Method and device for setting timer by which serving AP MLD transmits buffered DL data to non-AP sta in wireless LAN system

Abstract

A method and a device for setting a timer by which a serving AP MLD transmits buffered DL data to a non-AP STA in a wireless LAN system are presented. Specifically, the non-AP STA belonging to a non-AP MLD transmits a roaming request frame to a first AP belonging to a first AP MLD. After context is transferred from the first AP MLD to a second AP MLD, the non-AP STA receives a roaming response frame from the first AP. The non-AP STA receives buffered DL data from the first AP MLD. A roaming response frame includes information about a timer of the buffered DL data.

Description

Method and device for setting a timer for transmitting waiting DL data from a SERVING AP MLD to a NON-AP STA in a wireless LAN system

[0001] This specification relates to a technique for setting a timer for transmitting DL data waiting for a Serving AP MLD to a non-AP STA in a wireless LAN system, and more specifically, to a method for extending a timer for processing remaining data that has not been transmitted to the non-AP STA after the timer expires, or a method and device for directly transmitting data from the Serving AP MLD to a Target AP MLD.

[0002] Next-generation Wi-Fi (e.g., IEEE 802.11be and / or later) aims to support ultra-high reliability when transmitting signals to STAs. To achieve this, various technologies are being considered to support high throughput, low latency, and extended range. For example, seamless roaming can be achieved by transitioning from the current AP MLD to the target AP MLD.

[0003] The present specification proposes a method and device for setting a timer for transmitting waiting DL data to a non-AP STA by a Serving AP MLD in a wireless LAN system.

[0004] An example of this specification proposes a method for a Serving AP MLD to set a timer for forwarding pending DL data to a non-AP STA.

[0005] The present embodiment can be performed in a network environment that supports a next-generation wireless LAN system (UHR (Ultra High Reliability) wireless LAN system or next wi-fi). The next-generation wireless LAN system is a wireless LAN system that improves the 802.11be system and can satisfy backward compatibility with the 802.11be system.

[0006] The present embodiment proposes a method for setting a data timer used to transmit data in a buffer of a Serving AP MLD to a non-AP STA belonging to a non-AP MLD when MLD roaming is performed. Specifically, the present embodiment proposes a method for transmitting data in a buffer of the Serving AP MLD to the non-AP STA before the data timer expires, and for extending the data timer for processing remaining data that has not been transmitted to the non-AP STA after the data timer expires, or a method for directly transmitting data from the Serving AP MLD to the Target AP MLD.

[0007] A non-AP STA (station) belonging to the above non-AP MLD transmits a roaming request frame to the first AP belonging to the first AP MLD.

[0008] After the context is transferred from the first AP MLD to the second AP MLD, the non-AP STA receives a roaming response frame from the first AP.

[0009] The above non-AP STA receives queued DL (downlink) data from the first AP MLD.

[0010] The above roaming response frame includes information about the timer of the waiting DL data.

[0011] The above-mentioned waiting DL data is data that can be transmitted before the timer of the above-mentioned waiting DL data expires among the data in the buffer of the first AP MLD for the above-mentioned non-AP STA.

[0012] That is, the present embodiment proposes a method for the non-AP STA to receive data in the buffer of the first AP MLD before the timer of the waiting DL data set based on the roaming response frame expires. In addition, the present embodiment proposes a method for extending the timer of the waiting DL data to transmit the remaining data or directly transmitting the data from the first AP MLD to the second AP MLD when all the data in the buffer of the first AP MLD cannot be transmitted before the timer of the waiting DL data expires.

[0013] According to the embodiment proposed in this specification, the non-AP MLD can determine how long it will be connected to the Serving AP MLD, receive data in its buffer, and determine when it can transition to the Target AP MLD. Furthermore, data loss that may occur when the non-AP MLD transitions to the Target AP MLD can be minimized. This allows for efficient MLD roaming.

[0014] Figure 1 illustrates an example of a transmitting device and / or a receiving device of the present specification.

[0015] Figure 2 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

[0016] Figure 3 is a diagram illustrating a general link setup process.

[0017] Figure 4 illustrates one embodiment of a multi-link (ML).

[0018] FIG. 5 illustrates a PPDU (physical protocol data unit or physical layer (PHY) protocol data unit) transmitted / received by an STA of this specification.

[0019] Figure 6 is a diagram showing the layout of resource units (RUs) used for 20MHz PPDU.

[0020] Figure 7 is a diagram showing the layout of resource units (RUs) used for 40MHz PPDU.

[0021] Figure 8 is a diagram showing the layout of resource units (RUs) used for 80MHz PPDU.

[0022] Figure 9 shows the operation according to UL-MU.

[0023] Figure 10 shows an example of channels used / supported / defined within the 2.4 GHz band.

[0024] Figure 11 illustrates an example of channels used / supported / defined within the 5 GHz band.

[0025] Figure 12 illustrates an example of channels used / supported / defined within the 6 GHz band.

[0026] Figure 13 shows an example of a header of a MAC frame.

[0027] FIG. 14 illustrates a modified example of a transmitting device and / or a receiving device of the present specification.

[0028] Figure 15 illustrates an over-the-air (OTA) FT protocol in a Robust Security Network (RSN).

[0029] Figure 16 illustrates the high-level architecture for AP MLD.

[0030] Figure 17 illustrates an example of a high-level architecture for UHR AP MLD.

[0031] Figure 18 illustrates another example of a high-level architecture for UHR AP MLD.

[0032] Figure 19 illustrates another example of the High-level Architecture for UHR AP MLD.

[0033] Figure 20 illustrates an example of a high-level architecture in the case where there are only entities that are not MLD-based.

[0034] Figure 21 illustrates another example of a High-level Architecture in the case of entities that are not MLD-based.

[0035] Figure 22 illustrates an example of a Roaming Architecture in an AP MLD area.

[0036] Figure 23 illustrates an example of a data transfer procedure.

[0037] Figure 24 illustrates an example of transmitting DL data accumulated in the queue of the Serving AP MLD.

[0038] Figure 25 illustrates an example of notifying the completion of transmission of DL data accumulated in the queue of the Serving AP MLD using the DL Timer.

[0039] Figure 26 illustrates an example of transmitting data using Data Transfer when Queued DL Data is not fully transmitted.

[0040] Figure 27 illustrates an example of extending the Queued DL Data Timer when the Queued DL Data is not fully transmitted.

[0041] Figure 28 is a flowchart illustrating the operation of a transmitting device according to the present embodiment.

[0042] Fig. 29 is a flowchart illustrating the operation of a receiving device according to the present embodiment.

[0043] FIG. 30 is a flowchart illustrating a procedure for setting a timer for transmitting DL data that is waiting for Serving AP MLD in MLD roaming according to the present embodiment.

[0044] FIG. 31 is a flowchart illustrating a procedure for a non-AP MLD to receive DL data waiting based on a timer in MLD roaming according to the present embodiment.

[0045] In this specification, “A or B” can mean “only A,” “only B,” or “both A and B.” In other words, “A or B” in this specification can be interpreted as “A and / or B.” For example, “A, B or C” in this specification can mean “only A,” “only B,” “only C,” or “any combination of A, B, and C.”

[0046] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "and / or B." Accordingly, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0047] In this specification, “at least one of A and B” can mean “only A,” “only B,” or “both A and B.” Additionally, in this specification, the expressions “at least one of A or B” or “at least one of A and / or B” can be interpreted identically to “at least one of A and B.”

[0048] In addition, parentheses used in this specification may mean “for example.” Specifically, when “control information (UHR-Signal field)” is indicated, the “UHR-Signal field” may be suggested as an example of “control information.” In other words, the “control information” in this specification is not limited to the “UHR-Signal field,” and the “UHR-Signal field” may be suggested as an example of “control information.” In addition, even when indicated as “control information (UHR-Signal field),” the “UHR-Signal field” may be suggested as an example of “control information.”

[0049] Additionally, as used herein, “a / an” can mean “at least one” or “one or more.” Additionally, terms ending in “(s)” can mean “at least one” or “one or more.”

[0050] Additionally, the expressions “based on” or “on the basis of” or “according to” used herein mean “based at least in part on” and not “based solely on.”

[0051] Technical features individually described in a single drawing in this specification may be implemented individually or simultaneously.

[0052] The following examples of this specification can be applied to various wireless communication systems. For example, the following examples of this specification can be applied to wireless local area network (WLAN) systems. For example, the following examples of this specification can be applied to the IEEE 802.11a / g / n / ac / ax / be / bn standards. In addition, the examples of this specification can be applied to the Ultra High Reliability (UHR) standard or the next-generation wireless LAN standard that enhances IEEE 802.11bn. In addition, the examples of this specification can be applied to mobile communication systems. For example, the following examples of this specification can be applied to mobile communication systems based on the Long Term Evolution (LTE) and its evolution based on the 3rd Generation Partnership Project (3GPP) standard.

[0053] In order to explain the technical features of this specification, the technical features to which this specification can be applied are described below.

[0054] Figure 1 illustrates an example of a transmitting device and / or a receiving device of the present specification.

[0055] An example of FIG. 1 can perform various technical features described below. FIG. 1 relates to at least one STA (station). For example, the STA (110, 120) of the present specification may also be referred to by various names such as a mobile terminal, a wireless device, a Wireless Transmit / Receive Unit (WTRU), a User Equipment (UE), a Mobile Station (MS), a Mobile Subscriber Unit, or simply a user. The STA (110, 120) of the present specification may also be referred to by various names such as a network, a base station, a Node-B, an access point (AP), a repeater, a router, a relay, etc. The STA (110, 120) of the present specification may also be referred to by various names such as a receiving apparatus, a transmitting apparatus, a receiving STA, a transmitting STA, a receiving device, a transmitting device, etc.

[0056] For example, STA (110, 120) may perform the role of an AP (access point) or a non-AP role. That is, STA (110, 120) of the present specification may perform the functions of an AP and / or a non-AP. In the present specification, AP may also be indicated as an AP STA.

[0057] The STA (110, 120) of this specification can support various communication standards other than the IEEE 802.11 standard. For example, it can support communication standards according to the 3GPP standard (e.g., LTE, LTE-A, 5G NR standard). In addition, the STA of this specification can be implemented in various devices such as mobile phones, vehicles, and personal computers. In addition, the STA of this specification can support communication for various communication services such as voice calls, video calls, data communications, and autonomous driving (Self-Driving, Autonomous-Driving).

[0058] In this specification, STA (110, 120) may include a medium access control (MAC) and a physical layer interface for a wireless medium that follow the provisions of the IEEE 802.11 standard.

[0059] Based on the sub-drawing (a) of Fig. 1, STA (110, 120) is described as follows.

[0060] The first STA (110) may include a processor (111), a memory (112), and a transceiver (113). The illustrated processor, memory, and transceiver may each be implemented as separate chips, or at least two blocks / functions may be implemented through a single chip.

[0061] The transceiver (113) of the first STA performs signal transmission and reception operations. Specifically, it can transmit and receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0062] For example, the first STA (110) can perform the intended operation of the AP. For example, the processor (111) of the AP can receive a signal through the transceiver (113), process the received signal, generate a transmission signal, and perform control for signal transmission. The memory (112) of the AP can store a signal received through the transceiver (113) (i.e., a reception signal) and store a signal to be transmitted through the transceiver (i.e., a transmission signal).

[0063] For example, the second STA (120) can perform the intended operation of a non-AP STA. For example, the transceiver (123) of the non-AP performs signal transmission and reception operations. Specifically, it can transmit and receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0064] For example, the processor (121) of the Non-AP STA can receive a signal through the transceiver (123), process the received signal, generate a transmission signal, and perform control for signal transmission. The memory (122) of the Non-AP STA can store a signal received through the transceiver (123) (i.e., a reception signal) and store a signal to be transmitted through the transceiver (i.e., a transmission signal).

[0065] For example, in the specification below, the operation of a device indicated as AP may be performed in the first STA (110) or the second STA (120). For example, if the first STA (110) is an AP, the operation of the device indicated as AP may be controlled by the processor (111) of the first STA (110), and a related signal may be transmitted or received through a transceiver (113) controlled by the processor (111) of the first STA (110). In addition, control information related to the operation of the AP or a transmission / reception signal of the AP may be stored in the memory (112) of the first STA (110). In addition, when the second STA (110) is an AP, the operation of the device indicated as an AP is controlled by the processor (121) of the second STA (120), and a related signal can be transmitted or received through a transceiver (123) controlled by the processor (121) of the second STA (120). In addition, control information related to the operation of the AP or the transmission / reception signal of the AP can be stored in the memory (122) of the second STA (110).

[0066] For example, in the specification below, the operation of a device indicated as a non-AP (or User-STA) may be performed in the STA (110) or the second STA (120). For example, if the second STA (120) is a non-AP, the operation of the device indicated as a non-AP may be controlled by the processor (121) of the second STA (120), and a related signal may be transmitted or received through a transceiver (123) controlled by the processor (121) of the second STA (120). In addition, control information related to the operation of the non-AP or the transmission / reception signal of the AP may be stored in the memory (122) of the second STA (120). For example, if the first STA (110) is a non-AP, the operation of a device indicated as a non-AP is controlled by the processor (111) of the first STA (110), and a related signal may be transmitted or received through a transceiver (113) controlled by the processor (111) of the first STA (120). In addition, control information related to the operation of the non-AP or the transmission / reception signal of the AP may be stored in the memory (112) of the first STA (110).

[0067] In the following specification, devices called (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) Terminal, (transmitting / receiving) device, (transmitting / receiving) apparatus, network, etc. may refer to the STA (110, 120) of FIG. 1. For example, devices indicated as (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) Terminal, (transmitting / receiving) device, (transmitting / receiving) apparatus, network, etc. without specific drawing symbols may also refer to the STA (110, 120) of FIG. 1. For example, in the example below, the operation of various STAs transmitting and receiving signals (e.g., PPDUs) may be performed by the transceivers (113, 123) of FIG. 1. In addition, in the example below, the operation of various STAs generating transmission and reception signals or performing data processing or calculations in advance for transmission and reception signals may be performed by the processors (111, 121) of FIG. 1.For example, an example of an operation that generates a transmission / reception signal or performs data processing or operation in advance for a transmission / reception signal may include 1) an operation of determining / obtaining / configuring / computing / decoding / encoding bit information of a subfield (SIG, STF, LTF, Data) field included in a PPDU, 2) an operation of determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) used for a subfield (SIG, STF, LTF, Data) field included in a PPDU, 3) an operation of determining / configuring / obtaining a specific sequence (e.g., a pilot sequence, an STF / LTF sequence, an extra sequence applied to SIG) used for a subfield (SIG, STF, LTF, Data) field included in a PPDU, 4) a power control operation and / or a power saving operation applied to an STA, 5) an operation related to determining / obtaining / configuring / computing / decoding / encoding an ACK signal, etc. Additionally, in the examples below, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs for determining / acquiring / configuring / computing / decoding / encoding transmission / reception signals can be stored in the memory (112, 122) of FIG. 1.

[0068] The device / STA of the sub-drawing (a) of the above-described FIG. 1 can be modified as in the sub-drawing (b) of FIG. 1. Hereinafter, the STA (110, 120) of the present specification will be described based on the sub-drawing (b) of FIG. 1.

[0069] For example, the transceiver (113, 123) illustrated in sub-drawing (b) of FIG. 1 may perform the same function as the transceiver illustrated in sub-drawing (a) of FIG. 1 described above. For example, the processing chip (114, 124) illustrated in sub-drawing (b) of FIG. 1 may include a processor (111, 121) and a memory (112, 122). The processor (111, 121) and the memory (112, 122) illustrated in sub-drawing (b) of FIG. 1 may perform the same function as the processor (111, 121) and the memory (112, 122) illustrated in sub-drawing (a) of FIG. 1 described above.

[0070] The mobile terminal, wireless device, Wireless Transmit / Receive Unit (WTRU), User Equipment (UE), Mobile Station (MS), Mobile Subscriber Unit, user, user STA, network, Base Station, Node-B, Access Point (AP), repeater, router, relay, receiving device, transmitting device, receiving STA, transmitting STA, receiving Device, transmitting Device, receiving Apparatus, and / or transmitting Apparatus described below may refer to the STA (110, 120) illustrated in the sub-drawings (a) / (b) of FIG. 1, or may refer to the processing chip (114, 124) illustrated in the sub-drawing (b) of FIG. 1. That is, the technical feature of the present specification may be performed in the STA (110, 120) illustrated in the sub-drawings (a) / (b) of FIG. 1, or may be performed only in the processing chip (114, 124) illustrated in the sub-drawings (b) of FIG. 1. For example, the technical feature that the transmitting STA transmits a control signal may be understood as a technical feature that the control signal generated in the processor (111, 121) illustrated in the sub-drawings (a) / (b) of FIG. 1 is transmitted through the transceiver (113, 123) illustrated in the sub-drawings (a) / (b) of FIG. 1. Alternatively, the technical feature that the transmitting STA transmits a control signal may be understood as a technical feature that the control signal to be transmitted to the transceiver (113, 123) is generated in the processing chip (114, 124) illustrated in the sub-drawings (b) of FIG. 1.

[0071] For example, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal being received by a transceiver (113, 123) illustrated in sub-drawing (a) of FIG. 1. Alternatively, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal received by a transceiver (113, 123) illustrated in sub-drawing (a) of FIG. 1 being acquired by a processor (111, 121) illustrated in sub-drawing (a) of FIG. 1. Alternatively, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal received by a transceiver (113, 123) illustrated in sub-drawing (b) of FIG. 1 being acquired by a processing chip (114, 124) illustrated in sub-drawing (b) of FIG.

[0072] Referring to the sub-drawing (b) of FIG. 1, software code (115, 125) may be included in the memory (112, 122). The software code (115, 125) may include instructions that control the operation of the processor (111, 121). The software code (115, 125) may be included in various programming languages.

[0073] The processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device. The processor may be an application processor (AP). For example, the processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). For example, the processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may be a SNAPDRAGON™ series processor manufactured by Qualcomm®, an EXYNOSTM series processor manufactured by Samsung®, an A series processor manufactured by Apple®, a HELIO™ series processor manufactured by MediaTek®, an ATOM™ series processor manufactured by INTEL®, or an enhanced processor thereof.

[0074] In this specification, uplink may mean a link for communication from a non-AP STA to an AP STA, and uplink PPDU / packet / signal, etc. may be transmitted through the uplink. In addition, in this specification, downlink may mean a link for communication from an AP STA to a non-AP STA, and downlink PPDU / packet / signal, etc. may be transmitted through the downlink.

[0075] Figure 2 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

[0076] The upper part of Figure 2 shows the structure of the infrastructure BSS (basic service set) of IEEE (institute of electrical and electronic engineers) 802.11.

[0077] The upper part of Figure 2 shows the structure of the infrastructure BSS (basic service set) of IEEE (institute of electrical and electronic engineers) 802.11.

[0078] Referring to the top of FIG. 2, the wireless LAN system may include one or more infrastructure BSSs (200, 205) (hereinafter, BSS). The BSSs (200, 205) are a collection of APs and STAs, such as an access point (AP) 225 and a station (STA1, 200-1), that have successfully synchronized and can communicate with each other, and are not a concept that designates a specific area. The BSS (205) may also include one or more STAs (205-1, 205-2) that can be associated with one AP (230).

[0079] A BSS may include at least one STA, an AP (225, 230) providing a distribution service, and a distribution system (DS, 210) connecting multiple APs.

[0080] A distributed system (210) can connect multiple BSSs (200, 205) to implement an extended service set (ESS, 240). An ESS (240) can be used as a term to indicate a network formed by connecting one or more APs through the distributed system (210). APs included in a single ESS (240) can have the same SSID (service set identification).

[0081] The portal (portal, 220) can act as a bridge to connect a wireless LAN network (IEEE 802.11) to another network (e.g., 802.X).

[0082] In a BSS such as the upper part of Fig. 2, a network between APs (225, 230) and a network between APs (225, 230) and STAs (200-1, 205-1, 205-2) can be implemented. However, it may also be possible to establish a network and perform communication between STAs without an AP (225, 230). A network that establishes a network and performs communication between STAs without an AP (225, 230) is defined as an ad-hoc network or an independent basic service set (IBSS).

[0083] The bottom of Figure 2 is a conceptual diagram showing IBSS.

[0084] Referring to the bottom of Fig. 2, the IBSS is a BSS that operates in ad-hoc mode. Since the IBSS does not include an AP, there is no centralized management entity. That is, in the IBSS, the STAs (250-1, 250-2, 250-3, 255-4, 255-5) are managed in a distributed manner. In the IBSS, all STAs (250-1, 250-2, 250-3, 255-4, 255-5) can be mobile STAs, and access to the distributed system is not permitted, forming a self-contained network.

[0085] Figure 3 is a diagram illustrating a general link setup process.

[0086] In step S310, the STA may perform a network discovery operation. This network discovery operation may include scanning by the STA. That is, for the STA to access the network, it must find a network it can join. Before joining a wireless network, the STA must identify compatible networks. The process of identifying networks in a specific area is called scanning. Scanning methods include active scanning and passive scanning.

[0087] 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 which APs exist in the vicinity while moving between channels and waits for a response. A responder transmits a probe response frame to the STA that transmitted the probe request frame in response to 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 a BSS, the AP transmits the beacon frame, so the AP becomes the responder. In an IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not constant. 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.

[0088] Although not shown in the example of FIG. 3, the scanning operation can also be performed in a passive scanning manner. An STA performing scanning based on passive scanning can wait for a beacon frame while moving between channels. A beacon frame is one of the management frames in IEEE 802.11. It announces the presence of a wireless network and is periodically transmitted so that the scanning STA can find the wireless network and participate in the wireless network. In the BSS, the AP periodically transmits the beacon frame, and in the IBSS, the STAs within the IBSS take turns transmitting the beacon frame. When the scanning STA 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. An STA that receives a beacon frame can store the BSS-related information included in the received beacon frame, move to the next channel, and perform scanning on the next channel in the same manner.

[0089] An STA that discovers a network can perform an authentication process through step S320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation of step S340 described below. The authentication process of S320 may include a process in which the STA transmits an authentication request frame to the AP, and the AP responds by transmitting an authentication response frame to the STA. The authentication frame used for the authentication request / response corresponds to a management frame.

[0090] 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.

[0091] 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.

[0092] A successfully authenticated STA may perform an association process based on step S330. The association process includes a process in which the STA transmits an association request frame to the AP, and the AP transmits an association response frame to the STA in response. For example, the association request frame may include information related to various capabilities, such as a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, RSN, mobility domain, supported operating classes, a Traffic Indication Map Broadcast request, and interworking service capabilities. For example, the association response frame may contain information related to various capabilities, status codes, Association ID (AID), supported rates, Enhanced Distributed Channel Access (EDCA) parameter sets, Received Channel Power Indicator (RCPI), Received Signal to Noise Indicator (RSNI), mobility domains, timeout interval (association comeback time), overlapping BSS scan parameters, TIM broadcast response, QoS maps, etc.

[0093] In step S340, the STA may perform a security setup process. The security setup process of step S340 may include, for example, a process of setting up a private key through a four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame.

[0094] Figure 4 illustrates one embodiment of a multi-link (ML).

[0095] As illustrated in FIG. 4, multiple multi-link devices (MLDs) can communicate over a remote link. The MLDs can be categorized into AP MLDs including multiple AP STAs and non-AP MLDs including multiple non-AP STAs. That is, the AP MLD can include affiliated APs (i.e., AP STAs), and the non-AP MLD can include affiliated STAs (i.e., non-AP STAs, or user-STAs).

[0096] A multilink may include a first link and a second link, and different channels / subchannels / frequency resources may be allocated to the first and second links. The first and second multilinks may be identified through a link ID of 4 bits (or other n bits). The first and second links may be configured in the same 2.4 GHz, 5 GHz, or 6 GHz band. Alternatively, the first link and the second link may be configured in different bands.

[0097] The AP MLD of FIG. 4 includes three affiliated APs. In the example of FIG. 4, AP1 may operate in the 2.4 GHz band, AP2 may operate in the 5 GHz band, and AP3 may operate in the 6 GHz band. In the example of FIG. 4, the first link in which AP1 and non-AP1 operate may be defined as a channel / subchannel / frequency resource within the 2.4 GHz band. Furthermore, in the example of FIG. 4, the second link in which AP2 and non-AP2 operate may be defined as a channel / subchannel / frequency resource within the 5 GHz band. Furthermore, in the example of FIG. 4, the third link in which AP3 and non-AP3 operate may be defined as a channel / subchannel / frequency resource within the 6 GHz band.

[0098] In the example of FIG. 4, AP1 may initiate a multi-link setup procedure (ML setup procedure) by transmitting an Association Request frame to non-AP STA1. In the example of FIG. 4, non-AP STA1 may transmit an Association Response frame in response to the Association Request frame. Each AP (e.g., AP1 / 2 / 3) illustrated in FIG. 4 may be identical to the AP illustrated in FIG. 1 and / or FIG. 2, and each non-AP (e.g., non-AP1 / 2 / 3) illustrated in FIG. 4 may be identical to the STA (i.e., user-STA or non-AP STA) illustrated in FIG. 1 and / or FIG. 2.

[0099] The specific features of this specification are not limited to the specific features of FIG. 4. That is, the number of links can be defined in various ways, and multiple links can be defined in various ways within at least one band.

[0100] FIG. 5 illustrates a PPDU (physical protocol data unit or physical layer (PHY) protocol data unit) transmitted / received by an STA of this specification.

[0101] The STA (e.g., AP STA, non-AP STA, AP MLD, non-AP MLD) of the present specification can transmit and / or receive the PPDU of FIG. 5. The PPDU described in the present specification may have, for example, the structure of FIG. 5. In addition, the PPDU described in the present specification may be called by various names such as a transmission PPDU, a reception PPDU, a first type PPDU, or an Nth type PPDU, etc. The PPDU described in the present specification can be used in a WLAN system defined according to IEEE 802.11bn and / or a next-generation WLAN system that improves IEEE 802.11bn.

[0102] The PPDU of FIG. 5 may be related to various PPDU types used in a UHR system. For example, the example of FIG. 5 may be used for at least one of a single-user (SU) mode / type / transmission, a multi-user (MU) mode / type / transmission, and a null data packet (NDP) mode / type / transmission related to channel sounding. For example, if the example of FIG. 5 is related to NDP, the Data field illustrated may be omitted. If the PPDU of FIG. 5 is used for a trigger-based (TB) mode, the UHR-SIG of FIG. 5 may be omitted. In other words, an STA that has received a trigger frame for UL-MU (Uplink-MU) communication may transmit a PPDU with the UHR-SIG omitted in the example of FIG. 5.

[0103] In FIG. 5, L-STF or UHR-LTF may be called a preamble or physical preamble, and may be generated / transmitted / received / acquired / decoded in the physical layer (included in the transmitting / receiving STA).

[0104] Each block illustrated in Fig. 5 may be called a field / subfield / signal, etc. The names of these fields / subfields / signals may be, as illustrated in Fig. 5, L-STF (legacy short training field), L-LTF (legacy long training field), L-SIG (legacy signal), RL-SIG (repeated L-SIG), U-SIG (Universal Signal), UHR-SIG (UHR-signal), etc.

[0105] The subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG fields in FIG. 5 may be set to 312.5 kHz, and the subcarrier spacing of the UHR-STF, UHR-LTF, and Data fields may be set to 78.125 kHz. That is, the tone index (or subcarrier index) of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG fields may be expressed in units of 312.5 kHz, and the tone index (or subcarrier index) of the UHR-STF, UHR-LTF, and Data fields may be expressed in units of 78.125 kHz.

[0106] In the PPDU of Fig. 5, L-LTF and L-STF may be identical to conventional fields (e.g., non-HT LTF and non-HT STF defined in conventional WLAN standards).

[0107] The L-SIG field of FIG. 5 may include, for example, 24 bits of bit information. For example, the 24 bits of information may include a 4 bit Rate field, a 1 bit Reserved bit, a 12 bit Length field, a 1 bit Parity bit, and a 6 bit Tail bit. For example, the 12 bit Length field may include information about the length or time duration of the PPDU. For example, the value of the 12 bit Length field may be determined based on the type of the PPDU. For example, if the PPDU is a non-HT (non-High Throughput), HT (High Throughput), VHT (Very High Throughput) PPDU, or an EHT (extremely high throughput) PPDU or UHR PPDU, the value of the Length field may be determined as a multiple of 3. For example, if the PPDU is a HE PPDU, the value of the Length field may be determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, for non-HT, HT, VHT PPDU, EHT PPDU, UHR PPDU, the value of the Length field can be determined as a multiple of 3, and for HE (High-Efficiency) PPDU, the value of the Length field can be determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, the Length field in an UHR PPDU is set to a value satisfying the condition that the remainder is zero when LENGTH is divided by 3.

[0108] For example, (non-AP and AP) STAs can apply BCC encoding based on a code rate of 1 / 2 to the 24 bits of information in the L-SIG field. Then, the transmitting STA can obtain 48 BCC coded bits. BPSK modulation can be applied to the 48 coded bits to generate 48 BPSK symbols. The transmitting STA can map the 48 BPSK symbols to positions excluding the pilot subcarriers {subcarrier index -21, -7, +7, +21} and the DC subcarrier {subcarrier index 0}. As a result, the 48 BPSK symbols can be mapped to subcarrier indices -26 to -22, -20 to -8, -6 to -1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA can additionally map the signal {-1, -1, -1, 1} to the subcarrier indices {-28, -27, +27, +28}. The above signal can be used for channel estimation for the frequency domain corresponding to {-28, -27, +27, +28}.

[0109] For example, (non-AP and AP) STA can generate RL-SIG, which is generated in the same manner as L-SIG. BPSK modulation can be applied to RL-SIG. Receiving (non-AP and AP) STA can determine whether the received PPDU is a HE PPDU, EHT PPDU, or UHR PPDU based on the presence of RL-SIG. In other words, if RL-SIG is present, receiving (non-AP and AP) STA can determine whether the received PPDU is one of HE PPDU, EHT PPDU, or UHR PPDU. In other words, if RL-SIG is not present, receiving (non-AP and AP) STA can determine whether the received PPDU is one of non-HT PPDU, HT PPDU, or VHT PPDU. In other words, the RL-SIG field is a repeat of the L-SIG field and is used to differentiate an UHR PPDU from a non-HT PPDU, HT PPDU, and VHT PPDU.

[0110] After the RL-SIG in Fig. 5, a U-SIG (Universal SIG) may be inserted. The U-SIG may be called by various names such as the first SIG field, the first SIG, the first type SIG, the control signal, the control signal field, the first (type) control signal, the common control field, and the common control signal.

[0111] A U-SIG can contain N bits of information and can include information for identifying the type of EHT PPDU. For example, a U-SIG can be formed based on two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., an OFDM symbol) for a U-SIG can have a duration of 4 microseconds. Each symbol of a U-SIG can be used to transmit 26 bits of information. For example, each symbol of a U-SIG can be transmitted and received based on 52 data tones and 4 pilot tones.

[0112] For example, A bit information (e.g., 52 uncoded bits) can be transmitted through U-SIG, and the first symbol of U-SIG can transmit the first X bits of information (e.g., 26 uncoded bits) out of the total A bit information, and the second symbol of U-SIG can transmit the remaining Y bits of information (e.g., 26 uncoded bits) out of the total A bit information. For example, the transmitting STA can obtain 26 uncoded bits included in each U-SIG symbol. The transmitting STA can perform convolutional encoding (i.e., BCC encoding) based on a rate of R=1 / 2 to generate 52 coded bits, and perform interleaving on the 52 coded bits. The transmitting STA can perform BPSK modulation on the interleaved 52 coded bits to generate 52 BPSK symbols allocated to each U-SIG symbol. A single U-SIG symbol can be transmitted based on 56 tones (subcarriers) from subcarrier index -28 to subcarrier index +28, excluding DC index 0. The 52 BPSK symbols generated by the transmitting STA can be transmitted based on the remaining tones (subcarriers) excluding the pilot tones -21, -7, +7, and +21.

[0113] For example, A bit information (e.g., 52 uncoded bits) transmitted by U-SIG may include a CRC field (e.g., a 4-bit long field) and a tail field (e.g., a 6-bit long field). The CRC field and the tail field may be transmitted through the second symbol of the U-SIG. The CRC field may be generated based on 26 bits allocated to the first symbol of the U-SIG and the remaining 16 bits excluding the CRC / tail field within the second symbol, and may be generated based on a conventional CRC calculation algorithm. In addition, the tail field may be used to terminate the trellis of the convolutional decoder and may be set to, for example, "000000".

[0114] The A bit information (e.g., 52 uncoded bits) transmitted by the U-SIG (or U-SIG field) can be divided into version-independent bits and version-dependent bits. For example, the size of the version-independent bits can be fixed or variable. For example, the version-independent bits can be assigned only to the first symbol of the U-SIG, or the version-independent bits can be assigned to both the first symbol and the second symbol of the U-SIG. For example, the version-independent bits and the version-dependent bits can be called by various names, such as the first control bit and the second control bit.

[0115] For example, the version-independent bits of the U-SIG may include a 3-bit PHY version identifier. For example, the 3-bit PHY version identifier may include information related to the PHY version of the transmitted and received PPDU. For example, a first value (e.g., a value of 000) of the 3-bit PHY version identifier may indicate that the transmitted and received PPDU is an EHT PPDU. In addition, a second value (e.g., a value of 001) of the 3-bit PHY version identifier may indicate that the transmitted and received PPDU is an UHR PPDU.

[0116] In other words, when the (AP / non-AP) STA transmits an EHT PPDU, it can set the 3-bit PHY version identifier to the first value. In other words, the receiving (AP / non-AP) STA can determine that the received PPDU is an EHT PPDU based on the PHY version identifier having the first value, and can determine that the received PPDU is an UHR PPDU based on the PHY version identifier having the second value.

[0117] For example, the version-independent bits of U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication.

[0118] For example, the version-independent bits of U-SIG may include information about the length of a transmission opportunity (TXOP) and information about the BSS color ID.

[0119] For example, if a UHR PPDU is classified into various types (e.g., a type related to SU transmission (performed based on UL or DL), a type related to DL transmission, a type related to NDP transmission, a type related to DL non-MU-MIMO, a type related to DL MU-MIMO, a type related to Multi-AP operation, a type related to CBF (Coordinated beamforming), SR (Spatial Reuse), a type related to C-OFDMA (Coordinated OFDMA), a type related to C-TDMA (Coordinated TDMA)), information about the type of the EHT PPDU (e.g., 2-bit or 3-bit information) can be included in the version-dependent bits of the U-SIG.

[0120] For example, a U-SIG may include information about 1) a bandwidth field including information about a bandwidth, 2) a field including information about an MCS technique applied to the UHR-SIG, 3) an indication field including information about whether a dual subcarrier modulation (DCM) technique is applied to the UHR-SIG, 4) a field including information about the number of symbols used for the UHR-SIG, 5) a field including information about whether the UHR-SIG is generated over the entire band, 6) a field including information about the type of UHR-LTF / STF, and 7) a field indicating the length of the UHR-LTF and the CP length.

[0121] Preamble puncturing may be applied to the PPDU of FIG. 5. Preamble puncturing refers to applying puncturing to a portion of the entire bandwidth of the PPDU (e.g., the secondary 20 MHz band). For example, when an 80 MHz PPDU is transmitted, the STA applies puncturing to the secondary 20 MHz band within the 80 MHz band, and can transmit the PPDU only through the primary 20 MHz band and the secondary 40 MHz band.

[0122] For example, the pattern of preamble puncturing can be preset. For example, when the first puncturing pattern is applied, puncturing can be applied only to the secondary 20 MHz band within the 80 MHz band. For example, when the second puncturing pattern is applied, puncturing can be applied only to one of the two secondary 20 MHz bands included in the secondary 40 MHz band within the 80 MHz band. For example, when the third puncturing pattern is applied, puncturing can be applied only to the secondary 20 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band). For example, when the fourth puncturing pattern is applied, a primary 40 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band) may be present, and puncturing may be applied to at least one 20 MHz channel that does not belong to the primary 40 MHz band.

[0123] Information regarding preamble puncturing applied to the PPDU may be included in the U-SIG and / or UHR-SIG. For example, the first field of the U-SIG may include information regarding the contiguous bandwidth of the PPDU, and the second field of the U-SIG may include information regarding preamble puncturing applied to the PPDU.

[0124] For example, U-SIG and UHR-SIG may include information regarding preamble puncturing based on the following method. If the bandwidth of the PPDU exceeds 80 MHz, the U-SIGs may be individually configured in units of 80 MHz. For example, if the bandwidth of the PPDU is 160 MHz, the PPDU may include a first U-SIG for the first 80 MHz band and a second U-SIG for the second 80 MHz band. In this case, the first field of the first U-SIG may include information regarding the 160 MHz bandwidth, and the second field of the first U-SIG may include information regarding preamble puncturing applied to the first 80 MHz band (i.e., information regarding the preamble puncturing pattern). Additionally, the first field of the second U-SIG may include information about a 160 MHz bandwidth, and the second field of the second U-SIG may include information about preamble puncturing applied to the second 80 MHz band (i.e., information about a preamble puncturing pattern). Meanwhile, the UHR-SIG consecutive to the first U-SIG may include information about preamble puncturing applied to the second 80 MHz band (i.e., information about a preamble puncturing pattern), and the UHR-SIG consecutive to the second U-SIG may include information about preamble puncturing applied to the first 80 MHz band (i.e., information about a preamble puncturing pattern).

[0125] Additionally or alternatively, U-SIG and UHR-SIG may include information regarding preamble puncturing based on the following methods. U-SIG may include information regarding preamble puncturing for all bands (i.e., information regarding preamble puncturing patterns). That is, UHR-SIG may not include information regarding preamble puncturing, and only U-SIG may include information regarding preamble puncturing (i.e., information regarding preamble puncturing patterns).

[0126] U-SIGs can be configured in 20 MHz units. For example, if an 80 MHz PPDU is configured, U-SIGs can be duplicated. That is, four identical U-SIGs can be included within an 80 MHz PPDU. PPDUs exceeding the 80 MHz bandwidth can contain different U-SIGs.

[0127] The UHR-SIG of FIG. 5 may include control information for a receiving STA. The UHR-SIG may be transmitted via at least one symbol, and each symbol may have a length of 4 us. Information regarding the number of symbols used for the UHR-SIG may be included in the U-SIG.

[0128] UHR-SIG provides additional signals to the U-SIG field to enable STAs to interpret / decode UHR PPDUs. The UHR-SIG field may contain U-SIG overflow bits that are common to all users. The UHR-SIG field also contains resource allocation information, allowing STAs to look up resources used in fields containing data fields / UHR-STF / UHR-LTF (i.e., UHR modulated fields of an UHR PPDU).

[0129] The frequency resources of the UHR-LTF, UHR-STF, and data fields illustrated in FIG. 5 can be determined based on RUs (resource units) defined by multiple subcarriers / tones. That is, the UHR-LTF, UHR-STF, and data fields of this specification can be transmitted / received through RUs (resource units) defined by multiple subcarriers / tones.

[0130] FIG. 6 is a diagram illustrating the layout of resource units (RUs) used for a 20 MHz PPDU. That is, the UHR-LTF, UHR-STF, and / or data fields included in the 20 MHz PPDU can be transmitted / received through at least one of the various RUs defined in FIG. 6.

[0131] As shown at the top of Fig. 6, 26 units (i.e., units corresponding to 26 tones) can be arranged. Six tones can be used as a guard band in the leftmost band of the 20 MHz band, and five tones can be used as a guard band in the rightmost band of the 20 MHz band. In addition, seven DC tones can be inserted in the center band, i.e., the DC band, and 26 units corresponding to 13 tones can exist on each side of the DC band. In addition, 26 units, 52 units, and 106 units can be allocated to other bands. Each unit can be allocated for a receiving station, i.e., a user.

[0132] Meanwhile, the RU arrangement of FIG. 6 is utilized not only in a situation for multiple users (MUs) but also in a situation for a single user (SU), in which case it is possible to use one 242-unit as shown at the bottom of FIG. 4, in which case three DC tones can be inserted.

[0133] In the example of Fig. 6, RUs of various sizes, such as 26-RU, 52-RU, 106-RU, and 242-RU, are proposed. Since the specific sizes of these RUs can be expanded or increased, the present embodiment is not limited to the specific size of each RU (i.e., the number of corresponding tones). In this specification, N-RU may be represented as N-tone RU, etc. For example, 26-RU may be represented as 26-tone RU.

[0134] Figure 7 is a diagram showing the layout of resource units (RUs) used for 40MHz PPDU.

[0135] As in the example of Fig. 6 where RUs of various sizes were used, the example of Fig. 7 can also use 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, etc. In addition, 5 DC tones can be inserted at the center frequency, 12 tones can be used as a guard band in the leftmost band of the 40 MHz band, and 11 tones can be used as a guard band in the rightmost band of the 40 MHz band.

[0136] Additionally, as illustrated, 484 RUs may be used when used for a single user. Meanwhile, the specific number of RUs may be changed, as in the example of FIG. 6.

[0137] Figure 8 is a diagram illustrating the layout of resource units (RUs) used for an 80MHz PPDU. The layout of resource units (RUs) used in this specification may vary. For example, the layout of resource units (RUs) used in the 80MHz band may vary.

[0138] Figure 9 illustrates an operation according to UL-MU. As illustrated, a transmitting STA (e.g., AP) may perform channel access through contending (i.e., backoff operation) and transmit a trigger frame (930). That is, the transmitting STA (e.g., AP) may transmit a PPDU including a trigger frame (930). When a PPDU including a trigger frame is received, a TB (trigger-based) PPDU is transmitted after a delay of SIFS.

[0139] TB PPDUs (941, 942) are transmitted at the same time and can be transmitted from multiple STAs (e.g., User STAs) whose AIDs are indicated in the Trigger frame (930). The ACK frame (950) for the TB PPDU can be implemented in various forms.

[0140] Figure 10 shows an example of channels used / supported / defined within the 2.4 GHz band.

[0141] The 2.4 GHz band may be referred to by other names, such as the first band (band). Furthermore, the 2.4 GHz band may refer to a frequency range in which channels with a center frequency adjacent to 2.4 GHz (e.g., channels with a center frequency between 2.4 and 2.5 GHz) are used / supported / defined.

[0142] The 2.4 GHz band may include multiple 20 MHz channels. The 20 MHz within the 2.4 GHz band may have multiple channel indices (e.g., indices 1 through 14). For example, the center frequency of a 20 MHz channel assigned channel index 1 may be 2.412 GHz, the center frequency of a 20 MHz channel assigned channel index 2 may be 2.417 GHz, and the center frequency of a 20 MHz channel assigned channel index N may be (2.407 + 0.005*N) GHz. The channel indices may be referred to by various names, such as channel numbers. The specific numerical values ​​of the channel indices and center frequencies may change.

[0143] Figure 10 exemplarily illustrates four channels within the 2.4 GHz band. The illustrated first frequency region (1010) to fourth frequency region (1040) may each include one channel. For example, the first frequency region (1010) may include channel 1 (a 20 MHz channel having an index of 1). In this case, the center frequency of channel 1 may be set to 2412 MHz. The second frequency region (1020) may include channel 6. In this case, the center frequency of channel 6 may be set to 2437 MHz. The third frequency region (1030) may include channel 11. In this case, the center frequency of channel 11 may be set to 2462 MHz. The fourth frequency region (1040) may include channel 14. In this case, the center frequency of channel 14 may be set to 2484 MHz.

[0144] Figure 11 illustrates an example of channels used / supported / defined within the 5 GHz band.

[0145] The 5 GHz band may be referred to by other names, such as a second band / band, etc. The 5 GHz band may refer to a frequency range in which channels with center frequencies greater than or equal to 5 GHz and less than 6 GHz (or less than 5.9 GHz) are used / supported / defined. Alternatively, the 5 GHz band may include multiple channels between 4.5 GHz and 5.5 GHz. The specific figures shown in FIG. 11 are subject to change.

[0146] Multiple channels within the 5 GHz band include Unlicensed National Information Infrastructure (UNII)-1, UNII-2, UNII-3, and ISM. UNII-1 may be referred to as UNII Low. UNII-2 may include frequency ranges called UNII Mid and UNII-2Extended. UNII-3 may be referred to as UNII-Upper.

[0147] Within the 5 GHz band, multiple channels can be configured, and the bandwidth of each channel can be variously configured, such as 20 MHz, 40 MHz, 80 MHz, or 160 MHz. For example, the 5170 MHz to 5330 MHz frequency domain / range within UNII-1 and UNII-2 can be divided into eight 20 MHz channels. The 5170 MHz to 5330 MHz frequency domain / range can be divided into four channels through a 40 MHz frequency domain. The 5170 MHz to 5330 MHz frequency domain / range can be divided into two channels through an 80 MHz frequency domain. Alternatively, the 5170 MHz to 5330 MHz frequency domain / range can be divided into one channel through a 160 MHz frequency domain.

[0148] Figure 12 illustrates an example of channels used / supported / defined within the 6 GHz band.

[0149] The 6 GHz band may also be referred to by other names, such as the third band / band. The 6 GHz band may refer to the frequency range in which channels with center frequencies above 5.9 GHz are used, supported, or defined. The specific figures shown in Figure 12 are subject to change.

[0150] For example, the 20 MHz channel of FIG. 12 can be defined from 5.940 GHz. Specifically, the leftmost channel among the 20 MHz channels of FIG. 12 can have an index of 1 (or channel index, channel number, etc.), and a center frequency of 5.945 GHz can be assigned. That is, the center frequency of the indexed channel N can be determined as (5.940 + 0.005*N) GHz.

[0151] Accordingly, the indexes (or channel numbers) of the 20 MHz channels of FIG. 12 are 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125, 129, 133, 137, 141, 145, 149, 153, 157, 161, 165, 169, 173, 177, 181, 185, 189, 193, It can be 197, 201, 205, 209, 213, 217, 221, 225, 229, 233. Also, according to the (5.940 + 0.005*N) GHz rule mentioned above, the indices of the 40 MHz channels in Fig. 12 can be 3, 11, 19, 27, 35, 43, 51, 59, 67, 75, 83, 91, 99, 107, 115, 123, 131, 139, 147, 155, 163, 171, 179, 187, 195, 203, 211, 219, 227.

[0152] Below, the structure and types / subtypes of MAC frames are described.

[0153] Fig. 13 illustrates an example of a header of a MAC frame. As illustrated, the MAC frame may include a frame control field / information of 2 octets in length, a duration field / information of 2 octets in length, a RA (Receiver Address) field / information of 6 octets in length, and a TA (Transmitter Address) field / information of 6 octets in length. As illustrated in Fig. 13, the four fields may be consecutive to each other. The MAC header of Fig. 13 may be modified in various ways, and a new field may be inserted between the four illustrated fields, or at least one of the illustrated fields may be omitted.

[0154] The MAC header illustrated in Fig. 13 may be positioned at the very front of a MAC frame. That is, the MAC frame may include a MAC header as illustrated in Fig. 13 and MAC body fields / information subsequent to the MAC header. The MAC frame including the MAC header of Fig. 13 is inserted / included in the data field of the PPDU (e.g., UHR PPDU) illustrated in Fig. 5.

[0155] The MAC frames included in the data field of the PPDU of this specification can be classified into various types. For example, the MAC frames of this specification can be classified into control frames, management frames, and data frames.

[0156] For example, the management frame includes Association Request, Association Response, Reassociation Request, Reassociation Response, Probe Request, Probe Response, Beacon, Disassociation, Authentication, and Deauthentication frames / signals defined in conventional WLAN. For the management frame, the values ​​of the type fields (B3 and B2) in FIG. 13 are set to 00. In addition, the values ​​of the subtype fields (B7, B6, B5, B4) in FIG. 13 are as follows: Association Request (0000), Association Response (0001), Reassociation Request (0010), Reassociation Response (0011), Probe Request (0100), Probe Response (0101), Beacon (1000), Disassociation (1010), Authentication (1011), Deauthentication (1100).

[0157] For example, the control frame includes Trigger Beamforming Report Poll, NDP Announcement (NDPA), Control Frame Extension, Control Wrapper, Block Ack Request (BlockAckReq), Block Ack (BlockAck), PS-Poll, RTS, CTS, Ack, and CF-End frames / signals defined in conventional WLAN. For the control frame, the value of the type field (B3 and B2) in FIG. 13 is set to 01. Also, the values ​​of the subtype fields (B7, B6, B5, B4) of FIG. 13 are as follows: Trigger (0010), Beamforming Report Poll (0100), NDP Announcement (0101), Control Frame Extension (0110), Control Wrapper (0111), BlockAckReq (1000), BlockAck (1001), PS-Poll (1010), RTS (1011), CTS (1100), Ack (1101), CF-End (1110).

[0158] For example, the data frame includes (QoS) Data, (QoS) Null, etc. defined in conventional WLAN. For the management frame, the value of the type field (B3 and B2) of Fig. 13 is set to 10.

[0159] The MAC frame / signal used in this specification can be identified through the type field / information and subtype field / information described above. For example, “frame” in this specification can mean a MAC frame in which the type bits B3 and B2 bits in the frame control field of the MAC header are set to 01, and the subtype bits B7, B6, B5, and B4 bits in the frame control field are set to 0010. Various MAC frames described in this specification are inserted / included in the data fields of various PPDUs (e.g., HE / VHT / HE / EHT / UHR PPDUs).

[0160] FIG. 14 illustrates a modified example of a transmitting device and / or a receiving device of the present specification.

[0161] The devices (e.g., AP STA, non-AP STA) illustrated in FIGS. 1 to 4 may be modified as illustrated in FIG. 14. The transceiver (630) of FIG. 14 may be identical to the transceivers (113, 123) of FIG. 1. The transceiver (630) of FIG. 14 may include a receiver and a transmitter.

[0162] The processor (610) of FIG. 14 may be identical to the processor (111, 121) of FIG. 1. Alternatively, the processor (610) of FIG. 14 may be identical to the processing chip (114, 124) of FIG. 1.

[0163] The memory (150) of FIG. 14 may be the same as the memory (112, 122) of FIG. 1. Alternatively, the memory (150) of FIG. 14 may be a separate external memory different from the memory (112, 122) of FIG. 1.

[0164] Referring to FIG. 14, a power management module (611) manages power to a processor (610) and / or a transceiver (630). A battery (612) supplies power to the power management module (611). A display (613) outputs results processed by the processor (610). A keypad (614) receives input to be used by the processor (610). The keypad (614) may be displayed on the display (613). A SIM card (615) may be an integrated circuit used to securely store an international mobile subscriber identity (IMSI) and an associated key used to identify and authenticate a subscriber in a mobile phone device, such as a mobile phone or computer.

[0165] Referring to FIG. 14, the speaker (640) can output sound-related results processed by the processor (610). The microphone (641) can receive sound-related input to be used by the processor (610).

[0166] 1. Problems with prior art (Fast BSS Transition (FT))

[0167] Figure 15 illustrates an over-the-air (OTA) FT protocol in a Robust Security Network (RSN).

[0168] Currently, in 802.11, when a non-AP STA moves (roams) from an AP (Old AP) to another AP (New AP), i.e., for a BSS (Basic Service Set) Transition, it must go through a reassociation process in the same mobility domain. A representative example is the Fast BSS Transition (FT) technology. In FT, as shown in Figure 15, several processes such as authentication and reassociation are performed with the FT Originator (FTO) and the Target FT Responder (FTR) (i.e., the New AP).

[0169] After this process, many operational parameters such as Agreement, Sequence Number (SN), EDCAF Parameter, etc. related to BlockAck (BA), Stream Classification Service (SCS), etc. are reset. Accordingly, there is an overhead that requires re-performing agreement / configuration along with multiple frame exchanges, and data loss may also occur during the FT process. Furthermore, from the perspective of a non-AP STA, seamless roaming without interruption is not easy. Therefore, this specification proposes a seamless roaming method utilizing AP MLD (Multi-Link Device) to solve this problem. Unlike FT, roaming does not require re-authentication / association.

[0170] In this specification, an STA performing BSS Transition (i.e., Roaming) is referred to as an RSTA, the AP to which the STA is currently associated when roaming is referred to as an Old AP (O_AP), and the AP to which the STA will roam is referred to as a New AP (N_AP). In addition, the Roaming method proposed in this specification is referred to as MLD Roaming. The designations (names) in this specification may be changed, and an STA may include an AP STA or a non-AP STA.

[0171] 2. UHR AP MLD structure for roaming

[0172] 2.1 General Procedure of Roaming in AP MLD

[0173] Figure 16 illustrates the high-level architecture for AP MLD.

[0174] Basically, an AP MLD can include one or more APs and has a high-level architecture as shown in Figure 16. Basically, the MLD can control several procedures / parameters common to multiple APs using the upper MAC sublayer. Examples of these procedures / parameters include authentication, association, SN / PN assignment, and power-save buffering of individually addressed frames.

[0175] Therefore, by utilizing AP MLD functionality, MLD-level parameters can be maintained without being reset when moving between APs (affiliated APs) involved in AP MLD. This specification proposes a roaming method utilizing AP MLD functionality.

[0176] Figure 17 illustrates an example of a high-level architecture for UHR AP MLD.

[0177] Figure 17 illustrates the architecture of APs supporting Seamless Roaming. To support Seamless Roaming, devices must be compatible with previous standard versions and enable seamless roaming between multiple devices. First, to ensure legacy compatibility with older devices, non-UHR non-AP STAs must be able to see non-UHR APs. This requires maintaining the MLD definition itself and preserving the existing architecture. Therefore, as shown in Figure 17, we define a new UHR AP MLD that maintains the existing MLD architecture while hierarchically affiliates MLDs that support seamless roaming. Each LMAC of the AP MLDs interfaces with a UHR UMAC, and the functions of the UMAC of the AP MLD that supports seamless roaming are managed by the UHR UMAC. A separate entity can manage various functions for roaming between AP MLDs (e.g., multi-link authentication (e.g., PTK), multi-link discovery / setup, multi-link reconfiguration). That is, this specification does not limit roaming support to UMAC. An example of such a case is shown in Figure 18. An entity can manage the control plane context and, as needed, other contexts. The AP MLD and UHR AP MLD are each individually connected to a DS (Distribution System). This architecture can also resolve scalability issues caused by the limitations of the Link ID bit size.Basically, the link ID is a 4-bit identifier and can support up to 16 link IDs. This link ID is required to move from one link to another during roaming, but the existing method limits the number of APs that can be roamed to 16. To address this issue, link IDs are grouped together with AP MLD IDs, addressing scalability issues. This is described in more detail in Section 2.2 below.

[0178] Figure 18 illustrates another example of a high-level architecture for UHR AP MLD.

[0179] Figure 19 illustrates another example of the High-level Architecture for UHR AP MLD.

[0180] Figure 19 shows an example with a similar architecture to Figure 17 but with different interfacing. Figure 18 shows that the LMAC of the AP MLD and the UHR UMAC are not directly connected, but are interfaced to the TID-to-Link Mapping function of the UMAC. This architecture allows for TID-to-Link Mapping to be performed individually in the UMAC of the AP MLD or in the UHR UMAC. The AP MLD and the UHR AP MLD are each individually connected to the DS. The method of use of this architecture and the types and number of functions that interface with the UHR UMAC are not limited.

[0181] Figure 20 illustrates an example of a high-level architecture in the case where there are only entities that are not MLD-based.

[0182] Figure 21 illustrates another example of a High-level Architecture in the case of entities that are not MLD-based.

[0183] The entities in Figures 18, 20, and 21 have functionality for roaming. AP MLDs capable of roaming are connected to a single entity and can perform association, authentication, link setup, and other operations with this entity. The entity also manages control plane contexts. AP MLDs capable of roaming can be grouped under the concept of a domain, and one or more entities can exist within a domain. It manages contexts that must be shared between APs for non-AP STAs to perform seamless roaming.

[0184] Figure 22 illustrates an example of a Roaming Architecture in an AP MLD area.

[0185] Figure 22 shows the structure and process for basic Roaming.

[0186] Each AP MLD is in a different location (i.e., non-collocated), and the APs belonging to each AP MLD are in the same or similar locations (i.e., collocated). This collocated may mean belonging to the exact same physical device, or it may mean belonging to a logically similar location even if it does not belong to a physical device. Since an AP MLD is a logical entity, it can be any physical device, but regardless of location, it can operate as an MLD that includes affiliated APs and can apply multi-link operation (MLO). Ultimately, all APs belonging to each AP MLD become affiliated APs of one AP MLD. For example, AP MLD 1 in Figure 22 includes affiliated APs 1, 2, and 3.

[0187] Based on Fig. 22, when a non-AP MLD moves, it will typically roam from one AP MLD to another. For example, if a non-AP MLD is configured with a multi-link setup with an AP MLD, and STA 1 and STA 2 are connected to AP 2 and AP 3 of AP MLD 1, when roaming to AP MLD 2, STA 1 may be connected to AP 4 and STA 2 may be connected to AP 5. In this case, each STA may temporarily associate with AP 4 and AP 5 so that AP 4 and AP 5 can transmit frames to each STA during the roaming process.

[0188] For reference, in Fig. 22, this architecture can be applied to a non-AP MLD with one affiliated STA rather than a non-AP MLD with multiple affiliated STAs, or a non-AP STA that is not an MLD.

[0189] However, roaming does not necessarily only involve moving between different AP MLDs. For example, roaming can also involve changing APs within an AP MLD.

[0190] That is, a UHR AP MLD (or roaming-capable group) is affiliated with at least one (EHT) AP MLD, each AP MLD is non-collocated, and the APs belonging to each AP MLD are collocated.

[0191] Typically, a non-AP MLD (or STA) roams from one AP MLD to another (although roaming can also change APs within a specific AP MLD).

[0192] Since we are changing APs within the AP MLD, we can consider Roaming as a way to change links while maintaining the Multi-link Setup without completely tearing down the existing Multi-link Setup.

[0193] Since these processes are changing APs within the AP MLD, Roaming can be considered as a way to change links while maintaining the Multi-link Setup without completely tearing down the existing Multi-link Setup.

[0194] Basically, it can be composed of a) Announcement process and b) Frame exchange.

[0195] a) Announcement process: Each AP in the AP MLD announces to STAs whether it can perform MLD Roaming as proposed in this specification and information related to roaming APs within the AP MLD.

[0196] b) Frame exchange process: This is the process of exchanging frames that can trigger MLD roaming. Once frame exchange is complete, MLD roaming is completed based on the negotiated information, and operations with the O_AP are no longer performed, but rather with the N_AP.

[0197] In particular, this specification proposes to use the following method for MLD Roaming.

[0198] - One or more STAs belonging to a non-AP MLD can establish multiple links, each with a single radio. Therefore, we propose a method where a single STA adds and deletes links. This allows two or more links to be connected to a single STA.

[0199] - However, since frame exchange is performed only on one link and frame exchange cannot be performed on the remaining links, it becomes a doze state or disabled state.

[0200] - To achieve this, the non-AP MLD basically informs whether it is capable of the above-described capabilities in the Association Request frame during ML setup, i.e., when transmitting a Management frame containing the Basic Multi-link ML IE. This can be included in the MLD Capabilities and Operations subfield of the Common Info field if all STAs are capable, or in the Link Info field if only some STAs are capable. The information to be included is as follows:

[0201] => Single-radio ML setup enabled: This information indicates that STAs in a non-AP MLD can each have one radio and set up multiple links. This means that more than two links can be connected to one STA.

[0202] 2.2 Frame exchange process for MLD Roaming

[0203] Basically, for MLD Roaming to be triggered, frame exchange is required between the non-AP MLD (or STA) and the AP MLD. This frame can utilize the MGMT frame, particularly the Action frame, a type of MGMT frame. The frames are referred to as follows:

[0204] - The frame in which the STA requests MLD Roaming to the AP can be called the MLD Roaming Request frame.

[0205] - The frame in which the AP requests MLD Roaming to the STA can be called the MLD Roaming Response frame.

[0206] 2.2.1 MLD Roaming Request frame format

[0207] The MLD Roaming Request frame format can be configured in the following order:

[0208] OrderInformation1Category2UHR Action or Protected UHR Action3Dialog Token4Reconfiguration Multi-Link element5Context Transfer Level6Data Transfer Enabled

[0209] Order 1: Basically, a Category can be included in a new UHR Action or a Protected UHR Action, but is not limited to these.

[0210] Order 4: The Reconfiguration Multi-link IE defined in the existing 802.11be can be used to provide the information required for MLD Roaming requests.

[0211] - The modified Reconfiguration Multi-link IE is as follows:

[0212] Order 5: When requesting MLD Roaming, the degree to which context transfer is required or possible can be indicated by setting the bit value of the Context Transfer Level.

[0213] Order 6: This field can be used to indicate whether data transfer between AP MLDs is supported.

[0214] 2.2.2 MLD Roaming Response frame format

[0215] In the MLD Roaming Response frame, it is necessary to consider the link-level parameters that must be provided because the link must be changed while maintaining the multi-link setup.

[0216] OrderInformation1Category2UHR Action or Protected UHR Action3Dialog Token4Status Code5Basic Multi-Link element6Group key Information7AID8Channel Switching Announcement element (optional)9Extended Channel Switching Announcement element (optional)10TID-to-link Mapping element (optional)11Context Transfer Level12Context Transfer Contents Feedback13Queued Packets14Queued DL Data Timer

[0217] Order 1: Basically, a Category can be included in a new UHR Action or a Protected UHR Action, but is not limited to these.

[0218] Order 4: Status Code can utilize the existing Status code field.

[0219] - When responding to an MLD Roaming request, the Basic Multi-link IE defined in the existing 802.11be can be used to obtain the necessary information about AP MLD and N_AP.

[0220] Order 5: The modified Basic Multi-link IE is as follows:

[0221] Order 11: When sending an MLD Roaming Response, the degree of context transfer required can be indicated by setting the bit value of the Context Transfer Level.

[0222] Order 12: Context Transfer is complete and the contents actually transferred via Context Transfer are reported. At this time, the Context Transfer Level can be used.

[0223] The methods for providing this information can be broadly divided into Bitmap and Indexing methods.

[0224] - Bitmap method: Each Context Transfer Level is indicated by a bit of 0 or 1, and if the context corresponding to the level is actually transferred, it is set to 1, and if not transferred, it is set to 0. In this way, based on the details of the actual transfer, the STA can determine what needs to be negotiated or established again after roaming. Even without using 0 and 1, the presence / absence of the bit corresponding to the Context Transfer Level can be notified. For example, if it is bit 1: BA agreement but the bit does not exist, it can be known that it was not transferred.

[0225] - Indexing method:

[0226] a. Accumulation method: Accumulated in the order of Context Transfer Level. If bit 2 is displayed, it means that all contexts corresponding to bits 0, 1, and 2 have been transferred.

[0227] b. Grouping method: Specific bits can be grouped and notified as bits. For example, bit 3 may be a group including BA agreement and SN / PN, and bit 4 may be a group including SN / PN and Packet Reordering. In this example, if the field indicating context transfer in the Roaming Response is set to bit 3, it can be known that the context corresponding to SN / PN and BA Agreement has been transferred. There are various cases for grouping methods and it is not limited to this example.

[0228] As above, you can tell whether or not there are items that have been context transferred, or you can tell only those that have not been context transferred or those that have been context transferred.

[0229] Order 13: When roaming, a non-AP STA can use the Queued Packets field to indicate whether there are packets in the queue of the AP MLD (e.g., current AP MLD) that receives the Roaming Response frame. If Queued Packets is set to 1, it means there are packets left in the queue, and if it is set to 0, it may mean there are no packets left in the queue. Or, the opposite can apply. When roaming, a non-AP STA can read the Queued Packets field and determine whether to pass on to the newly roaming AP MLD (e.g., target AP MLD). When the non-AP MLD receives a Roaming Response, it reads the Queued Packets field, and if Queued Packets is set to 1, it can reflect (or include) additional information described below (e.g., DL data size, Number of pending MSDUs, SN or PN related information, TIDs for pending MSDUs) to know how and until when to receive DL data from the Serving AP MLD before roaming to the Target AP MLD. Conversely, if Queued Packets is set to 0, it can immediately start DL / UL transmission with the Target AP MLD after receiving the Roaming Response. Channel Switch Count is a period that allows operation (e.g., DL forwarding) with the AP MLDs that are connected while the previous link is added, and when the Channel Switch Count expires, the period corresponds to the point where the existing link is deleted and the AP MLD that roamed to the newly added link moves to a completely new link.The value of the above section can represent the number of TBTT (Target Beacon Transmission Time), or it can be the actual time unit in X unit (e.g. us). Through the Channel Switch Count field, the AP can inform the STA when to perform link switch to a new link. If the times to complete the link switch for each link are different, the Channel Switch Count field can be added to the Link Info to inform each link individually when to complete the link switch. If a link switch is requested for only one link in the MLD Roaming Request, the Channel Switch Count field can be included in the Common Info or the Link Info. Through the Channel Switch Count, when moving from O_AP to N_AP and switching to a new link, if the channels of the two links are different and information such as when the link was switched to another link cannot be exchanged, by setting a specified Count or time, the link switch can be known until when.

[0230] Order 13: If Queued packet is set to 1, additional information can be provided. This information includes:

[0231] - DL data size: Actual amount of DL data

[0232] - Number of pending MSDUs: The number of MSDUs (MAC Service Data Units) that have not yet been transmitted.

[0233] - Information related to SN (Sequence Number) or PN (Packet Number)

[0234] Example) Last SN / PN among MSDUs or Range

[0235] - TIDs (Traffic Identifiers) for pending MSDU: TIDs can be notified as a bitmap or value.

[0236] The above SN may be a unique number for identifying the order of transmitted frames or packets. The PN may be a serial number or identification number assigned to a packet. When transmitting multiple frames or packets, the transmitting side increments the SN or PN by one and assigns it, and the receiving side can detect sequence errors or loss through the SN or PN.

[0237] Order 14: Queued DL Data Timer is timer information that the Serving AP MLD notifies the non-AP MLD STA, and the timer information is related to the time to transmit the data remaining in the Buffer of the Serving AP MLD. When the time elapses, the non-AP MLD STA transitions to the Target AP MLD. Even if the amount of queued data is not fully transmitted, the transition to the Target AP MLD is made when the timer expires. If the transmission of all DL data accumulated in the Serving AP MLD is completed before the timer expires, the transition to the Target AP MLD can be made immediately.

[0238] The fact that the transmission of DL Data is complete means that the data corresponding to the Last SN of Order 13: Queued Packets has been transmitted, or if the More Data subfield is set to 0, all data accumulated in the buffer has been transmitted.

[0239] Before the timer expires, if the data corresponding to the Last SN value is not transmitted or the More Data subfield is set to 1 and the Data Transfer value of the Roaming Request frame is set to 1, it can be known that the untransmitted data has been passed on to the target AP MLD through Data Transfer. If the Data Transfer value is set to 0, it can be known that data loss has occurred. In this case, the timer can be extended until the transmission of the remaining data is completed.

[0240] AP MLD may inform non-AP MLD including one or more of the above additional information.

[0241] 2.3 Data Transfer

[0242] 2.3.1. Data Transfer Between AP MLDs

[0243] DL data that has been buffered in the Serving AP MLD until the Roaming Request is transmitted will result in data loss if the non-AP MLD STA does not receive the transmission before it moves on to the Target AP MLD. However, if the amount of buffered data is large or the channel condition is poor, making it difficult to complete the transmission of DL data before the Queued DL Data Transmission Timer expires, the Serving AP MLD can directly transmit some or all of the buffered data to the Target AP MLD.

[0244] Figure 23 illustrates an example of a data transfer procedure.

[0245] Figure 23 illustrates an example of a data transfer process assuming a non-AP MLD STA sends a Roaming Request. This example illustrates the baseline procedure of the data transfer itself, excluding the DL data transmission process received from the Serving AP MLD. The information required in advance for data transfer is included in the Roaming Request and Response frames. Data transfer is possible through Over-the-DS (communication via a wired DS connected between the Serving AP MLD and the Target AP MLD) and Over-the-Air (direct wireless communication between the non-AP MLD STA and the Target AP MLD from the non-AP MLD).

[0246] If the connected channel between the non-AP MLD STA and the Serving AP MLD and the Target AP MLD is the same, the non-AP MLD STA can receive the data transferred to the Target AP MLD without transitioning to the Target AP MLD. However, if the channel is different, the non-AP MLD STA can receive the transferred data after transitioning to the Target AP MLD.

[0247] Figure 24 illustrates an example of transmitting DL data accumulated in the queue of the Serving AP MLD.

[0248] As shown in FIG. 24, if the Queued packet is set to 1 in the Roaming Response frame and the additional information described above is provided, the Serving AP MLD transmits the DL Data remaining in the queue of the Serving AP MLD after transmitting the Roaming Response frame. The Non-AP MLD STA can measure the amount of DL data through the DL data size or the Number of pending MSDUs to determine the end of the DL Data transmission, or the Serving AP MLD can use the Last SN / PN information or the last DL data bit in the last DL data to indicate the part of the last DL data.

[0249] Figure 25 illustrates an example of notifying the completion of transmission of DL data accumulated in the queue of the Serving AP MLD using the DL Timer.

[0250] Figure 25 calculates the time required to transmit DL data in advance through the MSDU DL data size or the number of pending MSDUs, and then sets the DL Timer to determine when the DL data ends.

[0251] Additionally, if a Roaming Response is received and the value of the Queued Packets field is 1 and the non-AP STA does not know when the transmission of the queued packets of the Serving AP MLD will be completed, the Serving AP MLD can resend the Roaming Response with the value of the Queued Packets field set to 0 when the packets in the queue are gone. Based on the Roaming Response including the Queued Packets field with a value of 0, the non-AP MLD can indicate when it moves on to the Target AP MLD.

[0252] Figure 26 illustrates an example of transmitting data using Data Transfer when Queued DL Data is not fully transmitted.

[0253] Referring to FIG. 26, if there is data remaining in the buffer of the Serving AP MLD when the Queued DL Data Timer expires, the Serving AP MLD can perform additional data transfer to the Target Ap MLD.

[0254] Figure 27 illustrates an example of extending the Queued DL Data Timer when the Queued DL Data is not fully transmitted.

[0255] Referring to FIG. 27, if the remaining data is not transmitted through Data Transfer, the Queued DL Data Timer can be extended so that the Serving AP MLD can complete the transmission. For example, in the case of Different Channels where there is a delay in data transfer (for example, when the channels connected to the non-AP MLD STA and the Serving AP MLD and the Target AP MLD are different), the transition to the Target AP MLD can be performed only after the data transfer is completed. Accordingly, if the time of transitioning to the Target AP MLD is delayed, the present embodiment can also propose a method of extending the Queued DL Data Timer as shown in FIG. 27 to complete the transmission of the Queued DL Data.

[0256] Figure 28 is a flowchart illustrating the operation of a transmitting device according to the present embodiment.

[0257] An example of FIG. 28 may be performed at a transmitting STA or transmitting device (AP and / or non-AP STA).

[0258] Some of the steps (or detailed sub-steps described below) in the example of Fig. 28 may be omitted or changed.

[0259] Through step S2810, the transmitting device (transmitting STA) can obtain information regarding the aforementioned Tone Plan. As described above, the information regarding the Tone Plan includes the size and location of the RU, control information related to the RU, information regarding the frequency band in which the RU is included, information regarding the STA receiving the RU, etc.

[0260] Through step S2820, the transmitting device can configure / generate a PPDU based on the acquired control information. The step of configuring / generating the PPDU may include a step of configuring / generating each field of the PPDU. That is, step S2820 may include a step of configuring an EHT-SIG field including control information regarding a Tone Plan. That is, step S2820 may include a step of configuring a field including control information indicating the size / position of an RU (e.g., an N bitmap) and / or a step of configuring a field including an identifier (e.g., an AID) of an STA receiving the RU.

[0261] Additionally, step S2820 may include a step of generating an STF / LTF sequence to be transmitted through a specific RU. The STF / LTF sequence may be generated based on a preset STF generation sequence / LTF generation sequence.

[0262] Additionally, step S2820 may include a step of generating a data field (i.e., MPDU) to be transmitted via a specific RU.

[0263] The transmitting device can transmit the PPDU configured through step S2820 to the receiving device based on step S2830.

[0264] While performing step S2830, the transmitting device may perform at least one of operations such as CSD, Spatial Mapping, IDFT / IFFT operation, and GI insertion.

[0265] A signal / field / sequence configured according to this specification can be transmitted in the form of FIG. 5.

[0266] Fig. 29 is a flowchart illustrating the operation of a receiving device according to the present embodiment.

[0267] The above-described PPDU can be received according to an example of FIG. 29.

[0268] An example of FIG. 29 may be performed at a receiving STA or receiving device (AP and / or non-AP STA).

[0269] Some of the steps (or detailed sub-steps described below) in the example of Fig. 29 may be omitted.

[0270] A receiving device (receiving STA) may receive all or part of a PPDU through step S2910. The received signal may have the form of FIG. 5.

[0271] The sub-step of step S2910 can be determined based on step S2830 of Fig. 28. That is, step S2910 can perform an operation to restore the results of the CSD, Spatial Mapping, IDFT / IFFT operations, and GI insert operations applied in step S2830.

[0272] At step S2920, the receiving device can decode all or part of the PPDU. Additionally, the receiving device can obtain control information related to the Tone Plan (i.e., RU) from the decoded PPDU.

[0273] More specifically, the receiving device can decode the L-SIG and EHT-SIG of the PPDU based on the Legacy STF / LTF and obtain information included in the L-SIG and EHT SIG fields. Information regarding various Tone Plans (i.e., RUs) described herein can be included in the EHT-SIG, and the receiving STA can obtain information regarding the Tone Plan (i.e., RU) through the EHT-SIG.

[0274] In step S2930, the receiving device can decode the remaining portion of the PPDU based on the information about the Tone Plan (i.e., RU) acquired through step S2920. For example, the receiving STA can decode the STF / LTF field of the PPDU based on the information about one Plan (i.e., RU). In addition, the receiving STA can decode the data field of the PPDU based on the information about the Tone Plan (i.e., RU) and acquire the MPDU included in the data field.

[0275] Additionally, the receiving device may perform a processing operation to transmit the decoded data to a higher layer (e.g., MAC layer) through step S2930. Additionally, if the generation of a signal is instructed from the higher layer to the PHY layer in response to the data transmitted to the higher layer, a subsequent operation may be performed.

[0276] Hereinafter, the above-described embodiment will be described with reference to FIGS. 1 to 29.

[0277] FIG. 30 is a flowchart illustrating a procedure for setting a timer for transmitting DL data that is waiting for Serving AP MLD in MLD roaming according to the present embodiment.

[0278] An example of FIG. 30 can be performed in a network environment that supports a next-generation wireless LAN system (UHR (Ultra High Reliability) wireless LAN system or next wi-fi). The next-generation wireless LAN system is a wireless LAN system that improves on the 802.11be system and can satisfy backward compatibility with the 802.11be system.

[0279] The present embodiment proposes a method for setting a data timer used to transmit data in a buffer of a Serving AP MLD to a non-AP STA belonging to a non-AP MLD when MLD roaming is performed. Specifically, the present embodiment proposes a method for transmitting data in a buffer of the Serving AP MLD to the non-AP STA before the data timer expires, and for extending the data timer for processing remaining data that has not been transmitted to the non-AP STA after the data timer expires, or a method for directly transmitting data from the Serving AP MLD to the Target AP MLD.

[0280] In step S3010, the first AP belonging to the first AP MLD receives a roaming request frame from a non-AP STA (station) belonging to the non-AP MLD.

[0281] In step S3020, after the context is transferred from the first AP MLD to the second AP MLD, the first AP transmits a roaming response frame to the non-AP STA.

[0282] In step S3030, the first AP transmits queued DL (downlink) data to the non-AP STA.

[0283] The above roaming response frame includes information about the timer of the waiting DL data.

[0284] The above-mentioned waiting DL data is data that can be transmitted before the timer of the above-mentioned waiting DL data expires among the data in the buffer of the first AP MLD for the above-mentioned non-AP STA.

[0285] That is, the present embodiment proposes a method in which the non-AP STA receives data in the buffer of the first AP MLD before the timer of the pending DL data set based on the roaming response frame expires. In addition, the present embodiment proposes a method in which, if all data in the buffer of the first AP MLD cannot be transmitted before the timer of the pending DL data expires, the timer of the pending DL data is extended to transmit the remaining data or the data is directly transmitted from the first AP MLD to the second AP MLD (see the description below). This has the effect of allowing the non-AP MLD to determine how long it is connected to the Serving AP MLD to receive data in the buffer and at what point it can transition to the Target AP MLD. In addition, it has the effect of minimizing data loss that may occur when the non-AP MLD transitions to the Target AP MLD.

[0286] The above roaming response frame may further include information about the presence of a waiting packet and additional information related to the waiting packet.

[0287] Based on the information on whether the above-mentioned waiting packet exists being set to a first value (e.g., 1), the above-mentioned waiting DL data may exist. Based on the information on whether the above-mentioned waiting packet exists being set to a second value (e.g., 0), the above-mentioned waiting DL data may not exist.

[0288] Additional information related to the above-mentioned waiting packet may include information about the size of the above-mentioned waiting DL data, information about the number of MSDUs (MAC Service Data Units) that have not yet been delivered, information about the last SN (Sequence Number) or last PN (Packet Number) of the MSDU, and TID (Traffic Identifier) ​​information for the MSDU.

[0289] Based on whether all data in the buffer of the first AP MLD is transmitted before the timer of the waiting DL data expires, the non-AP STA can transit from the first AP MLD to the second AP MLD. At this time, it can be confirmed that all data in the buffer of the first AP MLD is transmitted based on information about the last SN or the last PN. In addition, it can be confirmed that all data in the buffer of the first AP MLD is transmitted based on information about the size of the waiting DL data, information about the number of MSDUs not yet transmitted, and / or TID information for the MSDUs.

[0290] Additionally, the present embodiment proposes a method for transmitting remaining data depending on whether data transmission between the first and second AP MLDs is supported.

[0291] The above roaming request frame may include information on whether data transfer between the first and second AP MLDs is supported.

[0292] Based on the above information, based on supporting data transfer between the first and second AP MLDs, data remaining after the timer of the waiting DL data expires among the data in the buffer of the first AP MLD is transferred from the first AP MLD to the second AP MLD, and the remaining data can be transferred after the waiting DL data is transferred.

[0293] Based on the fact that data transfer between the first and second AP MLDs is not supported (based on the above information), data remaining after the timer of the waiting DL data expires among the data in the buffer of the first AP MLD is not transferred from the first AP MLD to the second AP MLD, the timer of the waiting DL data is extended, and the remaining data can all be transferred from the first AP MLD to the non-AP STA before the timer of the extended waiting DL data expires.

[0294] After roaming is performed from the first AP MLD to the second AP MLD based on the roaming response frame, the second AP belonging to the second AP MLD can exchange data with the non-AP STA. (Alternatively, the non-AP STA can perform roaming from the first AP MLD to the second AP MLD based on the roaming response frame. The non-AP STA can perform data exchange with the second AP belonging to the second AP MLD.)

[0295] The first AP may be referred to as Old AP (O_AP), Serving AP, or Current AP. The second AP may be referred to as New AP (N_AP) or Target AP. The first AP MLD including the first AP may be referred to as Serving AP MLD. The second AP MLD including the second AP may be referred to as Target AP MLD. MLD roaming from the Serving AP MLD to the Target AP MLD is defined as an operation of seamlessly moving from one AP to another without any disconnection between the AP and the STA within the MLD.

[0296] The first and second AP MLDs are included in a roaming-enabled group. The roaming-enabled group may be referred to as a UHR AP MLD. The first and second AP MLDs are non-collocated, but are included in the same roaming-enabled group, so roaming (or movement) from an AP in the first AP MLD to an AP in the second AP MLD is possible. The APs in the first AP MLD are collocated. The APs in the second AP MLD are also collocated.

[0297] The non-AP STA can perform roaming from the first AP to the second AP based on the roaming request frame and the roaming response frame.

[0298] In seamless roaming, there can be two types of architectures:

[0299] First, there is the MLD-based architecture. The MLD-based architecture refers to a case where all AP MLDs have a single medium access control (MAC) service access point (SAP) in a single domain called SMD (Single Mobility Domain). In other words, the MLD-based architecture has a common AP MLD upper MAC interfaced to all AP MLDs capable of performing seamless roaming. The UMAC of the UFT AP MLD controls all UMAC functions required for seamless roaming and has its own MAC SAP and unique MLD MAC address. Since the MLD-based architecture is a centralized architecture, contexts are not transferred through the DS (Distribution System), and context transfer may not exist.

[0300] Second, there is a context-passing-based architecture. This context-passing-based architecture is an improved roaming architecture that utilizes existing architectures (specifically, existing Fast Transition (FT)). This method requires context-passing between the serving AP MLD and the target AP MLD. Each AP MLD has its own MAC SAP. Each AP MLD is individually mapped to a DS, and non-AP MLDs are associated with an AP MLD. When a non-AP MLD roams from the serving AP MLD to the target AP MLD, it should roam without re-authentication and re-association. To share information among AP MLDs, AP MLDs within a single domain need to be associated with a logical entity. A security key (e.g., a single MAC address for SMD) must be shared among AP MLDs within the same single domain.

[0301] The MLD-based architecture offers virtually no delay, but requires architectural changes and is more complex to implement. Security keys are generated in the roaming MLD and shared with affiliated AP MLDs. In contrast, roaming with context transfer introduces some delay, which may worsen over other channels. However, it maintains the current architecture and offers simpler implementation. Security keys are shared over a secure channel. Therefore, the MLD-based architecture is the preferred scenario because it satisfies the goal of seamless roaming with virtually no delay. However, implementation can be challenging due to the architectural changes, and a context transfer-based architecture can be used for ease of implementation.

[0302] The first AP MLD, the second AP MLD, and the roaming-enabled group may be connected to a Distribution System (DS). For example, based on the fact that the first and second AP MLDs each have their own MAC SAPs, after the MLD roaming request frame is transmitted, the context may be transmitted to the second AP MLD via the DS.

[0303] The above context may be referred to as a parameter set negotiated between an AP and an STA (or between a non-AP MLD STA and a Serving AP MLD). The DS may be a backbone network for a wireless LAN that extends a wireless network by providing connectivity between different BSSs (Basic Service Sets).

[0304] The above roaming request frame may be defined based on a Reconfiguration Multi-link Information Element (IE). The above roaming response frame may be defined based on either a Reconfiguration Multi-link IE or a Basic Multi-link IE.

[0305] FIG. 31 is a flowchart illustrating a procedure for a non-AP MLD to receive DL data waiting based on a timer in MLD roaming according to the present embodiment.

[0306] An example of FIG. 31 can be performed in a network environment that supports a next-generation wireless LAN system (UHR (Ultra High Reliability) wireless LAN system or next wi-fi). The next-generation wireless LAN system is a wireless LAN system that improves on the 802.11be system and can satisfy backward compatibility with the 802.11be system.

[0307] The present embodiment proposes a method for setting a data timer used to transmit data in a buffer of a Serving AP MLD to a non-AP STA belonging to a non-AP MLD when MLD roaming is performed. Specifically, the present embodiment proposes a method for transmitting data in a buffer of the Serving AP MLD to the non-AP STA before the data timer expires, and for extending the data timer for processing remaining data that has not been transmitted to the non-AP STA after the data timer expires, or a method for directly transmitting data from the Serving AP MLD to the Target AP MLD.

[0308] In step S3110, a non-AP STA (station) belonging to the non-AP MLD transmits a roaming request frame to the first AP belonging to the first AP MLD.

[0309] In step S3120, after the context is transferred from the first AP MLD to the second AP MLD, the non-AP STA receives a roaming response frame from the first AP.

[0310] In step S3130, the non-AP STA receives queued DL (downlink) data from the first AP MLD.

[0311] The above roaming response frame includes information about the timer of the waiting DL data.

[0312] The above-mentioned waiting DL data is data that can be transmitted before the timer of the above-mentioned waiting DL data expires among the data in the buffer of the first AP MLD for the above-mentioned non-AP STA.

[0313] That is, the present embodiment proposes a method in which the non-AP STA receives data in the buffer of the first AP MLD before the timer of the pending DL data set based on the roaming response frame expires. In addition, the present embodiment proposes a method in which, if all data in the buffer of the first AP MLD cannot be transmitted before the timer of the pending DL data expires, the timer of the pending DL data is extended to transmit the remaining data or the data is directly transmitted from the first AP MLD to the second AP MLD (see the description below). This has the effect of allowing the non-AP MLD to determine how long it is connected to the Serving AP MLD to receive data in the buffer and at what point it can transition to the Target AP MLD. In addition, it has the effect of minimizing data loss that may occur when the non-AP MLD transitions to the Target AP MLD.

[0314] The above roaming response frame may further include information about the presence of a waiting packet and additional information related to the waiting packet.

[0315] Based on the information on whether the above-mentioned waiting packet exists being set to a first value (e.g., 1), the above-mentioned waiting DL data may exist. Based on the information on whether the above-mentioned waiting packet exists being set to a second value (e.g., 0), the above-mentioned waiting DL data may not exist.

[0316] Additional information related to the above-mentioned waiting packet may include information about the size of the above-mentioned waiting DL data, information about the number of MSDUs (MAC Service Data Units) that have not yet been delivered, information about the last SN (Sequence Number) or last PN (Packet Number) of the MSDU, and TID (Traffic Identifier) ​​information for the MSDU.

[0317] Based on whether all data in the buffer of the first AP MLD is transmitted before the timer of the waiting DL data expires, the non-AP STA can transit from the first AP MLD to the second AP MLD. At this time, it can be confirmed that all data in the buffer of the first AP MLD is transmitted based on information about the last SN or the last PN. In addition, it can be confirmed that all data in the buffer of the first AP MLD is transmitted based on information about the size of the waiting DL data, information about the number of MSDUs not yet transmitted, and / or TID information for the MSDUs.

[0318] Additionally, the present embodiment proposes a method for transmitting remaining data depending on whether data transmission between the first and second AP MLDs is supported.

[0319] The above roaming request frame may include information on whether data transfer between the first and second AP MLDs is supported.

[0320] Based on the above information, based on supporting data transfer between the first and second AP MLDs, data remaining after the timer of the waiting DL data expires among the data in the buffer of the first AP MLD is transferred from the first AP MLD to the second AP MLD, and the remaining data can be transferred after the waiting DL data is transferred.

[0321] Based on the fact that data transfer between the first and second AP MLDs is not supported (based on the above information), data remaining after the timer of the waiting DL data expires among the data in the buffer of the first AP MLD is not transferred from the first AP MLD to the second AP MLD, the timer of the waiting DL data is extended, and the remaining data can all be transferred from the first AP MLD to the non-AP STA before the timer of the extended waiting DL data expires.

[0322] After roaming is performed from the first AP MLD to the second AP MLD based on the roaming response frame, the second AP belonging to the second AP MLD can exchange data with the non-AP STA. (Alternatively, the non-AP STA can perform roaming from the first AP MLD to the second AP MLD based on the roaming response frame. The non-AP STA can perform data exchange with the second AP belonging to the second AP MLD.)

[0323] The first AP may be referred to as Old AP (O_AP), Serving AP, or Current AP. The second AP may be referred to as New AP (N_AP) or Target AP. The first AP MLD including the first AP may be referred to as Serving AP MLD. The second AP MLD including the second AP may be referred to as Target AP MLD. MLD roaming from the Serving AP MLD to the Target AP MLD is defined as an operation of seamlessly moving from one AP to another without any disconnection between the AP and the STA within the MLD.

[0324] The first and second AP MLDs are included in a roaming-enabled group. The roaming-enabled group may be referred to as a UHR AP MLD. The first and second AP MLDs are non-collocated, but are included in the same roaming-enabled group, so roaming (or movement) from an AP in the first AP MLD to an AP in the second AP MLD is possible. The APs in the first AP MLD are collocated. The APs in the second AP MLD are also collocated.

[0325] The non-AP STA can perform roaming from the first AP to the second AP based on the roaming request frame and the roaming response frame.

[0326] In seamless roaming, there can be two types of architectures:

[0327] First, there is the MLD-based architecture. The MLD-based architecture refers to a case where all AP MLDs have a single medium access control (MAC) service access point (SAP) in a single domain called SMD (Single Mobility Domain). In other words, the MLD-based architecture has a common AP MLD upper MAC interfaced to all AP MLDs capable of performing seamless roaming. The UMAC of the UFT AP MLD controls all UMAC functions required for seamless roaming and has its own MAC SAP and unique MLD MAC address. Since the MLD-based architecture is a centralized architecture, contexts are not transferred through the DS (Distribution System), and context transfer may not exist.

[0328] Second, there is a context-passing-based architecture. This context-passing-based architecture is an improved roaming architecture that utilizes existing architectures (specifically, existing Fast Transition (FT)). This method requires context-passing between the serving AP MLD and the target AP MLD. Each AP MLD has its own MAC SAP. Each AP MLD is individually mapped to a DS, and non-AP MLDs are associated with an AP MLD. When a non-AP MLD roams from the serving AP MLD to the target AP MLD, it should roam without re-authentication and re-association. To share information among AP MLDs, AP MLDs within a single domain need to be associated with a logical entity. A security key (e.g., a single MAC address for SMD) must be shared among AP MLDs within the same single domain.

[0329] The MLD-based architecture offers virtually no delay, but requires architectural changes and is more complex to implement. Security keys are generated in the roaming MLD and shared with affiliated AP MLDs. In contrast, roaming with context transfer introduces some delay, which may worsen over other channels. However, it maintains the current architecture and offers simpler implementation. Security keys are shared over a secure channel. Therefore, the MLD-based architecture is the preferred scenario because it satisfies the goal of seamless roaming with virtually no delay. However, implementation can be challenging due to the architectural changes, and a context transfer-based architecture can be used for ease of implementation.

[0330] The first AP MLD, the second AP MLD, and the roaming-enabled group may be connected to a Distribution System (DS). For example, based on the fact that the first and second AP MLDs each have their own MAC SAPs, after the MLD roaming request frame is transmitted, the context may be transmitted to the second AP MLD via the DS.

[0331] The above context may be referred to as a parameter set negotiated between an AP and an STA (or between a non-AP MLD STA and a Serving AP MLD). The DS may be a backbone network for a wireless LAN that extends a wireless network by providing connectivity between different BSSs (Basic Service Sets).

[0332] The above roaming request frame may be defined based on a Reconfiguration Multi-link Information Element (IE). The above roaming response frame may be defined based on either a Reconfiguration Multi-link IE or a Basic Multi-link IE.

[0333] <Device Configuration>

[0334] The technical features of the present specification described above can be applied to various devices and methods. For example, the technical features of the present specification described above can be performed / supported by the devices of FIG. 1 and / or FIG. 14. For example, the technical features of the present specification described above can be applied only to a part of FIG. 1 and / or FIG. 14. For example, the technical features of the present specification described above can be implemented based on the processing chip (114, 124) of FIG. 1, or based on the processor (111, 121) and the memory (112, 122) of FIG. 1, or based on the processor (610) and the memory (620) of FIG. 14. For example, the device of the present specification transmits a roaming request frame to a first AP belonging to a first (access point) MLD (multi-link device); After the context is transferred from the first AP MLD to the second AP MLD, a roaming response frame is received from the first AP; and queued DL (downlink) data is received from the first AP MLD.

[0335] The technical features of this specification can be implemented based on a computer-readable medium (CRM). For example, the CRM proposed by this specification is at least one computer-readable recording medium containing instructions that are executed by at least one processor.

[0336] The CRM may store instructions for performing operations including the steps of: transmitting a Roaming Request frame to a first AP belonging to a first (access point) MLD (multi-link device); receiving a Roaming Response frame from the first AP after context is transferred from the first AP MLD to a second AP MLD; and receiving queued DL (downlink) data from the first AP MLD. The instructions stored in the CRM of the present specification may be executed by at least one processor. At least one processor related to the CRM of the present specification may be the processor (111, 121) or the processing chip (114, 124) of FIG. 1, or the processor (610) of FIG. 14. Meanwhile, the CRM of this specification may be the memory (112, 122) of FIG. 1, the memory (620) of FIG. 14, or a separate external memory / storage medium / disk, etc.

[0337] The technical features of this specification described above are applicable to various applications and business models. For example, the technical features described above can be applied to wireless communication in devices that support artificial intelligence (AI).

[0338] Artificial intelligence (AI) is the study of artificial intelligence or the methodologies for creating it, while machine learning (ML) defines various problems in the field of AI and studies the methodologies for solving them. Machine learning is also defined as an algorithm that improves performance on a task through consistent experience.

[0339] An artificial neural network (ANN) is a model used in machine learning. It can refer to a model with problem-solving capabilities, consisting of artificial neurons (nodes) formed by the connection of synapses to form a network. An ANN can be defined by the connection patterns between neurons in different layers, the learning process that updates model parameters, and the activation function that generates output values.

[0340] An artificial neural network may include an input layer, an output layer, and optionally one or more hidden layers. Each layer contains one or more neurons, and the artificial neural network may include synapses connecting neurons. In an artificial neural network, each neuron can output a function value of an activation function based on input signals, weights, and biases received through the synapses.

[0341] Model parameters are parameters determined through learning, including synaptic connection weights and neuron biases. Hyperparameters are parameters that must be set before learning in machine learning algorithms, including the learning rate, number of iterations, mini-batch size, and initialization function.

[0342] The goal of artificial neural network training can be seen as determining model parameters that minimize a loss function. The loss function can be used as an indicator for determining optimal model parameters during the artificial neural network training process.

[0343] Machine learning can be classified into supervised learning, unsupervised learning, and reinforcement learning depending on the learning method.

[0344] Supervised learning refers to a method for training an artificial neural network when given labels for the training data. The labels can refer to the correct answer (or output value) that the artificial neural network must infer when the training data is input to the artificial neural network. Unsupervised learning can refer to a method for training an artificial neural network when the training data is not given labels. Reinforcement learning can refer to a learning method in which an agent defined within a given environment is trained to select actions or action sequences that maximize the cumulative reward in each state.

[0345] Machine learning implemented with a deep neural network (DNN) containing multiple hidden layers among artificial neural networks is also called deep learning, and deep learning is a subset of machine learning. Hereinafter, the term "machine learning" is used to encompass deep learning.

[0346] Additionally, the above-described technical features can be applied to wireless communication of robots.

[0347] A robot can be defined as a machine that automatically performs or operates a given task based on its own capabilities. Specifically, a robot capable of perceiving its environment, making independent judgments, and performing actions can be called an intelligent robot.

[0348] Robots can be categorized into industrial, medical, household, and military applications based on their intended use or field. Robots are equipped with actuators or motors, enabling them to perform various physical actions, such as moving robot joints. Furthermore, mobile robots incorporate wheels, brakes, and propellers into their actuators, enabling them to move on the ground or fly in the air.

[0349] Additionally, the above-described technical features can be applied to devices that support extended reality.

[0350] Extended reality is a general term for virtual reality (VR), augmented reality (AR), and mixed reality (MR). VR technology presents real-world objects and backgrounds as CG images only, AR technology presents virtual CG images over images of real objects, and MR technology is a computer graphics technology that blends and combines virtual objects with the real world.

[0351] MR technology is similar to AR in that it presents both real and virtual objects simultaneously. However, while AR uses virtual objects to complement real objects, MR uses virtual and real objects on an equal footing.

[0352] XR technology can be applied to HMD (Head-Mount Display), HUD (Head-Up Display), mobile phones, tablet PCs, laptops, desktops, TVs, digital signage, etc., and devices to which XR technology is applied can be called XR devices.

[0353] The claims set forth in this specification may be combined in various ways. For example, the technical features of the method claims of this specification may be combined and implemented as a device, and the technical features of the device claims of this specification may be combined and implemented as a method. Furthermore, the technical features of the method claims and the technical features of the device claims of this specification may be combined and implemented as a device, and the technical features of the method claims and the technical features of the device claims of this specification may be combined and implemented as a method.

Claims

1. In a method performed by a non-AP (non-access point) MLD (multi-link device) in a wireless LAN system, A step in which a non-AP STA (station) belonging to the non-AP MLD transmits a roaming request frame to a first AP belonging to the first AP MLD; After the context is transferred from the first AP MLD to the second AP MLD, the non-AP STA receives a roaming response frame from the first AP; and The non-AP STA comprises a step of receiving queued DL (downlink) data from the first AP MLD, The above roaming response frame includes information about the timer of the waiting DL data, and The above-mentioned waiting DL data is data that can be transmitted before the timer of the above-mentioned waiting DL data expires among the data in the buffer of the first AP MLD for the above-mentioned non-AP STA. method.

2. In paragraph 1, The above roaming response frame further includes information about the presence of a waiting packet and additional information related to the waiting packet, Based on the information on the existence of the above-mentioned waiting packet being set to the first value, the above-mentioned waiting DL data exists, Based on the information about the existence of the above-mentioned waiting packet being set to the second value, the above-mentioned waiting DL data does not exist, Additional information related to the above-mentioned waiting packet includes information about the size of the above-mentioned waiting DL data, information about the number of MSDUs (MAC Service Data Units) that have not yet been delivered, information about the last SN (Sequence Number) or last PN (Packet Number) of the MSDU, and TID (Traffic Identifier) ​​information for the MSDU. method.

3. In paragraph 2, Based on the fact that all data in the buffer of the first AP MLD is transmitted before the timer of the waiting DL data expires, the non-AP STA transitions from the first AP MLD to the second AP MLD, Confirming that all data in the buffer of the first AP MLD is transmitted based on the information about the last SN or the last PN. method.

4. In paragraph 1, The above roaming request frame includes information on whether data transfer between the first and second AP MLDs is supported, Based on supporting data transfer between the first and second AP MLDs, data remaining after the timer of the waiting DL data expires among the data in the buffer of the first AP MLD is transferred from the first AP MLD to the second AP MLD, and the remaining data is transferred after the waiting DL data is transferred. method.

5. In paragraph 4, Based on not supporting data transfer between the first and second AP MLDs, data remaining after the timer of the waiting DL data expires among the data in the buffer of the first AP MLD is not transferred from the first AP MLD to the second AP MLD, the timer of the waiting DL data is extended, and the remaining data is all transferred from the first AP MLD to the non-AP STA before the timer of the extended waiting DL data expires. method.

6. In paragraph 1, The non-AP STA performs roaming from the first AP MLD to the second AP MLD based on the roaming response frame; and The non-AP STA further includes a step of performing data exchange with a second AP belonging to the second AP MLD, The above roaming request frame is defined based on the Reconfiguration Multi-link IE (Information Element), The above roaming response frame is defined based on the reset Multi-link IE or the basic Multi-link IE. method.

7. In a wireless LAN system, a non-AP (non-access point) MLD (multi-link device) is memory; transceiver; and A processor operatively coupled to the memory and the transceiver, the processor comprising: A non-AP STA (station) belonging to the above non-AP MLD transmits a roaming request frame to a first AP belonging to the first AP MLD; After the context is transferred from the first AP MLD to the second AP MLD, the non-AP STA receives a roaming response frame from the first AP; and The non-AP STA receives queued DL (downlink) data from the first AP MLD, The above roaming response frame includes information about the timer of the waiting DL data, and The above-mentioned waiting DL data is data that can be transmitted before the timer of the above-mentioned waiting DL data expires among the data in the buffer of the first AP MLD for the above-mentioned non-AP STA. Non-AP MLD.

8. In a method performed on a first AP (access point) MLD (multi-link device) in a wireless LAN system, A step in which a first AP belonging to the first AP MLD receives a roaming request frame from a non-AP STA (station) belonging to a non-AP MLD; After the context is transferred from the first AP MLD to the second AP MLD, the first AP transmits a roaming response frame to the non-AP STA; and The first AP comprises a step of transmitting queued DL (downlink) data to the non-AP STA, The above roaming response frame includes information about the timer of the waiting DL data, and The above-mentioned waiting DL data is data that can be transmitted before the timer of the above-mentioned waiting DL data expires among the data in the buffer of the first AP MLD for the above-mentioned non-AP STA. method.

9. In paragraph 8, The above roaming response frame further includes information about the presence of a waiting packet and additional information related to the waiting packet, Based on the information on the existence of the above-mentioned waiting packet being set to the first value, the above-mentioned waiting DL data exists, Based on the information about the existence of the above-mentioned waiting packet being set to the second value, the above-mentioned waiting DL data does not exist, Additional information related to the above-mentioned waiting packet includes information about the size of the above-mentioned waiting DL data, information about the number of MSDUs (MAC Service Data Units) that have not yet been delivered, information about the last SN (Sequence Number) or last PN (Packet Number) of the MSDU, and TID (Traffic Identifier) ​​information for the MSDU. method.

10. In paragraph 9, Based on the fact that all data in the buffer of the first AP MLD is transmitted before the timer of the waiting DL data expires, the non-AP STA transitions from the first AP MLD to the second AP MLD, Confirming that all data in the buffer of the first AP MLD is transmitted based on the information about the last SN or the last PN. method.

11. In paragraph 8, The above roaming request frame includes information on whether data transfer between the first and second AP MLDs is supported, Based on supporting data transfer between the first and second AP MLDs, data remaining after the timer of the waiting DL data expires among the data in the buffer of the first AP MLD is transferred from the first AP MLD to the second AP MLD, and the remaining data is transferred after the waiting DL data is transferred. method.

12. In paragraph 11, Based on not supporting data transfer between the first and second AP MLDs, data remaining after the timer of the waiting DL data expires among the data in the buffer of the first AP MLD is not transferred from the first AP MLD to the second AP MLD, the timer of the waiting DL data is extended, and the remaining data is all transferred from the first AP MLD to the non-AP STA before the timer of the extended waiting DL data expires. method.

13. In paragraph 8, After roaming is performed from the first AP MLD to the second AP MLD based on the roaming response frame, The second AP belonging to the second AP MLD further includes a step of performing data exchange with the non-AP STA. The above roaming request frame is defined based on the Reconfiguration Multi-link IE (Information Element), The above roaming response frame is defined based on the reset Multi-link IE or the basic Multi-link IE. method.

14. In a wireless LAN system, the first AP (access point) MLD (multi-link device) memory; transceiver; and A processor operatively coupled to the memory and the transceiver, the processor comprising: The first AP belonging to the first AP MLD receives a roaming request frame from a non-AP STA (station) belonging to the non-AP MLD; After the context is transferred from the first AP MLD to the second AP MLD, the first AP transmits a roaming response frame to the non-AP STA; and The above first AP transmits queued DL (downlink) data to the non-AP STA, The above roaming response frame includes information about the timer of the waiting DL data, and The above-mentioned waiting DL data is data that can be transmitted before the timer of the above-mentioned waiting DL data expires among the data in the buffer of the first AP MLD for the above-mentioned non-AP STA. 1st AP MLD.

15. At least one computer-readable medium containing instructions based on being executed by at least one processor, A step of transmitting a roaming request frame to the first AP belonging to the first (access point) MLD (multi-link device); A step of receiving a roaming response frame from the first AP after the context is transferred from the first AP MLD to the second AP MLD; and A step of receiving queued DL (downlink) data from the first AP MLD, The above roaming response frame includes information about the timer of the waiting DL data, and The above-mentioned waiting DL data is data that can be transmitted before the timer of the above-mentioned waiting DL data expires among the data in the buffer of the first AP MLD for the above-mentioned non-AP STA. Recording medium.

16. In a wireless LAN system, in the device, memory; and A processor operatively coupled to the memory, the processor comprising: Transmit a roaming request frame to the first AP belonging to the first (access point) MLD (multi-link device); After the context is transferred from the first AP MLD to the second AP MLD, a roaming response frame is received from the first AP; and Receive queued DL (downlink) data from the above first AP MLD, The above roaming response frame includes information about the timer of the waiting DL data, and The above-mentioned waiting DL data is data that can be transmitted before the timer of the above-mentioned waiting DL data expires among the data in the buffer of the first AP MLD for the above-mentioned non-AP STA. device.

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