Method executed by access point multi-link device and access point multi-link device

Abstract

The invention relates to a method executed by an access point multilink device and the access point multilink device. According to various embodiments, a multilink device (MLD) operating in a plurality of links may receive a PPDU through a first link among the plurality of links. The PPDU may include a first information field related to a second link different from the first link. The first information field related to the second link may include a second information field related to a link identifier of the second link and a third information field related to whether all element information about the second link is included in the PPDU.

Description

[0001] This application is a divisional application of the original invention patent application with application number 202180035144.9 (International application number: PCT / KR2021 / 003221, application date: March 16, 2021, invention name: Technology for performing multi-link communication in a wireless communication system). Technical Field

[0002] The present specification relates to a technology for performing multi-link communication in a wireless local area network (WLAN) system, and more particularly, to a method for transmitting information about links in multi-link communication and a device supporting the method. Background Art

[0003] Wireless local area networks (WLANs) have been enhanced in various ways. For example, the IEEE 802.11ax standard proposes an enhanced communication environment using orthogonal frequency division multiple access (OFDMA) and downlink multi-user multiple input multiple output (DL MU MIMO) schemes.

[0004] This specification proposes technical features that can be used in new communication standards. For example, the new communication standard may be the Extremely High Throughput (EHT) standard currently under discussion. The EHT standard may use newly proposed increased bandwidth, an enhanced PHY layer protocol data unit (PPDU) structure, enhanced sequences, a hybrid automatic repeat request (HARQ) scheme, and the like. The EHT standard may be referred to as the IEEE 802.11be standard. Summary of the Invention

[0005] Technical issues

[0006] In the EHT standard, wide bandwidth (eg, 160 / 320 MHz), 16 streams, and / or multi-link (or multi-band) operations may be used to support high throughput and high data rates.

[0007] In the EHT standard, a device that supports multiple links (i.e., a multi-link device) can operate in multiple links. A multi-link device needs to send element information about a second link via a first link. Therefore, a technical feature may be required for a multi-link device to receive information about different links.

[0008] Technical Solution

[0009] According to various embodiments, a multi-link device (MLD) operating in multiple links may perform: an operation of receiving a physical layer protocol data unit (PPDU) through a first link among the multiple links, the PPDU including a first information field related to a second link among the multiple links that is different from the first link, and the first information field related to the second link includes a second information field related to a link identifier of the second link and a third information field related to whether complete element information for the second link is included in the PPDU; and an operation of obtaining complete element information for the second link based on the second information field and the third information field.

[0010] Technical Effects

[0011] STAs included in a multi-link device can also send information about another STA (or link) in the multi-link device through a link. Therefore, the overhead of frame exchange can be reduced. In addition, the link usage efficiency of the STA can be increased and power consumption can be reduced.

[0012] In addition, the multi-link device may receive a PPDU including element information about the second link via the first link. The PPDU may include an information field for indicating whether the complete element information for the second link is included in the PPDU. Therefore, the multi-link device may determine whether the complete element information for the second link is included in the received PPDU and, based on this, may obtain / identify the complete element information for the second link. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Examples of the transmitting device and / or receiving device of this specification are shown.

[0014] Figure 2 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

[0015] Figure 3 A general link establishment process is shown.

[0016] Figure 4 An example of PPDU used in the IEEE standard is shown.

[0017] Figure 5 The operation based on UL-MU is shown.

[0018] Figure 6 An example of a trigger frame is shown.

[0019] Figure 7 An example of the common information field of a trigger frame is shown.

[0020] Figure 8 An example of subfields included in the per-user information field is shown.

[0021] Figure 9 An example of channels used / supported / defined in the 2.4 GHz band is shown.

[0022] Figure 10 Shows an example of channels used / supported / defined in the 5 GHz band.

[0023] Figure 11 Shown are examples of channels used / supported / defined in the 6 GHz band.

[0024] Figure 12 An example of HE-PPDU is shown.

[0025] Figure 13 An example of PPDU used in this specification is shown.

[0026] Figure 14 An example of a modified transmitting device and / or receiving device of the present specification is shown.

[0027] Figure 15 An example of channel bonding is shown.

[0028] Figure 16 An example of the structure of a non-AP MLD is shown.

[0029] Figure 17 This shows an example of processing connections by AP MLD and non-AP MLD through link establishment.

[0030] Figure 18 Shows an example of a link change or reconnection.

[0031] Figure 19 A specific example of link change or reconnection is shown.

[0032] Figure 20 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0033] Figure 21 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0034] Figure 22 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0035] Figure 23 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0036] Figure 24 A specific example of the STA ratio per link is shown.

[0037] Figure 25 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0038] Figure 26 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0039] Figure 27 An example of an MLD structure supporting anchor links is shown.

[0040] Figure 28 An example of a situation where an anchor link change or reconnection is required is shown.

[0041] Figure 29 The operations of AP MLD and non-AP MLD for anchor link change or reconnection are shown.

[0042] Figure 30 and Figure 31 A specific example of an element showing anchor link reconnection.

[0043] Figure 32 is a flow chart illustrating the operation of a multi-link device.

[0044] Figure 33 is a flowchart illustrating the operation of an AP multi-link device. DETAILED DESCRIPTION

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

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

[0047] In this specification, "at least one of A and B" may mean "only A", "only B", or "both A and B". In addition, in this specification, the expression "at least one of A or B" or "at least one of A and / or B" may be interpreted as "at least one of A and B".

[0048] In addition, in this specification, "at least one of A, B, and C" may mean "only A," "only B," "only C," or "any combination of A, B, and C." In addition, "at least one of A, B, or C" or "at least one of A, B, and / or C" may mean "at least one of A, B, and C."

[0049] In addition, brackets used in this specification may indicate "for example." Specifically, when indicated as "control information (EHT-signal)," it may indicate that "EHT-signal" is proposed as an example of "control information." In other words, "control information" in this specification is not limited to "EHT-signal," and "EHT-signal" may be proposed as an example of "control information." In addition, when indicated as "control information (i.e., EHT signal)," it may also mean that "EHT signal" is proposed as an example of "control information."

[0050] Technical features described separately in one drawing of this specification may be implemented separately or simultaneously.

[0051] 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, this specification can be applied to IEEE 802.11a / g / n / ac standards or IEEE 802.11ax standards. In addition, this specification can also be applied to the newly proposed EHT standard or IEEE 802.11be standard. In addition, the examples of this specification can also be applied to new WLAN standards enhanced from the EHT standard or the IEEE 802.11be standard. In addition, the examples of this specification can be applied to mobile communication systems. For example, it can be applied to long term evolution (LTE) based on the 3rd Generation Partnership Project (3GPP) standard and mobile communication systems based on the evolution of LTE. In addition, the examples of this specification can be applied to communication systems based on the 5G NR standard of the 3GPP standard.

[0052] Hereinafter, in order to describe the technical features of the present specification, technical features applicable to the present specification will be described.

[0053] Figure 1 Examples of the transmitting device and / or receiving device of this specification are shown.

[0054] exist Figure 1 In the example, various technical features described below can be performed. Figure 1At least one station (STA) is involved. For example, the STAs 110 and 120 in this specification may also be referred to by various terms such as mobile terminals, wireless devices, wireless transmit / receive units (WTRUs), user equipment (UEs), mobile stations (MSs), mobile subscriber units, or simply users. The STAs 110 and 120 in this specification may also be referred to by various terms such as networks, base stations, Node Bs, access points (APs), repeaters, routers, and relays. The STAs 110 and 120 in this specification may also be referred to by various names such as receiving devices, transmitting devices, receiving STAs, transmitting STAs, receiving devices, and transmitting devices.

[0055] For example, the STAs 110 and 120 may function as APs or non-APs. That is, the STAs 110 and 120 of this specification may function as APs and / or non-APs.

[0056] In addition to the IEEE 802.11 standard, the STAs 110 and 120 of this specification can support various communication standards. For example, they can support communication standards based on 3GPP standards (e.g., LTE, LTE-A, 5G NR standards). In addition, the STAs of this specification can be implemented as various devices such as mobile phones, vehicles, and personal computers. In addition, the STAs of this specification can support communication for various communication services such as voice calls, video calls, data communications, and self-driving (autonomous driving).

[0057] The STAs 110 and 120 of the present specification may include a medium access control (MAC) compliant with the IEEE 802.11 standard and a physical layer interface for a radio medium.

[0058] The following will refer to Figure 1 Sub-figure (a) of FIG. 1 depicts STAs 110 and 120 .

[0059] The first STA 110 may include a processor 111, a memory 112, and a transceiver 113. The illustrated processor, memory, and transceiver may be individually implemented as separate chips, or at least two blocks / functions may be implemented by a single chip.

[0060] The transceiver 113 of the first STA performs signal transmission / reception operations, and specifically, can transmit / receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0061] For example, the first STA 110 may perform operations expected by the AP. For example, the AP's processor 111 may receive signals via the transceiver 113, process the received (RX) signals, generate transmitted (TX) signals, and provide control over signal transmission. The AP's memory 112 may store signals received via the transceiver 113 (e.g., RX signals) and may store signals to be transmitted via the transceiver (e.g., TX signals).

[0062] For example, the second STA 120 can perform operations expected by a non-AP STA. For example, the non-AP transceiver 123 can perform signal transmission / reception operations. Specifically, it can transmit / receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be packets, etc.).

[0063] For example, the processor 121 of the non-AP STA may receive a signal through the transceiver 123, process the RX signal, generate a TX signal, and provide control for signal transmission. The memory 122 of the non-AP STA may store signals (e.g., RX signals) received through the transceiver 123 and may store signals (e.g., TX signals) to be transmitted through the transceiver.

[0064] For example, the operation of a device indicated as an AP in the following description 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 the AP may be controlled by the processor 111 of the first STA 110, and related signals may be transmitted or received through the transceiver 113 controlled by the processor 111 of the first STA 110. In addition, control information related to the operation of the AP or the AP's TX / RX signals may be stored in the memory 112 of the first STA 110. In addition, if the second STA 120 is an AP, the operation of the device indicated as the AP may be controlled by the processor 121 of the second STA 120, and related signals may be transmitted or received through the 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 AP's TX / RX signals may be stored in the memory 122 of the second STA 120.

[0065] For example, in the following description, the operation of a device indicated as a non-AP (or user STA) may be performed in the first 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 the non-AP may be controlled by the processor 121 of the second STA 120, and related signals may be transmitted or received through the 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 TX / RX signal of the non-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 the device indicated as the non-AP may be controlled by the processor 111 of the first STA 110, and related signals may be transmitted or received through the transceiver 113 controlled by the processor 111 of the first STA 110. In addition, control information related to the operation of the non-AP or the TX / RX signal of the non-AP may be stored in the memory 112 of the first STA 110.

[0066] In the following description, devices referred to 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. may refer to Figure 1 For example, a device indicated as (transmitting / receiving) STA, a first STA, a second STA, STA1, STA2, an AP, a first AP, a second AP, AP1, AP2, a (transmitting / receiving) terminal, a (transmitting / receiving) device, a (transmitting / receiving) apparatus, a network, etc. (but without specific reference numerals) may refer to Figure 1 For example, in the following example, the operations of various STAs transmitting / receiving signals (eg, PPDU) may be performed in Figure 1 In addition, in the following examples, the operations of various STAs generating TX / RX signals or performing data processing and calculations in advance for TX / RX signals may be performed in the transceiver 113 and 123. Figure 111 and 121. For example, examples of operations for generating TX / RX signals or performing data processing and calculation in advance may include: 1) determining / obtaining / configuring / calculating / decoding / encoding bit information of subfields (SIG, STF, LTF, Data) included in the PPDU; 2) determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) for the subfields (SIG, STF, LTF, Data) included in the PPDU; 3) determining / configuring / obtaining specific sequences (e.g., pilot sequences, STF / LTF sequences, additional sequences applied to SIG) for the subfields (SIG, STF, LTF, Data) included in the PPDU; 4) power control operations and / or power saving operations applied to STAs; and 5) operations related to determining / obtaining / configuring / decoding / encoding of ACK signals. In addition, in the following examples, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs to determine / obtain / configure / calculate / decode / encode TX / RX signals may be stored in Figure 1 in memories 112 and 122 .

[0067] Figure 1 The aforementioned device / STA of sub-graph (a) can be as follows Figure 1 In the following, we will modify the Figure 1 Sub-figure (b) of FIG. 1 is used to describe STA 110 and STA 120 of this specification.

[0068] For example, Figure 1 The transceivers 113 and 123 shown in the sub-diagram (b) can perform the same Figure 1 The same functions as the aforementioned transceiver shown in sub-figure (a) of FIG. Figure 1 The processing chips 114 and 124 shown in sub-figure (b) may include processors 111 and 121 and memories 112 and 122 . Figure 1 The processors 111 and 121 and the memories 112 and 122 shown in the sub-diagram (b) of FIG. Figure 1 The aforementioned processors 111 and 121 and memories 112 and 122 shown in sub-Figure (a) have the same functions.

[0069] 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 unit, transmitting unit, receiving STA, transmitting STA, receiving device, transmitting device, receiving apparatus and / or transmitting apparatus described below may mean Figure 1 STAs 110 and 120 shown in sub-figures (a) / (b) of FIG. 110 and 120, or may mean Figure 1 The processing chips 114 and 124 shown in the sub-figure (b) of FIG. In other words, the technical features of this specification can be Figure 1 110 and 120 shown in the sub-figures (a) / (b) of FIG. 110, or may be performed only in the STA110 and 120 shown in the sub-figures (a) / (b) of FIG. Figure 1 The processing chips 114 and 124 shown in the sub-figure (b) of FIG. Figure 1 For example, the technical feature of sending a control signal from a STA can be understood as the transceiver 113 and 123 shown in the sub-figure (a) / (b) of FIG. Figure 1 The transceiver 113 shown in the sub-figures (a) / (b) of FIG. Figure 1 Alternatively, the technical feature of the control signal generated by the processors 111 and 121 illustrated in the sub-figures (a) / (b) of FIG. 1 may be understood as the technical feature of the control signal generated by the processors 111 and 121. Figure 1 The technical features of the processing chips 114 and 124 shown in sub-figure (b) of FIG. 10 are those for generating control signals to be transmitted to the transceivers 113 and 123 .

[0070] For example, the technical feature of receiving the control signal by the receiving STA can be understood as Figure 1 Alternatively, the technical feature of the receiving STA receiving the control signal can be understood as the technical feature of the receiving STA receiving the control signal through Figure 1 The processors 111 and 121 shown in the sub-diagram (a) of Figure 1 Alternatively, the technical feature of the receiving STA receiving the control signal can be understood as the technical feature of the control signal received by the transceiver 113 and 123 shown in the sub-figure (a) of FIG. Figure 1 The processing chips 114 and 124 shown in the sub-graph (b) of FIG. Figure 1 Technical characteristics of the control signals received in transceivers 113 and 123 shown in sub-figure (b).

[0071] Reference Figure 1 , software codes 115 and 125 may be included in memories 112 and 122. The software codes 115 and 126 may include instructions for controlling operations of the processors 111 and 121. The software codes 115 and 125 may be included as various programming languages.

[0072] Figure 1 The processors 111 and 121 or the processing chips 114 and 124 may include application specific integrated circuits (ASICs), other chipsets, logic circuits and / or data processing devices. The processor may be an application processor (AP). For example, Figure 1 The processors 111 and 121 or the processing chips 114 and 124 may include at least one of the following: a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modulator and demodulator (modem). For example, Figure 1 The processors 111 and 121 or the processing chips 114 and 124 may be composed of SNAPDRAGONTM processor series manufactured by EXYNOSTM processor series manufactured by Processor family manufactured by HELIOTM processor series manufactured by The ATOMTM processor series manufactured by or enhanced from these processors.

[0073] In this specification, the uplink may refer to a link for communication from a non-AP STA to an SP STA, and uplink PPDUs / packets / signals, etc. may be transmitted through the uplink. In addition, in this specification, the downlink may refer to a link for communication from an AP STA to a non-AP STA, and downlink PPDUs / packets / signals, etc. may be transmitted through the downlink.

[0074] Figure 2 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

[0075] Figure 2 The upper portion of shows the structure of an infrastructure Basic Service Set (BSS) of the Institute of Electrical and Electronics Engineers (IEEE) 802.11.

[0076] Reference Figure 2 The wireless LAN system may include one or more infrastructure BSSs 200 and 205 (hereinafter referred to as BSSs). BSSs 200 and 205, which are a collection of APs and STAs (e.g., access point (AP) 225 and station (STA1) 200-1) that have successfully synchronized to communicate with each other, do not represent a specific area. BSS 205 may include one or more STAs 205-1 and 205-2 that can join one AP 230.

[0077] The BSS may include at least one STA, an AP providing a distributed service, and a distribution system (DS) 210 connecting a plurality of APs.

[0078] The distribution system 210 may implement an extended service set (ESS) 240 that is extended by connecting a plurality of BSSs 200 and 205. The ESS 240 may be used as a term indicating one network configured by connecting one or more APs 225 or 230 via the distribution system 210. APs included in one ESS 240 may have the same service set identifier (SSID).

[0079] The portal 220 may serve as a bridge connecting a wireless LAN network (IEEE 802.11) and another network (eg, 802.X).

[0080] exist Figure 2 In the BSS shown in the upper portion of FIG, a network between APs 225 and 230 and a network between APs 225 and 230 and STAs 200-1, 205-1, and 205-2 can be implemented. However, a network can be configured between STAs to perform communication even without APs 225 and 230. A network that performs communication by configuring a network between STAs even without APs 225 and 230 is defined as an ad hoc network or an independent basic service set (IBSS).

[0081] Figure 2 The lower part of FIG shows a conceptual diagram showing an IBSS.

[0082] Reference Figure 2 The IBSS is a BSS operating in self-organizing mode. Because the IBSS does not include an access point (AP), there is no centralized management entity that performs management functions. Specifically, in the IBSS, STAs 250-1, 250-2, 250-3, 255-4, and 255-5 are managed in a distributed manner. In the IBSS, all STAs 250-1, 250-2, 250-3, 255-4, and 255-5 may be mobile STAs and are not allowed to access the DS, forming a self-contained network.

[0083] Figure 3 A general link establishment process is shown.

[0084] In S310, the STA may perform a network discovery operation. This may include a scanning operation. Specifically, to access a network, the STA must discover participating networks. 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.

[0085] Figure 3The network discovery operation including active scanning processing is shown. In active scanning, the STA performing the scan sends a probe request frame and waits for a response to the probe request frame in order to identify which AP is around while moving to the channel. The responder sends a probe response frame to the STA that has sent the probe request frame as a response to the probe request frame. Here, the responder can be the STA that sent the last beacon frame in the BSS of the channel being scanned. In the BSS, since the AP sends the beacon frame, the AP is the responder. In the IBSS, since the STAs in the IBSS take turns sending beacon frames, the responder is not fixed. For example, when the STA sends a probe request frame via channel 1 and receives a probe response frame via channel 1, the STA may store the BSS-related information included in the received probe response frame, may move to the next channel (e.g., channel 2), and may perform scanning by the same method (e.g., sending a probe request and receiving a probe response via channel 2).

[0086] although Figure 3 Not shown in the figure, scanning can be performed using a passive scanning method. In passive scanning, the STA performing the scan can wait for a beacon frame while moving to a channel. The beacon frame is one of the management frames in IEEE 802.11 and is periodically transmitted to indicate the existence of a wireless network and enable the STA performing the scan to find and join the wireless network. In a BSS, the AP is used to periodically transmit beacon frames. In an IBSS, the STAs in the IBSS take turns transmitting beacon frames. Upon receiving the beacon frame, the STA performing the scan stores information related to the BSS included in the beacon frame and records beacon frame information in each channel while moving to another channel. The STA that receives the beacon frame can store the BSS-related information included in the received beacon frame, can move to the next channel, and can perform scanning in the next channel using the same method.

[0087] After discovering the network, the STA may perform an authentication process in S320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the subsequent security establishment operation in S340. The authentication process in S320 may include a process in which the STA sends an authentication request frame to the AP, and the AP sends an authentication response frame to the STA in response. The authentication frames used for authentication requests / responses are management frames.

[0088] The authentication frame may include information related to an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a robust security network (RSN), and a limited round robin group.

[0089] The STA may send an authentication request frame to the AP. The AP may determine whether to allow authentication of the STA based on the information included in the received authentication request frame. The AP may provide the authentication process result to the STA via an authentication response frame.

[0090] When the STA is successfully authenticated, the STA may perform an association process in S330. The association process includes a process in which the STA sends an association request frame to the AP, and the AP sends an association response frame to the STA in response. For example, the association request frame may include information related to various capabilities, a beacon listening interval, a service set identifier (SSID), supported rates, supported channels, RSN, mobility domain, supported operation category, a traffic indication map (TIM) broadcast request, and interworking service capabilities. For example, the association response frame may include information related to various capabilities, a status code, an association ID (AID), supported rates, an enhanced distributed channel access (EDCA) parameter set, a received channel power indicator (RCPI), a received signal-to-noise ratio indicator (RSNI), a mobility domain, a timeout interval (association recovery time), overlapping BSS scan parameters, a TIM broadcast response, and a QoS map.

[0091] In S340, the STA may perform a security establishment process. The security establishment process in S340 may include a process of establishing a private key through a four-way handshake (eg, through an Extensible Authentication Protocol over LAN (EAPOL) frame).

[0092] Figure 4 An example of PPDU used in the IEEE standard is shown.

[0093] As shown, various types of PHY protocol data units (PPDUs) are used in the IEEE a / g / n / ac standards. Specifically, LTF and STF include training signals, SIG-A and SIG-B include control information for receiving STAs, and the data field includes user data corresponding to PSDU (MAC PDU / aggregated MAC PDU).

[0094] Figure 4 An example of HE PPDU according to IEEE 802.11ax is also shown. Figure 4 The HE PPDU is an exemplary PPDU for multiple users. The HE-SIG-B may be included only in the PPDU for multiple users and may be omitted in the PPDU for a single user.

[0095] like Figure 4As shown, the HE-PPDU for multiple users (MUs) may include a legacy short training field (L-STF), a legacy long training field (L-LTF), a legacy signal (L-SIG), a high-efficiency signal A (HE-SIG A), a high-efficiency signal B (HE-SIG B), a high-efficiency short training field (HE-STF), a high-efficiency long training field (HE-LTF), a data field (alternatively, a MAC payload), and a packet extension (PE) field. Each field may be transmitted within the time period shown (i.e., 4 or 8 μs).

[0096] The following describes the resource unit (RU) used for the PPDU. An RU can include multiple subcarriers (or tones). An RU can be used to transmit signals to multiple STAs using OFDMA. Furthermore, an RU can be defined as transmitting signals to a single STA. An RU can be used for the STF, LTF, data field, and more.

[0097] Figure 5 UL-MU-based operations are shown. As shown, a transmitting STA (e.g., an AP) may perform channel access through contention (e.g., a backoff operation) and may transmit a trigger frame 530. That is, the transmitting STA may transmit a PPDU including the trigger frame 530. Upon receiving the PPDU including the trigger frame, a trigger-based (TB) PPDU is transmitted after a delay corresponding to SIFS.

[0098] The TB PPDUs 541 and 542 may be transmitted at the same time period and may be transmitted from a plurality of STAs (eg, user STAs) having the AID indicated in the trigger frame 530. The ACK frame 550 for the TB PPDU may be implemented in various forms.

[0099] Reference Figures 6 to 8 Describes the specific characteristics of the trigger frame. Even when using UL-MU communication, an Orthogonal Frequency Division Multiple Access (OFDMA) scheme or a MU-MIMO scheme may be used, and OFDMA and MU-MIMO schemes may be used simultaneously.

[0100] Figure 6 An example of a trigger frame is shown. Figure 6 The trigger frame allocates resources for uplink multi-user (MU) transmission and may be sent, for example, from an AP. The trigger frame may be configured by a MAC frame and may be included in a PPDU.

[0101] Figure 6 The various fields shown may be partially omitted, and another field may be added. In addition, the length of each field may be changed to be different from that shown in the figure.

[0102] Figure 6The frame control field 610 may include information related to the MAC protocol version and additional control information. The duration field 620 may include time information configured by the NAV or information related to an identifier (eg, AID) of the STA.

[0103] In addition, the RA field 630 may include the address information of the receiving STA of the corresponding trigger frame and may optionally be omitted. The TA field 640 may include the address information of the STA (e.g., AP) that sends the corresponding trigger frame. The public information field 650 includes public control information applied to the receiving STA that receives the corresponding trigger frame. For example, it may include a field indicating the length of the L-SIG field of the uplink PPDU sent in response to the corresponding trigger frame or information for controlling the content of the SIG-A field (i.e., HE-SIG-A field) of the uplink PPDU sent in response to the corresponding trigger frame. In addition, as public control information, it may include information related to the length of the CP of the uplink PPDU sent in response to the corresponding trigger frame or information related to the length of the LTF field.

[0104] In addition, it is preferred to include Figure 6 The number of STAs receiving the trigger frame corresponds to the per-user information fields 660#1 to 660#N. The per-user information field may also be referred to as an "allocation field."

[0105] in addition, Figure 6 The trigger frame may include a padding field 670 and a frame check sequence field 680.

[0106] Figure 6 Each of the illustrated per-user information fields 660#1 through 660#N may include a plurality of subfields.

[0107] Figure 7 An example of the common information field of a trigger frame is shown. Figure 7 The subfields of the FIFO may be partially omitted, and additional subfields may be added. In addition, the length of each subfield shown may be changed.

[0108] The length field 710 shown has the same value as the length field of the L-SIG field of the uplink PPDU sent in response to the corresponding trigger frame, and the length field of the L-SIG field of the uplink PPDU indicates the length of the uplink PPDU. As a result, the length field 710 of the trigger frame can be used to indicate the length of the corresponding uplink PPDU.

[0109] In addition, the tandem identifier field 720 indicates whether tandem operation is performed. Tandem operation means that downlink MU transmission and uplink MU transmission are performed together in the same TXOP. In other words, it means that downlink MU transmission is performed, and then uplink MU transmission is performed after a preset time (e.g., SIFS). During tandem operation, only one transmitting device (e.g., an AP) can perform downlink communication, and multiple transmitting devices (e.g., non-APs) can perform uplink communication.

[0110] The CS request field 730 indicates whether a wireless medium status or NAV, etc. must be considered in case a receiving apparatus that has received a corresponding trigger frame transmits a corresponding uplink PPDU.

[0111] The HE-SIG-A information field 740 may include information for controlling the content of the SIG-A field (ie, HE-SIG-A field) of the uplink PPDU in response to the corresponding trigger frame.

[0112] The CP and LTF type field 750 may include information about the CP length and LTF length of the uplink PPDU sent in response to the corresponding trigger frame. The trigger type field 760 may indicate the purpose of using the corresponding trigger frame, such as a typical trigger, a beamforming trigger, a request for block ACK / NACK, etc.

[0113] It can be assumed that the trigger type field 760 of the trigger frame in this specification indicates a basic type of trigger frame for typical triggering. For example, the basic type of trigger frame can be referred to as a basic trigger frame.

[0114] Figure 8 An example of subfields included in the per-user information field is shown. Figure 8 The user information field 800 can be understood as the above reference Figure 11 Any of the mentioned per-user information fields 1160#1 to 1160#N. Included in Figure 8 The subfields in the user information field 800 may be partially omitted, and additional subfields may be added. In addition, the length of each subfield shown may be changed.

[0115] Figure 8 The user identifier field 810 indicates an identifier of the STA (ie, the receiving STA) corresponding to the per-user information. An example of the identifier may be all or part of the association identifier (AID) value of the receiving STA.

[0116] In addition, the RU allocation field 820 may be included. That is, when the receiving STA identified by the user identifier field 810 transmits a TB PPDU in response to the trigger frame, the TB PPDU is transmitted through the RU indicated by the RU allocation field 820.

[0117] Figure 8 The subfield of may include a coding type field 830. The coding type field 830 may indicate the coding type of the TB PPDU. For example, when BCC coding is applied to the TB PPDU, the coding type field 830 may be set to "1", and when LDPC coding is applied, the coding type field 830 may be set to "0".

[0118] in addition, Figure 8 The subfields of the 840 may include an MCS field 840. The MCS field 840 may indicate the MCS scheme applied to the TB PPDU. For example, when BCC coding is applied to the TB PPDU, the coding type field 830 may be set to "1", and when LDPC coding is applied, the coding type field 830 may be set to "0".

[0119] Figure 9 Shown are examples of channels used / supported / defined in the 2.4 GHz band.

[0120] The 2.4 GHz band may be referred to as other terms such as a first frequency band. Additionally, the 2.4 GHz band may refer to a frequency domain that uses / supports / defines channels with center frequencies close to 2.4 GHz (eg, channels with center frequencies within 2.4 to 2.5 GHz).

[0121] Multiple 20 MHz channels may be included in the 2.4 GHz frequency band. The 20 MHz channels within the 2.4 GHz band may have multiple channel indices (e.g., index 1 to index 14). For example, the center frequency of a 20 MHz channel assigned with channel index 1 may be 2.412 GHz, the center frequency of a 20 MHz channel assigned with channel index 2 may be 2.417 GHz, and the center frequency of a 20 MHz channel assigned with channel index N may be (2.407+0.005*N) GHz. The channel index may be referred to by various terms such as channel number. The specific values ​​of the channel index and center frequency may vary.

[0122] Figure 9 An example is given of four channels within the 2.4 GHz frequency band. Each of the first frequency domain 910 to the fourth frequency domain 940 shown herein may include one channel. For example, the first frequency domain 910 may include channel 1 (a 20 MHz channel with index 1). In this case, the center frequency of channel 1 may be set to 2412 MHz. The second frequency domain 920 may include channel 6. In this case, the center frequency of channel 6 may be set to 2437 MHz. The third frequency domain 930 may include channel 11. In this case, the center frequency of channel 11 may be set to 2462 MHz. The fourth frequency domain 940 may include channel 14. In this case, the center frequency of channel 14 may be set to 2484 MHz.

[0123] Figure 10 Shows examples of channels used / supported / defined in the 5 GHz band.

[0124] The 5 GHz band may be referred to by other terms such as a second frequency band. The 5 GHz band may refer to a frequency domain that uses / supports / defines channels with a center frequency greater than or equal to 5 GHz and less than 6 GHz (or less than 5.9 GHz). Alternatively, the 5 GHz band may include multiple channels between 4.5 GHz and 5.5 GHz. Figure 10 The specific values ​​shown may vary.

[0125] 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 domains referred to as UNII Mid and UNII-2 Extended. UNII-3 may be referred to as UNII Upper.

[0126] Multiple channels can be configured within the 5 GHz frequency band, and the bandwidth of each channel can be set to various values, 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 using a 40 MHz frequency domain. The 5170 MHz to 5330 MHz frequency domain / range can be divided into two channels using an 80 MHz frequency domain. Alternatively, the 5170 MHz to 5330 MHz frequency domain / range can be divided into one channel using a 160 MHz frequency domain.

[0127] Figure 11 Shows examples of channels used / supported / defined in the 6 GHz band.

[0128] The 6 GHz frequency band may be referred to by other terms such as a third frequency band, etc. The 6 GHz frequency band may mean a frequency domain that uses / supports / defines channels having a center frequency greater than or equal to 5.9 GHz. Figure 11 The specific values ​​shown may vary.

[0129] For example, Figure 11 The 20MHz channel can be defined starting from 5.940GHz. Figure 11 Among the 20 MHz channels, the leftmost channel may have an index of 1 (or channel index, channel number, etc.), and 5.945 GHz may be assigned as the center frequency. That is, the center frequency of the channel of index N may be determined to be (5.940+0.005*N) GHz.

[0130] therefore, Figure 11 The indices (or channel numbers) of the 2 MHz channels can be 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, 197, 201, 205, 209, 213, 217, 221, 225, 229, 233. In addition, according to the above (5.940+0.005*N)GHz rule, Figure 11 The indices of the 40 MHz channels 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.

[0131] Despite Figure 11 20, 40, 80, and 160 MHz channels are shown in the example of , but a 240 MHz channel or a 320 MHz channel may be additionally added.

[0132] Hereinafter, the PPDU transmitted / received in the STA of this specification will be described.

[0133] Figure 12 An example of HE-PPDU is shown.

[0134] The illustrated L-STF 1200 may include a short training Orthogonal Frequency Division Multiplexing (OFDM) symbol. The L-STF 1200 may be used for frame detection, automatic gain control (AGC), diversity detection, and coarse frequency / time synchronization.

[0135] The L-LTF 1210 may include a long training Orthogonal Frequency Division Multiplexing (OFDM) symbol. The L-LTF 1210 may be used for fine frequency / time synchronization and channel estimation.

[0136] L-SIG 1220 may be used to transmit control information. L-SIG 1220 may include information related to data transmission rate and data length. Furthermore, L-SIG 1220 may be transmitted repeatedly. That is, L-SIG 1220 may be configured in a repetitive format (e.g., referred to as R-LSIG).

[0137] HE-SIG-A 1230 may include control information common to the receiving stations.

[0138] Specifically, HE-SIG-A1230 may include information related to the following: 1) DL / UL indicator; 2) BSS color field as an identifier of the BSS; 3) a field indicating the remaining time of the current TXOP duration / cycle; 4) a bandwidth field indicating whether it is 20, 40, 80, 160, or 80+80 MHz; 5) a field indicating the MCS scheme applied to HE-SIG-B; 6) an indication field indicating whether dual subcarrier modulation (DCM) is applied to the HE-SIG-B of the MCS; 7) a field indicating the number of symbols used for HE-SIG-B; 8) a field indicating whether HE-SIG-B is generated on the full / entire frequency band; 9) a field indicating the number of symbols of HE-LTF; 10) a field indicating the length of HE-LTF and the CP length; 11) a field indicating whether there are additional OFDM symbols for LDPC encoding; 12) a field indicating control information about packet extension (PE); and / or 13) a field indicating information related to the CRC field of HE-SIG-A, etc. At least one field of the HE-SIG-A may be omitted or changed. In addition, in environments other than the multi-user (MU) environment, some fields may be added or omitted.

[0139] In addition, HE-SIG-A 1230 may consist of two parts: HE-SIG-A1 and HE-SIG-A2. HE-SIG-A1 and HE-SIG-A2 included in the HE-SIG-A may be defined according to the following format structure (field) based on the corresponding PPDU. First, the HE-SIG-A field of the HE SUPPDU may be defined as follows.

[0140] [Table 1]

[0141]

[0142] [Table 2]

[0143]

[0144] [Table 3]

[0145]

[0146]

[0147] [Table 4]

[0148]

[0149] In addition, the HE-SIG-A field of the HE MU PPDU may be defined as follows.

[0150] [Table 5]

[0151]

[0152] [Table 6]

[0153]

[0154]

[0155] [Table 7]

[0156]

[0157] [Table 8]

[0158]

[0159]

[0160] In addition, the HE-SIG-A field of the HE TB PPDU can be defined as follows.

[0161] [Table 9]

[0162]

[0163] [Table 10]

[0164]

[0165] [Table 11]

[0166]

[0167] [Table 12]

[0168]

[0169] [Table 13]

[0170]

[0171] As described above, only a multi-user (MU) PPDU may include the HE-SIG-B 1240. Basically, the HE-SIG-A 1250 or the HE-SIG-B 1260 may include resource allocation information (or virtual resource allocation information) for at least one receiving STA.

[0172] Figure 13 An example of PPDU used in this specification is shown.

[0173] Figure 13The PPDU of the present invention may be referred to by various terms such as EHT PPDU, TX PPDU, RX PPDU, first type or Nth type PPDU, etc. For example, in this specification, PPDU or EHT PPDU may be referred to by various terms such as TX PPDU, RX PPDU, first type or Nth type PPDU, etc. In addition, the EHT PPDU may be used in the EHT system and / or a new WLAN system enhanced from the EHT system.

[0174] Figure 13 The PPDU may indicate all or part of the PPDU types used in the EHT system. For example, Figure 13 The example of can be used for both single user (SU) mode and multi user (MU) mode. In other words, Figure 13 The PPDU may be for one receiving STA or multiple receiving STAs. Figure 13 When the PPDU is used in trigger-based (TB) mode, it can be omitted Figure 13 In other words, a STA that has received a trigger frame for uplink MU (UL-MU) may send Figure 13 In the example, the PPDU of EHT-SIG is omitted.

[0175] exist Figure 13 In the physical layer, L-STF to EHT-LTF may be referred to as a preamble or a physical preamble and may be generated / sent / received / obtained / decoded in a physical layer.

[0176] Figure 13 The subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields may be determined to be 312.5 kHz, and the subcarrier spacing of the EHT-STF, EHT-LTF, and data fields may be determined to be 78.125 kHz. That is, the tone index (or subcarrier index) of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields may be expressed in units of 312.5 kHz, and the tone index (or subcarrier index) of the EHT-STF, EHT-LTF, and data fields may be expressed in units of 78.125 kHz.

[0177] exist Figure 13 In the PPDU, L-LTE and L-STF can be the same as those in the legacy fields.

[0178] For example, Figure 13The L-SIG field may include 24 bits of 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 6-bit tail bits. For example, the 12-bit length field may include information related to the length or duration of the PPDU. For example, the 12-bit length field may be determined based on the PPDU type. For example, when the PPDU is a non-HT, HT, VHT PPDU, or EHT PPDU, the value of the length field may be determined as a multiple of 3. For example, when the PPDU is an 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 a non-HT, HT, VHT PPDU, or EHT PPDU, the value of the length field may be determined as "a multiple of 3", and for an HE PPDU, the value of the length field may be determined as "a multiple of 3" + 1 or "a multiple of 3" + 2.

[0179] For example, the transmitting STA may apply BCC encoding based on a code rate of 1 / 2 to the 24-bit information in the L-SIG field. This results in 48 BCC coded bits. BPSK modulation may be applied to the 48 coded bits, generating 48 BPSK symbols. The transmitting STA may map the 48 BPSK symbols to locations other than the pilot subcarriers {subcarrier indices -21, -7, +7, +21} and the DC subcarrier {subcarrier index 0}. As a result, the 48 BPSK symbols may 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 may also map the signal {-1, -1, -1, 1} to subcarrier indices {-28, -27, +27, +28}. This signal can be used for channel estimation in the frequency domain corresponding to {-28, -27, +27, +28}.

[0180] The transmitting STA may generate the RL-SIG in the same manner as the L-SIG. BPSK modulation may be applied to the RL-SIG. The receiving STA may recognize whether the RX PPDU is a HE PPDU or an EHT PPDU based on the presence of the RL-SIG.

[0181] Universal SIG (U-SIG) can be inserted in Figure 13 The U-SIB may be referred to by various terms such as a first SIG field, a first SIG, a first type SIG, a control signal, a control signal field, a first (type) control signal, etc.

[0182] The U-SIG may include N bits of information and may include information for identifying the type of the EHT PPDU. For example, the U-SIG may be configured based on two symbols (e.g., two contiguous OFDM symbols). Each symbol of the U-SIG (e.g., OFDM symbol) may have a duration of 4 μs. Each symbol of the U-SIG may be used to transmit 26 bits of information. For example, each symbol of the U-SIG may be transmitted / received based on 52 data tones and 4 pilot tones.

[0183] For example, A-bit information (e.g., 52 uncoded bits) may be transmitted through U-SIG (or U-SIG field). The first symbol of U-SIG may transmit the first X bits of A-bit information (e.g., 26 uncoded bits), and the second symbol of U-SIB may transmit the remaining Y bits of A-bit information (e.g., 26 uncoded bits). For example, a transmitting STA may obtain 26 uncoded bits included in each U-SIG symbol. The transmitting STA may perform convolutional encoding (i.e., BCC encoding) based on a rate of R=1 / 2 to generate 52 coded bits, and may perform interleaving on the 52 coded bits. The transmitting STA may perform BPSK modulation on the interleaved 52 coded bits to generate 52 BPSK symbols to allocate to each U-SIG symbol. Except for DC index 0, one U-SIG symbol may be transmitted based on 65 tones (subcarriers) from subcarrier index -28 to subcarrier index +28. The 52 BPSK symbols generated by the transmitting STA may be transmitted based on the remaining tones (subcarriers) except for the pilot tones (ie, tones -21, -7, +7, +21).

[0184] For example, the A-bit information (e.g., 52 uncoded bits) generated by the U-SIG may include a CRC field (e.g., a field having a length of 4 bits) and a tail field (e.g., a field having a length of 6 bits). The CRC field and the tail field may be transmitted via the second symbol of the U-SIG. The CRC field may be generated based on the 26 bits allocated to the first symbol of the U-SIG and the remaining 16 bits of the second symbol excluding the CRC / tail field, 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".

[0185] 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 version-independent bits can have a fixed size or a variable size. For example, the version-independent bits can be allocated only to the first symbol of the U-SIG, or the version-independent bits can be allocated 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 referred to by various terms such as first control bits, second control bits, etc.

[0186] 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 TX / RX PPDU. For example, a first value of the 3-bit PHY version identifier may indicate that the TX / RX PPDU is an EHT PPDU. In other words, when the transmitting STA transmits an EHT PPDU, the 3-bit PHY version identifier may be set to the first value. In other words, based on the PHY version identifier having the first value, the receiving STA may determine that the RX PPDU is an EHT PPDU.

[0187] For example, the version-independent bit U-SIG may include a 1-bit UL / DL flag field. A first value of the 1-bit UL / DL flag field relates to UL communication, and a second value of the UL / DL flag field relates to DL communication.

[0188] For example, the version-independent bits of the U-SIG may include information related to the TXOP length and information related to the BSS color ID.

[0189] For example, when the EHT PPDU is divided into various types (for example, various types such as EHT PPDU related to SU mode, EHT PPDU related to MU mode, EHT PPDU related to TB mode, EHT PPDU related to extended range transmission, etc.), information related to the type of the EHT PPDU may be included in the version-related bit of the U-SIG.

[0190] For example, the U-SIG may include: 1) a bandwidth field including information related to the bandwidth; 2) a field including information related to the MCS scheme applied to the EHT-SIG; 3) an indication field including information on whether a dual subcarrier modulation (DCM) scheme is applied to the EHT-SIG; 4) a field including information on the number of symbols used for the EHT-SIG; 5) a field including information on whether the EHT-SIG is generated across the entire frequency band; 6) a field including information related to the type of EHT-LTF / STF; and 7) information related to fields indicating the EHT-LTF length and CP length.

[0191] Can Figure 13 Preamble puncturing is applied to PPDUs that are 80 MHz in length. Preamble puncturing applies puncturing to a portion of the full frequency band (e.g., the secondary 20 MHz frequency band). For example, when transmitting an 80 MHz PPDU, the STA may apply puncturing to the secondary 20 MHz frequency band within the 80 MHz frequency band and may transmit the PPDU only on the primary 20 MHz frequency band and the secondary 40 MHz frequency band.

[0192] For example, the pattern of preamble puncturing may be preconfigured. For example, when the first puncturing pattern is applied, puncturing may be applied only to the auxiliary 20 MHz band within the 80 MHz band. For example, when the second puncturing pattern is applied, puncturing may be applied only to either of the two auxiliary 20 MHz bands included in the auxiliary 40 MHz band within the 80 MHz band. For example, when the third puncturing pattern is applied, puncturing may be applied only to the auxiliary 20 MHz band included in the main 80 MHz band within the 160 MHz band (or the 80+80 MHz band). For example, when the fourth puncturing pattern is applied, puncturing may be applied to at least one 20 MHz channel that does not belong to the main 40 MHz band in the presence of the main 40 MHz band included in the 80 MHz band within the 160 MHz band (or the 80+80 MHz band).

[0193] Information related to the preamble puncturing applied to the PPDU may be included in the U-SIG and / or the EHT-SIG. For example, the first field of the U-SIG may include information related to the contiguous bandwidth, and the second field of the U-SIG may include information related to the preamble puncturing applied to the PPDU.

[0194] For example, based on the following method, the U-SIG and the EHT-SIG may include information related to preamble puncturing. When the bandwidth of the PPDU exceeds 80 MHz, the U-SIG may be configured separately in units of 80 MHz. For example, when the bandwidth of the PPDU is 160 MHz, the PPDU may include a first U-SIG for a first 80 MHz band and a second U-SIG for a second 80 MHz band. In this case, the first field of the first U-SIG may include information related to the 160 MHz bandwidth, and the second field of the first U-SIG may include information related to the preamble puncturing applied to the first 80 MHz band (i.e., information related to the preamble puncturing pattern). In addition, the first field of the second U-SIG may include information related to the 160 MHz bandwidth, and the second field of the second U-SIG may include information related to the preamble puncturing applied to the second 80 MHz band (i.e., information related to the preamble puncturing pattern). In addition, the EHT-SIG adjacent to the first U-SIG may include information related to the preamble code puncturing applied to the second 80 MHz frequency band (i.e., information related to the preamble code puncturing pattern), and the EHT-SIG adjacent to the second U-SIG may include information related to the preamble code puncturing applied to the first 80 MHz frequency band (i.e., information related to the preamble code puncturing pattern).

[0195] Additionally or alternatively, the U-SIG and the EHT-SIG may include information related to preamble puncturing based on the following method. The U-SIG may include information related to preamble puncturing for all frequency bands (i.e., information related to the preamble puncturing pattern). That is, the EHT-SIG may not include information related to preamble puncturing, and only the U-SIG may include information related to preamble puncturing (i.e., information related to the preamble puncturing pattern).

[0196] The U-SIG can be configured in 20MHz units. For example, when configuring an 80MHz PPDU, the U-SIG can be duplicated. That is, four identical U-SIGs can be included in an 80MHz PPDU. PPDUs with bandwidth exceeding 80MHz can include different U-SIGs.

[0197] Figure 13 The EHT-SIG may include control information for receiving STAs. The EHT-SIG may be transmitted using at least one symbol, and one symbol may have a length of 4 us. Information on the number of symbols used for the EHT-SIG may be included in the U-SIG.

[0198] Figure 13 The PPDU may be determined (or identified) as an EHT PPDU based on the following method.

[0199] The receiving STA may determine the type of the RX PPDU as an EHT PPDU based on the following aspects. For example, 1) when the first symbol after the L-LTF signal of the RX PPDU is a BPSK symbol; 2) when the RL-SIG in which the L-SIG of the RX PPDU is repeated is detected; and 3) when the result of applying "modulo 3" to the value of the length field of the L-SIG of the RX PPDU is detected as "0", the RX PPDU may be determined to be an EHT PPDU. When the RX PPDU is determined to be an EHT PPDU, the receiving STA may determine the type of the RX PPDU as an EHT PPDU based on Figure 13 The type of the EHT PPDU (e.g., SU / MU / triggered-based / extended range type) can be detected based on the bit information included in the symbol following the RL-SIG of the U-SIG. In other words, the receiving STA can determine that the RX PPDU is an EHT PPDU based on: 1) the first symbol following the L-LTF signal, which is a BPSK symbol; 2) the RL-SIG that is adjacent to and identical to the L-SIG field; 3) the L-SIG including the length field in which the result of applying "modulo 3" is set to "0"; and 4) the 3-bit PHY version identifier of the U-SIG (e.g., a PHY version identifier having a first value).

[0200] For example, the receiving STA may determine the type of the RX PPDU as an HE PPDU based on the following factors: 1) when the first symbol after the L-LTF signal is a BPSK symbol; 2) when an RL-SIG in which the L-SIG is repeated is detected; and 3) when the result of applying "modulo 3" to the value of the length field of the L-SIG is detected as "1" or "2", the RX PPDU may be determined to be an HE PPDU.

[0201] For example, the receiving STA may determine the type of the RX PPDU as non-HT, HT, or VHT PPDU based on the following factors. For example, if 1) the first symbol after the L-LTF signal is a BPSK symbol, and 2) the RL-SIG in which the L-SIG is repeated is not detected, the RX PPDU may be determined as non-HT, HT, or VHT PPDU. Furthermore, even if the receiving STA detects a repeated RL-SIG, if the result of applying "modulo 3" to the length value of the L-SIG is detected as "0," the RX PPDU may be determined as non-HT, HT, or VHT PPDU.

[0202] In the following examples, signals represented as (TX / RX / UL / DL) signals, (TX / RX / UL / DL) frames, (TX / RX / UL / DL) packets, (TX / RX / UL / DL) data units, (TX / RX / UL / DL) data, etc. may be based on Figure 13 PPDU transmission / reception signal. Figure 13 The PPDU can be used to send / receive various types of frames. For example, Figure 13 The PPDU may be used for control frames. Examples of control frames may include Request to Send (RTS), Clear to Send (CTS), Power Save Poll (PS-poll), BlockACKReq, BlockAck, Null Data Packet (NDP) notifications, and trigger frames. For example, Figure 13 The PPDU can be used for management frames. Examples of management frames may include beacon frames, (re)association request frames, (re)association response frames, probe request frames, and probe response frames. For example, Figure 13 The PPDU can be used for data frames. For example, Figure 13 The PPDU may be used to simultaneously transmit at least two or more of a control frame, a management frame, and a data frame.

[0203] Figure 14 An example of a modified transmitting device and / or receiving device of the present specification is shown.

[0204] Figure 1 Each device / STA of sub-graph (a) / (b) can be as follows Figure 14 Modifications shown. Figure 14 The transceiver 630 can be used with Figure 1 The transceivers 113 and 123 are the same. Figure 14 The transceiver 630 may include a receiver and a transmitter.

[0205] Figure 14 The processor 610 can be used with Figure 1 The processors 111 and 121 are the same. Alternatively, Figure 14 The processor 610 can be used with Figure 1 The processing chips 114 and 124 are the same.

[0206] Figure 14 The memory 620 can be used with Figure 1 The memories 112 and 122 are the same. Alternatively, Figure 14 The memory 620 may be Figure 1 The memories 112 and 122 are different separate external memories.

[0207] Reference Figure 14 , power management module 611 manages power for processor 610 and / or transceiver 630. Battery 612 supplies power to power management module 611. Display 613 outputs results processed by processor 610. Keypad 614 receives input to be used by processor 610. Keypad 614 may be displayed on display 613. SIM card 615 may be an integrated circuit for securely storing an International Mobile Subscriber Identity (IMSI) and its associated keys, which are used to identify and authenticate users on mobile telephony devices (e.g., mobile phones and computers).

[0208] Reference Figure 14 , the speaker 640 may output a result related to the sound processed by the processor 610. The microphone 641 may receive an input related to the sound to be used by the processor 610.

[0209] Hereinafter, the technical features of channel bonding supported by the STA of the present disclosure will be described.

[0210] For example, in IEEE 802.11n systems, 40 MHz channel bonding can be performed by combining two 20 MHz channels. Additionally, 40 / 80 / 160 MHz channel bonding can be performed in IEEE 802.11ac systems.

[0211] For example, a STA can perform channel bonding for a primary 20 MHz channel (P20 channel) and a secondary 20 MHz channel (S20 channel). A backoff count / counter can be used in the channel bonding process. The backoff count value can be selected as a random value and decremented during the backoff interval. Typically, when the backoff count value reaches 0, the STA can attempt to access the channel.

[0212] During the backoff interval, when the P20 channel is determined to be idle and the backoff count value of the P20 channel reaches 0, the STA performing channel bonding determines whether the S20 channel remains idle for a specific period of time (e.g., the Point Coordination Function Interframe Space (PIFS)). If the S20 channel is idle, the STA can bond the P20 and S20 channels. That is, the STA can transmit a signal (PPDU) over a 40 MHz channel (i.e., a 40 MHz bonded channel) that includes the P20 and S20 channels.

[0213] Figure 15 An example of channel bonding is shown. Figure 15 As shown, the primary 20 MHz channel and the secondary 20 MHz channel can be combined into a 40 MHz channel (primary 40 MHz channel) through channel bonding. That is, the bonded 40 MHz channel can include the primary 20 MHz channel and the secondary 20 MHz channel.

[0214] Channel bonding can be performed when the channels adjacent to the primary channel are idle. That is, the primary 20MHz channel, the secondary 20MHz channel, the secondary 40MHz channel, and the secondary 80MHz channel can be bonded in sequence. However, if the secondary 20MHz channel is determined to be busy, channel bonding cannot be performed even if all other secondary channels are idle. In addition, when the secondary 20MHz channel is determined to be idle and the secondary 40MHz channel is busy, channel bonding can be performed only on the primary 20MHz channel and the secondary 20MHz channel.

[0215] Hereinafter, preamble puncturing supported by STA in the present disclosure will be described.

[0216] For example, in Figure 15 In the example of FIG, if the primary 20 MHz channel, the secondary 40 MHz channel, and the secondary 80 MHz channel are all idle, but the secondary 20 MHz channel is busy, it may not be possible to bind to the secondary 40 MHz channel and the secondary 80 MHz channel. In this case, the STA may configure a 160 MHz PPDU and may perform preamble puncturing on the preambles (e.g., L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF, EHT-SIG, EHT-STF, EHT-LTF, etc.) sent through the secondary 20 MHz channel so that the STA can send signals through the idle channels. In other words, the STA may perform preamble puncturing for some frequency bands of the PPDU. Information about preamble puncturing (e.g., information about the 20 / 40 / 80 MHz channels / bands to which puncturing is applied) may be included in the signal field (e.g., HE-SIG-A, U-SIG, EHT-SIG) of the PPDU.

[0217] Hereinafter, technical features of multi-link (ML) supported by the STA of the present disclosure will be described.

[0218] The STA (AP and / or non-AP STA) of the present disclosure may support multi-link (ML) communication. ML communication may refer to communication that supports multiple links. Links related to ML communication may include Figure 9 The 2.4GHz frequency band shown, Figure 10 The 5GHz band shown and Figure 11 Channels of the 6 GHz frequency band are shown (e.g., 20 / 40 / 80 / 160 / 240 / 320 MHz channels).

[0219] The multiple links used for ML communication can be configured in various ways. For example, the multiple links supported by a STA for ML communication may include multiple channels in the 2.4 GHz band, multiple channels in the 5 GHz band, and multiple channels in the 6 GHz band. Alternatively, the multiple links supported by a STA for ML communication may include a combination of at least one channel in the 2.4 GHz band (or the 5 GHz / 6 GHz band) and at least one channel in the 5 GHz band (or the 2.4 GHz / 6 GHz band). Furthermore, at least one of the multiple links supported by a STA for ML communication may be a channel to which preamble puncturing is applied.

[0220] The STA may perform ML settings to perform ML communication. ML settings may be performed based on management frames or control frames such as beacons, probe requests / responses, and association requests / responses. For example, information about ML settings may be included in element fields included in beacons, probe requests / responses, and association requests / responses.

[0221] When ML setup is complete, an enabled link for ML communication may be determined. The STA may perform frame exchange via at least one of the multiple links determined as enabled links. For example, the enabled link may be used for at least one of management frames, control frames, and data frames.

[0222] When a STA supports multiple links, the transceivers supporting each link can operate as a single logical STA. For example, a STA supporting two links can be represented as a multi-link device (MLD), including a first STA for the first link and a second STA for the second link. For example, an AP supporting two links can be represented as an AP MLD, including a first AP for the first link and a second AP for the second link. In addition, a non-AP supporting two links can be represented as a non-AP MLD, including a first STA for the first link and a second STA for the second link.

[0223] In the following, more specific features related to the ML setting are described.

[0224] The MLD (AP MLD and / or non-AP MLD) can transmit information about the links that the corresponding MLD can support through ML settings. The link information can be configured in various ways. For example, the information about the link may include at least one of: 1) information about whether the MLD (or STA) supports simultaneous RX / TX operation, 2) information about the number / upper limit of uplinks / downlinks supported by the MLD (or STA), 3) information about the location / frequency band / resource of the uplinks / downlinks supported by the MLD (or STA), 4) information about the available or preferred frame type (management, control, data, etc.) in at least one uplink / downlink, 5) information about the available or preferred ACK policy in at least one uplink / downlink, and 6) information about the available or preferred traffic identifier (TID) in at least one uplink / downlink. The TID is related to the priority of the traffic data and is represented as eight types of values ​​according to the conventional wireless LAN standard. That is, eight TID values ​​corresponding to four access categories (ACs) (AC_Background (AC_BK), AC_Best Effort (AC_BE), AC_Video (AC_VI), AC_Voice (AC_VO)) according to the conventional WLAN standard may be defined.

[0225] For example, it may be preset that all TIDs are mapped for uplink / downlink. Specifically, if no negotiation is performed through ML settings, if all TIDs are used for ML communication, and if mapping between uplink / downlink and TIDs is negotiated through additional ML settings, the negotiated TIDs can be used for ML communication.

[0226] Through ML settings, multiple links available for ML communication by sending and receiving MLDs can be set. This can be referred to as "enabled links." "Enabled links" can be referred to variously. For example, they can be referred to variously as first links, second links, transmitting links, and receiving links.

[0227] After the ML setting is completed, the MLD may update the ML setting. For example, when it is necessary to update information about a link, the MLD may send information about the new link. The information about the new link may be sent based on at least one of a management frame, a control frame, and a data frame.

[0228] Depending on the implementation, MLDs may include non-AP MLDs and AP-MLDs. Non-AP MLDs and AP-MLDs may be categorized based on access point (AP) functionality. Non-AP MLDs and AP-MLDs may be physically or logically separated. For example, when an MLD performs AP functionality, it may be referred to as an AP MLD, while when an MLD performs STA functionality, it may be referred to as a non-AP MLD.

[0229] In the following description, an MLD has one or more connected / associated STAs and has one MAC service access point (SAP) through the upper link layer (Logical Link Control, LLC). MLD can refer to a physical device or a logical device. In the following, a device can refer to an MLD.

[0230] Additionally, the MLD may include at least one STA connected to each link in the multilink. For example, the processor of the MLD may control the at least one STA. For example, the at least one STA may be independently configured and operated. The at least one STA may each include a processor and a transceiver. For example, the at least one STA may operate independently without regard to the processor of the MLD.

[0231] In the following description, for convenience of description, it is described that the MLD (or the processor of the MLD) controls at least one STA, but is not limited thereto. As described above, at least one STA can independently transmit / receive signals without being associated with the MLD.

[0232] Depending on the implementation, an AP MLD or a non-AP MLD may be configured with a structure having multiple links. In other words, a non-AP MLD may support multiple links. A non-AP MLD may include multiple STAs. Each of the multiple STAs may have a link for the corresponding STA.

[0233] The EHT standard (802.11be standard) features a multi-link device (MLD) architecture in which a single AP / non-AP MLD supports multiple links. STAs in a non-AP MLD can transmit information related to other STAs in the same non-AP MLD over a single link. This reduces frame exchange overhead, increases STA link utilization efficiency, and reduces power consumption.

[0234] Figure 16 An example of the structure of a non-AP MLD is shown.

[0235] Reference Figure 16 , non-AP MLD can be configured in a structure with multiple links. In other words, non-AP MLD can support multiple links. Non-AP MLD can include multiple STAs. Multiple STAs can have links for each STA. Although Figure 16An example of a non-AP MLD structure is shown, but the AP MLD structure can be configured as Figure 16 The example of the structure of the non-AP MLD shown is the same.

[0236] For example, a non-AP MLD may include STA 1, STA 2, and STA 3. STA 1 may operate on link 1. Link 1 may be included in the 5 GHz frequency band. STA 2 may operate on link 2. Link 2 may be included in the 6 GHz frequency band. STA 3 may operate on link 3. Link 3 may be included in the 5 GHz frequency band. The frequency bands including links 1, 2, and 3 are provided for illustration, and links 1, 2, and 3 may be included in 2.4, 5, and 6 GHz.

[0237] AP / non-AP MLD supporting multi-link, APs of AP MLD, and STAs of non-AP MLD can connect to each link through the link establishment process. Depending on the situation, the connected link can be changed to another link or reconnected through AP MLD or non-AP MLD.

[0238] In the EHT standard, links can be classified as either anchor links or non-anchor links to reduce power consumption. Anchor links and non-anchor links can be referred to differently. For example, an anchor link can be referred to as a primary link, while a non-anchor link can be referred to as a secondary link.

[0239] Depending on the implementation, an AP MLD supporting multiple links can manage each link by designating each link as an anchor link or a non-anchor link. The AP MLD can support one or more links among the multiple links as anchor links. A non-AP MLD can select and use one or more anchor links from an anchor link list (a list of anchor links supported by the AP MLD).

[0240] For example, the anchor link may be used not only for frame exchange for synchronization, but also for non-data frame exchange (ie, beacon and management frame exchange). The non-anchor link may be used only for data frame exchange.

[0241] During idle periods, non-AP MLDs can monitor (or detect) only anchor links to receive beacons and management frames. Therefore, non-AP MLDs need to connect to at least one anchor link to receive beacons and management frames. One or more anchor links must always be enabled. However, non-anchor links are only used for data frame exchange. Therefore, during idle periods when channels / links are not in use, STAs corresponding to non-anchor links (or STAs connected to non-anchor links) can enter sleep mode. This reduces power consumption.

[0242] The following description will provide a protocol for dynamically recommending or requesting link reconnection based on the availability of efficient link connections using AP MLD or non-AP MLD. Furthermore, the following description will also provide an anchor link reconnection protocol that considers the characteristics of anchor links for power reduction and general links.

[0243] Link change and reconnection implementation

[0244] According to an embodiment, each link between the AP MLD and the non-AP MLD may be determined in the association or (re)association process. The AP MLD and the non-AP MLD may perform frame exchange via the connected links. Figure 17 A specific implementation of AP MLD and non-AP MLD connection handling via link establishment is described.

[0245] Figure 17 This shows an example of processing connections by AP MLD and non-AP MLD through link establishment.

[0246] Reference Figure 17 , AP MLD may include AP 1, AP 2, and AP 3. Non-AP MLD may include STA 1 and STA 2. AP 1 and STA 1 may be connected via link 1. AP 2 and STA 2 may be connected via link 2.

[0247] For example, AP 1 and STA 1 can connect via Link 1 through a first link establishment process. AP 2 and STA 2 can connect via Link 2 through a second link establishment process. In another example, an AP MLD and a non-AP MLD can connect via a single link establishment process. In other words, an AP MLD and a non-AP MLD can connect via Link 1 and Link 2 based on a single link establishment process.

[0248] As described above, each AP and each STA can perform frame exchange through the connected link. In addition, through one link, information about other APs related to different links or other STAs related to different links can be sent and received.

[0249] However, after this link establishment process, the AP MLD or non-AP MLD may request a link change or reconnection for more efficient frame exchange (eg, load balancing or interference avoidance) depending on the situation / circumstance.

[0250] Please refer to Figure 18 Embodiments related to link change or reconnection are described.

[0251] Figure 18 Shows an example of a link change or reconnection.

[0252] Reference Figure 18 STA 2 is normally connected to AP 2. Subsequently, excessive data load may be generated in AP 2. STA 2 can reconnect to AP 3, which has a relatively small data load. In this case, AP MLD and non-AP MLD can perform efficient data exchange.

[0253] Figure 19 A specific example of link change or reconnection is shown.

[0254] Reference Figure 19 , AP 1 of AP MLD can connect to STA 1 of non-AP MLD through link 1. AP 2 of AP MLD can connect to STA 2 of non-AP MLD through link 2. Subsequently, STA 2 can attempt / request connection to AP 3 through link change or reconnection, and STA 2 can connect to AP 3 through link 2 based on the link change or reconnection.

[0255] Depending on the implementation, non-AP MLD and AP MLD can request link transitions to improve performance. AP MLD and non-AP MLD can transmit, receive, and exchange various information regarding each current link and information regarding link status. Therefore, AP MLD and non-AP MLD can select a link more suitable for transmitting and receiving signals based on the various information regarding each current link and link status, and can transmit this information to assist in the selection. For example, the various information regarding each current link can include information regarding the data traffic load of each link and the channel access capabilities between the links. For example, the link status can be set to "disabled" or "enabled."

[0256] In the following description, a process in which AP MLD / non-AP MLD negotiates with non-AP MLD / AP MLD to request a link change or reconnection to a link other than the connected link to improve performance may be referred to as "link switching negotiation." "Link switching negotiation" may be referred to by various terms and may vary.

[0257] In the link switching negotiation process, the non-AP MLD (or AP MLD) may request to change a link connected to a specific STA to another link, and the AP MLD (or non-AP MLD) may respond to the request with a request accept or reject message.

[0258] For example, Figure 19 As shown, when the link change is agreed upon through the link switching negotiation, the STA can perform a link re-establishment process for reconnection by changing the existing link from AP 2 to AP 3.

[0259] In the following description, link change or reconnection processing can be divided into when an AP MLD request is made and when a non-AP MLD request is made.

[0260] AP MLD request link change or reconnection implementation

[0261] According to an embodiment, for efficient data transmission, the AP MLD may request the non-AP MLD to change or reconnect a link. For example, for load balancing, the AP MLD may request the STA to change or reconnect to a more efficient link based on the data traffic of each AP.

[0262] For example, the AP MLD may calculate / identify / determine a link suitable for a STA other than the AP MLD based on data traffic load information about each AP and / or channel access capability information about each link (e.g., information about simultaneous TX / RX (STR) capability). Subsequently, the AP MLD may request a link change or reconnection from the STA (or non-AP MLD) based on the data traffic load information about each AP and / or channel access capability information about each link.

[0263] As described above, when requesting a link change, the AP MLD may transmit information about a link considered most suitable for the non-AP MLD through a request message. For example, the request message may include a beacon or a management frame.

[0264] Regarding the above embodiment, a new element or field including information about a link considered to be the most suitable may be proposed. The newly proposed element or field may be defined as "recommended link." "Recommended link" is provided for illustration purposes only, and the specific element or field name may vary.

[0265] Recommended Link (element / field): This element or field indicates that the AP MLD recommends the link most suitable for STAs other than the AP MLD based on various information about each link (e.g., the data load of each link). For example, the recommended link (element / field) may be indicated as the link ID information of the AP MLD or the AP BSS information. In other words, the recommended link (element / field) may include the link ID information of the AP MLD or the AP BSS information.

[0266] Depending on the implementation, the recommended link (element / field) may optionally be included in the link switching response and sent. For example, the STA may establish a connection with the link recommended by the AP based on the element / field (i.e., the recommended link). In another example, the STA may request to connect to a link different from the indicated link based on the element / field (i.e., the recommended link) and additional information possessed by the STA.

[0267] Please refer to Figure 20 A specific signal exchange process between the AP MLD and the non-AP MLD according to the above embodiment will be described.

[0268] Figure 20 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0269] Reference Figure 20 In the case where STA 2 is connected to AP 2 via link 2, a large amount of data traffic may be concentrated in AP 2. In other words, in the case where STA 2 is connected to AP 2 via link 2, a large amount of data traffic may be generated in AP 2.

[0270] AP MLD (or AP 2) can request non-AP MLD (or STA 2) to reconnect to AP 3, to which relatively few STAs are connected. The reconnection request message is typically sent to the STA that wishes to reconnect (i.e., STA 2), but can be sent to any STA (i.e., another STA) depending on circumstances (e.g., channel status or link status). In other words, the STA to which the reconnection request message (e.g., link switch request frame) is sent can vary depending on the channel status or link status.

[0271] For example, the STA (i.e., STA 2) that receives the request message for requesting reconnection may send a response message "Accept" (e.g., a link switch response frame) when accepting the request. In another example, when rejecting the request, the STA (i.e., STA 2) may send a response message "Reject".

[0272] Typically, the STA that accepts the reconnection (ie, STA 2) sends a response message via the existing link (the link connected before the reconnection), but the response message may be sent through any link (ie, another STA) using the characteristics of the multi-link.

[0273] When STA 2 accepts the link reconnection request, it disconnects from existing AP 2 and, after sending a response message, requests link reconnection to AP 3. Here, the reconnection request process can be performed in the same manner as the existing link establishment process between MLDs. After the link establishment process between AP 3 and STA 2 is completed, STA 2 can exchange frames with AP 3 over Link 2.

[0274] However, when STA 2 rejects the link reconnection request, STA 2 and AP 2 may use the existing connected link (ie, link 2) as it is.

[0275] According to an embodiment, when the AP recommends a suitable link when requesting a link change to the STA, the STA may or may not change the link to the recommended link. For example, the AP may use the recommended link to recommend a link suitable for the STA.

[0276] For example, the STA may accept the link change via a response message to a request message from the AP for requesting reconnection. The STA may accept / identify the link change via the recommended link and may request another link change from the AP based on information other than the information included in the request message.

[0277] Therefore, the AP needs to inform the STA whether it accepts the response message. To this end, the AP can send a confirmation message (eg, a link switching confirmation frame) to the STA in response to the response message (eg, a link switching response frame) from the STA.

[0278] Please refer to Figure 21 The specific operations of AP MLD and non-AP MLD in the above embodiment are described.

[0279] Figure 21 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0280] Reference Figure 21 , AP 2 may request a link change including recommended link information from STA 2. In other words, AP 2 may send a link switching request frame including recommended link information to STA 2.

[0281] STA 2 may send a link switch response frame to indicate whether it accepts the link request.

[0282] For example, when accepting link switching, STA 2 may transmit a link switching response frame including information about the link to be changed. Here, the information about the link to be changed may or may not be the same as the recommended link.

[0283] In another example, when STA 2 responds with a link switch response frame by selecting a link other than the recommended link provided by AP 2, the AP may send a message to the STA regarding whether the link is finally accepted. This message may be referred to as a link switch confirmation frame.

[0284] For example, AP 2 may accept the link change to the link designated by STA 2 through the link switch confirm frame. STA 2 may attempt the link change to the link designated by STA 2 based on the link switch confirm frame.

[0285] In another example, AP 2 may reject the link change to the link designated by STA 2 through the link switch confirm frame. STA 2 and AP 2 may maintain the connection via the existing connection link without changing the link.

[0286] Even when the AP sends a link switching request frame without including the recommended link information, it can be applied Figure 21For example, when an AP (e.g., AP 2) sends a Link Switch Request frame to a STA (e.g., STA 2) without recommended link information, the STA can directly specify the link to change based on the information it has and respond with a Link Switch Response frame to the AP. Even in this case, the AP must eventually send a Link Switch Confirmation frame for acceptance. Therefore, even when the Link Switch Request frame does not include recommended link information, the embodiment in which the AP sends a Link Switch Confirmation frame can be applied.

[0287] Implementation of non-AP MLD request link change or reconnection

[0288] According to an embodiment, for efficient data transmission, the non-AP MLD may request the AP MLD to change or reconnect a link. For example, in order to use the STR capability in data transmission, the non-AP MLD may request the AP MLD to change or reconnect the connected link.

[0289] Figure 22 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0290] Reference Figure 22 , AP MLD and non-AP MLD may perform link switching negotiation. STA 2 of the non-AP MLD may send a link switching request frame to AP 2 of the AP MLD. In response to the link switching request frame, AP 2 of the AP MLD may send a link switching response frame to STA 2 of the non-AP MLD. The link switching request frame or link switching response frame may be sent and received over the link to be changed, but is not limited thereto. The link switching request frame or link switching response frame may be sent and received over various links other than the link to be changed.

[0291] A non-AP MLD can request a link change or reconnection through various methods. Below, three methods are presented for a non-AP MLD to request a link change or reconnection. Specifically, the three methods are described in order: a request method, a non-request method, and a general method.

[0292] 1) Request method : A method in which a non-AP MLD requests various information of an AP included in the AP MLD from the AP MLD and receives the various information. For example, the various information may include information on capabilities, operation elements, and BSS parameters.

[0293] Depending on the embodiment, a method in which a STA requests information about other APs of the connected AP MLD may be used in various situations, in addition to link reconfiguration. For example, after multi-link establishment, the STA may request BSS parameter information about other APs for link switching and select the best link based on the received information. Alternatively, during the discovery process, the STA may request BSS load information about each AP from the AP MLD and select a link to be established based on the received information. (Here, it is assumed that the number of APs of the AP MLD is greater than the number of STAs of the non-AP MLD.)

[0294] Therefore, the AP receiving the information request message may send any information about all APs in the AP MLD, such as capability information, BSS parameter information, key parameters and / or operation element information. All of the above examples are applicable to the embodiments to be described below.

[0295] 2) Unsolicited methods : A method in which an AP transmits various information without any information request from a non-AP MLD. STAs can use the received information in various situations. Depending on the embodiment, the method in which an AP MLD transmits information about other APs without any information request from a STA can be used in various situations, except for link reconfiguration. Therefore, an AP that receives an information request message can transmit any information about all APs in the AP MLD, such as capability information, BSS parameter information, key parameters, and / or operational element information. All of the above examples are applicable to the embodiments described below.

[0296] 3) General approach : Non-AP MLD is a method of requesting link (re)selection based on information obtained through a previous beacon frame or the like without additional information.

[0297] 1) Request method

[0298] Hereinafter, an implementation of the request method may be described.

[0299] According to an embodiment, before link change or reconnection, the non-AP MLD may request information for selecting a suitable link from the AP MLD. To select a suitable link, the STA may use data load information about each AP or capability information about each link (or information about other links).

[0300] For example, capability information on each link may be included in a beacon frame to be periodically transmitted.

[0301] In another example, the capability information about each link may be optional and may not be included in the beacon frame transmitted every period. Alternatively, to reduce frame overhead, only information about the link connected to the STA or some associated links may be received. Alternatively, when the beacon reception period is long due to the characteristics of the non-AP MLD (e.g., a low-power device), the non-AP MLD may not receive the capability information about each link for selecting an appropriate link.

[0302] In this case, non-AP MLD may require the latest information on the capabilities of each link and information on each link of AP MLD (e.g., BSS parameter information or operational element information). The capabilities of each link and the information on each link may include not only the links used for transmission and reception, but also other links. For example, fields in QoS data frames, management frames, probe response / request frames, PS-Poll frames, or null frames (the A-Control field in the 11ax standard) can be used to request / send the latest information. Alternatively, a separate new frame can be defined to request / send the latest information.

[0303] According to an embodiment, to request the latest information about the capabilities of each link and the AP's Multi-Level Local Area Network (MLD) for each link, the STA may send a request message to the AP requesting the information required for link reselection. For example, a conventionally defined probe request frame may be reused for the request message. In another example, a new frame for the request message may be defined.

[0304] Depending on the implementation, a STA can request specific information from an AP by specifying necessary specific information in a request message. The specific information that can be specified may vary depending on the situation. That is, a STA can request only information corresponding to a specific link or only information corresponding to specific capabilities. For example, information corresponding to a specific link may include information about the BSS load / parameters of the specific link. Information corresponding to capabilities may include BSS load information for all links or BSS load information for a specific link. In this case, the AP can send only the information specified by the STA in a response message. Specific implementations related to specific information requests and responses can be described through implementations related to the definition and operation of the IOM.

[0305] In another example, the STA may request all capability information currently possessed by the AP MLD (eg, including information about other links) through a request message.

[0306] As in the above example, the implementation method of transmitting all information possessed by the AP or transmitting only specific information specified by the STA can be defined / configured in various ways. For example, the AP can transmit all information or specified information based on a separate field or bitmap to indicate (or transmit) only specific information.

[0307] The message for requesting information from the AP MLD may generally be sent by a STA that wants to reconnect, but may be sent to any STA (ie, other STA) depending on circumstances (channel status or link status).

[0308] Upon receiving the request message, the AP MLD may send a response message (i.e., an information message) to the non-AP MLD, including the information requested by the STA (e.g., data load information about each link and STR capability information between the links). For example, when a conventional probe request frame is reused for the request message, the AP (or AP MLD) needs to respond with a probe response frame as the response message.

[0309] The response message is also typically sent by the AP that received the request message, but can also be sent to any AP (ie, other APs) using the multi-link feature.

[0310] Optionally, the AP MLD may also send a "recommended link" element that recommends a link suitable for the STA through a response message including the above-mentioned various information (eg, the latest information required for link reselection).

[0311] The request method described above can be used by non-AP MLD STAs to change or reconnect links. For example, if a non-AP MLD STA wishes to reselect a link due to link congestion, it can use the request method to request BSS load information and BSS parameter information for each link of the connected AP MLD. Upon receiving this request message, the AP can send the link and information indicated by the STA via a response message.

[0312] Hereinafter, the above request message and response message may be referred to as an information request message and an information response message to distinguish them from a link change request message and a link change response message.

[0313] The STA can reselect an appropriate link based on the information included in the information response message and can request a link change or reconnection from the AP MLD through a link change request message. The link change request message may include information about the AP to which the STA is reconnected and information about the link to which the STA is reconnected.

[0314] Upon receiving the request message, the AP MLD may send a response message "Accept" when accepting the request. The AP MLD may send a response message "Reject" when rejecting the request.

[0315] When the request is accepted, the AP may perform link (re)establishment based on frame exchange through the link reselected by the AP from the time after the response message is sent. When the request is rejected, the STA may use the link of the existing connection as it is.

[0316] Please refer to Figure 23 Describes specific examples of operations of AP MLD and non-AP MLD according to the request method.

[0317] Figure 23 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0318] Reference Figure 23 When STA 2 of the non-AP MLD wishes to reselect a connected link, STA 2 may send an information request message to AP MLD via link 2. Upon receiving the information request message, AP MLD may send an information response message including information required for link reselection by the non-AP MLD. Based on the information included in the information response message, STA 2 of the non-AP MLD may send a link change request message (i.e., a link switch request frame) to AP 2 of AP MLD. STA 2 may then receive a link change response message (i.e., a link switch response frame) and perform link (re)establishment to perform the link change.

[0319] Even when a STA requests necessary information from an AP, the information request implementation methods proposed in this specification can be used / applied. When the information included in a frame (e.g., a beacon) received by the STA from the AP is insufficient, the STA can request the required information from the AP. For example, when the AP only transmits information about connected links without including information about other links, or only transmits information about whether information about other links is updated, the STA can request the required information from the AP.

[0320] Hereinafter, a new element / field including information for a non-AP MLD STA to select a suitable link may be proposed.

[0321] For example, a "per link STA ratio" (element / field) may be proposed. The "per link STA ratio" may include information about the ratio of STAs connected per link. For a specific example of the "per link STA ratio", see Figure 24 describe.

[0322] Figure 24 A specific example of the STA ratio per link is shown.

[0323] Reference Figure 24 , STA ratio per link (element / field) may include information on the number or ratio of STAs connected per link in the entire AP MLD.

[0324] For example, when a total of 50 STAs are connected to an AP MLD having three links, 10 STAs may be connected to link 1 and 20 STAs may be connected to link 2. The AP MLD may transmit information about STAs connected per link to the non-AP MLD through the STA ratio per link (element / field) as information about a value or ratio (%).

[0325] For example, when information about STAs connected per link is expressed as a value, Link 1 may be expressed / set to 10, and Link 2 may be expressed / set to 20. Therefore, the value of the STA ratio per link 1 may be set to 10. In addition, the value of the STA ratio per link 2 may be set to 20.

[0326] In another example, when information about STAs connected per link is expressed as a ratio, link 1 may be expressed / set as 20 (10 / 50)%, and link 2 may be expressed / set as 40 (20 / 50)%. Therefore, the value of the STA ratio per link 1 may be set to 20. In addition, the value of the STA ratio per link 2 may be set to 40.

[0327] The above examples are provided for illustration, and the information on the STA connected per link may be set differently. In addition to the above examples, the information on the STA connected per link may be set as a relative value.

[0328] The STA may identify / obtain the number and ratio of STAs per link connection based on the information about the STAs per link connection, and may use the number and ratio as information for link selection.

[0329] According to an embodiment, in addition to the "per link STA ratio" (element / field), various information / elements / fields may be included in the information response message. For example, the following information / elements / fields may be included in the information response message.

[0330] - BSS load information about each AP

[0331] - STR capability information between links

[0332] -TXOP information about each link

[0333] -NAV information about each link

[0334] - Information about recommended links (i.e., "recommended links" element)

[0335] - Information about the ratio of STAs connected per link (ie, "per-link STA ratio" element)

[0336] -other

[0337] In addition to the above-mentioned information / elements / fields, various information required for link selection may be included in the information response message and transmitted.

[0338] Upon receiving this information, the STA can select an AP to which it wants to change or reconnect based on the received information, and then send a request message requesting link reconnection. Upon receiving the request message, the AP MLD can send an "Accept" response message if it accepts the request. Alternatively, the AP MLD can send a "Reject" response message if it rejects the request.

[0339] When the request is accepted, the AP may perform frame exchange with the AP through the newly selected link from the time after sending the response message. When the request is rejected, the STA may use the existing connected link as it is.

[0340] 2) Unsolicited methods

[0341] Unlike the request method, in which a non-AP MLD directly requests additional information, the unsolicited method enables the AP MLD to send additional information to the non-AP MLD via a beacon frame or a separate frame (e.g., a QoS data frame, a management frame, a FILS discovery frame, an unsolicited probe response frame, a PS-Poll frame, or a field of a null frame (the A-Control field in the 11ax standard)) without requesting the non-AP MLD for the additional information. In another example, a new frame can be defined as a frame for sending additional information to the non-AP MLD.

[0342] For example, when the beacon period is quite long, the necessary information for link switching of the non-AP MLD may be insufficient or may not be up to date. Therefore, the AP may send a frame including link capability information about the AP MLD to the non-AP MLD. The non-AP STA can then obtain the latest information about the link capabilities of the AP MLD. The frame may be sent periodically or aperiodically.

[0343] For example, when frames are transmitted periodically, the AP may transmit frames at regular intervals to share the latest information about the AP. Here, the intervals need to be shorter than the period of the beacon sent by the AP. Furthermore, when FILS discovery frames are used as frames, frames may be transmitted every 20 us. In another example, a period agreed upon by the AP and STA through capability negotiation may be used. For example, the transmission period may be indicated by the values ​​of the "Periodicity" field and the "Interval" field / subfield of the IOM Capabilities element.

[0344] In another example, when frames are transmitted aperiodically, the AP may transmit frames whenever an event occurs that updates information about the AP (capabilities, BSS parameters, and operational elements). In a specific example, whenever the link capabilities of the AP in the AP MLD change, the changed information may be transmitted to connected STAs. In this case, the STAs can maintain the latest information about the link capabilities.

[0345] According to the above example, since the non-AP STA does not send a separate request message for obtaining link capabilities, the frame exchange overhead is relatively small compared to the request method. In addition, since the STA can receive updated information whenever the main information is updated, the STA can effectively use the received information.

[0346] Please refer to Figure 25 Specific examples of operations of AP MLD and non-AP MLD according to the unsolicited method are described.

[0347] Figure 25 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0348] Reference Figure 25 , the AP MLD may send necessary information required for link reselection to the non-AP via a separate frame (eg, an information message) without any request message from the non-AP MLD.

[0349] According to the embodiment, Figure 25 Differently, the AP MLD may send information about the link capability to the STA through a field of a DL frame (eg, a QoS data frame) sent by the AP MLD to the non-AP MLD without any request message from the non-AP MLD.

[0350] Therefore, regardless of the beacon frame period, the non-AP MLD can obtain the latest link capability information. Based on the received information, the non-AP MLD can select an appropriate link during link switching. The STA can reselect an appropriate link based on the received information and request a link change or reconnection from the AP MLD. The request message may include information about the AP to which the STA wishes to reconnect and information about the link to which the STA wishes to reconnect. Upon receiving the request message, the AP MLD may send an "Accept" response message to accept the request, or a "Reject" response message to reject the request.

[0351] When the request is accepted, the AP may perform frame exchange with the AP through the newly selected link from the time after sending the response message. When the request is rejected, the STA may use the existing connected link as it is.

[0352] 3) General approach

[0353] According to a general method, a non-AP MLD can request a link change or reconnection based on the information currently held by the non-AP MLD without requesting additional information. The information used may include information about the AP MLD and information about the non-AP MLD (e.g., STR capability information and link status (enabled / disabled) information about each link) included in a previously received beacon or management frame.

[0354] Unlike the request method, a STA can directly send a link change or reconnection request message to the AP MLD, without having to separately request information from the AP MLD. The request message may include information about the AP to which the STA wishes to reconnect and information about the link to which the STA wishes to reconnect. Upon receiving the request message, the AP MLD may send an "Accept" response message to accept the request, or a "Reject" response message to reject the request.

[0355] When the request is accepted, the AP may perform frame exchange with the AP through the newly selected link from the time after sending the response message. When the request is rejected, the STA may use the existing connected link as it is.

[0356] Please refer to Figure 26 Specific examples of the operations of AP MLD and non-AP MLD according to the general method are described.

[0357] Figure 26 The operations of AP MLD and non-AP MLD for link change or reconnection are shown.

[0358] Reference Figure 26 To ensure QoS, STA 2 may want to change the link directly. When STA 2 has previously received information from the AP MLD (e.g., information received through a beacon frame or a management frame) or has already determined the link to which STA 2 wants to reconnect, STA 2 can request a link change or reconnection without separately requesting additional information.

[0359] STA 2 may transmit a link switching request frame including STA information (e.g., STA ID) and information about the link to which STA 2 wishes to switch (e.g., link ID or AP BSS information). Upon receiving this frame, AP MLD may transmit a link switching response frame "Accept" to STA 2 via the existing link 2 to accept the change. STA 2, which is not an AP MLD, may then perform a link (re)establishment process and reconnect to AP 3.

[0360] Signaling for indicating link change and reconnection methods

[0361] In order to indicate the method proposed above, a mutual agreement process through negotiation between the AP MLD and the non-AP MLD may be required. To this end, in the following description, a signaling method for implementing the method to be proposed may be proposed.

[0362] First, in order to indicate the method proposed above, a new element may be proposed. Hereinafter, an embodiment of signaling for indicating a link change and reconnection method is described, and this embodiment may also be applied to an embodiment of signaling for indicating an anchor link change and reconnection method.

[0363] The signaling process for indicating the link change and reconnection method can be performed during or after the multi-link establishment. In addition, the new elements proposed below can be used in the signaling process for indicating the link change and reconnection method. For example, the elements can be included in the (re)association frame of the traditional standard or the new frame.

[0364] Information Acquisition Methods (IOM) capability elements

[0365] The IOM Capability element may include information regarding whether a method for obtaining additional information about multilinks is permitted. For example, in a process in which the AP MLD and non-AP MLD exchange messages to agree on operations in a multilink establishment process (e.g., a capability negotiation process), an IOM Capability value may be present in an element within the message. The IOM Capability value present in the element within the message may indicate support for the IOM capability.

[0366] According to an embodiment, when an AP MLD supports IOM capability, information about other APs can be shared with the AP internally, and the AP can have information about other APs. An MLD that does not share information about other APs cannot support IOM capability.

[0367] According to an embodiment, when the value of the IOM capability element is set to a first value (e.g., 1), the IOM capability element may indicate that the IOM is enabled and the indicated function is operating. When the value of the IOM capability element is set to a second value (e.g., 0), the IOM capability element may indicate that the IOM is disabled.

[0368] Depending on the implementation, the IOM Capability element may include various fields / elements to indicate various operations. For example, the IOM Capability element may include the various fields / elements described below. However, the fields / elements added to the IOM Capability element may be configured differently depending on whether an AP MLD requests a link change or a non-AP MLD requests a link change. Furthermore, at least some fields / elements added to the IOM Capability element may be omitted. For example, fields / elements added to the IOM Capability element that include information that does not need to be indicated may be omitted.

[0369] Hereinafter, examples of various fields / elements defined / configured to obtain additional information about multilinks may be described. The various fields / elements described below may be configured independently, or two or more fields / elements may be combined and sent through various frames. For example, the various fields / elements described below may be included in other elements to perform defined operations. In another example, the various fields / elements described below may be used as separate elements or as independent fields added to other elements.

[0370] Method Type (or Method) Field / Element

[0371] The method type field / element (hereinafter, the method field / element) may include information about the IOM's operating method. In other words, the method field / element may indicate the IOM's operating method. For example, when the non-AP MLD enables the IOM to obtain information from the AP, the non-AP MLD may select and indicate the method to be used from among the methods mentioned above (e.g., the request method, the unsolicited method, and the general method).

[0372] For example, if the value of the method field / element is a first value (e.g., 0), a request method may be indicated or used. If the value of the method field / element is a second value (e.g., 1), a non-request method may be indicated or used. If the value of the method field / element is a third value (e.g., 2), a general method may be indicated or used. If the value of the method field / element is a fourth value (e.g., 3), both a request method and a non-request method may be indicated or used.

[0373] In another example, one bit may be used for the method field / element. In this case, if the value of the method field / element is a first value (e.g., 0), it may be indicated that a request method is used. If the value of the method field / element is a second value (e.g., 1), it may be indicated that a non-request method is used.

[0374] In another example, two bits can be used for the method field / element. In this case, the methods can be indicated as being used independently or in combination.

[0375] Link scope fields / elements

[0376] When non-AP MLD requests information from AP MLD, non-AP MLD may indicate the requested link range through the Link Range field / element. The Link Range field / element may include information about whether STA wants to request information about all links in AP MLD or some links in AP MLD.

[0377] For example, when the value of the Link Range field / element is a first value (e.g., 0), the Link Range field / element may indicate that information about all links in the AP MLD is requested. When the value of the Link Range field / element is a second value (e.g., 1), the Link Range field / element may indicate that information about some links in the AP MLD is requested.

[0378] Here, when the value of the link range field / element is a first value (e.g., 0) (request for all links in the AP MLD), separate link indicator information (e.g., the "Link Condition" field) is not required. When the value of the link range field / element is a second value (e.g., 1) (request for information about some links in the AP MLD), link indicator information is required.

[0379] Information scope fields / elements

[0380] When a non-AP MLD requests information, the Information Scope field may be used to indicate the scope of the information.

[0381] For example, when the value of the Information Range field is a first value (e.g., 0), the Information Range field may indicate that only partial information owned by the AP is provided. When the value of the Information Range field is a second value (e.g., 1), the Information Range field may indicate that complete information (or all information) owned by the AP is provided.

[0382] Depending on the implementation, the Information Range field may be defined to indicate a request for all or some of the information (elements) held by the AP, but a STA may request more detailed information using additional subfields. For example, a subfield indicating the scope of information to be provided (e.g., all or some information) may be included in the Information Range field. For example, the subfield indicating the scope of information to be provided may be defined / configured as a All / Part subfield.

[0383] According to an embodiment, a subfield for indicating whether to receive all information or only changed information among all information may be newly proposed. In other words, the newly proposed subfield may indicate whether to receive all information or only changed information among all information.

[0384] For example, a subfield for indicating whether to receive all information or only changed information among all information may be defined / configured as an update-only subfield.

[0385] When the STA wishes to receive only changed information, the Update Only subfield can be set to 1. In other words, when the STA wishes to receive only changed information, the STA can set the Update Only subfield to 1. For example, according to a request method, when the Update Only subfield is set to 1, the AP (or AP MLD) can transmit only changed information (i.e., updated information) among the requested information when the STA requests information. In another example, according to a non-request method, when the Update Only subfield is set to 1, the AP can notify the STA of only changed information within the set information range.

[0386] Although the above example proposes that the update-only subfield in the information range field is used to receive only changed information, the present specification is not limited thereto and a separate field or element may be defined / configured to receive only changed information.

[0387] According to the above embodiment, the range of information that STAs are allowed to request can be set to updated information or all information. In this case, STAs that do not want high frame overhead can request to receive only changed information. Therefore, overhead can be reduced.

[0388] Link Condition Fields / Elements

[0389] The Link Condition field may be used to indicate the specific link being requested. In other words, the Link Condition field may include information about the specific link being requested. The Link Condition field may be used when the STA wishes to receive only specific link information from the AP.

[0390] The link condition field may be indicated by a link identifier (e.g., link ID or BSSID). In other words, the link condition field may include information about the link identifier (e.g., link ID or BSSID). In other words, the link identifier may be used to specify the link for obtaining information.

[0391] For example, if a STA connected to link 1 wishes to request only information about links 2 and 3 from the AP, the STA can request this information by specifying links 2 and 3 in the Link Condition field. For example, when the value of the Information Range field is 1, all information corresponding to links 2 and 3 may be transmitted. In another example, when the value of the Information Range field is 0, partial information about links 2 and 3 specified by the STA may be transmitted. Depending on the embodiment, the partial information specified by the STA may be determined by the following Information Condition field.

[0392] According to an embodiment, when the link condition field has no value or has a value of 0, the AP may determine that there is no link condition. Therefore, the AP may provide / transmit information on all links to the STA.

[0393] Information Condition Fields / Elements

[0394] The information condition field may be used to indicate the specific type of information requested. In other words, the information condition field may be used when the STA wants to receive only specific information from the AP.

[0395] For example, the information condition field may be used only when the information range field is set to 0. In another example, the STA may use the information condition field to indicate specific information even when the information range field does not exist.

[0396] For example, in the information condition field, information that the STA can specify (eg, BSS load or STR capability) can be indicated by a bitmap. For example, the type of information provided by the AP and its indication method or order (bits) can be set differently.

[0397] According to an embodiment, the information condition field may be used together with the link condition field. According to an embodiment, the information condition field may send information of various requested conditions to the STA (or AP) based on a combination of various fields / elements.

[0398] According to an embodiment, fields / elements defined / configured to obtain additional information about multilinks are not limited to the above-mentioned fields / elements, and various fields / elements may be further configured.

[0399] Therefore, the MLD (AP MLD or non-AP MLD) can indicate the IOM capability through negotiation between the AP MLD and the non-AP MLD using at least one of the above elements / fields during the multi-link establishment process. In addition, the MLD can update the agreement between the MLDs through a separate message exchange after the multi-link establishment is completed.

[0400] According to an embodiment, when the IOM capability is enabled, AP MLD and non-AP MLD may operate based on the embodiment of link change and reconnection.

[0401] The following describes an example of the operations of the AP MLD and non-AP MLD when the IOM capability is enabled. For example, the non-AP MLD can request additional multilink information by sending the aforementioned fields / elements to the AP MLD. The non-AP MLD can send an IOM Capability element including the aforementioned fields / elements to the APMLD. The aforementioned fields / elements included in the IOM Capability element are for illustrative purposes only; the fields / elements may also be sent as independent fields / elements.

[0402] For example, during the multi-link establishment process, the non-AP MLD may send an IOM capability element including "Method field = 0" and "Information range field = 1" to the AP MLD, and may reach an agreement with the AP MLD. In this case, after the multi-link is established, the non-AP MLD operates according to the request method and, when requesting information, may request multi-link information including all information included in the beacon (e.g., information about other APs). Therefore, only when receiving a request message from the STA can the AP MLD provide / send information about the link via a response message. Upon receiving the request message, the AP MLD may send a response message including information about all links in the AP MLD to the STA. The information about all links in the AP MLD may include all information included in the beacon.

[0403] In another example, the non-AP MLD may send an IOM Capability Element including "Method Field = 1," "Information Range Field = 0," "Link Range = Link ID 2," and "Information Condition Field = (a bitmap indicating a value for BSS load)" to the AP MLD, and may reach an agreement with the AP MLD. In this case, after multi-link establishment, the non-AP MLD may operate according to the unsolicited method. Therefore, the AP can send BSS load information for Link 2 to the STA via a separate message without receiving a separate request message.

[0404] Depending on the implementation, AP MLD and non-AP MLD can implement the proposed IOM during or after the multi-link establishment process through the signaling method proposed in this specification. In addition, AP MLD and non-AP MLD can limit the scope and type of requested information through various field values ​​in the IOM capability element.

[0405] According to an embodiment, IOM operations can be performed after precise operation negotiation between MLDs using the aforementioned IOM signaling method. However, IOM operations can also be performed by MLD implementations without requiring separate signaling processing. That is, operations can be performed by APMLD implementations or by non-AP MLD implementations without requiring negotiation between the AP MLD and the non-AP MLD.

[0406] AP MLD and non-AP MLD may operate based on the above-described embodiments. However, when MLD performs IOM operations without separate signaling exchanges, the following constraints may occur.

[0407] 1) Constraints on the request method: When information sharing is not supported between APs of AP MLD, it is impossible to respond when a STA requests information about another link.

[0408] 2) Constraints on the unsolicited method: The AP may provide a separate message by autonomously determining which STAs require additional link information (e.g., beacon period). Therefore, the STA cannot predict in advance whether the STA will receive the information.

[0409] When MLD implements IOM without a separate signaling method, the operational process may be simplified, while the above-mentioned constraints may occur.

[0410] Implementation of anchor link changes and reconnections

[0411] Depending on the implementation, AP MLD may support anchor links. When AP MLD supports anchor links, additional considerations are taken into account in the above implementations of link change and reconnection.

[0412] The AP MLD may support one or more anchor links and may provide information about one or more anchor links to the non-AP MLD via the anchor link list information / element. The non-AP MLD may select and use one or more links in the anchor link list as its anchor links. Links other than those selected as anchor links may operate as non-anchor links.

[0413] There is a trade-off between power consumption and data load between anchor links and non-anchor links. Specifically, when non-AP MLD uses a single anchor link, power consumption can be reduced, but QoS for data transmission (particularly data in beacon and management frames) cannot be guaranteed. However, when using multiple anchor links, QoS for data transmission can be guaranteed, while power reduction can be reduced.

[0414] Therefore, non-AP MLD needs to be able to dynamically request reselection of the anchor link for efficient data exchange. In the following, an embodiment in which non-AP MLD dynamically requests anchor link change / reselection may be proposed.

[0415] First, refer to Figure 27 Describes the MLD structure that supports anchor links.

[0416] Figure 27 An example of an MLD structure supporting anchor links is shown.

[0417] Reference Figure 27 , AP MLD can use two of the five links (i.e., AP 1 and AP 4) as anchor links. Non-AP MLD can use one anchor link by selecting Link 1 from the two links used as anchor links. The remaining links of the non-AP MLD can be connected to non-anchor links (Link 2 and Link 3). In other words, non-AP MLD needs to always monitor Link 1 to receive beacons and management frames.

[0418] According to an embodiment, for load balancing, etc., STA 1 may request to change the previously used anchor link from the anchor link of AP 1 to the anchor link of AP 4. To change the anchor link, the above-described embodiments related to link switching may be applied.

[0419] However, a limited number of links among those supported by the AP MLD are supported as anchor links. Therefore, the AP MLD may have a separate anchor link list. A non-AP MLD (or STA) must select a link included in the anchor link list and request a change or reconnection to it. Furthermore, a non-AP MLD must have at least one anchor link, so when requesting a link change or reconnection, this consideration must be taken into account when requesting an anchor link change.

[0420] For the above embodiment, the AP MLD needs to provide the non-AP MLD with "anchor link list" information. This information can be included in the frame as a new element or field. The term "anchor link list" is for illustration and can be set / expressed differently.

[0421] - "anchor link list" (element / field) : A list of anchor links currently supported by the AP MLD. For example, the list of anchor links currently supported by the APMLD may be indicated / set by one or more link IDs or AP BSS values. Non-APMLDs are required to connect to at least one anchor link included in the list.

[0422] The above information (eg, "anchor link list" (element / field)) may be included in an existing beacon or management frame and transmitted, or may be included in an information response message according to a request method and transmitted to the non-AP MLD.

[0423] Therefore, when a non-AP MLD requests to change the anchor link used by the non-AP MLD, the non-AP MLD needs to know the currently supported anchor link list in advance. If the non-AP MLD does not know the anchor link list or wants to obtain the latest information, the non-AP MLD can obtain the information from the AP MLD according to the request method.

[0424] The STA may request to change or reconnect to only one link in the anchor link list based on the anchor link list information. When the STA requests to change or reconnect to another link not included in the list, the AP MLD may send a rejection message to the STA.

[0425] When changing or reconnecting the anchor link, additional considerations must be taken into account in addition to existing link change methods. There are two general cases where a non-AP MLD STA changes the anchor link.

[0426] In the first case, a STA already connected to an anchor link changes to another anchor link of the AP MLD for load balancing, etc. (AP change of anchor link). In the second case, a STA connected to the anchor link is disabled due to a power status, etc., so another STA other than the AP MLD reconnects to the anchor link (STA change of anchor link).

[0427] The first scenario can operate similarly or identically to the above-mentioned embodiments of link change and reconnection. Here, when the STA reselects a link, it needs to select a link from the list of anchor links supported by the AP MLD. When another link is selected, the AP MLD may send a rejection response message.

[0428] The second case requires additional considerations. Figure 28 An example describing the second case is given.

[0429] Figure 28 An example of a situation where an anchor link change or reconnection is required is shown.

[0430] Reference Figure 28 , a non-AP MLD STA may have a status of STA 1 that is disabled for various reasons (eg, power off). Here, since both STA 2 and STA 3 are currently connected to a non-anchor link, one of the STAs needs to reconnect to the anchor link.

[0431] like Figure 28 As shown, when the non-AP MLD needs to reconnect to the anchor link, the non-AP MLD may attempt to reconnect one of STA 2 and STA 3 to the anchor link.

[0432] For example, when the non-AP MLD has information on the anchor link list supported by the AP MLD, the non-AP MLD may select a suitable link to request a link change.

[0433] In another example, when the non-AP MLD does not have information on the anchor link list supported by the AP MLD, the non-AP MLD may obtain information from the AP MLD through an information request and may then select a suitable link to request a link change.

[0434] Please refer to Figure 29 A specific example of the operations of the AP MLD and the non-AP MLD according to the above embodiment will be described.

[0435] Figure 29 The operations of AP MLD and non-AP MLD for anchor link change or reconnection are shown.

[0436] Reference Figure 29When STA 1 connected to the anchor link is disabled, non-AP MLD requires a new connection to the anchor link. Here, non-AP MLD may disconnect STA 3 from the non-anchor link previously connected to AP 3 and may attempt to reconnect STA 3 to the anchor link.

[0437] For example, STA 3 may attempt to connect to AP 1, which serves as an existing anchor link. In another example, STA 3 may attempt to connect to a new AP 4 based on various information.

[0438] The process of selecting a new anchor link can be performed in the same or similar manner as in the above-described embodiments of link change or reconnection. For example, STA 3 can request reconnection by selecting an anchor link recommended by the AP or by directly selecting an anchor link. After completing reconnection to the anchor link, STA 3's link can operate as the anchor link.

[0439] Elements / fields containing information about anchor links

[0440] According to an embodiment, when information about an anchor link supported by the AP MLD changes or the STA directly requests information about the anchor link, the AP MLD may transmit the information (i.e., information about the change of the anchor link or information about the anchor link requested by the STA) to the non-AP MLD.

[0441] For example, the information may be information about the anchor link currently in use, and may be included in a beacon frame and transmitted, or may be included in a separate management frame and transmitted.

[0442] The information on the anchor link may include the above-mentioned "anchor link list" element indicating the anchor links supported by the AP MLD and information on whether the anchor link is for each STA other than the AP MLD.

[0443] Hereinafter, a new element including the above-mentioned information about the anchor link may be proposed. The newly proposed element may be configured / set as follows.

[0444] 1) "Anchor Link Indication" element (or field) The "Anchor Link Indication" element may include information on whether the anchor link is used for all STAs connected to the AP MLD. That is, the "Anchor Link Indication" element may be an element / field indicating whether the anchor link is used for each link or each STA of a non-AP MLD.

[0445] 2) "Per-anchor link STA ratio" element (or field)The "STA Ratio Per Anchor Link" element may include information regarding the ratio or number of STAs connected to each anchor link. Here, only STAs using a link as an anchor link may be considered. In other words, even if AP MLD supports the first link as an anchor link, STAs using the first link as a non-anchor link may not be included in the STAs connected to each anchor link.

[0446] According to an embodiment, in any process of the above-described embodiments in which an anchor link is changed or reconnected, an element may be included in a frame as additional information, if necessary.

[0447] Please refer to Figure 30 and Figure 31 Describes a specific example of an element.

[0448] Figure 30 and Figure 31 Specific examples of elements used for anchor link reconnection are shown.

[0449] Reference Figure 30 and Figure 31 Information about the anchor link can be sent via an anchor link list element (or field), an anchor link indication element (or field), and / or a per-anchor link STA ratio element (or field). In other words, the anchor link reconnection element may include an anchor link list element (or field), an anchor link indication element (or field), and / or a per-anchor link STA ratio element (or field).

[0450] Depending on the embodiment, the anchor link list element may include information regarding the list of links currently supported by the AP MLD, as described above. For example, the information regarding the list of links currently supported by the AP MLD may be indicated based on link IDs or AP BSS information. In other words, the list of links currently supported by the AP MLD may be configured / set based on link IDs or AP BSS information.

[0451] According to an embodiment, the anchor link indication element may include information about whether the anchor link is used for each STA of non-AP MLD. For example, the information about whether the anchor link is used for each STA of non-AP MLD may be indicated / specified for each link through an indication bitmap. (i.e., Figure 28 In another example, a bitmap may be used to indicate / specify whether the anchor link is used for all STAs. (i.e., Figure 29 ).

[0452] For example, when using an indication bitmap based on the link ID to indicate whether an anchor link is used, the STA can identify the current anchor link based on the value of the anchor link list element. This allows the STA to identify the ratio of STAs connected to each anchor link. The indication bitmap field for non-anchor links can be omitted to reduce overhead.

[0453] When a bit in the bitmap has a value of 1, it may indicate that the link currently connected to the STA is an anchor link. When a bit in the bitmap has a value of 0, it may indicate that the link currently connected to the STA is a non-anchor link. The embodiment of using a bitmap to indicate whether each STA is connected to an anchor link is for illustration purposes only. Information regarding whether each STA is connected to an anchor link may be transmitted in various embodiments.

[0454] Depending on the implementation, the ratio of STAs for all links supported by the AP MLD may be sent. Depending on the implementation, the Per-Anchor-Link-STA-Ratio element may include information regarding the ratio or number of STAs using each anchor link as the actual anchor link. For example, this information may be indicated only for the anchor links indicated / specified in the Anchor-Link-List element, thereby reducing overhead.

[0455] An example of setting the value of the per-anchor-link STA ratio element may be described below.

[0456] For example, the AP MLD may include five APs (i.e., AP 1 to AP 5), and AP 1 may be connected to the STA via link 1. AP 2 may be connected to the STA via link 2. AP 3 may be connected to the STA via link 3. AP 4 may be connected to the STA via link 4. AP 5 may be connected to the STA via link 5.

[0457] AP MLD can support two links among five links (ie, link 1 to link 5) as anchor links. Link 1 and link 4 can be supported / used as anchor links.

[0458] A total of 10 STAs are connected to link 1 (or AP 1), and seven STAs may use link 1 as an anchor link, which may be expressed / represented as 70% in terms of a ratio and as 7 in terms of a value.

[0459] A total of 20 STAs are connected to link 4 (or AP 4), and five STAs may use link 4 as an anchor link, which may be expressed as 25% in terms of ratio and as 5 in terms of value.

[0460] The per-anchor-link STA ratio element can be sent along with the per-link STA ratio element information above, thus providing more accurate information to STAs. Generally, since anchor links can have more data traffic than non-anchor links, the per-anchor-link STA ratio element can be used as useful information for STAs to reselect anchor links.

[0461] The non-AP MLD may identify whether the link to which the non-AP MLD is connected is an anchor link, the ratio of STAs connected to each anchor link, and the ratio of STAs actually using the anchor link based on the above information (or elements).

[0462] In addition, when the AP MLD transmits information about other links (i.e., all links) using the above elements, the STA can identify the ratio of STAs connected to all anchor links of the AP MLD and the ratio of STAs actually using all anchor links based on a single frame. Therefore, the above information (or elements) can be used when reselecting an anchor link to be used by the STA.

[0463] Therefore, according to an embodiment of anchor link change or reselection, it is possible to change or reconnect to a more appropriate anchor link by using not only the various link information used in the embodiment of link change or reselection (for example, BSS load information of each AP or STR capability information of each link) but also the above-mentioned information about the anchor link (for example, anchor link list information, information indicating whether the anchor link is used for each STA, or information about the ratio of STAs actually using each anchor link).

[0464] Figure 32 is a flow chart illustrating the operation of a multi-link device.

[0465] Reference Figure 32 In operation S3210, the multi-link device may receive the PPDU through a first link among a plurality of links. For example, the plurality of links may be included in 2.4 GHz, 5 GHz, and 6 GHz frequency bands.

[0466] For example, a multi-link device may be connected to an AP through multiple links including a first link and a second link. The multi-link device may include multiple STAs associated with the multiple links. The multi-link device may include a first STA and a second STA.

[0467] For example, a first STA among a plurality of STAs may be connected to a first link. In other words, the first STA may operate in the first link. In addition, the first STA may be connected to a first AP of an AP multi-link device via the first link.

[0468] For example, a second STA among the plurality of STAs may be connected to the second link. In other words, the second STA may operate in the second link. In addition, the second STA may be connected to the second AP of the AP multi-link device via the second link.

[0469] According to an embodiment, the PPDU may include a first information field related to a second link different from the first link among the plurality of links. The first information field may include information about the second link.

[0470] For example, the first information field related to the second link may include a second information field related to a link identifier of the second link and a third information field related to whether the complete element information for the second link is included in the PPDU.

[0471] The second information field may include four bits. The second information field may include link identifier (ID) information about the second link. The link identifier of the second link may be set to four bits. The second information field may include a link ID field.

[0472] The third information field may include one bit. The third information field may be set to a first value. For example, based on the third information field being set to the first value (e.g., 1), the multi-link device may recognize that complete element information for the second link is included in the PPDU. In another example, based on the third information field being set to a second value (e.g., 0), the multi-link device may recognize that partial element information about the second link is included in the PPDU. The third information field may include a complete profile field.

[0473] According to an embodiment, the complete element information for the second link can be configured based on the type of PPDU. In other words, the complete element information included in the PPDU can vary depending on the type of PPDU. For example, the element information that can be included in a probe request frame can be set / defined. In another example, the element information that can be included in a (re)association response frame can be set / defined. Therefore, when the PPDU is a probe request frame, the multi-link device can identify whether all element information that can be included in the probe request frame is included in the PPDU based on the third information field.

[0474] According to an embodiment, the PPDU may further include a fourth information field related to a third link among the multiple links. The fourth information field may include a fifth information field related to a link identifier of the third link and a sixth information field related to whether the complete element information of the third link is included in the PPDU.

[0475] According to an embodiment, the multi-link device may transmit a second PPDU for requesting complete element information for the second link, and may receive a PPDU including the first information field based on the second PPDU.

[0476] In operation S3220, the multi-link device may obtain complete element information for the second link based on the second information field and the third information field.

[0477] According to an embodiment, the first link may operate as an anchor link and the second link may operate as a non-anchor link.

[0478] For example, the multi-link device may change the link operating as the anchor link from the first link to the second link based on the complete element information for the second link. In one example, the multi-link device may identify traffic load information about the second link. The multi-link device may transmit a frame (or PPDU) for changing the link operating as the anchor link from the first link to the second link based on the traffic load information about the second link.

[0479] Figure 33 is a flowchart illustrating the operation of an AP multi-link device.

[0480] Reference Figure 33 In operation S3310, the AP multi-link device may generate a PPDU. For example, the multiple links may be included in 2.4 GHz, 5 GHz, and 6 GHz frequency bands.

[0481] For example, the AP multi-link device may be connected to the multi-link device via multiple links including a first link and a second link. The AP multi-link device may include multiple APs associated with the multiple links. The AP multi-link device may include a first AP and a second AP.

[0482] For example, a first AP among a plurality of APs may be connected to a first link. In other words, the first AP may operate in the first link. In addition, the first AP may be connected to a first STA of the multi-link device through the first link.

[0483] For example, a second AP among the plurality of APs may be connected to the second link. In other words, the second AP may operate in the second link. In addition, the second AP may be connected to the second STA of the multi-link device via the second link.

[0484] According to an embodiment, the PPDU may include a first information field related to a second link different from the first link among the plurality of links. The first information field may include information about the second link.

[0485] For example, the first information field related to the second link may include a second information field related to a link identifier of the second link and a third information field related to whether the complete element information for the second link is included in the PPDU.

[0486] The second information field may include four bits. The second information field may include link identifier (ID) information about the second link. The link identifier of the second link may be set to four bits. The second information field may include a link ID field.

[0487] The third information field may include one bit. The third information field may be set to a first value. For example, the AP multi-link device may set the third information field to a first value (e.g., 1) to indicate that complete element information for the second link is included in the PPDU. In another example, the AP multi-link device may set the third information field to a second value (e.g., 0) to indicate that partial element information about the second link is included in the PPDU. The third information field may include a complete profile field.

[0488] According to an embodiment, the complete element information for the second link can be configured based on the type of PPDU. In other words, the complete element information included in the PPDU can change depending on the type of PPDU. For example, the element information that can be included in the probe request frame can be set / defined. In another example, the element information that can be included in the (re)association response frame can be set / defined. Therefore, when the PPDU is a probe request frame, the AP multi-link device can transmit a PPDU including a third information field indicating whether all element information that can be included in the probe request frame is included in the PPDU.

[0489] According to an embodiment, the PPDU may further include a fourth information field related to a third link among the multiple links. The fourth information field may include a fifth information field related to a link identifier of the third link and a sixth information field related to whether the complete element information of the third link is included in the PPDU.

[0490] According to an embodiment, the AP multi-link device may receive a second PPDU for requesting complete element information for the second link, and may transmit a PPDU including the first information field based on the second PPDU.

[0491] In operation 3320, the AP multi-link device may transmit a PPDU via a first link among a plurality of links. For example, the first link may operate as an anchor link. The second link may operate as a non-anchor link. The AP multi-link device may transmit a PPDU including information about the second link via the first link serving as the anchor link.

[0492] The above technical features of this specification can be applied to various devices and methods. For example, the above technical features of this specification can be applied to various devices and methods. Figure 1 and / or Figure 14 For example, the above technical features of this specification can only be applied to Figure 1 and / or Figure 14For example, the above technical features of this specification can be based on Figure 1 The processing chips 114 and 124 can be implemented based on Figure 1 The processors 111 and 121 and the memories 112 and 122 can be implemented, or can be based on Figure 14 The processor 610 and the memory 620 of the present specification are implemented. For example, the device of the present specification may include a processor and a memory connected to the processor, wherein the processor may be configured to: generate a PPDU, the PPDU including a first information field related to a second link different from the first link among a plurality of links, and the first information field related to the second link including a second information field related to a link identifier of the second link and a third information field related to whether the complete element information for the second link is included in the PPDU; and transmit the PPDU through a first link among the plurality of links.

[0493] The technical features of this specification may be implemented based on a computer-readable medium (CRM). For example, the CRM proposed in accordance with this specification may be encoded using at least one computer program comprising instructions. When executed by at least one processor, the instructions may cause the at least one processor to perform operations including: receiving a physical layer protocol data unit (PPDU) through a first link among a plurality of links, the PPDU including a first information field related to a second link among the plurality of links that is different from the first link, and the first information field related to the second link including a second information field related to a link identifier of the second link and a third information field related to whether the complete element information for the second link is included in the PPDU; and obtaining the complete element information for the second link based on the second information field and the third information field. The instructions stored in the CRM of this specification may be executed by at least one processor. The at least one processor associated with the CRM of this specification may be Figure 1 The processors 111 and 121 or the processing chips 114 and 124 may be Figure 14 The CRM of this specification may be Figure 1 The memories 112 and 122 may be Figure 14 The memory 620 may be a separate external memory / storage medium / disk.

[0494] The above technical features of this specification are applicable to various applications or business models. For example, the above technical features can be applied to wireless communications of devices supporting artificial intelligence (AI).

[0495] Artificial intelligence refers to the field of study concerning artificial intelligence or methods for creating it, while machine learning refers to the field of study concerning methods for defining and solving various problems within the field of artificial intelligence. Machine learning is also defined as algorithms that improve operational performance through consistent operational experience.

[0496] An artificial neural network (ANN) is a model used in machine learning and can refer to an overall problem-solving model that includes artificial neurons (nodes) that form a network by combining synapses. An artificial neural network can be defined by the connection pattern between neurons in different layers, the learning process that updates the model parameters, and the activation function that generates the output value.

[0497] An artificial neural network may include an input layer, an output layer, and optionally one or more hidden layers. Each layer includes one or more neurons, and the artificial neural network may include synapses connecting the neurons. In the artificial neural network, each neuron may output a function value of an activation function of an input signal, a weight, and a bias input through the synapse.

[0498] Model parameters are those determined by learning and include the weights of synaptic connections and the biases of neurons. Hyperparameters are those set in a machine learning algorithm before learning and include the learning rate, number of iterations, mini-batch size, and initialization function.

[0499] Learning an artificial neural network can be aimed at determining model parameters for minimizing a loss function. The loss function can be used as an index for determining the optimized model parameters during the learning process of the artificial neural network.

[0500] Machine learning can be categorized into supervised learning, unsupervised learning, and reinforcement learning.

[0501] Supervised learning refers to a method of training an artificial neural network with labels given to the training data, where the labels indicate the correct answer (or result value) that the artificial neural network needs to infer when the training data is input to the artificial neural network. Unsupervised learning refers to a method of training an artificial neural network without labels given to the training data. Reinforcement learning refers to a training method in which an agent defined in a training environment selects an action or action sequence to maximize the cumulative reward in each state.

[0502] Machine learning implemented using a deep neural network (DNN) including multiple hidden layers in an artificial neural network is called deep learning, and deep learning is a part of machine learning. Hereinafter, machine learning is explained as including deep learning.

[0503] The above technical features can be applied to wireless communication of robots.

[0504] A robot may refer to a machine that automatically processes or operates a given task with its own capabilities. Specifically, a robot that has the function of recognizing the environment and autonomously making judgments to perform operations may be called an intelligent robot.

[0505] Robots can be classified into industrial, medical, household, military, etc. according to their use or field. A robot may include an actuator or drive, which includes a motor to perform various physical operations (for example, moving the robot joints). In addition, a mobile robot may include wheels, brakes, propellers, etc. in the drive to travel on the ground or fly in the air.

[0506] The above technical features can be applied to devices that support augmented reality.

[0507] Extended reality collectively refers to virtual reality (VR), augmented reality (AR), and mixed reality (MR). VR technology is a computer graphics technology that presents real-world objects and backgrounds solely within CG images. AR technology is a computer graphics technology that presents virtual CG images over images of real objects. MR technology is a computer graphics technology that presents virtual objects that are mixed and combined with the real world.

[0508] MR technology is similar to AR technology in that real objects and virtual objects are displayed together. However, in AR technology, virtual objects are used as a supplement to real objects, while in MR technology, virtual objects and real objects are used as equals.

[0509] XR technology can be applied to head-mounted displays (HMDs), head-up displays (HUDs), mobile phones, tablet PCs, laptop computers, desktop computers, TVs, digital signage, etc. Devices to which XR technology is applied may be referred to as XR devices.

[0510] The claims described in this specification may be combined in various ways. For example, the technical features of the method claims in this specification may be combined to implement a device, and the technical features of the device claims in this specification may be combined to implement a method. Furthermore, the technical features of the method claims and the technical features of the device claims in this specification may be combined to implement a device, and the technical features of the method claims and the technical features of the device claims in this specification may be combined to implement a method.

Claims

1. A method performed by an access point (AP) multi-link device (MLD) operating multiple links in a wireless local area network system, the method comprising the following steps: Generate physical layer protocol data unit PPDU, The PPDU includes first information related to a second link among the multiple links that is different from the first link, The first information related to the second link includes second information related to a link identifier of the second link and third information related to whether complete element information for the second link or partial element information for the second link is included in the PPDU, and the third information has a length of one bit. wherein, for the complete element information, the third information has a value of 1, and for the partial element information, the third information has a value of 0; and The PPDU is sent via the first link.

2. The method according to claim 1, wherein The complete element information for the second link is set based on whether the PPDU is a probe request frame, an association response frame, or a reassociation response frame.

3. The method according to claim 1, wherein The first link operates as an anchor link, and the second link operates as a non-anchor link.

4. The method according to claim 3, further comprising the steps of: A link operating as the anchor link is changed from the first link to the second link based on the complete element information for the second link.

5. The method according to claim 1, wherein The plurality of links are included in one of a 2.4 GHz frequency band, a 5 GHz frequency band, and a 6 GHz frequency band.

6. An access point (AP) multi-link device (MLD) applied to a wireless local area network system and operating in multiple links, the AP MLD comprising: a transceiver that transmits and receives radio signals; as well as a processor connected to the transceiver, Wherein, the processor is configured to: Generate physical layer protocol data unit PPDU, The PPDU includes first information related to a second link among the multiple links that is different from the first link, The first information related to the second link includes second information related to a link identifier of the second link and third information related to whether complete element information for the second link or partial element information for the second link is included in the PPDU, and the third information has a length of one bit. wherein, for the complete element information, the third information has a value of 1, and for the partial element information, the third information has a value of 0; and The PPDU is sent via the first link.

7. The AP MLD according to claim 6, wherein: The processor is further configured to perform the steps of the method according to any one of claims 2 to 5.

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