of information out of a total A bits of information. The A bits of information (e.g., 52 uncoded bits) may include a CRC field (e.g., a field of 4 bits in length) and a tail field (e.g., a field of 6 bits in length). The tail field may be used to terminate the trellis of the convolutional decoder and may be set to 0, for example.

[0118] The A bit information transmitted by U-SIG can be divided into version-independent bits and version-dependent bits. For example, U-SIG can be included in a new PPDU format (e.g., UHR PPDU format) not shown in FIG. 7, and in the format of the U-SIG field included in the EHT PPDU format and the format of the U-SIG field included in the UHR PPDU format, the version-independent bits can be the same, and some or all of the version-dependent bits can be different.

[0119] For example, the size of the version-independent bits of U-SIG can be fixed or variable. The version-independent bits can be assigned only to U-SIG-1 symbols, or to both U-SIG-1 symbols and U-SIG-2 symbols. The version-independent bits and the version-dependent bits can be called by various names, such as the first control bit and the second control bit.

[0120] For example, the version-independent bits of the U-SIG may include a 3-bit PHY version identifier, which may indicate the PHY version (e.g., EHT, UHR, etc.) of the transmitted and received PPDUs. The version-independent bits of the U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication. The version-independent bits of the U-SIG may include information about the length of a transmission opportunity (TXOP) and information about a BSS color ID.

[0121] For example, the version-dependent bits of the U-SIG may contain information that directly or indirectly indicates the type of PPDU (e.g., SU PPDU, MU PPDU, TB PPDU, etc.).

[0122] Information required for PPDU transmission and reception may be included in the U-SIG. For example, the U-SIG may further include information about bandwidth, information about the MCS technique applied to the non-legacy SIG (e.g., EHT-SIG or UHR-SIG), information indicating whether a dual carrier modulation (DCM) technique (e.g., a technique to achieve an effect similar to frequency diversity by reusing the same signal on two subcarriers) is applied to the non-legacy SIG, information about the number of symbols used for the non-legacy SIG, information about whether the non-legacy SIG is generated across the entire band, etc.

[0123] Some of the information required for transmitting and receiving a PPDU may be included in the U-SIG and / or the non-legacy SIG (e.g., EHT-SIG or UHR-SIG, etc.). For example, information about the type of the non-legacy LTF / STF (e.g., EHT-LTF / EHT-STF or UHR-LTF / UHR-STF, etc.), information about the length of the non-legacy LTF and the cyclic prefix (CP) length, information about the guard interval (GI) applicable to the non-legacy LTF, information about preamble puncturing applicable to the PPDU, information about resource unit (RU) allocation, etc. may be included only in the U-SIG, may be included only in the non-legacy SIG, or may be indicated by a combination of the information included in the U-SIG and the information included in the non-legacy SIG.

[0124] Preamble puncturing may refer to the transmission of a PPDU in which no signal is present in one or more frequency units within the PPDU's bandwidth. For example, the size of the frequency unit (or the resolution of the preamble puncturing) may be defined as 20 MHz, 40 MHz, etc. For example, preamble puncturing may be applied to a PPDU bandwidth greater than a certain size.

[0125] In the example of FIG. 7, non-legacy SIGs such as HE-SIG-B and EHT-SIG may include control information for the receiving STA. The non-legacy SIG may be transmitted over at least one symbol, and each symbol may have a length of 4 us. Information regarding the number of symbols used for the EHT-SIG may be included in a previous SIG (e.g., HE-SIG-A, U-SIG, etc.).

[0126] Non-legacy SIGs, such as HE-SIG-B and EHT-SIG, may contain common fields and user-specific fields. Common and user-specific fields may be coded separately.

[0127] In some cases, common fields may be omitted. For example, in a compressed mode where non-OFDMA (orthogonal frequency multiple access) is applied, common fields may be omitted, and multiple STAs may receive PPDUs (e.g., data fields of PPDUs) over the same frequency band. In a non-compressed mode where OFDMA is applied, multiple users may receive PPDUs (e.g., data fields of PPDUs) over different frequency bands.

[0128] The number of user-specific fields can be determined based on the number of users. A single user block field can contain up to two user fields. Each user field can be associated with either MU-MIMO allocation or non-MU-MIMO allocation.

[0129] The common field may include CRC bits and Tail bits, the length of the CRC bits may be determined as 4 bits, and the length of the Tail bits may be determined as 6 bits and set to 000000. The common field may include RU allocation information. The RU allocation information may include information about the location of RUs to which multiple users (i.e., multiple receiving STAs) are allocated.

[0130] An RU can contain multiple subcarriers (or tones). RUs can be used when transmitting signals to multiple STAs based on OFDMA techniques. RUs can also be defined when transmitting signals to a single STA. Resources can be allocated on an RU basis for non-legacy STFs, non-legacy LTFs, and data fields.

[0131] Depending on the PPDU bandwidth, an applicable RU size can be defined. The RU may be defined identically or differently for the applicable PPDU format (e.g., HE PPDU, EHT PPDU, UHR PPDU, etc.). For example, in the case of an 80MHz PPDU, the RU arrangements of HE PPDU and EHT PPDU may be different. The applicable RU size, RU number, RU position, DC (direct current) subcarrier position and number, null subcarrier position and number, guard subcarrier position and number, etc. for each PPDU bandwidth can be referred to as a tone plan. For example, a tone plan for a wide bandwidth can be defined in the form of multiple repetitions of a low bandwidth tone plan.

[0132] RUs of different sizes can be defined, such as 26-ton RU, 52-ton RU, 106-ton RU, 242-ton RU, 484-ton RU, 996-ton RU, 2X996-ton RU, 4X996-ton RU, etc. A multiple RU (MRU) is distinguished from multiple individual RUs and corresponds to a group of subcarriers consisting of multiple RUs. For example, one MRU can be defined as 52+26-tons, 106+26-tons, 484+242-tons, 996+484-tons, 996+484+242-tons, 2X996+484-tons, 3X996-tons, or 3X996+484-tons. Additionally, multiple RUs constituting one MRU may or may not be consecutive in the frequency domain.

[0133] The specific size of an RU may be reduced or expanded. Therefore, the specific size of each RU (i.e., the number of corresponding tones) in the present disclosure is not limited and is exemplary. Furthermore, within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, etc.) in the present disclosure, the number of RUs may vary depending on the RU size.

[0134] The names of each field in the PPDU formats of FIG. 7 are exemplary and the scope of the present disclosure is not limited by those names. Furthermore, the examples of the present disclosure can be applied not only to the PPDU format exemplified in FIG. 7, but also to a new PPDU format in which some fields are excluded and / or some fields are added based on the PPDU formats of FIG. 7.

[0135] Multi-Access Point (MAP) operation

[0136] Below, examples of the present disclosure for multi-access point (MAP) operation are described.

[0137] MAP operation can be defined as an operation between a master AP (or sharing AP) and a slave AP (or shared AP).

[0138] The master AP initiates and controls MAP operations for transmission and reception between multiple APs. It groups slave APs and manages links with them to enable information sharing. The master AP manages information about the BSS comprised of the slave APs and the STAs associated with that BSS.

[0139] Slave APs can associate with a master AP and share control information, management information, and data traffic. Slave APs perform the same basic functions as APs, establishing a base station service (BSS) in a wireless LAN.

[0140] In MAP operation, an STA can associate with a slave AP or a master AP and form a BSS.

[0141] In a MAP environment, the master AP and slave APs can directly transmit and receive with each other. The master AP and STA may not be able to directly transmit and receive with each other. A slave AP (e.g., a slave AP associated with an STA) can directly transmit and receive with the STA. One of the slave APs can become the master AP.

[0142] MAP operation is a technique in which one or more APs transmit and receive information to one or more STAs. For example, coordinated-time division multiple access (C-TDMA), which divides allocations between APs along the time axis, coordinated-orthogonal frequency division multiple access (C-OFDMA), which divides allocations along the frequency axis, and coordinated-spatial reuse (C-SR) techniques that utilize spatial reuse can be applied for MAP operation. Alternatively, coordinated beamforming (C-BF) or joint beamforming techniques, which cooperatively perform simultaneous transmission and reception, can also be applied to MAP operation.

[0143] FIG. 8 is a diagram for explaining various transmission and reception techniques in a MAP environment to which the present disclosure can be applied.

[0144] As in the conventional method, when a BSS AP transmits to a BSS STA, this can be referred to as STX (single transmission). STX suffers from the problem of reduced transmission and reception performance for users / STAs located at the cell edge due to interference with neighboring APs. For example, as shown in Figure 8(a), if AP1 and AP2 transmit to STA1 and STA2, respectively, at the same time and within the same frequency bandwidth, a collision may occur on the wireless medium.

[0145] In the MAP technique, performance can be improved by reducing inter-symbol interference (ISI) through cooperation between neighboring APs, or by performing joint transmissions. For example, in the C-OFDMA method of Fig. 8(b), interference can be avoided by simultaneously transmitting to STA1 in the first bandwidth and transmitting to STA2 in the second bandwidth. The example of Fig. 8(c) shows a cooperative beamforming or nulling technique in which AP1 nulls the interference to AP2 and / or STA2 while transmitting to STA1, and AP2 nulls the interference to AP1 and / or STA1 while transmitting to STA2. Fig. 8(d) shows an AP selection method in which an AP with a good channel condition among neighboring APs performs transmission. Joint transmission (JTX) or joint reception (JRX) may be applied, in which multiple APs cooperate to transmit or receive simultaneously, as in the example of Fig. 8(e), and further, joint MU-MIMO may be supported.

[0146] In the examples of this disclosure, multi-AP operation is assumed to be performed as follows.

[0147] Step 1: Allocate resource areas to each AP through a trigger frame from the master AP (i.e., AP-to-AP trigger frame, or master trigger frame).

[0148] Step 2: Each AP performs DL (i.e., from AP to STA) data transmission in the resource area allocated to it, or transmits a trigger frame (i.e., AP-to-STA trigger frame) for UL (i.e., from STA to AP) data transmission in the resource area allocated to it.

[0149] Step 3: STA sends a response to DL data or sends UL data (e.g., TB PPDU)

[0150] If the resources distributed between APs are frequency resources, it may correspond to the C-OFDMA method, if it is time resources, it may correspond to the C-TDMA technique, and if it is space resources (or beams), it may correspond to the CBF method. In the examples described below, it is assumed that the C-OFDMA technique, i.e., multi-AP operation is performed using resources distinguished in the frequency domain, is representative. However, the scope of the present disclosure is not limited thereto, and may additionally or alternatively include multi-AP operation using resources distinguished in other domains (e.g., time domain and / or space domain).

[0151] target wake time (TWT)

[0152] Below, we explain TWT (target wake time).

[0153] TWT is a power saving technology that can improve the energy efficiency of non-AP STAs by defining a service period (SP) between an AP and non-AP STAs and sharing information about the SP to reduce contention of the medium. In the TWT setup phase, an STA that performs requests / suggestions / demands, etc., can be called a TWT requesting STA. In addition, an AP that responds to the request with an acceptance / rejection, etc., can be called a TWT responding STA. The setup phase can include a process of determining / defining a TWT request from an STA to the AP, the type of TWT operation to be performed, and the type of frames to be transmitted and received. TWT operations can be divided into individual TWT and broadcast TWT.

[0154] FIG. 9 is a diagram illustrating an example of an individual TWT operation to which the present disclosure can be applied.

[0155] Individual TWT is a mechanism in which an AP and a non-AP STA negotiate the awake / doze status of a non-AP STA by sending and receiving TWT request / response frames, and then exchange data. In the example of Fig. 9, the AP and STA1 can form a trigger-enabled TWT agreement through a TWT request frame and a TWT response frame. Here, the method used by STA1 is a solicited TWT method, in which STA1 transmits a TWT request frame to the AP, and STA1 receives information for TWT operation from the AP through a TWT response frame. On the other hand, STA2, which performs the unsolicited TWT method, can receive information about the trigger-enabled TWT agreement setup from the AP through the 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 the AP has buffered data. In response, STA1 can inform the AP of its awake state by transmitting a PS-Poll frame. Additionally, STA2 can inform the AP of its activated state by transmitting a QoS Null frame. Here, the data frames transmitted by STA1 and STA2 can be frames in the TB PPDU format. The AP, which has checked the status of STA1 and STA2, can transmit DL MU PPDU to the activated STAs.When the corresponding TWT SP expires, STA1 and STA2 can enter doze state.

[0156] FIG. 10 is a diagram illustrating an example of a broadcast TWT operation to which the present disclosure can be applied.

[0157] Broadcast TWT is a TWT in which a non-AP STA (or TWT scheduling STA) obtains information such as target beacon transmission time (TBTT) and listen interval by transmitting and receiving TWT request / response frames with the AP (or TWT scheduled STA). Here, a negotiation operation for TBTT may be performed. Based on this, the AP can define a frame to include TWT scheduling information through a beacon frame. In Fig. 10, STA1 performs a requested TWT operation, and STA2 performs an unsolicited 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 the same as the process of an individual TWT. In broadcast TWT, a trigger-enabled TWT SP including a beacon frame may be repeated multiple times at a regular cycle.

[0158] Transmission of TWT information can be accomplished through a TWT information frame and a TWT information element.

[0159] With the recent explosion in wired and wireless traffic, latency-sensitive traffic has also increased significantly. Latency-sensitive traffic includes real-time audio / video transmission, and the proliferation of multimedia devices has increased the need to support this traffic in wireless environments. However, supporting latency-sensitive traffic in wireless environments requires more considerations than in wired environments. This is because wireless environments have lower transmission speeds and must also consider interference from surrounding environments. In particular, in WLAN systems, multiple STAs must compete equally for medium access in the Industry-Science-Medical (ISM) band, making it relatively more difficult to support latency-sensitive traffic compared to cellular communication networks, which rely on centralized radio resource scheduling. This disclosure describes a novel approach for supporting latency-sensitive traffic in WLAN systems.

[0160] In the present disclosure, latency may refer to latency defined in the 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 the transmitting STA, until the transmitting STA successfully completes transmission in the PHY layer, and the transmitting STA receives an ACK / block ACK, etc. from the receiving STA, and the corresponding frame is deleted from the MAC layer queue of the transmitting STA. In addition, in the present disclosure, a non-AP STA that supports transmission of latency-sensitive data may be referred to as a low latency STA. In addition, data other than latency-sensitive data may be referred to as regular data.

[0161] Restricted TWT (r-TWT) can support securing data transmission possibility for low-latency STAs transmitting latency-sensitive data preferentially over other STAs by having the AP set a special broadcast TWT for the low-latency STAs. The STAs can establish membership in one or more r-TWT schedules with respect to the AP. Here, the r-TWT agreement can be established by the same process as the broadcast TWT agreement, and the broadcast TWT element for this can be defined to include an r-TWT parameter set field. For example, the r-TWT parameter set can 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 can correspond to a special case of the broadcast TWT parameter set field. In addition, the AP can announce an r-TWT SP.

[0162] Basically, if another STA supporting r-TWT operation is a TXOP holder, the TXOP must end before the start time of the r-TWT SP advertised by the associated AP. Accordingly, the STA related to the r-TWT (i.e., the low-latency STA) can transmit and receive traffic with priority over the other STAs within the r-TWT SP.

[0163] In the present disclosure, a low-latency STA associated with a specific r-TWT, as described above, 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 an STA that has the capability to support r-TWT operation but is not a member of any r-TWT, or that supports r-TWT operation but is a member of another r-TWT, or that does not have the capability to support r-TWT operation.

[0164] An STA (e.g., a low-latency STA) that supports limited SP (or r-TWT SP) operation of broadcast TWT can inform the AP that it needs to transmit latency-sensitive data based on r-TWT operation. If the AP supports r-TWT operation / mode, the AP can transmit a frame containing scheduling information of TWTs requested by each STA to the low-latency STA and other STA(s). For example, in order to perform operation for r-TWT, non-AP STAs can obtain r-TWT related information from the AP through a beacon frame, a probe response frame, a (re)association response frame, or other frames in an undefined format (e.g., frames for broadcast, advertisement, or announcement purposes).

[0165] According to the restricted TWT operation, a separate TXOP (i.e., to which access of other STAs is restricted) can be secured within the r-TWT SP by 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 another STA (i.e., a non-member STA) other than the STA having the membership for the specific r-TWT schedule, it must be stopped. And the TXOP of the other STA (i.e., the non-member STA) can be additionally performed after the specific r-TWT SP ends.

[0166] OBSS R-TWT related announcement and protection

[0167] In a multi-BSS environment, when APs are located within a range where they can receive each other's beacon frames, an OBSS (overlapping BSS) range can be formed, which is a range where the transmission and reception ranges (i.e., BSS) of the APs overlap.

[0168] FIG. 11 is a diagram exemplarily showing APs and STAs in an OBSS to which the present disclosure can be applied.

[0169] As illustrated in FIG. 11, the signaling range of AP 1 (e.g., the range corresponding to BSS 1) and the signaling range of AP 2 (e.g., the range corresponding to BSS 2) may overlap. In this way, when AP 1 and AP 2 are located within a range where they can receive (i.e., overhear) each other, AP 1 and AP 2 can negotiate for coordination for their own scheduled R-TWT SPs (service periods) via (wireless / wired) communication. This case corresponds to a case where AP 1 and AP 2 are located within the range of an OBSS where their transmission and reception ranges overlap, unlike the case where AP 1 and AP 2 are hidden nodes.

[0170] In this regard, STAs located within the overlapping range can receive beacon frames from APs with which they are associated as well as beacon frames from APs with which they are not associated. For example, STA 1-2 can receive a beacon frame from AP 1 with which it is associated, and can also receive (i.e., overhear) a beacon frame from AP 2 with which it is not associated. For example, STA2-3 can receive a beacon frame from AP 2 with which it is associated, and can also receive (i.e., overhear) a beacon frame from AP 1 with which it is not associated.

[0171] At this time, AP 1 and AP 2 may be slave APs (or shared APs) belonging to a MAP that has the same master AP (or shared AP). Furthermore, either AP 1 or AP 2 may be the master AP (or shared AP). Furthermore, AP 1 and AP 2 belong to the same MAP.

[0172] A beacon frame may contain restricted-TWT (R-TWT) scheduling information that an AP assigns to STAs associated with it, and STAs receiving the R-TWT scheduling information are required to protect R-TWT SPs of which they are not a member (e.g., terminating a TXOP of the STA if it is in progress before the start time of the R-TWT SP, as described above). That is, an STA receiving a beacon frame including R-TWT scheduling information may mean that it is in a position to protect the corresponding R-TWT SP. On the other hand, it is not yet defined whether an STA should protect the corresponding R-TWT SP or transmit / receive low-latency traffic / data during the corresponding R-TWT SP when it receives R-TWT scheduling information advertised by an AP to which it is not associated (or a neighboring AP).

[0173] The present disclosure describes a method for an associated AP (e.g., AP 1) to notify associated STAs of R-TWT scheduling information of an unassociated (or neighboring) AP (e.g., AP 2) and a protection method based thereon. In the following description, an R-TWT SP scheduled by another AP (e.g., an unassociated AP or a neighboring AP) is referred to as an OBSS R-TWT SP to distinguish it from an R-TWT SP scheduled by the associated AP. The scope of the present disclosure is not limited by the name OBSS R-TWT.

[0174] Example 1

[0175] This embodiment is about a method for distinguishing between coordinated R-TWT and non-coordinated R-TWT.

[0176] First, cooperative R-TWT and non-cooperative R-TWT can be distinguished based on the results of (wireless / wired-based) negotiation for coordination between non-coordinated (or neighboring) APs.

[0177] The negotiation process for cooperation between an associated AP (e.g., AP 1) and a non-associated (or neighboring) AP (e.g., AP 2) can be performed in a 2-way manner.

[0178] - Step 1. An associated AP can send a coordination request to an unassociated (or neighboring) AP.

[0179] - Step 2. The unassociated (or neighboring) AP that received the cooperation request can send a coordination response to the AP that sent it, i.e., the associated AP.

[0180] During the aforementioned negotiation process, if the cooperation response in Step 2 includes information indicating "Accept (or Success)", the cooperation can be interpreted as having been successfully established. In this case, the R-TWT SP targeted for negotiation can be considered a cooperative R-TWT SP among the APs participating in the negotiation.

[0181] Alternatively, if the cooperation response in step 2 includes information indicating "Reject (or Failure)", the associated AP may retransmit a cooperation request to the non-associated (or neighboring) AP. The retransmitted cooperation request may include the same information about the R-TWT SP included in the previously transmitted cooperation request (e.g., the cooperation request transmitted in step 1), or may include some or all changed information. If the last cooperation response received from the non-associated (or neighboring) AP during the negotiation includes information indicating "Reject (or Failure)", the cooperation may be interpreted as being rejected (or failed). In this case, the R-TWT SP that is the target of the negotiation may be regarded as a non-cooperating R-TWT SP among the APs that participated in the negotiation. In this regard, non-cooperative R-TWT SPs may collectively refer to R-TWT SPs whose cooperation has failed through the negotiation process between APs and R-TWT SPs that are not targeted (i.e., not included) in the negotiation process for cooperation.

[0182] Next, in addition to the aforementioned negotiation process, cooperative R-TWT and non-cooperative R-TWT can be distinguished based on one or more of the following additional methods.

[0183] For example, if a third-party management entity (e.g., a central entity) exists, the third-party management entity can manage / assign scheduling of APs and share scheduling information of APs with the APs. For example, a master AP can act as the third-party management entity. In this case, if the third-party management entity assigns an R-TWT SP to each AP and shares the R-TWT-related scheduling information with other APs, the R-TWT SP can be regarded as a cooperative R-TWT SP between the APs.

[0184] For another example, if an associated AP obtains information about an OBSS R-TWT SP by receiving (i.e., overhearing) a beacon frame transmitted by a non-associated (or neighboring) AP, the OBSS R-TWT SP may be considered a non-cooperative R-TWT SP. In this regard, the associated AP may schedule an R-TWT SP based on the OBSS R-TWT SP obtained through the beacon frame that it received (i.e., overheard). As an example, the associated AP may allocate and announce an R-TWT SP to its associated STAs so as not to overlap with the OBSS R-TWT SP.

[0185] As another example, information about OBSS R-TWT SPs can be obtained by receiving (i.e., overhearing) a beacon frame transmitted by an unassociated (or neighboring) AP to which the STA is not associated.

[0186] In this case, the STA may notify the associated AP of information about the corresponding OBSS R-TWT SP. At this time, the corresponding OBSS R-TWT SP may be considered a non-cooperative R-TWT SP. In this regard, the associated AP may schedule / allocate the R-TWT SP based on the OBSS R-TWT SP shared / announced from the STA. For example, the associated AP may allocate and announce the R-TWT SP to its associated STAs so as not to overlap with the corresponding OBSS R-TWT SP.

[0187] Additionally or alternatively, in this case, based on the information about the acquired OBSS R-TWT SP, the STA can transmit a TWT request to the associated AP, which includes information about a time (e.g., SP) that does not overlap with the corresponding OBSS R-TWT SP. This method has the effect of reducing overhead that may occur by transmitting information about (a large number of) OBSS R-TWT SPs to the associated AP. This method can be efficient when direct data transmission is not possible between APs, when direct data transmission is possible between APs but cooperation cannot proceed, or when direct cooperation between APs cannot proceed.

[0188] In relation to the aforementioned TWT request-based approach, the STA may transmit a TWT request (via a TWT setup frame) that includes a new field indicating a non-overlapping time (e.g., SP) based on information about the OBSS R-TWT SP. The field may be indicated using a reserved bit in the TWT element.

[0189] For example, a new field (e.g., an OBSS non-overlapping SP field) with a length of 1 bit can be defined by utilizing reserved bits within a control field included in a TWT element. Depending on the value of that field, whether (all) of the request times (e.g., SPs) included in a TWT request overlap with an OBSS R-TWT SP can be indicated.

[0190] As another example, a new field (e.g., an overlapping R-TWT SP field) may be additionally configured in the information configuration of the cooperative R-TWT illustrated in FIG. 15 described below. As a specific example, the new field may be included as a new field in the broadcast TWT parameter set field within the TWT element, or may be included in a new element subsequent to the TWT element within the TWT setup frame. In this case, by indicating that the R-TWT SP corresponding to the broadcast TWT ID included in the information configuration is a non-cooperative R-TWT SP and a non-overlapping R-TWT SP, information on times (e.g., SPs) that do not overlap with the corresponding OBSS R-TWT SP may be included / indicated.

[0191] In this regard, the combined AP can recognize that the requested times (e.g., SPs) do not overlap with the OBSS R-TWT SPs through the values ​​of the aforementioned new fields (e.g., OBSS non-overlapping R-TWT SP field, overlapping R-TWT SP field). Based on this, the combined AP can allocate and notify (R-)TWT SPs to the STA combined with it based on information about the requested times (e.g., SPs) included in the TWT request of the STA. Through this, other STAs can also participate in the R-TWT as members.

[0192] Hereinafter, STA operation and AP operation considering the aforementioned method will be described with reference to FIGS. 12 and 13. In FIGS. 12 and 13, it is assumed that the first AP corresponds to an AP to which an STA is associated, and the second AP corresponds to an AP to which an STA is not associated (or a neighboring AP).

[0193] FIG. 12 illustrates an example of STA operation according to the present disclosure.

[0194] An STA associated with a first AP of a first BSS can receive (i.e., overhear) a frame transmitted from a second AP of a second BSS (S1210).

[0195] In this regard, it may be assumed that the STA is located in an OBSS area where the first BSS and the second BSS overlap.

[0196] At this time, if the frame includes information about an R-TWT SP scheduled by a second AP, the STA may determine / verify one or more time intervals that do not overlap with the R-TWT SP. Based on this, the STA may transmit information about the one or more time intervals (e.g., SPs) to the first AP associated with it (S1220).

[0197] Thereafter, the STA may receive (or be notified of) scheduling information based on information about one or more time intervals from the first AP (S1230). For example, the scheduling information may include information about a TWT SP allocated and notified to the STA or information about an R-TWT SP.

[0198] In this regard, information about one or more of the aforementioned time intervals may be transmitted by being included in a TWT element within a TWT setup frame for a TWT request. In this case, information regarding whether there is an overlap with an R-TWT SP may be included in a control field included in the TWT element within the corresponding TWT setup frame.

[0199] Alternatively, information related to whether there is overlap with the R-TWT SP may be included in a broadcast TWT parameter set field included in a TWT element within the corresponding TWT setup frame. In this case, the information related to whether there is overlap with the R-TWT SP may be configured together with at least one of a first field indicating whether there is cooperation between APs for the R-TWT SP, a second field indicating a BSS color value of an AP that scheduled the R-TWT SP, a third field indicating whether there is a protection operation for the R-TWT SP, or a fourth field indicating a broadcast TWT ID corresponding to the R-TWT SP within the broadcast TWT parameter set field (e.g., see the information configuration of FIG. 15).

[0200] Alternatively, information regarding whether there is an overlap with the R-TWT SP may be included in an element subsequent to the TWT element within the TWT setup frame.

[0201] Additionally, the R-TWT SP scheduled by the second AP that is received / overheard by the STA may be considered as an R-TWT SP that is not coordinated between the first AP and the second AP.

[0202] The method described in the example of FIG. 12 may be performed by the first device (100) of FIG. 1. For example, one or more processors (102) of the first device (100) of FIG. 1 may be configured to receive a frame transmitted from a second AP of a second BSS, transmit information about one or more time intervals that do not overlap with the R-TWT SP to the first AP via one or more transceivers, and receive scheduling information for the first device based on the information about the one or more time intervals from the first AP via one or more transceivers. Furthermore, one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 12 or the examples described below when executed by one or more processors (102).

[0203] FIG. 13 illustrates another example of the first AP operation according to the present disclosure.

[0204] A first AP of a first BSS can receive information about one or more time intervals that do not overlap with an R-TWT SP scheduled by a second AP of a second BSS from an STA associated with the first AP (S1310).

[0205] In this regard, it may be assumed that the STA is located in an OBSS area where the first BSS and the second BSS overlap.

[0206] Thereafter, the first AP may allocate and announce scheduling information for the corresponding STA based on information about one or more time intervals (S1320). For example, the scheduling information may include information about a TWT SP or an R-TWT SP that is allocated and announced to the STA.

[0207] In the example of Fig. 13, the specific description of information on one or more time intervals that do not overlap with the R-TWT SP scheduled by the second AP, scheduling information for the corresponding SRQ based thereon, etc. is the same as the example of Fig. 12, so the overlapping description is omitted.

[0208] The method described in the example of FIG. 13 may be performed by the second device (200) of FIG. 1. For example, one or more processors (202) of the second device (200) of FIG. 1 may be configured to receive, from a first device coupled with the second device, information about one or more time intervals that do not overlap with an R-TWT SP scheduled by a second AP of a second BSS, via one or more transceivers, and to allocate scheduling information for the STA based on the information about the one or more time intervals and notify the first device of the scheduling information via the one or more transceivers. Furthermore, one or more memories (204) of the second device (200) may store commands for performing the method described in the example of FIG. 13 or the examples described below when executed by one or more processors (202).

[0209] The examples in FIGS. 12 and 13 may correspond to some of the various examples of the present disclosure.

[0210] Example 2

[0211] The present embodiment relates to a method and a protection method for a combined AP to notify STAs associated with it of information about a cooperative R-TWT SP, for a cooperative R-TWT distinguished through the aforementioned method(s).

[0212] In this regard, the form of cooperative R-TWT SP can be classified into overlapped cooperative R-TWT SP, in which R-TWT SP and OBSS R-TWT SP overlap, and non-overlapped cooperative R-TWT SP, in which R-TWT SP and OBSS R-TWT SP do not overlap. In the case of non-overlapped cooperative R-TWT SP, R-TWT SP and OBSS R-TWT SP do not overlap in the time domain and can be located forward / backward.

[0213] Below, we propose a method for a combined AP to announce each of its cooperating R-TWT SPs (e.g., R-TWT SP, OBSS R-TWT SP) and a method for the combined STA(s) to protect it.

[0214] Example 2-1

[0215] First, for the case of overlapped cooperative R-TWT SPs, a notification method by an AP for cooperative R-TWT SP(s) and a protection method by an STA based thereon are described.

[0216] For overlapping cooperative R-TWT SPs, since the R-TWT SPs are scheduled by APs to overlap (e.g., overlapping cooperative R-TWT SPs and cooperative OBSS R-TWT SPs), the corresponding R-TWT SPs may have values ​​of the same or similar TWT parameter set. For example, the values ​​of the TWT field in the broadcast TWT element may be the same, but the TWT interval or duration values ​​of the TWT SP may be the same or different.

[0217] During an overlapping cooperative R-TWT SP, APs can transmit and receive data by utilizing / operating an AP coordination scheme (e.g., C-TDMA, C-OFDMA, C-SR, etc.). For example, with respect to the AP coordination scheme operated during the SP, an associated AP with an overlapping cooperative R-TWT SP and a non-associated (or neighboring) AP can share information indicating the same AP coordination scheme and information for operating the AP coordination scheme during the process of negotiating in advance to cooperate with the R-TWT SP. Based on the information, the associated AP and the non-associated (or neighboring) AP can operate the same AP coordination scheme during the SP to transmit and receive low-latency traffic.

[0218] When a combined AP announces information about an overlapping cooperative R-TWT SP to its associated STAs, the AP may announce only information corresponding to the overlapping cooperative R-TWT SP scheduled by the AP. In other words, when a combined AP announces information to its associated STAs, the AP may announce information related to the overlapping cooperative R-TWT SP as an SP of the BSS to which it belongs.

[0219] Based on the above-described notice, an STA that has received the notice can perform the following R-TWT protection actions.

[0220] FIG. 14 illustrates STA operation for an overlapping cooperative R-TWT SP according to the present disclosure.

[0221] As illustrated in FIG. 14, the STA terminates its TXOP before the start time of the upcoming R-TWT SP based on the R-TWT scheduling information transmitted by the AP to which it is associated.

[0222] For example, if an overlapping cooperative R-TWT SP is scheduled by AP 1 and AP 2, the STA associated with AP 1 and the STA associated with AP 2 must act to terminate their own TXOPs prior to the overlapping cooperative R-TWT SP.

[0223] In this regard, it is assumed that the STA coupled to AP 1 and the STA coupled to AP 2 are not members of the corresponding overlapping cooperative R-TWT, or are STAs that do not support R-TWT (e.g., an STA that does not support R-TWT operation itself as a type that supports a wireless LAN technology for which the R-TWT capability itself is not defined, an STA that supports a wireless LAN technology for which the R-TWT capability is defined but does not have an R-TWT capability for the corresponding overlapping cooperative R-TWT, etc.). However, the scope of the present disclosure is not limited thereto. For example, an exception rule, etc. may be applied to a specific STA.

[0224] Example 2-2

[0225] Next, for the non-overlapped cooperative R-TWT SP case, a notification method for cooperative R-TWT SP(s) and a protection method based thereon are described.

[0226] Non-overlapping cooperative R-TWT SPs correspond to R-TWT SPs that are scheduled so that they do not overlap with each other in the time domain between APs. For example, if there are cooperative R-TWT SPs scheduled by an associated AP and cooperative OBSS R-TWT SPs scheduled by non-associated (or neighboring) APs, and there is no overlap between them, then each R-TWT SP corresponds to a non-overlapping cooperative R-TWT SP. In this case, unlike the case of overlapping cooperative R-TWT SPs, each R-TWT SP can have a different set of TWT parameters.

[0227] During a non-overlapping cooperative R-TWT SP, APs can transmit and receive data without utilizing an AP coordination scheme (e.g., C-TDMA, C-OFDMA, C-SR, etc.). However, if information indicating the same AP coordination scheme and information for operating the AP coordination scheme are shared between APs during the negotiation process for cooperating on the R-TWT SP in advance, based on the information, APs (e.g., an associated AP and a non-associated (or neighboring) AP) can utilize the same AP coordination scheme to transmit and receive low-latency traffic during the R-TWT SP.

[0228] When an associated AP announces information about non-overlapping cooperative R-TWT SPs to its associated STAs, the AP may announce not only information about non-overlapping cooperative R-TWT SPs scheduled by the AP itself, but also information about non-overlapping cooperative OBSS R-TWT SPs scheduled by non-associated (or neighboring) APs.

[0229] In this regard, scheduling information for non-overlapping cooperative R-TWT SPs of non-associated (or neighboring) APs, i.e., non-overlapping cooperative OBSS R-TWT SPs, may be included as at least one piece of information within a TWT element. That is, the non-overlapping cooperative R-TWT SPs and the non-overlapping cooperative OBSS R-TWT SPs may each be included within a TWT element as individual broadcast TWT parameter sets.

[0230] Additionally, in this regard, collaborative R-TWT information such as that in FIG. 15 can be additionally defined / configured / transmitted.

[0231] Figure 15 illustrates the configuration of cooperative R-TWT information according to the present disclosure.

[0232] Referring to FIG. 15, the cooperative R-TWT information may be configured to include a cooperative R-TWT field, a BSS color field, a protection recommendation field, and a broadcast TWT ID field. Additionally, as described above, the cooperative R-TWT information may further include an overlapping cooperative R-TWT SP field related to whether it overlaps with another cooperative R-TWT SP.

[0233] The fields included in the corresponding collaborative R-TWT information may be defined as new fields by extending the Broadcast TWT Parameter Set field within the TWT element, or fields of new elements may also be defined. For example, the new element may be included / positioned subsequent to the TWT element within the TWT setup frame.

[0234] The cooperative R-TWT field may indicate whether the AP performing the announcement (i.e., the associated AP) corresponds to an R-TWT SP with which cooperation negotiation has been successfully completed. For example, the field may be 1-bit long, in which case a value of 1 may be defined to indicate a cooperative R-TWT SP, and a value of 0 may be defined to indicate a non-cooperative R-TWT SP. Additionally, the field may be extended and used to distinguish between cooperative R-TWT SPs and non-cooperative R-TWT SPs as described above in the present disclosure, considering the case where there is a third entity managing the APs.

[0235] The BSS Color field may indicate the BSS color of the AP scheduling the corresponding R-TWT SP. For example, the field may be 6 bits long and set to indicate a BSS color value.

[0236] The Protection Recommendation field may indicate whether the associated STA(s) should perform protection actions for the corresponding R-TWT SP. The Protection Recommendation field may have an indication value indicating whether the STA should follow the protection rules for the corresponding R-TWT SP in a mandatory or conditional mandatory (or optional) manner.

[0237] For example, if the value is 0, the STA is required to stop its TXOP before the start of the corresponding R-TWT SP. Conversely, if the value is 1 or higher, this may indicate that the STA is required to conditionally comply with the protection rules for the corresponding R-TWT SP based on other information. The other information may be information from another layer (e.g., PHY layer) for the STA.

[0238] As a specific example, the information may include a BSS color value of the U-SIG field that allows the PPDU to be determined to be from an AP other than the associated AP (i.e., an unassociated, neighboring, or OBSS AP), a threshold level value including the reception strength of data received from the unassociated (or neighboring) AP, a value for spatial reuse, etc. As an example, the threshold level value may be a PD level of -82 dBm, an ED level of -62 dBm, or a threshold level value between a specific range defined in the system, and may be announced via a beacon, etc. Also, as an example, the value for spatial reuse may be a value of a UL spatial reuse subfield indicated in a common Info field of a trigger frame.

[0239] The Broadcast TWT ID may refer to the Broadcast TWT ID in the TWT element corresponding to the corresponding R-TWT SP. Through this value, the STA can identify scheduling information for the corresponding R-TWT (i.e., the corresponding cooperating R-TWT).

[0240] Based on the above-described notice, an STA that has received the notice can perform the following R-TWT protection actions.

[0241] Specifically, based on the information transmitted / announced by the associated AP, the STA performs an R-TWT SP protection operation for a non-overlapping cooperative R-TWT SP scheduled by the associated AP, and may also perform an R-TWT SP protection operation for a non-overlapping cooperative R-TWT SP scheduled by a non-associated (or neighboring) AP (i.e., a non-overlapping cooperative OBSS R-TWT SP).

[0242] For example, an STA terminates its TXOP before the start time of a non-overlapping cooperative R-TWT SP scheduled (or assigned) by an associated AP. Additionally, based on the value of the Protection Recommendation field conveyed by the associated AP, an STA may or may not terminate its TXOP before the start time of a non-overlapping cooperative R-TWT SP (i.e., a non-overlapping cooperative OBSS R-TWT SP) scheduled (or assigned) by an unassociated (or neighboring) AP.

[0243] FIG. 16 illustrates an example of STA operation for a non-overlapping cooperative R-TWT SP according to the present disclosure.

[0244] In FIG. 16, as described above, it is explained assuming that the STA receives information about a non-overlapping cooperative R-TWT SP scheduled by AP 1 and information about a non-overlapping cooperative R-TWT SP scheduled by AP 2 from the AP associated with it.

[0245] For example, an STA associated with AP 1 follows the protection rule for a non-overlapping cooperative R-TWT SP scheduled by AP 1. That is, the STA terminates its TXOP before the start time of the non-overlapping cooperative R-TWT SP scheduled by AP 1. However, for a non-overlapping cooperative R-TWT SP scheduled by AP 2, the STA may or may not terminate its TXOP based on the value of the protection recommendation field indicated by AP 1.

[0246] Similarly, an STA associated with AP 2 follows the protection rule for a non-overlapping cooperative R-TWT SP scheduled by AP 2. That is, the STA terminates its TXOP before the start time of a non-overlapping cooperative R-TWT SP scheduled by AP 2. However, for a non-overlapping cooperative R-TWT SP scheduled by AP 1, the STA may or may not terminate its TXOP based on the value of the protection recommendation field indicated by AP 2.

[0247] In this regard, it is assumed that the STA coupled to AP 1 and the STA coupled to AP 2 are not members of the corresponding overlapping cooperative R-TWT, or are STAs that do not support R-TWT (e.g., STAs that do not support R-TWT operation itself as a type that supports a wireless LAN technology for which the R-TWT capability itself is not defined, STAs that support a wireless LAN technology for which the R-TWT capability is defined but do not have R-TWT capability for the corresponding overlapping cooperative R-TWT, etc.). However, the scope of the present disclosure is not limited thereto. For example, an exception rule, etc. may be applied to a specific STA. In addition, it is assumed that the STA coupled to AP 1 and the STA coupled to AP 2 are STAs that support enhanced R-TWT (or OBSS R-TWT) defined in a new wireless LAN technology (e.g., next-EHT or UHR technology) (e.g., next-EHT or UHR STAs), but is not limited thereto. For example, exception rules may apply to specific STAs.

[0248] Additionally, when an AP announces information about a non-overlapping cooperative R-TWT SP to its associated STAs, there may be cases where the AP does not include separate information about a non-overlapping cooperative OBSS R-TWT SP, or where the STAs are unable to interpret (or decode) such information even if such separate information is included.

[0249] Figure 17 describes the STA operation in the aforementioned case. For clarity of explanation, an R-TWT including features related to R-TWT defined in a new wireless LAN technology (e.g., next-EHT or UHR technology) is referred to as an enhanced R-TWT (or OBSS R-TWT).

[0250] FIG. 17 illustrates another example of STA operation for a non-overlapping cooperative R-TWT SP according to the present disclosure.

[0251] Referring to FIG. 17, it is assumed, but not limited to, that the STA coupled to AP 1 and the STA coupled to AP 2 are STAs that do not support the enhanced R-TWT (or OBSS R-TWT) and only support R-TWT defined in existing wireless LAN technologies (e.g., EHT technology). For example, the STAs may be STAs of the EHT STA type that have the R-TWT capability, or STAs of the UHR STA type that do not have the enhanced R-TWT (or OBSS R-TWT) capability and only have the R-TWT capability.

[0252] In this regard, the STAs cannot recognize separate information about the non-overlapping cooperative OBSS R-TWT announced / forwarded by the associated AP. Therefore, the STA associated with AP 1 terminates its TXOP before the start time of the non-overlapping cooperative R-TWT SP scheduled by AP 1 and the non-overlapping cooperative R-TWT SP scheduled by AP 2. In addition, the STA associated with AP 2 terminates its TXOP before the start time of the non-overlapping cooperative R-TWT SP scheduled by AP 1 and the non-overlapping cooperative R-TWT SP scheduled by AP 2.

[0253] In this regard, it is assumed that the STA coupled to AP 1 and the STA coupled to AP 2 are not members of the corresponding overlapping cooperative R-TWT, or are STAs that do not support R-TWT (e.g., STAs that do not support R-TWT operation themselves as they are of a type that supports a wireless LAN technology for which the R-TWT capability itself is not defined, STAs that support a wireless LAN technology for which the R-TWT capability is defined but do not have the R-TWT capability for the corresponding overlapping cooperative R-TWT, etc.).

[0254] Additionally, when an AP notifies information about a non-cooperative R-TWT SP to associated STAs based on the methods for notifying information about a cooperative R-TWT SP described above in the present disclosure, the associated STAs can perform a protection operation for the non-cooperative R-TWT SP.

[0255] FIG. 18 illustrates the operation of an AP performing an announcement to a cooperative R-TWT SP and / or a cooperative OBSS R-TWT SP according to the present disclosure.

[0256] The present disclosure describes a method for an AP to notify its associated STA(s) of information about its coordinated R-TWT and OBSS R-TWT with a non-associated (or neighboring) AP.

[0257] Referring to FIG. 18, the AP can check whether the corresponding cooperative R-TWT SP overlaps with the cooperative OBSS R-TWT SP (S1810). For example, the AP can check whether the cooperative OBSS R-TWT SP is configured with the same or similar TWT parameters (i.e., a TWT parameter set) as the cooperative R-TWT SP.

[0258] If the cooperative R-TWT SP and the cooperative OBSS R-TWT SP overlap, the AP may notify the combined STA(s) of only the information corresponding to the cooperative R-TWT SP, excluding the cooperative OBSS R-TWT SP (S1820).

[0259] In contrast, if the cooperative R-TWT SP and the cooperative OBSS R-TWT SP do not overlap, the AP may notify the associated STA(s) of the information corresponding to the cooperative R-TWT SP and the cooperative OBSS R-TWT SP, as well as additional information related to the cooperative OBSS R-TWT SP (S1830).

[0260] In this regard, information notified / shared to STA(s) associated with the AP, i.e., information regarding overlapping cooperative R-TWT SP, overlapping cooperative OBSS R-TWT SP, and / or non-cooperative (OBSS) R-TWT SP, may be based on the description in the present disclosure described above.

[0261] Although Fig. 18 is described based on a cooperative R-TWT SP, the AP can also notify the associated STA(s) of information about a non-cooperative R-TWT SP with an unassociated (or neighboring) AP, so the operation described in Fig. 18 can be extended and applied to this as well.

[0262] FIG. 19 illustrates the operation of an STA for a known R-TWT SP according to the present disclosure.

[0263] Referring to FIG. 19, a STA may receive an announcement from an associated AP that includes information about an R-TWT SP scheduled by the associated AP and / or an R-TWT SP scheduled by a non-associated (or neighboring) AP (i.e., an OBSS R-TWT SP).

[0264] In this regard, the STA can determine whether the R-TWT SP to which the protection rule is to be applied corresponds to the R-TWT SP notified from the combined AP (S1910).

[0265] For example, if it is not an R-TWT SP notified from an associated AP, it corresponds to the case where the STA obtains an OBSS R-TWT SP by receiving (i.e., overhearing) a beacon frame transmitted by an unassociated (or neighboring) AP. In this case, the STA may not follow the protection rule for the R-TWT SP (i.e., the OBSS R-TWT SP) (S1920). That is, the STA may not terminate its TXOP before the start time of the R-TWT SP.

[0266] Alternatively, if the R-TWT SP (or OBSS R-TWT SP) is notified by a combined AP, the STA may be configured / defined to follow protection rules for the SP. At this time, the STA may determine whether there is information on protection recommendations related to the application of protection rules for a specific R-TWT SP (S1930). Here, information on protection recommendations may be indicated by the combined AP.

[0267] If information about protection recommendation is not indicated for the corresponding R-TWT SP, the STA may transmit and receive data during the R-TWT SP based on the information received from the associated AP, or perform operations according to the protection rules (S1940). Conversely, if information about protection recommendation is indicated for the corresponding R-TWT SP, the STA may perform operations according to the protection rules for the corresponding R-TWT SP based on the information about protection recommendation, or may ignore the information (S1950).

[0268] The STA operation in FIG. 19 may be an STA operation applicable to the cooperative (OBSS) R-TWT SP, the non-cooperative (OBSS) R-TWT SP, the overlapping (OBSS) R-TWT SP, the non-overlapping (OBSS) R-TWW SP, and / or the combined (OBSS) R-TWT SP therebetween, as described above in the present disclosure.

[0269] Hereinafter, STA operation and AP operation considering the aforementioned method will be described with reference to FIGS. 20 and 21. In FIGS. 20 and 21, the description is made assuming that the first AP corresponds to an AP to which an STA is associated, and the second AP corresponds to an AP to which an STA is not associated (or a neighboring AP). In this regard, it is assumed that the first AP and the second AP belong to different BSSs.

[0270] FIG. 20 illustrates another example of STA operation according to the present disclosure.

[0271] The STA can receive a frame including an announcement related to the R-TWT SP from the associated first AP (S2010).

[0272] Thereafter, the STA can perform a relevant action for the R-TWT SP (e.g., an action according to a protection rule, an action that ignores a protection rule, a data transmission / reception action, etc.) based on the information included in the notice (S2020).

[0273] In this regard, if a first R-TWT SP scheduled by a first AP and a second R-TWT SP scheduled by a second AP to which an STA is not associated do not overlap in the time domain, the announcement may include both information related to the first R-TWT SP and information related to the second R-TWT SP. Conversely, if a first R-TWT SP scheduled by a first AP and a second R-TWT SP scheduled by a second AP to which an STA is not associated overlap in the time domain, the announcement may include only information related to the first R-TWT SP.

[0274] At this time, when information about the second R-TWT SP is notified to the STA, the notification may include scheduling information about the second R-TWT SP and related additional information. At this time, the additional information may be included as a field in the broadcast parameter set field in the TWT element for the second R-TWT SP within the frame, or may be included in an element subsequent to the TWT element for the second R-TWT SP.

[0275] For example, the additional information may include information indicating whether cooperation for a second R-TWT SP is achieved between the first AP and the second AP. Here, whether cooperation for the second R-TWT SP is achieved may be based on whether negotiation between the first AP and the second AP is successfully completed, or whether the second R-TWT SP is allocated by an entity managing the first AP and the second AP.

[0276] Additionally or alternatively, the additional information may include indication information (e.g., a protection recommendation field) indicating whether to follow a protection rule that terminates its own transmission opportunity (TXOP) before the start of the second R-TWT SP. Specifically, setting the indication information to a specific value (e.g., 0) may indicate mandatory compliance with the protection rule for the second R-TWT SP, and setting the indication information to a value other than the specific value may indicate conditional compliance with the protection rule for the second R-TWT SP. In this regard, when the indication information is set to a value other than the specific value, the STA may be configured to determine whether to follow the protection rule based on other information (e.g., PHY information, etc.). As a specific example, the other information may include one or more of a BSS color value in a U-SIG field, a threshold value for the reception strength of data received from the second AP, or a spatial reuse-related value.

[0277] Additionally or alternatively, the additional information may include information indicating a BSS color value of the AP scheduling the second R-TWT SP.

[0278] Additionally or alternatively, the additional information may include information indicating a broadcast TWT ID within a TWT element corresponding to the second R-TWT SP.

[0279] The method described in the example of FIG. 20 may be performed by the first device (100) of FIG. 1. For example, one or more processors (102) of the first device (100) of FIG. 1 may be configured to receive, from the associated first AP, a frame including an announcement related to a restricted-TWT (R-TWT) service period (SP) via one or more transceivers, and to perform a related operation for the R-TWT SP. Furthermore, one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 20 or the examples described below when executed by one or more processors (102).

[0280] FIG. 21 illustrates another example of the first AP operation according to the present disclosure.

[0281] The first AP can obtain information about an R-TWT SP scheduled by a second AP belonging to a second BSS different from the first BSS to which it belongs (S2110).

[0282] Thereafter, the first AP can determine whether there is overlap between the R-TWT SP scheduled by itself and the R-TWT SP scheduled by the second AP (S2120).

[0283] At this time, if the R-TWT SP scheduled by the first AP and the R-TWT SP scheduled by the second AP do not overlap in the time domain, the first AP can transmit a frame to notify both information related to the R-TWT SP scheduled by the first AP and information related to the R-TWT SP scheduled by the second AP (S2130).

[0284] In the example of Fig. 21, the specific description of the information included in the frame and announced, i.e., information related to the R-TWT SP scheduled by the first AP, information related to the R-TWT SP scheduled by the second AP, etc., is the same as the example of Fig. 20, so redundant description is omitted.

[0285] The method described in the example of FIG. 21 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 be configured to obtain information about a restricted-TWT (R-TWT) service period (SP) scheduled by a second AP belonging to a second BSS different from a first BSS to which the first AP belongs, through one or more transceivers, determine whether the R-TWT SP by the second AP overlaps with the R-TWT SP scheduled by the first AP, and announce information related to the R-TWT SP scheduled by the first AP and / or information related to the R-TWT SP scheduled by the second AP based on whether there is overlap, through one or more transceivers. Furthermore, one or more memories (204) of the second device (200) may store instructions for performing the method described in the example of FIG. 21 or the examples described below when executed by one or more processors (202).

[0286] The examples in FIGS. 20 and 21 may correspond to some of the various examples of the present disclosure.

[0287] Unlike the method of protecting the R-TWT SP based on R-TWT related scheduling information announced by the associated AP in the existing wireless LAN system, the method of protecting the R-TWT SP according to the examples of the present disclosure can achieve a new effect of protecting the R-TWT SP scheduled by the unassociated (or neighboring) AP by considering R-TWT related scheduling information of not only the associated AP but also the unassociated (or neighboring) AP.

[0288] The embodiments described above are combinations of components and features of the present disclosure in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented without being combined with other components or features. Furthermore, it is also possible to combine some components and / or features to form an embodiment of the present disclosure. The order of operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is self-evident that claims that are not explicitly cited in the scope of the patent may be combined to form an embodiment or incorporated as a new claim through a post-application amendment.

[0289] It will be apparent to those skilled in the art that the present disclosure may be embodied in other specific forms without departing from the essential characteristics of the present disclosure. Therefore, the above detailed description should not be construed as limiting in any respect, but rather as illustrative. The scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents of the present disclosure are intended to be included within the scope of the present disclosure.

[0290] The scope of the present disclosure includes software or machine-executable instructions (e.g., an operating system, an application, firmware, a program, etc.) that cause operations according to the methods of various embodiments to be executed on a device or a computer, and a non-transitory computer-readable medium having such software or instructions stored thereon and executable on the device or computer. Instructions that can be used to program a processing system to perform the features described in the present disclosure can be stored on / in a storage medium or a computer-readable storage medium, and a computer program product including such a storage medium can be used to implement the features described in the present disclosure. The storage medium can include, but is not limited to, high-speed random access memory, such as DRAM, SRAM, DDR RAM, or other random access solid state memory devices, and can include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices. The memory optionally includes one or more storage devices remotely located from the processor(s). The memory or, alternatively, the non-volatile memory device(s) within the memory comprise a non-transitory computer-readable storage medium. The features described in this disclosure may be incorporated into software and / or firmware stored on any of the machine-readable media, which may control the hardware of the processing system and allow the processing system to interact with other mechanisms that utilize results according to embodiments of the present disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0291] The method proposed in this disclosure is described with a focus on examples applied to IEEE 802.11-based systems, but can be applied to various wireless LANs or wireless communication systems in addition to IEEE 802.11-based systems.

Claims

1. A method performed by a station (STA) in a wireless LAN system, the method comprising: A step of receiving a frame transmitted from a second AP of a second BSS by the STA associated with a first AP (access point) of a first BSS (basic service set); A step of transmitting information about one or more time periods that do not overlap with the R-TWT SP to the first AP based on the fact that the frame includes information about a restricted-target wake time (R-TWT) service period (SP) scheduled by the second AP; and A method comprising the step of receiving scheduling information for the STA from the first AP based on information about the one or more time intervals.

2. In paragraph 1, A method wherein information about one or more of the above time intervals is included in a TWT element within a TWT setup frame for a TWT request.

3. In paragraph 2, A method in which information related to whether or not the above R-TWT SP overlaps is included in a control field included in a TWT element within the above TWT setup frame.

4. In paragraph 2, A method in which information related to whether or not the above overlaps with the R-TWT SP is included in a broadcast TWT parameter set field included in a TWT element within the above TWT setup frame.

5. In paragraph 4, Information related to whether there is overlap with the R-TWT SP is configured together with at least one of a first field indicating whether there is cooperation between APs for the R-TWT SP, a second field indicating a BSS color value of an AP that scheduled the R-TWT SP, a third field indicating whether there is a protection operation for the R-TWT SP, or a fourth field indicating a broadcast TWT ID corresponding to the R-TWT SP, within a broadcast TWT parameter set field.

6. In paragraph 2, A method in which information related to whether or not the above R-TWT SP overlaps is included in an element subsequent to the TWT element in the above TWT setup frame.

7. In paragraph 1, A method wherein the scheduling information for the first STA includes information about a TWT SP or information about an R-TWT SP that is allocated and announced to the STA.

8. In paragraph 1, A method wherein the above R-TWT SP is regarded as an R-TWT SP that does not cooperate between the first AP and the second AP.

9. In a first station (STA) device of a wireless LAN system, the device: one or more transmitters and receivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: By the first STA associated with the first AP (access point) of the first BSS (basic service set), a frame transmitted from the second AP of the second BSS is received; Based on the fact that the frame includes information about a restricted-target wake time (R-TWT) service period (SP) scheduled by the second AP, transmitting information about one or more time periods that do not overlap with the R-TWT SP to the first AP; A device configured to receive scheduling information for the STA from the first AP based on information about the one or more time intervals.

10. A method performed by a first access point (AP) in a wireless LAN system, wherein the method: A step of receiving information about one or more time intervals that do not overlap with an R-TWT SP scheduled by a second AP of a second BSS from a STA associated with the first AP of the first BSS; and A method comprising the step of allocating and notifying scheduling information for the STA based on information about the one or more time intervals.

11. In a first access point (AP) device of a wireless LAN system, the device: one or more transmitters and receivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: Receive information about one or more time intervals that do not overlap with an R-TWT SP scheduled by a second AP of a second BSS from a STA associated with the first AP of the first BSS, A device configured to allocate and notify scheduling information for the STA based on information about the one or more time intervals.

12. A method performed by a station (STA) in a wireless LAN system, the method comprising: A step of receiving a frame including an announcement related to a restricted-TWT (R-TWT) service period (SP) from a first access point (AP) to which the STA is coupled; A step of performing a related operation for the above R-TWT SP is included, A method wherein the announcement includes both information related to the first R-TWT SP and information related to the second R-TWT SP, based on the fact that the first R-TWT SP scheduled by the first AP and the second R-TWT SP scheduled by the second AP to which the STA is not associated do not overlap in the time domain.

13. In paragraph 12, A method wherein the announcement includes information related to the first R-TWT SP, based on the fact that the first R-TWT SP scheduled by the first AP and the second R-TWT SP scheduled by the second AP to which the STA is not associated overlap in the time domain.

14. In paragraph 12, The method further includes scheduling information and additional information for the second R-TWT SP.

15. In paragraph 14, A method wherein the additional information includes information indicating whether cooperation between the first AP and the second AP occurs for the second R-TWT SP.

16. In paragraph 15, A method in which cooperation with the second R-TWT SP is determined based on whether negotiation between the first AP and the second AP has been successfully completed, or whether the second R-TWT SP has been allocated by an entity managing the first AP and the second AP.

17. In paragraph 14, A method wherein the additional information includes indication information indicating whether to follow a protection rule that terminates its own transmission opportunity (TXOP) before the start time of the second R-TWT SP.

18. In paragraph 17, Setting the above instruction information to a specific value indicates that the second R-TWT SP is to follow the protection rules mandatory, A method in which the above instruction information is set to a value other than a specific value, which indicates that the second R-TWT SP is to follow a conditional protection rule.

19. In paragraph 18, Based on the above instruction information being set to a value other than the specific value, the STA is set to determine whether to follow the protection rule based on other information, A method wherein the other information includes at least one of a BSS color value in a U-SIG field, a threshold value for the reception strength of data received from the second AP, or a spatial reuse related value.

20. In paragraph 14, A method wherein the additional information includes information indicating a BSS color value of an AP scheduling the second R-TWT SP.

21. In paragraph 14, A method wherein the additional information includes information indicating a broadcast TWT ID within a TWT element corresponding to the second R-TWT SP.

22. In paragraph 14, The above additional information, within the frame, Included as a field within the broadcast parameter set field within the TWT element for the second R-TWT SP, A method, which is included within an element subsequent to the TWT element for the second R-TWT SP.

23. In a first station (STA) device of a wireless LAN system, the device: one or more transmitters and receivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: The STA receives a frame including an announcement related to a restricted-TWT (R-TWT) service period (SP) from a first access point (AP) to which the STA is coupled; Set to perform the relevant actions for the above R-TWT SP, A device wherein the announcement includes both information related to the first R-TWT SP and information related to the second R-TWT SP, based on the fact that the first R-TWT SP scheduled by the first AP and the second R-TWT SP scheduled by the second AP to which the STA is not associated do not overlap in the time domain.

24. A method performed by a first access point (AP) in a wireless LAN system, the method comprising: A step of acquiring information about a restricted TWT (R-TWT) service period (SP) scheduled by a second AP belonging to a second BSS different from the first BSS to which the first AP belongs; A step of determining whether there is overlap between the R-TWT SP scheduled by the second AP and the R-TWT SP scheduled by the first AP; A method comprising the step of transmitting a frame for notifying both information related to an R-TWT SP scheduled by the first AP and information related to an R-TWT SP scheduled by the second AP, based on the fact that the R-TWT SP scheduled by the first AP and the R-TWT SP scheduled by the second AP do not overlap in the time domain.

25. In a first access point (AP) device of a wireless LAN system, the device: one or more transmitters and receivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: Obtain information about a restricted TWT (R-TWT) service period (SP) scheduled by a second AP belonging to a second BSS different from the first BSS to which the first AP belongs; Determine whether there is overlap between the R-TWT SP scheduled by the second AP and the R-TWT SP scheduled by the first AP; A device configured to transmit a frame for notifying both information related to the R-TWT SP scheduled by the first AP and information related to the R-TWT SP scheduled by the second AP, based on the fact that the R-TWT SP scheduled by the first AP and the R-TWT SP scheduled by the second AP do not overlap in the time domain.

Images