Method and apparatus for changing a primary link belonging to a nstr link pair in a wlan system by an ml element

Abstract

A method and apparatus for changing a primary link belonging to a NSTR link pair by an ML element in a WLAN system are proposed. Specifically, a receiving MLD receives an ML element from a transmitting MLD via a first link. The receiving MLD decodes the ML element. The first link is a primary link, and a second link is a non-primary link. The first and second links are a link pair operating as NSTR. The ML element contains a common information field. The common information field includes first and second subfields. The first subfield includes information that the primary link is changed from the first link to the second link. The second subfield includes information about a time when the primary link is changed from the first link to the second link.

Description

Technical Field

[0001] This specification relates to multi-link operation in a wireless LAN system, and more specifically, to a method and apparatus for changing the primary link belonging to an NSTR link pair via an ML element. Background Technology

[0002] Wireless local area networks (WLANs) have been improved in various ways. For example, the IEEE 802.11ax standard proposes an improved communication environment using orthogonal frequency division multiple access (OFDMA) and downlink multiple user multiple input multiple output (DLMU MIMO) technologies.

[0003] This specification proposes technical features that can be utilized in new communication standards. For example, a new communication standard could be the currently discussed Extremely High Throughput (EHT) standard. The EHT standard could utilize newly proposed increased bandwidth, enhanced PHY layer Protocol Data Unit (PPDU) structures, enhanced sequencing, Hybrid Automatic Repeat Request (HARQ) schemes, etc. The EHT standard could be referred to as the IEEE 802.11be standard.

[0004] New wireless LAN standards may use an increased number of spatial streams. In this case, to properly utilize the increased number of spatial streams, it may be necessary to improve the signaling technology in the WLAN system. Summary of the Invention

[0005] Technical issues

[0006] This specification provides a method and apparatus for changing the primary link of an NSTR link pair in a WLAN system using ML elements.

[0007] Technical solution

[0008] The examples in this specification suggest a method for changing the primary link of an NSTR link pair using ML elements.

[0009] This embodiment can be implemented in a network environment that supports next-generation WLAN systems (IEEE 802.11be or EHT WLAN systems). Next-generation wireless LAN systems are WLAN systems enhanced from 802.11ax systems, and therefore can meet backward compatibility requirements with the 802.11ax systems.

[0010] This embodiment proposes a method and apparatus in which a transmitting MLD changes the primary link belonging to the NSTR link pair via the ML element. The primary link is the link that transmits and receives management frames, such as beacon frames or probe response frames, for discovery or association between the transmitting or receiving MLDs. The transmitting MLD is an NSTR soft access point (AP) MLD or an NSTR soft mobile AP and includes at least one NSTR link pair. Since the transmitting MLD must also be able to control at least one non-AP STA included in the receiving MLD, the at least one NSTR link pair must include the primary link. The received MLD may correspond to a non-AP MLD.

[0011] The receiving multilink device (MLD) receives multilink (ML) elements from the sending MLD via the first link.

[0012] The receiving MLD decodes the ML element.

[0013] The transmitting MLD includes a first transmitting station (STA) operating on the first link and a second transmitting STA operating on the second link. The receiving MLD includes a first receiving STA operating on the first link and a second receiving STA operating on the second link.

[0014] The first link is the primary link, and the second link is a non-primary link. The first and second links are a link pair operating in Non-Simultaneous Transmission and Reception (NSTR).

[0015] The ML element includes a public information field. The public information field includes a first subfield and a second subfield.

[0016] The first subfield includes information about the change of the primary link from the first link to the second link. The second subfield includes information about when the primary link changed from the first link to the second link.

[0017] That is, this embodiment proposes a method in which the transmitting MLD changes the primary link in a link pair that is an NSTR operation by defining the primary change subfield in the public information field of the ML element. The transmitting MLD is an NSTR soft AP MLD (or an NSTR mobile AP MLD), and the NSTR soft AP MLD is capable of changing the primary link because it depends on the channel quality or channel state having a significant impact on the link that is an NSTR operation.

[0018] Beneficial effects

[0019] According to the embodiments presented in this specification, first and second receiving STAs belonging to the receiving MLD associated with the transmitting MLD can flexibly identify the effects of changes in the main link. Therefore, link changes can be effectively performed based on the main change subfield included in the public information field of the ML element without additional overhead. Attached Figure Description

[0020] Figure 1 Examples of transmitting and / or receiving devices are shown in this specification.

[0021] Figure 2 This is a conceptual diagram illustrating the structure of a wireless local area network (WLAN).

[0022] Figure 3 The diagram illustrates the typical link establishment process.

[0023] Figure 4 The illustration shows an example of a PPDU used in IEEE standards.

[0024] Figure 5 An example of operation based on UL-MU is shown.

[0025] Figure 6 An example of a trigger frame is shown.

[0026] Figure 7 An example of the common information field of the trigger frame is shown.

[0027] Figure 8 Examples of subfields included in each user information field are shown.

[0028] Figure 9 The technical features of the UORA scheme are described.

[0029] Figure 10 An example of a PPDU used in this specification is shown.

[0030] Figure 11 Examples of transmitting and / or receiving devices modified in this specification are shown.

[0031] Figure 12 An example of the structure of STA MLD is shown.

[0032] Figure 13 The structure of the multi-link control field and public information field of the multi-link element is shown.

[0033] Figure 14 The structure of the existence bitmap subfield of the multi-link element is shown.

[0034] Figure 15 The structure of the Per-STA profile element is shown.

[0035] Figure 16 An example of how the main link changes the structure of a subfield is shown.

[0036] Figure 17 This is a flowchart illustrating the process of sending an MLD to change the primary link of an NSTR link pair according to this embodiment.

[0037] Figure 18 This is a flowchart illustrating the process of receiving information that the main link of the NSTR link pair has changed, according to this embodiment. Detailed Implementation

[0038] In this specification, "A or B" may mean "A only", "B only", 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 "A only", "B only", "C only", or "any combination of A, B, and C".

[0039] The forward slash ( / ) or comma used in this specification may mean "and / or". For example, "A / B" may mean "A and / or B". Therefore, "A / B" may mean "A only", "B only", or "both A and B". For example, "A, B, C" may mean "A, B, or C".

[0040] In this specification, "at least one of A and B" may mean "A only", "B only" or "both A and B". Additionally, 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".

[0041] Additionally, in this specification, "at least one of A, B, and C" may mean "A only", "B only", "C only" or "any combination of A, B, and C". Furthermore, "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".

[0042] Additionally, the parentheses used in this specification may mean "for example". Specifically, when indicated as "control information (EHT-signal)", it may mean that an "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 an "EHT-signal" may be proposed as an example of "control information". Furthermore, when indicated as "control information (i.e., EHT-signal)", it may also mean that an "EHT-signal" is proposed as an example of "control information".

[0043] The technical features described individually in one of the accompanying drawings of this specification may be implemented individually or simultaneously.

[0044] The examples in this specification can be applied to various wireless communication systems. For example, the examples in this specification can be applied to wireless local area network (WLAN) systems. For example, this specification can be applied to the IEEE 802.11a / g / n / ac standard or the IEEE 802.11ax standard. Additionally, this specification can also be applied to the newly proposed EHT standard or the IEEE 802.11be standard. Furthermore, the examples in this specification can also be applied to new WLAN standards enhanced from the EHT standard or the IEEE 802.11be standard. Additionally, the examples in this specification can be applied to mobile communication systems. For example, it can be applied to mobile communication systems based on Long Term Evolution (LTE) standards dependent on the 3rd Generation Partnership Project (3GPP) standards and LTE-based evolution. Furthermore, the examples in this specification can be applied to communication systems based on the 5G NR standard of the 3GPP standard.

[0045] In the following text, in order to describe the technical features of this specification, technical features that can be applied to this specification will be described.

[0046] Figure 1 Examples of transmitting and / or receiving devices are shown in this specification.

[0047] exist Figure 1 In the example, the various technical features described below can be implemented. Figure 1 This involves at least one station (STA). For example, STA 110 and 120 in this specification may also be referred to by various terms such as mobile terminal, wireless device, wireless transceiver unit (WTRU), user equipment (UE), mobile station (MS), mobile subscriber unit, or simply user. STA 110 and 120 in this specification may also be referred to by various terms such as network, base station, Node B, access point (AP), repeater, router, relay, etc. STA 110 and 120 in this specification may also be referred to by various names such as receiving device, transmitting device, receiving STA, transmitting STA, receiving apparatus, transmitting apparatus, etc.

[0048] For example, STA 110 and 120 can be used as an AP or a non-AP. That is, STA 110 and 120 of this specification can be used as an AP and / or a non-AP.

[0049] In addition to the IEEE 802.11 standard, STAs 110 and 120 in this specification can support various communication standards together. For example, they can support communication standards based on 3GPP standards (e.g., LTE, LTE-A, 5G NR standards). Furthermore, the STAs in this specification can be implemented in various devices such as mobile phones, vehicles, and personal computers. Additionally, the STAs in this specification can support various communication services such as voice calls, video calls, data communication, and autonomous driving.

[0050] The STA 110 and 120 of this specification may include media access control (MAC) conforming to the IEEE 802.11 standard and a physical layer interface for radio media.

[0051] The following will refer to Figure 1 The subgraph (a) is used to describe STA 110 and 120.

[0052] The first STA 110 may include a processor 111, a memory 112, and a transceiver 113. The illustrated processor, memory, and transceiver may be implemented as separate chips, or at least two blocks / functions may be implemented as a single chip.

[0053] The transceiver 113 of the first STA performs signal transmission / reception operations. Specifically, it can transmit / receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0054] For example, the first STA 110 can perform the operations expected by the AP. For example, the AP's processor 111 can receive signals via transceiver 113, process receive (RX) signals, generate transmit (TX) signals, and provide control over signal transmission. The AP's memory 112 can store signals received via transceiver 113 (e.g., RX signals) and can store signals to be transmitted via transceiver 113 (e.g., TX signals).

[0055] For example, the second STA 120 can perform operations not expected of an AP STA. For example, a non-AP transceiver 123 performs 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.).

[0056] For example, a non-AP STA processor 121 can receive signals via transceiver 123, process RX signals, generate TX signals, and provide control over signal transmission. A non-AP STA memory 122 can store signals received via transceiver 123 (e.g., RX signals) and can store signals to be transmitted via transceiver 123 (e.g., TX signals).

[0057] For example, the operation of a device designated as an AP in the description below can be performed in either the first STA 110 or the second STA 120. For instance, if the first STA 110 is an AP, the operation of the device designated as an AP can be controlled by the processor 111 of the first STA 110, and related signals can be transmitted or received via a transceiver 113 controlled by the processor 111 of the first STA 110. Additionally, control information related to the operation of the AP or the AP's TX / RX signals can be stored in the memory 112 of the first STA 110. Similarly, if the second STA 120 is an AP, the operation of the device designated as an AP can be controlled by the processor 121 of the second STA 120, and related signals can be transmitted or received via a transceiver 123 controlled by the processor 121 of the second STA 120. Furthermore, control information related to the operation of the AP or the AP's TX / RX signals can be stored in the memory 122 of the second STA 120.

[0058] For example, in the description below, the operation of a device indicated as a non-AP (or user STA) can be performed in either the first STA 110 or the second STA 120. For instance, if the second STA 120 is a non-AP, the operation of the device indicated as a non-AP can be controlled by the processor 121 of the second STA 120, and related signals can be transmitted or received via a transceiver 123 controlled by the processor 121 of the second STA 120. Additionally, control information related to the operation of a non-AP or non-AP TX / RX signals can be stored in the memory 122 of the second STA 120. Similarly, if the first STA 110 is a non-AP, the operation of the device indicated as a non-AP can be controlled by the processor 111 of the first STA 110, and related signals can be transmitted or received via a transceiver 113 controlled by the processor 111 of the first STA 110. Additionally, control information related to the operation of a non-AP or non-AP TX / RX signals can be stored in the memory 112 of the first STA 110.

[0059] In the following description, devices referred to as (transmit / receive) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmit / receive) terminal, (transmit / receive) device, (transmit / receive equipment), network, etc., may refer to... Figure 1 STAs 110 and 120. For example, devices designated as (but without specific labels) (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) terminal, (transmitting / receiving) device, (transmitting / receiving) equipment, network, etc., can implicitly refer to... Figure 1 STAs 110 and 120. For example, in the following example, the operation of various STA transmit / receive signals (e.g., PPDU) can be... Figure 1 This is performed in transceivers 113 and 123. Additionally, in the following examples, various STA operations for generating TX / RX signals or pre-performing data processing and calculations on TX / RX signals can be performed within these transceivers. Figure 1 The operations are executed in processors 111 and 121. Examples of operations for generating TX / RX signals or performing prior data processing and calculations may include: 1) operations to determine / obtain / configure / calculate / decode / encode bit information of subfields (SIG, STF, LTF, data) included in the PPDU; 2) operations to determine / configure / obtain time resources or frequency resources (e.g., subcarrier resources) for the subfields (SIG, STF, LTF, data) included in the PPDU; 3) operations to determine / configure / obtain 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 the STA; and 5) operations related to the determination / obtaining / configuration / decoding / encoding of the ACK signal. Additionally, 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 / decode the TX / RX signal may be stored in the STA's memory. Figure 1 In memory 112 and 122.

[0060] Figure 1 The aforementioned device / STA in subgraph (a) can be as follows Figure 1 The subgraph (b) is modified as shown below. In the following text, the modifications will be based on... Figure 1 The sub-diagram (b) is used to describe STA 110 and STA120 in this specification.

[0061] For example, Figure 1The transceivers 113 and 123 shown in subgraph (b) can perform operations with Figure 1 The transceiver shown in sub-diagram (a) has the same function as the aforementioned transceiver. For example, 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 sub-figure (b) can perform operations related to Figure 1 The processors 111 and 121 and the memories 112 and 122 shown in sub-figure (a) have the same functions.

[0062] The mobile terminal, wireless device, wireless transceiver unit (WTRU), user equipment (UE), mobile station (MS), mobile subscriber unit, user, subscriber 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 equipment and / or transmitting equipment described below may mean Figure 1 The STA 110 and 120 shown in subgraphs (a) / (b) may mean, or Figure 1 The processing chips 114 and 124 are shown in sub-figure (b). That is to say, the technical features of this specification can be found in... Figure 1 It can be performed in STA 110 and 120 as shown in subgraphs (a) / (b), or it can be performed only in... Figure 1 The processing chips 114 and 124 shown in sub-diagram (b) are executed Figure 1 Transceivers 113 and 123 are shown in sub-diagrams (a) and (b). For example, the technical features of transmitting control signals by the STA can be understood as being through... Figure 1 The transceiver 113 shown in sub-diagrams (a) / (b) transmits in Figure 1 The technical features of the control signals generated in processors 111 and 121 are illustrated in sub-figures (a) / (b). Alternatively, the technical features of the STA transmitting control signals can be understood as follows: Figure 1 The technical features of generating control signals to be transmitted to transceivers 113 and 123 in processing chips 114 and 124 are shown in sub-figure (b).

[0063] For example, the technical characteristics of receiving STA control signals can be understood as through... Figure 1 The technical features of transceivers 113 and 123 receiving control signals are shown in sub-figure (a). Alternatively, the technical features of receiving STA control signals can be understood as being achieved through... Figure 1 Processors 111 and 121 shown in subgraph (a) obtain Figure 1The technical features of the control signals received in transceivers 113 and 123 shown in sub-figure (a) are illustrated. Alternatively, the technical features of receiving control signals by the STA can be understood as being achieved through... Figure 1 The processing chips 114 and 124 shown in sub-figure (b) obtain Figure 1 Technical features of the control signals received in transceivers 113 and 123 as shown in sub-figure (b).

[0064] refer to Figure 1 Subgraph (b), software codes 115 and 125 can be included in memories 112 and 122. Software codes 115 and 125 can include instructions for controlling the operation of processors 111 and 121. Software codes 115 and 125 can be included in various programming languages.

[0065] Figure 1 The processors 111 and 121 or 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 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 can be made by The SNAPDRAGON™ processor series manufactured by The EXYNOS™ processor series manufactured by The processor series manufactured by The HELIO™ processor series manufactured by The ATOM™ series of processors manufactured or processors enhanced from these processors.

[0066] In this specification, uplink can mean a link used for communication from a non-AP STA to an SP STA, and uplink PPDUs / packets / signals, etc., can be transmitted through the uplink. Similarly, in this specification, downlink can mean a link used for communication from an AP STA to a non-AP STA, and downlink PPDUs / packets / signals, etc., can be transmitted through the downlink.

[0067] Figure 2 This is a conceptual diagram illustrating the structure of a wireless local area network (WLAN).

[0068] Figure 2The upper part of the diagram illustrates the structure of the Infrastructure Basic Services Set (BSS) of the Institute of Electrical and Electronics Engineers (IEEE) 802.11.

[0069] refer to Figure 2 The upper part of the wireless LAN system may include one or more infrastructures BSS200 and 205 (hereinafter referred to as BSS). BSS 200 and 205, as a set of APs and STAs (e.g., access point (AP) 225 and station (STA1) 200-1) that have successfully synchronized to communicate with each other, are not concepts indicating a specific area. BSS 205 may include one or more STAs 205-1 and 205-2 that can join an AP 230.

[0070] A BSS may include at least one STA, an AP that provides distributed services, and a distributed system (DS) 210 that connects multiple APs.

[0071] Distributed system 210 can implement an Extended Service Set (ESS) 240 that is expanded by connecting multiple BSSs 200 and 205. ESS 240 can be used as a term to refer to a network configured by connecting one or more APs 225 or 230 via distributed system 210. APs included in an ESS 240 can have the same Service Set Identifier (SSID).

[0072] Portal 220 can be used as a bridge to connect a wireless LAN network (IEEE 802.11) to another network (e.g., 802.X).

[0073] exist Figure 2 The BSS shown at the top allows for networking between APs 225 and 230, as well as between APs 225 and 230 and STAs 200-1, 205-1, and 205-2. However, it also allows for networking between STAs to perform communication even without APs 225 and 230. Networks that enable communication between STAs by configuring networks even without APs 225 and 230 are defined as self-organizing networks or Independent Basic Service Sets (IBSS).

[0074] Figure 2 The lower part of the diagram is a concept diagram, illustrating IBSS.

[0075] refer to Figure 2Below this, the IBSS operates as a BSS in a self-organizing mode. Since the IBSS does not include access points (APs), there is no centralized management entity performing management functions at the center. That is, 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 can be composed of mobile STAs, and access to DS to form a self-contained network is not permitted.

[0076] Figure 3 The diagram illustrates the typical link establishment process.

[0077] In S310, the STA can perform network discovery operations. Network discovery operations can include scanning operations by the STA. That is, in order to access a network, the STA needs to discover participating networks. The process of identifying compatible networks before joining a wireless network and identifying networks existing in a specific area is called scanning. Scanning methods include active scanning and passive scanning.

[0078] Figure 3 The diagram illustrates the network discovery process during an active scan. In an active scan, the STA performing the scan sends a probe request frame and waits for a response to it, in order to identify which APs are nearby while moving to a new channel. The responder sends a probe response frame to the STA that sent the probe request frame as a response. Here, the responder could be the STA in the BSS (Band of Service) of the channel being scanned that sent the last beacon frame. In the BSS, the AP is the responder because it sends the beacon frame. In the IBSS (Independent Broadband Switch), the responder is not fixed because the STAs in the IBSS take turns sending beacon frames. For example, when an STA sends a probe request frame via channel 1 and receives a probe response frame via channel 1, the STA can store the BSS-related information included in the received probe response frame, move to the next channel (e.g., channel 2), and perform a scan in the same way (e.g., sending a probe request and receiving a probe response via channel 2).

[0079] although Figure 3As not shown, scanning can be performed using a passive scanning method. In passive scanning, the STA performing the scan can wait for beacon frames while moving to a channel. Beacon frames are one of the management frames in IEEE 802.11 and are periodically sent to indicate the presence of a wireless network and enable the STA performing the scan to find and join the wireless network. In a BSS, the AP periodically sends beacon frames. In an IBSS, STAs in the IBSS take turns sending beacon frames. Upon receiving a beacon frame, the STA performing the scan stores information about the BSS included in the beacon frame and records the beacon frame information for each channel, while moving to another channel. The STA receiving the beacon frame can store the BSS-related information included in the received beacon frame, can move to the next channel, and can perform a scan on the next channel using the same method.

[0080] After network discovery, the STA can perform an authentication process in S320. This authentication process can 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 the STA sending an authentication request frame to the AP and the AP sending an authentication response frame to the STA in response. The authentication frame used for the authentication request / response is a management frame.

[0081] An authentication frame may include information about the authentication algorithm number, authentication transaction sequence number, status code, challenge text, robust security network (RSN), and finite cyclic group.

[0082] The STA can send an authentication request frame to the AP. The AP can determine whether to allow the STA's authentication based on the information included in the received authentication request frame. The AP can then provide the authentication processing result to the STA via an authentication response frame.

[0083] When a STA is successfully authenticated, it can perform an association process in S330. The association process includes the STA sending an association request frame to the AP, and the AP responding by sending an association response frame to the STA. For example, the association request frame may include information about various capabilities, beacon listening interval, service set identifier (SSID), supported rates, supported channels, RSN, mobile domain, supported operation classes, service indication map (TIM) broadcast request, and interoperability capabilities. Similarly, the association response frame may include information about various capabilities, status codes, association ID (AID), supported rates, enhanced distributed channel access (EDCA) parameter set, received channel power indicator (RCPI), received signal-to-noise ratio indicator (RSNI), mobile domain, timeout interval (association recovery time), overlapping BSS scan parameters, TIM broadcast response, and QoS map.

[0084] In the S340, the STA can perform a security establishment process. The security establishment process in the S340 may include the process of establishing a private key through a four-way handshake (e.g., via Extensible Authentication Protocol (EAPOL) frames over the LAN).

[0085] Figure 4 This diagram illustrates an example of a PPDU used in IEEE standards.

[0086] 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 the PSDU (MAC PDU / aggregated MAC PDU).

[0087] Figure 4 It also includes examples of HE PPDUs according to IEEE 802.11ax. Figure 4 The HE PPDU is an exemplary PPDU for multiple users. HE-SIG-B may be included only in PPDUs for multiple users, and HE-SIG-B may be omitted in PPDUs for single users.

[0088] like Figure 4 As illustrated, an HE-PPDU for multiple users (MUs) may include a conventional short training field (L-STF), a conventional long training field (L-LTF), a conventional 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 (or alternatively, a MAC payload), and a packet extension (PE) field. Each field can be transmitted within the indicated time period (i.e., 4 or 8 μs).

[0089] The following describes the Resource Unit (RU) used for the PPDU. An RU may include multiple subcarriers (or tones). An RU can be used to transmit signals to multiple STAs according to OFDMA. Alternatively, an RU can also be defined as transmitting signals to a single STA. An RU can be used for STF, LTF, data fields, etc.

[0090] The RUs described in this specification can be used for both uplink (UL) and downlink (DL) communication. For example, when performing UL-MU communication requested by a trigger frame, a transmitting STA (e.g., an AP) can assign a first RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a first STA via the trigger frame, and can assign a second RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a second STA. Subsequently, the first STA can transmit a first trigger-based PPDU based on the first RU, and the second STA can transmit a second trigger-based PPDU based on the second RU. The first and second trigger-based PPDUs are transmitted to the AP in the same (or overlapping) time period.

[0091] For example, when configuring a DL MU PPDU, a transmitting STA (e.g., an AP) can assign a first RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a first STA, and can assign a second RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a second STA. That is, a transmitting STA (e.g., an AP) can transmit HE-STF, HE-LTF, and data fields for a first STA through the first RU in a MU PPDU, and can transmit HE-STF, HE-LTF, and data fields for a second STA through the second RU.

[0092] Figure 5 Operation based on UL-MU is illustrated. As illustrated, a transmitting STA (e.g., AP) can perform channel access through contention (e.g., backoff operation) and can transmit trigger frame 1030. That is, the transmitting STA can transmit a PPDU including trigger frame 1030. Upon receiving the PPDU including the trigger frame, a trigger-based (TB) PPDU is transmitted after a delay corresponding to SIFS.

[0093] TB PPDUs 1041 and 1042 can be transmitted within the same time period and can be transmitted from multiple STAs (e.g., user STAs) having the AID indicated in trigger frame 1030. The ACK frame 1050 for the TB PPDU can be implemented in various forms.

[0094] refer to Figures 6 to 8 This describes the specific characteristics of the trigger frame. Even when using UL-MU communication, orthogonal frequency division multiple access (OFDMA) or MU-MIMO schemes can be used, and both OFDMA and MU-MIMO schemes can be used simultaneously.

[0095] Figure 6 An example of a trigger frame is shown. Figure 6The trigger frame is used to allocate resources for uplink multi-user (MU) transmissions and can be sent, for example, from the access point (AP). The trigger frame can consist of a MAC frame and can be included in a PPDU.

[0096] Figure 6 Each field shown can be partially omitted, and another field can be added. Additionally, the length of each field can be changed to a length different from that shown in the diagram.

[0097] Figure 6 The frame control field 1110 may include information related to the MAC protocol version and additional control information. The duration field 1120 may include time information configured in the NAV or information related to the STA's identifier (e.g., AID).

[0098] Additionally, the RA field 1130 may include address information of the receiving STA for the corresponding trigger frame, and may be optionally omitted. The TA field 1140 may include address information of the STA (e.g., AP) that sent the corresponding trigger frame. The common information field 1150 includes common control information applied to the receiving STA that received 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., the HE-SIG-A field) of the uplink PPDU sent in response to the corresponding trigger frame. Furthermore, as common 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.

[0099] Additionally, preferably includes receiving Figure 6 The number of STAs receiving the trigger frame corresponds to the per-user information fields 1160#1 to 1160#N. The per-user information field can also be called the "allocation field".

[0100] in addition, Figure 6 The trigger frame may include a padding field 1170 and a frame check sequence field 1180.

[0101] Figure 6 Each of the user information fields 1160#1 to 1160#N shown may include multiple subfields.

[0102] Figure 7 An example of the common information fields for the trigger frame is shown. Some parts can be omitted. Figure 7 It has subfields, and additional subfields can be added. Additionally, the length of each of the listed subfields can be changed.

[0103] The illustrated length field 1210 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 1210 of the trigger frame can be used to indicate the length of the corresponding uplink PPDU.

[0104] Additionally, the concatenation identifier field 1220 indicates whether a concatenation operation has been performed. A concatenation operation means that downlink MU transmission and uplink MU transmission are performed together within the same TXOP. That is, it means that downlink MU transmission is performed, and then, after a preset time (e.g., SIFS), uplink MU transmission is performed. During a concatenation operation, only one transmitting device (e.g., AP) can perform downlink communication, and multiple transmitting devices (e.g., non-APs) can perform uplink communication.

[0105] The CS request field 1230 indicates whether the radio medium state or NAV must be considered when the receiving device, having received the corresponding trigger frame, sends the corresponding uplink PPDU.

[0106] HE-SIG-A information field 1240 may include information controlling the content of the SIG-A field (i.e., the HE-SIG-A field) of the uplink PPDU in response to the corresponding trigger frame.

[0107] The CP and LTF type fields 1250 may include information related to the CP length and LTF length of the uplink PPDU sent in response to the corresponding trigger frame. The trigger type field 1260 may indicate the purpose of using the corresponding trigger frame, such as typical triggering, triggering for beamforming, request for block ACK / NACK, etc.

[0108] It can be assumed that the trigger type field 1260 of the trigger frame in this specification indicates a trigger frame of a basic type used for typical triggering. For example, a trigger frame of a basic type may be referred to as a basic trigger frame.

[0109] Figure 8 Examples of subfields included in each user information field are shown. Figure 8 The user information field 1300 can be understood as the above reference. Figure 6 Any one of the user information fields 1160#1 to 1160#N mentioned. Some can be omitted. Figure 8 The user information field 1300 includes subfields, and additional subfields can be added. Additionally, the length of each of the illustrated subfields can be changed.

[0110] Figure 8The User Identifier field 1310 indicates the identifier of the STA (i.e., the receiving STA) corresponding to each user information. An example of the identifier can be all or part of the Associated Identifier (AID) value of the receiving STA.

[0111] Additionally, an RU allocation field 1320 may be included. That is, when a receiving STA identified by the user identifier field 1310 sends a TB PPDU in response to a trigger frame, the TB PPDU is sent through the RU indicated by the RU allocation field 1320.

[0112] Figure 8 The subfield can include encoding type field 1330. Encoding type field 1330 can indicate the encoding type of the TB PPDU. For example, when BCC encoding is applied to the TB PPDU, encoding type field 1330 can be set to "1", and when LDPC encoding is applied, encoding type field 1330 can be set to "0".

[0113] in addition, Figure 8 The subfields may include the MCS field 1340. The MCS field 1340 may indicate the MCS scheme applied to the TB PPDU. For example, when BCC encoding is applied to the TB PPDU, the encoding type field 1330 may be set to "1", and when LDPC encoding is applied, the encoding type field 1330 may be set to "0".

[0114] The following section will describe a random access (UORA) scheme based on UL OFDMA.

[0115] Figure 9 The technical features of the UORA scheme are described.

[0116] Sending a STA (e.g., AP) can be done as follows: Figure 9 The diagram illustrates the allocation of six RU resources via a trigger frame. Specifically, the AP can allocate the first RU resource (AID 0, RU 1), the second RU resource (AID 0, RU 2), the third RU resource (AID 0, RU 3), the fourth RU resource (AID 2045, RU 4), ​​the fifth RU resource (AID 2045, RU 5), and the sixth RU resource (AID 3, RU 6). Information associated with AID 0, AID 3, or AID 2045 can, for example, be included in... Figure 8 The user identifier field 1310. Information related to RU1 through RU6 can be included, for example, in... Figure 8 In the RU allocation field 1320, AID=0 can mean a UORA resource used for an associated STA, and AID=2045 can mean a UORA resource used for a non-associated STA. Accordingly, Figure 9 The first to third RU resources can be used as UORA resources for associated STAs. Figure 9 The fourth and fifth RU resources can be used as UORA resources for non-associated STAs, and Figure 9 The sixth RU resource can be used as a typical resource for UL MU.

[0117] exist Figure 9 In the example, STA 1's OFDMA Random Access Backoff (OBO) is reduced to 0, and STA 1 randomly selects the second RU resource (AID 0, RU 2). Additionally, since the OBO counters of STA 2 / 3 are greater than 0, no uplink resources are allocated to STA 2 / 3. Furthermore, regarding... Figure 9 In STA4, since STA4's AID (e.g., AID=3) is included in the trigger frame, RU 6's resources are allocated without backoff.

[0118] Specifically, due to Figure 9 STA1 is an associated STA, therefore the total number of qualified RA RUs for STA1 is 3 (RU1, RU2, and RU3). Therefore, STA1 decrements the OBO counter by 3, making the OBO counter 0. Additionally, because... Figure 9 STA2 is an associated STA, therefore the total number of qualified RA RUs for STA2 is 3 (RU 1, RU 2, and RU 3). Therefore, STA2 decrements the OBO counter by 3, but the OBO counter remains greater than 0. Additionally, because... Figure 9 STA3 is a non-associated STA, so the total number of qualified RA RUs of STA3 is 2 (RU 4, RU 5). Therefore, STA3 will decrease the OBO counter by 2, but the OBO counter is greater than 0.

[0119] The following section describes the PPDUs sent / received in the STA of this specification.

[0120] Figure 10 An example of a PPDU used in this specification is shown.

[0121] Figure 10 PPDUs can be named using various terms such as EHT PPDU, TX PPDU, RX PPDU, Type 1, or Type N PPDU. For example, in this specification, PPDUs or EHT PPDUs can be named using various terms such as TX PPDU, RX PPDU, Type 1, or Type N PPDU. Furthermore, EHT PPDUs can be used in EHT systems and / or new WLAN systems enhanced relative to EHT systems.

[0122] Figure 10 A PPDU can indicate all or part of the PPDU types used in an EHT system. For example, Figure 10 The example can be used for both single-user (SU) and multi-user (MU) modes. In other words, Figure 10 The PPDU can be used for one or more receiving STAs. When Figure 10 When PPDU is used in trigger-based (TB) mode, Figure 10 The EHT-SIG can be omitted. In other words, a STA that has received a trigger frame for the uplink MU (UL-MU) can send a signal in... Figure 10 The PPDU for EHT-SIG is omitted in the example.

[0123] exist Figure 10 In this context, L-STF to EHT-LTF can be referred to as a preamble or physical preamble, and can be generated / sent / received / acquired / decoded at the physical layer.

[0124] Figure 10 The subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields can be determined to be 312.5 kHz, and the subcarrier spacing of the EHT-STF, EHT-LTF, and data fields can 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 can be represented in units of 312.5 kHz, and the tone index (or subcarrier index) of the EHT-STF, EHT-LTF, and data fields can be represented in units of 78.125 kHz.

[0125] exist Figure 10 In the PPDU, L-LTE and L-STF can be the same as those in the regular fields.

[0126] Figure 10The L-SIG field can include, for example, 24 bits of bit information. For instance, the 24 bits could include a 4-bit rate field, a 1-bit reserved bit, a 12-bit length field, a 1-bit parity bit, and a 6-bit tail bit. For example, the 12-bit length field could include information related to the length or duration of the PPDU. For example, the 12-bit length field can be determined based on the type of PPDU. For example, when the PPDU is a non-HT, HT, VHT, or EHT PPDU, the value of the length field can be determined to be a multiple of 3. For example, when the PPDU is an HE PPDU, the value of the length field can be determined to be either a multiple of 3 + 1 or a multiple of 3 + 2. In other words, for non-HT, HT, VHT, or EHT PPDUs, the value of the length field can be determined to be a multiple of 3, and for HE PPDUs, the value of the length field can be determined to be either a multiple of 3 + 1 or a multiple of 3 + 2.

[0127] For example, the transmitting STA can apply BCC coding based on a 1 / 2 coding rate to the 24-bit information of the L-SIG field. The transmitting STA then obtains 48 bits of BCC coded bits. BPSK modulation can be applied to these 48 coded bits, thereby generating 48 BPSK symbols. The transmitting STA can map these 48 BPSK symbols to positions 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 can be mapped to subcarrier indices -26 to -22, -20 to -8, -6 to -1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA can further map the signal {-1, -1, -1, 1} to subcarrier indices {-28, -27, +27, +28}. The signals mentioned above can be used for channel estimation in the frequency domain corresponding to {-28, -27, +27, +28}.

[0128] The transmitting STA can generate an RL-SIG in the same way as the L-SIG. BPSK modulation can be applied to the RL-SIG. The receiving STA can determine whether the RX PPDU is an HE PPDU or an EHT PPDU based on the presence of the RL-SIG.

[0129] It is possible Figure 10 A generic SIG (U-SIG) is inserted after the RL-SIG. U-SIBs can be named using various terms such as First SIG Field, First SIG, First Type SIG, Control Signal, Control Signal Field, First (Type) Control Signal, etc.

[0130] U-SIG can include N bits of information and may include information to identify the type of EHT PPDU. For example, U-SIG can be configured based on two symbols (e.g., two consecutive OFDM symbols). Each symbol of U-SIG (e.g., an OFDM symbol) can have a duration of 4 μs. Each symbol of U-SIG can be used to transmit 26 bits of information. For example, each symbol of U-SIG can be transmitted / received based on 52 data tones and 4 pilot tones.

[0131] A bits of information (e.g., 52 uncoded bits) can be transmitted via U-SIG (or the U-SIG field), for example. The first symbol of U-SIG can transmit the header X bits of the A bits (e.g., 26 uncoded bits), and the second symbol of U-SIG can transmit the remaining Y bits of the A bits (e.g., 26 uncoded bits). For example, the transmitting STA can obtain the 26 uncoded bits included in each U-SIG symbol. The transmitting STA can perform convolutional coding (i.e., BCC coding) at a rate of R = 1 / 2 to generate 52 coded bits, and can perform interleaving on the 52 coded bits. The transmitting STA can perform BPSK modulation on the interleaved 52 coded bits to generate 52 BPSK symbols to be assigned to each U-SIG symbol. A U-SIG symbol can be transmitted based on 65 tones (subcarriers) from subcarrier index -28 to subcarrier index +28, excluding DC index 0. The 52 BPSK symbols generated by the transmitting STA can be transmitted based on the remaining tones (subcarriers) other than the pilot tones (i.e., tones -21, -7, +7, +21).

[0132] For example, the A-bit information generated by U-SIG (e.g., 52 uncoded bits) may include a CRC field (e.g., a 4-bit field) and a tail field (e.g., a 6-bit field). The CRC and tail fields can be sent via a second symbol of U-SIG. The CRC field can be generated based on the 26 bits allocated to the first symbol of U-SIG and the remaining 16 bits in the second symbol excluding the CRC / tail field, and can be generated based on a conventional CRC calculation algorithm. Additionally, the tail field can be used to terminate the grid of the convolutional decoder and can be set to, for example, "000000".

[0133] The A-bit information (e.g., 52 unencoded bits) sent by U-SIG (or the U-SIG field) can be divided into version-independent bits and version-dependent bits. For example, version-independent bits can have a fixed or variable size. For example, version-independent bits can be assigned only to the first symbol of U-SIG, or version-independent bits can be assigned to both the first and second symbols of U-SIG. For example, version-independent bits and version-dependent bits can be named using various terms such as first control bit, second control bit, etc.

[0134] For example, the version-independent bits of the U-SIG can include a 3-bit PHY version identifier. For example, the 3-bit PHY version identifier can include information related to the PHY version of the TX / RX PPDU. For example, the first value of the 3-bit PHY version identifier can 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 can be set to the first value. In other words, the receiving STA can determine that the RX PPDU is an EHT PPDU based on the PHY version identifier having the first value.

[0135] For example, the version-independent bits of U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication.

[0136] For example, the version-independent bits of U-SIG can include information related to the TXOP length and information related to the BSS color ID.

[0137] For example, when EHT PPDUs are classified into various types (e.g., EHT PPDUs related to SU mode, EHT PPDUs related to MU mode, EHT PPDUs related to TB mode, EHT PPDUs related to extended range transmission, etc.), information related to the type of EHT PPDU can be included in the version-related bits of U-SIG.

[0138] For example, U-SIG may include: 1) a bandwidth field including information related to bandwidth; 2) a field including information related to the MCS scheme applied to EHT-SIG; 3) an indication field including information about whether a dual subcarrier modulation (DCM) scheme is applied to EHT-SIG; 4) a field including information related to the number of symbols used for EHT-SIG; 5) a field including information about whether 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 length of EHT-LTF and the length of CP.

[0139] 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., can be based on Figure 10 The signals transmitted / received by the PPDU. Figure 10 PPDUs can be used to send / receive various types of frames. For example, Figure 10 PPDUs can be used for control frames. Examples of control frames can include Request to Send (RTS), Allow to Send (CTS), Power Saving Polling (PS Polling), BlockACKReq, BlockAck, Null Data Packet (NDP) announcement, and trigger frames. For example, Figure 10 PPDUs can be used for management frames. Examples of management frames can include beacon frames, (re)association request frames, (re)association response frames, probe request frames, and probe response frames. For example, Figure 10 PPDUs can be used in data frames. For example, Figure 10 A PPDU can be used to send at least two or more of control frames, management frames, and data frames simultaneously.

[0140] Figure 11 Examples of modified transmitting and / or receiving devices are illustrated in this specification.

[0141] Figure 1 Each device / STA in subgraphs (a) / (b) can be as follows Figure 11 The modifications shown are as indicated. Figure 11 The transceiver 630 can be used with Figure 1 The transceivers 113 and 123 are the same. Figure 11 The transceiver 630 may include a receiver and a transmitter.

[0142] Figure 11 The processor 610 can be with Figure 1 The processors 111 and 121 are the same. Alternatively, Figure 11The processor 610 can be with Figure 1 The processing chips 114 and 124 are the same.

[0143] Figure 11 The memory 620 can be with Figure 1 The memories 112 and 122 are the same. Alternatively, Figure 11 The memory 620 can be with Figure 1 The memories 112 and 122 are different separate external memories.

[0144] Reference Figure 11 The power management module 611 manages the power supplied to the processor 610 and / or transceiver 630. The battery 612 supplies power to the power management module 611. The display 613 outputs the results processed by the processor 610. The keyboard 614 receives input to be used by the processor 610. The keyboard 614 may be displayed on the display 613. The SIM card 615 may be an integrated circuit for securely storing the International Mobile Subscriber Identity (IMSI) and its associated keys, which are used to identify and authenticate subscribers on mobile devices such as mobile phones and computers.

[0145] Reference Figure 11 The speaker 640 can output results related to the sound processed by the processor 610. The microphone 641 can receive input related to the sound to be used by the processor 610.

[0146] The technical features of multi-link (ML) supported by the STA in this specification will be described below.

[0147] The STA (AP and / or non-AP STA) in this specification can support multi-link (ML) communication. ML communication can refer to communication supporting multiple links. Links associated with ML communication can include channels in the 2.4 GHz band, 5 GHz band, and 6 GHz band (e.g., 20 / 40 / 80 / 160 / 240 / 320 MHz channels).

[0148] Multiple links for ML communication can be established in various ways. For example, multiple links for ML communication supported by a single STA can be 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 can be 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 for ML communication supported by a single STA can be a channel with preamble culling applied.

[0149] STA can perform ML establishment to execute ML communication. ML establishment can be performed based on management frames or control frames such as beacons, probe requests / responses, and association requests / responses. For example, information about the ML establishment can be included in element fields included in beacons, probe requests / responses, and association requests / responses.

[0150] Once ML is established, the enabled link for ML communication can be determined. STA can perform frame switching through at least one of the multiple links determined to be enabled. For example, the enabled link can be used for at least one of management frames, control frames, and data frames.

[0151] When a STA supports multiple links, the transmitting / receiving devices supporting each link can operate like a logical STA. For example, an STA supporting two links can be represented as an ML device (Multi-Link Device; MLD) including a first STA for the first link and a second STA for the second link. Similarly, 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. Conversely, 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.

[0152] The following describes more specific features built by ML.

[0153] MLDs (AP MLDs and / or non-AP MLDs) can send information about the links supported by the corresponding MLD through ML establishment. Link-related information can be configured in various ways. For example, link-related information includes at least one of the following: 1) information about whether the MLD (or STA) supports simultaneous RX / TX operation; 2) information about the number / upper limit of uplink / downlink links supported by the MLD (or STA); 3) information about the location / frequency band / resources of the uplink / downlink links supported by the MLD (or STA); 4) the type of frames available or preferred in at least one uplink / downlink link (management, control, data, etc.); 5) information about the available or preferred ACK policy for at least one uplink / downlink link; and 6) information about the available or preferred TID (Traffic Identifier) ​​for at least one uplink / downlink link. The TID is related to the priority of traffic data and is represented by eight types of values ​​according to standard wireless LAN standards. That is, eight TID values ​​can be defined corresponding to the four access categories (AC) (AC_BK (background), AC_BE (best effort), AC_VI (video), AC_VO (voice)) according to the conventional wireless LAN standard.

[0154] For example, all TIDs for uplink / downlink link mappings can be pre-configured. Specifically, if negotiation is not completed via ML, all TIDs can be used for ML communication, and if the mapping between uplink / downlink links and TIDs is negotiated via ML, the negotiated TIDs can be used for ML communication.

[0155] Multiple links that can be used by the sending MLD and receiving MLD associated with ML communication can be set up through ML establishment, and this can be referred to as enabling links. Enabling links can be named differently in various ways. For example, it can be named in various ways such as first link, second link, sending link, and receiving link.

[0156] After the ML (Link Management Frame) is established, the MLD (Link Deployment Frame) can update the ML establishment. For example, when it is necessary to update information about the link, the MLD can send information about the new link. This information can be sent based on at least one of management frames, control frames, and data frames.

[0157] The device described below can be Figure 1 and / or Figure 11 The device, and the PPDU can be Figure 10 The device can be an AP or a non-AP STA. The device described below can be an AP multi-link device (MLD) or a non-APSTA MLD that supports multiple links.

[0158] In EHT (Extremely High Throughput) (a standard discussed after 802.11ax), a multi-link environment using one or more frequency bands simultaneously is considered. When a device supports multiple links, it can use one or more frequency bands simultaneously or alternately (e.g., 2.4 GHz, 5 GHz, 6 GHz, 60 GHz, etc.).

[0159] In the following description, MLD refers to a multi-link device. An MLD has one or more connected STAs and a MAC service access point (SAP) that communicates with the uplink layer (logical link control, LLC). MLD can refer to a physical device or a logical device. In the following text, device may refer to an MLD.

[0160] In the following description, "transmitting device" and "receiving device" may refer to an MLD. The first link of the receiving / transmitting device may be a terminal (e.g., a STA or AP) included in the receiving / transmitting device and performing signal transmission / reception via the first link. The second link of the receiving / transmitting device may be a terminal (e.g., a STA or AP) that transmits / receives signals via the second link included in the receiving / transmitting device.

[0161] In IEEE 802.11be, two types of multilink operation are supported. For example, simultaneous transmit and receive (STR) and non-STR operations can be considered. STR can be referred to as asynchronous multilink operation, and non-STR as synchronous multilink operation. Multilink can include multiple frequency bands. That is, multilink can refer to links included in several frequency bands, or it can refer to multiple links included in one frequency band.

[0162] EHT (11be) considers multi-link technology, where multiple links can include multiple frequency bands. That is, multiple links can simultaneously represent links in several frequency bands or multiple multiple links within a single frequency band. Two main multi-link operations are being considered: asynchronous operation of TX / RX simultaneously on multiple links and the impossibly synchronous operation. In the following text, the ability to enable simultaneous reception and transmission on multiple links is referred to as STR (Simultaneous Transmit and Receive), an STA with STR capability is called a STR MLD (Multi-Link Device), and an STA without STR capability is called a non-STR MLD.

[0163] In the following description, for ease of explanation, it is described that the MLD (or the processor of the MLD) controls at least one STA, but is not limited thereto. As mentioned above, the at least one STA can transmit and receive signals independently of the MLD.

[0164] Depending on the implementation, an AP MLD or a non-AP MLD can have a structure containing multiple links. In other words, a non-AP MLD can support multiple links. A non-AP MLD can include multiple STAs. Multiple STAs can have links for each STA.

[0165] In the EHT standard (802.11be standard), the MLD (Multi-Link Device) architecture, where one AP / non-AP MLD supports multiple links, is considered a key technology. STAs included in a non-AP MLD can transmit information about other STAs in the non-AP MLD together via a single link. Therefore, this reduces frame switching overhead. Additionally, it improves link utilization efficiency for STAs and reduces power consumption.

[0166] Here, multiple links can include multiple frequency bands. That is, multiple links can simultaneously represent links in multiple frequency bands or multiple links within a single frequency band.

[0167] Figure 12 An example of the structure of STA MLD is shown.

[0168] Figure 12An example of a STA MLD with three links is shown. Essentially, for each link pair in the MLD (i.e., [link 1, link 2], [link 2, link 3], [link 1, link 3]), it can operate as either simultaneous transmit and receive (STR) or non-STR (NSTR) operation. In an NSTR link pair (which operates as NSTR), when a frame is transmitted on one link, the resulting intra-device interference affects reception on the other link of that pair. On the other hand, an STR link pair (which operates as STR) can operate without affecting frame transmission / reception on each link.

[0169] Meanwhile, in EHT (802.11be), an NSTR soft AP MLD (or NSTR mobile AP MLD) is defined. That is, an NSTR soft AP MLD has one or more NSTR link pairs. Specifically, since an NSTR soft AP MLD is a type of AP MLD, it must have a master link for the NSTR link pairs to control multiple non-AP MLDs. On the master link (PL), non-AP STAs send management frames, such as beacon and probe response frames for discovery / association. Because of NSTR, frames on the master link must always be sent together in order to send frames on non-PLs instead of the master link (PL). If frames are only sent on non-PLs, this would have a significant impact since all STAs are sending frames on the PL that is set as the master link.

[0170] NSTR soft AP MLDs can change this master link due to channel quality / state, etc. However, since the master link is monitored by all associated non-AP STAs, a suitable method for changing it is required. This specification proposes a method for changing the master link. In this specification, STA (MLD) can refer to AP (MLD) or non-AP (MLD), and the terminology can be changed.

[0171] 1. Configuration and operation proposed in this embodiment

[0172] Basically, 1) multi-link elements (ML IE) and 2) new action frames can be used to change the main link.

[0173] 1.1. A method for using multi-link elements (ML IE)

[0174] Basically, multi-link elements have a common information field that contains public information about the MLD level, i.e., the STA belonging to the MLD. For example... Figure 13 As shown, in order to indicate its presence or absence, a presence bitmap exists in front of the public information field.

[0175] refer to Figure 12The AP MLD has three links and advertises information about them via beacon frames or probe response frames. Essentially, as before, information about AP 1 (link 1) is contained in the body of the frames sent by AP 1. Specifically, in 802.11be, a STA in the STA MLD is used for single multi-link establishment; that is, in order to simultaneously associate (establish) multiple links within a single link via association frame exchange, information about one or more links other than its own must be provided. To provide this information, a Multi-Link Element (MLIE) has been defined, and the basic structure of the MLIE is as follows: Figure 13 As shown.

[0176] exist Figure 13 The order, names, and sizes of the fields shown can be changed and can exist as additional fields. Basically, common information refers to information shared between STAs in the MLD, and specific information about each STA is indicated in the Per-STA profile.

[0177] Figure 13 The structure of the multi-link control field and public information field of the multi-link element is shown.

[0178] refer to Figure 13 The multi-link control fields include a type subfield, a reserved subfield, and an existence bitmap subfield. The common information fields include a common information length subfield, an MLD MAC address subfield, a link ID information subfield, a BSS parameter change count subfield, a media synchronization delay information subfield, an EML capability subfield, and an MLD capability subfield.

[0179] Figure 14 The structure of the existence bitmap subfield of the multi-link element is shown.

[0180] refer to Figure 14 The bitmap subfields include the link ID information subfield, the BSS parameter change count subfield, the media synchronization delay information subfield, the EML capability subfield, the MLD capability subfield, and the reserved subfield.

[0181] exist Figure 14 The existence bitmap subfield in is defined as indicating the presence of Figure 13The presence or absence of public information fields is determined by the presence or absence of the Link ID information subfield. For example, if the Link ID information presence subfield is set to 1, then the Link ID information subfield exists in the public information field (if the Link ID information presence subfield is set to 0, then the Link ID information subfield does not exist in the public information field). Additionally, when the BSS parameter change count presence subfield is set to 1, the BSS parameter change count subfield exists in the public information field. Other subfields in the presence bitmap subfield have the same effect as other subfields in the public information field.

[0182] refer to Figure 13 Following the public information field, the ML IE has a link information field containing information about the STAs / links belonging to the MLD. The link information field includes a Per-STA profile sub-element corresponding to each link to include information about each link, and is formatted as follows: Figure 15 As shown.

[0183] Figure 15 The structure of the Per-STA profile element is shown.

[0184] When the optional sub-element ID is 0, the link information field includes the Per-STA profile sub-field, and when the optional sub-element ID is 221, the link information field includes the vendor-specific sub-field. The optional sub-element IDs used for multi-link elements are defined as follows.

[0185] [Table 1]

[0186] 0 Per-STA Profile yes 1-220 Reserved 221 Supplier-specific Supplier-specific 222-255 Reserved

[0187] The link information field includes the per-STA profile subfield within the same MLD for other STAs (STAs operating on unrelated links). Reference Figure 12 Assuming that STA MLD includes STA 2 and STA 3, the link information field may include the Per-STA profile #2 subfield for STA 2 and the Per-STA profile #3 subfield for STA 3.

[0188] Basically, the common information field refers to common information between STAs in the MLD, and specific information about each STA / link is indicated in the Per-STA profile, which includes the link ID corresponding to the STA. Specifically, in the multi-link element of the association request / response frame used for multi-link establishment (association), the complete profile of the Per-STA control field is set to 1, so that the complete information of the AP MLD and the non-AP MLD must always be included.

[0189] 1) First, this specification proposes a method for changing the main link by adding the following fields to the public information of ML IE, and it is not limited to the method described later.

[0190] - Primary Link Subfield: This field indicates a change in the primary link (e.g., 1 bit). For example, if the NSTR soft AP MLD is limited to two links, a value of 1 in the Primary Link Subfield indicates that the primary link has been changed from the current link to another link. If the NSTR soft AP MLD can have two or more links, the Primary Link Subfield can be configured with 4 bits to indicate the link ID of the link to be changed.

[0191] - Master Link Change Count subfield (e.g., 1 byte): This subfield indicates when the master link was changed. For example, it may include information about the number of TBTTs (Target Beacon Transmission Time) until the AP changed the master link. Alternatively, it may indicate a specific time (e.g., in microseconds) from the time the corresponding ML IE was sent to the time of the change. In other words, an STA that reads and decodes the master link change count subfield is able to operate on the new master link after that time.

[0192] The system can redefine the main link change subfield, which includes the main link change subfield and the main link change count subfield, and include the main link change subfield in the public information. Additionally, it can redefine the main link change existence field, which indicates the existence of the main link change subfield, and add it to the existence bitmap subfield. Additionally, it can add the main link change subfield to the MLD capability subfield.

[0193] Figure 16 An example of how the main link changes the structure of a subfield is shown.

[0194] It is possible to assume that an NSTR soft AP MLD with two links sends ML IE to define in Figure 16 The main link in the data changes the sub-field. (See reference.) Figure 16 As mentioned above, the main link change subfield may include a main link subfield (1 bit) and a main link change count subfield (8 bits, 1 byte).

[0195] 2) Additionally, considering the link information field of ML IE, this embodiment can also propose a method to add a main link change sub-field to each Per-STA profile. Therefore, similar to the common information field, a main link change sub-field existence field can be added to the STA control field of the Per-STA profile, and the main link change sub-field can be included in the STA information field of the Per-STA profile.

[0196] Specifically, when the link corresponding to the link ID indicated by the per-STA profile sub-element is changed to the primary link, the primary link change sub-field of the primary link change sub-field is set to 1. The use of the primary link change count sub-field of the primary link change sub-field is the same as described above. Basically, when link information is included instead of public information, the overhead is greater due to the default overhead of the sub-element.

[0197] Essentially, ML IEs that include the primary link change subfield can be sent within management frames, such as beacon frames or probe response frames sent on the primary link by an NSTR soft AP MLD. If a primary link change has not occurred, the primary link change subfield will not be included in the primary link change presence field.

[0198] 1.2. When using new elements / fields

[0199] The aforementioned main link change subfield can be defined as an element, or as a field / element in a management frame such as an action frame or beacon / probe response frame, an EHT Operation Mode (OM) control field, or an EHT Operation Mode Notification frame, and can be included and sent.

[0200] For action frames, a main link change notification action frame can be used by defining the main link change notification in the protected EHT action field or the EHT action field. The structure of the main link change notification action frame can be defined as follows.

[0201] [Table 2]

[0202] 1 type 2 Protected EHT Actions 3 Dialogue token 4 Main link change

[0203] In the following text, reference will be made to Figures 1 to 16 The above embodiments are described.

[0204] Figure 17 This is a flowchart illustrating the process of sending an MLD to change the primary link of an NSTR link pair according to this embodiment.

[0205] Figure 17 Examples can be implemented in network environments that support next-generation WLAN systems (IEEE 802.11be or EHT WLAN systems). Next-generation wireless LAN systems are WLAN systems enhanced from 802.11ax systems and therefore meet backward compatibility requirements with 802.11ax systems.

[0206] This embodiment proposes a method and apparatus in which a transmitting MLD modifies the primary link belonging to an NSTR link pair via an ML element. The primary link is the link that transmits and receives management frames, such as beacon frames or probe response frames, for discovery or association between the transmitting or receiving MLDs. The transmitting MLD is an NSTR soft access point (AP) MLD or an NSTR soft mobile AP and includes at least one NSTR link pair. Since the transmitting MLD must also be able to control at least one non-AP STA included in the receiving MLD, at least one NSTR link pair must include the primary link. The received MLD may correspond to a non-AP MLD.

[0207] In step S1710, the transmitting multilink device (MLD) generates multilink (ML) elements from the receiving MLD.

[0208] In step S1720, the sending MLD sends ML elements to the receiving MLD via the first link.

[0209] The transmitting MLD includes a first transmitting station (STA) operating on a first link and a second transmitting STA operating on a second link. The receiving MLD includes a first receiving STA operating on a first link and a second receiving STA operating on a second link.

[0210] The first link is the primary link, and the second link is a non-primary link. The first and second links are a link pair that operates in Non-Simultaneous Transmission and Reception (NSTR).

[0211] ML elements include public information fields. Public information fields include first and second subfields.

[0212] The first subfield contains information about when the primary link changed from the first link to the second link. The second subfield contains information about when the primary link changed from the first link to the second link.

[0213] The first subfield can consist of 1 bit. When the value of the first subfield is 1, the main link can be changed from the first link to the second link. When the value of the first subfield is 0, the main link can remain unchanged from the first link to the second link.

[0214] The second subfield can consist of 8 bits (or 1 byte). Information about when the primary link changes from the first link to the second link can be the number of Target Beacon Transmission Time (TBTT) from the time the ML element was sent to the time the primary link changed.

[0215] The public information field may further include a main link change subfield. The main link change subfield may further include first and second subfields. The main link change subfield may consist of 9 bits.

[0216] ML elements can further include ML control fields.

[0217] The ML control field may include an existence bitmap subfield. The existence bitmap subfield may include a main link change existence subfield.

[0218] When the value of the "Primary Link Change Existence" subfield is 1, the "Primary Link Change Existence" subfield can be included in the public information field or the MAC capability subfield of the public information field. When the value of the "Primary Link Change Existence" subfield is 0, the "Primary Link Change Existence" subfield may not be included in the public information field or the MAC capability subfield of the public information field.

[0219] That is, this embodiment proposes a method in which the transmitted MLD changes the primary link in a link pair operating as an NSTR by defining a primary change subfield in the public information field of the ML element. The transmitted MLD is an NSTR soft AP MLD (or an NSTR mobile AP MLD), and because the NSTR soft AP MLD has a significant impact on the link operating as an NSTR depending on channel quality or channel state, the NSTR soft AP MLD is capable of changing the primary link.

[0220] According to the proposed embodiment, first and second receiving STAs belonging to the receiving MLD associated with the transmitting MLD can flexibly identify the effects of changes in the main link. Therefore, link changes can be efficiently performed based on the main change subfield included in the common information field of the ML element without additional overhead.

[0221] Figure 18 This is a flowchart illustrating the process of receiving information that the main link of the NSTR link pair has changed, according to this embodiment.

[0222] Figure 18 Examples can be implemented in network environments that support next-generation WLAN systems (IEEE 802.11be or EHT WLAN systems). Next-generation wireless LAN systems are WLAN systems enhanced from 802.11ax systems and therefore meet backward compatibility requirements with 802.11ax systems.

[0223] This embodiment proposes a method and apparatus in which a transmitting MLD modifies the primary link belonging to an NSTR link pair via an ML element. The primary link is the link that transmits and receives management frames, such as beacon frames or probe response frames, for discovery or association between the transmitting or receiving MLDs. The transmitting MLD is an NSTR soft access point (AP) MLD or an NSTR soft mobile AP and includes at least one NSTR link pair. Since the transmitting MLD must also be able to control at least one non-AP STA included in the receiving MLD, at least one NSTR link pair must include the primary link. The received MLD may correspond to a non-AP MLD.

[0224] In step S1810, the receiving multilink device (MLD) receives multilink (ML) elements from the sending MLD via the first link.

[0225] In step S1820, the MLD decodes the ML element.

[0226] The transmitting MLD includes a first transmitting station (STA) operating on a first link and a second transmitting STA operating on a second link. The receiving MLD includes a first receiving STA operating on a first link and a second receiving STA operating on a second link.

[0227] The first link is the primary link, and the second link is a non-primary link. The first and second links are a link pair that operates in Non-Simultaneous Transmission and Reception (NSTR).

[0228] ML elements include public information fields. Public information fields include first and second subfields.

[0229] The first subfield contains information about when the primary link changed from the first link to the second link. The second subfield contains information about when the primary link changed from the first link to the second link.

[0230] The first subfield can consist of 1 bit. When the value of the first subfield is 1, the main link can be changed from the first link to the second link. When the value of the first subfield is 0, the main link can remain unchanged from the first link to the second link.

[0231] The second subfield can consist of 8 bits (or 1 byte). Information about when the primary link changes from the first link to the second link can be the number of Target Beacon Transmission Time (TBTT) from the time the ML element was sent to the time the primary link changed.

[0232] The public information field may further include a main link change subfield. The main link change subfield may further include first and second subfields. The main link change subfield may consist of 9 bits.

[0233] ML elements can further include ML control fields.

[0234] The ML control field may include an existence bitmap subfield. The existence bitmap subfield may include a main link change existence subfield.

[0235] When the value of the "Primary Link Change Existence" subfield is 1, the "Primary Link Change Existence" subfield can be included in the public information field or the MAC capability subfield of the public information field. When the value of the "Primary Link Change Existence" subfield is 0, the "Primary Link Change Existence" subfield may not be included in the public information field or the MAC capability subfield of the public information field.

[0236] That is, this embodiment proposes a method in which the transmitted MLD changes the primary link in a link pair that is an NSTR operation by defining a major change subfield in the public information field of the ML element. The transmitted MLD is an NSTR soft AP MLD (or an NSTR mobile AP MLD), and because the NSTR soft AP MLD has a significant impact on the link that is an NSTR operation depending on the channel quality or channel state, the NSTR soft AP MLD is capable of changing the primary link.

[0237] According to the proposed embodiment, first and second receiving STAs belonging to the receiving MLD associated with the transmitting MLD can flexibly identify the effects of changes in the main link. Therefore, link changes can be efficiently performed based on the main change subfield included in the common information field of the ML element without additional overhead.

[0238] The technical features of this disclosure can be applied to various devices and methods. For example, they can be used... Figure 1 and / or Figure 11 The device is used to execute / support the technical features of this disclosure. For example, the technical features of this disclosure may be applied only to... Figure 1 and / or Figure 11 This is part of the disclosure. For example, the technical features of this disclosure can be based on... Figure 1 The processing chips 114 and 124 are implemented, or based on processors 111 and 121 and memories 112 and 122, or based on... Figure 11 The processor 610 and memory 620 are implemented. For example, the device according to this disclosure receives multilink (ML) elements from a transmitting multilink device (MLD) via a first link; and decodes the ML elements.

[0239] The technical features of this disclosure can be implemented based on a computer-readable medium (CRM). For example, the CRM according to this disclosure is at least one computer-readable medium that includes instructions designed to be executed by at least one processor.

[0240] The CRM can store instructions for performing operations including receiving multi-link (ML) elements from a transmitting multi-link device (MLD) via a first link; and decoding ML elements. At least one processor can execute the instructions stored in the CRM according to this disclosure. The at least one processor associated with the CRM of this disclosure may be... Figure 1 Processors 111, 121, Figure 1 Processing chips 114, 124 or Figure 11 The processor 610. Meanwhile, the CRM disclosed herein can be... Figure 1 Memory 112, 122, Figure 11 The memory 620 or a separate external memory / storage medium / disk.

[0241] The aforementioned technical features in this specification are applicable to various applications or business models. For example, the aforementioned technical features can be applied to wireless communication in devices that support artificial intelligence (AI).

[0242] Artificial intelligence (AI) refers to the field of research concerning artificial intelligence or the methods used to create it, while machine learning refers to the field of research concerning methods for defining and solving various problems within the field of AI. Machine learning is also defined as an algorithm that improves operational performance through stable operational experience.

[0243] Artificial neural networks (ANNs) are models used in machine learning, and can refer to models that solve problems in general, including artificial neurons (nodes) that form a network by combining synapses. An artificial neural network can be defined by the connection patterns between neurons in different layers, the learning process that updates model parameters, and the activation function that generates the output value.

[0244] 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 an artificial neural network, each neuron can output the function value of an activation function of the input signal input through synapses, weights, and biases.

[0245] Model parameters refer to the parameters determined through learning, and include the weights of synaptic connections and the biases of neurons. Hyperparameters refer to the parameters that are set before learning in a machine learning algorithm, and include the learning rate, number of iterations, minimum batch size, and initialization function.

[0246] Learning artificial neural networks may aim to determine model parameters used to minimize a loss function. The loss function can be used as a metric for determining the optimal model parameters during the learning process of an artificial neural network.

[0247] Machine learning can be divided into supervised learning, unsupervised learning, and reinforcement learning.

[0248] Supervised learning refers to the method of training an artificial neural network using labels provided for the training data. When the training data is input into the artificial neural network, the labels indicate the correct answer (or result value) that the network should infer. Unsupervised learning refers to the method of training an artificial neural network without providing labels for the training data. Reinforcement learning can be a training method used to train an agent defined in an environment to select actions or sequences of actions to maximize the cumulative reward in each state.

[0249] Machine learning implemented using deep neural networks (DNNs) with multiple hidden layers is called deep learning, and deep learning is a part of machine learning. In the following text, machine learning will be interpreted as including deep learning.

[0250] The aforementioned technical features can be applied to wireless communication for robots.

[0251] A robot can be defined as a machine that automatically processes or operates a given task using its own capabilities. In particular, a robot that has the ability to recognize its environment and make autonomous judgments to perform operations can be called an intelligent robot.

[0252] Depending on their application or field, robots can be categorized into industrial, medical, household, and military robots, among others. Robots can include actuators or drives that include motors to perform various physical operations, such as moving robot joints. Additionally, mobile robots can include wheels, brakes, propellers, etc., in their drives to move on the ground or fly in the air.

[0253] The aforementioned technical features can be applied to devices that support extended reality.

[0254] Extended reality is collectively referred to as Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR). VR technology is a computer graphics technology that provides real-world objects and backgrounds only in CG images; AR technology is a computer graphics technology that provides virtual CG images on top of real object images; and MR technology is a computer graphics technology that provides virtual objects that are mixed and combined with the real world.

[0255] MR technology is similar to AR technology in that it can display real and virtual objects together. However, in AR technology, virtual objects are used as a supplement to real objects, while in MR technology, virtual and real objects are used as equals.

[0256] XR technology can be applied to head-mounted displays (HMDs), head-up displays (HUDs), mobile phones, tablets, laptops, desktop computers, televisions, digital signage, and more. Devices that utilize XR technology can be referred to as XR devices.

[0257] The claims disclosed in this specification can be combined in various ways. For example, the technical features in the method claims of this specification can be combined to implement as an apparatus, and the technical features in the apparatus claims of this specification can be combined to implement by a method. Furthermore, the technical features in the method claims and apparatus claims of this specification can be combined to implement as an apparatus, and the technical features in the method claims and apparatus claims of this specification can be combined to implement by a method.

Claims

1. A method in a wireless local area network (WLAN) system, the method comprising: The receiving multilink device (MLD) receives multilink (ML) elements from the transmitting MLD via the first link; as well as The ML element is decoded by the receiving MLD. The MLD transmission includes a first transmitting station (STA) operating on the first link and a second transmitting STA operating on the second link. The receiving MLD includes a first receiving STA operating on the first link and a second receiving STA operating on the second link. Wherein, the first link is the primary link, and the second link is a non-primary link. The first and second links are link pairs that operate in non-simultaneous transmission and reception (NSTR). The ML element includes a public information field. The public information field includes first and second sub-fields. The first subfield includes information about the change of the primary link from the first link to the second link, and The second subfield includes information about when the primary link was changed from the first link to the second link.

2. The method according to claim 1, wherein, The first subfield consists of 1 bit. Specifically, when the value of the first sub-field is 1, the main link changes from the first link to the second link. Specifically, when the value of the first sub-field is 0, the main link does not change from the first link to the second link.

3. The method according to claim 1, wherein, The second subfield consists of 8 bits. The information regarding when the primary link changes from the first link to the second link is the number of Target Beacon Transmission Time (TBTT) from the time the ML element is sent to the time when the primary link is changed.

4. The method according to claim 1, wherein, The public information field further includes a main link change subfield. The main link change subfield further includes the first and second subfields.

5. The method according to claim 1, wherein, The ML element further includes ML control fields. The ML control field includes a bitmap subfield. The existence bitmap subfield includes a main link change existence subfield. Specifically, when the value of the primary link change subfield is 1, the primary link change subfield is included in the public information field or the MAC capability subfield of the public information field. Specifically, when the value of the main link change subfield is 0, the main link change subfield is not included in the public information field or the MAC capability subfield of the public information field.

6. The method according to claim 1, wherein, The MLD being sent is either an NSTR Soft Access Point (AP) MLD or an NSTR Mobile AP MLD.

7. A receive multilink device (MLD) in a wireless local area network (WLAN) system, the receive MLD comprising: Memory; transceiver; as well as A processor, operatively coupled to the memory and the transceiver, The processor is configured as follows: Receive multi-link (ML) elements from the sending MLD via the first link; and Decode the ML element, The MLD transmission includes a first transmitting station (STA) operating on the first link and a second transmitting STA operating on the second link. The receiving MLD includes a first receiving STA operating on the first link and a second receiving STA operating on the second link. Wherein, the first link is the primary link, and the second link is a non-primary link. The first and second links are link pairs that operate in non-simultaneous transmission and reception (NSTR). The ML element includes a public information field. The public information field includes first and second sub-fields. The first sub-field includes information about the change of the primary link from the first link to the second link, and The second subfield includes information about when the primary link was changed from the first link to the second link.

8. A method in a wireless local area network (WLAN) system, the method comprising: Multilink (ML) elements are generated by the transmitting multilink device (MLD); as well as The sending MLD sends the ML element to the receiving MLD via the first link. The MLD transmission includes a first transmitting station (STA) operating on the first link and a second transmitting STA operating on the second link. The receiving MLD includes a first receiving STA operating on the first link and a second receiving STA operating on the second link. Wherein, the first link is the primary link, and the second link is a non-primary link. The first and second links are link pairs that operate in non-simultaneous transmission and reception (NSTR). The ML element includes a public information field. The public information field includes a first subfield and a second subfield. The first sub-field includes information about the change of the primary link from the first link to the second link, and The second subfield includes information about when the primary link was changed from the first link to the second link.

9. The method according to claim 8, wherein, The first subfield consists of 1 bit. Specifically, when the value of the first sub-field is 1, the main link is changed from the first link to the second link. Specifically, when the value of the first sub-field is 0, the main link does not change from the first link to the second link.

10. The method according to claim 8, wherein, The second subfield consists of 8 bits. The information regarding when the primary link changes from the first link to the second link includes the number of Target Beacon Transmission Time (TBTT) from the time the ML element is sent to the time when the primary link is changed.

11. The method according to claim 8, wherein, The public information field further includes a main link change subfield. The main link change subfield further includes the first and second subfields.

12. The method according to claim 11, wherein, The ML element further includes ML control fields. The ML control field includes a bitmap subfield. The existence bitmap subfield includes a main link change existence subfield. Specifically, when the value of the primary link change subfield is 1, the primary link change subfield is included in the public information field or the MAC capability subfield of the public information field. Specifically, when the value of the main link change subfield is 0, the main link change subfield is not included in the public information field or the MAC capability subfield of the public information field.

13. The method according to claim 8, wherein, The MLD being sent is either an NSTR Soft Access Point (AP) MLD or an NSTR Mobile AP MLD.

14. A transmit multilink device (MLD) in a wireless local area network (WLAN) system, the transmit MLD comprising: Memory; transceiver; as well as A processor, operatively coupled to the memory and the transceiver, The processor is configured as follows: Generate multi-link (ML) elements; and The ML element is sent to the receiving MLD via the first link. The MLD transmission includes a first transmitting station (STA) operating on the first link and a second transmitting STA operating on the second link. The receiving MLD includes a first receiving STA operating on the first link and a second receiving STA operating on the second link. Wherein, the first link is the primary link, and the second link is a non-primary link. The first and second links are link pairs that operate in non-simultaneous transmission and reception (NSTR). The ML element includes a public information field. The public information field includes first and second sub-fields. The first sub-field includes information about the change of the primary link from the first link to the second link, and The second subfield includes information about when the primary link was changed from the first link to the second link.

15. At least one computer-readable medium (CRM) storing instructions, said instructions performing operations based on execution by at least one processor, said operations comprising: Receive multilink (ML) elements from the transmitting multilink device (MLD) via the first link; as well as Decode the ML element, The MLD transmission includes a first transmitting station (STA) operating on the first link and a second transmitting STA operating on the second link. The receiving MLD includes a first receiving STA operating on the first link and a second receiving STA operating on the second link. Wherein, the first link is the primary link, and the second link is a non-primary link. The first and second links are link pairs that operate in non-simultaneous transmission and reception (NSTR). The ML element includes a public information field. The public information field includes a first subfield and a second subfield. The first sub-field includes information about the change of the primary link from the first link to the second link, and The second subfield includes information about when the primary link was changed from the first link to the second link.

16. An apparatus in a wireless local area network (WLAN) system, the apparatus comprising: Memory; as well as A processor, operatively coupled to the memory, The processor is configured as follows: The multi-link (ML) element is received from the transmitting multi-link device (MLD) via the first link; and Decode the ML element, The MLD transmission includes a first transmitting station (STA) operating on the first link and a second transmitting STA operating on the second link. The receiving MLD includes a first receiving STA operating on the first link and a second receiving STA operating on the second link. Wherein, the first link is the primary link, and the second link is a non-primary link. The first and second links are link pairs that operate in non-simultaneous transmission and reception (NSTR). The ML element includes a public information field. The public information field includes first and second sub-fields. The first sub-field includes information about the change of the primary link from the first link to the second link, and The second subfield includes information about when the primary link was changed from the first link to the second link.

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