Method and apparatus for protection level negotiation for multi-access point coordination in wireless LAN system

Abstract

Disclosed are a method and apparatus for protection level-based negotiation for multi-access point coordination in a wireless LAN system. The method according to an embodiment of the present disclosure may comprise the steps of: receiving, by a first AP, a negotiation request frame for multi-access point (AP) coordination from a second AP; and transmitting, by the first AP, a negotiation response frame for the multi-AP coordination to the second AP. The negotiation request frame may comprise information related to protection for a specific target wake time (TWT) schedule.

Description

Method and device for consultation on protection levels for multi-access point cooperation in a wireless LAN system

[0001] The present disclosure relates to a protection level-based negotiation method and apparatus for multi-access point coordination in a Wireless Local Area Network (WLAN) system.

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

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

[0004] The technical problem of the present disclosure is to provide a negotiation method and apparatus based on a protection level for multi-access point coordination in a wireless LAN (WLAN) system.

[0005] The technical problems to be solved in this disclosure are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this disclosure belongs from the description below.

[0006] A method according to one aspect of the present disclosure may include the step of receiving a negotiation request frame for multi-access point (AP) coordination from a second AP by a first AP; and the step of transmitting a negotiation response frame for multi-AP coordination to the second AP by the first AP. The negotiation request frame may include information related to protection for a specific target wake time (TWT) schedule.

[0007] A method according to a further aspect of the present disclosure may include the step of transmitting a consultation request frame for multi-access point (AP) cooperation to a first AP by a second AP; and the step of receiving a consultation response frame for multi-AP cooperation from the first AP by the second AP. The consultation request frame may include information related to protection for a specific target wake time (TWT) schedule.

[0008] According to the present disclosure, a negotiation method and apparatus based on a protection level for multi-access point coordination in a wireless LAN (WLAN) system may be provided.

[0009] According to the present disclosure, a method and apparatus for transmitting or receiving a response to a request for multi-access point cooperation consultation in a wireless LAN system may be provided.

[0010] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below.

[0011] The accompanying drawings, which are included as part of the detailed description to aid in understanding the present disclosure, provide embodiments of the present disclosure and explain the technical features of the present disclosure together with the detailed description.

[0012] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0013] FIG. 2 is a drawing showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0014] FIG. 3 is a diagram illustrating a link setup process to which the present disclosure can be applied.

[0015] FIG. 4 is a drawing illustrating a backoff process to which the present disclosure may be applied.

[0016] FIG. 5 is a diagram illustrating a CSMA / CA-based frame transmission operation to which the present disclosure may be applied.

[0017] FIG. 6 is a drawing for illustrating an example of a frame structure used in a wireless LAN system to which the present disclosure may be applied.

[0018] FIG. 7 is a drawing illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure may be applied.

[0019] FIG. 8 is a diagram illustrating various transmission and reception techniques in a MAP environment to which the present disclosure can be applied.

[0020] FIG. 9 is a drawing illustrating an example of an individual TWT operation to which the present disclosure may be applied.

[0021] FIG. 10 is a drawing illustrating an example of a broadcast TWT operation to which the present disclosure may be applied.

[0022] Figure 11 is a diagram illustrating an example of a TWT information element format.

[0023] Figure 12 is a diagram illustrating examples of individual TWT parameter set field formats.

[0024] Figure 13 is a diagram illustrating examples of broadcast TWT parameter set field formats.

[0025] FIG. 14 is a diagram illustrating exemplary APs and STAs in an OBSS to which the present disclosure may be applied.

[0026] FIG. 15 is a drawing showing an example of the operation of a first AP according to the present disclosure.

[0027] FIG. 16 is a drawing illustrating an example of the operation of a second AP according to the present disclosure.

[0028] FIG. 17 is a diagram illustrating the process of requesting / responding to cooperation / consultation between APs based on protection levels according to the present disclosure.

[0029] Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description disclosed below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiment in which the present disclosure may be practiced. The following detailed description includes specific details to provide a complete understanding of the present disclosure. However, those skilled in the art will know that the present disclosure may be practiced without such specific details.

[0030] In some cases, to avoid obscuring the concept of the present disclosure, known structures and devices may be omitted or illustrated in the form of a block diagram focusing on the core functions of each structure and device.

[0031] In the present disclosure, when a component is described as being “connected,” “combined,” or “joined” with another component, this may include not only a direct connection but also an indirect connection in which another component exists between them. Furthermore, in the present disclosure, the terms “comprising” or “having” specify the presence of the mentioned features, steps, actions, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, actions, elements, components, and / or groups thereof.

[0032] In the present disclosure, terms such as "first," "second," etc. are used solely for the purpose of distinguishing one component from another and are not used to limit the components, nor do they limit the order or importance of the components unless specifically stated otherwise. Accordingly, within the scope of the present disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and likewise, a second component in one embodiment may be referred to as a first component in another embodiment.

[0033] The terms used in this disclosure are for the description of specific embodiments and are not intended to limit the claims. As used in the description of embodiments and in the appended claims, the singular form is intended to include the plural form unless the context clearly indicates otherwise. The term "and / or" as used in this disclosure may refer to one of the related enumerated items, or refers to and includes any and all possible combinations of two or more of them. Additionally, the " / " between words in this disclosure has the same meaning as "and / or" unless otherwise noted.

[0034] The embodiments of the present disclosure may be applied to various wireless communication systems. For example, the embodiments of the present disclosure may be applied to wireless LAN systems. For example, the embodiments of the present disclosure may be applied to wireless LANs based on IEEE 802.11a / g / n / ac / ax / be standards. Furthermore, the embodiments of the present disclosure may be applied to wireless LANs based on newly proposed IEEE 802.11bn (or UHR) standards. Additionally, the embodiments of the present disclosure may be applied to wireless LANs based on next-generation standards following IEEE 802.11bn. Furthermore, the embodiments of the present disclosure may be applied to cellular wireless communication systems. For example, they may be applied to cellular wireless communication systems based on LTE (Long Term Evolution) series technologies and 5G NR (New Radio) series technologies of 3GPP (3rd Generation Partnership Project) standards.

[0035] The following describes the technical features to which the examples of the present disclosure may be applied.

[0036] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0037] The first device (100) and the second device (200) exemplified in FIG. 1 may be replaced with various terms such as terminal, wireless device, WTRU (Wireless Transmit Receive Unit), UE (User Equipment), MS (Mobile Station), UT (user terminal), MSS (Mobile Subscriber Station), MSS (Mobile Subscriber Unit), SS (Subscriber Station), AMS (Advanced Mobile Station), WT (Wireless terminal), or simply user. Additionally, the first device (100) and the second device (200) may be replaced with various terms such as access point (AP), BS (Base Station), fixed station, Node B, BTS (base transceiver system), network, AI (Artificial Intelligence) system, RSU (road side unit), repeater, router, relay, gateway, etc.

[0038] The device (100, 200) exemplified in FIG. 1 may be referred to as a station (STA). For example, the device (100, 200) exemplified in FIG. 1 may be referred to by various terms such as a transmitting device, a receiving device, a transmitting STA, or a receiving STA. For example, the STA (110, 200) may perform the role of an access point (AP) or a non-AP. That is, in the present disclosure, the STA (110, 200) may perform the functions of an AP and / or a non-AP. If the STA (110, 200) performs the AP function, it may simply be referred to as an AP, and if the STA (110, 200) performs the non-AP function, it may simply be referred to as a STA. Additionally, in the present disclosure, the AP may also be indicated as an AP STA.

[0039] Referring to FIG. 1, the first device (100) and the second device (200) can transmit and receive wireless signals through various wireless LAN technologies (e.g., IEEE 802.11 series). The first device (100) and the second device (200) may include interfaces for the medium access control (MAC) layer and the physical layer (PHY) that comply with the specifications of the IEEE 802.11 standard.

[0040] In addition, the first device (100) and the second device (200) may additionally support various communication standards other than wireless LAN technology (e.g., 3GPP LTE series, 5G NR series standards, etc.). In addition, the device of the present disclosure may be implemented as various devices such as mobile phones, vehicles, personal computers, AR (Augmented Reality) equipment, VR (Virtual Reality) equipment, etc. Furthermore, the STA of the present specification may support various communication services such as voice calls, video calls, data communication, autonomous driving, MTC (Machine-Type Communication), M2M (Machine-to-Machine), D2D (Device-to-Device), and IoT (Internet-of-Things).

[0041] The first device (100) includes one or more processors (102) and one or more memories (104), and may additionally include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memory (104) and / or transceivers (106) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or sequences of operation disclosed in this disclosure. For example, the processor (102) may process information within the memory (104) to generate a first information / signal and then transmit a wireless signal containing the first information / signal through the transceiver (106). Additionally, the processor (102) may receive a wireless signal containing a second information / signal through the transceiver (106) and then store information obtained from the signal processing of the second information / signal in the memory (104). Memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, memory (104) may store software code including instructions for performing some or all of the processes controlled by the processor (102) or for performing the descriptions, functions, procedures, proposals, methods, and / or sequences of operation disclosed in this disclosure. Here, the processor (102) and memory (104) may be part of a communication modem / circuit / chip designed to implement wireless LAN technology (e.g., IEEE 802.11 series). A transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals through one or more antennas (108). The transceiver (106) may include a transmitter and / or receiver. The transceiver (106) may be combined with an RF (Radio Frequency) unit. In the present disclosure, the device may refer to a communication modem / circuit / chip.

[0042] The second device (200) includes one or more processors (202) and one or more memories (204), and may additionally include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memory (204) and / or transceivers (206) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or sequences of operation disclosed in this disclosure. For example, the processor (202) may process information within the memory (204) to generate a third information / signal and then transmit a wireless signal containing the third information / signal through the transceiver (206). Additionally, the processor (202) may receive a wireless signal containing a fourth information / signal through the transceiver (206) and then store information obtained from the signal processing of the fourth information / signal in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may store software code containing instructions for performing some or all of the processes controlled by the processor (202) or for performing the descriptions, functions, procedures, proposals, methods, and / or sequences of operation disclosed in this disclosure. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement wireless LAN technology (e.g., IEEE 802.11 series). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals through one or more antennas (208). The transceiver (206) may include a transmitter and / or receiver. The transceiver (206) may be used in combination with an RF unit. In the present disclosure, the device may refer to a communication modem / circuit / chip.

[0043] Hereinafter, hardware elements of the device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this disclosure. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this disclosure. One or more processors (102, 202) may generate a signal (e.g., a baseband signal) including a PDU, SDU, message, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed in this disclosure and provide it to one or more transceivers (106, 206). One or more processors (102, 202) may receive a signal (e.g., a baseband signal) from one or more transceivers (106, 206) and may obtain a PDU, SDU, message, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this disclosure.

[0044] One or more processors (102, 202) may be referred to as a controller, microcontroller, microprocessor, or microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this disclosure may be included in one or more processors (102, 202) or stored in one or more memories (104, 204) and driven by one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this disclosure may be implemented using firmware or software in the form of code, instructions, and / or sets of instructions.

[0045] One or more memories (104, 204) may be connected to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. One or more memories (104, 204) may be composed of ROM, RAM, EPROM, flash memory, hard drive, registers, cache memory, computer read storage media, and / or combinations thereof. One or more memories (104, 204) may be located inside and / or outside of one or more processors (102, 202). Additionally, one or more memories (104, 204) may be connected to one or more processors (102, 202) through various technologies such as wired or wireless connections.

[0046] One or more transceivers (106, 206) may transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or operation flowcharts, etc., of the present disclosure to one or more other devices. One or more transceivers (106, 206) may receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or operation flowcharts, etc., disclosed in the present disclosure from one or more other devices. For example, one or more transceivers (106, 206) may be connected to one or more processors (102, 202) and may transmit and receive wireless signals. For example, one or more processors (102, 202) may control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be connected to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this disclosure through one or more antennas (108, 208). In this disclosure, one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can convert the received wireless signal / channel, etc. from an RF band signal to a baseband signal in order to process the received user data, control information, wireless signal / channel, etc. using one or more processors (102, 202).One or more transceivers (106, 206) can convert user data, control information, wireless signals / channels, etc. processed using one or more processors (102, 202) from baseband signals to RF band signals. To this end, one or more transceivers (106, 206) may include (analog) oscillators and / or filters.

[0047] For example, one of the STAs (100, 200) may perform the intended operation of an AP, and the other of the STAs (100, 200) may perform the intended operation of a non-AP STA. For example, the transceiver (106, 206) of FIG. 1 may perform the operation of transmitting and receiving signals (e.g., packets or PPDU (Physical Layer Protocol Data Unit) according to IEEE 802.11a / b / g / n / ac / ax / be / bn, etc.). Additionally, the operation of generating transmission and reception signals or performing data processing or calculations in advance for transmission and reception signals by various STAs in the present disclosure may be performed by the processor (102, 202) of FIG. 1. For example, an example of an operation to generate a transmission and reception signal or to perform data processing or operations in advance for a transmission and reception signal may include: 1) an operation to determine / acquire / configure / operate / decode / encode bit information of fields (SIG (signal), STF (short training field), LTF (long training field), Data, etc.) included in the PPDU; 2) an operation to determine / configure / acquire time resources or frequency resources (e.g., subcarrier resources) used for fields (SIG, STF, LTF, Data, etc.) included in the PPDU; 3) an operation to determine / configure / acquire specific sequences (e.g., pilot sequence, STF / LTF sequence, extra sequence applied to SIG) used for fields (SIG, STF, LTF, Data, etc.) included in the PPDU; 4) power control operations and / or power saving operations applied to the STA; and 5) operations related to determining / acquiring / configuring / operating / decoding / encoding of an ACK signal. In addition, in the following example, various information (e.g., information related to fields, subfields, control fields, parameters, power, etc.) used by various STAs for determining / acquiring / configuring / calculating / decoding / encoding of transmission and reception signals can be stored in the memory (104, 204) of FIG. 1.

[0048] In the following, the downlink (DL) refers to a link for communication from an AP STA to a non-AP STA, and downlink PPDUs, packets, signals, etc., can be transmitted and received through the downlink. In downlink communication, the transmitter may be part of the AP STA, and the receiver may be part of the non-AP STA. The uplink (UL) refers to a link for communication from a non-AP STA to an AP STA, and uplink PPDUs, packets, signals, etc., can be transmitted and received through the uplink. In uplink communication, the transmitter may be part of the non-AP STA, and the receiver may be part of the AP STA.

[0049] FIG. 2 is a drawing showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0050] The structure of a wireless LAN system can be composed of multiple components. Through the interaction of multiple components, a wireless LAN that supports STA mobility transparent to the upper layer can be provided. A Basic Service Set (BSS) corresponds to the basic building block of a wireless LAN. Figure 2 exemplarily illustrates the existence of two BSSs (BSS1 and BSS2) and the inclusion of two STAs as members of each BSS (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2). In Figure 2, the ellipse representing the BSS can also be understood as representing the coverage area where the STAs included in the corresponding BSS maintain communication. This area can be referred to as a Basic Service Area (BSA). If a STA moves outside the BSA, it becomes unable to communicate directly with other STAs within that BSA.

[0051] Excluding the DS illustrated in Fig. 2, the most basic type of BSS in a wireless LAN is the Independent BSS (IBSS). For example, an IBSS can have a minimal form consisting of only two STAs. For instance, assuming other components are omitted, a BSS1 composed of only STA1 and STA2, or a BSS2 composed of only STA3 and STA4, can each be considered a representative example of an IBSS. Such a configuration is possible when the STAs can communicate directly without an AP. Furthermore, this type of wireless LAN is not configured through pre-planning but can be configured when a LAN is needed, and this can be referred to as an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity. In other words, in an IBSS, STAs are managed in a distributed manner. In IBSS, all STAs can be mobile STAs, and since connections to distributed systems (DS) are not allowed, they form a self-contained network.

[0052] The membership of an STA in a BSS can be dynamically changed by the STA being turned on or off, or by the STA entering or leaving the BSS area. To become a member of a BSS, an STA can join the BSS using a synchronization process. To access all services of the BSS infrastructure, an STA must be associated with the BSS. This association can be configured dynamically and may include the use of a Distribution System Service (DSS).

[0053] In a wireless LAN, the direct STA-to-STA distance may be limited by PHY performance. In some cases, this distance limit may be sufficient, but in others, communication between STAs over longer distances may be required. To support extended coverage, a distributed system (DS) may be configured.

[0054] DS refers to a structure in which BSSs are interconnected. Specifically, as shown in FIG. 2, a BSS may exist as a component in an extended form of a network composed of multiple BSSs. DS is a logical concept and can be specified by the characteristics of the Distributed System Medium (DSM). In this regard, the Wireless Medium (WM) and the DSM can be logically distinguished. Each logical medium is used for a different purpose and is utilized by different components. These media are not limited to being identical or different. The flexibility of the wireless LAN structure (DS structure or other network structure) can be explained by the fact that multiple media are logically distinct in this way. That is, the wireless LAN structure can be implemented in various ways, and the corresponding wireless LAN structure can be specified independently by the physical characteristics of each implementation.

[0055] DS can support mobile devices by providing seamless integration of multiple BSSs and providing logical services necessary for handling addresses to destinations. Additionally, DS may include a component called a portal that acts as a bridge for connecting the wireless LAN with another network (e.g., IEEE 802.X).

[0056] An AP refers to an entity that enables access to the DS via the WM for combined non-AP STAs and also possesses the functionality of an STA. Data movement between the BSS and the DS can be performed through the AP. For example, STA2 and STA3 shown in FIG. 2 possess the functionality of an STA and provide the ability for combined non-AP STAs (STA1 and STA4) to access the DS. Furthermore, since all APs fundamentally correspond to STAs, all APs are addressable entities. The address used by the AP for communication on the WM and the address used by the AP for communication on the DSM do not necessarily have to be the same. A BSS composed of an AP and one or more STAs can be referred to as an infrastructure BSS.

[0057] Data transmitted from one of the STA(s) coupled to the AP to the STA address of the AP can always be received at an uncontrolled port and processed by an IEEE 802.1X port access entity. Additionally, if the controlled port is authenticated, the transmitted data (or frame) can be forwarded to the DS.

[0058] In addition to the structure of the aforementioned DS, an Extended Service Set (ESS) may be configured to provide wider coverage.

[0059] An ESS refers to a network of arbitrary size and complexity composed of DSs and BSSs. An ESS can correspond to a set of BSSs connected to a single DS. However, an ESS does not contain a DS. An ESS network is characterized by appearing as an IBSS at the Logical Link Control (LLC) layer. STAs included in an ESS can communicate with each other, and mobile STAs can move from one BSS to another (within the same ESS) transparently to the LLC. APs included in a single ESS can have the same Service Set Identification (SSID). The SSID is distinct from the BSSID, which is the identifier for the BSS.

[0060] In wireless LAN systems, no assumptions are made regarding the relative physical locations of BSSs, and all of the following forms are possible. BSSs may partially overlap, which is a form commonly used to provide continuous coverage. Additionally, BSSs may not be physically connected, and logically, there is no limit to the distance between BSSs. Furthermore, BSSs may be located in the same physical location, which can be used to provide redundancy. Also, one (or more) IBSS or ESS networks may physically exist in the same space as one (or more) ESS networks. This may apply to ESS network forms such as when an ad-hoc network operates at a location where an ESS network exists, when wireless networks that physically overlap are configured by different organizations, or when two or more different access and security policies are required at the same location.

[0061] FIG. 3 is a diagram illustrating a link setup process to which the present disclosure can be applied.

[0062] In order for an STA to set up a link and transmit and receive data on a network, it must first discover the network, perform authentication, establish an association, and go through authentication procedures for security. The link setup process can also be referred to as the session initiation process or the session setup process. Additionally, the processes of discovery, authentication, association, and security setup in the link setup process can be collectively referred to as the association process.

[0063] In step S310, the STA may perform a network discovery operation. The network discovery operation may include the STA's scanning operation. That is, in order for the STA to access a network, it must find a network it can join. Before joining a wireless network, the STA must identify a compatible network, and the process of identifying networks existing in a specific area is called scanning.

[0064] Scanning methods include active scanning and passive scanning. Figure 3 illustrates a network discovery operation that includes an active scanning process as an example. In active scanning, the STA performing the scanning moves between channels to search for nearby APs, transmits a probe request frame, and waits for a response. The responder transmits a probe response frame as a response to the probe request frame to the STA that transmitted the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame from the BSS of the channel being scanned. In a BSS, the AP becomes the responder because it transmits the beacon frame; however, in an IBSS, the responder is not constant because STAs within the IBSS take turns transmitting the beacon frame. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning in the same way (i.e., transmit and receive probe request / response on channel 2).

[0065] Although not illustrated in FIG. 3, the scanning operation may be performed using a passive scanning method. In passive scanning, the STA performing the scanning waits for a beacon frame while switching between channels. A beacon frame is one of the management frames defined in IEEE 802.11, which is periodically transmitted to announce the presence of a wireless network and to allow the scanning STA to find the wireless network and join it. In a BSS, the AP performs the role of periodically transmitting beacon frames, and in an IBSS, the STAs within the IBSS take turns transmitting beacon frames. When the scanning STA receives a beacon frame, it stores the information about the BSS included in the beacon frame and records the beacon frame information in each channel while moving to another channel. The STA that receives the beacon frame stores the BSS-related information included in the received beacon frame, moves to the next channel, and can perform scanning in the next channel in the same way. When comparing active scanning and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.

[0066] After the STA discovers the network, an authentication process may be performed in step S320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation in step S340 described later.

[0067] The authentication process involves the STA sending an authentication request frame to the AP, and the AP sending an authentication response frame to the STA in response. The authentication frame used in the authentication request / response corresponds to a management frame.

[0068] The authentication frame may include information regarding the authentication algorithm number, authentication transaction sequence number, status code, challenge text, Robust Security Network (RSN), Finite Cyclic Group, etc. These are some examples of information that may be included in the authentication request / response frame, and they may be replaced with other information or additional information may be included.

[0069] The STA can send an authentication request frame to the AP. Based on the information contained in the received authentication request frame, the AP can determine whether to allow authentication for the STA. The AP can provide the result of the authentication process to the STA through an authentication response frame.

[0070] After the STA is successfully authenticated, the association process can be performed in step S330. The association process includes the STA transmitting an association request frame to the AP, and in response, the AP transmitting an association response frame to the STA.

[0071] For example, the association request frame may include information regarding various capabilities, beacon listen interval, service set identifier (SSID), supported rates, supported channels, RSN, mobility domain, supported operating classes, Traffic Indication Map Broadcast request, interworking service capabilities, etc. For example, the association response frame may include information regarding various capabilities, status code, Association ID (AID), supported rates, Enhanced Distributed Channel Access (EDCA) parameter set, Received Channel Power Indicator (RCPI), Received Signal to Noise Indicator (RSNI), mobility domain, timeout interval (e.g., association comeback time), overlapping BSS scan parameters, TIM broadcast response, Quality of Service (QoS) map, etc. These are some examples of information that may be included in a combined request / response frame, and may be replaced with other information or additional information may be included.

[0072] After the STA is successfully joined to the network, a security setup process can be performed in step S340. The security setup process in step S340 may be described as an authentication process through RSNA (Robust Security Network Association) requests / responses, and the authentication process in step S320 may be referred to as the first authentication process, and the security setup process in step S340 may simply be referred to as the authentication process.

[0073] The security setup process of step S340 may include, for example, a private key setup process through a 4-way handshake via an EAPOL (Extensible Authentication Protocol over LAN) frame. Additionally, the security setup process may be performed according to a security method not defined in the IEEE 802.11 standard.

[0074] FIG. 4 is a drawing illustrating a backoff process to which the present disclosure may be applied.

[0075] In wireless LAN systems, the basic access mechanism for MAC (Medium Access Control) is the CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism. The CSMA / CA mechanism is also known as the Distributed Coordination Function (DCF) of IEEE 802.11 MAC, and it basically employs a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or STA may perform Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time interval (e.g., DIFS (DCF Inter-Frame Space)) before starting transmission. If the sensing result determines that the medium is in an idle status, it starts transmitting a frame through that medium. On the other hand, if the medium is detected to be occupied or busy, the AP and / or STA may not start its own transmission but wait by setting a delay period for medium access (e.g., a random backoff period) before attempting to transmit a frame. By applying a random backoff period, multiple STAs are expected to attempt to transmit frames after waiting for different periods of time, thereby minimizing collisions.

[0076] In addition, the IEEE 802.11 MAC protocol provides a Hybrid Coordination Function (HCF). The HCF is based on the aforementioned Point Coordination Function (PCF). The PCF is a polling-based synchronous access method that periodically polls to ensure all receiving APs and / or STAs can receive data frames. Furthermore, the HCF includes Enhanced Distributed Channel Access (EDCA) and Controlled Channel Access (HCCA). EDCA is a contention-based access method for a provider to offer data frames to multiple users, while HCCA uses a non-contention-based channel access method utilizing a polling mechanism. Additionally, the HCF includes a media access mechanism to improve the Quality of Service (QoS) of the wireless LAN and can transmit QoS data during both the Contention Period (CP) and the Contention-Free Period (CFP).

[0077] With reference to FIG. 4, the operation based on the random backoff period is described. When a medium in an occupied / busy state changes to an idle state, multiple STAs may attempt to transmit data (or frames). As a measure to minimize collisions, each STA may select a random backoff count and attempt transmission after waiting for the corresponding slot time. The random backoff count has a pseudo-random integer value and can be determined as one of the values ​​in the range from 0 to CW. Here, CW is the Contention Window parameter value. The CW parameter is given an initial value of CWmin, but in the case of transmission failure (e.g., failure to receive an ACK for a transmitted frame), it may take a value twice that amount. When the CW parameter value becomes CWmax, data transmission may be attempted while maintaining the CWmax value until data transmission is successful; if data transmission is successful, it is reset to the CWmin value. The values ​​of CW, CWmin, and CWmax are 2 n It is desirable to set it to -1 (n=0, 1, 2, ...).

[0078] When the random backoff process begins, the STA continues to monitor the media while counting down the backoff slots according to the determined backoff count value. When the media is monitored as occupied, it stops the countdown and waits, and when the media becomes idle, it resumes the remaining countdown.

[0079] In the example of Fig. 4, when a packet to be transmitted arrives at the MAC of STA3, STA3 confirms that the medium is idle for DIFS and can immediately transmit the frame. The remaining STAs monitor whether the medium is occupied or busy and wait. Meanwhile, data to be transmitted may also arise from each of STA1, STA2, and STA5, and each STA can perform a countdown of the backoff slot according to a random backoff count value selected by each after waiting for DIFS when the medium is monitored to be idle. Assume the case where STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. That is, this exemplifies a case where, at the point when STA2 finishes the backoff count and starts transmitting the frame, the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1. STA1 and STA5 pause the countdown briefly and wait while STA2 occupies the medium. When STA2's possession ends and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume the paused backoff count. That is, they can start transmitting a frame after counting down the remaining backoff slots corresponding to the remaining backoff time. Since STA5's remaining backoff time was shorter than STA1's, STA5 starts transmitting the frame. While STA2 is occupying the medium, data to be transmitted may also be generated by STA4. From STA4's perspective, when the medium becomes idle, it waits for DIFS, performs a countdown based on a random backoff count value selected by itself, and can start transmitting a frame. The example in Figure 4 illustrates a case where STA5's remaining backoff time happens to match STA4's random backoff count value; in this case, a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 receives an ACK, resulting in a failure to transmit data.In this case, STA4 and STA5 can double the CW value, select a random backoff count value, and perform a countdown. STA1 waits while the medium is occupied due to transmission by STA4 and STA5, and when the medium becomes idle, it waits for DIFS, and then can start transmitting frames after the remaining backoff time has passed.

[0080] As shown in the example in Fig. 4, a data frame is a frame used for transmitting data that is forwarded to an upper layer, and can be transmitted after a backoff performed after the elapsed time of DIFS from when the medium becomes idle. Additionally, a management frame is a frame used for exchanging management information that is not forwarded to an upper layer, and is transmitted after a backoff performed after the elapsed time of an IFS such as DIFS or PIFS (Point coordination function IFS). Subtypes of management frames include Beacon, Association request / response, re-association request / response, probe request / response, and authentication request / response. A control frame is a frame used to control access to the medium. Subtype frames of control frames include RTS (Request-To-Send), CTS (Clear-To-Send), ACK (Acknowledgment), PS-Poll (Power Save-Poll), Block ACK (BlockAck), Block ACK Request (BlockACKReq), NDP Announcement (null data packet announcement), and Trigger. If a control frame is not an acknowledgment frame of a previous frame, it is transmitted after a backoff performed after the elapsed DIFS; if it is an acknowledgment frame of a previous frame, it is transmitted after the elapsed SIFS (short IFS) without a backoff. The type and subtype of a frame can be identified by the type field and subtype field within the Frame Control (FC) field.

[0081] A QoS (Quality of Service) STA can transmit a frame after backoff, which is performed after the passage of the arbitration IFS (AIFS) for the access category (AC) to which the frame belongs, i.e., AIFS[i] (where i is a value determined by the AC). Here, the frame for which AIFS[i] can be used can be a data frame or a management frame, and can also be a control frame rather than a response frame.

[0082] FIG. 5 is a diagram illustrating a CSMA / CA-based frame transmission operation to which the present disclosure may be applied.

[0083] As previously mentioned, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, where the STA directly senses the medium. Virtual carrier sensing is intended to mitigate problems that may occur in medium access, such as the hidden node problem. For virtual carrier sensing, the STA's MAC can utilize the Network Allocation Vector (NAV). The NAV is a value that indicates to other STAs the time remaining until the medium becomes available, provided that the STA currently using or authorized to use the medium is using it. Therefore, the value set as the NAV corresponds to the period during which the medium is scheduled to be used by the STA transmitting the frame, and the STA receiving the NAV value is prohibited from accessing the medium during that period. For example, the NAV can be set based on the value of the "duration" field in the frame's MAC header.

[0084] In the example of FIG. 5, it is assumed that STA1 intends to transmit data to STA2, and STA3 is located in a position where it can overhear part or all of the frames transmitted and received between STA1 and STA2.

[0085] In order to reduce the possibility of collisions between multiple STAs in a CSMA / CA-based frame transmission operation, a mechanism utilizing RTS / CTS frames may be applied. In the example of FIG. 5, while STA1 is transmitting, the medium may be determined to be idle based on the carrier sensing result of STA3. That is, STA1 may be a hidden node to STA3. Alternatively, in the example of FIG. 5, while STA2 is transmitting, the medium may be determined to be idle based on the carrier sensing result of STA3. That is, STA2 may be a hidden node to STA3. By exchanging RTS / CTS frames before performing data transmission and reception between STA1 and STA2, it is possible to prevent a STA outside the transmission range of either STA1 or STA2, or a STA outside the carrier sensing range for transmission from STA1 or STA3, from attempting to occupy the channel during data transmission and reception between STA1 and STA2.

[0086] Specifically, STA1 can determine whether the channel is in use through carrier sensing. In terms of physical carrier sensing, STA1 can determine the channel occupancy idle state based on the energy magnitude or signal correlation detected in the channel. Additionally, in terms of virtual carrier sensing, STA1 can determine the channel occupancy state using a NAV (network allocation vector) timer.

[0087] If the channel is idle during DIFS, STA1 can send an RTS frame to STA2 after performing backoff. If STA2 receives the RTS frame, it can send a CTS frame to STA1 as a response to the RTS frame after SIFS.

[0088] If STA3 cannot overhear a CTS frame from STA2 but can overhear an RTS frame from STA1, STA3 can set a NAV timer for the duration of subsequently transmitted frames (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame) using the duration information included in the RTS frame. Alternatively, if STA3 cannot overhear an RTS frame from STA1 but can overhear a CTS frame from STA2, STA3 can set a NAV timer for the duration of subsequently transmitted frames (e.g., SIFS + data frame + SIFS + ACK frame) using the duration information included in the CTS frame. That is, if STA3 can overhear one or more of the RTS or CTS frames from one or more of STA1 or STA2, it can set a NAV accordingly. If STA3 receives a new frame before the NAV timer expires, it can update the NAV timer using the duration information contained in the new frame. STA3 does not attempt channel access until the NAV timer expires.

[0089] If STA1 receives a CTS frame from STA2, it may transmit a data frame to STA2 after SIFS from the time the reception of the CTS frame is completed. If STA2 successfully receives the data frame, it may transmit an ACK frame to STA1 as an acknowledgment to the data frame after SIFS. STA3 may determine whether the channel is in use through carrier sensing when the NAV timer expires. If STA3 determines that the channel is not in use by another terminal during DIFS from the time the NAV timer expires, it may attempt channel access after a contention window (CW) based on random backoff has passed.

[0090] FIG. 6 is a drawing for illustrating an example of a frame structure used in a wireless LAN system to which the present disclosure may be applied.

[0091] Based on instructions or primitives (meaning a set of instructions or parameters) from the MAC layer, the PHY layer can prepare the MPDU (MAC PDU) to be transmitted. For example, upon receiving an instruction from the MAC layer requesting the start of transmission, the PHY layer switches to transmit mode and can construct the information provided by the MAC layer (e.g., data) into a frame for transmission. Additionally, if the PHY layer detects a valid preamble of a received frame, it monitors the preamble header and sends an instruction to the MAC layer indicating the start of reception.

[0092] As such, information transmission and reception in wireless LAN systems are carried out in the form of frames, and for this purpose, the Physical Layer Protocol Data Unit (PPDU) format is defined.

[0093] A basic PPDU may include a Short Training Field (STF), a Long Training Field (LTF), a Signal (SIGNAL) field, and a Data field. The most basic (e.g., the non-HT (High Throughput)) PPDU format illustrated in FIG. 7 may consist only of Legacy-STF (Legacy-STF), Legacy-LTF (Legacy-LTF), Legacy-SIG (Legacy-SIG) fields and a Data field. In addition, depending on the type of PPDU format (e.g., HT-mixed format PPDU, HT-greenfield format PPDU, VHT (Very High Throughput) PPDU, etc.), additional (or other types of) RL-SIG, U-SIG, non-legacy SIG fields, non-legacy STF, non-legacy LTF, (i.e., xx-SIG, xx-STF, xx-LTF (e.g., xx is HT, VHT, HE, EHT, etc.)) may be included between the L-SIG field and the data field. More specific details will be described later with reference to FIG. 7.

[0094] STF is a signal for signal detection, AGC (Automatic Gain Control), diversity selection, and precise time synchronization, while LTF is a signal for channel estimation and frequency error estimation. STF and LTF can be considered signals for synchronization and channel estimation in the OFDM physical layer.

[0095] The SIG field may contain various information related to the transmission and reception of the PPDU. For example, the L-SIG field consists of 24 bits and may include a 4-bit Rate field, a 1-bit Reserved bit, a 12-bit Length field, a 1-bit Parity field, and a 6-bit Tail field. The RATE field may contain information regarding the modulation and coding rates of the data. For example, the 12-bit Length field may contain information regarding the length or time duration of the PPDU. For example, the value of the 12-bit Length field may be determined based on the type of the PPDU. For example, for non-HT, HT, VHT, or EHT PPDUs, the value of the Length field may be determined as a multiple of 3. For example, for HE PPDUs, the value of the Length field may be determined as a multiple of 3 + 1 or a multiple of 3 + 2.

[0096] The data field may include a SERVICE field, a PSDU (Physical layer Service Data Unit), and PPDU TAIL bits, and may also include padding bits if necessary. Some bits of the SERVICE field may be used for synchronization of the descrambler at the receiver. The PSDU corresponds to a MAC PDU defined at the MAC layer and may contain data generated or used by the upper layer. The PPDU TAIL bits may be used to return the encoder to a 0 state. Padding bits may be used to adjust the length of the data field to a predetermined unit.

[0097] A MAC PDU is defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a Frame Check Sequence (FCS). A MAC frame is composed of a MAC PDU and can be transmitted or received through the PSDU of the data portion in the PPDU format.

[0098] The MAC header includes a Frame Control field, a Duration / ID field, an Address field, etc. The Frame Control field may contain control information necessary for transmitting or receiving frames. The Duration / ID field may be set as the time for transmitting the corresponding frame. Address subfields may indicate the frame's receiver address, transmitter address, destination address, and source address, and some address subfields may be omitted. Specific details regarding each subfield of the MAC header, including Sequence Control, QoS Control, and HT Control subfields, can be found in the IEEE 802.11 standard document.

[0099] The Null-Data PPDU (NDP) format refers to a PPDU format that does not include a data field. In other words, NDP is a frame format that includes the PPDU preamble (i.e., L-STF, L-LTF, L-SIG fields, and additionally, non-legacy SIG, non-legacy STF, and non-legacy LTF if present) from a standard PPDU format, but excludes the remaining parts (i.e., the data field).

[0100] FIG. 7 is a drawing illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure may be applied.

[0101] Various forms of PPDU have been used in standards such as IEEE 802.11a / g / n / ac / ax. The basic PPDU format (IEEE 802.11a / g) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format may also be referred to as the non-HT PPDU format (Fig. 7(a)).

[0102] The HT PPDU format (IEEE 802.11n) additionally includes HT-SIG, HT-STF, and HT-LFT(s) fields in addition to the basic PPDU format. The HT PPDU format illustrated in FIG. 7(b) may be referred to as the HT-mixed format. Additionally, an HT-greenfield format PPDU may be defined, which corresponds to a format consisting of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTFs, and a Data field, without including L-STF, L-LTF, and L-SIG (not shown).

[0103] An example of the VHT PPDU format (IEEE 802.11ac) includes the VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format (Fig. 7(c)).

[0104] An example of the HE PPDU format (IEEE 802.11ax) includes the RL-SIG (Repeated L-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and PE (Packet Extension) fields in addition to the basic PPDU format (Fig. 7(d)). Depending on the specific examples of the HE PPDU format, some fields may be excluded or their lengths may vary. For example, the HE-SIG-B field is included in the HE PPDU format for multiple users (MU), but is not included in the HE PPDU format for single users (SU). Additionally, the HE trigger-based (TB) PPDU format does not include HE-SIG-B, and the length of the HE-STF field may vary to 8 µs. The HE ER (Extended Range) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may vary to 16 µs. For example, RL-SIG can be configured identically to L-SIG. Based on the presence of RL-SIG, the receiving STA can determine that the received PPDU is a HE PPDU or the EHT PPDU described later.

[0105] The EHT PPDU format may include the EHT MU (multi-user) of FIG. 7(e) and the EHT TB (trigger-based) PPDU of FIG. 7(f). The EHT PPDU format is similar to the HE PPDU format in that it includes RL-SIG following L-SIG, but it may include U (universal)-SIG, EHT-SIG, EHT-STF, and EHT-LTF following RL-SIG.

[0106] The EHT MU PPDU of FIG. 7(e) corresponds to a PPDU that carries one or more data (or PSDU) for one or more users. That is, the EHT MU PPDU can be used for both SU transmission and MU transmission. For example, the EHT MU PPDU can correspond to a PPDU for one receiving STA or multiple receiving STAs.

[0107] The EHT-SIG is omitted in the EHT TB PPDU of FIG. 7(f) compared to the EHT MU PPDU. A STA that receives a trigger for UL MU transmission (e.g., a trigger frame or TRS (triggered response scheduling)) can perform UL transmission based on the EHT TB PPDU format.

[0108] The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated so that demodulation and decoding can be attempted even on legacy STAs, and mapped based on a defined subcarrier frequency interval (e.g., 312.5 kHz). These can be referred to as pre-EHT modulated fields. Next, the EHT-STF, EHT-LTF, Data, and PE fields can be encoded and modulated so that they can be demodulated and decoded by a STA that has successfully decoded a non-legacy SIG (e.g., U-SIG and / or EHT-SIG) to obtain the information contained in the corresponding fields, and mapped based on a defined subcarrier frequency interval (e.g., 78.125 kHz). These can be referred to as EHT modulated fields.

[0109] Similarly, in the HE PPDU format, the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, and HE-SIG-B fields can be referred to as pre-HE modulation fields, and the HE-STF, HE-LTF, Data, and PE fields can be referred to as HE modulation fields. Also, in the VHT PPDU format, the L-STF, L-LTF, L-SIG, and VHT-SIG-A fields can be referred to as pre-VHT modulation fields, and the VHT STF, VHT-LTF, VHT-SIG-B, and Data fields can be referred to as VHT modulation fields.

[0110] The U-SIG included in the EHT PPDU format of FIG. 7 can be constructed based on, for example, two symbols (e.g., two consecutive OFDM symbols). Each symbol for the U-SIG (e.g., OFDM symbol) can have a duration of 4 µs, and the U-SIG can have a total duration of 8 µs. Each symbol of the U-SIG can be used to transmit 26 bits of information. For example, each symbol of the U-SIG can be transmitted and received based on 52 data tones and 4 pilot tones.

[0111] U-SIGs can be configured in 20 MHz units. For example, if an 80 MHz PPDU is configured, the same U-SIG can be duplicated in 20 MHz units. That is, four identical U-SIGs can be included within an 80 MHz PPDU. If the bandwidth exceeds 80 MHz, for example, for a 160 MHz PPDU, the U-SIG of the first 80 MHz unit and the U-SIG of the second 80 MHz unit may be different.

[0112] For example, A number of uncoded bits may be transmitted through U-SIG, and the first symbol of U-SIG (e.g., U-SIG-1 symbol) transmits the first X bits of the total A bit information, and the second symbol of U-SIG (e.g., U-SIG-2 symbol) transmits the remaining Y bits of the total A bit information. The A bit information (e.g., 52 uncoded bits) may include a CRC field (e.g., a field of 4 bits) and a tail field (e.g., a field of 6 bits). The tail field may be used to terminate the trellis of the convolution decoder and may be set to, for example, 0.

[0113] A bit information transmitted by U-SIG can be divided into version-independent bits and version-dependent bits. For example, U-SIG may be included in a new PPDU format not shown in FIG. 7 (e.g., UHR PPDU format), and in the format of the U-SIG field included in the EHT PPDU format and the format of the U-SIG field included in the UHR PPDU format, the version-independent bits may be the same, and some or all of the version-dependent bits may be different.

[0114] For example, the size of the version-independent bits of U-SIG may be fixed or variable. The version-independent bits may be assigned only to U-SIG-1 symbols or to both U-SIG-1 and U-SIG-2 symbols. The version-independent bits and version-dependent bits may be referred to by various names, such as the first control bit and the second control bit.

[0115] For example, the version-independent bits of U-SIG may include a 3-bit physical layer version identifier (PHY version identifier), and this information may indicate the PHY version of the transmitted / received PPDU (e.g., EHT, UHR, etc.). The version-independent bits of U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication. The version-independent bits of U-SIG may include information regarding the length of the TXOP (transmission opportunity) and information regarding the BSS color ID.

[0116] For example, the version-dependent bits of U-SIG may contain information that directly or indirectly indicates the type of PPDU (e.g., SU PPDU, MU PPDU, TB PPDU, etc.).

[0117] Information necessary for PPDU transmission and reception may be included in the U-SIG. For example, the U-SIG may further include information regarding bandwidth, information regarding MCS techniques applied to non-legacy SIGs (e.g., EHT-SIG or UHR-SIG, etc.), information indicating whether DCM (dual carrier modulation) techniques (e.g., techniques to achieve an effect similar to frequency diversity by reusing the same signal on two subcarriers) are applied to non-legacy SIGs, information regarding the number of symbols used for non-legacy SIGs, and information regarding whether non-legacy SIGs are generated across the entire band.

[0118] Some of the information required for PPDU transmission and reception may be included in U-SIG and / or non-legacy SIGs (e.g., EHT-SIG or UHR-SIG, etc.). For example, information regarding the type of non-legacy LTF / STF (e.g., EHT-LTF / EHT-STF or UHR-LTF / UHR-STF, etc.), information regarding the length of non-legacy LTF and cyclic prefix (CP) length, information regarding guard interval (GI) applied to non-legacy LTF, information regarding preamble puncturing applicable to PPDU, information regarding resource unit (RU) allocation, etc., may be included only in U-SIG, may be included only in non-legacy SIG, or may be indicated by a combination of information included in U-SIG and information included in non-legacy SIG.

[0119] Preamble puncturing may refer to the transmission of a PPDU in which a signal is not present in one or more frequency units within the PPDU bandwidth. For example, the size of the frequency unit (or the resolution of preamble puncturing) may be defined as 20 MHz, 40 MHz, etc. For example, preamble puncturing may be applied to a PPDU bandwidth of a predetermined size or larger.

[0120] In the example of FIG. 7, non-legacy SIGs such as HE-SIG-B and EHT-SIG may include control information for the receiving STA. A non-legacy SIG may be transmitted through at least one symbol, and one symbol may have a length of 4 µs. Information regarding the number of symbols used for EHT-SIG may be included in the previous SIG (e.g., HE-SIG-A, U-SIG, etc.).

[0121] Non-legacy SIGs, such as HE-SIG-B and EHT-SIG, may include common fields and user-specific fields. Common fields and user-specific fields may be coded individually.

[0122] In some cases, the common field may be omitted. For example, in a compression mode where non-OFDMA (orthogonal frequency multiple access) is applied, the common field may be omitted, and multiple STAs may receive PPDUs (e.g., the data field of the PPDU) over the same frequency band. In a non-compression mode where OFDMA is applied, multiple users may receive PPDUs (e.g., the data field of the PPDU) over different frequency bands.

[0123] The number of user-specific fields can be determined based on the number of users. A single user block field can contain up to two user fields. Each user field may be related to MU-MIMO allocation or non-MU-MIMO allocation.

[0124] The common field may include CRC bits and Tail bits, the length of the CRC bits may be determined to be 4 bits, and the length of the Tail bits may be determined to be 6 bits and set to 000000. The common field may include RU allocation information. The RU allocation information may include information regarding the location of the RU to which a plurality of users (i.e., a plurality of receiving STAs) are allocated.

[0125] An RU may include multiple subcarriers (or tones). An RU may be used when transmitting signals to multiple STAs based on the OFDMA technique. Additionally, an RU may be defined when transmitting signals to a single STA. Resources may be allocated on an RU basis for non-legacy STF, non-legacy LTF, and Data fields.

[0126] Applicable RU sizes can be defined according to the PPDU bandwidth. RUs may be defined identically or differently for the applicable PPDU format (e.g., HE PPDU, EHT PPDU, UHR PPDU, etc.). For example, in the case of an 80 MHz PPDU, the RU placement for HE PPDU and EHT PPDU may differ. The applicable RU sizes, number of RUs, RU locations, DC (direct current) subcarrier locations and numbers, null subcarrier locations and numbers, and guard subcarrier locations and numbers for each PPDU bandwidth can be referred to as a tone-plan. For example, a tone-plan for a wide bandwidth may be defined as a multiple repetition of a tone-plan for a low bandwidth.

[0127] RUs of various sizes can be defined as 26-ton RUs, 52-ton RUs, 106-ton RUs, 242-ton RUs, 484-ton RUs, 996-ton RUs, 2x996-ton RUs, 4x996-ton RUs, etc. An MRU (multiple RU) is distinguished from multiple individual RUs and corresponds to a group of subcarriers composed of multiple RUs. For example, one MRU can be defined as 52+26-tons, 106+26-tons, 484+242-tons, 996+484-tons, 996+484+242-tons, 2x996+484-tons, 3x996-tons, or 3x996+484-tons. In addition, multiple RUs constituting a single MRU may be continuous or non-continuous in the frequency domain.

[0128] The specific size of the RU may be reduced or expanded. Accordingly, the specific size of each RU (i.e., the number of corresponding tones) in this disclosure is not limited and is exemplary. Additionally, within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, ...) in this disclosure, the number of RUs may vary depending on the RU size.

[0129] The names of the respective fields in the PPDU formats of FIG. 7 are exemplary and the scope of the present disclosure is not limited by such names. Furthermore, the examples of the present disclosure may be applied not only to the PPDU formats exemplified in FIG. 7, but also to new PPDU formats based on the PPDU formats of FIG. 7 in which some fields are excluded and / or some fields are added.

[0130] Multiple Access Point (MAP) Operation

[0131] Examples of the present disclosure regarding multiple access point (MAP) operations are described below.

[0132] MAP operation can be defined as operation between a master AP (or sharing AP) and a slave AP (or shared AP).

[0133] The master AP plays the role of initiating and controlling MAP operations for transmission and reception between multiple APs. The master AP groups slave APs and manages links with slave APs to enable information sharing among them. The master AP manages information about the BSS configured by the slave APs and information about the STAs that have formed an association with the BSS.

[0134] A slave AP forms a pair with a master AP and can share control information, management information, and data traffic. The slave AP performs the same basic functions as an AP, including establishing a BSS in a wireless LAN.

[0135] In MAP operation, the STA can form a BSS by combining with a slave AP or a master AP.

[0136] In a MAP environment, the master AP and slave AP can perform direct transmission and reception with each other. The master AP and STA may not be able to perform direct transmission and reception with each other. A slave AP (for example, a slave AP coupled with a STA) can perform direct transmission and reception with the STA. One of the slave APs can become the master AP.

[0137] MAP operation is a technique in which one or more APs transmit and receive information to one or more STAs. For example, techniques such as C-TDMA (coordinated-time division multiple access), which divides allocation between APs along the time axis; C-OFDMA (coordinated-orthogonal frequency division multiple access), which divides along the frequency axis; and C-SR (coordinated-spatial reuse), which utilizes spatial reuse, can be applied for MAP operation. Alternatively, MAP operation may also apply coordinated beamforming (C-BF) or joint beamforming techniques, which perform simultaneous transmission and reception in cooperation.

[0138] FIG. 8 is a diagram illustrating various transmission and reception techniques in a MAP environment to which the present disclosure can be applied.

[0139] As with the existing method, the transmission performed by a BSS AP to a BSS STA can be referred to as STX (single transmission). In STX, there is a problem where the transmission and reception performance for users / STAs located at the cell edge is degraded due to interference with adjacent APs. For example, as shown in Fig. 8(a), if AP1 and AP2 perform transmissions to STA1 and STA2 respectively at the same time in the same frequency band, a collision may occur on the wireless medium.

[0140] In MAP techniques, performance can be improved by reducing inter-symbol interference (ISI) through cooperation among neighboring APs or by performing joint transmissions. For example, in the C-OFDMA method of Fig. 8(b), interference can be avoided by AP1 transmitting to STA1 in the first bandwidth and AP2 transmitting to STA2 in the second bandwidth at the same time. The example in Fig. 8(c) illustrates a cooperative beamforming or nulling technique in which AP1 nulls the interference affecting AP2 and / or STA2 while transmitting to STA1, and AP2 nulls the interference affecting AP1 and / or STA1 while transmitting to STA2. Fig. 8(d) illustrates an AP selection method in which the AP with the best channel conditions among adjacent APs performs the transmission. As shown in the example of Fig. 8(e), joint transmission (JTX) or joint reception (JRX) in which multiple APs cooperate to transmit or receive simultaneously may be applied, and furthermore, joint MU-MIMO may be supported.

[0141] In the examples of the present disclosure, multiple AP operations are assumed to be performed as follows.

[0142] Step 1: Distribute resource areas to each AP via trigger frames from the master AP (i.e., AP-to-AP trigger frames, or master trigger frames).

[0143] Step 2: Each AP performs DL (i.e., from AP to STA) data transmission within its allocated resource area, or transmits a trigger frame (i.e., AP-to-STA trigger frame) for UL (i.e., from STA to AP) data transmission within its allocated resource area.

[0144] Step 3: The STA transmits a response to the DL data or transmits via UL data (e.g., TB PPDU).

[0145] If the resources distributed among APs are frequency resources, it corresponds to the C-OFDMA method; if they are time resources, it corresponds to the C-TDMA method; and if they are spatial resources (or beams), it corresponds to the CBF method. The examples described below are explained by assuming, typically, that the C-OFDMA method, that is, multi-AP operation is performed through resources distinguished in the frequency domain. However, the scope of the present disclosure is not limited thereto and may additionally or alternatively include multi-AP operation through resources distinguished in other domains (e.g., time domain and / or spatial domain).

[0146] Target Wake Time (TWT)

[0147] The following explains TWT (target wake time).

[0148] TWT is a Power Saving (PS) technology that can improve the energy efficiency of non-AP STAs by defining the Service Period (SP) between APs and non-AP STAs and sharing information about SPs to reduce contention. In the TWT Setup phase, an STA that performs requests, suggestions, or demands can be referred to as a Requesting STA. Additionally, an AP that responds to such requests by accepting or rejecting them can be referred to as a Responding STA. The Setup phase may include the process of determining or defining the STA's TWT request to the AP, the type of TWT operation to be performed, and the frame types to be transmitted and received. TWT operations can be classified into Individual TWT and Broadcast TWT.

[0149] FIG. 9 is a drawing illustrating an example of an individual TWT operation to which the present disclosure may be applied.

[0150] Individual TWT is a mechanism for AP and non-AP STA to perform data exchange after negotiating the awake / doze status of the non-AP STA through the transmission and reception of TWT request / response frames. In the example of Fig. 9, AP and STA1 can form a trigger-enabled TWT agreement through TWT request frames and TWT response frames. Here, the method used by STA1 is a solicited TWT method, in which STA1 transmits a TWT request frame to AP, and STA1 receives information for TWT operation from AP through a TWT response frame. On the other hand, STA2, which performs the unsolicited TWT method, can receive information regarding the setup of the trigger-enabled TWT agreement from the AP via an unsolicited TWT response. Specifically, STA2 can calculate the next TWT by adding a specific number to the current TWT value. During the trigger-enabled TWT SP, the AP can transmit a trigger frame to the STAs. The trigger frame can inform the STAs that there is buffered data in the AP. In this regard, STA1 can notify the AP of its awake state by transmitting a PS-Poll frame. Additionally, STA2 can notify the AP of its awake state by transmitting a QoS Null frame. Here, the data frames transmitted by STA1 and STA2 may be frames in the TB PPDU format. The AP that checks the status of STA1 and STA2 can send DL MU PPDU to the active STAs.When the TWT SP expires, STA1 and STA2 can transition to a doze state.

[0151] FIG. 10 is a drawing illustrating an example of a broadcast TWT operation to which the present disclosure may be applied.

[0152] Broadcast TWT is a type of TWT in which a non-AP STA (or TWT scheduling STA) obtains information regarding the target beacon transmission time (TBTT) and listen interval, etc., by transmitting and receiving TWT request / response frames with an AP (or TWT scheduled STA). Here, a negotiation operation regarding the TBTT may be performed. Based on this, the AP can define a frame containing the TWT scheduling information through a beacon frame. In FIG. 10, STA1 performs a request-type TWT operation, and STA2 performs an un-request-type TWT operation. The AP can transmit a DL MU PPDU after checking the awake status of the STAs through the trigger it transmitted. This may be identical to the process of an individual TWT. In a broadcast TWT, a trigger-enabled TWT SP containing a beacon frame can be repeated multiple times at a regular interval.

[0153] The transmission of TWT information can be achieved through TWT information frames and TWT information elements.

[0154] A TWT information frame is transmitted by an STA to request or transmit information about a TWT consensus, and is transmitted by one of the STAs of the existing TWT consensus. The action frame of the TWT information frame includes a TWT information field. The TWT Information field may include a 3-bit TWT flow identifier subfield, a 1-bit response requested subfield, a 1-bit next TWT request subfield, a 2-bit next TWT subfield size subfield, a 1-bit all TWT subfield, and a 0 / 32 / 48 / 64-bit next TWT subfield.

[0155] Figure 11 is a diagram illustrating an example of a TWT information element format.

[0156] TWT information elements may be transmitted or received by being included in beacons, probe responses, (re)combined response frames, etc. TWT information elements may include an element ID field, a length field, a control field, and a TWT parameter information field.

[0157] The control field of a TWT information element has the same format regardless of whether it is an individual TWT or a broadcast TWT.

[0158] The NDP paging indicator subfield can have a value of 1 if the NDP paging field exists, and a value of 0 if the NDP paging field does not exist.

[0159] The responder PM mode subfield can represent Power Management (PM) mode.

[0160] The negotiation type subfield may indicate whether the information contained in the TWT element is for negotiation of parameters of a broadcast TWT or individual TWT(s), or for a wake TBTT interval.

[0161] For example, if the value of the negotiation type subfield is 0, the TWT subfield is for a future individual TWT SP start time, and the TWT element contains a set of individual TWT parameters. This may correspond to an individual TWT negotiation between a TWT requesting STA and a TWT response STA, or to an individual TWT announcement by a TWT responder.

[0162] For example, if the value of the consultation type subfield is 1, the TWT subfield is for the next TBTT time, and the TWT element contains a single set of TWT parameters. This may correspond to the wake TBTT and wake interval consultation between the TWT-scheduled STA and the TWT-scheduling AP.

[0163] For example, if the value of the consultation type subfield is 2, the TWT subfield is for a future broadcast TWT SP start time, and the TWT element contains one or more sets of broadcast TWT parameters. This may correspond to providing a broadcast TWT schedule to a TWT-scheduled STA by including the TWT element in a broadcast management frame transmitted by the TWT scheduling AP.

[0164] For example, if the value of the consultation type subfield is 3, the TWT subfield is for a future broadcast TWT SP start time, and the TWT element contains one or more sets of broadcast TWT parameters. This may correspond to managing membership in a broadcast TWT schedule by including the TWT element in an individually addressed management frame transmitted by either the TWT-scheduled STA or the TWT-scheduled AP.

[0165] If the TWT information frame disabled subfield is set to 1, it indicates that reception of TWT information frames by the STA is disabled, otherwise it can be set to 0.

[0166] The wake duration unit subfield indicates the unit of the nominal minimum TWT wake duration field. The wake duration unit subfield can be set to 0 when the unit is 256us, and to 1 when the unit is TU. If it is not HE / EHT STA, the wake duration unit subfield can be set to 0.

[0167] The MSB (most significant bit) of the consultation type field may correspond to the broadcast field. If the broadcast field is 1, the TWT element may contain one or more sets of broadcast TWT parameters. If the broadcast field is 0, only one set of individual TWT parameters may be contained in the TWT element. A TWT element in which the broadcast field is set to 1 may be referred to as a broadcast TWT element.

[0168] FIG. 12 is a diagram illustrating examples of individual TWT parameter set field formats. FIG. 13 is a diagram illustrating examples of broadcast TWT parameter set field formats.

[0169] The TWT parameter information field included in the TWT element of Fig. 11 may have different configurations depending on the individual TWT or broadcast TWT.

[0170] In the case of an individual TWT, the TWT parameter information field within the TWT element contains a single individual TWT parameter set field.

[0171] In the case of a broadcast TWT, the TWT parameter information field within the TWT element includes one or more broadcast TWT parameter set fields. Each broadcast TWT parameter set may include specific information for a single broadcast TWT.

[0172] As illustrated in FIGS. 12 and 13, the individual TWT parameter set field and the broadcast TWT parameter set field include common subfields.

[0173] The request type subfield has the same size as the individual TWT parameter set field and the broadcast TWT parameter set field, but its detailed configuration may differ. This will be discussed later.

[0174] The target wake time subfield indicates the start time of an upcoming individual / broadcast TWT SP.

[0175] The nominal maximum TWT wake duration subfield represents the minimum unit that a TWT requesting STA expects to be woken up to complete frame exchanges associated with the TWT flow identifier during the TWT wake interval duration. Here, the TWT wake interval may refer to the average time between consecutive TWT SPs expected by the TWT requesting STA.

[0176] The TWT Wake Interval Mantissa subfield can be expressed in microseconds as the binary value of the TWT Wake Interval.

[0177] Referring to Fig. 12, the TWT group assignment subfield, TWT channel, and NDP paging subfield are included only in the individual TWT parameter set fields.

[0178] The TWT group assignment subfield contains information about the TWT group to which the STA is assigned and provides it to the TWT requesting STA. This information can be used to calculate the TWT value within the TWT group. The STA's TWT value may be equal to the zero offset value and the TWT offset value multiplied by the TWT unit value.

[0179] The TWT channel subfield represents a bitmap indicating an allowed channel. When transmitted by a TWT request STA, the TWT channel subfield may contain a bitmap indicating a channel that the STA requests to use as a temporary default channel during the TWT SP. When transmitted by a TWT response STA, the TWT channel subfield may contain a bitmap indicating a channel that the TWT request allows.

[0180] The NDP paging subfield is optional and may include information such as the identifier of the STA being paged and the maximum number of TWT wake intervals between NDP paging frames.

[0181] Referring to FIG. 13, the broadcast TWT info subfield is included only in the broadcast TWT parameter set field. The broadcast TWT info subfield may include a 3-bit reserve bit, a 5-bit broadcast TWT identifier (ID) subfield, and an 8-bit broadcast TWT persistence subfield. The broadcast TWT identifier subfield indicates the broadcast ID of a specific broadcast TWT that the STA requests to join or provides TWT parameters for, depending on the value of the TWT setup command subfield of the TWT element. The broadcast TWT persistence subfield indicates the number of TBTTs planned on the broadcast TWT schedule.

[0182] Next, the detailed configuration of the request type subfield is explained.

[0183] First, with reference to Fig. 12, the format of the request type subfield of the individual TWT parameter set field will be explained.

[0184] The TWT request subfield can indicate whether it is a request STA or a response STA. If the value is 1, it indicates that it is a TWT request STA or a scheduled STA, and if it is 0, it indicates that it is a TWT response STA or a scheduling AP.

[0185] The TWT setup command subfield can represent commands such as Request, Suggest, Demand, Accept, Alternate, Dictate, and Reject.

[0186] The trigger subfield indicates whether to use trigger frames in the TWT SP. If the value is 1, the trigger is used, and if it is 0, the trigger may not be used.

[0187] The implicit subfield can indicate whether it is an implicit TWT or an explicit TWT. If the value is 1, it indicates an implicit TWT, and if it is 0, it indicates an explicit TWT.

[0188] The flow type subfield may indicate the type of interaction between the TWT requesting STA (or the STA being scheduled for TWT) and the TWT responding STA (or the AP scheduling for TWT). If the value is 1, it may indicate an announced TWT, where the STA sends a wake-up signal to the AP by transmitting a PS-Poll or APSD (automatic power save delivery) trigger frame before a non-trigger frame is transmitted from the AP to the STA. If the value is 0, it may indicate an unannounced TWT.

[0189] The TWT flow identifier subfield may include a 3-bit value that uniquely identifies specific information about the TWT request in other requests made between the same TWT request STA and TWT response STA pair.

[0190] The TWT wake interval exponent subfield allows setting the TWT wake interval value in binary microseconds. For individual TWTs, it may refer to the interval between individual TWT SPs. The TWT wake interval of a request STA can be defined as [TWT Wake Interval Mantissa * 2 * TWT Wake Interval Exponent].

[0191] The TWT protection subfield may indicate whether a TWT protection mechanism is used. If the value is 1, the TXOP within the TWT SP may be initiated by a NAV protection mechanism such as (MU)RTS / CTS or CTS-to-self frames, and if it is 0, the NAV protection mechanism may not be applied.

[0192] Referring to Fig. 13, some of the subfields of the request type subfield of the broadcast TWT parameter set field are common to the subfields of the request type subfield of the individual TWT parameter set field, so a description thereof is omitted. The subfields included only in the broadcast TWT parameter set are described below.

[0193] The Last Broadcast Parameter Set subfield indicates whether it is the last broadcast TWT parameter set. If the value is 1, it indicates that it is the last broadcast TWT parameter set, and if it is 0, it indicates that the next broadcast TWT parameter set exists.

[0194] The broadcast TWT recommendation subfield can represent recommendations for frame types transmitted by the AP during the broadcast TWT SP with values ​​from 1 to 7.

[0195] The last bit of the request type subfield of the broadcast TWT parameter set field can be reserved.

[0196] With the recent surge in wired and wireless traffic, latency-sensitive traffic has also increased significantly. Latency-sensitive traffic includes real-time audio and video transmission, and the need to support this in wireless environments has grown with the proliferation of multimedia devices. However, compared to wired environments, there are many factors to consider when supporting latency-sensitive traffic in wireless environments. This is because wireless environments have lower transmission speeds than wired environments, and issues regarding interference from the surroundings must also be taken into account. In particular, in wireless LAN systems, since multiple STAs must compete equally for media occupancy in the ISM (Industry-Science-Medical) band, it is relatively more difficult to support latency-sensitive traffic compared to cellular communication networks based on wireless resource scheduling by a central base station. This disclosure describes a new method for supporting latency-sensitive traffic in wireless LAN systems.

[0197] In the present disclosure, latency may refer to latency as defined in IEEE 802.11 series standards. For example, it may refer to the time from when a frame to be transmitted enters the queue of the MAC layer of a transmitting STA, until the transmission by the transmitting STA is successfully completed at the PHY layer, and until the transmitting STA receives an ACK / block ACK, etc. from a receiving STA and the corresponding frame is deleted from the queue of the transmitting STA's MAC layer. Additionally, in the present disclosure, a non-AP STA that supports the transmission of latency-sensitive data may be referred to as a Low Latency STA. Furthermore, data other than latency-sensitive data may be referred to as regular data.

[0198] Restricted TWT (r-TWT) can support the AP in securing priority data transmission possibilities for low-latency STAs over other STAs by establishing a special broadcast TWT for low-latency STAs transmitting latency-sensitive data. An STA can establish membership for one or more r-TWT schedules with respect to the AP. Here, r-TWT consensus can be established through the same process as broadcast TWT consensus, and for this purpose, broadcast TWT elements can be defined to include an r-TWT parameter set field. For example, the r-TWT parameter set may refer to a specific broadcast TWT parameter set field that is distinct from other broadcast TWT parameter set fields. That is, the r-TWT parameter set field may correspond to a special case of the broadcast TWT parameter set field. Additionally, the AP can announce the r-TWT SP.

[0199] Basically, if another STA that supports r-TWT operation is a TXOP holder, the TXOP must be ended before the start time of the r-TWT SP advertised by the combined AP. Accordingly, the STA associated with the r-TWT (i.e., the low-latency STA) can perform traffic transmission and reception preferentially over the other STA within the r-TWT SP.

[0200] In the present disclosure, as described above, a low-latency STA associated with a specific r-TWT is referred to as a member r-TWT scheduled STA, and other STAs are referred to as non-member STAs. A non-member STA may be a STA that has the capability to support r-TWT operation but is not a member of any r-TWT, a STA that supports r-TWT operation and is a member of another r-TWT, or a STA that does not have the capability to support r-TWT operation.

[0201] A STA that supports the limited SP (or r-TWT SP) operation of a broadcast TWT (e.g., a low-latency STA) may notify the AP that it needs to transmit latency-sensitive data based on the r-TWT operation. If the AP supports the r-TWT operation / mode, the AP may transmit a frame containing scheduling information for the TWTs requested by each STA to the low-latency STA and other STA(s). For example, to perform an operation for an r-TWT, non-AP STAs may obtain r-TWT related information from the AP via a beacon frame, a probe response frame, a (re)join response frame, or other frames in an as-yet-undefined format (e.g., a broadcast, advertisement, or announcement frame).

[0202] According to restricted TWT operations, a separate TXOP (i.e., access by other STAs is restricted) can be secured within an r-TWT SP using a NAV such as (MU) RTS / CTS or CTS-to-self, or a quiet interval. Before a specific r-TWT SP starts, if there is a TXOP of a STA other than the STA that has membership in the specific r-TWT schedule (i.e., a non-member STA), it must be stopped. The TXOP of the other STA (i.e., a non-member STA) may be additionally executed after the specific r-TWT SP ends.

[0203] Negotiation and announcement of protection levels related to TWT coordination

[0204] In a multi-BSS environment, when APs are located within a range where they can receive beacon frames from each other, an overlapping BSS (OBSS) range can be formed, in which the transmission and reception ranges (i.e., BSS) of the APs overlap.

[0205] FIG. 14 is a diagram illustrating exemplary APs and STAs in an OBSS to which the present disclosure may be applied.

[0206] As illustrated in FIG. 14, the signaling range of AP1 (e.g., the range corresponding to BSS 1) and the signaling range of AP2 (e.g., the range corresponding to BSS 2) may overlap. In this way, when AP1 and AP2 are located within a range where they can receive (i.e., overhear) each other, AP1 and AP2 can negotiate for coordination regarding their respective scheduled R-TWT SP (service period) through (wireless / wired) communication. This case corresponds to the situation where AP1 and AP2 are located within the range of an OBSS where their transmission and reception ranges overlap, unlike the case where AP1 and AP2 are hidden nodes.

[0207] In this regard, STAs located within the overlapping range can receive beacon frames from APs with which they have formed an association, as well as beacon frames from APs with which they have not formed an association. For example, STA 1-2 can receive beacon frames from AP1 with which they have formed an association, and can also receive (i.e., overhear) beacon frames from AP2 with which they have not formed an association. For example, STA 2-3 can receive beacon frames from AP2 with which they have formed an association, and can also receive (i.e., overhear) beacon frames from AP1 with which they have not formed an association.

[0208] The examples of the present disclosure are not limited to the situations of APs and / or STAs exemplified in FIG. 14, but may be applied to various situations where consultation regarding the cooperation service period between APs is required. For example, AP1 may be in a location / situation where it can receive AP2's beacon frame, and AP2 may be in a location / situation where it cannot receive AP1's beacon frame. Alternatively, AP1 and AP2 may be in a location / situation where they can receive each other's beacon frames. Alternatively, AP1 may be in a location / situation where it cannot receive AP2's beacon frame, and AP2 may be in a location / situation where it can receive AP1's beacon frame.

[0209] Beacon frames may contain restricted-TWT (R-TWT) scheduling information assigned by an AP to STAs associated with it, and STAs receiving R-TWT scheduling information are required to protect an R-TWT SP to which they are not members (e.g., if the STA's TXOP is in progress before the start time of the R-TWT SP as previously described, the TXOP is terminated). In other words, a STA receiving a beacon frame containing R-TWT scheduling information may be in a position where it must protect the R-TWT SP. Meanwhile, if an STA receives R-TWT scheduling information advertised by an unassociated (or neighboring) AP, it is not yet defined whether it must protect the R-TWT SP or transmit / receive low-latency traffic / data during the R-TWT SP.

[0210] The present disclosure describes a method for performing negotiation for coordination of an R-TWT based on scheduling information for an R-TWT scheduled by a combined AP (e.g., AP1) and / or scheduling information for an R-TWT scheduled by an uncombined (or neighboring) AP (e.g., AP2). In the following description, to distinguish it from an R-TWT SP scheduled by a combined AP (e.g., which may be referred to as a BSS R-TWT SP), an R-TWT SP scheduled by another AP (e.g., an uncombined AP or a neighboring AP) is referred to as an OBSS R-TWT SP. The scope of the present disclosure is not limited by the designation OBSS R-TWT.

[0211] In this disclosure, the case where a cooperation request is transmitted by a coupled AP and a cooperation response is transmitted by an uncoupled (or neighboring) AP is described primarily as a representative example; however, for the sake of clarity of explanation, the method proposed in this disclosure may also be applied to the case where a cooperation request is transmitted by an uncoupled (or neighboring) AP and a cooperation response is transmitted by a coupled AP.

[0212] AP1 and AP2 of FIG. 14 may, for example, belong to the same multi-AP (MAP) group. They may correspond to slave APs in a MAP operation having the same master AP. Alternatively, either AP1 or AP2 may correspond to the master AP in a MAP operation.

[0213] In the present disclosure, negotiation for R-TWT coordination can be performed based on R-TWT schedule information set by AP1 for STAs combined with AP1 and R-TWT schedule information set by AP2 for STAs combined with AP2. During the negotiation process between two APs, in response to a request for cooperation / negotiation from another AP, the AP may transmit a cooperation / negotiation response, and the cooperation / negotiation response may include information signaling the status of the cooperation / negotiation request.

[0214] In this disclosure, it is assumed that the APs performing cooperation / consultation are APs whose BSS overlaps. One of the APs corresponds to an associated AP in terms of a specific STA, and the other AP may correspond to a neighboring AP or an OBSS AP. For example, in terms of the STA associated with the first AP, the first AP may be an associated AP and the second AP may be an OBSS AP. In terms of the STA associated with the second AP, the second AP may be an associated AP and the first AP may be an OBSS AP.

[0215] The following describes a method for negotiating the degree / level of protection within another AP's BSS regarding the R-TWT schedule of a specific AP that is the subject of the negotiation during the Multi-AP Cooperation (MAPC) negotiation process. Additionally, the following describes a method for an AP to announce the degree / level of protection regarding another AP's R-TWT schedule within its own BSS during the R-TWT cooperation negotiation process.

[0216] FIG. 15 is a drawing showing an example of the operation of a first AP according to the present disclosure.

[0217] In the example of Fig. 15, the first AP is a multi-AP cooperation response AP, and the second AP may correspond to a multi-AP cooperation request AP.

[0218] In step S1510, the first AP can receive a consultation request frame for the MAPC from the second AP.

[0219] In some examples, the consultation request frame may include information related to protection for a specific TWT schedule.

[0220] In some examples, information regarding protection for a specific TWT schedule may correspond to a level of protection or a scope of protection regarding which entity(s) provide protection for a specific TWT schedule. For example, the entity providing protection for a specific TWT schedule may be a first AP, a part of the STA combined with the first AP, all of the STA combined with the first AP, the first AP and a part of the STA combined with the first AP, or the first AP and all of the STA combined with the first AP.

[0221] In some examples, the consultation request frame may include reference information related to protection for a specific TWT schedule. This reference information may be included together with or separately from information related to protection for a specific TWT schedule.

[0222] In some examples, the reference information may include a reference value related to OBSS PD (overlapping basic service set packet detect)-based spatial reuse. Additionally, or alternatively, the reference information may include a threshold related to received signal strength.

[0223] In some examples, based on reference information, protection by subject(s) for a specific TWT schedule may be provided. For example, the subject providing protection for a specific TWT schedule may be a first AP, a part of the STA combined with the first AP, all of the STA combined with the first AP, the first AP and a part of the STA combined with the first AP, or the first AP and all of the STA combined with the first AP.

[0224] In some examples, protection for a specific TWT schedule may include the TXOP holder ensuring that the transmission opportunity (TXOP) ends before the start time of the specific TWT schedule.

[0225] In some examples, a specific TWT may correspond to an R-TWT.

[0226] In step S1520, the first AP can transmit a consultation response frame for the MAPC to the second AP.

[0227] In some examples, the consultation response frame may include information indicating acceptance or rejection of cooperation for a specific TWT schedule.

[0228] In some examples, the consultation response frame may include information regarding the level or scope of protection regarding which entity(s) provide protection for a specific TWT schedule. For example, the entity providing protection for a specific TWT schedule may be the first AP, some of the STAs combined with the first AP, all of the STAs combined with the first AP, the first AP and some of the STAs combined with the first AP, or the first AP and all of the STAs combined with the first AP.

[0229] In some examples, the first AP may notify the STA(s) corresponding to the subject of protection for the specific TWT schedule (e.g., some or all of the STAs combined with the first AP) of information related to the specific TWT schedule. If the first AP is the only subject of protection for the specific TWT schedule, information related to the specific TWT schedule may not be notified to the STAs combined with the first AP.

[0230] In some examples, information related to a specific TWT schedule (e.g., information announced by the first AP) may indicate that the specific TWT schedule is a protected TWT schedule.

[0231] In some examples, information related to a specific TWT schedule (e.g., information announced by the first AP) may indicate that the specific TWT schedule is a trigger-enabled broadcast TWT schedule.

[0232] In some examples, the first AP may announce reference information related to protection for a specific TWT schedule to some or all of the STAs coupled with the first AP. For example, the reference information may include reference values ​​related to overlapping basic service set packet detect (OBSS PD)-based spatial reuse, and / or thresholds related to received signal strength.

[0233] The method described in the example of FIG. 15 may be performed by the first device (100) of FIG. 1. For example, one or more processors (102) of the first device (100) (or the first AP) of FIG. 1 may be configured to receive a consultation request frame for MAPC containing information related to protection for a specific TWT schedule from the second device (200) via one or more transceivers (106), and to transmit a consultation response frame for MAPC to the second device (200) via one or more transceivers (106). Furthermore, one or more memories (104) of the first device (100) may store instructions for performing the method described in the example of FIG. 15 or the examples described below when executed by one or more processors (102).

[0234] For example, when a PPDU is received from a second device (200) through one or more transceivers (106), one or more processors (102) of the first device (100) can parse a MAC frame obtained through PHY decoding of the data field of the PPDU, obtain information related to a consultation request and protection for a specific TWT schedule included in the consultation request based on the decoded data from the parsed MAC frame, and determine whether to accept the consultation request based thereon. Additionally, the processor (202) can generate a MAC frame containing information indicating acceptance or rejection of the consultation request, generate a PPDU containing the same, and transmit it to the second device (200) through one or more transceivers (106). Additionally, if the first device (100) needs to notify the STA(s) coupled with it of information for protection regarding a specific TWT schedule, it can generate a MAC frame containing the information to be notified and generate a PPDU containing the same and transmit it to the STAs through one or more transceivers (106).

[0235] FIG. 16 is a drawing illustrating an example of the operation of a second AP according to the present disclosure.

[0236] In the example of Fig. 15, the second AP is a multi-AP cooperation request AP, and the first AP may correspond to a multi-AP cooperation response AP.

[0237] In step S1610, the second AP may send a consultation request frame for MAPC to the first AP. This consultation request frame may include information related to protection for a specific TWT schedule.

[0238] In step S1620, the second AP can receive a consultation response frame for the MAPC from the first AP.

[0239] In the example of Fig. 16, the specific descriptions of the first AP, second AP, consultation request frame, consultation response frame, information related to protection, etc. are the same as those in the example of Fig. 15, so redundant descriptions are omitted.

[0240] The method described in the example of FIG. 16 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 (e.g., the second AP) may be configured to transmit a consultation request frame for MAPC containing information related to protection for a specific TWT schedule to the first device (100) via one or more transceivers (206), and to receive a consultation response frame for MAPC from the first device (100) via one or more transceivers (206). Furthermore, one or more memories (204) of the second device (200) may store instructions for performing the method described in the example of FIG. 16 or the examples described below when executed by one or more processors (202).

[0241] For example, the processor (202) may generate a MAC frame containing information related to protection for a specific TWT schedule and generate a PPDU containing the same and transmit it to the first device (100) through one or more transceivers (206). When the PPDU is received from the first device (100) through one or more transceivers (206), one or more processors (202) of the second device (200) may parse the MAC frame obtained through PHY decoding of the data field of the PPDU and confirm the acceptance or rejection of the consultation request by the first device (100) based on the data decoded from the parsed MAC frame.

[0242] The first AP in FIG. 15 corresponds to a transmitting STA (or requesting AP), and the second AP in FIG. 16 corresponds to a receiving STA (or response AP). For example, the transmitting STA may generate and transmit a cooperation / consultation request based on information regarding an R-TWT schedule (or R-TWT SP) to proceed with cooperation with the receiving STA before configuring the PPDU, information for consultation regarding the cooperation target, and information regarding the protection level for the R-TWT SP within the receiving STA's BSS. Based on the data included in the received cooperation / consultation request, the receiving STA may generate and transmit a cooperation / consultation response including a status code indicating acceptance / rejection based on whether protection can be applied to a specific R-TWT schedule within its BSS, utilizing the cooperation TWT ID included in the cooperation / consultation request. If the receiving STA recommends or proposes an alternative to a specific R-TWT schedule in the cooperation / consultation request of the sending STA, the receiving STA may generate and transmit a cooperation / consultation response containing a parameter set in which the values ​​of some or all of the parameter sets of the R-TWT schedule corresponding to the cooperation TWT ID have been changed. If the receiving STA determines that it can apply protection for the R-TWT schedule within its BSS according to the protection level included in the cooperation / consultation request, it may notify the STAs within its BSS of information regarding protection for the specific R-TWT schedule.

[0243] The examples of FIGS. 15 and 16 may correspond to some of the various examples of the present disclosure. Hereinafter, various examples of the present disclosure including the examples of FIGS. 15 and 16 will be described in more detail.

[0244] In the embodiments described below, examples of the present disclosure are explained by assuming two APs where neighbors or BSSs (partially) overlap, but the scope of the present disclosure is not limited thereto, and the examples of the present disclosure can be equally applied to the consultation process regarding the cooperation service period between three or more APs / BSSs.

[0245] In the following examples, the term "field" may be replaced with "subfield," and the term "subfield" may be replaced with "field." Additionally, in the following examples, the term "element" may be replaced with "subelement," and the term "subelement" may be replaced with "element."

[0246] Example 1

[0247] This embodiment relates to a general consultation process for R-TWT cooperation among APs.

[0248] As shown in Fig. 14, APs can perform consultation via wireless communication in a topology where the other party's BSS and their own BSS overlap. If wireless communication between APs is not possible, consultation may be performed via wired communication. Additionally, if there is a master AP of a MAP group to which the APs belong in common, wireless / wired consultation between APs may be performed through the master AP. For example, cooperation / consultation requests and cooperation / consultation responses in the examples described below may be transmitted / received through direct wireless / wired communication between APs, or indirectly transmitted / received through another AP (e.g., master AP).

[0249] In the present disclosure, it may be assumed that a consultation for cooperation is initiated whether the AP has prior knowledge of information regarding an R-TWT SP (or R-TWT schedule) scheduled by a neighboring AP or not. As a case where the AP obtains / shares information regarding the neighboring AP's R-TWT schedule in advance, for example, the case where the AP overhears the neighboring AP's beacon frame may be assumed, but the scope of the present disclosure is not limited to such a case.

[0250] In the examples described below, a request for cooperation may correspond to a request for consultation regarding cooperation and may simply be referred to as a request for consultation. Similarly, in the examples described below, a cooperation response may correspond to a consultation response regarding cooperation and may simply be referred to as a consultation response. Therefore, in the examples described below, a request for cooperation and a cooperation response may be replaced by a request for consultation and a consultation response, respectively.

[0251] In the examples of the present disclosure, the cooperation request and the cooperation response may be defined as a new frame or as a new element transmitted together with other information / elements.

[0252] In the examples of the present disclosure, it is assumed that the AP transmitting the cooperation request and the AP receiving the cooperation response correspond to one identical AP, and that the AP receiving the cooperation request and the AP transmitting the cooperation response correspond to another identical AP. However, the scope of the present disclosure may include cases where the AP transmitting the cooperation request and the AP receiving the cooperation response correspond to different APs, and / or cases where the AP receiving the cooperation request and the AP transmitting the cooperation response correspond to different APs.

[0253] In the present disclosure, an AP can determine / obtain a cooperative R-TWT (e.g., an R-TWT schedule subject to cooperation between APs) based on the result of wireless / wired consultation for cooperation regarding an R-TWT SP with neighboring APs.

[0254] For example, the consultation process for cooperation between an AP (e.g., AP1) and a neighboring AP (e.g., AP2) can be carried out in a 2-way manner as follows.

[0255] Step 1) AP1 sends a cooperation request to neighbor AP2.

[0256] Step 2) Neighbor AP2, having received the cooperation request, sends a cooperation response to AP1, which sent the cooperation request.

[0257] Based on the results of the consultation, R-TWT SP(s) may be classified into cooperative R-TWT SPs or non-cooperative (or non-cooperative) R-TWT SPs.

[0258] For example, if the status code included in the cooperation response in Step 2 indicates acceptance of the request in Step 1, it is interpreted that the consultation for cooperation has been successfully completed, and the R-TWT SP can be considered as a cooperative R-TWT SP between the AP participating in the consultation and a neighboring AP.

[0259] Alternatively, if the status code included in the cooperation response in Step 2 indicates a rejection of the request in Step 1, the AP may resend the cooperation request to a neighboring AP. In this case, the information of the R-TWT SP included in the cooperation request sent in Step 1 during the previous consultation process, or information that is identical or changed, may be included in the resent cooperation request. If the last cooperation response received from the neighboring AP during the consultation process following the resent consultation request indicates a rejection, the consultation is interpreted as rejected (or failed), and the R-TWT SP may be considered a non-cooperative R-TWT SP between the AP participating in the consultation and the neighboring AP.

[0260] Alternatively, the status code included in the cooperation response in Step 2 may not be an acceptance of the request in Step 1 but may include a proposal (e.g., REJECTED_WITH_SUGGESTED_CHANGES). In this case, the AP sending the cooperation response may send a value containing its own proposal through the cooperation response based on the values ​​included in the received cooperation request.

[0261] As another example, the consultation process for cooperation between an AP (e.g., AP1) and a neighboring AP (e.g., AP2) may be carried out in a 3-way manner as follows.

[0262] Step 1) AP1 sends the first cooperation request to neighbor AP2.

[0263] Step 2) Neighbor AP2, having received the cooperation request, may send a first cooperation response to AP1, which sent the cooperation request, and may include a second cooperation request containing R-TWT information scheduled by neighbor AP2, which sent the cooperation request, within the frame containing the first cooperation response.

[0264] Step 3) AP1, having received a frame containing a first cooperation response and a second cooperation request, can transmit a second cooperation response to the second cooperation request to neighbor AP2.

[0265] Example 2

[0266] The present embodiment relates to a method in which an AP transmitting a cooperation / consultation request (e.g., a requesting AP) includes within the cooperation / consultation request a new (sub)field indicating a level / range of protection within the BSS of an AP receiving a cooperation / consultation request (e.g., a responding AP) for a cooperation R-TWT schedule (Co-RTWT) specified in the cooperation / consultation request.

[0267] According to the present embodiment, the cooperation / consultation response AP does not arbitrarily determine and perform protection for the Co-RTWT schedule, but rather the cooperation / consultation request AP can specify the (requested) protection level / range for the Co-RTWT schedule and provide it to the response AP during the consultation process. Accordingly, unlike the application of full protection for the Co-RTWT during the consultation process without considering the protection level / range, flexible protection for the Co-RTWT according to various protection levels / ranges can be supported.

[0268] The protection level information included in the cooperation / consultation request frame may be referred to as information regarding protection recommendation, degree, range, etc. The (sub)field containing the protection level information may be included within an element containing information about the cooperation / consultation request (e.g., a TWT element), a field (e.g., an individual TWT parameter set field, a broadcast TWT parameter set field), a new element, or a new field.

[0269] The protection level information may correspond to the protection level for an OBSS R-TWT (e.g., a cooperating OBSS R-TWT) that is consulted with the requesting AP (e.g., an AP sending the cooperation / consultation request) within the BSS of the responding AP (e.g., an AP receiving the cooperation / consultation request). The value of the (sub)field containing this protection level information may indicate one or more of various protection levels. The higher the protection level, the more subjects may protect the R-TWT, and the lower the protection level, the fewer subjects may protect the R-TWT.

[0270] For example, a level can be defined where only the responding AP (e.g., the AP receiving the cooperation / consultation request) protects the schedule of the R-TWT included in the cooperation / consultation request.

[0271] For example, a level of protection can be defined for the response AP (e.g., an AP receiving a cooperation / consultation request) and the STAs combined with the response AP (e.g., all combined STAs) to protect the schedule of the R-TWT included in the cooperation / consultation request. This may correspond to a protection level that is applied by default even when cooperation / consultation based on the protection level is not applied.

[0272] For example, a level may be defined in which a response AP (e.g., an AP receiving a cooperation / consultation request) and some of the STAs coupled with the response AP protect the schedule of an R-TWT included in the cooperation / consultation request. Here, some of the coupled STAs may correspond to STA(s) affected by the schedule of an R-TWT included in the cooperation / consultation request. The remaining STA(s) may not be substantially affected by the said R-TWT schedule or may not perform protection for the said R-TWT schedule.

[0273] For example, a level can be defined in which STAs combined with the response AP (e.g., all combined STAs) (excluding the response AP) protect the schedule of the R-TWT included in the cooperation / consultation request.

[0274] For example, a level can be defined in which some of the STAs combined with the response AP (excluding the response AP) protect the schedule of the R-TWT included in the cooperation / consultation request.

[0275] The protection level (sub)field may indicate one or more protection levels among indices (e.g., indices from 0 to N corresponding to different protection levels). Alternatively, the protection level (sub)field may indicate one or more protection levels in the form of a bitmap (e.g., bit positions corresponding to different protection subjects, or bit positions corresponding to different protection levels). For example, at the xyz bit positions, x may correspond to the response AP, y may correspond to all STAs associated with the response AP, and z may correspond to some of the STAs associated with the response AP. The values ​​of the protection level (sub)field and the protection levels based on this bitmap format may correspond as shown in the table below.

[0276] xyz Protection Level 100: Only the responding AP (e.g., the AP receiving the cooperation / consultation request) protects the schedule of the R-TWT included in the cooperation / consultation request. Level 010 (excluding the responding AP): The STAs coupled to the responding AP (e.g., all coupled STAs) protect the schedule of the R-TWT included in the cooperation / consultation request. Level 001 (excluding the responding AP): Some of the STAs coupled to the responding AP protect the schedule of the R-TWT included in the cooperation / consultation request. Level 110: The responding AP (e.g., the AP receiving the cooperation / consultation request) and the STAs coupled to the responding AP (e.g., all coupled STAs) protect the schedule of the R-TWT included in the cooperation / consultation request. Level 101: The responding AP (e.g., the AP receiving the cooperation / consultation request) and some of the STAs coupled to the responding AP protect the schedule of the R-TWT included in the cooperation / consultation request.

[0277] Examples of distinguishing some STAs from others among those combined with a response AP are described below. Some STAs and other STAs can be distinguished by whether the STAs combined with the response AP are affected by the R-TWT schedule included in the cooperation / consultation request. To this end, information / fields representing a value serving as a criterion for distinguishing whether they are affected by the R-TWT schedule included in the cooperation / consultation request may be included in the cooperation / consultation request.

[0278] For example, these criterion values ​​may correspond to parameter values ​​utilized in the OBSS PD (overlapping basic service set packet detect)-based spatial reuse method. For instance, an OBSS PD-related reference value may be applied to determine whether the responding AP detects an OBSS packet. OBSS packets with a strength lower than or less than the OBSS PD-related reference value may be considered unaffected by the OBSS R-TWT schedule. Alternatively, OBSS packets with a strength greater than or higher than the OBSS PD-related reference value may be considered affected by the OBSS R-TWT schedule. In this way, the requesting AP can set the criteria for determining whether an OBSS R-TWT is affected to the responding AP.

[0279] When a response AP that has received a request for cooperation / consultation notifies the STAs that are joined to it about the OBSS R-TWT being cooperated with, it may also notify information / fields regarding the reference values ​​related to the OBSS PD. Through this, each STA can determine whether it falls within the OBSS's sphere of influence based on the specific OBSS PD-related reference values ​​included in the request for cooperation / consultation within the BSS of the response AP that has received the request for cooperation / consultation.

[0280] STAs combined with the responding AP may compare the OBSS PD value to be applied when detecting / receiving OBSS data based on their transmission power with the OBSS PD-related reference value (hereinafter referred to as OBSS PD_ref) specified in the cooperation / consultation request (also announced by the responding AP). For example, if the OBSS PD value matching the transmission power of a certain STA is greater than or equal to the OBSS PD_ref value, it corresponds to a case where the transmission power of the STA is low enough not to affect OBSS transmission, and accordingly, the STA may not perform protection against the OBSS R-TWT SP. Or, if the OBSS PD value matching the transmission power of a certain STA is less than or equal to the OBSS PD_ref value, it corresponds to a case where the transmission power of the STA is high enough to affect OBSS transmission, and accordingly, the STA may perform protection against the OBSS R-TWT SP. Through this, the problem of overprotection of OBSS R-TWT can be prevented.

[0281] Additionally or alternatively, the STA coupled with the responding AP may adjust its transmit power during the Co-RTWT schedule announced by the responding AP so that the OBSS PD value matching its transmit power is set high enough to be greater than (or exceed) the OBSS PD_ref value (e.g., so that its transmit power is lowered to a level that does not affect OBSS transmission). Thus, before the STA adjusts its transmit power, it may be subject to or give interference in data transmission and reception during the Co-RTWT schedule, but after adjusting its transmit power based on the OBSS PD_ref value, it may not be subject to or give interference in data transmission and reception during the Co-RTWT schedule.

[0282] Additionally or alternatively, a specific threshold corresponding to a value serving as a criterion for distinguishing whether STAs combined with the response AP receiving the cooperation / consultation request are affected by the Co-RTWT schedule may be included within the cooperation / consultation request. For example, such a specific threshold may be included within the cooperation / consultation request as a new (sub)field.

[0283] A response AP that receives such a cooperation / consultation request may notify the STAs coupled with it of information regarding the Co-RTWT, and may include a (sub)field containing the relevant threshold. Through this, if the signal strength received or decoded by the STA coupled with the response AP is below (or less than) the specific threshold (included in the cooperation / consultation request) notified by the response AP, protection for the corresponding Co-RTWT schedule may not be performed. Alternatively, if the signal strength received or decoded by the STA coupled with the response AP is above (or greater than) the specific threshold (included in the cooperation / consultation request) notified by the response AP, protection for the corresponding Co-RTWT schedule may be performed. Through this, the problem of overprotection regarding the OBSS R-RTWT can be prevented.

[0284] Additionally or alternatively, the responding AP that has received the cooperation / consultation request may include in the cooperation / consultation response information indicating to what level of protection to perform within its BSS for the Co-RTWT schedule included in the cooperation / consultation request, and transmit this information to the requesting AP. The reference values ​​and / or specific thresholds related to OBSS PD-based space reuse included in the aforementioned cooperation / consultation request may correspond to criteria related to the protection level presented by the requesting AP to the responding AP. Alternatively, the information related to the protection level included in the cooperation / consultation response may correspond to information presenting to the requesting AP the protection level that the responding AP can support.

[0285] The protection level (sub)field may not be included in the cooperation / consultation request but only in the cooperation / consultation response. For example, if a response AP that has received a cooperation / consultation request instructs the status code of the R-TWT schedule included in the cooperation / consultation request to accept, it may use the protection level (sub)field to instruct the AP sending the cooperation / consultation request on what level of protection to perform within its BSS for the cooperation OBSS R-TWT.

[0286] Alternatively, the cooperation / consultation response may include a protection level (sub)field with a value different from that of the protection level (sub)field in the cooperation / consultation request (e.g., a protection level different from the requested protection level). In this case, the status code of the cooperation / consultation response may correspond to Reject or Alternate, rather than Accept.

[0287] Example 3

[0288] This embodiment relates to a method of announcing or not announcing information about R-TWTs (Co-RTWTs) that cooperate with the response AP to STAs combined with the response AP, depending on the protection level / range.

[0289] Whether the responding AP provides notice may be determined by whether protection for the Co-RTWT schedule by some or all of the STAs associated with the responding AP is required. Protection for the Co-RTWT schedule by the AP that provided notice and / or the STA that received the notice may mean that the AP and / or STA ensure that the TXOP ends before the start time of the announced Co-RTWT schedule (e.g., the R-RTWT schedule of a neighboring BSS).

[0290] When an AP notifies the STAs that are coupled with it of the schedule information of the OBSS R-TWT being coordinated, the STAs that support the R-TWT may receive such notification. The AP that sent the notification and / or the STAs that received the notification may protect the notified schedule of the OBSS R-TWT being coordinated. For example, such protection action may be performed when the protection level (sub)field in the cooperation / consultation between the AP and a neighbor AP is set to a value indicating "a level in which the responding AP (e.g., the AP receiving the cooperation / consultation request) and the STAs coupled with the responding AP (e.g., all of the coupled STAs) protect the schedule of the R-TWT included in the cooperation / consultation request" or "a level in which the responding AP (e.g., the AP receiving the cooperation / consultation request) and some of the STAs coupled with the responding AP protect the schedule of the R-TWT included in the cooperation / consultation request."

[0291] When an AP notifies the STAs that are coupled with it of the schedule information of the OBSS R-TWT being cooperated, the STAs supporting the R-TWT may receive such notification. The STAs that receive the notification may protect the notified schedule of the OBSS R-TWT being cooperated. For example, this protection action may be performed when, in cooperation / consultation between an AP and a neighboring AP, the protection level (sub)field is set to a value indicating "a level in which STAs coupled with the responding AP (excluding the responding AP) (e.g., all coupled STAs) protect the schedule of the R-TWT included in the cooperation / consultation request" or "a level in which some of the STAs coupled with the responding AP (excluding the responding AP) protect the schedule of the R-TWT included in the cooperation / consultation request."

[0292] If an AP does not notify the STAs that are joined to it of the schedule information of the OBSS R-TWT being collaborated, only the AP can protect the schedule of the OBSS R-TWT being collaborated. The STAs that are joined to the AP may not perform protection on the OBSS R-TWT being collaborated (since they do not receive notification from the AP). For example, this protection action may be performed when, in a collaboration / consultation between an AP and a neighboring AP, the protection level (sub)field is set to a value indicating "a level where only the responding AP (e.g., the AP receiving the collaboration / consultation request) protects the schedule of the R-TWT included in the collaboration / consultation request."

[0293] When an AP notifies the STAs to which it is joined of the schedule information of the OBSS R-TWT being collaborated, it may inform the STAs to which it is joined that the schedule of the OBSS R-TWT being collaborated corresponds to a schedule that is a trigger-enabled broadcast TWT. For example, this protection action may be performed when the protection level (sub)field in the cooperation / consultation between the AP and a neighbor AP is set to a value indicating "a level where only the responding AP (e.g., the AP receiving the cooperation / consultation request) protects the schedule of the R-TWT included in the cooperation / consultation request," or "a level where the responding AP (e.g., the AP receiving the cooperation / consultation request) and the STAs to which it is joined (e.g., all of the joined STAs) protect the schedule of the R-TWT included in the cooperation / consultation request," or "a level where the responding AP (e.g., the AP receiving the cooperation / consultation request) and some of the STAs to which it is joined protect the schedule of the R-TWT included in the cooperation / consultation request."

[0294] For example, if we assume an R-TWT SP that is not announced as a trigger-enabled broadcast TWT SP, where "only the responding AP (e.g., the AP receiving the cooperation / consultation request) protects the schedule of the R-TWT included in the cooperation / consultation request," there may be a fairness issue because the AP performs a protection action but the STAs do not. If a cooperating OBSS R-TWT SP that is announced as a trigger-enabled broadcast TWT SP does not require the STAs to perform protection directly, it can indirectly protect the R-TWT SP because the STAs do not perform data transmission or reception unless triggered by the AP within the R-TWT SP.

[0295] For a cooperating OBSS R-TWT SP corresponding to a trigger-enabled broadcast TWT SP announced from the AP, the STAs coupled with the AP may operate as follows.

[0296] For example, the AP may terminate its TXOP before the start time of the cooperating OBSS R-TWT SP to protect the schedule of the cooperating OBSS R-TWT. After the cooperating OBSS R-TWT SP starts and a certain amount of time has passed, it may trigger the joining STAs to perform data transmission and reception with the AP.

[0297] For example, the STAs being combined may wait from the start time of a trigger-enabled broadcast TWT SP announced by the AP until they receive a triggering signal from the AP. If they receive a triggering signal from the AP after a certain period of time, the STAs being combined may perform data transmission and reception based on the triggering signal.

[0298] In the examples described above, "some of the STAs coupled with the responding AP" may refer to the STA(s) affected by the R-TWT included in the cooperation / consultation request. For example, whether or not an STA is affected by the R-TWT may be determined based on reference information as described above (e.g., OBSS PD and / or a specific threshold), and for this purpose, reference information may be included in the announcement of the cooperating OBSS R-TWT. For example, STAs that receive such reference information may adjust their transmission strength using the OBSS PD value. Accordingly, interference caused by mutual data transmission during the R-TWT schedule may not occur or may be reduced.

[0299] Additionally or alternatively, based on the aforementioned notification methods of the AP, if the AP does not notify some or all of the STAs being combined of the schedule of the cooperating OBSS R-TWT, the TXOP of the combined STA may conflict with the start time of the schedule of the cooperating OBSS R-TWT. To prevent this, it may be permitted, by the AP or at the request of the AP, to terminate the TXOP of the corresponding STAs before the start time of the cooperating OBSS R-TWT.

[0300] Example 4

[0301] This embodiment relates to examples of the operation of a transmitting STA and a receiving STA.

[0302] FIG. 17 is a diagram illustrating the process of requesting / responding to cooperation / consultation between APs based on protection levels according to the present disclosure.

[0303] In the examples of the present disclosure, one AP may perform consultation regarding R-TWT cooperation for obtaining an R-TWT that is cooperated with a neighboring AP. For example, it is assumed that one AP can receive a beacon frame from a neighboring AP, and that the neighboring AP is located in a position where it can receive a beacon frame from one AP.

[0304] As shown in the example of FIG. 17, one AP (e.g., the first AP) sends a cooperation / consultation request containing information about an R-TWT SP to be consulted to a neighbor AP (e.g., the second AP), and the neighbor AP (e.g., the responding AP) can send a cooperation response containing information such as a status code for the R-TWT schedule based on the R-TWT schedule included in the received cooperation request. Based on the value of the status code in the cooperation response, it may be indicated whether cooperation / consultation for each R-TWT schedule was successfully carried out.

[0305] If the value of the status code (sub)field within the status list (sub)field of the cooperation response transmitted by the neighbor AP has a value indicating success / acceptance / acceptance, the R-TWT schedule corresponding to the specific cooperating TWT ID associated with that status code can be determined / acquired as the cooperating R-TWT SP between the AP and the neighbor AP.

[0306] According to the examples of the present disclosure, new information (e.g., a protection level (sub)field) indicating protection associated with an R-TWT schedule included in the cooperation / consultation request may be additionally included in the cooperation / consultation request. For example, the protection level (sub)field may include information indicating the level or scope of AP / STA for which the provision of protection for a specific R-TWT schedule is requested. For example, through the protection level (sub)field, APs may consult during the R-TWT cooperation / consultation process regarding the protection of the R-TWT schedule included in the cooperation / consultation request by the AP, all of the combined STA, part of the combined STA, the AP and all of the combined STA, or the AP and part of the combined STA.

[0307] For example, if an AP that receives a cooperation / consultation request (e.g., a responding AP) accepts the protection level included in the cooperation / consultation request, it may transmit the cooperation / consultation response including a status code corresponding to the acceptance.

[0308] For example, if an AP that has received a cooperation / consultation request (e.g., a responding AP) rejects the protection level included in the cooperation / consultation request and proposes a new protection level, it may transmit the cooperation / consultation response including protection level information that includes a changed value compared to the value of the protection level included in the cooperation / consultation request (including a status code corresponding to the alternative).

[0309] For example, if an AP that receives a cooperation / consultation request (e.g., a responding AP) rejects the protection level included in the request, it may send a cooperation / consultation response containing a status code corresponding to the rejection. Upon receiving this, an AP (e.g., a requesting AP) may send a cooperation / consultation request again to the AP that sent the response, including a new protection level value.

[0310] If R-TWT cooperation / consultation between an AP and a neighboring AP is successfully performed and an agreement is established, the AP that received the cooperation / consultation request may decide whether to notify the joining STAs located within its BSS of the information of the R-TWT included in the cooperation / consultation request. For example, the decision to notify may be based on the value indicated by the protection level (sub)field included in the cooperation / consultation request.

[0311] For example, if it is agreed that only the AP protects the OBSS R-TWT being cooperated with, the AP may not notify the STAs being joined of information regarding the OBSS R-TWT for which the agreement has been established.

[0312] For example, if all joining STAs agree to protect the OBSS R-TWT they are cooperating with, AP may notify all joining STAs of information regarding the agreed-upon OBSS R-TWT.

[0313] For example, if some of the STAs being combined agree to protect the OBSS R-TWT being cooperated, the AP may notify the STA(s) of information regarding the OBSS R-TWT for which the agreement has been reached.

[0314] For example, if all STAs that are joined together with AP agree to protect the OBSS R-TWT that is being cooperated with, AP may notify all STAs of information regarding the OBSS R-TWT that has been agreed upon.

[0315] For example, if some of the STAs being combined with AP have agreed to protect the OBSS R-TWT being cooperated with, AP may notify the STA(s) of information regarding the OBSS R-TWT for which agreement has been reached.

[0316] In existing wireless LAN systems, there is no specific method provided for considering the protection level of a particular AP's R-TWT schedule during the consultation process regarding cooperation among APs regarding R-TWT schedules. According to the present disclosure, since the consultation regarding R-TWT cooperation is performed by considering the protection level of a specific R-TWT schedule during the consultation process and thereby accepting, rejecting, or presenting an alternative, cooperation regarding R-TWT schedules can be performed more efficiently. Furthermore, since an AP that accepts cooperation regarding another AP's R-TWT schedule can notify the STA(s) coupled with it of information related to the protection of the specific R-TWT schedule, the media utilization by the AP and / or STA(s) on the corresponding R-TWT schedule can be performed more efficiently.

[0317] The embodiments described above are combinations of the components and features of the present disclosure in a specific form. Each component or feature should be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, it is possible to construct embodiments of the present disclosure by combining some components and / or features. The order of operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is obvious that embodiments may be constructed by combining claims that are not explicitly related in the claims, or that they may be included as new claims by amendment after filing.

[0318] It is obvious to those skilled in the art that the present disclosure may be embodied in other specific forms without departing from the essential features of the present disclosure. Accordingly, the detailed description set forth above should not be interpreted restrictively in all respects and should be considered exemplary. The scope of the present disclosure shall be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present disclosure are included within the scope of the present disclosure.

[0319] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that enable operations according to the methods of various embodiments to be executed on a device or computer, and a non-transitory computer-readable medium on which such software or instructions, etc. are stored and executable on a device or computer. Instructions that may be used to program a processing system to perform the features described in the present disclosure may be stored on or within a storage medium or a computer-readable storage medium, and the features described in the present disclosure may be implemented using a computer program product comprising such a storage medium. The storage medium may include, but is not limited to, high-speed random access memory such as DRAM, SRAM, DDR RAM, or other random access solid-state memory devices, and may include non-volatile memory such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state storage devices. The memory may optionally include one or more storage devices located remotely from the processor(s). Memory or alternatively, non-volatile memory device(s) within memory comprises a non-transient computer-readable storage medium. The features described in this disclosure may be stored in any one of the machine-readable media and integrated into software and / or firmware that can control the hardware of a processing system and allow the processing system to interact with other mechanisms utilizing results according to the embodiments of this disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0320] Although the method proposed in this disclosure has been described with an example applied to an IEEE 802.11-based system, it can be applied to various wireless LANs or wireless communication systems in addition to IEEE 802.11-based systems.

Claims

1. A step of receiving a negotiation request frame for multi-access point (AP) coordination from the second AP by the first AP; and It includes the step of transmitting a consultation response frame for multi-AP cooperation to the second AP by the first AP, A method in which the above consultation request frame includes information related to protection for a specific target wake time (TWT) schedule.

2. In Paragraph 1, Information regarding protection for the aforementioned specific TWT schedule is, A method comprising information relating to one or more of protection by the first AP or protection by some or all of the stations (STAs) associated with the first AP for the specific TWT schedule.

3. In Paragraph 1, A method in which the above consultation request frame includes reference information related to protection for the above specific TWT schedule.

4. In Paragraph 3, A method in which the above reference information includes a reference value related to OBSS PD (overlapping basic service set packet detect)-based spatial reuse, or a threshold related to received signal strength.

5. In Paragraph 3, A method in which, based on the above reference information, one or more of protection by the first AP, or protection by some or all of the STA combined with the first AP are specified.

6. In Paragraph 1, A method in which the above consultation response frame includes information indicating acceptance or rejection of cooperation for the above specific TWT schedule.

7. In Paragraph 1, A method in which the above consultation response frame includes information indicating one or more of protection by the first AP or protection by some or all of the stations (STAs) associated with the first AP for the specific TWT schedule.

8. In Paragraph 1, A method in which information related to the specific TWT schedule is disclosed from the first AP, for some or all of the STAs combined with the first AP.

9. In Paragraph 8, A method in which information related to the above specific TWT schedule indicates that the above specific TWT schedule is a protected TWT schedule.

10. In Paragraph 8, A method in which information related to the above specific TWT schedule indicates that the above specific TWT schedule is a trigger-enabled broadcast TWT schedule.

11. In Paragraph 1, A method in which reference information related to protection for a specific TWT schedule is disclosed from the first AP, for some or all of the STAs combined with the first AP.

12. In Paragraph 1, A method for protection of the specific TWT schedule, comprising the termination of a transmission opportunity (TXOP) before the start time of the specific TWT schedule.

13. In Paragraph 1, The above specific TWT is a method corresponding to a restricted-TWT (R-TWT).

14. In Paragraph 1, The above-mentioned first AP is a multi-AP cooperative response AP, and The above second AP is a multi-AP cooperation request AP, method.

15. One or more transceivers; and It includes one or more processors connected to the above one or more transmitters and receivers, and The above one or more processors are: Receiving a consultation request frame for multi-access point (AP) cooperation from a second AP through one or more of the transceivers; and It is configured to transmit a consultation response frame for multi-AP cooperation to the second AP through the one or more transceivers, and The above consultation request frame is a first AP containing information related to protection for a specific target wake time (TWT) schedule.

16. A step of transmitting a consultation request frame for multi-access point (AP) cooperation to the first AP by the second AP; and It includes the step of receiving a consultation response frame for multi-AP cooperation from the first AP by the second AP, and A method in which the above consultation request frame includes information related to protection for a specific target wake time (TWT) schedule.

17. One or more transceivers; and It includes one or more processors connected to the above one or more transmitters and receivers, and The above one or more processors are: Transmitting a consultation request frame for multi-access point (AP) cooperation to the first AP through the one or more transceivers; and It is configured to receive a consultation response frame for multi-AP cooperation from the first AP through the one or more transceivers, and The above consultation request frame is a second AP containing information related to protection for a specific target wake time (TWT) schedule.

18. One or more processors; and A processing device comprising one or more computer memories that are operably connected to one or more processors and store instructions for performing a method according to any one of claims 1 to 14 based on execution by one or more processors.

19. One or more non-transitory computer-readable media storing one or more instructions that are executed by one or more processors to control the execution of a method according to any one of claims 1 through 14.

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