Method and apparatus for performing c-TDMA operation by receiving additional CTS frame in wireless LAN system

Abstract

Presented are a method and an apparatus for performing a C-TDMA operation by receiving an additional CTS frame in a wireless LAN system. Specifically, a first AP receives an MU-RTS trigger frame from a second AP. The first AP transmits a first CTS frame to the second AP, receives a second CTS frame from the second AP, and transmits a TXOP return sequence to the second AP.

Description

Method and device for performing C-TDMA operation by receiving additional CTS frame in wireless LAN system

[0001] The present invention relates to a technique for performing C-TDMA operation by receiving an additional CTS frame in a wireless LAN system, and more specifically, to a method and device for protecting an SAP by transmitting an additional CTS frame and setting an NAV to prevent a third party STA or OBSS STA from occupying the medium.

[0002] Next-generation Wi-Fi (e.g., IEEE 802.11be and / or later) aims to support ultra-high reliability when transmitting signals to STAs. To achieve this, various technologies are being considered to support high throughput, low latency, and extended range. For example, multiple APs can cooperate to perform TXOP sharing procedures.

[0003] The present specification proposes a method and device for performing C-TDMA operation by receiving an additional CTS frame in a wireless LAN system.

[0004] An example of this specification proposes a method for performing C-TDMA operation by receiving an additional CTS frame.

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

[0006] The present embodiment is performed in a first AP, and the first AP may be set as a shared AP (DAP) after negotiation in multi-AP communication, and the second AP may be set as a sharing AP (SAP) after negotiation in multi-AP communication. The first and second non-AP STAs of the present embodiment may correspond to at least one STA (station).

[0007] The present embodiment proposes a method for protecting SAP by setting NAV to prevent a third party STA or an Overlapping Basic Service Set (OBSS) STA from occupying the medium by transmitting an additional CTS frame when performing C-TDMA operation in multi-AP (Access Point) communication (or multi-AP operation). In particular, the present embodiment proposes a method for reserving the medium to prevent a TXOP return fail issue by setting the NAV.

[0008] The first AP (access point) receives a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame from the second AP.

[0009] The first AP transmits a first CTS (Clear to Send) frame to the second AP.

[0010] The first AP receives a second CTS frame from the second AP.

[0011] The first AP transmits a TXOP return sequence to the second AP.

[0012] The above second AP is a Sharing AP that controls cooperation between multiple APs, and the above first AP is a Shared AP that is allocated or shared with resources from the Sharing AP.

[0013] The first CTS frame is a response frame to the MU-RTS TXS trigger frame. Based on the second CTS frame, a first NAV (Network Allocation Vector) is set for the first non-AP STA (station). Alternatively, a second NAV may be set for the first non-AP STA based on the MU-RTS TXS trigger frame, and a NAV timer may be updated before a NAV timeout period of the second NAV expires based on the second CTS frame. Alternatively, a third NAV may be set for the first non-AP STA based on the first NAV setting sequence described below, and a NAV timer may be updated before a NAV timeout period of the third NAV expires based on the second CTS frame. That is, a new NAV may be set due to the additionally transmitted second CTS frame, or a NAV timeout issue of an existing NAV may be prevented, thereby withholding channel access of the first non-AP STA.

[0014] At this time, the first non-AP STA does not participate in the cooperation between the plurality of APs and is in a hidden node relationship with the first AP.

[0015] The technique for cooperation between the above multiple APs may include a coordinated multi-AP technique such as C-TDMA (Coordinated-Time Division Multiplexing Access), C-SR (Coordinated-Spatial Reuse), C-BF (Coordinated-beamforming), or C-OFMA (Coordinated-Orthogonal Frequency Division Multiple Access).

[0016] In an example of C-TDMA operation, an entity sharing a TXOP (SAP, here a second AP) and an entity sharing a TXOP (DAP, here a first AP) are APs with different BSSs. However, an STA (third party STA or OBSS STA, here a first non-AP STA) that has a hidden node relationship with the DAP and does not participate in the C-TDMA operation can determine that the medium is idle during the period in which the TXOP is shared with the SAP DAP, and thus can perform channel access to occupy the medium used by the SAP. In addition, if the third party STA or OBSS STA does not receive a response frame to the MU-RTS TXS trigger frame, the NAV timeout period due to the MU-RTS TXS trigger frame expires, and the NAV can be reset to occupy the medium. That is, even if DAP performs TXOP return using the time allocated from SAP, a problem may occur in which SAP cannot receive TXOP return because the third party STA or OBSS STA may occupy the medium.

[0017] Therefore, the present embodiment proposes a method for reserving medium to ensure that the SAP can receive a TXOP in an environment performing C-TDMA. Specifically, the present invention proposes a method for protecting the SAP by transmitting an additional CTS frame (the second CTS frame) to set a NAV (the first NAV) to prevent the third party STA or OBSS STA from occupying the medium.

[0018] This embodiment proposes a medium reservation method to prevent TXOP return fail issues that may occur in a C-TDMA procedure utilizing multiple TXOPs. The medium reservation method proposed in this embodiment has the effect of protecting an SAP from NAV so that a third-party STA or an OBSS STA (the first non-AP STA) cannot occupy the medium. For example, a DAP can perform a frame exchange for a NAV-set sequence with the SAP during the time allocated by the SAP, thereby allowing surrounding STAs of the SAP to set NAVs during that time. This has the effect of enabling appropriate scheduling according to cooperation between multiple APs, and thus increasing overall network throughput.

[0019] Figure 1 illustrates an example of a transmitting device and / or a receiving device of the present specification.

[0020] Figure 2 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

[0021] Figure 3 is a diagram illustrating a general link setup process.

[0022] Figure 4 illustrates one embodiment of a multi-link (ML).

[0023] FIG. 5 illustrates a PPDU (physical protocol data unit or physical layer (PHY) protocol data unit) transmitted / received by an STA of this specification.

[0024] Figure 6 is a diagram showing the layout of resource units (RUs) used for 20MHz PPDU.

[0025] Figure 7 is a diagram showing the layout of resource units (RUs) used for 40MHz PPDU.

[0026] Figure 8 is a diagram showing the layout of resource units (RUs) used for 80MHz PPDU.

[0027] Figure 9 shows the operation according to UL-MU.

[0028] Figure 10 shows an example of channels used / supported / defined within the 2.4 GHz band.

[0029] Figure 11 illustrates an example of channels used / supported / defined within the 5 GHz band.

[0030] Figure 12 illustrates an example of channels used / supported / defined within the 6 GHz band.

[0031] FIG. 13 illustrates a modified example of a transmitting device and / or a receiving device of the present specification.

[0032] Figure 14 illustrates operation according to a conventional STX operation.

[0033] Figure 15 illustrates an example of C-OFDMA (Coordinated OFDMA).

[0034] Figure 16 illustrates an example of CBF (Coordinated beamforming).

[0035] Figure 17 illustrates an example of AP selection.

[0036] Figure 18 shows an example of JTX / JT.

[0037] Figure 19 shows an example of the operation of a 2-day MU-RTS TXS trigger frame with a value of the TXOP Sharing Mode subfield.

[0038] Figure 20 shows an example of coordinated TDMA operation.

[0039] Figure 21 illustrates an example of C-TDMA operation using two TXOPs.

[0040] Figure 22 illustrates an example of a TXOP return failure issue by a hidden node (STA 3).

[0041] Figure 23 illustrates an embodiment 1 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0042] Figure 24 illustrates an embodiment 2 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0043] Figure 25 illustrates an embodiment 3 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0044] Figure 26 illustrates an embodiment 4 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0045] Figure 27 illustrates an embodiment 5 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0046] Figure 28 illustrates an embodiment 6 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0047] Fig. 29 is a flowchart illustrating the operation of a transmitting device according to the present embodiment.

[0048] Figure 30 is a flowchart illustrating the operation of a receiving device according to the present embodiment.

[0049] FIG. 31 is a flowchart illustrating a procedure of a method for performing C-TDMA operation by transmitting an additional CTS frame on the Sharing AP side according to the present embodiment.

[0050] FIG. 32 is a flowchart illustrating a procedure of a method for performing C-TDMA operation by receiving an additional CTS frame on the Shared AP side according to the present embodiment.

[0051] In this specification, “A or B” can mean “only A,” “only B,” or “both A and B.” In other words, “A or B” in this specification can be interpreted as “A and / or B.” For example, “A, B or C” in this specification can mean “only A,” “only B,” “only C,” or “any combination of A, B, and C.”

[0052] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "and / or B." Accordingly, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0053] In this specification, “at least one of A and B” can mean “only A,” “only B,” or “both A and B.” Additionally, in this specification, the expressions “at least one of A or B” or “at least one of A and / or B” can be interpreted identically to “at least one of A and B.”

[0054] In addition, parentheses used in this specification may mean “for example.” Specifically, when “control information (UHR-Signal field)” is indicated, the “UHR-Signal field” may be suggested as an example of “control information.” In other words, the “control information” in this specification is not limited to the “UHR-Signal field,” and the “UHR-Signal field” may be suggested as an example of “control information.” In addition, even when indicated as “control information (UHR-Signal field),” the “UHR-Signal field” may be suggested as an example of “control information.”

[0055] Additionally, as used herein, “a / an” can mean “at least one” or “one or more.” Additionally, terms ending in “(s)” can mean “at least one” or “one or more.”

[0056] Additionally, the expressions “based on” or “on the basis of” or “according to” used herein mean “based at least in part on” and not “based solely on.”

[0057] Technical features individually described in a single drawing in this specification may be implemented individually or simultaneously.

[0058] The following examples of this specification can be applied to various wireless communication systems. For example, the following examples of this specification can be applied to wireless local area network (WLAN) systems. For example, the present specification can be applied to the IEEE 802.11a / g / n / ac / ax / be / bn standards. In addition, the examples of this specification can be applied to the Ultra High Reliability (UHR) standard or the next-generation wireless LAN standard that enhances IEEE 802.11bn. In addition, the examples of this specification can be applied to mobile communication systems. For example, the examples of this specification can be applied to mobile communication systems based on Long Term Evolution (LTE) and its evolution based on the 3rd Generation Partnership Project (3GPP) standard.

[0059] In order to explain the technical features of this specification, the technical features to which this specification can be applied are described below.

[0060] Figure 1 illustrates an example of a transmitting device and / or a receiving device of the present specification.

[0061] An example of FIG. 1 can perform various technical features described below. FIG. 1 relates to at least one STA (station). For example, the STA (110, 120) of the present specification may also be referred to by various names such as a mobile terminal, a wireless device, a Wireless Transmit / Receive Unit (WTRU), a User Equipment (UE), a Mobile Station (MS), a Mobile Subscriber Unit, or simply a user. The STA (110, 120) of the present specification may also be referred to by various names such as a network, a base station, a Node-B, an access point (AP), a repeater, a router, a relay, etc. The STA (110, 120) of the present specification may also be referred to by various names such as a receiving apparatus, a transmitting apparatus, a receiving STA, a transmitting STA, a receiving device, a transmitting device, etc.

[0062] For example, STA (110, 120) may perform the role of an AP (access point) or a non-AP role. That is, STA (110, 120) of the present specification may perform the functions of an AP and / or a non-AP. In the present specification, AP may also be indicated as an AP STA.

[0063] The STA (110, 120) of this specification can support various communication standards other than the IEEE 802.11 standard. For example, it can support communication standards according to the 3GPP standard (e.g., LTE, LTE-A, 5G NR standard). In addition, the STA of this specification can be implemented in various devices such as mobile phones, vehicles, and personal computers. In addition, the STA of this specification can support communication for various communication services such as voice calls, video calls, data communications, and autonomous driving (Self-Driving, Autonomous-Driving).

[0064] In this specification, STA (110, 120) may include a medium access control (MAC) and a physical layer interface for a wireless medium that follow the provisions of the IEEE 802.11 standard.

[0065] Based on the sub-drawing (a) of Fig. 1, STA (110, 120) is described as follows.

[0066] The first STA (110) may include a processor (111), a memory (112), and a transceiver (113). The illustrated processor, memory, and transceiver may each be implemented as separate chips, or at least two blocks / functions may be implemented through a single chip.

[0067] The transceiver (113) of the first STA performs signal transmission and reception operations. Specifically, it can transmit and receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0068] For example, the first STA (110) can perform the intended operation of the AP. For example, the processor (111) of the AP can receive a signal through the transceiver (113), process the received signal, generate a transmission signal, and perform control for signal transmission. The memory (112) of the AP can store a signal received through the transceiver (113) (i.e., a reception signal) and store a signal to be transmitted through the transceiver (i.e., a transmission signal).

[0069] For example, the second STA (120) can perform the intended operation of a non-AP STA. For example, the transceiver (123) of the non-AP performs signal transmission and reception operations. Specifically, it can transmit and receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0070] For example, the processor (121) of the Non-AP STA can receive a signal through the transceiver (123), process the received signal, generate a transmission signal, and perform control for signal transmission. The memory (122) of the Non-AP STA can store a signal received through the transceiver (123) (i.e., a reception signal) and store a signal to be transmitted through the transceiver (i.e., a transmission signal).

[0071] For example, in the specification below, the operation of a device indicated as AP may be performed in the first STA (110) or the second STA (120). For example, if the first STA (110) is an AP, the operation of the device indicated as AP may be controlled by the processor (111) of the first STA (110), and a related signal may be transmitted or received through a transceiver (113) controlled by the processor (111) of the first STA (110). In addition, control information related to the operation of the AP or a transmission / reception signal of the AP may be stored in the memory (112) of the first STA (110). In addition, when the second STA (110) is an AP, the operation of the device indicated as an AP is controlled by the processor (121) of the second STA (120), and a related signal can be transmitted or received through a transceiver (123) controlled by the processor (121) of the second STA (120). In addition, control information related to the operation of the AP or the transmission / reception signal of the AP can be stored in the memory (122) of the second STA (110).

[0072] For example, in the specification below, the operation of a device indicated as a non-AP (or User-STA) may be performed in the STA (110) or the second STA (120). For example, if the second STA (120) is a non-AP, the operation of the device indicated as a non-AP may be controlled by the processor (121) of the second STA (120), and a related signal may be transmitted or received through a transceiver (123) controlled by the processor (121) of the second STA (120). In addition, control information related to the operation of the non-AP or the transmission / reception signal of the AP may be stored in the memory (122) of the second STA (120). For example, if the first STA (110) is a non-AP, the operation of a device indicated as a non-AP is controlled by the processor (111) of the first STA (110), and a related signal may be transmitted or received through a transceiver (113) controlled by the processor (111) of the first STA (120). In addition, control information related to the operation of the non-AP or the transmission / reception signal of the AP may be stored in the memory (112) of the first STA (110).

[0073] In the following specification, devices called (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) Terminal, (transmitting / receiving) device, (transmitting / receiving) apparatus, network, etc. may refer to the STA (110, 120) of FIG. 1. For example, devices indicated as (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) Terminal, (transmitting / receiving) device, (transmitting / receiving) apparatus, network, etc. without specific drawing symbols may also refer to the STA (110, 120) of FIG. 1. For example, in the example below, the operation of various STAs transmitting and receiving signals (e.g., PPDUs) may be performed by the transceivers (113, 123) of FIG. 1. In addition, in the example below, the operation of various STAs generating transmission and reception signals or performing data processing or calculations in advance for transmission and reception signals may be performed by the processors (111, 121) of FIG. 1.For example, an example of an operation that generates a transmission / reception signal or performs data processing or operation in advance for a transmission / reception signal may include 1) an operation of determining / obtaining / configuring / computing / decoding / encoding bit information of a subfield (SIG, STF, LTF, Data) field included in a PPDU, 2) an operation of determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) used for a subfield (SIG, STF, LTF, Data) field included in a PPDU, 3) an operation of determining / configuring / obtaining a specific sequence (e.g., a pilot sequence, an STF / LTF sequence, an extra sequence applied to SIG) used for a subfield (SIG, STF, LTF, Data) field included in a PPDU, 4) a power control operation and / or a power saving operation applied to an STA, 5) an operation related to determining / obtaining / configuring / computing / decoding / encoding an ACK signal, etc. Additionally, in the examples below, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs for determining / acquiring / configuring / computing / decoding / encoding transmission / reception signals can be stored in the memory (112, 122) of FIG. 1.

[0074] The device / STA of the sub-drawing (a) of the above-described FIG. 1 can be modified as in the sub-drawing (b) of FIG. 1. Hereinafter, the STA (110, 120) of the present specification will be described based on the sub-drawing (b) of FIG. 1.

[0075] For example, the transceiver (113, 123) illustrated in sub-drawing (b) of FIG. 1 may perform the same function as the transceiver illustrated in sub-drawing (a) of FIG. 1 described above. For example, the processing chip (114, 124) illustrated in sub-drawing (b) of FIG. 1 may include a processor (111, 121) and a memory (112, 122). The processor (111, 121) and the memory (112, 122) illustrated in sub-drawing (b) of FIG. 1 may perform the same function as the processor (111, 121) and the memory (112, 122) illustrated in sub-drawing (a) of FIG. 1 described above.

[0076] The mobile terminal, wireless device, Wireless Transmit / Receive Unit (WTRU), User Equipment (UE), Mobile Station (MS), Mobile Subscriber Unit, user, user STA, network, Base Station, Node-B, Access Point (AP), repeater, router, relay, receiving device, transmitting device, receiving STA, transmitting STA, receiving Device, transmitting Device, receiving Apparatus, and / or transmitting Apparatus described below may refer to the STA (110, 120) illustrated in the sub-drawings (a) / (b) of FIG. 1, or may refer to the processing chip (114, 124) illustrated in the sub-drawing (b) of FIG. 1. That is, the technical feature of the present specification may be performed in the STA (110, 120) illustrated in the sub-drawings (a) / (b) of FIG. 1, or may be performed only in the processing chip (114, 124) illustrated in the sub-drawings (b) of FIG. 1. For example, the technical feature that the transmitting STA transmits a control signal may be understood as a technical feature that the control signal generated in the processor (111, 121) illustrated in the sub-drawings (a) / (b) of FIG. 1 is transmitted through the transceiver (113, 123) illustrated in the sub-drawings (a) / (b) of FIG. 1. Alternatively, the technical feature that the transmitting STA transmits a control signal may be understood as a technical feature that the control signal to be transmitted to the transceiver (113, 123) is generated in the processing chip (114, 124) illustrated in the sub-drawings (b) of FIG. 1.

[0077] For example, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal being received by a transceiver (113, 123) illustrated in sub-drawing (a) of FIG. 1. Alternatively, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal received by a transceiver (113, 123) illustrated in sub-drawing (a) of FIG. 1 being acquired by a processor (111, 121) illustrated in sub-drawing (a) of FIG. 1. Alternatively, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal received by a transceiver (113, 123) illustrated in sub-drawing (b) of FIG. 1 being acquired by a processing chip (114, 124) illustrated in sub-drawing (b) of FIG.

[0078] Referring to the sub-drawing (b) of FIG. 1, software code (115, 125) may be included in the memory (112, 122). The software code (115, 125) may include instructions that control the operation of the processor (111, 121). The software code (115, 125) may be included in various programming languages.

[0079] The processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device. The processor may be an application processor (AP). For example, the processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). For example, the processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may be a SNAPDRAGON™ series processor manufactured by Qualcomm®, an EXYNOSTM series processor manufactured by Samsung®, an A series processor manufactured by Apple®, a HELIO™ series processor manufactured by MediaTek®, an ATOM™ series processor manufactured by INTEL®, or an enhanced processor thereof.

[0080] In this specification, uplink may mean a link for communication from a non-AP STA to an AP STA, and uplink PPDU / packet / signal, etc. may be transmitted through the uplink. In addition, in this specification, downlink may mean a link for communication from an AP STA to a non-AP STA, and downlink PPDU / packet / signal, etc. may be transmitted through the downlink.

[0081] Figure 2 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

[0082] The upper part of Figure 2 shows the structure of the infrastructure BSS (basic service set) of IEEE (institute of electrical and electronic engineers) 802.11.

[0083] The upper part of Figure 2 shows the structure of the infrastructure BSS (basic service set) of IEEE (institute of electrical and electronic engineers) 802.11.

[0084] Referring to the top of FIG. 2, the wireless LAN system may include one or more infrastructure BSSs (200, 205) (hereinafter, BSS). The BSSs (200, 205) are a collection of APs and STAs, such as an access point (AP) 225 and a station (STA1, 200-1), that have successfully synchronized and can communicate with each other, and are not a concept that designates a specific area. The BSS (205) may also include one or more STAs (205-1, 205-2) that can be associated with one AP (230).

[0085] A BSS may include at least one STA, an AP (225, 230) providing a distribution service, and a distribution system (DS, 210) connecting multiple APs.

[0086] A distributed system (210) can connect multiple BSSs (200, 205) to implement an extended service set (ESS, 240). An ESS (240) can be used as a term to indicate a network formed by connecting one or more APs through the distributed system (210). APs included in a single ESS (240) can have the same SSID (service set identification).

[0087] The portal (portal, 220) can act as a bridge to connect a wireless LAN network (IEEE 802.11) to another network (e.g., 802.X).

[0088] In a BSS such as the upper part of Fig. 2, a network between APs (225, 230) and a network between APs (225, 230) and STAs (200-1, 205-1, 205-2) can be implemented. However, it may also be possible to establish a network and perform communication between STAs without an AP (225, 230). A network that establishes a network and performs communication between STAs without an AP (225, 230) is defined as an ad-hoc network or an independent basic service set (IBSS).

[0089] The bottom of Figure 2 is a conceptual diagram showing IBSS.

[0090] Referring to the bottom of Fig. 2, the IBSS is a BSS that operates in ad-hoc mode. Since the IBSS does not include an AP, there is no centralized management entity. That is, in the IBSS, the STAs (250-1, 250-2, 250-3, 255-4, 255-5) are managed in a distributed manner. In the IBSS, all STAs (250-1, 250-2, 250-3, 255-4, 255-5) can be mobile STAs, and access to the distributed system is not permitted, forming a self-contained network.

[0091] Figure 3 is a diagram illustrating a general link setup process.

[0092] In step S310, the STA may perform a network discovery operation. This network discovery operation may include scanning by the STA. That is, for the STA to access the network, it must find a network it can join. Before joining a wireless network, the STA must identify compatible networks. The process of identifying networks in a specific area is called scanning. Scanning methods include active scanning and passive scanning.

[0093] Figure 3 illustrates a network discovery operation that includes an active scanning process as an example. In active scanning, an STA performing scanning transmits a probe request frame to discover which APs exist in the vicinity while moving between channels and waits for a response. A responder transmits a probe response frame to the STA that transmitted the probe request frame in response to the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame in the BSS of the channel being scanned. In a BSS, the AP transmits the beacon frame, so the AP becomes the responder. In an IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not constant. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning (i.e., transmitting and receiving probe requests / responses on channel 2) in the same manner.

[0094] Although not shown in the example of FIG. 3, the scanning operation can also be performed in a passive scanning manner. An STA performing scanning based on passive scanning can wait for a beacon frame while moving between channels. A beacon frame is one of the management frames in IEEE 802.11. It announces the presence of a wireless network and is periodically transmitted so that the scanning STA can find the wireless network and participate in the wireless network. In the BSS, the AP periodically transmits the beacon frame, and in the IBSS, the STAs within the IBSS take turns transmitting the beacon frame. When the scanning STA receives a beacon frame, it stores the information about the BSS included in the beacon frame and moves to another channel, recording the beacon frame information on each channel. An STA that receives a beacon frame can store the BSS-related information included in the received beacon frame, move to the next channel, and perform scanning on the next channel in the same manner.

[0095] An STA that discovers a network can perform an authentication process through step S320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation of step S340 described below. The authentication process of S320 may include a process in which the STA transmits an authentication request frame to the AP, and the AP responds by transmitting an authentication response frame to the STA. The authentication frame used for the authentication request / response corresponds to a management frame.

[0096] The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), and a Finite Cyclic Group.

[0097] An STA can transmit an authentication request frame to an AP. The AP can determine whether to grant authentication to the STA based on the information contained in the received authentication request frame. The AP can provide the result of the authentication process to the STA via an authentication response frame.

[0098] A successfully authenticated STA may perform an association process based on step S330. The association process includes a process in which the STA transmits an association request frame to the AP, and the AP transmits an association response frame to the STA in response. For example, the association request frame may include information related to various capabilities, such as a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, RSN, mobility domain, supported operating classes, a Traffic Indication Map Broadcast request, and interworking service capabilities. For example, the association response frame may contain information related to various capabilities, status codes, Association ID (AID), supported rates, Enhanced Distributed Channel Access (EDCA) parameter sets, Received Channel Power Indicator (RCPI), Received Signal to Noise Indicator (RSNI), mobility domains, timeout interval (association comeback time), overlapping BSS scan parameters, TIM broadcast response, QoS maps, etc.

[0099] In step S340, the STA may perform a security setup process. The security setup process of step S340 may include, for example, a process of setting up a private key through a four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame.

[0100] Figure 4 illustrates one embodiment of a multi-link (ML).

[0101] As illustrated in FIG. 4, multiple multi-link devices (MLDs) can communicate over a remote link. The MLDs can be categorized into AP MLDs including multiple AP STAs and non-AP MLDs including multiple non-AP STAs. That is, the AP MLD can include affiliated APs (i.e., AP STAs), and the non-AP MLD can include affiliated STAs (i.e., non-AP STAs, or user-STAs).

[0102] A multilink may include a first link and a second link, and different channels / subchannels / frequency resources may be allocated to the first and second links. The first and second multilinks may be identified through a link ID of 4 bits (or other n bits). The first and second links may be configured in the same 2.4 GHz, 5 GHz, or 6 GHz band. Alternatively, the first link and the second link may be configured in different bands.

[0103] The AP MLD of FIG. 4 includes three affiliated APs. In the example of FIG. 4, AP1 may operate in the 2.4 GHz band, AP2 may operate in the 5 GHz band, and AP3 may operate in the 6 GHz band. In the example of FIG. 4, the first link in which AP1 and non-AP1 operate may be defined as a channel / subchannel / frequency resource within the 2.4 GHz band. Furthermore, in the example of FIG. 4, the second link in which AP2 and non-AP2 operate may be defined as a channel / subchannel / frequency resource within the 5 GHz band. Furthermore, in the example of FIG. 4, the third link in which AP3 and non-AP3 operate may be defined as a channel / subchannel / frequency resource within the 6 GHz band.

[0104] In the example of FIG. 4, AP1 may initiate a multi-link setup procedure (ML setup procedure) by transmitting an Association Request frame to non-AP STA1. In the example of FIG. 4, non-AP STA1 may transmit an Association Response frame in response to the Association Request frame. Each AP (e.g., AP1 / 2 / 3) illustrated in FIG. 4 may be identical to the AP illustrated in FIG. 1 and / or FIG. 2, and each non-AP (e.g., non-AP1 / 2 / 3) illustrated in FIG. 4 may be identical to the STA (i.e., user-STA or non-AP STA) illustrated in FIG. 1 and / or FIG. 2.

[0105] The specific features of this specification are not limited to the specific features of FIG. 4. That is, the number of links can be defined in various ways, and multiple links can be defined in various ways within at least one band.

[0106] FIG. 5 illustrates a PPDU (physical protocol data unit or physical layer (PHY) protocol data unit) transmitted / received by an STA of this specification.

[0107] The STA (e.g., AP STA, non-AP STA, AP MLD, non-AP MLD) of the present specification can transmit and / or receive the PPDU of FIG. 5. The PPDU described in the present specification may have, for example, the structure of FIG. 5. In addition, the PPDU described in the present specification may be called by various names such as a transmission PPDU, a reception PPDU, a first type PPDU, or an Nth type PPDU, etc. The PPDU described in the present specification can be used in a WLAN system defined according to IEEE 802.11bn and / or a next-generation WLAN system that improves IEEE 802.11bn.

[0108] The PPDU of FIG. 5 may be related to various PPDU types used in a UHR system. For example, the example of FIG. 5 may be used for at least one of a single-user (SU) mode / type / transmission, a multi-user (MU) mode / type / transmission, and a null data packet (NDP) mode / type / transmission related to channel sounding. For example, if the example of FIG. 5 is related to NDP, the Data field illustrated may be omitted. If the PPDU of FIG. 5 is used for a trigger-based (TB) mode, the UHR-SIG of FIG. 5 may be omitted. In other words, an STA that has received a trigger frame for UL-MU (Uplink-MU) communication may transmit a PPDU with the UHR-SIG omitted in the example of FIG. 5.

[0109] In FIG. 5, L-STF or UHR-LTF may be called a preamble or physical preamble, and may be generated / transmitted / received / acquired / decoded in the physical layer (included in the transmitting / receiving STA).

[0110] Each block illustrated in Fig. 5 may be called a field / subfield / signal, etc. The names of these fields / subfields / signals may be, as illustrated in Fig. 5, L-STF (legacy short training field), L-LTF (legacy long training field), L-SIG (legacy signal), RL-SIG (repeated L-SIG), U-SIG (Universal Signal), UHR-SIG (UHR-signal), etc.

[0111] The subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG fields in FIG. 5 may be set to 312.5 kHz, and the subcarrier spacing of the UHR-STF, UHR-LTF, and Data fields may be set to 78.125 kHz. That is, the tone index (or subcarrier index) of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG fields may be expressed in units of 312.5 kHz, and the tone index (or subcarrier index) of the UHR-STF, UHR-LTF, and Data fields may be expressed in units of 78.125 kHz.

[0112] In the PPDU of Fig. 5, L-LTF and L-STF may be identical to conventional fields (e.g., non-HT LTF and non-HT STF defined in conventional WLAN standards).

[0113] The L-SIG field of FIG. 5 may include, for example, 24 bits of bit information. For example, the 24 bits of information may include a 4 bit Rate field, a 1 bit Reserved bit, a 12 bit Length field, a 1 bit Parity bit, and a 6 bit Tail bit. For example, the 12 bit Length field may include information about the length or time duration of the PPDU. For example, the value of the 12 bit Length field may be determined based on the type of the PPDU. For example, if the PPDU is a non-HT (non-High Throughput), HT (High Throughput), VHT (Very High Throughput) PPDU, or an EHT (extremely high throughput) PPDU or UHR PPDU, the value of the Length field may be determined as a multiple of 3. For example, if the PPDU is a HE PPDU, the value of the Length field may be determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, for non-HT, HT, VHT PPDU, EHT PPDU, UHR PPDU, the value of the Length field can be determined as a multiple of 3, and for HE (High-Efficiency) PPDU, the value of the Length field can be determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, the Length field in an UHR PPDU is set to a value satisfying the condition that the remainder is zero when LENGTH is divided by 3.

[0114] For example, (non-AP and AP) STAs can apply BCC encoding based on a code rate of 1 / 2 to the 24 bits of information in the L-SIG field. Then, the transmitting STA can obtain 48 BCC coded bits. BPSK modulation can be applied to the 48 coded bits to generate 48 BPSK symbols. The transmitting STA can map the 48 BPSK symbols to positions excluding the pilot subcarriers {subcarrier index -21, -7, +7, +21} and the DC subcarrier {subcarrier index 0}. As a result, the 48 BPSK symbols can be mapped to subcarrier indices -26 to -22, -20 to -8, -6 to -1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA can additionally map the signal {-1, -1, -1, 1} to the subcarrier indices {-28, -27, +27, +28}. The above signal can be used for channel estimation for the frequency domain corresponding to {-28, -27, +27, +28}.

[0115] For example, (non-AP and AP) STA can generate RL-SIG, which is generated in the same manner as L-SIG. BPSK modulation can be applied to RL-SIG. Receiving (non-AP and AP) STA can determine whether the received PPDU is a HE PPDU, EHT PPDU, or UHR PPDU based on the presence of RL-SIG. In other words, if RL-SIG is present, receiving (non-AP and AP) STA can determine whether the received PPDU is one of HE PPDU, EHT PPDU, or UHR PPDU. In other words, if RL-SIG is not present, receiving (non-AP and AP) STA can determine whether the received PPDU is one of non-HT PPDU, HT PPDU, or VHT PPDU. In other words, the RL-SIG field is a repeat of the L-SIG field and is used to differentiate an UHR PPDU from a non-HT PPDU, HT PPDU, and VHT PPDU.

[0116] After the RL-SIG in Fig. 5, a U-SIG (Universal SIG) may be inserted. The U-SIG may be called by various names such as the first SIG field, the first SIG, the first type SIG, the control signal, the control signal field, the first (type) control signal, the common control field, and the common control signal.

[0117] A U-SIG can contain N bits of information and can include information for identifying the type of EHT PPDU. For example, a U-SIG can be formed based on two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., an OFDM symbol) for a U-SIG can have a duration of 4 microseconds. Each symbol of a U-SIG can be used to transmit 26 bits of information. For example, each symbol of a U-SIG can be transmitted and received based on 52 data tones and 4 pilot tones.

[0118] For example, A bit information (e.g., 52 uncoded bits) can be transmitted through U-SIG, and the first symbol of U-SIG can transmit the first X bits of information (e.g., 26 uncoded bits) out of the total A bit information, and the second symbol of U-SIG can transmit the remaining Y bits of information (e.g., 26 uncoded bits) out of the total A bit information. For example, the transmitting STA can obtain 26 uncoded bits included in each U-SIG symbol. The transmitting STA can perform convolutional encoding (i.e., BCC encoding) based on a rate of R=1 / 2 to generate 52 coded bits, and perform interleaving on the 52 coded bits. The transmitting STA can perform BPSK modulation on the interleaved 52 coded bits to generate 52 BPSK symbols allocated to each U-SIG symbol. A single U-SIG symbol can be transmitted based on 56 tones (subcarriers) from subcarrier index -28 to subcarrier index +28, excluding DC index 0. The 52 BPSK symbols generated by the transmitting STA can be transmitted based on the remaining tones (subcarriers) excluding the pilot tones -21, -7, +7, and +21.

[0119] For example, A bit information (e.g., 52 uncoded bits) transmitted by U-SIG may include a CRC field (e.g., a 4-bit long field) and a tail field (e.g., a 6-bit long field). The CRC field and the tail field may be transmitted through the second symbol of the U-SIG. The CRC field may be generated based on 26 bits allocated to the first symbol of the U-SIG and the remaining 16 bits excluding the CRC / tail field within the second symbol, and may be generated based on a conventional CRC calculation algorithm. In addition, the tail field may be used to terminate the trellis of the convolutional decoder and may be set to, for example, "000000".

[0120] The A bit information (e.g., 52 uncoded bits) transmitted by the U-SIG (or U-SIG field) can be divided into version-independent bits and version-dependent bits. For example, the size of the version-independent bits can be fixed or variable. For example, the version-independent bits can be assigned only to the first symbol of the U-SIG, or the version-independent bits can be assigned to both the first symbol and the second symbol of the U-SIG. For example, the version-independent bits and the version-dependent bits can be called by various names, such as the first control bit and the second control bit.

[0121] For example, the version-independent bits of the U-SIG may include a 3-bit PHY version identifier. For example, the 3-bit PHY version identifier may include information related to the PHY version of the transmitted and received PPDU. For example, a first value (e.g., a value of 000) of the 3-bit PHY version identifier may indicate that the transmitted and received PPDU is an EHT PPDU. In addition, a second value (e.g., a value of 001) of the 3-bit PHY version identifier may indicate that the transmitted and received PPDU is an UHR PPDU.

[0122] In other words, when the (AP / non-AP) STA transmits an EHT PPDU, it can set the 3-bit PHY version identifier to the first value. In other words, the receiving (AP / non-AP) STA can determine that the received PPDU is an EHT PPDU based on the PHY version identifier having the first value, and can determine that the received PPDU is an UHR PPDU based on the PHY version identifier having the second value.

[0123] For example, the version-independent bits of U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication.

[0124] For example, the version-independent bits of U-SIG may include information about the length of a transmission opportunity (TXOP) and information about the BSS color ID.

[0125] For example, if a UHR PPDU is classified into various types (e.g., a type related to SU transmission (performed based on UL or DL), a type related to DL transmission, a type related to NDP transmission, a type related to DL non-MU-MIMO, a type related to DL MU-MIMO, a type related to Multi-AP operation, a type related to CBF (Coordinated beamforming), SR (Spatial Reuse), a type related to C-OFDMA (Coordinated OFDMA), a type related to C-TDMA (Coordinated TDMA)), information about the type of the EHT PPDU (e.g., 2-bit or 3-bit information) can be included in the version-dependent bits of the U-SIG.

[0126] For example, a U-SIG may include information about 1) a bandwidth field including information about a bandwidth, 2) a field including information about an MCS technique applied to the UHR-SIG, 3) an indication field including information about whether a dual subcarrier modulation (DCM) technique is applied to the UHR-SIG, 4) a field including information about the number of symbols used for the UHR-SIG, 5) a field including information about whether the UHR-SIG is generated over the entire band, 6) a field including information about the type of UHR-LTF / STF, and 7) a field indicating the length of the UHR-LTF and the CP length.

[0127] Preamble puncturing may be applied to the PPDU of FIG. 5. Preamble puncturing refers to applying puncturing to a portion of the entire bandwidth of the PPDU (e.g., the secondary 20 MHz band). For example, when an 80 MHz PPDU is transmitted, the STA applies puncturing to the secondary 20 MHz band within the 80 MHz band, and can transmit the PPDU only through the primary 20 MHz band and the secondary 40 MHz band.

[0128] For example, the pattern of preamble puncturing can be preset. For example, when the first puncturing pattern is applied, puncturing can be applied only to the secondary 20 MHz band within the 80 MHz band. For example, when the second puncturing pattern is applied, puncturing can be applied only to one of the two secondary 20 MHz bands included in the secondary 40 MHz band within the 80 MHz band. For example, when the third puncturing pattern is applied, puncturing can be applied only to the secondary 20 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band). For example, when the fourth puncturing pattern is applied, a primary 40 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band) may be present, and puncturing may be applied to at least one 20 MHz channel that does not belong to the primary 40 MHz band.

[0129] Information regarding preamble puncturing applied to the PPDU may be included in the U-SIG and / or UHR-SIG. For example, the first field of the U-SIG may include information regarding the contiguous bandwidth of the PPDU, and the second field of the U-SIG may include information regarding preamble puncturing applied to the PPDU.

[0130] For example, U-SIG and UHR-SIG may include information regarding preamble puncturing based on the following method. If the bandwidth of the PPDU exceeds 80 MHz, the U-SIG may be individually configured in units of 80 MHz. For example, if the bandwidth of the PPDU is 160 MHz, the PPDU may include a first U-SIG for the first 80 MHz band and a second U-SIG for the second 80 MHz band. In this case, the first field of the first U-SIG may include information regarding the 160 MHz bandwidth, and the second field of the first U-SIG may include information regarding preamble puncturing applied to the first 80 MHz band (i.e., information regarding the preamble puncturing pattern). Additionally, the first field of the second U-SIG may include information about a 160 MHz bandwidth, and the second field of the second U-SIG may include information about preamble puncturing applied to the second 80 MHz band (i.e., information about a preamble puncturing pattern). Meanwhile, the UHR-SIG consecutive to the first U-SIG may include information about preamble puncturing applied to the second 80 MHz band (i.e., information about a preamble puncturing pattern), and the UHR-SIG consecutive to the second U-SIG may include information about preamble puncturing applied to the first 80 MHz band (i.e., information about a preamble puncturing pattern).

[0131] Additionally or alternatively, U-SIG and UHR-SIG may include information regarding preamble puncturing based on the following methods. U-SIG may include information regarding preamble puncturing for all bands (i.e., information regarding preamble puncturing patterns). That is, UHR-SIG may not include information regarding preamble puncturing, and only U-SIG may include information regarding preamble puncturing (i.e., information regarding preamble puncturing patterns).

[0132] U-SIGs can be configured in 20 MHz units. For example, if an 80 MHz PPDU is configured, U-SIGs can be duplicated. That is, four identical U-SIGs can be included within an 80 MHz PPDU. PPDUs exceeding the 80 MHz bandwidth can contain different U-SIGs.

[0133] The UHR-SIG of FIG. 5 may include control information for a receiving STA. The UHR-SIG may be transmitted via at least one symbol, and each symbol may have a length of 4 us. Information regarding the number of symbols used for the UHR-SIG may be included in the U-SIG.

[0134] UHR-SIG provides additional signals to the U-SIG field to enable STAs to interpret / decode UHR PPDUs. The UHR-SIG field may contain U-SIG overflow bits that are common to all users. The UHR-SIG field also contains resource allocation information, allowing STAs to look up resources used in fields containing data fields / UHR-STF / UHR-LTF (i.e., UHR modulated fields of an UHR PPDU).

[0135] The frequency resources of the UHR-LTF, UHR-STF, and data fields illustrated in FIG. 5 can be determined based on RUs (resource units) defined by multiple subcarriers / tones. That is, the UHR-LTF, UHR-STF, and data fields of this specification can be transmitted / received through RUs (resource units) defined by multiple subcarriers / tones.

[0136] FIG. 6 is a diagram illustrating the layout of resource units (RUs) used for a 20 MHz PPDU. That is, the UHR-LTF, UHR-STF, and / or data fields included in the 20 MHz PPDU can be transmitted / received through at least one of the various RUs defined in FIG. 6.

[0137] As shown at the top of Fig. 6, 26 units (i.e., units corresponding to 26 tones) can be arranged. Six tones can be used as a guard band in the leftmost band of the 20 MHz band, and five tones can be used as a guard band in the rightmost band of the 20 MHz band. In addition, seven DC tones can be inserted in the center band, i.e., the DC band, and 26 units corresponding to 13 tones can exist on each side of the DC band. In addition, 26 units, 52 units, and 106 units can be allocated to other bands. Each unit can be allocated for a receiving station, i.e., a user.

[0138] Meanwhile, the RU arrangement of FIG. 6 is utilized not only in a situation for multiple users (MUs) but also in a situation for a single user (SU), in which case it is possible to use one 242-unit as shown at the bottom of FIG. 4, in which case three DC tones can be inserted.

[0139] In the example of Fig. 6, RUs of various sizes, such as 26-RU, 52-RU, 106-RU, and 242-RU, are proposed. Since the specific sizes of these RUs can be expanded or increased, the present embodiment is not limited to the specific size of each RU (i.e., the number of corresponding tones). In this specification, N-RU may be represented as N-tone RU, etc. For example, 26-RU may be represented as 26-tone RU.

[0140] Figure 7 is a diagram showing the layout of resource units (RUs) used for 40MHz PPDU.

[0141] As in the example of Fig. 6 where RUs of various sizes were used, the example of Fig. 7 can also use 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, etc. In addition, 5 DC tones can be inserted at the center frequency, 12 tones can be used as a guard band in the leftmost band of the 40 MHz band, and 11 tones can be used as a guard band in the rightmost band of the 40 MHz band.

[0142] Additionally, as illustrated, 484 RUs may be used when used for a single user. Meanwhile, the specific number of RUs may be changed, as in the example of FIG. 6.

[0143] Figure 8 is a diagram illustrating the layout of resource units (RUs) used for an 80MHz PPDU. The layout of resource units (RUs) used in this specification may vary. For example, the layout of resource units (RUs) used in the 80MHz band may vary.

[0144] Figure 9 illustrates an operation according to UL-MU. As illustrated, a transmitting STA (e.g., AP) can perform channel access through contending (i.e., backoff operation) and transmit a trigger frame (930). That is, the transmitting STA (e.g., AP) can transmit a PPDU including a trigger frame (930). When a PPDU including a trigger frame is received, a TB (trigger-based) PPDU is transmitted after a delay of SIFS.

[0145] TB PPDUs (941, 942) are transmitted at the same time and can be transmitted from multiple STAs (e.g., User STAs) whose AIDs are indicated in the Trigger frame (930). The ACK frame (950) for the TB PPDU can be implemented in various forms.

[0146] Figure 10 shows an example of channels used / supported / defined within the 2.4 GHz band.

[0147] The 2.4 GHz band may be referred to by other names, such as the first band (band). Furthermore, the 2.4 GHz band may refer to a frequency range in which channels with a center frequency adjacent to 2.4 GHz (e.g., channels with a center frequency between 2.4 and 2.5 GHz) are used / supported / defined.

[0148] The 2.4 GHz band may include multiple 20 MHz channels. The 20 MHz within the 2.4 GHz band may have multiple channel indices (e.g., indices 1 through 14). For example, the center frequency of a 20 MHz channel assigned channel index 1 may be 2.412 GHz, the center frequency of a 20 MHz channel assigned channel index 2 may be 2.417 GHz, and the center frequency of a 20 MHz channel assigned channel index N may be (2.407 + 0.005*N) GHz. The channel indices may be referred to by various names, such as channel numbers. The specific numerical values ​​of the channel indices and center frequencies may change.

[0149] Figure 10 exemplarily illustrates four channels within the 2.4 GHz band. The illustrated first frequency region (1010) to fourth frequency region (1040) may each include one channel. For example, the first frequency region (1010) may include channel 1 (a 20 MHz channel having an index of 1). In this case, the center frequency of channel 1 may be set to 2412 MHz. The second frequency region (1020) may include channel 6. In this case, the center frequency of channel 6 may be set to 2437 MHz. The third frequency region (1030) may include channel 11. In this case, the center frequency of channel 11 may be set to 2462 MHz. The fourth frequency region (1040) may include channel 14. In this case, the center frequency of channel 14 may be set to 2484 MHz.

[0150] Figure 11 illustrates an example of channels used / supported / defined within the 5 GHz band.

[0151] The 5 GHz band may be referred to by other names, such as a second band / band, etc. The 5 GHz band may refer to a frequency range in which channels with center frequencies greater than or equal to 5 GHz and less than 6 GHz (or less than 5.9 GHz) are used / supported / defined. Alternatively, the 5 GHz band may include multiple channels between 4.5 GHz and 5.5 GHz. The specific figures shown in FIG. 11 are subject to change.

[0152] Multiple channels within the 5 GHz band include Unlicensed National Information Infrastructure (UNII)-1, UNII-2, UNII-3, and ISM. UNII-1 may be referred to as UNII Low. UNII-2 may include frequency ranges called UNII Mid and UNII-2Extended. UNII-3 may be referred to as UNII-Upper.

[0153] Within the 5 GHz band, multiple channels can be configured, and the bandwidth of each channel can be variously configured, such as 20 MHz, 40 MHz, 80 MHz, or 160 MHz. For example, the 5170 MHz to 5330 MHz frequency domain / range within UNII-1 and UNII-2 can be divided into eight 20 MHz channels. The 5170 MHz to 5330 MHz frequency domain / range can be divided into four channels through a 40 MHz frequency domain. The 5170 MHz to 5330 MHz frequency domain / range can be divided into two channels through an 80 MHz frequency domain. Alternatively, the 5170 MHz to 5330 MHz frequency domain / range can be divided into one channel through a 160 MHz frequency domain.

[0154] Figure 12 illustrates an example of channels used / supported / defined within the 6 GHz band.

[0155] The 6 GHz band may also be referred to by other names, such as the third band / band. The 6 GHz band may refer to the frequency range in which channels with center frequencies above 5.9 GHz are used, supported, or defined. The specific figures shown in Figure 12 are subject to change.

[0156] For example, the 20 MHz channel of FIG. 12 can be defined from 5.940 GHz. Specifically, the leftmost channel among the 20 MHz channels of FIG. 12 can have an index of 1 (or channel index, channel number, etc.), and a center frequency of 5.945 GHz can be assigned. That is, the center frequency of the indexed channel N can be determined as (5.940 + 0.005*N) GHz.

[0157] Accordingly, the indexes (or channel numbers) of the 20 MHz channels of FIG. 12 are 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125, 129, 133, 137, 141, 145, 149, 153, 157, 161, 165, 169, 173, 177, 181, 185, 189, 193, It can be 197, 201, 205, 209, 213, 217, 221, 225, 229, 233. Also, according to the (5.940 + 0.005*N) GHz rule mentioned above, the indices of the 40 MHz channels in Fig. 12 can be 3, 11, 19, 27, 35, 43, 51, 59, 67, 75, 83, 91, 99, 107, 115, 123, 131, 139, 147, 155, 163, 171, 179, 187, 195, 203, 211, 219, 227.

[0158] FIG. 13 illustrates a modified example of a transmitting device and / or a receiving device of the present specification.

[0159] The devices (e.g., AP STA, non-AP STA) illustrated in FIGS. 1 to 4 may be modified as illustrated in FIG. 13. The transceiver (630) of FIG. 13 may be identical to the transceivers (113, 123) of FIG. 1. The transceiver (630) of FIG. 13 may include a receiver and a transmitter.

[0160] The processor (610) of FIG. 13 may be identical to the processor (111, 121) of FIG. 1. Alternatively, the processor (610) of FIG. 13 may be identical to the processing chip (114, 124) of FIG. 1.

[0161] The memory (150) of FIG. 13 may be the same as the memory (112, 122) of FIG. 1. Alternatively, the memory (150) of FIG. 13 may be a separate external memory different from the memory (112, 122) of FIG. 1.

[0162] Referring to FIG. 13, a power management module (611) manages power to a processor (610) and / or a transceiver (630). A battery (612) supplies power to the power management module (611). A display (613) outputs results processed by the processor (610). A keypad (614) receives input to be used by the processor (610). The keypad (614) may be displayed on the display (613). A SIM card (615) may be an integrated circuit used to securely store an international mobile subscriber identity (IMSI) and an associated key used to identify and authenticate a subscriber in a mobile phone device, such as a mobile phone or computer.

[0163] Referring to FIG. 13, the speaker (640) can output sound-related results processed by the processor (610). The microphone (641) can receive sound-related input to be used by the processor (610).

[0164] Below, the Multi-AP operation applied to this specification is described.

[0165] The above Multi-AP operation refers to a communication technique related to multiple APs in a WLAN. For example, the Multi-AP operation may refer to an operation in which one or more APs transmit and receive information to one or more STAs. In contrast to the Multi-AP operation, existing techniques may be expressed by various terms such as STX (Single Transmission). For example, the STX operation may refer to a method in which one BSS AP performs communication with one BSS STA. When communication is performed based on the STX operation, interference with adjacent APs (e.g., APs located in an overlapping BSS) may occur. Due to such interference, a problem in which the transmission and reception performance of cell-edge users (e.g., non-AP STAs located at the edge of the BSS) is reduced may occur.

[0166] Figure 14 illustrates operation according to a conventional STX operation. As illustrated, interference between STA and AP may occur due to adjacent AP1 and AP2.

[0167] To improve the above STX operation, a new Multi-AP operation is proposed. The Multi-AP operation may be based on a technology that reduces various interferences, such as Inter-Symbol Interference (ISI), through coordination with neighboring APs (e.g., APs located in overlapping BSSs).

[0168] In Fig. 14, STA1 and AP1 may be included in a BSS, and STA2 and AP2 may be included in an OBSS (Overlapping Basic Service Set). That is, STA2 may be an unassociated STA to AP1, and STA1 may be an unassociated STA to AP2.

[0169] For example, the Multi-AP operation can be classified into various technologies / types / formats / protocols, etc. For example, the Multi-AP operation can include Coordinated TDMA (C-TDMA) that distinguishes wireless resources allocated to multiple APs based on a time axis (time domain). Additionally or alternatively, the Multi-AP operation can include Coordinated OFDMA (C-OFDMA) that distinguishes wireless resources allocated to multiple APs based on a frequency axis (time domain). Additionally or alternatively, the Multi-AP operation can include Coordinated Spatial Reuse (C-SR) that applies Spatial Reuse (SR) to at least one AP. Additionally or alternatively, the Multi-AP operation can include Coordinated beamforming (CBF) / nulling that nulls and transmits interference generated from neighbors (e.g., adjacent APs / STAs, and / or OBSS APs / OBSS STAs). Additionally or alternatively, the Multi-AP operation may include AP selection in which an AP with a good channel condition among neighboring APs (e.g., at least one AP located within a BSS or OBSS and with a good channel condition) transmits. Additionally or alternatively, the Multi-AP operation may include Joint Transmission (JTX) or JT in which multiple APs (e.g., multiple APs included in the same BSS / OBSS, or multiple APs included in different BSS / OBSS) cooperate to perform simultaneous transmission and reception, and JTX / JT may be implemented based on Joint Beamforming or Joint MU-MIMO.

[0170] FIG. 15 illustrates an example of Coordinated OFDMA (C-OFDMA). The illustrated AP1 may transmit a PPDU / signal to STA1, and AP2 may transmit a PPDU / signal to STA2. Transmission from AP1 and transmission from AP2 may be performed in the same / overlapping time intervals. Transmission from AP1 to STA1 may be performed based on a first frequency band, and transmission from AP2 to STA2 may be performed based on a second frequency band different from the second frequency band. For example, in FIG. 15, STA1 and AP1 may be included in a BSS, and STA2 and AP2 may be included in an OBSS. That is, STA2 may be an unassociated STA to AP1, and STA1 may be an unassociated STA to AP2.

[0171] Although not illustrated in Figure 15, an example of Coordinated TDMA (C-TDMA) is also possible. For example, the acquired TXOP can be divided into specific time units (e.g., slots), and the divided slots can be sequentially assigned to multiple different APs.

[0172] The above-described example of C-OFDMA can be further modified as follows. For example, an AP (e.g., AP1) that has acquired a TXOP can share frequency resources with at least one AP in the vicinity (e.g., AP2 existing in the BSS / OBSS). For example, the shared frequency resources can be defined in units of RU (resource units) or subchannels, and for example, frequency resources can be shared by AP1 to AP2 in units of 20 / 40 / 80 MHz subchannels or 242 / 484 / 996-tone RUs for flexibility.

[0173] AP1, which performs C-OFDMA, can act as a sharing AP or a master AP. That is, AP1 can request at least one AP in its vicinity (e.g., AP2 in the BSS / OBSS) to report information about the channel and / or buffer status. Based on this, AP1 can obtain a TXOP and share a portion of its frequency resources (e.g., a 20 MHz subchannel or a RU of a specific size) with at least one AP in its vicinity (e.g., AP2 in the BSS / OBSS) within all or part of the time interval associated with the TXOP.

[0174] Figure 16 illustrates an example of Coordinated Beamforming (CBF). In the illustrated example, AP1 may transmit a PPDU / signal to STA1, and AP2 may transmit a PPDU / signal to STA2. Transmissions from AP1 and AP2 may be performed in the same / overlapping time intervals. Transmissions from AP1 and AP2 may be performed through the same / overlapping frequency bands. In order to reduce interference caused to STA2 by AP1, AP1 may perform nulling / beamforming toward STA2, and in order to reduce interference caused to STA1 by AP2, AP2 may perform nulling / beamforming toward STA1. For example, such nulling / beamforming may be implemented in a manner of positioning a radiation null to a neighboring unassociated STA. The above-described nulling / beamforming may make a specific AP invisible to a neighboring unassociated STA. For example, the above-described nulling / beamforming may make AP1 (or AP2) invisible to STA2 (or STA1).

[0175] For example, in FIG. 16, STA1 and AP1 may be included in a BSS, and STA2 and AP2 may be included in an OBSS. That is, STA2 may be an un-associated STA to AP1, and STA1 may be an un-associated STA to AP2.

[0176] Although not shown in FIG. 16, control signals (e.g., coordination frames) for nulling / beamforming between AP1 and STA2 and / or nulling / beamforming between AP2 and STA1 may be transmitted and received over the backhaul link between AP1 and AP2.

[0177] Figure 17 illustrates an example of AP selection. The illustrated AP2 is determined to have a better channel condition than AP1. AP1 transmits its data / signal to AP2 via a backhaul link, and AP2, instead of AP1, can transmit a signal to STA1. For example, in Figure 17, STA1 and AP1 may be included in the BSS, and STA2 and AP2 may be included in the OBSS. In other words, STA2 may be an unassociated STA to AP1, and STA1 may be an unassociated STA to AP2.

[0178] Figure 18 illustrates an example of JTX / JT. The illustrated AP1 can transmit to STA1 together with AP2. For example, the PPDU / signal transmitted from AP2 to STA1 may be all or part of the same as the PPDU / signal transmitted from AP1 to STA1. For example, the PPDU / signal transmitted from AP2 to STA1 may be simultaneously transmitted through the same / overlapping frequency band as the PPDU / signal transmitted from AP1 to STA1. For example, the PPDU / signal transmitted from AP2 to STA1 may be a signal transmitted from AP1 through a backhaul link. For example, in Figure 18, STA1 and AP1 may be included in a BSS, and STA2 and AP2 may be included in an OBSS. That is, STA2 may be an unassociated STA to AP1, and STA1 may be an unassociated STA to AP2.

[0179] More specifically, in FIG. 18, AP1 can transmit a coordination request (or can be named variously, such as a first request, a control request, etc.) to AP2 and receive a coordination response (or can be named variously, such as a first response, a control response, etc.) from AP2. Through the exchange of the request / response, information about coordination between AP1 and AP2 (e.g., information about whether AP1 and AP2 will perform simultaneous transmission to STA1), information about the point in time when coordination starts, information about the point in time when AP1 and AP2 start simultaneous transmission to STA1, information about data shared between AP1 and AP2, etc. can be exchanged. AP1 can share its data with AP2 via the backhaul link. Thereafter, AP1 can transmit a coordination trigger frame (or can be named variously, such as a trigger frame) to AP2 and perform simultaneous transmission to STA1 based on the trigger frame.

[0180] <Embodiments applicable to this specification>

[0181] To enable terminals to maintain continuous WLAN connectivity over a wider area, numerous APs are being installed adjacent to each other. However, overlapping BSSs of multiple APs can lead to issues such as radio interference and transmission collisions between APs. To address these issues, various technologies have been proposed to coordinate APs across frequency, time, and spatial domains (e.g., RU selection, joint transmission, nulling, etc.). Furthermore, attention should be paid to the various issues that can arise during inter-AP cooperation.

[0182] In EHT (802.11be), a technology was proposed to allocate some time within the TXOP acquired by the AP to support peer-to-peer (P2P) transmission to non-AP STAs. To this end, a new TXOP Sharing Mode subfield was defined in the Common Info field of the existing MU-RTS Trigger frame, and the MU-RTS (Multi User-Request To Send) Trigger frame when this value is nonzero is referred to as an MU-RTS TXOP Sharing (TXS) Trigger frame (TF). If the value of the TXOP Sharing mode is 1, the non-AP STA supports one or more (non-TB) PPDU transmissions to the AP, and if the value of the TXOP Sharing mode is 2, the non-AP STA supports P2P transmission in addition to (non-TB) PPDU transmissions to the AP.

[0183] Figure 19 shows an example of the operation of a 2-day MU-RTS TXS trigger frame with a value of the TXOP Sharing Mode subfield.

[0184] Fig. 19 shows an example of operation when the TXOP Sharing mode value is 2. When the AP transmits an MU-RTS TXS TF including time allocation information (Time allocated in MU-RTS TXS Trigger Frame of Fig. 19) to non-AP STA 1, non-AP STA 1 can perform P2P transmission to non-AP STA 2 after responding with CTS (Clear-To-Send).

[0185] Figure 20 shows an example of coordinated TDMA operation.

[0186] Meanwhile, if the existing Triggered TXOP Sharing protocol is utilized for multi-AP coordination, frame exchange can be performed without affecting each other by dividing the transmission within the BSS of each cooperative AP by time unit. That is, FIG. 20 shows an example of Coordinated-Time Division Multiplexing Access (C-TDMA) according to the time unit among the cooperation methods between cooperative APs. At this time, the AP in the existing Triggered TXS protocol can play the role of an AP that shares TXOP in the multi-AP coordination operation, and the STA in the existing Triggered TXS protocol can play the role of an AP that shares TXOP in the multi-AP coordination operation. In this specification, an AP that shares TXOP is referred to as a Sharing AP (SAP), and an AP that receives TXOP from an SAP is referred to as a Shared AP (DAP). Here, the SAP that shares TXOP is not limited to only AP STAs, and may also include non-AP STAs that share TXOP. Additionally, the DAPs that share TXOPs are not limited to AP STAs, and may also include non-AP STAs that share TXOPs (or transmit and receive with AP STAs that share TXOPs). Furthermore, frame exchanges with non-AP STAs or SAPs belonging to the DAP BSS during the time allocated to the DAP are referred to as BSS frame exchanges (FEs) of the DAP.For example, frame exchange may be performed by transmitting data frames and responding to block ACK frames following RTS / CTS frame exchange between a DAP and a non-AP STA, transmitting UL data frames by non-AP STAs in response to a trigger frame transmitted from the DAP, or transmitting data frames by the DAP in response to a trigger frame transmitted from the SAP.

[0187] 1. Problem

[0188] Figure 21 illustrates an example of C-TDMA operation using two TXOPs.

[0189] To prevent the protection issue where non-AP STAs cannot transmit UL PPDU / frame to the DAP, a C-TDMA procedure can be performed in which the TXOP duration is set short by utilizing two TXOPs. That is, through the C-TDMA operation procedure as in FIG. 21, the DAP and some non-AP STAs within the BSS of the DAP can perform frame exchange with the DAP without being affected by the NAV of the SAP. For example, when the associated STAs of the DAP receive a Trigger frame from the DAP in which resources (e.g., Resource Unit (RU)) are allocated for them to transmit PPDU / frame, they can transmit PPDU / frame without being affected by the NAV that may be set by the SAP or the non-AP STA(s) associated with the SAP.

[0190] Figure 22 illustrates an example of a TXOP return failure issue by a hidden node (STA 3).

[0191] However, as shown in FIG. 22, STA 3 (e.g., AP or non-AP STA) that is in a hidden node relationship with DAP (i.e., AP 2) and does not participate in C-TDMA can determine that the medium is idle depending on what value is set in the duration field of the MU-RTS TXS TF during the period that SAP (i.e., AP 1) shared TXOP with DAP (i.e., Time allocated in MU-RTS TXS TF or TXOP Duration by Shared AP), and thus can perform channel access to occupy the medium that SAP was using. In addition, STAs that have not received a response frame for the MU-RTS TXS TF can reset the NAV and occupy the medium when the NAVTimeout period expires. In other words, even if DAP uses the time allocated from SAP and performs the TXOP return sequence, a problem may occur in which SAP cannot receive a TXOP in return because STA 3 can occupy the medium.

[0192] Therefore, this specification proposes a medium reservation method to prevent the TXOP return fail issue that may occur in a C-TDMA procedure utilizing two TXOPs.

[0193] The medium reservation method proposed in this specification can protect SAP from NAV to prevent third-party STA or OBSS STA (i.e., STA 3 in FIG. 22) from occupying the medium. For example, DAP can exchange frames for NAV-set sequence with SAP during the time allocated by SAP, thereby allowing surrounding STAs of SAP to set NAV during that time. Alternatively, SAP can transmit additional response frames during TXOP sharing to provide protection. The specific designations (names) proposed in this specification can be changed and are not limited.

[0194] 2. Medium reservation method to prevent TXOP return failure issues that may occur in the C-TDMA procedure.

[0195] This specification describes a medium reservation method to prevent TXOP return failure issues that may occur in the C-TDMA procedure. Specifically, a DAP performing a NAV-set sequence process for the time allocated from a SAP through TXOP sharing transmits an MU-RTS TXS TF or a CTS-to-Self frame (or CTS frame) to the SAP, and the SAP responds with a CTS-to-Self frame (or CTS frame) to allow neighboring STAs to set their NAVs. Alternatively, the SAP may transmit an additional CTS-to-Self frame during the TXOP sharing process.

[0196] The medium reservation method for the C-TDMA procedure according to the present disclosure means that when a SAP shares a TXOP with a DAP and then a TXOP return is performed, the TXOP return can be performed without occupying the medium by the surrounding STAs of the SAP. For example, a DAP that has shared a TXOP from a SAP can perform a NAV-set sequence through a pre-frame exchange with the SAP in order to successfully return the TXOP after an individual FE. That is, the surrounding STAs of the SAP that receive / detect the frame exchange during the NAV-set sequence process between the DAP and the SAP can defer channel access by updating or setting the NAV during the corresponding time. Alternatively, the SAP can transmit an additional frame to perform protection during the TXOP sharing process.

[0197] The medium reservation method in the C-TDMA procedure utilizing two TXOPs proposed in this specification can operate as follows.

[0198] 2.1 MU-RTS TXS TF & CTS frame exchange

[0199] Figure 23 illustrates an embodiment 1 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0200] Figure 23 illustrates an example of a medium reservation method for successful TXOP return in a C-TDMA procedure. First, APs and third-party STAs (e.g., APs or non-AP STAs, referring to STA 3 in Figure 23) participating in C-TDMA compete for a TXOP corresponding to the Basic TXOP Duration. An AP (e.g., AP 1) that acquires a TXOP and acts as an SAP includes, in the Duration / ID field, the time required for FE with STAs within its BSS and the time required for the TXOP sharing procedure (i.e., Basic TXOP Duration), rather than the Nominal TXOP Duration, which means the entire duration of the C-TDMA operation it wishes to perform. In other words, the SAP acquires a TXOP only for the period corresponding to the Basic TXOP Duration through the NAV-set sequence procedure and protects it with a NAV, and during this period, the SAP can perform FE and TXOP sharing procedures with STAs within its BSS. Alternatively, SAP can perform FE with STAs within its BSS and then perform TXOP sharing procedure by continuing frame transmission / reception at SIFS intervals without a separate NAV-set sequence procedure.

[0201] In addition, SAP can include the Nominal TXOP Duration value in the frame transmitted in the NAV-set sequence (e.g., MU-RTS TXS TF, CTS-to-Self, etc.) or the frame transmitted in the frame exchange sequence and transmit it to the cooperating AP(s) during the Basic TXOP Duration. At this time, the cooperating AP(s) include the DAP(s) that are scheduled to share TXOP according to SAP's scheduling during the Nominal TXOP Duration and the DAP(s) that are not scheduled to share TXOP. Therefore, the DAP(s) that are scheduled to share TXOP from SAP within the Nominal TXOP Duration can recognize in advance whether or not they will share through the notified Nominal TXOP Duration information. In addition, the DAP(s) that are not scheduled to share TXOP from SAP within the Nominal TXOP Duration can recognize that SAP is going to share TXOP with other DAP(s) through the notified Nominal TXOP Duration information. Subsequently, SAP can perform individual FE through frame exchange sequence procedure, and SAP that terminates individual FE can start the TXOP sharing procedure that was initially scheduled by sending MU-RTS TXS TF (or Control frame).

[0202] DAPs following Rule 1) defined below can perform NAV-set sequence procedures or individual FEs at SIFS / PIFS intervals following SAP's TXOP sharing procedure.

[0203] Rule 1) After the DAP is notified of the Nominal TXOP Duration through the frame transmitted from the SAP, it may respond with a CTS frame (or a response frame corresponding to the frame transmitted from the SAP) after receiving the MU-RTS TXS TF transmitted from the SAP (i.e., a frame transmitted for the purpose of sharing TXOP in the TXOP sharing procedure) and immediately perform the NAV-set sequence procedure or individual FE after SIFS / PIFS. Alternatively, the DAP may perform the response to the reception of the MU-RTS TXS TF and the NAV-set sequence procedure in an integrated manner using the CTS-to-Self frame after receiving the MU-RTS TXS TF transmitted from the SAP. In this case, the start point of the allocated time allocated from the SAP can be assumed to be immediately after receiving the MU-RTS TXS TF, similar to the existing EHT TXS protocol.

[0204] In this specification, in order to prevent the TXOP return fail issue due to medium contention of a third party STA that does not participate in C-TDMA, the NAV-set sequence procedure described in Rule 1) is performed through a frame exchange sequence with the SAP. First, as in Embodiment 1 of FIG. 23, after receiving the MU-RTS TXS TF (i.e., a frame transmitted for the purpose of sharing TXOP in the TXOP sharing procedure) transmitted from the SAP, a CTS frame (or a response frame corresponding to the frame transmitted from the SAP) is responded to, and after SIFS / PIFS, an MU-RTS TXS TF (i.e., a frame transmitted for the purpose of medium reservation and NAV setup) can be immediately transmitted to the SAP for the NAV-set sequence procedure.

[0205] The MU-RTS TXS TF at this time may be defined and indicated as a new mode (i.e., 3) to be used for frame exchange for the NAV-set sequence at the time allocated to the DAP, or may be signaled using reserved bits in the Common Info field or User Info field. Additionally, the unused Allocation duration field in the User Info field may be reserved.

[0206] Upon receiving this, the SAP responds with a CTS-to-Self frame (or CTS frame) to allow the surrounding STA (i.e., STA 3 in Fig. 23) to set the NAV by the CTS-to-Self frame (or CTS frame). Therefore, the SAP can also be protected from the NAV by the CTS-to-Self frame (or CTS frame) for a time corresponding to the time allocated by the SAP to the DAP (i.e., Time allocated in MU-RTS TXS TF), and can perform the NAV-set sequence procedure or individual FE after SIFS / PIFS according to Rule 3) defined below, following the TXOP return sequence procedure that can be performed by the DAP before the allocated time expires.

[0207] Rule 3) When a SAP receives a frame transmitted from a DAP within the initially set Nominal TXOP Duration (i.e., a frame transmitted for the purpose of returning a TXOP in the TXOP return procedure), it may respond with a response frame corresponding to the frame transmitted from the DAP and immediately perform the NAV-set sequence procedure or an individual FE after SIFS / PIFS. Alternatively, the SAP may integrate the response to the reception of the MU-RTS TXS TF and the NAV-set sequence procedure using the CTS-to-Self frame after receiving the MU-RTS TXS TF (for the TXOP return procedure) transmitted from the DAP. Alternatively, the SAP may immediately perform the NAV-set sequence procedure or an individual FE after SIFS / PIFS without transmitting a separate response frame after receiving a frame for the purpose of TXOP return transmitted from the DAP (e.g., CF-End frame).

[0208] 2.2 CTS-to-Self frame (or CTS frame) & CTS-to-Self frame exchange

[0209] 2.2.1 Example 2

[0210] Figure 24 illustrates an embodiment 2 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0211] In Example 2 of FIG. 24, after receiving the MU-RTS TXS TF transmitted from SAP (i.e., a frame transmitted for the purpose of sharing TXOP in a TXOP sharing procedure), a CTS-to-Self frame (or CTS frame) is transmitted to immediately perform a reception response and NAV-set sequence for the MU-RTS TXS TF.

[0212] Upon receiving this, the SAP responds with a CTS-to-Self frame (or CTS frame) to allow the neighboring STA (i.e., STA 3 in Fig. 24) to set the NAV by the CTS-to-Self frame (or CTS frame). Therefore, the SAP can also be protected from the NAV by the CTS-to-Self frame (or CTS frame) for a time corresponding to the time allocated by the SAP to the DAP (i.e., Time allocated in MU-RTS TXS TF), and can perform the NAV-set sequence procedure or individual FE after SIFS / PIFS according to Rule 3) defined below, following the TXOP return procedure that can be performed by the DAP before the allocated time expires.

[0213] Rule 3) When a SAP receives a frame transmitted from a DAP within the initially set Nominal TXOP Duration (i.e., a frame transmitted for the purpose of returning a TXOP in the TXOP return procedure), it may respond with a response frame corresponding to the frame transmitted from the DAP and immediately perform the NAV-set sequence procedure or an individual FE after SIFS / PIFS. Alternatively, the SAP may integrate the response to the reception of the MU-RTS TXS TF and the NAV-set sequence procedure using the CTS-to-Self frame after receiving the MU-RTS TXS TF (for the TXOP return procedure) transmitted from the DAP. Alternatively, the SAP may immediately perform the NAV-set sequence procedure or an individual FE after SIFS / PIFS without transmitting a separate response frame after receiving a frame for the purpose of TXOP return transmitted from the DAP (e.g., CF-End frame).

[0214] 2.2.2 Example 3

[0215] Figure 25 illustrates an embodiment 3 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0216] In Embodiment 3 of FIG. 25, similarly to Embodiment 2, after receiving the MU-RTS TXS TF transmitted from the SAP, a CTS-to-Self frame (or CTS frame) may be transmitted in response. In Embodiment 3, it is assumed that the duration field of the MU-RTS TXS TF transmitted by the SAP includes an allocation duration value, which is a time to be allocated to the DAP. STAs that receive an MU-RTS TXS TF including an allocation duration value in the Duration field may update an existing NAV (i.e., in the case of STA 3) or set a new NAV. An SAP that receives a CTS-to-Self frame (or CTS frame), which is a response frame to the MU-RTS TXS TF, may additionally respond with a CTS-to-Self frame (or CTS frame) to prevent a NAV timeout issue.

[0217] Specifically, an STA that uses the information in the MU-RTS TXS TF to update the most recent NAV setting is allowed to reset its NAV if it receives the MU-RTS TXS TF transmitted from AP 1 and does not receive the PHY-RXEARLYSIG.indication or PHY-RXSTART.indication primitive from the PHY during the NAVTimeout period for the MU-RTS TXS TF. That is, a specific STA that is in a hidden node relationship with AP 2 may reset its NAV and perform a random backoff when the NAVTimeout expires because it does not hear the CTS frame for the MU-RTS TXS TF from AP 1, which may cause an issue of occupying the medium.

[0218] Therefore, an STA that receives a CTS-to-Self frame (or CTS frame) additionally transmitted by SAP can update the NAVTimer before the NAVTimeout period expires and defer channel access for that duration.

[0219] In addition, there are several methods to prevent and mitigate NAVTimeout issues. These are based on adding new signaling bits to the MU-RTS TXS TF that SAP transmits for TXOP sharing. The options described below are not applicable to legacy STAs and can only be interpreted by STAs with UHR or higher.

[0220] Option 1) A new signaling bit can indicate that the SAP will transmit a CTS-to-Self frame (or CTS) within a certain time following the MU-RTS TXS TF transmission. An example of this is as follows:

[0221] -> More CTS (bit): Indicates that a CTS frame (or CTS-to-Self) will be transmitted within a certain time. For example, this utilizes the EHT Reserved (7 bits) or Reserved (4 bits) in the Common Info field. Specifically, a new field is defined to indicate that a CTS frame (or CTS-to-Self) will be transmitted using 1 bit corresponding to EHT Reserved or Reserved.

[0222] bit 0: Indicates that a CTS frame (or CTS-to-Self) will not be transmitted following the transmission of the corresponding MU-RTS TXS TF.

[0223] bit 1: Indicates that a CTS frame (or CTS-to-Self) will be transmitted following the transmission of the corresponding MU-RTS TXS TF.

[0224] Option 2) A new signaling bit can instruct an STA that has received an MU-RTS TXS TF not to reset the NAV even if it has not received a frame until the NAVTimeout period expires. An example of this is as follows.

[0225] -> NAVTimeout Disable (bit): Instructs not to reset the NAV even if the NAVTimeout period expires. For example, utilize the EHT Reserved (7 bits) or Reserved (4 bits) in the Common Info field. Specifically, define a new field to instruct not to reset the NAV even if the NAVTimeout period expires by utilizing 1 bit corresponding to EHT Reserved or Reserved.

[0226] bit 0: Instructs to reset the NAV if the NAVTimeout period expires after receiving the corresponding MU-RTS TXS TF. (default)

[0227] bit 1: Instructs not to reset the NAV even if the NAVTimeout period expires after receiving the corresponding MU-RTS TXS TF.

[0228] The SAP can also be protected for a period of time corresponding to the time allocated to the DAP via the additional CTS-to-Self frame (or CTS frame) transmitted from the SAP, and can perform the NAV-set sequence procedure or individual FE after SIFS / PIFS according to Rule 3) described above, following the TXOP return procedure that can be performed by the DAP before the allocated time expires.

[0229] 2.2.3 Example 4

[0230] Figure 26 illustrates an embodiment 4 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0231] In Embodiment 4 of FIG. 26, similarly to Embodiment 2, after the DAP receives the MU-RTS TXS TF transmitted from the SAP, it may respond by transmitting a CTS-to-Self frame (or CTS frame). In Embodiment 4, it is assumed that the duration field of the MU-RTS TXS TF transmitted by the SAP includes the remaining Nominal TXOP Duration value excluding the Basic TXOP Duration acquired by the initial SAP within the Nominal TXOP Duration for the entire C-TDMA operation (i.e., Nominal TXOP Duration - the first Basic TXOP Duration of the SAP). In the case where additional TXOP sharing is performed with another DAP following the first TXOP sharing for AP 2 within the Nominal TXOP Duration (i.e., when considering the Multiple DAPs support scenario), the duration value until the TXOP sharing time scheduled for the subsequent DAP may be included.

[0232] STAs that receive an MU-RTS TXS TF with a remaining Nominal TXOP Duration value in the Duration field can update the existing NAV (i.e., in the case of STA 3) or set a new NAV. An SAP that receives a CTS-to-Self frame (or CTS frame), which is a response frame to the MU-RTS TXS TF, can additionally respond with a CTS-to-Self frame (or CTS frame) to prevent a NAV timeout issue.

[0233] Specifically, an STA that uses the information in the MU-RTS TXS TF to update the most recent NAV setting is allowed to reset its NAV if it receives the MU-RTS TXS TF transmitted from AP 1 and does not receive the PHY-RXEARLYSIG.indication or PHY-RXSTART.indication primitive from the PHY during the NAVTimeout period for the MU-RTS TXS TF. That is, a specific STA that is in a hidden node relationship with AP 2 may reset its NAV and perform a random backoff when the NAVTimeout expires because it does not hear the CTS frame for the MU-RTS TXS TF from AP 1, which may cause an issue of occupying the medium.

[0234] Therefore, an STA that receives a CTS-to-Self frame (or CTS frame) additionally transmitted by SAP can update the NAVTimer before the NAVTimeout period expires and defer channel access for that duration.

[0235] In addition, there may be several ways to prevent and mitigate NAVTimeout issues. These are based on adding a new signaling bit to the MU-RTS TXS TF that SAP delivers for TXOP sharing.

[0236] Option 1) A new signaling bit can indicate that the SAP will transmit a CTS-to-Self frame (or CTS) within a certain time following the MU-RTS TXS TF transmission. An example of this is as follows:

[0237] -> More CTS (bit): Indicates that a CTS frame (or CTS-to-Self) will be transmitted within a certain time. For example, this utilizes the EHT Reserved (7 bits) or Reserved (4 bits) in the Common Info field. Specifically, a new field is defined to indicate that a CTS frame (or CTS-to-Self) will be transmitted using 1 bit corresponding to EHT Reserved or Reserved.

[0238] bit 0: Indicates that a CTS frame (or CTS-to-Self) will not be transmitted following the transmission of the corresponding MU-RTS TXS TF.

[0239] bit 1: Indicates that a CTS frame (or CTS-to-Self) will be transmitted following the transmission of the corresponding MU-RTS TXS TF.

[0240] Option 2) A new signaling bit can instruct an STA that has received an MU-RTS TXS TF not to reset the NAV even if it has not received a frame until the NAVTimeout period expires. An example of this is as follows.

[0241] -> NAVTimeout Disable (bit): Instructs not to reset the NAV even if the NAVTimeout period expires. For example, utilize the EHT Reserved (7 bits) or Reserved (4 bits) in the Common Info field. Specifically, define a new field to instruct not to reset the NAV even if the NAVTimeout period expires by utilizing 1 bit corresponding to EHT Reserved or Reserved.

[0242] bit 0: Instructs to reset the NAV if the NAVTimeout period expires after receiving the corresponding MU-RTS TXS TF. (default)

[0243] bit 1: Instructs not to reset the NAV even if the NAVTimeout period expires after receiving the corresponding MU-RTS TXS TF.

[0244] The SAP can also be protected for a period of time corresponding to the time allocated to the DAP via the additional CTS-to-Self frame (or CTS frame) transmitted from the SAP, and can perform individual FEs after SIFS / PIFS according to Rule 3) described above, following the TXOP return procedure that can be performed by the DAP before the allocated time expires.

[0245] 2.2.4 Example 5

[0246] Figure 27 illustrates an embodiment 5 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0247] In Example 5 of FIG. 27, similarly to Example 2, the DAP may respond by transmitting a CTS (or CTS-to-Self frame) after receiving the MU-RTS TXS TF transmitted from the SAP. In Example 5, it is assumed that the duration field of the MU-RTS TXS TF transmitted by the SAP includes the time required to receive the CTS frame (or CTS-to-Self frame) transmitted from the DAP. Some STAs that receive the MU-RTS TXS TF may update the existing NAV or set a new NAV. An SAP that receives a CTS frame (or CTS-to-Self frame), which is a response frame to the MU-RTS TXS TF, may additionally respond with a CTS-to-Self frame (or CTS frame). The duration field of the CTS-to-Self frame (or CTS frame) transmitted by SAP may contain a value corresponding to the allocation duration allocated to the DAP, and the NAV timeout issue can be prevented through the transmission of the CTS-to-Self frame (or CTS frame) from SAP.

[0248] Specifically, the duration field can contain the following values, depending on when the time allocated to the DAP by SAP begins:

[0249] The duration field of the CTS-to-Self frame (or CTS frame) transmitted by SAP can be set as follows (*excluding the PPDU length of the frame);

[0250] i) Assuming that the allocated time starts immediately after the MU-RTS TXS TF transmission:

[0251] duration field = {(Allocation duration) - (2×SIFS) - (CTS_Time)}

[0252] ii) Assuming that the allocated time starts immediately after receiving the CTS frame (or CTS-to-Self frame) from the DAP:

[0253] duration field = {(Allocation duration) - (SIFS)}

[0254] iii) Assuming that the time allocated by SAP starts when it sends the CTS-to-Self frame (or CTS frame):

[0255] duration field = Allocation duration

[0256] The duration field of the frame for the NAV-set sequence transmitted by the DAP can be set as follows (*excluding the PPDU length of the frame);

[0257] i) Assuming that the allocated time starts immediately after receiving the MU-RTS TXS TF:

[0258] duration field = {(Allocation duration) - (3×SIFS) - (2×CTS_Time)}

[0259] ii) Assuming that the allocated time starts immediately after the DAP transmits the CTS frame (or CTS-to-Self frame):

[0260] duration field = {(Allocation duration) - (2×SIFS) - (CTS_Time)}

[0261] iii) Assuming that the allocated time starts immediately after receiving the CTS-to-Self frame (or CTS frame) from SAP:

[0262] duration field = {(Allocation duration} - (SIFS)}

[0263] Specifically, an STA that uses the information in the MU-RTS TXS TF to update the most recent NAV setting is allowed to reset its NAV if it receives the MU-RTS TXS TF transmitted from AP 1 and does not receive the PHY-RXEARLYSIG.indication or PHY-RXSTART.indication primitive from the PHY during the NAVTimeout period for the MU-RTS TXS TF. That is, a specific STA that is in a hidden node relationship with AP 2 may reset its NAV and perform a random backoff when the NAVTimeout expires because it does not hear the CTS frame for the MU-RTS TXS TF from AP 1, which may cause an issue of occupying the medium.

[0264] Therefore, an STA that receives a CTS-to-Self frame (or CTS frame) additionally transmitted by SAP can update the NAVTimer before the NAVTimeout period expires and defer channel access for that duration.

[0265] In addition, there may be several ways to prevent and mitigate NAVTimeout issues. These are based on adding a new signaling bit to the MU-RTS TXS TF that SAP delivers for TXOP sharing.

[0266] Option 1) A new signaling bit can indicate that the SAP will transmit a CTS-to-Self frame (or CTS) within a certain time following the MU-RTS TXS TF transmission. An example of this is as follows:

[0267] -> More CTS (bit): Indicates that a CTS frame (or CTS-to-Self) will be transmitted within a certain time. For example, this utilizes the EHT Reserved (7 bits) or Reserved (4 bits) in the Common Info field. Specifically, a new field is defined to indicate that a CTS frame (or CTS-to-Self) will be transmitted using 1 bit corresponding to EHT Reserved or Reserved.

[0268] bit 0: Indicates that a CTS frame (or CTS-to-Self) will not be transmitted following the transmission of the corresponding MU-RTS TXS TF.

[0269] bit 1: Indicates that a CTS frame (or CTS-to-Self) will be transmitted following the transmission of the corresponding MU-RTS TXS TF.

[0270] Option 2) A new signaling bit can instruct an STA that has received an MU-RTS TXS TF not to reset the NAV even if it has not received a frame until the NAVTimeout period expires. An example of this is as follows.

[0271] -> NAVTimeout Disable (bit): Instructs not to reset the NAV even if the NAVTimeout period expires. For example, utilize the EHT Reserved (7 bits) or Reserved (4 bits) in the Common Info field. Specifically, define a new field to instruct not to reset the NAV even if the NAVTimeout period expires by utilizing 1 bit corresponding to EHT Reserved or Reserved.

[0272] bit 0: Instructs to reset the NAV if the NAVTimeout period expires after receiving the corresponding MU-RTS TXS TF. (default)

[0273] bit 1: Instructs not to reset the NAV even if the NAVTimeout period expires after receiving the corresponding MU-RTS TXS TF.

[0274] The SAP can also be protected for a period of time corresponding to the time allocated to the DAP via the additional CTS-to-Self frame (or CTS frame) transmitted from the SAP, and can perform the NAV-set sequence procedure or individual FE after SIFS / PIFS according to Rule 3) described above, following the TXOP return procedure that can be performed by the DAP before the allocated time expires.

[0275] 2.2.5 Example 6

[0276] Figure 28 illustrates an embodiment 6 of a medium reservation method for TXOP return in a C-TDMA procedure.

[0277] In Example 6 of FIG. 28, similarly to Example 2, the DAP may respond by transmitting a CTS frame (or CTS-to-Self frame) after receiving the MU-RTS TXS TF transmitted from the SAP. In Example 6, it is assumed that the duration field of the MU-RTS TXS TF transmitted by the SAP includes the time required to transmit an additional CTS-to-Self frame (or CTS frame) after receiving the CTS frame (or CTS-to-Self frame). Some STAs that receive the MU-RTS TXS TF may update the existing NAV or set a new NAV. An SAP that receives a CTS frame (or CTS-to-Self frame), which is a response frame to the MU-RTS TXS TF, may additionally respond with a CTS-to-Self frame (or CTS frame). The duration field of the CTS-to-Self frame (or CTS frame) may contain a value corresponding to the allocation duration allocated to the DAP, and the NAV timeout issue can be prevented through the transmission of the CTS-to-Self frame (or CTS frame) from the SAP.

[0278] Specifically, the duration field can contain the following values, depending on when the time allocated to the DAP by SAP begins:

[0279] From the SAP perspective, the duration field of the CTS frame can be set as follows (*excluding the PPDU length of the CTS frame);

[0280] The duration field of the CTS-to-Self frame (or CTS frame) transmitted by SAP can be set as follows (*excluding the PPDU length of the frame);

[0281] i) Assuming that the allocated time starts immediately after the MU-RTS TXS TF transmission:

[0282] duration field = {(Allocation duration) - (2×SIFS) - (CTS_Time)}

[0283] ii) Assuming that the allocated time starts immediately after receiving the CTS frame (or CTS-to-Self frame) from the DAP:

[0284] duration field = {(Allocation duration) - (SIFS)}

[0285] iii) Assuming that the time allocated by SAP starts when it sends the CTS-to-Self frame (or CTS frame):

[0286] duration field = Allocation duration

[0287] The duration field of the frame for the NAV-set sequence transmitted by the DAP can be set as follows (*excluding the PPDU length of the frame);

[0288] i) Assuming that the allocated time starts immediately after receiving the MU-RTS TXS TF:

[0289] duration field = {(Allocation duration) - (3×SIFS) - (2×CTS_Time)}

[0290] ii) Assuming that the allocated time starts immediately after the DAP transmits the CTS frame (or CTS-to-Self frame):

[0291] duration field = {(Allocation duration) - (2×SIFS) - (CTS_Time)}

[0292] iii) Assuming that the allocated time starts immediately after receiving the CTS-to-Self frame (or CTS frame) from SAP:

[0293] duration field = {(Allocation duration} - (SIFS)}

[0294] Specifically, an STA that uses the information in the MU-RTS TXS TF to update the most recent NAV setting is allowed to reset its NAV if it receives the MU-RTS TXS TF transmitted from AP 1 and does not receive the PHY-RXEARLYSIG.indication or PHY-RXSTART.indication primitive from the PHY during the NAVTimeout period for the MU-RTS TXS TF. That is, a specific STA that is in a hidden node relationship with AP 2 may reset its NAV and perform a random backoff when the NAVTimeout expires because it does not hear the CTS frame for the MU-RTS TXS TF from AP 1, which may cause an issue of occupying the medium.

[0295] Therefore, an STA that receives a CTS-to-Self frame (or CTS frame) additionally transmitted by SAP can update the NAVTimer before the NAVTimeout period expires and defer channel access for that duration.

[0296] In addition, there may be several ways to prevent and mitigate NAVTimeout issues. These are based on adding a new signaling bit to the MU-RTS TXS TF that SAP delivers for TXOP sharing.

[0297] Option 1) A new signaling bit can indicate that the SAP will transmit a CTS-to-Self frame (or CTS) within a certain time following the MU-RTS TXS TF transmission. An example of this is as follows:

[0298] -> More CTS (bit): Indicates that a CTS frame (or CTS-to-Self) will be transmitted within a certain time. For example, this utilizes the EHT Reserved (7 bits) or Reserved (4 bits) in the Common Info field. Specifically, a new field is defined to indicate that a CTS frame (or CTS-to-Self) will be transmitted using 1 bit corresponding to EHT Reserved or Reserved.

[0299] bit 0: Indicates that a CTS frame (or CTS-to-Self) will not be transmitted following the transmission of the corresponding MU-RTS TXS TF.

[0300] bit 1: Indicates that a CTS frame (or CTS-to-Self) will be transmitted following the transmission of the corresponding MU-RTS TXS TF.

[0301] Option 2) A new signaling bit can instruct an STA that has received an MU-RTS TXS TF not to reset the NAV even if it has not received a frame until the NAVTimeout period expires. An example of this is as follows.

[0302] -> NAVTimeout Disable (bit): Instructs not to reset the NAV even if the NAVTimeout period expires. For example, utilize the EHT Reserved (7 bits) or Reserved (4 bits) in the Common Info field. Specifically, define a new field to instruct not to reset the NAV even if the NAVTimeout period expires by utilizing 1 bit corresponding to EHT Reserved or Reserved.

[0303] bit 0: Instructs to reset the NAV if the NAVTimeout period expires after receiving the corresponding MU-RTS TXS TF. (default)

[0304] bit 1: Instructs not to reset the NAV even if the NAVTimeout period expires after receiving the corresponding MU-RTS TXS TF.

[0305] The SAP can also be protected for a period of time corresponding to the time allocated to the DAP via the additional CTS-to-Self frame (or CTS frame) transmitted from the SAP, and can perform the NAV-set sequence procedure or individual FE after SIFS / PIFS according to Rule 3) described above, following the TXOP return procedure that can be performed by the DAP before the allocated time expires.

[0306] On the other hand, the medium reservation procedure for C-TDMA presented in this specification may be omitted in the following situations. Conditions and situations for which the medium reservation procedure is omitted may be added and are not limited.

[0307] i) When negotiating / configuring not to support TXOP return in the Multi-AP set configuration (i.e., negotiation for C-TDMA) procedure.

[0308] ii) If SAP instructs that TXOP return is not supported or that TXOP return does not need to be performed during the Multi-AP selection procedure.

[0309] iii) If you are instructed by SAP not to support TXOP return during the TXOP sharing procedure or that TXOP return does not need to be performed.

[0310] In this specification, we propose a medium reservation method to prevent TXOP return fail issues that may occur in a C-TDMA procedure utilizing two TXOPs. Specifically, a DAP performing a NAV-set sequence process or a TXOP sharing process transmits an MU-RTS TXS TF or a CTS-to-Self frame (or CTS frame) to a SAP, and the SAP responds with a CTS-to-Self frame (or CTS frame) to enable neighboring STAs to set NAVs. The proposed medium reservation method has the advantage that the SAP is protected by the NAV and can receive TXOPs in return.

[0311] Fig. 29 is a flowchart illustrating the operation of a transmitting device according to the present embodiment.

[0312] An example of FIG. 29 may be performed at a transmitting STA or transmitting device (AP and / or non-AP STA).

[0313] Some of the steps (or detailed sub-steps described below) in the example of Fig. 29 may be omitted or changed.

[0314] Through step S2910, the transmitting device (transmitting STA) can obtain information regarding the aforementioned Tone Plan. As described above, the information regarding the Tone Plan includes the size and location of the RU, control information related to the RU, information regarding the frequency band in which the RU is included, information regarding the STA receiving the RU, etc.

[0315] Through step S2920, the transmitting device can configure / generate a PPDU based on the acquired control information. The step of configuring / generating the PPDU may include a step of configuring / generating each field of the PPDU. That is, step S2920 may include a step of configuring an EHT-SIG field including control information regarding a Tone Plan. That is, step S2920 may include a step of configuring a field including control information indicating the size / position of the RU (e.g., an N bitmap) and / or a step of configuring a field including an identifier (e.g., an AID) of an STA receiving the RU.

[0316] Additionally, step S2920 may include a step of generating an STF / LTF sequence to be transmitted through a specific RU. The STF / LTF sequence may be generated based on a preset STF generation sequence / LTF generation sequence.

[0317] Additionally, step S2920 may include a step of generating a data field (i.e., MPDU) to be transmitted via a specific RU.

[0318] The transmitting device can transmit the PPDU configured through step S2920 to the receiving device based on step S2930.

[0319] While performing step S2930, the transmitting device may perform at least one of operations such as CSD, Spatial Mapping, IDFT / IFFT operation, and GI insertion.

[0320] A signal / field / sequence configured according to this specification can be transmitted in the form of FIG. 5.

[0321] Figure 30 is a flowchart illustrating the operation of a receiving device according to the present embodiment.

[0322] The above-described PPDU can be received according to an example of FIG. 30.

[0323] An example of FIG. 30 may be performed at a receiving STA or receiving device (AP and / or non-AP STA).

[0324] Some of the steps (or detailed sub-steps described below) in the example of Fig. 30 may be omitted.

[0325] A receiving device (receiving STA) may receive all or part of a PPDU through step S3010. The received signal may have the form of FIG. 5.

[0326] The sub-step of step S3010 can be determined based on step S2930 of Fig. 29. That is, step S3010 can perform an operation to restore the results of the CSD, Spatial Mapping, IDFT / IFFT operations, and GI insert operations applied in step S2930.

[0327] At step S3020, the receiving device can decode all or part of the PPDU. Additionally, the receiving device can obtain control information related to the Tone Plan (i.e., RU) from the decoded PPDU.

[0328] More specifically, the receiving device can decode the L-SIG and EHT-SIG of the PPDU based on the Legacy STF / LTF and obtain information included in the L-SIG and EHT SIG fields. Information regarding various Tone Plans (i.e., RUs) described herein can be included in the EHT-SIG, and the receiving STA can obtain information regarding the Tone Plan (i.e., RU) through the EHT-SIG.

[0329] In step S3030, the receiving device can decode the remaining portion of the PPDU based on the information about the Tone Plan (i.e., RU) acquired in step S3020. For example, the receiving STA can decode the STF / LTF field of the PPDU based on the information about one Plan (i.e., RU). In addition, the receiving STA can decode the data field of the PPDU based on the information about the Tone Plan (i.e., RU) and acquire the MPDU included in the data field.

[0330] Additionally, the receiving device may perform a processing operation to transmit the decoded data to a higher layer (e.g., MAC layer) through step S3030. Additionally, if the generation of a signal is instructed from the higher layer to the PHY layer in response to the data transmitted to the higher layer, a subsequent operation may be performed.

[0331] Hereinafter, the above-described embodiment will be described with reference to FIGS. 1 to 30.

[0332] FIG. 31 is a flowchart illustrating a procedure of a method for performing C-TDMA operation by transmitting an additional CTS frame on the Sharing AP side according to the present embodiment.

[0333] An example of FIG. 31 can be performed in a network environment that supports a next-generation wireless LAN system (UHR (Ultra High Reliability) wireless LAN system or next wi-fi). The next-generation wireless LAN system is a wireless LAN system that improves on the 802.11be system and can satisfy backward compatibility with the 802.11be system.

[0334] An example of FIG. 31 is performed in a second AP, wherein the second AP may be set as a shared AP (SAP) after negotiation in multi-AP communication, and the first AP may be set as a shared AP (DAP) after negotiation in multi-AP communication. The first and second non-AP STAs of the present embodiment may correspond to at least one STA (station).

[0335] The present embodiment proposes a method for protecting SAP by setting NAV to prevent a third party STA or an Overlapping Basic Service Set (OBSS) STA from occupying the medium by transmitting an additional CTS frame when performing C-TDMA operation in multi-AP (Access Point) communication (or multi-AP operation). In particular, the present embodiment proposes a method for reserving the medium to prevent a TXOP return fail issue by setting the NAV.

[0336] In step S3110, the second AP (access point) transmits a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame to the first AP.

[0337] At step S3120, the second AP receives a first CTS (Clear to Send) frame from the first AP.

[0338] At step S3130, the second AP transmits a second CTS frame to the first AP.

[0339] At step S3140, the second AP receives a TXOP return sequence from the first AP.

[0340] The above second AP is a Sharing AP that controls cooperation between multiple APs, and the above first AP is a Shared AP that is allocated or shared with resources from the Sharing AP.

[0341] The first CTS frame is a response frame to the MU-RTS TXS trigger frame. Based on the second CTS frame, a first NAV (Network Allocation Vector) is set for the first non-AP STA (station). Alternatively, a second NAV may be set for the first non-AP STA based on the MU-RTS TXS trigger frame, and a NAV timer may be updated before a NAV timeout period of the second NAV expires based on the second CTS frame. Alternatively, a third NAV may be set for the first non-AP STA based on the first NAV setting sequence described below, and a NAV timer may be updated before a NAV timeout period of the third NAV expires based on the second CTS frame. That is, a new NAV may be set due to the additionally transmitted second CTS frame, or a NAV timeout issue of an existing NAV may be prevented, thereby withholding channel access of the first non-AP STA.

[0342] At this time, the first non-AP STA does not participate in the cooperation between the plurality of APs and is in a hidden node relationship with the first AP.

[0343] The technique for cooperation between the above multiple APs may include a coordinated multi-AP technique such as C-TDMA (Coordinated-Time Division Multiplexing Access), C-SR (Coordinated-Spatial Reuse), C-BF (Coordinated-beamforming), or C-OFMA (Coordinated-Orthogonal Frequency Division Multiple Access).

[0344] In an example of C-TDMA operation, an entity sharing a TXOP (SAP, here a second AP) and an entity sharing a TXOP (DAP, here a first AP) are APs with different BSSs. However, an STA (third party STA or OBSS STA, here a first non-AP STA) that has a hidden node relationship with the DAP and does not participate in the C-TDMA operation can determine that the medium is idle during the period in which the TXOP is shared with the SAP DAP, and thus can perform channel access to occupy the medium used by the SAP. In addition, if the third party STA or OBSS STA does not receive a response frame to the MU-RTS TXS trigger frame, the NAV timeout period due to the MU-RTS TXS trigger frame expires, and the NAV can be reset to occupy the medium. That is, even if DAP performs TXOP return using the time allocated from SAP, a problem may occur in which SAP cannot receive TXOP return because the third party STA or OBSS STA may occupy the medium.

[0345] Therefore, the present embodiment proposes a method for reserving medium to ensure that the SAP can receive a TXOP in an environment performing C-TDMA. Specifically, the present invention proposes a method for protecting the SAP by transmitting an additional CTS frame (the second CTS frame) to set a NAV (the first NAV) to prevent the third party STA or OBSS STA from occupying the medium.

[0346] That is, this embodiment proposes a medium reservation method to prevent a TXOP return fail issue that may occur in a C-TDMA procedure utilizing multiple TXOPs. The medium reservation method proposed in this embodiment has the effect that the SAP can be protected from NAV to prevent a third-party STA or OBSS STA (the first non-AP STA) from occupying the medium. For example, the DAP can perform a frame exchange for a NAV-set sequence with the SAP during the time allocated from the SAP, thereby allowing the surrounding STAs of the SAP to set the NAV during that time. This has the effect that appropriate scheduling can be performed according to cooperation between multiple APs, and an increase in the overall network throughput can be expected.

[0347] The time at which the first NAV expires may be determined based on the value of the Allocation Duration subfield of the User Info field of the MU-RTS TXS trigger frame. The first non-AP STA may withhold channel access during the period in which the first NAV is set. The TXOP return sequence may be transmitted before the first NAV expires.

[0348] Since the first non-AP STA cannot perform channel access due to the first NAV until the TXOP return sequence is transmitted, the TXOP return from the DAP to the SAP based on the TXOP return sequence can always be guaranteed.

[0349] Additionally, the present embodiment can propose a method to prevent and compensate for NAV timeout issues by adding a new signaling bit within the MU-RTS TXS trigger frame.

[0350] Specifically, the MU-RTS TXS trigger frame may include first and second bits. The first bit may include information indicating that the second AP will transmit the second CTS frame within a certain time following transmission of the MU-RTS TXS trigger frame. The second bit may include information indicating not to reset the NAV timeout period of the second NAV set for the first non-AP STA based on the MU-RTS TXS trigger frame even if it expires.

[0351] The first and second bits may be set using the EHT (Extremely High Throughput) Reserved bit or the Reserved bit of the Common Info field of the MU-RTS TXS trigger frame.

[0352] For example, if the first bit is set to 0, the first bit may indicate that the second AP does not intend to transmit the second CTS frame within a certain period of time following transmission of the MU-RTS TXS trigger frame. If the first bit is set to 1, the first bit may indicate that the second AP intends to transmit the second CTS frame within a certain period of time following transmission of the MU-RTS TXS trigger frame.

[0353] For example, when the second bit is set to 0, the second bit may instruct to reset even if the NAV timeout period of the second NAV set for the first non-AP STA based on the MU-RTS TXS trigger frame expires. When the second bit is set to 1, the second bit may instruct not to reset even if the NAV timeout period of the second NAV set for the first non-AP STA expires based on the MU-RTS TXS trigger frame.

[0354] In order to prevent and compensate for the timeout issue of the above second NAV, it is preferable that both the first and second bits are set to 1.

[0355] The first AP may receive notification information about the first TXOP from the second AP. The first AP may determine whether to share the TXOP according to the MU-RTS TXS trigger frame based on the notification information about the first TXOP.

[0356] The above first TXOP may be the entire section including the second to fourth TXOPs in which the first and second APs participating in the cooperation between the plurality of APs individually exchange frames. The first TXOP may be defined as a nominal TXOP scheduled by the Sharing AP for C-TDMA operation.

[0357] The second AP may transmit a first NAV configuration sequence to a second non-AP STA during the second TXOP. At this time, the second non-AP STA may be a non-AP STA within a BSS (Basic Service Set) of the second AP.

[0358] A third NAV may be set for the first non-AP STA based on the first NAV setting sequence. The time at which the third NAV expires and the time at which the second TXOP ends may be determined based on the value of the Duration or ID (Identifier) ​​field of the first NAV setting sequence.

[0359] The above first CTS frame can be transmitted after the MU-RTS TXS trigger frame is received and after a SIFS (Short Inter Frame Space) or PIFS (PCF (Point Coordination Function) IFS).

[0360] Starting from the transmission of the first CTS frame, the second TXOP may be switched to the third TXOP. The second TXOP may be a TXOP acquired by the second AP, and the third TXOP may be a TXOP acquired by the first AP.

[0361] Additionally, the present embodiment describes a procedure for returning a TXOP holder from a DAP back to a SAP by having the DAP transmit the TXOP return sequence.

[0362] Starting from the transmission of the TXOP return sequence, the third TXOP may be switched to the fourth TXOP. The fourth TXOP is a remaining TXOP that the second AP acquires again and may not exceed the period of the first TXOP. This is because the first TXOP corresponds to the entire TXOP for cooperation between the plurality of APs. The time point at which the third TXOP ends may be determined based on the value of the Allocation Duration subfield of the User Info field of the MU-RTS TXS trigger frame. The time point at which the third TXOP ends and the time point at which the first NAV expires may be the same.

[0363] The second AP may receive the TXOP return sequence and transmit a second NAV configuration sequence to the second non-AP STA after SIFS or PIFS. Here, the fourth TXOP may be initiated from the transmission of the second NAV configuration sequence.

[0364] The first and second CTS frames may be general CTS frames or CTS-to-Self frames. If the first and second CTS frames are CTS-to-Self frames, the reception response and NAV setting sequence for the MU-RTS TXS trigger frame may be transmitted and received immediately (not after SIFS or PIFS).

[0365] FIG. 32 is a flowchart illustrating a procedure of a method for performing C-TDMA operation by receiving an additional CTS frame on the Shared AP side according to the present embodiment.

[0366] An example of FIG. 32 can be performed in a network environment that supports a next-generation wireless LAN system (UHR (Ultra High Reliability) wireless LAN system or next wi-fi). The next-generation wireless LAN system is a wireless LAN system that improves on the 802.11be system and can satisfy backward compatibility with the 802.11be system.

[0367] An example of FIG. 32 is performed in a first AP, wherein the first AP may be set as a shared AP (DAP) after negotiation in multi-AP communication, and the second AP may be set as a shared AP (SAP) after negotiation in multi-AP communication. The first and second non-AP STAs of the present embodiment may correspond to at least one STA (station).

[0368] The present embodiment proposes a method for protecting SAP by setting NAV to prevent a third party STA or an Overlapping Basic Service Set (OBSS) STA from occupying the medium by transmitting an additional CTS frame when performing C-TDMA operation in multi-AP (Access Point) communication (or multi-AP operation). In particular, the present embodiment proposes a method for reserving the medium to prevent a TXOP return fail issue by setting the NAV.

[0369] At step S3210, the first AP (access point) receives a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame from the second AP.

[0370] At step S3220, the first AP transmits a first CTS (Clear to Send) frame to the second AP.

[0371] At step S3230, the first AP receives a second CTS frame from the second AP.

[0372] At step S3240, the first AP transmits a TXOP return sequence to the second AP.

[0373] The above second AP is a Sharing AP that controls cooperation between multiple APs, and the above first AP is a Shared AP that is allocated or shared with resources from the Sharing AP.

[0374] The first CTS frame is a response frame to the MU-RTS TXS trigger frame. Based on the second CTS frame, a first NAV (Network Allocation Vector) is set for the first non-AP STA (station). Alternatively, a second NAV may be set for the first non-AP STA based on the MU-RTS TXS trigger frame, and a NAV timer may be updated before a NAV timeout period of the second NAV expires based on the second CTS frame. Alternatively, a third NAV may be set for the first non-AP STA based on the first NAV setting sequence described below, and a NAV timer may be updated before a NAV timeout period of the third NAV expires based on the second CTS frame. That is, a new NAV may be set due to the additionally transmitted second CTS frame, or a NAV timeout issue of an existing NAV may be prevented, thereby withholding channel access of the first non-AP STA.

[0375] At this time, the first non-AP STA does not participate in the cooperation between the plurality of APs and is in a hidden node relationship with the first AP.

[0376] The technique for cooperation between the above multiple APs may include a coordinated multi-AP technique such as C-TDMA (Coordinated-Time Division Multiplexing Access), C-SR (Coordinated-Spatial Reuse), C-BF (Coordinated-beamforming), or C-OFMA (Coordinated-Orthogonal Frequency Division Multiple Access).

[0377] In an example of C-TDMA operation, an entity sharing a TXOP (SAP, here a second AP) and an entity sharing a TXOP (DAP, here a first AP) are APs with different BSSs. However, an STA (third party STA or OBSS STA, here a first non-AP STA) that has a hidden node relationship with the DAP and does not participate in the C-TDMA operation can determine that the medium is idle during the period in which the TXOP is shared with the SAP DAP, and thus can perform channel access to occupy the medium used by the SAP. In addition, if the third party STA or OBSS STA does not receive a response frame to the MU-RTS TXS trigger frame, the NAV timeout period due to the MU-RTS TXS trigger frame expires, and the NAV can be reset to occupy the medium. That is, even if DAP performs TXOP return using the time allocated from SAP, a problem may occur in which SAP cannot receive TXOP return because the third party STA or OBSS STA may occupy the medium.

[0378] Therefore, the present embodiment proposes a method for reserving medium to ensure that the SAP can receive a TXOP in an environment performing C-TDMA. Specifically, the present invention proposes a method for protecting the SAP by transmitting an additional CTS frame (the second CTS frame) to set a NAV (the first NAV) to prevent the third party STA or OBSS STA from occupying the medium.

[0379] That is, this embodiment proposes a medium reservation method to prevent a TXOP return fail issue that may occur in a C-TDMA procedure utilizing multiple TXOPs. The medium reservation method proposed in this embodiment has the effect that the SAP can be protected from NAV to prevent a third-party STA or OBSS STA (the first non-AP STA) from occupying the medium. For example, the DAP can perform a frame exchange for a NAV-set sequence with the SAP during the time allocated from the SAP, thereby allowing the surrounding STAs of the SAP to set the NAV during that time. This has the effect that appropriate scheduling can be performed according to cooperation between multiple APs, and an increase in the overall network throughput can be expected.

[0380] The time at which the first NAV expires may be determined based on the value of the Allocation Duration subfield of the User Info field of the MU-RTS TXS trigger frame. The first non-AP STA may withhold channel access during the period in which the first NAV is set. The TXOP return sequence may be transmitted before the first NAV expires.

[0381] Since the first non-AP STA cannot perform channel access due to the first NAV until the TXOP return sequence is transmitted, the TXOP return from the DAP to the SAP based on the TXOP return sequence can always be guaranteed.

[0382] Additionally, the present embodiment can propose a method to prevent and compensate for NAV timeout issues by adding a new signaling bit within the MU-RTS TXS trigger frame.

[0383] Specifically, the MU-RTS TXS trigger frame may include first and second bits. The first bit may include information indicating that the second AP will transmit the second CTS frame within a certain time following transmission of the MU-RTS TXS trigger frame. The second bit may include information indicating not to reset the NAV timeout period of the second NAV set for the first non-AP STA based on the MU-RTS TXS trigger frame even if it expires.

[0384] The first and second bits may be set using the EHT (Extremely High Throughput) Reserved bit or the Reserved bit of the Common Info field of the MU-RTS TXS trigger frame.

[0385] For example, if the first bit is set to 0, the first bit may indicate that the second AP does not intend to transmit the second CTS frame within a certain period of time following transmission of the MU-RTS TXS trigger frame. If the first bit is set to 1, the first bit may indicate that the second AP intends to transmit the second CTS frame within a certain period of time following transmission of the MU-RTS TXS trigger frame.

[0386] For example, when the second bit is set to 0, the second bit may instruct to reset even if the NAV timeout period of the second NAV set for the first non-AP STA based on the MU-RTS TXS trigger frame expires. When the second bit is set to 1, the second bit may instruct not to reset even if the NAV timeout period of the second NAV set for the first non-AP STA expires based on the MU-RTS TXS trigger frame.

[0387] In order to prevent and compensate for the timeout issue of the above second NAV, it is preferable that both the first and second bits are set to 1.

[0388] The first AP may receive notification information about the first TXOP from the second AP. The first AP may determine whether to share the TXOP according to the MU-RTS TXS trigger frame based on the notification information about the first TXOP.

[0389] The above first TXOP may be the entire section including the second to fourth TXOPs in which the first and second APs participating in the cooperation between the plurality of APs individually exchange frames. The first TXOP may be defined as a nominal TXOP scheduled by the Sharing AP for C-TDMA operation.

[0390] The second AP may transmit a first NAV configuration sequence to a second non-AP STA during the second TXOP. At this time, the second non-AP STA may be a non-AP STA within a BSS (Basic Service Set) of the second AP.

[0391] A third NAV may be set for the first non-AP STA based on the first NAV setting sequence. The time at which the third NAV expires and the time at which the second TXOP ends may be determined based on the value of the Duration or ID (Identifier) ​​field of the first NAV setting sequence.

[0392] The above first CTS frame can be transmitted after the MU-RTS TXS trigger frame is received and after a SIFS (Short Inter Frame Space) or PIFS (PCF (Point Coordination Function) IFS).

[0393] Starting from the transmission of the first CTS frame, the second TXOP may be switched to the third TXOP. The second TXOP may be a TXOP acquired by the second AP, and the third TXOP may be a TXOP acquired by the first AP.

[0394] Additionally, the present embodiment describes a procedure for returning a TXOP holder from a DAP back to a SAP by having the DAP transmit the TXOP return sequence.

[0395] Starting from the transmission of the TXOP return sequence, the third TXOP may be switched to the fourth TXOP. The fourth TXOP is a remaining TXOP that the second AP acquires again and may not exceed the period of the first TXOP. This is because the first TXOP corresponds to the entire TXOP for cooperation between the plurality of APs. The time point at which the third TXOP ends may be determined based on the value of the Allocation Duration subfield of the User Info field of the MU-RTS TXS trigger frame. The time point at which the third TXOP ends and the time point at which the first NAV expires may be the same.

[0396] The second AP may receive the TXOP return sequence and transmit a second NAV configuration sequence to the second non-AP STA after SIFS or PIFS. Here, the fourth TXOP may be initiated from the transmission of the second NAV configuration sequence.

[0397] The first and second CTS frames may be general CTS frames or CTS-to-Self frames. If the first and second CTS frames are CTS-to-Self frames, the reception response and NAV setting sequence for the MU-RTS TXS trigger frame may be transmitted and received immediately (not after SIFS or PIFS).

[0398] <Device Configuration>

[0399] The technical features of the present specification described above can be applied to various devices and methods. For example, the technical features of the present specification described above can be performed / supported by the devices of FIG. 1 and / or FIG. 13. For example, the technical features of the present specification described above can be applied only to a part of FIG. 1 and / or FIG. 13. For example, the technical features of the present specification described above can be implemented based on the processing chip (114, 124) of FIG. 1, or based on the processor (111, 121) and the memory (112, 122) of FIG. 1, or based on the processor (610) and the memory (620) of FIG. 13. For example, the device of the present specification receives a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame from a second AP (access point); transmits a first CTS (Clear to Send) frame to the second AP; Receive a second CTS frame from the second AP; and transmit a TXOP return sequence to the second AP.

[0400] The technical features of this specification can be implemented based on a computer-readable medium (CRM). For example, the CRM proposed by this specification is at least one computer-readable recording medium containing instructions that are executed by at least one processor.

[0401] The CRM may store instructions for performing operations including the steps of: receiving a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame from a second AP (access point); transmitting a first CTS (Clear to Send) frame to the second AP; receiving a second CTS frame from the second AP; and transmitting a TXOP return sequence to the second AP. The instructions stored in the CRM of the present specification may be executed by at least one processor. At least one processor related to the CRM of the present specification may be the processor (111, 121) or the processing chip (114, 124) of FIG. 1, or the processor (610) of FIG. 13. Meanwhile, the CRM of this specification may be the memory (112, 122) of FIG. 1, the memory (620) of FIG. 13, or a separate external memory / storage medium / disk, etc.

[0402] The technical features of this specification described above are applicable to various applications and business models. For example, the technical features described above can be applied to wireless communication in devices that support artificial intelligence (AI).

[0403] Artificial intelligence (AI) is the study of artificial intelligence or the methodologies for creating it, while machine learning (ML) defines various problems in the field of AI and studies the methodologies for solving them. Machine learning is also defined as an algorithm that improves performance on a task through consistent experience.

[0404] An artificial neural network (ANN) is a model used in machine learning. It can refer to a model with problem-solving capabilities, consisting of artificial neurons (nodes) formed by the connection of synapses to form a network. An ANN can be defined by the connection patterns between neurons in different layers, the learning process that updates model parameters, and the activation function that generates output values.

[0405] An artificial neural network may include an input layer, an output layer, and optionally one or more hidden layers. Each layer contains one or more neurons, and the artificial neural network may include synapses connecting neurons. In an artificial neural network, each neuron can output a function value of an activation function based on input signals, weights, and biases received through the synapses.

[0406] Model parameters are parameters determined through learning, including synaptic connection weights and neuron biases. Hyperparameters are parameters that must be set before learning in machine learning algorithms, including the learning rate, number of iterations, mini-batch size, and initialization function.

[0407] The goal of artificial neural network training can be seen as determining model parameters that minimize a loss function. The loss function can be used as an indicator for determining optimal model parameters during the artificial neural network training process.

[0408] Machine learning can be classified into supervised learning, unsupervised learning, and reinforcement learning depending on the learning method.

[0409] Supervised learning refers to a method for training an artificial neural network when given labels for the training data. The labels can refer to the correct answer (or output value) that the artificial neural network must infer when the training data is input to the artificial neural network. Unsupervised learning can refer to a method for training an artificial neural network when the training data is not given labels. Reinforcement learning can refer to a learning method in which an agent defined within a given environment is trained to select actions or action sequences that maximize the cumulative reward in each state.

[0410] Machine learning implemented with a deep neural network (DNN) containing multiple hidden layers among artificial neural networks is also called deep learning, and deep learning is a subset of machine learning. Hereinafter, the term "machine learning" is used to encompass deep learning.

[0411] Additionally, the above-described technical features can be applied to wireless communication of robots.

[0412] A robot can be defined as a machine that automatically performs or operates a given task based on its own capabilities. Specifically, a robot capable of perceiving its environment, making independent judgments, and performing actions can be called an intelligent robot.

[0413] Robots can be categorized into industrial, medical, household, and military applications based on their intended use or field. Robots are equipped with actuators or motors, enabling them to perform various physical actions, such as moving robot joints. Furthermore, mobile robots incorporate wheels, brakes, and propellers into their actuators, enabling them to move on the ground or fly in the air.

[0414] Additionally, the above-described technical features can be applied to devices that support extended reality.

[0415] Extended reality is a general term for virtual reality (VR), augmented reality (AR), and mixed reality (MR). VR technology presents real-world objects and backgrounds as CG images only, AR technology presents virtual CG images over images of real objects, and MR technology is a computer graphics technology that blends and combines virtual objects with the real world.

[0416] MR technology is similar to AR in that it presents both real and virtual objects simultaneously. However, while AR uses virtual objects to complement real objects, MR uses virtual and real objects on an equal footing.

[0417] XR technology can be applied to HMD (Head-Mount Display), HUD (Head-Up Display), mobile phones, tablet PCs, laptops, desktops, TVs, digital signage, etc., and devices to which XR technology is applied can be called XR devices.

[0418] The claims set forth in this specification may be combined in various ways. For example, the technical features of the method claims of this specification may be combined and implemented as a device, and the technical features of the device claims of this specification may be combined and implemented as a method. Furthermore, the technical features of the method claims and the technical features of the device claims of this specification may be combined and implemented as a device, and the technical features of the method claims and the technical features of the device claims of this specification may be combined and implemented as a method.

Claims

1. In a wireless LAN system, A step in which a first AP (access point) receives a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame from a second AP; A step in which the first AP transmits a first CTS (Clear to Send) frame to the second AP; The step of the first AP receiving a second CTS frame from the second AP; and The first AP comprises a step of transmitting a TXOP return sequence to the second AP, The above second AP is a Sharing AP that controls cooperation between multiple APs, The above first AP is a Shared AP that is allocated or shared with resources from the Sharing AP, The above first CTS frame is a response frame to the MU-RTS TXS trigger frame, Based on the second CTS frame, a first NAV (Network Allocation Vector) is set for the first non-AP STA (station), and The above first non-AP STA does not participate in the cooperation between the plurality of APs and has a hidden node relationship with the first AP. method.

2. In paragraph 1, The time at which the above first NAV expires is determined based on the value of the Allocation Duration subfield of the User Info field of the MU-RTS TXS trigger frame, The first non-AP STA withholds channel access during the period in which the first NAV is set, The above TXOP return sequence is transmitted before the first NAV expires. method.

3. In paragraph 1, The above MU-RTS TXS trigger frame includes first and second bits, The first bit includes information that the second AP will transmit the second CTS frame within a certain time following transmission of the MU-RTS TXS trigger frame, The second bit includes information instructing not to reset the second NAV even if the NAV timeout period set for the first non-AP STA expires based on the MU-RTS TXS trigger frame, The first and second bits are set using the EHT (Extremely High Throughput) Reserved bit or the Reserved bit of the Common Info field of the MU-RTS TXS trigger frame. method.

4. In paragraph 2, A step in which the first AP receives notification information for the first TXOP from the second AP; and The first AP further includes a step of recognizing whether to share a TXOP according to the MU-RTS TXS trigger frame based on notification information for the first TXOP, The above first TXOP is the entire section including the second to fourth TXOPs in which the first and second APs participating in the cooperation between the plurality of APs individually perform frame exchange. method.

5. In paragraph 4, The second AP transmits the first NAV configuration sequence to the second non-AP STA during the second TXOP, The above second non-AP STA is a non-AP STA within the BSS (Basic Service Set) of the second AP, A third NAV is set for the first non-AP STA based on the first NAV setting sequence, The time at which the third NAV expires and the time at which the second TXOP ends are determined based on the value of the Duration or ID (Identifier) ​​field of the first NAV setting sequence. method.

6. In paragraph 5, The above first CTS frame is transmitted after the MU-RTS TXS trigger frame is received and after SIFS (Short Inter Frame Space) or PIFS (PCF (Point Coordination Function) IFS), Starting from the transmission of the first CTS frame, the second TXOP is switched to the third TXOP, The second TXOP is the TXOP acquired by the second AP, and the third TXOP is the TXOP acquired by the first AP. method.

7. In paragraph 6, Starting from the transmission of the above TXOP return sequence, the third TXOP is switched to the fourth TXOP, The above 4th TXOP is the remaining TXOP that the 2nd AP acquires again and does not exceed the interval of the 1st TXOP, The point in time when the third TXOP ends is determined based on the value of the Allocation Duration subfield of the User Info field of the MU-RTS TXS trigger frame. method.

8. In paragraph 7, The second AP receives the TXOP return sequence and transmits a second NAV setting sequence to the second non-AP STA after SIFS or PIFS, The above 4th TXOP starts from the transmission of the above 2nd NAV setting sequence. method.

9. In a wireless LAN system, the first AP (access point) is memory; transceiver; and A processor operatively coupled to the memory and the transceiver, the processor comprising: Receive a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame from the second AP; Transmit a first CTS (Clear to Send) frame to the second AP; Receive a second CTS frame from the second AP; and Transmit a TXOP return sequence to the second AP, The above second AP is a Sharing AP that controls cooperation between multiple APs, The above first AP is a Shared AP that is allocated or shared with resources from the Sharing AP, The above first CTS frame is a response frame to the MU-RTS TXS trigger frame, Based on the second CTS frame, a first NAV (Network Allocation Vector) is set for the first non-AP STA (station), and The above first non-AP STA does not participate in the cooperation between the plurality of APs and has a hidden node relationship with the first AP. 1st AP.

10. In a wireless LAN system, A step in which a second AP (access point) transmits a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame to the first AP; A step in which the second AP receives a first CTS (Clear to Send) frame from the first AP; The second AP transmits a second CTS frame to the first AP; and The second AP comprises a step of receiving a TXOP return sequence from the first AP, The above second AP is a Sharing AP that controls cooperation between multiple APs, The above first AP is a Shared AP that is allocated or shared with resources from the Sharing AP, The above first CTS frame is a response frame to the MU-RTS TXS trigger frame, Based on the second CTS frame, a first NAV (Network Allocation Vector) is set for the first non-AP STA (station), and The above first non-AP STA does not participate in the cooperation between the plurality of APs and has a hidden node relationship with the first AP. method.

11. In paragraph 10, The time at which the above first NAV expires is determined based on the value of the Allocation Duration subfield of the User Info field of the MU-RTS TXS trigger frame, The first non-AP STA withholds channel access during the period in which the first NAV is set, The above TXOP return sequence is transmitted before the first NAV expires. method.

12. In paragraph 10, The above MU-RTS TXS trigger frame includes first and second bits, The first bit includes information that the second AP will transmit the second CTS frame within a certain time following transmission of the MU-RTS TXS trigger frame, The second bit includes information instructing not to reset the second NAV even if the NAV timeout period set for the first non-AP STA expires based on the MU-RTS TXS trigger frame, The first and second bits are set using the EHT (Extremely High Throughput) Reserved bit or the Reserved bit of the Common Info field of the MU-RTS TXS trigger frame. method.

13. In paragraph 11, The second AP comprises a step of transmitting notification information for the first TXOP to the first AP, The first AP recognizes whether to share the TXOP according to the MU-RTS TXS trigger frame based on the notification information for the first TXOP, The above first TXOP is the entire section including the second to fourth TXOPs in which the first and second APs participating in the cooperation between the plurality of APs individually perform frame exchange. method.

14. In paragraph 13, The second AP further comprises a step of transmitting a first NAV setting sequence to a second non-AP STA during the second TXOP, The above second non-AP STA is a non-AP STA within the BSS (Basic Service Set) of the second AP, A third NAV is set for the first non-AP STA based on the first NAV setting sequence, The time at which the third NAV expires and the time at which the second TXOP ends are determined based on the value of the Duration or ID (Identifier) ​​field of the first NAV setting sequence. method.

15. In paragraph 14, The above first CTS frame is transmitted after the MU-RTS TXS trigger frame is received and after SIFS (Short Inter Frame Space) or PIFS (PCF (Point Coordination Function) IFS), Starting from the transmission of the first CTS frame, the second TXOP is switched to the third TXOP, The second TXOP is the TXOP acquired by the second AP, and the third TXOP is the TXOP acquired by the first AP. method.

16. In paragraph 15, Starting from the transmission of the above TXOP return sequence, the third TXOP is switched to the fourth TXOP, The above 4th TXOP is the remaining TXOP that the 2nd AP acquires again and does not exceed the interval of the 1st TXOP, The point in time when the third TXOP ends is determined based on the value of the Allocation Duration subfield of the User Info field of the MU-RTS TXS trigger frame. method.

17. In paragraph 16, The second AP further comprises a step of receiving the TXOP return sequence and transmitting a second NAV setting sequence to the second non-AP STA after SIFS or PIFS, The above 4th TXOP starts from the transmission of the above 2nd NAV setting sequence. method.

18. In a wireless LAN system, the second AP (access point) is memory; transceiver; and A processor operatively coupled to the memory and the transceiver, the processor comprising: Transmit a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame to the first AP; Receive a first CTS (Clear to Send) frame from the first AP; Transmitting a second CTS frame to the first AP; and Receive a TXOP return sequence from the first AP, The above second AP is a Sharing AP that controls cooperation between multiple APs, The above first AP is a Shared AP that is allocated or shared with resources from the Sharing AP, The above first CTS frame is a response frame to the MU-RTS TXS trigger frame, Based on the second CTS frame, a first NAV (Network Allocation Vector) is set for the first non-AP STA (station), and The above first non-AP STA does not participate in the cooperation between the plurality of APs and has a hidden node relationship with the first AP. 2nd AP.

19. At least one computer-readable medium containing instructions based on being executed by at least one processor, A step of receiving a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame from a second AP (access point); A step of transmitting a first CTS (Clear to Send) frame to the second AP; A step of receiving a second CTS frame from the second AP; and Including a step of transmitting a TXOP return sequence to the second AP, The above second AP is a Sharing AP that controls cooperation between multiple APs, The above first AP is a Shared AP that is allocated or shared with resources from the Sharing AP, The above first CTS frame is a response frame to the MU-RTS TXS trigger frame, Based on the second CTS frame, a first NAV (Network Allocation Vector) is set for the first non-AP STA (station), and The above first non-AP STA does not participate in the cooperation between the plurality of APs and has a hidden node relationship with the first AP. Recording medium.

20. In a wireless LAN system, in the device, memory; and A processor operatively coupled to the memory, the processor comprising: Receive a MU-RTS (Multi User-Request to Send) TXS (TXOP (Transmit Opportunity) sharing) trigger frame from the second AP (access point); Transmit a first CTS (Clear to Send) frame to the second AP; Receive a second CTS frame from the second AP; and Transmit a TXOP return sequence to the second AP, The above second AP is a Sharing AP that controls cooperation between multiple APs, The above first AP is a Shared AP that is allocated or shared with resources from the Sharing AP, The above first CTS frame is a response frame to the MU-RTS TXS trigger frame, Based on the second CTS frame, a first NAV (Network Allocation Vector) is set for the first non-AP STA (station), and The above first non-AP STA does not participate in the cooperation between the plurality of APs and has a hidden node relationship with the first AP. device.

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