Method and apparatus for acquiring information about inter-MLD links in wireless LAN system

Abstract

To provide a method and an apparatus for acquiring information about inter-MLD links in a wireless LAN system.SOLUTION: A method and an apparatus for acquiring information about inter-MLD links in a wireless LAN system are proposed. Specifically, a receiving MLD transmits a probe request frame to a transmitting MLD via a first link. The receiving MLD receives a probe response frame from the transmitting MLD via the first link. The transmitting MLD includes a first transmitting STA operating in the first link, a second transmitting STA operating in a second link, and a third transmitting STA operating in a third link. The receiving MLD includes a first receiving STA operating in the first link. When the first receiving STA requests information about the second and third links, the probe request frame includes link identifiers for the second and third links. When the first receiving STA requests information about all links, the probe request frame does not include link identifiers for all the links.SELECTED DRAWING: Figure 30

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 obtaining information on an MLD-to-MLD link.

Background Art

[0002] WLAN (wireless local area network) has been improved in various ways. For example, the IEEE802.11ax standard proposed an improved communication environment using OFDMA (orthogonal frequency division multiple access) and DL MU MIMO (downlink multi-user multiple input, multiple output) technologies.

[0003] This specification proposes technical features that can be utilized in new communication standards. For example, the new communication standard is the recently discussed EHT (Extreme high throughput) standard. The EHT standard can use newly proposed increased bandwidth, improved PPDU (PHY layer protocol data unit) structure, improved sequence, HARQ (Hybrid automatic repeat request) technology, etc. The EHT standard can be called the IEEE802.11be standard.

[0004] In the new wireless LAN standard, an increased number of spatial streams are used. In this case, it is necessary to improve the signaling technology in the wireless LAN system in order to appropriately use the increased number of spatial streams.

Summary of the Invention

Problems to be Solved by the Invention

[0005] This specification proposes a method and apparatus for obtaining information on an MLD-to-MLD link in a wireless LAN system.

Means for Solving the Problem

[0006] In an example of this specification, a method for obtaining information about the link between MLDs is proposed.

[0007] This embodiment can be executed in a network environment supported by a next-generation wireless LAN system (IEEE 802.11be or EHT wireless LAN system). The next-generation wireless LAN system can satisfy backward compatibility with the 802.11ax system as a wireless LAN system that improves the 802.11ax system.

[0008] This embodiment proposes a method and apparatus for a receiving MLD (Multi-link Device) in MLD communication to request information about all or some of the links of a transmitting MLD. The transmitting MLD may be an AP MLD, and the receiving MLD may be a non-AP MLD.

[0009] The receiving MLD transmits a probe request frame to the transmitting MLD via a first link.

[0010] The receiving MLD receives a probe response frame from the transmitting MLD via the first link.

[0011] As an example, the transmitting MLD includes a first transmitting STA (station) operating on the first link, a second transmitting STA operating on the second link, and a third transmitting STA operating on the third link. The receiving MLD includes a first receiving STA operating on the first link. The receiving MLD may further include a second receiving STA operating on the second link and a third receiving STA operating on the third link.

[0012] When the first receiving STA requests information about the second and third links, the probe request frame includes link identifiers for the second and third links. That is, when the first receiving STA only wishes to obtain information about a specific link from the first transmitting STA, the link identifier for the specific link can be included in the probe request frame to indicate the necessary information.

Advantages of the Invention

[0013] According to the embodiments proposed in this specification, when the receiving STA requests information about all links, there is no need to include identifiers for all links (either omit or exclude identifiers for all links), so there is an effect of reducing the overhead of the probe request frame.

Brief Description of the Drawings

[0014]

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Mode for Carrying Out the Invention

[0015] In this specification, "A or B" can mean "only A", "only B", or "both A and B". Also, in this specification, "A or B" can be interpreted as "A and / or B". For example, in this specification, "A, B or C" can mean "only A", "only B", "only C", or "any combination of A, B and C".

[0016] The slashes ( / ) and commas used in this specification can mean "and / or". For example, "A / B" can mean "A and / or B". Thus, "A / B" can mean "only A", "only B", or "both A and B". For example, "A, B, C" can mean "A, B or C".

[0017] In this specification, "at least one of A and B" can mean "only A", "only B", or "both A and B". Also, in this specification, expressions such as "at least one of A or B" and "at least one of A and / or B" can be interpreted in the same way as "at least one of A and B".

[0018] Also, in this specification, "at least one of A, B, and C" can mean "only A", "only B", "only C", or "any combination of A, B, and C". Also, "at least one of A, B, or C" and "at least one of A, B, and / or C" can mean "at least one of A, B, and C".

[0019] Also, the parentheses used in this specification can mean "for example". Specifically, when it is shown as "control information (PDCCH)", "PDCCH" is proposed as an example of "control information". Also, the "control information" in this specification is not limited to "PDCCH", and "PDDCH" is proposed as an example of "control information". Also, when it is shown as "control information (that is, PDCCH)", "PDCCH" is proposed as an example of "control information".

[0020] In this specification, the technical features individually described within one drawing can be embodied individually or simultaneously.

[0021] The following example in this specification is applicable to various wireless communication systems. For example, the following example in this specification is applicable to a wireless local area network (WLAN) system. For example, this specification is applicable to the IEEE 802.11a / g / n / ac standards and the IEEE 802.11ax standard. Also, this specification is applicable to the newly proposed EHT standard or the IEEE 802.11be standard. Further, an example in this specification is also applicable to a new wireless LAN standard that enhances the EHT standard or the IEEE 802.11be. Also, an example in this specification is applicable to a mobile communication system. For example, it is applicable to a mobile communication system based on LTE (Long Term Evolution) based on the 3GPP (Registered Trademark) (3rd Generation Partnership Project) standard and its evolution. Also, an example in this specification is applicable to a communication system of the 5GNR standard based on the 3GPP standard.

[0022] Hereinafter, in order to explain the technical features of this specification, the technical features to which this specification is applicable will be described.

[0023] FIG. 1 shows an example of a transmission device and / or a reception device in this specification.

[0024] An example of FIG. 1 can perform various technical features described below. FIG. 1 is related to at least one STA (station). For example, the STAs (110, 120) in this specification are called by various names such as mobile terminal, wireless device, Wireless Transmit / Receive Unit (WTRU), User Equipment (UE), Mobile Station (MS), Mobile Subscriber Unit, or simply user. The STAs (110, 120) in this specification are called by various names such as network, Base Station, Node-B, AP (Access Point), repeater, router, relay, etc. The STAs (110, 120) in this specification are called by various names such as receiving device, transmitting device, receiving STA, transmitting STA, receiving Device, transmitting Device, etc.

[0025] For example, the STAs (110, 120) can perform the role of an AP (Access Point) or perform a non-AP role. That is, the STAs (110, 120) in this specification can perform the functions of an AP and / or a non-AP. In this specification, an AP can also be denoted as an AP STA.

[0026] The STAs (110, 120) in this specification can support various communication standards other than the IEEE802.11 standard. For example, it can support communication standards related to 3GPP standards (e.g., LTE, LTE-A, 5GNR standards), etc. Also, the STA in this specification is implemented in various devices such as mobile phones, vehicles, personal computers, etc. Further, the STA in this specification can support communication for various communication services such as voice calls, video calls, data communication, self-driving (Autonomous-Driving).

[0027] In this specification, the STA (110, 120) can include a medium access control (MAC) that complies with the provisions of the IEEE 802.11 standard and a physical layer interface for the wireless medium.

[0028] Based on FIG. 1(a), the STA (110, 120) is described as follows.

[0029] The first STA (110) includes a processor (111), a memory (112), and a transceiver (113). The shown processor, memory, and transceiver are implemented as separate chips respectively, or at least two or more blocks / functions are implemented via one chip.

[0030] The transceiver (113) of the first STA performs signal transmission and reception operations. Specifically, it can transmit and receive IEEE 802.11 packets (for example, IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0031] For example, the first STA (110) can perform the intended operations of an AP. For example, the processor (111) of the AP can receive signals via the transceiver (113), process the received signals, generate transmission signals, and execute control for signal transmission. The memory (112) of the AP can store the signals received via the transceiver (i.e., the received signals), and can store the signals transmitted via the transceiver (i.e., the transmission signals).

[0032] For example, the second STA (120) can perform the intended operations of a Non-AP STA. For example, the transceiver (123) of the non-AP performs signal transmission and reception operations. Specifically, it can transmit and receive IEEE 802.11 packets (for example, IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0033] For example, the processor (121) of the Non-AP STA can receive signals via the transceiver (123), process the received signals, generate transmission signals, and execute control for signal transmission. The memory (122) of the Non-AP STA can store signals received via the transceiver (123) (i.e., received signals), and can store signals transmitted via the transceiver (i.e., transmission signals).

[0034] For example, in the following specification, the operations of the device indicated as AP are executed in the first STA (110) or the second STA (120). For example, when the first STA (110) is the AP, the operations of the device indicated as AP are controlled by the processor (111) of the first STA (110), and related signals are transmitted or received via the transceiver (113) controlled by the processor (111) of the first STA (110). Also, the control information related to the operations of the AP and the transmission / reception signals of the AP are stored in the memory (112) of the first STA (110). Also, when the second STA (110) is the AP, the operations of the device indicated as AP are controlled by the processor (121) of the second STA (120), and related signals are transmitted or received via the transceiver (123) controlled by the processor (121) of the second STA (120). Also, the control information related to the operations of the AP and the transmission / reception signals of the AP are stored in the memory (122) of the second STA (110).

[0035] For example, in the following specification, the operations of the device displayed as non-AP (or User-STA) are executed at the first STA (110) or the second STA (120). For example, when the second STA (120) is non-AP, the operations of the device displayed as non-AP are controlled by the processor (121) of the second STA (120), and related signals are transmitted or received via the transceiver (123) controlled by the processor (121) of the second STA (120). Also, the control information related to the operations of non-AP and the transmission / reception signals of the AP are stored in the memory (122) of the second STA (120). For example, when the first STA (110) is non-AP, the operations of the device displayed as non-AP are controlled by the processor (111) of the first STA (110), and related signals are transmitted or received via the transceiver (113) controlled by the processor (111) of the first STA (120). Also, the control information related to the operations of non-AP and the transmission / reception signals of the AP are stored in the memory (112) of the first STA (110).

[0036] In the following specification, devices such as (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) Terminal, (transmitting / receiving) Device, (transmitting / receiving) apparatus, and network mean the STA (110, 120) in FIG. 1. For example, devices displayed as (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) Terminal, (transmitting / receiving) Device, (transmitting / receiving) apparatus, network, etc. without specific reference signs also mean the STA (110, 120) in FIG. 1. For example, in the following example, the operation of various STAs transmitting and receiving signals (e.g., PPPDU) may be executed in the transceivers (113, 123) of FIG. 1. Also, in the following example, the operation of various STAs generating transmission and reception signals or performing data processing and calculations in advance for transmission and reception signals may be executed in the processors (111, 121) of FIG. 1. For example, an example of the operation of generating transmission and reception signals or performing data processing and calculations in advance for transmission and reception signals includes: 1) the operation of determining / acquiring / configuring / calculating / decoding / encoding the bit information of the sub-field (SIG, STF, LTF, Data) fields included in the PPPDU; 2) the operation of determining / configuring / acquiring time resources and frequency resources (e.g., sub-carrier resources) used for the sub-field (SIG, STF, LTF, Data) fields included in the PPPDU; 3) the operation of determining / configuring / acquiring specific sequences (e.g., pilot sequence, STF / LTF sequence, extra sequence applied to SIG) used for the sub-field (SIG, STF, LTF, Data) fields included in the PPPDU; 4) the power control operation and / or power saving operation applied to the STA; 5) operations related to the determination / acquisition / configuring / calculating / decoding / encoding of the ACK signal, etc.Also, in the following example, various information (e.g., information related to fields / sub-fields / control fields / parameters / powers, etc.) used by various STAs for determining / acquiring / composing / operating / decoding / encoding transmission and reception signals is stored in the memories (112, 122) of FIG. 1.

[0037] The apparatus / STA of FIG. 1(a) described above is modified as shown in FIG. 1(b). Based on the following FIG. 1(b), the STAs (110, 120) in this specification will be described.

[0038] For example, the transceivers (113, 123) shown in FIG. 1(b) can perform the same functions as the transceivers shown in FIG. 1(a) described above. For example, the processing chips (114, 124) shown in FIG. 1(b) can include processors (111, 121) and memories (112, 122). The processors (111, 121) and memories (112, 122) shown in FIG. 1(b) can perform the same functions as the processors (111, 121) and memories (112, 122) shown in FIG. 1(a) described above.

[0039] The mobile terminal, wireless device, Wireless Transmit / Receive Unit (WTRU), User Equipment (UE), Mobile Station (MS), Mobile Subscriber Unit, user, user STA, network, Base Station, Node-B, Access Point (AP), repeater, router, relay, receiving device, transmitting device, receiving STA, transmitting STA, receiving Device, transmitting Device, receiving Apparatus, and / or transmitting Apparatus described below mean the STAs (110, 120) shown in FIGS. 1(a) / (b), or the processing chips (114, 124) shown in FIG. 1(b). That is, the technical features of this specification can be executed on the STAs (110, 120) shown in FIGS. 1(a) / (b), or may be executed only on the processing chips (114, 124) shown in FIG. 1(b). For example, the technical feature that the transmitting STA transmits a control signal can be understood as the technical feature that the control signal generated in the processors (111, 121) shown in FIGS. 1(a) / (b) is transmitted via the transceivers (113, 123) shown in FIGS. 1(a) / (b). Or, the technical feature that the transmitting STA transmits a control signal can be understood as the technical feature that the control signal transmitted to the transceivers (113, 123) is generated in the processing chips (114, 124) shown in FIG. 1(b).

[0040] For example, the technical feature that the receiving STA receives a control signal can be understood as the technical feature that the control signal is received by the transceivers (113, 123) shown in FIG. 1(a). Or, the technical feature that the receiving STA receives a control signal can be understood as the technical feature that the control signal received by the transceivers (113, 123) shown in FIG. 1(a) is acquired by the processors (111, 121) shown in FIG. 1(a). Or, the technical feature that the receiving STA receives a control signal can be understood as the technical feature that the control signal received by the transceivers (113, 123) shown in FIG. 1(b) is acquired by the processing chips (114, 124) shown in FIG. 1(b).

[0041] Referring to FIG. 1(b), software codes (115, 125) are included in the memories (112, 122). The software codes (115, 125) include instructions for controlling the operations of the processors (111, 121). The software codes (115, 125) are included in various programming languages.

[0042] The processors (111, 121) or processing chips (114, 124) shown in FIG. 1 can include an ASIC (application-specific integrated circuit), other chip sets, logic circuits, and / or data processing devices. The processor is an AP (application processor). For example, the processors (111, 121) or processing chips (114, 124) shown in FIG. 1 can include at least one of a DSP (digital signal processor), a CPU (central processing unit), a GPU (graphics processing unit), and a modem (modulator and demodulator). For example, the processors (111, 121) or processing chips (114, 124) shown in FIG. 1 can be a SNAPDRAGON manufactured by Qualcomm (registered trademark) TMSeries processors, EXYNOS manufactured by Samsung (registered trademark) TM Series processors, A series processors manufactured by Apple (registered trademark), HELIO manufactured by MediaTek (registered trademark) TM Series processors, ATOM manufactured by INTEL (registered trademark) TM It is a series processor or a processor that enhances this.

[0043] In this specification, the uplink means a link for communication from a non-AP STA to an AP STA, and an uplink PPDU / packet / signal, etc. is transmitted via the uplink. Also, in this specification, the downlink means a link for communication from an AP STA to a non-AP STA, and a downlink PPDU / packet / signal, etc. is transmitted via the downlink.

[0044] Figure 2 is a conceptual diagram showing the structure of a wireless LAN (WLAN).

[0045] The upper part of Figure 2 shows the structure of the IEEE (Institute of Electrical and Electronic Engineers) 802.11 infrastructure BSS (Basic Service Set).

[0046] Referring to the upper part of Figure 2, the wireless LAN system can include one or more infrastructure BSSs (200, 205) (hereinafter, BSS). BSS (200, 205) is not a concept referring to a specific area as a set of an AP (Access Point, 225) and an AP and STA such as STA1 (Station, 200-1) that can communicate with each other by synchronizing normally. BSS (205) can include one or more connectable STAs (205-1, 205-2) to one AP (230).

[0047] A BSS can include at least one STA, an AP (225, 230) that provides a distribution service, and a distribution system (DS, 210) that connects multiple APs.

[0048] The distribution system (210) can connect multiple BSSs (200, 205) to implement an extended service set (ESS, 240). The ESS (240) is used as a term to indicate a single network formed by connecting one or more APs via the distribution system (210). The APs included in a single ESS (240) have the same SSID (service set identification).

[0049] The portal (220) can perform the role of a bridge that executes the connection between a wireless LAN network (IEEE802.11) and other networks (e.g., 802.X).

[0050] In the BSS as shown in the upper part of Figure 2, the network between the APs (225, 230) and the network between the APs (225, 230) and the STAs (200-1, 205-1, 205-2) are implemented. However, it is also possible to set up a network and communicate directly between STAs without the APs (225, 230). A network that sets up a network and communicates directly between STAs without the APs (225, 230) is defined as an ad-hoc network or an independent basic service set (IBSS).

[0051] The lower part of Figure 2 is a conceptual diagram showing an IBSS.

[0052] Referring to the lower part of FIG. 2, an IBSS is a BSS operating in ad hoc mode. Since an IBSS does not include an AP, there is no centralized management entity that executes management functions in the center. That is, in an IBSS, STAs (250-1, 250-2, 250-3, 255-4, 255-5) are managed in a distributed manner. In an IBSS, all STAs (250-1, 250-2, 250-3, 255-4, 255-5) are composed of mobile STAs, and connections to a distribution system are not permitted, forming a self-contained network.

[0053] FIG. 3 is a drawing explaining a normal link setup process.

[0054] In the shown step S310, the STA can perform an operation of finding a network. The operation of finding a network can include a scanning operation of the STA. That is, in order for the STA to access a network, it is necessary to find a network that can be joined. The STA needs to identify a compatible network before participating in a wireless network, and the process of identifying a network existing in a specific area is called scanning. There are active scanning and passive scanning as scanning methods.

[0055] FIG. 3 exemplarily shows an operation of finding a network including an active scanning process. In active scanning, a STA that performs scanning sends a probe request frame to move channels and search for which APs exist in the vicinity and waits for a response thereto. A responder sends a probe response frame as a response to the probe request frame to the STA that sent the probe request frame. Here, the responder is the STA that last sent a beacon frame in the BSS of the channel being scanned. In a BSS, since an AP sends a beacon frame, the AP becomes the responder, and in an IBSS, since a STA within the IBSS sends back a beacon frame, the responder is not constant. For example, a STA that sends a probe request frame on channel 1 and receives a probe response frame on channel 1 stores the BSS-related information included in the received probe response frame, moves to the next channel (e.g., channel 2), and can perform scanning in the same manner (i.e., send and receive probe requests / responses on channel 2).

[0056] Although not shown as an example in FIG. 3, the scanning operation may be performed by the passive scanning method. A STA that performs scanning based on passive scanning can wait for a beacon frame while moving channels. The beacon frame is one of the management frames in IEEE 802.11, which notifies the presence of a wireless network, and is periodically transmitted to find a wireless network for a STA performing scanning and allow the STA to participate in the wireless network. In a BSS, the AP performs the role of periodically transmitting the beacon frame, and in an IBSS, the STA within the IBSS transmits the beacon frame back. A STA performing scanning stores the information on the BSS included in the beacon frame when receiving the beacon frame, and records the beacon frame information on each channel while moving to other channels. A STA that has received a beacon frame stores the BSS-related information included in the received beacon frame, and can move to the next channel and perform scanning on the next channel in the same way.

[0057] A STA that has discovered a network can execute an authentication process via step S320. Such an authentication process is referred to as the first authentication process in order to clearly distinguish it from the security setting operation in step S340 described later. The authentication process in S320 can include a process in which the STA transmits an authentication request frame to the AP and, in response, the AP transmits an authentication response frame to the STA. The authentication frame used for the authentication request / response corresponds to the management frame.

[0058] The authentication frame can include information regarding an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), a Finite Cyclic Group, etc.

[0059] The STA can send an authentication request frame to the AP. Based on the information contained in the received authentication request frame, the AP can determine whether to permit the authentication for the corresponding STA. The AP can provide the result of the authentication process to the STA via an authentication response frame.

[0060] The normally authenticated STA can execute the connection process based on step S330. The connection process includes the process in which the STA transmits an association request frame to the AP, and in response, the AP transmits an association response frame to the STA. For example, the association request frame can include information related to various capabilities, beacon listen interval, SSID (service set identifier), supported rates, supported channels, RSN, mobility domain, supported operating classes, TIM (Traffic Indication Map) broadcast request, information on inter-working service capabilities, and the like. For example, the association response frame can include information related to various capabilities, status code, AID (Association ID), supported rate, EDCA (Enhanced Distributed Channel Access) parameter set, RCPI (Received Channel Power Indicator), RSNI (Received Signal to Noise Indicator), mobility domain, timeout interval (association comeback time), overlapping BSS scan parameters, TIM broadcast response, QoS map, and the like.

[0061] Thereafter, in step S340, the STA can execute the security setting process. The security setting process in step S340 can include, for example, a process of setting a private key via a 4-way handshake via an EAPOL (Extesible Authntication Protocol over LAN) frame.

[0062] Figure 4 is a drawing showing an example of a PPDU used in the IEEE standard.

[0063] As shown, various forms of PPDU (PHY protocol data unit) are used in standards such as IEEE a / g / n / ac. Specifically, the LTF and STF fields contain training signals, the SIG-A and SIG-B contain control information for the receiving station, and the data field contains user data corresponding to the PSDU (MAC PDU / Aggregated MAC PDU).

[0064] Figure 4 also includes an example of an HE PPDU of the IEEE 802.11ax standard. The HE PPDU according to Figure 4 is an example of a PPDU for multiple users. HE-SIG-B is included only in the case of multiple users, and the corresponding HE-SIG-B is omitted from the PPDU for a single user.

[0065] As shown, the HE-PPDU for multiple users (Multiple User; MU) can include an L-STF (legacy-short training field), an L-LTF (legacy-long training field), an L-SIG (legacy-signal), an HE-SIG-A (high efficiency-signal A), an HE-SIG-B (high efficiency-signal-B), an HE-STF (high efficiency-short training field), an HE-LTF (high efficiency-long training field), a data field (or MAC payload), and a PE (Packet Extension) field. Each field is transmitted during the indicated time interval (i.e., 4 or 8 μs, etc.).

[0066] The resource unit (RU) used in the PPDU is described as follows. The resource unit can include a plurality of subcarriers (or tones). The resource unit is used when transmitting signals to a number of STAs based on the OFDMA technology. Also, a resource unit is defined even when transmitting a signal to one STA. The resource unit is used for the STF, LTF, data field, etc.

[0067] The RUs described in this specification are used for UL (Uplink) communication and DL (Downlink) communication. For example, when UL-MU communication solicited by a Trigger frame is performed, the transmitting STA (e.g., AP) can allocate a first RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to the first STA and a second RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to the second STA via the Trigger frame. Thereafter, 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 / second Trigger-based PPDUs are transmitted to the AP in the same time interval.

[0068] For example, when a DL MU PPDU is configured, the transmitting STA (e.g., AP) can allocate a first RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to the first STA and a second RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to the second STA. That is, the transmitting STA (e.g., AP) can transmit the HE-STF, HE-LTF, and Data fields for the first STA via the first RU and the HE-STF, HE-LTF, and Data fields for the second STA via the second RU within one MU PPDU.

[0069] FIG. 5 shows the operation related to UL-MU. As shown, the transmitting STA (e.g., AP) can execute channel connection through contending (i.e., Backoff operation) and transmit Trigger frame 1030. That is, the transmitting STA (e.g., AP) can transmit a PPDU containing Trigger frame 1330. If a PPDU containing a Trigger frame is received, after a delay of only SIFS, a TB (trigger-based) PPDU is transmitted.

[0070] TB PPDUs 1041 and 1042 are transmitted in the same time slot and are transmitted from a plurality of STAs (e.g., User STAs) whose AIDs are indicated in Trigger frame 1030. ACK frames 1050 for the TB PPDUs are implemented in various forms.

[0071] The specific features of the trigger frame are described via FIGS. 6 to 8. Even when UL-MU communication is used, OFDMA (Orthogonal Frequency Division Multiple Access) technology or MU MIMO technology is used, and OFDMA and MU MIMO technologies are used simultaneously.

[0072] FIG. 6 shows an example of a trigger frame. The trigger frame in FIG. 6 allocates resources for uplink MU transmission (Uplink Multiple-User transmission) and is transmitted from, for example, an AP. The trigger frame is composed of a MAC frame and is included in the PPDU.

[0073] Each field shown in FIG. 6 can be partially omitted, and another field can be added. Also, the length of each field changes to be different from that shown.

[0074] The frame control field 1110 in FIG. 6 contains information regarding the version of the MAC protocol and other additional control information, and the duration field 1120 contains time information for NAV setting and information regarding the identifier of the STA (e.g., AID).

[0075] Also, the RA field 1130 contains the address information of the receiving STA of the trigger frame and can be omitted if necessary. The TA field 1140 contains the address information of the STA (e.g., AP) that transmits the trigger frame, and the common information field 1150 contains common control information applied to the receiving STA that receives the trigger frame. For example, it includes a field that indicates the length of the L-SIG field of the up PPDU transmitted corresponding to the trigger frame, and information that controls the content of the SIG-A field (i.e., the HE-SIG-A field) of the up PPDU transmitted corresponding to the trigger frame. Also, as common control information, it includes information regarding the length of the CP of the up PPDU transmitted corresponding to the trigger frame and information regarding the length of the LTF field.

[0076] Also, it is desirable to include per user information fields (1160#1 to 1160#N) corresponding to the number of receiving STAs that receive the trigger frame in FIG. 6. The per user information field can also be referred to as the "allocation field".

[0077] Also, the trigger frame in FIG. 6 can include a padding field 1170 and a frame check sequence field 1180.

[0078] Each of the per user information fields (1160#1 to 1160#N) shown in FIG. 6 can again include a number of sub-fields.

[0079] Figure 7 shows an example of the common information field of the trigger frame. Among the sub-fields in Figure 7, some can be omitted, and other sub-fields can be added. Also, the length of each of the shown sub-fields can be modified.

[0080] The shown length field 1210 has the same value as the length field of the L-SIG field of the up PPDU transmitted corresponding to the trigger frame, and the length field of the L-SIG field of the up PPDU indicates the length of the up PPDU. As a result, the length field 1210 of the trigger frame is used to indicate the length of the corresponding uplink PPDU.

[0081] Also, the cascade indicator field 1220 indicates whether the cascade operation is to be executed. The cascade operation means that both downlink MU transmission and uplink MU transmission are executed within the same TXOP. That is, it means that after the downlink MU transmission is executed, after a preset time (e.g., SIFS), the uplink MU transmission is executed. In the cascade operation, there is only one transmission device (e.g., AP) that performs downlink communication, and there can be multiple transmission devices (e.g., non-AP) that perform uplink communication.

[0082] The CS request field 1230 indicates whether it is necessary to consider the state of the wireless medium, NAV, etc. in the situation where the receiving device that receives the trigger frame transmits the corresponding uplink PPDU.

[0083] The HE-SIG-A information field 1240 contains information that controls the content of the SIG-A field (i.e., the HE-SIG-A field) of the up PPDU transmitted corresponding to the trigger frame.

[0084] The CP and LTF type field 1250 can include information regarding the length of the LTF and the CP length of the uplink PPDU transmitted corresponding to the trigger frame. The trigger type field 1060 can indicate the purpose for which the trigger frame is used, such as a normal trigger, a trigger for beamforming, a request for Block Ack / NACK, etc.

[0085] In this specification, it can be assumed that the trigger type field 1260 of the trigger frame indicates a basic type of trigger frame for a normal trigger. For example, a basic type of trigger frame is referred to as a basic trigger frame.

[0086] FIG. 8 shows an example of sub-fields included in the per user information field. The user information field 1300 in FIG. 8 is understood as any one of the individual user information fields (1160#1 to 1160#N) mentioned in FIG. 6 above. Among the sub-fields included in the user information field 1300 in FIG. 8, some can be omitted, and other sub-fields can be added. Also, the length of each of the shown sub-fields can be modified.

[0087] The User Identifier field 1310 in FIG. 8 indicates the identifier of the STA (i.e., the receiving STA) corresponding to the per user information. An example of the identifier is all or part of the AID (association identifier) value of the receiving STA.

[0088] Also, an RU Allocation field 1320 is included. That is, when the receiving STA identified as the user identifier field 1310 transmits a TB PPDU corresponding to the trigger frame, the TB PPDU is transmitted via the RU indicated by the RU Allocation field 1320.

[0089] The subfield of FIG. 8 can include a coding type field 1330. The coding type field 1330 can indicate the coding type of the TB PPDU. For example, when BCC coding is applied to the TB PPDU, the coding type field 1330 is set to "1", and when LDPC coding is applied, the coding type field 1330 is set to "0".

[0090] Also, the subfield of FIG. 8 can include an MCS field 1340. The MCS field 1340 can indicate the MCS technology applied to the TB PPDU. For example, when BCC coding is applied to the TB PPDU, the coding type field 1330 is set to "1", and when LDPC coding is applied, the coding type field 1330 is set to "0".

[0091] The following UORA (UL OFDMA-based Random Access) technology will be described.

[0092] FIG. 9 illustrates the technical features of the UORA technology.

[0093] The transmitting STA (e.g., AP) can allocate 6 RU resources as shown in FIG. 9 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 regarding AID 0, AID 3, or AID 2045 is included, for example, in the user identification field 1310 of FIG. 8. Information regarding RU 1 to RU 6 is included, for example, in the RU allocation field 1320 of FIG. 8. AID = 0 means a UORA resource for an associated STA, and AID = 2045 means a UORA resource for an un-associated STA. Accordingly, the first to third RU resources in FIG. 9 are used as UORA resources for an associated STA, the fourth to fifth RU resources in FIG. 9 are used as UORA resources for an un-associated STA, and the sixth RU resource in FIG. 9 is used as a resource for normal UL MU.

[0094] In an example of FIG. 9, the OBO (OFDMA random access Back Off) counter of STA1 decreases to 0, and STA1 randomly selects the second RU resource (AID 0, RU 2). Also, since the OBO counters of STA2 / 3 are greater than 0, no uplink resources are allocated to STA2 / 3. Also, in FIG. 9, since the AID of STA4 (i.e., AID = 3) is included in the trigger frame, the resource of RU 6 is allocated without backoff.

[0095] Specifically, since STA1 in FIG. 9 is an associated STA, there are a total of 3 eligible RA RUs for STA1 (RU 1, RU 2, RU 3). Accordingly, STA1 decreased the OBO counter by 3 and the OBO counter became 0. Also, since STA2 in FIG. 9 is an associated STA, there are a total of 3 eligible RA RUs for STA2 (RU 1, RU 2, RU 3). Accordingly, STA2 decreased the OBO counter by 3, but the OBO counter is in a state greater than 0. Also, since STA3 in FIG. 9 is an un-associated STA, there are a total of 2 eligible RA RUs for STA3 (RU 4, RU 5). Accordingly, STA3 decreased the OBO counter by 2, but the OBO counter is in a state greater than 0.

[0096] As follows, the PPDU transmitted / received in the STA of this specification is described.

[0097] FIG. 10 shows an example of the PPDU used in this specification.

[0098] The PPDU in FIG. 10 can be called by various names such as an EHT PPDU, a transmission PPDU, a reception PPDU, a first type or an Nth type PPDU. For example, in this specification, the PPDU or the EHT PPDU can be called by various names such as a transmission PPDU, a reception PPDU, a first type or an Nth type PPDU. Also, the EHT PPU is used in an EHT system and / or a new wireless LAN system that improves the EHT system.

[0099] The PPDU in FIG. 10 can indicate some or all of the PPDU types used in the EHT system. For example, an example in FIG. 10 is used for both the SU (single-user) mode and the MU (multi-user) mode. In other words, the PPDU in FIG. 10 can be a PPDU for one receiving STA or multiple receiving STAs. When the PPDU in FIG. 10 is used for the TB (Trigger-based) mode, the EHT-SIG in FIG. 10 can be omitted. In other words, a STA that has received a Trigger frame for UL-MU (Uplink-MU) communication can transmit a PPDU in which the EHT-SIG is omitted in an example of FIG. 10.

[0100] In FIG. 10, from L-STF to EHT-LTF can be called a preamble or a physical preamble, and is generated / transmitted / received / acquired / decoded in the physical layer.

[0101] The subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields in FIG. 10 is set to 312.5 kHz, and the subcarrier spacing of the EHT-STF, EHT-LTF, and Data fields is set to 78.125 kHz. That is, the tone index (or subcarrier index) of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields is displayed 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.

[0102] The L-LTF and L-STF in the PPDU of FIG. 10 can be the same as the conventional fields.

[0103] The L-SIG field in FIG. 10 can include, for example, 24-bit bit information. For example, the 24-bit information can 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 can include information regarding the length or time duration of the PPDU. For example, the value of the 12-bit Length field is determined based on the type of the PPDU. For example, when the PPDU is a non-HT, HT, VHT PPDU or an EHT PPDU, the value of the Length field is determined as a multiple of 3. For example, when the PPDU is a HE PPDU, the value of the Length field is determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, for non-HT, HT, VHT PPDU or EHT PPDU, the value of the Length field can be determined as a multiple of 3, and for HE PPDU, the value of the Length field is determined as "a multiple of 3 + 1" or "a multiple of 3 + 2".

[0104] For example, the transmitting STA can apply coding that is a BCC based on a code rate of 1 / 2 to the 24-bit information in the L-SIG field. Subsequently, the transmitting STA can obtain 48-bit BCC-coded bits. BPSK modulation is applied to the 48-bit coded bits to generate 48 BPSK symbols. The transmitting STA can map the 48 BPSK symbols to positions excluding the pilot subcarriers {subcarrier indices -21, -7, +7, +21} and the DC subcarrier {subcarrier index 0}. As a result, the 48 BPSK symbols are mapped to subcarrier indices from -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 signals of {-1, -1, -1, 1} to subcarrier indices {-28, -27, +27, 28}. The above signals are used for channel estimation for the frequency region corresponding to {-28, -27, +27, 28}.

[0105] The transmitting STA can generate an RL-SIG that is generated in the same way as the L-SIG. BPSK modulation is applied to the RL-SIG. The receiving STA can determine that the received PPDU is a HE PPDU or an EHT PPDU based on the presence of the RL-SIG.

[0106] After the RL-SIG in FIG. 10, a U-SIG (Universal SIG) is inserted. The U-SIG can be called by various names such as the first SIG field, the first SIG, the first type SIG, the control signal, the control signal field, the first (type) control signal, etc.

[0107] U-SIG can contain N-bit information and can also contain information for identifying the type of EHT PPDU. For example, U-SIG is composed based on two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., OFDM symbol) for U-SIG can have a duration of 4 us. Each symbol of U-SIG is used to transmit 26-bit information. For example, each symbol of U-SIG is transmitted and received based on 52 data tones and 4 pilot tones.

[0108] For example, A-bit information (e.g., 52 un-coded bits) is transmitted via U-SIG (or the U-SIG field). The first symbol of U-SIG can transmit the first X-bit information (e.g., 26 un-coded bits) among the total A-bit information, and the second symbol of U-SIG can transmit the remaining Y-bit information (e.g., 26 un-coded bits) among the total A-bit information. For example, the transmitting STA can obtain the 26 un-coded bits included in each U-SIG symbol. The transmitting STA can perform convolutional encoding (i.e., coding which is BCC) based on 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 assigned to each U-SIG symbol. One U-SIG symbol is transmitted based on 56 tones (sub-carriers) from sub-carrier index -28 to sub-carrier index +28 except for the DC index 0. The 52 BPSK symbols generated by the transmitting STA are transmitted based on the remaining tones (sub-carriers) excluding the pilot tones -21, -7, +7, +21 tones.

[0109] For example, the A-bit information (e.g., 52 un-coded bit) transmitted by U-SIG can include a CRC field (e.g., a field with a length of 4 bits) and a tail field (e.g., a field with a length of 6 bits). The CRC field and the tail field are transmitted via the second symbol of U-SIG. The CRC field is generated based on 26 bits assigned to the first symbol of U-SIG and the remaining 16 bits excluding the CRC / tail field within the second symbol, and is generated based on a conventional CRC calculation algorithm. Also, the tail field is used to terminate the trellis of the convolutional decoder and is set to, for example, "000000".

[0110] The A-bit information (e.g., 52 un-coded bit) transmitted by U-SIG (or U-SIG field) can be divided into version-independent bits and version-dependent bits. For example, the size of the version-independent bits can be fixed or variable. For example, the version-independent bits are assigned only to the first symbol of U-SIG, or the version-independent bits are assigned to all of the first symbol and the second symbol of U-SIG. For example, the version-independent bits and the version-dependent bits can be called by various names such as the first control bit and the second control bit.

[0111] For example, the version-independent bits of 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 transmitted and received PPDU. For example, the first value of the 3-bit PHY version identifier can indicate that the transmitted and received 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 received PPDU is an EHT PPDU based on the PHY version identifier with the first value.

[0112] For example, the version-independent bits of U-SIG can include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field is related to UL communication, and the second value of the UL / DL flag field is related to DL communication.

[0113] For example, the version-independent bits of U-SIG can include information regarding the length of the TXOP and information regarding the BSS color ID.

[0114] For example, when EHT PPDUs are divided into various types (such as EHT PPDUs related to the SU mode, EHT PPDUs related to the MU mode, EHT PPDUs related to the TB mode, EHT PPDUs related to Extended Range transmission, etc.), information regarding the type of EHT PPDU is included in the version-dependent bits of U-SIG.

[0115] For example, the U-SIG may include: 1) a bandwidth field containing information about the bandwidth, 2) a field containing information about the MCS technology applied to the EHT-SIG, 3) an indication field containing information related to whether the dual subcarrier modulation (DCM) technology is applied to the EHT-SIG, 4) a field containing information about the number of symbols used for the EHT-SIG, 5) a field containing information related to whether the EHT-SIG is generated across the entire band, 6) a field containing information about the type of EHT-LTF / STF, and 7) information about a field indicating the length of the EHT-LTF and the CP length.

[0116] In the following example, signals represented by (transmission / reception / upload / download) signals, (transmission / reception / upload / download) frames, (transmission / reception / upload / download) packets, (transmission / reception / upload / download) data units, (transmission / reception / upload / download) data, etc. can be signals transmitted and received based on the PPDU of FIG. 10. The PPDU of FIG. 10 is used to transmit and receive various types of frames. For example, the PPDU of FIG. 10 is used for a control frame. An example of a control frame can include RTS (request to send), CTS (clear to send), PS-Poll (Power Save-Poll), Block ACK Req, Block Ack, NDP (Null Data Packet) announcement, Trigger frame. For example, the PPDU of FIG. 18 is used for a management frame. An example of a management frame can include a Beacon frame, (Re-)Association Request frame, (Re-)Association Response frame, Probe Request frame, Probe Response frame. For example, the PPDU of FIG. 10 is used for a data frame. For example, the PPDU of FIG. 10 is also used to simultaneously transmit at least two or more of a control frame, a management frame, and a data frame.

[0117] FIG. 11 shows a modified example of the transmission device and / or reception device of this specification.

[0118] Each device / STA in FIGS. 1(a) / (b) can be modified as shown in FIG. 11. The transceiver 630 in FIG. 11 can be the same as the transceivers 113 and 123 in FIG. 1. The transceiver 630 in FIG. 11 can include a receiver and a transmitter.

[0119] The processor 610 in FIG. 11 may be the same as the processors 111 and 121 in FIG. 1. Alternatively, the processor 610 in FIG. 11 may be the same as the processing chips 114 and 124 in FIG. 1.

[0120] The memory 150 in FIG. 11 may be the same as the memories 112 and 122 in FIG. 1. Alternatively, the memory 150 in FIG. 11 may be a separate external memory different from the memories 112 and 122 in FIG. 1.

[0121] Referring to FIG. 11, the power management module 611 manages the power for the processor 610 and / or the 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 keypad 614 receives the inputs used by the processor 610. The keypad 614 can be represented on the display 613. The SIM card 615 can be an integrated circuit used to securely store the IMSI (international mobile subscriber identity) and related keys used to identify and authenticate subscribers in mobile phone devices such as mobile phones and computers.

[0122] Referring to FIG. 11, the speaker 640 can output the sound-related results processed by the processor 610. The microphone 641 can receive the sound-related inputs used by the processor 610.

[0123] The technical features for the multi-link (ML) supported by the STA in the following specification are described.

[0124] The STA (AP and / or non-AP STA) in this specification can support MultiLink (ML) communication. ML communication means communication that supports multiple links. The links related to 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).

[0125] The multiple links used for ML communication are configured in various ways. For example, the multiple links supported by one STA for ML communication can be multiple channels within the 2.4 GHz band, multiple channels within the 5 GHz band, and multiple channels within the 6 GHz band. Or, the multiple links supported by one STA for ML communication can be a combination of at least one channel within the 2.4 GHz band (or 5 GHz / 6 GHz band) and at least one channel within the 5 GHz band (or 2.4 GHz / 6 GHz band). On the other hand, among the multiple links supported by one STA for ML communication, at least one can be a channel to which preamble puncturing is applied.

[0126] The STA can execute an ML setup to perform ML communication. The ML setup can be executed based on management frames and control frames such as Beacon, Probe Request / Response, and Association Request / Response. For example, the information related to the ML setup is included in the element field included in Beacon, Probe Request / Response, and Association Request / Response.

[0127] Once the ML setup is completed, an enabled link for ML communication is determined. The STA can perform frame exchange via at least one of the multiple links determined by the enabled link. For example, the enabled link is used for at least one of the management frame, control frame, and data frame.

[0128] When one STA supports multiple Links, the transmit-receive devices supporting each Link can operate as one logical STA. For example, one STA supporting two Links can be represented by one ML device (Multi Link Device; MLD) including a first STA for the first Link and a second STA for the second Link. For example, one AP supporting two Links can be represented by one AP MLD including a first AP for the first Link and a second AP for the second Link. Also, one non-AP supporting two Links can be represented by one non-AP MLD including a first STA for the first Link and a second STA for the second Link.

[0129] More specific features regarding the ML setup are described as follows.

[0130] MLD (AP MLD and / or non-AP MLD) can transmit information regarding links that the MLD can support via the ML setup. Information regarding the links is configured in various ways. For example, the information regarding the links can include at least one of 1) information regarding whether the MLD (or STA) supports simultaneous RX / TX operation, 2) information regarding the number / limit of uplink / downlink Links supported by the MLD (or STA), 3) information regarding the position / band / resource of the uplink / downlink Links supported by the MLD (or STA), 4) information regarding the type (management, control, data, etc.) of frames available or preferred in at least one uplink / downlink Link, 5) ACK policy information available or preferred in at least one uplink / downlink Link, and 6) information regarding the TID (traffic identifier) available or preferred in at least one uplink / downlink Link. The TID is related to the priority of traffic data and is represented by eight values according to the conventional wireless LAN standard. That is, eight TID values corresponding to four access categories (AC) (AC_BK (background), AC_BE (best effort), AC_VI (video), AC_VO (voice)) according to the conventional wireless LAN standard are defined.

[0131] For example, all TIDs are pre-set by being mapped to the uplink / downlink Link. Specifically, if no negotiation is performed via the ML setup, all TIDs are used for ML communication, and when the mapping between the uplink / downlink Link and the TID is negotiated via additional ML setup, the negotiated TIDs are used for ML communication.

[0132] Multiple Links related to ML communication can be set up via the ML setup and can be referred to as "enabled links". The "enabled links" can be called by various expressions. For example, they can be called by various expressions such as the first Link, the second Link, the transmission Link, the reception Link, etc.

[0133] After the ML setup is completed, the MLD can update the ML setup. For example, if the MLD needs to update the information related to the link, it can send the information related to the new link. The information related to the new link is sent based on at least one of the management frame, control frame, and data frame.

[0134] The devices described below can be the devices in FIG. 1 and / or FIG. 11, and the PPDU can be the PPDU in FIG. 10. The device can be an AP or a non-AP STA. The devices described below can be an AP MLD (multi-link Device) or a non-AP STA MLD that supports multi-link.

[0135] Since 802.11ax, in the EHT (Extremely High Throughput), which is a standard under discussion, a multi-link environment that uses one or more bands simultaneously is considered. If a device becomes capable of supporting multi-link, the device can use one or more bands (for example, 2.4 GHz, 5 GHz, 6 GHz, 60 GHz, etc.) simultaneously or alternately.

[0136] In the following specification, MLD means multi-link Device. An MLD has one or more connected STAs and has one MAC SAP (service access point) leading to the upper link layer (Logical Link Control, LLC). An MLD means a physical device or a logical device. In the following, a device means an MLD.

[0137] In the following specification, the transmitting device and the receiving device mean an MLD. The first link of the receiving / transmitting device can be a terminal (e.g., an STA or an AP) included in the receiving / transmitting device that performs signal transmission and reception via the first link. The second link of the receiving / transmitting device can be a terminal (e.g., an STA or an AP) included in the receiving / transmitting device that performs signal transmission and reception via the second link.

[0138] IEEE 802.11be can support two major types of multi-link operations. For example, STR (simultaneous transmit and receive) and non-STR operations are considered. For example, STR can be called an asynchronous multi-link operation, and non-STR can be called a synchronous multi-link operation. Multi-link can include multi-band. That is, multi-link means a link included in multiple frequency bands and can also mean multiple links included within one frequency band.

[0139] In EHT (11be), multi-link technology is considered, where multi-link can include multi-band. That is, multi-link can indicate links of multiple bands and at the same time can indicate multiple multi-links within one band. Two major types of multi-link operations are considered. Asynchronous operation that enables simultaneous TX / RX on multiple links and Synchronous operation that is not possible are considered. In the following, the capability to enable simultaneous reception and transmission on multiple links is called STR (simultaneous transmit and receive), a STA with STR capability is called an STR MLD (multi-link Device), and a STA without STR capability is called a non-STR MLD.

[0140] In the following specification, for convenience of explanation, it is described that an MLD (or the processor of the MLD) controls at least one STA, but it is not limited to this. As described above, the at least one STA can also transmit and receive signals independently of the MLD.

[0141] According to one embodiment, an AP MLD or a non-AP MLD is configured with a structure having multiple links. In other words, a non-AP MLD can support multiple links. A non-AP MLD can include multiple STAs. The multiple STAs can each have a Link.

[0142] In the EHT standard (802.11be standard), the MLD (Multi-Link Device) structure in which one AP / non-AP MLD supports multiple Links is considered as a major technology. The STAs included in the non-AP MLD can transfer information to another STA within the non-AP MLD together via one Link. Therefore, there is an effect of reducing the overhead of frame exchange. Also, there is an effect of increasing the link usage efficiency of the STA and reducing the power consumption.

[0143] Figure 12 shows an example of the structure of the non-AP MLD.

[0144] Referring to Figure 12, the non-AP MLD is configured with a structure having multiple Links. In other words, the non-AP MLD can support multiple Links. The non-AP MLD can include multiple STAs. Each of the multiple STAs can have a Link for each STA. Figure 12 shows an example of the non-AP MLD structure, but the structure of the AP MLD is also configured in the same way as the example of the non-AP MLD structure shown in Figure 12.

[0145] For example, the non-AP MLD can include STA1, STA2, and STA3. STA1 can operate on Link 1. Link 1 is included within the 5GHz band. STA2 can operate on link2. link2 is included within the 6GHz band. STA3 can operate on link3. link3 is included within the 6GHz band. The bands in which Link 1 / 2 / 3 are included are exemplary and are included within 2.4, 5, and 6GHz.

[0146] Thus, in the case of an AP / non-AP MLD that supports Multi-link, each AP of the AP MLD and each STA of the non-AP MLD are connected to their respective Links via the Link setup process. And at this time, the connected Link can be changed or reconnected to another Link by the AP MLD or the non-AP MLD depending on the situation.

[0147] Also, in the EHT standard, for power consumption reduction, Link can be divided into Anchored link or non - Anchored link. Anchored link or non - Anchored link can be called in various ways. For example, Anchored link can be called Primary Link. Non - Anchored link can be called Secondary link.

[0148] According to one embodiment, an AP MLD that supports Multi - link can manage each Link by designating it as an Anchored link or a non - Anchored Link. The AP MLD can support one or more Links out of the multiple Links as Anchored links. A non - AP MLD can use one or more of its own Anchored links by selecting them from the Anchored link List (the list of Anchored links supported by the AP MLD).

[0149] For example, the Anchored link is used not only for frame exchange for synchronization but also for non - data frame exchange (i.e., Beacon and Management frame). Also, the non - Anchored link is used only for data frame exchange.

[0150] Non-AP MLD can only monitor (or monitor) the Anchored link for receiving Beacons and Management frames during the idle period. Therefore, in the case of non-AP MLD, it is necessary to be connected to at least one Anchored link for receiving Beacons and management frames. The one or more Anchored links need to always maintain the enable state. In contrast, the non-Anchored link is only used for data frame exchange. Therefore, the STA corresponding to the non-Anchored link (or the STA connected to the non-Anchored link) can enter the doze state during the idle period when the channel / link is not used. This has the effect of reducing power consumption.

[0151] Therefore, in the following specification, a protocol is proposed in which AP MLD or non-AP MLD recommends or requests Link reconnection dynamically according to the situation for efficient Link connection. Also, in the following specification, an Anchored link reconnection protocol considering the characteristics of the Anchored link used for power reduction as well as the normal Link is further proposed.

[0152] Embodiments for Link Change and Reconnection

[0153] According to one embodiment, each Link between AP MLD and non-AP MLD is determined in the Association or (re)Association process. At this time, AP MLD and non-AP MLD can execute frame exchange through the connected Link. A specific embodiment in which AP MLD and non-AP MLD are connected through the Link setup process will be described with reference to FIG. 13.

[0154] FIG. 13 shows an example in which AP MLD and non-AP MLD are connected through the Link setup process.

[0155] Referring to FIG. 13, the AP MLD can include AP1, AP2, and AP3. The non-AP MLD can include STA1 and STA2. AP1 and STA1 are connected via Link 1. AP2 and STA2 are connected via link2.

[0156] For example, AP1 and STA1 are connected via Link 1 through the first Link setup process. AP2 and STA2 are connected via link2 through the second Link setup process. In another example, the AP MLD and the non-AP MLD are connected through one Link setup process. In other words, the AP MLD and the non-AP MLD are connected via Link 1 and link2 based on one Link setup process.

[0157] As described above, each AP and STA can perform frame exchange via the connected Link. Also, information about other APs or other STAs regarding other links is transmitted and received via one Link.

[0158] However, after such a Link setup process, depending on the situation / environment, the AP MLD or the non-AP MLD can request Link change or reconnection for more efficient frame exchange (e.g., load balancing or interference avoidance).

[0159] Embodiments regarding Link change or reconnection are described via FIG. 14.

[0160] FIG. 14 shows an example where the Link is changed or reconnected.

[0161] Referring to FIG. 14, conventionally, STA2 is connected to AP2. Subsequently, a transient data load of AP2 can occur. STA2 reconnects to AP3 with a relatively low data load. In this case, there is an effect that AP MLD and non-AP MLD can perform efficient data exchange.

[0162] FIG. 15 shows a specific example where a link is changed or reconnected.

[0163] Referring to FIG. 15, AP1 of AP MLD is connected to STA1 of non-AP MLD via Link 1. AP2 of AP MLD is connected to STA2 of non-AP MLD via link2. Subsequently, STA2 can attempt / request to connect to AP3 via link change or reconnection, and STA2 is connected to AP3 via link2 based on the link change or reconnection.

[0164] According to one embodiment, non-AP MLD and AP MLD can request a link transition for performance improvement. AP MLD and non-AP MLD can transmit / receive / exchange various information for each current link and information regarding the link state. Therefore, AP MLD and non-AP MLD can select a more suitable link for transmitting and receiving signals based on various information for each current link and the link state, and can transmit the above-mentioned information to support the selection. For example, various information for each current link can include information regarding data traffic load for each link and channel access capability between links. For example, the link state is set as disabled or enabled, etc.

[0165] In the following specification, the process of negotiating with the non - AP MLD / AP MLD to request a change or re - connection to another Link that is not the Link to which the AP MLD / non - AP MLD is connected to enhance performance is called "Link switching negotiation". The name of the said "Link switching negotiation" can be called in various ways and can be changed.

[0166] In the Link switching negotiation process, the non - AP MLD (or AP MLD) requests to change the Link connected to a specific STA to another Link, and in response to this request, the AP MLD (or non - AP MLD) can respond via a request approval or rejection message.

[0167] As an example, as shown in Figure 15, when a Link change is agreed upon via Link switching negotiation, the STA can execute a Link re - setup process of changing the existing Link from AP2 to AP3 and reconnecting.

[0168] In the following, the Link change or re - connection process is described separately for the case where the AP MLD requests it and the case where the non - AP MLD requests it.

[0169] Embodiments where the AP MLD Requests Link Change or Reconnection

[0170] According to one embodiment, the AP MLD can request a Link change or re - connection to the non - AP MLD for efficient data transmission. For example, based on the data traffic of each AP for load balancing, the AP MLD can request a more efficient Link change or re - connection to the STA.

[0171] For example, the AP MLD can calculate / confirm / determine a link suitable for the STA of the non-AP MLD based on the Data traffic load information for each AP and / or the Channel access capability information between each link (for example, information regarding the STR (Simultaneous TX / RX) capability, etc.). Subsequently, the AP MLD can request the STA (or non-AP MLD) to change or reconnect the link based on the Data traffic load information for each AP and / or the Channel access capability information between each link, etc.

[0172] As described above, when requesting a link change, the AP MLD can send the link information considered to be the most suitable to the non-AP MLD via a request message. For example, the request message can include a Beacon or a management frame, etc.

[0173] In relation to the above-described embodiment, a new element or field containing the link information considered to be the most suitable is proposed. The newly proposed element or field is defined as "recommended link". "Recommended link" is exemplary, and the name of the specific element or field can be changed.

[0174] recommend link(element / field) : An element or field for the AP MLD to recommend the most suitable link to the STA of the non-AP MLD based on various information for each link (for example, data load for each link, etc.). For example, the recommend link (element / field) is indicated by the Link ID information of the AP MLD or the AP BSS information, etc. In other words, the recommend link (element / field) can include the Link ID information of the AP MLD or the AP BSS information, etc.

[0175] According to one embodiment, the said recommend link (element / field) is optionally included in and transmitted with the Link switching Response. For example, the STA can establish a connection to the Link recommended by the AP based on the said element / field (i.e., the recommend link). In another example, the STA can also execute a connection request to a Link other than the instructed Link based on the said element / field (i.e., the recommend link) and additional information it has.

[0176] The specific signal exchange processes of the AP MLD and non-AP MLD according to the above-described embodiments will be described with reference to FIG. 16.

[0177] FIG. 16 shows the operations of the AP MLD and non-AP MLD for link change or reconnection.

[0178] Referring to FIG. 16, in the situation where STA2 is connected to AP2 via link2, there is a possibility that a large amount of Data traffic concentrates on AP2. In other words, in the situation where STA2 is connected to AP2 via link2, a large amount of Data traffic is generated on AP2.

[0179] The AP MLD (or AP2) can request the non-AP MLD (or STA2) to reconnect to AP3 which has relatively fewer STA connections. The message for requesting normal reconnection is sent to the STA that wishes to reconnect (i.e., STA2), but depending on the situation (e.g., channel situation or link state), it can be sent to any STA (i.e., other STA). In other words, based on the channel situation or link state, the STA to which the request message for requesting reconnection (e.g., Link switching request frame) is sent can be changed.

[0180] For example, when the STA (i.e., STA2) that has received a request message for the reconnection approves this request, it can send a response message of "Accept" (e.g., Link switching Response frame). In another example, when the STA (i.e., STA2) rejects this request, it can send a response message of "Decline".

[0181] The STA (i.e., STA2) that approves the normal reconnection sends a response message to the existing Link (the Link connected before the reconnection), and the response message is sent via any Link (i.e., another STA) using the multi-link characteristic.

[0182] If STA2 approves the link reconnection request, after sending the response message, STA2 can disconnect the connection with the existing AP2 and request a link reconnection to AP3. At this time, the reconnection request process can be executed in the same way as the link setup process between the existing MLDs. After the link setup process between AP3 and STA2 is completed, STA2 can perform frame exchange with AP3 via Link2.

[0183] Conversely, when STA2 rejects the link reconnection request, STA2 and AP2 can continue to use the existing connected Link (i.e., link2) as it is.

[0184] According to an embodiment, when the AP requests a link change to the STA and recommends a suitable Link, the STA can change the link to the recommended Link or may not change it. For example, the recommend link described above is used for the AP to recommend a suitable link to the STA.

[0185] For example, the STA can approve a Link change in a response message to a request message for requesting reconnection to the AP. The STA can approve / confirm a link change to the recommended Link, and can also request another Link change to the AP based on information other than the information included in the request message.

[0186] Therefore, the AP needs to notify the STA of the approval status for the response message. For this purpose, the AP can send a Confirmation message (e.g., link switching confirmation frame) to the STA for the STA's response message (e.g., Link switching Response frame).

[0187] The specific operations of the AP MLD and non-AP MLD in the above-described embodiments will be described with reference to FIG. 17.

[0188] FIG. 17 shows the operations of the AP MLD and non-AP MLD for link change or reconnection.

[0189] Referring to FIG. 17, AP2 can request a link change to STA2 including the recommended link information. In other words, AP2 can send a Link switching request frame including the recommended link information to STA2.

[0190] STA2 can send the link request approval status via a Link switching Response frame.

[0191] For example, when approving Link switching, STA2 can send the Link information to be changed included in the Link switching Response frame. At this time, the Link information to be changed may or may not be the same as the recommended Link.

[0192] In another example, when STA2 selects a link other than the recommended link provided by AP2 and responds with a Link switching Response frame, the AP can send a message to the STA regarding the final approval or rejection. The said message can be called a Link switching confirmation frame.

[0193] As an example, AP2 can approve, via a Link switching confirmation frame, the link change to the link determined by STA2. Based on the Link switching confirmation frame, STA2 can attempt to change the link to the link it specified.

[0194] As another example, AP2 can reject, via a Link switching confirmation frame, the link change to the link determined by STA2. STA2 and AP2 can maintain the connection with the existing connected link without changing the link.

[0195] The embodiment shown in FIG. 17 is also applicable when the AP sends a Link switching request frame without including the recommended link information. For example, when an AP (e.g., AP2) sends a Link switching request frame to a STA (e.g., STA2) without the recommended link information, the STA can, based on the information it has, directly specify the link to be changed and then respond to the AP via a Link switching Response frame. In this case as well, the AP ultimately needs to send a Link switching confirmation frame for approval. Therefore, the embodiment where the AP sends a Link switching confirmation frame is applicable even when the Link switching request frame does not include the recommended link information.

[0196] Embodiments where the non - AP MLD Requests Link Change or Reconnection

[0197] According to one embodiment, the non-AP MLD can request the AP MLD to change the link or reconnect for efficient data transmission. For example, the non-AP MLD can request the AP MLD to change the connection link or reconnect for using the STR capability during data transmission.

[0198] FIG. 18 shows the operations of the AP MLD and the non-AP MLD for link change or reconnection.

[0199] Referring to FIG. 18, the AP MLD and the non-AP MLD can perform Link switching negotiation. The STA2 of the non-AP MLD can send a Link switching request frame to the AP2 of the AP MLD. In response to the Link switching request frame, the AP2 of the AP MLD can send a Link switching Response frame to the STA2 of the non-AP MLD. The Link switching request frame or the Link switching Response frame is transmitted and received via the link to be changed, but is not limited thereto. The Link switching request frame or the Link switching Response frame is transmitted and received via not only the link to be changed but also various links.

[0200] The non-AP MLD can request link change or reconnection through various methods. Three methods for the non-AP MLD to request link change or reconnection are proposed below. Specifically, the three methods will be described in order: the Solicited method, the Unsolicited method, and the General method.

[0201] 1) Solicited method: A method in which a non-AP MLD requests various information for Link (re)selection from an AP MLD and receives various information through this. For example, the various information can include information regarding capability, operation element, and BSS Parameters.

[0202] According to one embodiment, the method by which a STA requests information on other APs of a connected AP MLD is used not only when reconfiguring a link but also in various cases. For example, after multi-Link setup, the STA can request BSS parameter information of other APs for Link switching and select the best link based on the received information. Or in the discovery process, the STA can request BSS load information of each AP from the AP MLD and select a link for executing Link setup based on the received information. (However, it is assumed that the number of APs in the AP MLD is larger than the number of STAs in the non-AP MLD.)

[0203] Therefore, the AP that has received the information request message can transmit any information such as Capability information, BSS parameter information, critical parameters, and / or Operation element information for all APs within the AP MLD. The examples described above are all applicable to the embodiments described below.

[0204] 2) Unsolicited method: A method in which the AP transmits various information for Link (re)selection without a separate information request from the non-AP MLD. The STA can utilize the received information in various situations. According to one embodiment, the method in which the AP of the AP MLD transmits information of other APs without a separate information request from the STA is used not only when reconfiguring the link but also in various cases. Therefore, the AP that has received the information request message can transmit any information such as Capability information, BSS parameter information, critical parameters, and / or Operation element information for all APs within the AP MLD. The examples described above are all applicable to the embodiments described below.

[0205] 3) General method: A method in which the non-AP MLD requests Link (re)selection without additional information based on information previously acquired via a Beacon frame or the like

[0206] 1) Solicited method

[0207] First, embodiments related to the above-mentioned solicited method will be described below.

[0208] According to one embodiment, the non-AP MLD can request information for selecting a link suitable for the AP MLD before changing or reconnecting the link. The STA can utilize per-AP Data load information or Capability information (or information of other links) for each link in order to select a suitable link.

[0209] For example, the per-link Capability information is included in a Beacon frame or the like and transmitted periodically.

[0210] In another example, the Link-specific Capability information may not be included in the Beacon frame that is transmitted periodically as optional information for each Link. Or, in order to reduce the frame overhead, only the information of the link to which the STA is connected or some related links is received. Or, when the Beacon reception period is long due to the characteristics of the non-AP MLD (for example, a low-power device), the non-AP MLD may not be able to receive the Link-specific Capability information for more suitable Link selection.

[0211] In the above-described case, the non-AP MLD can request the latest information of the Link-specific capability information and each Link-specific information of the AP MLD (for example, BSS parameter information or Operation element information, etc.). The links of the Link-specific capability information and each Link-specific information can include not only the links for transmission and reception but also other links. For example, fields of the QoS data frame (A-Control field in the 11ax standard), management frames, Probe response / request frames, PS-Poll frames, or Null frames are used to request / transmit the latest information. Or, a separate new frame is defined to request / transmit the latest information.

[0212] According to one embodiment, in order to request the latest information of the Link-specific capability information and each Link-specific information of the AP MLD, the STA can send a request message to the AP to request the information necessary for Link reselection. For example, the conventionally defined Probe Request frame is reused for the request message. In another example, a new frame for the request message is defined.

[0213] According to one embodiment, via the request message, the STA can also request the AP to specify necessary specific information. The specific information that can be specified can be changed according to the situation. That is, the STA can request only the information corresponding to a specific Link or only the information corresponding to a specific Capability. For example, the information corresponding to a specific link can include information regarding the BSS load / parameters of the specific link. Also, the information corresponding to the Capability can include the BSS load information of all links (all link) or the BSS load information of a specific link. In this case, the AP can transmit only the information specified by the STA via the response message. Specific embodiments regarding specific information requests and responses are described via the embodiments regarding IOM definition and operation.

[0214] As another example, the STA can also request all the Capability information currently held by the AP MLD (including information of other links, for example) via the request message.

[0215] Embodiments for transmitting all the information held by the AP as in the above-described examples or embodiments for transmitting only the specific information specified by the STA are defined / set in various ways. For example, the AP can transmit all the information or the specified information based on a separate field or bitmap, etc., in order to indicate (or transmit) only the specific information.

[0216] Normally, a message requesting information from the AP MLD is transmitted via a STA desiring reconnection, but depending on the situation (channel situation or link state), it can be transmitted to any STA (i.e., other STA).

[0217] The AP MLD that has received the request message can send a response message (i.e., an information message) including the information requested by the STA (e.g., per-link data load information, inter-link STR capability information, etc.) to the non-AP MLD. For example, when a conventional Probe Request frame is reused for the request message, the AP (or AP MLD) needs to respond with a Probe Response frame in the response message.

[0218] The response message is also sent via the AP that has normally received the Request message, but is sent to any AP (i.e., other AP) using the multi-link characteristic.

[0219] Optionally, the AP MLD can also send a "recommend link" element that recommends a link suitable for the STA together with a response message including the above-mentioned multiple information (e.g., the latest information necessary for link reselection).

[0220] The solicited method described above is used for link change or reconnection in the non-AP MLD STA. For example, when the non-AP MLD STA wishes to reselect a link due to link congestion, the non-AP MLD STA can request the per-link BSS load information and BSS parameter information of each link of the connected AP MLD via the Solicited method. The AP that has received this request message can send a response message including the link and information indicated by the STA.

[0221] In the following, the above-mentioned request message and response message are described as an information request message and an information response message in order to distinguish them from the request message for link change and the response message for link change.

[0222] Based on the information contained in the above-mentioned information response message, the STA can reselect a suitable Link and request the AP MLD to change or reconnect the Link via a request message for link change. The request message for link change can include the AP information and Link information to which it will reconnect.

[0223] When the AP MLD that receives the request message approves the request, it can send a response message of "Accept". When the AP MLD rejects the request, it can send a response message of "Decline".

[0224] If the request is approved, the AP can execute Link (re) setup based on frame exchange via the Link of the reselected AP after sending the response message. Conversely, if the request is rejected, the STA can continue to use the existing connected Link.

[0225] Examples of the specific operations of the AP MLD and non-AP MLD related to the Solicited method are described via FIG. 19.

[0226] FIG. 19 shows the operations of the AP MLD and non-AP MLD for link change or reconnection.

[0227] Referring to FIG. 19, when STA2 of the non-AP MLD wants to reselect a connected Link, STA2 can send an Info request message to the AP MLD via Link2. The receiving AP MLD can send an Info response message including the information necessary for the non-AP MLD's Link reselection. Based on the information included in the above-described Info response message, STA2 of the non-AP MLD can send a request message for link change (i.e., Link switching request frame) to AP2 of the AP MLD. Thereafter, STA2 can receive a response message for link change (i.e., Link switching request frame) and execute a link (re)set-up for link change.

[0228] The embodiments regarding the information request proposed in this specification are also used / applied when the STA requests necessary information from the AP. When the information included in the frame (e.g., beacon) received by the STA from the AP is insufficient, the STA can request the AP for the insufficient information. For example, when the AP sends only the information of the connected link without including the information of other links or only sends the information regarding the presence or absence of the update of the information of other links, the STA can request the AP for the insufficient information.

[0229] Specific examples of the above embodiments are described with reference to FIG. 20.

[0230] FIG. 20 shows the operation of the non-AP MLD for requesting information regarding other APs.

[0231] Referring to FIG. 20, the AP MLD (or AP1 to AP3) can transmit only information regarding whether there is an update of information of other APs (i.e., links) to the STA via a beacon frame. Therefore, STA2 can transmit an Info request message (or Info request frame) to AP2. Based on the Info request message, STA2 can receive an Info response message (or Info message). Based on the Info response message, STA2 can receive / acquire information regarding other APs.

[0232] For example, whether the other AP information (such as BSS load information, etc.) of the AP MLD is included in the Beacon, or AP2 can transmit only information regarding whether there is an update of the other AP information (such as version / update version).

[0233] STA2 may need the information of AP1 (or information regarding AP1). STA2 can request the necessary information via AP2. STA2 can acquire the information of AP1 via a response message to the request. STA2 can use the information of AP1 to reselect an appropriate link for Link switching. For example, frames for Link switching are set in various ways.

[0234] Furthermore, the above-mentioned solicited method is also used for the STA to obtain the information of the APs held by the AP MLD even before the multi-Link setup. In the multi-Link setup process of the non-AP MLD and the AP MLD, when the number of APs held by the AP MLD is greater than the number of STAs held by the non-AP MLD, the STA of the non-AP MLD needs to determine which AP of the AP MLD to set up a link with. In this case, the STA of the non-AP MLD can request link-specific information (e.g., the BSS load information of the APs held by the AP MLD, etc.) to recognize the state of each link for the APs of the AP MLD before the multi-Link setup. As an example, the STA can use a Probe Request in the request message. As another example, a new frame for the request message is defined. The STA can include an indicator (e.g., a Request element or an Extended Request element or a PV 1 Probe Response Option element, etc.) for requesting a specific element in the request message and an indicator (e.g., a Link ID, etc.) for indicating specific link information when transmitting the request message.

[0235] For example, the STA of the non-AP MLD can send a request message including an instruction to request the current BSS load information for each AP within the connected AP MLD. The AP that receives the request message can include the required information (the BSS load information of all the APs of the AP MLD to which the AP is connected) in the response message and send it to the STA based on the instruction of the STA. At this time, the STA that has confirmed the BSS load information for each AP can select the link to connect in the order of the BSS (i.e., the AP) with the least BSS load. The STA can indicate the link selected during the multi-Link setup. In other words, information regarding the link selected during the multi-Link setup can be sent to the AP.

[0236] Thus, the STA can also use the solicited method described above to obtain the per-AP information of the AP MLD in order to select the link to connect before the multi-Link setup.

[0237] In the following, a new element / field containing information for the STA of the non-AP MLD to select a suitable link is proposed.

[0238] For example, "ratio per Link" (element / field) is proposed. "STA ratio per Link" can include information regarding the ratio of the number of STAs linked per Link. A specific example of "STA ratio per Link" is described via FIG. 21.

[0239] FIG. 21 shows a specific example of the STA ratio per Link.

[0240] Referring to FIG. 21, the STA ratio per Link (element / field) can include information regarding the number or ratio of STAs connected per Link in the overall AP MLD.

[0241] For example, when a total of 50 STAs are connected to an AP MLD with 3 Links, 10 STAs are connected to Link 1 and 20 STAs are connected to Link 2. The AP MLD can transmit information regarding the STAs linked per Link to the non-AP MLD in terms of values or ratios (%) via the STA ratio per Link (element / field).

[0242] As an example, when the information regarding the STAs linked per Link appears as values, Link 1 is represented / set as 10 and Link 2 is represented / set as 20. Therefore, the value of the STA ratio per Link 1 is set as 10. Also, the value of the STA ratio per Link 2 is set as 20.

[0243] As another example, when the information for the STAs linked to each Link is represented as a ratio, Link 1 is expressed / set as 20 (10 / 50)%, and Link 2 is expressed / set as 40 (20 / 50)%. Therefore, the value of STA ratio per Link 1 is set to 20. Also, the value of STA ratio per Link 2 is set to 40.

[0244] The above examples are illustrative, and the information for the STAs linked to each Link is set in various ways. In addition to the above examples, the information for the STAs linked to each Link is set as a relative value.

[0245] Based on the above information for the STAs linked to each Link, the STA can confirm / acquire the number and ratio of the STAs connected to each Link, and this can be used as information for Link selection.

[0246] According to one embodiment, in addition to the above-mentioned "ratio per Link" (element / field), various information / elements / fields are included in the information response message. For example, the following information / elements / fields are included in the information response message.

[0247] - BSS load information per AP

[0248] - STR capability information between Links

[0249] - TXOP information per Link

[0250] - NAV information per Link

[0251] - Recommended Link information (i.e., "recommend link" element)

[0252] - Connected STA ratio information per Link (i.e., "STA ratio per Link" element)

[0253] - Others and the like

[0254] In addition to the above-mentioned information / element / field, various information necessary for link selection is included in the information response message and transmitted.

[0255] After receiving the information like the above-mentioned example, the STA can select the AP to be changed or reconnected based on the received information, and then send a request message for requesting reconnection of the Link. If the AP MLD that has received the request message approves the request, it can send a response message of "Accept". If the AP MLD rejects the request, it can send a response message of "Decline".

[0256] If the request is approved, the AP can perform frame exchange via the Link with the reselected AP after sending the response message. Conversely, if the request is rejected, the STA can continue to use the existing connected Link as it is.

[0257] 2) Unsolicited method

[0258] Different from the Solicited method in which the non-AP MLD directly requests additional information, according to the Unsolicited method, the AP MLD can send additional information to the non-AP MLD via a Beacon frame or a separate frame (for example, the field of the QoS data frame (A-Control field of the 11ax standard), management frame, FILS discovery frame, unsolicited Probe Response frame, PS-Poll frame or Null frame, etc.) without the non-AP MLD requesting additional information. In another example, a new frame is defined as the frame for sending additional information to the non-AP MLD.

[0259] For example, when the Beacon period is somewhat long, the non-AP MLD may lack essential information necessary for Link switching or the information may not be the latest. Therefore, the AP can send a frame containing the Link capability information of the AP MLD to the non-AP MLD. Subsequently, the non-AP STA can obtain the latest information regarding the capabilities of each Link of the AP MLD. The frame is transmitted periodically or aperiodically.

[0260] As an example, when the frame is transmitted periodically, the AP can send the frame at regular time intervals to share the latest information of the AP. At this time, the time interval needs to be shorter than the Beacon period transmitted by the AP. Also, when the FILS discovery frame is used in the frame, the frame is transmitted every 20 us. As another example, a period agreed upon by the AP and the STA through capability negotiation may also be used. For example, the transmission period is indicated via the "periodic" field and the "interval" field / subfield values of the IOM capability element.

[0261] As another example, when the frame is transmitted aperiodically, the AP can send the frame whenever an update event occurs for the AP's information (capability, BSS parameter, operation element). As a specific example, whenever the Link capability of the AP of the AP MLD changes, the changed information is sent to the connected STA. In this case, the STA can maintain the latest information regarding the Link capability.

[0262] According to the above example, since the non-AP STA does not send a request message for separately obtaining Link capability, there is an effect that relatively less frame exchange overhead occurs compared to the solicited method. Also, since the STA can receive the updated information each time the main information is updated, there is an effect that the information received by the STA can be effectively used.

[0263] An example of the operations of the specific AP MLD and non-AP MLD according to the Unsolicited method will be described with reference to FIG. 22.

[0264] FIG. 22 shows the operations of the AP MLD and non-AP MLD for link change or reconnection.

[0265] Referring to FIG. 22, the AP MLD can send the essential information required for Link reselection to the non-AP in a separate frame (e.g., a PS-Poll frame or a Null frame, etc.) without a separate request message from the non-AP MLD.

[0266] According to one embodiment, different from FIG. 22, the AP MLD can also send the information regarding Link capability to the STA via the field of the DL frame (e.g., QoS data frame) that it sends to the non-AP MLD without a separate request message from the non-AP MLD. The operations of the AP MLD and non-AP MLD according to the said embodiment will be described with reference to FIG. 23.

[0267] FIG. 23 shows the operations of the AP MLD and non-AP MLD for link change or reconnection.

[0268] Referring to FIG. 23, AP2 can send information about other APs (or information regarding other APs) to STA2 based on the DL frame (i.e., DL1). In other words, the DL frame can contain information about other APs. For example, the information about other APs is included in the A-Control field of the 802.11ax standard. According to the above embodiment, there is an effect of reducing the frame overhead by utilizing the existing DL frame without a separate message. If the Critical information of other APs is changed and real-time information is required, the updated information is sent via a separate message as in the embodiment of FIG. 23.

[0269] For example, the Critical information of an AP can include A to Q below.

[0270] A. Inclusion of a Channel Switch Announcement element

[0271] B. Inclusion of an Extended Channel Switch Announcement element

[0272] C. Modification of the EDCA parameters element

[0273] D. Inclusion of a Quiet element

[0274] E. Modification of the DSSS Parameter Set

[0275] F. Modification of the CF Parameter Set element

[0276] G. Modification of the HT Operation element

[0277] H. Inclusion of a WideBand width Channel Switch element

[0278] I. Inclusion of a Channel Switch Wrapper element

[0279] J. Inclusion of an Operating Mode Notification element

[0280] K. Inclusion of a Quiet Channel element

[0281] L. Modification of the VHT Operation element

[0282] M. Modification of the HE Operation element

[0283] N. Insertion of a Broadcast TWT element

[0284] O. Inclusion of the BSS Color Change Announcement element

[0285] P. Modification of the MU EDCA Parameter Set element

[0286] Q. Modification of the Spatial Reuse Parameter Set element

[0287] Therefore, the non-AP MLD can obtain the latest Link capability information regardless of the Beacon frame period. Based on the received information, the non-AP MLD can select a suitable Link during Link switching. Based on the received information, the STA can reselect a suitable Link and request a Link change or reconnection to the AP MLD. The request message can include the AP information and Link information to which it will reconnect. Also, when the AP MLD that receives this message approves the request, it can send a response message of "Accept", and when it rejects, it can send a response message of "Decline".

[0288] If the request is approved, the AP can perform Link (re)setup via frame exchange on the Link of the reselected AP after sending the response message. Conversely, if it rejects, the STA can continue to use the existing connected Link as it is.

[0289] 3) General method

[0290] According to the General method, the non-AP MLD can request a Link change or reconnection without additional information request based on the information it currently has. The information used at this time can include the information of the AP MLD and the information of the non-AP MLD (for example, Link-by-STR capability information, Link state (enable / disable) information, etc.) included in the previously received Beacon or Management frame, etc.

[0291] Unlike the Solicited method, the STA can directly send a request message for link change or reconnection to the AP MLD without separately requesting information from the AP MLD. The request message can include the AP information and link information to which it will reconnect. If the AP MLD that receives the request message approves the request, it can send an "Accept" response message; if it rejects the request, it can send a "Decline" response message.

[0292] If the request is approved, the AP can perform frame exchange via the link with the reselected AP after sending the response message. Conversely, if the request is rejected, the STA can continue to use the existing connected link as it is.

[0293] Examples of the specific operations of the AP MLD and non-AP MLD related to the General method are described via FIG. 24.

[0294] FIG. 24 shows the operations of the AP MLD and non-AP MLD for link change or reconnection.

[0295] Referring to FIG. 24, STA2 can desire to directly change the link for reasons of QoS guarantee. If STA2 has existing information received from the AP MLD (e.g., information received via Beacon frame or Management frame, etc.) or has already determined the link to which it desires to reconnect, STA2 can request link change or reconnection without separately requesting information.

[0296] STA2 can send a Link switching request frame including STA information (e.g., STA ID, etc.) and Link information to be changed (e.g., Link ID or AP BSS information, etc.). If the AP MLD that receives this approves the change, it can send an "Approved" Link switching Response frame to STA3 via the existing Link2. Thereafter, the non-AP MLD STA2 reconnects to AP3 after executing the Link (re)setup process.

[0297] Signaling for Indicating Link Change and Reconnection Methods

[0298] In order to instruct the method proposed above, an agreement process between each other may be required through negotiation between the AP MLD and the non-AP MLD. Therefore, in the following specification, a signaling method for enabling the proposed method is proposed.

[0299] First, a new element is proposed to instruct the method proposed above. In the following, embodiments regarding signaling for indicating Link change and reconnection methods will be described, and the embodiments are also applicable to embodiments regarding signaling for indicating Anchored link change and reconnection methods.

[0300] The signaling process for indicating Link change and reconnection methods can be executed after multi-Link setup or during multi-Link setup. Also, the new elements proposed below are used in the signaling process for indicating Link change and reconnection methods. For example, the elements are included in a conventional standard (re)association frame or a new frame.

[0301] IOM(Information Obtain Method)Capability Element

[0302] The IOM capability element can include information regarding the enablement of an additional information acquisition method for multi-link. For example, in a process where an AP MLD and a non-AP MLD exchange messages for operation agreement in a multi-Link setup process (e.g., a capability negotiation process), an IOM capability value can exist in the element of the message. The existence of an IOM capability value in the element of the message means that the IOM capability is supported.

[0303] According to one embodiment, when an AP MLD supports the IOM capability, the AP can internally share the information of other APs and can have the information of other APs. An MLD that does not share the information of other APs cannot support the IOM capability.

[0304] According to one embodiment, when the value of the IOM capability element is set as a first value (e.g., 1), the IOM capability element means that the IOM is activated and operates with the instructed function. Conversely, when the value of the IOM capability element is set as a second value (e.g., 0), the IOM capability element means that the IOM is deactivated.

[0305] According to one embodiment, the IOM capability element can include various fields / elements to instruct various operations. For example, the IOM capability element can also include various fields / elements described below. However, the fields / elements added to the IOM capability element are set differently depending on whether the AP MLD requests a link change and whether the non-AP MLD requests a link change. Also, at least some of the fields / elements added to the IOM capability element are omitted. As an example, among the fields / elements added to the IOM capability element, the fields / elements containing information that does not need to be instructed can be omitted.

[0306] Examples of various fields / elements defined / set to obtain additional information regarding multilink are described below. The various fields / elements described below are configured independently or two or more fields / elements are combined and transmitted via various frames. For example, the various fields / elements described below can be included in another element and perform the defined operations. In another example, the various fields / elements described below are added to another element in each respective element or independent field and used.

[0307] Method Type(or Method)field / element

[0308] The Method type field / element (the Method field / element as follows) can contain information regarding the operation method of the IOM. In other words, the Method field / element can indicate the operation method of the IOM. For example, when a non-AP MLD activates an IOM method to obtain information from an AP, the non-AP MLD can select and indicate the method to be used among the methods proposed above (e.g., the Solicited method, the Unsolicited method, the General method).

[0309] As an example, based on the value of the Method field / element being the first value (e.g., 0), the Solicited method is indicated / used. Based on the value of the Method field / element being the second value (e.g., 1), the Unsolicited method is indicated / used. Based on the value of the Method field / element being the third value (e.g., 2), the General method is indicated / used. Based on the value of the Method field / element being the fourth value (e.g., 3), both the Solicited method and the Unsolicited method are indicated / used.

[0310] As another example, 1 bit is used for the Method field / element. In this case, based on the value of the Method field / element being the first value (e.g., 0), the Solicited method is indicated / used. Based on the value of the Method field / element being the second value (e.g., 1), the Unsolicited method is indicated / used.

[0311] As another example, 2 bits are used for the Method field / element. In this case, separate use or overlapping use for each method, etc., is indicated.

[0312] Information Range(Info range)field / element

[0313] The information range field is used to indicate the range of information when a non-AP MLD requests information (or when the IOM provides information to the non-AP MLD).

[0314] For example, when the value of the information range field is the first value (e.g., 0), the information range field can indicate that only some of the information held by the AP is provided. When the value of the information range field is the second value (e.g., 1), the information range field can indicate that all the information (or total information) held by the AP is provided.

[0315] According to one embodiment, an information range field is defined to represent a request for all or part of the information held by the AP, but the STA can also request more detailed information via an additional subfield. For example, a subfield for indicating the information range to be provided (e.g., all information or partial information) is included in the information range field. For example, the subfield for indicating the information range to be provided is defined / set in the all / partial subfield.

[0316] According to one embodiment, a new subfield is proposed to indicate whether all the information is provided or only the changed information among all the information is provided. In other words, the newly proposed subfield can indicate whether all the information is provided or only the changed information among all the information is provided.

[0317] For example, the subfield for indicating whether all the information is provided or only the changed information among all the information is provided is defined / set in the only updated subfield.

[0318] When the STA wishes to receive only the changed information, the only updated subfield value is set to 1. In other words, when the STA wishes to receive only the changed information, the STA can set the only updated subfield value to 1. For example, when the only updated subfield value is set to 1, according to the solicited method, when the STA requests information, the AP (or AP MLD) can transmit only the changed information (i.e., the updated information) among the requested information. In another example, when the only updated subfield value is set to 1, according to the unsolicited method, the AP can notify only the changed information within the information range set by the STA.

[0319] According to the above example, an only updated subfield within the Info range field was proposed to receive only the changed information, but it is not limited to this. A separate field or element is defined / set to receive only the changed information.

[0320] According to the above-described embodiment, the range of information that the STA can request is set to the updated information or all the information. In this case, a STA that does not desire a large frame overhead can request to receive only the changed information. Therefore, there is an effect of reducing the overhead.

[0321] Link Condition field / element

[0322] The Link condition field is used to indicate a specific link to be requested. In other words, the Link condition field can contain information regarding a specific link to be requested. The Link condition field is used when the STA wishes to receive only specific link information from the AP.

[0323] The Link condition field can be represented by a link identifier (e.g., Link ID, BSS ID). In other words, the Link condition field can contain information regarding the link identifier (e.g., Link ID, BSS ID). In other words, the link identifier is used to identify the link for obtaining information. When necessary, the "The number of links" field indicating the total number of link identifiers requested by the STA may also be used together.

[0324] For example, when a STA connected to Link 1 only wishes to request information about Link 2 and Link 3 from the AP, the STA can display Link 2 and Link 3 in the Link condition field and request information about Link 2 and Link 3 from the AP. For example, when the value of the Info range field described above is 1, all information corresponding to Link 2 and Link 3 is transmitted. In another example, when the value of the Info range field described above is 0, some of the information specified by the STA for Link 2 and Link 3 is transmitted. According to one embodiment, some of the information specified by the STA is determined via the following Info condition field.

[0325] According to one embodiment, when the value of the Link condition field is absent or 0, the AP can determine that there is no link condition. Therefore, the AP can provide / transmit information about all links to the STA.

[0326] At this time, when the STA wishes to request link information for all APs of the associated AP MLD, the following additional options are proposed. The first is to include the Link identifier for all APs in the "Link condition" field in the request. The second is to have a "all / partial" field in the subfield of the "Link condition" field. At this time, the "all / partial" field is an indicator that shows whether the Link condition currently requested by the STA is information for all APs or information for some APs. For example, when the "all / partial" field is 1, it means a request for information for all APs of the associated AP MLD, and when the "all / partial" field is 0, it means a request for information for some APs of the associated AP MLD. If a request for information for some APs is made, information regarding the Link identifier for which AP's information is requested needs to be provided. The third is to omit the "Link condition" field. If the "Link condition" field is sent while omitted, this is an example where the AP MLD receives it as a request for information for all APs. In 802.11be, information for some APs can be requested with multiple options as described above.

[0327] However, when the STA requests link information for all APs of the associated AP MLD as in the above case, the AP MLD responds with only the information of the currently set up APs. For example, when the AP MLD has a total of 5 APs (AP1 to AP5) and is set up with only 3 links (AP1 to AP3) with a non-AP MLD, when the non-AP MLD's STA receives a message requesting information for all APs, it responds with only the information for the set up links (AP1 to AP3).

[0328] Info Condition field / element

[0329] The Information Condition field is used to indicate the specific type of information required. In other words, the Information Condition field is used when the STA wishes to receive only specific information from the AP.

[0330] For example, the Information Condition field is used only when the Info Range field is set to 0. In another example, the Information Condition field is also used by the STA to indicate specific information when there is no Info Range field.

[0331] For example, within the Information Condition field, the information that the STA can specify (e.g., BSS load, STR capability, etc.) can be represented by a bitmap. As an example, the types of information provided by the AP and the indication methods or procedures within the bit are set in various ways.

[0332] According to one embodiment, the Information Condition field is used together with the Link Condition field described above. According to one embodiment, the Information Condition field can send request information for various conditions to the STA (or AP) based on various combinations of fields / elements.

[0333] In this regard, the STA can also reuse existing standard elements to request specific information. For example, the Request IE or Extended Request IE can be used. The element information for this is as shown in FIGS. 25 and 26.

[0334] FIG. 25 shows an example of the Request IE format.

[0335] FIG. 26 shows an example of the Extended Request IE format.

[0336] The elements in FIGS. 25 and 26 are used to request specific information in a Probe Request frame or an Information Request frame. If the STA indicates a list of information it wishes to respond to in the requested element IDs, the AP will include the corresponding information in a Probe Response frame or an Information Response frame and transmit it. Therefore, in this specification, this element can also be reused as an indicator for requesting specific information, and can also be used to request the necessary information of the desired link together with a link identifier (e.g., Link identifier). For example, when indicating the element ID for BSS load information in the Request element mentioned in FIGS. 28 and 29 and wishing to obtain information about AP2, if it is indicated in the Link identifier, only the BSS load information of AP2 can be requested. Such element ID information is used together with the Link identifier information in various combinations to indicate specific information of a specific AP. If a new frame for information request that is not an existing frame in the present invention is defined, the Request element and the Extended Request element in FIGS. 25 and 26 are also reused.

[0337] Also, in existing standards, in order to provide a PV 1 Probe Response Option element to request specific information, such an element can also be reused in a way that indicates the specific information. For the information frequently used in the way that the STA uses optional information in the Probe Request to request the necessary information, each piece of information is indicated by a Probe response option bitmap as follows. However, in the case of 11be, since it is necessary to provide multi-link information considering MLD, the STA can request specific information for specific links in various combinations using a Link identifier together with the following bitmap indicators. However, in this case, since there may be optional information (e.g., STR capability) newly defined together with multi-link in 802.11be, if this PV 1 Probe Response Option element is reused, a bitmap for the information newly defined or further acquired in 802.11be needs to be newly defined or additionally defined.

[0338] Figure 27 shows an example of the PV 1 Probe Response Option element format.

[0339] Transmission Periodicity(periodic)field / element

[0340] When the STA wishes to provide information in an Unsolicited manner, it can indicate whether to receive the message containing the information periodically or aperiodically via a transmission periodicity field.

[0341] For example, when the STA wishes to receive the information aperiodically, the AP can notify the updated information each time an update occurs for the information of other APs.

[0342] In another example, when the STA is instructed to receive the information periodically, the STA can also receive a message including the information at the periodic interval set by the STA.

[0343] According to one embodiment, the transmission periodic field is set to 1 bit. When the value of the transmission periodic field is set to 1, the STA can receive / acquire information via a periodic method of receiving messages periodically. When the value of the transmission periodic field is set to 0, the STA can receive / acquire information via a method of receiving messages aperiodically.

[0344] Transmission Interval field / element

[0345] According to one embodiment, when the STA desires to be periodically received information of other APs, the STA can also directly set the period. The STA can transmit information regarding the period for receiving other AP information based on the transmission period (interval) field. However, the period needs to be set shorter than the Beacon transmission period. For example, when a FILS discovery frame is used, the period needs to be set to 20 us.

[0346] As described above, it is defined in a separate field within the element that indicates the transmission period, or is also defined as a subfield within the transmission periodic field.

[0347] According to one embodiment, the fields / elements defined / set for obtaining additional information regarding multi-link are not limited to the fields / elements described above, and various fields / elements are further set.

[0348] Therefore, MLD (AP MLD or non-AP MLD) can indicate the IOM function (capability) through negotiation between AP MLD and non-AP MLD using at least one of the elements / fields described above in the multi-Link setup process. Also, after the completion of multi-Link setup, MLD can update the agreed-upon content between MLDs through separate message exchanges.

[0349] According to one embodiment, when the IOM function (capability) is activated, AP MLD and non-AP MLD can operate based on the embodiments for link change and reconnection.

[0350] In the following, examples of the operations of AP MLD and non-AP MLD are described when the IOM function (capability) is activated. For example, the non-AP MLD can request additional information for multi-link by sending the above-described field / element to the AP MLD. The non-AP MLD can send an IOM capability element including the above-described field / element to the AP MLD. The fact that the above-described field / element is included in the IOM capability element is exemplary and is sent as an independent field / element.

[0351] For example, in the multi-Link setup process, the non-AP MLD can send an IOM capability element containing "Method field=0" and "Info range field=1" to the AP MLD and reach an agreement with the AP MLD on this. In this case, after multi-Link setup, the non-AP MLD operates in the Solicited method and can request information for the multi-link (e.g., information about other APs) including all the information contained in the beacon when information is requested. Therefore, the AP MLD can provide / send information about the Link in a response message only when it receives a request message from the STA. When receiving a request message, the AP MLD can send a response message containing information about all the links within the AP MLD to the STA. The information about all the links within the said AP MLD can include all the information contained in the beacon.

[0352] In another example, the non-AP MLD can send an IOM capability element containing "Method field=1", "Info range field=0", "Linkrange=Link ID2", "Info condition field=(value indicating BSS load via bitmap)" to the AP MLD and reach an agreement with the AP MLD on this. In this case, after multi-Link setup, the non-AP MLD can operate in the UnSolicited method. Therefore, without a separate request message, the AP can send the BSS load information of Link2 to the STA via a separate message.

[0353] In another example, the non-AP MLD can send an IOM capability element containing "Method field = 0", "Info range field = 0", "only updated field or subfield = 1", and "Info condition field = (value indicating BSS load via bitmap)" to the AP MLD and reach an agreement with the AP MLD on this. In this case, after multi-Link setup, the non-AP MLD can operate in the Solicited method. Therefore, the AP MLD (or the AP) can send to the STA only the updated (changed) information among the BSS load information of all the APs of the AP MLD to which the STA is connected when requesting information, included in the response message.

[0354] The AP MLD and the non-AP MLD can activate the IOM method proposed via the signaling method proposed in this specification during or after the multi-Link setup process, and limit the information range and types requested via various filed values in the IOM capability element.

[0355] Thus, after the accurate operation negotiation (Negotiation) between MLDs via such an IOM signaling method in the standard, IOM operations may be performed, but in this specification, cases where the IOM method operates by the MLD implementation without a separate signaling process are also considered. This means it operates by the AP MLD implementation or the non-AP MLD implementation without an agreement between the AP MLD and the non-AP MLD.

[0356] Although it can operate generally as proposed above, when the MLD performs IOM operations without a separate signaling exchange, the following constraints may occur.

[0357] 1) Constraints for the Solicited method: If info sharing between APs of the AP MLD is not supported, when the STA requests information about another link, the response cannot be made.

[0358] 2) Constraints for the Unsolicited method: The AP itself determines the STA that needs link addition information (e.g., beacon period, etc.) and provides a separate message. Therefore, the STA cannot predict in advance whether it will be provided with this information.

[0359] If the MLD implements the IOM without a separate signaling method, the operation process becomes simple, but there may be the above-mentioned constraints.

[0360] The method proposed in this specification can also be set based on the agreement between the AP MLD and the non-AP MLD using the "IOM capability" element mentioned above. However, in the case of the Solicited method, if the STA temporarily hopes to obtain specific information other than the agreed content and indicates it, when the STA dynamically sends a Request message, it can also include the indicated content (e.g., IOM capability information) in the request.

[0361] During or after the Multi-Link setup, although the AP MLD and the non-AP MLD may agree and the STA may be provided with information from the AP based on the agreed content, if the STA temporarily hopes to request specific information of a particular AP or specific parameter information of the AP, when making the information request, it can be sent including the indication for the information desired using the "IOM capability" element in the request frame (e.g., Probe Request frame or reassociation frame or new frame, etc.). Then, the AP can provide the information as an included response message based on the information value. If the field in the IOM capability element is omitted, the AP provides the information based on the previously agreed content.

[0362] Therefore, MLD provides information by agreeing with the information provided through negotiation between the AP MLD and the non-AP MLD using the above elements after the multi-Link setup process or later. Alternatively, the MLD can also receive information only for the temporarily requested information by including instructions for the information desired by the STA in the request message. However, when the STA omits special instructions in the request message, it operates based on the basically agreed instructions. If it is desired to change the agreed content after the completion of the multi-Link setup, the agreed content between the MLDs can be updated through separate message exchanges.

[0363] Method for Requesting Changed Critical Update Information

[0364] This specification proposes a method for a non-AP MLD STA to request some information of the affiliated AP of the AP MLD. However, such a method is used particularly for the method of obtaining only the Critical update information when the STA is changed.

[0365] First, a method is provided in which a STA uses a "Change sequence" element (or field) and a link indicator (e.g., Link ID or BSS ID) in a request frame (e.g., Probe Request frame) to request some information from an affiliated AP of an AP MLD. In 802.11ah, when transmitting a Probe Request frame including the "Change sequence" element, the Probe response responds with a compressed Probe response including only the updated values in the current Critical update list. By reusing such a method in 802.11be, the STA can utilize it to obtain only the changed Critical update information from the AP. For example, if a STA that is not an AP MLD transmits a Probe Request including the Chance sequence element, the AP that receives this will respond with a Probe response including only the Critical update change values. At this time, the STA can propose four operation options in 802.11be for transmitting a request frame including the Change sequence element.

[0366] 1) When the STA transmits a request frame including the Change sequence element, a method in which the AP that receives this provides the change information of its own Critical update. For example, when a non-AP MLD STA1 transmits a Probe Request including the Change sequence element to an AP (however, in this case, when transmitted without a separate link indicator), the AP1 that receives this responds by including the change value of its own Critical update in the Probe Response frame.

[0367] 2) When the STA sends a request frame including the Change sequence element (however, in this case, when it is sent without a separate link indicator), it is a method for the AP that receives this to provide information on all APs of the AP MLD that includes itself. For example, when STA1, which is not an AP MLD, sends a Probe Request to the AP including the Change sequence element, AP1 that receives this responds by including the change values of the Critical update of all APs (for example, AP1, 2, 3) of the AP MLD to which it is connected in the Probe Response frame.

[0368] 3) When the STA sends including a Link identifier (link indicator, for example, Link ID or BSS ID, etc.) together with the Change sequence element, it is a method for the AP that receives this to respond by including all the change values of the Critical update of the link corresponding to the indicated Link identifier. For example, when STA1, which is not an AP MLD, sends a Probe Request to the AP indicating AP1, 2 in the Link identifier together with the Change sequence element (assuming that the AP MLD has AP1, 2, 3), it is a method of responding by including only the Critical update change values corresponding to AP1, 2 in the Probe Response frame.

[0369] 4) When the STA sends a request frame including the "all / part" field (an indicator that instructs whether the requested information means all APs of the connected AP MLD or some APs) together with the Change sequence element, it is a method of responding with all or some information in the response according to the "all / part" field value. For example, when the STA sends a Probe Request frame with the "all / part" field value set to 1 together with the Change sequence element (meaning a request for information about all APs), the AP that receives this will respond with a Probe response including the Critical update change values for all APs of the connected AP MLD. Or when the STA sends a Probe Request frame with the "all / part" field value set to 0 together with the Change sequence element (meaning a request for information about some APs), the AP that receives this will respond with a Probe response including the Critical update change values for some APs of the connected AP MLD. In this case, the STA needs to send it together with a Link identifier (link indicator, Link ID, or BSS ID) that can indicate which AP's information is being requested.

[0370] Second, when the STA requests some information from an affiliated AP of the AP MLD, it uses a request frame (e.g., a Probe Request frame) with an "updated only" field (a newly defined field in this specification) and a link indicator (e.g., Link ID or BSS ID). When the STA sends a request frame with the "updated only" field value set to 1 to request information from the AP, the AP responds with only the information updated in its Critical update value. It is an advantage that it can be indicated in a simple 1-bit field without adding separate elements. At this time, the STA can propose four operation options in 802.11be for sending a request frame including the "updated only" field.

[0371] 1) When the STA sends a request frame with the "updated only" field value set to 1, it is a method for the receiving AP to provide the changed information of its own Critical update. When sending a request frame with the "updated only" field value set to 0, the receiving AP provides the current information of its current Critical update (i.e., all information including not only the changed information but also the unchanged information). For example, when a non-AP MLD STA sends a Probe Request with the "updated only" field indicated as 1 to the AP (however, in this case, when sending without a separate link indicator), the receiving AP responds by including only the changed value of its Critical update in the Probe Response frame.

[0372] 2) When the STA sends a request frame including the "updated only" field (however, in this case, when it is sent without a separate link indicator), it is a method for the receiving AP to provide the information of all APs in the AP MLD in which it is included. For example, when the non-AP MLD STA1 sets the "updated only" field value to 1 in the Probe Request and sends it to the AP, the received AP1 includes the changed values of the Critical update of all APs (for example, AP1, 2, 3) in the AP MLD to which it is connected in the Probe Response frame and responds.

[0373] 3) When the STA sends including the "updated only" field and a Link identifier (link indicator, for example, Link ID or BSS ID, etc.), it is a method for the receiving AP to respond by including all the changed values of the Critical update of the link corresponding to the indicated Link identifier. For example, when the non-AP MLD STA1 sends a Probe Request to the AP with the "updated only" field = 1 and the link indicators AP1 and 2 (assuming the AP MLD has AP1, 2, 3), it is a method to respond by including only the changed values of the Critical update corresponding to AP1 and 2 in the Probe Response frame.

[0374] 4) When the STA sends a request frame including the "all / part" field (an indicator that indicates whether the requested information means all APs or some APs of the connected AP MLD) together with the "updated only" field, it is a method of responding with all or some information in the response according to the "all / part" field value. For example, when the STA sends a Probe Request frame with the "updated only" field set to 1 and the "all / part" field value indicating 1 (meaning a request for information about all APs), the AP that receives this will respond with a Probe response including the Critical update change values for all APs of the connected AP MLD. Or when the STA sends a Probe Request frame with the "updated only" field set to 1 and the "all / part" field value indicating 0 (meaning a request for information about some APs), the AP that receives this will respond with a Probe response including the Critical update change values for some APs of the connected AP MLD. In this case, the STA needs to send it together with a Link identifier (link indicator, Link ID, or BSS ID) that can indicate which AP's information is requested.

[0375] A method is also proposed in which the STA requests information of other APs of the connected AP MLD (or information of all links of the connected AP MLD) using the ML (Multi-Link) element defined in the 802.11be standard.

[0376] Figure 28 shows an example of the ML element format defined in 802.11be.

[0377] In 802.11be, an ML element was defined as shown in the upper part of FIG. 28 to define per-link information. Subsequently, elements or fields are added by the proposed functions. The ML element can include an Element ID field, a Length field, an Element ID Extension field, a Multi-Link Control field, a Common Info field, and a Link Info field.

[0378] The lower part of FIG. 28 shows the Multi-Link Control field.

[0379] The Multi-Link Control field includes a Type subfield. The Type subfield is defined as follows and is used to distinguish various variants of the ML element. Various variants of the ML element are used for different multi-link operations.

[0380]

Table 1

[0381] The Multi-Link Control field further includes a Presence Bitmap subfield. The Presence Bitmap subfield is used to indicate the presence of various subfields in the Common Info field.

[0382] The Common Info field transfers information common to all links except the Link ID Info subfield and the BSS Parameters Change Count subfield for the link to which the Multi-Link element is transmitted, and is selectively present based on the value of the Type subfield.

[0383] The said Common Info field is composed of zero or more sub-fields whose existence is indicated by sub-fields of the said Multi-Link Control field. The sub-fields of the said Common Info field are shown in the same order as the said existence sub-fields of the Multi-Link Control sub-fields.

[0384] The said Link Info field transfers specific information to the link and selectively exists based on the value of the Type sub-field.

[0385] The Probe Request variant Multi-Link element is used for the AP to request another AP belonging to the same AP MLD as the AP to provide information. If a Probe Request variant Multi-Link element is included in the probe request frame, it is identified as an ML probe request.

[0386] The said Link Info field includes zero or more Per-STA Profile subelements.

[0387] Figure 29 shows the Per-STA Profile subelement of the Probe Request variant Multi-Link element.

[0388] Referring to the upper part of Figure 29, the Per-STA Profile subelement of the Probe Request variant Multi-Link element includes a Subelement ID field, a Length field, a STA Control field, and a STA Profile field.

[0389] The lower part of Figure 29 shows the STA Control field. The said STA Control field includes a Link ID sub-field, a Complete Profile sub-field, and a reserved field.

[0390] The Link ID subfield specifies a value that uniquely identifies the AP for which information is requested.

[0391] The Complete Profile subfield is set to 1 when complete information is requested from the AP. Otherwise, the Complete Profile subfield is set to 0.

[0392] The STA Profile field of the Per-STA Profile subelement contains only the (Extended) Request element when a non-AP STA requests partial information from the AP corresponding to the per-STA Profile, and does not exist when the non-AP STA requests complete information from the AP.

[0393] In the following, the above-described embodiments will be described with reference to FIGS. 1 to 29.

[0394] FIG. 30 is a flowchart showing a procedure in which a transmitting MLD according to the present embodiment provides information on an AP included in the transmitting MLD to a receiving MLD based on a probe response frame.

[0395] An example of FIG. 30 can be executed in a network environment supported by a next-generation wireless LAN system (IEEE 802.11be or EHT wireless LAN system). The next-generation wireless LAN system can satisfy backward compatibility with the 802.11ax system as a wireless LAN system that improves the 802.11ax system.

[0396] The present embodiment proposes a method and apparatus for a STA of a receiving MLD to request information on all or some of the links of a transmitting MLD in MLD communication. The transmitting MLD may be an AP MLD, and the receiving MLD may be a non-AP MLD.

[0397] In step S3010, the transmitting MLD (Multi-link Device) receives a probe request frame from the receiving MLD via the first link.

[0398] In step S3020, the transmitting MLD transmits a probe response frame to the receiving MLD via the first link.

[0399] As an example, the transmitting MLD includes a first transmitting STA (station) operating on the first link, a second transmitting STA operating on the second link, and a third transmitting STA operating on the third link. The receiving MLD includes a first receiving STA operating on the first link. The receiving MLD may further include a second receiving STA operating on the second link and a third receiving STA operating on the third link.

[0400] When the first receiving STA requests information about the second and third links, the probe request frame includes link identifiers for the second and third links. That is, when the first receiving STA only wishes to obtain information about a specific link from the first transmitting STA, the probe request frame can include the link identifier for the specific link to indicate the necessary information.

[0401] However, when the first receiving STA requests information about all links, the probe request frame does not include link identifiers for all links. Conventionally, when the first receiving STA requests information about all links, there has been a problem of large overhead because it is necessary to include identifiers for all links in the probe request frame. On the other hand, in this embodiment, when the first receiving STA requests information about all links, there is no need to include identifiers for all links (either omitting or removing identifiers for all links), so there is an effect of reducing frame overhead.

[0402] The probe request frame can include an information range field and an information condition field.

[0403] The information range field can include the information that the receiving MLD can provide. If the information range field is set to 1, the information that the receiving MLD can provide can be all the information of the transmitting MLD. If the information range field is set to 0, the information that the receiving MLD can provide can be partial information or updated information of the transmitting MLD. All the information of the transmitting MLD can be all the information for a specific link indicated by a link identifier. The partial information or updated information of the transmitting MLD can also be partial information or updated information for a specific link indicated by a link identifier.

[0404] The information condition field can include the information that the receiving MLD wants to provide. If the information range field is set to 0, the information that the receiving MLD wants to provide is defined by a bitmap. Each bit of the bitmap can indicate the information that the receiving MLD can specify. For example, assuming that the bitmap is composed of 6 bits, the first bit of the bitmap represents the BSS (Basic Service Set) load information for each AP, the second bit represents the STR (Simultaneous transmit and receive) Capability information between links, the third bit represents the TXOP (Transmission Opportunity) information for each link, the fourth bit represents the NAV (Network Allocate Vector) information for each link, the fifth bit represents the recommended link information, and the sixth bit can indicate the connection STA ratio information for each link. At this time, when each bit is set to 1, the receiving MLD can request the corresponding information, and when each bit is set to 0, the receiving MLD does not request the corresponding information.

[0405] The probe request frame may further include a change sequence element. When the probe request frame includes link identifiers for the second and third links, the change sequence element is used to request important update information of the second and third transmitting STAs. When the probe request frame does not include link identifiers for all the links, the change sequence element is used to request important update information of all the transmitting STAs within the transmitting MLD.

[0406] Also, the probe request frame may further include a newly defined updated only field instead of the change sequence element. The updated only field is also used to request important update information (changed information) of the transmitting MLD.

[0407] The probe response frame may include information that the receiving MLD can provide, information that the receiving MLD wants to provide, important update information of the second and third transmitting STAs, or important update information of all the transmitting STAs within the transmitting MLD. That is, the first transmitting STA of the transmitting MLD can notify the first receiving STA of the information requested by the first receiving STA via the probe response frame.

[0408] The probe request frame may further include link indicator information. The link indicator information may include identifier information of the first, second, or third link. The profile field of the first receiving STA, the profile field of the second receiving STA, and the profile field of the third receiving STA are included in the probe request frame based on the link indicator information. For example, if the link indicator information includes the identifier information of the first link, the profile field of the first receiving STA is included in the probe request frame. If the link indicator information includes the identifier information of the second link, the profile field of the second receiving STA is included in the probe request frame.

[0409] FIG. 31 is a flowchart showing a procedure in which a receiving MLD according to the present embodiment requests information on an AP included in a transmitting MLD based on a probe request frame from the transmitting MLD.

[0410] An example of FIG. 31 can be executed in a network environment supported by a next-generation wireless LAN system (IEEE 802.11be or EHT wireless LAN system). The next-generation wireless LAN system can satisfy backward compatibility with the 802.11ax system as a wireless LAN system that improves the 802.11ax system.

[0411] The present embodiment proposes a method and apparatus for a receiving STA of an MLD to request information on all or some of the links of a transmitting MLD in MLD communication. The transmitting MLD may be an AP MLD, and the receiving MLD may be a non-AP MLD.

[0412] In step S3110, a receiving MLD (Multi-link Device) transmits a probe request frame to a transmitting MLD via a first link.

[0413] In step S3120, the receiving MLD receives a probe response frame from the transmitting MLD via the first link.

[0414] As an example, the transmitting MLD includes a first transmitting STA (station) operating on the first link, a second transmitting STA operating on the second link, and a third transmitting STA operating on the third link. The receiving MLD includes a first receiving STA operating on the first link. The receiving MLD may further include a second receiving STA operating on the second link and a third receiving STA operating on the third link.

[0415] When the first receiving STA requests information about the second and third links, the probe request frame includes link identifiers for the second and third links. That is, when the first receiving STA wishes to obtain only information about a specific link from the first transmitting STA, the necessary information can be indicated by including the link identifier for the specific link in the probe request frame.

[0416] However, when the first receiving STA requests information about all links, the probe request frame does not include link identifiers for all links. Conventionally, when the first receiving STA requests information about all links, there has been a problem of large overhead because it is necessary to include identifiers for all links in the probe request frame. On the other hand, in this embodiment, when the first receiving STA requests information about all links, there is no need to include identifiers for all links (except by omitting or removing identifiers for all links), so there is an effect of reducing frame overhead.

[0417] The probe request frame can include an information range field and an information condition field.

[0418] The information range field can include information that the receiving MLD can provide. If the information range field is set to 1, the information that the receiving MLD can provide can be all the information of the transmitting MLD. If the information range field is set to 0, the information that the receiving MLD can provide can be some information or updated information of the transmitting MLD. All the information of the transmitting MLD can be all the information for a specific link indicated by a link identifier. Some information or updated information of the transmitting MLD can also be some information or updated information for a specific link indicated by a link identifier.

[0419] The information condition field can include the information that the receiving MLD wants to provide. If the information range field is set to 0, the information that the receiving MLD wants to provide is defined by a bitmap. Each bit of the bitmap can indicate the information that can be specified by the receiving MLD. For example, assuming that the bitmap is composed of 6 bits, the first bit of the bitmap represents the BSS (Basic Service Set) load information for each AP, the second bit represents the link - level STR (Simultaneous transmit and receive) Capability information, the third bit represents the TXOP (Transmission Opportunity) information for each link, the fourth bit represents the NAV (Network Allocate Vector) information for each link, the fifth bit represents the recommended link information, and the sixth bit can indicate the connected STA ratio information for each link. At this time, when each bit is set to 1, the receiving MLD can request the corresponding information, and when each bit is set to 0, the receiving MLD does not request the corresponding information.

[0420] The probe request frame can further include a Change sequence element. When the probe request frame includes link identifiers for the second and third links, the change sequence element is used to request important update information of the second and third transmitting STAs. When the probe request frame does not include link identifiers for all links, the change sequence element is used to request important update information of all transmitting STAs within the transmitting MLD.

[0421] Also, the probe request frame can further include a newly defined updated only field instead of the change sequence element. The updated only field is also used to request important update information (changed information) of the transmitting MLD.

[0422] The probe response frame can include information that the receiving MLD can provide, information that the receiving MLD wants to provide, important update information of the second and third transmitting STAs, or important update information of all transmitting STAs in the transmitting MLD. That is, the first transmitting STA of the transmitting MLD can notify the first receiving STA of the information requested by the first receiving STA via the probe response frame.

[0423] The probe request frame can further include link indicator information. The link indicator information can include identifier information of the first, second, or third link. The profile fields of the first receiving STA, the second receiving STA, and the third receiving STA are included in the probe request frame based on the link indicator information. For example, if the link indicator information includes the identifier information of the first link, the profile field of the first receiving STA is included in the probe request frame. If the link indicator information includes the identifier information of the second link, the profile field of the second receiving STA is included in the probe request frame.

[0424] The technical features of the present specification described above can be applied to various apparatuses and methods. For example, the technical features of the present specification described above are executed / supported via the apparatuses of FIGS. 1 and / or 11. For example, the technical features of the present specification described above are only applied to a part of FIGS. 1 and / or 11. For example, the technical features of the present specification described above are implemented based on the processing chips 114 and 124 of FIG. 1, or implemented based on the processors 111 and 121 and memories 112 and 122 of FIG. 1, or implemented based on the processor 610 and memory 620 of FIG. 11. For example, the apparatus of the present specification transmits a probe request frame to the transmitting MLD via the first link and receives a probe response frame from the transmitting MLD via the first link.

[0425] The technical features of this specification are implemented based on a CRM (computer readable medium). For example, the CRM proposed by this specification is at least one computer readable recording medium containing instructions based on being executed by at least one processor.

[0426] The CRM can store instructions for performing operations including the step of transmitting a probe request frame via a first link to a transmitting MLD; and the step of receiving a probe response frame from the transmitting MLD via the first link. The instructions stored within the CRM of this specification are executed by at least one processor. At least one processor related to the CRM of this specification can be the processor 111, 121 or processing chip 114, 124 in FIG. 1, or the processor 610 in FIG. 11. On the other hand, the CRM of this specification can be the memory 112, 122 in FIG. 1 or the memory 620 in FIG. 11, or a separate external memory / storage medium / disk, etc.

[0427] The above-described technical features of this specification are applicable to various applications and business models. For example, the above-described technical features are applied for wireless communication in a device supporting artificial intelligence (AI).

[0428] Artificial intelligence means the field of studying artificial intelligence or the methodology for creating it, and machine learning means the field of studying the methodologies for defining and solving various problems dealt with in the field of artificial intelligence. Machine learning can also be defined as an algorithm that improves the performance of a certain task through continuous experience with that task.

[0429] An artificial neural network (ANN) is a model used in machine learning that generally refers to a model with problem-solving capabilities, composed of artificial neurons (nodes) that form a network through synaptic connections. An artificial neural network is defined by the connection pattern between neurons in other layers, the learning process for updating model parameters, and the activation function that generates output values.

[0430] An artificial neural network can include an input layer, an output layer, and optionally one or more hidden layers. Each layer contains one or more neurons, and an artificial neural network can include synapses that connect neuron to neuron. In an artificial neural network, each neuron can output the function value of the activation function for the input signal, weight value, and bias input through the synapse.

[0431] Model parameters refer to parameters determined through learning, including the weight values of synaptic connections and the biases of neurons. Hyperparameters refer to parameters that need to be set before learning in a machine learning algorithm, including the learning rate, number of iterations, mini-batch size, initialization function, etc.

[0432] The purpose of learning an artificial neural network is to determine model parameters that minimize the loss function. The loss function is used as an indicator for determining optimal model parameters in the learning process of an artificial neural network.

[0433] Machine learning can be classified into supervised learning, unsupervised learning, and reinforcement learning according to the learning method.

[0434] Supervised learning means a method of training an artificial neural network with labels for training data. When training data with labels is input into the artificial neural network, the label means the correct answer (or result value) that the artificial neural network needs to infer. Unsupervised learning means a method of training an artificial neural network without labels for training data. Reinforcement learning means a learning method that trains an agent defined in an environment to select actions or action sequences that maximize cumulative rewards in each state.

[0435] Among artificial neural networks, machine learning implemented as a deep neural network (DNN) with multiple hidden layers is also called deep learning. Deep learning is a part of machine learning. Hereinafter, machine learning is used to include deep learning.

[0436] In addition, the above-described technical features are applied to wireless communication of robots.

[0437] A robot means a machine that automatically processes or operates a job given by its own capabilities. In particular, a robot with the function of recognizing the environment, making its own judgment, and executing operations is called an intelligent robot.

[0438] Robots can be classified into industrial, medical, household, military, etc. according to their usage purposes and fields. A robot is equipped with a drive unit including an actuator or a motor and can perform various physical operations such as moving robot joints. In addition, a movable robot includes wheels, brakes, propellers, etc. in its drive unit and can travel on the ground or fly in the air through the drive unit.

[0439] In addition, the above-described technical features are applied to devices that support augmented reality.

[0440] Extended reality is a general term for virtual reality (VR), augmented reality (AR), and mixed reality (MR). VR technology only provides objects and backgrounds in the real world as CG images. AR technology provides both real object images and CG images created virtually on top of them. MR technology is a computer graphics technology that mixes and combines virtual objects with the real world.

[0441] MR technology is similar to AR technology in that it shows virtual objects together. However, there is a difference in that while virtual objects are used in a complementary form to virtual objects in AR technology, virtual objects and virtual objects are used with equal status in MR technology.

[0442] XR technology is applicable to head-mounted displays (HMDs), head-up displays (HUDs), mobile phones, tablets, notebook computers, desktops, TVs, digital signage, etc. Devices to which XR technology is applied can be called XR devices.

[0443] The claims described in this specification can be combined in various ways. For example, the technical features of the method claims in this specification are combined and implemented in a device, and the technical features of the device claims in this specification are combined and implemented as a method. Also, the technical features of the method claims and the technical features of the device claims in this specification are combined and implemented in a device, and the technical features of the method claims and the technical features of the device claims in this specification are combined and implemented as a method.

Claims

1. A method in a WLAN (wireless local area network) system, the method comprising: a first non-AP (non-access point) STA (station) transmitting a probe request frame to a first AP; the first non-AP STA receiving a probe response frame from the first AP, wherein a first AP operating on a first link, a second AP operating on a second link, and a third AP operating on a third link are affiliated with an AP MLD (multi-link device); the first non-AP STA operating on the first link is affiliated with a non-AP MLD; based on the probe request frame including information about the second AP and the third AP, only APs whose link ID is equal to the value in the Link ID field in the information about the second AP and the third AP in the probe request frame are the second AP and the third AP; the probe request frame permits the first non-AP STA to request information about all APs affiliated with the AP MLD based on the probe request frame not including any information about all APs.

2. The method according to claim 1, wherein the probe request frame includes an information range field and an information condition field.

3. The information range field includes information that can be provided to the non-AP MLD; when the information range field is set to 1, the information that can be provided to the non-AP MLD is all information of the AP MLD; when the information range field is set to 0, the information that can be provided to the non-AP MLD is partial information or updated information of the AP MLD.

4. The information condition field includes information that the non-AP MLD desires to provide; when the information range field is set to 0, the information that the non-AP MLD desires to provide is defined as a bitmap; each bit of the bitmap indicates information that can be specified by the non-AP MLD.

5. The probe request frame further includes a change sequence element, Based on the probe request frame including link identifiers for the second and third links, the change sequence element is used to request important update information of the second and third APs, The method according to claim 4, wherein when the probe request frame does not include the link identifiers for all links, the change sequence element is used to request important update information of all APs within the AP MLD. **Claim 6** The method according to claim 5, wherein the probe response frame includes the information that can be provided to the non-AP MLD, the information that the non-AP MLD desires to provide, the important update information of the second and third APs, or the important update information of all APs within the AP MLD. **Claim 7** The non-AP MLD further includes a second non-AP STA operating on the second link and a third non-AP STA operating on the third link, The probe request frame further includes link indicator information, The link indicator information includes identifier information of the first, second, or third link, The method according to claim 1, wherein the profile fields of the first non-AP STA, the profile fields of the second non-AP STA, and the profile fields of the third non-AP STA are included in the probe request frame based on the link indicator information. **Claim 8** A first non-access point (non-AP) station (STA) in a WLAN (wireless local area network) system, wherein the first non-AP STA includes a memory, a transceiver, and a processor coupled to operate with the memory and the transceiver, and the processor is configured to transmit a probe request frame to a first AP, receive a probe response frame from the first AP, The first AP operating on the first link, the second AP operating on the second link, and the third AP operating on the third link are affiliated with an AP MLD (multi-link device), The first non-AP STA operating on the first link is affiliated with a non-AP MLD, Based on the probe request frame including information about the second AP and the third AP, only the APs whose link ID is equal to the value in the Link ID field in the information about the second AP and the third AP in the probe request frame are the second AP and the third AP. The probe request frame permits the first non-AP STA to request information about all APs with which the AP MLD is affiliated, based on the probe request frame not including any information about all APs. Claim 9 A method in a WLAN (wireless local area network) system, the method comprising: a first AP (access point) receiving a probe request frame from a first non-AP STA (station); an AP MLD transmitting a probe response frame to the first non-AP STA; the first AP operating on a first link, a second AP operating on a second link, and a third AP operating on a third link being affiliated with an AP MLD (multi-link device); the first non-AP STA operating on the first link being affiliated with a non-AP MLD; Based on the probe request frame including information about the second AP and the third AP, only the APs whose link ID is equal to the value in the Link ID field in the information about the second AP and the third AP in the probe request frame are the second AP and the third AP. The probe request frame permits the first non-AP STA to request information about all APs with which the AP MLD is affiliated, based on the probe request frame not including any information about all APs. Claim 10 The method according to claim 9, wherein the probe request frame includes an information range field and an information condition field. Claim 11 The information range field includes information that can be provided to the non-AP MLD. When the information range field is set to 1, the information that can be provided to the non-AP MLD is all the information of the AP MLD. The method according to claim 10, wherein when the information range field is set to 0, the information that can be provided to the non-AP MLD is part of the information of the AP MLD or updated information.

12. The information condition field includes the information that the non-AP MLD wants to provide. When the information range field is set to 0, the information that the non-AP MLD wants to provide is defined as a bitmap. The method according to claim 11, wherein each bit of the bitmap indicates information that can be specified by the non-AP MLD.

13. The probe request frame further includes a change sequence element. When the probe request frame includes link identifiers for the second and third links, the change sequence element is used to request important update information of the second and third APs. The method according to claim 12, wherein when the probe request frame does not include the link identifiers for all links, the change sequence element is used to request important update information of all APs in the AP MLD.

14. The method according to claim 13, wherein the probe response frame includes the information that can be provided to the non-AP MLD, the information that the non-AP MLD wants to provide, the important update information of the second and third APs, or the important update information of all APs in the AP MLD.

15. The non-AP MLD further includes a second non-AP STA operating on the second link and a third non-AP STA operating on the third link. The probe request frame further includes link indicator information. The link indicator information includes identifier information of the first, second, or third link. The method according to claim 9, wherein the profile fields of the first non-AP STA, the profile fields of the second non-AP STA, and the profile fields of the third non-AP STA are included in the probe request frame based on the link indicator information.

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