Method and device for applying IDC to TXOP in wireless LAN system

Abstract

The present disclosure relates to an improved wireless LAN system. The present disclosure proposes a method and a device for an operation considering IDC to improve traffic reliability in an improved wireless LAN system. Specifically, the present disclosure proposes a signaling and format structure for applying IDC to a TXOP.

Description

Method and device for applying IDC to TXOP in wireless LAN system

[0001] The present disclosure relates to a wireless local area network (WLAN) system. Specifically, the present disclosure relates to a method and apparatus for applying in-device coexistence (IDC) to a transmission opportunity (TXOP) in a WLAN system.

[0002] Wireless LAN (WLAN) systems are evolving for various purposes, such as improving transmission rates, increasing bandwidth, enhancing reliability, reducing errors, and reducing latency. The Institute of Electrical and Electronics Engineers (IEEE) publishes the 802.11 standard specification for WLAN systems, and the technology described in the 802.11 standard specification can be called WiFi (or Wi-Fi, Wireless Fidelity).

[0003] Wi-Fi technology has evolved over several generations of the 802.11 standard. For example, the 802.11ac standard addresses improvements for very high throughput (VHT), the 802.11ax standard addresses improvements for high efficiency (HE), and the 802.11be standard addresses improvements for extreme high throughput (EHT).

[0004] Meanwhile, technologies to provide a more improved wireless communication environment in wireless LAN systems are being discussed, and various technologies are being proposed and researched in response to the demand to further increase the reliability of wireless LAN systems.

[0005] This disclosure proposes a method and device for applying IDC to TXOPs to ensure traffic reliability in a wireless LAN system. Specifically, this disclosure proposes a procedure for a device to transmit and receive IDC information in relation to TXOPs. Furthermore, this disclosure proposes a frame structure for operations that take IDC into account.

[0006] The technical objectives to be achieved in the present disclosure are not limited to those mentioned above, and other technical tasks not mentioned can be considered by a person having ordinary skill in the art to which the present invention pertains from the embodiments of the present invention described below.

[0007] According to one embodiment of the present disclosure, a method performed by a station (STA) comprises the steps of: receiving a first frame for initiating a transmission opportunity (TXOP) from an access point (AP); and transmitting a second frame for notifying the AP of unavailability based on in-device coexistence (IDC) for the TXOP, wherein the second frame comprises a first field for an association identifier (AID), a second field and a third field for indicating unavailability based on the IDC, and a fourth field including parameters related to the IDC, wherein the second field is an Ack Type field and the value of the Ack Type field may be 0, and the third field is a traffic identifier (TID) field and the value of the TID field may be 13.

[0008] According to one embodiment of the present disclosure, a method performed by an access point (AP) comprises the steps of: transmitting a first frame for initiating a transmission opportunity (TXOP) to a station (STA); and receiving a second frame for notifying unavailability based on in-device coexistence (IDC) for the TXOP from the STA, wherein the second frame comprises a first field for an association identifier (AID), a second field and a third field for indicating unavailability based on the IDC, and a fourth field including parameters related to the IDC, wherein the second field is an Ack Type field and the value of the Ack Type field may be 0, and the third field is a traffic identifier (TID) field and the value of the TID field may be 13.

[0009] According to one embodiment of the present disclosure, an STA comprises a transceiver; and at least one processor connected to the transceiver, wherein the at least one processor is configured to: receive a first frame for initiating a transmission opportunity (TXOP) from an access point (AP), and transmit a second frame for notifying unavailability based on in-device coexistence (IDC) for the TXOP to the AP, wherein the second frame includes a first field for an association identifier (AID), a second field and a third field for indicating unavailability based on the IDC, and a fourth field including parameters related to the IDC, wherein the second field is an Ack Type field and the value of the Ack Type field may be 0, and the third field is a traffic identifier (TID) field and the value of the TID field may be 13.

[0010] According to one embodiment of the present disclosure, an AP comprises a transceiver; and at least one processor connected to the transceiver, wherein the at least one processor is configured to: transmit a first frame to a station (STA) for initiating a transmission opportunity (TXOP), and receive a second frame from the STA for notifying unavailability based on in-device coexistence (IDC) for the TXOP, wherein the second frame includes a first field for an association identifier (AID), a second field and a third field for indicating unavailability based on the IDC, and a fourth field including parameters related to the IDC, wherein the second field is an Ack Type field and the value of the Ack Type field may be 0, and the third field is a traffic identifier (TID) field and the value of the TID field may be 13.

[0011] According to the various embodiments proposed in this disclosure, the reliability of traffic transmission and reception in a wireless LAN system can be improved. Furthermore, by simplifying the procedures for improving reliability, the efficiency of device operation can also be improved.

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

[0013] FIG. 2 illustrates an exemplary structure of a wireless LAN system related to the present disclosure.

[0014] Figure 3 illustrates a link setup process related to the present disclosure.

[0015] Figure 4 illustrates a backoff operation related to the present disclosure.

[0016] FIG. 5 illustrates a frame transmission operation based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) in connection with the present disclosure.

[0017] FIG. 6 illustrates an exemplary format of a frame used in a wireless LAN system related to the present disclosure.

[0018] FIG. 7 illustrates an exemplary format of a physical layer protocol data unit (PPDU) of a wireless LAN system related to the present disclosure.

[0019] FIG. 8 illustrates another exemplary format of a PPDU of a wireless LAN system related to the present disclosure.

[0020] Figure 9 is a drawing for explaining an IDC related to the present disclosure.

[0021] Figure 10 is a drawing for explaining an IDC related to the present disclosure.

[0022] FIG. 11 illustrates an exemplary format of a multi-station block acknowledgement (ACK) (M-BA) frame related to the present disclosure.

[0023] FIG. 12 is a diagram illustrating an example of fields included in an M-BA frame related to the present disclosure.

[0024] FIG. 13 is a diagram illustrating an exemplary format of a field included in a frame according to one embodiment of the present disclosure.

[0025] FIG. 14 is a diagram illustrating an exemplary format of a field included in a frame according to one embodiment of the present disclosure.

[0026] FIG. 15 is a diagram illustrating an exemplary format of a field included in a frame according to one embodiment of the present disclosure.

[0027] FIG. 16 is a diagram illustrating an exemplary format of a field included in a frame according to one embodiment of the present disclosure.

[0028] FIG. 16A is a diagram illustrating an exemplary format of a field included in a frame according to one embodiment of the present disclosure.

[0029] FIG. 16b is a diagram illustrating an exemplary format of a field included in a frame according to one embodiment of the present disclosure.

[0030] FIG. 17 is a diagram illustrating an exemplary format of a field included in a frame according to one embodiment of the present disclosure.

[0031] FIG. 18 is a flowchart illustrating operations for applying IDC to TXOP according to one embodiment of the present disclosure.

[0032] FIG. 19 illustrates a flowchart of operations for applying IDC according to one embodiment of the present disclosure.

[0033] FIG. 20 illustrates a flowchart of operations for applying IDC according to one embodiment of the present disclosure.

[0034] FIG. 21 illustrates a flowchart of operations for applying IDC according to one embodiment of the present disclosure.

[0035] FIG. 22 illustrates a flowchart of operations for applying IDC according to one embodiment of the present disclosure.

[0036] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the attached drawings. It should be noted that, where possible, identical components are represented by identical reference numerals throughout the attached drawings. Furthermore, detailed descriptions of well-known functions and configurations that may obscure the gist of the present disclosure will be omitted.

[0037] In describing the embodiments in this specification, descriptions of technical details that are well known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to avoid obscuring the gist of the present disclosure by omitting unnecessary explanations and to convey the gist more clearly.

[0038] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size.

[0039] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined solely by the scope of the claims.

[0040] At this time, it will be understood that each block of the flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0041] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0042] Here, the term '~ unit' used in the present embodiment means a software or hardware component such as an FPGA or ASIC, and the '~ unit' performs certain roles. However, the '~ unit' is not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Accordingly, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. Additionally, components and '~parts' may be implemented to regenerate one or more CPUs within a device or secure multimedia card.

[0043] In the present disclosure, when a component is said to be "connected," "coupled," or "connected" to another component, this may include not only a direct connection but also an indirect connection in which another component exists between them. Furthermore, the terms "comprises" or "has" in the present disclosure specify the presence of the mentioned features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0044] In this disclosure, terms such as "first," "second," etc. are used only to distinguish one component from another, are not used to limit the components, and do not limit the order or importance of components unless specifically stated otherwise. Accordingly, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0045] The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "and / or" as used herein may refer to any one of the associated enumerated items, or is meant to refer to and encompass any and all possible combinations of two or more of them. Furthermore, the use of " / " between words in this disclosure has the same meaning as "and / or" unless otherwise stated.

[0046] The examples of the present disclosure can be applied to various wireless communication systems. For example, the examples of the present disclosure can be applied to a wireless LAN system. For example, the examples of the present disclosure can be applied to a wireless LAN system based on the IEEE 802.11a / g / n / ac / ax / be standards. Furthermore, the examples of the present disclosure can be applied to a wireless LAN system based on the newly discussed IEEE 802.11bn (or UHR (ultra high reliability)) standards. Furthermore, the examples of the present disclosure can be applied to a next-generation wireless LAN system based on a new standards document that improves on the IEEE 802.11bn.

[0047] Additionally, examples of the present disclosure may be applied to cellular wireless communication systems. For example, examples of the present disclosure may be applied to cellular wireless communication systems based on Long Term Evolution (LTE), LTE-Advanced (LTE-A), and New Radio (NR) technologies based on 3rd Generation Partnership Project (3GPP) standard documents.

[0048] FIG. 1 illustrates a configuration of a device for wireless communication according to one embodiment of the present disclosure.

[0049] The first device (100) and the second device (200) of FIG. 1 may be replaced with various terms such as terminal, wireless device, WTRU (Wireless Transmit and 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), client terminal, or simply user.

[0050] In addition, the first device (100) and the second device (200) may be replaced with various terms such as access point (AP), base station (BS), fixed station, Node B, base transceiver system (BTS), network, artificial intelligence (AI) system, road side unit (RSU), repeater, router, relay, gateway, etc.

[0051] The devices (100, 200) illustrated in FIG. 1 may also be referred to as stations (STAs). For example, the devices (100, 200) illustrated in FIG. 1 may be referred to by various terms such as transmitting device, receiving device, transmitting STA, and receiving STA. For example, the STAs (110, 200) may perform an AP (access point) role or a non-AP role. That is, in the present disclosure, the STAs (110, 200) may perform the functions of an AP and / or a non-AP. When the STAs (110, 200) perform an AP function, they may simply be referred to as APs, and when the STAs (110, 200) perform a non-AP function, they may simply be referred to as STAs. In addition, in the present disclosure, the APs may also be referred to as AP STAs.

[0052] Referring to FIG. 1, the first device (100) and the second device (200) can transmit and / or receive wireless signals through various wireless LAN technologies (e.g., technologies based on the IEEE 802.11 standard document). The first device (100) and the second device (200) can include interfaces for a medium access control (MAC) layer and a physical (PHY) layer that follow the regulations of the IEEE 802.11 standard document.

[0053] In addition, the first device (100) and the second device (200) may additionally support various wireless communication technologies other than wireless LAN technology (for example, technologies based on 3GPP LTE, LTE-A, or NR standard documents). In addition, the devices 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. In addition, the STA of the present specification may support various communication services such as voice calls, video calls, data communications, autonomous driving, MTC (Machine-Type Communication), M2M (Machine-to-Machine), D2D (Device-to-Device), and IoT (Internet-of-Things).

[0054] A first device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (or transceivers) (106) and / or one or more antennas (108). The processor (102) controls the memories (104) and / or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (102) may process information in the memories (104) to generate first information and / or a first signal, and then transmit a wireless signal including the first information and / or the first signal via the transceivers (106). In addition, the processor (102) may receive a wireless signal including second information and / or a second signal through the transceiver (106), and then store information obtained through signal processing of the second information and / or the second signal in the memory (104). The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software code including instructions for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (102) and the memory (104) may be part of a communication modem / circuit / chip designed to implement a wireless LAN technology (e.g., a technology based on the IEEE 802.11 document). A transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit.

[0055] The second device (200) includes one or more processors (202) and one or more memories (204), and may further include one or more transceivers (or transceiver units) (206) and / or one or more antennas (208). The processor (202) controls the memories (204) and / or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (202) may process information in the memories (204) to generate third information and / or a third signal, and then transmit a wireless signal including the third information and / or the third signal via the transceivers (206). In addition, the processor (202) may receive a wireless signal including the fourth information and / or the fourth signal through the transceiver (206), and then store information obtained through signal processing of the fourth information and / or the fourth 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 perform some or all of the processes controlled by the processor (202), or store software code including instructions for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement a wireless LAN technology (e.g., a technology based on the IEEE 802.11 document). A transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit.

[0056] Hereinafter, hardware elements of the device (100, 200) will be described in more detail. Although not limited to the following, operations of 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 operations of one or more layers (e.g., functional layers such as PHY, MAC). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, traffic or information according to the functions, procedures, proposals and / or methods disclosed in this disclosure, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data, traffic or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed in this disclosure.

[0057] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as read only memory (ROM), random access memory (RAM), erasable programmable ROM (EPROM), electronically EPROM (EEPROM), flash memory, hard drives, registers, cache memory, computer readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0058] One or more transceivers (106, 206) can transmit user data, control information, data, traffic, wireless signals, and / or channels, etc., as described in the methods and / or flowcharts of the present disclosure, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, data, traffic, wireless signals, and / or channels, etc., as described in the descriptions, functions, procedures, proposals, methods, and / or flowcharts of the present disclosure, from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, traffic, wireless signals, and / or channels, etc., 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, traffic, wireless signals, and / or channels from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, traffic, wireless signals, and / or channels, etc., as described in the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure, via one or more antennas (108, 208). In the present disclosure, one or more antennas (108, 208) may be multiple physical antennas or multiple logical antennas (e.g., antenna ports).One or more transceivers (106, 206) may convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202). One or more transceivers (106, 206) may convert processed user data, control information, wireless signals / channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or a filter.

[0059] In one example, one of the devices (100, 200) may perform the intended operation of an AP, and the other of the devices (100, 200) may perform the intended operation of a non-AP STA. In another example, the transceiver (106, 206) of FIG. 1 may perform transmission and / or reception operations of signals (e.g., packets or PPDUs (physical layer protocol data units) according to IEEE 802.11a / b / g / n / ac / ax / be / bn, etc.).

[0060] Additionally, in the present disclosure, the operations of various STAs generating transmission / reception signals or performing data processing or calculations in advance for transmission / reception signals can be performed in the processor (102, 202) of FIG. 1. For example, an example of an operation of generating a transmission / reception signal or performing data processing or operation in advance for a transmission / reception signal is an operation of determining / obtaining / configuring / computing / decoding / encoding bit information of a field included in a PPDU (e.g., SIG (signal), STF (short training field), LTF (long training field), Data, etc.), 2) determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) used for a field included in a PPDU (e.g., SIG, STF, LTF, Data, etc.), 3) determining / configuring / obtaining a specific sequence (e.g., pilot sequence, STF / LTF sequence, extra sequence applied to SIG) used for a field included in a PPDU (e.g., SIG, STF, LTF, Data, etc.), 4) power control operation and / or power saving operation applied to an STA, 5) ACK (acknowledgement) signal It may include operations related to decision / acquisition / configuration / computation / decoding / encoding, etc. In addition, in the example below, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs for decision / acquisition / configuration / computation / decoding / encoding of transmission / reception signals may be stored in the memory (104, 204) of FIG. 1.

[0061] Hereinafter, downlink (DL) refers to a link for communication from an AP STA to a non-AP STA, and downlink PPDUs / packets / signals, etc. can be transmitted and received through the downlink. In downlink communication, the transmitter may be part of an AP STA, and the receiver may be part of a non-AP STA. Uplink (UL) refers to a link for communication from a non-AP STA to an AP STA, and uplink PPDUs / packets / signals, etc. can be transmitted and received through the uplink. In uplink communication, the transmitter may be part of a non-AP STA, and the receiver may be part of an AP STA.

[0062] An exemplary structure of a wireless LAN system related to the present disclosure is illustrated.

[0063] A wireless LAN system may have a structure composed of multiple components. The wireless LAN system can support transparent STA mobility to the upper layer through the interaction of the multiple components. A Basic Service Set (BSS) corresponds to a basic building block of a wireless LAN. FIG. 2 illustrates, by way of example, the existence of two BSSs (BSS 1 and BSS 2), and the inclusion of two STAs as members of each BSS (STA 1 and STA 2 are included in BSS 1, and STA 3 and STA 4 are included in BSS 2). The oval representing a BSS in FIG. 2 can also be understood as representing a coverage area in which STAs included in the corresponding BSS maintain communication. This area can be referred to as a Basic Service Area (BSA). When an STA moves outside of the BSA, it cannot directly communicate with other STAs within the BSA.

[0064] If we do not consider the distributed system (DS) illustrated in Fig. 2, the most basic type of BSS in a wireless LAN is an Independent BSS (IBSS). For example, an IBSS can have a minimal form consisting of only two STAs. For example, assuming other components are omitted, BSS 1 consisting of only STA 1 and STA 2, or BSS 2 consisting of only STA 3 and STA 4, can be representative examples of an IBSS, respectively. Such a configuration is possible when the STAs can communicate directly without an AP. Furthermore, this type of WLAN is not planned in advance but can be configured when a local area network (LAN) is required, and can also be called an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity. That is, in an IBSS, STAs are managed in a distributed manner. In IBSS, all STAs can be mobile STAs, and access to the DS is not permitted, forming a self-contained network.

[0065] An STA's membership in a BSS can dynamically change, for example, when an STA is turned on or off, or when an STA enters or leaves a BSS area. To become a member of a BSS, an STA can join the BSS using a synchronization process. To access all services in the BSS infrastructure, an STA must be associated with the BSS. This association can be dynamically established and may involve the use of a Distribution System Service (DSS).

[0066] In a wireless LAN, the direct STA-to-STA distance may be limited by PHY performance. While this distance limit may be sufficient in some cases, communication between STAs over longer distances may be required in other cases. To support extended coverage, a DS can be configured.

[0067] DS refers to a structure in which BSSs are interconnected. Specifically, a BSS may exist as an extended component of a network composed of multiple BSSs, as illustrated in Figure 2. DS is a logical concept and can be specified by the characteristics of the distributed system medium (DSM, DS medium). In this regard, the Wireless Medium (WM) and DSM can be logically distinguished. Each logical medium is used for a different purpose and by different components. These media are neither limited to being identical nor limited to being different. This logical difference between multiple media explains the flexibility of the WLAN architecture (DS architecture or other network architectures). In other words, the WLAN architecture can be implemented in various ways, and the physical characteristics of each implementation can independently specify the WLAN architecture.

[0068] A DS can support mobile devices by providing seamless integration of multiple BSSs and the logical services necessary to handle addresses to destinations. Additionally, a DS may further include a component called a portal, which acts as a bridge for connecting wireless LANs to other networks (e.g., IEEE 802.X).

[0069] An AP enables non-AP STAs associated with it to access the DS through the WM. An AP may refer to an entity that also has the functionality of an STA, and data movement between the BSS and the DS may be performed through the AP. For example, STA 2 and STA 3 illustrated in FIG. 2 have the functionality of an STA and provide the function of allowing associated non-AP STAs (STA 1 and STA 4) to access the DS. In addition, since all APs are basically STAs, all APs are addressable entities. The address used by an AP for communication on the WM and the address used by an AP for communication on the DSM do not necessarily have to be the same. A BSS consisting of an AP and one or more STAs may be referred to as an infrastructure BSS.

[0070] Data transmitted from one of the STA(s) associated with an AP to the STA address of that AP is always received on an uncontrolled port and can be processed by an IEEE 802.1X port access entity. In addition, if the controlled port is authenticated, the transmitted data (or frame) can be forwarded to the DS.

[0071] In addition to the structure of the DS described above, an extended service set (ESS) may be established to provide wider coverage.

[0072] An ESS is a network of arbitrary size and complexity, and may correspond to a set of BSSs connected to a DS. However, an ESS does not include a DS. An ESS network is characterized by appearing as an IBSS at the LLC (Logical Link Control) layer. STAs included in an ESS can communicate with each other, and mobile STAs can move from one BSS to another (i.e., within the same ESS) transparently to the LLC. APs included in an ESS may have the same SSID (service set identifier). The SSID is distinct from the BSS ID (BSS SSID), which is the identifier of the BSS.

[0073] In a wireless LAN system, no assumptions are made about the relative physical locations of BSSs, and all of the following configurations are possible: BSSs can be partially overlapping, which is commonly used to provide continuous coverage. BSSs can also be physically disconnected, and there is no logical distance restriction between them. BSSs can also be physically co-located, which can be used to provide redundancy. Furthermore, one or more IBSS or ESS networks can physically co-exist in the same space as one (or more) ESS networks. This can occur in cases where an ad-hoc network operates in the same location as an ESS network, where physically overlapping wireless networks are configured by different organizations, or where two or more different access and security policies are required at the same location.

[0074] Figure 3 illustrates a link setup process related to the present disclosure.

[0075] For an STA to set up a link and transmit and receive data on a network, it must discover the network via an AP, perform authentication, establish an association, and establish security. The link setup process can also be referred to as the session initiation process or session setup process. Furthermore, the discovery, authentication, association, and security setup processes of the link setup process can be collectively referred to as the association process.

[0076] At step 310, the STA may perform a network discovery operation. This network discovery operation may include scanning operations by the STA. That is, for the STA to access a network, it must search for available networks. Before joining a wireless network, the STA must identify compatible networks. The process of identifying networks in a specific area is called scanning.

[0077] 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, an STA performing scanning transmits a probe request frame to discover any APs in the vicinity while moving between channels and waits for a response. The responder transmits a probe response frame in response to the STA that transmitted the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame in the BSS of the channel being scanned. In the BSS, the AP transmits the beacon frame, so the AP becomes the responder. In the IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not fixed. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning (i.e., transmitting and receiving probe requests / responses on channel 2) in the same manner.

[0078] Although not shown in Figure 3, the scanning operation can also be performed in a passive scanning manner. In passive scanning, the STA performing the scanning moves between channels and waits for a beacon frame. A beacon frame is one of the management frames defined in IEEE 802.11. It announces the existence of a wireless network and is periodically transmitted to enable the STA performing the scanning to find the wireless network and participate in the wireless network. In the BSS, the AP performs the role of periodically transmitting the beacon frame, and in the IBSS, the STAs within the IBSS take turns transmitting the beacon frame. When the STA performing the scanning receives a beacon frame, it stores the information about the BSS included in the beacon frame and moves to another channel, recording the beacon frame information on each channel. The STA receiving the beacon frame stores the BSS-related information included in the received beacon frame and moves to the next channel to perform scanning on the next channel in the same manner. Comparing active scanning and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.

[0079] After the STA discovers the network, an authentication process may be performed at step 320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation of step 340 described below.

[0080] The authentication process involves the STA sending an authentication request frame to the AP, and the AP responding by sending an authentication response frame to the STA. The authentication request frame and the authorization response frame used in the authentication process belong to management frames.

[0081] The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), and a Finite Cyclic Group. These are just some examples of information that may be included in an authentication request / response frame, and may be replaced with other information or include additional information.

[0082] An STA can transmit an authentication request frame to an AP. The AP can determine whether to grant authentication to the STA based on the information contained in the received authentication request frame. The AP can provide the result of the authentication process to the STA via an authentication response frame.

[0083] After the STA is successfully authenticated, an association process may be performed at step 330. The association process includes a process in which the STA transmits an association request frame to the AP, and in response, the AP transmits an association response frame to the STA.

[0084] The association request frame may include information about various capabilities, a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, a robust security network (RSN), a mobility domain, supported operating classes, a Traffic Indication Map Broadcast request, interworking service capabilities, etc. For example, the association response frame may include information about various capabilities, a status code, an Association ID (AID), supported rates, an Enhanced Distributed Channel Access (EDCA) parameter set, a Received Channel Power Indicator (RCPI), a Received Signal to Noise Indicator (RSNI), a mobility domain, a timeout interval (e.g., an association comeback time), overlapping BSS scan parameters, a TIM broadcast response, a Quality of Service (QoS) map, etc. These are just some examples of information that may be included in a combined request / response frame, and the combined request / response frame may further include additional information.

[0085] After the STA successfully joins the network via the AP, a security setup process may be performed at step 340. The security setup process of step 340 may include an authentication process via a Robust Security Network Association (RSNA) request / response. Furthermore, if the authentication process of step 320 is referred to as the first authentication process, the security setup process of step 340 may also be referred to simply as the authentication process.

[0086] The security setup process of step 340 may include, for example, a process of establishing a private key through a four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame. Furthermore, the security setup process may be performed according to a security method not defined in the IEEE 802.11 standard.

[0087] Figure 4 illustrates a backoff operation related to the present disclosure.

[0088] In wireless LAN systems, the basic MAC access mechanism is Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). CSMA / CA, also known as the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC, essentially employs a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or STA performs Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time period (e.g., DIFS (DCF Inter-Frame Space)) before starting transmission. If the sensing result determines that the medium is in an idle state, the AP and / or STA starts transmitting frames through the medium. On the other hand, if the medium is detected to be occupied or busy, the AP and / or STA may not start its own transmission, but may wait for a predetermined delay period (e.g., a random backoff period) for medium access before attempting to transmit frames. By applying the random backoff period, multiple STAs may attempt to transmit frames after waiting for different periods of time, thereby minimizing collisions.

[0089] Additionally, the IEEE 802.11 MAC protocol provides a Hybrid Coordination Function (HCF). HCF is based on the DCF and Point Coordination Function (PCF). PCF is a polling-based synchronous access method, which refers to a method in which all receiving APs and / or STAs periodically poll to ensure that they can receive data frames. HCF also includes Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA). EDCA is a contention-based access method in which a provider provides data frames to multiple users, while HCCA uses a non-contention-based channel access method using a polling mechanism. In addition, HCF includes a medium access mechanism to improve the Quality of Service (QoS) of a wireless LAN, and can transmit QoS data in both a Contention Period (CP) and a Contention Free Period (CFP).

[0090] Referring to Fig. 4, an operation based on a random backoff period is described. When an occupied / busy medium changes to an idle state, multiple STAs may attempt to transmit data (or frames). To minimize collisions, each STA may select a random backoff count, wait for the corresponding slot time, and then attempt transmission. The random backoff count has a pseudo-random integer value and may be determined as one of the values ​​in the range of 0 to CW. Here, CW is a contention window parameter value. The CW parameter is initially given a value of CWmin, but in case of a transmission failure (e.g., if an ACK for a transmitted frame is not received), the STA may increase the CW by a factor of two. When the CW parameter value reaches CWmax, the STA may attempt data transmission while maintaining the CWmax value until the data transmission is successful, and if the data transmission is successful, the CW is reset to the CWmin value. The values ​​of CW, CWmin and CWmax can be set to 2n-1 (n=0, 1, 2, ...).

[0091] Once the random backoff process begins, the STA continues to monitor the medium while counting down the backoff slots according to the determined backoff count value. If the medium is monitored as occupied, the countdown stops and waits. When the medium becomes idle, the remaining countdown resumes.

[0092] In the example of FIG. 4, when a packet to be transmitted reaches the MAC of STA3, STA3 can immediately transmit the frame if it confirms that the medium is idle for DIFS. The remaining STAs monitor the medium for occupied / busy states and wait. In the meantime, data to be transmitted may also occur in each of STA1, STA2, and STA5, and each STA can count down the backoff slot according to the random backoff count value selected by each STA after waiting for DIFS if it confirms that the medium is idle. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. In other words, this example shows a case where the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1 when STA2 finishes the backoff count and starts frame transmission. STA1 and STA5 briefly stop counting down and wait while STA2 occupies the medium. When STA2's occupation ends and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume the backoff count that was stopped. That is, STA1 and STA5 can start frame transmission after counting down the remaining backoff slots equal to the remaining backoff time. Since STA5's remaining backoff time is shorter than STA1's, STA5 starts frame transmission. While STA2 occupies the medium, STA4 may also have data to transmit. When the medium becomes idle, STA4 waits for DIFS, counts down according to the random backoff count value it selected, and then starts frame transmission. In the example of FIG. 4, the remaining backoff time of STA5 coincidentally matches the random backoff count value of STA4, in which case a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 will receive an ACK, resulting in a failure in data transmission.In this case, STA4 and STA5 can select a random backoff count value and perform a countdown after doubling the CW value. STA1 waits while the medium is occupied by transmissions from STA4 and STA5, and when the medium becomes idle, it waits for DIFS and can start transmitting frames after the remaining backoff time elapses.

[0093] As shown in the example of Fig. 4, a data frame is a frame used for transmitting data to an upper layer, and can be transmitted after a backoff performed after DIFS elapses from when the medium becomes idle. Additionally, a management frame is a frame used for exchanging management information without being transmitted to an upper layer, and is transmitted after a backoff performed after an IFS such as DIFS or PIFS (Point coordination function IFS) elapses. A management frame may include a beacon, an association request / response, a re-association request / response, a probe request / response, an authentication request / response, etc. as a subtype frame. A control frame is a frame used to control access to the medium. Control frames can include RTS (Request-To-Send), CTS (Clear-To-Send), ACK (Acknowledgment), PS-Poll (Power Save-Poll), Block ACK (B-ACK or BlockAck), Block ACK Request (BlockACKReq), NDP announcement (null data packet announcement), Trigger, etc. as subtype frames. If the control frame is not a response frame to the previous frame, it is transmitted after a backoff performed after the DIFS (Direct Inverse Frame Stop) has elapsed, and if it is a response frame to the previous frame, it is transmitted without a backoff performed after the SIFS (short IFS) has elapsed. The type and subtype of a frame can be identified by the type field and subtype field in the frame control (FC) field.

[0094] A QoS (Quality of Service) STA can transmit a frame after a backoff performed after the AIFS (arbitration IFS) for the access category (AC) to which the frame belongs, i.e., AIFS[i] (where i is a value determined by the AC), has elapsed. Here, the frames for which AIFS[i] can be used can be data frames, management frames, and also control frames that are not response frames.

[0095] FIG. 5 illustrates a frame transmission operation based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) in connection with the present disclosure.

[0096] As mentioned above, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, in which STAs directly sense the medium. Virtual carrier sensing is intended to address potential issues in medium access, such as the hidden node problem. For virtual carrier sensing, the MAC of an STA can utilize a Network Allocation Vector (NAV). The NAV is a value that an STA that is currently using or has the right to use the medium indicates to other STAs the remaining time until the medium becomes available. Therefore, the value set as NAV corresponds to the period during which the STA transmitting the frame is scheduled to use the medium, and an STA that receives the NAV value is prohibited from accessing the medium during that period. For example, the NAV can be set based on the value of the "duration" field in the MAC header of the frame.

[0097] In the example of FIG. 5, STA1 wants to transmit data to STA2, and STA3 is in a position to overhear part or all of the frames transmitted and received between STA1 and STA2.

[0098] In order to reduce the possibility of collisions in transmissions of multiple STAs in a CSMA / CA-based frame transmission operation, a mechanism using RTS / CTS frames may be applied. In the example of FIG. 5, while STA1 is transmitting, STA3 may determine that the medium is idle based on carrier sensing. That is, STA1 may correspond to a hidden node for STA3. Alternatively, in the example of FIG. 5, while STA2 is transmitting, STA3 may determine that the medium is idle based on carrier sensing. That is, STA2 may correspond to a hidden node for STA3. By exchanging RTS / CTS frames before performing data transmission and reception between STA1 and STA2, STAs outside the transmission range of either STA1 or STA2, or STAs outside the carrier sensing range for transmissions from STA1 or STA3, may not attempt to occupy the channel during data transmission and reception between STA1 and STA2.

[0099] Specifically, STA1 can determine whether a channel is occupied through carrier sensing. In terms of physical carrier sensing, STA1 can determine channel occupancy idleness based on the energy level or signal correlation detected in the channel. Furthermore, in terms of virtual carrier sensing, STA1 can determine the channel occupancy status using the NAV timer.

[0100] STA1 can transmit an RTS frame to STA2 after performing a backoff if the channel is idle during the DIFS. STA2 can transmit a CTS frame, which is a response to the RTS frame, to STA1 after an SIFS if it receives the RTS frame.

[0101] If STA3 cannot overhear a CTS frame from STA2 but can overhear an RTS frame from STA1, STA3 can use the duration information contained in the RTS frame to set a NAV timer for the subsequent consecutively transmitted frame transmission period (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame). Alternatively, if STA3 cannot overhear an RTS frame from STA1 but can overhear a CTS frame from STA2, STA3 can use the duration information contained in the CTS frame to set a NAV timer for the subsequent consecutively transmitted frame transmission period (e.g., SIFS + data frame + SIFS + ACK frame). That is, if STA3 can overhear one or more of the RTS or CTS frames from one or more of STA1 or STA2, it can set a NAV accordingly. If STA3 receives a new frame before the NAV timer expires, it can update the NAV timer using the duration information contained in the new frame. STA3 does not attempt channel access until the NAV timer expires.

[0102] If STA1 receives a CTS frame from STA2, it can transmit a data frame to STA2 after SIFS from the time when the CTS frame is completely received. If STA2 successfully receives the data frame, it can transmit an ACK frame in response to the data frame to STA1 after SIFS. STA3 can determine whether the channel is in use through carrier sensing if the NAV timer expires. If STA3 determines that the channel is not in use by another terminal during the DIFS after the NAV timer expires, it can attempt channel access after a contention window (CW) based on a random backoff has elapsed.

[0103] FIG. 6 illustrates an exemplary format of a frame used in a wireless LAN system related to the present disclosure.

[0104] Based on an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer, the PHY layer can prepare an MPDU (MAC PDU) to be transmitted. When the PHY layer receives a command requesting the start of transmission from the MAC layer, the PHY layer can switch to transmission mode and transmit the information (e.g., data) provided by the MAC layer in the form of a frame. In addition, when the PHY layer detects a valid preamble of the received frame, it can monitor the header of the preamble and send a command to the MAC layer notifying the start of reception by the PHY layer.

[0105] In this way, information transmission / reception in a wireless LAN system is done in the form of frames, and for this purpose, the PHY layer Protocol Data Unit (PPDU) frame format is defined.

[0106] A basic PPDU frame may include a short training field (STF), a long training field (LTF), a SIGNAL (SIG) field, and a data field. The most basic (e.g., non-HT (high throughput)) PPDU frame format may consist of only L-STF (Legacy-STF), L-LTF (Legacy-LTF), a SIG field, and a data field. In addition, depending on the type of PPDU frame format (e.g., HT-mixed format PPDU, HT-greenfield format PPDU, VHT (very high throughput) PPDU, etc.), additional (or different types of) STF, LTF, and SIG fields may be included between the SIG field and the data field. Specific types of frame formats are described later in FIG. 7.

[0107] STF is a signal for signal detection, AGC (automatic gain control), diversity selection, precise time synchronization, etc., and LTF is a signal for channel estimation, frequency error estimation, etc. STF and LTF are signals for synchronization and channel estimation of the OFDM (orthogonal frequency division multiplexing) physical layer.

[0108] The SIG field may include a RATE field and a LENGTH field, among others. The RATE field may include information about the modulation and coding rate of the data. The LENGTH field may include information about the length of the data. Additionally, the SIG field may include a parity bit, a SIG TAIL bit, among others.

[0109] The data field may include a SERVICE field, a physical layer service data unit (PSDU), a PPDU TAIL bit, and, if necessary, padding bits. Some bits of the SERVICE field may be used to synchronize the descrambler at the receiving end. The PSDU corresponds to a MAC PDU defined at the MAC layer and may contain data generated / used by upper layers. The PPDU TAIL bit may be used to return the encoder to a 0 state. The padding bit may be used to adjust the length of the data field to a predetermined unit.

[0110] MAC PDUs are defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a frame check sequence (FCS). A MAC frame is composed of MAC PDUs and can be transmitted / received through the PSDU in the data portion of the PPDU frame format.

[0111] The MAC header includes a frame control field, a duration / ID field, an address field, etc. The frame control field may include control information necessary for frame transmission / reception. The duration / ID field may be set to the time for transmitting the corresponding frame, etc. The specific contents of the Sequence Control, QoS Control, and HT Control subfields of the MAC header are omitted.

[0112] Although not shown in FIG. 6, the null data packet (NDP) frame format refers to a frame format that does not include a data packet. That is, the NDP frame refers to a frame format that includes the PLCP (physical layer convergence procedure) header portion (i.e., STF, LTF, and SIG fields) of the general PPDU frame format, but does not include the remaining portion (i.e., data field). The NDP frame may also be referred to as a short frame format.

[0113] FIG. 7 illustrates an exemplary format of a physical layer protocol data unit (PPDU) of a wireless LAN system related to the present disclosure.

[0114] Standards such as IEEE 802.11a / g / n / ac / ax / be use various PPDU formats. The basic PPDU format (IEEE 802.11a / g format) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format can also be referred to as the non-HT PPDU format.

[0115] The HT PPDU format (IEEE 802.11n format) 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 may be referred to as an HT-mixed format. Although not illustrated, an HT-greenfield format PPDU may be defined, which corresponds to a format that does not include L-STF, L-LTF, and L-SIG, and is composed of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTF, and Data fields.

[0116] The VHT PPDU format (IEEE 802.11ac format) includes VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format.

[0117] The HE PPDU format (IEEE 802.11ax format) additionally includes RL-SIG (Repeated L-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and PE (Packet Extension) fields in addition to the basic PPDU format. Depending on specific examples of the HE PPDU format, some fields may be excluded or their lengths may vary. For example, the HE-SIG-B field is included in the HE PPDU format for multi-users (MUs), but the HE PPDU format for single-users (SUs) does not include the HE-SIG-B. In addition, the HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may vary to 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 can vary up to 16 μs.

[0118] FIG. 8 illustrates another exemplary format of a PPDU of a wireless LAN system related to the present disclosure.

[0119] The EHT PPDU format (IEEE 802.11be format) of FIG. 8 may include an EHT MU PPDU format and an EHT TB PPDU format. The EHT MU PPDU format corresponds to a PPDU that carries one or more data (or PSDU) for one or more users. The EHT MU PPDU can be used for both SU transmission and MU transmission, and the EHT MU PPDU may correspond to a PPDU for one receiving STA or multiple receiving STAs. The EHT TB PPDU omits the EHT-SIG compared to the EHT MU PPDU. An STA that receives a trigger for UL MU transmission (e.g., a trigger frame or an RTS frame) can perform UL transmission based on the EHT TB PPDU format.

[0120] The EHT PPDU format includes RL-SIG, U-SIG (Universal SIG), EHT-SIG, EHT-STF, EHT-LTF(s), and PE fields in addition to the basic PPDU format. Depending on the specific examples of the EHT PPDU format, some fields may be excluded or their lengths may vary. For example, depending on the EHT MU PPDU format and EHT TB PPDU format described above, some fields of the EHT PPDU format may or may not be included, or the lengths of specific fields may vary.

[0121] Figure 9 is a drawing for explaining an IDC related to the present disclosure.

[0122] As devices evolve, they (including non-AP STAs and APs) support a variety of different radio access technologies (RATs). Furthermore, as devices become increasingly smaller, antennas and transceivers supporting multiple RATs are mounted adjacent to each other within the device. Alternatively, a single radio frequency (RF) chain within a device may be shared among different RATs. In particular, when different RATs occupy adjacent frequency bands, there is a growing need for seamless coexistence (i.e., in-device coexistence, or IDC) among different RATs within a device. This IDC must be considered across various RATs, such as wireless LAN (WLAN), Bluetooth (BT), Bluetooth low-energy (BLE), peer-to-peer (P2P), ultra-wideband (UWB), licensed assisted access (LAA), and NR unlicensed (NR-U).

[0123] Meanwhile, APs may include not only fixed APs that operate in a fixed location, but also mobile APs that can move, and the description of APs below can be understood to apply to both fixed APs and mobile APs.

[0124] Recently, various discussions have been held to improve or solve these IDCs. Examples include methods that support transmission and reception of wireless access technologies other than WLAN systems by utilizing schedulable time intervals such as TWT (target wakeup time), APSU (automatic power save delivery), and U-APSD (unscheduled APSD); methods that support transmission and reception of other wireless access technologies by utilizing unscheduled time intervals such as AM (active mode) / PS (power saving) mode transition or flexible TWT; and methods that signal unavailability through the duration field of the MAC header. These methods correspond to methods that utilize available time or unavailable time.

[0125] Alternatively, as illustrated in Fig. 9, a method of indicating target availability or target unavailability within a specific control frame, such as an initial control frame (ICF), an initial control response (ICR), or a response control frame (RCF), is also being discussed. According to this method, by indicating the unavailability (or availability) of a wireless LAN based on a specific wireless access technology (i.e., a wireless access technology other than a wireless LAN system) during the transmission and reception of a control frame or a management frame, a device can be made to operate or not operate at a specific point in time.

[0126] However, the various methods for improving IDC described above fall short in precisely and efficiently controlling it. Specifically, the 802.11bn standard document discusses various methods for improving reliability. Therefore, from this perspective, a method for controlling IDC through specific yet simple procedures is needed. Furthermore, various discussions are underway to control IDC when supporting the multi-link device (MLD) function based on the 802.11be standard.

[0127] Figure 10 is a drawing for explaining an IDC related to the present disclosure.

[0128] In addition to what is described in Figure 9, more specific and diverse discussions are taking place regarding methods for notifying and negotiating unavailability between devices. In particular, when unavailability occurs within or in relation to an initiated transmission opportunity (TXOP), it may be necessary to notify non-AP STAs and STAs of the unavailability for the TXOP and apply IDC to the TXOP.

[0129] Figure 10 illustrates signaling between a device that performs an IDC operation (STA with IDC in Figure 10) and a device that initiates a TXOP (peer STA in Figure 10). In one example, when a peer STA requests reporting of unavailability-related information via ICF, the STA with IDC reports the unavailability-related information via ICR, and such unavailability-related information may be applied within or for a TXOP initiated by the peer STA. If the unavailability-related information reported by the STA with IDC indicates that unavailability of the WLAN is expected due to IDC for at least a portion of the initiated TXOP, the time period during which PPDU transmission is possible in the TXOP may be shortened or truncated.

[0130] To apply IDC in TXOP, a method for efficiently transmitting and receiving unavailability-related information is required. Below, various examples of procedures and frame formats for transmitting and receiving unavailability-related information are proposed.

[0131] Below, we propose embodiments for devices (non-AP STAs and APs) to transmit or report unavailability-related information for TXOPs. Furthermore, we propose a frame format structure for devices to report unavailability-related information for TXOPs. The proposed embodiments enable TXOP-level IDC implementation between devices.

[0132] Hereinafter, related embodiments will be further described using the two devices described in FIG. 10, namely, an STA with IDC and a peer STA, as examples. A peer STA (e.g., an AP) can initiate a TXOP by transmitting an ICF. According to an example, the ICF can include any one of a BSRP (buffer status report poll) trigger frame, a BQRP (bandwidth query report poll) trigger frame, a MU-BAR (multi-user block acknowledgment request) trigger frame, or a basic trigger frame, and the ICF can be a frame for requesting an ICR (e.g., an M-BA (multi-station block acknowledgment) frame or a multi-STA block ack frame). The ICF can include an AID (association identifier) ​​of at least one STA for which transmission of an ICR is requested. It should be understood that the device initiating the TXOP can include not only an AP but also a non-AP STA. As another example, a peer STA can control (or schedule) the time interval of transmitting a DL PPDU or requesting a UL TB PPDU so that it does not overlap with the unavailable time reported via ICR from the STA with IDC.

[0133] An STA with an IDC (e.g., a non-AP STA) that receives an ICF transmits an ICR, which may include information about the time and duration of an unavailability that overlaps with or follows the initiated TXOP. In one example, the ICR may include the aforementioned M-BA frame or a multi-TID (traffic identifier) ​​block Ack frame. The information included in the ICR may include parameters or information about an unavailability associated with the TXOP or an IDC to be applied to the TXOP. Such an IDC may be an IDC due to an aperiodic, unexpected, or instantaneous unavailability.

[0134] FIG. 11 illustrates an exemplary format of an M-BA (or multi-STA BA (multi station block acknowledgment)) frame related to the present disclosure.

[0135] The M-BA frame illustrated in FIG. 11 may be a type of control frame. The M-BA frame may include at least one of a frame control field, a duration field, a receiving address (RA) field, a transmitter address (TA) field, a block ack control (BA) field, a BA information field (1110), or a frame check sequence (FCS) field. The BA information field may include a per AID TID information field (1120).<AID, TID> Each tuple can include. Each Per AID TID information field (1120) can include an AID TID information field (1130), a Block Ack starting sequence control field (1140), and a Block Ack bitmap field (1150).

[0136] The AID TID information field (1130) may include an AID11 field, an Ack Type field, and a TID field, and the fields included in the AID TID information field (1130) will be described in detail later in FIG. 13.

[0137] FIG. 12 is a diagram illustrating an example of fields included in an M-BA frame related to the present disclosure.

[0138] According to one embodiment, the value of a specific field included in the M-BA frame may be assigned as a value indicating unavailability or IDC for TXOP. For example, a specific value among the values ​​indicated by the AID (association identifier) ​​field included in the M-BA frame may be assigned as a value indicating control extension. Additionally, specific values ​​among the values ​​indicated by the Ack Type field and the TID field included in the M-BA frame may be assigned as values ​​indicating unavailability or IDC.

[0139] For example, any one of the values ​​indicated by the 11 bits included in the AID11 field of the M-BA frame may be assigned to indicate a control extension. As another example, any one of the combinations of the values ​​indicated by the 1 bit included in the Ack Type field of the M-BA frame and the values ​​indicated by the 4 bits included in the TID field may be assigned to indicate a control extension. Control extension may mean a case where a control frame is used for an extended purpose other than its original usage.

[0140] Specifically, any one of the reserved values ​​from 2008 to 2042 among the values ​​indicated by the AID11 field of the M-BA frame may be assigned to indicate control extension of the M-BA frame. Alternatively, the AID11 field of the M-BA frame may also assign any one of the AID values ​​that may be assigned for the STA to indicate control extension of the M-BA frame. For example, a specific value (e.g., 2006, etc.) among the values ​​that may be assigned as the AID of the STA may be utilized for control extension of the M-BA frame. In addition, a combination of 0 or 1 among the values ​​of the Ack Type field of the M-BA frame and 8 to 13 among the values ​​of the TID field may be assigned to indicate unavailability or IDC among the control extensions. Any one of the reserved cases of the combination of the values ​​of the Ack Type field and the TID field can be utilized to indicate unavailability or IDC for the TXOP, and an example of this is illustrated in FIG. 12 (1210).

[0141] FIG. 13 is a diagram illustrating an exemplary format of a field included in a frame according to one embodiment of the present disclosure.

[0142] FIG. 13 illustrates an example of a format structure in which an M-BA frame includes an AID TID information field (1310), a Block Ack starting sequence control field (1320), and a Block Ack bitmap field (1330). In addition, FIG. 13 illustrates an embodiment in which the AID TID information field (1310) includes an 11-bit AID11 field (1340), a 1-bit Ack Type field (1350), and a 4-bit TID field (1360), and the Block Ack starting sequence control field (1320) includes a 4-bit fragment number field (1370) and a 12-bit starting sequence number field (1380).

[0143] Hereinafter, an embodiment proposed in the present disclosure will be described in more detail based on the format structure and fields of the frame illustrated in FIG. 13. In one embodiment, a non-AP STA may transmit an M-BA frame to an AP, and the M-BA frame may be a frame for notifying or feedback of aperiodic, unexpected, or instantaneous unavailability or IDC within a TXOP. In one example, the M-BA frame transmitted by the STA may include an ICR, which is a response to an ICF, within the TXOP, and in this case, the M-BA frame may include information about the unavailability or IDC according to the proposed embodiment. In another example, the M-BA frame transmitted by the STA may include an acknowledgment for a PPDU within the TXOP, and in this case, the M-BA frame may include not only an acknowledgment for the PPDU, but also information about the unavailability or IDC when the unpredictable unavailability or IDC suddenly occurs in an STA operating within the TXOP.

[0144] According to one embodiment, the AID11 field (1340) of the M-BA frame that the STA transmits to the AP to indicate unavailability or IDC for TXOP may include a predetermined value (e.g., 2009 or any one of other reserved values) to indicate control extension. Alternatively, the AID11 field (1340) of the M-BA frame that the STA transmits to the AP to indicate unavailability or IDC for TXOP may include the AID of the STA or the AID of the AP, and a combination of the value of the Ack Type field (1350) and the value of the TID field (1360) may include values ​​to indicate unavailability or IDC (e.g., the value of the Ack Type field may include 0 or 1, and the value of the TID field may include 8 or any one of the reserved values ​​8 to 13).

[0145] According to one embodiment, the fragment number field (1370) of the Block Ack start sequence control field (1320) may indicate the size of the Block Ack bitmap field (1330), and the start sequence number field (1380) of the Block Ack start sequence control field (1320) may include AID12 or AID11 of an STA transmitting an M-BA frame to indicate unavailability or IDC. Alternatively, the start sequence number field (1380) of the Block Ack start sequence control field (1320) may include AID12 or AID11 of an AP or non-AP STA receiving an M-BA frame instead of AID12 or AID11 of an STA transmitting an M-BA frame.

[0146] According to one embodiment, the Block Ack bitmap field (1330) includes actual information transmitted for control extension. For example, if the M-BA frame is transmitted to indicate unavailability or IDC, the Block Ack bitmap field (1330) may include specific information about the unavailability or IDC. For example, the Block Ack bitmap field (1330) may include an unavailability information field or an IDC information field (or an IDC information feedback field).

[0147] The above describes an embodiment in which a non-AP STA transmits an M-BA frame to notify the AP of unavailability or IDC for a TXOP. Alternatively, an AP may also transmit an M-BA frame to notify a non-AP STA of unavailability or IDC for a TXOP. If an AP transmits an M-BA frame to notify unavailability or IDC, the explanations previously provided for STAs may be applied identically or similarly to the AP.

[0148] FIG. 14 is a diagram illustrating an exemplary format of a field included in a frame according to one embodiment of the present disclosure.

[0149] Figure 14 specifically describes the unavailability or IDC-related information for the TXOP described above. Figure 14 illustrates an exemplary format structure of the IDC feedback information field described above, and the IDC feedback information field depicted in Figure 14 can be understood as the unavailability information field or IDC information field described above.

[0150] An IDC feedback information field according to an embodiment may include at least one of a time unit field (1410), a start time field (1415), a duration field (1420), a presence field (1425), a radio mode field (1430), a bandwidth field (1435), a number of spatial stream (NSS) field (1440), a service specific identifier field (1445), a traffic information field (1450), or a preferred link field (1455), and some of the 128 bits included in the IDC feedback information field may be reserved.

[0151] The time unit field (1410) may indicate the unit that the value indicated by the subsequent duration field (1420) signifies. For example, if the value of the time unit field (1410) is 0, 1, ..., 7, it may indicate that the units of the values ​​indicated by the duration field (1420) are 1 μs, 2 μs, ..., 128 μs, respectively. Alternatively, the time unit field (1410) may also include a bitmap for indicating a unit of powers of 2.

[0152] The start time field (1415) and the duration field (1420) may indicate the start time of unavailability or IDC and the length of the time interval during which unavailability or IDC lasts, respectively. The start time field (1415) and the duration field (1420) may indicate a value in a predetermined time unit or TU (time unit).

[0153] The presence field (1425) may indicate whether any of the fields for indicating IDC capabilities (e.g., the wireless mode field (1430), the bandwidth field (1435), the number of spatial streams field (1440), the service specific identifier field (1445), the traffic information field (1450), or the preferred link field (1455)) is included in the IDC feedback information field.

[0154] The radio mode field (1430) may indicate a transmission mode or reception mode during unavailability or IDC time. For example, a value of 0 in the radio mode field (1430) may be used for full unavailability, a value of 1 may be used for Tx only mode, a value of 2 may be used for Rx only mode, a value of 3 may be used for both Tx and Tx modes, and the remaining values ​​may be reserved.

[0155] The bandwidth field (1435) (or channel field) may indicate the subchannel to be used during unavailability or IDC time. For example, assuming the primary 20 MHz is set as the lowest channel number, 0x0003 (1 bit corresponds to a 20 MHz subchannel, so 2 octets for 320 MHz) may indicate that the possible subchannel set is known as the primary 40 MHz channel. Conversely, this field may also be used to indicate a subchannel that is unavailable during unavailability or IDC time.

[0156] The spatial stream count field (1440) may indicate the maximum number of spatial streams that can be used during unavailability or IDC time.

[0157] The service specific identifier field (1445) may identify the type of heterogeneous technology (i.e., other wireless access technologies, e.g., BT, BLE, 5G, UWB, LAA, NR-U, etc.) or P2P connection to be used during unavailability or IDC time.

[0158] The traffic information field (1450) may include information about the type of traffic available during unavailability or IDC time. For example, the traffic information field (1450) may indicate traffic information such as TID, AC (access category), TSID (traffic stream identifier), etc. In addition, the traffic information field (1450) may include a bitmap for indicating the type of traffic or an encoded number mapped to each type of traffic.

[0159] The preferred link field (1460) may indicate a bitmap of alternative links for a specific link that is unavailable or unavailable during IDC periods. Additionally, the traffic information field (1450) may include a list of link identifiers for indicating alternative links.

[0160] The above describes an exemplary format of the IDC feedback information field (or, unavailability information field or IDC information field) for indicating unavailability or IDC. However, the Block Ack bitmap field including information for indicating unavailability or IDC may be configured to include fewer or more fields than the structure illustrated. For example, the Block Ack bitmap field may include fewer or equal number of bits than 64 bits, in which case the IDC feedback information field of the Block Ack bitmap field may be configured to include only some fields while omitting some fields from the illustrated embodiment. If the Block Ack bitmap field includes only some of the fields according to the illustrated embodiment, which fields / subfields are included in the IDC feedback information field may be indicated by the presence field (1425) described above.

[0161] FIGS. 15 and 16 are diagrams illustrating exemplary formats of fields included in a frame according to an embodiment of the present disclosure. FIGS. 15 and 16 illustrate an embodiment for reporting unavailability or IDC-related information in a case where MLO (multi-link operation) is applied.

[0162] Devices (STAs and non-AP STAs) that implement MLO are called multi-link devices (MLDs), and MLDs can communicate with other MLDs via one or more links. When communication occurs across multiple links, the unavailability or IDC described above must be announced for each link.

[0163] Therefore, the following describes an embodiment in which a device transmits information (e.g., IDC feedback information) to indicate unavailability or IDC as described above for a specific link. According to the proposed embodiment, unavailability or IDC related information for a specific link or for each link may be referred to as link unavailability information or link IDC information. The link unavailability information or link IDC information may further include information on a link to which unavailability or IDC related fields are applied, in addition to the embodiments described above with reference to FIGS. 11 to 14. For convenience of explanation, the link unavailability information or link IDC information is referred to as a link IDC element.

[0164] In the embodiment illustrated in FIG. 15, the link IDC element may include a link identifier (link ID) and IDC feedback information. The link identifier may include an identifier of a link to which unavailability or IDC is applied, which is specified by parameters and information of the IDC feedback information. The time unit field, start time field, duration field, existence field, and fields for indicating IDC capabilities included in the link IDC element may be applied identically or similarly to those described in FIG. 14, and thus a detailed description thereof will be omitted.

[0165] When a non-AP STA or AP that is MLD reports information indicating unavailability or IDC, the above-described link IDC element must be able to be reported for each link. In particular, when a non-AP STA or AP that is MLD reports unavailability or IDC for a TXOP of a specific link, reporting unavailability or IDC for other links as well can help to efficiently control unavailability or IDC.

[0166] Below, various embodiments of configuring link IDC elements for each of a plurality of links are described in FIG. 16. FIG. 16 illustrates embodiments of configuring link IDC elements for a plurality of links by cascading them, respectively, in (a), (b), and (c).

[0167] According to the embodiment illustrated in (a) of FIG. 16, an M-BA frame for notifying unavailability or IDC may include an AID TID information field (1612) for indicating control extension and unavailability or IDC, a Block Ack Start Sequence Control field (1614) for indicating the size of the Block Ack bitmap field and the number of link IDC elements included in the Block Ack bitmap, and a Block Ack bitmap field (1616) including link IDC elements for multiple links (1610). In the embodiment illustrated in (a) of FIG. 16, the Block Ack Start Sequence Control field (1614) may indicate the number of link IDC elements or IDC feedback information fields included in the Block Ack bitmap field (1616) in addition to the embodiment described above. Additionally, in the embodiment illustrated in (a) of FIG. 16, the Block Ack bitmap field (1616) may be configured in a form of concatenation or cascade of bitmaps equal to the number of links for which unavailability or IDC is to be reported (illustrated as # in (a) of FIG. 16).

[0168] According to the embodiment illustrated in (b) of FIG. 16, an M-BA frame for notifying unavailability or IDC may have a format structure in which a combination of a control extension and an AID TID information field (1621, 1624) for indicating unavailability or IDC, a Block Ack start sequence control field (1622, 1625) for indicating the size of a Block Ack bitmap field and an AID of a non-AP STA or AP transmitting the M-BA frame, and a Block Ack bitmap field (1623, 1626) including a link ID element are concatenated or cascaded for each of a plurality of links (1620). In the embodiment illustrated in (b) of FIG. 16, the M-BA frame may be configured such that the combination of the AID TID information fields (1621, 1624), the Block Ack start sequence control fields (1622, 1625), and the Block Ack bitmap fields (1623, 1626) may be specifically applied to each link. That is, the combination of the AID TID information fields (1621, 1624), the Block Ack start sequence control fields (1622, 1625), and the Block Ack bitmap fields (1623, 1626) may be repeated as many times as the number of links for which unavailability or IDC is reported to configure the M-BA frame. In the embodiment illustrated in (b) of FIG. 16, the AID TID information fields (1621, 1624) may exist separately for each link.

[0169] According to the embodiment illustrated in (c) of FIG. 16, an M-BA frame for notifying unavailability or IDC may include an AID TID information field (1631) for indicating control extension and unavailability or IDC, a Block Ack start sequence control field (1632) for indicating the size of a Block Ack bitmap field and an AID of a non-AP STA or AP transmitting the M-BA frame, and a Block Ack bitmap field (1633) including unavailability information or IDC information (or an IDC feedback information field). In one example, the Block Ack start sequence control field (1632) may include an AID of a non-AP STA or AP receiving the M-BA frame instead of an AID of a non-AP STA or AP transmitting the M-BA frame. In the embodiment illustrated in (c) of FIG. 16, the Block Ack bitmap field (1633) may include a link IDC element count field (1634) for indicating the number of link IDC elements for each of the plurality of links, and link IDC elements (1635, 1636) for each of the plurality of links (1630). The embodiment illustrated in (c) of FIG. 16 is different from the embodiment illustrated in (a) of FIG. 16, which is indicated through the Block Ack start sequence control field, in that a field for indicating the number of reported link IDC elements is separately included in the Block Ack bitmap field.

[0170] According to the embodiments described above, a non-AP STA may transmit an M-BA frame to an AP to indicate unavailability or IDC for a TXOP. Conversely, an AP may also transmit an M-BA frame to a non-AP STA to indicate unavailability or IDC for a TXOP. In addition, a non-AP STA and an AP may transmit an M-BA frame to indicate unavailability or IDC even in a single-STA single-TID situation, and in particular, an M-BA frame to indicate unavailability or IDC may be used as a response to an aggregated MAC PDU (A-MPDU) transmission in a single-STA single-TID and for control extension. In addition, a non-AP STA or an AP may transmit an M-BA frame to indicate unavailability or IDC in response to a trigger frame transmitted from an AP or a non-AP STA. That is, an AP or non-AP STA may transmit an M-BA frame to indicate unavailability or IDC in response to a trigger frame even if it does not receive data.

[0171] According to the proposed embodiments, an STA may report or inform the AP of partial or full unavailability within a TXOP initiated by the AP (or mobile AP). Hereinafter, full unavailability may mean a state in which neither transmission nor reception using the WLAN of a non-AP STA or the AP is possible during the duration in which an IDC operation for the TXOP is applied. For example, a case in which the value of the wireless mode field (1430) of FIG. 14 is 0 may indicate full unavailability. Hereinafter, partial unavailability may refer to a situation in which, during the period in which the IDC operation for the TXOP is applied, only transmission using the WLAN of a non-AP STA or AP is possible (i.e., reception is not possible), reception using the WLAN is possible (i.e., transmission is not possible), or both transmission and reception using the WLAN are possible but operation is possible in a state other than the full capability (e.g., reduced bandwidth, reduced NSS, etc.). In addition, the AP (or mobile AP) may notify part or all of the unavailability within the TXOP it initiated to its associated STAs (i.e., non-AP STAs). In addition, the AP (or mobile AP) may notify part or all of the unavailability within the TXOP it initiated. In addition, the AP (or mobile AP) may also notify the unavailability right after the TXOP it initiated, which may correspond to an operation to save power consumption of the AP (or mobile AP) even if it is not an unavailability or IDC within the TXOP.

[0172] FIGS. 16A and 16B are diagrams illustrating exemplary formats of fields included in a frame according to one embodiment of the present disclosure.

[0173] According to one proposed embodiment, an M-BA frame may include unavailability or IDC related information (or IDC feedback information) for a specific link and one or more other links, even if there is no unavailability or IDC for a TXOP of the specific link among multiple links (e.g., unavailability or IDC for a predetermined time interval within or after the TXOP). For example, when unavailability or IDC occurs in one or more links, the M-BA frame may indicate a link (or links) to be used for transmission or reception instead of the link on which the unavailability or IDC occurred. According to this embodiment, the M-BA frame may be utilized to provide unavailability or IDC status or unavailability or IDC related information for the entire link and the link on which the M-BA frame is transmitted between an AP and a non-AP STA. In other words, the AP and non-AP STAs may transmit and / or receive M-BA frames to indicate a specific link to be used as a substitute when unavailability or IDC occurs on multiple links instead of unavailability or IDC-related information for a specific TXOP. According to this embodiment, the unavailability or IDC-related information included in the M-BA frame may indicate not only information about the time of unavailability or IDC, but also information for effectively controlling unavailability or IDC of all links (or links on which the M-BA frame is transmitted) related to MLO.

[0174] An M-BA frame according to this embodiment may include information to indicate one or more preferred links (or alternate links) to be used in the event of unavailability or IDC among all links, and formats of frames according to this embodiment are illustrated in FIGS. 16A and 16B.

[0175] The exemplary format of the frame illustrated in FIG. 16A may be a modified example of the format described in (a) of FIG. 16 above. In the structure illustrated in FIG. 16A, the Block Ack bitmap field (1616) of the M-BA frame may include a preferred link field (1680) for indicating a preferred link (or alternate link) for all links. Unlike the preferred link (or alternate link) applied to a specific link described in FIGS. 14, 15, and 16 above, the preferred link field (1680) according to the structure of FIG. 16A may indicate a preferred link (or alternate link) to be used instead when unavailability or IDC occurs in at least some of the entire links, and the specific link indicated by the preferred link field (1680) may be commonly applied to all links. According to the proposed embodiment, since the preferred link field (1680) indicates a link common to all links (or indicates a preferred link or an alternative link for the link on which the M-BA frame is transmitted), among the fields / subfields for indicating the IDC capabilities of the IDC elements (1688, 1689, etc.) for each link, bits corresponding to the preferred link field described in FIG. 14 above may be reserved (1685).

[0176] The exemplary format of the frame illustrated in FIG. 16b may be a modified example of the format described in (c) of FIG. 16 above. In the structure illustrated in FIG. 16b, the Block Ack bitmap field (1633) of the M-BA frame may include a preferred link field (1690) for indicating a preferred link (or alternate link) for all links. Unlike the preferred link (or alternate link) applied to a specific link described in FIGS. 14, 15, and 16 above, the preferred link field (1690) according to the structure of FIG. 16b may indicate a preferred link (or alternate link) to be used instead when unavailability or IDC occurs in at least some of the entire links, and the specific link indicated by the preferred link field (1690) may be commonly applied to all links. According to the proposed embodiment, since the preferred link field (1690) indicates a link common to all links (or indicates a preferred link or an alternative link for the link on which the M-BA frame is transmitted), among the fields / subfields for indicating the IDC capabilities of the IDC elements (1698, 1699, etc.) for each link, bits corresponding to the preferred link field described in FIG. 14 above may be reserved (1695).

[0177] FIG. 17 is a diagram illustrating an exemplary format of a field included in a frame according to one embodiment of the present disclosure.

[0178] An embodiment in which a device transmits or receives an M-BA frame to indicate unavailability or IDC for a TXOP has been described above. FIG. 17 illustrates an embodiment in which a device (non-AP STA or AP) transmits or receives a multi-TID block ack frame to indicate unavailability or IDC for a TXOP.

[0179] Fig. 17 illustrates an exemplary structure of a BA (block ack) information field included in a multi-TID block ack frame. In addition to the fields illustrated in Fig. 17, the multi-TID block ack frame may further include a MAC header including a frame control field, a duration field, an RA field, and a TA field, as well as a BA control field, an FCS field, and the like. The same descriptions of the M-BA frame described in Fig. 11 may be applied to other fields included in the multi-TID block ack frame. According to one embodiment, a multi-TID block ack frame (or a BA information field of a multi-TID block ack frame) may include a Per TID information field (1710), a Block Ack starting sequence control field (1720), and a Block Ack bitmap field (1730), and the Per TID information field (1710), the Block Ack starting sequence control field (1720), and the Block Ack bitmap field (1730) may be repeated for each TID within the multi-TID block ack.

[0180] According to one embodiment, the Per TID information field (1710) may include a TID value field (1740) and reserved bits, and the Block Ack start sequence control field (1720) may include a fragment number field (1750) and a start sequence number field (1760). In one embodiment, the size of the Block Ack bitmap field (1730) may be fixed to 8 octets, and the fragment number field (1750), which indicates the size of the Block Ack bitmap field (1730), may indicate a fixed value of 0.

[0181] Hereinafter, an embodiment proposed in the present disclosure will be described in more detail based on the format structure and fields of the frame illustrated in FIG. 17. In one embodiment, a non-AP STA may transmit a multi-TID block ack frame to an AP, and the multi-TID block ack frame may be a frame for notifying or feedback of aperiodic, unexpected, or instantaneous unavailability or IDC within a TXOP. The multi-TID block ack frame transmitted by a non-AP STA may include an acknowledgment for a PPDU, and may further include information for indicating a control extension related to unavailability or IDC for the TXOP.

[0182] According to one embodiment, in a multi-TID block ack frame that a non-AP STA transmits to an AP to indicate unavailability or IDC for a TXOP, 11 bits (e.g., B0 - B10) or 12 bits (e.g., B0 - B11) of the 12 reserved bits (B0 - B11) included in the per TID information field (1710) may be used to indicate a control extension, and examples of specific values ​​may be similarly applied to the embodiment described in the AID11 field (1340) described above in FIG. 13.

[0183] According to another embodiment, in a multi-TID block ack frame that a non-AP STA transmits to an AP to indicate unavailability or IDC for a TXOP, a combination of a value of one bit (e.g., B11) among 12 reserved bits (B0 to B11) included in a per TID information field (1710) and a value of a TID value field (1740) may include values ​​for indicating unavailability or IDC. A specific example of a combination of a value of one reserved bit and a value of a TID value field (1740) may be similarly applied to the embodiment described in the Ack Type field (1350) and the TID field (1360) described above in FIG. 13, and the value of the TID value field (1740) may be any one of reserved 8 to 15.

[0184] In another embodiment, any one of the reserved values ​​of the TID value field (1740) in the multi-TID block ack frame that a non-AP STA transmits to the AP to indicate unavailability or IDC for a TXOP may indicate unavailability or IDC. For example, any one of the reserved values ​​8 to 15 of the TID value field (1740) may indicate unavailability or IDC.

[0185] In one embodiment, the start sequence number field (1760) included in the Block Ack start sequence control field (1720) may include AID11 or AID12 of a non-AP STA or AP transmitting a multi-TID block ack frame. Alternatively, the start sequence number field (1760) of the Block Ack start sequence control field (1720) may include AID12 or AID11 of an AP or non-AP STA receiving a multi-TID block ack frame instead of AID12 or AID11 of a non-AP STA or AP transmitting a multi-TID block ack frame. The Block Ack bitmap field (1730) includes actual information transmitted for control extension and may have a fixed size of 8 octets. For example, the Block Ack bitmap field (1730) may include at least some of the various fields / subfields included in the Block Ack bitmap field (1330) described in FIG. 13 and the IDC feedback information field described in FIG. 14, and at least some may be omitted. For example, the Block Ack bitmap field (1730) of the multi-TID block ack frame may be configured to include only some of the IDC capability-related fields / subfields described in FIG. 14.

[0186] The above describes an embodiment in which a non-AP STA transmits a multi-TID block ack frame to notify the AP of unavailability or IDC for a TXOP. Conversely, an AP (or a mobile AP) may also transmit a multi-TID block ack frame to notify a non-AP STA of unavailability or IDC for a TXOP. When an AP transmits a multi-TID block ack frame to notify unavailability or IDC, the explanation given above for the STA may be applied to the AP in the same or similar manner. When a mobile AP transmits a multi-TID block ack frame to notify a non-AP STA of unavailability or IDC for a TXOP, the corresponding TXOP may be a TXOP initiated by a non-AP STA. Alternatively, if the AP (or mobile AP) needs to use a shorter TXOP than the initiated TXOP due to some reason (e.g., if IDC is expected from the AP (or mobile AP), if the mobile AP is moving, etc.), the AP (or mobile AP) may transmit a multi-TID block ack frame to inform non-AP STAs of unavailability or IDC.

[0187] FIG. 18 is a flowchart illustrating operations for applying IDC to TXOP according to one embodiment of the present disclosure. FIG. 18 illustrates and describes, in a time-series fashion, operations of a non-AP STA and an AP according to various embodiments described previously in FIGS. 11 to 17.

[0188] When an AP supporting a BSS with a bandwidth of 160MHz transmits an ICF to initiate a TXOP (1805), non-AP STA1 and non-AP STA2, which receive this, transmit M-BA frames to the AP in response to the ICF (1810, 1835). Non-AP STA1 and non-AP STA2 may transmit information to the AP to indicate unavailability or IDC, as unavailability exists due to IDC operation within the TXOP initiated by the AP.

[0189] In the embodiment illustrated in FIG. 18, when non-AP STA1 recognizes that partial unavailability (1825) will occur in the TXOP, operating with half bandwidth and reduced NSS, the non-AP STA1 may transmit an M-BA frame including IDC feedback information to the AP (1810) to indicate partial unavailability (1825). The AP verifies that the M-BA frame received from non-AP STA1 includes unavailability or IDC-related information for the TXOP. The AP transmits a DL PPDU to the non-AP STA1 at a time that does not overlap with the unavailability of the non-AP STA1 within the TXOP (1815). Alternatively, unlike the embodiment illustrated, the AP may schedule the transmission of a UL TB PPDU of the non-AP STA1 at a time that does not overlap with the unavailability of the non-AP STA1. Transmission of a DL PPDU (or reception of a UL TB PPDU) can be performed using both the full bandwidth of 160MHz and the full NSS because it does not overlap with the partial unavailability (1825) of a non-AP STA. Non-AP STA1, which has received a DL PPDU from the AP, can transmit an M-BA frame to the AP to acknowledge the DL PPDU (1820). This M-BA frame can include not only the acknowledgement for the DL PPDU but also information about the partial unavailability (1825) that will occur within the TXOP.The AP transmits a new DL PPDU to the non-AP STA1 (1830), and since the transmission of this DL PPDU overlaps with the partial unavailability (1825) of the non-AP STA1 within the TXOP, it can be transmitted using limited capabilities (e.g., limited bandwidth and limited NSS) (1830). The description of the DL PPDU transmission (1830) due to the partial unavailability (1825) of the non-AP STA1 is only an example, and the same operation can be applied to the UL TB PPDU transmission of the non-AP STA1.

[0190] In the embodiment illustrated in FIG. 18, when non-AP STA2 recognizes that full unavailability (1840) that is completely inoperable will occur in TXOP, non-AP STA2 can transmit an M-BA frame including IDC feedback information to AP (1835) to indicate full unavailability (1840). AP confirms that the M-BA frame received from non-AP STA2 includes unavailability or IDC-related information for TXOP. Since full unavailability (1840) of non-AP STA2 and transmission of DL PPDU (1815) overlap within TXOP, AP does not transmit DL PPDU to non-AP STA2. The AP can receive a UL TB PPDU from the non-AP STA2 by triggering the UL of the non-AP STA2 after the full unavailability (1840) of the non-AP STA2 is terminated within the TXOP (1845). The description of the UL TB PPDU transmission (1845) due to the full unavailability (1840) of the non-AP STA2 is only an example, and the same operation can be applied to the operation of transmitting a DL PPDU to the non-AP STA2.

[0191] In the above, an embodiment in which a non-AP STA notifies unavailability or IDC for a TXOP through an M-BA frame has been described. Meanwhile, it is of course possible for a non-AP STA to notify unavailability or IDC for a TXOP through a multi-TID block ack frame according to another embodiment described above. In addition, although the illustrated embodiment has described an embodiment in which a non-AP STA reports its unavailability or IDC for a TXOP initiated by an AP, it is of course also applicable to an embodiment in which an AP notifies its unavailability or IDC for a TXOP initiated by a non-AP STA. Furthermore, the above-described embodiments can be equally applied to the operation of not only a general AP but also a mobile AP.

[0192] FIG. 19 illustrates a flowchart of operations for applying IDC according to one embodiment of the present disclosure. Some or all of the various embodiments described above regarding the process by which a non-AP STA notifies unavailability or IDC may be applied identically or similarly to FIG. 19.

[0193] In the illustrated embodiment, a non-AP STA receives a first frame for a TXOP from an AP (1910). The first frame received by the non-AP STA may be an ICF frame for the AP to initiate a TXOP, and may include, for example, at least one of a BSRP trigger frame, a BQRP trigger frame, a MU-BAR trigger frame, or a basic trigger frame. In another example, the first frame received by the non-AP STA may be a frame including a DL PPDU.

[0194] The non-AP STA transmits a second frame to the AP that includes unavailability information (or IDC information) related to the TXOP (1920). The second frame transmitted by the non-AP STA may be an ICR frame that is a response to an ICF frame. For example, the second frame may include an ICR frame that includes an M-BA frame for indicating unavailability information (or IDC information). In another example, the second frame transmitted by the non-AP STA may include a multi-TID block ack frame for indicating unavailability information (or IDC information) together with a response to a DL PPDU. In another example, in the case of a non-AP STA MLD, the second frame may include unavailability information (or IDC information) for each of a plurality of links.

[0195] A non-AP STA operates within a TXOP based on unavailability information (or IDC information) transmitted to the AP (1930). For example, a non-AP STA may operate by limiting some capabilities (i.e., partial unavailability) or by limiting all capabilities (i.e., full unavailability) during a time period determined by the unavailability information (or IDC information) within the TXOP. A non-AP STA limiting its capabilities may mean that it does not perform WLAN-related operations, and may include that the non-AP STA does not receive DL data from the AP via WLAN or does not transmit UL data to the AP. As another example, a non-AP STA may receive or transmit data through another link on which unavailability or IDC does not occur based on preferred link information included in the unavailability information (or IDC information) among multiple links.

[0196] Meanwhile, an example of signaling operations between a non-AP STA and an AP has been described based on the flowchart illustrated in FIG. 19 above. However, it should be understood that operations between a non-AP STA and an AP may vary depending on other embodiments described above.

[0197] Figure 20 illustrates a flowchart of operations for applying IDC according to one embodiment of the present disclosure. Some or all of the various embodiments described above regarding the process by which an AP receives unavailability or IDC-related information may be applied identically or similarly to Figure 19.

[0198] In the illustrated embodiment, the AP transmits a first frame for a TXOP to a non-AP STA (2010). The first frame transmitted by the AP may be an ICF frame for the AP to initiate a TXOP, and may include, for example, at least one of a BSRP trigger frame, a BQRP trigger frame, an MU-BAR trigger frame, or a basic trigger frame. In another example, the first frame transmitted by the AP may be a frame including a DL PPDU.

[0199] The AP receives a second frame including unavailability information (or IDC information) related to a TXOP from a non-AP STA (2020). The second frame received by the AP may be an ICR frame that is a response to an ICF frame, and as an example, the second frame may include an ICR frame including an M-BA frame for indicating unavailability information (or IDC information). In another example, the second frame received by the AP may include a multi-TID block ack frame for indicating unavailability information (or IDC information) together with a response to a DL PPDU. In another example, when the AP MLD establishes multiple links with the non-AP STA MLD, the second frame may include unavailability information (or IDC information) for each of the multiple links.

[0200] The AP operates within the TXOP according to the unavailability information (or IDC information) received from the non-AP STA (2030). For example, the AP may schedule, trigger, or poll the non-AP STA considering that some of the capabilities of the non-AP STA are limited (i.e., partial unavailability) during a time period determined by the unavailability information (or IDC information) received from the non-AP STA within the TXOP, and may schedule, trigger, or poll the non-AP STA considering that the entire capabilities of the non-AP STA are limited (i.e., full unavailability). The limited capabilities of the non-AP STA may mean that the non-AP STA cannot perform WLAN-related operations, and the AP may include not transmitting DL data to the non-AP STA over the WLAN or not receiving UL data from the non-AP STA in consideration of the capability limitations of the non-AP STA. As another example, an AP may receive or transmit data through a link other than the one where unavailability or IDC does not occur based on preferred link information included in the unavailability information (or IDC information) among multiple links.

[0201] Meanwhile, based on the flowchart illustrated in FIG. 20, an example of signaling operations between a non-AP STA and an AP has been described. However, it should be understood that operations between a non-AP STA and an AP may vary depending on other embodiments described above.

[0202] FIG. 21 illustrates a flowchart of operations for applying IDC according to one embodiment of the present disclosure. Some or all of the various embodiments described above regarding the process by which a non-AP STA receives unavailability or IDC-related information may be applied identically or similarly to FIG. 21.

[0203] In the illustrated embodiment, a non-AP STA transmits a first frame for a TXOP to the AP (2110). The first frame transmitted by the non-AP STA may be an ICF frame for the AP to initiate a TXOP, and may include, for example, at least one of an RTS frame, a ranging frame, a BSRP trigger frame, a BQRP trigger frame, an MU-BAR trigger frame, or a basic trigger frame. In another example, the first frame transmitted by the non-AP STA may be a frame including a UL PPDU.

[0204] A non-AP STA receives a second frame from an AP that includes unavailability information (or IDC information) related to a TXOP (2120). The second frame received by the non-AP STA may be an ICR frame that is a response to an ICF frame. For example, the second frame may include an ICR frame that includes an M-BA frame for indicating unavailability information (or IDC information). In another example, the second frame received by the non-AP STA may include a multi-TID block ack frame for indicating unavailability information (or IDC information) together with a response to a UL PPDU. In another example, in the case of a non-AP STA MLD, the second frame may include unavailability information (or IDC information) for each of a plurality of links.

[0205] A non-AP STA operates within a TXOP based on unavailability information (or IDC information) received from the AP (2130). For example, a non-AP STA may communicate with an AP considering that some of the AP's capabilities are limited (i.e., partial unavailability) during a time period determined by the unavailability information (or IDC information) within the TXOP, and may communicate with an AP considering that the entire AP's capabilities are limited (i.e., full unavailability). A limited AP's capabilities may mean that the AP cannot perform WLAN-related operations, and a non-AP STA may include not expecting DL scheduling via WLAN or not transmitting UL data based on the capability limitations of the AP. As another example, a non-AP STA may receive or transmit data through another link where unavailability or IDC does not occur based on preferred link information included in the unavailability information (or IDC information) among multiple links.

[0206] Meanwhile, an example of signaling operations between a non-AP STA and an AP has been described based on the flowchart illustrated in FIG. 21 above. However, it should be understood that operations between a non-AP STA and an AP may vary depending on other embodiments described above.

[0207] FIG. 22 illustrates a flowchart of operations for applying IDC according to one embodiment of the present disclosure. Some or all of the various embodiments described above regarding the process by which an AP notifies unavailability or IDC may be applied identically or similarly to FIG. 22.

[0208] In the illustrated embodiment, the AP receives a first frame for a TXOP from a non-AP STA (2210). The first frame received by the AP may be an ICF frame for the non-AP STA to initiate a TXOP, and may include, for example, at least one of an RTS frame, a ranging frame, a BSRP trigger frame, a BQRP trigger frame, an MU-BAR trigger frame, or a basic trigger frame. In another example, the first frame received by the AP may be a frame including a UL PPDU.

[0209] The AP transmits a second frame including unavailability information (or IDC information) related to the TXOP to the non-AP STA (2220). The second frame transmitted by the AP may be an ICR frame in response to an ICF frame, and as an example, the second frame may include an ICR frame including an M-BA frame for indicating unavailability information (or IDC information). In another example, the second frame transmitted by the AP may include a multi-TID block ack frame for indicating unavailability information (or IDC information) together with a response to a UL PPDU. In another example, when the AP MLD establishes multiple links with the non-AP STA MLD, the second frame may include unavailability information (or IDC information) for each of the multiple links.

[0210] The AP operates within the TXOP according to the unavailability information (or IDC information) transmitted to the non-AP STA (2230). For example, the AP may operate by limiting some of its capabilities (i.e., partial unavailability) or by limiting all of its capabilities (i.e., full unavailability) during a time period determined by the unavailability information (or IDC information) within the TXOP. The AP limiting its capabilities may mean not performing WLAN-related operations, and may include the AP not transmitting DL data to the non-AP STA via the WLAN or not receiving UL data from the non-AP STA. As another example, the AP may receive or transmit data through another link where unavailability or IDC does not occur based on preferred link information included in the unavailability information (or IDC information) among multiple links.

[0211] Meanwhile, an example of signaling operations between a non-AP STA and an AP has been described based on the flowchart illustrated in FIG. 22 above. However, it should be understood that operations between a non-AP STA and an AP may vary depending on other embodiments described above.

[0212] Meanwhile, the present specification and drawings disclose preferred embodiments of the present disclosure, and although specific terms are used, they are used only in a general sense to easily explain the technical contents of the present disclosure and to help understand the disclosure, and are not intended to limit the scope of the present disclosure.

[0213] Furthermore, it will be apparent to those skilled in the art that, in addition to the embodiments described in this disclosure, other modifications based on the technical concepts of this disclosure are possible. For example, some or all of the contents of one embodiment described above may be combined with some or all of one or more other embodiments, and such combinations are also included in the embodiments proposed in this disclosure.

Claims

1. A method performed by a STA (station) of a wireless local area network (WLAN) system, A step of receiving a first frame for initiating a transmission opportunity (TXOP) from an AP (access point); and A step of transmitting a second frame to the AP to notify unavailability of the TXOP based on in-device coexistence (IDC), The second frame includes a first field for an AID (association identifier), a second field and a third field for indicating unavailability based on the IDC, and a fourth field including parameters related to the IDC. The above second field is an Ack Type field and the value of the Ack Type field is 0, A method wherein the third field is a TID (traffic identifier) ​​field and the value of the TID field is 13.

2. In paragraph 1, The above first field is an AID11 field, and the value of the AID11 field is a value for indicating the AID, 0, or control extension of the STA, A method wherein the fourth field includes a Block Ack bitmap field.

3. In paragraph 2, The parameters related to the IDC included in the Block Ack bitmap field include at least one of a time unit field, a start time field, a duration field, a presence field, a wireless mode field, a bandwidth field, a number of spatial stream (NSS) field, a service specific identifier field, a traffic information field, or a preferred link field. The fourth field above contains a plurality of parameter sets for a plurality of links, A method wherein each of the plurality of parameter sets includes a link identifier of a corresponding link.

4. In paragraph 1, The first frame is an initial control frame (ICF) for initiating the TXOP, and the second frame is an initial control response (ICR) for the ICF and includes an M-BA (multi-STA block ack) frame, or The first frame is a frame for transmitting a PPDU (physical layer protocol data unit), the second frame is a frame for transmitting an acknowledgment for the PPDU, and includes the M-BA frame, or The first frame is an ICF for initiating the TXOP, and the second frame is an ICR for the ICF and includes a multi-STA block ack frame, or A method wherein the first frame is a frame for transmitting a PPDU, the second frame is a frame for transmitting an acknowledgment for the PPDU, and includes the multi-STA block ack frame.

5. In a method performed by an AP (access point) of a wireless local area network (WLAN) system, A step of transmitting a first frame to initiate a transmission opportunity (TXOP) to a STA (station); and A step of receiving a second frame from the STA to notify unavailability of the TXOP based on in-device coexistence (IDC), The second frame includes a first field for an AID (association identifier), a second field and a third field for indicating unavailability based on the IDC, and a fourth field including parameters related to the IDC. The above second field is an Ack Type field and the value of the Ack Type field is 0, A method wherein the third field is a TID (traffic identifier) ​​field and the value of the TID field is 13.

6. In paragraph 5, The above first field is an AID11 field, and the value of the AID11 field is a value for indicating the AID, 0, or control extension of the STA, A method wherein the fourth field includes a Block Ack bitmap field.

7. In paragraph 6, The parameters related to the IDC included in the Block Ack bitmap field include at least one of a time unit field, a start time field, a duration field, a presence field, a wireless mode field, a bandwidth field, a number of spatial stream (NSS) field, a service specific identifier field, a traffic information field, or a preferred link field. The fourth field above contains a plurality of parameter sets for a plurality of links, A method wherein each of the plurality of parameter sets includes a link identifier of a corresponding link.

8. In the STA (station) of a wireless local area network (WLAN) system, At least one transceiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions, The above instructions are executed individually or in any combination by the at least one processor, so that the STA: Receive the first frame to initiate TXOP (transmission opportunity) from AP (access point), A second frame is set to be transmitted to the AP to notify unavailability based on IDC (in-device coexistence) for the above TXOP, The second frame includes a first field for an AID (association identifier), a second field and a third field for indicating unavailability based on the IDC, and a fourth field including parameters related to the IDC. The above second field is an Ack Type field and the value of the Ack Type field is 0, The third field above is a TID (traffic identifier) ​​field, and the value of the TID field is 13, STA.

9. In paragraph 8, The above first field is an AID11 field, and the value of the AID11 field is a value for indicating the AID, 0, or control extension of the STA, The STA, wherein the fourth field includes a Block Ack bitmap field.

10. In paragraph 9, The parameters related to the IDC included in the Block Ack bitmap field include at least one of a time unit field, a start time field, a duration field, a presence field, a wireless mode field, a bandwidth field, a number of spatial stream (NSS) field, a service specific identifier field, a traffic information field, or a preferred link field. The fourth field above contains a plurality of parameter sets for a plurality of links, STA, wherein each of the plurality of parameter sets includes a link identifier of a corresponding link.

11. In paragraph 8, The first frame is an initial control frame (ICF) for initiating the TXOP, and the second frame is an initial control response (ICR) for the ICF and includes an M-BA (multi-STA block ack) frame, or The first frame is a frame for transmitting a PPDU (physical layer protocol data unit), the second frame is a frame for transmitting an acknowledgment for the PPDU, and includes the M-BA frame, or The first frame is an ICF for initiating the TXOP, and the second frame is an ICR for the ICF and includes a multi-STA block ack frame, or An STA wherein the first frame is a frame for transmitting a PPDU, the second frame is a frame for transmitting an acknowledgment for the PPDU, and includes the multi-STA block ack frame.

12. In the AP (access point) of a wireless local area network (WLAN) system, At least one transceiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions, The above instructions are executed individually or in any combination by the at least one processor, so that the AP: Transmit the first frame to STA (station) to initiate TXOP (transmission opportunity), It is set to receive a second frame from the STA to notify unavailability based on IDC (in-device coexistence) for the above TXOP, The second frame includes a first field for an AID (association identifier), a second field and a third field for indicating unavailability based on the IDC, and a fourth field including parameters related to the IDC. The above second field is an Ack Type field and the value of the Ack Type field is 0, The third field above is a TID (traffic identifier) ​​field, and the value of the TID field is 13, AP.

13. In paragraph 12, The above first field is an AID11 field, and the value of the AID11 field is a value for indicating the AID, 0, or control extension of the STA, The fourth field above includes a Block Ack bitmap field, AP.

14. In paragraph 13, The parameters related to the IDC included in the Block Ack bitmap field include at least one of a time unit field, a start time field, a duration field, a presence field, a wireless mode field, a bandwidth field, a number of spatial stream (NSS) field, a service specific identifier field, a traffic information field, or a preferred link field. The fourth field above contains a plurality of parameter sets for a plurality of links, An AP, wherein each of the plurality of parameter sets includes a link identifier of a corresponding link.

15. In paragraph 12, The first frame is an initial control frame (ICF) for initiating the TXOP, and the second frame is an initial control response (ICR) for the ICF and includes an M-BA (multi-STA block ack) frame, or The first frame is a frame for transmitting a PPDU (physical layer protocol data unit), the second frame is a frame for transmitting an acknowledgment for the PPDU, and includes the M-BA frame, or The first frame is an ICF for initiating the TXOP, and the second frame is an ICR for the ICF and includes a multi-STA block ack frame, or An AP wherein the first frame is a frame for transmitting a PPDU, the second frame is a frame for transmitting an acknowledgment for the PPDU, and includes the multi-STA block ack frame.

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