Method and device for managing multiple links in wireless LAN system

Abstract

The present disclosure relates to an enhanced wireless LAN system. The present disclosure proposes a method and a device for an operation considering IDC to improve reliability of traffic in the enhanced wireless LAN system. Specifically, the present disclosure proposes a method and a device for a periodic TTLM procedure considering IDC in a multi-link operation.

Description

Method and device for managing multiple links in a 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 device for efficiently controlling and managing multiple links 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] The present disclosure proposes a method and device for efficiently controlling and managing multiple links for multi-link operation (MLO) in a wireless LAN system. In particular, the present disclosure proposes methods for controlling and managing multiple links while considering in-device coexistence (IDC) to ensure traffic reliability. Furthermore, the present disclosure specifically proposes a frame structure and procedures for such control and management.

[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] A method performed by a station (STA) according to one embodiment of the present disclosure may include the steps of transmitting, to an access point (AP), a first frame including a first periodic TTLM element for requesting periodic TTLM (TID (traffic identifier) ​​to link mapping) related to multi-link operation (MLO), wherein a TTLM control field of the first periodic TTLM element includes a field indicating whether the first periodic TTLM element includes a parameter for periodic TTLM; receiving, from the AP, a second frame including a second periodic TTLM element for responding to the request for periodic TTLM; and periodically changing the TTLM for the MLO based on the second frame.

[0008] A method performed by an access point (AP) according to one embodiment of the present disclosure may include the steps of: receiving, from a station (STA), a first frame including a first periodic TTLM element for requesting periodic TTLM (TID (traffic identifier) ​​to link mapping) related to multi-link operation (MLO), wherein a TTLM control field of the first periodic TTLM element includes a field indicating whether the first periodic TTLM element includes a parameter for periodic TTLM; transmitting, to the STA, a second frame including a second periodic TTLM element for responding to the request for periodic TTLM; and periodically changing the TTLM for the MLO based on the second frame.

[0009] According to one embodiment of the present disclosure, a station (STA) comprises: at least one transceiver; at least one processor communicatively coupled to the at least one transceiver; And at least one memory communicatively coupled to the at least one processor and storing instructions, wherein the instructions are individually or in any combination executed by the at least one processor, such that the STA: transmits to an access point (AP) a first frame including a first periodic TTLM element for a request of periodic TTLM (TID (traffic identifier) ​​to link mapping) related to multi-link operation (MLO), wherein a TTLM control field of the first periodic TTLM element includes a field indicating whether the first periodic TTLM element includes a parameter for periodic TTLM, and receives from the AP a second frame including a second periodic TTLM element for a response to the request of the periodic TTLM, and may be configured to change the TTLM periodically for the MLO based on the second frame.

[0010] An access point (AP) according to one embodiment of the present disclosure comprises: at least one transceiver; at least one processor communicatively coupled to the at least one transceiver; And at least one memory communicatively coupled to the at least one processor and storing instructions, wherein the instructions are individually or in any combination executed by the at least one processor, such that the AP: receives from a station (STA) a first frame including a first periodic TTLM element for a request of periodic TTLM (TID (traffic identifier) ​​to link mapping) related to multi-link operation (MLO), wherein a TTLM control field of the first periodic TTLM element includes a field indicating whether the first periodic TTLM element includes a parameter for periodic TTLM, and transmits to the STA a second frame including a second periodic TTLM element for a response to the request of the periodic TTLM, and may be configured to change the TTLM periodically for the MLO based on the second frame.

[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] FIG. 9 illustrates multi-link operation (MLO) in connection with the present disclosure.

[0021] FIG. 10 illustrates an exemplary format of an element for TTLM (TID (traffic identifier) ​​to link mapping) in connection with the present disclosure.

[0022] FIG. 11 is a diagram illustrating a TTLM procedure related to the present disclosure.

[0023] FIG. 12 is a diagram illustrating a TTLM procedure according to one embodiment of the present disclosure.

[0024] FIG. 13 illustrates the format of an exemplary element for a TTLM procedure according to one embodiment of the present disclosure.

[0025] FIG. 14 illustrates an exemplary format of a TTLM-related frame according to one embodiment of the present disclosure.

[0026] FIG. 15 illustrates an exemplary format of a TTLM-related frame according to one embodiment of the present disclosure.

[0027] FIG. 16 is a diagram illustrating a TTLM procedure according to one embodiment of the present disclosure.

[0028] FIG. 17 is a diagram illustrating a TTLM procedure and frame format according to one embodiment of the present disclosure.

[0029] FIG. 18 is a diagram illustrating a TTLM procedure and frame format according to one embodiment of the present disclosure.

[0030] FIG. 19 is a diagram illustrating a TTLM procedure according to one embodiment of the present disclosure.

[0031] FIG. 20 is a diagram illustrating a TTLM procedure according to one embodiment of the present disclosure.

[0032] FIG. 21 illustrates a flowchart of TTLM operation of a device according to one embodiment of the present disclosure.

[0033] FIG. 22 illustrates a flowchart of TTLM operation of a device according to one embodiment of the present disclosure.

[0034] FIG. 23 illustrates a flowchart of TTLM operation of a device according to one embodiment of the present disclosure.

[0035] FIG. 24 illustrates a flowchart of TTLM operation of a device 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 upon 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 identification). 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 so that the STA performing the scanning can find the wireless network and participate in the wireless network. In the BSS, the AP performs the role of periodically transmitting the beacon frame, and in the IBSS, the STAs within the IBSS take turns transmitting the beacon frame. When the STA performing the scanning receives a beacon frame, it stores the information about the BSS included in the beacon frame and moves to another channel, recording the beacon frame information on each channel. The STA receiving the beacon frame stores the BSS-related information included in the received beacon frame and moves to the next channel to perform scanning on the next channel in the same manner. Comparing active scanning and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.

[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 a random backoff count value selected by it, 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] FIG. 9 illustrates multi-link operation (MLO) in connection with the present disclosure.

[0122] As wireless LAN systems have evolved, a function has been introduced that allows a single device to communicate with other devices through multiple links. The operation of a device based on this function is called multi-link operation (MLO). A device that supports multi-link operation is called a multi-link device (MLD), and an MLD can mean a logical entity. For example, an MLD can mean a device that has one or more affiliated STAs (i.e., non-APs or APs) and a single MAC data service and a single MAC service access point for logical link control (LLC). In particular, a non-AP STA that supports multi-link operation is called a non-AP MLD, and an AP that supports multi-link operation is called an AP MLD.

[0123] Multi-link operation requires mapping a traffic identifier (TID) for specific traffic to one or more of the multi-links. This process is called TID to link mapping (TTLM). A TID can refer to an identifier used by upper-layer entities to distinguish between MAC entities and MAC SDUs (MSDUs) to support quality of service (QoS) among MAC data services.

[0124] For example, any one of up to 16 or more values ​​may be assigned to a particular TID. Furthermore, eight of the 16 TID values ​​may identify traffic categories (TCs), and the other eight may identify parameterized traffic streams (TSs).

[0125] The mechanism for mapping TIDs to links, i.e., the TTLM process, may refer to a process for determining the correspondence between TIDs during setup or association (or after performing setup or association) for downlink and uplink established through setup or association between a non-AP MLD and an AP MLD. If at least one TID is mapped to a specific link through the TTLM process, the link is defined as enabled, and if no TID is mapped to a specific link, the link can be defined as disabled. A TID must always be mapped to at least one set-up link unless admission control is applied. By default, a TID is mapped to all set-up links, so all set-up links can be activated.

[0126] According to the example of FIG. 9, TIDs 0 to 6 are mapped to link 1 set up between a non-AP MLD (STA-1) and an AP MLD (AP-1) (i.e., an enabled link), TID 7 is mapped to link 2 set up between a non-AP MLD (STA-2) and an AP MLD (AP-2) (i.e., an enabled link), and no TID is mapped to link 3 set up between a non-AP MLD (STA-3) and an AP MLD (AP-3) (i.e., a disabled link).

[0127] When a specific link is enabled (i.e., has a TID mapped to it), the link can be used for frame exchange, depending on the power state of the non-AP MLD operating on that link. Conversely, when a specific link is disabled (i.e., has no TID mapped to it), the link may not be used for frame exchange, either on the downlink or uplink.

[0128] The TTLM process described above can be performed through default mapping mode or negotiation mapping mode. Default mapping mode refers to a mode in which all TIDs are mapped to all links by the AP MLD, and since all TIDs are mapped to all links, all established links can be activated. Non-AP MLDs and AP MLDs that have performed multi-link setups can operate in this default mapping mode if negotiation for TTLM to other mappings is not performed, fails, or is torn down.

[0129] Negotiated mapping mode refers to a mode in which mapping is performed through a process in which a non-AP MLD transmits mapping information between a TID and a link to the AP MLD through a TTLM element included in a binding request frame or a TTLM request frame, and the AP MLD approves or rejects the request. If TTLM is negotiated between a non-AP MLD and an AP MLD, the non-AP MLD or the AP MLD can tear down or release the negotiated TTLM by transmitting a TTLM teardown frame. If TTLM is teardown, the non-AP MLD and the AP MLD can operate in the default mapping mode.

[0130] FIG. 10 illustrates an exemplary format of an element for TTLM in connection with the present disclosure.

[0131] A TTLM element may include an element identifier (ID) field, a length field, an element ID extension field, a TID-to-Link Mapping (TTLM) control field, and a link mapping of TID n field (where n is an integer greater than or equal to 0) to indicate a link to which each TID is mapped, as illustrated in FIG. 10. The TTLM control field may include 1 or 2 octets, and may include at least one of a direction field, a default link mapping field, a reserved field, and a link mapping presence indicator field, and the link mapping presence indicator field may or may not be included in the TTLM control field. Each of the link mapping fields of TID n (where n=0, 1, ..., 7) may include 0 to 2 octets. The link mapping field of TID n may indicate a link on which a frame to which TID n belongs can be transmitted or received.

[0132] In the format of the element illustrated in FIG. 10, the direction field may include 2 bits, where a value of 0 in the direction field indicates uplink, a value of 1 indicates downlink, a value of 2 may indicate bidirectional links of both uplink and downlink, and a value of 3 may be reserved. The default link mapping field may include 1 bit, where a value of 1 in the default link mapping field may indicate default TTLM. The link mapping presence indicator field may include 0 or 8 bits, and may indicate whether the link mapping field of TID n is present (i.e., included) in the TTLM element. When the link mapping presence indicator field includes 0 bits (i.e., the link mapping presence indicator field is not included in the TTLM control field), it may mean that the link mapping field of TID n is not present in the TTLM element (i.e., the link mapping field of TID n is not included in the TTLM element). When the link mapping presence indicator field includes 8 bits, the bit at the nth position among the 8 bits can indicate whether the link mapping field of TID n exists within the TTLM element. For example, when the link mapping presence indicator field includes 8 bits and the bit at the nth position has a value of 1, it can mean that the link mapping field of TID n exists (i.e., is included) within the TTLM element. When the link mapping presence indicator field includes 8 bits and the bit at the nth position has a value of 0, it can mean that the link mapping field of TID n does not exist (i.e., is not included) within the TTLM element. Meanwhile, when the default link mapping field includes a value of 1, the link mapping presence indicator field can be reserved.

[0133] Figure 11 is a diagram illustrating a TTLM procedure related to the present disclosure. Figure 11 describes a procedure for changing the mapping relationship between a TID and a link through a TTLM procedure after a multi-link is established.

[0134] In Fig. 11, a TID-link mapping relationship is established between a non-AP MLD and an AP MLD, and for convenience of explanation, this mapping relationship is referred to as mapping A. For example, mapping A may include a mapping relationship according to a default mapping mode. Thereafter, the non-AP MLD transmits a frame for a request to the AP MLD to change (or update) the TID-link mapping relationship from mapping A to mapping B, which is different from mapping A. The request that the non-AP MLD transmits to the AP MLD may include the TTLM element described above, and the TTLM element may include a link mapping field for changing the link of a specific TID. For example, the TTLM element for changing to mapping B may include a field for changing the link for TID x (x=0, 1, ..., 7) from A to B, or may include a field for switching the link for TID y (y=0, 1, ..., 7) to a disabled state.

[0135] The AP MLD, upon receiving a request from a non-AP MLD, approves the change (or update) of the mapping relationship and sends a response to the non-AP MLD. The response may include a field indicating that the request from the non-AP MLD succeeded in changing (or updating) the mapping relationship. As the change (or update) of the mapping relationship is approved, the mapping relationship between the TID and the link is changed from Mapping A to Mapping B, and transmission and reception between the non-AP MLD and the AP MLD can be performed according to the changed Mapping B. Meanwhile, after a predetermined time period has elapsed after the changed (or updated) Mapping B is applied, the mapping relationship may be changed (or updated) from Mapping B to Mapping A. For example, if Mapping A is the default mapping mode or unavailability is approved between the AP MLD and the non-AP MLD, the changed mapping relationship, Mapping B, may be changed to the previous mapping relationship, Mapping A. Therefore, the non-AP MLD and AP MLD must re-perform the process of sending / receiving a frame for a request and receiving / sending a frame for a response in order to change (or update) the mapping relationship to mapping B.

[0136] Meanwhile, as devices evolve, devices (including non-AP STAs and APs) support a variety of different radio access technologies (RATs). Furthermore, as devices become increasingly smaller, antennas and transceivers for supporting multiple RATs are mounted adjacently within the device. In particular, when different RATs occupy adjacent frequency bands, the need for seamless coexistence (i.e., in-device coexistence, IDC) of different RATs within the device is increasing. 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).

[0137] Recently, various discussions have been held to improve or resolve 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), and 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. These methods correspond to methods that utilize available or unavailable time.

[0138] Alternatively, 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 the IDC target wireless access technology (i.e., a wireless access technology other than a wireless LAN system) during the transmission and reception of the control frame, the device can operate or not operate at a specific point in time after transmitting and receiving the data frame.

[0139] 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 issues, particularly those related to improving reliability. Therefore, from this perspective, a method for controlling IDC through specific yet simple procedures is needed.

[0140] These IDCs may be elements that must be periodically considered in the device's traffic. For example, if the impact of other wireless access technologies on wireless LAN communication is periodic, and if the IDC is controlled by changing the mapping relationship from Mapping A to Mapping B, as illustrated in Figure 11, the signaling overhead increases. This is because, since each time the mapping relationship is changed from Mapping A to Mapping B, frames for request and response must be transmitted and received, signaling must be performed every time an IDC occurs.

[0141] Therefore, the following proposes embodiments for efficiently controlling the mapping relationship between TID and link, and through these embodiments, smooth coexistence of wireless LAN and other wireless access technologies within a device can be supported.

[0142] FIG. 12 is a diagram illustrating a TTLM procedure according to one embodiment of the present disclosure. FIG. 12 illustrates exemplary TTLM-related operations between a non-AP MLD and an AP MLD at time intervals 1210, 1220, 1230, and 1240 over time.

[0143] In section 1210, the non-AP MLD (or STA MLD) and the AP MLD perform multi-link operation according to mapping A. Mapping A may mean a mapping relationship in which all three links for different frequency bands (e.g., link 1 at 2.4 GHz, link 2 at 5 GHz, and link 3 at 6 GHz) are enabled between the non-AP MLD and the AP MLD (1215). In section 1210, the non-AP MLD may detect that an IDC has occurred due to a different radio access technology affecting the WLAN for a specific link (e.g., link 2 at 5 GHz in FIG. 12), or may recognize (or predict) that an IDC will occur. According to the embodiment of FIG. 12, when the non-AP MLD recognizes that the WLAN is affected by the IDC in section 1220, the non-AP MLD may decide to change link 2 to an unavailable state. Therefore, the non-AP MLD can send a request to the AP MLD to change (or update) the mapping relationship to change (or update) mapping B with link 2 inactive for section 1220.

[0144] In one embodiment, the non-AP MLD may send a request to the AP MLD to periodically change the mapping relationship to mapping B for the IDC. The AP MLD may acknowledge the request from the non-AP MLD and send a response to the non-AP MLD to indicate that the result of the request for periodic change is successful.

[0145] The process of requesting that the Non-AP MLD periodically change (or update) the mapping relationship can be performed based on at least one of the traffic characteristics of a specific TS, the frequency characteristics of a specific link, the capability of the Non-AP MLD, the communication characteristics of another wireless access technology that is the target of the IDC, the duration of the IDC, the periodicity of the IDC, or the occurrence time of the IDC. Hereinafter, the process of periodically changing (or updating) the mapping relationship in this way can be referred to as periodic TTLM. For periodic TTLM, the Non-AP MLD can include a parameter or field for periodically changing the mapping relationship in the request it transmits to the AP MLD, and for example, at least one of a periodic TTLM identifier, the time to first TTLM switch, the expected duration, or the expected period can be included in the request frame for periodic TTLM. In one embodiment, if the first TTLM switch time, expected duration, and expected period are pre-negotiated between the non-AP MLD and the MLD, the request frame for periodic TTLM transmitted by the non-AP MLD may only include the periodic TTLM ID.

[0146] As the periodic TTLM requested by the non-AP MLD is approved, the non-AP MLD and the AP MLD may perform multi-link operation according to mapping B in section 1220. For example, mapping B may include a mapping relationship (1225) in which link 2 is unavailable between the non-AP MLD and the AP MLD, which may be due to a wireless access technology other than WLAN in the non-AP MLD (i.e., for IDC).

[0147] Meanwhile, the time period in which the changed (or updated) mapping relationship according to the periodic TTLM is applied can be determined based on the parameters or fields for the periodic TTLM described above. In the embodiment illustrated in FIG. 12, the time period 1220 in which the changed (or updated) mapping relationship (i.e., mapping B) is applied can be defined as the time starting from the time to the first TTLM switch and the expected duration. That is, the non-AP MLD and the AP MLD can apply the changed (or updated) mapping relationship according to the periodic TTLM during the time period determined based on the first TTLM switch time and the expected duration.

[0148] As described above in FIG. 11, when a mapping relationship is changed (or updated) according to the TTLM procedure, the mapping relationship before the TTLM procedure is applied again may be applied after a predetermined time interval. An example of this is illustrated in section 1230 of FIG. 12, where, in section 1230, mapping A (i.e., mapping relationship 1235 in which link 2 is activated), which is the mapping relationship before the mapping relationship is changed, is applied, allowing the non-AP MLD and the AP MLD to exchange traffic.

[0149] Meanwhile, in the case of IDC, since periodic occurrences can be detected or predicted in the non-AP MLD due to other wireless access technologies as explained above, the process of exchanging requests and responses for TTLM between the non-AP MLD and the AP MLD at each period can be disadvantageous in terms of signaling overhead. Therefore, according to one embodiment explained above, the non-AP MLD can send a request including an expected period to the AP MLD for periodic TTLM. That is, if it is predicted that Link 2 will become unavailable again due to other wireless access technologies after the expected period, the non-AP MLD can request periodic TTLM including information about the expected period. As the AP MLD approves this request, the non-AP MLD and the AP MLD can exchange traffic by applying mapping B (i.e., a mapping relationship in which Link 2 is in a disabled state, 1245) in the section 1240 after the expected period has elapsed. According to the periodic TTLM proposed in one embodiment, no separate signaling is required between the non-AP MLD and the AP MLD to apply the mapping B, which is a mapping relationship changed (or updated) in 1240, and the non-AP MLD and the AP MLD can communicate by periodically changing (or updating) the mapping A to the mapping B based on the request and response in the section 1210.

[0150] In one embodiment, if an IDC is detected or predicted between a non-AP MLD and an MLD and there are pre-negotiated parameters (e.g., first TTLM switch time, expected duration, expected period, etc.), the non-AP MLD may request periodic TTLM without transmitting redundant parameters by transmitting a periodic TTLM request frame that does not include those parameters but only includes the periodic TTLM ID.

[0151] Figure 13 illustrates the format of an exemplary element for a TTLM procedure according to one embodiment of the present disclosure. Figure 13 specifically describes the format and fields of the element for the periodic TTLM described above. Hereinafter, the element for periodic TTLM may be referred to as a periodic TTLM element.

[0152] According to one embodiment, a periodic TTLM element may include a 1-byte (or octet) element ID field, a 1-byte length field, a 1-byte element ID extension field, a 1 or 2-byte TTLM control field, a 1-byte periodic TTLM ID field, a 2-byte time to first TTLM switch field, a 3-byte expected duration field, a 3-byte expected period field, and a 0 to 2-byte TID n link mapping field (where n is an integer greater than or equal to 0) (Fig. 13(a)). The structure and format of the periodic TTLM element illustrated in Fig. 13(a) are merely exemplary, and the periodic TTLM element format may include more or fewer fields than illustrated, and the order or bit size of the fields included in the periodic TTLM element format may also be different.

[0153] In the illustrated embodiment, a 1 or 2 byte TTLM control field may include a 2-bit direction field, a 1-bit periodic TTLM ID present or presence field, a 1-bit first TTLM switch time present or presence field, a 1-bit expected duration present or presence field, a 2-bit expected period present or presence field, a 1-bit link mapping size field, a 1-bit reserved field, and a 0 or 8-bit link mapping presence bitmap field (Fig. 13(b)). The link mapping presence bitmap field may or may not be included within the TTLM control field. The structure and format of the TTLM control field illustrated in Fig. 13(b) are merely examples, and the TTLM control field may include more or fewer fields than illustrated, and the order or bit size of the fields included in the TTLM control field may also vary.

[0154] Below, each field included in the periodic TTLM element is described in detail. Fields included in the periodic TTLM element that overlap with those previously described may be omitted for detailed description.

[0155] According to one embodiment, the Element ID field may include a value of 255 for a periodic TTLM element. The Element ID Extension field may include a value to indicate a periodic TTLM element (for example, the value 111 may be applicable, although this value is merely an example and may include other values). For the TTLM Control field, the Periodic TTLM ID Present field may indicate whether a Periodic TTLM ID field is included (or present) within the Periodic TTLM element, the First TTLM Switch Time Present field may indicate whether a First TTLM Switch Time field is included (or present) within the Periodic TTLM element, the Expected Duration Present field may indicate whether an Expected Duration field is included (or present) within the Periodic TTLM element, and the Expected Period Present field may indicate whether an Expected Period field is included (or present) within the Periodic TTLM element. The Link Mapping Present Bitmap field may indicate whether the link mapping field of TID n is included (i.e., present) in the periodic TTLM element. If the Link Mapping Present Bitmap field contains a 0 bit (i.e., the Link Mapping Present Bitmap field is not included in the TTLM Control field), it may mean that the link mapping field of TID n is not included in the periodic TTLM element (i.e., the link mapping field of TID n is not present in the periodic TTLM element). If the Link Mapping Present Bitmap field contains 8 bits, the bit at the nth position among the 8 bits may indicate whether the link mapping field for TID n is present in the periodic TTLM element. For example, if the Link Mapping Present Bitmap field contains 8 bits and the bit at the nth position has a value of 1, it may mean that the link mapping field of TID n is included (i.e., present) in the TTLM element.If the Link Mapping Existence Indicator field contains 8 bits and the bit at the nth position has a value of 0, it may mean that the Link Mapping field of TID n is not included (i.e., does not exist) in the TTLM element.

[0156] Continuing with the periodic TTLM element, the periodic TTLM ID field may include a value for identifying a mapping relationship set up according to the periodic TTLM element. The first TTLM switch time field may indicate a target time at which the first switch (change or update) of the mapping takes place, and may indicate the target time in units of time units (TUs) or in absolute time units such as microseconds, milliseconds, or 32 microseconds. According to one embodiment, when the frame carrying the periodic TTLM element is a beacon frame, the starting point of the time at which the first switch takes place may be the target beacon transmission time (TBTT) corresponding to the beacon frame, and when the frame carrying the periodic TTLM element is not a beacon frame, the starting point of the time at which the first switch takes place may be the most recent TBTT preceding the transmission of the corresponding frame.

[0157] The Expected Duration field may include a value to indicate the time period (e.g., in TU units or absolute time units) over which the IDC actually occurs. The Expected Period field may include a value to indicate the time interval between each IDC (e.g., in TU units or absolute time units). The Link Mapping field of TID n may indicate a link over which a frame to which TID n belongs can be transmitted or received, and the example of FIG. 13 illustrates an exemplary embodiment that indicates that a frame to which TID 0 belongs can be transmitted or received over link 3.

[0158] The structure of the format illustrated in FIG. 13, the field names, the values ​​indicated by the fields, the number of fields to which meaningful values ​​are assigned, the order of the fields, the number of octets or bits, whether fields are included in the format, etc. are merely examples and may, of course, be changed differently from the illustrated and described embodiment.

[0159] FIG. 14 illustrates an exemplary format of a TTLM-related frame according to one embodiment of the present disclosure.

[0160] Fig. 14 illustrates an embodiment in which a frame for periodic TTLM is an EHT or protected EHT action frame. (a) of Fig. 14 illustrates the format of a frame for a periodic TTLM request (hereinafter, may be referred to as a periodic TTLM request frame), (b) illustrates the format of a frame for a periodic TTLM response (hereinafter, may be referred to as a periodic TTLM response frame), and (c) illustrates the format of a frame for periodic TTLM teardown (hereinafter, may be referred to as a periodic TTLM teardown frame).

[0161] A periodic TTLM request frame ((a) of FIG. 14) according to an embodiment may include a category field of order 1 (which may include, for example, a value of 37 to indicate a protected EHT frame), a protected EHT action field of order 2 (which may include, for example, a value of 13 to indicate a periodic TTLM request frame), a dialog token field of order 3, and a periodic TTLM element field of order 4, wherein the periodic TTLM element field of order 4 may be according to the embodiment described above in FIG. 13. According to an embodiment, the periodic TTLM element field may include at least one of a periodic TTLM ID, a first TTLM switch time, an expected duration, or an expected period, and the periodic TTLM element field may include only a periodic TTLM ID.

[0162] A periodic TTLM response frame ((b) of FIG. 14) according to an embodiment may include a category field of order 1 (which may include, for example, a value of 37 to indicate a protected EHT frame), a protected EHT action field of order 2 (which may include, for example, a value of 14 to indicate a periodic TTLM response frame), a dialog token field of order 3, a status code field of order 4, and a periodic TTLM element field of order 5. The status code field of order 4 may include a value to indicate whether a request of a non-AP MLD based on the periodic TTLM request frame has been accepted (i.e., SUCCESS), rejected (i.e., REJECT), or counted (i.e., COUNTERED). The periodic TTLM element field of Order 5 may follow the embodiment described above in FIG. 13, and when the status code field indicates COUNTERED, the periodic TTLM element field may contain parameters and values ​​counter-proposed by the AP MLD.

[0163] A periodic TTLM teardown frame according to an embodiment ((c) of FIG. 14) may include a category field of order 1 (which may include, for example, a value of 37 to indicate a protected EHT frame), a protected EHT action field of order 2 (which may include, for example, a value of 15 to indicate a periodic TTLM teardown frame), and a periodic TTLM element field of order 3, wherein the periodic TTLM element field of order 3 may have a structure in which some fields are omitted from the format of the embodiment described in FIG. 13. For example, the periodic TTLM element field included in the periodic TTLM teardown frame may include a periodic TTLM ID field, and may not include at least one of a first TTLM switch time field, an expected duration field, an expected period field, and a link mapping field of TID n.

[0164] The structure of the format, field names, values ​​indicated by fields, order of fields, inclusion of fields, etc., shown in Fig. 14 are merely examples and may be changed differently from the illustrated and described embodiment.

[0165] FIG. 15 illustrates an exemplary format of a TTLM-related frame according to one embodiment of the present disclosure.

[0166] FIG. 15 illustrates an embodiment in which a frame for periodic TTLM is a new type of action frame. For example, the frame for periodic TTLM illustrated in FIG. 15 may include an action frame for IDC, a UHR or protected UHR action frame, or other types of action frames. FIG. 15 (a) illustrates the format of a frame for a periodic TTLM request (or periodic TTLM request frame), (b) illustrates the format of a frame for a periodic TTLM response (or periodic TTLM response frame), and (c) illustrates the format of a frame for a periodic TTLM teardown (or periodic TTLM teardown frame).

[0167] A periodic TTLM request frame ((a) of FIG. 15) according to an embodiment may include a category field of order 1 (which may include, for example, a value of 38 to indicate an action frame for IDC or an action frame for UHR or protected UHR), a newly defined action field of order 2 (which may include, for example, a value of 0 to indicate a periodic TTLM request frame), a dialog token field of order 3, and a periodic TTLM element field of order 4, wherein the periodic TTLM element field of order 4 may be according to the embodiment described above in FIG. 13. According to an embodiment, the periodic TTLM element field may include at least one of a periodic TTLM ID, a first TTLM switch time, an expected duration, or an expected period, and the periodic TTLM element field may include only a periodic TTLM ID.

[0168] A periodic TTLM response frame ((b) of FIG. 15) according to an embodiment may include a category field of order 1 (which may include, for example, a value of 38 to indicate an action frame for IDC or an action frame for UHR or protected UHR), a newly defined action field of order 2 (which may include, for example, a value of 1 to indicate a periodic TTLM response frame), a dialog token field of order 3, a status code field of order 4, and a periodic TTLM element field of order 5. The status code field of order 4 may include a value to indicate whether a request of a non-AP MLD based on the periodic TTLM request frame has been accepted (i.e., SUCCESS), rejected (i.e., REJECT), or counted (i.e., COUNTERED). The periodic TTLM element field of Order 5 may follow the embodiment described above in FIG. 13, and when the status code field indicates COUNTERED, the periodic TTLM element field may contain parameters and values ​​counter-proposed by the AP MLD.

[0169] A periodic TTLM teardown frame according to an embodiment ((c) of FIG. 15) may include a category field of order 1 (which may include, for example, a value of 38 to indicate an action frame for IDC or an action frame for UHR or protected UHR), a newly defined action field of order 2 (which may include, for example, a value of 2 to indicate a periodic TTLM response frame), and a periodic TTLM element field of order 3, wherein the periodic TTLM element field of order 3 may have a structure in which some fields are omitted from the format of the embodiment described in FIG. 13. For example, the periodic TTLM element field included in the periodic TTLM teardown frame may include a periodic TTLM ID field, and may not include at least one of a first TTLM switch time field, an expected duration field, an expected period field, and a link mapping field of TID n.

[0170] The structure of the format, field names, values ​​indicated by fields, order of fields, inclusion of fields, etc., shown in Fig. 15 are merely examples and may be changed differently from the illustrated and described embodiment.

[0171] FIG. 16 is a diagram illustrating a TTLM procedure according to an embodiment of the present disclosure. FIG. 16 describes an embodiment in which a periodic TTLM procedure is performed during an association process.

[0172] In FIG. 16, the non-AP MLD and the AP MLD can transmit and receive an association request frame and an association response frame during the association process. According to one embodiment, the non-AP MLD can transmit the association request frame to the AP MLD by including the periodic TTLM element described above, and the AP MLD can transmit the association response frame to the non-AP MLD by including the periodic TTLM element described above.

[0173] Through this embodiment, the non-AP MLD and the AP MLD can perform communication by applying the mapping relationship for IDC even immediately after the link is set up through the association process. For example, after the association process is completed, the non-AP MLD and the AP MLD can exchange frames according to the mapping relationship set up considering IDC (hereinafter, “IDC-related mapping relationship”) based on the mapping relationship, the first TTLM switch time, the expected duration, and the expected cycle included in the periodic TTLM element. In addition, after a predetermined duration during which the IDC-related mapping relationship is applied, the default mapping relationship, Mapping A, can be applied between the non-AP MLD and the AP MLD. Since the non-AP MLD and the AP MLD have negotiated the periodic TTLM through the association process, the IDC-related mapping relationship can be reapplied according to the periodic TTLM element even if no separate signaling or frame exchange occurs between the non-AP MLD and the AP MLD after the predetermined cycle has elapsed.

[0174] FIG. 17 and FIG. 18 are diagrams illustrating a TTLM procedure and frame format according to an embodiment of the present disclosure. FIG. 17 and FIG. 18 illustrate operations after a connection is established by completing the association process between a non-AP MLD and an AP MLD, and in particular, the non-AP MLD and the AP MLD illustrate a situation in which periodic TTLM is applied after a connection is established.

[0175] According to the embodiment of FIG. 17, the non-AP MLD and the AP MLD can tear down the applied periodic TTLM and apply a new periodic TTLM. For example, the non-AP MLD can transmit a frame (i.e., a periodic TTLM teardown frame, 1710) to the AP MLD for tearing down the periodic TTLM that has been approved and is being applied through frame exchange with the AP MLD. The frame (1710) for tearing down the periodic TTLM can include the format and structure according to the embodiment described above, and the periodic TTLM ID field can include a value for indicating an identifier of the periodic TTLM to be teared down (e.g., ID=1 in FIG. 17). The AP MLD can transmit a frame (i.e., a periodic TTLM response frame, 1720) to the non-AP MLD for responding to the teardown request of the non-AP MLD of the periodic TTLM. A frame (1720) for a response to periodic TTLM may include a format and structure according to the embodiment described above, and may include a value of a status code or a field value of a periodic TTLM element to confirm that the currently applied periodic TTLM (e.g., periodic TTLM corresponding to ID=1) has been discontinued.

[0176] In the embodiment of FIG. 17, the non-AP MLD and the AP MLD can exchange frames to apply a new periodic TTLM. For example, the non-AP MLD can transmit a frame (i.e., a periodic TTLM request frame, 1730) to the AP MLD to request periodic TTLM to the AP MLD in order to negotiate and apply a new periodic TTLM (e.g., a periodic TTLM corresponding to ID=2) in addition to the discontinued periodic TTLM (i.e., a periodic TTLM corresponding to ID=1). The frame (1730) for requesting periodic TTLM can include a format and structure according to the embodiment described above, and the periodic TTLM ID field can include a value for indicating an identifier of the periodic TTLM to be newly requested (e.g., ID=2 in FIG. 17). The AP MLD may transmit a frame (i.e., a periodic TTLM response frame, 1740) for responding to a request from the non-AP MLD for periodic TTLM to the non-AP MLD. The frame (1720) for responding to periodic TTLM may include a format and structure according to the embodiment described above, and may include a value of a status code or a field value of a periodic TTLM element for confirming that a new periodic TTLM (e.g., a periodic TTLM corresponding to ID=2) has been approved in response to a request from the non-AP MLD.

[0177] According to the embodiment of FIG. 18, the non-AP MLD and the AP MLD can tear down the applied periodic TTLM and apply a new periodic TTLM. In the embodiment of FIG. 18, unlike the embodiment of FIG. 17, the teardown of the previous periodic TTLM and the request for a new periodic TTLM can be performed through a single frame exchange between the non-AP MLD and the AP MLD.

[0178] For example, a non-AP MLD may request both the termination of an already applied periodic TTLM (e.g., the periodic TTLM corresponding to ID=1) and a new periodic TTLM (e.g., the periodic TTLM corresponding to ID=2). In other words, the non-AP MLD may transmit to the AP MLD an element for the periodic TTLM termination and an element for the periodic TTLM request in one frame. In the illustrated embodiment, the frame transmitted by the non-AP MLD may include both a field and an element for the periodic TTLM termination (corresponding to ID=1) and a field and an element for the periodic TTLM request (corresponding to ID=2). According to one embodiment, among the fields included in the frame for the periodic TTLM termination and the frame for the periodic TTLM request, common fields (e.g., a category field, etc.) may not be included in the frame redundantly and at least some of them may be omitted.

[0179] The AP MLD can transmit a response for the termination of the currently applied periodic TTLM (e.g., the periodic TTLM corresponding to ID=1) and a response for a new periodic TTLM (e.g., the periodic TTLM corresponding to ID=2) together based on the frame received from the non-AP MLD. In other words, the AP MLD can transmit the response of the element for the periodic TTLM termination and the response of the element for the periodic TTLM request in one frame to the non-AP MLD. In the illustrated embodiment, the frame transmitted by the AP MLD can include both a field and an element (corresponding to ID=1) for the response to the periodic TTLM termination and a field and an element (corresponding to ID=2) for the response to the periodic TTLM request. According to one embodiment, among the fields for responding to periodic TTLM disconnection and the fields for responding to periodic TTLM request, common fields (e.g., category field, action field, dialog token field, etc.) may not be included in the frame redundantly and at least some of them may be omitted.

[0180] FIG. 19 is a diagram illustrating a TTLM procedure according to an embodiment of the present disclosure. FIG. 19 describes an embodiment in which multiple periodic TTLMs are applied between a non-AP MLD and an AP MLD.

[0181] In the embodiment of FIG. 19, the non-AP MLD and the AP MLD can transmit and receive frames for requesting periodic TTLM (e.g., periodic TTLM corresponding to ID=1) and for responding to the request of periodic TTLM during the association process. Through this process, after the AP MLD transmits a frame for responding to periodic TTLM to the non-AP MLD, the non-AP MLD and the AP MLD can periodically change the mapping relationship according to the periodic TTLM corresponding to ID=1. For example, the periodic TTLM of ID=1 can include a mapping relationship in which the link in the 2.4 GHz band is unavailable, and the non-AP MLD and the AP MLD can communicate by applying the mapping relationship according to the start time, duration, and period approved during the process of negotiating the periodic TTLM of ID=1.

[0182] Meanwhile, in the embodiment of FIG. 19, the non-AP MLD and the AP MLD can transmit and receive frames for requesting another periodic TTLM (e.g., periodic TTLM corresponding to ID=2) after the association process and transmit and receive frames for responding to the request of the periodic TTLM. Through this process, the AP MLD and the non-AP MLD can change or apply a mapping relationship to another period according to the periodic TTLM corresponding to ID=2. For example, the periodic TTLM of ID=2 can include a mapping relationship in which the link in the 6 GHz band is unavailable, and the non-AP MLD and the AP MLD can apply the mapping relationship according to the start time, duration, and period approved in the process of negotiating the periodic TTLM of ID=2.

[0183] That is, the non-AP MLD and the AP MLD can communicate by negotiating and applying multiple periodic TTLMs. In the embodiment illustrated in FIG. 19, the period of the periodic TTLM corresponding to ID=1 is longer than the period of the periodic TTLM corresponding to ID=2, and the duration of the periodic TTLM corresponding to ID=1 is longer than the duration of the periodic TTLM corresponding to ID=2. Accordingly, there may exist a section where both the periodic TTLM of ID=1 and the periodic TTLM of ID=2 are applied (i.e., a section where a mapping relationship in which both the 2.4 GHz link and the 6 GHz link are inactive is applied), a section where only the periodic TTLM of ID=1 is applied (i.e., a section where a mapping relationship in which only the 2.4 GHz link is inactive is applied), and a section where only the periodic TTLM of ID=2 is applied (i.e., a section where a mapping relationship in which only the 6 GHz link is inactive is applied).

[0184] FIG. 20 is a diagram illustrating a TTLM procedure according to one embodiment of the present disclosure.

[0185] Figure 20 illustrates an embodiment in which the AP MLD is a mobile AP. The mobile AP may broadcast (or unicast) the periodic TTLM element according to the embodiments described above by including it in a beacon frame or a frame response frame. This is because mobile APs may not be able to maintain an available period compared to general APs due to reasons such as power consumption, heat generation, battery, or mobility. Accordingly, the AP according to one embodiment may transmit the periodic TTLM element described above to a non-AP STA by including it in a beacon frame or a probe response frame.

[0186] FIG. 21 illustrates a flowchart of TTLM operation of a device according to an embodiment of the present disclosure. FIG. 21 illustrates the operation of a non-AP STA (or non-AP MLD) proposed in the present disclosure, and some or all of the various embodiments related to the non-AP STA (or non-AP MLD) described above may be applied identically or similarly to FIG. 21.

[0187] According to an embodiment of FIG. 21, a non-AP STA transmits a frame for a periodic TTLM request (or, a periodic TTLM request frame) to an AP (2110). The periodic TTLM request frame may include at least one field for indicating a first TTLM switch time, expected duration, expected cycle, etc. for periodically applying TTLM, and may also include a field for indicating a mapping relationship between an identifier of TTLM to be periodically applied and a TID and a link. According to one embodiment, the periodic TTLM request frame may only include a periodic TTLM ID field corresponding to a pre-agreed first TTLM switch time, expected duration, and expected cycle.

[0188] A non-AP STA receives a frame for a periodic TTLM response (or, a periodic TTLM response frame) from the AP (2120). The periodic TTLM response frame may include the AP's response to the non-AP STA's request, and may include information on whether the periodic TTLM request was accepted, rejected, or countered.

[0189] A non-AP STA can periodically switch the mapping between TID and link based on the AP's response (2130). In other words, a non-AP STA can periodically apply a TID-link mapping relationship approved or set up through negotiation with the AP. Periodically applying a TID-link mapping relationship may mean changing (or updating) the TID-link mapping relationship at a predetermined cycle even without separate signaling. Through this, the non-AP STA and the AP can operate while considering the IDC between the non-AP STA's wireless LAN and other wireless access technologies.

[0190] Meanwhile, in the above, one embodiment of the operation of a non-AP STA (or non-AP MLD) and an AP (or AP MLD) has been described based on the flowchart illustrated in FIG. 21, but it is obvious that the operation of a non-AP STA (or non-AP MLD) and an AP (or AP MLD) may vary depending on other embodiments described above.

[0191] Fig. 22 illustrates a flowchart of the TTLM operation of a device according to an embodiment of the present disclosure. Fig. 22 illustrates the operation of a non-AP STA (or non-AP MLD) proposed in the present disclosure, and some or all of the various embodiments related to the non-AP STA (or non-AP MLD) described above may be applied identically or similarly to Fig. 22. In Fig. 22, a detailed description of the operations overlapping with those of Fig. 21 is omitted.

[0192] According to the embodiment of FIG. 22, a non-AP STA may request a periodic TTLM from an AP (2210), receive a response to the periodic TTLM from the AP (2220), and operate by periodically switching the TID-link mapping (2230). Meanwhile, in the embodiment of FIG. 22, the non-AP STA receives a frame for disabling the periodic TTLM (or, a periodic TTLM disabling frame) from the AP (2240). Through the periodic TTLM disabling frame, the non-AP STA may disabling an approved or set-up periodic TTLM (2250), and disabling the periodic TTLM may mean stopping the change (or update) of the mapping relationship according to the periodic TTLM and no longer applying it. For this purpose, the periodic TTLM disabling frame may include an identifier for identifying the periodic TTLM to be disabling. If multiple periodic TTLMs are approved and applied between a Non-AP STA and an AP, it is possible that only a portion of one or more of the multiple periodic TTLMs may be dismantled.

[0193] According to one embodiment, a non-AP STA may also release the periodic TTLM by transmitting a periodic TTLM release frame to the AP. That is, although FIG. 22 illustrates an embodiment in which an AP sends a periodic TTLM release frame to a non-AP STA, it is of course possible for a non-AP to send a periodic TTLM release frame to the AP. Since the release of the periodic TTLM means that the mapping relationship between the non-AP STA and the AP changes, the periodic TTLM release frame may be transmitted by any device among the non-AP STA and the AP.

[0194] Meanwhile, in the above, one embodiment of the operation of a non-AP STA (or non-AP MLD) and an AP (or AP MLD) has been described based on the flowchart illustrated in FIG. 22, but it is obvious that the operation of a non-AP STA (or non-AP MLD) and an AP (or AP MLD) may vary depending on other embodiments described above.

[0195] FIG. 23 illustrates a flowchart of the TTLM operation of a device according to one embodiment of the present disclosure. FIG. 23 illustrates the operation of the AP (or AP MLD) proposed in the present disclosure, and some or all of the various embodiments related to the AP (or non-AP MLD) described above may be applied identically or similarly to FIG. 23.

[0196] According to an embodiment of FIG. 23, an AP receives a frame for a periodic TTLM request (or, a periodic TTLM request frame) from a non-AP STA (2310). The periodic TTLM request frame may include at least one field for indicating a first TTLM switch time, expected duration, expected cycle, etc. for periodically applying TTLM, and may also include a field for indicating a mapping relationship between an identifier of TTLM to be periodically applied and a TID and a link. According to one embodiment, the periodic TTLM request frame may only include a periodic TTLM ID field corresponding to a pre-agreed first TTLM switch time, expected duration, and expected cycle.

[0197] The AP transmits a frame for a periodic TTLM response (or, a periodic TTLM response frame) to a non-AP STA (2220). The periodic TTLM response frame may include the AP's response to the non-AP STA's request, and may include information on whether the periodic TTLM request was accepted, rejected, or countered.

[0198] The AP can periodically switch the mapping between TIDs and links based on responses transmitted to non-AP STAs (2330). In other words, the AP can periodically apply the TID-link mapping relationship approved or set up through negotiation with the non-AP STA. Periodically applying the TID-link mapping relationship may mean changing (or updating) the TID-link mapping relationship at a predetermined cycle even without separate signaling. Through this, the AP can operate with the non-AP STA by considering the IDC between the non-AP STA's wireless LAN and other wireless access technologies.

[0199] Meanwhile, in the above, one embodiment of the operation of the AP (or AP MLD) and the non-AP STA (or non-AP MLD) has been described based on the flowchart illustrated in FIG. 23, but it is obvious that the operation of the AP (or AP MLD) and the non-AP STA (or non-AP MLD) may vary depending on other embodiments described above.

[0200] Fig. 24 illustrates a flowchart of the TTLM operation of a device according to an embodiment of the present disclosure. Fig. 24 illustrates the operation of the AP (or AP MLD) proposed in the present disclosure, and some or all of the various embodiments related to the AP (or non-AP MLD) described above may be applied identically or similarly to Fig. 24. In Fig. 24, a detailed description of the operations overlapping with those of Fig. 23 is omitted.

[0201] According to the embodiment of FIG. 24, the AP may receive a request for periodic TTLM from a non-AP STA (2410), transmit a response to the periodic TTLM to the non-AP STA (2420), and operate by periodically switching the TID-link mapping (2430). Meanwhile, in the embodiment of FIG. 24, the AP transmits a frame for periodic TTLM dismantling (or, periodic TTLM dismantling frame) to the non-AP STA (2440). Through the periodic TTLM dismantling frame, the AP may dismantle the periodic TTLM approved or set up for the non-AP STA (2450), and dismantling the periodic TTLM may mean stopping and no longer applying the change (or update) of the mapping relationship according to the periodic TTLM. For this purpose, the periodic TTLM dismantling frame may include an identifier for identifying the periodic TTLM to be dismantled. If multiple periodic TTLMs are approved and applied between an AP and a Non-AP STA, it is of course possible that only a portion of one or more of the multiple periodic TTLMs may be dismantled.

[0202] According to one embodiment, an AP may tear down the periodic TTLM by receiving a periodic TTLM teardown frame from a non-AP STA. That is, although FIG. 24 illustrates an embodiment in which an AP transmits a periodic TTLM teardown frame to a non-AP STA, it is of course possible for a non-AP STA to transmit a periodic TTLM teardown frame to the AP and for the AP to receive a periodic TTLM teardown frame from a non-AP STA. Since tearing down the periodic TTLM means that the mapping relationship between a non-AP STA and an AP changes, a periodic TTLM teardown frame may be transmitted by any device among a non-AP STA and an AP.

[0203] Meanwhile, in the above, one embodiment of the operation of the AP (or AP MLD) and the non-AP STA (or non-AP MLD) has been described based on the flowchart illustrated in FIG. 24, but it is obvious that the operation of the AP (or AP MLD) and the non-AP STA (or non-AP MLD) may vary depending on other embodiments described above.

[0204] 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.

[0205] 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 transmitting a first frame including a first periodic TTLM element for requesting periodic TTLM (TID (traffic identifier) ​​to link mapping) related to multi-link operation (MLO) to an AP (access point), wherein a TTLM control field of the first periodic TTLM element includes a field indicating whether the first periodic TTLM element includes a parameter for periodic TTLM; Receiving a second frame from the AP, the second frame including a second periodic TTLM element for responding to the request for the periodic TTLM; and A method comprising the step of periodically changing the TTLM for the MLO based on the second frame.

2. In paragraph 1, The first periodic TTLM element further includes at least one of a periodic TTLM identifier field, a first TTLM switch time field, an expected duration field, an expected period field, or a link mapping field of a TID, The second frame further includes a status code field, A method according to claim 1, wherein the second periodic TTLM element comprises at least one of a TTLM control field, a periodic TTLM identifier field, a first TTLM switch time field, an expected duration field, an expected period field, or a link mapping field of a TID.

3. In paragraph 2, The above first TTLM time field contains a value for indicating the starting point of the periodically changing step, The above expected duration field includes a value for indicating the time period to which the above changed TTLM applies, A method wherein the above expected cycle field includes a value for indicating a time interval of a cycle to which the above changing step is applied.

4. In paragraph 1, The above method, Further comprising a step of transmitting a third frame for teardown of the periodic TTLM to the AP, A method wherein the third frame includes a field for indicating an identifier of the periodic TTLM to be disbanded.

5. In paragraph 1, The step of periodically changing the above further includes the step of applying a specific TTLM identified based on the first frame, A method wherein the above specific TTLM is a TTLM for supporting in-device coexistence (IDC) with a radio access technology other than the WLAN for the STA.

6. In a method performed by an AP (access point) of a wireless local area network (WLAN) system, A step of receiving, from a station (STA), a first frame including a first periodic TTLM element for requesting periodic TTLM (TID (traffic identifier) ​​to link mapping) related to multi-link operation (MLO), wherein a TTLM control field of the first periodic TTLM element includes a field indicating whether the first periodic TTLM element includes a parameter for periodic TTLM; transmitting, to the STA, a second frame including a second periodic TTLM element for responding to the request for the periodic TTLM; and A method comprising the step of periodically changing the TTLM for the MLO based on the second frame.

7. In paragraph 6, The first periodic TTLM element further includes at least one of a periodic TTLM identifier field, a first TTLM switch time field, an expected duration field, an expected period field, or a link mapping field of a TID, The second frame further includes a status code field, A method according to claim 1, wherein the second periodic TTLM element comprises at least one of a TTLM control field, a periodic TTLM identifier field, a first TTLM switch time field, an expected duration field, an expected period field, or a link mapping field of a TID.

8. In paragraph 7, The above first TTLM time field contains a value for indicating the starting point of the periodically changing step, The above expected duration field includes a value for indicating the time period to which the above changed TTLM applies, A method wherein the above expected cycle field includes a value for indicating a time interval of a cycle to which the above changing step is applied.

9. 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: A first frame including a first periodic TTLM element for requesting periodic TTLM (TID (traffic identifier) ​​to link mapping) related to multi-link operation (MLO) is transmitted to an access point (AP), wherein a TTLM control field of the first periodic TTLM element includes a field indicating whether the first periodic TTLM element includes a parameter for periodic TTLM, Receive a second frame from the AP, the second frame including a second periodic TTLM element for responding to the request for the periodic TTLM; STA to change TTLM periodically for the MLO based on the second frame.

10. In paragraph 9, The first periodic TTLM element further includes at least one of a periodic TTLM identifier field, a first TTLM switch time field, an expected duration field, an expected period field, or a link mapping field of a TID, The second frame further includes a status code field, STA, wherein the second periodic TTLM element includes at least one of a TTLM control field, a periodic TTLM identifier field, a first TTLM switch time field, an expected duration field, an expected period field, or a link mapping field of a TID.

11. In paragraph 10, The above first TTLM time field contains a value for indicating the starting point of the periodically changing step, The above expected duration field includes a value for indicating the time period to which the above changed TTLM applies, STA, wherein the above expected cycle field includes a value for indicating the time interval of the cycle to which the above changing step is applied.

12. In paragraph 9, The above commands are: To transmit a third frame for teardown of the above periodic TTLM to the AP, STA, wherein the third frame includes a field for indicating an identifier of the periodic TTLM to be disbanded.

13. 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: Receiving a first frame from a STA (station) including a first periodic TTLM element for requesting periodic TTLM (TID (traffic identifier) ​​to link mapping) related to multi-link operation (MLO), wherein a TTLM control field of the first periodic TTLM element includes a field indicating whether the first periodic TTLM element includes a parameter for periodic TTLM, Transmitting a second frame to the STA, the second frame including a second periodic TTLM element for responding to the request for the periodic TTLM, An AP that periodically changes the TTLM for the MLO based on the second frame.

14. In paragraph 13, The first periodic TTLM element further includes at least one of a periodic TTLM identifier field, a first TTLM switch time field, an expected duration field, an expected period field, or a link mapping field of a TID, The second frame further includes a status code field, An AP, wherein the second periodic TTLM element includes at least one of a TTLM control field, a periodic TTLM identifier field, a first TTLM switch time field, an expected duration field, an expected period field, or a link mapping field of a TID.

15. In paragraph 14, The above first TTLM time field contains a value for indicating the starting point of the periodically changing step, The above expected duration field includes a value for indicating the time period to which the above changed TTLM applies, The above expected cycle field contains a value for indicating the time interval of the cycle to which the above changing step is applied, AP.

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